CN116498984A

CN116498984A - Boiler flue gas waste heat recycling system and boiler flue gas waste heat recycling method

Info

Publication number: CN116498984A
Application number: CN202210788972.6A
Authority: CN
Inventors: 郭启刚
Original assignee: Individual
Current assignee: Individual
Priority date: 2022-01-21
Filing date: 2022-07-06
Publication date: 2023-07-28

Abstract

A boiler flue gas waste heat recycling system and a boiler flue gas waste heat recycling method. The boiler flue gas waste heat recovery utilizes system includes: boiler, bypass economizer, air preheater, flue heat exchanger, desulfurizing tower, chimney, forced draught blower and air supply heater. The system can realize the efficient recovery and the efficient utilization of the flue gas waste heat.

Description

Boiler flue gas waste heat recycling system and boiler flue gas waste heat recycling method

Technical Field

The invention relates to a boiler flue gas waste heat recycling system and a boiler flue gas waste heat recycling method.

Background

In a conventional boiler system, fuel is combusted by a boiler to form flue gas which is discharged out of a hearth, and the flue gas is discharged into the atmosphere through a chimney after passing through an air preheater, a dust remover, an induced draft fan and a desulfurizing tower in sequence. The saturated flue gas at the outlet of the desulfurizing tower has a large amount of heat energy, and the saturated flue gas discharged into the atmosphere not only can cause a large amount of heat energy waste, but also can cause environmental pollution. The saturated flue gas temperature at the outlet of the desulfurizing tower is lower, the heat energy quality is lower, the recovery efficiency is lower, and the recovered heat energy utilization value and the utilization efficiency are lower because the heat energy quality is low.

Disclosure of Invention

In order to solve the problems, the invention provides a boiler flue gas waste heat recycling system.

The boiler flue gas waste heat recovery utilizes system includes: the boiler comprises a boiler, a bypass economizer, an air preheater, a flue heat exchanger, a desulfurizing tower, a chimney, a blower and a blast heater; wherein,,

the boiler is provided with a fuel inlet, a boiler air supply inlet and a boiler flue gas outlet;

the bypass economizer is provided with a bypass economizer flue gas inlet, a bypass economizer flue gas outlet, a bypass economizer working medium water inlet and a bypass economizer working medium water outlet;

the air preheater is provided with an air preheater flue gas inlet, an air preheater flue gas outlet, an air preheater air supply inlet and an air preheater air supply outlet;

the flue heat exchanger is provided with a flue heat exchanger smoke inlet, a flue heat exchanger smoke outlet, a flue heat exchanger working medium water inlet and a flue heat exchanger working medium water outlet; optionally, the flue heat exchanger is a dividing wall heat exchanger;

the desulfurizing tower includes: a desulfurizing tower body and a slurry circulating pump; a slurry pond is arranged at the bottom of the desulfurizing tower body; the lower part of the desulfurizing tower body is provided with a desulfurizing tower flue gas inlet, and the upper part of the desulfurizing tower body is provided with a desulfurizing tower flue gas outlet; a desulfurizing tower spraying device is arranged between the desulfurizing tower flue gas inlet and the desulfurizing tower flue gas outlet, the desulfurizing tower spraying device is directly or indirectly communicated with the slurry circulating pump, and the slurry circulating pump is directly or indirectly communicated with the slurry pool; optionally, a desulfurizing tower demister is arranged between the desulfurizing tower spraying device and the desulfurizing tower flue gas outlet;

The blower is provided with a blower inlet and a blower outlet;

the air supply heater is provided with an air supply inlet of the air supply heater, an air supply outlet of the air supply heater, a working medium water inlet of the air supply heater and a working medium water outlet of the air supply heater;

the boiler flue gas outlet is directly or indirectly communicated with the air preheater flue gas inlet and the bypass economizer flue gas inlet at the same time; the flue gas outlet of the air preheater and the flue gas outlet of the bypass economizer are directly or indirectly communicated with the flue gas inlet of the flue heat exchanger; the flue gas outlet of the flue heat exchanger is directly or indirectly communicated with the flue gas inlet of the desulfurizing tower; the flue gas outlet of the desulfurizing tower is directly or indirectly communicated with the chimney;

the air supply inlet of the air blower is directly or indirectly communicated with the atmosphere; the air supply outlet of the air supply blower is directly or indirectly communicated with the air supply inlet of the air supply heater; the air supply outlet of the air supply heater is directly or indirectly communicated with the air supply inlet of the air preheater; the air preheater air supply outlet is directly or indirectly communicated with the boiler air supply inlet;

the working medium water outlet of the air supply heater is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; the flue heat exchanger working medium water outlet is directly or indirectly communicated with the air supply heater working medium water inlet;

Optionally, a dust remover or/and an induced draft fan are connected in series on a flue gas channel which is directly or indirectly communicated with the flue gas inlet of the flue heat exchanger or the flue gas outlet of the flue heat exchanger;

optionally, the flue heat exchanger comprises a first stage flue heat exchange module and a second stage flue heat exchange module which are connected in series; the first-stage flue heat exchange module is provided with a flue heat exchanger flue gas inlet, a first-stage flue heat exchange module flue gas outlet, a first-stage flue heat exchange module working medium water inlet and a flue heat exchanger working medium water outlet; the second-stage flue heat exchange module is provided with a second-stage flue heat exchange module flue gas inlet, a flue heat exchanger flue gas outlet, a flue heat exchanger working medium water inlet and a second-stage flue heat exchange module working medium water outlet; the flue gas outlet of the first-stage flue heat exchange module is directly or indirectly communicated with the flue gas inlet of the second-stage flue heat exchange module through a dust remover and/or an induced draft fan, and the working medium water outlet of the second-stage flue heat exchange module is directly or indirectly communicated with the working medium water inlet of the first-stage flue heat exchange module;

preferably, the bypass economizer comprises a first-stage bypass heat exchange module and a second-stage bypass heat exchange module which are connected in series front and back; the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet, a first-stage bypass heat exchange module flue gas outlet, a first-stage bypass heat exchange module working medium water inlet and a bypass economizer working medium water outlet; the second-stage bypass heat exchange module is provided with a second-stage bypass heat exchange module smoke inlet, a bypass economizer smoke outlet, a bypass economizer working medium water inlet and a second-stage bypass heat exchange module working medium water outlet; the first-stage bypass heat exchange module smoke outlet is directly or indirectly communicated with the second-stage bypass heat exchange module smoke inlet, and the second-stage bypass heat exchange module working medium water outlet is directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet; optionally, a bypass header or/and a first bypass deaerator or/and a first bypass water supply pump are connected in series on a working medium water channel between the working medium water outlet of the second-stage bypass heat exchange module and the working medium water inlet of the first-stage bypass heat exchange module;

Optionally, the bypass economizer working medium water outlet is also communicated with a heat user;

optionally, the flue heat exchanger is a tubular heat exchanger or a heat pipe heat exchanger;

optionally, the flue heat exchanger is a series connection of a heat pipe heat exchanger and a tubular heat exchanger;

optionally, a first desulfurizing tower is connected in series on the flue directly or indirectly communicated with the desulfurizing tower flue gas outlet or the desulfurizing tower flue gas outlet;

optionally, the bypass economizer has two or more heat exchange modules and their series/parallel switching structures;

optionally, a working medium water pump is arranged on a working medium water channel which is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger or the working medium water outlet of the flue heat exchanger;

optionally, a bypass feed water pump or/and a bypass deaerator or/and a buffer water tank are arranged on a working medium water channel directly or indirectly communicated with the working medium water inlet of the bypass economizer.

Preferably, in the boiler flue gas waste heat recycling system, a spray tower is connected in series between the desulfurizing tower and the chimney; a second air supply heater is also arranged;

the spray tower is provided with a spray tower smoke inlet, a spray tower smoke outlet, a spray tower heat medium water inlet and a spray tower heat medium water outlet; a spray tower water receiving device is arranged at the bottom of the spray tower; a spray tower water distribution device for heating medium water is arranged between the spray tower flue gas inlet and the spray tower flue gas outlet; the spray tower water distribution device is communicated with the spray tower heat medium water inlet, and the spray tower water receiving device is communicated with the spray tower heat medium water outlet;

The second air supply heater is provided with a second air supply heater air supply inlet, a second air supply heater air supply outlet, a second air supply heater heating medium water inlet and a second air supply heater heating medium water outlet;

the flue gas outlet of the desulfurizing tower is directly or indirectly communicated with the flue gas inlet of the spraying tower, and the flue gas outlet of the spraying tower is directly or indirectly communicated with the chimney; the spray tower heating medium water inlet is directly or indirectly communicated with the second air supply heater heating medium water outlet; the spray tower heating medium water outlet is directly or indirectly communicated with the second air supply heater heating medium water inlet; the air supply channel of the second air supply heater is connected in series with an air channel which is directly or indirectly communicated with the air supply inlet of the blower or the air supply outlet of the blower, and the air supply outlet of the second air supply heater is directly or indirectly communicated with the air supply inlet of the air supply heater;

optionally, a spray tower demister is arranged on a flue gas channel between the spray tower water distribution device and the chimney;

optionally, a heat medium water circulating pump is arranged on a heat medium water pipeline which is directly or indirectly communicated with the spray tower heat medium water outlet or the spray tower heat medium water inlet;

Optionally, a packing layer is arranged between the spray tower water receiving device and the spray tower water distribution device.

Preferably, in the boiler flue gas waste heat recycling system, a spray tower and an absorption heat pump are also arranged;

the spray tower comprises a spray tower body; the spray tower body is provided with a spray tower smoke inlet, a spray tower smoke outlet, a spray tower heating medium water inlet and a spray tower heating medium water outlet; a spray tower water receiving device is arranged at the bottom of the spray tower body; a spray tower water distribution device for heating medium water is arranged between the spray tower flue gas inlet and the spray tower flue gas outlet; the spray tower water distribution device is directly or indirectly communicated with the spray tower heat medium water inlet, and the spray tower water receiving device is directly or indirectly communicated with the spray tower heat medium water outlet; optionally, the spray tower water distribution device is a water distribution tank or a water distribution pipe or a spray device;

the absorption heat pump comprises an evaporator, an absorber, a generator and a condenser, wherein the evaporator is provided with an evaporator low-temperature heat source inlet, an evaporator low-temperature heat source outlet, an evaporator refrigerant water inlet and an evaporator refrigerant water vapor outlet; the absorber is provided with an absorber cold water inlet, an absorber cold water outlet, an absorber refrigerant water vapor inlet, an absorber concentrated absorbent solution inlet and an absorber diluted absorbent solution outlet; the generator is provided with a generator high-temperature heat source inlet, a generator high-temperature heat source outlet, a generator dilute absorbent solution inlet, a generator concentrated absorbent solution outlet and a generator refrigerant water vapor outlet; the condenser is provided with a condenser cooling water inlet, a condenser cooling water outlet, a condenser refrigerant water vapor inlet and a condenser refrigerant water outlet;

The evaporator refrigerant water inlet is in direct or indirect communication with the condenser refrigerant water outlet; the evaporator refrigerant vapor outlet is in direct or indirect communication with the absorber refrigerant vapor inlet; the absorber concentrated absorbent solution inlet is directly or indirectly communicated with the generator concentrated absorbent solution outlet; the absorber lean absorbent solution outlet is directly or indirectly communicated with the generator lean absorbent solution inlet; the generator refrigerant water vapor outlet is directly or indirectly communicated with the condenser refrigerant water vapor inlet; the absorber cold water outlet is directly or indirectly communicated with the condenser cooling water inlet; the absorption heat pump forms a heat-increasing type absorption heat pump;

the spray tower is connected in series on a flue gas channel between the desulfurizing tower and the chimney; the flue gas outlet of the desulfurizing tower is directly or indirectly communicated with the flue gas inlet of the spraying tower, and the flue gas outlet of the spraying tower is directly or indirectly communicated with the chimney;

the spray tower heating medium water outlet is directly or indirectly communicated with the evaporator low-temperature heat source inlet; the low-temperature heat source outlet of the evaporator is directly or indirectly communicated with the spray tower heat medium water inlet;

The bypass economizer working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, and the generator high-temperature heat source outlet is directly or indirectly communicated with the bypass economizer working medium water inlet; or the working medium water outlet of the flue heat exchanger is directly or indirectly communicated with the high-temperature heat source inlet of the generator, and the high-temperature heat source outlet of the generator is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; or the generator high-temperature heat source channel is connected in series with the working medium water channel between the flue heat exchanger working medium water outlet and the air supply heater working medium water inlet, the flue heat exchanger working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, the generator high-temperature heat source outlet is directly or indirectly communicated with the air supply heater working medium water inlet, and the air supply heater working medium water outlet is directly or indirectly communicated with the flue heat exchanger working medium water inlet; or the flue heat exchanger working medium water channel, the bypass economizer working medium water channel, the generator working medium water channel and the air supply heater working medium water channel are sequentially connected in series from beginning to end; the flue heat exchanger working medium water outlet is directly or indirectly communicated with the bypass economizer working medium water inlet; the bypass economizer working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet; the high-temperature heat source outlet of the generator is directly or indirectly communicated with the working medium water inlet of the air supply heater; the working medium water outlet of the air supply heater is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; or the working medium water outlet of the second-stage bypass heat exchange module is directly or indirectly communicated with the working medium water inlet of the first-stage bypass heat exchange module and the generator high-temperature heat source inlet at the same time, and the generator high-temperature heat source outlet is directly or indirectly communicated with the working medium water inlet of the bypass economizer; optionally, a bypass header or/and a first bypass deaerator or/and a first bypass water supply pump are connected in series on a branch working medium water channel between the working medium water outlet of the second-stage bypass heat exchange module and the working medium water inlet of the first-stage bypass heat exchange module;

Optionally, the spray tower heating medium water inlet is also in direct or indirect communication with a raw water source device, and the spray tower heating medium water outlet is also in direct or indirect communication with a raw water user;

optionally, a high-temperature heat source water pump is arranged on the high-temperature heat source channel which is directly or indirectly communicated with the generator high-temperature heat source inlet or the generator high-temperature heat source outlet;

optionally, the high-temperature heat source outlet of the generator is directly or indirectly communicated with the working medium water inlet of the bypass economizer through a cooler; optionally, the cooler is a generator of other absorption heat pumps or other air supply heaters;

optionally, a cold water reheater is connected in series on a cold water channel directly or indirectly communicated with the condenser cooling water outlet or the absorber cold water outlet;

optionally, a cold water pump is connected in series on a cold water channel directly or indirectly communicated with the condenser cooling water outlet or the absorber cold water inlet;

Preferably, in the boiler flue gas waste heat recycling system, the absorber cold water outlet or the condenser cooling water outlet is also directly or indirectly communicated with the flue heat exchanger working medium water inlet; the working medium water outlet of the flue heat exchanger is also directly or indirectly communicated with a heat user; or a cold water channel directly or indirectly communicated with the condenser cooling water outlet is connected with a cold water reheater in series; the cold water reheater is provided with a cold water inlet of the cold water reheater, a cold water outlet of the cold water reheater, a heat source inlet of the cold water reheater and a heat source outlet of the cold water reheater; the cold water inlet of the cold water reheater is directly or indirectly communicated with the condenser cooling water outlet; the cold water outlet of the cold water reheater is directly or indirectly communicated with a hot user; the heat source inlet of the cold water reheater is directly or indirectly communicated with the working medium water outlet of the flue heat exchanger; the heat source outlet of the cold water reheater is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; optionally, a second cooler is connected in series between the cold water reheater heat source outlet and the flue heat exchanger working medium water inlet; the cold water reheater is a dividing wall type heat exchanger; optionally, the cold water reheater is a plate heat exchanger.

Preferably, in the boiler flue gas waste heat recycling system, a first absorption heat pump is further arranged; the first absorption heat pump comprises a first evaporator, a first absorber, a first generator and a first condenser; the first evaporator is provided with a first evaporator low temperature heat source inlet, a first evaporator low temperature heat source outlet, a first evaporator refrigerant water inlet and a first evaporator refrigerant water vapor outlet; the first absorber is provided with a first absorber cold water inlet, a first absorber cold water outlet, a first absorber refrigerant water vapor inlet, a first absorber concentrated absorbent solution inlet and a first absorber diluted absorbent solution outlet; the first generator is provided with a first generator high-temperature heat source inlet, a first generator high-temperature heat source outlet, a first generator dilute absorbent solution inlet, a first generator concentrated absorbent solution outlet and a first generator refrigerant water vapor outlet; the first condenser is provided with a first condenser cooling water inlet, a first condenser cooling water outlet, a first condenser refrigerant water vapor inlet and a first condenser refrigerant water outlet; the first evaporator refrigerant water inlet is in direct or indirect communication with the first condenser refrigerant water outlet; the first evaporator refrigerant vapor outlet is in direct or indirect communication with the first absorber refrigerant vapor inlet; the first absorber concentrated absorbent solution inlet is in direct or indirect communication with the first generator concentrated absorbent solution outlet; the first absorber lean absorbent solution outlet is in direct or indirect communication with the first generator lean absorbent solution inlet; the first generator refrigerant vapor outlet is in direct or indirect communication with the first condenser refrigerant vapor inlet; the first absorber cold water outlet is directly or indirectly communicated with the first condenser cooling water inlet; the absorption heat pump forms a heat-increasing type absorption heat pump;

The spray tower heating medium water outlet is also directly or indirectly communicated with the low-temperature heat source inlet of the first evaporator; the low-temperature heat source outlet of the first evaporator is directly or indirectly communicated with the spray tower heat medium water inlet;

when the bypass economizer working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, the generator high-temperature heat source outlet is directly or indirectly communicated with the bypass economizer working medium water inlet, the first generator high-temperature heat source channel is connected in series with the working medium water channel between the generator high-temperature heat source outlet and the bypass economizer working medium water inlet, and the first generator high-temperature heat source inlet is directly or indirectly communicated with the generator high-temperature heat source outlet; the high-temperature heat source outlet of the first generator is directly or indirectly communicated with the working medium water inlet of the bypass economizer;

when the flue heat exchanger working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, the first generator high-temperature heat source channel is connected in series with the working medium water channel between the generator high-temperature heat source outlet and the flue heat exchanger working medium water inlet, and the first generator high-temperature heat source inlet is directly or indirectly communicated with the generator high-temperature heat source outlet; the high-temperature heat source outlet of the first generator is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger;

When the generator high-temperature heat source channel is connected in series with the working medium water channel between the flue heat exchanger working medium water outlet and the air supply heater working medium water inlet, the flue heat exchanger working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, the generator high-temperature heat source outlet is directly or indirectly communicated with the air supply heater working medium water inlet, and the air supply heater working medium water outlet is directly or indirectly communicated with the flue heat exchanger working medium water inlet, the first generator high-temperature heat source channel is connected in series with the working medium water channel between the generator high-temperature heat source outlet and the air supply heater working medium water inlet, and the first generator high-temperature heat source inlet is directly or indirectly communicated with the generator high-temperature heat source outlet; the high-temperature heat source outlet of the first generator is directly or indirectly communicated with the working medium water inlet of the air supply heater;

when the second-stage bypass heat exchange module bypass economizer working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, and the generator high-temperature heat source outlet is directly or indirectly communicated with the bypass economizer working medium water inlet, the first generator high-temperature heat source channel is connected in series with the working medium water channel between the generator high-temperature heat source outlet and the bypass economizer working medium water inlet, and the first generator high-temperature heat source inlet is directly or indirectly communicated with the generator high-temperature heat source outlet; the high-temperature heat source outlet of the first generator is directly or indirectly communicated with the working medium water inlet of the bypass economizer;

When the flue heat exchanger working medium water channel, the bypass economizer working medium water channel, the generator working medium water channel and the air supply heater working medium water channel are sequentially connected in series from end to end, the first generator high-temperature heat source channel is connected in series to the working medium water channel between the generator high-temperature heat source outlet and the air supply heater working medium water inlet, and the first generator high-temperature heat source inlet is directly or indirectly communicated with the generator high-temperature heat source outlet; the high-temperature heat source outlet of the first generator is directly or indirectly communicated with the working medium water inlet of the air supply heater;

the cold water channel of the first absorber and the first condenser which are connected in series is connected in series with the cold water channel of the cold water inlet of the absorber; the first condenser cooling water outlet is in direct or indirect communication with the absorber cold water inlet.

Preferably, in the boiler flue gas waste heat recycling system, a first air supply heater is further arranged; the first air supply heater is provided with a first air supply heater air supply inlet, a first air supply heater air supply outlet, a first air supply heater cold water inlet and a first air supply heater cold water outlet; the air supply channel of the first air supply heater is connected in series with an air channel which is directly or indirectly communicated with the air supply inlet of the air blower or the air supply outlet of the air blower; the air supply outlet of the first air supply heater is directly or indirectly communicated with the air supply inlet of the air supply heater; the first air supply heater cold water inlet is directly or indirectly communicated with the condenser cooling water outlet; the first air supply heater cold water outlet is directly or indirectly communicated with the absorber cold water inlet; when the first absorption heat pump is further arranged, the cold water outlet of the first air supply heater is directly or indirectly communicated with the cold water inlet of the first absorber; optionally, the first air supply heater is a dividing wall type heat exchanger; optionally, a cold water pump is arranged on a cold water channel which is directly or indirectly communicated with the cold water inlet of the absorber or the cold water outlet of the condenser.

Preferably, in the boiler flue gas waste heat recycling system, a second air supply heater is further arranged; the second air supply heater is provided with a second air supply heater air supply inlet, a second air supply heater air supply outlet, a second air supply heater heating medium water inlet and a second air supply heater heating medium water outlet; the air supply channel of the second air supply heater is connected in series with the air channel which is directly or indirectly communicated with the air supply inlet of the air blower or the air supply outlet of the air blower; the air supply outlet of the second air supply heater is directly or indirectly communicated with the air supply inlet of the air supply heater; preferably, when the first air supply heater is provided, the second air supply heater air supply outlet is directly or indirectly communicated with the first air supply heater air supply inlet; the second air supply heater heating medium water inlet is directly or indirectly communicated with the spray tower heating medium water outlet; the second air supply heater heating medium water outlet is directly or indirectly communicated with the spray tower heating medium water inlet; optionally, the second supply air heater is a dividing wall heat exchanger.

Preferably, in the boiler flue gas waste heat recycling system, a steam turbine, a condenser, a condensate pump, a low-pressure heater, a deaerator, a water supply pump and a high-pressure heater are further arranged;

The steam turbine is provided with a steam turbine steam inlet, a steam turbine steam outlet, a steam turbine high-pressure steam extraction outlet and a steam turbine low-pressure steam extraction outlet;

the condenser is provided with a condenser steam inlet and a condenser working medium water outlet;

the condensate pump is provided with a condensate pump inlet and a condensate pump outlet;

the low-pressure heater is provided with a low-pressure heater working medium water inlet, a low-pressure heater working medium water outlet and a low-pressure heater steam extraction inlet;

the deaerator is provided with a deaerator working medium water inlet and a deaerator working medium water outlet;

the water feed pump is provided with a water feed pump inlet and a water feed pump outlet;

the high-pressure heater is provided with a high-pressure heater working medium water inlet, a high-pressure heater working medium water outlet and a high-pressure heater steam extraction inlet;

the boiler is also provided with a boiler working medium water inlet and a boiler steam outlet;

the boiler steam outlet is directly or indirectly communicated with the steam inlet of the steam turbine; the steam outlet of the steam turbine is directly or indirectly communicated with the steam inlet of the condenser; the condenser working medium water outlet is directly or indirectly communicated with the condensate pump inlet; the condensate pump outlet is directly or indirectly communicated with the low-pressure heater working medium water inlet and the bypass economizer working medium water inlet at the same time; the low-pressure heater working medium water outlet is directly or indirectly communicated with the deaerator working medium water inlet; the working medium water outlet of the deaerator is directly or indirectly communicated with the inlet of the water feeding pump; the water feed pump outlet is directly or indirectly communicated with the working medium water inlet of the high-pressure heater; the high-pressure heater working medium water outlet and the bypass economizer working medium water outlet are directly or indirectly communicated with the boiler working medium water inlet; the low-pressure heater steam extraction inlet is directly or indirectly communicated with the steam turbine low-pressure steam extraction outlet; the high-pressure heater steam extraction inlet is directly or indirectly communicated with the steam turbine high-pressure steam extraction outlet;

Optionally, a first low pressure heater is also provided; the condensate pump outlet is directly or indirectly communicated with the low-pressure heater working medium water inlet and the bypass economizer working medium water inlet through the first low-pressure heater;

the low-pressure heater is one-stage or multi-stage low-pressure heater; the high-pressure heater is a one-stage or multi-stage high-pressure heater; the first low-pressure heater is a one-stage or multi-stage low-pressure heater; the high-pressure steam extraction outlet of the steam turbine is one-stage or multi-stage; the low-pressure steam extraction outlet of the steam turbine is one-stage or multi-stage.

the boiler steam outlet is directly or indirectly communicated with the steam inlet of the steam turbine; the steam outlet of the steam turbine is directly or indirectly communicated with the steam inlet of the condenser; the condenser working medium water outlet is directly or indirectly communicated with the condensate pump inlet; the condensate pump outlet is directly or indirectly communicated with the working medium water inlet of the low-pressure heater; the low-pressure heater working medium water outlet is directly or indirectly communicated with the deaerator working medium water inlet; the working medium water outlet of the deaerator is directly or indirectly communicated with the inlet of the water feeding pump; the water feed pump outlet is directly or indirectly communicated with the high-pressure heater working medium water inlet and the bypass economizer working medium water inlet at the same time; the high-pressure heater working medium water outlet and the bypass economizer working medium water outlet are directly or indirectly communicated with the boiler working medium water inlet; the low-pressure heater steam extraction inlet is directly or indirectly communicated with the steam turbine low-pressure steam extraction outlet; the high-pressure heater steam extraction inlet is directly or indirectly communicated with the steam turbine high-pressure steam extraction outlet;

Optionally, a first low pressure heater is also provided; the condensate pump outlet is directly or indirectly communicated with the working medium water inlet of the low-pressure heater through the first low-pressure heater;

the low-pressure heater is one-stage or multi-stage low-pressure heater; the high-pressure heater is a one-stage or multi-stage high-pressure heater; the high-pressure steam extraction outlet of the steam turbine is one-stage or multi-stage; the low-pressure steam extraction outlet of the steam turbine is one-stage or multi-stage.

Preferably, in the boiler flue gas waste heat recycling system, the condensate pump outlet is directly or indirectly communicated with the bypass economizer working medium water inlet through the flue heat exchanger; the outlet of the condensate pump is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; the flue heat exchanger working medium water outlet is directly or indirectly communicated with the bypass economizer working medium water inlet; the bypass economizer working medium water outlet is directly or indirectly communicated with the boiler working medium water inlet; optionally, a first bypass buffer water tank or/and a first bypass working medium water pump or/and a heater are arranged on a working medium water channel between the condensate pump outlet and the flue heat exchanger working medium water inlet.

Preferably, in the boiler flue gas waste heat recycling system, the spray tower is arranged above the desulfurization tower, the desulfurization tower and the spray tower are connected through a liquid collecting device to form a desulfurization spray integrated structure, and the slurry pool, the flue gas inlet of the desulfurization tower, the spray device of the desulfurization tower, the liquid collecting device, the water distributing device of the spray tower and the flue gas outlet of the spray tower are sequentially arranged inside the desulfurization spray integrated structure from bottom to top; the liquid collecting device is of a multifunctional integrated structure comprising a flue gas outlet of the desulfurizing tower, a flue gas inlet of the spraying tower and a water receiving device of the spraying tower, flue gas from the desulfurizing tower can enter the spraying tower through the liquid collecting device, heat medium water from the spraying tower falls into the liquid collecting device to be collected, and is guided out of the liquid collecting device through the heat medium water outlet of the spraying tower to be incapable of flowing into the desulfurizing tower; optionally, a filler layer is arranged between the liquid collecting device and the spray tower water distribution device.

Preferably, in the boiler flue gas waste heat recycling system, the liquid collecting device is a liquid collecting and demisting integrated structure with demisting function, and the liquid collecting and demisting integrated structure comprises a liquid collecting chassis, a gas lifting pipe and a gas lifting cap; the liquid collecting chassis is provided with a plurality of vent holes, the vent holes are correspondingly provided with the gas lifting pipes, the top ends of the gas lifting pipes are provided with gas lifting caps, and gas lifting channels for the circulation of flue gas are arranged on the gas lifting caps or between the gas lifting caps and the top ends of the gas lifting pipes or on the pipe walls of the upper sections of the gas lifting pipes; a guide vane or a cyclone is arranged in the gas lift pipe, or/and a demisting pipe is connected below the gas lift pipe or arranged in the gas lift pipe, and the guide vane or the cyclone is arranged in the demisting pipe; the gas lifting pipe and the demisting pipe are of a split structure or an integrated structure; the liquid collecting chassis is provided with a water retaining edge or is in sealing connection with the inner wall of the tower body of the desulfurization spraying integrated structure, the inner wall of the desulfurization spraying integrated structure is used as the water retaining edge, an upward opening space enclosed between the liquid collecting chassis and the water retaining edge is used as a spray tower water receiving device, and the spray tower water receiving device is directly or indirectly communicated with a spray tower heating medium water outlet; optionally, the lift cap adopts a tower-type shutter structure, the outer diameter of the lift cap and the outer diameter of the lift pipe are smaller than or equal to the inner diameter of the vent hole on the liquid collecting chassis, and the lift pipe and the lift cap are installed in a mode of being detachable from the liquid collecting chassis.

In another aspect of the invention, a method for recycling waste heat of boiler flue gas is provided, comprising the following steps: the fuel is sent into the hearth of the boiler, the blower sends air into the hearth of the boiler through the air preheater, the fuel burns to release heat, and the flue gas generated by the combustion flows out of the boiler; then a part of flue gas is sent into an air preheater to heat the air supply from the blower, and the flue gas exchanges heat with the air supply to cool and then flows out of the air preheater; a part of flue gas enters a bypass economizer, exchanges heat with working medium water and then flows out of the bypass economizer; flue gas from a flue gas outlet of the air preheater and flue gas from a flue gas outlet of the bypass economizer directly or indirectly enter a flue heat exchanger through other equipment (such as a dust remover or/and an induced draft fan), exchange heat with working medium water, cool down and flow out of the flue heat exchanger, and then directly or indirectly flow into the desulfurizing tower through other equipment (such as the dust remover or/and the induced draft fan);

the flue gas enters the desulfurizing tower and flows through a desulfurizing tower spraying device from bottom to top, the desulfurizing slurry in the slurry pond enters the desulfurizing tower spraying device under the drive of a slurry circulating pump, the desulfurizing tower spraying device sprays the desulfurizing slurry into the flue gas from top to bottom, the flue gas and the desulfurizing slurry exchange heat and transfer mass in a countercurrent way, the flue gas is optionally defogged through a desulfurizing tower defogger in a saturated state or a near saturated state after heat exchange and desulfurization, and then flows out of the desulfurizing tower through a desulfurizing tower flue gas outlet and is discharged into the atmosphere through a chimney;

The working medium water enters a flue heat exchanger, exchanges heat with the flue gas, heats up and flows out; then the air enters an air supply heater to be heated and supplied with air, the temperature is reduced, and then the air returns to a flue heat exchanger to be heated again for recycling; the air supply enters the air supply heater under the drive of the air blower, is heated by working medium water from the flue heat exchanger, and flows out of the air supply heater after being heated; then enters an air preheater, is further heated by flue gas from a boiler, flows out of the air preheater after being heated, and enters a boiler hearth;

optionally, the bypass economizer is provided with two or more heat exchange modules and a series/parallel switching structure thereof, and the connection mode of the heat exchange modules is switched through the series/parallel switching structure;

optionally, a bypass feed pump or/and a bypass deaerator are arranged on a working medium water channel directly or indirectly communicated with the working medium water inlet of the bypass economizer;

optionally, the flue heat exchanger comprises a first stage flue heat exchange module and a second stage flue heat exchange module which are connected in series; the flue gas outlet of the first-stage flue heat exchange module is directly or indirectly communicated with the flue gas inlet of the second-stage flue heat exchange module through a dust remover and/or an induced draft fan, and the working medium water outlet of the second-stage flue heat exchange module is directly or indirectly communicated with the working medium water inlet of the first-stage flue heat exchange module; the flue gas firstly passes through the first-stage flue heat exchange module, then passes through a dust remover or/and an induced draft fan, and then enters the second-stage flue heat exchange module; the working medium water is heated by the second-stage flue heat exchange module and then enters the first-stage flue heat exchange module for continuous heating;

optionally, the bypass economizer comprises a first-stage bypass heat exchange module and a second-stage bypass heat exchange module which are connected in series front and back; the flue gas from the boiler passes through the first-stage bypass heat exchange module and the second-stage bypass heat exchange module in sequence, exchanges heat with working medium water, cools down and then is sent to a flue heat exchanger; the working medium water is firstly subjected to heat exchange and temperature rise between the second-stage bypass heat exchange module and the flue gas, then is sent to the first-stage bypass heat exchange module, is further subjected to heat exchange and temperature rise between the working medium water and the flue gas with higher temperature, and is then sent to a heat user; optionally, the working medium water is firstly subjected to heat exchange and temperature rise between the second-stage bypass heat exchange module and the flue gas, then is sent to a bypass header or/and deoxidized by a first bypass deaerator or/and is sent to the first-stage bypass heat exchange module through the pressure rise of a first bypass feed water pump, and is further subjected to heat exchange and temperature rise with the flue gas with higher temperature;

In the method for recycling the waste heat of the boiler flue gas, a spray tower is connected in series between the desulfurizing tower and the chimney; the air supply channel of the second air supply heater is connected in series with an air channel which is directly or indirectly communicated with the air supply inlet of the blower or the air supply outlet of the blower, and the air supply outlet of the second air supply heater is directly or indirectly communicated with the air supply inlet of the air supply heater; the desulfurized saturated or nearly saturated flue gas enters a spray tower, the heat medium water from a second air supply heater is scattered into the flue gas through a spray tower water distribution device, the flue gas and the heat medium water are mixed for heat exchange, the saturated flue gas is further cooled, dehumidified and washed, and then the saturated flue gas is discharged into the atmosphere through a spray tower flue gas outlet and a chimney;

after the heat medium water is mixed with the flue gas in the spray tower for heat exchange and temperature rise, the heat medium water is sent into a heat medium water channel of a second air supply heater, air supply (air) enters the air supply channel of the second air supply heater under the drive of an air supply blower, the temperature of the heat medium water is reduced after the heat medium water is heated and supplied with air, and then the heat medium water returns to the spray tower for recycling; the air supply with the temperature increased is sent to the air supply heater and the air preheater in sequence, and then is sent to a hearth of the boiler after being further heated;

optionally, the spray tower water distribution device distributes the heat medium water on the packing layer, and the flue gas and the heat medium water exchange heat in the packing layer.

In the method for recycling the waste heat of the boiler flue gas, a spray tower and an absorption heat pump are also arranged; the absorption heat pump comprises an evaporator, an absorber, a generator and a condenser; the saturated or nearly saturated flue gas after desulfurization enters a spray tower, hot medium water from a low-temperature heat source outlet of an evaporator is scattered into the flue gas through a spray tower water distribution device, the flue gas and the hot medium water are mixed for heat exchange, the saturated flue gas is further cooled, dehumidified and washed, and then the saturated flue gas is discharged into the atmosphere through a spray tower flue gas outlet and a chimney;

the sensible heat of the flue gas, the vaporization latent heat of the condensation of the water vapor and the temperature of the heat of reaction in the desulfurization process are absorbed by the heat medium water in the spray tower, and the heat medium water is collected by a water receiving device of the spray tower and then sent to an evaporator;

The heat medium water from the spray tower enters the heat exchange tube in the evaporator, the evaporator is in a low-pressure (such as vacuum) state, the refrigerant water conveyed by the condenser absorbs the heat of the heat medium water in the heat exchange tube and then evaporates to cool the heat medium water, and meanwhile, the refrigerant water vapor generated by evaporation enters the absorber; the cooled heat medium water flows out of the absorption heat pump and returns to the spray tower for recycling;

cold water from a hot user enters into a heat transfer pipe of an absorber, and in the absorber, the concentrated absorbent solution from the absorber absorbs the refrigerant vapor from an evaporator and emits heat to increase the temperature of the absorbent solution; when the absorbent solution is in contact with the heat transfer pipe of the absorber, cold water in the heat transfer pipe is heated to enter water, so that heat transfer from low-grade heat of the heat medium water of the spray tower to the cold water is realized, and the temperature of the cold water is increased; then the concentrated absorbent solution is changed into the dilute absorbent solution and then is delivered to the generator after flowing out of the absorber and entering the condenser;

working medium water from the bypass economizer is used as a high-temperature driving heat source, enters the generator, dilute absorbent solution from the absorber in the generator is heated and concentrated by the working medium water to form concentrated absorbent solution, then enters the absorber, the dilute absorbent solution is heated and concentrated, and refrigerant water vapor with higher temperature is generated at the same time, and enters the condenser; after heat exchange and temperature reduction, the working medium water flows out of the absorption heat pump and returns to the bypass economizer for recycling;

Or, working medium water with higher temperature from a working medium water outlet of the flue heat exchanger is used as a high-temperature driving heat source, and enters the generator, the dilute absorbent solution from the absorber in the generator is heated and concentrated by the working medium water to form a concentrated absorbent solution, and then enters the absorber, the dilute absorbent solution is heated and concentrated while generating refrigerant water vapor with higher temperature, and the refrigerant water vapor enters the condenser; the working medium water flows out of the absorption heat pump after heat exchange and temperature reduction and returns to the flue heat exchanger for recycling;

or, working medium water with higher temperature from a working medium water outlet of the flue heat exchanger is used as a high-temperature driving heat source, and enters the generator, the absorbent dilute solution from the absorber in the generator is heated and concentrated by the working medium water to be concentrated into a concentrated solution, and then enters the absorber, the dilute absorbent solution is heated and concentrated and simultaneously generates refrigerant water vapor with higher temperature, and the refrigerant water vapor enters the condenser; the working medium water flows out of the absorption heat pump after heat exchange and cooling, is sent to the air supply heater for heating, air supply and cooling, and then returns to the flue heat exchanger for recycling;

or working medium water from the bypass economizer is used as a high-temperature driving heat source, the working medium water enters the generator, the absorbent dilute solution from the absorber in the generator is heated and concentrated by the working medium water to form a concentrated solution, the concentrated solution enters the absorber, the dilute absorbent solution is heated and concentrated, refrigerant water vapor with higher temperature is generated, and the refrigerant water vapor enters the condenser; the working medium water flows out of the absorption heat pump after heat exchange and cooling, is sent to the air supply heater for heating, air supply and cooling, is sent to the flue heat exchanger for heat exchange with the flue gas, and is returned to the bypass economizer for recycling;

Or the bypass economizer comprises a first-stage bypass heat exchange module and a second-stage bypass heat exchange module which are connected in series front and back; the flue gas from the boiler passes through the first-stage bypass heat exchange module and the second-stage bypass heat exchange module in sequence, exchanges heat with working medium water, cools down and then is sent to a flue heat exchanger; after the heat exchange and temperature rising of the working medium water between the second-stage bypass heat exchange module and the flue gas are carried out, a part of the working medium water is sent to the first-stage bypass heat exchange module to be further subjected to heat exchange and temperature rising with the flue gas with higher temperature, and then is sent to a heat user; part of the refrigerant water vapor is used as a high-temperature driving heat source, enters the generator, the dilute absorbent solution from the absorber in the generator is heated and concentrated by working medium water to form a concentrated absorbent solution, then enters the absorber, the dilute absorbent solution is heated and concentrated and generates refrigerant water vapor with higher temperature, and the refrigerant water vapor enters the condenser; the working medium water flows out of the absorption heat pump after heat exchange and temperature reduction and returns to the second-stage bypass heat exchange module for recycling; optionally, working medium water at a working medium water outlet of the second-stage bypass heat exchange module is subjected to heat exchange and temperature rise with smoke at a higher temperature by passing through a bypass header or/and deoxidizing by a first bypass deaerator or/and boosting by a first bypass water supply pump and then is sent to the first-stage bypass heat exchange module.

Cold water from the absorber, which is heated by the absorber and heated, enters the condenser as cooling water, in the condenser, high-temperature refrigerant vapor from the generator exchanges heat with the cooling water to release condensation latent heat and condense the condensation latent heat into refrigerant water, and the cooling water absorbs heat and heats up and flows out of the condenser to be sent to a heat user for use; the refrigerant water after the condensation of the refrigerant water vapor enters an evaporator to be evaporated, and the circulation is performed;

optionally, the spray tower heating medium water inlet is directly or indirectly communicated with a raw water source device, and the spray tower heating medium water outlet is directly or indirectly communicated with a raw water user;

optionally, a cold water reheating device is connected in series on a cold water channel directly or indirectly communicated with the condenser cooling water outlet;

In the method for recycling the waste heat of the boiler flue gas, cold water from a cooling water outlet of a condenser and working medium water from a working medium water outlet of an air supply heater are sent to a flue heat exchanger to be heated by flue gas, and then a part of the cold water and the working medium water are sent to the air supply heater to be heated and supplied to a heat user; or, part of cold water heated by the absorber is split into a flue heat exchanger working medium water inlet, and part of cold water and working medium water at a working medium water outlet of the air supply heater are heated by the flue heat exchanger, and then the part of cold water and working medium water are sent to the air supply heater for heating and air supply, and the part of cold water and working medium water are sent to a heat user for use; or, the device is also provided with a cold water reheater, cold water from a cooling water outlet of the condenser enters the cold water reheater, exchanges heat with high-temperature working medium water from a working medium water outlet of the flue heat exchanger in the cold water reheater, and flows out of the cold water reheater after being warmed up, and is sent to a hot user for use; the temperature of the working medium water is reduced after heat exchange with cold water, and the working medium water returns to the flue heat exchanger for recycling; optionally, a second cooler is connected in series between the cold water reheater heat source outlet and the flue heat exchanger working medium water inlet.

In the method for recycling the waste heat of the boiler flue gas, a first absorption heat pump is further arranged; the first absorption heat pump comprises a first evaporator, a first absorber, a first generator and a first condenser; the heat medium water from the spray tower enters a heat exchange tube in a first evaporator, the first evaporator is in a low-pressure (such as vacuum) state, the refrigerant water conveyed by the first condenser absorbs the heat of the heat medium water in the heat exchange tube and then evaporates to cool the heat medium water, and meanwhile, the refrigerant water vapor generated by evaporation enters a first absorber; the cooled heat medium water flows out of the first absorption heat pump and returns to the spray tower for recycling;

cold water from a hot user enters a heat transfer pipe of a first absorber, and in the first absorber, the concentrated absorbent solution from a first generator absorbs the refrigerant vapor from a first evaporator and emits heat to increase the solution temperature; when the absorbent solution contacts with the heat transfer pipe of the first absorber, cold water in the heat transfer pipe is heated to enter water, so that heat transfer from low-grade heat of the heat medium water of the spray tower to the cold water is realized, and the temperature of the cold water is increased; then the concentrated absorbent solution flows out of the first absorber and enters the first condenser, and is conveyed to the first generator after being changed into the dilute absorbent solution;

The high-temperature working medium water from the bypass economizer is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, the high-temperature driving heat source of the first absorption heat pump enters the first generator after heat exchange and cooling of the generator, and the high-temperature driving heat source of the first absorption heat pump flows out of the first absorption heat pump after further heat exchange and cooling of the generator and is returned to the bypass economizer for recycling; or the high-temperature working medium water from the first-stage bypass heat exchange module is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, flows out of the absorption heat pump after heat exchange and temperature reduction of the generator, then enters the first generator as a high-temperature driving heat source of the first absorption heat pump, flows out of the first absorption heat pump after heat exchange and temperature reduction, and is returned to the first bypass module for recycling; or, working medium water from the flue heat exchanger is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, enters the generator for heat exchange and cooling, and then flows out of the generator; then enters the first generator to exchange heat and cool down, and then flows out of the first generator to return to the flue heat exchanger for recycling; or the working medium water from the flue heat exchanger is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, enters the generator for heat exchange and cooling, and then flows out of the generator; then enters the first generator to exchange heat and cool down, and then flows out of the first generator; then, the air is taken as a heating source of the air supply heater, enters the air supply heater to be heated, supplied with air and cooled, flows out, and returns to the flue heat exchanger for recycling; a heat source is driven at a high temperature to enter a first generator, in the first generator, a dilute absorbent solution from a first absorber is heated and concentrated by working medium water to form a concentrated solution, the concentrated solution enters the first absorber, the dilute absorbent solution is heated and concentrated and simultaneously generates refrigerant water vapor with higher temperature, and the refrigerant water vapor enters a first condenser; the working medium water used as a high-temperature driving heat source exchanges heat and cools and flows out of the first absorption heat pump;

Cold water which is heated and warmed by the first absorber and comes from the first absorber enters the first condenser as cooling water, high-temperature refrigerant vapor from the first generator exchanges heat with the cooling water in the first condenser to release condensation latent heat and condense the condensation latent heat into refrigerant water, the cooling water absorbs heat and is warmed and flows out of the first condenser, and the refrigerant water is sent to an evaporator low-temperature heat source inlet of the absorption heat pump to be further heated and warmed; the refrigerant water after the condensation of the refrigerant water vapor enters a first evaporator to be evaporated, and the circulation is performed;

cold water from a heating user firstly enters the first absorption heat pump for heating, then enters the absorption heat pump for further heating, then flows out of the absorption heat pump, and is sent to the heating user for use.

In the method for recycling the waste heat of the boiler flue gas, a first air supply heater is further arranged; cold water from the condenser cooling water outlet is sent to the first air supply heater for heating and air supply, then cooled, and is sent back to the absorber cold water inlet for circulation; when the first absorption heat pump is further arranged, cold water is heated and blown by the first blowing heater and then cooled, and then is sent to a cold water inlet of the first absorber; the air supply is driven by the blower, passes through the first air supply heater, is heated by cold water from the cooling water outlet of the condenser, and is then heated by the air supply heater and the air preheater and then is fed into the boiler;

Optionally, a cold water pump is arranged on a cold water channel which is directly or indirectly communicated with the cold water inlet of the absorber or the cold water outlet of the condenser.

In the method for recycling the waste heat of the boiler flue gas, a second air supply heater is also arranged; the heat medium water from the spray tower is directly or indirectly sent to a second air supply heater for heating and air supply, then the temperature is reduced, and the heat medium water returns to the spray tower for recycling; the air supply (air) is heated by the heat medium water from the spray tower through the second air supply heater under the drive of the blower, then continuously heated through the first air supply heater (if any), the air supply heater and the air preheater in sequence, and then sent into the boiler; optionally, the second supply air heater is a dividing wall heat exchanger.

The method for recycling the waste heat of the boiler flue gas is further provided with the following steps: the device comprises a steam turbine, a condenser, a condensate pump, a low-pressure heater, a deaerator, a water supply pump and a high-pressure heater; the high-pressure high-temperature steam generated by boiler combustion is sent into a steam turbine to do work and then is discharged into a condenser to be cooled and condensed into working medium water (condensed water), then part of working medium water is sent into a low-pressure heater to be heated and flows out by the extraction steam from a low-pressure extraction steam outlet of the steam turbine under the driving of a condensed water pump, then is sent into a deaerator to be deoxidized, is sent into a high-pressure heater to be heated and flows out of the high-pressure heater after being heated by the extraction steam from the high-pressure extraction steam outlet of the steam turbine under the driving of a water supply pump; part of working medium water is directly or indirectly sent to a bypass economizer through other devices (such as a heater, a water pump and a buffer water tank) to exchange heat with the flue gas to raise the temperature, and then flows out of the bypass economizer; working medium water (all or part) from the high-pressure heater and the bypass economizer is sent to the boiler; the fuel from the fuel inlet of the boiler and the air supply from the air supply inlet of the boiler generate combustion reaction to release heat, the working medium water from the working medium water inlet of the boiler is heated to generate high-pressure high-temperature steam, and the high-pressure high-temperature steam is sent to the steam turbine through the steam outlet of the boiler to continuously do work, and the cycle is performed;

Optionally, a first low pressure heater is also provided; working medium water from a condensate pump is heated by a first low-pressure heater and then is respectively sent to a low-pressure heater and a bypass economizer;

The method for recycling the waste heat of the boiler flue gas is further provided with the following steps: the device comprises a steam turbine, a condenser, a condensate pump, a low-pressure heater, a deaerator, a water supply pump and a high-pressure heater; the high-pressure high-temperature steam generated by boiler combustion is sent into a steam turbine to do work and then is discharged into a condenser to be cooled and condensed into working medium water (condensed water), then is sent into a low-pressure heater to be heated and flows out by the extraction steam from a low-pressure extraction steam outlet of the steam turbine under the driving of a condensed water pump, is then sent into a deaerator to flow out after deoxidization, then is sent into a high-pressure heater to be heated and flows out of the high-pressure heater by the extraction steam from a high-pressure extraction steam outlet of the steam turbine under the driving of a water supply pump; part of working medium water is directly or indirectly sent to a bypass economizer through other devices (such as a heater, a water pump and a buffer water tank) to exchange heat with the flue gas to raise the temperature, and then flows out of the bypass economizer; working medium water (all or part) from the high-pressure heater and the bypass economizer is sent to the boiler; the fuel from the fuel inlet of the boiler and the air supply from the air supply inlet of the boiler generate combustion reaction to release heat, the working medium water from the working medium water inlet of the boiler is heated to generate high-pressure high-temperature steam, and the high-pressure high-temperature steam is sent to the steam turbine through the steam outlet of the boiler to continuously do work, and the cycle is performed;

Optionally, a first low pressure heater is also provided; working medium water from the condensate pump is heated by a first low-pressure heater and then sent to the low-pressure heater;

In the method for recycling the waste heat of the boiler flue gas, working medium water at the outlet of the condensate pump is sent into the bypass economizer through the flue heat exchanger; working medium water from the outlet of the condensate pump is directly or through a first buffer water tank or/and a first bypass working medium water pump or/and a heater sent to the flue heat exchanger, flows out after heat exchange and temperature rise with flue gas, and the working medium water (whole or part) from the working medium water outlet of the flue heat exchanger enters the bypass economizer to heat exchange with higher-temperature flue gas, flows out from the working medium water outlet of the bypass economizer after further temperature rise, and the working medium water (whole or part) from the working medium water outlet of the bypass economizer enters a boiler, flows out from the steam outlet of the boiler after being heated into high-temperature high-pressure steam in the boiler, works by being sent to a steam turbine, is discharged to the condenser to be cooled into condensate water, namely the working medium water, and enters the inlet of the condensate pump for circulation in sequence.

The method for recycling the waste heat of the boiler flue gas is carried out by adopting the system for recycling the waste heat of the boiler flue gas.

The blowers described herein are various blowers that supply oxygen required for combustion to the supply air in a boiler, such as blowers and/or primary blowers in a power plant. The boiler refers to a device that burns fuel to emit heat and generates flue gas.

The steam turbine is generally used for driving a generator to generate electricity, and has the advantages of improving the working efficiency, improving the working capacity and reducing the energy consumption, namely reducing the electricity generation coal consumption and the power supply coal consumption.

The spray tower water distribution device is a water distribution tank, a water distribution pipe, a spray device or the like, and can distribute the heat medium water into the flue gas. The spray tower water receiving device can be a tower pool positioned at the lower part of the spray tower or other structural forms, so long as the heat medium water flowing out from the water distribution device can be collected.

The absorption heat pump is a circulating system which utilizes high-grade energy to drive and realize heat transfer from low temperature to high temperature. The heat energy is used for driving operation, lithium bromide solution or other solution with strong water absorbability and the like can be used as an absorbent, water or aqueous solution is used as a refrigerant, heat is extracted from a low-grade heat source, medium-temperature and high-temperature hot water or steam meeting the requirements of a process or heating is prepared, waste heat recycling is realized, and heat energy is conveyed from low temperature to high temperature.

The absorption heat pump optionally further comprises heat exchanger suction devices, canned pumps (solution pump and refrigerant pump), etc. The air extractor extracts noncondensable gases such as air in the unit and keeps the unit in a high vacuum state all the time.

The specific structure of other conventional components related to the absorption heat pump belongs to the conventional technology, and is not described herein.

The lithium bromide solution can be changed into other solutions with strong water absorption, such as ammonia water and the like.

The surface type heat exchanger refers to a heat exchanger, wherein cold side medium and hot side medium are not in direct contact, but indirectly exchange heat through wall surfaces such as heat exchange tube walls or heat exchange plate walls, such as a tube type heat exchanger, a plate type heat exchanger, a heat tube type heat tube hybrid heat exchanger and the like, and the heat exchange process of the heat tube type heat exchanger is that the hot side medium transfers heat to an intermediate medium in a heat tube through a heat tube hot section tube wall, and the intermediate medium transfers heat to the cold side medium through the heat tube cold section tube wall.

Communication as described herein, including direct communication and indirect communication;

herein, optionally, means that it may be selected, e.g., with or without, being provided, in some way or not.

The sequential arrangement, sequential communication, etc. of the various devices or components described herein relate to sequential expressions, and do not exclude the case where other devices or components are disposed between two devices or components that are sequentially adjacent.

Description of the drawings:

FIG. 1 is a schematic diagram of an embodiment of a boiler flue gas waste heat recovery system of the present invention; the method comprises the steps of carrying out a first treatment on the surface of the

FIG. 1-1 is a schematic diagram of another connection mode structure of a flue heat exchanger in a boiler flue gas waste heat recovery system of the present invention;

FIGS. 1-2 are schematic diagrams of another connection mode structure of a bypass economizer in the boiler flue gas waste heat recovery system of the present invention;

FIG. 2 is a schematic diagram of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 3 is a schematic diagram of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 3-1 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 3-2 is a schematic diagram of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 3-3 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 4 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 4-1 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 4-2 is a schematic diagram of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 5 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 6 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 7 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 8 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 9 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 9-1 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 9-2 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

fig. 9-3 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 9-4 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 9-5 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 9-6 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 9-7 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 9-8 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 9-9 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 9-10 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 10 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 10-1 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 10-2 is a schematic diagram of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 10-3 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIGS. 10-4 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 10-5 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 11 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 11-1 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 11-2 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIG. 11-3 is a schematic diagram of another embodiment of a boiler flue gas waste heat recovery system of the present invention;

FIGS. 11-4 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 11-5 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 11-6 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 11-7 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIGS. 11-8 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention;

FIG. 12 is a schematic diagram of a configuration of one embodiment of a desulfurizing tower and a spray tower in the boiler flue gas waste heat recovery and utilization system of the present invention;

FIG. 13 is a schematic view of a structure of an embodiment of a liquid collecting device in the boiler flue gas waste heat recovery system of the present invention;

FIGS. 13a and 13b are schematic structural views of an embodiment of a guide vane;

FIG. 13-1 is a schematic view of another embodiment of a liquid collection device;

FIG. 13-2 is a schematic view of another embodiment of a liquid collection device;

13-3 are schematic structural views of another embodiment of a liquid collection device in some embodiments of the boiler flue gas waste heat recovery system of the present invention;

13-4 are schematic structural views of one embodiment of an air lift cap of a liquid collection device;

FIG. 14 is a schematic view of another embodiment of a desulfurizing tower, a spray tower in some embodiments of the boiler flue gas waste heat recovery system of the present invention;

fig. 15 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

Reference numerals illustrate:

1, a boiler;

1-1 boiler fuel inlet;

1-2 a boiler air supply inlet;

1-3 boiler flue gas outlets;

1-4 boiler steam outlets;

1-5 boiler working medium water inlets;

15 by-pass economizer;

15-1 by-pass economizer flue gas inlet;

15-2 by-pass economizer flue gas outlet;

15-3 bypass economizer working medium water inlet;

15-4 bypass economizer working medium water outlet;

15a first stage bypass heat exchange module;

15a-2 a flue gas outlet of the first-stage bypass heat exchange module;

15a-3 working medium water inlet of the first-stage bypass heat exchange module;

15b second stage bypass heat exchange module;

15b-1 a flue gas inlet of a second-stage bypass heat exchange module;

15-8 bypass flue gas control baffle

30C a first bypass deaerator;

32C a first bypass feed pump;

2 an air preheater;

2-1 an air preheater flue gas inlet;

2-2 an air preheater flue gas outlet;

2-3 air supply inlet of air preheater;

2-4 air supply outlets of the air preheater;

22 flue heat exchanger;

a flue gas inlet of a 22-1 flue heat exchanger;

a flue gas outlet of the 22-2 flue heat exchanger;

22-3 flue heat exchanger water inlet;

22-4 flue heat exchanger water outlet;

22a first stage flue heat exchange module;

22a-2 a flue gas outlet of the first-stage flue heat exchange module;

22a-3 working medium water inlet of the first-stage flue heat exchange module;

22b a second stage flue heat exchange module;

22b-1 a flue gas inlet of a second stage flue heat exchange module;

22b-4 working medium water outlet of the second-stage flue heat exchange module;

6 a desulfurizing tower;

6-1 of a desulfurizing tower body;

6-2 slurry circulation pump;

6-3 slurry tanks;

6-4 flue gas outlets of the desulfurizing tower;

6-5 flue gas inlets of the desulfurizing tower;

6-6, a desulfurizing tower spraying device;

7, a chimney;

8, an air blower;

8-1 blower inlet;

8-2 and an air supply outlet of the blower;

9, an air supply heater;

9-1 air supply inlet of air supply heater;

9-2 an air supply outlet of an air supply heater;

9-3 a hot medium water inlet of an air supply heater;

9-4 a hot medium water outlet of the air supply heater;

12 a spray tower;

12-1 a flue gas inlet of a spray tower;

12-2 a flue gas outlet of the spray tower;

12-3 a spray tower heating medium water inlet;

12-4 a spray tower heating medium water outlet;

12-5 a spray tower water receiving device;

12-6 spraying tower water distribution device;

12-7 liquid collecting devices;

12-8 of a liquid collecting chassis;

12-9 liters of air pipes;

12-10 liters of air cap;

12-11 vent holes;

12-12 swirlers;

12-13 liter gas channels;

12-14 water blocking edges;

12-15 demisting pipes;

12-16 filler layers;

25 steam turbines;

25-1 steam inlet of steam turbine;

25-2 steam turbine steam outlets;

25-5 high-pressure steam extraction outlet of steam turbine;

25-4 and a low-pressure steam extraction outlet of the steam turbine;

27, a condenser;

27-1 condenser steam inlet;

27-2 and a condenser working medium water outlet;

26, a condensate pump;

26-1 condensate pump inlet;

26-2 condensate pump outlet;

29 low pressure heater;

29-1 working medium water inlet of low-pressure heater;

29-2 working medium water outlet of low-pressure heater;

29-3 a low pressure heater extraction inlet;

a 30 deaerator;

30-1 working medium water inlet of deaerator;

30-2 working medium water outlet of deaerator;

32 a water feed pump;

32-1 feed pump inlet;

32-2 a feed pump outlet;

31 high pressure heater;

31-1 working medium water inlet of high-pressure heater;

31-2 working medium water outlet of high-pressure heater;

31-3 a high pressure heater steam extraction inlet;

28 a first low pressure heater;

36 raw water users;

35 raw water source device;

60 dust collectors;

61, induced draft fan;

90-absorption heat pump;

91-an evaporator;

91-1 low temperature heat source inlet of evaporator;

91-2 low temperature heat source outlet of evaporator;

91-3 evaporator refrigerant water inlet;

91-4 evaporator refrigerant vapor outlet;

92-absorber;

92-1 absorber cold water inlet;

a 92-2 absorber cold water outlet;

92-3 absorber refrigerant vapor inlet;

92-4 absorber concentrated absorbent solution inlet;

92-5 absorber lean absorbent solution outlet;

93-generator;

93-1 generator high temperature heat source inlet;

93-2 generator high temperature heat source outlet;

93-3 generator lean absorbent solution inlet;

93-4 generator concentrated absorbent solution outlet;

93-5 generator refrigerant vapor outlet;

94-a condenser;

94-1 condenser cooling water inlet;

94-2 condenser cooling water outlet

94-3 condenser refrigerant vapor inlet;

94-4 condenser refrigerant water outlet;

80 a first supply air heater;

80-1 a first supply air heater supply air inlet;

80-2 a first supply air heater supply air outlet;

80-3 a first air supply heater heating medium water inlet;

80-4 a first air supply heater heating medium water outlet;

a second supply air heater 100;

100-1 a second supply air heater supply air inlet;

100-2 a second air supply heater air supply outlet;

100-3 a second supply air heater cold water inlet;

100-4 second air supply heater cold water outlet.

40-a first absorption heat pump;

41-a first evaporator;

41-1 a first evaporator low temperature heat source inlet;

41-2 a first evaporator low temperature heat source outlet;

41-3 a first evaporator refrigerant water inlet;

41-4 a first evaporator refrigerant vapor outlet;

42-a first absorber;

42-1 a first absorber cold water inlet;

42-2 a first absorber cold water outlet;

42-3 a first absorber refrigerant vapor inlet;

42-4 a first absorber concentrated absorbent solution inlet;

42-5 a first absorber lean absorbent solution outlet;

43-a first generator;

43-1 first generator high temperature heat source inlet;

43-2 a first generator high temperature heat source outlet;

43-3 first generator lean absorbent solution inlet;

43-4 first generator concentrated absorbent solution outlet;

43-5 a first generator refrigerant vapor outlet;

44-a first condenser;

44-1 a first condenser cooling water inlet;

44-2 first condenser cooling water outlet

44-3 a first condenser refrigerant vapor inlet;

44-4 first condenser refrigerant water outlet.

Detailed Description

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a schematic structural view of an embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 1, the boiler flue gas waste heat recycling system includes: a boiler 1, a bypass economizer 15, an air preheater 2, a flue heat exchanger 22, a desulfurizing tower 6, a chimney 7, a blower 8, and a blower heater 9; wherein,,

the boiler 1 is provided with a fuel inlet 1-1, a boiler air supply inlet 1-2 and a boiler flue gas outlet 1-3;

the bypass coal-saving device 15 is provided with a bypass coal-saving device smoke inlet 15-1, a bypass coal-saving device smoke outlet 15-2, a bypass coal-saving device working medium water inlet 15-3 and a bypass coal-saving device working medium water outlet 15-4;

the air preheater 2 is provided with an air preheater flue gas inlet 2-1, an air preheater flue gas outlet 2-2, an air preheater air supply inlet 2-3 and an air preheater air supply outlet 2-4;

The flue heat exchanger 22 is provided with a flue heat exchanger flue gas inlet 22-1, a flue heat exchanger flue gas outlet 22-2, a flue heat exchanger working medium water inlet 22-3 and a flue heat exchanger working medium water outlet 22-4; optionally, the flue heat exchanger 22 is a dividing wall heat exchanger;

the desulfurizing tower 6 includes: a desulfurizing tower body 6-1 and a slurry circulating pump 6-2; the bottom of the desulfurizing tower body 6-1 is provided with a slurry pool 6-3; the lower part of the desulfurizing tower body 6-1 is provided with a desulfurizing tower flue gas inlet 6-5, and the upper part of the desulfurizing tower body is provided with a desulfurizing tower flue gas outlet 6-4; a desulfurizing tower spraying device 6-6 is arranged between the desulfurizing tower flue gas inlet 6-5 and the desulfurizing tower flue gas outlet 6-4, the desulfurizing tower spraying device 6-6 is directly or indirectly communicated with the slurry circulating pump 6-2, and the slurry circulating pump 6-2 is directly or indirectly communicated with the slurry pool 6-3; optionally, a desulfurizing tower demister 6-7 is arranged between the desulfurizing tower spraying device 6-6 and the desulfurizing tower flue gas outlet 6-4;

the blower 8 is provided with a blower inlet 8-1 and a blower outlet 8-2;

the air supply heater 9 is provided with an air supply heater air supply inlet 9-1, an air supply heater air supply outlet 9-1, an air supply heater working medium water inlet 9-4 and an air supply heater working medium water outlet 9-5;

The boiler flue gas outlet 1-3 is simultaneously communicated with the air preheater flue gas inlet 2-1 and the bypass economizer flue gas inlet 15-1 directly or indirectly; the air preheater flue gas outlet 2-2 and the bypass economizer flue gas outlet 15-2 are both directly or indirectly communicated with the flue heat exchanger flue gas inlet 22-1; the flue gas outlet 22-2 of the flue heat exchanger is directly or indirectly communicated with the flue gas inlet 6-5 of the desulfurizing tower; the flue gas outlet 6-4 of the desulfurizing tower is directly or indirectly communicated with the chimney 7;

the blower outlet 8-2 is directly or indirectly communicated with the blower inlet 9-1 of the blower heater; the air supply outlet 9-2 of the air supply heater is directly or indirectly communicated with the air supply inlet 2-3 of the air preheater; the air preheater air supply outlet 2-4 is directly or indirectly communicated with the boiler air supply inlet 1-2;

the working medium water outlet of the air supply heater is directly or indirectly communicated with the working medium water inlet 22-3 of the flue heat exchanger; the flue heat exchanger working medium water outlet 22-4 is directly or indirectly communicated with the air supply heater working medium water inlet 9-3;

the working process is as follows:

fuel is sent into a hearth of the boiler 1 through a boiler fuel inlet 1-1, an air blower 8 sends air into the hearth of the boiler 1 through an air preheater 2 and a boiler air supply inlet 1-2, the fuel burns to release heat, and flue gas generated by combustion flows out of the boiler 1 through a boiler flue gas outlet 1-3; then a part of flue gas is sent into the air preheater 2 through the flue gas inlet 2-1 of the air preheater, the air supply from the air supply outlet 8-2 of the air feeder is heated, and the flue gas and the air supply exchange heat and cool down and then flow out of the air preheater 2 through the flue gas outlet 2-2 of the air preheater; the other part of the flue gas enters a flue gas channel of the bypass economizer 15 through a flue gas inlet 15-1 of the bypass economizer, exchanges heat with working medium water in a working medium water channel of the bypass economizer 15, cools down, and flows out of the bypass economizer 15 through a flue gas outlet 15-2 of the bypass economizer; the flue gas from the air preheater flue gas outlet 2-2 and the flue gas from the bypass economizer flue gas outlet 15-2 enter the flue gas channel of the flue heat exchanger 22 directly or indirectly through other equipment (such as a dust collector or/and an induced draft fan) through the flue heat exchanger flue gas inlet 22-1, heat (including heating through heat exchange tube walls or heat exchange plate walls, or heating through heat exchange tube walls or heat exchange plate walls and an intermediate medium, etc. the same applies below) the working medium water flowing through the flue heat exchanger working medium water channel. When the flue heat exchanger 22 is a heat pipe heat exchanger (one of the partition wall heat exchangers), the heat exchange process is as follows: the flue gas flowing through the flue heat exchanger 22 flue gas channel transfers the heat of the flue gas to an intermediate medium, such as water, in the heat pipe through the heat pipe heat section pipe wall of the flue heat exchanger 22, the intermediate medium is heated and evaporated to be in a gaseous state under the vacuum condition in the heat pipe, the gaseous intermediate medium in the heat pipe transfers the heat to the heat pipe cold section, and the heat is transferred to working medium water outside the heat pipe through the heat pipe cold section pipe wall. The flue gas flows out of the flue gas outlet 22-2 of the flue heat exchanger after being cooled, and then directly flows into the flue gas inlet 6-5 of the desulfurizing tower or indirectly flows into the desulfurizing tower 6 through other equipment (such as a dust remover or/and a draught fan);

The flue gas enters the desulfurizing tower 6 from the desulfurizing tower flue gas inlet 6-5 and flows through the desulfurizing tower spraying device 6-6, the optional desulfurizing tower demister 6-7 and the desulfurizing tower flue gas outlet 6-4 from bottom to top, the desulfurizing slurry in the slurry tank 6-3 enters the desulfurizing tower spraying device 6-6 under the driving of the slurry circulating pump 6-2, the desulfurizing tower spraying device 6-6 sprays the desulfurizing slurry into the flue gas from top to bottom, the flue gas and the desulfurizing slurry exchange heat and transfer mass in a countercurrent manner, the flue gas is optionally defogged through the desulfurizing tower demister 6-7 in a saturated state or a nearly saturated state after being exchanged and desulfurized, flows out of the desulfurizing tower 6 through the desulfurizing tower flue gas outlet 6-4 and is discharged into the atmosphere through the chimney 7.

Working medium water flows through a working medium water channel of the flue heat exchanger through a working medium water inlet 22-3 of the flue heat exchanger, the working medium water and flue gas absorb the waste heat of the flue gas through heat exchange to rise in temperature, then enters the working medium water channel of the air supply heater 9 through a working medium water outlet 22-4 of the flue heat exchanger and a working medium water inlet 9-3 of the air supply heater, the temperature of the working medium water is reduced after the working medium water heats air flowing through the air supply channel of the air supply heater 9, then flows out through a working medium water outlet 9-4 of the air supply heater, and then returns to the working medium water inlet 22-3 of the flue heat exchanger for recycling; the air supply enters an air supply channel of the air supply heater 9 through an air supply heater air supply inlet 9-1 under the drive of an air feeder 8, is heated and warmed by working medium water from a flue heat exchanger 22, flows out of the air supply heater 9 through an air supply heater air supply outlet 9-2, enters the air preheater 2 through an air preheater air supply inlet 2-3, is further heated and warmed by flue gas from a boiler flue gas outlet 1-3, flows out of the air preheater 2 through an air preheater air supply outlet 2-4, and enters a boiler hearth through the boiler air supply inlet 1-2;

Working medium water from the flue heat exchanger heats air flowing through the air supply heater 9, and the air supply with the temperature increased is sent to the hearth of the boiler 1 after being further heated by the air preheater 2, so that the combustion efficiency of the boiler 1 can be further improved, and the waste heat of flue gas is recovered and sent to the hearth of the boiler 1, so that the fuel consumption can be equivalently saved, and the high-efficiency utilization of the waste heat of the flue gas is realized. Because the air preheater 2 has higher heat exchange efficiency, and the flow rate and heat capacity of the flue gas flowing through the air preheater 2 are far greater than those of the air supplied through the air preheater 2, the temperature difference (end difference) between the flue gas temperature of the flue gas inlet 2-1 of the air preheater and the air supply temperature of the air supply outlet 2-4 of the air preheater is small. In general, the increase in the air supply temperature of the air inlet 2-3 of the air preheater results in less increase in the air supply temperature of the air outlet 2-4 of the air preheater, i.e., less heat is eventually transferred to the boiler furnace by the increase in the air supply temperature of the air outlet 9-2 of the air heater, most of the heat is converted into heat energy of flue gas at the flue gas outlet of the air preheater, and the heat energy is converted into heat equivalent flue gas temperature increase due to the unchanged flue gas amount. As the temperature of the air supply entering the air preheater 2 is increased, the temperature of the smoke at the outlet of the air preheater 2 is increased, the smoke temperature at the smoke inlet 22-1 of the flue heat exchanger is increased, the waste heat of the smoke absorbed by working medium water flowing through the flue heat exchanger 22 is increased, the temperature is increased, and after the working medium water flows out of the flue heat exchanger 22, the air supply heater 9 is used for heating and supplying air, the air supply temperature is increased, and the temperature of the smoke at the outlet of the air preheater is further increased; the circulation is that the temperature of the flue gas at the outlet of the air preheater 2 is continuously increased, and the temperature of the working medium water at the working medium water outlet 22-4 of the flue heat exchanger is also continuously increased until the temperature of the working medium water at the working medium water outlet 22-4 of the flue heat exchanger reaches a higher level after the heat leaving the system is equal to the heat entering the system, namely, the heat is balanced. The low-temperature flue gas waste heat at the outlet of the air preheater 2 is converted into high-temperature flue gas heat through the flue heat exchanger 22, the air supply heater 9 and the air preheater 2, the temperature of the inlet flue gas of the flue heat exchanger 22 is increased, the temperature of working medium water at the working medium water outlet 22-4 of the flue heat exchanger is also increased, and therefore the low-temperature flue gas waste heat at the outlet of the air preheater 2 is converted into higher-temperature flue gas heat, and the temperature of the working medium water at the working medium water outlet 22-4 of the flue heat exchanger is further increased.

On the basis of the above, in order to convert the low-grade flue gas waste heat into heat energy with higher temperature, a part of flue gas flowing through the air preheater 2 is separated and flows into a flue gas channel of the bypass economizer 15. Under the condition that the smoke temperature of the smoke outlet 2-2 of the air preheater and the air supply temperature of the air supply outlet 2-4 of the air preheater are kept unchanged, the heat of the smoke which is split into the smoke channel of the bypass economizer 15 is equal to the heat which is transmitted to the air supply by the air supply heater 9 (the heat dissipation loss and the secondary factors are ignored), but the temperature is the smoke temperature of the smoke inlet 2-1 of the air preheater. In general, the smoke temperature of the smoke outlet 2-2 of the air preheater is about 120 ℃, the smoke temperature of the smoke inlet 2-1 of the air preheater is about 300 ℃, the heat is equal, the heat energy temperature and the quality are greatly improved, and the working medium water temperature of the working medium water outlet 15-4 of the bypass economizer can also be improved. Therefore, by the flue heat exchanger 22, the air supply heater 9, the air preheater 2 and the bypass economizer 15, the low-temperature flue gas waste heat from the air preheater flue gas outlet 2-2 can be converted into high-temperature heat energy with equal heat (neglecting secondary factors such as heat dissipation) and the utilization value and the utilization efficiency are greatly improved. The low-grade smoke energy after the air preheater is converted into higher-grade heat energy, and the temperature of the working medium water at the working medium water outlet 15-4 of the bypass economizer can be increased. Therefore, by the flue heat exchanger 22, the air supply heater 9, the air preheater 2 and the bypass economizer 15, the low-temperature flue gas waste heat from the air preheater flue gas outlet 2-2 can be converted into high-temperature heat energy with equal heat (neglecting secondary factors such as heat dissipation) and higher temperature, and the utilization value and the utilization efficiency are greatly improved.

When the heat transferred to the air supply through the air supply heater 9 is ignored and finally distributed into the hearth of the boiler 1 and other secondary factors, the heat transferred to the air supply by the air supply heater 9 is converted into the equal heat to be converted into the increase of the flue gas temperature of the flue gas outlet 2-2 of the air preheater or the increase of the bypass flue gas flow of the bypass economizer 15, namely the heat and the temperature of the working medium water outlet 22-4 of the flue heat exchanger or the heat and the temperature of the working medium water outlet 15-4 of the bypass economizer. The heat transferred to the air supply by the air supply heater 9 can be controlled to be converted into the proportion of the temperature rise of the flue gas of the air preheater flue gas outlet 2-2 and the increase of the bypass flue gas flow of the bypass economizer 15 by means of adjusting the bypass flue gas flow entering the bypass economizer flue gas inlet 15-1, namely, the proportion of the heat and the temperature rise of the working medium water of the flue heat exchanger working medium water outlet 22-4 and the heat and the temperature rise of the working medium water of the bypass economizer working medium water outlet 15-4.

The energy saving effect is better when accounting for the part of the heat transferred to the supply air by the supply air heater 9 that is eventually distributed into the furnace of the boiler 1.

In addition, the bypass economizer 15 is arranged to shunt a part of bypass flue gas from the flue gas entering the air preheater 2, so that the system resistance can be greatly reduced, the flue resistance increased by a part of the flue heat exchanger 22 can be offset, and the power consumption of the induced draft fan can be reduced. Setting the pressure difference of inlet and outlet flue gas of the air preheater 2 as U, the flue gas flow as Q, and the resistance of the air preheater as R, wherein R=U/Q; after the technology of the invention is adopted, the bypass flue gas flow of the air preheater 2 which is shunted to the bypass economizer 15 is Q1, and the flue gas pressure difference at the inlet and the outlet of the air preheater 2 is changed into U1= (Q-Q1) R. It can be seen that the reduction of the flue gas flow of the air preheater can greatly reduce the pressure difference between the flue gas inlet and the flue gas outlet of the air preheater.

The air supply temperature of the air supply inlet 2-3 of the air preheater is increased, so that the problems of low-temperature corrosion and the like of the cold end of the air preheater can be effectively solved, and the problems of deposition blockage of ammonium bisulfate and the like of the air preheater 2 can be effectively solved: at present, most boiler units are provided with a denitration system, when the boiler load is low and the flue gas temperature is low, the efficiency of the denitration system is reduced, the ammonia spraying amount is required to be increased, and excessive ammonia gas reacts with sulfide in the flue gas to generate ammonium bisulfate. As the temperature of the flue gas in the air preheater gradually decreases, ammonium bisulfate changes from a gaseous state to a nasal mucus state in the air preheater 2 to adhere to dust, and when the temperature decreases below the solidification point temperature of the ammonium bisulfate, the ammonium bisulfate is deposited on heat exchange elements of the air preheater 2, thereby causing corrosion and blockage of the air preheater 2 and seriously affecting the operation of the air preheater. The system improves the air supply temperature of the air supply inlet 2-3 of the air preheater, and can effectively avoid the problems of corrosion and blockage of the air preheater 2 caused by ammonium bisulfate. The method can be used for improving the flexibility of the thermal power plant, reducing the lowest stable load of the unit and improving the peak shaving capacity.

Optionally, a dust remover or/and an induced draft fan (not shown in the figure) is connected in series on a flue gas channel directly or indirectly communicated with the flue gas inlet 22-1 or the flue gas outlet 22-2 of the flue heat exchanger. The flue heat exchanger may be connected in series at any position of the flue gas channel between the air preheater and the desulfurizing tower. The dust remover can remove part of dust in the flue gas; the induced draft fan is used for sucking the flue gas in the boiler furnace and sending the flue gas to a chimney.

Optionally, the bypass economizer working medium water outlet 15-4 is also in communication with a hot user (not shown in the figures).

Optionally, the flue heat exchanger 22 is a tubular heat exchanger or a heat pipe heat exchanger;

optionally, the flue heat exchanger 22 is a series connection of a heat pipe heat exchanger and a tubular heat exchanger, and the heat pipe heat exchanger is arranged at the inlet of the flue heat exchanger 22, that is, at the windward position of the flue gas flow direction. The leakage quantity of the heat pipe heat exchanger after abrasion leakage is only the water quantity in a single heat pipe, so that a large quantity of leakage is avoided, and large-area ash sticking and blocking are avoided.

Optionally, a first desulfurizing tower (not shown in the figure) is connected in series on a flue which is directly or indirectly communicated with the desulfurizing tower flue gas outlet 6-5 or the desulfurizing tower flue gas outlet 6-4;

optionally, the bypass economizer 15 has two or more heat exchange modules and a series/parallel switching structure thereof, and the connection manner of the heat exchange modules of the bypass economizer 15 can be switched. If the high-temperature driving heat source is required to have high temperature, adopting a serial structure, wherein the flow rate of the working medium water in the working medium water channel of the bypass economizer 15 is small; if the temperature of the high-temperature driving heat source is required to be low, a parallel structure is adopted, and at the moment, the flow rate of the working medium water in the working medium water channel of the bypass economizer 15 is large.

Optionally, a working medium water pump is arranged on a working medium water channel which is directly or indirectly communicated with the working medium water inlet 22-3 of the flue heat exchanger or the working medium water outlet 22-4 of the flue heat exchanger;

optionally, a bypass feed pump or/and a bypass deaerator or/and a buffer water tank (not shown in the figure) is/are arranged on the working fluid water channel directly or indirectly communicated with the working fluid water inlet 15-3 of the bypass economizer. Wherein the bypass feed water pump is used for driving working medium water into the bypass economizer 15; the bypass deaerator is used for removing oxygen in the working medium water so as to prevent the working medium water from corroding a working medium water channel; the buffer water tank provides buffer capacity for the bypass feed pump, and ensures the operation safety of the water pump.

Fig. 1-1 is a schematic structural diagram of another connection mode of a flue heat exchanger in the boiler flue gas waste heat recovery system of the present invention. As shown in fig. 1-1, unlike fig. 1, the flue heat exchanger 22 includes a first stage flue heat exchange module 22a and a second stage flue heat exchange module 22b connected in series; the first-stage flue heat exchange module 22a is provided with a flue heat exchanger flue gas inlet 22-1, a first-stage flue heat exchange module flue gas outlet 22a-2, a first-stage flue heat exchange module working medium water inlet 22a-3 and a flue heat exchanger working medium water outlet 22-4; the second-stage flue heat exchange module 22b is provided with a second-stage flue heat exchange module flue gas inlet 22b-1, a flue heat exchanger flue gas outlet 22-2, a flue heat exchanger working medium water inlet 22-3 and a second-stage flue heat exchange module working medium water outlet 22b-4; the flue gas outlet 22a-2 of the first-stage flue heat exchange module is directly or indirectly communicated with the flue gas inlet 22b-1 of the second-stage flue heat exchange module through a dust remover 60 or/and an induced draft fan 61, and the working medium water outlet 22b-4 of the second-stage flue heat exchange module is directly or indirectly communicated with the working medium water inlet 22a-3 of the first-stage flue heat exchange module.

The purpose of adopting the structure is mainly to match the relevant parameters of the flue heat exchanger with the parameters of the flue gas at the inlet of the dust remover. If the temperature of the working medium water at the working medium water inlet 22-3 of the flue heat exchanger is too low, the smoke temperature at the inlet of the dust remover 60 is too low, and the low-temperature corrosion of the dust remover is possibly caused; if the flue heat exchanger 22 recovers the waste heat of the flue gas, the low temperature corrosion of the dust remover can be caused when the flue heat exchanger outlet flue temperature is too low. In this case, the stack heat exchanger 22 is divided into a first stage stack heat exchange module 22a and a second stage stack heat exchange module 22b, and is disposed before and after the dust remover. The flue gas firstly passes through the first-stage flue heat exchange module 22a, then passes through a dust remover 60 or/and an induced draft fan 61, and then enters the second-stage flue heat exchange module 22b; the working medium water is heated by the second-stage flue heat exchange module 22b and then enters the first-stage flue heat exchange module 22a for continuous heating.

Fig. 1-2 are schematic structural diagrams of another connection mode of a bypass economizer in the boiler flue gas waste heat recovery system. As shown in fig. 1-2, the bypass economizer 15 includes a first stage bypass heat exchange module 15a and a second stage bypass heat exchange module 15b connected in series; the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet 15-1, a first-stage bypass heat exchange module flue gas outlet 15a-2, a first-stage bypass heat exchange module working medium water inlet 15a-3 and a bypass economizer working medium water outlet 15-4; the second-stage bypass heat exchange module 15b is provided with a second-stage bypass heat exchange module smoke inlet 15b-1, a bypass economizer smoke outlet 15-2, a bypass economizer working medium water inlet 15-3 and a second-stage bypass heat exchange module working medium water outlet 15b-4; the first-stage bypass heat exchange module flue gas outlet 15a-2 is directly or indirectly communicated with the second-stage bypass heat exchange module flue gas inlet 15b-1, and the second-stage bypass heat exchange module working medium water outlet 15b-4 is directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet 15a-3 through a first bypass deaerator 30C and/or a first bypass water feed pump 32C;

The working process is as follows:

the flue gas from the boiler flue gas outlet 1-3 passes through the first-stage bypass heat exchange module 15a and the second-stage bypass heat exchange module 15b in sequence, exchanges heat with working medium water, cools down and then is sent to the flue heat exchanger 22; working medium water is firstly subjected to heat exchange and temperature rise between the second-stage bypass heat exchange module 15b and the flue gas, is sent to the first bypass deaerator 30C for deaeration, is boosted by the first bypass feed pump 32C, and is sent to the first-stage bypass heat exchange module 15a for further heat exchange and temperature rise between the working medium water and the flue gas with higher temperature. The working medium water temperature node in the working medium water heating process, namely the working medium water outlet 15b-4 of the second bypass heat exchange module, is used for deoxidizing and pressurizing to meet the system operation requirement.

The second-stage bypass heat exchange module working fluid water outlet 15b-4 may also be directly or indirectly connected to the first-stage bypass heat exchange module working fluid water inlet 15a-3 without passing through the first bypass deaerator 30C and/or the first bypass feed pump 32C. Namely, the working medium water is firstly subjected to heat exchange and temperature rise with the flue gas in the second-stage bypass heat exchange module 15b and then is sent to the first-stage bypass heat exchange module 15a to be subjected to heat exchange and temperature rise with the flue gas with higher temperature.

Optionally, a bypass header (not shown) is connected in series to the working fluid water channel between the working fluid water outlet 15b-4 of the second-stage bypass heat exchange module and the working fluid water inlet 15a-3 of the first-stage bypass heat exchange module.

Fig. 2 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 2, on the basis of fig. 1, a spray tower 12 is connected in series between the desulfurizing tower 6 and the chimney 7; a second air supply heater 100 is arranged on an air supply channel which is directly or indirectly communicated with the air supply inlet 9-1 of the air supply heater;

the spray tower 12 is provided with a spray tower flue gas inlet 12-1, a spray tower flue gas outlet 12-2, a spray tower heat medium water inlet 12-3 and a spray tower heat medium water outlet 12-4. The bottom of the spray tower is provided with a spray tower water receiving device 12-5. A spray tower water distribution device 12-6 for heating medium water is arranged between the spray tower flue gas inlet 12-1 and the spray tower flue gas outlet 12-2. The spray tower water distribution device 12-6 is communicated with the spray tower heat medium water inlet 12-3, and the spray tower water receiving device 12-5 is communicated with the spray tower heat medium water outlet 12-4;

the second air supply heater 100 is provided with a second air supply heater air supply inlet 100-1, a second air supply heater air supply outlet 100-2, a second air supply heater heat medium water inlet 100-3 and a second air supply heater heat medium water outlet 100-4;

the flue gas outlet 6-4 of the desulfurizing tower is directly or indirectly communicated with the flue gas inlet 12-1 of the spraying tower; the spray tower flue gas outlet 12-2 is directly or indirectly communicated with the chimney 7; the spray tower heating medium water outlet 12-4 is directly or indirectly communicated with the second air supply heater heating medium water inlet 100-3; the second air supply heater heat medium water outlet 100-4 is directly or indirectly communicated with the spray tower heat medium water inlet 12-3; the second blast heater blast outlet 100-2 communicates directly or indirectly with the blast heater blast inlet 9-1.

The working process is as follows:

the desulfurized saturated or nearly saturated flue gas enters the spray tower 12 through the spray tower flue gas inlet 12-1. The heating medium water from the second air supply heater 100 is conveyed to the spray tower water distribution device 12-6 through the spray tower heating medium water inlet 12-3, the spray tower water distribution device 12-6 distributes the heating medium water into the flue gas, the flue gas and the heating medium water are subjected to mixed heat exchange in the spray tower 12, the saturated flue gas is further cooled, dehumidified and washed, and then the saturated flue gas is discharged into the atmosphere through the spray tower flue gas outlet 12-2 and the chimney 7.

The heat medium water from the spray tower heat medium water outlet 12-4 is directly or indirectly sent to the second air supply heater heat medium water inlet 100-3, enters the heat medium water channel of the second air supply heater 100, and the air supply (air) enters the air supply channel of the second air supply heater 100 through the second air supply heater air supply inlet 100-1 under the driving of the blower 8, the temperature of the heat medium water in the heat medium water channel of the second air supply heater 100 is reduced after the air supply of the air supply channel of the second air supply heater 100 is heated, and then flows out through the heat medium water outlet 100-4 of the second air supply heater, returns to the spray tower heat medium water inlet 12-3 for recycling. The air with the increased temperature flows out through the air outlet 100-2 of the second air supply heater and then is sent to the air supply heater 9 and the air preheater 2 in sequence, and is sent to the hearth of the boiler 1 after further temperature rise.

When the heat transferred to the air supply through the second air supply heater 100 is ignored and finally distributed to part of heat and other secondary factors entering the hearth of the boiler 1, the heat transferred to the air supply by the second air supply heater 100 is converted into the equal heat to increase the temperature of the flue gas at the flue gas outlet 2-2 of the air preheater or increase the bypass flue gas flow of the bypass economizer 15, namely, the working medium water heat of the working medium water outlet 22-4 of the flue heat exchanger or the working medium water heat of the working medium water outlet 15-4 of the bypass economizer is increased, so that the low-grade heat energy of the saturated flue gas after desulfurization is converted into the equal heat high-grade working medium water heat energy through the spray tower 12, the second air supply heater 100, the air preheater 2, the flue heat exchanger 22 or the bypass economizer 15, and the utilization value and utilization efficiency of the heat energy can be improved. The heat transferred to the air supplied by the second air supply heater 100 can be controlled to be converted into the proportion of the rise of the temperature of the flue gas at the flue gas outlet 2-2 of the air preheater and the increase of the bypass flue gas flow of the bypass economizer 15 by adjusting the bypass flue gas flow entering the flue gas inlet 15-1 of the bypass economizer and the like, namely, the proportion of the increase of the water heat and the temperature of the working medium at the working medium water outlet 22-4 of the flue heat exchanger and the increase of the water heat and the temperature of the working medium at the working medium water outlet 15-4 of the bypass economizer is controlled. The energy saving effect is better when accounting for the part of the heat which is finally distributed into the furnace of the boiler 1 by the heat transferred to the air supply by the second air supply heater 100.

The pollutants in the flue gas such as residual desulfurization slurry, sulfur dioxide, sulfur trioxide, fine dust (such as PM 2.5), heavy metals and the like can be further removed through the washing of the large flow and full coverage of the heat medium water; the temperature and the humidity of the flue gas are reduced, and the condensable particles in the flue gas are reduced; the fine mist droplets formed by condensing the water vapor in the flue gas are used as condensation nuclei, and other fine particles can be condensed by condensation to form large particles, so that the removal efficiency is improved; the humidity of the smoke is reduced, the local atmospheric environment can be improved, the possibility of forming aerosol and haze is reduced, and the smoke plume phenomenon of the chimney is further weakened, so that the purpose of whitening the chimney is realized.

In addition, part of water in the saturated flue gas is condensed and separated out, so that the effect of water recovery can be achieved, the part of water is condensed water without chloride ions, after the condensed water is recovered to a system, process water supplementing can be reduced, when the process water contains the chloride ions, the intake of the chloride ions can be reduced, and the treatment cost and the discharge of waste water are reduced, so that further energy and water conservation and discharge reduction of flue gas pollutants and water pollution are realized.

Because the flue gas at the outlet of the desulfurizing tower 6 is desulfurized and dedusted to reach a higher emission standard, the condensed water of the flue gas in the spray tower 12 has higher water quality, and can be sent to the outside of the system for use, and the water balance of the desulfurizing tower 6 is not influenced. As the saturated flue gas temperature at the outlet of the desulfurizing tower 6 is lower, near-zero end difference heat exchange can be realized by adopting mixed heat exchange, and the recovery amount of flue gas waste heat is increased.

The second blast heater 100 has self-adapting and self-adjusting capabilities for stack plume abatement: when the ambient temperature is low, smoke plume phenomenon is aggravated, and the diffusion of smoke pollutants at the outlet of the chimney is worsened; meanwhile, the air temperature of the air supply inlet 100-1 of the second air supply heater is low, the cooling capacity of the second air supply heater 100 to the heat medium water is improved, the temperature of the heat medium water outlet 100-3 of the second air supply heater is reduced, the condensation cooling of the heat medium water to the flue gas in the spray tower 12 is increased, the smoke plume regulating effect of the chimney is enhanced, and pollutants in the flue gas are reduced. And vice versa. When the atmospheric humidity increases, the diffusion of the smoke pollutants at the outlet of the chimney becomes worse, the smoke plume phenomenon is aggravated, meanwhile, the air humidity increases, the specific heat capacity increases, the cooling capacity of the second air supply heater 100 to the heat medium water increases, the temperature of the heat medium water outlet 100-4 of the second air supply heater decreases, the condensation cooling of the smoke is increased, the smoke plume regulating effect of the chimney is enhanced, and the pollutants in the smoke are reduced. And vice versa.

The number of the spray tower heating medium water outlets 12-4 can be one or more; the spray tower heating medium water inlet 12-3 may be one or more.

Optionally, a spray tower demister is arranged on a flue gas channel between the spray tower water distribution device 12-6 and the chimney 7;

Optionally, a heat medium water circulating pump (not shown in the figure) is arranged on the heat medium water pipeline which is directly or indirectly communicated with the spray tower heat medium water outlet 12-4 or the spray tower heat medium water inlet 12-3. The purpose is to provide flowing power for the heat medium water through a heat medium water circulating pump.

Fig. 3 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 3, on the basis of fig. 1, a spray tower 12 and an absorption heat pump 90 are also provided;

the spray tower 12 is provided with a spray tower flue gas inlet 12-1, a spray tower flue gas outlet 12-2, a spray tower heat medium water inlet 12-3 and a spray tower heat medium water outlet 12-4. The bottom of the spray tower is provided with a spray tower water receiving device 12-5. A spray tower water distribution device 12-6 for heating medium water is arranged between the spray tower flue gas inlet 12-1 and the spray tower flue gas outlet 12-2. The spray tower water distribution device 12-6 is communicated with the spray tower heat medium water inlet 12-3, and the spray tower water receiving device 12-5 is communicated with the spray tower heat medium water outlet 12-4. And the heat medium water is scattered into the flue gas through the spray tower water distribution device 12-6, and the flue gas and the heat medium water are subjected to mixed heat exchange.

The absorption heat pump 90 includes an evaporator 91, an absorber 92, a generator (also referred to as a regenerator) 93, and a condenser 94; the evaporator 91 is provided with an evaporator low temperature heat source inlet 91-1, an evaporator low temperature heat source outlet 91-2, an evaporator refrigerant water inlet 91-3 and an evaporator refrigerant water vapor outlet 91-4; the absorber 92 is provided with an absorber cold water inlet 92-1, an absorber cold water outlet 92-2, an absorber refrigerant water vapor inlet 92-3, an absorber rich absorbent inlet 92-4, and an absorber lean absorbent outlet 92-5; the generator 93 is provided with a generator high temperature heat source inlet 93-1, a generator high temperature heat source outlet 93-2, a generator lean absorbent inlet 93-3, a generator rich absorbent outlet 93-4 and a generator refrigerant water vapor outlet 93-5; the condenser 94 is provided with a condenser cooling water inlet 94-1, a condenser cooling water outlet 94-2, a condenser refrigerant water vapor inlet 94-3, and a condenser refrigerant water outlet 94-4.

The evaporator refrigerant water inlet 91-3 communicates directly or indirectly with the condenser refrigerant water outlet 94-4; the evaporator refrigerant vapor outlet 91-4 communicates directly or indirectly with the absorber refrigerant vapor inlet 92-3; the absorber rich absorbent inlet 92-4 communicates directly or indirectly with the generator rich absorbent outlet 93-4; the absorber lean absorbent outlet 92-5 is in direct or indirect communication with the generator lean absorbent inlet 93-3; the generator refrigerant vapor outlet 93-5 communicates directly or indirectly with the condenser refrigerant vapor inlet 94-3. The absorber cold water outlet 92-2 communicates directly or indirectly with the condenser cold water inlet 94-1; the absorption heat pump 90 constitutes a first type of absorption heat pump, i.e. a heat-increasing type of absorption heat pump;

the spray tower 12 is connected in series with a flue gas channel between the flue gas outlet 6-4 of the desulfurizing tower and the chimney 7; the flue gas outlet 6-4 of the desulfurizing tower is directly or indirectly communicated with the flue gas inlet 12-1 of the spraying tower, and the flue gas outlet 12-2 of the spraying tower is directly or indirectly communicated with the chimney 7;

the spray tower heating medium water outlet 12-4 is directly or indirectly communicated with the evaporator low temperature heat source inlet 91-1; the low-temperature heat source outlet 91-2 of the evaporator is directly or indirectly communicated with the spray tower heat medium water inlet 12-3;

The bypass economizer working medium water outlet 15-4 is directly or indirectly communicated with the generator high-temperature heat source inlet 93-1; the high-temperature heat source outlet 93-2 of the generator is directly or indirectly communicated with the working medium water inlet 15-3 of the bypass economizer;

the working process is as follows:

the desulfurized saturated or nearly saturated flue gas enters the spray tower 12 through the spray tower flue gas inlet 12-1. The heat medium water from the low-temperature heat source outlet 91-2 of the evaporator is conveyed to the spray tower water distribution device 12-6 through the spray tower heat medium water inlet 12-3, the spray tower water distribution device 12-6 distributes the heat medium water into the flue gas, the flue gas and the heat medium water are subjected to mixed heat exchange in the spray tower 12, the saturated flue gas is further cooled, dehumidified and washed, and then the saturated flue gas is discharged into the atmosphere through the spray tower flue gas outlet 12-2 and the chimney 7.

The sensible heat of flue gas, the vaporization latent heat of water vapor condensation and the temperature after the reaction heat in the desulfurization process are absorbed by the heat medium water in the spray tower 12, and the heat medium water is directly or indirectly sent to the low-temperature heat source inlet 91-1 of the evaporator through the heat medium water outlet 12-4 of the spray tower after being collected by the water receiving device 12-5 of the spray tower.

The heat medium water from the spray tower heat medium water outlet 12-4 enters the heat exchange tube in the evaporator 91 through the low temperature heat source inlet 91-1 of the evaporator, the evaporator 91 is in a low pressure (such as vacuum) state, the principle that the boiling point of water is low in the low pressure state is utilized, the refrigerant water conveyed by the condenser 94 absorbs the heat of the heat medium water in the heat exchange tube and then evaporates and cools the heat medium water, and meanwhile, the refrigerant water vapor generated by evaporation enters the absorber 92. The cooled heat medium water flows out of the absorption heat pump 90 through the low-temperature heat source outlet 91-2 of the evaporator, returns to the heat medium water inlet 12-3 of the spray tower and enters the water distribution device 12-6 of the spray tower for recycling.

Cold water from a hot user enters the heat transfer tubes of the absorber 92 through the absorber cold water inlet 92-1, and in the absorber 92, the strong water absorption of the lithium bromide concentrated solution (or other absorbent solution) is utilized, the water vapor from the evaporator 91 is absorbed by the concentrated solution from the evaporator 93, and heat is released, the solution temperature is raised, and the solution temperature can be higher than the heat medium water temperature from the spray tower 12. When the solution contacts with the heat transfer pipe of the absorber 92, the cold water in the heat transfer pipe is heated to realize the heat transfer from the low-grade heat of the heat medium water of the spray tower to the cold water, the temperature of the cold water is increased, and the temperature of the cold water can be higher than the temperature of the heat medium water at the low-temperature heat source inlet 91-1 of the evaporator. And then flows out through the absorber cold water outlet 92-2 and then enters the condenser cooling water inlet 94-1, and meanwhile, the lithium bromide concentrated solution is changed into a dilute solution and then is conveyed to the generator 93.

The working medium water with higher temperature from the working medium water outlet 15-4 of the bypass economizer is used as a high-temperature driving heat source, enters the generator 93 through the generator high-temperature heat source inlet 93-1, the lithium bromide dilute solution in the generator 93 from the absorber 92 is heated and concentrated by the working medium water to be concentrated into a concentrated solution, then enters the absorber 92, the working medium water heats and concentrates the lithium bromide dilute solution and simultaneously generates refrigerant water vapor with higher temperature, and the refrigerant water vapor enters the condenser 94; after heat exchange and temperature reduction, the working medium water flows out of the absorption heat pump 90 through the high-temperature heat source outlet 93-2 of the generator and returns to the working medium water inlet 15-3 of the bypass economizer for recycling.

Cold water which is heated by the absorber 92 and is heated up from the absorber cold water outlet 92-2 is taken as cooling water, enters the condenser 94 through the condenser cooling water inlet 94-1, high-temperature refrigerant vapor from the generator 93 exchanges heat with the cooling water in the condenser 94 to release condensation latent heat and condense into refrigerant water, the cooling water absorbs heat and is heated up, and then flows out of the condenser 94 through the condenser cooling water outlet 94-2 and is sent to a hot user for use; the refrigerant water after the condensation of the refrigerant water vapor enters the evaporator 91 to be evaporated, thus circulating.

The cold water from the hot user is heated by the absorber 92 and the condenser 94 in sequence, the heat of the cold water from the condenser cooling water outlet 94-2 is equal to the sum of the heat input from the spray tower heating medium water outlet 12-4 through the evaporator low-temperature heat source inlet 91-1 and the heat input from the bypass economizer working medium water outlet 15-4 through the generator high-temperature heat source inlet 93-1, and the heating medium water low-temperature heat energy from the spray tower heating medium water outlet 12-4 is converted into heat energy with higher temperature. Thus forming a first type of absorption heat pump, namely a heat-increasing absorption heat pump. The cold water from the condenser cooling water outlet 94-2 may be sent to a hot user, such as heating to the outside, etc.

According to the principle of the absorption heat pump, the high temperature drives the temperature of the heat source to rise within a certain range, so that the efficiency of the absorption heat pump can be improved. Therefore, the low-temperature heat energy of the flue gas outlet 2-2 of the air preheater can be equivalently converted into the high-temperature heat energy of the working medium water outlet 15-4 of the bypass economizer, and the high-temperature working medium water of the working medium water outlet 15-4 of the bypass economizer is used as a high-temperature driving heat source of the absorption heat pump 90, so that the working efficiency of the absorption heat pump 90 can be improved, namely, the low-grade flue gas waste heat of the outlet of the desulfurizing tower 6 can be more recovered under the condition that the heat quantity of the flue gas waste heat of the flue gas outlet 2-2 of the air preheater is the same.

In general, the smoke temperature of the smoke outlet 2-2 of the air preheater is about 120 ℃, and the temperature of working medium water from the flue heat exchanger 22 is about 90 ℃; the smoke temperature of the smoke inlet 2-1 of the air preheater is about 300 ℃, and the temperature of working medium water (high-temperature driving heat source) from the working medium water outlet 15-4 of the bypass economizer can reach about 290 ℃ (can be adjusted according to the requirement of the absorption heat pump 90); the saturated flue gas temperature of the flue gas outlet 6-4 of the desulfurizing tower is about 50 ℃, and the temperature of the heat medium water from the spray tower 12 is about 40 ℃ (low temperature heat source); the cold water temperature at the condenser cooling water outlet 94-2 of the absorption heat pump 90 can reach about 80 c (output heat energy). That is, the flue heat exchanger 22, the air supply heater 9 and the bypass economizer 15 are utilized to equally convert the low-temperature flue gas waste heat of the flue gas outlet 2-2 of the air preheater into high-temperature heat energy (which can be adjusted according to the requirement) of about 290 ℃ and serve as a high-temperature driving heat source of the absorption heat pump 90, then the absorption heat pump and the high-temperature driving heat source are utilized to convert the low-temperature heat of the heat medium water which is difficult to utilize and comes from the spray tower into the available medium-temperature heat, and the heat of the cold water of the condenser cooling water outlet 94-2 is equal to the sum of the heat of the working medium water coming from the working medium water outlet 15-4 of the bypass economizer and the heat of the heat medium water coming from the heat medium water outlet 12-4 of the spray tower, so that the increase of the available heat is realized. Compared with the prior art that a high-temperature driving heat source with higher use value is adopted, all heat of the embodiment is from flue gas waste heat, the flue gas waste heat is recovered by the flue gas waste heat, the waste is treated by the waste, the waste is recovered by the waste, and the waste is turned into wealth, so that the flue gas waste heat recovery amount, the energy quality and the utilization efficiency are greatly improved, and the economical efficiency is greatly improved.

The heat medium water is cooled by the evaporator and then is sent to the spray tower 12 for mixed heat exchange of the flue gas. The pollutants in the flue gas such as residual desulfurization slurry, sulfur dioxide, sulfur trioxide, fine dust (such as PM 2.5), heavy metals and the like can be further removed through the washing of the large flow and full coverage of the heat medium water; the temperature and the humidity of the flue gas are reduced, and the condensable particles in the flue gas are reduced; the fine mist droplets formed by condensing the water vapor in the flue gas are used as condensation nuclei, and other fine particles can be condensed by condensation to form large particles, so that the removal efficiency is improved; the humidity of the smoke is reduced, the local atmospheric environment can be improved, the possibility of forming aerosol and haze is reduced, and the smoke plume phenomenon of the chimney is further weakened, so that the purpose of whitening the chimney is realized.

The emission of pollutants is fundamentally reduced while the recovery and utilization efficiency of the waste heat of the flue gas is improved, and the emission of carbon dioxide is included, so that the realization of a carbon neutralization target is facilitated.

Therefore, the embodiment realizes the high-efficiency recovery and the high-efficiency utilization of the waste heat of the flue gas, and simultaneously realizes the water conservation, the deep emission reduction of the flue gas, the near zero emission and the treatment of the flue gas plume.

Optionally, the spray tower heating medium water inlet 12-3 communicates directly or indirectly with raw water source means 35 and the spray tower heating medium water outlet communicates directly or indirectly with raw water user 36. Raw water from the raw water source device 35 enters the spray tower water distribution device 12-6 through the spray tower heat medium water inlet 12-3, the raw water is heated by utilizing flue gas of the spray tower, and the heated raw water is sent to the raw water user 36 through the spray tower heat medium water outlet 12-4 so as to fully utilize the flue gas waste heat and reduce the energy consumption.

Optionally, a spray tower demister (not shown in the figure) is arranged on a flue gas channel between the spray tower water distribution device 12-6 and the chimney 7. The purpose is to further purify the flue gas entering the chimney through a spray tower demister.

Optionally, a high-temperature heat source water pump (not shown in the figure) is arranged on the high-temperature heat source channel which is directly or indirectly communicated with the generator high-temperature heat source inlet 93-1 or the generator high-temperature heat source outlet 93-2. The purpose is to provide flowing power for the high-temperature driving heat source through the high-temperature heat source water pump.

Optionally, the generator high temperature heat source outlet 93-2 is in direct or indirect communication with the bypass economizer working medium water inlet 15-3 through a cooler (not shown in the figures); optionally, the cooler is a generator of other absorption heat pumps or other air supply heaters;

optionally, a cold water pump (not shown) is connected in series to a cold water channel directly or indirectly connected to the condenser cold water outlet 93-2 or the absorber cold water inlet 92-1;

Optionally, a cold water reheater (not shown) is connected in series to the cold water channel in direct or indirect communication with the condenser cooling water outlet 94-2.

Fig. 3-1 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 3-1, the difference from fig. 3 is that the generator high temperature heat source inlet 93-1 is directly or indirectly connected with the flue heat exchanger working fluid water outlet 22-4, and the generator high temperature heat source outlet 93-2 is directly or indirectly connected with the flue heat exchanger working fluid water inlet 22-3.

The working process is as follows:

the working medium water from the working medium water outlet 22-4 of the flue heat exchanger is used as a high-temperature driving heat source of the absorption heat pump 90, enters the generator 93 through the generator high-temperature heat source inlet 93-1 to exchange heat and cool, flows out through the generator high-temperature heat source outlet 93-2, and returns to the working medium water inlet 22-3 of the flue heat exchanger for recycling. At this time, the absorption heat pump 90 will be less efficient, but the bypass economizer working fluid water outlet 15-4 will be more available to the heat consumer. The other principle is the same as in fig. 3.

Fig. 3-2 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 3-2, the difference from fig. 3 is that the high temperature heat source channel of the generator 93 is connected in series with the working fluid water channel of the working fluid water outlet 22-4 of the flue heat exchanger and the working fluid water inlet 9-3 of the air supply heater, the working fluid water outlet 22-4 of the flue heat exchanger is directly or indirectly connected with the high temperature heat source inlet 93-1 of the generator, the high temperature heat source outlet 93-2 of the generator is directly or indirectly connected with the working fluid water inlet 9-3 of the air supply heater, and the working fluid water outlet 9-4 of the air supply heater is directly or indirectly connected with the working fluid water inlet 22-3 of the flue heat exchanger.

The working process is as follows:

the working medium water from the working medium water outlet 22-4 of the flue heat exchanger is firstly used as a high-temperature driving heat source to enter the generator 93 for heat exchange and cooling, then is used as a heating heat source to be sent to the air supply heater 9 for heating and air supply, and returns to the flue heat exchanger 22 for continuous recycling after heat exchange and cooling with the air supply. Compared with fig. 3-1, the embodiment can more fully utilize the heat of the working medium water from the flue heat exchanger 22, and can also reduce the temperature of the working medium water at the working medium water inlet 22-3 of the flue heat exchanger and improve the heat exchange efficiency of the flue heat exchanger 22.

Fig. 3-3 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 3-3, the bypass economizer 15 is different from fig. 3 in that it includes a first stage bypass heat exchange module 15a and a second stage bypass heat exchange module 15b connected in series one after the other; the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet 15-1, a first-stage bypass heat exchange module flue gas outlet 15a-2, a first-stage bypass heat exchange module working medium water inlet 15a-3 and a bypass economizer working medium water outlet 15-4; the second-stage bypass heat exchange module 15b is provided with a second-stage bypass heat exchange module smoke inlet 15b-1, a bypass economizer smoke outlet 15-2, a bypass economizer working medium water inlet 15-3 and a second-stage bypass heat exchange module working medium water outlet 15b-4; the first-stage bypass heat exchange module flue gas outlet 15a-2 is directly or indirectly communicated with the second-stage bypass heat exchange module flue gas inlet 15b-1, and the second-stage bypass heat exchange module working medium water outlet 15b-4 is simultaneously directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet 15a-3 and the generator high-temperature heat source inlet 93-1; the high-temperature heat source outlet 93-2 of the generator is directly or indirectly communicated with the working medium water inlet 15-3 of the bypass economizer.

The working process is as follows:

the flue gas from the boiler flue gas outlet 1-3 passes through the first-stage bypass heat exchange module 15a and the second-stage bypass heat exchange module 15b in sequence, exchanges heat with working medium water, cools down and then is sent to the flue heat exchanger 22; the working medium water flows out through a working medium water outlet 15b-4 of the second-stage bypass heat exchange module after heat exchange and temperature rise of the second-stage bypass heat exchange module 15b and the flue gas, and then a part of the working medium water is sent to the first-stage bypass heat exchange module 15a to be subjected to further heat exchange and temperature rise of the flue gas with higher temperature, and then is sent to a heat user; part of the refrigerant is used as a high-temperature driving heat source, enters the generator 93 of the absorption heat pump 90 through the generator high-temperature heat source inlet 93-1, the dilute absorbent solution from the absorber 92 in the generator 93 is heated and concentrated by working medium water to be concentrated into concentrated absorbent solution, then enters the absorber, the dilute absorbent solution is heated and concentrated to generate refrigerant water vapor with higher temperature, and the refrigerant water vapor enters the condenser 94; the working medium water flows out of the absorption heat pump 90 after heat exchange and temperature reduction, and returns to the second-stage bypass heat exchange module 15b for recycling.

Compared with fig. 3-1 and 3-2, the high-temperature driving heat source of the absorption heat pump 90 of the embodiment has higher temperature and higher working efficiency; with respect to fig. 3, the working fluid water of the bypass economizer working fluid water outlet 15-4 of the present embodiment can be used for off-system users, such as for power generation.

Optionally, the working fluid water at the working fluid water outlet 15b-4 of the second-stage bypass heat exchange module is subjected to heat exchange and temperature rise with the flue gas at a higher temperature by passing through a bypass header (not shown in the figure) or by passing through the first bypass deaerator 30C for deaeration or/and passing through the first bypass feed pump 32C for boosting, and then is sent to the first-stage bypass heat exchange module 15 a. The function is that the proper working medium water temperature node in the working medium water heating flow, namely the working medium water outlet 15b-4 of the second-stage bypass heat exchange module, is deoxidized or/and pressurized to meet the system operation requirement.

Fig. 4 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 4, on the basis of fig. 3 or fig. 3-1 or fig. 3-2 (on the basis of fig. 3 in this embodiment), the cold water channel through which the condenser cooling water outlet 94-2 directly or indirectly communicates is connected in series with a cold water reheater 95; the cold water reheater 95 is provided with a cold water reheater cold water inlet 95-1, a cold water reheater cold water outlet 95-2, a cold water reheater heat source inlet 95-3 and a cold water reheater heat source outlet 95-4; the cold water reheater cold water inlet 95-1 communicates directly or indirectly with the condenser cooling water outlet 94-2; the cold water outlet 95-2 of the cold water reheater is directly or indirectly communicated with a hot user; the cold water reheater heat source inlet 95-3 is directly or indirectly communicated with the flue heat exchanger working medium water outlet 22-4; the cold water reheater heat source outlet 95-4 is directly or indirectly communicated with the flue heat exchanger working medium water inlet 22-3.

The working process is as follows: cold water from a condenser cooling water outlet 94-2 enters a cold water channel of the cold water reheater through a cold water inlet 95-1 of the cold water reheater, high-temperature working medium water from a working medium water outlet 22-4 of the flue heat exchanger enters a working medium water channel of the cold water reheater 95 through a heat source inlet 95-3 of the cold water reheater, and after heat exchange and temperature rise, the cold water flows out through the cold water outlet 95-2 of the cold water reheater and is sent to a hot user for use; after the temperature of the working medium water is reduced after heat exchange with cold water, the working medium water flows out through the heat source outlet 95-4 of the cold water reheater and returns to the working medium water inlet 22-3 of the flue heat exchanger for recycling. The purpose is to utilize the flue gas waste heat recovered by the working medium water of the flue heat exchanger 22 to heat the cold water of the cooling water outlet 94-2 of the heating condenser so as to meet the use requirement of the system heat user.

Optionally, a second cooler (not shown) is connected in series between the cold water reheater heat source outlet 95-4 and the flue heat exchanger working fluid water inlet 22-3. Because the working fluid water temperature at the cold water reheater heat source outlet 95-4 is also relatively high, the second cooler may be used to heat the supply air or other user.

Optionally, the cold water reheater 95 is a dividing wall heat exchanger; optionally, the cold water reheater 95 is a plate heat exchanger.

Fig. 4-1 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 4-1, on the basis of fig. 3, the condenser cooling water outlet 94-2 is also directly or indirectly communicated with the flue heat exchanger working medium water inlet 22-3; the flue heat exchanger working medium water outlet 22-4 is also directly or indirectly communicated with a heat user.

The working process is as follows:

the cold water heated by the absorber 92 and the condenser 94 is sent to the flue heat exchanger working medium water inlet 22-3, and after being heated by the flue heat exchanger 22 together with the working medium water of the working medium water outlet 9-4 of the air supply heater, part of the cold water is sent to the working medium water inlet 9-3 of the air supply heater for heating and air supply, and the other part of the cold water is sent to a heat user for use.

Compared with the embodiment of fig. 4, in the embodiment, cold water at the cooling water outlet 94-2 of the condenser is directly sent to the flue heat exchanger 22 to be heated by flue gas without passing through an intermediate heat exchanger, so that the primary heat exchange end difference can be reduced, the heat exchange efficiency and the temperature of the cold water sent to a hot user can be improved, and meanwhile, the equipment investment can be reduced. When in heating season, the high-temperature working medium water at the working medium water outlet 15-4 of the bypass economizer can be used as a high-temperature driving heat source to absorb low-grade heat of the heating medium water from the spray tower 12, the heat and the working efficiency of the absorption heat pump for absorbing the low-temperature heat source of the heating medium water can be improved, and then the cooling water at the cooling water outlet 94-2 of the condenser is reheated by the working medium water at the working medium water outlet 22-4 of the flue heat exchanger so as to meet the requirement of users on the temperature of the cooling water. In addition, for the same boiler unit, the flue gas flow and the heat capacity of the flue gas outlet 2-2 of the air preheater are far greater than the air supply flow and the heat capacity of the air preheater 2, and the working medium water of the working medium water outlet 22-4 of the flue heat exchanger is simply utilized to be sent to the air supply heater 9 for heating and air supply, and the air supply is limited by the heat exchange temperature difference of the heat exchanger, so that the heat of the flue gas cannot be fully absorbed and utilized by the air supply. Therefore, the cold water from the condenser cooling water outlet 94-2 is sent to the flue heat exchanger 22 to absorb part of the heat of the flue gas, so that the flue gas waste heat recovery efficiency can be improved.

Fig. 4-2 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 4-2, on the basis of fig. 3, the absorber cold water outlet 92-2 is also directly or indirectly communicated with the flue heat exchanger working medium water inlet 22-3; the flue heat exchanger working medium water outlet 22-4 is also directly or indirectly communicated with a heat user.

The working process is as follows:

the part of cold water heated by the absorber 92 is split into the working medium water inlet 22-3 of the flue heat exchanger, and after being heated by the flue heat exchanger 22 together with the working medium water of the working medium water outlet 9-4 of the air supply heater, part of the cold water is sent to the working medium water inlet 9-3 of the air supply heater for heating and air supply, and part of the cold water is sent to a heat user for use.

In this embodiment, part of cold water heated by the absorber 92 is sent to the flue heat exchanger 22 to be heated by flue gas, and compared with fig. 4-1, the temperature of cold water sent to the working medium water inlet 22-3 of the flue heat exchanger in this embodiment is low, so that the heat exchange efficiency of the flue heat exchanger 22 can be improved; another portion of the cold water from the absorber cold water outlet 92-2 is sent to the condenser 94 to be heated by the refrigerant vapor from the generator 93, and a higher outlet water temperature can be obtained due to the reduced flow of cold water.

Fig. 5 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 5, on the basis of fig. 3 or fig. 3-1 or fig. 3-2 or fig. 4 (on the basis of fig. 3 in this embodiment), the boiler flue gas waste heat recovery system is further provided with a first absorption heat pump 40; the first absorption heat pump 40 includes a first evaporator 41, a first absorber 42, a first generator 43, and a first condenser 44; the first evaporator 41 is provided with a first evaporator low-temperature heat source inlet 41-1, a first evaporator low-temperature heat source outlet 41-2, a first evaporator refrigerant water inlet 41-3 and a first evaporator refrigerant water vapor outlet 41-4; the first absorber 42 is provided with a first absorber cold water inlet 42-1, a first absorber cold water outlet 42-2, a first absorber refrigerant vapor inlet 42-3, a first absorber concentrated absorbent solution inlet 42-4, and a first absorber dilute absorbent solution outlet 42-5; the first generator 43 is provided with a first generator high temperature heat source inlet 43-1, a first generator high temperature heat source outlet 43-2, a first generator dilute absorbent solution inlet 43-3, a first generator concentrated absorbent solution outlet 43-4 and a first generator refrigerant water vapor outlet 43-5; the first condenser 44 is provided with a first condenser cooling water inlet 44-1, a first condenser cooling water outlet 44-2, a first condenser refrigerant water vapor inlet 44-3, and a first condenser refrigerant water outlet 44-4.

The first evaporator refrigerant water inlet 41-3 communicates directly or indirectly with the first condenser refrigerant water outlet 44-4; the first evaporator refrigerant vapor outlet 41-4 communicates directly or indirectly with the first absorber refrigerant vapor inlet 42-3; the first absorber concentrated absorbent solution inlet 42-4 communicates directly or indirectly with the first generator concentrated absorbent solution outlet 43-4; the first absorber lean absorbent solution outlet 42-5 is in direct or indirect communication with the first generator lean absorbent solution inlet 43-3; the first generator refrigerant vapor outlet 43-5 communicates directly or indirectly with the first condenser refrigerant vapor inlet 44-3; the first absorber cold water outlet 42-2 communicates directly or indirectly with the first condenser cold water inlet 44-1; the absorption heat pump 40 constitutes a first type of absorption heat pump, i.e. a heat-increasing absorption heat pump.

The spray tower heating medium water outlet 12-4 is also directly or indirectly communicated with the first evaporator low temperature heat source inlet 41-1; the low-temperature heat source outlet 41-2 of the first evaporator is directly or indirectly communicated with the spray tower heat medium water inlet 12-3;

when the bypass economizer working medium water outlet 15-4 is directly or indirectly communicated with the generator high temperature heat source inlet 93-1 and the generator high temperature heat source outlet 93-2 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3, the first generator 43 high temperature heat source channel is connected in series with the working medium water channel between the generator high temperature heat source outlet 93-2 and the bypass economizer working medium water inlet 15-3; the first generator high temperature heat source inlet 43-1 is directly or indirectly communicated with the generator high temperature heat source outlet 93-2; the first generator high-temperature heat source outlet 43-2 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3; the cold water path of the first absorber 42 and the first condenser 44 connected in series is connected in series to the cold water path of the absorber cold water inlet 92-1; the first condenser cooling water outlet 44-2 communicates directly or indirectly with the absorber cold water inlet 92-1;

The working principle is as follows:

the high-temperature working medium water from the bypass economizer working medium water outlet 15-4 is sequentially used as a high-temperature driving heat source of the absorption heat pump 90 and the first absorption heat pump 40, enters the generator 93 through the generator high-temperature heat source inlet 93-1, flows out of the absorption heat pump 90 through the generator high-temperature heat source outlet 93-2 after heat exchange and temperature reduction of the working medium water, then enters the first generator 43 through the first generator high-temperature heat source inlet 43-1 as a high-temperature driving heat source of the first absorption heat pump 40, and flows out of the first absorption heat pump 40 through the first generator high-temperature heat source outlet 43-2 after further heat exchange and temperature reduction of the working medium water; the working medium water is returned to the bypass economizer 15 for recycling.

The heat medium water from the spray tower heat medium water outlet 12-4 is used as a low-temperature heat source of the absorption heat pump 90, enters the evaporator 91 through the evaporator low-temperature heat source inlet 91-1, is extracted by the absorption heat pump 90, flows out of the absorption heat pump 90 through the evaporator low-temperature heat source outlet 91-2 after being cooled, and returns to the spray tower 12 for recycling; similarly, the heat medium water from the spray tower heat medium water outlet 12-4 is used as a low-temperature heat source of the first absorption heat pump 40, enters the first evaporator 41 through the first evaporator low-temperature heat source inlet 41-1, is cooled by the heat extracted by the first absorption heat pump 40, flows out of the first absorption heat pump 40 through the evaporator low-temperature heat source outlet 41-2, and returns to the spray tower 12 for recycling; cold water from a hot user firstly enters the first absorption heat pump 40 through the first absorber cold water inlet 42-1 to be heated, the warmed cold water flows out of the first absorption heat pump 40 through the first condenser cooling water outlet 44-2, then enters the absorption heat pump 90 through the absorber cold water inlet 92-1 to be further heated, and the further warmed cold water flows out of the absorption heat pump 90 through the condenser cooling water outlet 94-2 to be sent to the hot user for use.

In general, in order to control the manufacturing cost of the absorption heat pump 90, the temperature reduction range of the high-temperature driving heat source in the generator 93 of the absorption heat pump 90 is not too large, that is, the temperature of the working medium water at the high-temperature heat source outlet 93-2 of the generator is relatively high. Therefore, the first absorption heat pump 40 is provided, and the high-temperature driving heat source is sent to the first absorption heat pump 40 for further heat exchange and temperature reduction after the heat exchange and temperature reduction of the absorption heat pump 90, so that the heat of the high-temperature driving heat source can be fully utilized. In addition, since the high-temperature driving heat source temperature of the first absorption heat pump 40 is low, and the cold water temperature of the condenser cooling water outlet 44-2 is low in order to improve the efficiency of the first absorption heat pump 40, the cold water of the condenser cooling water outlet 44-2 of the first absorption heat pump 40 needs to be sent to the absorption heat pump 90 for further heating, and the efficiency of the absorption heat pump 90 can be improved. Therefore, the heat of the high-temperature driving heat source from the bypass economizer 15 can be fully utilized, and the low-grade heat of the heat medium water from the spray tower heat medium water outlet 12-4 can be more absorbed, so that the recovery efficiency and the utilization efficiency of the flue gas waste heat after desulfurization are improved.

The operation principle of the first absorption heat pump 40 is the same as that of the absorption heat pump 90, and will not be described here again.

When the flue heat exchanger working medium water outlet 22-4 is directly or indirectly communicated with the generator high temperature heat source inlet 93-1 and the generator high temperature heat source outlet 93-2 is directly or indirectly communicated with the flue heat exchanger working medium water inlet 22-3, the first generator 43 high temperature heat source channel is connected in series with the working medium water channel between the generator high temperature heat source outlet 93-2 and the flue heat exchanger working medium water inlet 22-3, and the first generator high temperature heat source inlet 43-1 is directly or indirectly communicated with the generator high temperature heat source outlet 93-2; the first generator high temperature heat source outlet 43-2 is directly or indirectly communicated with the flue heat exchanger working medium water inlet 22-3. (not shown in the drawings)

The working process is as follows:

the working medium water from the working medium water outlet 22-4 of the flue heat exchanger is used as a high-temperature driving heat source of the absorption heat pump 90 and the first absorption heat pump 40 in sequence, enters the generator 93 through the generator high-temperature heat source inlet 93-1 for heat exchange and temperature reduction, and flows out through the generator high-temperature heat source outlet 93-2; then enters the first generator through the first generator high-temperature heat source inlet 43-1 to exchange heat and cool, flows out through the first generator high-temperature heat source outlet 43-2, and returns to the flue heat exchanger working medium water inlet 22-3 for recycling. At this time, the absorption heat pump 90 will be less efficient, but the bypass economizer working fluid water outlet 15-4 will be more available to the heat consumer. The other basic principles are the same as those of fig. 5, and will not be described again.

When the generator 93 high temperature heat source channel is connected in series with the working medium water channel between the flue heat exchanger working medium water outlet 22-4 and the air supply heater working medium water inlet 9-3, the flue heat exchanger working medium water outlet 22-4 is directly or indirectly connected with the generator high temperature heat source inlet 93-1, the generator high temperature heat source outlet 93-2 is directly or indirectly connected with the air supply heater working medium water inlet 9-3, and the air supply heater working medium water outlet 9-4 is directly or indirectly connected with the flue heat exchanger working medium water inlet 22-3, the first generator 43 high temperature heat source channel is connected in series with the working medium water channel between the generator high temperature heat source outlet 93-2 and the air supply heater working medium water inlet 9-3, and the first generator high temperature heat source inlet 43-1 is directly or indirectly connected with the generator high temperature heat source outlet 93-2; the first generator high temperature heat source outlet 43-2 is directly or indirectly communicated with the working medium water inlet 9-3 of the air supply heater. (not shown in the drawings).

The working process is as follows:

the working medium water from the working medium water outlet 22-4 of the flue heat exchanger is used as a high-temperature driving heat source of the absorption heat pump 90 and the first absorption heat pump 40 in sequence, enters the generator 93 through the generator high-temperature heat source inlet 93-1 for heat exchange and temperature reduction, and flows out through the generator high-temperature heat source outlet 93-2; then enters the first generator through the first generator high-temperature heat source inlet 43-1 to exchange heat and cool down, and then flows out through the first generator high-temperature heat source outlet 43-2; then, the air is taken as a heating source of the air supply heater 9, enters the air supply heater 9 through the air supply heater working medium water inlet 9-3 to heat and supply air, flows out through the air supply heater working medium water outlet 9-4, and returns to the flue heat exchanger working medium water inlet 22-3 for recycling. At this time, the efficiency of the absorption heat pump 90 is low, and the heat of the working medium water from the flue heat exchanger 22 is fully utilized, so that the temperature of the working medium water at the working medium water inlet 22-3 of the flue heat exchanger is reduced, the heat exchange efficiency of the flue heat exchanger 22 is improved, and the working medium water at the working medium water outlet 15-4 of the bypass economizer can be used for heat users more. The other basic principles are the same as those of fig. 5, and will not be described again.

When the second-stage bypass heat exchange module working medium water outlet 15b-4 is directly or indirectly communicated with the generator high-temperature heat source inlet 93-1 and the generator high-temperature heat source outlet 93-2 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3, the first generator 43 high-temperature heat source channel is connected in series with the working medium water channel between the generator high-temperature heat source outlet 93-2 and the bypass economizer working medium water inlet 15-3; the first generator high temperature heat source inlet 43-1 is directly or indirectly communicated with the generator high temperature heat source outlet 93-2; the first generator high-temperature heat source outlet 43-2 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3; the cold water path of the first absorber 42 and the first condenser 44 connected in series is connected in series to the cold water path of the absorber cold water inlet 92-1; the first condenser cooling water outlet 44-2 communicates directly or indirectly with the absorber cold water inlet 92-1; (not shown in the drawings)

The working principle is as follows:

the high-temperature working medium water from the working medium water outlet 15b-4 of the second-stage bypass heat exchange module is sequentially used as a high-temperature driving heat source of the absorption heat pump 90 and the first absorption heat pump 40, enters the generator 93 through the generator high-temperature heat source inlet 93-1, flows out of the absorption heat pump 90 through the generator high-temperature heat source outlet 93-2 after heat exchange and temperature reduction, then enters the first generator 43 through the first generator high-temperature heat source inlet 43-1 as a high-temperature driving heat source of the first absorption heat pump 40, and flows out of the first absorption heat pump 40 through the first generator high-temperature heat source outlet 43-2 after further heat exchange and temperature reduction; the working medium water is returned to the second-stage bypass heat exchange module 15b for recycling.

The other principles are basically the same as those of fig. 5, and will not be described again.

Fig. 6 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 6, the boiler flue gas waste heat recycling system is further provided with a first air supply heater 80; the first air supply heater 80 is provided with a first air supply heater air supply inlet 80-1, a first air supply heater air supply outlet 80-2, a first air supply heater cold water inlet 80-3 and a first air supply heater cold water outlet 80-4; the air supply channel of the first air supply heater 80 is connected in series with the air channel of the blower air supply inlet 8-1 or the blower air supply outlet 8-2 which is directly or indirectly communicated, and the air supply inlet 80-1 of the first air supply heater is directly or indirectly communicated with the atmosphere; the first air supply heater air supply outlet 80-2 is directly or indirectly communicated with the air supply heater air supply inlet 9-1; the first supply air heater cold water inlet 80-3 communicates directly or indirectly with the condenser cold water outlet 94-2; the first supply air heater cold water outlet 80-4 communicates directly or indirectly with the absorber cold water inlet 92-1.

The working process is as follows:

the cold water from the condenser cooling water outlet 94-2 is sent to the first air supply heater cold water inlet 80-3 to enter the first air supply heater 80 cold water channel, and after heating the air supply flowing through the first air supply heater 80 air supply channel, the air supply is sent back to the absorber cold water inlet 92-1 through the first air supply heater cold water outlet 80-4. Other working processes are basically the same as those of fig. 3, and will not be described again.

Part of working medium water from the working medium water outlet 15-4 of the bypass economizer is used as a high-temperature driving heat source, the heat quantity is set as Qg, the heat quantity of a low-temperature heat source of low-temperature heat medium water from the spray tower 12 is absorbed through the first type absorption heat pump 90, and the heat quantity is set as Q _d The medium temperature heat converted into the condenser cooling water outlet 94-2 is set as Q _Z According to the working principle of the first type of absorption heat pump, Q _Z ＝Qg+Q _d . This heat is transferred to the air supply through the first air supply heater 80 and then enters the air preheater 2, and when the smoke temperature at the smoke outlet 2-2 of the air preheater is kept unchanged and secondary factors are ignored, the bypass smoke flow of the bypass economizer 15 can be increased, and the heat of this smoke is Q _Z ＝Qg+Q _d That is, the high-temperature driving heat source from the bypass economizer 15 and the low-grade heat energy of the saturated flue gas which is difficult to utilize after desulfurization from the spray tower 12 are converted into the high-temperature heat energy of the flue gas by the absorption heat pump 90, the spray tower 12, the first air supply heater 80, the air preheater 2 and the bypass economizer 15.

The high temperature driving heat source of the absorption heat pump 90 may also use the working fluid water of the working fluid water outlet 22-4 of the flue heat exchanger, but the efficiency of the absorption heat pump 90 will be lower because the temperature is lower than the temperature of the working fluid water outlet 15-4 of the bypass economizer.

Optionally, a cold water pump (not shown) is provided on the cold water path through which the absorber cold water inlet 92-1 or the condenser cold water outlet 94-2 communicates directly or indirectly.

Optionally, the first supply air heater 80 is a dividing wall heat exchanger.

Fig. 7 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 7, the boiler flue gas waste heat recycling system is further provided with a second air supply heater 100; the second air supply heater 100 is provided with a second air supply heater air supply inlet 100-1, a second air supply heater air supply outlet 100-2, a second air supply heater heat medium water inlet 100-3 and a second air supply heater heat medium water outlet 100-4; the air supply channel of the second air supply heater 100 is connected in series with the air channel of the blower air supply inlet 8-1 or the blower air supply outlet 8-2 which is directly or indirectly communicated, and the air supply inlet 100-1 of the second air supply heater is directly or indirectly communicated with the atmosphere; when the first air supply heater 80 is provided, the second air supply heater air supply outlet 100-2 is directly or indirectly communicated with the first air supply heater air supply inlet 80-1; when the first air supply heater 80 is not provided, the second air supply heater air supply outlet 100-2 is directly or indirectly communicated with the air supply heater air supply inlet 9-1; the second air supply heater heat medium water inlet 100-3 is directly or indirectly communicated with the spray tower heat medium water outlet 12-4; the second air supply heater heat medium water outlet 100-4 is directly or indirectly communicated with the spray tower heat medium water inlet 12-3.

The working process is as follows:

the heat medium water from the spray tower heat medium water outlet 12-4 is directly or indirectly sent to the second air supply heater heat medium water inlet 100-3, enters the heat medium water channel of the second air supply heater 100, and the air supply (air) enters the air supply channel of the second air supply heater 100 through the second air supply heater air supply inlet 100-1 under the driving of the blower 8, the temperature of the heat medium water in the heat medium water channel of the second air supply heater 100 is reduced after the air supply of the air supply channel of the second air supply heater 100 is heated, and then flows out through the heat medium water outlet 100-4 of the second air supply heater, returns to the spray tower heat medium water inlet 12-3 for recycling. The air with increased temperature is sent to the hearth of the boiler 1 through the air preheater air supply outlet 2-4 after being further heated by the first air supply heater 80 (if any), the air supply heater 9 and the air preheater 2. When the heat transferred to the air supply through the second air supply heater 100 is ignored and finally distributed to heat and other secondary factors entering the hearth of the boiler 1, the heat transferred to the air supply by the second air supply heater 100 is converted into the equal heat to increase the temperature of the flue gas outlet 2-2 of the air preheater or increase the bypass flue gas flow of the bypass economizer 15, namely, the working medium water heat of the working medium water outlet 22-4 of the flue heat exchanger or the working medium water heat of the working medium water outlet 15-4 of the bypass economizer is increased, so that the low-grade heat energy of the saturated flue gas after desulfurization is converted into the equal heat high-grade water heat energy through the spray tower 12, the second air supply heater 100, the air preheater 2, the flue heat exchanger 22 or the bypass economizer 15, and the utilization value and the utilization efficiency of the heat energy can be improved. The heat transferred to the air supplied by the second air supply heater 100 can be controlled to be converted into the proportion of the rise of the temperature of the flue gas at the flue gas outlet 2-2 of the air preheater and the increase of the bypass flue gas flow of the bypass economizer 15 by adjusting the bypass flue gas flow entering the flue gas inlet 15-1 of the bypass economizer and the like, namely, the proportion of the increase of the water heat and the temperature of the working medium at the working medium water outlet 22-4 of the flue heat exchanger and the increase of the water heat and the temperature of the working medium at the working medium water outlet 15-4 of the bypass economizer is controlled. The energy saving effect is better when the heat transferred to the air supply through the second air supply heater 100 is counted up and finally distributed into the furnace of the boiler 1.

Further, the heat energy is used as a high-temperature driving heat source of the absorption heat pump 90 to be input into the generator 93 of the absorption heat pump, so that the low-temperature heat of the heat medium water from the spray tower 12 can be recovered more, which is beneficial to improving the efficiency and external heat supply of the absorption heat pump 90. Therefore, the low-temperature flue gas waste heat which is difficult to utilize after desulfurization can be recovered through mixed heat exchange of the spray tower and is converted into high-grade heat energy through the second air supply heater 100 and the air preheater 2, so that the full recovery and the efficient utilization of the flue gas waste heat are realized, and the increase of the flue gas waste heat recovery amount and the improvement of the heat energy quality are realized. The low-grade flue gas waste heat after desulfurization is converted into heat of high-temperature hot water through the spray tower 12, the second air supply heater 100, the air preheater 2 and the bypass economizer 2 and is used as a high-temperature driving heat source of the absorption heat pump 90, and further the heat of the low-temperature heat source of the heat medium water from the spray tower 12 is further absorbed through the absorption heat pump 90 and is converted into usable heat energy with higher temperature, so that the low-grade heat energy of the flue gas after desulfurization is driven and absorbed by the low-grade heat energy from the flue gas after desulfurization, and is converted into the usable heat energy with higher temperature. In general, the temperature of the flue gas at the outlet of the desulfurizing tower 6 is about 50 ℃, the temperature of the flue gas at the outlet of the air preheater is about 120 ℃, the temperature of the air at the inlet of the second air supply heater 100 is about 15 ℃, the temperature of the hot medium water after mixed heat exchange between the spraying tower 12 and the flue gas can be raised to about 40 ℃, the temperature of the air supply after being heated by the hot medium water at the second air supply heater 100 can be raised to about 35 ℃, and the temperature of the flue gas at the flue gas outlet of the air preheater 2-2 is about 300 ℃. Under the condition that the air supply temperature of the air preheater air supply inlet 2-3 is increased, and the air supply temperature of the air preheater air supply outlet 2-4 is increased (if the income is counted into the air supply system), and other secondary factors are not counted, the heat conservation is considered, the heat increase realized by the increased flue gas flow of the bypass economizer 15 is equal to the flue gas waste heat absorbed by the heat medium water from the spray tower 12, namely, the low-grade flue gas waste heat at the outlet 50 ℃ of the desulfurizing tower 6 passes through the spray tower 12, the air supply heater 80, the air preheater 2 and the bypass economizer 15 and can be converted into the high-grade flue gas heat at the flue gas inlet 120 ℃ of the flue heat exchanger or the flue gas inlet 300 ℃ of the bypass economizer by the equal heat quantity, so that the heat quantity and the temperature of the working medium water outlet 15-4 of the flue heat exchanger are improved, or the recovery efficiency of the low-temperature heat of the heat medium water of the bypass economizer is further increased through the absorption heat pump 90, and the recovery efficiency of the low-grade flue gas waste heat and the high-grade flue gas waste heat are further improved, and the flue gas waste heat recovery efficiency and the utilization efficiency are further improved.

The second blast heater 100 has self-adapting and self-adjusting capabilities for stack plume abatement: when the ambient temperature is low, smoke plume phenomenon is aggravated, and the diffusion of smoke pollutants at the outlet of the chimney is worsened; meanwhile, the air temperature of the air supply inlet 100-1 of the second air supply heater is low, the cooling capacity of the second air supply heater 100 to the heat medium water is improved, the temperature of the heat medium water outlet 100-3 of the second air supply heater is reduced, the condensation cooling of the heat medium water to the flue gas in the spray tower 12 is increased, the smoke plume regulating effect of the chimney is enhanced, and pollutants in the flue gas are reduced. And vice versa. When the atmospheric humidity increases, the diffusion of the smoke pollutants at the outlet of the chimney becomes worse, the smoke plume phenomenon is aggravated, meanwhile, the air humidity increases, the specific heat capacity increases, the cooling capacity of the second air supply heater 100 to the heat medium water increases, the temperature of the heat medium water at the heat medium water outlet 100-4 of the second air supply heater decreases, the condensation cooling of the smoke is increased, the smoke plume regulating effect of the chimney is enhanced, and the pollutants in the smoke are reduced. And vice versa.

The first air blast heater 80 or the second air blast heater 100 may be disposed on an air blast passage between the blower air blast outlet 8-2 and the air preheater air blast inlet 2-3; alternatively, the first blower heater 80 and the second blower heater 100 are provided at the blower inlet 8-1. The former mode is characterized in that the temperature of the air supply is increased after the air supply is driven and pressurized by the air blower, and under the same condition, the heat transferred to the air supply by the heater is reduced, but the power consumption of the air blower is basically unchanged; the latter approach has the advantage that the heater inlet air temperature is low and, under the same conditions, the heater can transfer more heat to the supply air, but the power consumption of the blower will increase slightly.

The second air supply heater 100 is a dividing wall type heat exchanger.

Fig. 8 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 8, the working medium water channel of the flue heat exchanger 22, the working medium water channel of the bypass economizer 15, the working medium water channel of the generator 93, the working medium water channel of the air supply heater 9 and the working medium water channel of the flue heat exchanger 22 are sequentially connected in series end to end; the flue heat exchanger working medium water outlet 22-4 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3; the bypass economizer working medium water outlet 15-4 is directly or indirectly communicated with the generator high-temperature heat source inlet 93-3; the high-temperature heat source outlet 93-2 of the generator is directly or indirectly communicated with the working medium water inlet 9-3 of the air supply heater; the working medium water outlet 9-4 of the air supply heater is directly or indirectly communicated with the working medium water inlet 22-3 of the flue heat exchanger.

The working process is as follows:

working medium water from a working medium water outlet 9-4 of the air supply heater firstly exchanges heat with flue gas through a flue heat exchanger 22 to raise temperature, and then is sent into a bypass economizer 15 to exchange heat with higher-temperature flue gas to raise temperature; then the air is sent into the generator 93 as a high-temperature driving heat source for heat exchange and temperature reduction, then is sent into the air supply heater 9 as a heating heat source for heating and air supply, and then returns to the flue heat exchanger for recycling. Therefore, the countercurrent cascade heat exchange of the working medium water and the flue and the cascade heat release of the working medium water are realized, the irreversible loss is reduced, and the heat exchange efficiency and the heat utilization efficiency are improved.

Fig. 9 is a schematic structural view of an embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 9, the boiler flue gas waste heat recycling system is further provided with: a steam turbine 25, a condenser 27, a condensate pump 26, a low-pressure heater 29, a deaerator 30, a feed pump 32, and a high-pressure heater 31; wherein,,

the steam turbine 25 is provided with a steam turbine steam inlet 25-1, a steam turbine steam outlet 25-2, a steam turbine high-pressure steam extraction outlet 25-5 and a steam turbine low-pressure steam extraction outlet 25-4;

the condenser 27 is provided with a condenser steam inlet 27-1 and a condenser working medium water outlet 27-2;

the condensate water pump 26 is provided with a condensate water pump inlet 26-1 and a condensate water pump outlet 26-2;

the low-pressure heater 29 is provided with a low-pressure heater working medium water inlet 29-1, a low-pressure heater working medium water outlet 29-2 and a low-pressure heater steam extraction inlet 29-3;

the deaerator 30 is provided with a deaerator working medium water inlet 30-1 and a deaerator working medium water outlet 30-2;

the feed pump 32 is provided with a feed pump inlet 32-1 and a feed pump outlet 32-2;

the high-pressure heater 31 is provided with a high-pressure heater working medium water inlet 31-1, a high-pressure heater working medium water outlet 31-2 and a high-pressure heater steam extraction inlet 31-3;

The boiler 1 is also provided with a boiler steam outlet 1-4 and a boiler working medium water inlet 1-5;

the boiler steam outlet 1-4 communicates directly or indirectly with the turbine steam inlet 25-1; the steam turbine steam outlet 26-2 is directly or indirectly communicated with the condenser steam inlet 27-1; the condenser working medium water outlet 27-2 is directly or indirectly communicated with the condensate pump inlet 26-1; the condensate pump outlet 26-2 is simultaneously communicated with the low-pressure heater working medium water inlet 29-1 and the bypass economizer working medium water inlet 15-3 directly or indirectly; the low-pressure heater working medium water outlet 29-2 is directly or indirectly communicated with the deaerator working medium water inlet 30-1; the deaerator working medium water outlet 30-2 is directly or indirectly communicated with the water feed pump inlet 32-1; the water feed pump outlet 32-2 is directly or indirectly communicated with the working medium water inlet 31-1 of the high-pressure heater; the high-pressure heater working medium water outlet 31-2 and the bypass economizer working medium water outlet 15-4 are directly or indirectly communicated with the boiler working medium water inlet 1-5; the low-pressure heater extraction inlet 29-3 is directly or indirectly communicated with the turbine low-pressure extraction outlet 25-4; the high-pressure heater extraction inlet 31-3 is in direct or indirect communication with the turbine high-pressure extraction outlet 25-5.

The working process is as follows:

the high-pressure high-temperature steam generated by the combustion of the boiler 1 is subjected to work in the steam turbine 25, the pressure and the temperature are reduced, the low-pressure high-temperature steam is discharged into the condenser 27 through the steam turbine steam outlet 25-2 and the condenser working medium water inlet 27-1, the cooled and condensed working medium water (condensed water) flows out of the condenser 27 through the condenser working medium water outlet 27-2, then part of the working medium water is driven by the condensed water pump 26 to be sent into the low-pressure heater 29 through the low-pressure heater working medium water inlet 29-1, the working medium water is heated and warmed in the low-pressure heater 29 by using the extraction steam from the steam turbine low-pressure extraction steam outlet 25-4, the warmed working medium water flows out of the low-pressure heater 29 through the low-pressure heater working medium water outlet 29-2 and is sent to the deaerator 30, the deaerated working medium water is sent into the high-pressure heater 31 under the driving of the water feed pump 32, the working medium water is heated and warmed by using the extraction steam from the steam turbine high-pressure outlet 25-5 in the high-pressure heater 31, and the warmed working medium water flows out of the high-pressure heater 31 through the high-pressure heater 31; part of working medium water is directly or indirectly sent to a working medium water inlet 15-3 of a bypass economizer through other equipment (such as a heater, a water pump, a buffer water tank and the like) to enter the bypass economizer 15, and the working medium water and flue gas absorb the waste heat of the flue gas through heat exchange to raise the temperature and then flow out of the bypass economizer 15 through a working medium water outlet 15-4 of the bypass economizer; all or part of working medium water from the high-pressure heater 31 and the bypass economizer 15 is fed into the boiler 1 through the boiler working medium water inlets 1-5; the fuel from the boiler fuel inlet 1-1 and the air from the boiler air inlet 1-2 generate combustion reaction to release heat, heat the working medium water from the boiler working medium water inlet 1-5 and generate high-pressure high-temperature steam, and the high-pressure high-temperature steam is sent to the steam turbine 26 through the boiler steam outlet 1-4 to continuously do work, and the cycle is performed.

The flue gas waste heat and the bypass economizer 15 are utilized to heat part of working medium water from the steam turbine condenser, so that steam turbine extraction steam for heating the working medium water in the traditional technology can be saved. The part of the extracted steam can return to the steam turbine to do work and generate electricity, and can also be extracted to supply heat to the outside. Therefore, the power generation coal consumption is reduced, the power generation capacity, the heat supply capacity and the thermoelectric ratio of the steam turbine are improved, the lowest steam inlet flow of the low-pressure cylinder can be reduced, and the peak regulation capacity and the flexibility of the unit are improved. In addition, the low-grade flue gas waste heat is converted into high-grade flue gas heat of the flue gas inlet 15-1 of the bypass economizer, working medium water from the working medium water outlet 27-2 of the condenser can be heated to the temperature requirement that the working medium water can enter the working medium water inlet 1-5 of the boiler (the working medium water can be sent to the working medium water inlet 1-5 of the boiler after being heated and warmed by a high-pressure heater system in the conventional technology), high-stage steam turbine extraction steam can be saved, and the working capacity of steam with the same heat but high temperature in the steam turbine is high according to the steam turbine principle, so that the heat utilization efficiency is high, and the energy saving efficiency is greatly improved. Under the condition of accounting the heat sent into the hearth 1 by the air preheater 2 through the air supply heater 9, the flue gas waste heat recycling efficiency is higher.

The boiler is also provided with an economizer, and the boiler working medium water inlets 1-5 may be working medium water inlets (not shown in the figure) of said economizer.

Optionally, a first low pressure heater 28 is also provided; the condensate pump outlet 26-2 is in direct or indirect communication with the low pressure heater working fluid water inlet 29-1 and the bypass economizer working fluid water inlet 15-3 simultaneously through the first low pressure heater 28. Working fluid water from the condensate pump 26 is heated by the first low-pressure heater 28 and then sent to the low-pressure heater 29 and the bypass economizer 15 respectively. Typically, the first low pressure heater 28 is heated using steam extraction from the steam turbine 25 or other heat source (not shown).

Optionally, low pressure heater 29 is a one-stage or multi-stage low pressure heater (one stage is shown in the figures); the high-pressure heater 31 is a one-stage or multi-stage high-pressure heater (one stage is shown in the figure); the first low pressure heater 28 is a one-stage or multi-stage low pressure heater (one stage is shown); optionally, the turbine high pressure extraction outlet 25-5 is one or more stages (one stage is shown); optionally, the low pressure extraction steam turbine outlet 25-4 is one or more stages (one stage is shown).

In general, the steam turbine is used for driving the generator to generate electricity, so that the efficiency or the working capacity of the steam turbine is improved, and the electricity generation coal consumption or the electricity supply coal consumption can be reduced.

Fig. 9-1 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 9, a spray tower 12 is connected in series between the desulfurizing tower 6 and the chimney 7; a second air supply heater 100 is provided in an air supply passage through which the air supply inlet 9-1 of the air supply heater is directly or indirectly connected, and the connection between the spray tower 12 and the second air supply heater 100 is described with reference to the embodiment of fig. 2. In the embodiment, the low-grade flue gas waste heat of the desulfurized saturated flue gas can be recovered through the spray tower 12, and is converted into high-temperature flue gas heat of the flue gas inlet 15-1 of the bypass economizer through the second air supply heater 100, the air preheater 2 and the bypass economizer 15, so that part of working medium water from the condensate pump 26 is heated, the extraction steam of a high-stage steam turbine can be saved, and the functional capability of the steam turbine is improved.

Fig. 9-2 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 9, there are also a spray tower 12 and an absorption heat pump 90, and the connection mode of the spray tower 12 and the absorption heat pump 90 refers to the embodiment of fig. 3-1.

Fig. 9-3 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 9, there are also a spray tower 12 and an absorption heat pump 90, and the connection between the spray tower 12 and the absorption heat pump 90 is described with reference to the embodiment of fig. 3-2.

Fig. 9-4 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 9-2, a first blast heater 80 is also provided. The connection mode of the first air supply heater 80 refers to the embodiment of fig. 6 or 8. In the embodiment, the working medium water at the working medium water outlet 22-4 of the flue heat exchanger is used as a high-temperature driving heat source, more low-grade flue gas waste heat of the desulfurized saturated flue gas can be recovered by utilizing the absorption heat pump 90 and the spray tower 12, and because the cold water at the condenser cooling water outlet 94-2 of the absorption heat pump 90 has higher temperature, more cold water can be transmitted to the air supply through the first air supply heater 80, and then the cold water is converted into high-temperature heat energy through the air preheater 2 and the bypass economizer 15, and the working medium water from the condensate pump 26 is heated, so that the extraction steam of a high-stage steam turbine can be saved, and the functional capability and the working efficiency of the steam turbine are improved. The method can be used for non-heating seasons, when no heating requirement exists outside the system, the low-grade flue gas waste heat of the air preheater outlet and the low-grade flue gas waste heat of the desulfurized saturated flue gas which is difficult to utilize can be converted into the high-temperature working medium water heat energy of the bypass economizer working medium water outlet 15-4 to be used for power generation of a steam turbine or other purposes, so that the utilization efficiency of the flue gas waste heat is greatly improved, and meanwhile, the effective utilization of the non-heating season absorption heat pump is realized. And the temperature and humidity of the smoke emission can be reduced, and the smoke pollutant emission and smoke plume phenomenon can be reduced. In addition, the environment temperature is high in the non-heating season, the temperature difference between the heating medium water at the heating medium water outlet of the spray tower and the air supply is small, the heat exchange efficiency is low, the heat of the heating medium water at the heating medium water outlet of the spray tower can be recovered by utilizing the absorption heat pump and converted into the medium-temperature heat energy of cold water at the cooling water outlet (the cooling water outlet of the condenser or/and the cold water outlet of the absorber) of the absorption heat pump with high temperature, the medium-temperature heat energy is used for heating the air supply, the heat quantity delivered to the air supply can be improved, and then the medium-temperature heat energy is converted into the high-temperature heat energy through the air preheater and the bypass economizer. (conventional technology, absorption heat pumps are typically in an idle state during non-heating seasons).

Fig. 9-5 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. A second blast heater 100 is also provided on the basis of fig. 9-2. The connection mode of the second blower heater 100 refers to the embodiment of fig. 7. Features refer to fig. 9-1.

Fig. 9-6 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 9-6, the bypass economizer 15 differs from fig. 9-2 in that it includes a first stage bypass heat exchange module 15a and a second stage bypass heat exchange module 15b connected in series one after the other; the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet 15-1, a first-stage bypass heat exchange module flue gas outlet 15a-2, a first-stage bypass heat exchange module working medium water inlet 15a-3 and a bypass economizer working medium water outlet 15-4; the second-stage bypass heat exchange module 15b is provided with a second-stage bypass heat exchange module smoke inlet 15b-1, a bypass economizer smoke outlet 15-2, a bypass economizer working medium water inlet 15-3 and a second-stage bypass heat exchange module working medium water outlet 15b-4; the first-stage bypass heat exchange module flue gas outlet 15a-2 is directly or indirectly communicated with the second-stage bypass heat exchange module flue gas inlet 15b-1, and the second-stage bypass heat exchange module working medium water outlet 15b-4 is simultaneously directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet 15a-3 and the generator high-temperature heat source inlet 93-1; the high-temperature heat source outlet 93-2 of the generator is directly or indirectly communicated with the working medium water inlet 15-3 of the bypass economizer.

The working process is as follows:

Compared to fig. 9-2, the high-temperature driving heat source of the absorption heat pump 90 of the present embodiment has a high temperature and a high heat pump operation efficiency.

Fig. 9-7 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 9 to 7, the bypass economizer 15 is different from fig. 9 to 4 in that the bypass economizer 15 includes a first stage bypass heat exchange module 15a and a second stage bypass heat exchange module 15b connected in series one after the other; the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet 15-1, a first-stage bypass heat exchange module flue gas outlet 15a-2, a first-stage bypass heat exchange module working medium water inlet 15a-3 and a bypass economizer working medium water outlet 15-4; the second-stage bypass heat exchange module 15b is provided with a second-stage bypass heat exchange module smoke inlet 15b-1, a bypass economizer smoke outlet 15-2, a bypass economizer working medium water inlet 15-3 and a second-stage bypass heat exchange module working medium water outlet 15b-4; the first-stage bypass heat exchange module flue gas outlet 15a-2 is directly or indirectly communicated with the second-stage bypass heat exchange module flue gas inlet 15b-1, and the second-stage bypass heat exchange module working medium water outlet 15b-4 is simultaneously directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet 15a-3 and the generator high-temperature heat source inlet 93-1; the high-temperature heat source outlet 93-2 of the generator is directly or indirectly communicated with the working medium water inlet 15-3 of the bypass economizer.

The working process is as follows:

Compared with fig. 9-4, the high-temperature driving heat source of the absorption heat pump 90 of the present embodiment has a high temperature, and the heat pump has a high working efficiency.

Fig. 9-8 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 9 to 8, the bypass economizer 15 is different from fig. 9 to 5 in that the bypass economizer 15 includes a first stage bypass heat exchange module 15a and a second stage bypass heat exchange module 15b connected in series one after the other; the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet 15-1, a first-stage bypass heat exchange module flue gas outlet 15a-2, a first-stage bypass heat exchange module working medium water inlet 15a-3 and a bypass economizer working medium water outlet 15-4; the second-stage bypass heat exchange module 15b is provided with a second-stage bypass heat exchange module smoke inlet 15b-1, a bypass economizer smoke outlet 15-2, a bypass economizer working medium water inlet 15-3 and a second-stage bypass heat exchange module working medium water outlet 15b-4; the first-stage bypass heat exchange module flue gas outlet 15a-2 is directly or indirectly communicated with the second-stage bypass heat exchange module flue gas inlet 15b-1, and the second-stage bypass heat exchange module working medium water outlet 15b-4 is simultaneously directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet 15a-3 and the generator high-temperature heat source inlet 93-1; the high-temperature heat source outlet 93-2 of the generator is directly or indirectly communicated with the working medium water inlet 15-3 of the bypass economizer.

The working process is as follows:

Compared with fig. 9-5, the high-temperature driving heat source of the absorption heat pump 90 of the present embodiment has a high temperature, and the heat pump has a high working efficiency.

Fig. 9-9 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 9-9, the difference from fig. 9-6 is that the flue heat exchanger is utilized to reheat the cold water at the condenser cooling water outlet. The basic principle is described with reference to fig. 9-6 and fig. 4-1, and will not be repeated.

Fig. 9-10 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 9-10, the difference from fig. 9-6 is that the flue heat exchanger is utilized to reheat the cold water at the cold water outlet of the absorber. The basic principle is described with reference to fig. 9-6 and fig. 4-2, and will not be repeated.

Fig. 10 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 10, the boiler flue gas waste heat recycling system is further provided with: a steam turbine 25, a condenser 27, a condensate pump 26, a low-pressure heater 29, a deaerator 30, a feed pump 32, and a high-pressure heater 31; wherein,,

the boiler steam outlet 1-4 communicates directly or indirectly with the turbine steam inlet 25-1; the steam turbine steam outlet 26-2 is directly or indirectly communicated with the condenser steam inlet 27-1; the condenser working medium water outlet 27-2 is directly or indirectly communicated with the condensate pump inlet 26-1; the condensate pump outlet 26-2 is directly or indirectly communicated with the low-pressure heater working medium water inlet 29-1; the low-pressure heater working medium water outlet 29-2 is directly or indirectly communicated with the deaerator working medium water inlet 30-1; the deaerator working medium water outlet 30-2 is directly or indirectly communicated with the water feed pump inlet 32-1; the water feed pump outlet 32-2 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3 and the high-pressure heater working medium water inlet 31-1 at the same time; the high-pressure heater working medium water outlet 31-2 and the bypass economizer working medium water outlet 15-4 are directly or indirectly communicated with the boiler working medium water inlet 1-5; the low-pressure heater extraction inlet 29-3 is directly or indirectly communicated with the turbine low-pressure extraction outlet 25-4; the high-pressure heater extraction inlet 31-3 is in direct or indirect communication with the turbine high-pressure extraction outlet 25-5.

The working process is as follows:

the high-pressure high-temperature steam generated by the combustion of the boiler 1 is subjected to work in the steam turbine 25, the pressure and the temperature are reduced, the low-pressure high-temperature steam is discharged into the condenser 27 through the steam turbine steam outlet 25-2 and the condenser working medium water inlet 27-1, the condensed working medium water (condensed water) is cooled by the condenser 27 and flows out of the condenser 27 through the condenser working medium water outlet 27-2, the condensed water is driven by the condensed water pump 26 and is sent into the low-pressure heater 29 through the low-pressure heater working medium water inlet 29-1, the working medium water is heated and warmed in the low-pressure heater 29 by using the extraction steam from the steam turbine low-pressure extraction steam outlet 25-4, the warmed working medium water flows out of the low-pressure heater 29 through the low-pressure heater working medium water outlet 29-2, the deoxygenated working medium water is sent to the deaerator 30, a part of the working medium water after deaeration is sent into the high-pressure heater 31 under the driving of the water feed pump 32, the working medium water enters the high-pressure heater 31, the working medium water is heated and warmed by using the extraction steam from the steam turbine high-pressure outlet 25-5 in the high-pressure heater 31, and the warmed working medium water flows out of the high-pressure heater 31 through the high-pressure heater 31; part of the water is directly or indirectly sent to a working medium water inlet 15-3 of the bypass economizer through other equipment (such as a heater, a water pump, a buffer water tank and the like) to enter the bypass economizer 15, and the working medium water and the flue gas absorb the waste heat of the flue gas through heat exchange to raise the temperature and then flow out of the bypass economizer 15 through a working medium water outlet 15-4 of the bypass economizer; working fluid water (all or part) from the high-pressure heater 31 and the bypass economizer 15 is fed into the boiler 1 through the boiler working fluid water inlets 1-5; the fuel from the boiler fuel inlet 1-1 and the air from the boiler air inlet 1-2 generate combustion reaction to release heat, heat the working medium water from the boiler working medium water inlet 1-5 and generate high-pressure high-temperature steam, and the high-pressure high-temperature steam is sent to the steam turbine 26 through the boiler steam outlet 1-4 to continuously do work, and the cycle is performed.

The flue gas waste heat and the bypass economizer 15 are utilized to heat part of working medium water from the steam turbine condenser, so that steam turbine extraction steam for heating the working medium water in the traditional technology can be saved. The part of the extracted steam can return to the steam turbine to do work and generate electricity, and can also be extracted to supply heat to the outside. Therefore, the power generation coal consumption is reduced, the power generation capacity, the heat supply capacity and the thermoelectric ratio of the steam turbine are improved, the lowest steam inlet flow of the low-pressure cylinder can be reduced, and the peak regulation capacity and the flexibility of the unit are improved. In addition, the low-grade flue gas waste heat is converted into high-grade flue gas heat of the flue gas inlet 15-1 of the bypass economizer, working medium water from the working medium water outlet 27-2 of the condenser can be heated to the temperature requirement that the working medium water can enter the working medium water inlet 1-5 of the boiler (the working medium water can be sent to the working medium water inlet 1-5 of the boiler after being heated and warmed by a high-pressure heater system in the conventional technology), high-stage steam turbine extraction steam can be saved, and the working capacity of steam with the same heat but high temperature in the steam turbine is high according to the steam turbine principle, so that the heat utilization efficiency is high, and the energy saving efficiency is greatly improved. Compared with the condition that the temperature of the working medium water from the condensate pump outlet 26-2 is higher, the bypass economizer 15 can heat more working medium water flow under the condition of the same heat exchange quantity, and more high-stage steam turbine extraction steam is saved, so that the heat utilization efficiency is higher, and the energy saving efficiency is higher.

Optionally, a first low pressure heater 28 is also provided; the condensate pump outlet 26-2 communicates directly or indirectly with the low pressure heater working fluid water inlet 29-1 through the first low pressure heater 28. Working fluid water from the condensate pump 26 is heated by the first low-pressure heater 28 and then sent to the low-pressure heater 29 and the bypass economizer 15 respectively. Typically, the first low pressure heater 28 is heated using steam extraction from the steam turbine 25 or other heat source (not shown).

Fig. 10-1 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 10, a spray tower 12 is connected in series between the desulfurizing tower 6 and the chimney 7; a second air supply heater 100 is provided in an air supply passage through which the air supply inlet 9-1 of the air supply heater is directly or indirectly connected, and the connection between the spray tower 12 and the second air supply heater 100 is described with reference to the embodiment of fig. 2. Features refer to fig. 10 and 9-1.

Fig. 10-2 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 10, a spray tower 12 and an absorption heat pump 90 are further arranged, and the connection mode of the spray tower 12 and the absorption heat pump 90 refers to the embodiment of fig. 3-1.

Fig. 10-3 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 10, there are also a spray tower 12 and an absorption heat pump 90, and the connection between the spray tower 12 and the absorption heat pump 90 is described with reference to the embodiment of fig. 3-2.

Fig. 10-4 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 10-2, a first blast heater 80 is also provided. The connection mode of the first air supply heater 80 refers to the embodiment of fig. 6 or 8. Features refer to fig. 10, 9-4.

Fig. 10-5 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 10-2, a second blast heater 100 is also provided. The connection mode of the second blower heater 100 refers to the embodiment of fig. 7. Features are shown in fig. 10 and 9-1.

Fig. 11 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 11, unlike the embodiment shown in fig. 9-2, the condensate pump outlet 26-2 is in direct or indirect communication with the flue heat exchanger working fluid water inlet 22-3; the flue heat exchanger working medium water outlet 22-4 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3.

The working process is as follows:

working medium water from the condensate pump outlet 26-2 is directly or through a first buffer water tank or/and a first bypass working medium water pump or/and a heater to the flue heat exchanger working medium water inlet 22-3, enters the flue heat exchanger 22, exchanges heat with flue gas, and flows out through the flue heat exchanger working medium water outlet 22-4, working medium water (whole or part) from the flue heat exchanger working medium water outlet 22-4 enters the bypass economizer 15 through the bypass economizer working medium water inlet 15-3, exchanges heat with higher-temperature flue gas, further heats up and flows out through the bypass economizer working medium water outlet 15-4, working medium water (whole or part) from the bypass economizer working medium water outlet 15-4 enters the boiler 1 through the boiler working medium water inlet 1-5, flows out from the boiler steam outlet 1-4 after being heated to high-pressure steam in the boiler 1, is sent to the steam turbine 25 to do work, is discharged to the condenser 27 to be cooled to be working medium water, and enters the condensate pump inlet 26-1, and circulates in sequence.

The advantage of this embodiment is that the flow rate and heat capacity of the flue gas from the boiler 1 are both greater than the flow rate and heat capacity of the air fed from the blower 8, so that it is difficult to fully utilize the flue gas waste heat by heating the air fed. The flue gas waste heat from the flue gas outlet 2-2 of the air preheater is utilized to heat the working medium water from the condensate pump 26, so that the flue gas waste heat can be recovered more and the flue gas waste heat can be utilized more fully.

Fig. 11-1 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 11-1, unlike the embodiment shown in fig. 9-3, the condensate pump outlet 26-2 is in direct or indirect communication with the flue heat exchanger working fluid water inlet 22-3; the flue heat exchanger working medium water outlet 22-4 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3.

Fig. 11-2 is a schematic structural view of another embodiment of the boiler flue gas waste heat recovery system of the present invention. In addition to fig. 11, a first blower heater 80 is also provided. The connection mode of the first air supply heater 80 refers to the embodiment of fig. 6 or 8.

Fig. 11-3 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. On the basis of fig. 11-1, a first blast heater 80 is also provided. The connection mode of the first air supply heater 80 refers to the embodiment of fig. 6 or 8.

Fig. 11-4 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. In addition to fig. 11, a second blast heater 100 is also provided. The connection mode of the second blower heater 100 refers to the embodiment of fig. 7.

Fig. 11-5 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. A second blast heater 100 is also provided on the basis of fig. 11-1. The connection mode of the second blower heater 100 refers to the embodiment of fig. 7.

Fig. 11-6 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

11-6, unlike the embodiment of FIG. 9, the condensate pump outlet 26-2 is in direct or indirect communication with the flue heat exchanger working fluid water inlet 22-3; the flue heat exchanger working medium water outlet 22-4 is directly or indirectly communicated with the bypass economizer working medium water inlet 15-3.

Fig. 11-7 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention. A second blast heater 100 is also provided on the basis of fig. 11-6. The connection mode of the second blower heater 100 refers to the embodiment of fig. 2.

From the above, the invention realizes the full and deep recovery of the flue gas waste heat and converts the flue gas waste heat into high-grade heat energy, thereby greatly improving the usable range, the utilization value and the utilization efficiency of the flue gas waste heat; meanwhile, the invention also provides stronger adaptability and mode selectivity.

If the temperature difference between low-temperature heat medium water at the outlet of the spray tower and the air supply is large in heating seasons and when the heating load is high, part of heat medium water is heated and supplied by the second air supply heater 100 and is converted into high-grade heat energy through the air preheater and the bypass economizer; converting low-grade flue gas waste heat at an outlet of the air preheater into high-temperature working medium water heat energy at a working medium water outlet of the bypass economizer by using a flue heat exchanger, an air supply heater, the air preheater and the bypass economizer; and then the other part of heat medium water from the spray tower is used as a low-temperature heat source, the high-temperature working medium water bypassing the working medium water outlet of the economizer is used as a high-temperature driving heat source, the heat of the heat medium water from the spray tower is further recovered by utilizing the absorption heat pump, and the available heat output by the absorption heat pump system is large and the temperature level is high. Thereby greatly improving the recovery efficiency and the utilization efficiency of the waste heat of the flue gas.

When there is no heating demand in non-heating season or outside the system, working medium water at the working medium water outlet of the flue heat exchanger is used as a high-temperature driving heat source, the waste heat of the flue gas is recovered through the absorption heat pump and the spray tower, the first air supply heater is used for heating and supplying air, and the waste heat is converted into high-temperature flue gas heat energy at the flue gas inlet of the bypass economizer through the air preheater and the bypass economizer; and converting the low-grade flue gas waste heat at the outlet of the air preheater into high-temperature flue gas heat energy at the flue gas inlet of the bypass economizer by using the flue heat exchanger, the air supply heater, the air preheater and the bypass economizer. The bypass economizer and the high-temperature flue gas at the flue gas inlet of the bypass economizer are used for heating working medium water from the condensate pump outlet or the water supply pump outlet, so that the working capacity and the working efficiency of the steam turbine can be greatly improved, the power generation coal consumption can be greatly reduced when the bypass economizer is used for generating power, and the energy saving efficiency is improved.

In practical application, the first air supply heater and the second air supply heater may be combined into one, which is called as a common air supply heater. In heating season, the environment temperature is low, the heat medium water from the spray tower and the common air supply heater are used for heating and air supply, and the heat exchange efficiency is high; in non-heating seasons, the environment temperature is high, the temperature difference between the heat medium water at the heat medium water outlet of the spray tower and the air supply is small, the heat exchange efficiency is low, the heat of the heat medium water at the heat medium water outlet of the spray tower can be recovered by utilizing the absorption heat pump and converted into medium-temperature heat energy of cold water at the outlet (the condenser cooling water outlet or/and the absorber cold water outlet) of the absorption heat pump with high temperature, and the heat source of the common air supply heater is changed into the cold water at the outlet of the absorption heat pump, so that the heat exchange efficiency is improved. Meanwhile, the absorption heat pump in non-heating seasons also exerts investment value.

Fig. 11-8 are schematic structural views of another embodiment of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 11-8, the bypass economizer 15 differs from fig. 11 in that it includes a first stage bypass heat exchange module 15a and a second stage bypass heat exchange module 15b connected in series one after the other; the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet 15-1, a first-stage bypass heat exchange module flue gas outlet 15a-2, a first-stage bypass heat exchange module working medium water inlet 15a-3 and a bypass economizer working medium water outlet 15-4; the second-stage bypass heat exchange module 15b is provided with a second-stage bypass heat exchange module smoke inlet 15b-1, a bypass economizer smoke outlet 15-2, a bypass economizer working medium water inlet 15-3 and a second-stage bypass heat exchange module working medium water outlet 15b-4; the first-stage bypass heat exchange module flue gas outlet 15a-2 is directly or indirectly communicated with the second-stage bypass heat exchange module flue gas inlet 15b-1, and the second-stage bypass heat exchange module working medium water outlet 15b-4 is simultaneously directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet 15a-3 and the generator high-temperature heat source inlet 93-1; the high-temperature heat source outlet 93-2 of the generator is directly or indirectly communicated with the working medium water inlet 15-3 of the bypass economizer.

The working process is as follows:

FIG. 12 is a schematic diagram of one embodiment of a desulfurizing tower and a spray tower in some embodiments of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 12, in the boiler flue gas waste heat recovery system, the spray tower 12 is disposed above the desulfurizing tower 6, and the desulfurizing tower 6 and the spray tower 12 are connected through the liquid collecting device 12-7 to form a desulfurizing and spraying integrated structure. The desulfurization spraying integrated structure is internally provided with a slurry pool 6-3, a desulfurization tower flue gas inlet 6-5, a desulfurization tower spraying device 6-6, a desulfurization tower demister 6-7, a liquid collecting device 12-7, a spray tower water distributing device 12-6 and a spray tower flue gas outlet 12-2 from bottom to top.

The liquid collecting device 12-7 is a multifunctional integrated structure comprising the flue gas outlet 6-4 of the desulfurizing tower, the flue gas inlet 12-1 of the spraying tower and the water receiving device 12-5 of the spraying tower, the flue gas from the desulfurizing tower 6 can enter the spraying tower 12 through the liquid collecting device 12-7, and the heat medium water from the water distributing device 12-6 of the spraying tower falls into the liquid collecting device 12-7 to be collected, and is led out of the spraying tower 12 through the heat medium water outlet 12-4 of the spraying tower to be incapable of flowing into the desulfurizing tower 6.

The tower wall of the tower body above the liquid collecting device 12-7 (the spray tower body in the present embodiment) and the tower wall of the tower body below the liquid collecting device 12-7 (the desulfurizing tower body in the present embodiment) can be directly connected, and the liquid collecting device 12-7 is arranged in the combined part of the tower wall of the tower body above the liquid collecting device 12-7 and the tower wall of the tower body below the liquid collecting device 12-7 and is separated up and down by the liquid collecting device 12-7; the tower wall of the tower body above the liquid collecting device 12-7 can be connected with the liquid collecting device 12-7, and then the liquid collecting device 12-7 is connected with the tower wall of the tower body below the liquid collecting device.

The structure has the advantages of saving occupied space, reducing system resistance and having great advantages especially for the improvement of the existing unit. The liquid collecting device 12-7 can be a water receiving disc commonly used in single-tower double-circulation, a liquid collector commonly used in the chemical industry, a liquid collector and the like, so long as the functional requirements of the liquid collecting device are met.

FIG. 13 is a schematic view of an embodiment of a liquid collection device in some embodiments of the boiler flue gas waste heat recovery system of the present invention.

As shown in fig. 13, the liquid collecting device 12-7 has a liquid collecting and demisting integrated structure with demisting function. The liquid collecting and demisting integrated structure comprises a liquid collecting chassis 12-8, a gas lift pipe 12-9 and a gas lift cap 12-10. The liquid collecting chassis 12-8 is provided with a plurality of vent holes 12-11, the vent holes 12-11 are correspondingly provided with the gas raising pipes 12-9, the top ends of the gas raising pipes 12-9 are provided with the gas raising caps 12-10, and gas raising channels 12-13 for flue gas circulation are arranged between the gas raising caps 12-10 or between the gas raising caps 12-10 and the top ends of the gas raising pipes 12-9 or on the pipe wall of the upper section of the gas raising pipes 12-9; the draft tube 12-9 is provided with guide vanes or swirlers 12-12 therein (fig. 13a, 13b are schematic structural views of an embodiment of the guide vanes); the liquid collecting chassis 12-8 is provided with a water blocking edge 12-4 or the liquid collecting chassis 12-8 is in sealing connection with the inner wall of the tower body of the desulfurization spraying integrated structure and takes the inner wall of the desulfurization spraying integrated structure as a water blocking edge 12-14, an upward opening space enclosed between the liquid collecting chassis 12-8 and the water blocking edge 12-14 is taken as a spray tower water receiving device 12-5, and the spray tower water receiving device 12-5 is communicated with the spray tower heating medium water outlet 12-4. The guide vane or the cyclone 12-12 is fixedly arranged in the gas lift pipe, and when the flue gas flows through the guide vane or the cyclone from bottom to top, the flue gas generates high-speed rotation taking the central line of the gas lift pipe as the center and moves in a spiral ascending manner under the guide effect.

The structure can purify the flue gas entering the spray tower 12, reduce the pollution of the flue gas to the heat medium water, and simultaneously reduce the height of the desulfurization and spray integrated structure.

The working principle is as follows: the flue gas with particles and fog drops from the desulfurizing tower 6 flows upwards into the gas lift pipe 12-9 in the liquid collecting and demisting integrated structure 12-7, the flue gas rotates at a high speed and ascends around the central line of the gas lift pipe 12-9 under the action of the guide vane or the cyclone 12-12 in the gas lift pipe 12-9, namely, the flue gas moves in a spiral ascending mode, the particles and the fog drops collide with each other and are condensed into large particles, the large particles and the fog drops as well as the heavy particles with a specific gravity are thrown to the pipe wall of the gas lift pipe 12-9 under the action of centrifugal force to be trapped, and then flow downwards under the action of gravity, so that the separation and removal of the particles, the fog drops and the flue gas are realized. The flue gas continues to flow upwards to the gas raising cap 12-10, flows into the spray tower 12 from the gas raising cap itself or the gas raising channel 12-13 arranged between the top end of the gas raising cap 12-10 and the gas raising pipe 12-9 or on the pipe wall of the upper section of the gas raising pipe 12-9, flows upwards to be mixed and heat exchanged with the heat medium water falling from the spray tower water distribution device 12-6 from top to bottom in countercurrent, and then the temperature, humidity and pollutants of the flue gas are further reduced, and flows out of the spray tower 12 through the spray tower flue gas outlet 12-2. The heat medium water from the spray tower water distribution device 12-6 falls into the spray tower water receiving device 12-5 from top to bottom, and the heat medium water together with condensed water condensed and separated from the flue gas is led out of the spray tower 12 through the spray tower heat medium water outlet 12-4. The function of the gas-raising cap 12-10 is to enable the flue gas from the desulfurizing tower 6 to flow into the spraying tower 12, while the heat medium water from the water distribution device 12-6 of the spraying tower 12 cannot flow into the desulfurizing tower 6. The lift cap may take the shape of a cap, a shutter, or other commercially available lift cap forms, as long as the above-described function is achieved. The air lifting cap and the air lifting pipe can be of an integrated structure or a split structure. One of the gas risers may correspond to one of the gas caps, or two or more of the gas risers may share one of the gas caps.

It is possible to take the form of a structure in which the outer diameter of the gas-raising cap 12-10 is larger than the outer diameter of the gas-raising tube 12-9, that is, the vertical projection of the gas-raising cap 12-10 is completely covered and larger than the vertical projection of the gas-raising tube. Since the diameter of the gas-raising cap 12-10 is larger than the outer diameter of the gas-raising pipe 12-9, the heat medium water cannot flow into the gas-raising pipe 12-9, that is, cannot flow into the desulfurizing tower 6.

The distance of each of the risers 12-9 can be appropriately adjusted as needed to provide the desired volume of the heat medium water reservoir.

The liquid collecting device 12-7 can also adopt the structure shown in fig. 13-1, a demisting pipe 12-15 is connected below the gas raising pipe 12-9, and a guide vane or a cyclone is arranged in the demisting pipe. The working principle is basically the same as that of the prior art.

The liquid collecting device 12-7 can also adopt the structure shown in fig. 13-2, a demisting pipe 12-15 is arranged in the gas raising pipe 12-9, and guide vanes or swirlers are arranged in the demisting pipe. The working principle is basically the same as that of the prior art.

The riser pipe 12-9 and the demisting pipe 12-15 can be separated or integrated.

Optionally, the water blocking edge is connected with the tower body above the liquid collecting device (the tower body of the spray tower in the embodiment) or/and the tower body below the liquid collecting device (the tower body of the desulfurizing tower in the embodiment) to form an integrated structure. The tower wall of the tower body above the liquid collecting device 12-7 and the tower wall of the tower body below the liquid collecting device 12-7 can be directly connected, the liquid collecting device 12-7 is arranged in the combination part of the tower wall of the tower body above the liquid collecting device 12-7 and the tower wall of the tower body below the liquid collecting device 12-7, and is vertically separated through the liquid collecting device 12-7, the inner wall of the tower body above the liquid collecting device 12-7 can be used as a water blocking edge, and the liquid collecting and demisting integrated structure can also be provided with a water blocking edge on the liquid collecting chassis; the tower wall of the tower body above the liquid collecting device 12-7 can be connected with the water blocking edge of the liquid collecting device 12-7, and then the water blocking edge of the liquid collecting device 12-7 is connected with the tower wall of the tower body below the water blocking edge.

Fig. 13-3 are schematic structural views of another embodiment of a liquid collection device in some embodiments of the boiler flue gas waste heat recovery system of the present invention.

Fig. 13-4 are schematic structural views of an embodiment of an air cap of a liquid collection device.

13-3 and 13-4, on the basis of FIG. 13, the lift cap 12-10 adopts a tower-type shutter structure with a small top and a large bottom, and flue gas from below the lift cap 12-10 can flow to above the lift cap 12-10 through the lift cap 12-10, but heat medium water from above the lift cap 12-10 cannot flow to below the lift cap 12-10 through the lift cap 12-10; in addition, the outer diameter of the riser cap and the outer diameter of the riser are smaller than or equal to the inner diameter of the vent hole 12-11 on the liquid collecting chassis 12-8, so that the riser 12-9 and the riser cap 12-10 can be pulled out from the lower part of the liquid collecting chassis 12-8 for maintenance. The purpose is mainly to reduce the height of the desulfurization spraying integrated structure.

Fig. 14 is a schematic structural view of another embodiment of a desulfurizing tower and a spray tower in some embodiments of the boiler flue gas waste heat recovery system of the present invention.

As shown in FIG. 14, a filler layer 12-16 is disposed between the liquid collecting device 12-7 and the water distributing device 12-6. The advantages are that: when the flow rate of the heating medium is fixed, the residence time and the heat transfer area of the heating medium can be improved, and the heat exchange efficiency and the outlet water temperature can be improved.

As shown in fig. 15, on the basis of fig. 3-3, a bypass flue gas control baffle 15-8 is provided on a flue gas diversion branch from the boiler flue gas outlet 1-3 to the bypass economizer flue gas inlet 15-1 (on the bypass economizer flue gas inlet diversion branch) for adjusting the flue gas flow rate entering the flue gas channel of the bypass economizer 15.

The working principle is as follows:

the opening of the bypass flue gas control baffle 15-8 is adjusted to adjust the flue gas flow entering the flue gas channel of the bypass economizer 15 and the ratio between the flue gas flow entering the flue gas channel of the air preheater 2, so that the flue gas temperature of the flue gas outlet 2-2 of the air preheater, the working medium water temperature of the working medium water outlet 22-4 of the flue heat exchanger and the working medium water temperature of the working medium water outlet 15-4 of the bypass economizer can be adjusted.

At present, the main problems of the boiler unit are as follows: firstly, the flue gas temperature is low under low load, so that the denitration efficiency is ensured, a large amount of ammonium bisulfate is generated due to excessive ammonia spraying of a denitration system, and then the ammonium bisulfate is deposited on heat exchange elements of an air preheater and a flue heat exchanger, so that blocking corrosion is caused; secondly, the flue heat exchanger for recycling the waste heat of the flue gas has the problems of abrasion, corrosion, leakage, blockage and the like, and seriously affects the operation of a unit; thirdly, under the condition of adopting electric dust removal, if the smoke temperature at the outlet of the air preheater is too high, the electric dust removal efficiency after the air preheater is arranged is reduced; and fourthly, the resistance of the flue is large, the load capacity of the unit is influenced, and the power consumption of the fan is increased.

The system and the method provided by the embodiment can solve the problems and further improve the recycling efficiency of the waste heat of the flue gas: in the normal operation stage, on the premise of ensuring that the air supply temperature of the air supply outlet of the air preheater is within a certain range, the bypass flue gas control baffle 15-8 is opened, the bypass flue gas flow is increased, the flue gas temperature of the air preheater flue gas outlet is reduced as much as possible, and the flue gas waste heat can be converted into the high-temperature heat energy of the bypass economizer. Meanwhile, as the outlet smoke temperature of the air preheater is reduced, namely the inlet smoke temperature of the dust remover is low, the flue heat exchanger can be arranged behind the dust remover on the premise of ensuring the dust removal efficiency, so that the abrasion problem of the flue heat exchanger is solved. Because the air preheater and the dust remover are covered by dust, and the leakage risk is avoided, the flue gas temperature at the outlet of the air preheater is reduced as much as possible, and ammonium bisulfate can be trapped in the air preheater and the dust remover, so that the influence on the flue heat exchanger is reduced. When the ammonium bisulfate blockage in the air preheater reaches a certain degree, the bypass flue gas control baffle 15-8 can be closed or turned off in a staged way, and the flue gas waste heat at the outlet of the air preheater or/and the flue gas waste heat after desulfurization are returned to the air preheater by utilizing the absorption heat pump and the first air supply heater 80 by utilizing the heat exchanger 22 and the air supply heater 9, and the temperature in the air preheater and the flue gas temperature at the outlet of the air preheater can be greatly increased to the ammonium bisulfate gasification temperature, and the air preheater is cleaned by utilizing the soot blower in a matched manner, so that the normal operation is recovered. In addition, by utilizing the bypass economizer and the bypass flue gas baffle, the flue resistance and the fan power consumption can be reduced, and meanwhile, the areas of the flue heat exchanger and the air supply heater can be reduced, so that the flue resistance and the air supply channel resistance are reduced, and the power consumption of the induced draft fan and the air supply fan is reduced.

The bypass flue gas control baffle 15-8 may also be disposed on a flue gas diversion branch of the bypass economizer flue gas outlet 15-2.

The foregoing description is only exemplary of the invention and is not intended to limit the scope of the invention. Equivalent alterations, modifications and combinations will be effected by those skilled in the art without departing from the spirit and principles of this invention.

Claims

1. A boiler flue gas waste heat recovery system, comprising: the boiler comprises a boiler, a bypass economizer, an air preheater, a flue heat exchanger, a desulfurizing tower, a chimney, a blower and a blast heater; wherein,,

the blower is provided with a blower inlet and a blower outlet;

2. The system for recycling flue gas waste heat of a boiler according to claim 1, wherein a spray tower is connected in series between the desulfurizing tower and the chimney; a second air supply heater is also arranged;

3. The boiler flue gas waste heat recovery and utilization system according to claim 1, further comprising a spray tower and an absorption heat pump;

The bypass economizer working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, and the generator high-temperature heat source outlet is directly or indirectly communicated with the bypass economizer working medium water inlet; or the working medium water outlet of the flue heat exchanger is directly or indirectly communicated with the high-temperature heat source inlet of the generator, and the high-temperature heat source outlet of the generator is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; or the generator high-temperature heat source channel is connected in series with the working medium water channel between the flue heat exchanger working medium water outlet and the air supply heater working medium water inlet, the flue heat exchanger working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, the generator high-temperature heat source outlet is directly or indirectly communicated with the air supply heater working medium water inlet, and the air supply heater working medium water outlet is directly or indirectly communicated with the flue heat exchanger working medium water inlet; or the flue heat exchanger working medium water channel, the bypass economizer working medium water channel, the generator working medium water channel and the air supply heater working medium water channel are sequentially connected in series from beginning to end; the flue heat exchanger working medium water outlet is directly or indirectly communicated with the bypass economizer working medium water inlet; the bypass economizer working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet; the high-temperature heat source outlet of the generator is directly or indirectly communicated with the working medium water inlet of the air supply heater; the working medium water outlet of the air supply heater is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; or the bypass economizer comprises a first-stage bypass heat exchange module and a second-stage bypass heat exchange module which are connected in series back and forth, wherein the first-stage bypass heat exchange module is provided with a bypass economizer flue gas inlet, a first-stage bypass heat exchange module flue gas outlet, a first-stage bypass heat exchange module working medium water inlet and a bypass economizer working medium water outlet; the second-stage bypass heat exchange module is provided with a second-stage bypass heat exchange module smoke inlet, a bypass economizer smoke outlet, a bypass economizer working medium water inlet and a second-stage bypass heat exchange module working medium water outlet, the first-stage bypass heat exchange module smoke outlet is directly or indirectly communicated with the second-stage bypass heat exchange module smoke inlet, the second-stage bypass heat exchange module working medium water outlet is simultaneously directly or indirectly communicated with the first-stage bypass heat exchange module working medium water inlet and the generator high-temperature heat source inlet, and the generator high-temperature heat source outlet is directly or indirectly communicated with the bypass economizer working medium water inlet; optionally, a bypass header or/and a first bypass deaerator or/and a first bypass water supply pump are connected in series on a branch working medium water channel between the working medium water outlet of the second-stage bypass heat exchange module and the working medium water inlet of the first-stage bypass heat exchange module;

4. A boiler flue gas waste heat recovery system according to claim 3, wherein the absorber cold water outlet or the condenser cooling water outlet is also in direct or indirect communication with the flue heat exchanger working fluid water inlet; the working medium water outlet of the flue heat exchanger is also directly or indirectly communicated with a heat user; or a cold water channel directly or indirectly communicated with the condenser cooling water outlet is connected with a cold water reheater in series; the cold water reheater is provided with a cold water inlet of the cold water reheater, a cold water outlet of the cold water reheater, a heat source inlet of the cold water reheater and a heat source outlet of the cold water reheater; the cold water inlet of the cold water reheater is directly or indirectly communicated with the condenser cooling water outlet; the cold water outlet of the cold water reheater is directly or indirectly communicated with a hot user; the heat source inlet of the cold water reheater is directly or indirectly communicated with the working medium water outlet of the flue heat exchanger; the heat source outlet of the cold water reheater is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; optionally, a second cooler is connected in series between the cold water reheater heat source outlet and the flue heat exchanger working medium water inlet; the cold water reheater is a dividing wall type heat exchanger; optionally, the cold water reheater is a plate heat exchanger.

5. The boiler flue gas waste heat recovery and utilization system according to claim 3 or 4, further comprising a first absorption heat pump; the first absorption heat pump comprises a first evaporator, a first absorber, a first generator and a first condenser; the first evaporator is provided with a first evaporator low temperature heat source inlet, a first evaporator low temperature heat source outlet, a first evaporator refrigerant water inlet and a first evaporator refrigerant water vapor outlet; the first absorber is provided with a first absorber cold water inlet, a first absorber cold water outlet, a first absorber refrigerant water vapor inlet, a first absorber concentrated absorbent solution inlet and a first absorber diluted absorbent solution outlet; the first generator is provided with a first generator high-temperature heat source inlet, a first generator high-temperature heat source outlet, a first generator dilute absorbent solution inlet, a first generator concentrated absorbent solution outlet and a first generator refrigerant water vapor outlet; the first condenser is provided with a first condenser cooling water inlet, a first condenser cooling water outlet, a first condenser refrigerant water vapor inlet and a first condenser refrigerant water outlet; the first evaporator refrigerant water inlet is in direct or indirect communication with the first condenser refrigerant water outlet; the first evaporator refrigerant vapor outlet is in direct or indirect communication with the first absorber refrigerant vapor inlet; the first absorber concentrated absorbent solution inlet is in direct or indirect communication with the first generator concentrated absorbent solution outlet; the first absorber lean absorbent solution outlet is in direct or indirect communication with the first generator lean absorbent solution inlet; the first generator refrigerant vapor outlet is in direct or indirect communication with the first condenser refrigerant vapor inlet; the first absorber cold water outlet is directly or indirectly communicated with the first condenser cooling water inlet; the absorption heat pump forms a heat-increasing type absorption heat pump;

When the second-stage bypass heat exchange module economizer working medium water outlet is directly or indirectly communicated with the generator high-temperature heat source inlet, and the generator high-temperature heat source outlet is directly or indirectly communicated with the bypass economizer working medium water inlet, the first generator high-temperature heat source channel is connected in series with the working medium water channel between the generator high-temperature heat source outlet and the bypass economizer working medium water inlet, and the first generator high-temperature heat source inlet is directly or indirectly communicated with the generator high-temperature heat source outlet; the high-temperature heat source outlet of the first generator is directly or indirectly communicated with the working medium water inlet of the bypass economizer;

6. The boiler flue gas waste heat recovery and utilization system according to any one of claims 3 to 5, further comprising a first supply air heater; the first air supply heater is provided with a first air supply heater air supply inlet, a first air supply heater air supply outlet, a first air supply heater cold water inlet and a first air supply heater cold water outlet; the air supply channel of the first air supply heater is connected in series with an air channel which is directly or indirectly communicated with the air supply inlet of the air blower or the air supply outlet of the air blower; the air supply outlet of the first air supply heater is directly or indirectly communicated with the air supply inlet of the air supply heater; the first air supply heater cold water inlet is directly or indirectly communicated with the condenser cooling water outlet; the first air supply heater cold water outlet is directly or indirectly communicated with the absorber cold water inlet; when the first absorption heat pump is further arranged, the cold water outlet of the first air supply heater is directly or indirectly communicated with the cold water inlet of the first absorber; optionally, the first air supply heater is a dividing wall type heat exchanger; optionally, a cold water pump is arranged on a cold water channel which is directly or indirectly communicated with the cold water inlet of the absorber or the cold water outlet of the condenser.

7. The boiler flue gas waste heat recovery and utilization system according to any one of claims 3 to 6, further comprising a second air supply heater; the second air supply heater is provided with a second air supply heater air supply inlet, a second air supply heater air supply outlet, a second air supply heater heating medium water inlet and a second air supply heater heating medium water outlet; the air supply channel of the second air supply heater is connected in series with the air channel which is directly or indirectly communicated with the air supply inlet of the air blower or the air supply outlet of the air blower; the air supply outlet of the second air supply heater is directly or indirectly communicated with the air supply inlet of the air supply heater; preferably, when the first air supply heater is provided, the second air supply heater air supply outlet is directly or indirectly communicated with the first air supply heater air supply inlet; the second air supply heater heating medium water inlet is directly or indirectly communicated with the spray tower heating medium water outlet; the second air supply heater heating medium water outlet is directly or indirectly communicated with the spray tower heating medium water inlet; optionally, the second supply air heater is a dividing wall heat exchanger.

8. The system for recycling flue gas waste heat of a boiler according to any one of claims 1 to 7, further comprising a steam turbine, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feed pump, and a high-pressure heater;

9. The system for recycling waste heat of flue gas of a boiler according to any one of claims 1 to 7, further comprising a steam turbine, a condenser, a condensate pump, a low-pressure heater, a deaerator, a water feed pump, and a high-pressure heater;

10. The system of claim 8, wherein the condensate pump outlet is in direct or indirect communication with the bypass economizer working medium water inlet through the flue heat exchanger; the outlet of the condensate pump is directly or indirectly communicated with the working medium water inlet of the flue heat exchanger; the flue heat exchanger working medium water outlet is directly or indirectly communicated with the bypass economizer working medium water inlet; the bypass economizer working medium water outlet is directly or indirectly communicated with the boiler working medium water inlet; optionally, a first bypass buffer water tank or/and a first bypass working medium water pump or/and a heater are arranged on a working medium water channel between the condensate pump outlet and the flue heat exchanger working medium water inlet.

11. The system for recycling waste heat of boiler flue gas according to any one of claims 2 to 10, wherein the spray tower is arranged above the desulfurizing tower, the desulfurizing tower and the spray tower are connected through a liquid collecting device to form a desulfurizing and spraying integrated structure, and the slurry pool, the flue gas inlet of the desulfurizing tower, the spraying device of the desulfurizing tower, the liquid collecting device, the water distributing device of the spraying tower and the flue gas outlet of the spraying tower are arranged in the desulfurizing and spraying integrated structure from bottom to top; the liquid collecting device is of a multifunctional integrated structure comprising a flue gas outlet of the desulfurizing tower, a flue gas inlet of the spraying tower and a water receiving device of the spraying tower, flue gas from the desulfurizing tower can enter the spraying tower through the liquid collecting device, heat medium water from the spraying tower falls into the liquid collecting device to be collected, and is guided out of the liquid collecting device through the heat medium water outlet of the spraying tower to be incapable of flowing into the desulfurizing tower; optionally, a filler layer is arranged between the liquid collecting device and the spray tower water distribution device.

12. The boiler flue gas waste heat recovery and utilization system according to claim 11, wherein the liquid collecting device is a liquid collecting and demisting integrated structure with demisting function, and the liquid collecting and demisting integrated structure comprises a liquid collecting chassis, a gas lifting pipe and a gas lifting cap; the liquid collecting chassis is provided with a plurality of vent holes, the vent holes are correspondingly provided with the gas lifting pipes, the top ends of the gas lifting pipes are provided with gas lifting caps, and gas lifting channels for the circulation of flue gas are arranged on the gas lifting caps or between the gas lifting caps and the top ends of the gas lifting pipes or on the pipe walls of the upper sections of the gas lifting pipes; a guide vane or a cyclone is arranged in the gas lift pipe, or/and a demisting pipe is connected below the gas lift pipe or arranged in the gas lift pipe, and the guide vane or the cyclone is arranged in the demisting pipe; the gas lifting pipe and the demisting pipe are of a split structure or an integrated structure; the liquid collecting chassis is provided with a water retaining edge or is in sealing connection with the inner wall of the tower body of the desulfurization spraying integrated structure, the inner wall of the desulfurization spraying integrated structure is used as the water retaining edge, an upward opening space enclosed between the liquid collecting chassis and the water retaining edge is used as a spray tower water receiving device, and the spray tower water receiving device is directly or indirectly communicated with a spray tower heating medium water outlet; optionally, the lift cap adopts a tower-type shutter structure, the outer diameter of the lift cap and the outer diameter of the lift pipe are smaller than or equal to the inner diameter of the vent hole on the liquid collecting chassis, and the lift pipe and the lift cap are installed in a mode of being detachable from the liquid collecting chassis.

13. A boiler flue gas waste heat recovery and utilization system according to any one of claims 1-12, wherein a bypass flue gas control baffle is provided on the bypass economizer flue gas inlet or the flue gas diversion branch of the bypass economizer flue gas outlet for adjusting the flue gas flow into the bypass economizer flue gas channel.

14. A method for recycling waste heat of boiler flue gas is characterized in that fuel is fed into a hearth of a boiler, an air blower feeds air into the hearth of the boiler through an air preheater, the fuel burns to release heat, and flue gas generated by combustion flows out of the boiler; then a part of flue gas is sent into an air preheater to heat the air supply from the blower, and the flue gas exchanges heat with the air supply to cool and then flows out of the air preheater; a part of flue gas enters a bypass economizer, exchanges heat with working medium water and then flows out of the bypass economizer; flue gas from a flue gas outlet of the air preheater and flue gas from a flue gas outlet of the bypass economizer directly or indirectly enter a flue heat exchanger through other equipment (such as a dust remover or/and an induced draft fan), exchange heat with working medium water, cool down and flow out of the flue heat exchanger, and then directly or indirectly flow into the desulfurizing tower through other equipment (such as the dust remover or/and the induced draft fan);

Optionally, the bypass economizer comprises a first-stage bypass heat exchange module and a second-stage bypass heat exchange module which are connected in series front and back; the flue gas from the boiler passes through the first-stage bypass heat exchange module and the second-stage bypass heat exchange module in sequence, exchanges heat with working medium water, cools down and then is sent to a flue heat exchanger; the working medium water is firstly sent to the first-stage bypass heat exchange module to be further subjected to heat exchange with the smoke with higher temperature after being subjected to heat exchange and temperature rise of the second-stage bypass heat exchange module and the smoke, and then is sent to a heat user, optionally, the working medium water is firstly sent to the bypass header after being subjected to heat exchange and temperature rise of the second-stage bypass heat exchange module and the smoke, or/and is sent to the first-stage bypass heat exchange module to be subjected to heat exchange and temperature rise of the smoke with higher temperature after being subjected to deoxidization by the first bypass deaerator or/and is sent to the first-stage bypass heat exchange module after being subjected to pressure rise by the first bypass feed pump.

15. The method for recycling flue gas waste heat of a boiler according to claim 14, wherein a spray tower is connected in series between the desulfurizing tower and the chimney; the air supply channel of the second air supply heater is connected in series with an air channel which is directly or indirectly communicated with the air supply inlet of the blower or the air supply outlet of the blower, and the air supply outlet of the second air supply heater is directly or indirectly communicated with the air supply inlet of the air supply heater; the desulfurized saturated or nearly saturated flue gas enters a spray tower, the heat medium water from a second air supply heater is scattered into the flue gas through a spray tower water distribution device, the flue gas and the heat medium water are mixed for heat exchange, the saturated flue gas is further cooled, dehumidified and washed, and then the saturated flue gas is discharged into the atmosphere through a spray tower flue gas outlet and a chimney;

16. The method for recycling flue gas waste heat of a boiler according to claim 14, wherein a spray tower and an absorption heat pump are further provided; the absorption heat pump comprises an evaporator, an absorber, a generator and a condenser; the saturated or nearly saturated flue gas after desulfurization enters a spray tower, hot medium water from a low-temperature heat source outlet of an evaporator is scattered into the flue gas through a spray tower water distribution device, the flue gas and the hot medium water are mixed for heat exchange, the saturated flue gas is further cooled, dehumidified and washed, and then the saturated flue gas is discharged into the atmosphere through a spray tower flue gas outlet and a chimney;

or the bypass economizer comprises a first-stage bypass heat exchange module and a second-stage bypass heat exchange module which are connected in series front and back; the flue gas from the boiler passes through the first-stage bypass heat exchange module and the second-stage bypass heat exchange module in sequence, exchanges heat with working medium water, cools down and then is sent to a flue heat exchanger; after the heat exchange and temperature rising of the working medium water between the second-stage bypass heat exchange module and the flue gas are carried out, a part of the working medium water is sent to the first-stage bypass heat exchange module to be further subjected to heat exchange and temperature rising with the flue gas with higher temperature, and then is sent to a heat user; part of the refrigerant water vapor is used as a high-temperature driving heat source, enters the generator, the dilute absorbent solution from the absorber in the generator is heated and concentrated by working medium water to form a concentrated absorbent solution, then enters the absorber, the dilute absorbent solution is heated and concentrated and generates refrigerant water vapor with higher temperature, and the refrigerant water vapor enters the condenser; the working medium water flows out of the absorption heat pump after heat exchange and temperature reduction and returns to the second-stage bypass heat exchange module for recycling; optionally, working medium water at a working medium water outlet of the second-stage bypass heat exchange module is subjected to deoxygenation through a bypass header or/and a first bypass deaerator or/and pressure rise through a first bypass water supply pump and then is sent to the first-stage bypass heat exchange module to be further subjected to heat exchange with flue gas with higher temperature to raise the temperature;

17. The method for recycling waste heat of boiler flue gas according to claim 16, wherein cold water from a condenser cooling water outlet and working medium water from a working medium water outlet of the air supply heater are sent to a flue heat exchanger to be heated by flue gas, and then are sent to the air supply heater to be heated and supplied with air partially, and are sent to a heat user to be used partially; or, part of cold water heated by the absorber is split into a flue heat exchanger working medium water inlet, and part of cold water and working medium water at a working medium water outlet of the air supply heater are heated by the flue heat exchanger, and then the part of cold water and working medium water are sent to the air supply heater for heating and air supply, and the part of cold water and working medium water are sent to a heat user for use; or, the device is also provided with a cold water reheater, cold water from a cooling water outlet of the condenser enters the cold water reheater, exchanges heat with high-temperature working medium water from a working medium water outlet of the flue heat exchanger in the cold water reheater, and flows out of the cold water reheater after being warmed up, and is sent to a hot user for use; the temperature of the working medium water is reduced after heat exchange with cold water, and the working medium water returns to the flue heat exchanger for recycling; optionally, a second cooler is connected in series between the cold water reheater heat source outlet and the flue heat exchanger working medium water inlet.

18. The method for recycling flue gas waste heat of a boiler according to claim 16 or 17, wherein a first absorption heat pump is further provided; the first absorption heat pump comprises a first evaporator, a first absorber, a first generator and a first condenser; the heat medium water from the spray tower enters a heat exchange tube in a first evaporator, the first evaporator is in a low-pressure (such as vacuum) state, the refrigerant water conveyed by the first condenser absorbs the heat of the heat medium water in the heat exchange tube and then evaporates to cool the heat medium water, and meanwhile, the refrigerant water vapor generated by evaporation enters a first absorber; the cooled heat medium water flows out of the first absorption heat pump and returns to the spray tower for recycling;

The high-temperature working medium water from the bypass economizer is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, the high-temperature driving heat source of the first absorption heat pump enters the first generator after heat exchange and cooling of the generator, and the high-temperature driving heat source of the first absorption heat pump flows out of the first absorption heat pump after further heat exchange and cooling of the generator and is returned to the bypass economizer for recycling; or the high-temperature working medium water from the second-stage bypass heat exchange module is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, the high-temperature driving heat source of the first absorption heat pump enters the first generator after the heat exchange and the cooling of the generator are firstly carried out, and the high-temperature driving heat source of the first absorption heat pump is further used as a high-temperature driving heat source of the first absorption heat pump and then flows out of the first absorption heat pump to be returned to the second-stage bypass heat exchange module for recycling; or, working medium water from the flue heat exchanger is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, enters the generator for heat exchange and cooling, and then flows out of the generator; then enters the first generator to exchange heat and cool down, and then flows out of the first generator to return to the flue heat exchanger for recycling; or the working medium water from the flue heat exchanger is sequentially used as a high-temperature driving heat source of the absorption heat pump and the first absorption heat pump, enters the generator for heat exchange and cooling, and then flows out of the generator; then enters the first generator to exchange heat and cool down, and then flows out of the first generator; then, the air is taken as a heating source of the air supply heater, enters the air supply heater to be heated, supplied with air and cooled, flows out, and returns to the flue heat exchanger for recycling; a heat source is driven at a high temperature to enter a first generator, in the first generator, a dilute absorbent solution from a first absorber is heated and concentrated by working medium water to form a concentrated solution, the concentrated solution enters the first absorber, the dilute absorbent solution is heated and concentrated and simultaneously generates refrigerant water vapor with higher temperature, and the refrigerant water vapor enters a first condenser; the working medium water used as a high-temperature driving heat source exchanges heat and cools and flows out of the first absorption heat pump;

19. The method for recycling flue gas waste heat of a boiler according to any one of claims 16 to 18, further comprising a first supply air heater; cold water from the condenser cooling water outlet is sent to the first air supply heater for heating and air supply, then cooled, and is sent back to the absorber cold water inlet for circulation; when the first absorption heat pump is further arranged, cold water is heated and blown by the first blowing heater and then cooled, and then is sent to a cold water inlet of the first absorber; the air supply is driven by the blower, passes through the first air supply heater, is heated by cold water from the cooling water outlet of the condenser, and is then heated by the air supply heater and the air preheater and then is fed into the boiler;

20. The method for recycling flue gas waste heat of a boiler according to any one of claims 16 to 19, further comprising a second blast heater; the heat medium water from the spray tower is directly or indirectly sent to a second air supply heater for heating and air supply, then the temperature is reduced, and the heat medium water returns to the spray tower for recycling; the air supply (air) is heated by the heat medium water from the spray tower through the second air supply heater under the drive of the blower, then continuously heated through the first air supply heater (if any), the air supply heater and the air preheater in sequence, and then sent into the boiler;

optionally, the second supply air heater is a dividing wall heat exchanger.

21. The method for recycling flue gas waste heat of a boiler according to any one of claims 14 to 20, further comprising: the device comprises a steam turbine, a condenser, a condensate pump, a low-pressure heater, a deaerator, a water supply pump and a high-pressure heater; the high-pressure high-temperature steam generated by boiler combustion is sent into a steam turbine to do work and then is discharged into a condenser to be cooled and condensed into working medium water (condensed water), then part of working medium water is sent into a low-pressure heater to be heated and flows out by the extraction steam from a low-pressure extraction steam outlet of the steam turbine under the driving of a condensed water pump, then is sent into a deaerator to be deoxidized, is sent into a high-pressure heater to be heated and flows out of the high-pressure heater after being heated by the extraction steam from the high-pressure extraction steam outlet of the steam turbine under the driving of a water supply pump; part of working medium water is directly or indirectly sent to a bypass economizer through other devices (such as a heater, a water pump and a buffer water tank) to exchange heat with the flue gas to raise the temperature, and then flows out of the bypass economizer; working medium water (all or part) from the high-pressure heater and the bypass economizer is sent to the boiler; the fuel from the fuel inlet of the boiler and the air supply from the air supply inlet of the boiler generate combustion reaction to release heat, the working medium water from the working medium water inlet of the boiler is heated to generate high-pressure high-temperature steam, and the high-pressure high-temperature steam is sent to the steam turbine through the steam outlet of the boiler to continuously do work, and the cycle is performed;

22. The method for recycling flue gas waste heat of a boiler according to any one of claims 14 to 20, further comprising: the device comprises a steam turbine, a condenser, a condensate pump, a low-pressure heater, a deaerator, a water supply pump and a high-pressure heater; the high-pressure high-temperature steam generated by boiler combustion is sent into a steam turbine to do work and then is discharged into a condenser to be cooled and condensed into working medium water (condensed water), then is sent into a low-pressure heater to be heated and flows out by the extraction steam from a low-pressure extraction steam outlet of the steam turbine under the driving of a condensed water pump, is then sent into a deaerator to flow out after deoxidization, then is sent into a high-pressure heater to be heated and flows out of the high-pressure heater by the extraction steam from a high-pressure extraction steam outlet of the steam turbine under the driving of a water supply pump; part of working medium water is directly or indirectly sent to a bypass economizer through other devices (such as a heater, a water pump and a buffer water tank) to exchange heat with the flue gas to raise the temperature, and then flows out of the bypass economizer; working medium water (all or part) from the high-pressure heater and the bypass economizer is sent to the boiler; the fuel from the fuel inlet of the boiler and the air supply from the air supply inlet of the boiler generate combustion reaction to release heat, the working medium water from the working medium water inlet of the boiler is heated to generate high-pressure high-temperature steam, and the high-pressure high-temperature steam is sent to the steam turbine through the steam outlet of the boiler to continuously do work, and the cycle is performed;

23. The method for recycling waste heat of boiler flue gas according to claim 22, wherein working medium water at the outlet of the condensate pump is sent to the bypass economizer through the flue heat exchanger; working medium water from the outlet of the condensate pump is directly or through a first buffer water tank or/and a first bypass working medium water pump or/and a heater sent to the flue heat exchanger, flows out after heat exchange and temperature rise with flue gas, and the working medium water (whole or part) from the working medium water outlet of the flue heat exchanger enters the bypass economizer to heat exchange with higher-temperature flue gas, flows out from the working medium water outlet of the bypass economizer after further temperature rise, and the working medium water (whole or part) from the working medium water outlet of the bypass economizer enters a boiler, flows out from the steam outlet of the boiler after being heated into high-temperature high-pressure steam in the boiler, works by being sent to a steam turbine, is discharged to the condenser to be cooled into condensate water, namely the working medium water, and enters the inlet of the condensate pump for circulation in sequence.

24. The boiler flue gas waste heat recovery and utilization system according to any one of claims 14-23, wherein: and a bypass flue gas control baffle is arranged on a flue gas diversion branch of the flue gas inlet of the bypass economizer or the flue gas outlet of the bypass economizer and is used for adjusting the flue gas flow entering the flue gas channel of the bypass economizer.

25. A method of boiler flue gas waste heat recovery according to any one of claims 14 to 24, carried out using a boiler flue gas waste heat recovery system according to any one of claims 1 to 13.