CN204373030U - Make full use of the step heating heating system of residual heat of electric power plant - Google Patents

Abstract

The utility model discloses a cascaded heating system for fully utilizing the waste heat of a power plant, which solves the problems in the prior art that the utilization rate of the waste heat of the power plant is not high and the adjustment of the heating temperature is inflexible. The utility model is a heat supply system that combines the high back pressure condenser of the air-cooling unit with the heat pump to recover the exhaust steam of the steam turbine for heat supply, which changes the existing heat pump recovery exhaust steam heat supply and the high back pressure condenser recovery exhaust steam supply. The utility model has the beneficial effect of increasing the heating system of the heating network water to three-stage heating, reducing the temperature gradient difference of the heating network water during the heating process, thereby reducing Fire damage. The system of the utility model can be constructed in stages, the initial investment is relatively small, and the heat supply can be adjusted flexibly. It is suitable for direct air-cooling units in thermal power plants, especially suitable for direct air-cooling units of 300,000 or less.

Description

Cascade heating heating system that makes full use of waste heat in power plants

technical field

The invention relates to a thermal power plant direct air-cooling unit high back pressure combined with heat pump heat supply system, which is a heat supply system that combines the high back pressure condenser of the air-cooling unit with the heat pump to recover exhaust steam from the steam turbine.

Background technique

The traditional heating method of cogeneration heating units is to use steam extraction for heating. Under the guidance of energy conservation and emission reduction policies, in recent years, more and more projects have used waste heat utilization equipment such as heat pumps and condensers to extract exhaust steam at the tail of steam turbines for heating. There are four commonly used heating methods at present: the first is steam extraction for heating, which uses steam turbines for heating and extracting steam, and heats the circulating water of the heating network through a steam-water heat exchanger, that is, a heating network heater. The characteristic is that the investment is small, but the exhaust steam of the steam turbine cannot be used. The second is heat pump heating, which is to extract the exhaust steam of the steam turbine for heating by setting up an absorption or compression heat pump, and the insufficient heat is supplemented by a heat network heater. The characteristic is that a part of exhaust steam can be utilized, but the utilization rate of exhaust steam is not high, accounting for about 30%-40%. The third is the pre-condenser heat pump for heat supply. Since the air-cooled unit operates at a back pressure of 12-15KPa, installing a condenser in front of the heat pump can take advantage of the low temperature of the return water in the early and late cold periods to absorb a large amount of exhaust steam from the turbine. The heating network water heated by the pre-condenser enters the heat pump to continue heating. When the heat is insufficient, the heating network heater is used to heat the heating network water. The feature is that it can use a large amount of exhaust steam in the early and late cold periods, and the utilization rate of waste heat is about 45%-55%. The fourth is the high back pressure heating of the unit, which is to increase the back pressure of an air-cooled unit to more than 25KPa, and heat the hot network water by setting a large-capacity condenser, and heat the insufficient part by the hot network heater. The waste heat utilization rate of this type is about 55%-65%, and the investment is less. The disadvantage is that the adjustment is not flexible, the heating area needs to be large enough, and the design water supply temperature should not be too high, otherwise the proportion of waste heat will be reduced.

Contents of the invention

The invention provides a cascaded heating and heat supply system that fully utilizes the waste heat of the power plant, and solves the technical problems of low utilization rate of waste heat of the power plant and inflexible adjustment of the heating temperature existing in the prior art.

The present invention solves the above technical problems through the following technical solutions:

A cascaded heating system that makes full use of the waste heat of a power plant, including the steam turbine of the first unit, the steam exhaust device of the first unit, the steam turbine of the second unit and the exhaust device of the second unit, and the exhaust device of the first unit is directly air-cooled by the first unit The exhaust pipe is connected with the air-cooled radiator of the first unit, and the air-cooled radiator of the first unit is connected with the hot well on the exhaust device of the first unit through the direct air-cooled condensate pipeline of the first unit, and the exhaust device of the second unit is passed through The direct air-cooled exhaust pipeline of the second unit is connected with the air-cooled radiator of the second unit, and the air-cooled radiator of the second unit is connected with the hot well on the exhaust device of the second unit through the direct air-cooled exhaust steam condensate pipeline of the second unit; The exhaust steam port of the condenser is connected with the direct air-cooling exhaust pipeline of the first unit through the exhaust steam pipe of the first unit, and the exhaust steam condensate port of the heat network condenser is connected with the exhaust steam condensate pipe of the heat network condenser of the first unit It is directly connected with the air-cooled exhaust steam condensate pipeline of the first unit, the return water pipeline of the urban heating network is connected with the water inlet of the heating network condenser through the water inlet pipe of the heating network condenser, and one end of the outlet pipe of the heating network condenser is connected with the heat The water outlet of the network condenser is connected, and the other end of the water outlet pipe of the heat network condenser is connected with the heat network water inlet of the heat pump. The air-cooled exhaust steam condensate pipeline is connected, the exhaust steam port of the heat pump is connected with the direct air-cooling exhaust pipeline of the second unit through the exhaust steam pipeline of the second unit, and the driving steam port of the heat pump is connected with the exhaust pipe of the second unit steam turbine The steam port is connected, and the heat network outlet of the heat pump is connected with the heat network water inlet on the heat network heater through the heat pump outlet pipe. The water outlet pipe of the heat network heater is connected with the urban heat network water supply pipe, the heating steam port on the heat network heater is connected with the steam extraction port of the second unit steam turbine through the steam pipe of the second unit, and the heating steam port on the heat network heater is passed through The steam pipe of the first unit is connected with the steam extraction port of the steam turbine of the first unit, and the heating steam drain on the heat network heater is connected with the low-pressure condensate pipe of the steam turbine of the first unit through the steam drain pipe of the first unit, and the steam drain on the heat network heater The heating steam drain port of the second unit communicates with the low-pressure condensate water pipeline of the steam turbine of the second unit through the steam drain pipe of the second unit.

The invention has the beneficial effects of increasing the heating system of the heating network water to three stages of heating, reducing the temperature gradient difference of the heating network water during the heating process, thereby reducing the exergy loss. The system of the invention can be constructed in stages, the initial investment is relatively small, and the heat supply can be adjusted flexibly. This system is suitable for direct air-cooling units in thermal power plants, especially for direct air-cooling units of 300,000 or less.

Description of drawings

Fig. 1 is a schematic structural view of the present invention.

Detailed ways

The present invention is described in detail below in conjunction with accompanying drawing:

A cascaded heating heating system that makes full use of the waste heat of a power plant, including a first unit steam turbine 1, a first unit exhaust device 2, a second unit steam turbine 6, and a second unit exhaust device 7, and the first unit exhaust device 2 passes through The direct air-cooled exhaust pipeline 4 of the first unit communicates with the air-cooled radiator 3 of the first unit, and the air-cooled radiator 3 of the first unit communicates with the heat on the exhaust device 2 of the first unit through the direct air-cooled exhaust steam condensate pipeline 5 of the first unit. The well is connected, the exhaust device 7 of the second unit communicates with the air-cooled radiator 8 of the second unit through the direct air-cooled exhaust pipeline 9 of the second unit, and the air-cooled radiator 8 of the second unit passes through the direct air-cooled exhaust steam condensate pipeline 10 of the second unit It communicates with the hot well on the exhaust device 7 of the second unit, and the exhaust steam port of the heat network condenser 11 communicates with the direct air-cooling exhaust pipeline 4 of the first unit through the exhaust steam pipeline 12 of the first unit, and the heat network condenser The exhaust steam condensate outlet of 11 is connected with the exhaust steam condensate pipeline 5 of the first unit direct air-cooled exhaust steam condensate pipeline 5 through the exhaust steam condensate pipeline 13 of the heat network condenser of the first unit, and the urban heating network return water pipeline 14 enters water through the heat network condenser Pipeline 16 is communicated with the water inlet of heat network condenser 11, and one end of heat network condenser water outlet pipe 15 is communicated with the water outlet of heat network condenser 11, and the other end of heat network condenser water outlet pipe 15 is connected with heat pump 17 The water inlet of the heating network is connected, the exhaust steam condensate outlet of the heat pump 17 is connected with the direct air-cooled exhaust steam condensate pipeline 10 of the second unit through the second unit heat pump exhaust steam condensate pipeline 18, and the exhaust steam outlet of the heat pump 17 is connected through the second unit The exhaust steam pipeline 19 communicates with the direct air-cooling exhaust pipeline 9 of the second unit, the drive steam port of the heat pump 17 communicates with the steam extraction port of the steam turbine 6 of the second unit through the steam pipeline 20 of the second unit, and the heat network outlet of the heat pump 17 passes through the heat pump The water outlet pipeline 21 communicates with the hot network water inlet on the heat network heater 23, and the heat network circulation pump 28 is arranged on the heat pump outlet pipeline 21, and the heat network water outlet on the heat network heater 23 passes through the heat network heater outlet pipe 24 communicates with the urban heating network water supply pipeline 25, the heating steam port on the heating network heater 23 communicates with the steam extraction port of the second unit steam turbine 6 through the steam pipeline 20 of the second unit, and the heating steam port on the heating network heater 23 passes through The steam pipe 26 of the first unit is communicated with the steam extraction port of the steam turbine 1 of the first unit, and the steam drain outlet of the heating network heater 23 is communicated with the low-pressure condensate pipe of the steam turbine of the first unit through the steam drain pipe 28 of the first unit. The heating steam drain port on the network heater 23 communicates with the low-pressure condensed water pipeline of the steam turbine of the second unit through the steam drain pipe 27 of the second unit.

The heating system of the present invention is designed according to the three-level gradient heating of the heating network water, and the operating parameter of the water in the urban heating network return water pipeline 14 in the conventional heating network is T ₁₄ =50°C; in the direct air cooling unit On the premise that the main engine is not modified, the temperature of water in the outlet pipe (15) of the heat network condenser is T ₁₅ =70°C; considering the performance of the heat pump itself, the heat pump characteristic system cop=1.8, and the temperature of water in the outlet pipe 21 of the heat pump is T ₂₁ = 85°C; according to the actual requirements of the water supply temperature of the heating pipe network, the water temperature T ₂₅ in the water supply pipe 25 of the urban heating network =110°C-90°C;

According to the comprehensive calculation, the waste heat utilization load factor x _yr of this heating system is between 44% and 66%, that is to say, the proportion of exhaust steam and waste heat in the whole heating season is as high as 65% to 85%;

Calculation formula for waste heat utilization load factor of heating system:

x _yr = ;

In the formula: T ₁₄ - temperature of return water of heating network (that is, water entering the condenser of heating network) (°C);

T ₁₅ —Temperature of the outlet water of the heat network condenser (°C);

T ₂₁ ——heat pump outlet water temperature (°C);

T ₂₅ ——heating network water supply (that is, heating network heater outlet water) temperature (°C);

cop——heat pump characteristic coefficient, constant;

G——Water flow of heating network (t/h);

Q - heating load (KW);

Q _yr - waste heat load (KW);

c——the specific heat coefficient of water [kj/(℃·kg)];

x _yr - load coefficient of waste heat utilization of heating system;

formula: Recovery of waste heat load for heat network condenser, Recovery of waste heat loads for heat pumps, is the total heating load. (Heating network condenser waste heat recovery load + heat pump recovery waste heat load) / total heating load × 100 = waste heat utilization load factor;

The formula is simplified: x _yr = .

Claims (1)

1. one kind makes full use of the step heating heating system of residual heat of electric power plant, comprise the first power generator turbine (1), first unit steam exhaust device (2), second power generator turbine (6) and the second unit steam exhaust device (7), first unit steam exhaust device (2) is communicated with the first unit air cooling heat radiator (3) by the first unit Direct Air-Cooled exhaust line (4), first unit air cooling heat radiator (3) is communicated with the hot well on the first unit steam exhaust device (2) by the first unit Direct Air-Cooled exhaust steam condensate line (5), second unit steam exhaust device (7) is communicated with the second unit air cooling heat radiator (8) by the second unit Direct Air-Cooled exhaust line (9), second unit air cooling heat radiator (8) is communicated with the hot well on the second unit steam exhaust device (7) by the second unit Direct Air-Cooled exhaust steam condensate line (10), it is characterized in that, the exhaust port of heat supply network condenser (11) is communicated with the first unit Direct Air-Cooled exhaust line (4) by the first unit exhaust steam pipeline (12), the exhaust steam condensation mouth of a river of heat supply network condenser (11) is communicated with the first unit Direct Air-Cooled exhaust steam condensate line (5) by the first unit heat supply network condenser exhaust steam condensing water conduit (13), municipal heating systems water return pipeline (14) is communicated with by the water inlet of heat supply network condenser inlet channel (16) with heat supply network condenser (11), one end of heat supply network condenser outlet conduit (15) is communicated with the delivery port of heat supply network condenser (11), the other end of heat supply network condenser outlet conduit (15) is communicated with the hot net water water inlet of heat pump (17), the exhaust steam condensation mouth of a river of heat pump (17) is communicated with the second unit Direct Air-Cooled exhaust steam condensate line (10) by the second unit heat pump exhaust steam condensing water conduit (18), the exhaust port of heat pump (17) is communicated with the second unit Direct Air-Cooled exhaust line (9) by the second unit exhaust steam pipeline (19), the driving steam port of heat pump (17) is communicated with the extraction opening of the second power generator turbine (6) by the second unit jet chimney (20), the heat supply network mouth of a river of heat pump (17) is communicated with the hot net water water inlet on heat exchangers for district heating (23) by heat pump outlet conduit (21), heat pump outlet conduit (21) is provided with pumps for hot water supply net (28), heat supply network delivery port on heat exchangers for district heating (23) is communicated with municipal heating systems water supply line (25) by heat exchangers for district heating outlet conduit (24), heating steam mouth on heat exchangers for district heating (23) is communicated with the extraction opening of the second power generator turbine (6) by the second unit jet chimney (20), heating steam mouth on heat exchangers for district heating (23) is communicated with the extraction opening of the first power generator turbine (1) by the first unit jet chimney (26), heating steam drain port on heat exchangers for district heating (23) is by the low pressure condensate water pipeline communication of the first unit steam drainage pipeline (28) with the first power generator turbine, heating steam drain port on heat exchangers for district heating (23) is by the low pressure condensate water pipeline communication of the second unit steam drainage pipeline (27) with the second power generator turbine.