JPH09112802A - Bed-ash cooling apparatus for pressurized fluid boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the plant efficiency of a pressurized fluid bed boiler by disposing an in-bed evaporator partially in a bed-ash storage hopper to cool the bed ash with high pressure feedwater. SOLUTION: A bed-ash cooling apparatus for a pressurized fluid bed boiler comprises a fluid bed boiler body 2 disposed in a pressure vessel 1 and having a diffuser pipe 3 and an in-bed evaporator 8 provided therein, and a bed-ash storage hopper 45 provided in the bottom of the fluid bed boiler body 2 for storing bed ash 6 and having a bed-ash discharge valve 43 through which the bed ash 6 stored therein is discharged to the underside thereof, thereby cooling the ash 6 in the bed-ash storage hopper 45. The bed-ash cooling apparatus further comprises an in-hopper evaporator 46 disposed within the bed-ash storage hopper 45 for introducing therein high pressure feedwater 40 which is heated by heat exchange with the ash 6 in the bed-ash storage hopper 45 and then feeding the heated high pressure feedwater 40 into the in-bed evaporator 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bed ash cooling device for a pressurized fluidized bed boiler for cooling the bed ash in a fluidized bed boiler body to the outside through a bed ash reservoir hopper. is there.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional pressurized fluidized bed boiler, in which a fluidized bed boiler main body 2 is placed in a pressure vessel 1 whose interior is under a pressurized atmosphere by the supply of pressurized air 1a. Is provided, and the air diffusing pipe 3 is arranged inside the lower portion of the fluidized bed boiler body 2.

Sand and the like are supplied to the upper part of the air diffuser 3, and further coal fuel 4 and desulfurization material 5 such as limestone are supplied,
It is agitated and efficiently burned by being fluidized by the pressurized air 1a which is taken into the air diffuser 3 from the air intake 3a and jetted upward, and at this time, combustion ash, limestone, and ash due to the combustion of the coal fuel 4 Bed ash mixed with sand 6
The in-bed evaporator 8 and the reheater 9 installed in the fluidized bed 7 are heated by the fluidized bed 7 having a bed temperature of, for example, about 860 ° C.

The combustion exhaust gas 1b that has heated the in-layer evaporator 8 and the reheater 9 is dedusted by the cyclone 10, then goes out of the pressure vessel 1 and is further dedusted by the ceramic filter 11, and the high pressure gas turbine 12 is used. , And the low-pressure gas turbine 13, and then to the chimney 16 through the denitration device 14 and the exhaust gas cooler (coal saver) 15. In the figure, 10a indicates an ash cooler for cooling the ash that is collected and sucked and discharged to the outside by the pressurized air 1a.

The high pressure gas turbine 12 is coaxially provided with a high pressure compressor 17 and a gas turbine generator 18, and the low pressure gas turbine 13 is coaxially provided with a low pressure compressor 19. The air that has been sucked by and is primarily pressurized is cooled by the intercooler 20 and then secondarily pressurized by the high-pressure compressor 17 to become pressurized air 1a, which is supplied to the pressure vessel 1. There is.

A high-pressure steam turbine 21, an intermediate-pressure steam turbine 22, a low-pressure steam turbine 23, and a steam turbine generator 24 are coaxially arranged outside the pressure vessel 1, and the fluidized bed boiler is used. For example, the main steam 25 of 225 K and 596 ° C. from the in-layer evaporator 8 in the main body 2 is guided to the high-pressure steam turbine 21 to perform work, and then is guided to the reheater 9 to be reheated, for example, 46 K, It becomes the reheated steam 26 of 595 ° C. and is guided to the intermediate pressure steam turbine 22 for work, and then is guided to the low pressure steam turbine 23 to drive the steam turbine generator 24 and then to the condenser 27. Then, the water is cooled by the cooling water 29 circulated by the circulating water pump 28 to condense, and the condensate pump 30 forms the low pressure feed water 31 at 20 K and 34 ° C., for example, and the low pressure feed heater conduit 35a. Through is supplied to the low-pressure feed water heater 32, the is performed heated by low pressure steam turbine 23 low pressure bleed air 34 bled from the example 7K, 140 ° C.
The low-pressure feed water 31 ′ is introduced into the deaerator 36.

Further, a part of the low pressure feed water 31 from the condensate pump 30 is guided to the intercooler 20 via an intercooler conduit 35b, and the low pressure compressor 1 is introduced.
It is heated by the air that is primarily pressurized at 9
K, 140 ° C. low-pressure feed water 31 ′, low-pressure feed water 31 ′ from the intercooler conduit 35 b and low-pressure feed water 31 ′ from the low-pressure feed water heater conduit 35 a are both supplied to the deaerator 36, and the medium-pressure steam turbine The medium pressure bleed air 37 bleed from 22 is used for degassing.

The feed water degassed by the deaerator 36 is pressurized by the water feed pump 38, guided to the exhaust gas cooler 15 by the exhaust gas cooler conduit 39, and heated by the combustion exhaust gas 1b, for example, at 300 K and 320 ° C. The high-pressure feed water 40 is supplied to the in-layer evaporator 8 inside the fluidized-bed boiler body 2 via the inlet header 8a. The high-pressure feed water 40 supplied to the in-layer evaporator 8 becomes steam in the in-layer evaporator 8 and becomes the main steam 25 and is supplied to the high-pressure steam turbine 21.

Since the bed ash 6 generated by the combustion of the coal fuel 4 remains in the fluidized bed 7, the bed height of the fluidized bed 7 gradually increases due to the continued operation of the pressurized fluidized bed boiler. . Therefore, the increased amount of bed ash 6 needs to be discharged to the outside from the pressurized fluidized bed boiler.

In order to discharge the bed ash 6 from the pressurized fluidized bed boiler to the outside, a bed ash reservoir hopper 41 is formed at the bottom of the fluidized bed boiler main body 2 as shown in FIG. 2), a bed ash extraction valve 43 is provided at the lower end of the bed ash extraction pipe 42 connected to the bottom of the bed ash storage hopper 41, and an L valve or the like not shown is provided below the bed ash extraction valve 43. It is equipped with a bed ash discharge device.

The temperature of the bed ash 6 moving from the fluidized bed 7 having a bed temperature of about 860 ° C. into the bed ash reservoir hopper 41 is almost close to the bed temperature, and this hot bed ash 6 can be directly taken out to the bed ash discharging device. Since the bed ash extraction valve 43 and the like have no temperature, the bed ash extraction valve 43 and the like can be inexpensively implemented as a normal material such as carbon steel.
Cooling to 50 ° C or lower is required.

For this reason, conventionally, the bed ash 6 is cooled by supplying a cooling fluid such as cooling air or cooling water (not shown) of a system different from that of the pressurized fluidized bed boiler into the bed ash reservoir hopper 41. A bed ash cooler was made to do so.

However, as described above, when the cooling fluid of the system different from that of the pressurized fluidized bed boiler is supplied to cool the bed ash 6, the heat of the bed ash 6 is simply wasted. Therefore, there is a problem in the thermal efficiency of the pressurized fluidized bed boiler.

For this reason, in recent years, a low-pressure water supply bed ash cooler 44 using a heat transfer tube in the bed ash storage hopper 41 is used.
The low-pressure feed water ash cooler 44 is provided with a part of the low-pressure feed water 31 at the outlet of the condensate pump 30 and a cooler conduit 35.
c) and the inlet header 31a, and the low-pressure feed water ash cooler 44 heat-recovers the low-pressure feed water 31 '.
Through the outlet header 31b and the cooler conduit 35c,
It has been practiced to implement a device in which the other side of the low-pressure feed water 31 'is joined on the inlet side of the deaerator 36.

As described above, the bed ash 6 is cooled by supplying a part of the low pressure feed water 31 from the condensate pump 30 to the low pressure feed water bed ash cooler 44 provided in the bed ash reservoir hopper 41. Then, the temperature of the bed ash 6 taken out from the bed ash extraction pipe 42 is cooled to 350 ° C. or lower to protect the bed ash extraction valve 43 and the like from high temperature, and the temperature of the bed ash 6 is further cooled to about 150 ° C. The heat efficiency of the pressurized fluidized bed boiler is improved by collecting the heat of the bed ash 6.

[0016]

However, as shown in FIG. 2, a low-pressure feed water bed ash cooler 44 is arranged in the bed ash reservoir hopper 41, and the low-pressure feed water 3 from the condensate pump 30 is provided.
In the system in which the bed ash 6 is cooled by supplying a part of the ash 6, the bed ash 6 at about 860 ° C. in the bed ash storage hopper 41 is 350 ° C. to 150 ° C.
In order to cool to about ℃, it is necessary to supply a large amount of low pressure feed water 31 from the condensate pump 30 to the low pressure feed bed ash cooler 44 via the cooler conduit 35c. Low-pressure water supply 3
The flow rate of 1 decreases, and the supply amount of the low pressure extraction air 34 extracted from the low pressure steam turbine 23 to the low pressure feed water heater 32 decreases. Therefore, the amount of steam discharged from the low pressure steam turbine 23 to the condenser 27 is reduced. Increased, which caused condenser 2
Since the amount of heat to be discarded in the cooling water 29 increases due to No. 7, there is a problem that the plant efficiency of the entire pressurized fluidized bed boiler that constitutes the regeneration cycle decreases.

The present invention improves the plant efficiency of a pressurized fluidized bed boiler by installing a part of the in-bed evaporator in the bed ash storage hopper and cooling the bed ash by high-pressure feed water. It is an object of the present invention to provide a bed ash cooling device for a pressurized fluidized bed boiler.

[0018]

According to the present invention, a fluidized bed boiler main body having an air diffuser and an in-layer evaporator is arranged in a pressure vessel, and bed ash is placed at the bottom of the fluidized bed boiler main body. A bed ash of a pressurized fluidized bed boiler is provided with a bed ash reservoir hopper configured to take out the stored bed ash to a lower portion via a bed ash extraction valve to cool the bed ash in the ash reservoir hopper. A cooling device, which supplies high-pressure feed water into the bed ash storage hopper to exchange heat with the bed ash in the bed ash storage hopper for heating, and guides the high-pressure feed water after heating to the intra-layer evaporator. The present invention relates to a bed ash cooling device for a pressurized fluidized bed boiler, in which the evaporator in the hopper as described above is arranged.

Further, a low-pressure feed water bed ash cooler for supplying a part of the low-pressure feed water at the outlet of the condensate pump and exchanging heat is provided below the evaporator in the hopper arranged in the bed ash storage hopper. It is characterized by.

According to the present invention, an in-hopper evaporator that constitutes a part of the in-layer evaporator is installed in the bed ash-storing hopper, and high-pressure feed water is introduced to the in-hopper evaporator to inject the bed-ash-storing hopper. The bed ash inside is cooled, and the high-pressure feed water whose temperature and pressure are increased by the cooling is guided to the in-layer evaporator, so the heat of the bed ash in the bed ash reservoir hopper is effectively supplied by the high-pressure feed water. Steam can be generated immediately after recovery, and therefore, the coal fuel for the heat recovery can be saved, and the plant efficiency of the pressurized fluidized bed boiler can be improved.

Further, when a low pressure feed water bed ash cooler for supplying heat to a part of the low pressure feed water at the outlet of the condensate pump and exchanging heat is provided below the evaporator in the hopper installed in the bed ash storage hopper, The bed ash cooled by the evaporator in the hopper can be cooled to a lower predetermined temperature, and the bed ash is cooled by the evaporator in the hopper, and the flow rate of low-pressure feed water required to cool the bed ash is Since the amount is small, it is possible to secure the extraction amount of the low-pressure extraction air from the low-pressure steam turbine to the low-pressure feed water heater and maintain the plant efficiency of the pressurized fluidized bed boiler high.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of the present invention. The same components as those in FIG. 2 are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in FIG. 1, a bed ash-storing hopper 4 is formed in a lower portion of a fluidized bed boiler main body 2 so as to extend downward.
The bed ash extraction pipe 4 is provided with two bed ash collecting valves 43 at the bottom of the bed ash storage hopper 45.
2 are connected.

An in-hopper evaporator 46, which constitutes a part of the in-layer evaporator 8 provided in the fluidized bed boiler main body 2, is installed in the upper part of the inside of the bed ash storage hopper 45. . In the in-hopper evaporator 46, a lower inlet header 47 is connected to an exhaust gas cooler conduit 39 that guides the high-pressure feed water 40 to the exhaust gas cooler 15 after being heated, and an upper outlet header 48 is connected to the outlet header 48. , Is connected to the lower inlet header 8a of the intra-layer evaporator 8 via the connecting pipe 49.

A low pressure feed water bed ash cooler 44 using a heat transfer tube is provided below the evaporator 46 in the hopper in the bed ash reservoir hopper 45, as shown in FIG. 2, to cool the low pressure feed water bed ash. A part of the low-pressure feed water 31 from the condensate pump 30 is supplied to the cooler 44 through the cooler conduit 35c, and the low-pressure feed water 31 'recovered by the low-pressure feed water ash cooler 44 is used as the deaerator 36. It is arranged to join the other low-pressure feed water 31 'on the inlet side of the.

Next, the operation of the above-mentioned device will be described.

A bed ash reservoir hopper 45 formed at the bottom of the fluidized bed boiler main body 2 is provided with an in-hopper evaporator 46 which constitutes a part of the in-bed evaporator 8, and the in-hopper evaporator 46 is installed in the in-hopper evaporator 46. Guide the high-pressure water supply 40 to the bed ash storage hopper 4
Since the bed ash 6 in 5 is cooled and the high-pressure feed water 40 whose temperature and pressure are increased by the cooling is guided to the in-layer evaporator 8 through the communication pipe 49, the bed ash storage hopper 45 The heat of the bed ash 6 in the inside can be recovered and steam can be immediately generated.
It is possible to save the amount of the coal fuel 4 for which the heat recovery has been performed and to improve the plant efficiency of the entire pressurized fluidized bed boiler.

At this time, the temperature of the high-pressure feed water 40 supplied from the exhaust gas cooler 15 to the in-hopper evaporator 46 is 320.
Since the temperature is around ℃, it is 860 in the bed ash storage hopper 45.
Even if the temperature of the bed ash 6 having a temperature of about 0 ° C. is cooled by the evaporator 46 in the hopper, it is about 400 ° C. at the most.

Therefore, when a part of the low pressure feed water 31 at the outlet of the condensate pump 30 is supplied to the low pressure water supply bed ash cooler 44 installed below the evaporator 46 in the hopper to exchange heat, the temperature is 400 ° C. The bed ash 6 before and after can be cooled to around 150 ° C.

At this time, the low pressure water supply bed ash cooler 44 is used.
Then, since the bed ash 6 at around 400 ° C. may be cooled to around 150 ° C., the flow rate of the low-pressure feed water supplied to the low-pressure feed water bed ash cooler 44 may be small, and thus the condensate pump 3
Low-pressure water supply 3 supplied from 0 to low-pressure water supply heaters 32, 33
1 can secure a large flow rate, and therefore the low-pressure steam turbine 2
Since the flow rate of the low pressure extraction air 34 from 3 is sufficiently secured, the amount of steam discharged from the low pressure steam turbine 23 to the condenser 27 is reduced, and the amount of heat discarded to the cooling water 29 by the condenser 27 is reduced. The plant efficiency of the entire pressurized fluidized bed boiler constituting the regeneration cycle can be increased.

In the example shown in FIG. 1, the bed ash storage hopper 45 is provided with the in-hopper evaporator 46 and the low-pressure feed water bed ash cooler 44. It is also possible to provide a combination of a cooling system and a cooler for guiding a cooling fluid such as cooling air or cooling water of another system.

[0033]

According to the present invention, in the bed ash storage hopper,
An evaporator in the hopper that is configured to form a part of the in-layer evaporator is installed, high-pressure feed water is guided to the evaporator in the hopper to cool the bed ash in the bed ash reservoir hopper, and the temperature is controlled by the cooling. Since the high-pressure feed water whose pressure is increased is guided to the in-layer evaporator, the heat of the bed ash in the bed ash reservoir hopper can be effectively recovered by the high-pressure feed water to immediately generate steam. It is possible to save the coal fuel for the amount of heat recovered, and to improve the plant efficiency of the pressurized fluidized bed boiler.

If a low pressure feed water bed ash cooler is provided below the evaporator in the hopper installed in the bed ash storage hopper to heat-exchange by supplying a part of the low pressure feed water at the outlet of the condensate pump, The bed ash cooled by the evaporator in the hopper can be cooled to a lower predetermined temperature, and the bed ash is cooled by the evaporator in the hopper, and the flow rate of low-pressure feed water required to cool the bed ash is Since the amount is small, it is possible to secure the extraction amount of the low-pressure extraction air from the low-pressure steam turbine to the low-pressure feed water heater and maintain the plant efficiency of the pressurized fluidized bed boiler high.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is a system diagram showing an example of a conventional pressurized fluidized bed boiler.

[Explanation of symbols]

 1 pressure vessel 2 fluidized bed boiler main body 3 air diffuser 6 bed ash 8 in-layer evaporator 30 condensate pump 31 low pressure water supply 40 high pressure water supply 43 bed ash extraction valve 44 low pressure water supply bed ash cooler 45 bed ash storage hopper 46 evaporation in hopper vessel

Claims (2)

[Claims] 1. A fluidized bed boiler main body having an air diffuser and an in-layer evaporator inside is arranged in a pressure vessel, and bed ash is stored and stored at the bottom of the fluidized bed boiler main body. A bed ash cooling device for a pressurized fluidized bed boiler, which is provided with a bed ash storage hopper adapted to be taken out through an ash extraction valve to cool the bed ash in the ash storage hopper, wherein said bed A high-pressure feed water is supplied into the ash-storing hopper to heat the bed ash in the bed ash-storing hopper by heating, and a high-pressure feed water after heating is introduced into the in-layer evaporator. A bed ash cooling device for a pressurized fluidized bed boiler characterized by being arranged. 2. A low-pressure feed water bed ash cooler for supplying heat to a part of the low-pressure feed water at the outlet of the condensate pump and exchanging heat under the evaporator in the hopper arranged in the bed ash storage hopper. The bed ash cooling device for a pressurized fluidized bed boiler according to claim 1, wherein: