JPH06257413A - Gas turbine-steam turbine composite plant - Google Patents

Abstract

(57) [Abstract] [Purpose] To cool the blades of a gas turbine, etc., the compressed air partially extracted from the air compressor of the gas turbine is cooled by cooling water and supplied to the gas turbine. The exhaust heat associated with is recovered to reduce heat loss. [Structure] Compressed air partially extracted from an air compressor 1 is cooled by heat exchange with cooling water from a deaerator 23 in a cooling air cooler 6 and pressure of cooling water discharged from the cooling air cooler 6. Is reduced by the pressure control valve 38 so that the pressure in the evaporator 35 becomes equal to or lower than the saturation pressure corresponding to the temperature of the cooling water discharged from the cooling air cooler 6 and higher than the pressure in the deaerator 23. The cooling water is controlled to boil the cooling water in the evaporator 35, and the generated steam is supplied to the deaerator 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention drives a gas turbine to generate power, heats feed water in a boiler with exhaust gas from the gas turbine to generate steam, and drives the steam turbine with this steam. The present invention relates to a gas turbine / steam turbine combined power generation plant for generating power, and more particularly to a gas turbine / steam turbine combined power generation plant for converting the power of the gas turbine and the steam turbine into electric power by a generator.

[0002]

2. Description of the Related Art As a gas turbine / steam turbine combined plant in which a gas turbine and a steam turbine are combined, a gas turbine is driven by combustion gas generated by burning fuel in a combustor with compressed air compressed by an air compressor. The generated power is converted into electric power by a generator, and the feed water supplied to the boiler is heated by the exhaust gas of the gas turbine to generate steam, and the steam is used to drive the steam turbine to generate power. As a gas turbine / steam turbine combined cycle power plant that is converted into electric power by a machine, the system shown in FIG. 3 is known.

In FIG. 3, an air compressor 1 and a gas turbine 2 coaxial with the air compressor 1 are axially coupled to a generator 3. The combustor 4 combusts the fuel supplied thereto by the compressed air from the air compressor 1, and the combustion gas thereof is supplied to the gas turbine 2. The cooling air cooler 6 is provided in the cooling air supply system 7 connected to the middle stage of the air compressor 1 and the gas turbine 2, and cools the compressed air extracted from the middle stage of the air compressor 1. The radiator 8 is provided in the cooling water circulation system 9 passing through the cooling air cooler 6 and cools the compressed air extracted from the air compressor 1 and then cools the cooling water discharged from the cooling air cooler 6. Equipped with 10. A cooling tower equipped with a cooling fan may be used instead of the radiator 8.

The boiler 11 is connected to the exhaust port of the gas turbine 2 via an exhaust gas supply system 12 and is supplied with exhaust gas from the gas turbine 2. The steam turbine 15 is a condenser 16
And is axially coupled to the generator 17. The steam turbine 15 is connected to the boiler 11 via a steam supply system 18. The feed water heating system 20 is a condensate pump 21, a deaerator 23 connected to a degassing extraction system 22 for supplying extraction air from the steam turbine 15, a high pressure feed water heating connected to a high pressure extraction system 24 and a low pressure extraction system 26, respectively. Vessel 25, low-pressure feed water heater 2
7 and the water supply pump 28, and the condenser 16 and the boiler 1
It is provided by connecting with 1. In addition, 30 is a drain discharge system for guiding the drain of the high-pressure feed water heater 25 to the deaerator 23,
Reference numeral 31 is a drain discharge system for guiding the drain of the low-pressure feed water heater 27 to the condenser 16.

With such a structure, the compressed air compressed by the air compressor 1 is supplied to the combustor 4, the fuel is combusted by the compressed air in the combustor 4, and the combustion gas generated by this combustion is the gas turbine. 2, the gas turbine 2 is driven to generate electric power by a generator 3 which is axially coupled.
At this time, the compressed air extracted from the middle stage of the air compressor 1 is cooled by the cooling water flowing through the cooling air cooler 6 provided in the cooling air supply system 7 and supplied to the gas turbine 2, where it is burned by the combustion gas. The blades of the driven gas turbine 2 and the gas flow path are cooled.

The cooling water flowing through the cooling air cooler 6 circulates through a cooling water circulation system 9 and the heated cooling water discharged by cooling the compressed air in the cooling air cooler 6 is discharged to a radiator 8. The cooling air is cooled by driving the fan 10 and supplied again to the cooling air cooler 6. Exhaust gas discharged by driving the gas turbine 2 is supplied to the boiler 11 to heat the feed water from the condenser 16 through the feed water heating system 20 to generate steam.
The generated steam is supplied to the steam turbine 15 via the steam supply system 18 to drive the steam turbine 15. The exhaust gas discharged from the steam turbine 15 is cooled and condensed by the cooling water in the condenser 16 to be condensed water, and the inside of the condenser 16 is maintained at a pressure equal to or lower than the atmospheric pressure. Note that this condensate serves as water for the boiler 11.

Condensed water from the condenser 16, that is, feed water is supplied to the low-pressure feed water heater 27 by the condensate pump 21 and heated by the extraction air supplied from the steam turbine 15 through the low-pressure extraction system 26 to raise the temperature. . The heated supply water is supplied to the deaerator 23, and is heated and deaerated by the extracted air supplied from the steam turbine 15 through the deaeration extraction system 22 and stored in the deaerator 23.

The degassed feed water in the deaerator 23 is supplied to the high-pressure feed water heater 25 by the feed water pump 28, heated and heated by the bleed air supplied from the steam turbine 15 through the high-pressure bleed system 24, and then heated by the boiler. 11 is supplied. Boiler 1
The feed water supplied to No. 1 is converted into steam and supplied to the steam turbine 15 as described above, and drives the steam turbine 15 to generate electric power by the generator 17.

The drain generated in the high-pressure feed water heater 25 passes through the drain discharge pipe 30 to the deaerator 23, and the drain generated in the low-pressure feed water heater 27 passes through the drain discharge system 31 to the condenser 16 Is supplied to.

[0010]

The compressed air extracted from the middle stage of the air compressor 1 for cooling the blades and gas passages of the gas turbine 2 is cooled by the cooling air cooler 6 in the cooling water circulation system 9.
Is supplied to the gas turbine 2 by being circulated through cooling water, and the cooling water whose temperature has been raised by cooling the compressed air by the cooling air cooler 6 is cooled by the radiator 8 and a cooling tower (not shown). At this time, there is a drawback in that the heat of cooling the compressed air extracted from the air compressor 1 is not recovered but is released to the atmosphere by being cooled by the radiator of the cooling water flowing through the cooling water circulation system 9 or the cooling tower.

Further, since a radiator or a cooling tower is used to cool the cooling water circulating in the cooling water circulation system 9, there is a drawback that noise of a cooling fan is generated and environmental pollution occurs. An object of the present invention is to provide a gas turbine / steam turbine combined plant capable of recovering exhaust heat accompanying cooling of compressed air for cooling a gas turbine and preventing generation of noise.

[0012]

In order to solve the above-mentioned problems, according to the present invention, a gas turbine driven by combustion gas produced by burning fuel with compressed air from an air compressor in a combustor and , A boiler that heats the feed water by the exhaust gas from this gas turbine to turn it into steam, a steam turbine that is driven by the steam from this boiler, and a deaeration that heats the feed water by extraction from the steam turbine and supplies it to the boiler In a gas turbine / steam turbine combined plant including a feed water heating system including a water heater and a feed water heater, and a cooling air cooler that cools compressed air extracted from the middle stage of the air compressor and sends the cooled air to the inside of a gas turbine. , A cooling water circulation system equipped with a circulation pump for returning the water supplied from the deaerator as cooling water to the deaerator via the cooling air cooler, and the cooling water circulation system And an evaporator for evaporating the cooling water discharged from the cooling air cooler and a cooling water circulation system on the cooling water inlet side of the evaporator, and the pressure in the evaporator is adjusted to the temperature of the discharged cooling water. Lower than the corresponding saturation pressure,
And a pressure control valve for controlling the pressure in the deaerator or a predetermined pressure higher than the pressure in the feed water heater, the pressure control means by this pressure control valve, and the vapor in the evaporator to the deaerator or the feed water heater. A steam supply system for supply shall be provided.

Further, in the gas turbine / steam turbine combined plant comprising the above gas turbine, boiler, steam turbine, feed water heating system and cooling air cooler, an evaporator for evaporating the cooling water discharged from the cooling air cooler, ,
The cooling water circulation system is equipped with a circulation pump that returns the cooling water in the evaporator to the evaporator via the cooling air cooler, and the cooling water circulation system on the cooling water inlet side of the evaporator is provided to control the pressure in the evaporator. A pressure control valve for controlling to a predetermined pressure lower than the saturation pressure corresponding to the temperature of the discharged cooling water and higher than the pressure in the deaerator or the pressure in the feed water heater, and pressure control means by this pressure control valve. And a water supply system that branches from the water supply heating system to supply the water supply to the evaporator, and a steam supply system that supplies the steam generated in the evaporator to the deaerator or the water supply heater.

In the above description, the pressure control means controls the pressure control valve based on the pressure detector for detecting the pressure in the evaporator and the deviation between the pressure detected by the pressure detector and the target value of the predetermined pressure. And control means.

[0015]

In order to cool the inside of the gas turbine, the compressed air extracted from the middle stage of the air compressor is cooled by the cooling air cooler. The cooling of the compressed air in the cooling air cooler is performed by the feed water in the deaerator, which is boosted by the circulation pump of the cooling water circulation system and is supplied to the cooling air cooler, that is, the cooling water. The discharged cooling water is returned to the deaerator through the evaporator. At this time, the pressure of the cooling water discharged from the cooling air cooler is reduced by the pressure control valve, so that the pressure inside the evaporator is lower than the saturation pressure corresponding to the temperature of the discharged cooling water, and the inside of the deaerator is reduced. Or a predetermined pressure higher than the pressure in the feed water heater. Therefore, since the cooling water in the evaporator has a pressure equal to or lower than the saturation pressure corresponding to the temperature and boils to generate steam, this steam is supplied to the deaerator or the feed water heater via the steam supply system. As a result, the exhaust heat accompanying the cooling of the compressed air extracted from the middle stage of the air compressor is recovered, and the plant efficiency is improved.

Further, the cooling of the compressed air extracted from the middle stage of the air compressor for cooling the inside of the gas turbine by the means different from the above by the cooling air cooler is returned to the evaporator via the cooling air cooler. The cooling water in the evaporator, which circulates in the cooling water circulation system, is pressurized by a circulation pump and supplied to the cooling air cooler. At this time, the pressure of the cooling water discharged from the cooling air cooler is reduced by the pressure control valve, and the pressure inside the evaporator is controlled to the aforementioned predetermined pressure and supplied to the evaporator. Therefore, since the cooling water in the evaporator boils to generate steam, this steam is supplied to the deaerator or the feed water heater of the feed water heating system via the steam supply system. The water supply that is consumed by supplying steam from the evaporator to the deaerator or the feed water heater is replenished by the feed water supplied from the feed water supply system branched from the feed water heating system.

By doing so, the exhaust heat due to the cooling of the compressed air extracted from the middle stage of the air compressor is recovered, and the plant efficiency is improved. The pressure control in the evaporator controls the pressure control valve by the control means from the deviation between the detected pressure detected by the pressure detector provided in the evaporator and the target value of the predetermined pressure. The pressure inside the evaporator is controlled to a predetermined pressure.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a gas turbine according to an embodiment of the present invention.
It is a system diagram of a combined cycle power generation plant as a steam turbine combined plant. In FIG. 1 and FIG. 2 described later, the same parts as those of the conventional example of FIG. 1 is different from the conventional example of FIG. 3 in the following points.

A cooling water inlet system 37 provided with an evaporator 35 for evaporating the cooling water discharged from the cooling air cooler 6 and connected to the deaerator 23 and the inlet of the cooling air cooler 6 and having a circulation pump 36. And the outlet of the cooling air cooler 6 and the evaporator 3
5, a cooling water outlet system 39 including a pressure control valve 38, and a cooling water return system 40 connected to the evaporator 35 and the deaerator 23.
The supply water stored in 3, that is, the cooling water is the deaerator 23 →
A cooling water circulation system 41 that circulates the cooling air cooler 6-> evaporator 35-> deaerator 23 is provided.

Further, a vapor supply system 42 is provided which is connected to the evaporator 35 and the deaerator 23 and supplies the vapor generated in the evaporator 35 to the deaerator 23. Reference numeral 43 is a check valve.
The evaporator 35 is provided with a pressure detector 45 for detecting the pressure inside the evaporator 35, and the pressure is below the saturation pressure corresponding to the pressure detected by the pressure detector 45 and the temperature of the cooling water discharged from the cooling air cooler 6. And the regulator 4 for controlling the pressure control valve 38 from the deviation from the target value of the predetermined pressure higher than the pressure in the deaerator 23.
6 is provided.

With such a configuration, the feed water in the deaerator 23, that is, the cooling water is pressurized by the circulation pump 36 and supplied to the cooling air cooler 6 via the cooling water inlet system 37. Here, the pressure of the cooling water boosted by the circulation pump 36 is set to a pressure at which the boosted cooling water does not cause boiling due to heat exchange in the cooling air cooler 6. The cooling water supplied to the cooling air cooler 6 becomes the cooling water that has been heated by cooling the compressed air extracted from the middle stage of the air compressor 1 as described above and flows through the cooling water outlet system 39 to control the pressure. The pressure is reduced by the valve 38 and flows into the evaporator 35. At this time, the pressure in the evaporator 35 detected by the pressure detector 45 is lower than the saturation pressure corresponding to the temperature of the cooling water discharged from the cooling air cooler 6 and the pressure in the deaerator 23. The pressure in the evaporator 35 is controlled to a predetermined pressure by controlling the pressure control valve 38 by the controller 46 based on the deviation from the target value of the higher predetermined pressure.

Therefore, the cooling water in the evaporator 35 boils due to the pressure in the evaporator 35 to generate steam.
Here, the cooling water in the evaporator 35 is returned to the deaerator 23 via the cooling water return system 40. In this way, the cooling water in the deaerator 23 passes through the cooling air cooler 6 and the evaporator 35, and then the deaerator 2
It returns to 3 and circulates through the cooling water circulation system 41. On the other hand, the steam in the evaporator 35 is supplied to the deaerator 23 via the steam supply system 42.

As described above, the cooling water supplied from the deaerator 23 and discharged from the cooling air cooler 6 is evaporated by the evaporator 35, and the vapor is supplied to the deaerator 23, whereby the deaerator 23 is discharged. Since the feed water inside is heated together with the extracted air that passes through the deaerating extraction system 22, it is possible to recover the amount of heat exchanged as exhaust heat in the cooling air cooler 6 during normal operation of the gas turbine / steam turbine combined cycle power plant.

When the gas turbine / steam turbine combined cycle power plant is started, the feed water in the deaerator 23 can be preheated by the steam from the evaporator 35, so that the heat loss at the start can be reduced. In this embodiment, the vapor generated in the evaporator 35 is supplied to the deaerator 23, but the pressure inside the evaporator 35 is lower than the saturation pressure and the pressure inside the high or low pressure feed water heater 25, 27. By controlling to a higher predetermined pressure and supplying the steam generated in the evaporator 35 to the high-pressure or low-pressure feed water heaters 25 and 27 instead of the deaerator 23, the same effect as described above can be obtained.

FIG. 2 is a system diagram of a combined gas turbine / steam turbine power plant according to another embodiment of the present invention. In FIG. 2, the cooling water circulation system 41 of FIG. 1 is removed, and the cooling water inlet system 48 including the circulation pump 36 is connected to the lower portion of the evaporator 35 and the cooling water inlet of the cooling air cooling device 6, and the cooling air cooling device. 6, a cooling water circulation system 50 including a cooling water outlet 6 and a cooling water outlet system 49 connected to the evaporator 35 and provided with a pressure control valve 38, and a low-pressure feed water heater 2 of the feed water heating system 20.
7 is the same as FIG. 1 except that it is branched from the downstream side of 7 and connected to the evaporator 35, and a water supply system 52 having a water supply pump 51 is provided.

With such a configuration, the cooling water in the evaporator 35 is boosted by the circulation pump 36 to a pressure at which it does not boil due to heat exchange in the cooling air cooler 6, and the cooling air cooler 6 is cooled.
Is supplied to. The supplied cooling water is the air compressor 1
The cooling water that cools the compressed air extracted from the middle stage, raises the temperature, and is discharged is the pressure control valve 3 by the pressure control means described above.
The pressure is controlled to the above-mentioned predetermined pressure by 8 and boils in the evaporator 35 to generate steam. Here, the cooling water in the evaporator 35 is again supplied to the cooling air cooler 6, while the steam is supplied to the deaerator 23.

The feed water consumed by the cooling water generated by the supply of the steam to the deaerator 23 is the feed water supply system 5.
The water is supplied via the water supply heating system 20 via the water supply pump 51 via the water supply system 2. The vapor generated in the evaporator 35 may be supplied to the high-pressure feed water heater 25 or the low-pressure feed water heater 27 as described above, instead of the deaerator 23.

By supplying the vapor generated in the evaporator 35 to the deaerator 23, the high pressure feed water heater 25 or the low pressure feed water heater 27, the same effect as described above can be obtained.

[0029]

As is apparent from the above description, according to the present invention, with the above-described structure, the compressed air extracted from the middle stage of the air compressor is cooled by the cooling air cooler to evaporate the heat-exchanged cooling water. Since the steam generated by boiling by controlling the pressure in the vessel is supplied to the deaerator or the feed water heater to heat the feed water together with the extraction air from the steam turbine, it is possible to recover the exhaust heat accompanying the cooling of the compressed air, Plant efficiency is improved. Further, since the feed water flowing through the deaerator and feed water heater can be preheated at the time of starting the gas turbine / steam turbine combined plant, starting loss can be reduced.

Since no radiator or cooling tower is used unlike the conventional case, no noise is generated.

[Brief description of drawings]

FIG. 1 is a system diagram of a gas turbine / steam turbine combined power generation plant according to an embodiment of the present invention.

FIG. 2 is a system diagram of a gas turbine / steam turbine combined power generation plant according to a different embodiment of the present invention.

[Fig. 3] System diagram of a conventional gas turbine / steam turbine combined cycle power plant

[Explanation of symbols]

 1 Air Compressor 2 Gas Turbine 6 Cooling Air Cooler 11 Boiler 15 Steam Turbine 16 Condenser 17 Generator 20 Water Supply Heating System 23 Deaerator 25 High Pressure Water Heater 27 Low Pressure Water Heater 35 Evaporator 36 Circulation Pump 38 Pressure Control valve 41 Cooling water circulation system 42 Steam supply system 45 Pressure detector 46 Regulator 50 Cooling water circulation system 52 Water supply system

Claims (3)

[Claims] 1. A gas turbine driven by a combustion gas produced by combusting fuel with compressed air from an air compressor in a combustor, and a boiler for heating feed water to steam by exhaust gas from the gas turbine. And a steam turbine driven by steam from the boiler, a feed water heating system including a deaerator and a feed water heater that heat feed water by bleed air from the steam turbine to supply the boiler, and the air compressor. In a gas turbine / steam turbine combined plant equipped with a cooling air cooler that cools the compressed air extracted from the middle stage and sends it out to the inside of the gas turbine, feed water from the deaerator is used as cooling water via the cooling air cooler. Cooling water circulation system equipped with a circulation pump for returning to the deaerator and steam for evaporating the cooling water discharged from the cooling air cooler provided in this cooling water circulation system. And a cooling water circulation system on the cooling water inlet side of the evaporator, the pressure inside the evaporator is lower than the saturation pressure corresponding to the temperature of the discharged cooling water, and the pressure inside the deaerator or the water supply. A pressure control valve for controlling a predetermined pressure higher than the pressure in the heater, a pressure control means by this pressure control valve, and a steam supply system for supplying the steam generated in the evaporator to the deaerator or the feed water heater A gas turbine / steam turbine combined plant characterized by 2. A gas turbine driven by combustion gas produced by combusting fuel with compressed air from an air compressor in a combustor, and a boiler for heating feed water into steam by exhaust gas from the gas turbine. And a steam turbine driven by steam from the boiler, a feed water heating system including a deaerator and a feed water heater that heat feed water by bleed air from the steam turbine to supply the boiler, and the air compressor. In a gas turbine / steam turbine combined plant comprising a cooling air cooler for cooling the compressed air extracted from the middle stage and sending it to the inside of the gas turbine, an evaporator for evaporating the cooling water discharged from the cooling air cooler, , A cooling water circulation system having a circulation pump for returning the cooling water in the evaporator to the evaporator via a cooling air cooler, and cooling water at the cooling water inlet side of the evaporator A pressure provided in the ring system for controlling the pressure in the evaporator to a predetermined pressure lower than the saturation pressure corresponding to the temperature of the discharged cooling water and higher than the pressure in the deaerator or the pressure in the feed water heater. A control valve, a pressure control means by this pressure control valve, a feed water supply system that branches from the feed water heating system to supply the feed water to the evaporator, and the steam generated in the evaporator is supplied to the deaerator or the feed water heater. A gas turbine / steam turbine combined plant, comprising a steam supply system. 3. The pressure control means according to claim 1, wherein the pressure control means detects a pressure in the evaporator,
A gas turbine / steam turbine combined plant comprising: a control unit that controls a pressure control valve based on a deviation between a pressure detected by the pressure detector and a target value of the predetermined pressure.