JP2007016791A - Combined power plant and closed air cooled gas turbine system - Google Patents

Abstract

An object of the present invention is to effectively recover the exhaust heat of a precooler in a plant to improve efficiency, and to maintain reliability in various operating modes of a closed air cooling gas turbine to improve reliability.
As a cooling medium for cooling a high temperature portion of a gas turbine, air discharged from a compressor 1 is cooled by a precooler 31 and pressurized by a boost compressor 32, and the cooled air is used as combustion air in a combustor. In a combined power plant including a closed air cooling gas turbine to be recovered, an exhaust heat recovery boiler 9 that generates steam from exhaust gas of the gas turbine, and a steam turbine that converts steam generated in the exhaust heat recovery boiler into power The precooler 31 of the air-cooled gas turbine includes a plurality of heat exchangers each having a different temperature of the cooling medium, and the precooler upstream heat exchanger is supplied with a high-temperature refrigerant and recovered at a high-temperature location. Formed as follows.
[Selection] Figure 1

Description

  The present invention relates to a combined power plant and a closed air cooled gas turbine system.

  The air discharged from the compressor is pressurized by the boost compressor, the high-temperature portion of the gas turbine is cooled by the pressurized air, and the cooled air is recovered as combustion air without being released into the turbine gas path. The configuration of the cooling gas turbine is described in, for example, JP-A-54-82518.

Also, the compressor discharge air is cooled by a precooler, the cooled air is boosted by a boost compressor, the gas turbine high temperature part is cooled by the boosted air, and the cooled air is burned without being released into the turbine gas path. For example, the ASME Joint International Power Generation Conf
erence 94-JPGC-GT-8).

JP-A-54-82518 The ASME Joint International Power Generation Conference 94-JPGC-GT-8

  In the closed-air cooled gas turbine system formed in this way, the air after cooling the high-temperature part of the gas turbine is not released into the turbine gas path. There is no loss, and pumping power due to centrifugal force can be recovered, so a significant improvement in plant efficiency is expected.

  However, in a closed air cooling gas turbine that collects cooled air as combustion air, a boost compressor that increases the pressure of the cooling air in advance by an amount corresponding to the pressure loss of the cooling air due to high-temperature cooling is necessary. Therefore, the boost compressor power may cause a decrease in plant efficiency.

  In the next high-temperature gas turbine, the combustor outlet temperature is 1500 ° C. and the compressor pressure ratio is about 25, so the compressor discharge air temperature also rises to about 500 ° C. When the pressure of the compressor discharge air at 500 ° C. is increased by the boost compressor, the temperature of the cooling air further increases, so that it may be impossible to cool the high temperature portion. Therefore, it is essential to reduce the temperature of the cooling air from the compressor discharge by the precooler so that the high temperature portion can be cooled.

  As described above, in the closed air cooling gas turbine, the precooler and the boost compressor are required as auxiliary machines, and the exhaust heat of the precooler and the power of the boost compressor cause the plant efficiency to decrease.

  In order to minimize this reduction in efficiency, the issue is how to effectively use the precooler exhaust heat as a combined cycle in terms of improving plant efficiency. In order to increase the exhaust heat recovery effect of the precooler, it is desirable to supply a high-temperature refrigerant to the precooler and recover the exhaust heat at a location where the temperature is as high as possible. However, there is a possibility that the temperature of the cooling air cannot be lowered as much as necessary with a high-temperature refrigerant, and the high-temperature portion cannot be sufficiently cooled. The prior art does not mention the configuration of the precooler heat exchanger and the precooler exhaust heat recovery cycle that solve these problems.

  In addition, the amount of cooling air required for cooling the high-temperature part of the gas turbine fluctuates in various operating conditions, from starting the closed air cooling gas turbine to rated operation and stopping, so it is necessary to control the cooling air flow rate accordingly. . Furthermore, in order to maintain the precooler outlet cooling air temperature at a set value in various operating states, it is necessary to control the amount of refrigerant supplied to the precooler. When recovering a refrigerant that has been used in a precooler and the temperature has risen, if the difference between the refrigerant temperature and the recovery destination temperature is large, it can cause thermal stress, so it is necessary to control the temperature difference to be within an allowable value. .

Further, in this closed cooling system, cracks occur due to the life of the gas turbine high temperature part, and cooling air may leak from there. When this leak becomes large, the high temperature part after the leak cannot be sufficiently cooled, and the temperature of the recovered air also becomes high. When the amount of air recovered into the combustor decreases due to leakage, the amount of working gas passing through the turbine first stage stationary blades decreases, and the first stage stationary blade inlet pressure decreases. When the first stage stationary blade inlet pressure decreases, the gas turbine output decreases. At this time, if the vehicle is operated in a constant load control state, the amount of fuel is increased to prevent a decrease in output. However, since the amount of air entering the combustor is reduced due to leakage, the combustion temperature rises. Conventionally, an increase in combustion temperature is detected by an increase in exhaust gas temperature. However, when a leak occurs in the closed cooling method, the exhaust gas temperature does not increase and may not be detected at the exhaust gas temperature.

  The present invention has been made in view of this, and an object of the present invention is to effectively recover the exhaust heat of the precooler described above to a plant and to improve efficiency. It is another object of the present invention to provide a combined power plant and a closed air cooling gas turbine system of this type that can maintain an appropriate operating state in various operating modes of the closed air cooling gas turbine and can improve reliability.

  That is, the present invention uses, as a cooling medium for cooling the high temperature portion of the gas turbine, the air discharged from the compressor by the precooler and the pressure increased by the boost compressor, and the cooled air is recovered to the combustor as combustion air. In the combined power plant comprising an air-cooled gas turbine, an exhaust heat recovery boiler that generates steam from the exhaust gas of the gas turbine, and a steam turbine that converts the steam generated in the exhaust heat recovery boiler into power, the air cooling As the precooler of the gas turbine, a plurality of heat exchangers each having a different temperature of the cooling medium are provided, and the precooler upstream heat exchanger is supplied with a high temperature refrigerant and is recovered so as to be recovered at a high temperature point. It is intended to achieve the intended purpose.

  Further, the precooler of the air-cooled gas turbine includes a plurality of heat exchangers, and both the steam and water supply from the exhaust heat recovery boiler are used as a cooling medium for the precooler, and the steam and water supply whose temperature has increased after cooling are used. The waste heat recovery boiler is again supplied. Further, the precooler of the air-cooled gas turbine includes a plurality of heat exchangers, and the high pressure is obtained by increasing the steam at the outlet of the high-pressure steam turbine and the medium pressure economizer outlet feed water of the exhaust heat recovery boiler as the cooling medium of the precooler. Both the feed water is used, and the steam and feed water whose temperature has risen after the precooler cooling is supplied to the reheater outlet and the high pressure evaporator inlet, respectively.

  In addition, as a cooling medium for cooling the high-temperature part of the gas turbine, the air discharged from the compressor is cooled by a precooler and the pressure is increased by a boost compressor, and the cooled air is recovered in the combustor as combustion air. In order to generate steam of high pressure, medium pressure and low pressure from the turbine and the exhaust gas of this gas turbine, equipped with economizer, evaporator and superheater for high pressure, medium pressure and low pressure steam respectively, In a combined power plant having an exhaust heat recovery boiler having a reheater that reheats steam at an outlet of a high pressure steam turbine driven by the high pressure steam, and a steam turbine that converts steam from the exhaust heat recovery boiler into power The precooler of the air-cooled gas turbine is provided with a plurality of heat exchangers, and the precooler is cooled with the steam at the outlet of the high-pressure evaporator as a cooling medium. Using both the high-pressure feed water boosted from the medium-pressure economizer outlet feed water of the exhaust heat recovery boiler, the steam and feed water whose temperature has risen after the precooler cooling is supplied to the high-pressure superheater outlet and the high-pressure evaporator inlet, respectively. It is a thing.

  In addition, the precooler of the air-cooled gas turbine includes a plurality of heat exchangers, and the medium pressure obtained by boosting the steam at the outlet of the high-pressure steam turbine and the low-pressure economizer outlet water supply of the exhaust heat recovery boiler as the cooling medium of the precooler. Both the feed water is used, and the steam and feed water whose temperature has risen after precooler cooling is supplied to the reheater outlet and the medium pressure economizer outlet, respectively.

  Further, a device for adjusting the supply flow rate to the precooler is provided on the supply system from the exhaust heat recovery boiler to the precooler or the recovery system from the precooler to the exhaust heat recovery boiler, and the recovery pipe and the exhaust heat recovery boiler pipe The precooler supply flow rate adjusting device adjusts the supply flow rate to the precooler so that the temperature difference at the junction with

  In addition, a device for adjusting the recovery temperature to the exhaust heat recovery boiler by mixing steam or water on the recovery pipe from the precooler of the gas turbine to the exhaust heat recovery boiler is provided, and the recovery pipe and the exhaust heat recovery boiler pipe The amount of steam or water mixed is changed by the recovery temperature adjusting device so that the temperature difference becomes less than the allowable value at the merging point.

  In addition, as the cooling medium for cooling the high-temperature part of the gas turbine, the air discharged from the compressor is cooled by the precooler and the pressure is increased by the boost compressor, and the cooled air is recovered in the combustor as the combustion air. In the gas turbine system, the exhaust heat of the precooler is used for increasing the temperature of the fuel of the gas turbine. Moreover, an evaporator is provided as a heat exchanger for the precooler. The boost compressor drive device is an electric motor, and the amount of cooling air supplied to the gas turbine high-temperature section by changing the number of revolutions of the boost compressor according to the exhaust gas temperature of the gas turbine or the number of revolutions of the gas turbine. Is adjusted.

  The boost compressor drive source is a gas turbine rotating shaft. The cooling medium flow system is provided with detecting means for detecting a leakage state of the cooling air, and the fluctuation amount of the fuel flow rate or the fluctuation amount of the recovered air pressure is used for the detection of the leakage state. .

  That is, in the plant formed in this way, a plurality of pre-cooler heat exchangers are provided, and a high-temperature refrigerant is supplied to the pre-cooler upstream heat exchanger, and is recovered at a high-temperature location. At the same time, if the cooling air temperature is not sufficiently lowered, the cooling effect of the gas turbine high temperature part can be enhanced by supplying a low temperature refrigerant to the downstream heat exchanger. For adjusting the amount of cooling air necessary for cooling the gas, the boost compressor drive device is an electric motor, and the rotational speed of the boost compressor is changed in accordance with the exhaust gas temperature of the gas turbine or the rotational speed of the gas turbine. This can be achieved by adjusting the amount of air supplied to the high temperature section of the turbine. Further, the amount of air supplied to the high temperature portion of the gas turbine is controlled by an air flow rate adjusting device provided on the cooling air supply pipe according to the exhaust gas temperature of the gas turbine or the rotation speed of the gas turbine, and the high temperature portion of the gas turbine is controlled. The cooling effect can be enhanced.

  For maintaining the precooler outlet cooling air temperature at the set value in various operating conditions, the refrigerant flow rate to the precooler on the refrigerant supply pipe from the exhaust heat recovery boiler to the precooler or the refrigerant recovery pipe from the precooler to the exhaust heat recovery boiler This is achieved by measuring the precooler outlet air temperature and adjusting the refrigerant supply flow rate to the precooler by the precooler refrigerant flow rate adjustment device so that the temperature becomes a set value.

  Also, when recovering the refrigerant that has been used in the precooler and the temperature has risen, if there is a large difference between the refrigerant temperature and the recovery destination temperature, it can cause thermal stress. A device for adjusting the flow rate of refrigerant supplied to the precooler is installed on the recovery pipe from the precooler to the exhaust heat recovery boiler, and the precooler is supplied so that the temperature difference at the junction between the recovery pipe and the exhaust heat recovery boiler pipe is less than the allowable value. This can be achieved by adjusting the refrigerant flow rate to the precooler by the flow rate adjusting device.

  In addition, a device that adjusts the recovery temperature to the exhaust heat recovery boiler by mixing steam or water on the recovery pipe from the precooler to the exhaust heat recovery boiler is installed, and the temperature at the junction of the recovery pipe and the exhaust heat recovery boiler pipe This can also be achieved by changing the amount of steam or water mixed by the recovery temperature adjusting device so that the difference is less than the allowable value. Detection of cooling air leaks can be accomplished by monitoring fuel flow fluctuations or recovered air pressure.

  As described above, according to the present invention, the exhaust heat of the precooler is effectively recovered in the plant, and it is possible to achieve high efficiency. Further, in the various operation modes of the closed air cooling gas turbine, it is possible to perform proper operation. This type of air-cooled gas turbine system capable of maintaining the state and improving the reliability can be obtained.

  Hereinafter, the present invention will be described in detail based on the illustrated embodiments. FIG. 1 shows a system diagram of the closed air cooled gas turbine system. The gas turbine apparatus mainly includes a compressor 1, a combustor 2, and a turbine 3, and the steam turbine apparatus includes a high pressure steam turbine 4, a reheat steam turbine 5, and a low pressure steam turbine 6. In this case, the gas turbine device, the steam turbine device, and the generator 7 are installed on the same axis.

  Exhaust gas from the turbine 3 is supplied to the exhaust heat recovery boiler 9 via the path 8. The exhaust heat recovery boiler 9 includes a low pressure economizer 10, a low pressure drum 11, a low pressure evaporator 12, an intermediate pressure economizer 13, an intermediate pressure drum 14, an intermediate pressure evaporator 15, a low pressure superheater 16, and a high pressure economizer. 17, medium pressure superheater 18, high pressure drum 19, high pressure evaporator 20, high pressure primary superheater 21, primary reheater 22, secondary reheater 23, high pressure secondary superheater 24, feed water pump 25, medium A pressure pump 26, a high-pressure pump 27, a recirculation pump 28, and a precooler water supply pump 29 are installed.

  The steam turbine system includes a high pressure steam turbine 4, a reheat steam turbine 5, a low pressure turbine 6, and a condenser 30, and the closed air cooling system includes a precooler 31, a boost compressor 32, and a gas turbine high temperature section 33. Yes.

  The compressor inlet air 41 is pressurized by the compressor 1 and supplied to the combustor 2. A part of the compressor discharge air is reduced in temperature by the precooler 31. The air reduced in temperature by the precooler 31 is pressurized by the boost compressor 32 and used to cool the gas turbine high temperature section 33. The air that has cooled the gas turbine high-temperature portion 33 is recovered by the combustor 2 without being released into the turbine gas path.

  In the combustor 2, the fuel 42 is combusted by the compressor discharge air and the recovered cooling air, and high-temperature and high-pressure combustion gas is generated. The combustion gas works in the turbine 3, and the exhaust gas passes through the path 8 and is supplied to the exhaust heat recovery boiler 9. The exhaust gas heat recovered by the exhaust heat recovery boiler 9 is released to the atmosphere 45.

  The feed water from the condenser 30 flows through the feed water pump 25 and flows into the low pressure economizer 10 in the exhaust heat recovery boiler 9. The outlet water supply of the low pressure economizer 10 is supplied to the low pressure drum 11 and simultaneously to the intermediate pressure pump 26 and the recirculation pump 28. The feed water at the outlet of the recirculation pump 28 merges with the low pressure economizer 10 inlet, and the low pressure economizer inlet feed water temperature is raised to prevent low temperature corrosion of the low pressure economizer 10 due to condensation.

  The feed water at the outlet of the intermediate pressure pump 26 is guided to the intermediate pressure economizer 13 and supplied to the intermediate pressure drum 14 and the high pressure pump 27. The feed water at the outlet of the high pressure pump 27 is supplied to the high pressure drum 19 through the high pressure economizer 17. The feed water of the high-pressure drum 19 becomes saturated steam in the high-pressure evaporator 20 and is supplied to the high-pressure primary superheater 21.

  The steam that has exited the high-pressure primary superheater 21 merges with a part of the feed water at the outlet of the high-pressure pump 27 by the temperature controller 34 and is supplied to the high-pressure secondary superheater 24. The high-pressure pump outlet water supply amount to the temperature controller 34 is adjusted so that the temperature of the outlet of the high-pressure secondary superheater 24 becomes an appropriate temperature. The high-pressure secondary superheater 24 outlet steam is supplied to the high-pressure steam turbine 4 through the main steam pipe 35. The steam that has worked in the high-pressure steam turbine 4 is supplied to the primary reheater 22 through the pipe 36.

  The steam that has exited the primary reheater 22 merges with a part of the feed water from the outlet of the intermediate pressure pump 26 by the temperature controller 37 and is supplied to the secondary reheater 23. The steam exiting the secondary reheater 23 is supplied to the reheat steam turbine 5 through the pipe 38. The amount of water supplied to the intermediate pressure pump outlet to the temperature controller 37 is adjusted so that the temperature at the outlet of the secondary reheater 23 becomes an appropriate temperature. The steam that has worked in the reheat steam turbine 5 is supplied to the inlet of the low-pressure steam turbine 6 through the pipe 39.

  On the other hand, the feed water supplied to the low-pressure drum 11 is evaporated by the low-pressure evaporator 12 and led to the low-pressure superheater 16. The steam that has exited the low-pressure superheater 16 passes through the pipe 40 and joins the steam from the reheat steam turbine outlet at the inlet of the low-pressure steam turbine 6 and is supplied to the low-pressure steam turbine 6. Steam discharged from the low-pressure turbine 6 becomes water in the condenser 30 and is supplied to the exhaust heat recovery boiler 9 by the feed water pump 25.

  The heat recovery system of the precooler will be described. The precooler 31 is divided into a high temperature side heat exchanger 43 and a low temperature side heat exchanger 44. The high temperature side heat exchanger 43 is supplied with steam obtained by mixing the steam that has passed through the intermediate pressure evaporator 15 and the intermediate pressure superheater and the steam at the outlet of the high pressure steam turbine 4. The steam whose temperature has risen due to heat exchange with the cooling air in the high temperature section 33 in the high temperature side heat exchanger 43 joins the outlet of the primary reheater. The low temperature side heat exchanger 44 is branched from the outlet of the medium pressure economizer 13 and is fed with water that has been pressurized by the supply pump 29. The feed water whose temperature has been raised by the low temperature side heat exchanger 44 joins the outlet of the high pressure economizer 17.

  In this embodiment, the high-pressure steam turbine 4 outlet steam is distributed to the primary reheater 22 and the high temperature side heat exchanger 43 and merges before the temperature regulator 37. That is, since the flow rate of the steam supplied to the primary reheater 22 is reduced by the amount of branching of the steam to the high temperature side heat exchanger 43, the amount of heat recovered in the primary reheater 22 is reduced, thereby reducing the primary flow. The temperature of the exhaust gas that has passed through the reheater 22 rises and the amount of evaporation in the high-pressure evaporator 20 increases. That is, the output of the steam turbine increases and the plant efficiency increases.

  The cooling air that has passed through the high temperature side heat exchanger 43 does not drop below the steam temperature supplied to the high temperature side heat exchanger 43, and the cooling air temperature may not be sufficiently reduced. In this embodiment, a low-temperature side heat exchanger 44 is provided to supply a low-temperature refrigerant and further lower the cooling air temperature. As a result, the power of the boost compressor 32 is reduced, which is advantageous in terms of cooling the high-temperature portion 33 of the gas turbine.

  In this embodiment, the water supply at the outlet of the medium pressure economizer 13 is distributed to the high pressure economizer 17 and the low temperature side heat exchanger 44 and merges at the outlet of the high pressure economizer 17. That is, the amount of water supplied to the high-pressure economizer 17 is reduced by the amount of water supplied to the low-temperature side heat exchanger 44, so that the temperature of the exhaust gas that has passed through the high-pressure economizer 17 rises and the intermediate-pressure evaporator 15 The amount of evaporation increases. That is, the output of the steam turbine increases and the plant efficiency increases.

  The compressor discharge air temperature is about 500 ° C. at a pressure ratio of about 25, while the secondary reheater outlet steam temperature is 538 ° C. to 593 ° C., and the primary reheater outlet steam temperature level is 400 ° C. to 500 ° C. Therefore, the steam at the outlet of the high temperature side heat exchanger 43 is recovered at the outlet of the primary reheater where the temperature can be matched.

  Another example of the present invention is shown in FIG. This embodiment is different from the embodiment of FIG. 1 in that the steam from the high pressure evaporator 20 is supplied to the high temperature side heat exchanger 43 and the recovered steam is recovered at the outlet of the high pressure primary superheater 21. is there. Also in the present embodiment, the amount of high-pressure steam generated increases as in the embodiment of FIG. 1, and the plant efficiency increases. Also in the present embodiment, the steam at the outlet of the high temperature side heat exchanger 43 is recovered at the outlet of the high pressure primary superheater that can match the temperature.

  Another embodiment of the present invention is shown in FIG. This embodiment is different from the embodiment of FIG. 1 in that the feed water at the outlet of the intermediate pressure pump 26 is supplied to the low temperature side heat exchanger 44 and the recovered heat feed water is recovered at the outlet of the intermediate pressure economizer 13. is there. In the present embodiment, the refrigerant supplied to the precooler 31 is an intermediate pressure system of the exhaust heat recovery boiler 9 and can be set lower than the pressure of the cooling air passing through the precooler 31. That is, when a crack occurs in the high temperature side heat exchanger 43 or the low temperature side heat exchanger 44, the cooling air leaks into the steam or the feed water, so that damage to the boost compressor 32 located downstream can be prevented from being mixed. , Driving reliability is improved.

  Another embodiment of the present invention is shown in FIG. This embodiment differs from the embodiment of FIG. 1 in that the feed water whose temperature has been raised by the low temperature side heat exchanger 44 is supplied to the fuel heater 45 and heat is recovered in the fuel 42. According to the present embodiment, the amount of fuel supplied to the combustor 2 can be reduced by the amount of temperature rise due to fuel heating, so that the plant efficiency is increased. Since the temperature of the fuel is sufficiently lower than the temperature of the water supply or steam, it is effective for low-temperature heat recovery and the recovered heat amount directly acts on the reduction of the fuel amount, so that the plant efficiency is most greatly improved.

  Another embodiment of the present invention is shown in FIG. This embodiment is different from the embodiment of FIG. 1 in that the high temperature side heat exchanger 43 is an evaporator. The low-temperature side heat exchanger 44 is fed with water supply whose pressure has been increased by the supply pump 29. The feed water whose temperature has risen in the low-temperature side heat exchanger 44 is supplied to the drum 46, evaporated in the high-temperature side heat exchanger 43, and supplied to the inlet of the high-pressure primary superheater 21. Also in the present embodiment, the amount of high-pressure steam generated increases as in the embodiment of FIG. 1, and the plant efficiency increases.

Another embodiment of the present invention is shown in FIG. A flow rate adjusting valve 48 is installed on the refrigerant supply pipe from the exhaust heat recovery boiler 9 to the high temperature side heat exchanger 43, and the refrigerant temperature T ₁ recovered from the high temperature side heat exchanger 43 to the exhaust heat recovery boiler 9 The temperature T ₂ before joining on the exhaust heat recovery boiler side is detected, and the temperature difference between T ₁ and T ₂ falls within an allowable temperature difference where thermal stress does not become a problem. Adjust the refrigerant inflow.

  FIG. 7 shows the exhaust heat recovery boiler inlet exhaust gas and precooler inlet air temperature, GT rotation speed, and plant output change from startup to rated operation. From this figure, between the points A and B, the precooler inlet air temperature is higher than the exhaust gas temperature, and the temperature relationship is reversed from that during rated operation.

If the distribution amount at the branch point 47 is not controlled by the flow rate control valve 48, even if the temperature difference at the junction 49 is within an allowable value during rated operation, the precooler is near the point B from the point A. the temperature difference exceeds the allowable value quantity of heat recovered is heated to a high temperature side heat exchanger 43 outlet temperature T ₁ is a temperature higher than the pre-merging the temperature T ₂ of the exhaust heat recovery boiler for relatively increased than the recovery amount of heat from the exhaust gas There is a possibility. Therefore, in such a case, by increasing the opening degree of the flow control valve 48 and increasing the distribution ratio to the high temperature side heat exchanger 43, an increase in the outlet temperature of the high temperature side heat exchanger 43 is suppressed and the temperatures of T1 and T2 are suppressed. The difference can be kept within tolerance.

Another embodiment of the present invention is shown in FIG. This embodiment is different from the embodiment of FIG. 6 in that a temperature controller 51 is installed on the pipe from the high temperature side heat exchanger 43 to the junction 49 in order to suppress an excessive temperature difference at the junction 49. is there. The temperature T _{1 of the} refrigerant recovered from the high temperature side heat exchanger 43 to the exhaust heat recovery boiler 9 and the pre-merging temperature T ₂ on the exhaust heat recovery boiler side are detected, and the temperature difference between T1 and T2 does not cause a problem of thermal stress. Water or steam is supplied to the temperature controller 51 through the supply flow rate adjustment valve 50 so as to be within an allowable temperature difference.

In this embodiment, the outlet air temperature T ₃ of the precooler 31 is detected so as to keep the cooling air temperature supplied to the inlet of the boost compressor 32 and the gas turbine high temperature section 33 at the set temperature, and the low temperature side is detected by the flow rate adjustment valve 52. The amount of refrigerant supplied to the heat exchanger 44 is adjusted.

  Furthermore, in this embodiment, a recirculation pump 53 is installed at the outlet of the low temperature side heat exchanger 44. By combining the refrigerant whose temperature at the outlet of the low-temperature side heat exchanger 44 has increased with the inlet of the low-temperature side heat exchanger 44, the refrigerant temperature at the inlet of the low-temperature side heat exchanger 44 can be raised and condensation of the precooler outlet air can be prevented. That is, damage to the boost compressor 32 due to inflow of water droplets into the boost compressor 32 can be prevented, so that reliability is improved.

  Another embodiment of the present invention is shown in FIG. In this embodiment, the gas turbine exhaust gas temperature T is detected, and the rotation speed of the drive motor 54 of the boost compressor 32 is controlled according to the exhaust gas temperature T. Under normal operating conditions, the exhaust gas temperature T is linked to the temperature of the gas turbine high temperature section 33. Therefore, if the exhaust gas temperature rises, the gas turbine high temperature section 33 also rises in temperature. To ensure the required flow rate. By this operation method, an appropriate amount of cooling air can be supplied to the gas turbine high temperature section 33.

  Another embodiment of the present invention is shown in FIG. In this embodiment, the gas turbine rotational speed N and the plant output W are detected, and the rotational speed of the drive motor 54 of the boost compressor 32 is controlled according to the turbine speed N and the plant output W. Although there are some fluctuations depending on the atmospheric state, the exhaust gas temperature can be known if the gas turbine rotation speed and the plant output can be known as shown in FIG. 7 in a normal operation state. That is, the temperature of the gas turbine high-temperature part 33 is predicted from the gas turbine rotational speed N and the plant output W via the exhaust gas temperature, and the rotational speed of the drive motor 54 is controlled. An appropriate amount of cooling air can be supplied by this operation method.

  Another embodiment of the present invention is shown in FIG. In this embodiment, the gas turbine exhaust gas temperature T is detected, and the cooling air supply amount adjusting valve 55 is controlled in accordance with the exhaust gas temperature T. Under normal operating conditions, the exhaust gas temperature T is linked to the temperature of the gas turbine high temperature section 33. Therefore, if the exhaust gas temperature increases, the gas turbine high temperature section 33 also increases in temperature. Increase the amount of cooling air. An appropriate amount of cooling air can be supplied to the gas turbine high temperature section 33 also by this operation method.

  Another embodiment of the present invention is shown in FIG. This embodiment is different from the embodiment of FIG. 11 in that the drive source of the boost compressor 32 is a gas turbine rotating shaft 56. By using the gas turbine shaft drive, the boost compressor can always be operated while the gas turbine is rotating, so that the reliability of the boost compressor is improved without the risk of stopping the boost compressor due to a power failure.

Another embodiment of the present invention is shown in FIG. When a leak exceeding the allowable value occurs for some reason from the gas turbine high temperature portion 33, the amount of cooling air recovered in the combustor 2 decreases. Due to the decrease in the amount of recovered cooling air, the amount of combustion gas at the turbine first stage stationary blade inlet also decreases, and the pressure at the first stage stationary blade inlet decreases. As the first stage stationary blade inlet pressure decreases, the recovered cooling air pressure P also decreases.

  In order to prevent a decrease in the plant output due to a decrease in the first stage stationary blade inlet pressure, the amount of fuel increases. If the amount of cooling air recovered decreases and the amount of fuel supplied decreases, but the amount of fuel increases, the combustion temperature rises and the gas turbine high temperature section 33 is damaged. In a closed-air cooled gas turbine, even if the combustion temperature rises due to a leak of cooling air, the leak air lowers the gas temperature, so there is a possibility that an increase in the combustion temperature cannot be detected due to an increase in the exhaust gas temperature T1.

  As shown in FIG. 14, when the closed cooling air leaks, the fuel flow rate G increases and the recovered air pressure, that is, the combustor pressure P decreases for the above-described reason. Therefore, the fuel flow rate G and the combustor pressure P are monitored. Thus, leakage of closed cooling air can be detected.

  That is, the fuel flow rate control valve detects the fuel flow rate G, the combustor pressure P, the exhaust gas temperature T1, and the plant output W so that the plant output W becomes a set value within a range where the exhaust gas temperature T1 does not exceed the limit value during normal operation. The fuel supply amount is adjusted by 58. However, when the fuel amount G is supplied more than the allowable value within the unit time, or when the temperature of the combustor pressure P falls within the allowable value within the unit time, the closed cooling air leaks beyond the allowable value. The fuel flow control valve 58 is closed by a signal from the fuel flow control valve control device 57 and the plant is stopped.

  With this operation method, even if the closed cooling air leaks, the plant can be safely stopped without damaging the high temperature portion of the gas turbine.

  As described above, in the closed air cooling gas turbine system formed as described above, a plurality of precooler heat exchangers are provided, and a high temperature refrigerant is supplied to the precooler upstream heat exchanger to provide a high temperature location. Since the cooling air temperature is sufficiently reduced, the cooling effect of the gas turbine high-temperature part is enhanced by supplying a low-temperature refrigerant to the downstream heat exchanger as long as the cooling air temperature is not sufficiently lowered. It is possible to satisfy the optimization of the precooler exhaust heat recovery system from the viewpoint of high efficiency of the combined cycle and the reduction of the precooler outlet air temperature from the viewpoint of cooling the high temperature portion of the gas turbine.

  According to the present invention, the boost compressor drive device is an electric motor, and the rotation speed of the boost compressor is changed in accordance with the exhaust gas temperature of the gas turbine or the rotation speed of the gas turbine. The amount of cooling air required for cooling can be adjusted.

  According to the present invention, since the air flow rate adjusting device provided on the cooling air supply pipe according to the exhaust gas temperature of the gas turbine or the gas turbine rotation speed is provided, the amount of cooling air required for cooling the high temperature portion of the gas turbine Can be adjusted.

  According to the present invention, the apparatus for adjusting the refrigerant flow rate to the precooler is provided on the refrigerant supply pipe from the exhaust heat recovery boiler to the precooler or the refrigerant recovery pipe from the precooler to the exhaust heat recovery boiler, and the precooler outlet air temperature is measured. Since the refrigerant supply flow rate to the precooler is adjusted by the precooler refrigerant flow rate adjusting device so that the temperature becomes the set value, the precooler outlet cooling air temperature can be maintained at the set value in various operating states.

  According to the present invention, the apparatus for adjusting the flow rate of refrigerant supplied to the precooler is provided on the supply pipe from the exhaust heat recovery boiler to the precooler or the recovery pipe from the precooler to the exhaust heat recovery boiler, and the recovery pipe and the exhaust heat recovery boiler pipe The refrigerant flow rate to the precooler is adjusted by the precooler supply flow rate adjustment device so that the temperature difference at the confluence with the precooler is less than the allowable value. The thermal stress can be reduced by keeping the difference from the temperature at the collection destination within an allowable value.

  According to the present invention, a device for adjusting the recovery temperature to the exhaust heat recovery boiler by mixing steam or water on the recovery pipe from the precooler to the exhaust heat recovery boiler is provided. Since the amount of steam or water mixed is changed by the recovery temperature adjustment device so that the temperature difference is less than the allowable value at the junction, when recovering the refrigerant that has been used in the precooler and the temperature has risen, the temperature of the refrigerant and the recovery destination The thermal stress can be reduced by keeping the difference from the temperature within the allowable value.

  According to the present invention, since the fluctuation of the fuel flow rate or the recovered air pressure is monitored, the leakage of the cooling air can be detected.

1 is a system diagram showing an embodiment of a closed air cooled gas turbine system of the present invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a gas turbine characteristic figure from starting to a rating. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a systematic diagram which shows the other Example of the closed air cooling gas turbine system of this invention. It is a gas turbine characteristic view at the time of closed cooling air leak.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 4 ... High pressure steam turbine, 13 ... Medium pressure economizer, 15 ... Medium pressure evaporator, 17 ... High pressure economizer, 20 ... High pressure evaporator, 22 ... Primary reheater, 32 ... Boost compressor, 33 ... Gas turbine high temperature section, 37 ... temperature controller, 43 ... high temperature side heat exchanger, 44 ... low temperature side heat exchanger, 21 ... high pressure primary superheater, 9 ... exhaust heat recovery boiler, 26 ... medium pressure pump, 31 ... Precooler, 2 ... Combustor, 42 ... Fuel, 45 ... Fuel heater, 29 ... Supply pump, 46 ... Drum, 47 ... Branch point, 48 ... Flow control valve, 49 ... Confluence, 50 ... Supply flow control valve, 51 DESCRIPTION OF SYMBOLS ... Temperature controller, 52 ... Flow control valve, 53 ... Recirculation pump, 54 ... Drive motor, 55 ... Cooling air supply flow control valve, 56 ... Gas turbine rotating shaft, 57 ... Fuel flow control valve controller, 58 ... Fuel Flow control valve.

Claims (8)

As a cooling medium for cooling the high-temperature part of the gas turbine, a closed-air cooling gas turbine that uses air precooled by the compressor and increased in pressure by the boost compressor, and the cooled air is recovered in the combustor as combustion air; An exhaust heat recovery boiler that generates steam from the exhaust gas of the gas turbine, and a steam turbine that converts steam generated in the exhaust heat recovery boiler into power, and the exhaust gas is used as a cooling medium for the heat exchanger of the precooler. In the combined power plant that uses the steam or feed water branched from the heat recovery boiler, the steam that has risen in temperature after cooling the precooler, and the feed water joins the exhaust heat recovery boiler again,
A device for adjusting the supply flow rate to the precooler is provided on the supply system from the exhaust heat recovery boiler to the precooler or the recovery system from the precooler to the exhaust heat recovery boiler, and the recovery pipe and the exhaust heat recovery boiler pipe A combined power generation plant characterized in that the supply flow rate to the precooler is adjusted by the precooler supply flow rate adjusting device so that the temperature difference at the junction is equal to or less than an allowable value. As a cooling medium for cooling the high-temperature part of the gas turbine, a closed-air cooling gas turbine that uses air precooled by the compressor and increased in pressure by the boost compressor, and the cooled air is recovered in the combustor as combustion air; An exhaust heat recovery boiler that generates steam from the exhaust gas of the gas turbine, and a steam turbine that converts steam generated in the exhaust heat recovery boiler into power, and the exhaust gas is used as a cooling medium for the heat exchanger of the precooler. In the combined power plant that is configured to use steam or feed water branched from the heat recovery boiler, steam that has risen in temperature after cooling the precooler, and feed water to join the exhaust heat recovery boiler again,
A device for adjusting the supply flow rate of the refrigerant to the precooler is provided on the supply system from the exhaust heat recovery boiler to the precooler or the recovery system from the precooler to the exhaust heat recovery boiler, and the precooler outlet air temperature becomes a set value. As described above, the combined power generation plant is characterized in that the refrigerant supply flow rate to the precooler is adjusted by the precooler supply flow rate adjusting device. As a cooling medium for cooling the high-temperature portion of the gas turbine, a closed-air cooling gas turbine that uses air precooled by the compressor and boosted by the boost compressor and collects the cooled air as combustion air in the combustor. In the system,
A closed air cooled gas turbine system, wherein the exhaust heat of the precooler is used to increase the temperature of fuel in the gas turbine. A closed-air cooled gas turbine system that uses the air discharged from the compressor as a cooling medium for cooling the high-temperature portion of the gas turbine with the precooler and increased in pressure by the boost compressor, and recovers the cooled air as combustion air in the combustor. In
A closed air cooled gas turbine system comprising an evaporator as a heat exchanger for the precooler. As a cooling medium for cooling the high-temperature portion of the gas turbine, a closed-air cooling gas turbine that uses air precooled by the compressor and boosted by the boost compressor and collects the cooled air as combustion air in the combustor. In the system,
The boost compressor drive unit is an electric motor, and the rotation speed of the boost compressor is changed in accordance with the exhaust gas temperature of the gas turbine or the rotation speed of the gas turbine, and the amount of cooling air supplied to the high temperature section of the gas turbine is adjusted. A closed air-cooled gas turbine system, characterized in that: As a cooling medium for cooling the high-temperature portion of the gas turbine, a closed-air cooling gas turbine that uses air precooled by the compressor and boosted by the boost compressor and collects the cooled air as combustion air in the combustor. In
A closed air cooled gas turbine system, wherein a drive source of the boost compressor is a gas turbine rotating shaft.   An apparatus for adjusting an air flow rate according to an exhaust gas temperature of the gas turbine or a gas turbine rotational speed is provided on a cooling air supply pipe for supplying the cooling medium so as to adjust an amount of air supplied to the high-temperature portion of the gas turbine. The closed air cooling gas turbine system according to claim 6. As a cooling medium for cooling the high-temperature portion of the gas turbine, a closed-air cooling gas turbine that uses air precooled by the compressor and boosted by the boost compressor and collects the cooled air as combustion air in the combustor. In the system,
The cooling medium flow system is provided with detection means for detecting a leakage state of the cooling air, and a fluctuation amount of the fuel flow rate or a fluctuation amount of the recovered air pressure is used for the detection of the leakage state. Closed air cooled gas turbine system.

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