JP2011149434A - Gas turbine combined power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas turbine combined power generation system capable of efficiently and effectively utilizing or recovering energy with a simple structure. <P>SOLUTION: The gas turbine combined power generation system 200, including a fuel gas return line 50 through which a part of fuel gas can be circulated, a gas turbine generator comprising a fuel gas compressor 32 compressing the fuel gas while circulating the part of the fuel gas, a combustor 35 combusting the fuel gas, and an air compressor 37 supplying compressed air to the combustor 35, and a steam power generator comprising an exhaust heat recovery boiler 100 and a steam turbine 131, has a heat exchanger 210 exchanging heat between the high-temperature and high-pressure fuel gas compressed by the fuel gas compressor 32, flowing through the fuel gas return line 50, and supplied water for the exhaust heat recovery boiler 100 in order to heat the supplied water for the exhaust heat recovery boiler 100. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a gas turbine combined power generation system capable of effectively using energy, and more particularly to a combined power generation system including a gas turbine power generation apparatus having a fuel gas compressor that circulates a part of fuel gas.

  FIG. 7 is a diagram showing a schematic configuration of a gas turbine combined power generation system 1 that uses a low pressure / low heating value fuel such as a conventional blast furnace gas. The gas turbine combined power generation system 1 is roughly classified into a gas turbine power generation device and a steam power generation device. The gas turbine power generation apparatus generates power by driving a gas turbine and a generator connected to the gas turbine with combustion gas obtained by burning fuel such as blast furnace gas. On the other hand, the steam power generator recovers the heat of the combustion gas that has exited the gas turbine with an exhaust heat recovery boiler, generates steam, and drives the steam turbine and generator to generate power. In this way, the heat efficiency of the combustion gas is recovered to increase the thermal efficiency.

  In a gas turbine power generator using a low pressure / low calorific value fuel such as blast furnace gas, the pressure of the fuel gas is low, and the pressure is increased to a predetermined pressure by the axial fuel gas compressor 2 and sent to the combustor 3. And burned. Specifically, the fuel gas is guided to the electrostatic precipitator 5 through the pipe line 4 and is removed here, and then guided to the fuel gas compressor 2 where the pressure is increased to a predetermined pressure. The compressed fuel gas is sent to the combustor 3 via the fuel cutoff valve 6 and mixed with the air compressed by the air compressor 7 to burn. This combustion gas becomes a drive source of the gas turbine 8, and the gas turbine 8 drives the air compressor 7 and the fuel gas compressor 2, and also drives the generator 9, thereby generating power.

  The axial flow compressor used for the fuel gas compressor 2 has a wide surging range, and surging occurs when the flow rate of the fuel gas falls below a predetermined amount. For the purpose of avoiding this, it does not fall below the predetermined flow rate. As described above, a part of the discharge gas (fuel gas) is circulated through the fuel gas return line 10. A first gas return amount control valve 11 for adjusting the amount of return gas (circulation gas) is provided in the middle of the fuel gas return line 10. The fuel gas return line 10 has a bypass line 12 for processing a large amount of return gas, and a second gas return amount control valve 13 is disposed in the bypass line 12. When the fuel gas is compressed by the fuel gas compressor 2, the temperature of the fuel gas rises. Therefore, the circulating gas is cooled by the gas cooler 14 disposed in the fuel gas return line 10 and returned to the fuel gas compressor 2. Is done.

  The exhaust heat recovery boiler 20 includes a low-pressure economizer 21 and preheats the feed water fed by the low-pressure feed water pump 22 with the combustion gas from the gas turbine 8. Most of the preheated water is sent to the high-pressure economizer, high-pressure evaporator, and high-pressure superheater of the exhaust heat recovery boiler 20 via the high-pressure feed pump 23 to become high-pressure steam, and drives the steam turbine 24. A part of the preheated water is sent to the low-pressure evaporator and low-pressure superheater of the exhaust heat recovery boiler 20 to become low-pressure steam, and drives the steam turbine 24. The steam turbine 24 drives the generator 9 to be connected to generate power.

  The steam that exits the steam turbine 24 becomes condensate in the condenser 25 and is sent to the low-pressure feed water pump 22 via the condensate pump 26 for circulation. The exhaust heat recovery boiler includes a economizer circulation pump 27 for preventing corrosion of the low pressure economizer 21 and a chimney 28 for releasing combustion gas discharged from the exhaust heat recovery boiler 20.

  The gas turbine combined power generation system 1 is generally configured as described above, but the fuel gas compressor is different in the calories of the fuel gas returned from the fuel gas return line and the fuel gas supplied from the pipe 4. However, problems that the rotational speed and load of the gas turbine fluctuate have been pointed out. In order to solve this, a technique for mixing the fuel gas returned from the fuel gas return line and the fuel gas supplied from the pipe 4 is disclosed (for example, see Patent Document 1).

JP-A-9-79046

  In a gas turbine power generator using a low-pressure, low calorific value fuel such as blast furnace gas, or a combined power generation system including a gas turbine power generator, in a power generation system that operates while circulating a part of the compressed fuel gas As shown in FIG. 7, the energy of the high-temperature and high-pressure circulating gas in the fuel gas return line is not sufficiently utilized and recovered. This is because the circulating gas plays an important role in the operation of the power generation system, and it is necessary to circulate the circulating gas stably. After cooling the circulating gas sufficiently and reducing the pressure to near atmospheric pressure, the fuel This is due to the constraint that it must be returned to the gas compressor.

  Needless to say, these power generation systems are useful for these power generation systems if the energy can be effectively used or recovered. The technique described in Patent Document 1 is a technique that is useful for a gas turbine power generation system that uses a low-pressure, low heating value fuel such as a blast furnace gas, but is not a technique related to effective use of energy or energy recovery. A gas turbine power generation apparatus using a low-pressure, low calorific value fuel such as blast furnace gas, a combined power generation system including a gas turbine power generation apparatus, which has a technology for effectively using energy or a technology for efficiently recovering energy, It is not disclosed in other documents, and development is awaited.

  An object of the present invention is to provide a gas turbine combined power generation system that can efficiently use energy efficiently or recover energy.

  The present invention includes a fuel gas return line that can circulate a part of the fuel gas, a fuel gas compressor that compresses the fuel gas while circulating a part of the fuel gas, a combustor that burns the fuel gas, and the combustion In the gas turbine combined power generation system comprising: a gas turbine power generation device configured to include an air compressor that sends compressed air to a generator; and a steam power generation device configured to include an exhaust heat recovery boiler and a steam turbine, the fuel gas return A gas turbine combined power generation comprising a feed water heating means for raising a feed water temperature of the exhaust heat recovery boiler using a fuel gas that has been compressed by the fuel gas compressor and that has become a high temperature and a high pressure that circulates in a line System.

  Further, in the gas turbine combined power generation system according to the present invention, the exhaust heat recovery boiler includes a economizer, and the feed water heating means includes fuel gas flowing through the fuel gas return line and feed water of the exhaust heat recovery boiler. The heat exchanger uses the heat exchanger to raise the feed water temperature of the exhaust heat recovery boiler, and then feeds the feed water to the economizer.

  Further, the present invention provides the gas turbine combined power generation system, wherein the exhaust heat recovery boiler includes a economizer, and the feed water heating means is a heat pipe, and the fuel gas return line is circulated using the heat pipe. Then, heat is recovered from the fuel gas, and the recovered heat is used to raise the feed water temperature of the exhaust heat recovery boiler, and then the feed water is sent to the economizer.

  The gas turbine combined power generation system of the present invention includes a fuel gas return line capable of circulating a part of the fuel gas, and a gas turbine power generation including a fuel gas compressor that compresses the fuel gas while circulating a part of the fuel gas And a steam power generator configured to include an exhaust heat recovery boiler and a steam turbine. The exhaust gas is exhausted using fuel gas that has been compressed by a fuel gas compressor and circulated through the fuel gas return line. Since the feed water heating means for raising the feed water temperature of the heat recovery boiler is provided, the steam generation amount in the exhaust heat recovery boiler is increased by heating the feed water, and the power generation amount can be increased. The energy that has been wasted without being collected in the past can be recovered and used effectively.

  In the gas turbine combined power generation system of the present invention, the exhaust heat recovery boiler is provided with a economizer, and the feed water heating means is a heat exchanger that performs heat exchange between the fuel gas and the feed water of the exhaust heat recovery boiler, Since the feed water is sent to the economizer after raising the feed water temperature of the exhaust heat recovery boiler using the cooler, the thermal load on the economizer can be reduced. As a result, the amount of steam generated in the exhaust heat recovery boiler increases, and the amount of power generation can be increased. In addition, since the water supply temperature to the economizer is high, the heat load on the economizer circulation line necessary to prevent corrosion of the economizer is reduced, and the circulation rate of the economizer circulation line can be reduced. It becomes. Therefore, the power of the economizer circulation pump or the number and capacity of the economizer circulation pumps can be suppressed.

  In the gas turbine combined power generation system of the present invention, the exhaust heat recovery boiler is provided with a economizer, the feed water heating means is a heat pipe, and the water feed temperature of the exhaust heat recovery boiler is increased by using the heat pipe. Is sent to the economizer, so the heat load on the economizer can be reduced. As a result, the amount of steam generated in the exhaust heat recovery boiler increases, and the amount of power generation can be increased. In addition, since the water supply temperature to the economizer is high, the heat load on the economizer circulation line necessary to prevent corrosion of the economizer is reduced, and the circulation rate of the economizer circulation line can be reduced. it can. As a result, the power of the economizer circulation pump, or the number and capacity of the economizer circulation pumps can be suppressed.

1 is a diagram showing a schematic configuration of a gas turbine combined power generation system 30 as a first embodiment of the present invention. It is a figure which shows schematic structure of the gas turbine combined power generation system 200 as 2nd embodiment of this invention. It is a figure which shows schematic structure of the gas turbine combined power generation system 300 as 3rd embodiment of this invention. It is a figure which shows schematic structure of the gas turbine combined power generation system 400 as 4th embodiment of this invention. It is a figure which shows schematic structure of the gas turbine combined power generation system 500 as 5th embodiment of this invention. It is a figure which shows schematic structure of the gas turbine combined power generation system 600 as 6th embodiment of this invention. It is a figure which shows schematic structure of the gas turbine combined cycle power generation system 1 using the low pressure and low calorific value fuels, such as the conventional blast furnace gas.

  FIG. 1 is a diagram showing a schematic configuration of a gas turbine combined power generation system 30 as a first embodiment of the present invention. The gas turbine combined power generation system 30 uses blast furnace gas generated at an ironworks as a fuel. The gas turbine combined power generation system 30 is roughly classified into a gas turbine power generation device and a steam power generation device.

  The gas turbine power generation apparatus generates power by driving a gas turbine and a generator connected to the gas turbine with combustion gas obtained by burning fuel such as blast furnace gas. On the other hand, the steam power generator recovers the heat of the combustion gas that has exited the gas turbine with an exhaust heat recovery boiler, generates steam, and drives the steam turbine and generator to generate power. In this way, the heat efficiency of the combustion gas is recovered to increase the thermal efficiency.

  The blast furnace gas sent from the ironworks is sent to the fuel gas compressor 32 through the fuel receiving pipe 31. A wet electric dust collector 33 is provided in the middle of the fuel receiving pipe 31 to remove dust such as iron oxide contained in the fuel gas. Since the pressure of the blast furnace gas sent from the ironworks is as low as about 0.105 MPa, the pressure is raised to a predetermined pressure by the fuel gas compressor 32 and sent to the combustor 35 through the gas supply line 34. The gas supply line 34 is provided with a fuel cutoff valve 36 that shuts off the fuel supply to the combustor 35 in the middle of the line.

  The combustor 35 is supplied with high-pressure air from an air compressor 37. The air compressor 37 sucks outside air through an intake filter 39 provided in the suction pipe 38 and compresses it to a predetermined pressure. The high-pressure fuel gas is mixed and burned with high-pressure air in the combustor 35 to form a high-temperature and high-pressure combustion gas. The high-temperature, high-pressure combustion gas is guided to the gas turbine 40 and drives the gas turbine 40. An air compressor 37 and a generator 41 are connected to the gas turbine 40, and as the gas turbine 40 is driven, the air compressor 37 and the generator 41 are also driven, thereby generating power.

  The fuel gas compressor 32 used in the gas turbine combined power generation system 30 is an axial compressor. The axial flow compressor has a wide surging range, and surging occurs when the flow rate of the fuel gas falls below a predetermined amount. Therefore, in order to avoid this, a part of the fuel gas is circulated through the fuel gas return line 50 so that the flow rate of the fuel gas does not become a predetermined flow rate or less. The fuel gas return line 50 branches from the gas supply pipe 34 provided on the discharge side of the fuel gas compressor 32, and is provided at the branch portion 51.

  The fuel gas return line 50 includes a pipeline, a gas return amount control valve, an expansion turbine, a gas cooler, and the like. A pipe line 52 connected to the branch part 51 of the gas supply pipe line 34 includes a first gas return amount control valve 53 that controls the amount of gas circulation at one end. A pipe 54 is connected to the outlet of the first gas return amount control valve 53, and an expansion turbine 55 is mounted in the middle of the pipe. In the pipelines 56 and 57 to which the expansion turbine 55 is connected, an inlet valve 58 and an outlet valve 59 are provided as shutoff valves for shutting off the fuel gas. The generator 60 is connected to the expansion turbine 55, and the generator 60 can generate power by driving the expansion turbine 55. As will be described later, the expansion turbine 55 functions as an energy recovery device.

  In addition to the outlet valve 59, a gas cooler 65 for cooling the circulating gas is attached to the outlet line 57 of the expansion turbine 55. The reason why the circulating gas is cooled is to increase the gas density and increase the compression efficiency of the fuel gas compressor. A pipe 66 is disposed at the outlet of the gas cooler 65, and one end of the pipe 66 is connected to the fuel receiving pipe 31. The fuel gas thus cooled is sent to the fuel gas compressor 32 again.

  The fuel gas return line 50 is further provided with an expansion turbine bypass line 70 that bypasses the expansion turbine 55. The expansion turbine bypass line 70 branches the pipe line 54 that connects the first gas return amount control valve 53 and the inlet valve 58, and is connected to the branch portion 71. The expansion turbine bypass line 70 is for bypassing the expansion turbine 55 and circulating the fuel gas when the expansion turbine 55 is malfunctioning. A bypass valve 73 is provided in the middle of the pipeline 72 of the expansion turbine bypass line 70, and one end of the pipeline 72 has a first gas return amount control valve 80 for processing a large amount of return gas. It connects with the pipe line 82 of the gas return amount control valve bypass line 81.

  Another pipe 84 is connected to the connecting portion 83 between the pipe 72 of the expansion turbine bypass line 70 and the pipe 82 of the first gas return amount control valve bypass line 81. One end is connected to a pipe line 57 provided with an outlet valve 59 of the expansion turbine 55. Since the second gas return amount control valve 80 can circulate a larger amount of return gas compared to the first gas return amount control valve 53, the first gas return amount control valve bypass line 81 Used when the flow rate fluctuation is large, such as unit trip. Note that the second gas return amount control valve 80 has a branch portion 85 of the gas supply pipeline 34 on the upstream (fuel gas compressor) side of the branch portion 51 of the gas supply pipeline 34 to which the fuel gas return line 50 is connected. It is provided in the middle of the pipe line connected to.

  As described above, since the fuel gas return line 50 of the present invention includes the bypass line 70 of the expansion turbine 55 and the bypass line 81 of the first gas return amount control valve 53, the expansion turbine 55 or the first gas Even if the return amount control valve 53 malfunctions, the fuel gas can be reliably circulated through the bypass lines 70 and 81. When the circulation of the fuel gas is stopped, the entire gas turbine combined power generation system 30 needs to be stopped. By adopting such a configuration, the gas turbine combined power generation system 30 can be stably operated.

  The gas cooler 65 provided in the fuel gas return line 50 is a kind of heat exchanger, and cools the fuel gas with cooling water supplied from the outside. Cooling water supply to the gas cooler 65 is performed through a cooling water circulation line 93 including a gas cooler cooling water pump 90, a gas cooling water cooler 91, and a pipe 92. The gas cooler cooling water pump 90 supplies cooling water to the gas cooler 65, and the gas cooling water cooler 91 is a cooler that cools the cooling water circulating in the cooling water circulation line 93. The cooling water circulation line 93 also has a bypass line 95 configured to include a bypass valve 94.

  Cooling water (seawater) is supplied to the gas cooling water cooler 91 by a seawater pump 98 provided in a seawater supply pipe 97. The seawater supply pipe 97 takes in seawater with several intake pumps 96 (96 a, 96 b, 96 c, 96 d) and branches off from the middle of the seawater supply pipe 99 that is sent to the condenser 133. The seawater supplied to the gas cooling water cooler 91 cools the cooling water circulating in the cooling water circulation line 93, and the seawater whose temperature has increased is returned to the sea.

  The gas turbine power generator described above has the configuration of the conventional gas turbine power generator except for the expansion turbine 55, the generator 60 connected to the expansion turbine, the inlet valve 58 of the expansion turbine, the outlet valve 59, and the expansion turbine bypass line 70. It is similar. The gas turbine power generator according to this embodiment is characterized in that an expansion turbine 55 is provided in the middle of the fuel gas return line 50 to recover energy from the circulating fuel gas. Details will be described later.

  The gas turbine combined power generation system 30 further includes a steam power generation apparatus. Since the temperature of the combustion gas exiting the gas turbine is sufficiently high to generate steam, the heat of the combustion gas exiting the gas turbine is recovered by the exhaust heat recovery boiler. The combustion gas exiting the exhaust heat recovery boiler is exhausted from the chimney 98.

  The exhaust heat recovery boiler 100 includes a low pressure economizer 101, a high pressure economizer 102, a low pressure evaporator 103, a high pressure evaporator 104, a low pressure drum 105, a high pressure drum 106, a low pressure superheater 107, and a high pressure superheater 108. Water supply to the exhaust heat recovery boiler 100 is performed through a low-pressure feed water pump 110. Discharged water from the low-pressure feed pump 110 is guided to the low-pressure economizer 101 through the pipe 111 and preheated here. Most of the preheated water is led to the high-pressure feed pump 113 through the pipe 112, and after being pressurized, is further preheated by the high-pressure economizer 102. A part of the feed water preheated by the low pressure economizer 101 is sent to the low pressure drum 105.

  In order to prevent corrosion of the economizer, the low-pressure economizer 101 is provided with a economizer circulation line 120, and a part of the water supply preheated by the low-pressure economizer 101 and having a high temperature is saved in the economizer. It is circulated through a circulation pump 121. By circulating a part of the hot water supply water, the temperature of the water supply is raised above the dew point of the sulfurous acid gas in the combustion gas that heats the low pressure economizer 101, and corrosion of the low pressure economizer 101 is prevented. . Therefore, it is necessary to increase the circulation amount of the economizer circulation line 120 as the temperature of the feed water passing through the pipeline 111 supplied to the low-pressure economizer 101 is lower.

  The feed water whose temperature is increased by the high-pressure economizer 102 is sent to the high-pressure drum 106, the high-pressure evaporator 104, and the high-pressure superheater 108, becomes superheated steam, and then is sent to the steam turbine 131 through the high-pressure steam line 130. The turbine 131 is driven. The feed water sent to the low-pressure drum 105 is also sent to the low-pressure evaporator 103 and the low-pressure superheater 107 to become superheated steam, and then sent to the steam turbine 131 through the low-pressure steam line 132 to drive the steam turbine 131. The steam whose pressure and temperature are reduced by driving the steam turbine 131 is sent to the condenser 133 where it is cooled and becomes condensate. The steam turbine 131 is connected to the generator 41 and drives the generator 41 to generate power.

  The condenser 133 sends the condensate to the condensate pump 135 through the pipe line 134, and the condensate pump 135 boosts the condensate and then sends it to the low-pressure feed pump 110 through the pipe line 136. As a result, the feed water sent to the exhaust heat recovery boiler 100 is circulated and used through steam and condensate.

  The steam power generator of this embodiment has a configuration similar to that of conventionally used steam power generators. From the above, the characteristic of the gas turbine combined power generation system 30 as the first embodiment is that the fuel gas return line 50 constituting the gas turbine power generation device includes the expansion turbine 55 that is an energy recovery device. I can say that.

  Next, the expansion turbine 55 that is an energy recovery device provided in the fuel gas return line 50 constituting the gas turbine power generation device, and the energy recovery mechanism using the expansion turbine 55 will be described. The fuel gas obtained by compressing blast furnace gas or the like with the fuel gas compressor 32 is in a state of high temperature and high pressure, such as a gas temperature of about 410 ° C. and a pressure of about 1.5 MPa. In the conventional gas turbine power generator, the fuel gas in this state is adiabatically expanded by the gas return amount control valve to reduce the pressure and temperature. This is because the fuel gas cannot be returned to the fuel gas compressor in a high temperature and high pressure state.

  In the gas turbine combined power generation system 30 shown in the first embodiment of the present invention, the energy of the high-temperature, high-pressure fuel gas in the fuel gas return line 50 is to be recovered using the expansion turbine 55. The high-temperature, high-pressure fuel gas introduced to the expansion turbine 55 through the pipe line is adiabatically expanded in the expansion turbine 55 to drive the expansion turbine. A generator 60 is connected to the expansion turbine 55, and the generator 60 is driven to generate power as the expansion turbine 55 is driven. This means that the energy of the high-temperature, high-pressure fuel gas in the fuel gas return line 50 is recovered as electric energy. In the embodiment of the present invention, the energy of the fuel gas is recovered as electric energy, so that the recovered energy is easy to use.

  In the present invention, since energy is recovered by the expansion turbine 55, it is desirable that the temperature and pressure of the fuel gas at the inlet of the expansion turbine 55 be high. Therefore, it is necessary to select a valve type or the like so that the temperature and pressure of the fuel gas are not reduced as much as possible by the first gas return amount control valve 53 and the like.

  The high-temperature and high-pressure fuel gas expanded adiabatically in the expansion turbine 55 is discharged from the expansion turbine 55 with the temperature and pressure lowered. The fuel gas whose temperature and pressure have been reduced is further cooled by the gas cooler 65 and returned to the fuel gas compressor 32 as in the prior art. At this time, since the expansion turbine 55 can expand the fuel gas to a lower temperature than the conventional gas return amount control valve, the thermal load of the gas cooler 65 can be reduced. Thereby, compared with the conventional gas turbine combined power generation system, the power of the seawater pump 98 and the intake pump 96 or the number of operation can be reduced.

Next, an example of a calculation result obtained by applying energy that can be recovered by the expansion turbine to the gas turbine combined power generation system 30 is shown. The discharge gas (fuel gas) amount of the fuel gas compressor was about 300,000 m ³ N / h, and the gas return (gas circulation) amount was about 16,000 m ³ N / h. This value is the throughput of the fuel gas compressor currently used by the Company. The calculation is performed under the following conditions under the following conditions: (1) which is a theoretical expression of adiabatic expansion (for example, mechanical engineering manual, basic edition, applied edition, 2001, B5-6). The balance equation was used. As a result, it was found that energy of about 1700 to 1800 kW can be recovered.

  As described above, by attaching the expansion turbine 55 to the fuel gas return line 50 constituting the gas turbine power generator, the energy of the fuel gas can be efficiently recovered. In addition, by installing the expansion turbine 55 and adiabatic expansion of the fuel gas, the temperature of the fuel gas can be reduced more than that of the conventional gas turbine power generator, so that the thermal load of the gas cooler 65 can be reduced. It is possible and energy can be used effectively. In the first embodiment, an example of a gas turbine combined power generation system has been described. Needless to say, a gas turbine power generation apparatus may be used.

  FIG. 2 is a diagram showing a schematic configuration of a gas turbine combined power generation system 200 as a second embodiment of the present invention. The same members and portions as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly to the gas turbine combined power generation system 30 shown in the first embodiment, the gas turbine combined power generation system 200 also has a fuel gas return line through which a part of the fuel gas of the fuel gas compressor is circulated by the gas turbine power generation apparatus. And having an energy recovery device for recovering energy from the fuel gas flowing through the fuel gas return line.

  In the second embodiment, a feed water heater 210 is used as a device for recovering energy from the fuel gas return line 50. Comparing the first embodiment with the present embodiment, the expansion turbine 55 and the generator 60 in the first embodiment are schematically changed to the feed water heater 210. The feed water heater 210 is a partition wall type heat exchanger, and exchanges heat between the high-temperature and high-pressure fuel gas flowing through the fuel gas return line 50 and the feed water of the exhaust heat recovery boiler 100 with a solid wall interposed therebetween. Thus, heat recovery is performed from the high-temperature, high-pressure fuel gas flowing through the fuel gas return line 50.

  A branch pipe 230 is provided in the conduit 220 at the outlet of the condensate pump, and a feed water heater inlet valve 231 is disposed in the branch pipe 230. A pipe line 232 having one end connected to the feed water heater 210 is disposed at the outlet of the feed water heater inlet valve 231. On the other hand, a pipe 233 is disposed at the outlet of the feed water heater 210, and a feed water heater outlet valve 234 is connected to the outlet of the pipe 233. Further, the feed water heater outlet valve 234 is connected to the pipe line 235, and the pipe line 235 is connected to the pipe line 221 at one end.

  The pipe line 240 and the pipe line 241 are connected via a bypass valve 242. Normally, the bypass valve 242 is closed, and the water supply is led to the water heater 210 through the pipes 230 and 232 and heated. The feed water whose temperature has been increased is guided to the pipeline 221 through the pipelines 233 and 235, and is sent to the low-pressure economizer 101 by the low-pressure feed pump 110.

  Thereby, the feed water temperature of the exhaust heat recovery boiler 100 increases, and the heat load of the low-pressure economizer 101 can be reduced. In order to prevent corrosion of the low pressure economizer 101, the low pressure economizer 101 is provided with a economizer circulation line 120, and a part of the feed water preheated by the low pressure economizer 101 and having a high temperature is provided. The circulation through the economizer circulation pump 121 is as described in the first embodiment.

  By circulating a part of the hot water supply water, the temperature of the water supply is raised above the dew point of the sulfurous acid gas in the combustion gas that heats the low pressure economizer 101. By adopting such a configuration, corrosion of the low-pressure economizer 101 is prevented. When the feed water temperature to the low pressure economizer 101 is increased as in the second embodiment, the circulation amount of the economizer circulation line 120 can be reduced. Since the economizer circulation line 120 is circulated by the economizer circulation pump 121, the power of the economizer circulation pump 121 or the number of operating units can be reduced by adopting the second embodiment. Can do. Moreover, by raising the feed water temperature to the low-pressure economizer 101, the amount of steam generated in the exhaust heat recovery boiler increases, and the amount of power generation can be increased.

  On the other hand, the fuel gas from which heat has been removed by the feed water heater 210 and its temperature has been lowered is led to the gas cooler 65 through the conduit 57 and cooled, as in the first embodiment. Since the feed water heater 210 sufficiently reduces the temperature of the fuel gas through heat exchange with the feed water, the heat load of the gas cooler 65 can be reduced as in the first embodiment. Thereby, compared with the conventional gas turbine combined power generation system, the power of the seawater pump 98 and the intake pump 96 or the number of operation can be reduced. The feed water heater 210 is not particularly limited as long as it is a partition wall type heat exchanger capable of performing gas-liquid heat exchange. For example, a multi-tube heat exchanger may be used. it can.

An example of a calculation result obtained by applying energy that can be recovered by the feed water heater to the gas turbine combined power generation system 200 is shown. The discharge gas (fuel gas) amount of the fuel gas compressor was about 300,000 m ³ N / h, and the gas return (gas circulation) amount was about 16,000 m ³ N / h. This value is the throughput of the fuel gas compressor currently used by the Company. As the physical property values, the physical property values used in the formula (1) were used. Conventionally, the inlet water temperature of the condensate pump 135 is 20 to 40 ° C., whereas the outlet water temperature of the low pressure feed water pump 110 is 40 to 65 ° C., which is about 20 ° C. On the other hand, in the gas turbine combined power generation system 200 of the second embodiment, the inlet temperature of the condensate pump 135 is 20 to 40 ° C., and the feed water temperature at the outlet of the low pressure feed water pump 110 is 48 to 48 ° C. The temperature rises to 73 ° C and about 30 ° C.

  In the second embodiment, since the energy of the fuel gas is recovered by the feed water heater 210, it is desirable that the enthalpy of the fuel gas at the inlet of the feed water heater 210 is high. Therefore, it is necessary to select a valve type or the like so that the enthalpy of the fuel gas does not decrease as much as possible by the first gas return amount control valve 53 or the like. As described above, since the gas turbine combined power generation system 200 includes the feed water heater 210, the energy of the fuel gas flowing through the fuel gas return line 50 can be effectively recovered and used.

  FIG. 3 is a diagram showing a schematic configuration of a gas turbine combined power generation system 300 as a third embodiment of the present invention. The same members and portions as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted. Similarly to the gas turbine combined power generation system 30 shown in the first embodiment, the gas turbine combined power generation system 300 also has a fuel gas return line for circulating a part of the fuel gas of the fuel gas compressor. And having an energy recovery device for recovering energy from the fuel gas flowing through the fuel gas return line.

  In the third embodiment, a heat pipe 310 is used as a device for recovering energy from the fuel gas return line 50. The fuel gas return line 50 includes a circulating gas cooler 320 that applies heat to the evaporation part of the heat pipe. The high-temperature, high-pressure fuel gas flowing through the fuel gas return line 50 evaporates the working fluid in the heat pipe 310 and cools this vapor with the feed water of the exhaust heat recovery boiler 100. Thereby, the energy which fuel gas has can be collect | recovered in the form which raises the feed water temperature of the exhaust heat recovery boiler 100. FIG.

  The heat pipe 310 brings the evaporation unit 311 into contact with the circulating gas cooler 320 provided in the pipe 56 of the fuel gas return line 50, and the condensation unit 312 is provided in the feed water heater 210 provided at the outlet of the condensate pump 135. It is arrange | positioned so that it may contact. Due to the heat received from the circulating gas cooler 320, the evaporation section 311 of the heat pipe 310 is heated, and the working fluid in the heat pipe 310 is evaporated. The steam moves in the metal pipe 313 constituting the heat pipe and releases heat into a liquid by the feed water heater 210 provided at the outlet of the condensate pump 135. The working fluid that has become liquid moves in the metal pipe 313, returns to the evaporation unit 311, and is heated again. By repeating the above operation, the energy of the fuel gas can be recovered effectively. On the other hand, the fuel gas that has been deprived of heat through the circulating gas cooler 320 and has been lowered in temperature is led to the gas cooler 65 through the conduit 57 and cooled, as in the second embodiment.

  Similarly to the second embodiment, the third embodiment also performs heat recovery from the fuel gas in the fuel gas return line and raises the feed water temperature of the exhaust heat recovery boiler 100. This is the same as the embodiment. Further, since the temperature of the fuel gas is sufficiently lowered by giving heat to the evaporation section 311 of the heat pipe 310, the first and second implementations are also possible in that the heat load of the gas cooler 65 can be reduced. It is the same as the form. Thereby, compared with the conventional gas turbine combined power generation system, the power of the seawater pump 98 and the intake pump 96 or the number of operation can be reduced. Further, the third embodiment has an advantage that it can be applied even when the distance between the pipes 56 and 57 of the fuel gas return line 50 and the feed water heater 210 is long.

  In the third embodiment, the heat transfer between the circulating gas cooler 320 and the feed water heater 210 is performed using the heat pipe 310, but instead of the heat pipe 310, the circulating gas cooler 320 and the feed water heating are performed. Heat recovery can also be performed by providing a circulation line connecting the vessels 210 and circulating the fluid in the circulation line with a circulation pump.

  FIG. 4 is a diagram showing a schematic configuration of a gas turbine combined power generation system 400 as a fourth embodiment of the present invention. The same members and portions as those in FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted. In the gas turbine combined power generation system 400, similarly to the gas turbine combined power generation systems shown in the first to third embodiments, the gas turbine power generation apparatus returns the fuel gas that circulates a part of the fuel gas of the fuel gas compressor. It is characterized by having an energy recovery device that includes a line and recovers energy from the fuel gas flowing through the fuel gas return line.

  In the fourth embodiment, an apparatus for recovering energy from the fuel gas return line 50 includes an expansion turbine 55 and a generator 60 connected to the expansion turbine 55 as in the first embodiment. Furthermore, in the fourth embodiment, steam including a fuel gas cooling cooler 418 for cooling the intake gas of the fuel gas compressor 32 and a feed water heater 210 for raising the feed water temperature of the exhaust heat recovery boiler 100 is configured. It is characterized in that a compression refrigeration apparatus 410 is provided.

  The vapor compression refrigeration apparatus 410 includes a refrigerant compressor 411 for compressing the refrigerant. The refrigerant whose pressure and temperature are increased by being compressed by the refrigerant compressor 411 is sent to the feed water heater 210 through the pipe line 412. The feed water heater 210 increases the temperature of the feed water of the exhaust heat recovery boiler 100 as shown in the second and third embodiments. On the other hand, the feed water heater 210 also functions as a condenser that cools and condenses the refrigerant sent through the pipe 412.

  The refrigerant condensed in the feed water heater 210 is sent to the liquid receiver 414 through the pipe line 413. The refrigerant is gas-liquid separated by the liquid receiver 414, and the liquefied refrigerant is guided to the expansion valve 416 through the pipe line 415. The expansion valve 416 decompresses the liquefied refrigerant in an enthalpy manner. The refrigerant becomes wet steam with the temperature lowered thereby. The refrigerant that has become wet steam is guided through a conduit 417 to a fuel gas cooling cooler 418 for cooling the intake gas of the fuel gas compressor 32. The fuel gas is deprived of heat by the wet steam via the fuel gas cooling cooler 418 and decreases in temperature. On the other hand, the wet steam receives heat from the fuel gas via the fuel gas cooling cooler 418 and becomes saturated steam. Therefore, the fuel gas cooling cooler 418 functions as a cooler that lowers the temperature of the fuel gas, while functioning as an evaporator that converts the wet steam of the refrigerant into saturated steam.

  The refrigerant that has received heat at the fuel gas cooling cooler 418 and has become saturated vapor is sent to the refrigerant compressor 411 through the pipe 419. The vapor compression refrigeration apparatus 410 is generally configured as described above. The driving source of the refrigerant compressor 411 is an expansion turbine 55 provided in the fuel gas return line 50, and the rotation of the expansion turbine is received through the fluid coupling 420 and driven.

  Energy recovery by the vapor compression refrigeration apparatus 410 can be performed as follows. In a period of high outside air temperature such as summer, the temperature of the intake gas of the fuel gas compressor 32 inevitably increases. When the temperature of the intake gas increases, the gas density decreases and the compression efficiency of the fuel gas compressor 32 decreases. According to the present embodiment, the temperature of the intake gas can be lowered by the fuel gas cooling cooler 418 constituting the vapor compression refrigeration apparatus 410, so that the gas density of the fuel gas increases, and the fuel gas compressor The compression efficiency of 32 can be increased. As a result, the driving power of the fuel gas compressor 32 is reduced (the amount of combustion gas as the gas turbine working fluid is increased), and as a result, the amount of power generated by the generator 41 is increased.

  Furthermore, the vapor compression refrigeration apparatus 410 can increase the feed water temperature of the exhaust heat recovery boiler 100 by the feed water heater 210 that constitutes the vapor compression refrigeration apparatus 410. The effect of increasing the feed water temperature of the exhaust heat recovery boiler 100 is as described in the second and third embodiments. Further, since the expansion turbine 55 can expand the fuel gas to a lower temperature than the conventional gas turbine combined power generation system, the thermal load of the gas cooler 65 can be reduced. The effects accompanying this are as shown in the first embodiment.

  In the fourth embodiment, the expansion turbine 55 is connected to the generator 60 and is connected to the refrigerant compressor 411 via the fluid coupling 420. Therefore, the power generation in the generator 60 and the vapor compression refrigeration apparatus Energy recovery by 410 can be selected. When power is generated by the generator 60, the refrigerant compressor 411 is disconnected, and when energy recovery is performed by the vapor compression refrigeration apparatus 410, the generator 60 is disconnected. If necessary, the generator 60 and the vapor compression refrigeration apparatus 410 can be operated at the same time. In the fourth embodiment, although the generator 60 is connected to the expansion turbine 55, it is needless to say that the generator 60 may be provided and only the vapor compression refrigeration apparatus 410 may be provided.

  FIG. 5 is a diagram showing a schematic configuration of a gas turbine combined power generation system 500 as a fifth embodiment of the present invention. The same members and portions as those in FIGS. 1 to 4 are denoted by the same reference numerals, and detailed description thereof is omitted. In the gas turbine combined power generation system 500 as well, as in the gas turbine combined power generation systems shown in the first to fourth embodiments, the gas turbine power generation apparatus returns the fuel gas that circulates a part of the fuel gas of the fuel gas compressor. It is characterized by having an energy recovery device that includes a line and recovers energy from the fuel gas flowing through the fuel gas return line.

  The fifth embodiment employs a configuration similar to that of the fourth embodiment. As an apparatus for recovering energy from the fuel gas return line 50, an expansion turbine 55 and a generator 60 connected to the expansion turbine 55 are provided as in the fourth embodiment. Further, similarly to the fourth embodiment, a vapor compression refrigeration apparatus 510 including a cooler for cooling the intake gas and a feed water heater for raising the feed water temperature of the exhaust heat recovery boiler 100 is provided.

  The basic configuration of the fifth embodiment is the same as that of the fourth embodiment, and the difference is in the installation location of the cooler (cooler 421 for air cooling) constituting the vapor compression refrigeration apparatus 510. In the fourth embodiment, the configuration for cooling the intake gas of the fuel gas compressor 32 is adopted. However, in the fifth embodiment, the configuration for cooling the intake air of the air compressor 37 is adopted. As a result, the density of the intake air increases and the compression efficiency of the air compressor 37 increases. As a result, the driving power of the air compressor 37 is reduced (the amount of combustion gas as the gas turbine working fluid is increased), and as a result, the amount of power generated by the generator 41 is increased. The effect of increasing the feed water temperature of the exhaust heat recovery boiler 100 is as shown in the second to fourth embodiments.

  Furthermore, since the expansion turbine 55 can expand the fuel gas to a lower temperature than the conventional gas turbine combined power generation system, the thermal load of the gas cooler 65 can be reduced. The effects accompanying this are as shown in the first and fourth embodiments. Further, the point that energy recovery by the generator 60 and the vapor compression refrigeration apparatus 510 can be selected is the same as that of the fourth embodiment.

  FIG. 6 is a diagram showing a schematic configuration of a gas turbine combined power generation system 600 as a sixth embodiment of the present invention. The same members and portions as those in FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof is omitted. In the gas turbine combined power generation system 600, as in the gas turbine combined power generation systems shown in the first to fifth embodiments, the gas turbine power generation apparatus returns the fuel gas that circulates a part of the fuel gas of the fuel gas compressor. It is characterized by having an energy recovery device that includes a line and recovers energy from the fuel gas flowing through the fuel gas return line.

  The sixth embodiment employs a configuration similar to the fourth and fifth embodiments. As an apparatus for recovering energy from the fuel gas return line 50, as in the fourth and fifth embodiments, an expansion turbine 55 and a generator 60 connected to the expansion turbine 55 are included. Further, similarly to the fourth and fifth embodiments, a vapor compression refrigeration apparatus 610 including a cooler for cooling the intake gas and a feed water heater for raising the feed water temperature of the exhaust heat recovery boiler 100 is provided.

  The difference between the sixth embodiment and the fourth and fifth embodiments resides in the coolers 418 and 421 constituting the vapor compression refrigeration apparatus 610. In the fourth embodiment, a fuel gas cooling cooler 418 is provided in the middle of the pipeline 31 in order to cool the intake gas of the fuel gas compressor 32. On the other hand, in the fifth embodiment, an air cooling cooler 421 is provided in the middle of the pipe line 38 in order to cool the intake gas of the air compressor 37.

  In contrast, in the sixth embodiment, a fuel gas cooling cooler 418 for cooling the intake gas of the fuel gas compressor 32 and an air cooling cooler 421 for cooling the intake air of the air compressor 37. With both. A pipe line 417 connected to the outlet of the expansion valve 416 has a branch portion and is connected to the pipe line 422 and the pipe line 423. The pipe line 422 is provided with a fuel gas cooling cooler inlet valve 424 at one end, and the fuel gas cooling cooler inlet valve 424 sends the refrigerant to the fuel gas cooling cooler 418 through a pipe line 425 connected thereto.

  The refrigerant that has received heat at the fuel gas cooling cooler 418 and has become saturated vapor is transported through the fuel gas cooling cooler outlet valve 426 and the pipe 427 and then returned to the refrigerant compressor 411 through the pipe 419. The air cooling cooler 421 also receives the refrigerant through the air cooling cooler inlet valve 428 connected to one end of the pipe 423 and the pipe 429 connected to the air cooling cooler inlet valve 428. The refrigerant that has received heat at the air cooling cooler 421 and becomes saturated vapor is transported through the air cooling cooler outlet valve 430 and the pipe line 431 and then returned to the refrigerant compressor 411 through the pipe line 419.

  In the sixth embodiment, the intake gas cooler includes a fuel gas cooling cooler 418 that cools the intake gas of the fuel gas compressor 32, and an air cooling cooler 421 that cools the intake air of the air compressor 37, respectively. Since the inlet valves 424 and 428 and the outlet valves 426 and 430 are provided, the fuel gas cooling cooler 418 and the air cooling cooler 421 can be selectively used. Furthermore, the fuel gas cooling cooler 418 and the air cooling cooler 421 can be used simultaneously as necessary.

  Further, the sixth embodiment also includes a feed water heater 210 for increasing the feed water temperature of the exhaust heat recovery boiler 100 as in the fourth and fifth embodiments. The advantages of lowering the intake gas temperature, the advantages of increasing the feed water temperature of the exhaust heat recovery boiler 100 with the feed water heater 210, and the advantage of reducing the heat load of the gas cooler 65 are the fourth and the fourth. This is as shown in the fifth embodiment.

  In a gas turbine power generation system and a gas turbine combined power generation system including a fuel gas return line that circulates part of the fuel gas of the fuel gas compressor, the fuel gas return line is an essential component on the power generation system. If the return line does not function properly, the power generation system cannot be operated normally and stably. Therefore, an energy recovery device that recovers energy from the fuel gas flowing through the fuel gas return line must recover the energy of the fuel gas without impairing the function of the fuel gas return line.

  For example, even a device capable of efficiently recovering energy should not increase the pressure loss of the fuel gas return line more than necessary or reduce the circulation flow rate of the fuel gas. In this regard, the energy recovery device of the present invention can recover energy without impairing the function of the fuel gas return line. The present invention is not limited to the first to sixth embodiments, and can naturally be used as long as it is an apparatus and method that can recover energy without impairing the function of the fuel gas return line. is there.

  Moreover, as shown in the first to sixth embodiments, the process flow of the gas turbine combined power generation system of the present invention is similar to the process flow of the existing gas turbine power generation apparatus or the gas turbine combined power generation system. For this reason, it can be easily applied to existing gas turbine power generation devices or gas turbine combined power generation systems.

30, 200, 300 Gas turbine combined power generation system 400, 500, 600 Gas turbine combined power generation system 32 Fuel gas compressor 35 Combustor 37 Air compressor 40 Gas turbine 41, 60 Generator 50 Fuel gas return line 53 Gas return amount control Valve 55 Expansion turbine 65 Gas cooler 90 Gas cooler cooling water pump 98 Chimney 100 Waste heat recovery boiler 101 Low-pressure economizer 121 Eco-circulator circulation pump 131 Steam turbine 133 Condenser 210 Feed water heater 310 Heat pipes 410 and 510 , 610 Vapor compression refrigeration system 411 Refrigerant compressor 418 Fuel gas cooling cooler 421 Air cooling cooler

Claims (3)

A fuel gas return line capable of circulating a part of the fuel gas, a fuel gas compressor for compressing the fuel gas while circulating a part of the fuel gas, a combustor for burning the fuel gas, and compressed air in the combustor A gas turbine power generator configured to include an air compressor;
In a gas turbine combined power generation system comprising a steam power generation device including an exhaust heat recovery boiler and a steam turbine,
A feed water heating means for increasing the feed water temperature of the exhaust heat recovery boiler using the fuel gas compressed in the fuel gas compressor and having a high temperature and a high pressure flowing through the fuel gas return line is provided. Gas turbine combined power generation system. The exhaust heat recovery boiler includes a economizer.
The feed water heating means is a heat exchanger for exchanging heat between the fuel gas flowing through the fuel gas return line and the feed water of the exhaust heat recovery boiler, and the feed water temperature of the exhaust heat recovery boiler using the heat exchanger 2. The gas turbine combined power generation system according to claim 1, wherein the feed water is sent to the economizer after the temperature is raised. The exhaust heat recovery boiler includes a economizer.
The feed water heating means is a heat pipe, recovers heat from the fuel gas flowing through the fuel gas return line using the heat pipe, and raises the feed water temperature of the exhaust heat recovery boiler using the recovered heat The gas turbine combined power generation system according to claim 1, wherein the water supply is sent to the economizer.

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