JP5822487B2 - Gas turbine plant and control method thereof - Google Patents

Description

  The present invention relates to a gas turbine plant and a control method thereof, and more particularly to heating of fuel supplied to a gas turbine.

  In general, in a gas turbine combined plant, air is compressed by an air compressor, sent to a combustor provided in the gas turbine, and fuel gas supplied into the combustor is combusted. The high-temperature and high-pressure combustion gas generated in the combustor is expanded in the gas turbine, thereby driving the gas turbine to drive the gas turbine generator. Thereby, the generator for gas turbines will generate electric power.

  Further, the exhaust gas discharged from the gas turbine is guided to an exhaust heat recovery boiler (HRSG), and steam is generated in the exhaust heat recovery boiler using the exhaust heat (about 600 ° C.). Steam generated in the exhaust heat recovery boiler is guided to a steam turbine to drive the steam turbine to generate power for the steam turbine generator.

  The steam that has driven the steam turbine is discharged from the steam turbine and guided to the condenser. The steam guided to the condenser is cooled and condensed by cooling water such as seawater. The condensed steam is converted into condensate and led to the water supply system of the exhaust heat recovery boiler.

  In such a gas turbine combined plant, the air used for cooling the turbine rotor of the gas turbine (hereinafter referred to as “GT rotor cooling air”) is a high temperature (for example, about 440 ° C.) compressed by an air compressor. ) Air is used. When a part of this compressed air is exchanged with the atmosphere by an air cooler, the heat of the compressed air is released as it is outside the system. Therefore, an air cooling and fuel heater that performs heat recovery for heating the fuel gas led to the combustor of the gas turbine using the heat released to the outside of the system is provided.

  This air cooling and fuel heater is provided with a fan that feeds air into the air cooling and fuel heater below the outside (for example, Patent Document 1). Therefore, the GT rotor cooling air of about 440 ° C. led from the air compressor to the air cooling / fuel heater is approximately exchanged with the air blown by the fan provided in the air cooling / fuel heater. Cool to 200 ° C. The GT rotor cooling air cooled to about 200 ° C. is guided to the gas turbine to cool the turbine rotor and the like, thereby preventing the turbine from being damaged.

  On the other hand, the temperature of the air that exchanges heat with the GT rotor cooling air in the air cooling and fuel heater is about 220 ° C. The atmosphere at about 220 ° C. exchanges heat with the fuel gas introduced to the air cooling / fuel heater. The fuel gas exchanged with the atmosphere at about 220 ° C. in the air cooling and fuel heater is heated to about 200 ° C.

  Patent Document 2 and Patent Document 3 include a fuel gas having a temperature of about 200 ° C. after passing through an air cooling and fuel heater, and a steam having a temperature of about 260 ° C. derived from an exhaust heat recovery boiler. It is disclosed to improve the thermal efficiency of a gas turbine combined plant by providing a fuel gas heat exchanger for heat exchange, and further heating the fuel gas to about 240 ° C. and guiding it to the combustor of the gas turbine. Yes.

Japanese Patent Application Laid-Open No. 8-284891 Japanese Patent Laid-Open No. 11-117712 Japanese Patent Laid-Open No. 11-117714

  However, the invention described in Patent Document 1 performs heat recovery of air guided from the air compressor by exchanging heat between the air blown by the fan, the GT rotor cooling air, and the fuel gas. There was a problem of causing loss.

  In the inventions described in Patent Document 2 and Patent Document 3, the fuel gas is heated by using an air cooling and fuel heater and a fuel gas heat exchanger, but the temperature that can be raised is at most two hundred. It is about several tens of degrees Celsius. Therefore, in order to improve the thermal efficiency of the gas turbine plant, it is preferable to heat the fuel to a higher temperature. However, the conventional technique has a problem that it is difficult to heat the fuel to a high temperature that can sufficiently contribute to the improvement of the thermal efficiency of the gas turbine combined plant.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a gas turbine plant capable of heating fuel to a high temperature that can sufficiently contribute to an increase in thermal efficiency, and a control method thereof. To do.

In order to solve the above problems, the gas turbine plant and the control method of the present invention employ the following means.
That is, according to the gas turbine plant according to the present invention, the combustor that combusts the fuel, the turbine that is rotationally driven by the combustion gas derived from the combustor, and the rotational drive of the turbine that is rotationally driven. A compressor that compresses air; a heat recovery steam generator that generates heat compressed water and steam by exchanging heat with the exhaust gas derived from the gas turbine; and the heat recovery steam generator that is derived from the heat recovery steam generator The first heat exchange means for exchanging heat between the heated compressed water and the fuel guided to the combustor, the fuel derived from the first heat exchange means, and the compressed air compressed by the compressor are directly comprising a second heat exchange means for heat exchange, and deriving a temperature of the compressed air is reduced by direct heat exchange with the fuel derived from the first heat exchange means from said heat recovery steam generator Further characterized Rukoto reduced by the heated compressed water.

In the present invention, first, heat-compressed water led out from the exhaust heat recovery boiler and fuel guided to the combustor of the gas turbine are heat-exchanged by the first heat exchange means. Next, the air compressed by the compressor and the fuel heated by the first heat exchange means are heat-exchanged by the second heat exchange means.
In the first heat exchanging means, the fuel is heat exchanged with the heated compressed water. As a result, the fuel is heated from room temperature to, for example, over 200 ° C. On the other hand, in the second heat exchanging means, heat of the fuel heated to slightly above 200 ° C. is exchanged by the air compressed by the compressor. Here, the air compressed by the compressor can use the high temperature of about 440 degreeC, for example. In other words, for example, the fuel heated up to about 200 ° C. or higher is heat-exchanged with compressed air having a high temperature of about 440 ° C., so that it can sufficiently contribute to the improvement of thermal efficiency (in the case of methane fuel, for example, 400 ° C.) The fuel can be heated to the combustor. Therefore, it is possible to improve the thermal efficiency of the gas turbine plant.

In order to improve the thermal efficiency of the gas turbine plant, it is preferable to heat the fuel to a higher temperature as described above. However, if the temperature of the fuel is higher than the self-ignition temperature, there is a risk of self-ignition. For example, in the case of methane-based fuel, the temperature is 445 ° C. (12 kg / cm ² (G) or more) or higher.

  Therefore, according to the gas turbine plant of the present invention, the second heat exchange means includes temperature control means for controlling the derived fuel to be held at a predetermined constant temperature lower than the self-ignition temperature of the fuel. It is characterized by providing.

  The temperature control means for controlling the fuel derived from the second heat exchange means to be held at a predetermined constant temperature lower than the self-ignition temperature of the fuel (for example, 400 ° C. in the case of methane-based fuel). It was decided to provide the means. Thereby, there is no possibility that the fuel self-ignites, and the safety of the gas turbine plant can be ensured.

  Furthermore, according to the gas turbine plant of the present invention, the temperature control means includes a temperature detector that detects the temperature of the derived fuel, and the second heat exchange means based on an output signal of the temperature detector. A flow rate adjusting means for adjusting the flow rate of the guided fuel and a bypass means for bypassing the fuel guided to the second heat exchanging means are provided.

  A temperature detector for detecting the temperature of the fuel derived from the second heat exchange means, a flow rate adjusting means for adjusting the flow rate of the fuel guided to the second heat exchange means based on the output signal of the temperature detector, and a second The temperature control means including the bypass means for bypassing the fuel guided to the heat exchange means is used. Therefore, when the temperature of the fuel detected by the temperature detector is lower than the predetermined temperature, the flow rate of the fuel guided to the second heat exchange means by the flow rate adjusting means is increased, and the temperature of the fuel detected by the temperature detector is increased. Is higher than a predetermined temperature, the fuel guided to the second heat exchange means can be bypassed by the bypass means. Therefore, the temperature of the fuel guided to the combustor can be kept at a predetermined temperature.

Furthermore, according to the control method for a gas turbine plant according to the present invention, a combustor that combusts fuel, a turbine that is rotationally driven by the combustion gas derived from the combustor, and the turbine that rotates when the turbine is rotationally driven. And a compressor for driving and compressing air, wherein the fuel guided to the combustor is derived from the exhaust heat recovery boiler by exchanging heat with the exhaust gas derived from the turbine. After heat exchange with the heated compressed water and the first heat exchange means, the air compressed by the compressor and the second heat exchange means are directly heat exchanged and heated to a predetermined temperature, and from the first heat exchange means wherein Rukoto further reduced by heating the compressed water that has been derived the temperature of the compressed air is reduced from the exhaust heat recovery boiler by direct heat exchange with the derived fuel To.

  Fuel is directed to the combustor as follows. First, the first heat exchange means exchanges heat between the exhaust gas derived from the turbine and the heated compressed water generated by the exhaust heat recovery boiler. Next, the fuel derived from the first heat exchange means and the air compressed by the compressor are heat exchanged by the second heat exchange means. Therefore, the fuel guided to the combustor can be heated to a high temperature that can sufficiently contribute to an increase in thermal efficiency. Therefore, it is possible to improve the thermal efficiency of the gas turbine plant.

  According to the present invention, a gas turbine plant capable of heating a fuel to a high temperature that can sufficiently contribute to an increase in thermal efficiency and a control method thereof are provided.

It is a whole lineblock diagram of a gas turbine combined plant provided with a direct heat exchanger concerning one embodiment of the present invention. It is a longitudinal cross-section block diagram of the direct heat exchanger shown in FIG. FIG. 3 is a layout view of the direct heat exchanger shown in FIG. 2, (A) shows the case of the present embodiment, and (B) and (C) are modified examples thereof.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3. In the following description, “G” is used as the symbol for the fuel gas. However, when it is necessary to distinguish the fuel gas depending on the passage route or the temperature state, the number “1” is added to the end of “G”, and “G1”. Write “G2” and “G3”.
As shown in FIG. 1, a gas turbine combined plant (gas turbine plant) 1 according to this embodiment includes a gas turbine 2, a steam turbine 3, an exhaust heat recovery boiler 4, a condenser 5, and direct heat exchange. A heater (second heat exchanging means) 6, a fuel heater (first heat exchanging means) 7, and an air cooler (hereinafter referred to as “TCA cooler”) 8.

  The gas turbine 2 includes a combustor 9 that combusts fuel gas (fuel) G, a turbine 10 that is rotationally driven by the combustion gas derived from the combustor 9, and rotationally driven by the turbine 10 being rotationally driven. And an air compressor (compressor) 11 that compresses the gas and a gas turbine generator 13 that generates power when the turbine 10 is rotationally driven.

The combustor 9 burns an air-fuel mixture of the air A1 compressed by the air compressor 11 and the fuel gas G supplied from the outside. The high-temperature and high-pressure combustion gas generated by the combustion is supplied to the turbine 10.
The combustion gas derived from the combustor 9 is expanded in the turbine 10, whereby the turbine 10 is driven to rotate. A gas turbine rotating shaft 12 is connected to the turbine 10.

  The gas turbine rotating shaft 12 is a cylindrical member connected to the turbine 10, the air compressor 11, and the gas turbine generator 13, and the rotational driving force generated in the turbine 10 is transmitted to the air compressor 11. This is transmitted to the gas turbine generator 13.

  The air compressor 11 sucks and compresses the atmosphere. A part of the air A1 compressed by the air compressor 11 is led to the direct heat exchanger 6 described later, and the rest is supplied to the combustor 9. A gas turbine rotating shaft 12 is connected to the air compressor 11 and is compressed by being driven by the gas turbine rotating shaft 12.

  As shown in FIG. 1, the steam turbine 3 includes a high-medium pressure turbine 15, a low-pressure turbine 16, and a steam turbine generator 14, and uses superheated steam V (details will be described later) led from the exhaust heat recovery boiler 4. Driven.

  The high and medium pressure turbine 15, the low pressure turbine 16, and the steam turbine generator 14 are connected by a steam turbine rotating shaft 17 that is a cylindrical member. The steam turbine rotating shaft 17 drives the steam turbine generator 14 when the high and medium pressure turbine 15 and the low pressure turbine 16 are rotationally driven by the superheated steam V.

  The exhaust heat recovery boiler 4 exchanges heat between the exhaust gas EG derived from the gas turbine 2 and the feed water RW that has been pressurized by the feed water pump 5a from the condenser 5 and led to the heated compressed water W (WI , WL) and superheated steam V (VL, VI, VH) from the heated compressed water W. The superheated steam V (VL, VI, VH) generated here is used as a drive medium for the steam turbine 3. The heated compressed water WI is used as a heat medium in the fuel heater 7. The heated compressed water WL is used as a refrigerant in the TCA cooler 8.

  The exhaust heat recovery boiler 4 includes a high pressure heat exchange system 4a, an intermediate pressure heat exchange system 4b, and a low pressure heat exchange system 4c. Although these three heat exchange systems 4a, 4b, and 4c are not shown, they each include a economizer, an evaporator, and a superheater.

  The economizer has a function of generating heated compressed water W (WI, WL) by heating the feed water RW that is pressurized and guided from the condenser 5 by the feed water pump 5a. The evaporator has a function of evaporating the heated compressed water W obtained by the economizer. The superheater has a function of superheating steam generated by the evaporator to generate superheated steam V (VL, VI, VH).

  The feed water RW guided from the condenser 5 to the low-pressure heat exchange system 4c is converted from the low-pressure heat exchange system 4c into the superheated steam VL and the heated compressed water WL by exchanging heat with the exhaust gas EG. The superheated steam VL derived from the low pressure heat exchange system 4 c is guided to the low pressure turbine 16. Part of the heated compressed water WL derived from the low-pressure heat exchange system 4c is led to the TCA cooler 8, and the rest is led to the medium-pressure heat exchange system 4b and the high-pressure heat exchange system 4a.

  The heated compressed water WL guided to the intermediate pressure heat exchange system 4b and the high pressure heat exchange system 4a is subjected to heat exchange with the exhaust gas EG in the intermediate pressure heat exchange system 4b and the high pressure heat exchange system 4a, and the superheated steam VI, VH Is done. The superheated steam VI and VH derived from the intermediate pressure heat exchange system 4 b and the high pressure heat exchange system 4 a are guided to the high and intermediate pressure turbine 15. In addition, the heated compressed water WI derived from the intermediate pressure heat exchange system 4 b is guided to the fuel heater 7.

  Steam that has rotationally driven the low-pressure turbine 16 of the steam turbine 3 is guided to the condenser 5. The steam guided to the condenser 5 is cooled and condensed by cooling water such as seawater. The condensed steam becomes condensate and is led out from the condenser 5, and then pressurized by the feed water pump 5 a and led to the feed water system of the exhaust heat recovery boiler 4.

  The fuel heater 7 exchanges heat between the fuel gas G1 guided from the fuel supply system and the heated compressed water WI at about 250 ° C. derived from the intermediate pressure heat exchange system 4b of the exhaust heat recovery boiler 4. . The fuel gas G <b> 2 whose temperature has increased to about 220 ° C. through heat exchange with the heated compressed water WI in the fuel heater 7 is directly led to the heat exchanger 6.

  In the direct heat exchanger 6, the fuel gas G <b> 2 heated to about 220 ° C. by the fuel heater 7 and the compressed air A <b> 1 compressed from the air compressor 11 to about 440 ° C., for example, exchange heat. Is. The fuel gas G3 heat-exchanged with the compressed air A1 in the direct heat exchanger 6 is heated to about 400 ° C., for example. The fuel gas G3 heated to about 400 ° C. is guided to the combustor 9 of the gas turbine 2.

  The TCA cooler 8 exchanges heat between the air A2 directly derived from the heat exchanger 6 and the heated compressed water WL derived from the low-pressure heat exchange system 4c of the exhaust heat recovery boiler 4. The air A3 whose temperature has decreased due to heat exchange in the TCA cooler 8 is guided to the gas turbine 2 to cool the gas turbine rotating shaft 12 and the like.

FIG. 2 shows a longitudinal sectional configuration diagram of the direct heat exchanger 6. Moreover, the example of arrangement | positioning of the some direct heat exchanger 6 is shown by FIG.
The direct heat exchanger 6 is a shell and tube type heat exchanger. Two direct heat exchangers 6 may be provided in a straight line in series as shown in FIG. As shown in FIGS. 3B and 3C, the direct heat exchanger 6 is provided so as to overlap in two stages according to the arrangement position in the gas turbine combined plant 1 or the like. Anyway.

  The direct heat exchanger 6 includes a cylindrical heat exchanger main body 50 and end plates 51 a and 51 b provided at each end of the heat exchanger main body 50. The heat exchanger body 50 has a plurality of air flow channel pipes 52 penetrating therethrough. The plurality of air flow path tubes 52 are the flow paths of the air A1 led directly to the heat exchanger 6, and can exchange heat with the fuel gas G2 flowing on the outer periphery of each air flow path tube 52. Yes.

  The heat exchanger body 50 in the vicinity of the end plate 51a is provided with a fuel gas inlet 50a, and the heat exchanger body 50 in the vicinity of the end plate 51b is provided with a fuel gas outlet 50b. Further, the end plate 51a is provided with an air inlet 51c, and the end plate 51b is provided with an air outlet 51d.

  The air A1 guided from the air inlet 51c into the heat exchanger main body 50 flows in the axial direction of the air flow path pipe 52 through the plurality of air flow path pipes 52 provided in the heat exchanger main body 50. . The air A1 flowing through the air flow path pipe 52 exchanges heat with the fuel gas G2 introduced into the heat exchanger body 50 from the fuel gas inlet 50a.

  The air A1 in the air flow path pipe 52 is led out from the air outlet 51d as the temperature decreases due to heat exchange with the fuel gas G2. On the other hand, the fuel gas G3 heated by exchanging heat between the air A1 and the fuel gas G2 in the air passage pipe 52 is led out from the fuel gas outlet 50b.

  As shown in FIG. 1, the direct heat exchanger 6 has a temperature for controlling the fuel gas G3 derived from the direct heat exchanger 6 so as to be maintained at a predetermined constant temperature lower than the self-ignition temperature of the fuel gas G. A control device (temperature control means) 22 is provided. The temperature control device 22 is based on a direct heat exchanger temperature sensor (temperature detector) 24 for detecting the temperature of the fuel gas G3 derived from the direct heat exchanger 6 and an output signal of the direct heat exchanger temperature sensor 24. A direct heat exchanger three-way valve (flow rate adjusting means) 23 for adjusting the flow rate of the fuel gas G2 led directly to the heat exchanger 6, and a direct heat exchanger bypass circuit for bypassing the fuel gas G2 led to the direct heat exchanger 6 (Bypass means) 54.

  The direct heat exchanger three-way valve 23 adjusts the distribution of the flow rate of the fuel gas G2 guided to the direct heat exchanger 6 and the direct heat exchanger bypass circuit 54 by the controller 25 so that the fuel gas G3 guided to the combustor 9 is Control is performed so as to maintain the following predetermined temperature.

  The fuel gas G <b> 2 that avoids the passage of the direct heat exchanger 6 is guided to the direct heat exchanger bypass circuit 54. The direct heat exchanger temperature sensor 24 is provided downstream of the junction of the fuel gas G3 that has passed through the direct heat exchanger 6 and the fuel gas G3 that has passed through the direct heat exchanger bypass circuit 54. The temperature of the fuel gas G3 led to is detected.

  The controller 25 maintains the temperature of the fuel gas G3 led to the combustor 9 at a predetermined constant temperature lower than the self-ignition temperature of the fuel gas G based on the temperature detected by the temperature sensor 24 for direct heat exchanger. As described above, the three-way valve 23 for direct heat exchanger is feedback-controlled.

Next, the flow and control method for heating the fuel gas G to a predetermined temperature will be described with reference to FIG.
The fuel gas G1 (for example, about 15 ° C.) guided from the fuel supply system and the heated compressed water WI (for example, about 250 ° C.) guided from the intermediate pressure heat exchange system 4b of the exhaust heat recovery boiler 4 in the fuel heater 7 Exchange heat. By exchanging heat with the heated compressed water WI at about 250 ° C. in the fuel heater 7, the fuel gas G 1 becomes the fuel gas G 2 whose temperature has increased to about 220 ° C.

  Here, the flow rate of the fuel gas G1 led from the fuel supply system to the fuel heater 7 is adjusted by the fuel heater three-way valve 21 constituting the fuel heater temperature adjusting means (not shown). The fuel heater three-way valve 21 is led out from the fuel heater 7 in accordance with the temperature of the fuel gas G2 detected by a fuel heater temperature sensor (not shown) provided at the outlet of the fuel heater 7. The flow rate of the fuel gas G1 guided to the fuel heater 7 is adjusted so that the temperature of the fuel gas G2 is maintained at a predetermined constant temperature (for example, about 220 ° C.).

  That is, when the temperature of the fuel gas G2 detected by the fuel heater temperature sensor is lower than a predetermined temperature (for example, about 220 ° C.), the fuel heater three-way valve 21 is adjusted to guide the fuel gas to the fuel heater 7. The flow rate of the fuel gas G1 is increased. Thereby, the temperature of the fuel gas G2 led out from the fuel heater 7 can be set to about 220 ° C.

  Further, when the temperature of the fuel gas G2 detected by the fuel heater temperature sensor is about 220 ° C. or higher, the fuel heater 7 is bypassed by introducing the fuel gas G1 to the fuel heater bypass circuit 53. be able to. In this manner, by bypassing the fuel gas G1 to the fuel heater bypass circuit 53, the fuel gas G2 that is not heated by the fuel heater 7 can be led directly to the heater 6.

  The fuel gas G 2 at about 220 ° C. derived from the fuel heater 7 or the fuel heater bypass circuit 53 is directly led to the heat exchanger 6. The fuel gas G2 led to the direct heat exchanger 6 is heat-exchanged with the compressed air A1 of about 440 ° C., for example, which has been compressed by the air compressor 11 in the direct heat exchanger 6 and has become high temperature. The temperature of the fuel gas G2 exchanging heat with the high-temperature compressed air A1 rises to about 400 ° C., for example. The fuel gas G3 heated to about 400 ° C. is directly led out from the heat exchanger 6 and supplied to the combustor 9 of the gas turbine 2.

  Here, the flow rate of the fuel gas G2 directly guided to the heat exchanger 6 is adjusted by adjusting the opening degree of the direct heat exchanger three-way valve 23 in accordance with a command from the controller 25 constituting the temperature control device 22. Is done. The direct heat exchanger three-way valve 23 is controlled by the controller 25 as follows in accordance with the temperature of the fuel gas G3 detected by the direct heat exchanger temperature sensor 24.

  When the temperature of the fuel gas G3 detected by the direct heat exchanger temperature sensor 24 is lower than about 400 ° C., the flow rate of the fuel gas G2 guided to the direct heat exchanger 6 by adjusting the direct heat exchanger three-way valve 23 is adjusted. Increase. As a result, the temperature of the fuel gas G3 derived directly from the heat exchanger 6 can be set to about 400 ° C.

  Further, when the temperature of the fuel gas G3 detected by the direct heat exchanger temperature sensor 24 is about 400 ° C. or higher, direct heat exchange is performed by directing the fuel gas G2 to the bypass circuit 54 for heat exchanger. The device 6 can be bypassed. Thus, by bypassing the fuel gas G2 to the fuel heater bypass circuit 54, the fuel gas G3 that is not directly heated by the heat exchanger 6 can be guided to the combustor 9.

  By this temperature control device 22, the temperature of the fuel gas G3 guided to the combustor 9 is finely adjusted. Thus, the fuel gas G3 adjusted to about 400 ° C. from the fuel supply system through the fuel heater 7 and the direct heat exchanger 6 is led to the combustor 9 and burned.

As described above, the gas turbine combined plant 1 and the control method according to the present embodiment have the following effects.
First, in the fuel heater (first heat exchange means) 7, the heated compressed water WI derived from the intermediate pressure heat exchange system 4 b of the exhaust heat recovery boiler 4 and the fuel gas ( Fuel) It was decided to exchange heat with G1. Next, the compressed air (air) A1 compressed by the air compressor (compressor) 11 to a temperature of about 440 ° C. and the fuel gas G2 heated by the fuel heater 7 are directly converted into a heat exchanger (second In the heat exchange means 6, heat exchange was performed. The compressed air A1 compressed by the air compressor 11 has a high temperature of about 440 ° C., for example. The fuel G2 that exchanges heat with the high-temperature compressed air A1 has been heated to, for example, about 220 ° C. in advance by heat exchange with the heated compressed water WI. Since the fuel G2 heated to about 220 ° C. is heat-exchanged with the compressed air A1 having a high temperature of about 440 ° C., in the direct heat exchanger 6, the fuel gas G is heated to about 400 ° C. (predetermined temperature). It can be heated and led to the combustor 9. Therefore, the thermal efficiency of the gas turbine combined plant (gas turbine plant) 1 can be improved.

  The direct heat exchanger 6 is provided with a temperature control device (temperature control means) 22 for controlling the fuel gas G3 derived from the direct heat exchanger 6 to be maintained at a predetermined constant temperature lower than the self-ignition temperature of the fuel gas G. We decided to provide it. Therefore, the fuel gas G3 directly guided from the heat exchanger 6 to the combustor 9 can be maintained at a predetermined constant temperature (about 400 ° C.) lower than the self-ignition temperature of the fuel gas G. Therefore, there is no risk of self-ignition, and the safety of the gas turbine combined plant 1 can be ensured.

  A direct heat exchanger temperature sensor (temperature detector) 24 for detecting the temperature of the fuel gas G3 derived from the direct heat exchanger 6 and an output signal of the direct heat exchanger temperature sensor 24 to the direct heat exchanger 6 A direct heat exchanger three-way valve (flow rate adjusting means) 23 for adjusting the flow rate of the guided fuel gas G2, and a direct heat exchanger bypass circuit (bypass means) 54 for bypassing the fuel gas G2 guided to the direct heat exchanger 6. The temperature control device 22 provided with Therefore, when the temperature of the fuel gas G3 detected by the direct heat exchanger temperature sensor 24 is lower than about 400 ° C., the adjustment of the direct heat exchanger three-way valve 23 adjusts the amount of the fuel gas led directly to the heat exchanger 6. The flow rate can be increased. Thereby, the temperature of the fuel gas led out directly from the heat exchanger 6 can be set to about 400 ° C. Further, when the temperature of the fuel gas G3 detected by the direct heat exchanger temperature sensor 24 is about 400 ° C. or higher, direct heat exchange is performed by directing the fuel gas G2 to the bypass circuit 54 for heat exchanger. The device 6 can be bypassed. Therefore, the temperature of the fuel gas G3 guided to the combustor 9 can be finely adjusted.

  The fuel gas G1 guided from the fuel supply system is heat-exchanged with the heated compressed water WI derived by the exhaust heat recovery boiler 4 and the fuel heater 7 and then directly heated with the compressed air A1 compressed by the air compressor 11. Heat was exchanged in the exchanger 6 and led to the combustor 9. The compressed air A1 compressed by the air compressor 11 has a high temperature of about 440 ° C., for example. Therefore, the fuel gas G3 guided to the combustor 9 can be heated to about 400 ° C. by guiding the compressed air A1 directly to the heat exchanger 6 to exchange heat with the fuel gas G2. Therefore, the thermal efficiency of the gas turbine combined plant 1 can be improved.

1 Gas turbine combined plant (gas turbine plant)
2 Gas turbine 4 Waste heat recovery boiler 6 Direct heat exchanger (second heat exchange means)
7 Fuel heater (first heat exchange means)
9 Combustor 10 Turbine 11 Air compressor (compressor)
22 Temperature control device (temperature control means)
23 Three-way valve for direct heat exchanger (flow rate adjusting means)
24 Temperature sensor for direct heat exchanger (temperature detector)
54 Bypass circuit for direct heat exchanger (bypass means)

Claims (5)

A gas turbine comprising: a combustor that combusts fuel; a turbine that is rotationally driven by combustion gas derived from the combustor; and a compressor that rotationally drives and compresses air when the turbine is rotationally driven. ,
An exhaust heat recovery boiler that exchanges heat with the exhaust gas derived from the gas turbine to generate heated compressed water and steam;
First heat exchange means for exchanging heat between the heated compressed water derived from the exhaust heat recovery boiler and the fuel led to the combustor;
A second heat exchange means for directly exchanging heat between the fuel derived from the first heat exchange means and the compressed air compressed by the compressor ;
Further gas turbine Ru lowers the temperature of the compressed air is lowered by heat exchange with the heating compressed water derived from the heat recovery steam by direct heat exchange with the fuel derived from the first heat exchange means plant.   The second heat exchange means includes a cylindrical heat exchanger main body, a pair of end plates provided at each end of the heat exchanger main body, and a plurality of air flows provided inside the heat exchanger main body. A shell-and-tube heat exchanger configured to exchange heat between air flowing in the plurality of air flow path tubes and fuel flowing in the outer periphery of the plurality of air flow path tubes. Item 4. The gas turbine plant according to Item 1.   3. The gas turbine according to claim 1, wherein the second heat exchange unit includes a temperature control unit that controls the derived fuel to be held at a predetermined constant temperature lower than a self-ignition temperature of the fuel. plant.   The temperature control means includes a temperature detector that detects the temperature of the derived fuel, and a flow rate adjustment means that adjusts the flow rate of the fuel guided to the second heat exchange means based on an output signal of the temperature detector; The gas turbine plant according to claim 3, further comprising bypass means for bypassing fuel guided to the second heat exchange means. A gas turbine comprising: a combustor that combusts fuel; a turbine that is rotationally driven by combustion gas derived from the combustor; and a compressor that rotationally drives and compresses air when the turbine is rotationally driven. In the control method,
The fuel guided to the combustor is heat-exchanged with the exhaust gas derived from the turbine, and heat-exchanged with the heated compressed water derived from the exhaust heat recovery boiler and the first heat exchanging means, and then by the compressor. Heat is directly exchanged with the compressed air compressed by the second heat exchange means and heated to a predetermined temperature ,
The method further gas turbine plant Ru reduced by heating the compressed water that has been derived the temperature of the compressed air is reduced from the exhaust heat recovery boiler by direct heat exchange with the fuel derived from the first heat exchange means.

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