JP2007182785A - Gas turbine, method for starting gas turbine and combined-cycle power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit drop of exhaust emission control efficiency and increase of fuel cost by shortening start time in a gas turbine, a method for starting the gas turbine and a combined-cycle power generation system. <P>SOLUTION: The power generation system is constructed to burn high pressure fuel and high pressure air in the gas turbine and generate power by generated combustion gas, and to form steam by sending high temperature exhaust gas discharged from the gas turbine to an exhaust gas boiler 20 and generate power by sending the formed steam to a steam turbine 22. An exhaust gas recirculation line 31 re-circulating at least part of exhaust gas discharged form the turbine 14 to the compressor 12 at a time of start of the gas turbine 11. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a gas turbine that supplies fuel to compressed compressed air and burns it, supplies the generated combustion gas to the turbine to obtain rotational power, a method for starting the gas turbine, and high-pressure fuel and high-pressure air. Combustion in the gas turbine and power generation with the generated combustion gas, high temperature exhaust gas discharged from the gas turbine is sent to the boiler to generate steam, and the generated steam is sent to the steam turbine to generate power and cooling The present invention relates to a combined power generation system in which the supplied water is returned to the boiler and overheated.

  For example, a gas turbine is composed of a compressor, a combustor, and a turbine. The air taken in from the air intake port is compressed by the compressor to become high-temperature / high-pressure compressed air. Fuel is supplied to the compressed air and burned, and high-temperature and high-pressure combustion gas drives a turbine and a generator connected to the turbine. In a combined power plant to which such a gas turbine is applied, the high-temperature exhaust gas generated in this gas turbine is sent to an exhaust heat recovery boiler to generate steam, and the generated steam is sent to the steam turbine to generate a generator. The condensate cooled by the steam turbine is returned to the exhaust heat recovery boiler and heated, and steam is generated again and sent to the steam turbine.

  As such a combined power plant, there is one described in Patent Document 1 below.

Japanese Patent Laid-Open No. 08-121117

  By the way, in the above-described combined power plant, the gas turbine has many operation modes that are repeatedly started and stopped every day. In this case, it is important to shorten the start time of the gas turbine. In general, the operation of the gas turbine is started by a starter motor connected to the turbine shaft, and the rotation speed at which the gas turbine can stand by operating (igniting) the combustor (for example, the rotation speed of 70% of the rated rotation). ) To assist the climb. Then, after the gas turbine is self-supporting, the starting motor is disconnected from the turbine shaft, the amount of fuel input to the combustor is increased, the speed is increased to the rated number of revolutions, and the engine is started continuously.

  However, in such a conventional gas turbine starting method, there is a problem that the starting time becomes long and the exhaust purification efficiency decreases. That is, when the gas turbine is started, the combustor itself is at a low temperature, so that carbon monoxide (CO) and unburned carbon (UHC) contained in the exhaust gas increase. In addition, if the start-up time of the gas turbine is long, the amount of fuel consumed at the time of start-up increases, fuel costs increase, and the total emission of carbon monoxide (CO) and unburned carbon (UHC) increases. There is a problem that it ends up.

  Therefore, in order to shorten the start-up time of the gas turbine, it is conceivable to increase the amount of fuel input when the combustor is operated and the speed is increased after the drive rotation is started by the start-up motor. However, if the amount of fuel input is increased when the turbine speed is low, the turbine pressure ratio becomes too high, so that the operating condition of the compressor approaches the surge line and the rotation becomes unstable. Further, when the turbine pressure ratio is low, if the amount of fuel input is increased here, the exhaust gas temperature may exceed the limit or the turbine generated torque may be insufficient.

  The present invention solves the above-described problems, and provides a gas turbine, a gas turbine startup method, and a combined power generation system that can suppress a reduction in exhaust purification efficiency and an increase in fuel cost by shortening the startup time. For the purpose.

  In order to achieve the above object, the gas turbine according to the first aspect of the present invention is configured such that fuel is supplied to the compressed air compressed by the compressor by the combustor and burned, and the generated combustion gas is supplied to the turbine to rotate the power. Is provided with an exhaust gas recirculation line for recirculating at least a part of the exhaust gas discharged from the turbine to the compressor at startup.

  A gas turbine according to a second aspect of the present invention is a gas turbine that obtains rotational power by supplying fuel to compressed air compressed by a compressor by a combustor and supplying the generated combustion gas to the turbine. An exhaust gas discharge line for opening at least a part of the exhaust gas discharged from the turbine to the atmosphere is provided.

  In the gas turbine according to the third aspect of the present invention, an on-off valve is provided in the exhaust gas recirculation line or the exhaust gas discharge line, and the combustion is performed when the turbine shaft reaches a preset first predetermined rotation speed or more. And the opening / closing valve is opened.

  In a gas turbine according to a fourth aspect of the present invention, an open / close valve is provided in the exhaust gas recirculation line or the exhaust gas discharge line, and the open / close valve is opened at the start of driving rotation of the turbine shaft.

  The gas turbine according to claim 5 is characterized in that the on-off valve is closed when the turbine shaft reaches or exceeds a preset second predetermined rotational speed.

  According to a sixth aspect of the present invention, there is provided a combined power generation system in which high-pressure fuel and high-pressure air are combusted in a gas turbine to generate electric power from the generated combustion gas and high-temperature exhaust gas discharged from the gas turbine is boiler. In a combined power generation system in which the generated steam is sent to a steam turbine to generate electricity, and the cooled feed water is returned to the boiler and overheated, and at least of the exhaust gas discharged at the start of the gas turbine An exhaust gas recirculation line that recirculates a part to the compressor is provided.

  A combined power generation system according to a seventh aspect of the invention combusts high pressure fuel and high pressure air in a gas turbine, generates electric power with the generated combustion gas, and sends high-temperature exhaust gas discharged from the gas turbine to a boiler. In a combined power generation system that generates steam and sends the generated steam to a steam turbine to generate electric power and returns the cooled feed water to a boiler to overheat, and at least a part of the exhaust gas discharged at the time of starting the gas turbine Is provided with an exhaust gas discharge line for opening the air to the atmosphere.

  Furthermore, a gas turbine according to an eighth aspect of the present invention is a gas turbine in which fuel is supplied to a compressed air compressed by a compressor and burned by a combustor, and rotational power is obtained by supplying the generated combustion gas to the turbine. A bypass line for supplying a part of the compressed air compressed by the compressor to the rear stage of the turbine at the time of startup is provided.

  In the gas turbine according to the ninth aspect of the present invention, an on-off valve is provided in the bypass line, and when the turbine shaft reaches or exceeds a preset first predetermined rotation speed, the combustor is operated and the on-off valve is operated. It is characterized by opening.

  In a gas turbine according to a tenth aspect of the present invention, an open / close valve is provided in the bypass line, and the open / close valve is opened at the start of driving rotation of the turbine shaft.

  The gas turbine according to an eleventh aspect of the invention is characterized in that the on-off valve is closed when the turbine shaft reaches a preset second predetermined rotation speed or higher.

  In a gas turbine according to a twelfth aspect of the present invention, the bypass line is connected to a stationary blade in a rear stage of the turbine, and a slit that discharges compressed air toward the moving blade as an air flow of a swirling component in the stationary blade. It is characterized by being provided.

  According to a thirteenth aspect of the present invention, there is provided a gas turbine start-up method in which fuel is supplied to a compressed air compressed by a compressor and burned by a combustor, and the generated combustion gas is supplied to the turbine to obtain rotational power. The turbine is characterized in that at least a part of the exhaust gas discharged from the turbine at the time of startup is opened to the atmosphere.

  According to a fourteenth aspect of the present invention, there is provided a gas turbine start-up method in which fuel is supplied to a compressed air compressed by a compressor and burned by a combustor, and the generated combustion gas is supplied to the turbine to obtain rotational power. In the turbine, a part of the compressed air compressed by the compressor at the time of start-up is supplied to the rear stage of the turbine.

  According to the gas turbine of the first aspect of the present invention, since the exhaust gas recirculation line for recirculating at least a part of the exhaust gas discharged from the turbine at the start-up to the compressor is provided, the gas turbine is compressed by the compressor. Combustion is performed by supplying fuel to the compressed air with a combustor, and the generated combustion gas is supplied to the turbine to obtain rotational power. At the start of the gas turbine, a part of the exhaust gas discharged from the turbine is exhausted. Since the gas is recirculated to the compressor by the gas recirculation line, the exhaust pressure can be lowered, the turbine expansion ratio can be raised and the exhaust gas temperature can be lowered, while the turbine driving torque is raised and the rate of acceleration is increased. In addition, it is possible to reduce the intake flow rate of the compressor and reduce the required drive torque. It is possible to suppress the increase of the bets.

  According to the gas turbine of the second aspect of the present invention, since the exhaust gas discharge line that opens at least a part of the exhaust gas discharged from the turbine at the start-up to the atmosphere is provided, the gas turbine is compressed air compressed by the compressor. The fuel is supplied by the combustor and burned, and the generated combustion gas is supplied to the turbine to obtain rotational power. At the start of the gas turbine, a part of the exhaust gas discharged from the turbine is discharged into the exhaust gas discharge line. The exhaust pressure can be reduced and the exhaust gas temperature can be reduced by increasing the turbine expansion ratio, while the driving torque of the turbine can be increased to increase the rate of acceleration. As a result, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost by shortening the startup time.

  According to the gas turbine of the third aspect of the present invention, the on-off valve is provided in the exhaust gas recirculation line or the exhaust gas discharge line, and the combustor is operated when the turbine shaft reaches a first predetermined rotation speed or higher. In addition, since the on-off valve is opened, the on-off valve is opened after ignition in the combustor, and a part of the exhaust gas discharged from the turbine is recirculated to the compressor or opened to the atmosphere. By reducing the value, the turbine expansion ratio can be increased.

  According to the gas turbine of the fourth aspect of the present invention, the on-off valve is provided in the exhaust gas recirculation line or the exhaust gas discharge line, and the on-off valve is opened at the start of driving rotation of the turbine shaft. A part of the exhaust gas discharged from the turbine is recirculated to the compressor or opened to the atmosphere by opening the on-off valve, and the turbine expansion ratio can be increased by reducing the exhaust pressure from the start-up. .

  According to the gas turbine of the fifth aspect of the invention, since the on-off valve is closed when the turbine shaft reaches or exceeds the second predetermined rotation speed set in advance, the gas turbine exceeds the second predetermined rotation speed at which the gas turbine can stand on its own. Then, the on-off valve is closed to stop recirculation of exhaust gas discharged from the turbine or release to the atmosphere, and the gas turbine can be started at an early stage to start power generation.

  According to the combined power generation system of the sixth aspect of the present invention, since the exhaust gas recirculation line for recirculating at least a part of the exhaust gas discharged when starting the gas turbine to the compressor is provided, , High-pressure fuel and high-pressure air are combusted in a gas turbine, and electric power is generated by the generated combustion gas, and high-temperature exhaust gas discharged from the gas turbine is sent to a boiler to generate steam, and the generated steam is Power is sent to the steam turbine to generate electricity, but when the gas turbine is started, a part of the exhaust gas discharged from the turbine is recirculated to the compressor by the exhaust gas recirculation line. The exhaust pressure can be reduced and the turbine expansion ratio can be increased to lower the exhaust gas temperature, while the turbine drive torque is increased to increase the rate of acceleration. And the required drive torque can be reduced by reducing the intake air flow rate of the compressor. As a result, the start-up time can be shortened to suppress the decrease in exhaust purification efficiency and the increase in fuel cost. it can.

  According to the combined power generation system of the seventh aspect of the present invention, since the exhaust gas discharge line that opens at least a part of the exhaust gas discharged from the turbine at start-up to the atmosphere is provided, the combined power generation system includes a high-pressure fuel and a high-pressure fuel The air is combusted in a gas turbine and power is generated by the generated combustion gas. The high-temperature exhaust gas discharged from the gas turbine is sent to a boiler to generate steam, and the generated steam is sent to the steam turbine to generate power. However, when the gas turbine is started, a part of the exhaust gas exhausted from the turbine is recirculated to the compressor by the exhaust gas recirculation line, so that the exhaust pressure of the exhaust gas line from the gas turbine to the boiler is reduced. It is possible to increase the turbine expansion ratio and lower the exhaust gas temperature, while increasing the turbine drive torque and the acceleration rate. As a result, it is possible to suppress an increase in the reduction and fuel costs of the exhaust gas purification efficiency by shortening the startup time.

  Further, according to the gas turbine of the invention of claim 8, since the bypass line for supplying a part of the compressed air compressed by the compressor at the start to the rear stage of the turbine is provided, the gas turbine is compressed by the compressor. Combustion is performed by supplying fuel to the compressed air with a combustor, and the generated combustion gas is supplied to the turbine to obtain rotational power. When the gas turbine is started, a part of the compressed air compressed by the compressor is obtained. Since the bypass line supplies the rear stage of the turbine, the amount of air in the rear stage of the turbine is increased, so that the low torque operation mode can be shifted to the high torque operation mode, and the turbine generation torque is increased to increase the speed increase rate. As a result, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost by shortening the startup time.

  According to the gas turbine of the ninth aspect of the present invention, the on-off valve is provided in the bypass line, and the combustor is operated and the on-off valve is opened when the turbine shaft reaches a first predetermined rotation speed or higher. After the ignition in the combustor, the on-off valve is opened and a part of the compressed air compressed by the compressor is supplied to the rear stage of the turbine, increasing the turbine generation torque after combustion and increasing the rate of acceleration. Can do.

  According to the gas turbine of the tenth aspect of the present invention, the on-off valve is provided in the bypass line, and the on-off valve is opened when the turbine shaft drive rotation is started. A part of the compressed air compressed in step (3) is supplied to the rear stage of the turbine, and the turbine generation torque from the start-up can be increased to increase the speed increase rate.

  According to the gas turbine of the eleventh aspect of the invention, since the on-off valve is closed when the turbine shaft reaches a preset second predetermined rotation speed or higher, the gas turbine becomes the second predetermined rotation speed or higher at which the gas turbine can stand on its own. Then, the on-off valve is closed to stop the supply of compressed air to the rear stage of the turbine, and the gas turbine can be started early to start power generation.

  According to the gas turbine of the twelfth aspect of the present invention, the bypass line is connected to the stationary blade in the rear stage of the turbine, and the stationary blade is provided with a slit for discharging the compressed air as a swirling component air flow toward the moving blade. As a result, the compressed air supplied to the rear stage of the turbine is discharged from the slits of the stationary blades toward the rotor blades as a swirling component air flow, thereby minimizing the pressure loss during discharge of the compressed air. The driving force of the turbine can be assisted.

  According to the gas turbine start-up method of the thirteenth aspect of the present invention, at least a part of the exhaust gas discharged from the turbine at the time of start-up is opened to the atmosphere, so the gas turbine converts the compressed air compressed by the compressor into Rotation power is obtained by supplying fuel with a combustor and burning, and the generated combustion gas is supplied to the turbine, but when the gas turbine starts up, part of the exhaust gas discharged from the turbine is released to the atmosphere. The exhaust pressure can be reduced and the turbine expansion ratio can be increased to lower the exhaust gas temperature, while the turbine drive torque can be increased to increase the rate of acceleration, resulting in a reduction in start-up time. By doing so, a decrease in exhaust purification efficiency and an increase in fuel cost can be suppressed.

  According to the gas turbine starting method of the invention of claim 14, since a part of the compressed air compressed by the compressor at the time of starting is supplied to the rear stage of the turbine, the gas turbine is compressed by the compressor. Rotation power is obtained by supplying fuel to the compressed air with a combustor and supplying the generated combustion gas to the turbine. When the gas turbine starts up, a part of the compressed air compressed by the compressor is Therefore, the amount of air in the rear stage of the turbine is increased, the low torque operation mode can be shifted to the high torque operation mode, the turbine generation torque can be increased, and the speed increase rate can be increased. As a result, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost by shortening the startup time.

  Exemplary embodiments of a gas turbine, a gas turbine starting method, and a combined power generation system according to the present invention will be described below in detail with reference to the accompanying drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a schematic configuration diagram illustrating a combined power generation system to which a gas turbine according to a first embodiment of the present invention is applied. FIG. 2 illustrates changes in turbine rotational speed and expansion ratio when the gas turbine according to the first embodiment is started. It is a graph to represent.

  In the combined power generation system according to the first embodiment, as illustrated in FIG. 1, the gas turbine 11 includes a compressor 12, a combustor 13, and a turbine 14, and the generator 16 is connected via a turbine shaft 15. ing. The generator 16 is a thyristor motor, which functions as a gas turbine starting motor and functions as a generator after starting the gas turbine. An intake pipe 18 having a filter 17 is connected to the compressor 12 of the gas turbine 11 on the inlet side, and an exhaust pipe 19 is connected to the outlet side of the turbine 14.

  An exhaust pipe 19 of the gas turbine 11 is connected to a chimney 21 via an exhaust heat recovery boiler 20. The exhaust heat recovery boiler 20 has, for example, a high-pressure boiler, an intermediate-pressure boiler, and a low-pressure boiler, and can generate steam in each boiler by the exhaust gas from the gas turbine 11. The steam turbine 22 is driven by the steam generated in the exhaust heat recovery boiler 20 being supplied through the pipe 23, and the connected generator 24 can be operated. The steam supplied to the steam turbine 22 is sent to the condenser 26 through the pipe 25 and condensed, and then sent to the exhaust heat recovery boiler 20 by the condensate pump 27.

  Here, the operation of the above-described combined power plant will be described. In the gas turbine 11, the air taken into the compressor 12 through the intake pipe 18 is compressed to become high-temperature and high-pressure compressed air, and this compressed air is combusted. In this case, the fuel is combusted by supplying a predetermined amount of fuel to the compressed air. The high-temperature and high-pressure combustion gas generated by the combustor 13 is sent to the turbine 14 and passes through a plurality of stationary blades and moving blades, thereby driving and rotating the turbine shaft 15 and rotating the generator 16. To generate electricity. On the other hand, the exhaust gas discharged from the turbine 14 is sent to the exhaust heat recovery boiler 20 through the exhaust pipe 16, where steam is generated by the high-temperature and high-pressure exhaust gas. The steam generated here is sent to the steam turbine 22 through the pipe 23, and by driving the steam turbine 22, the generator 24 is rotationally driven to generate power. The steam supplied to the steam turbine 22 is sent to the condenser 26 through the pipe 25 and condensed, and then returned to the exhaust heat recovery boiler 20 by the condensate pump 27.

  In the combined power plant configured as described above, since the gas turbine 11 has many operation modes that are repeatedly started and stopped every day, it is important to shorten the start-up time in terms of exhaust purification efficiency and fuel cost. It is. Therefore, in this embodiment, when the gas turbine 11 is started, at least a part of the exhaust gas discharged from the turbine 14 is recirculated to the compressor 12, thereby reducing the exhaust pressure and increasing the expansion ratio to start up the engine. To shorten.

  That is, an exhaust gas recirculation line 31 extending from the exhaust pipe 19 of the turbine 14 to the intake pipe 18 of the compressor 12 is provided, and an open / close valve 32 is provided in the exhaust gas recirculation line 31. In this case, it is desirable to connect the downstream end portion of the exhaust gas recirculation line 31 to the downstream side of an unillustrated IGV (Inlet Guide Vane) in the compressor 12.

  Therefore, when the gas turbine 11 is started, the generator 16 is caused to function as a starter motor to start driving rotation of the turbine shaft 15, and the rotation speed of the turbine shaft 15 is equal to or higher than a preset first predetermined rotation speed. At this time, the combustor 13 is operated to ignite, and at the same time, the on-off valve 32 is opened, whereby the exhaust gas discharged from the turbine 14 is recirculated to the compressor 12 through the exhaust gas recirculation line 31. In this case, a positive pressure (pressure loss) acts by connecting the exhaust heat recovery boiler 20 to the downstream side of the exhaust pipe 19, and a negative pressure acts on the intake pipe 18 side by operating the compressor 12. Therefore, the exhaust gas can be recirculated to the compressor 12 simply by opening the on-off valve 32.

  Thereafter, when the rotational speed of the turbine shaft 15 becomes equal to or higher than a preset second predetermined rotational speed, the on-off valve 32 is closed so that the exhaust gas is recirculated to the compressor 12 by the exhaust gas recirculation line 31. Stop circulation. Then, the generator 16 that has been functioning as the starter motor is caused to function as a generator, the amount of fuel input to the combustor 13 is increased, the speed is increased to the rated rotational speed, and the engine is then started.

  In this case, the second predetermined rotational speed is a rotational speed at which the gas turbine 11 can stand on its own (for example, 70% of the rated rotational speed), and the first predetermined rotational speed is lower than the second predetermined rotational speed, and the compressor 12 is a rotational speed at which fuel can be injected into the compressed air compressed by 12 and ignited.

Here, in the combined power generation system of the first embodiment, the turbine rotation speed and the expansion ratio when the gas turbine 11 is started will be described in detail. As shown in the graph of FIG. 2, first, when the turbine shaft 15 is driven and rotated by the generator (starting motor) 16 at time t ₀ , the turbine rotational speed N increases and the expansion ratio R increases. Here, when the pressure of the combustion gas sent from the combustor 13 to the turbine 14 is P ₁ and the pressure of the exhaust gas discharged from the turbine 14 is P ₂ , the expansion ratio R is R = P ₁ / P ₂ It is required.

Next, in the conventional control, as indicated by a dotted line in FIG. 2, when the rotational speed N of the turbine shaft 15 reaches the first predetermined rotational speed N ₁ at time t ₁ , the combustor 13 is operated. Ignite. Then, the combustion gas generated in the combustor 13 is sent to the turbine 14, so that the turbine 14 is driven to further increase the turbine rotational speed N and increase the expansion ratio R. Subsequently, at time t _2, when the rotational speed N of the turbine shaft 15 is in the second predetermined rotational speed N _2, to stop the driving of the generator (start motor) 16 turbine shaft 15 by. When the rotation speed N of the turbine shaft 15 reaches the second predetermined rotation speed N ₂ and becomes self-supporting, the amount of fuel input to the combustor 13 is increased to increase the speed to the rated rotation speed, thereby achieving steady operation.

On the other hand, in the control of this embodiment, as indicated by the solid line in FIG. 2, when the rotational speed N of the turbine shaft 15 reaches the first predetermined rotational speed N ₁ at time t ₁ , the combustor 13 is operated. Then, the ignition valve 32 is opened simultaneously with the ignition. Then, the combustion gas generated in the combustor 13 is sent to the turbine 14, so that the turbine 14 is driven to further increase the turbine rotational speed N and increase the expansion ratio R. Further, since the exhaust gas discharged from the turbine 14 by opening the on-off valve 32 is recirculated to the compressor 12 through the exhaust gas recirculation line 31, the exhaust pressure of the turbine 14 (the exhaust gas discharged from the turbine 14) The pressure P ₂ ) can be reduced, and the exhaust gas temperature can be lowered by increasing the expansion ratio. Furthermore, since the exhaust pressure of the turbine 14 decreases, the driving torque of the turbine 14 can be increased and the speed increase rate can be increased. On the other hand, the exhaust gas is introduced into the compressor 12, and the intake flow rate introduced from the intake pipe 18 can be reduced to reduce the required drive torque.

Accordingly, at the time t ₃ earlier than the time t ₂ by the conventional control, the rotational speed N of the turbine shaft 15 becomes the second predetermined rotational speed N ₂ , and here, the turbine shaft 15 by the generator (starting motor) 16. At the same time, the on-off valve 32 is closed and the recirculation of the exhaust gas to the compressor 12 by the exhaust gas recirculation line 31 is stopped. When the rotation speed N of the turbine shaft 15 reaches the second predetermined rotation speed N ₂ and becomes self-supporting, the amount of fuel input to the combustor 13 is increased and the speed is increased to the rated rotation speed to achieve steady operation.

From the above description, in the conventional gas turbine, the turbine shaft 15 is driven and rotated by the generator 16 in the region a from the time t ₀ to the time t ₁ , and the generator 16 and the combustor 13 in the region b up to the time t _2. The turbine shaft 15 is driven and rotated by the operation of, and the turbine shaft 15 is driven and rotated only by the operation of the combustor 13 in the region c after time t ₂ to be in steady operation. On the other hand, the generator in the gas turbine of this embodiment, rotates the turbine shaft 15 by the generator 16 in the area A (A = a) up to the time t _1, the region up to the time t ₃ B (B <b) 16 and the turbine shaft 15 and rotated by the operation of the combustor 13, and a steady operation by rotating the turbine shaft 15 by only the operation of the combustor 13 at time t ₃ after the region C (C> c). Therefore, in this embodiment, the speed can be increased to the second predetermined rotational speed N _{2 in a} shorter time than before, and the operation can be shifted to the steady operation at an early stage, and the startup time of the gas turbine 11 can be shortened.

  As described above, in the gas turbine and the combined power generation system according to the first embodiment, high-pressure fuel and high-pressure air are combusted in the gas turbine 11, and the generated combustion gas generates power and is discharged from the gas turbine 11. The high-temperature exhaust gas is sent to the exhaust heat recovery boiler 20 to generate steam, and the generated steam is sent to the steam turbine 22 to generate power, and the exhaust gas discharged from the turbine 14 when the gas turbine 11 is started up. An exhaust gas recirculation line 31 is provided for recirculating at least a part of the exhaust gas to the compressor 12.

  Accordingly, the gas turbine 11 is supplied with fuel by the combustor 13 to the compressed air compressed by the compressor 12 and burns, and the generated combustion gas is supplied to the turbine 14 to obtain rotational power. When the engine is started up, a part of the exhaust gas exhausted from the turbine 14 is recirculated to the compressor 12 through the exhaust gas recirculation line 31, so that the exhaust pressure of the turbine 14 can be reduced, and the exhaust gas is exhausted with an increased expansion ratio. While the gas temperature can be lowered, the drive torque of the turbine 14 can be increased to increase the rate of acceleration, and the intake flow rate of the compressor 12 can be reduced to reduce the required drive torque, and as a result. By shortening the startup time of the gas turbine 11 and the combined power generation system, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost.

  Further, in the gas turbine of this embodiment, an on-off valve 32 is provided in the exhaust gas recirculation line 31 to operate the combustor 13 and open the on-off valve 32 when the turbine shaft 15 reaches the first predetermined rotation speed or higher. Like to do. Accordingly, after the ignition in the combustor 13, the on-off valve 32 is opened and a part of the exhaust gas discharged from the turbine 14 is recirculated to the compressor 12, and the exhaust pressure after combustion is reduced, thereby expanding the exhaust gas. The ratio can be reliably increased.

  Further, in the gas turbine of the present embodiment, the on-off valve 32 is closed when the turbine shaft 15 reaches the second predetermined rotation speed or higher. Accordingly, after the gas turbine 11 reaches a second predetermined rotation speed or more at which it can stand on its own, the on-off valve 32 is closed to stop the recirculation of the exhaust gas discharged from the turbine 14, and the gas turbine 11 is started early. Then you can start power generation.

  Further, the downstream end of the exhaust gas recirculation line 31 is connected to the downstream side of the IGV in the compressor 12. By restricting the intake air flow rate to the compressor 12 when the gas turbine 11 is started, a high acceleration rate of the turbine shaft 15 by the generator (starting motor) 16 is secured, so the opening degree of the IGV is located on the closing side. At this time, exhaust gas can be efficiently introduced into the compressor 12 by introducing the exhaust gas downstream of the IGV in the compressor 12.

  FIG. 3 is a graph showing changes in the turbine rotational speed and the expansion ratio when the gas turbine is started in the combined power generation system to which the gas turbine according to the second embodiment of the present invention is applied. The overall configuration of the combined power generation system of the present embodiment is almost the same as that of the first embodiment described above, and will be described with reference to FIG. 1 and members having the same functions as those described in this embodiment will be described. The description which attaches | subjects the same code | symbol and overlaps is abbreviate | omitted.

The overall configuration of the combined power generation system of Example 2 is the same as that of Example 1 described above, and only the on / off control of the on / off valve at the time of activation is different. Here, in the combined power generation system of the second embodiment, the turbine rotation speed and the expansion ratio when the gas turbine 11 is started will be described in detail. First, in the conventional control, when the turbine shaft 15 is driven and rotated by the generator (starting motor) 16 at time t ₀ as shown by a dotted line in FIG. 3, the turbine rotational speed N increases and the expansion ratio R is increased. To rise. Then, at time t _1, when the rotational speed N of the turbine shaft 15 becomes the first predetermined rotational speed N _1, ignited by operating the combustor 13. Then, the combustion gas generated in the combustor 13 is sent to the turbine 14, so that the turbine 14 is driven to further increase the turbine rotational speed N and increase the expansion ratio R. Subsequently, at time t _2, when the rotational speed N of the turbine shaft 15 is in the second predetermined rotational speed N _2, to stop the drive of the turbine shaft 15 by the generator (start motor) 16, the gas turbine 11 is self-supporting For this reason, the amount of fuel input to the combustor 13 is increased and the speed is increased to the rated rotational speed to achieve steady operation.

On the other hand, in the control of this embodiment, as indicated by the solid line in FIG. 3, when the turbine shaft 15 is driven and rotated by the generator (starting motor) 16 at the time t _{0 and} at the same time the opening / closing valve 32 is opened, As the turbine speed N increases, the expansion ratio R increases. Next, when the rotational speed N of the turbine shaft 15 reaches the first predetermined rotational speed N ₁ at time t ₁₁ , the combustor 13 is operated to ignite. Then, the combustion gas generated in the combustor 13 is sent to the turbine 14, so that the turbine 14 is driven to further increase the turbine rotational speed N and increase the expansion ratio R. In this case, since the on-off valve 32 has been opened since the start, the exhaust gas discharged from the turbine 14 is recirculated to the compressor 12 through the exhaust gas recirculation line 31, and the exhaust pressure of the turbine 14 (discharged from the turbine 14). The exhaust gas pressure P ₂ ) can be reduced, and the expansion ratio can be increased to lower the exhaust gas temperature. Furthermore, since the exhaust pressure of the turbine 14 decreases, the driving torque of the turbine 14 can be increased and the speed increase rate can be increased. On the other hand, the flow rate of intake air introduced from the intake pipe 18 into the large furnace where the exhaust gas is introduced into the compressor 12 can be reduced, and the required driving torque can be reduced.

Thus, at an earlier time t ₁₁ than the time t ₁ by a conventional control, the rotational speed N of the turbine shaft 15 becomes the first predetermined rotational speed N _2, also earlier at time t ₁₂ than the time t _2, The rotational speed N of the turbine shaft 15 becomes the second predetermined rotational speed N ₂ , where the on-off valve 32 is closed simultaneously with stopping the driving of the turbine shaft 15 by the generator (starting motor) 16, and the exhaust gas recirculation line The recirculation of exhaust gas to the compressor 12 by 31 is stopped. When the rotation speed N of the turbine shaft 15 reaches the second predetermined rotation speed N ₂ and becomes self-supporting, the amount of fuel input to the combustor 13 is increased and the speed is increased to the rated rotation speed to achieve steady operation.

From the above description, in the gas turbine of this embodiment, rotates the turbine shaft 15 by the generator 16 in the area A (A = a) from the time t ₀ to time t _11, the region up to the time t ₁₂ B ( <rotates the turbine shaft 15 by the operation of the generator 16 and a combustor 13 b), the time t ₁₂ after the region C (C> B rotates the turbine shaft 15 by only the operation of the combustor 13 in c) Steady operation. Therefore, in the present embodiment, the speed can be increased to the second predetermined rotational speed N _{2 in a} shorter time than in the prior art and in a shorter time than in the first embodiment, and the operation can be shifted to the steady operation at an early stage. Can be shortened.

As described above, in the gas turbine and the combined power generation system according to the second embodiment, the exhaust gas recirculation line 31 for recirculating a part of the exhaust gas discharged from the turbine 14 to the compressor 12 is provided. An open / close valve 32 is provided in the recirculation line 31, and the open / close valve 32 is opened until the gas turbine 11 is started up to the second predetermined rotation speed N ₂ , and the exhaust gas discharged from the turbine 14 is discharged to the compressor. 12 is recirculated.

  Accordingly, the gas turbine 11 is supplied with fuel by the combustor 13 to the compressed air compressed by the compressor 12 and burns, and the generated combustion gas is supplied to the turbine 14 to obtain rotational power. Since a part of the exhaust gas discharged from the turbine 14 is recirculated to the compressor 12 by the exhaust gas recirculation line 31 immediately after the start of the engine, the exhaust pressure of the turbine 14 can be reduced, and the expansion ratio is increased. While the exhaust gas temperature can be lowered, the driving torque of the turbine 14 can be increased to increase the rate of acceleration, and the intake flow rate of the compressor 12 can be reduced to reduce the required driving torque. As a result, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost by shortening the startup time of the gas turbine 11 and the combined power generation system.

  FIG. 4 is a schematic configuration diagram illustrating a combined power generation system to which a gas turbine according to a third embodiment of the present invention is applied. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the combined power generation system of the third embodiment, as shown in FIG. 4, the gas turbine 11 includes a compressor 12, a combustor 13, and a turbine 14, and a generator 16 is connected via a turbine shaft 15. An intake pipe 18 having a filter 17 on the inlet side is connected to the compressor 12, while an exhaust pipe 19 is connected to the outlet side of the turbine 14. The exhaust pipe 19 of the gas turbine 11 is connected to the chimney 21 via the exhaust heat recovery boiler 20. The steam turbine 22 is driven by the steam generated in the exhaust heat recovery boiler 20 being supplied through the pipe 23 and operates the generator 24. The steam supplied to the steam turbine 22 is sent to the condenser 26 through the pipe 25 and condensed, and then sent to the exhaust heat recovery boiler 20 by the condensate pump 27.

  In the combined power plant configured as described above, in this embodiment, when the gas turbine 11 is started, the exhaust pressure is reduced by opening at least a part of the exhaust gas discharged from the turbine 14 to the atmosphere. The startup time is shortened by increasing the expansion ratio. In other words, an exhaust gas discharge line 41 that bypasses the exhaust heat recovery boiler 20 from the exhaust pipe 19 of the turbine 14 to the chimney 21 is provided, and an open / close valve 42 is provided in the exhaust gas discharge line 41.

  Therefore, when the gas turbine 11 is started, the generator 16 is caused to function as a starter motor to start driving rotation of the turbine shaft 15, and the rotation speed of the turbine shaft 15 is equal to or higher than a preset first predetermined rotation speed. At this time, the combustor 13 is operated and ignited, and at the same time, the on-off valve 42 is opened, so that the exhaust gas discharged from the turbine 14 is discharged from the chimney 21 through the exhaust gas discharge line 41 to the atmosphere. Thereafter, when the rotational speed of the turbine shaft 15 becomes equal to or higher than a second predetermined rotational speed set in advance, the on-off valve 42 is closed to stop the exhaust gas exhaust line 41 from discharging to the atmosphere. . Then, the generator 16 that has been functioning as the starter motor is caused to function as a generator, the amount of fuel input to the combustor 13 is increased, the speed is increased to the rated rotational speed, and the engine is then started.

  In this case, the exhaust gas discharged from the turbine 14 passes through the exhaust gas discharge line 41 by opening the on-off valve 42 at the same time as the generator 16 starts driving rotation of the turbine shaft 15 as in the second embodiment. It may be discharged from the chimney 21 to the atmosphere.

  As described above, in the gas turbine and the combined power generation system according to the third embodiment, high-pressure fuel and high-pressure air are burned in the gas turbine 11, and the generated combustion gas generates power and is discharged from the gas turbine 11. The high-temperature exhaust gas is sent to the exhaust heat recovery boiler 20 to generate steam, and the generated steam is sent to the steam turbine 22 to generate power, and the exhaust gas discharged from the turbine 14 when the gas turbine 11 is started up. Is provided with an exhaust gas discharge line 41 for discharging at least a part thereof to the atmosphere.

  Accordingly, the gas turbine 11 is supplied with fuel by the combustor 13 to the compressed air compressed by the compressor 12 and burns, and the generated combustion gas is supplied to the turbine 14 to obtain rotational power. When starting up, a part of the exhaust gas exhausted from the turbine 14 is exhausted to the atmosphere through the exhaust gas exhaust line 41, so that the exhaust pressure of the turbine 14 can be reduced, and the expansion ratio is increased to lower the exhaust gas temperature. On the other hand, the driving torque of the turbine 14 can be increased to increase the speed increase rate, and the intake flow rate of the compressor 12 can be reduced to reduce the required driving torque. As a result, the gas turbine 11 can be reduced. In addition, by reducing the startup time of the combined power generation system, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost.

  Further, in the gas turbine of this embodiment, the on-off valve 42 is provided in the exhaust gas discharge line 41 so that the on-off valve 42 is opened when the turbine shaft 15 is started or when the first predetermined rotational speed is exceeded. . Therefore, a part of the compressed air compressed by the compressor at the time of start-up or the combustion gas combusted by the combustor 13 is recirculated to the compressor 12, and the exhaust pressure is reduced after the start-up or after the combustion. Thus, the expansion ratio can be reliably increased.

  Further, in the gas turbine of this embodiment, the on-off valve 42 is closed when the turbine shaft 15 reaches the second predetermined rotation speed or higher. Therefore, after the gas turbine 11 reaches a second predetermined rotation speed or more at which it can stand on its own, the on-off valve 42 is closed to stop the exhaust gas discharged from the turbine 14 from being released into the atmosphere, and the gas turbine 11 is started early. Then you can start power generation.

  FIG. 5 is a schematic configuration diagram illustrating a gas turbine according to a fourth embodiment of the present invention, and FIG. 6 is a schematic diagram illustrating a stationary blade and a moving blade for explaining an extraction line in the gas turbine according to the fourth embodiment. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the combined power generation system according to the fourth embodiment, as shown in FIG. 5, the gas turbine 11 includes a compressor 12, a combustor 13, and a turbine 14, and an intake pipe 18 is connected to the compressor 12 on the inlet side. The exhaust pipe 19 is connected to the outlet side of the turbine 14. The compressor 12 is provided with four vehicle compartments 12a, 12b, 12c, and 12d for each stage, and the turbine is provided with four vehicle compartments 14a, 14b, 14c, and 14d for each stage. ing. In the compressor 12, three extraction lines 51a, 51b, 51c extending from the first, second, and third stage casings 12a, 12b, and 12c to the exhaust pipe 19 are provided, and combustion is performed from the fourth stage casing 12d. An extraction line 51 d extending to the exhaust pipe 19 is provided in the supply line for supplying compressed air to the vessel 13. On / off valves 52a, 52b, 52c and 52d are attached to the extraction lines 51a, 51b, 51c and 51d.

  In addition, cooling lines 53b, 53c, and 53d that branch from the respective extraction lines 51a, 51b, and 51c and reach the second, third, and fourth stage casings 14b, 14c, and 14d in the turbine 14 are provided. Further, in the present embodiment, a bypass line 54 branched from the fourth cooling line 53d branched from the first extraction line 51a is provided, and an on-off valve 55 is attached to the bypass line 54.

  On the other hand, as shown in FIGS. 5 and 6, in the fourth stage of the turbine 14, a plurality of stationary blades 56 are attached to a casing (not shown), while the turbine shaft 15 is positioned downstream of each stationary blade 56. A plurality of blades 57 are mounted. Each of the stationary blades 56 has a hollow shape, and the inside thereof is partitioned into first and second hollow portions 56a and 56b by a partition member 58. The tip of the fourth cooling line 53d is connected to the first hollow portion 56a of the stationary blade 56, while the tip of the bypass line 54 is connected to the second hollow portion 56b. The first hollow portion 56a is for supplying cooling air extracted from the casing 12a of the compressor 12 to cool the stationary blade 56 itself, and this cooling air is used for a bearing (not shown) of the turbine shaft 15. The seal air is supplied to the part to prevent leakage of the lubricating oil from the bearing part. Further, the stator blade 56 is formed with a slit 59 on the inner side corresponding to the second hollow portion 56b, and the second hollow portion 56b is cooled air extracted from the casing 12a of the compressor 12. Is supplied to cool the stationary blade 56 itself, and the cooling air is discharged from the slit 59 toward the rotor blade 57 as a swirling component air flow.

  Therefore, when the gas turbine 11 is started, the driving rotation of the turbine shaft 15 is started, and the combustor 13 is operated when the rotation speed of the turbine shaft 15 exceeds a preset first predetermined rotation speed. By opening the on-off valve 55 at the same time as ignition, the compressed air extracted from the first stage casing 12a of the compressor 12 passes through the extraction line 51a, the cooling line 53d, and the bypass line 54 in each of the fourth stage in the turbine 14. The air is supplied to the second hollow portion 56 b of the stationary blade 56 and is discharged from each slit 59 toward the moving blade 57 as a swirling component air flow. Thereafter, when the rotational speed of the turbine shaft 15 exceeds a preset second predetermined rotational speed, the on-off valve 55 is closed to discharge the compressed air to the rear stage of the turbine 14 by the bypass line 54. Stop. Then, the start of the turbine shaft 15 is stopped, the amount of fuel input to the combustor 13 is increased, the speed is increased to the rated rotational speed, and then the steady operation is performed.

  As described above, in the gas turbine and the combined power generation system according to the fourth embodiment, the bypass line 54 that supplies a part of the compressed air extracted from the compressor 12 to the rear stage of the turbine 14 when the gas turbine 11 is started is provided. An open / close valve 55 is provided in the bypass line 54.

  Accordingly, the gas turbine 11 is supplied with fuel by the combustor 13 to the compressed air compressed by the compressor 12 and burns, and the generated combustion gas is supplied to the turbine 14 to obtain rotational power. Since the compressed air extracted from the compressor 12 is supplied to the rear stage (fourth stage) of the turbine 14 through the extraction line 51a, the cooling line 53d, and the bypass line 54, the amount of air in the rear stage of the turbine 14 increases. The turbine 14 can be shifted from the compression operation mode to the turbine operation mode, the turbine generation torque can be increased and the speed increase rate can be increased, and as a result, the startup time of the gas turbine 11 and the combined power generation system can be shortened. Thus, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost.

  In this embodiment, when the gas turbine 11 is started, the on-off valve 55 is opened, and the compressed air extracted from the first stage compartment 12a of the compressor 12 passes through the extraction line 51a, the cooling line 53d, and the bypass line 54. The turbine 14 is supplied to the second hollow portion 56 b of each of the fourth stage stationary blades 56, and is discharged from each slit 59 toward the moving blade 57 as a swirling component air flow. Accordingly, since the swirl component is given to the compressed air from the slit 59 of the stationary blade 56 and discharged as the swirling air flow toward the moving blade 57, the energy for driving the turbine shaft 15 while suppressing the pressure loss at the time of discharge is used. By using it, the driving torque of the turbine 14 can be reduced.

  FIG. 7 is a schematic diagram illustrating a stationary blade and a moving blade for explaining an extraction line in a gas turbine according to a fifth embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the gas turbine of the fifth embodiment, as shown in FIG. 7, the tip of the fourth cooling line 53 d is connected to the first hollow portion 56 a of the stationary blade 56 in the fourth stage of the turbine 14, while the bypass line 54. Is connected to the second hollow portion 56b. A slit 60 is formed at the tip of the stationary blade 56 corresponding to the second hollow portion 56b, and the second hollow portion 56b is supplied with cooling air extracted from the casing 12a of the compressor 12. Then, the stationary blade 56 itself is cooled, and this cooling air is discharged from the slit 60 toward the moving blade 57 as a swirling component air flow.

  Therefore, when the gas turbine is started, the combustor is operated to ignite, and at the same time, the on-off valve 55 is opened, so that the compressed air extracted from the compressor passes through the extraction line, the cooling line, and the bypass line 54 and the fourth in the turbine 14. It is supplied to the second hollow portion 56 b of each stage stationary blade 56 and discharged from each slit 60 toward the moving blade 57 as a swirling component air flow. And after starting, by closing the on-off valve 55, the discharge to the back | latter stage of the turbine 14 by the bypass line 54 is stopped. Then, the start of the turbine shaft is stopped, the amount of fuel input to the combustor is increased, the speed is increased to the rated rotational speed, and then the steady operation is performed.

  As described above, in the gas turbine and the combined power generation system according to the fifth embodiment, the bypass line 54 for supplying a part of the compressed air extracted from the compressor to the rear stage of the turbine 14 is provided, and the bypass line 54 is opened and closed. A valve 55 is provided, and when the gas turbine is started, the on-off valve 55 is opened, and the compressed air extracted from the compressor passes through the extraction line, the cooling line, and the bypass line 54, and the fourth stage stationary blades 56 of the fourth stage in the turbine 14. 2 is supplied to the hollow portion 56b and discharged from each slit 60 toward the rotor blade 57 as a swirling component air flow.

  Accordingly, the amount of air in the rear stage of the turbine 14 is increased, the turbine 14 can be shifted from the compression operation mode to the turbine operation mode, the turbine generation torque can be increased, and the speed increase rate can be increased. By shortening the startup time of the turbine 11 and the combined power generation system, it is possible to suppress a decrease in exhaust purification efficiency and an increase in fuel cost. Further, since a swirl component is given to the compressed air from the slit 59 of the stationary blade 56 and discharged as a swirling air flow toward the moving blade 57, energy for driving the turbine shaft 15 while suppressing pressure loss at the time of discharge is provided. By using it, the driving torque of the turbine 14 can be reduced.

  FIG. 8 is a schematic configuration diagram illustrating a gas turbine according to a sixth embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the member which has the same function as what was demonstrated in the Example mentioned above, and the overlapping description is abbreviate | omitted.

  In the combined power generation system of the sixth embodiment, as shown in FIG. 8, the gas turbine 11 includes a compressor 12, a combustor 13, and a turbine 14, and an intake pipe 18 is connected to the compressor 12 on the inlet side. The exhaust pipe 19 is connected to the outlet side of the turbine 14. The compressor 12 is provided with four vehicle compartments 12a, 12b, 12c, and 12d for each stage, and the turbine is provided with four vehicle compartments 14a, 14b, 14c, and 14d for each stage. ing. In the compressor 12, three extraction lines 51a, 51b, 51c extending from the first, second, and third stage casings 12a, 12b, and 12c to the exhaust pipe 19 are provided, and combustion is performed from the fourth stage casing 12d. An extraction line 51 d extending to the exhaust pipe 19 is provided in the supply line for supplying compressed air to the vessel 13. On / off valves 52a, 52b, 52c and 52d are attached to the extraction lines 51a, 51b, 51c and 51d.

  In addition, cooling lines 53b, 53c, and 53d that branch from the respective extraction lines 51a, 51b, and 51c and reach the second, third, and fourth stage casings 14b, 14c, and 14d in the turbine 14 are provided. Furthermore, in the present embodiment, a bypass line 61 is provided that branches from the fourth extraction line 51d and reaches the fourth-stage casing 14d, and an on-off valve 62 is attached to the bypass line 61.

  As in the fourth and fifth embodiments described above, the tip of the bypass line 61 is connected to the second hollow portion of the stationary blade, and the cooling air can be discharged from the slit toward the blade as a swirling component air flow. it can.

  Therefore, when the gas turbine 11 is started, the driving rotation of the turbine shaft 15 is started, and the combustor 13 is operated when the rotation speed of the turbine shaft 15 exceeds a preset first predetermined rotation speed. By opening the on-off valve 62 simultaneously with ignition, the compressed air extracted from the fourth stage casing 12d of the compressor 12 passes through the extraction line 51d and the bypass line 61 to the fourth stage (each stationary blade) in the turbine 14. Supplied and discharged as a swirling component air stream from the slit of the stationary blade toward the moving blade 57. Thereafter, when the rotational speed of the turbine shaft 15 exceeds a preset second predetermined rotational speed, the on-off valve 62 is closed so that the compressed air is discharged to the rear stage of the turbine 14 by the bypass line 61. Stop. Then, the start of the turbine shaft 15 is stopped, the amount of fuel input to the combustor 13 is increased, the speed is increased to the rated rotational speed, and then the steady operation is performed.

  As described above, in the gas turbine and the combined power generation system according to the sixth embodiment, the bypass line 61 that supplies a part of the compressed air extracted from the compressor 12 to the rear stage of the turbine 14 when the gas turbine 11 is started is provided. An open / close valve 62 is provided in the bypass line 61.

  Accordingly, the gas turbine 11 is supplied with fuel by the combustor 13 to the compressed air compressed by the compressor 12 and burns, and the generated combustion gas is supplied to the turbine 14 to obtain rotational power. , The compressed air extracted from the compressor 12 is supplied to the rear stage (fourth stage) of the turbine 14 through the extraction line 51d and the bypass line 61, so that the amount of air in the rear stage of the turbine 14 is increased. Can be shifted from the compression operation mode to the turbine operation mode, the turbine generation torque can be increased and the speed-up rate can be increased. As a result, the start-up time of the gas turbine 11 and the combined power generation system can be shortened, thereby purifying exhaust gas. Reduction in efficiency and increase in fuel cost can be suppressed.

  In Examples 4, 5, and 6 described above, when the gas turbine 11 is started and the rotational speed of the turbine shaft 15 becomes equal to or higher than the first predetermined rotational speed, the combustor 13 is operated to ignite and simultaneously open and close. The valves 55 and 62 are opened, and the compressed air extracted from the compressor 12 is supplied to the rear stage of the turbine 14 through the bypass lines 55 and 61. The compressed air of the compressor 12 may be supplied to the rear stage of the turbine 14 through the bypass lines 55 and 61. In this case, the compressed air extracted from the compressor 12 may be supplied not only to the fourth stage in the turbine 14 but also to the third stage.

  In each of the above-described embodiments, the combined power generation system is configured by the gas turbine 11, the exhaust heat recovery boiler 20, and the steam turbine 22. However, the exhaust heat recovery boiler 20 may be an exhaust reheat boiler, a supercharged boiler, or a water supply It is good also as a heating boiler etc. It is good also as a regenerator (heat exchanger).

  The gas turbine, the gas turbine starting method, and the combined power generation system according to the present invention can suppress a decrease in exhaust purification efficiency and an increase in fuel cost by shortening the starting time, and any kind of gas turbine It can also be applied to a combined power generation system.

1 is a schematic configuration diagram illustrating a combined power generation system to which a gas turbine according to Embodiment 1 of the present invention is applied. It is a graph showing the change of the turbine speed and expansion ratio at the time of starting of the gas turbine of Example 1. It is a graph showing the change of the turbine speed and expansion ratio at the time of starting of the gas turbine in the combined power generation system to which the gas turbine according to the second embodiment of the present invention is applied. It is a schematic block diagram showing the combined power generation system to which the gas turbine which concerns on Example 3 of this invention was applied. It is a schematic block diagram showing the gas turbine which concerns on Example 4 of this invention. It is the schematic showing the stationary blade and moving blade explaining the extraction line in the gas turbine of Example 4. FIG. It is the schematic showing the stationary blade and moving blade explaining the extraction line in the gas turbine which concerns on Example 5 of this invention. It is a schematic block diagram showing the gas turbine which concerns on Example 6 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Gas turbine 12 Compressor 13 Combustor 14 Turbine 15 Turbine shaft 16 Generator (starting motor)
20 Exhaust heat recovery boiler 24 Steam turbine 31 Exhaust gas recirculation line 32 Open / close valve 41 Exhaust gas discharge line 42 Open / close valve 51a, 51b, 51c, 51d Extraction line 53b, 53c, 53d Cooling line 54, 61 Bypass line 55, 62 Open / close Valve 56 Stator blade 59, 60 Slit

Claims (14)

  In a gas turbine that obtains rotational power by supplying fuel to compressed air compressed by a compressor and burning it with a combustor and supplying the generated combustion gas to the turbine, at least of the exhaust gas discharged from the turbine at startup An exhaust gas recirculation line for recirculating a part of the gas to the compressor is provided.   In a gas turbine that obtains rotational power by supplying fuel to compressed air compressed by a compressor and burning it with a combustor and supplying the generated combustion gas to the turbine, at least of the exhaust gas discharged from the turbine at startup A gas turbine, characterized in that an exhaust gas discharge line that partially opens to the atmosphere is provided.   The gas turbine according to claim 1 or 2, wherein an opening / closing valve is provided in the exhaust gas recirculation line or the exhaust gas discharge line, and when the turbine shaft reaches a preset first predetermined rotation speed or more, A gas turbine that operates the combustor and opens the on-off valve.   3. The gas turbine according to claim 1, wherein an open / close valve is provided in the exhaust gas recirculation line or the exhaust gas discharge line, and the open / close valve is opened at the start of driving rotation of the turbine shaft. 4. Turbine.   5. The gas turbine according to claim 3, wherein the on-off valve is closed when the turbine shaft reaches a preset second predetermined number of revolutions or more.   High-pressure fuel and high-pressure air are combusted in a gas turbine, and electric power is generated by the generated combustion gas. High-temperature exhaust gas discharged from the gas turbine is sent to a boiler to generate steam, and the generated steam is Exhaust gas recirculation that recycles at least part of the exhaust gas discharged at the start of the gas turbine to a compressor in a combined power generation system that generates power by sending it to a steam turbine and returns the cooled feed water to a boiler and overheats A combined power generation system characterized in that a line is provided.   High-pressure fuel and high-pressure air are combusted in a gas turbine, and electric power is generated by the generated combustion gas. High-temperature exhaust gas discharged from the gas turbine is sent to a boiler to generate steam, and the generated steam is In a combined power generation system in which power is sent to a steam turbine to generate power, and the cooled feed water is returned to the boiler and overheated, an exhaust gas discharge line is provided to open at least a part of the exhaust gas discharged at the start of the gas turbine to the atmosphere. Combined power generation system characterized by that.   In a gas turbine that obtains rotational power by supplying fuel to a compressed air compressed by a compressor by a combustor and supplying the generated combustion gas to the turbine, the compressed air compressed by the compressor at the time of start-up A gas turbine comprising a bypass line for supplying a part to a rear stage of the turbine.   9. The gas turbine according to claim 8, wherein an opening / closing valve is provided in the bypass line, and the combustor is operated and the opening / closing valve is operated when the turbine shaft reaches a first predetermined rotation speed or higher. A gas turbine that is opened.   The gas turbine according to claim 8, wherein an open / close valve is provided in the bypass line, and the open / close valve is opened at the start of driving rotation of the turbine shaft.   11. The gas turbine according to claim 9, wherein the on-off valve is closed when the turbine shaft reaches a preset second predetermined number of revolutions or more.   The gas turbine according to any one of claims 8 to 11, wherein the bypass line is connected to a stationary blade in a rear stage of the turbine, and the compressed air is used as a swirling component air flow to the stationary blade. A gas turbine characterized in that a slit is provided for discharging toward the front.   In a gas turbine that obtains rotational power by supplying fuel to compressed air compressed by a compressor and burning it with a combustor and supplying the generated combustion gas to the turbine, at least of the exhaust gas discharged from the turbine at startup A method for starting a gas turbine, wherein a part of the gas turbine is opened to the atmosphere.   In a gas turbine that obtains rotational power by supplying fuel to a compressed air compressed by a compressor by a combustor and supplying the generated combustion gas to the turbine, the compressed air compressed by the compressor at the time of start-up A method for starting a gas turbine, wherein a part of the gas turbine is supplied to a rear stage of the turbine.

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