JP5751982B2 - Power plant and its remodeling method - Google Patents

Description

  The present invention relates to a combined power generation plant including a gas turbine and a steam turbine driven by exhaust heat of the gas turbine, and a method for remodeling the combined power plant.

  In a combined cycle power plant equipped with a gas turbine and a steam turbine, a steam turbine is driven using exhaust heat of the gas turbine using an exhaust heat recovery boiler. In such a power plant, during the start-up operation, the temperature of the members constituting the exhaust heat recovery boiler and the steam turbine rises rapidly due to the exhaust of the gas turbine. For example, in the exhaust heat recovery boiler, the temperature rapidly rises from a temperature near normal temperature (around 40 ° C.) to around 600 ° C. by starting the gas turbine. For this reason, these constituent members may suddenly undergo thermal distortion and be damaged by heat. In order to prevent this, the rapid output increase of the gas turbine is suppressed.

  Patent Document 1 discloses means for suppressing the rapid temperature rise in the exhaust heat recovery boiler and promoting the start-up operation of the combined cycle power plant. Hereinafter, this means will be described with reference to FIG. In FIG. 9, an exhaust passage of the gas turbine is formed inside the exhaust heat recovery boiler 200. A heat pipe 204 is disposed in the exhaust passage, and the heat pipe 204 extends outside through a partition wall of the exhaust heat recovery boiler 200 and an inner flange 202 provided in the partition wall. A fan 206 is provided outside the exhaust heat recovery boiler 100, and the fan 206 is configured to send cold air to the heat pipe 202.

  A gate 212 is rotatably provided on an outer flange 208 provided at an end of the heat pipe 204 via a hinge 210, and the flow area of the cold air can be changed by the gate 212. A heat couple 214 for detecting the temperature of the gas turbine exhaust and the heat pipe 204 is disposed inside and outside the exhaust heat recovery boiler 200. The temperature detection value of the thermocouple 214 is sent to the controller 216. The heat pipe 204 is sealed with a working fluid or a coolant.

The working fluid or coolant absorbs and evaporates the heat of the gas turbine exhaust inside the exhaust heat recovery boiler 200 and is cooled and condensed outside the exhaust heat recovery boiler 200. The controller 216 controls the rotational speed of the fan 206 and the angle θ of the gate 112 according to the gas turbine exhaust and the temperature of the heat pipe 204 to adjust the cooling effect of the heat pipe 204.

Gas turbine combustors include a diffusion combustion type and a premixed combustion type. Those premixed combustion scheme can reduce NO _X emissions as compared to that of the diffusion combustion system. When the load on the gas turbine decreases from the rated load, the combustion temperature also decreases at the same time. With combustor premixing combustion system, although NO _X emissions decrease, in some combustion temperature below which may CO exceeds the allowable level. Therefore, during low load operation is made to be used as a diffusion combustion system, compared with the premixed combustion system, comprising a number NO _X emissions. Therefore, it is desirable to be able to expand the low load operation region where the premixed combustion method can be used.

  The gas turbine turn-down operation (partial load operation or low load operation) has a lower load limit because there are exhaust emission requirements, exhaust temperature, generation of vibration noise due to pressure pulsation, and several other operation limits. From the viewpoint of power demand, gas turbines are often subject to large load fluctuations, and therefore it is desired to enable flexible operation that can tolerate wide load fluctuations. Otherwise, frequent shutdowns and restarts are required, thereby shortening the life of the gas turbine hardware.

  Patent Document 2 discloses means that can expand the low-load operation range of a gas turbine that uses a premixed combustion system. This means is provided with a partition plate that restricts the exhaust flow rate in the exhaust passage of the gas turbine, and the controller operates the partition plate to reduce the cross-sectional area of the exhaust passage so that the exhaust temperature can be set to a desired temperature during low-load operation. The engine is shifted to the target low-load operation while maintaining the exhaust pressure below the threshold value.

JP 2010-31868 A JP 2009-250236 A

  Since the exhaust temperature rise suppression means disclosed in Patent Document 1 requires the installation of a heat pipe and a fan, the equipment cost becomes expensive. In addition, it is necessary to secure a space for a heat pipe and a fan disposed outside the exhaust heat recovery boiler, and it is necessary to make a large installation space for the exhaust heat recovery boiler. Furthermore, since a fan and a gate are provided, the facility becomes large and it is necessary to drive the fan at all times. Therefore, there is a problem that the fan power increases and the operation cost becomes high.

  If the exhaust flow rate of the gas turbine is controlled to shift to a low load operation, the exhaust temperature rises. Therefore, the temperature of the high temperature part of the gas turbine rises and there is a risk of thermal damage due to thermal strain. The low-load operation region expanding means disclosed in Patent Document 2 does not take measures against thermal damage that is caused to the parts and equipment that constitute the gas turbine.

  In view of the problems of the prior art, a first object of the present invention is to realize an exhaust temperature rise suppression means that can be easily modified even when the equipment is not large and is provided in existing equipment. The second object is to eliminate the risk of thermal damage of the gas turbine hot part during partial load operation or low load operation.

  In order to achieve this object, the power plant of the present invention is driven by a gas turbine, an exhaust heat recovery boiler that generates heat by exchanging heat with the exhaust of the gas turbine, and steam generated by the exhaust heat recovery boiler. In a power plant including a steam turbine and a gas turbine and a generator driven by the steam turbine, an inflow heat amount reducing device provided in an inlet side exhaust passage in the exhaust heat recovery boiler, and an exhaust gas downstream of the inflow heat amount reducing device A temperature sensor provided in the passage, and a temperature rise suppression mechanism comprising a first controller that operates the inflow heat quantity reduction device so that the rate of rise of the exhaust gas temperature detected by the temperature sensor does not exceed a threshold value; A variable opening device that is provided in the exhaust passage and makes the opening of the exhaust passage variable, gas turbine output, gas turbine exhaust pressure and temperature detection values, and Inputs the temperature detection value of the high temperature part of the gas turbine, and selects the input value closest to the threshold value among these input values, and the opening variable device so that the input value selected by the minimum selector does not exceed the threshold value And a load control mechanism including a second controller that operates the controller.

  The temperature rise suppression mechanism of the plant of the present invention limits the amount of heat retained in the exhaust flowing into the exhaust heat recovery boiler by providing an inflow heat amount reducing device in the inlet side exhaust passage in the exhaust heat recovery boiler. Thereby, the rapid temperature rise of the exhaust heat recovery boiler can be suppressed, and the heat damage of the constituent parts of the exhaust heat recovery boiler and the steam turbine can be prevented. Moreover, since it is not necessary to arrange equipment outside the exhaust heat recovery boiler, it does not require extensive modification of the existing equipment even when it is attached to the existing equipment without expanding the installation space of the exhaust heat recovery boiler. In addition, since a threshold is set for the rising speed of the downstream exhaust temperature of the inflow heat quantity reducing device and the inflow heat quantity reducing device is operated according to the rising speed, the exhaust heat recovery boiler and the downstream side thereof are provided. It is possible to stably control the temperature rise of the components of the steam turbine.

  The load control mechanism of the plant of the present invention adds the temperature of the hot part of the gas turbine to the control parameters in addition to the gas turbine output and the pressure and temperature of the gas turbine exhaust, and controls the load so that the temperature of the hot part does not exceed the threshold value. To do. Therefore, in addition to providing an opening degree variable device that makes the opening degree of the exhaust passage variable so that the operable low load region can be expanded, the temperature rise of the high temperature part can be avoided during low load operation, Thermal damage of the constituent parts can be prevented.

  The bypass stack (bypass chimney) is mainly used when the gas turbine is operated independently during maintenance inspection of the exhaust heat recovery boiler or the steam turbine. In such a configuration, a part of the exhaust gas is discharged from the bypass stack to the outside, so that the heat amount of the exhaust gas introduced into the exhaust heat recovery boiler can be reduced. In the present invention plant, a bypass stack connected to an exhaust passage of a gas turbine, an exhaust branch passage that branches from the exhaust passage and sends exhaust gas to an exhaust heat recovery boiler before the bypass stack, an exhaust passage and an exhaust branch passage, And a damper device that adjusts the flow rate of the exhaust gas sent to the bypass stack or the exhaust heat recovery boiler, and the inflow heat quantity reduction device adjusts the opening of the inlet side exhaust passage in the exhaust heat recovery boiler. The exhaust heat quantity introduced into the exhaust heat recovery boiler may be adjustable.

  Accordingly, the flow rate of the exhaust gas flowing into the exhaust heat recovery boiler can be controlled in two stages, that is, the damper device and the inflow heat amount reducing device, and the retained heat amount of the inflowing exhaust gas can be controlled. The damper device has an angular region in which the exhaust flow rate cannot be controlled. By supplementing the flow rate control in this region with the inflow heat amount reducing device, the introduced exhaust heat amount can be accurately controlled. In addition, it is possible to easily remodel existing equipment equipped with a gas turbine bypass stack, thereby reducing the cost of remodeling. Moreover, the operating power of the inflow heat amount reducing device can be reduced as compared with Patent Document 1 in which the fan is always operated.

  In the plant of the present invention, the inflow heat quantity reducing device is formed by arranging a large number of strip-shaped plates so as to be rotatable about the longitudinal axis, and rotating the strip-shaped plates to adjust the gaps between the strip-shaped plates. The opening of the inlet side exhaust passage of the exhaust heat recovery boiler may be adjusted. As a result, the flow rate of exhaust gas flowing into the exhaust heat recovery boiler and the amount of retained heat can be controlled by simple and low-cost means. Further, the flow direction of the exhaust gas can be directed to the inner wall side of the exhaust heat recovery boiler depending on the angle of the belt-like plate. This makes it possible to increase the time required for the exhaust flow path to bend and reach the heat exchanger provided on the downstream side of the exhaust passage, thereby increasing the exhaust cooling effect.

  In the plant according to the present invention, the inflow heat amount reducing device is configured by a nozzle that injects cooling water into the exhaust passage on the inlet side of the exhaust heat recovery boiler, and the first controller responds to the rising speed of the exhaust temperature detected by the temperature sensor. It is preferable that the cooling water injection amount be adjusted. As a result, a simple and low-cost configuration in which the drive unit and the power required for the drive unit are reduced can be achieved. In addition, since the exhaust is cooled using the latent heat of the cooling water, the cooling effect can be increased.

  In the plant of the present invention, a gas turbine inlet part into which combustion gas flows and a turbine blade such as a stationary blade and a moving blade are selected as a high temperature part of the gas turbine as a temperature monitoring part. By detecting the temperature of the cooling air introduced into the drilled cooling holes, it may be used as a measure of the temperature of the turbine blades. Thereby, the thermal damage of the component part of the gas turbine whole including a component part can be prevented.

  The power plant remodeling method according to the present invention generates steam by exchanging heat with a gas turbine, a bypass stack connected to an exhaust passage of the gas turbine, and an exhaust sent through an exhaust branch passage branched from the exhaust passage. An exhaust heat recovery boiler, a steam turbine driven by steam generated in the exhaust heat recovery boiler, a gas turbine and a generator driven by the steam turbine, and a branch portion between the exhaust passage and the branch exhaust passage, In a power plant remodeling method comprising a damper device for adjusting a flow rate of exhaust gas sent to a bypass stack or an exhaust heat recovery boiler, a step of providing an inflow heat amount reducing device in an inlet side exhaust passage in the exhaust heat recovery boiler, inflow heat amount reduction A step of providing a temperature sensor in the exhaust passage on the downstream side of the device, and a flow rate so that the rate of rise of the exhaust temperature detected by the temperature sensor does not exceed the threshold value A temperature rise suppression mechanism installation step comprising a step of providing a first controller for operating the heat quantity reduction device, a step of providing an opening variable device for varying the opening of the exhaust passage in the exhaust passage of the gas turbine, a gas turbine output, Input the detected pressure and temperature values of the gas turbine exhaust and the detected temperature value of the high temperature part of the gas turbine, and provide a minimum selector that selects the input value closest to the threshold value among these input values, and select with the minimum selector And a load control mechanism installation step including a step of providing a second controller for operating the opening degree varying device so that the input value does not exceed the threshold value.

  As a result, an inflow heat amount reducing device, a variable opening device, and these control devices are attached to an existing power plant equipped with a damper device that sends the bypass stack and gas turbine exhaust to the bypass stack or the exhaust heat recovery boiler. Thus, the power plant of the present invention can be remodeled without requiring significant remodeling. Therefore, the cost and labor required for remodeling can be saved.

  According to the power plant of the present invention, a gas turbine, an exhaust heat recovery boiler that exchanges heat with the exhaust of the gas turbine to generate steam, a steam turbine that is driven by the steam generated in the exhaust heat recovery boiler, and a gas In a power plant including a turbine and a generator driven by a steam turbine, an inflow heat amount reducing device provided in an inlet side exhaust passage in an exhaust heat recovery boiler, and provided in a downstream exhaust passage of the inflow heat amount reducing device A temperature rise suppression mechanism comprising a temperature controller and a first controller for operating the inflow heat quantity reduction device is provided in the exhaust passage of the gas turbine so that the rise rate of the exhaust temperature detected by the temperature sensor does not exceed a threshold value. , Variable opening device for variable exhaust passage opening, gas turbine output, gas turbine exhaust pressure and temperature detection values, and gas turbine high temperature A minimum selector that selects an input value that is closest to the threshold value among these input values, and a variable opening device that operates the opening degree varying device so that the input value selected by the minimum selector does not exceed the threshold value. Since the load control mechanism consisting of two controllers is provided, the output restriction of the gas turbine in the combined cycle power plant can be relaxed while avoiding the thermal damage of the parts constituting the exhaust heat recovery boiler and the steam turbine, The low-load operation area can be expanded without suffering thermal damage to the gas turbine components. Such a function can be realized by a low-cost means, and can be realized without requiring significant modification to the existing equipment.

  The power plant remodeling method according to the present invention generates steam by exchanging heat with a gas turbine, a bypass stack connected to an exhaust passage of the gas turbine, and an exhaust sent through an exhaust branch passage branched from the exhaust passage. An exhaust heat recovery boiler, a steam turbine driven by steam generated in the exhaust heat recovery boiler, a gas turbine and a generator driven by the steam turbine, and a branch portion between the exhaust passage and the branch exhaust passage A step of providing an inflow heat quantity reducing device in an inlet side exhaust passage in the exhaust heat recovery boiler, in a power plant remodeling method comprising a damper device for adjusting a flow rate of exhaust gas sent to the bypass stack or the exhaust heat recovery boiler, The step of providing a temperature sensor in the downstream exhaust passage of the reduction device, and the rising speed of the exhaust temperature detected by the temperature sensor does not exceed the threshold A temperature rise suppression mechanism installation step comprising a step of providing a first controller for operating the inflow heat quantity reduction device, a step of providing an opening variable device for varying the opening of the exhaust passage in the exhaust passage of the gas turbine, a gas turbine output A gas turbine exhaust pressure and temperature detection value, and a temperature detection value of a high temperature portion of the gas turbine, and a minimum selector for selecting an input value closest to the threshold among the input values, and a minimum selector An existing power plant including a bypass stack and a damper device, since the load control mechanism is provided with a step of providing a second controller for operating the opening degree varying device so that the selected input value does not exceed the threshold value. On the other hand, the plant of the present invention can be realized by simple and low-cost modification.

1 is an overall configuration diagram of a combined cycle power plant according to a first embodiment of the apparatus of the present invention. It is a diagram which shows an example of the opening degree control method of a damper apparatus in 1st Embodiment. It is a block diagram which shows the control circuit of the load control mechanism of 1st Embodiment. It is a block diagram which shows the feedback circuit of the said control circuit. It is a top view which shows the inflow heat amount reducing apparatus of 3rd Embodiment of this invention apparatus. FIG. 6 is a front sectional view taken along line AA in FIG. 5. It is a top view sectional view showing the inflow heat amount reducing device of a 4th embodiment of the present invention device. In 4th Embodiment, it is a diagram which shows the control method of the cooling water spray amount. It is the schematic which shows the conventional inflow heat amount reducing apparatus.

  Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
A first embodiment in which the present invention is applied to a combined cycle power plant will be described with reference to FIGS. In FIG. 1, the combined cycle power plant 10 according to the present embodiment includes a gas turbine 14, a compressor 16, and a generator 16 that share a single rotating shaft 12. Further, the generator 16 is provided with an output detector 20 for detecting the power generation output. The supply air a is taken into the compressor 16, compressed, and sent to the combustor 22. A fuel gas supply pipe 24 is connected to the combustor 22, and the fuel gas f is supplied from the fuel gas supply pipe 24. In the combustor 22, the supply air a and the fuel gas f are mixed, and the mixed gas is ignited to generate high-temperature combustion gas, which is introduced into the gas turbine 14.

  A temperature sensor 26 is attached to the inlet portion 14a of the gas turbine 14 into which the combustion gas is introduced. The combustion gas drives the gas turbine 14, rotates the rotating shaft 12 at a high speed, and generates power by the generator 18. A part of the supply air a sucked into the compressor 16 is branched into the branch path 28 and introduced into the air cooler 30, where it is cooled by exchanging heat with the cooling water w. The cooled supply air a is introduced into the rotor (not shown) of the gas turbine 14 from the branch pipe 28a to cool the rotor. The other cooling air is introduced from the branch pipe 28 b into cooling holes (not shown) drilled in the turbine blade 32 such as a stationary blade and a moving blade, and cools the turbine blade 32.

A temperature sensor 36 is attached to a recovery pipe 34 that recovers cooling air from the turbine blades 32.
By detecting the temperature of the recovered cooling air with the temperature sensor 36, the temperature of the turbine blade 32 can be detected. As described above, in the gas turbine, the temperature sensors 26 and 36 are provided in the gas turbine inlet portion 14a and the turbine blade 32 that are particularly high in temperature, and the temperatures of these high temperature portions are detected.

  An exhaust branch passage 40 branches into the exhaust passage 38 of the gas turbine 14 in the middle. The exhaust passage 38 is connected to the bypass stack 42, and the exhaust branch passage 40 is connected to the inlet side of the exhaust passage 44 a formed in the exhaust heat recovery boiler 44. A branch portion between the exhaust passage 38 and the exhaust branch passage 40 is provided with a damper device 46 that is made of a rotatable damper and distributes the exhaust e to the bypass stack 42 or the exhaust heat recovery boiler 44. The inclination angle θ <b> 1 of the damper device 46 is changed by the driving device 48, and thereby the amount of distribution to the bypass stack 42 or the exhaust heat recovery boiler 44 is adjusted. The driving device 48 is controlled by the controller 50.

  Inside the exhaust heat recovery boiler 44, a heat exchange tube group 44b is disposed downstream of the inlet side exhaust passage 44a. Condensate condensed in the condenser 52 flows into the heat exchange pipe group 44b from the pipe 51, and is evaporated by exchanging heat with the exhaust. The evaporated steam is supplied to the steam turbine 56 through the pipe 54 and drives the steam turbine 56. The steam turbine 56 and the generator 58 share the rotating shaft 60, and the generator 58 generates electric power when the steam turbine 56 is driven. The steam after driving the steam turbine 56 is condensed in the condenser 52 and then introduced into the heat exchange pipe 44b again.

  An exhaust introduction amount control device 62 is provided on the inlet side of the exhaust passage 44 a in the exhaust heat recovery boiler 44. The exhaust gas introduction amount control device 62 is disposed so as to be able to reciprocate in the direction of the arrow through the partition wall 44c of the exhaust heat recovery boiler 44, and a partition plate 64 that makes the inlet side flow passage area of the exhaust passage 44a variable. It is comprised with the drive device 66 which reciprocates 64. The driving device 66 is controlled by the controller 50.

  A partition plate 68 is provided in the exhaust passage 38 upstream of the damper device 46. The partition plate 68 is disposed through the partition wall of the exhaust passage 38 and is moved by the driving device 70 to change the cross-sectional area of the exhaust passage 38. The partition plate 68 and the driving device 70 constitute a load control mechanism 71. The driving device 70 is controlled by the controller 50. A pressure sensor 72 that detects the pressure of the exhaust e and a temperature sensor 74 that detects the temperature of the exhaust e are provided in the upstream exhaust passage 38 of the partition plate 68. In the exhaust heat recovery boiler 44, a temperature sensor 76 for detecting the exhaust temperature of the exhaust passage 44a on the downstream side of the partition plate 64 is provided. Detection values of the output sensor 20, the temperature sensors 26, 36, 74, 76 and the pressure sensor 72 are input to the controller 50.

  In such a configuration, the amount of exhaust gas flowing into the exhaust heat recovery boiler 44 from the exhaust passage 38 is doubly adjusted by the angle θ1 of the damper device 46 and the partition plate 64. When the angle θ1 of the damper device 46 is 10 ° or less or 90 ° or more, the flow rate adjustment capability of the damper device 46 decreases. This decrease in flow rate adjustment capability can be compensated by the operation of the partition plate 64. The exhaust temperature is detected by the temperature sensor 76, and the opening degree of the exhaust passage 44a by the partition plate 64 is adjusted by the controller 50 according to the exhaust gas temperature rising speed (the exhaust gas temperature is a differential value with respect to time) calculated from the detected value. . Then, the exhaust inflow amount passing through the partition plate 64, that is, the retained heat amount of the inflowing exhaust gas is controlled so that the exhaust temperature rising speed detected by the temperature sensor 76 does not exceed the set threshold value.

  FIG. 2 shows an example of opening degree control of the exhaust passage 38 by the damper device 46 with respect to the exhaust temperature change amount (dT / dt) of the exhaust temperature detected by the temperature sensor 74. In the figure, in the region A, in order to prevent damage to the seal mechanism of the damper device 46, the minute opening degree control is not performed. In the region B, the amount of exhaust heat introduced into the exhaust passage 44a is reduced by increasing the decrease rate of the damper opening degree from the exhaust temperature change amount (dT / dt). In a region C where the damper opening is 50% or less, the exhaust flow rate flowing into the bypass stack 42 is rapidly reduced. Therefore, in order to prevent overshoot of the damper opening, the decrease rate of the damper opening is made smaller than the exhaust temperature change amount (dT / dt). In the region D, the minute opening degree control is not performed in order to prevent damage to the seal mechanism of the damper device 46.

  While controlling the opening degree of the damper device 46, the partition plate 64 is driven to control the opening degree of the exhaust passage 44a, and the exhaust gas temperature change amount (dT / dt) detected by the temperature sensor 76 is set. By holding below the threshold value, the temperature rise of the exhaust heat recovery boiler 44 and the components of the steam turbine 56 disposed downstream of the exhaust heat recovery boiler 44 is suppressed, and thermal damage is prevented.

  Next, the control circuit of the load control mechanism 71 of this embodiment will be described with reference to FIGS. FIG. 3 shows a control circuit 80 that controls the driving device 70. The control circuit 80 is built in the controller 50. When the load on the gas turbine 14 decreases and the gas turbine output needs to follow it, a control signal is transmitted from the feedback circuit 82 to the drive device 70. The control signal is for inserting the partition plate 68 deeply into the exhaust passage 38 to reduce the cross-sectional area of the exhaust passage 38, and this control signal is transmitted to the drive device 70 via the minimum selector 92.

  By inserting the partition plate 68, the exhaust pressure increases. When the exhaust pressure rises and approaches a pressure suitable for controlling the exhaust pressure, an exhaust pressure control signal is transmitted from the feedback circuit 84 to the drive device 70, and the exhaust pressure is set to a pressure suitable for the target load. When the cross-sectional area of the exhaust passage 38 decreases, the exhaust gas temperature increases as the exhaust pressure increases. Therefore, since the temperature of the hot part of the gas turbine rises, the hot part must be protected.

  Therefore, in the present embodiment, the gas turbine inlet portion 14a and the turbine blade 32 are selected as the high temperature portions, the temperatures of these high temperature portions are monitored, and control is performed so as not to exceed the set value when approaching the set value. . In FIG. 3, the gas turbine output is detected by the output sensor 20, the exhaust pressure is detected by the pressure sensor 72, the gas turbine inlet temperature is detected by the temperature sensor 26, and the disk cavity temperature (turbine blade temperature) is detected by the temperature sensor 36. The exhaust temperature is detected by the temperature sensor 74.

  Hereinafter, the configuration of the feedback circuit 82 will be described with reference to FIG. In FIG. 4, the gas turbine output detected by the output sensor 20 and the target value of the gas turbine output are input to the comparator 94. The comparator 94 sends these differences to the PI calculator 96, and the PI calculator 96 calculates the difference PI (proportional + integral), and transmits the obtained control signal to the driving device 70 via the minimum selector 92. .

  For each parameter shown in FIG. 3, feedback circuits 84 to 90 having the same configuration as the feedback circuit 82 are provided. The minimum selector 92 selects a control signal transmitted from each feedback circuit, and transmits the selected control signal to the driving device 70. The minimum selector 92 selects the minimum control signal calculated by each feedback circuit. That is, a control signal of a parameter that is closest to the set value and that is most likely to reach the set value is selected and transmitted to the drive device 70.

  According to the present embodiment, the exhaust heat recovery boiler 44 is provided with the exhaust gas introduction amount control device 62, and the damper device 46 and the exhaust gas introduction amount control device 62 control the flow rate of exhaust gas flowing into the exhaust heat recovery boiler 44, and the temperature sensor 76. Since the rising speed of the exhaust gas temperature downstream of the partition plate 64 detected in step S1 can be suppressed to a threshold value or less, the exhaust heat recovery boiler 44 and the rapid temperature of the components of the steam turbine 56 on the downstream side of the exhaust heat recovery boiler 44 are reduced. The rise can be suppressed. Therefore, it is possible to prevent thermal damage to the constituent parts of the exhaust heat recovery boiler 44 and the steam turbine 56, and it is possible to relax the output increase restriction of the gas turbine.

  Further, when installing the exhaust gas introduction amount control device 62, it is not necessary to expand the installation space of the exhaust heat recovery boiler 44, and the exhaust gas introduction amount control device itself is compact, so that the equipment cost can be reduced. Further, no large power is required to operate the partition plate 64.

  In addition, since the load control mechanism 71 is provided, the low load operation region can be expanded, and thus frequent operation stop is not required, so that stable operation is possible and the life of the gas turbine 14 can be extended. Furthermore, since the temperatures of the inlet part 14a and the turbine blade 32, which are constituent parts of the gas turbine 14, can always be kept below the set value, thermal damage of the gas turbine constituent parts can be prevented.

(Embodiment 2)
Next, an embodiment of the method of the present invention will be described with reference to FIG. The present embodiment is an example in which the combined cycle power plant 10 according to the first embodiment is modified from an existing combined cycle power plant. The existing combined cycle type power plant includes a bypass stack 42, an exhaust passage 38, an exhaust branch passage 40, and a damper device in addition to the main equipment such as the gas turbine 14, the exhaust heat recovery boiler 44, the steam turbine 56 and the generators 16 and 58. 46 is provided in advance.

In the remodeling process of the present embodiment, an exhaust flow rate control device 62 including a partition plate 64 and a drive device 66 is provided in the inlet side exhaust passage 44 a of the exhaust heat recovery boiler 44. Next, a load control mechanism 71 including a partition plate 68 and a driving device 70 is provided. Next, a control function including sensors associated with the exhaust flow control device 62 and the load control mechanism 71 and a control circuit 80 for controlling the exhaust flow control device 62 and the load control mechanism 71 is added to the controller 50.

  According to this embodiment, a power plant according to the present invention can be manufactured without requiring significant modification to an existing combined cycle power plant. Therefore, the cost and labor required for remodeling can be saved.

(Embodiment 3)
A second embodiment of the apparatus of the present invention will be described with reference to FIGS. The exhaust gas introduction amount control device 100 of the present embodiment has a large number of strip-like plates 102 arranged in parallel in the vertical direction. A shaft 104 having a circular cross section is formed at the center of the belt-like plate 102. The shaft 104 is rotatably supported by bases 106 and 108 provided on the top and bottom surfaces of the housing of the exhaust heat recovery boiler 44. A pair of drive bars 110a and 110b are arranged in the horizontal direction inside the base portion 108. The drive bars 110a and 110b are arranged in parallel to each other and connected to the shaft 104 of each strip plate 102.

  One end of each of the drive bars 110a and 110b extends outside the housing of the exhaust heat recovery boiler 44. A motor 112 is attached outside the housing of the exhaust heat recovery boiler 44. The ends of the drive bars 110a and 110b are connected to both sides of the rotating shaft 112a of the motor 112, respectively. As a result, when the rotation shaft 112a rotates, the drive bars 110a and 110b move in opposite directions to rotate the shaft 104 as indicated by arrows. As a result, the gap between the strips 102 can be adjusted, and the amount of exhaust gas introduced into the exhaust passage 44a of the exhaust heat recovery boiler 44 can be adjusted. The configuration other than the exhaust gas introduction amount control device 100 is the same as that of the first embodiment. The driving of the motor 112 is controlled by the controller 50.

  According to the present embodiment, a simple and low-cost exhaust flow rate reducing device can be realized. Further, by inclining the belt-like plate 102 with respect to the exhaust inflow direction, the exhaust can be bent to the wall side of the housing of the exhaust heat recovery boiler 44, and the exhaust passage leading to the heat exchange tube group 44b can be lengthened. Therefore, the amount of heat dissipated in the exhaust can be increased and the cooling effect of the exhaust e can be increased before the exhaust reaches the exchange tube group 44b.

(Embodiment 4)
Next, a third embodiment of the device of the present invention will be described with reference to FIGS. The inflow heat quantity reduction device 120 of the present embodiment has a cooling water introduction pipe 122 disposed in the housing of the exhaust heat recovery boiler 44. A number of nozzles 124 are attached to the cooling water introduction pipe 122. The opening of the nozzle 124 is directed downstream in the flow direction of the exhaust e. A cooling water supply pump 126 is interposed in the cooling water introduction pipe 122. The configuration other than the inflow heat amount reducing device 120 is the same as that of the first embodiment. The controller 50 controls the driving device 128 of the cooling water supply pump 126, and the controller 50 controls the amount of cooling water sprayed from the nozzle 124.

  In such a configuration, the exhaust water e can be cooled by supplying the cooling water w to the cooling water introduction pipe 122 and spraying it from the nozzle 124. As a result, it is possible to realize a simple and low-cost inflow heat amount reducing device that reduces the drive unit and the power required for the drive unit. In addition, since the exhaust is cooled using the latent heat of the cooling water, the cooling effect can be increased. Furthermore, the nozzle 124 can be prevented from being clogged by directing the opening of the nozzle 124 to the downstream side in the flow direction of the exhaust e.

  FIG. 8 shows a control method of the cooling water spray amount with respect to the temperature change amount (dT / dt) of the exhaust e detected by the temperature sensor 76. In the region E where the temperature change amount (dT / dt) is very small, in order to avoid undershoot, the cooling water is not sprayed. In the region F, a positive correlation is given to the temperature change amount (dT / dt). In the region G where the temperature change amount (dT / dt) is large, an upper limit is set for the spray amount from the viewpoint of preventing damage to the components of the exhaust heat recovery boiler 44 due to condensation of steam or the like.

  While performing the spray amount control, the exhaust heat temperature change amount (dT / dt) is kept below the threshold value, so that the exhaust heat recovery boiler 44 and the components of the steam turbine 56 disposed on the downstream side of the exhaust heat recovery boiler 44 Suppresses temperature rise and prevents thermal damage.

  According to the present invention, in the combined cycle type power plant, the output restriction can be relaxed at the start of the gas turbine by a simple and low-cost means, and the low load operation region can be expanded. Moreover, the thermal damage of the component part of a gas turbine can be prevented.

DESCRIPTION OF SYMBOLS 10 Combined cycle type power plant 12, 60, 112a Rotating shaft 14 Gas turbine 14a Inlet part 16 Compressor 18, 58 Generator 20 Output sensor 22 Combustor 24 Fuel gas supply pipe 26, 36, 74, 76 Temperature sensor 28 Branch 28a, 28b Branch 30 Air cooler 32 Turbine blade 34 Recovery pipe 38, 44a Exhaust passage 40 Exhaust branch passage 42 Bypass stack 44 Exhaust heat recovery boiler 44b Heat exchange pipe group 46 Damper device 48, 66, 70, 128 Drive device 50 Controller 52 Condenser 56 Steam turbine 62,100 Exhaust introduction amount control device (exhaust heat reduction device)
64, 68 Partition plate 71 Load control mechanism 72 Pressure sensor 80 Control circuit 82, 84, 86, 88, 90 Feedback circuit 92 Minimum selector 100 Exhaust introduction amount control device 102 Strip plate 104 Shaft 110a, 110b Drive bar 112 Motor 120 Inflow heat amount Reduction device 122 Cooling water introduction pipe 124 Nozzle a Supply air e Exhaust f Fuel gas w Cooling water

Claims (6)

A gas turbine, an exhaust heat recovery boiler that generates heat by exchanging heat with the exhaust of the gas turbine, a steam turbine that is driven by steam generated in the exhaust heat recovery boiler, and that is driven by the gas turbine and the steam turbine In a power plant with a generator,
An inflow heat amount reducing device provided in an inlet side exhaust passage in the exhaust heat recovery boiler, a temperature sensor provided in a downstream exhaust passage of the inflow heat amount reducing device, and an exhaust temperature rising speed detected by the temperature sensor A temperature rise suppression mechanism comprising a first controller that operates the inflow heat amount reducing device so that the threshold does not exceed a threshold value;
A variable opening device that is provided in the exhaust passage of the gas turbine and makes the opening of the exhaust passage variable, a gas turbine output, a detected value of the pressure and temperature of the gas turbine exhaust, and a detected temperature value of a high temperature portion of the gas turbine. A minimum selector that inputs and selects an input value closest to the threshold value among these input values, and a second controller that operates the opening degree varying device so that the input value selected by the minimum selector does not exceed the threshold value And a load control mechanism. A bypass stack connected to an exhaust passage of the gas turbine, an exhaust branch passage that branches from the exhaust passage and sends exhaust gas to the exhaust heat recovery boiler, and a branch portion between the exhaust passage and the exhaust branch passage, A damper device for adjusting the flow rate of exhaust gas sent to the bypass stack or the exhaust heat recovery boiler,
The inflow heat quantity reducing device is configured to adjust an opening degree of an inlet side exhaust passage in the exhaust heat recovery boiler and to adjust an exhaust heat quantity introduced into the exhaust heat recovery boiler. The power plant according to 1.   The inflow heat amount reducing device includes a large number of strips arranged in parallel so as to be rotatable about a longitudinal axis, and the gaps between the strips are adjusted by rotating the strips, and the inlet side exhaust passage The power plant according to claim 2, wherein the opening is adjusted.   The inflow heat quantity reducing device is a nozzle that injects cooling water into an inlet side exhaust passage of the exhaust heat recovery boiler, and is cooled by the first controller according to an exhaust temperature increase rate detected by the temperature sensor. The power plant according to claim 1, wherein the water injection amount is adjusted.   The high-temperature part of the gas turbine is an inlet part and a turbine blade of a gas turbine into which combustion gas flows. By detecting the temperature of cooling air introduced into a cooling hole drilled in the turbine blade, the turbine blade The power plant according to claim 1, wherein the temperature is detected. A gas turbine, a bypass stack connected to the exhaust passage of the gas turbine, an exhaust heat recovery boiler that generates steam by exchanging heat with the exhaust sent through the exhaust branch passage branched from the exhaust passage, A steam turbine driven by steam generated in the exhaust heat recovery boiler; a generator driven by the gas turbine and the steam turbine; and the bypass stack or exhaust heat provided at a branch portion of the exhaust passage and the branch exhaust passage. In a power plant remodeling method comprising a damper device for adjusting the flow rate of exhaust gas sent to a recovery boiler,
A step of providing an inflow heat amount reducing device in an inlet side exhaust passage in the exhaust heat recovery boiler, a step of providing a temperature sensor in a downstream exhaust passage of the inflow heat amount reducing device, and a rate of increase in exhaust temperature detected by the temperature sensor Temperature rise suppression mechanism installation process comprising the step of providing a first controller that operates the inflow heat quantity reduction device so that the threshold value does not exceed a threshold value;
A step of providing an opening degree variable device for changing an opening degree of the exhaust passage in the exhaust passage of the gas turbine, a detected value of the gas turbine output, pressure and temperature of the gas turbine exhaust, and a detected temperature value of a high temperature portion of the gas turbine; A step of providing a minimum selector for inputting and selecting an input value closest to the threshold value among these input values; and a second operation for operating the opening degree varying device so that the input value selected by the minimum selector does not exceed the threshold value. And a load control mechanism installation step comprising the step of providing a controller.

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