JP2020133532A - Power generating system - Google Patents

Abstract

To rapidly increase an amount of power generation even when a bypass stack is not used.SOLUTION: A power generating system includes: a gas turbine; an exhaust heat recovery boiler for generating steam using heat of an exhaust gas from the gas turbine; and a cooling part for cooling the exhaust gas supplied to the exhaust heat recovery boiler from the gas turbine.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power generation system.

Patent Document 1 below discloses a gas turbine combined cycle (GTCC) power generation system including a gas turbine and an exhaust heat recovery boiler that generates steam by using the heat of exhaust gas from the gas turbine. ..

In the above power generation system, if the gas turbine is started quickly in order to rapidly increase the amount of power generation, the temperature of the exhaust gas from the gas turbine rises sharply, exceeding the temperature rise rate of the exhaust gas allowed by the exhaust heat recovery boiler. There is. Therefore, the power generation system cannot rapidly increase the amount of power generation. Therefore, in order to solve the above problem, a bypass stack that discharges exhaust gas may be installed between the gas turbine and the exhaust heat recovery boiler.

Japanese Patent No. 4469222

When a bypass stack is installed, the entire power generation system becomes large.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a power generation system capable of rapidly increasing the amount of power generation without using a bypass stack.

(1) One aspect of the present invention is a power generation system including a gas turbine and an exhaust heat recovery boiler that generates steam by using the heat of exhaust gas from the gas turbine, and the exhaust heat from the gas turbine. The power generation system is characterized by including a cooling unit for cooling the exhaust gas supplied to the recovery boiler.

(2) In the power generation system of (1) above, the cooling unit may cool the exhaust gas by injecting cooling water into the exhaust gas before the heat is recovered by the exhaust heat recovery boiler. ..

(3) The power generation system according to (2) above, further comprising a control device for controlling the injection amount of the cooling water, the control device is from the gas turbine based on a target value of a start speed of the gas turbine. The state of the exhaust gas supplied to the exhaust heat recovery boiler may be estimated, and the injection amount of the cooling water may be feed-forward controlled based on the estimated state of the exhaust gas.

(4) In the power generation system of (3) above, the control device has a calorific value of the exhaust gas supplied to the exhaust heat recovery steam generator and a change in the calorific value based on the target value of the starting speed of the gas turbine. The amount is estimated as the first state, and the amount of heat of the exhaust gas supplied to the exhaust heat recovery boiler and the amount of change in the amount of heat are estimated and estimated as the second state based on the operating state of the gas turbine. Based on the feed forward control unit that obtains the injection amount for controlling the temperature of the exhaust gas to the target value based on the first state and the second state as the feed forward command value, and the feed forward command value. A drive control unit that controls the injection amount injected from the cooling unit may be provided.

(5) In the power generation system of the above (4), the temperature measuring unit for measuring the temperature of the exhaust gas after being cooled by the cooling unit and the injection amount calculated by the feedback control unit are the exhaust gas. The drive control unit includes a feedback control unit that calculates a feedback command value based on a deviation between a predicted value of the temperature of the exhaust gas after being injected into the system and a measurement value of the temperature measurement unit. The injection amount injected from the cooling unit may be controlled based on the forward command value and the feedback command value.

As described above, according to the present invention, the amount of power generation can be rapidly increased without using the bypass stack.

It is a figure which shows an example of the schematic structure of the power generation system A which concerns on this embodiment. It is a functional block diagram of the control device 8 which concerns on this embodiment. It is a functional block diagram of the control device 8B of the modification 1. It is a functional block diagram of the control device 8C of the modification 2. It is a functional block diagram of the control device 8D of the modification 3.

Hereinafter, the power generation system according to the present embodiment will be described with reference to the drawings.

FIG. 1 is a diagram showing an example of a schematic configuration of a power generation system A according to the present embodiment. The power generation system A according to the present embodiment is a gas turbine combined cycle (GTCC) plant.

As shown in FIG. 1, the power generation system A includes an intake flow path 1, a first temperature measuring unit 2, a gas turbine 3, a generator 4, an exhaust heat recovery boiler 5, a cooling unit 6, and a second temperature measuring unit 7. And a control device 8.

The intake flow path 1 is connected to the gas turbine 3 and takes in outside air as an intake fluid.

The first temperature measuring unit 2 measures the temperature (intake temperature) Ti of the intake fluid taken into the gas turbine 3. The first temperature measuring unit 2 is provided inside the intake flow path 1. For example, the first temperature measuring unit 2 includes a plurality of temperature sensors 2a. The first temperature measuring unit 2 outputs the measured temperature Ti of the suction fluid to the control device 8 wirelessly or by wire.

The gas turbine 3 is a drive source of the generator 4, and generates rotational power by burning fuel. Specifically, the gas turbine 3 includes a compressor 10, a combustor 11, and a turbine 12.

The compressor 10 is coaxially connected to the turbine 12. The compressor 10 rotates by the rotation of the turbine 12 and compresses the intake fluid taken in through the intake flow path 1 to a predetermined pressure to generate a compressed fluid (compressed air). The compressor 10 supplies the generated compressed fluid to the combustor 11.

An inlet guide vane (IGV) 10a is provided at the inlet of the compressor 10. The flow rate of the intake fluid sucked into the compressor 10 is adjusted by adjusting the opening degree of the IGV 10a. Information on the opening degree of the IGV10a (hereinafter referred to as "IGV opening degree") is transmitted to the control device 8 by wire or wirelessly. Further, the compressor 10 is provided with a bleed valve 10b, and by controlling the opening degree of the bleed valve 10b, the pressure of the compressor 10 is controlled so as not to exceed a specified value. Information on the opening degree of the bleed valve 10b (hereinafter referred to as "bleed valve opening degree") is transmitted to the control device 8 by wire or wirelessly.

The combustor 11 mixes and burns the compressed fluid compressed by the compressor 10 and fuel (for example, natural gas) to generate combustion gas.

The turbine 12 is rotated by the combustion gas generated in the combustor 11, and the rotational energy obtained by the rotation is transmitted to the compressor 10 and the generator 4 through the rotating shaft G.

The generator 4 converts the rotational energy transmitted from the turbine 12 into electrical energy. That is, in the generator 4, the rotation shaft G is rotated by the drive of the turbine 12, and electric power is generated by the rotation.

The exhaust heat recovery boiler 5 uses the heat of the exhaust gas exhausted from the gas turbine 3 to generate steam. Specifically, the exhaust heat recovery boiler 5 includes a boiler body 21, a low-pressure side preheater 22, a low-pressure side steam drum 23, a low-pressure side evaporator 24, a low-pressure side superheater 25, a high-pressure side preheater 26, and a high-pressure side steam drum. 27, a high-pressure side evaporator 28 and a high-pressure side superheater 29 are provided.

The boiler body 21 is connected to the exhaust port of the turbine 12. The exhaust gas after rotating the turbine 12 is heat-recovered in the process of flowing through the boiler main body 21, and is exhausted from the chimney 21a provided at the rear end of the boiler main body 21.

The low-pressure side preheater 22 is arranged on the most downstream side of the boiler main body 21 and preheats water by heat exchange with exhaust gas. The low-pressure side preheater 22 circulates a part of water by the pump 22a. The low pressure side preheater 22 may be supplied with water from the condenser of the steam turbine. The water preheated by the low pressure side preheater 22 is supplied to the low pressure side steam drum 23.

The low-pressure side steam drum 23 introduces the water supplied from the low-pressure side preheater 22 into the low-pressure side evaporator 24 to generate steam. The low pressure side steam drum 23 is provided with an deaerator 23a. The deaerator 23a removes air and other dissolved gases.

The low-pressure side evaporator 24 is arranged on the upstream side of the low-pressure side preheater 22 in the boiler main body 21, and generates steam by heating water by heat exchange with exhaust gas. The steam generated by the low-pressure side evaporator 24 is introduced into the low-pressure side steam drum 23. The steam introduced into the low-pressure side steam drum 23 is supplied to the low-pressure side superheater 25.

The low-pressure side superheater 25 is arranged on the upstream side of the low-pressure side evaporator 24 in the boiler main body 21, superheats steam by heat exchange with exhaust gas, and supplies it to a steam turbine or the like.

A part of the water introduced into the low-pressure side steam drum 23 is supplied to the high-pressure side preheater 26 by the pump 23b. A part of the water transported by the pump 23b bypasses the high-pressure side preheater 26 and is supplied to the high-pressure side superheater 29.

The high-pressure side preheater 26 is arranged on the upstream side of the low-pressure side superheater 25 in the boiler main body 21, and preheats water by heat exchange with exhaust gas. The water preheated by the high-pressure side preheater 26 is supplied to the high-pressure side steam drum 27.

The high-pressure side steam drum 27 introduces the supplied water into the high-pressure side evaporator 28 to generate steam.

The high-pressure side evaporator 28 is arranged on the upstream side of the high-pressure side preheater 26 in the boiler main body 21, and heats water by heat exchange with exhaust gas to generate steam. The steam generated by the high-pressure side evaporator 28 is introduced into the high-pressure side steam drum 27. The steam introduced into the high-pressure side steam drum 27 is supplied to the high-pressure side superheater 29.

The high-pressure side superheater 29 is arranged on the upstream side of the high-pressure side evaporator 28 in the boiler main body 21, superheats steam by heat exchange with exhaust gas, and supplies it to a steam turbine or the like.

The cooling unit 6 cools the exhaust gas (boiler inlet exhaust gas) supplied from the gas turbine 3 to the exhaust heat recovery boiler 5. The cooling unit 6 of the present embodiment cools the exhaust gas by injecting cooling water onto the exhaust gas at the inlet of the boiler. For example, the cooling unit 6 may inject cooling water toward the inlet of the exhaust gas in the exhaust heat recovery boiler 5. Further, the cooling unit 6 may inject cooling water from the inlet of the exhaust gas in the exhaust heat recovery boiler 5 toward the downstream side of the exhaust heat recovery boiler 5. However, the cooling unit 6 according to the present embodiment only needs to be able to cool the exhaust gas by injecting cooling water into the exhaust gas before the heat is recovered by the exhaust heat recovery boiler 5, and the direction of injecting the cooling water. The installation position of the cooling unit 6 and the cooling unit 6 is not particularly limited. The "injection" of the present embodiment is a concept including water injection.
An example of the configuration of the cooling unit 6 will be described below.

The cooling unit 6 according to the present embodiment includes a pipe 31, a flow rate control valve 32, and an injection nozzle 33.
Cooling water for cooling the exhaust gas flows through the pipe 31. The pipe 31 is connected to the injection nozzle 33 and supplies cooling water to the injection nozzle 33.

The flow rate control valve 32 is provided in the pipe 31 and adjusts the flow rate of the cold water flowing through the pipe 31. The opening degree of the flow rate control valve 32 is controlled by the control device 8.

The injection nozzle 33 includes an injection port that communicates with the pipe 31, and flows through the pipe 31 to inject cooling water from the injection port. The injection amount W of the cooling water injected from the injection nozzle 33 is controlled by the control device 8.

The second temperature measuring unit 7 measures the temperature To of the exhaust gas after being cooled by the cooling unit 6 and before the heat of the exhaust gas is recovered by the exhaust heat recovery boiler 5. For example, the second temperature measuring unit 7 is provided in the boiler main body 21, is provided near the entrance of the exhaust heat recovery boiler 5, and is provided on the downstream side of the injection nozzle 33. For example, the second temperature measuring unit 7 is provided between the injection nozzle 33 and the high pressure side superheater 29 in the boiler main body 21. For example, the second temperature measuring unit 7 includes a plurality of temperature sensors 7a. The second temperature measuring unit 7 outputs the measured exhaust gas temperature To to the control device 8 wirelessly or by wire.

Next, the control device 8 according to the present embodiment will be described.
The control device 8 controls the injection amount W of the cooling water by controlling the opening degree of the flow rate control valve 32. The control device 8 controls the opening degree of the flow rate control valve 32 to inject cooling water into the exhaust gas to cool the exhaust gas whose temperature rises rapidly when the gas turbine 3 is started. Therefore, the control device 8 may control the opening degree of the flow rate control valve 32 to inject the cooling water into the exhaust gas while the gas turbine 3 is running. Here, the control device 8 of the present embodiment uses feed-forward control in order to obtain the optimum injection amount W of the cooling water.

Hereinafter, the functional unit of the control device 8 according to the present embodiment will be described with reference to FIG. FIG. 2 is a functional block diagram of the control device 8 according to the present embodiment.

As shown in FIG. 2, the control device 8 includes a feedforward control unit 40, a feedback control unit 50, and a drive control unit 60.

The feed forward control unit 40 estimates the heat amount (heat input amount) of the boiler inlet exhaust gas and the change amount of the heat input amount as the first state based on the information including the target value of the starting speed of the gas turbine 3. Further, the feed forward control unit 40 estimates the heat input amount of the boiler inlet exhaust gas and the change amount of the heat input amount as the second state based on the information including the measured value of the operating state of the gas turbine 3. Then, the feed forward control unit 40 controls the injection amount for controlling the temperature of the exhaust gas to a target value (hereinafter, referred to as “boiler inlet exhaust gas target temperature”) based on the estimated first state and second state. W is obtained as a feed forward command value.

The feed forward control unit 40 according to the present embodiment will be specifically described below. The feed forward control unit 40 includes a first calculation unit 41 and a second calculation unit 42.

The first calculation unit 41 includes an engine model 411 and a first injection amount calculation unit 412.

The engine model 411 estimates the first state by estimating the temperature of the exhaust gas exhausted from the gas turbine 3 and the flow rate of the exhaust gas, respectively, based on the target starting rate. Then, the engine model 411 sets the estimated exhaust gas temperature (hereinafter, referred to as "exhaust gas temperature estimated value") Ts1 and the estimated exhaust gas flow rate (hereinafter, referred to as "exhaust gas flow rate estimated value") Fs1. It is output to the injection amount calculation unit 412 of 1. Here, the target starting rate is information indicating the operating conditions of the power generation system A. For example, the target starting rate is a target value of the starting speed of the gas turbine 3. Therefore, the engine model 411 can estimate the first state of the exhaust gas exhausted from the gas turbine in the state where the gas turbine 3 is started.

The first injection amount calculation unit 412 calculates the injection amount W1 such that the boiler inlet exhaust gas reaches the boiler inlet exhaust gas target temperature as the first feed forward command value. Here, the target temperature of the exhaust gas at the inlet of the boiler is the temperature of the exhaust gas allowed when the exhaust heat recovery boiler 5 is started, and is set in advance. Here, the amount of heat input of the exhaust heat recovery boiler 5 and the amount of change thereof, which are allowed when the exhaust heat recovery boiler 5 is started, are predetermined. Therefore, the target temperature of the exhaust gas at the boiler inlet may be set based on the amount of heat input of the exhaust heat recovery boiler 5 and the amount of change thereof, which are allowed when the exhaust heat recovery boiler 5 is started.

For example, the first injection amount calculation unit 412 first sets the injection amount W1 such that the boiler inlet exhaust gas becomes the boiler inlet exhaust gas target temperature based on the target boost rate, the exhaust gas temperature estimated value Ts1 and the exhaust gas flow rate estimated value Fs1. It is calculated as the feed forward command value of. Here, the target boost rate is a target value of the boost rate of the steam generated by the exhaust heat recovery boiler 5, and is set to the boost rate allowed by the exhaust heat recovery boiler 5.
The first injection amount calculation unit 412 outputs the calculated first feed forward command value to the second calculation unit 42.

Further, the first injection amount calculation unit 412 estimates the temperature of the exhaust gas after injecting the calculated cooling water of the injection amount W1 into the exhaust gas (boiler inlet exhaust gas). The first injection amount calculation unit 412 outputs the estimated exhaust gas temperature (hereinafter, referred to as “post-injection exhaust gas temperature estimated value”) Tx to the feedback control unit 50.

The second calculation unit 42 includes an exhaust gas state calculation unit 421, a deviation device 422, 423, and a second injection amount calculation unit 424.

The exhaust gas state calculation unit 421 calculates the temperature and flow rate of the exhaust gas at the boiler inlet at the same time as starting the gas turbine 3 based on information including information on the operating state of the gas turbine 3 (hereinafter, referred to as "operation information"). Estimates the second state with. The information including the operation information may be only the operation information, or may further include information on the fuel used in the combustor 11 (hereinafter, referred to as “fuel information”). Here, the fuel information is information about the fuel used in the combustor 11, and includes, for example, at least one or more of the pressure of the fuel, the temperature of the fuel, the type of the fuel, the composition of the fuel, and the calorific value. The operation information includes, for example, at least one or more of measured values such as IGV opening degree, bleed valve opening degree, intake air temperature Ti, operating state of auxiliary equipment (intake air cooler, intake air heater), and output of gas turbine 3. The exhaust gas temperature calculated by the exhaust gas state calculation unit 421 is designated as "exhaust gas temperature estimated value Ts2". The flow rate of the exhaust gas calculated by the exhaust gas state calculation unit 421 is designated as "exhaust gas flow rate estimated value Fs2". Here, the operating state of the auxiliary equipment (intake cooler, intake heater) is, for example, the output of the auxiliary equipment, the current value applied to the auxiliary equipment, the voltage value applied to the auxiliary equipment, and the auxiliary equipment. Includes at least one or more of the power value consumed.
The exhaust gas state calculation unit 421 does not have to use the measured value of the output of the gas turbine 3 as the operation information in obtaining the exhaust gas temperature estimated value Ts2 and the exhaust gas flow rate estimated value Fs2. This is because the measured value of the output of the gas turbine 3 is slow to be used for feed forward control. Therefore, for example, when the exhaust gas state calculation unit 421 obtains the exhaust gas temperature estimated value Ts2 and the exhaust gas flow rate estimated value Fs2, the IGV opening degree, the bleed valve opening degree, the intake air temperature Ti, and the auxiliary equipment (intake air cooler, intake air heater) The operating state of may be used as driving information.

The deviation device 422 obtains the difference value ΔTs between the exhaust gas temperature estimated value Ts1 and the exhaust gas temperature estimated value Ts2, and outputs the obtained difference value ΔTs to the second injection amount calculation unit 424.

The deviation device 423 obtains a difference value ΔFs between the exhaust gas flow rate estimated value Fs1 and the exhaust gas flow rate estimated value Fs2, and outputs the obtained difference value ΔFs to the second injection amount calculation unit 424.

The second injection amount calculation unit 424 uses the injection amount Wout of the cooling water injected from the cooling unit 6 as a control command value based on the first feedforward command value, the feedback command value, the difference value ΔTs and the difference value ΔFs. Ask. For example, the second injection amount calculation unit 424 sets the injection amount W1'so that the boiler inlet exhaust gas reaches the boiler inlet exhaust gas target temperature based on the difference value ΔTs, the difference value ΔFs, and the first feed forward command value. Generates a feedforward command value of 2. For example, the second injection amount calculation unit 424 corrects the injection amount W1 (first feed forward command value) by the correction amount based on the difference value ΔTs and the difference value ΔFs to obtain the injection amount W1 ′. Generates the feed forward command value of. Then, the second injection amount calculation unit 424 generates a control command value based on the second feedforward command value and the feedback command value, and outputs the generated control command value to the drive control unit 60. Note that this control command value corresponds to the injection amount Wout that is finally injected from the cooling unit 6.
For example, the second injection amount calculation unit 424 corrects the first feed forward command value so that the difference value ΔTs and the difference value ΔFs disappear, so that the corrected first feed forward command value, that is, the second Obtain the feed forward command value of 2.

The feedback control unit 50 acquires the temperature To of the exhaust gas measured by the second temperature measurement unit 7. Then, the feedback control unit 50 obtains a difference value ΔTx between the exhaust gas temperature To and the exhaust gas temperature estimated value Tx after injection, and obtains a cooling water injection amount W2 such that the difference value ΔTx disappears. For example, the feedback control unit 50 obtains the cooling water injection amount W2 by applying PI control or PID control to the difference value ΔTx. Then, the feedback control unit 50 outputs the obtained injection amount W2 as a feedback command value to the second calculation unit 42.

The drive control unit 60 controls the opening degree of the flow rate control valve 32 based on the control command value. As a result, an appropriate amount of cooling water is injected from the cooling unit 6. Therefore, the control device 8 can suppress a rapid rise in the temperature of the exhaust gas at the inlet of the boiler. Therefore, although the load increase of the gas turbine 3 is close to that of the gas turbine 3 alone, the temperature increase is not limited at the inlet of the exhaust heat recovery boiler 5. As a result, the amount of power generation can be rapidly increased without using the bypass stack.

Next, the operation of the control device 8 according to the present embodiment will be described.
When the target start rate (operating condition of the power generation system A) is set, the control device 8 estimates the first state of the boiler inlet exhaust gas from the engine model 411 from the target start rate, and the temperature of the boiler inlet exhaust gas becomes high. The injection amount W1 is calculated so as to match the target temperature of the exhaust gas at the boiler inlet.

Further, the control device 8 calculates the second state of the boiler inlet exhaust gas from various measurement data such as fuel information and operation information at the same time when the gas turbine 3 is started. Then, the control device 8 corrects the injection amount W1 with the injection amount W1 as the base and the second state of the boiler inlet exhaust gas as the correction amount to obtain the injection amount W1'. Then, the control device 8 feed-forward controls the cooling unit 6 with the injection amount W1'as a feed-forward command value. As a result, the control device 8 can calculate and correct the injection amount more accurately prior to the feedback control of the temperature To of the exhaust gas, and can quickly and stably control the injection amount injected from the cooling unit 6. realizable. The control device 8 may inject the cooling water only when the gas turbine 3 is started, for example, or in order to rapidly increase the amount of power generated by the power generation system A, the gas turbine 3 may be injected. It may be done when the startup speed is increased. For example, when the starting speed of the gas turbine 3 is increased, for example, the starting speed of the gas turbine 3 or the increase amount of the power generation amount may exceed a predetermined value.

As described above, the power generation system A of the present embodiment includes a cooling unit 6 that cools the boiler inlet exhaust gas, which is the exhaust gas supplied from the gas turbine 3 to the exhaust heat recovery boiler 5. As a result, the power generation system A can control the temperature of the exhaust gas from the gas turbine 3 to an allowable value even if the start of the gas turbine 3 is accelerated in order to rapidly increase the amount of power generation. As a result, the power generation system A can rapidly increase the amount of power generation without using the bypass stack.

Here, the bypass stack needs to open and close the valve at a high temperature. However, since the power generation system A does not need to be equipped with the bypass stack damper, the reliability of the power generation equipment of the power generation system A is improved. Furthermore, although the size of the land for the power generation equipment of the power generation system A is often limited, the power generation system A reduces the bypass stack itself, which has a large inner diameter and has a heat insulating material, which is required to emit high-temperature exhaust gas. it can. Therefore, the ground contact area of the power generation facility of the power generation system A can be made compact.

Further, since the power generation system A can reduce the temperature of the exhaust gas at the inlet of the boiler, it is possible to prevent the exhaust heat recovery boiler 5 from consuming the life due to thermal stress while rapidly increasing the amount of power generation by the gas turbine 3.

Further, the control device 8 of the present embodiment estimates the heat input amount of the boiler inlet exhaust gas and the change amount of the heat input amount as the first state based on the target value of the starting speed of the gas turbine 3, and the gas turbine 3 The feed forward control unit 40 is provided to estimate the amount of heat input of the exhaust gas at the inlet of the boiler and the amount of change in the amount of heat input as the second state based on the operating state. Then, the feed forward control unit 40 obtains an injection amount for controlling the temperature of the exhaust gas (boiler inlet exhaust gas) to a target value as a feed forward command value based on the estimated first state and the second state. The drive control unit 60 controls the injection amount injected from the cooling unit 6 based on the feed forward command value.

As a result, the control device 8 can perform advance control (feed forward control) for calculating the injection amount to the boiler inlet exhaust gas by obtaining the prediction of the exhaust gas state amount corresponding to the state of the gas turbine 3 changing at high speed. Therefore, the control device 8 can obtain a faster control response than the control (feedback control) according to the measured value (temperature To) of the temperature of the boiler inlet exhaust gas accompanied by a time delay, and the optimum amount without excess or deficiency. Can realize the injection of cooling water.

Further, the control device 8 has a predicted value Tx of the temperature of the exhaust gas after the injection amount calculated by the feedforward control unit 40 is injected into the exhaust gas, and the temperature To of the exhaust gas measured by the second temperature measuring unit 7. The feedback control unit 50 is provided to calculate the feedback command value based on the deviation from. And. The drive control unit 60 may control the injection amount injected from the cooling unit 6 based on the feedforward command value and the feedback command value.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and the design and the like within a range not deviating from the gist of the present invention are also included.

(Modification example 1)
In the present embodiment, the control device 8 controls the injection amount of the cooling water of the cooling unit 6 by combining feedforward control and feedback control, but the present embodiment is not limited to this. For example, the control device 8B of the first modification may control the injection amount of the cooling water of the cooling unit 6 by using only the feed forward control. FIG. 3 is a functional block diagram of the control device 8B of the first modification. In the power generation system of the first modification, the configurations other than the control device 8B are the same as those of the above-described embodiment.

The control device 8B of the first modification includes a feed forward control unit 40B and a drive control unit 60B.
The feed forward control unit 40B estimates the heat amount (heat input amount) of the boiler inlet exhaust gas and the change amount of the heat input amount as the first state based on the information including the target value of the starting speed of the gas turbine 3. Then, the feed forward control unit 40B obtains an injection amount for controlling the temperature of the exhaust gas to a target value as a feed forward command value based on the estimated first state.

Specifically, the feed forward control unit 40B includes an engine model 411B and a first injection amount calculation unit 412B.

The engine model 411B estimates the first state by estimating the temperature of the exhaust gas exhausted from the gas turbine 3 and the flow rate of the exhaust gas, respectively, based on the target starting rate. Then, the engine model 411B outputs the estimated exhaust gas temperature estimated value Ts1 and the estimated exhaust gas flow rate estimated value Fs1 to the first injection amount calculation unit 412B.
The first injection amount calculation unit 412B injects the exhaust gas supplied to the exhaust heat recovery boiler 5 to the boiler inlet exhaust gas target temperature based on the target boost rate, the exhaust gas temperature estimated value Ts1 and the exhaust gas flow rate estimated value Fs1. The quantity W1 is calculated as the first feed forward command value.

The drive control unit 60B controls the opening degree of the flow rate control valve 32 based on the first feed forward command value (control command value). As a result, an appropriate amount of cooling water is injected from the cooling unit 6. Therefore, the control device 8B can control the temperature of the exhaust gas from the gas turbine 3 to an allowable value even if the start of the gas turbine 3 is accelerated in order to rapidly increase the amount of power generation. As a result, the power generation system including the control device 8B can rapidly increase the amount of power generation without using the bypass stack.
The control device 8B may inject the cooling water only when the gas turbine 3 is started, for example, or increase the starting speed of the gas turbine 3 in order to rapidly increase the amount of power generation. You may go when you do. For example, when the starting speed of the gas turbine 3 is increased, for example, the starting speed of the gas turbine 3 or the increase amount of the power generation amount may exceed a predetermined value.

(Modification 2)
In the present embodiment, the control device 8 controls the injection amount of the cooling water of the cooling unit 6 by combining feedforward control and feedback control, but the present embodiment is not limited to this. For example, the control device 8C of the modification 2 may control the injection amount of the cooling water of the cooling unit 6 by using only the feed forward control. FIG. 4 is a functional block diagram of the control device 8C of the second modification. In the power generation system of the second modification, the configurations other than the control device 8C are the same as those in the above-described embodiment.

The control device 8C of the second modification includes a feed forward control unit 40C and a drive control unit 60C.
The feed forward control unit 40C estimates the heat amount (heat input amount) of the boiler inlet exhaust gas and the change amount of the heat input amount as the second state based on the information including the operation information of the gas turbine 3. Then, the feed forward control unit 40C obtains an injection amount for controlling the temperature of the exhaust gas to a target value as a feed forward command value based on the estimated second state.

The feed forward control unit 40C includes an exhaust gas state calculation unit 421C and a second injection amount calculation unit 424C.

The exhaust gas state calculation unit 421C estimates the second state by starting the gas turbine 3 and calculating the temperature Ts1 and the flow rate Fs2 of the exhaust gas at the boiler inlet based on the information including the operation information of the gas turbine 3.

Based on the second state, the second injection amount calculation unit 424C calculates an injection amount such that the exhaust gas supplied to the exhaust heat recovery boiler 5 reaches the boiler inlet exhaust gas target temperature as a feed forward command value.

The drive control unit 60C controls the opening degree of the flow rate control valve 32 based on the feed forward command value calculated by the second injection amount calculation unit 424C. As a result, an appropriate amount of cooling water is injected from the cooling unit 6. Therefore, the control device 8C can control the temperature of the exhaust gas from the gas turbine 3 to an allowable value even if the start of the gas turbine 3 is accelerated in order to rapidly increase the amount of power generation. As a result, the power generation system including the control device 8C can rapidly increase the amount of power generation without using the bypass stack.
The control device 8C may inject the cooling water only when the gas turbine 3 is started, for example, or increase the starting speed of the gas turbine 3 in order to rapidly increase the amount of power generation. You may go when you do. For example, when the starting speed of the gas turbine 3 is increased, for example, the starting speed of the gas turbine 3 or the increase amount of the power generation amount may exceed a predetermined value.

(Modification 3)
The control device 8 of the present embodiment may have the configuration shown in FIG. FIG. 5 is a functional block diagram of the control device 8D of the modified example 3. For example, the control device 8D of the third modification includes a feedforward control unit 40D, a feedback control unit 50D, an adder 70, and a drive control unit 60D. In the power generation system of the third modification, the configurations other than the control device 8D are the same as those in the above-described embodiment.

The feed forward control unit 40D has the same configuration as the feed forward control unit 40B. The feed forward control unit 40D estimates the heat amount (heat input amount) of the boiler inlet exhaust gas and the change amount of the heat input amount as the first state based on the information including the target value of the starting speed of the gas turbine 3. Then, the feed forward control unit 40D obtains an injection amount for controlling the temperature of the exhaust gas to a target value as a feed forward command value based on the estimated first state.

The feedback control unit 50D acquires the temperature To of the exhaust gas measured by the second temperature measurement unit 7. Then, the feedback control unit 50D obtains a difference value ΔTo between the exhaust gas temperature To and the boiler inlet exhaust gas target temperature, and obtains a cooling water injection amount W2'so that the difference value ΔTo disappears. For example, the feedback control unit 50D obtains the cooling water injection amount W2'by applying PI control or PID control to the difference value ΔTo. Then, the feedback control unit 50D outputs the obtained injection amount W2'as a feedback command value to the adder 70.

The adder 70 adds the feedforward command value obtained by the feedforward control unit 40D and the feedback command value obtained by the feedback control unit 50D, so that the injection amount of cooling water actually injected from the cooling unit 6 Wout. Find the control command value that is ´. Then, the adder 70 outputs the control command value to the drive control unit 60D.

The drive control unit 60D controls the opening degree of the flow rate control valve 32 based on the control command value. As a result, cooling water having an injection amount of Wout'is injected from the cooling unit 6. Therefore, the control device 8D can control the temperature of the exhaust gas from the gas turbine 3 to an allowable value even if the start of the gas turbine 3 is accelerated in order to rapidly increase the amount of power generation. As a result, the power generation system including the control device 8D can rapidly increase the amount of power generation without using the bypass stack.

The control device 8D may inject the cooling water only when the gas turbine 3 is started, for example, or increase the starting speed of the gas turbine 3 in order to rapidly increase the amount of power generation. You may go when you do. For example, when the starting speed of the gas turbine 3 is increased, for example, the starting speed of the gas turbine 3 or the increase amount of the power generation amount may exceed a predetermined value.

The control device 8D of the modification 3 may be configured by replacing the feed forward control unit 40B with the feed forward control unit 40C.

It should be noted that all or part of the above-mentioned control device may be realized by a computer. In this case, the computer may include a processor such as a CPU and GPU and a computer-readable recording medium. Then, a program for realizing all or a part of the functions of the control device on the computer is recorded on the computer-readable recording medium, and the program recorded on the recording medium is read by the processor and executed. It may be realized by. Here, the "computer-readable recording medium" refers to a portable medium such as a flexible disk, a magneto-optical disk, a ROM, or a CD-ROM, or a storage device such as a hard disk built in a computer system. Further, a "computer-readable recording medium" is a communication line for transmitting a program via a network such as the Internet or a communication line such as a telephone line, and dynamically holds the program for a short period of time. It may also include a program that holds a program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or a client in that case. Further, the above program may be for realizing a part of the above-mentioned functions, and may be further realized for realizing the above-mentioned functions in combination with a program already recorded in the computer system. It may be realized by using a programmable logic device such as FPGA.

A Power generation system 3 Gas turbine 5 Exhaust heat recovery boiler 6 Cooling unit 8 Control device 40 Feedforward control unit 50 Feedback control unit 60 Drive control unit

Claims (5)

A power generation system including a gas turbine and an exhaust heat recovery boiler that generates steam by using the heat of exhaust gas from the gas turbine.
A cooling unit that cools the exhaust gas supplied from the gas turbine to the exhaust heat recovery boiler, and
A power generation system characterized by being equipped with. The power generation system according to claim 1, wherein the cooling unit cools the exhaust gas by injecting cooling water onto the exhaust gas before the heat is recovered by the exhaust heat recovery boiler. A control device for controlling the injection amount of the cooling water is further provided.
The control device estimates the state of the exhaust gas supplied from the gas turbine to the exhaust heat recovery boiler based on the target value of the starting speed of the gas turbine, and the cooling water is based on the estimated state of the exhaust gas. The power generation system according to claim 2, wherein the injection amount of the above is controlled by feed forward control. The control device is
Based on the target value of the starting speed of the gas turbine, the amount of heat of the exhaust gas supplied to the exhaust heat recovery boiler and the amount of change in the amount of heat are estimated as the first state, and based on the operating state of the gas turbine. The amount of heat of the exhaust gas supplied to the exhaust heat recovery boiler and the amount of change in the amount of heat are estimated as the second state, and the temperature of the exhaust gas is set based on the estimated first state and the second state. A feed forward control unit that obtains the injection amount for controlling to a target value as a feed forward command value, and
A drive control unit that controls the injection amount injected from the cooling unit based on the feed forward command value.
The power generation system according to claim 3, further comprising: A temperature measuring unit that measures the temperature of the exhaust gas after being cooled by the cooling unit,
Feedback that calculates a feedback command value based on the deviation between the predicted value of the temperature of the exhaust gas after the injection amount calculated by the feed forward control unit is injected into the exhaust gas and the measurement value of the temperature measurement unit. Control unit and
With
The power generation system according to claim 4, wherein the drive control unit controls the injection amount injected from the cooling unit based on the feedforward command value and the feedback command value.

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