JPH02130203A - Steam temperature controller for composite power plant facility - Google Patents

Abstract

PURPOSE:To make it possible to promptly follow variations in the temperature of outlet steam by limiting the upper limit of the sum of a feed-back signal and a feed- forward signal for a cooling water valve in accordance with a temperature of steam at the outlet of a temperature reducer and a steam pressure signal. CONSTITUTION:Detectors 41 through 48 detect a temperature and a flow rate of steam, and a flow rate and a temperature of gas and the like in a superheater 16 and a reheater 17 in a heat recovery boiler 15 which is heated by gas discharged from a gas turbine 13, for generating, heating and reheating steam. Detection signals from these detectors are fed to a feed-back signal generating device so as to be used for a feed-back signal delivered to a cooling water valve 25 for controlling the superheater 16, the reheater 17 and the like. Further, the detection signals from the detectors 41 through 48 are also fed to a feed-forward controller and the like so as to be used for a feed-forward signal for controlling the preceding temperature and the like for the cooling water valve 25. These signals are fed to the cooling water valve 25 while their upper limits are controlled, and accordingly, a predetermined volume of cooling water is fed to a temperature reducer 27, thereby the superheater 16, the reheater 17 and the like are controlled so as to maintain suitable temperatures.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a steam temperature control device for combined cycle power generation equipment, and in particular, to a steam temperature control device for a combined power generation facility, and in particular for controlling the temperature of steam heated by a superheater, reheater, etc. to a predetermined value. The present invention relates to a steam temperature control device for a combined power generation facility that maintains the temperature at a certain temperature.

(Conventional technology) Generally, power generation equipment uses either a steam turbine or a gas turbine as the prime mover, but recently, combined cycle power generation equipment that takes advantage of the characteristics of both turbines, that is, combined cycle power generation equipment, has been increasingly used. There is.

The schematic configuration of this combined power generation facility is as shown in FIG. 8, and this facility will be explained below.

The combined power generation facility, generally indicated by 10, is provided with a compressor 11 that compresses a gas medium. The gas medium compressed by the compressor 11 is sent to the combustor 12, where it is made into a high-temperature, high-pressure gas and sent to the gas turbine 13, which is driven to rotate. A generator 14 is connected to the gas turbine 13 through a common shaft together with the compressor 11, a steam turbine, etc. which will be described later, and when the gas turbine 13 is rotationally driven, the generator 14 generates electric power and sends the electric power to a system (not shown). is supplied. The gas used in the gas turbine 13 is discharged as exhaust gas to the exhaust heat recovery boiler 15, and is used in the superheater 16, reheater 17, evaporator 18, etc. provided inside the exhaust heat recovery boiler 15 to supply water or Heat exchanged with steam.

That is, steam is generated in the evaporator 18 by heat exchange between the supplied water and the exhaust gas. This steam is sent to a drum 19, where steam and water separation is performed, and the steam is sent to a superheater 16 via a pipe 20, where it is heated by exhaust gas and turned into high-temperature, high-pressure steam. This steam is transferred to pipe 21
is sent to the high-pressure turbine 22, where it performs work and drives the generator 14. The steam that has performed work in the high-pressure turbine 22 is sent to the reheater 17 via the pipe 23, where it is reheated by the exhaust gas to become high-temperature, high-pressure steam, and sent to the low-pressure turbine 24, where it performs work. generator 14
is driven to rotate.

In such a combined power generation facility 10, the gas turbine 1
3, the temperature of the exhaust gas discharged from the gas turbine 13 becomes higher, and the heat exchange efficiency of the exhaust heat recovery boiler 15 improves, resulting in an overall improvement in the combined power generation equipment 1.
0 efficiency has improved. However, due to this high efficiency,
Due to the relationship between the exhaust gas and the combustion temperature of the combustor 12, the temperature of the exhaust gas becomes too high in the intermediate to high load range, and the temperature of the steam sent to it exceeds the usage range of the high pressure turbine 22 and the low pressure turbine 24. Sometimes it happens.

For this purpose, superheater 16 and reheater 17 are each provided with desuperheaters 27 and 28, and by spraying cooling water controlled by cooling water valves 25 and 26 into the steam, high-pressure turbine 22 and low-pressure Steam sent to the turbine 24 is maintained at a predetermined temperature.

The cooling water valves 25 and 26 are controlled by the superheater 16 and reheater 1 of the combined power generation facility 10, as shown in FIGS. 8 and 9.
This is carried out based on the detection output signals of temperature detectors 29 and 30 provided on the steam outlet side of No. 7.

Since this control is performed by substantially the same means for both the superheater 16 and the reheater 17, the control of the superheater 16 will be explained below with reference to FIG. 9.

The detection output signal of the temperature detector 29 is sent to the deviation calculator 32, where the setting signal of the temperature setting device 33 is received and compared with this signal, and the deviation signal is sent to the proportional/integral/differential calculator 34.
The opening degree of the cooling water valve 25 is controlled based on this calculation signal. Therefore, the steam in the superheater 16 is controlled to a predetermined temperature by the cooling water sent from the cooling water valve 25, and the steam at the predetermined temperature is always sent to the high-pressure turbine 22.

This also applies to the low pressure turbine 2 in the reheater 17 as well.
4 is maintained at a predetermined temperature.

In addition, in Fig. 8, 35, 36, and 37 are drum 19,
Steam pressure detector installed in line 21.23, 38.39
is a steam flow rate detector flowing through line 21.23.

(Problem to be Solved by the Invention) However, in the above-described control, when the load on the combined power generation equipment 10, particularly the gas turbine 13, changes, the temperature of the exhaust gas discharged from the gas turbine 13 changes to follow the load, When the steam temperature heated in the superheater 16 etc., that is, the outlet steam temperature is varied due to this variation, this variation in steam temperature is detected by the temperature detector 29, and as described above, the detection signal is sent to the cooling water valve 25. etc. are controlled so that the outlet steam temperature is maintained at a predetermined temperature, but as mentioned above, the temperature detector 29
Because it is installed on the outlet side of the steam generator, there is a detection delay, which causes a time delay in control and excessive fluctuations in steam temperature.

These relationships will be explained with reference to FIGS. 10(a) and (b). In other words, the steam flow rate and steam heat input of the superheater 16 are normally flat when the temperature changes as shown in FIG. Then, the flow rate of steam flowing into the superheater 16 and the amount of steam heat input are rapidly changed and increased. This fluctuation is detected by the temperature detector 29, and the opening degree of the cooling water valve 25 is controlled, cooling water is supplied to the desuperheater 27, and the temperature of the steam flowing out from the superheater 16 is controlled. There is a considerable time delay until the temperature approaches normal temperature.

For example, a detector detects fluctuations in steam flow rate and steam heat input,
It takes time ts-tn-tf until the superheater 16 is controlled. During this time, the superheater 16 reaches a high temperature Tm higher than the design temperature due to the load, and high-temperature steam flows into the superheater 1.
6. It flows into the steam turbine 22, and a large thermal stress is applied to the superheater 16 and the steam turbine 22.
This may reduce the lifespan of the superheater 16 and the steam turbine 22. In particular, composite power membranes (IIL).

Since starting, stopping, etc. are frequently repeated, thermal stress is easily applied, resulting in problems such as shortening of the life of the superheater 16.

Conversely, if the load suddenly decreases and the control of the cooling water valve 25 is delayed, the steam temperature will drop and the water droplets of the cooling water sent to the superheater 16 will not be vaporized and will flow inside the superheater 16 as is. Erosion or the like occurs within the tube, leading to thinning of the inner tube of the superheater 16, and in the worst case, the leakage flows to the steam turbine 22, causing problems such as damage to the steam turbine 22.

In particular, when the exhaust gas temperature of the gas turbine 13 increases in a situation where the steam flow rate is low in the intermediate load region, the gain of the superheater increases, and there is a problem that the temperature becomes periodic and unstable due to mismatching of the gain of the control device. .

These phenomena may become a problem because they are particularly large in combined power generation facilities that are started and stopped more frequently than in simple steam turbine plants.

Fluctuations in the steam flow rate and steam heat input due to the sudden change in load occur in the reheater 17 as well, causing damage to the reheater 17 and the steam turbine 24.

In view of the above points, when the outlet steam temperature of the superheater, reheater, etc. changes, the present invention quickly follows this change, and the superheater, reheater, etc.
The object of the present invention is to provide a steam temperature control device for a combined power generation facility that appropriately controls cooling water supplied to a reheater and the like.

[Structure of the invention]

(Means for Solving the Problems) The present invention consists of a gas turbine, an exhaust gas boiler, a steam turbine, etc., and a desuperheater is installed in each heater such as a superheater and a reheater disposed in the exhaust gas boiler. In the steam temperature control device for the combined cycle power generation facility provided, a feedback signal generator for generating a feedback signal to the cooling water valve of the attemperator based on the heater outlet temperature and a signal corresponding to the steam flow rate, and a signal corresponding to the output of the combined cycle power generation facility. The apparatus includes a feedforward signal generator for the cooling water valve, and an upper limit limiter that limits the upper limit of the sum of the feedback signal and the feedforward signal based on the attemperator outlet steam temperature and steam pressure signals.

(Function) The superheater, reheater, and evaporator inside the heat recovery boiler are heated by the exhaust gas discharged from the gas turbine, and steam is generated, heated, and reheated.

The steam temperature, steam flow rate, exhaust gas flow rate, temperature, etc. in the superheater, reheater, etc. are each detected by a detector, and this detection signal is sent to a feedback signal generator to control the superheater, reheater, etc. This is used as a feedback signal for the cooling water valve to be controlled. Further, the detection signal of the detector is sent to a feedforward controller or the like, and is made to be a feedforward signal for controlling the preliminary temperature of a cooling water valve that controls a superheater, a reheater, etc. The upper limits of these signals are controlled and sent to the cooling water valve, and a predetermined amount of cooling water is supplied to the desuperheater and controlled so as to properly maintain the temperature of the superheater, reheater, etc.

(Embodiment) An embodiment of the steam temperature control device for combined cycle power generation equipment of the present invention will be described below with reference to the drawings. In addition, in the same drawing, the same parts as the steam temperature control device and its characteristic diagram for the conventional combined cycle power generation facility shown in FIGS. 8, 9, and 10 will be explained using the same reference numerals, and detailed explanation thereof will be omitted.

In Figure 1, a composite power generation membrane! The main equipment 40 is the same as the conventional combined power generation equipment calculator 10. However, in the composite power generation membrane of the present invention (III40), the superheater 16 and the reheater 17
is equipped with various detectors to detect its temperature, steam flow rate, and steam pressure. The positions and functions of these installations are the same for the superheater 16 and the reheater 17, so the following explanation will be based on the one attached to the superheater 16, and the reheater 17 will only be described with reference numerals and detailed explanations will be omitted. Omitted.

This superheater 16 is provided with three temperature detectors. 1st
The temperature detector 41 is provided on the steam outlet side of the superheater 16 as in the conventional case, and detects the steam temperature at the outlet of the superheater 16.
The second temperature detector 42 is provided in the middle of the superheater 16 and on the steam inlet side of the attemperator 27, and the inlet steam temperature is detected. Vessel 27
The temperature of the outlet steam reduced by the attemperator 27 provided on the steam outlet side of the is detected. In addition, a fourth temperature detector 4
4 is provided on the inlet side of the exhaust heat recovery boiler 15, and the superheater 1
The temperature of the inlet exhaust gas flowing into 6 is detected. Further, the flow rate detector 45 is provided on the steam outlet side of the superheater 16,
The outlet steam flow rate heated by the superheater 16 is detected;
The flow rate detector 46 is provided on the steam inlet side of the superheater 16, and detects the flow rate of the inlet steam flowing into the superheater 16. The pressure detector 47 is provided on the steam outlet side of the superheater 6,
The outlet steam pressure heated by the superheater 16 is detected. Furthermore, an exhaust gas flow rate detector 48 is provided on the exhaust gas inlet side of the exhaust heat recovery boiler 15 and is connected to the superheater 16.
The inlet exhaust gas flow rate is detected.

The output signals of these valley detectors are sent to a control device as shown in FIG. 2, and the cooling water valve 25 is controlled and operated. That is, the temperature signal of the first temperature detector 41 is inputted to the deviation calculator 49.
The four deviation calculators receive a setting signal from a temperature setting device 50 that sets the steam temperature on the outlet side of the superheater 16 and compare it with the temperature signal.The deviation signal is sent to a multiplier 51. It will be done.

Further, the steam flow rate signal of the superheater 16 detected by the flow rate detector 45 is sent to a function generator 60 to correct the coefficients of temperature and flow rate, and this output signal is sent to the multiplier 51. In the multiplier 51, this output signal is multiplied by the output signal of the temperature deviation signal to produce a multiplied signal that maintains the steam temperature and steam flow rate on the steam outlet side of the superheater 16 at predetermined values. This multiplied signal is sent to a proportional/integral/differential calculator 52, subjected to signal correction, and sent to an adder 53. The adder 53 receives this signal and the feedforward signal from the feedforward calculation unit A, and converts them into addition signals.

That is, the inlet steam temperature of the superheater 16 is detected by the second temperature detector 42, and this inlet steam temperature signal is sent to the feedforward calculator 55 of the feedforward calculator A.
It is then sent to adder 56 as a feedforward signal that precedes the inlet steam temperature of superheater 16 . Similarly, the output signal of the artificial exhaust gas temperature of the heat recovery boiler 15 detected by the temperature detector 44 is sent to the feedforward calculator 57.
The inlet exhaust gas temperature of the heat recovery boiler 15 detected by the exhaust gas flow rate detector 48 is sent to the adder 56 as a feedforward signal that precedes the exhaust gas temperature at the inlet of the heat recovery boiler 15. The output signal of the exhaust gas flow rate is sent to the feedforward calculator 58, where it is sent as a feedforward signal preceding the inlet exhaust gas flow rate of the heat recovery boiler 15 to the adder 56, and furthermore, the flow rate detector The output signal of the outlet steam flow rate of the superheater 16 detected by the feedforward calculator 5
9, where it is made into a feedforward signal that precedes the outlet steam flow rate of superheater 16 and is sent to the adder 56. The adder 56 adds the respective feedforward signals and sends the result to the adder 53. In this adder 53, each feedforward signal is added together with the correction signal sent from the proportional/integral/differential calculator 52, and is used as an addition signal for pre-controlling the outlet steam temperature and outlet steam flow rate of the superheater 16. .

This addition signal is sent to an upper limiter 54. In the upper limit limiter 54, its operating range is limited by a setting device 66, and a multiplication signal of the limited range is sent to the cooling water valve 25.
The opening degree of this cooling water valve 25 is controlled.

Furthermore, the outlet steam temperature of the attemperator 27 is detected by the third temperature detector 43, and this output signal is sent to the deviation calculator 61. Further, the pressure detector 47 detects the steam pressure at the outlet of the superheater 16, and this pressure signal is sent to the function generator 62.
sent to. The function generator 62 converts the pressure signal into a saturated temperature signal and sends it to the adder 63. In this adder 63, the bias signal from the setter 64 is added to the saturation temperature signal, which is converted into an added signal of the saturation temperature signal α and sent to the deviation calculator 61. This addition signal and the output signal are compared and calculated by a deviation calculator 61, and the deviation signal is sent to the upper limit limiter 54 via a proportional/integral/differential calculator 65. In the upper limit limiter 54, the upper limit value of the control signal to the cooling water valve 25 is determined based on the deviation signal, and the opening degree of the cooling water valve 25 is restricted.

The operation of the control device having these circuit configurations will be explained.

First, the steam flow rate correction, that is, the gain correction of the superheater 16 will be described. The amount of heat exchanged between the exhaust gas exhausted to the superheater 16 and the steam flowing through the superheater 16 is
The outlet steam flow rate sent from F to the high pressure steam turbine 22 is F.
1 The specific heat of steam is Cp.

When the temperature of the steam flowing into the superheater 16 is Ti, the outlet steam temperature To of the superheater 16 is expressed by the following equation from the heat balance.

To-T i 10/ (Cp ・F) (1)
Generally, if the steam flow ff1F sent to the superheater 16 is small, the influence on the exchange heat iQ becomes large, and the superheater 16
Since the gain of the control device becomes large, it is necessary to reduce the gain of the control device. Also, if the flow rate of steam sent to the superheater 16 increases while the gain of the control device is small, the superheater 1
Since the gain of 6 becomes small, controllability becomes worse. Therefore, it is necessary to provide the control device with an optimum gain in both a high flow rate region where a large amount of steam flows and a low flow region where only a small amount of steam flows.

In order to obtain this gain, first, the steam flow rate F flowing through the superheater 16 is detected by the steam flow rate detector 45. Also,
The temperature detector 41 detects the outlet steam temperature To flowing out from the superheater 16. The output signal of the steam flow rate detector 45 is subjected to function correction by a function generator 60, and then this output signal is sent to a multiplier 51. In addition, the temperature detector 41
The output signal is compared with the setting signal of the setting device 50 in the deviation calculation unit 49, and this deviation signal is sent to the multiplier 51. This multiplier 51 multiplies the output signal of the function generator 60 and the deviation signal of the deviation calculator 49, and this multiplied signal is sent to the adder 53 via the proportional/integral/differential calculator 52.

The adder 53 adds this multiplied signal and the feedforward signal from the feedforward calculation unit A, and sends the result to the upper limit limiter 54, where the upper limit value is controlled and the opening degree of the cooling water valve 25 is controlled.

Therefore, the outlet steam temperature Ti1 and the steam flow rate at the outlet of the superheater 16 are controlled by the valve opening control of the cooling water valve 25, that is, the phytback control is performed to maintain predetermined values of the steam temperature and steam flow rate. Gain correction is performed.

Next, the feedforward calculation section A will be explained.

The steam outlet temperature To of the superheater 16 is expressed by the above equation (1) from the heat balance.

In addition, the exhaust gas sent to the heat recovery boiler 15 and the superheater 16
The exchange heat ff1Q with the steam flowing through the heat recovery boiler 15 is experimentally determined by the following relationship, assuming that the exhaust gas flow rate Fg of the exhaust gas sent to the heat recovery boiler 15, the exhaust gas inflow temperature Tg, and the average steam temperature T12 of the superheater 16 are as follows. There is.

0.65 Q = -Fg (Tg - T12) (2) Therefore, from these relationships, detect the exhaust gas inflow temperature Tg, exhaust gas flow rate Fg, steam inflow temperature Ti, and steam flow rate F, and calculate the preceding What is necessary is to extract the control signal. Therefore, the signals of each detector are fed to the feedforward calculator 5.
5.57.58 and 59, and if the opening degree of the cooling water valve 25 is controlled using the preliminary output signal here, the superheater 1
6, the outlet steam temperature can always be kept at the optimum temperature.

That is, the middle part of the superheater 16 by the temperature detector 42,
Preferably, the steam inlet temperature Ti near the inlet is detected;
This detected temperature signal is sent to a phytoforward calculator 55 and then sent to an adder 56 as a preceding temperature signal. Similarly, the temperature Tg of the exhaust gas at the inlet of the heat recovery boiler 15 is detected by the temperature detector 44, and this detected temperature signal is sent to the phytoforward calculator 57 and sent to the adder 56 as a preceding temperature signal. The exhaust gas flow fiFg of the artificial part of the heat recovery boiler 15 is detected by the gas flow rate detector 48, and this detected flow rate signal is sent to the wide forward calculator 58 and sent to the adder 56 as a preceding flow rate signal. from the superheater 16 to the high temperature and high pressure steam turbine 2
2 is detected, and this detected flow rate signal is sent to a phytoforward calculator 59 and sent to an adder 56 as a preceding flow rate signal. Each of these feedforward signals is added by an adder 56, and the added feedforward signal is sent to an adder 53 that receives the multiplied signal. The adder 53 adds the phytoforward signal and the multiplication signal, that is, the phytoback signal, and this added signal is added to the upper limit limiter 53.
4 to the cooling water valve 25, which is controlled in advance, so that the steam outlet temperature of the superheater 16 can be controlled to a desired temperature.

Therefore, even if the load on the gas turbine 13 fluctuates and the temperature of its exhaust gas fluctuates, the steam turbine 22 is able to operate the superheater 1
6 is always controlled by an advance signal so that the steam does not get too hot.

Further, in order to prevent the superheater 16 from undergoing excessive temperature changes, the temperature detector 43 detects the outlet steam temperature of the desuperheater 27 and sends this detected temperature signal to the deviation calculator 61.

On the other hand, the pressure signal from the pressure detector 47 is converted into a saturated temperature signal by a function generator 62, and the adder 6 is applied to this saturated converted signal.
In step 3, the bias signal from the setting device 64 is added, and the signal is made into a sum signal of the saturated conversion signal α and sent to the deviation calculator 61. The deviation calculator 61 calculates the detected temperature signal and the saturation conversion signal α
This deviation signal is sent to the upper limit limiter 54 via the proportional/integral/differential calculator 65, and the upper limit value of the upper limit limiter 54 is set.

Therefore, when the opening degree of the cooling water valve 25 is controlled by the wide forward signal and the phytoback signal, the upper limit of the control signal is regulated to limit the opening degree of the cooling water valve 25, and the opening degree of the cooling water valve 25 is limited. Since the above amount of cooling water is not supplied, a large amount of water droplets may enter the superheater 16 due to load fluctuations, especially at low temperatures, which may cause damage such as thinning of the internal components of the superheater 16 and the turbine 22. do not have.

As explained above, by performing gain correction using phytoback control, wide forward control, and excessive fluctuation prevention control in this combined cycle power generation equipment, the flow rate of steam flowing into the high-temperature and high-pressure steam turbine 22 and the amount of steam heat input are Diagram (a)
Even if the steam changes as shown in FIG. 3(b), it can be controlled as shown in FIG. 3(b) and stable steam can be supplied to the high pressure turbine 22. Such control can also be performed in the reheater 17 by the same control as the above-mentioned control.

FIG. 4 shows another embodiment, and the same parts as those in FIG. 2 are given the same reference numerals, and the explanation thereof will be omitted. An addition differentiator 70 is connected to the output side of the feedforward calculation section A in place of the adder 56 in FIG. Therefore, each feedforward signal of each feedforward calculator 55, 57, 58, and 59 is added by an addition differentiator 70 and taken out as a differential signal, and this differential signal is passed through an adder 53 and an upper limit limiter 54. Cooling water valve 25
The opening degree of this cooling water valve 25 is controlled.

In this way, steam flow rate, steam temperature, exhaust gas flow rate,
The desuperheater 27 is controlled with good responsiveness to fluctuations in exhaust gas temperature, etc., without leaving any deviations, and the steam temperature can be stably controlled.

FIG. 5 shows still another embodiment, in which the same parts as in FIG. The output signals of 57, 58 and 59 are sent to the adder 56, this added signal is detected by the temperature detector 41, and is sent to the adder 71 which receives the deviation signal compared and set by the setter 50 and the deviation calculator 49. It will be done. In this adder 71, the addition signal of the feedforward calculator and the deviation signal of the temperature detector 41 are added, and the multiplier 5
1. The water is sent to the cooling water valve 25 via the proportional/integral/differential calculator 65 and the upper limit limiter 54, and its opening degree is controlled.

Since the addition signal of the adder 56 is added together with the deviation signal of the temperature detector 41 in the adder 71 in this way, the steam flow rate can be controlled by the feedback control signal and the feedforward signal, and the control characteristics for each steam flow rate region can be adjusted. can be improved.

FIG. 6 shows still another embodiment, and the same parts as those in FIG. 2 will be described with the same reference numerals. In addition to the temperature detector 42 and the flow rate detector 45, a power detector 72 for detecting the power of the generator 14 is provided as a detector. The detection signal of this power detector 72 is sent to a feedforward calculator 73 that obtains a preceding power change of the generator 14, and the feedforward signal is sent to an adder 56. Further, the detection signal of the power detector 72 is sent to a function generator 74 for function correction.

This correction signal is sent to the multiplier 74 together with a deviation signal from which the output signal of the temperature detector 41 is sent via the deviation calculator 49. This multiplier 74 multiplies the deviation signal from the deviation calculator 49 by the signal corrected by the function generator 73, and sends the multiplied signal through the proportional/integral/differential calculator 52, the adder 53, and the upper limit limiter 54. The cooling water valve 25 is controlled by the

The power detector 72 detects the power of the generator 14 in this way.
The output signal of is made into a feedforward signal by the feedforward calculator 73, and this feedforward signal is multiplied by the deviation signal of the temperature detector 41 by the multiplier 74, so that the detection function is simplified and the power of the generator 14 is reduced. Since the detection accuracy is accurate, the control characteristics for each steam flow rate region can be improved.

FIG. 7 shows another embodiment of the control device shown in FIG. Only the power detector 72 for detecting the power of the machine 14 is used.

In this way, the feedforward calculation section can be further simplified.

In addition, in FIGS. 6 and 7, the power signal of the generator 14 is used as the signal source of the feedforward calculation section A, but the fuel flow signal of the gas turbine, the fuel flow control signal, etc. may also be used in addition to this. Similar control can be performed.

〔Effect of the invention〕

In the present invention, the steam temperature of the superheater and reheater of combined power generation equipment,
The signals of the detectors that detect the steam flow rate, exhaust gas flow rate, and exhaust gas temperature are sent to the feedforward calculation section, and this feedforward calculation section extracts the feedforward signal that precedes the detection signal of each detector. Since the cooling water valve is controlled in advance of changes in the steam temperature and steam flow rate of the superheater and reheater, even if the load on the generator or gas turbine changes suddenly, overheating can be avoided. The steam temperature and steam flow rate of the reheater and reheater can be maintained at desired values. Therefore, no thermal stress is applied to the superheater, reheater, etc., and no water droplets are generated.

Further, since the upper limit limiter has its limit value determined in consideration of the supersaturation condition of steam, water droplets etc. do not flow into the superheater.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an outline of the steam temperature control device for the combined cycle power generation facility of the present invention. Fig. 2 is a block diagram of the steam temperature control device of the superheater in Fig. 1, and Fig. 3(a)
is a characteristic diagram showing the steam flow rate and steam heat input of the superheater in Figure 1, Figure 3(b) is a characteristic diagram showing the steam temperature of the superheater in Figure 1, and Figures 4 to 7 are , FIG. 2 is a block diagram showing another embodiment of the steam temperature control device for a superheater, FIG. 8 is a block diagram showing an outline of a steam temperature control device for a conventional combined power generation facility, and FIG. The figure is a block diagram of the steam temperature control device of the superheater in Figure 8, Figure 10 (a) is a characteristic diagram showing the steam flow rate and steam heat input amount of the superheater in Figure 8, and Figure 10 (b) is a block diagram of the steam temperature control device of the superheater in Figure 8. ) is a characteristic diagram showing the steam temperature of the superheater in FIG. 8. 10... Combined power generation equipment, 11... Compressor, 12...
・Superheater, 13... Gas turbine, 14... Generator, 15... Heat recovery boiler, 16... Superheater, 17.
... Reheater, 18... Steam generator, 19... Drum, 22... High pressure gas turbine, 24... Low pressure gas turbine, 24.25... Cooling water valve, 26.27.・・・
Desuperheater, 28... Temperature detector, 30... Deviation calculator, 31... Setting device, 33... Proportional/integral/derivative/j
t calculator, 40...combined power generation equipment, 41.41a, 42
．． 42a, 43.43g, 44 and 44a...temperature detector, 45.45a, 46 and 46a...steam flow rate detector, 47.47a...steam pressure detector, 48.
48a... Exhaust gas flow rate detector, 49.61... Deviation calculator, 50.64.66... Setting device, 51.74
...Multiplier, 52.65...Proportional/integral/differential calculator, 55.57.58.59 and 73...Feedforward calculator, 60.62.74...Function generator, 53 .56.71...Adder, 54...Upper limit limiter, 70...Additional differentiator, 72...Power detector.

Claims (1)

[Claims] 1. In a steam temperature control device for a combined power generation facility consisting of a gas turbine, an exhaust gas boiler, a steam turbine, etc., and in which each heater such as a superheater and a reheater installed in the exhaust gas boiler is provided with a desuperheater. , a feedback signal generating device for generating a feedback signal to the cooling water valve of the desuperheater based on a signal corresponding to the heater outlet temperature and the steam flow rate; and a feed forward signal generating device for generating a feedforward signal to the cooling water valve using a signal corresponding to the output of the combined power generating equipment. 1. A steam temperature control device for a combined power generation facility, comprising: a device; and an upper limit limiter that limits the upper limit of the sum of the feedback signal and the feedforward signal based on the steam temperature at the outlet of the desuperheater and the steam pressure signal.