JPH09195718A - Main steam temperature control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the rising rate of main steam temperature in an allowable range so as to restrain consumption of life of a steam turbine at minimum by adjusting the main steam temperature based on exhaust gas temperature of a gas turbine at starting process of the gas turbine so that the main steam temperature does not rise at over a specified allowable temperature changing rate. SOLUTION: Low pressure steam and high pressure steam are generated by exhaust gas of a gas turbine and superheated by superheaters 16, 18, 19. Main steam temperature obtained by superheating high pressure steam of an exhaust heat recovery boiler 48 supplying the steam to a steam turbine is controlled by supplying spray water to a high pressure main steam temperature reducer 23. At starting process of the gas turbine in particular, the main steam temperature is adjusted based on the exhaust gas temperature of the gas turbine, so that the main steam temperature does not rise exceeding a specified allowable temperature changing rate. Consequently, the temperature rising rate of main steam temperature generated from the exhaust heat recovery boiler 48 is restrained in an allowable range, thermal stress is not applied to the steam turbine, and hence consumption of the life of the steam turbine can be restrained at minimum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a main steam temperature control device for controlling a main steam temperature generated in an exhaust heat recovery boiler in a combined thermal power plant including a gas turbine and a steam turbine.

[0002]

2. Description of the Related Art Generally, a combined cycle power plant including a gas turbine and a steam turbine is called a combined cycle power plant. In recent combined cycle power plants, the inlet gas temperature of the gas turbine has been raised to cope with higher efficiency, larger capacity, etc., and thereby the exhaust gas temperature of the gas turbine has also been raised. As the temperature of the gas turbine exhaust gas rises, the outlet steam temperature (high-pressure main steam temperature) of the exhaust heat recovery boiler also tends to rise. Therefore, the temperature of the main steam supplied to the steam turbine tends to increase.

Since a steam turbine uses high-pressure steam, the casing has a thick wall and the rotor is exposed to high-temperature steam. Therefore, optimum steam conditions exist depending on the output. The current maximum value of the main steam temperature at the steam turbine inlet is about 538 ° C to 566 ° C. Therefore, if an operating condition occurs in which the main steam temperature exceeds this value, the upper limit value of the main steam temperature generated by the exhaust heat recovery boiler is set regardless of the load, and the main steam temperature is controlled to this value. doing.

FIG. 9 is a block diagram of the exhaust heat recovery boiler 48. Although illustration is omitted, the steam that has worked in the steam turbine is cooled in the condenser and becomes condensed water, which is stored in the condenser hot well. And the condensate stored in the hot well is
It is extracted by the condensate pump and is supplied to the low pressure economizer 2 of the waste heat recovery boiler 48 via the low pressure water supply pipe 1.

In the low-pressure coal economizer 2, all feed water is heated by heat exchange with the gas turbine exhaust gas that has become low in temperature. That is, the gas turbine exhaust gas in the low-pressure economizer 2 part is the gas turbine exhaust gas after heat exchange has already been performed in the other heat exchanger parts, and therefore has a low temperature. The water supply heated by the low-pressure coal economizer 2 is supplied to the high-pressure water supply pump 6 via the low-pressure communication pipe 4 and the low-pressure water supply control valve 5. The low pressure water supply control valve 5 adjusts the low pressure water supply amount so that the water level of the high pressure water supply pump 6 is kept constant.

On the other hand, the feed water heated by the low pressure economizer 2 is
It is supplied to the low-pressure steam drum 8 via the high-pressure feed water pump suction pipe 3 branched from the low-pressure connecting pipe 4, and the pressure is increased in the low-pressure steam drum 8. The pressurized water supply is supplied as high pressure water supply to the high pressure economizer 12 via the high pressure water supply pipe 7. Further, the low-pressure feed water is supplied via a low-pressure economizer inlet feed water temperature control pipe 28 and a low-pressure feed water temperature control valve 29 which branch from the high-pressure water feed pipe 7 on the discharge side of the low-pressure steam drum 8 and circulate to the inlet of the low-pressure economizer 2. It is supplied to the pipe 1 and the inlet temperature of the low pressure economizer 2 is adjusted to be constant.

The high-pressure feedwater supplied from the low-pressure steam drum 8 to the high-pressure economizer 12 is heated in the high-pressure economizer 12 by exchanging heat with the exhaust gas. It is supplied to the high-pressure steam drum 15 via the valve 14. That is, in the high pressure water supply control valve 14, the high pressure water supply amount is adjusted so as to keep the water level of the high pressure steam drum 15 constant,
It will be supplied to the high-pressure steam drum 15.

Next, the feed water supplied to the low pressure steam drum 8 exchanges heat with the exhaust gas in the low pressure evaporator 9 and returns to the low pressure steam drum 8 while generating low pressure steam. That is, the high-pressure water supply pump 6 and the low-pressure evaporator 9 are circulated while exchanging heat to generate low-pressure steam. The low-pressure steam separated by the high-pressure water supply pump 6 is supplied to the low-pressure superheater 11 via the low-pressure steam communication pipe 10 and exchanges heat with the exhaust gas to be supplied as superheated steam to the low-pressure stage of the steam turbine.

On the other hand, the feed water heated in the high-pressure coal economizer 12 and supplied to the high-pressure steam drum 15 exchanges heat with the exhaust gas in the high-pressure evaporator 16 and returns to the high-pressure steam drum 15 while generating high-pressure steam. That is, the high-pressure steam drum 15 and the high-pressure evaporator 16 are circulated while exchanging heat to generate high-pressure steam. The steam separated by the high-pressure steam drum 15 is passed through a high-pressure steam connecting pipe 17 to a high-pressure first stage superheater 18
And is heat-exchanged with the exhaust gas to become superheated steam. Then, it is supplied to the high-pressure main steam desuperheater 23 to bring the main steam temperature to a predetermined temperature, spray water is supplied by the high-pressure main steam desuperheater 23, and the high-pressure second-stage superheater 19 and the high-pressure main steam It is supplied to the high-pressure stage of the steam turbine via the steam pipe 20.

On the other hand, the steam that has finished its work in the high pressure stage of the steam turbine is reheated in the first reheater 21, the temperature is adjusted in the reheat steam desuperheater 26, and in the second reheater 22. After being heated again to hot steam, it is fed to the medium pressure stage of the steam turbine. Also for this reheat steam, the maximum allowable temperature determined by the material of the steam turbine and the like is set, and the temperature of the reheat steam is controlled to be equal to or lower than the allowable temperature regardless of a change in the operation state.

In this temperature control method, the heat transfer surface of the reheater is divided into a first reheater 21 and a second reheater 22, and the reheated steam is connected to the connecting pipes of the divided heat transfer surfaces. A desuperheater 26 is provided,
The amount of spray water to the reheated steam desuperheater 26 is adjusted by the reheated steam temperature control valve 27 according to the temperature of the reheated steam and supplied.
However, the reheaters 21 and 22 may not be installed depending on the scale of the plant.

Generally, the main steam temperature of the exhaust heat recovery boiler 48 is determined by the characteristic determining factors such as the exhaust gas inlet temperature, the exhaust gas amount, the steam amount and the heat transfer area. Further, the main steam temperature of the steam turbine has an upper limit value, and the main steam temperature is adjusted so as not to exceed this upper limit value. That is, the superheater is divided, and the high-pressure main steam desuperheater 23 is provided in the middle of the connecting pipe connecting the heat transfer surfaces of the divided superheaters 18 and 19, and the main steam temperature of the high-pressure main steam pipe 20 is changed. A system in which the amount of spray water supplied to the high-pressure main steam desuperheater 23 is adjusted by the high-pressure main steam temperature adjusting spray valve 25 to control the main steam temperature is generally adopted. The source of the spray water must have a pressure higher than the steam pressure and be able to adequately cope with changes in water volume. In the example of FIG. 9, the spray water is supplied from the reduced-temperature water supply pipe 24 branched from the high-pressure water supply pipe 7.

FIG. 10 is a control block diagram of the conventional main steam temperature adjustment. That is, based on the deviation between the high pressure main steam temperature and the set value, the main steam temperature controller 37 causes the high pressure main steam temperature control spray valve 25 to open based on the deviation between the high pressure main steam temperature and the set value. Is calculated. On the other hand, the high-pressure main steam temperature adjusting spray valve opening calculator 36 determines the high-pressure second steam superheater inlet steam temperature lower limit value obtained from the high-pressure steam drum pressure via the function generator 35, the spray water temperature, and the steam flow rate. Based on the above, the opening degree of the high pressure main steam temperature adjusting spray valve 25 is calculated so that the spray water does not flow into the high temperature second stage superheater 19 in the state of water droplets. Then, in the low value priority circuit 38, the smaller one of the output signals of the main steam temperature controller 37 and the high pressure main steam temperature adjusting spray valve opening calculator 36 is selected to open the high pressure main steam temperature adjusting spray valve 25. Will be adjusted. As described above, the main steam temperature control according to the conventional technique adopts the constant value control for keeping the set temperature constant regardless of the load, and when the constant value control is performed, the inside of the high temperature second superheater 19 is When the water content becomes supersaturated, the injection amount of spray water is limited.

[0014]

However, by adopting an operating method in consideration of an increase in capacity of the gas turbine and environmental measures, the exhaust gas temperature of the gas turbine tends to increase and the rate of temperature rise tends to increase. In particular, in an exhaust heat recovery boiler not equipped with an auxiliary combustion device, the outlet of the high-pressure second superheater 19 is governed by the characteristic determining factors such as exhaust gas inlet temperature, exhaust gas amount, steam amount, heat transfer area and the like. Since the steam temperature is determined, in the operating state in which the amount of steam generated is small (operating state in which the output of the gas turbine is low), that is, in the operating state at the startup stage of the gas turbine, the rate of rise of the main steam temperature is The temperature change is equivalent to.

If the steam temperature rises at the same rate as the temperature rise rate of the exhaust gas, it may exceed the allowable temperature rise rate of the steam turbine, so that the thermal stress of the steam turbine becomes abnormally large and the life consumption becomes large. Inconvenience occurs.

On the other hand, in order to solve such inconvenience,
It is necessary to control the steam temperature by changing the set temperature at a certain temperature rise rate. When performing this temperature control only by adjusting the amount of spray water, the injection amount of spray water is restricted so that water does not become supersaturated so that the spray water does not flow into the superheater in the state of water droplets.
It is difficult to control the main steam temperature rise rate only by adjusting the spray water amount.

That is, the limit value of this spray water amount is
Generally, it is necessary to set the amount of water such that the temperature does not drop below the temperature obtained by adding a margin of 30 to 50 ° C. to the saturation temperature with respect to the steam pressure of the spray injection portion. There will be a delay. For this reason, a state occurs in which the main steam temperature cannot be controlled to the set value, and as a result, the temperature rise rate also becomes higher than the initial target.

As described above, in the operating state in which the output of the gas turbine with a small amount of steam generation is low, the rate of increase of the main steam temperature is the same as that of the exhaust gas. In the case of constant steam temperature value control, steam temperature control is possible even with conventional technology, but in the case where the steam temperature rises at a rate equivalent to the temperature rise rate of exhaust gas, conventional steam temperature control The rate of increase in steam temperature may exceed the allowable rate of temperature increase in the steam turbine, which causes an inconvenience that the thermal stress of the steam turbine becomes abnormally large and the life consumption increases.

An object of the present invention is to keep the main steam temperature increase rate within the allowable range of the steam turbine without changing the load increase rate (fuel input amount) of the gas turbine, and to increase the steam without increasing the plant start-up time. It is an object of the present invention to provide a main steam temperature control device that minimizes the lifetime consumption of the turbine.

[0020]

The invention according to claim 1 is based on the exhaust gas temperature of the gas turbine so that the main steam temperature does not rise above a predetermined allowable temperature change rate during the starting process of the gas turbine. It is equipped with a main steam temperature adjusting device for adjusting the steam temperature. This prevents a rapid change in the main steam temperature and keeps it within the allowable thermal stress range of the steam turbine.

According to a second aspect of the present invention, in the first aspect of the present invention, the high-pressure steam temperature control device comprises an exhaust gas bypass passage for bypassing the exhaust gas of the gas turbine, and an exhaust gas flow rate adjustment damper provided in the exhaust gas bypass passage. The switch, the exhaust gas temperature detector that detects the exhaust gas temperature at the exhaust gas inlet side of the final stage superheater that superheats high-pressure steam, and the exhaust gas flow rate so that the exhaust gas temperature detected by the exhaust gas temperature detector reaches its set value. The exhaust gas flow rate controller for adjusting the damper opening degree of the adjustment damper switch.

Thus, the damper switch for adjusting the exhaust gas flow rate is opened / closed in accordance with the exhaust gas temperature, and the amount of the exhaust gas passing through the superheater is adjusted to prevent a rapid change in the main steam temperature.

According to a third aspect of the present invention, in the first aspect of the present invention, the high-pressure steam temperature control device is configured to inject compressed air into the exhaust gas of the gas turbine from the middle stage of the compressor that supplies the compressed air to the gas turbine. A connecting pipe, a damper switch for adjusting the compressed air amount provided in the compressed air connecting pipe, an exhaust gas temperature detector that detects the exhaust gas temperature at the exhaust gas inlet side of the final stage superheater that superheats high-pressure steam, and the exhaust gas temperature A compressed air amount controller for adjusting the damper opening of the compressed air amount adjusting damper switch so that the exhaust gas temperature detected by the detector becomes the set value.

Thus, the compressed air to be injected into the exhaust gas is adjusted according to the exhaust gas temperature, and the exhaust gas temperature passing through the superheater is adjusted, thereby preventing a rapid change in the main steam temperature.

According to a fourth aspect of the present invention, in the first aspect of the present invention, the high-pressure steam temperature control device comprises an exhaust gas temperature detector for detecting the exhaust gas temperature at the exhaust gas inlet side of the final stage superheater that superheats the high-pressure steam, A spray water flow controller for adjusting the flow rate of the spray water supplied to the high-pressure main steam desuperheater so that the exhaust gas temperature becomes the set value.

Thus, the flow rate of spray water is corrected according to the exhaust gas temperature to prevent a rapid change in the main steam temperature.

According to a fifth aspect of the invention, in the invention of the fourth aspect, the high-pressure steam temperature control device comprises a main steam desuperheater provided on the steam outlet side of the final stage superheater and a final stage for superheating the high pressure steam. Equipped with a main steam temperature controller for adjusting the flow rate of the spray steam from the inlet of the final stage superheater, which is supplied to the main steam desuperheater so that the main steam temperature on the steam outlet side of the superheater of Is.

Thus, the spray steam flow rate is adjusted according to the main steam temperature and the final superheater steam outlet main steam temperature is controlled to prevent a rapid change in the main steam temperature.

[0029]

Embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a first embodiment of the present invention. The first embodiment is a main steam that adjusts the main steam temperature based on the exhaust gas temperature of the gas turbine so that the main steam temperature does not rise above a predetermined allowable temperature change rate during the starting process of the gas turbine. Temperature control device 50
It is provided with. The high-pressure steam temperature control device 50 superheats high-pressure steam, and an exhaust gas bypass flow passage 41 that bypasses the exhaust gas of the gas turbine, an exhaust gas flow rate adjusting damper switch 42 provided in the exhaust gas bypass flow passage 41. Exhaust gas temperature detector 33 that detects the exhaust gas temperature at the exhaust gas inlet side of the final stage superheater 19, and a damper switch for adjusting the exhaust gas flow rate so that the exhaust gas temperature detected by this exhaust gas temperature detector 33 reaches its set value. 42
And an exhaust gas flow rate controller 34 that adjusts the damper opening degree. Since other configurations are the same as those of the conventional example shown in FIG. 9, the same elements are designated by the same reference numerals and the description thereof is omitted.

In FIG. 1, an exhaust gas temperature detector 33 is provided near the high pressure second stage superheater 19 which is the final stage superheater of the exhaust heat recovery boiler 48, and the exhaust gas from the gas turbine is high pressure second stage. An exhaust gas bypass passage 41 is provided so as to bypass the superheater 19. The exhaust gas bypass flow passage 41 bypasses the high pressure second stage superheater 19 and guides the exhaust gas from the gas turbine to the high pressure economizer 12 and the low pressure economizer 2 of the exhaust heat recovery boiler 48 and directly to the chimney. You can do it.

The flow rate of the exhaust gas flowing through the exhaust gas bypass passage 41 is adjusted by the damper opening degree of the damper switch 42 for adjusting the exhaust gas flow rate, and the damper opening degree is adjusted by the exhaust gas flow rate controller 34. FIG. 2 shows a control block diagram of the main steam temperature adjustment in the first embodiment. FIG.
In contrast to the conventional example shown in FIG. 0, the deviation between the exhaust gas temperature and the exhaust gas temperature set value is input to the exhaust gas flow rate controller 34, and the exhaust gas flow rate controller 34 uses the damper switch degree command value of the damper switch 42 for controlling the exhaust gas flow rate. Is added to control the damper opening of the exhaust gas flow rate adjusting damper switch 42.

As a result, when the exhaust gas temperature rapidly rises, the exhaust gas flow rate controller 34 opens and closes the damper opening degree of the exhaust gas flow rate adjusting damper switch 42. Although the effect of suppressing the high-pressure steam temperature rise by injecting the spray water with the high-pressure main steam temperature control spray valve 25 causes a considerable delay, it does not affect the superheated steam by opening / closing the damper opening of the exhaust gas flow rate control damper switch 42. The effect of reducing the amount of heat exchanged gradually appears and acts so that the high-pressure main steam temperature becomes the steam temperature set value. Therefore, it becomes possible to prevent a rapid change in the main steam temperature.

As described above, in the first embodiment, the exhaust gas bypass passage 41 that bypasses the high pressure second stage superheater 19 which is the final stage superheater is provided, and the high pressure second stage superheater 19 is provided. Since the flow rate of the exhaust gas passing therethrough is adjusted, it is possible to prevent a rapid change in the main steam temperature.

Next, a second embodiment of the present invention will be described. FIG. 3 is a block diagram showing a second embodiment of the present invention. In the second embodiment, the compressed air is injected into the exhaust gas from the gas turbine so that the high pressure second stage superheater 19
By adjusting the temperature of the exhaust gas passing through, the rapid change of the main steam temperature is prevented.

That is, a compressed air communication pipe 44 for injecting compressed air is provided at the inlet of the exhaust heat recovery boiler, and a compressed air amount adjusting damper switch 4 provided in the compressed air communication pipe 44.
With the damper opening of 5, the temperature of the gas flowing into the second stage superheater 19, which is the final stage superheater that superheats the high-pressure steam, is adjusted.

In FIG. 3, the compressed air is supplied from the middle stage of the compressor for supplying the compressed air to the gas turbine to the compressed air amount adjusting damper switch 45 of the high pressure steam temperature adjusting device 50 through the compressed air connecting pipe 44. . The damper opening of the compressed air amount adjusting damper switch 45 is adjusted by the compressed air amount adjusting device 43. That is, the compressed air amount adjuster 43 uses the compressed air amount adjusting damper switch 45 so that the exhaust gas temperature at the exhaust gas inlet side of the high-pressure second-stage superheater 19 detected by the exhaust gas temperature detector 33 becomes the set value. Adjust the damper opening of.

FIG. 4 shows a control block diagram for main steam temperature adjustment according to the second embodiment. In contrast to the conventional example shown in FIG. 10, the deviation between the exhaust gas temperature and the exhaust gas temperature set value is input to the compressed air amount adjuster 43, and the compressed air amount adjuster 43 uses the damper switch 45 for adjusting the compressed air amount. A control element for calculating the opening / closing degree command value and controlling the damper opening degree of the compressed air amount adjusting damper switch 45 is added.

When the exhaust gas temperature of the gas turbine rises abruptly, the effect of suppressing the high-pressure steam temperature rise by the injection of spray water is delayed considerably, but the exchange heat of superheated steam is reduced by the injection of compressed air into the exhaust gas. The effect of appears gradually and acts to bring the high-pressure main steam temperature to the steam temperature set value.

As described above, in the second embodiment, the temperature of the exhaust gas passing through the superheater is controlled by injecting the compressed air into the exhaust gas, so that the amount of heat exchange from the exhaust gas to the main steam is also controlled. Therefore, it is possible to suppress a rapid change in the main steam temperature. As a result, an increase in the steam temperature can be suppressed, and the temperature can be controlled even when the rate of change restriction is required.

FIG. 5 is a block diagram showing the third embodiment of the present invention. In the third embodiment, the opening of the high-pressure main steam temperature adjusting spray valve 25 is adjusted according to the exhaust gas temperature, and the spray water flow rate in the high-pressure main steam desuperheater 23 is corrected. is there.

The high-pressure steam temperature control device 50 includes an exhaust gas temperature detector 33 for detecting the exhaust gas temperature at the exhaust gas inlet side of the second stage superheater 19 which is the final stage superheater for superheating high pressure steam, and the exhaust gas temperature It is provided with a spray water flow rate controller 46 that adjusts the flow rate of the spray water supplied to the high-pressure main steam desuperheater 23 so that it becomes a set value.

That is, the high pressure main steam temperature adjusting spray valve 2 is controlled by the spray water flow controller 46 in accordance with the exhaust gas temperature.
5 is adjusted to correct the spray water amount of the high-pressure main steam desuperheater 23 to prevent a rapid change in the main steam temperature. In this way, the high pressure first stage superheater 1 is controlled by the spray water flow controller 46.
8 and the high pressure second stage superheater 19 between the high pressure main steam desuperheater 2
When the spray water amount control to 3 is performed, the delay due to the heat capacity of the high pressure second stage superheater 19 can be avoided as compared with the case where the spray water amount of the high pressure main steam desuperheater 23 is adjusted based on the main steam temperature. The response can be quick.

FIG. 6 shows a control block diagram for main steam temperature adjustment according to the third embodiment. In comparison with the conventional example shown in FIG. 10, in controlling the high pressure main steam temperature adjusting spray valve 25,
The exhaust gas temperature and its set value are used instead of the main steam temperature and its set value. The deviation between the exhaust gas temperature and its set value is input to the exhaust gas temperature controller 40, and the valve opening command of the high pressure main steam temperature adjusting spray valve 25 is calculated based on the deviation. Then, the smaller one of the output signals from the high pressure main steam temperature adjusting spray valve calculator 36 is selected by the low value priority circuit 38 and the high pressure main steam temperature adjusting spray valve 2 is selected.
5 valve opening command.

When the exhaust gas temperature rapidly rises, the exhaust gas temperature controller 40 adjusts the spray flow rate. The effect of suppressing the rise in high-pressure steam temperature by spray water injection is
Although there is a considerable delay, the effect of reducing the heat of exchange with superheated steam by injection of spray water gradually appears and acts to bring the high-pressure main steam temperature to the steam temperature set value.

As described above, in the third embodiment, the amount of heat exchange is reduced in advance by adjusting the spray flow rate to the high-pressure main steam desuperheater 23 according to the exhaust gas temperature, so that the rise in steam temperature is suppressed. The target temperature control is possible even when the rate of change limitation is required.

Next, a fourth embodiment of the present invention will be described. FIG. 7 is a block diagram showing a fourth embodiment of the present invention. The fourth embodiment is different from the third embodiment shown in FIG. 5 in that a main steam temperature controller 32 and a main steam desuperheater 47 are newly provided, and the main steam desuperheater 47 is sprayed. As the steam, the steam from the superheater bypass steam pipe 30 is used. And the main steam temperature controller 3
Reference numeral 2 adjusts the spray steam flow rate according to the main steam temperature of the high-pressure main steam pipe 20, and controls the steam outlet main steam temperature of the high-pressure second-stage superheater 19, which is the final superheater, to control the main steam temperature. Prevent sudden changes.

In FIG. 7, a high pressure steam temperature controller 50
Is an exhaust gas temperature detector 33 that detects the exhaust gas temperature at the exhaust gas inlet side of the second-stage superheater 19 that is the final stage superheater that superheats the high-pressure steam, and high-pressure main steam so that the exhaust gas temperature reaches its set value. A spray water flow controller 46 for adjusting the flow rate of spray water supplied to the desuperheater 23, and
The main steam desuperheater 47 provided on the steam outlet side of the high pressure second stage superheater 19 and the main steam desuperheater so that the main steam temperature on the steam outlet side of the high pressure second stage superheater 19 becomes the set value. And a main steam temperature controller 32 for adjusting the flow rate of the spray steam from the inlet of the high-pressure second-stage superheater 19 supplied to the reactor 47.

In this way, if the main steam temperature controller 32 controls the amount of spray steam to the main steam desuperheater 47 at the outlet of the high pressure second stage superheater 19, the high pressure first stage superheater 18
As compared with the control of the amount of spray water between the high pressure second stage superheater 19 and the high pressure second stage superheater 19, a delay due to the heat capacity and heat exchange of the high pressure second stage superheater 19 can be avoided, so that the control response can be accelerated.

FIG. 8 shows a control block diagram for main steam temperature adjustment according to the fourth embodiment. In contrast to the third embodiment shown in FIG. 6, a main steam temperature controller 32 that adjusts the main steam temperature control valve 31 based on the deviation between the high pressure main steam temperature of the high pressure main steam pipe 20 and its set value is provided. It is additionally provided. The deviation between the high-pressure main steam temperature and its set value is input to the differentiator 39 of the main steam temperature controller 32, the change rate of the high-pressure main steam temperature is calculated, and the main steam temperature adjusting valve opening degree is calculated based on the change rate. The calculator 49 calculates the valve opening of the main steam temperature adjusting valve 31.

When the exhaust gas temperature rises sharply, the exhaust gas temperature controller 40 calculates the valve opening command of the high pressure main steam temperature adjusting spray valve 25, and the spray water is injected into the high temperature second stage desuperheater 23. It At the same time, the temperature deviation differentiated by the differentiator 39 also sharply rises, so the main steam temperature controller 32 increases the spray steam flow rate of the main steam reducer 47. At this time, the effect of suppressing the rise in high-pressure steam temperature by injecting spray water causes a considerable delay, but the effect of reducing the amount of heat exchanged into superheated steam by injecting spray steam into the main steam desuperheater 47 gradually appears, It acts to bring the high pressure main steam temperature to the steam temperature set point.

According to the fourth embodiment, the heat exchange amount of the high-pressure main steam (superheated steam) is obtained from the differential value of the main steam temperature deviation, and the main steam temperature controller 32 uses the high pressure second stage superheater 1
Since the amount of heat exchange is reduced by injecting the spray steam into the main steam desuperheater 47 on the steam outlet side of No. 9, the rise in steam temperature can be suppressed, and the main steam temperature can be controlled even when the rate of change restriction is required. It can be controlled.

[0052]

As described above, according to the first aspect of the present invention, the temperature rise rate of the main steam temperature generated from the exhaust heat recovery boiler is kept within the allowable range and thermal stress is applied to the steam turbine. , The life consumption of the steam turbine can be minimized.

According to the second aspect of the present invention, the exhaust gas is branched to reduce the amount of heat exchange with the feed water, so that heat can be exchanged with an appropriate amount of exhaust gas. Therefore, it is possible to suppress an excessive rise in the steam temperature, and it is possible to perform appropriate temperature control even when the rate of change in steam temperature needs to be limited.

According to the third aspect of the invention, the compressed air is injected into the exhaust gas to reduce the amount of heat exchange with the feed water, so that the rise in the steam temperature can be suppressed and the rate of change of the steam temperature needs to be limited. Even in such a case, proper temperature control is possible.

According to the fourth aspect of the invention, since the spray flow rate is adjusted by the exhaust gas temperature control device to cause the heat exchange amount to occur, the rise in the steam temperature can be suppressed in advance, and the rate of change in the steam temperature can be reduced. Appropriate temperature control is possible even when restrictions are required.

According to the fifth aspect of the present invention, the heat exchange amount of the high temperature steam is obtained from the differential value of the steam temperature deviation, and the main steam temperature reducer provided on the steam outlet side of the final stage superheater in the main steam temperature controller. Since the amount of heat exchange is reduced by injecting the spray steam into the vessel, the rise in steam temperature can be suppressed in advance.
Therefore, even when the rate of change of steam temperature needs to be limited, proper steam temperature control is possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a control block diagram of main steam temperature adjustment according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is a control block diagram of main steam temperature adjustment according to the second embodiment of the present invention.

FIG. 5 is a block diagram showing a third embodiment of the present invention.

FIG. 6 is a control block diagram for main steam temperature adjustment according to a third embodiment of the present invention.

FIG. 7 is a block diagram showing a fourth embodiment of the present invention.

FIG. 8 is a control block diagram of main steam temperature adjustment according to a fourth embodiment of the present invention.

FIG. 9 is a block diagram showing a conventional example.

FIG. 10 is a control block diagram for main steam temperature adjustment according to a conventional example.

[Explanation of symbols]

 1 low-pressure water supply pipe 2 low-pressure coal economizer 3 high-pressure water supply pump suction pipe 4 low-pressure communication pipe 5 low-pressure water supply control valve 6 high-pressure water supply pump 7 high-pressure water supply pipe 8 low-pressure steam drum 9 low-pressure evaporator 10 low-pressure steam communication pipe 11 low-pressure superheater 12 High pressure economizer 13 High pressure connecting pipe 14 High pressure water supply control valve 15 High pressure steam drum 16 High pressure evaporator 17 High pressure steam connecting pipe 18 High pressure first stage superheater 19 High pressure second stage superheater 20 High pressure main steam pipe 21 First re- Heater 22 Second reheater 23 High pressure main steam desuperheater 24 Dehumidifying water supply pipe 25 High pressure main steam temperature control spray valve 26 Reheat steam desuperheater 27 Reheat steam temperature control valve 28 Low pressure economizer inlet water supply Temperature control pipe 29 Low-pressure feed water temperature control valve 30 Superheater bypass steam pipe 31 Main steam temperature control valve 32 Main steam temperature controller 33 Exhaust gas temperature detector 34 Exhaust gas flow controller 35 Function generation 36 High pressure main steam temperature control Spray valve opening calculator 37 Main steam temperature controller 38 Low value priority circuit 39 Differentiator 40 Exhaust gas temperature controller 41 Exhaust gas bypass flow path 42 Exhaust gas flow rate adjustment damper switch 43 Compressed air amount adjustment Device 44 Compressed air connecting pipe 45 Compressor switch for controlling compressed air amount 46 Spray water amount controller 47 Main steam desuperheater 48 Exhaust heat recovery boiler 49 Main steam temperature control valve opening degree calculator 50 Main steam temperature adjusting device

Claims (5)

[Claims] 1. A main steam temperature obtained by superheating the high pressure steam of an exhaust heat recovery boiler, which generates high-pressure steam and low-pressure steam from exhaust gas from a gas turbine, superheats them in a superheater and supplies them to a steam turbine. In a main steam temperature control device for supplying spray water to a steam desuperheater to control, the gas turbine is controlled so that the main steam temperature does not rise above a predetermined allowable temperature change rate during a starting process of the gas turbine. A main steam temperature control device comprising a main steam temperature adjusting device for adjusting the main steam temperature based on the exhaust gas temperature of the above. 2. The high-pressure steam temperature control device comprises an exhaust gas bypass passage for bypassing exhaust gas from the gas turbine, an exhaust gas flow rate adjusting damper switch provided in the exhaust gas bypass passage, and the high-pressure steam being superheated. An exhaust gas temperature detector for detecting the exhaust gas temperature at the exhaust gas inlet side of the final stage superheater, and the exhaust gas flow rate adjusting damper switch so that the exhaust gas temperature detected by the exhaust gas temperature detector becomes a predetermined set value. 2. The main steam temperature control device according to claim 1, further comprising: an exhaust gas flow rate controller that adjusts the damper opening degree. 3. The high-pressure steam temperature control device, a compressed air connecting pipe for injecting compressed air into the exhaust gas of the gas turbine from a compressor middle stage for supplying compressed air to the gas turbine, and the compressed air connecting pipe. A damper switch for adjusting the compressed air amount provided in the exhaust gas temperature detector, an exhaust gas temperature detector that detects the exhaust gas temperature at the exhaust gas inlet side of the final stage superheater that superheats the high-pressure steam, and the exhaust gas temperature detector. 2. A compressed air amount controller for adjusting the damper opening of the compressed air amount adjusting damper switch so that the exhaust gas temperature becomes a predetermined set value.
Main steam temperature control device described in. 4. An exhaust gas temperature detector for detecting an exhaust gas temperature at an exhaust gas inlet side of a final stage superheater that superheats the high pressure steam, and the exhaust gas temperature reaches a predetermined set value. The main steam temperature controller according to claim 1, further comprising a spray water flow rate controller that adjusts a flow rate of spray water supplied to the high-pressure main steam desuperheater. 5. The high-pressure steam temperature control device comprises a main steam desuperheater provided on a steam outlet side of the final stage superheater and a main steam outlet side of a final stage superheater that superheats the high pressure steam. A main steam temperature controller for adjusting the flow rate of spray steam from the inlet of the final stage superheater which is supplied to the main steam desuperheater so that the steam temperature becomes a predetermined set value. 4. The main steam temperature control device according to 4.