JPH1038201A - Control method and apparatus for outlet supply water temperature of gas high pressure supply water heater in exhaust recombustion type combined cycle plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control water supply temperature at an outlet of a gas high pressure water supply heater by adjusting the flow rate of supply water distributed to a high pressure water supply heater and the gas high pressure water supply heater through the opening adjustment of a flow rate adjusting valve of the high pressure supply water heater. SOLUTION: There is estimated a supply water flow rate corrected value of a high pressure supply water heater based upon an outlet supply water temperature deviation 29 between an outlet supply water temperature set value 25 of a gas high pressure supply water heater and outlet supply water temperature of the gas high pressure supply water heater on the basis of a boiler loading instruction 19. Then, a supply water flow rate correction set value of a high pressure supply water heater is estimated by adding the supply water flow rate correction value to a supply water flow rate set value 27 of the high pressure supply water heater based upon the boiler loading instruction 19 such that a supply water lowest flow rate of line high pressure supply water heater. Hereby, an opening of a flow rate adjusting valve 12 of the supply water heater is adjusted in response to a supply water flow rate deviation 39 between the supply water flow rate correction set value 37 and an actual supply water flow rate 23, and hence the outlet supply water temperature 18 of the gas high pressure supply water heater 11 is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the outlet feedwater temperature of a high-pressure gas feedwater heater in an exhaust gas reburning combined cycle plant.

[0002]

2. Description of the Related Art In general, a power plant using a boiler includes:
As shown in FIG. 5, while burning fuel in the boiler main body 1, feed water pumped by the feed water pump 2 is guided to the boiler main body 1 through the high pressure feed water heater 3, and heated to generate steam, The steam is supplied to the steam turbine 4 to drive the steam turbine generator 5 to generate electric power. A part of the steam after driving the steam turbine generator 5 is guided to the high-pressure feed water heater 3, and the boiler body 1 is heated, but in recent years, an existing plant as shown in FIG. 5 has been remodeled, and as shown in FIG.
Attempts have been made to achieve an exhaust gas reburning combined cycle plant with improved thermal efficiency.

[0003] The exhaust gas reburning combined cycle plant is driven by combustion gas supplied from a combustor 6 and drives a gas turbine generator 7 and a compressor 8. And a gas which is provided in parallel with the high-pressure feed water heater 3 and heats a part of the feed water by the exhaust gas discharged from the boiler body 1. The high pressure feed water heater 11 is additionally provided.

[0006] In the exhaust reburning combined cycle plant shown in FIG. 6, fuel injected into the combustor 6 mixes with compressed air supplied from a compressor 8 and burns. The combustion gas is supplied to the gas turbine 9, the compressor 8 and the gas turbine generator 7 are driven to generate electric power, and the exhaust gas of the gas turbine 9 after driving the gas turbine generator 7 is discharged from the wind path evaporator. In 10, the temperature is lowered to a required temperature and guided to the boiler main body 1, where the exhaust gas is supplied to the boiler main body 1 for combustion as a fuel combustion gas. The high pressure feed water heater 11 heats a part of the feed water by the exhaust gas, and the high pressure feed water heater 3 heats the feed water by steam from the steam turbine 4. Wherein it is merged with the water supply is guided to the boiler body 1, and is vaporized.

[0005]

In the above-described exhaust-refueling combined cycle plant, the opening of one flow control valve 12 of the high-pressure feed water heater 3 is reduced in view of simplification of the equipment configuration and economy. By adjusting appropriately,
It is desired to adjust the flow rate of the feed water distributed to the high-pressure feed water heater 3 and the high-pressure gas feed water heater 11 to control the outlet feed temperature of the high-pressure gas feed water heater 11. At the present time, no specific means for controlling the outlet water temperature of the eleventh outlet has been established.

In view of this situation, the present invention adjusts the flow rate of the feedwater distributed to the high-pressure feedwater heater 3 and the gas high-pressure feedwater heater 11 by adjusting the opening of the flow control valve 12 of the high-pressure feedwater heater 3. It is an object of the present invention to provide a method and an apparatus for controlling the outlet feedwater temperature of a gas high-pressure feedwater heater in an exhaust gas reburning combined cycle plant that can adjust and control the outlet feedwater temperature of a gas high-pressure feedwater heater 11.

[0007]

The present invention uses the exhaust gas of a gas turbine 9 as a fuel combustion gas in a boiler body 1 and uses a high-pressure feed water heater 3 and a gas high-pressure feed water heater 11 to heat the boiler body 1. A method for controlling the outlet feed water temperature of a gas high pressure feed water heater in an exhaust gas reburning combined cycle plant configured to heat feed water to a gas, wherein the gas high pressure feed water heater 1 based on a boiler load command 19
Outlet feed water temperature set point 25 and gas high pressure feed water heater 11
From the outlet water temperature deviation 29 from the actual outlet water temperature 18, the feed water flow correction value of the high pressure feed water heater 3 is obtained, and the feed water flow correction value of the high pressure feed water heater 3 is calculated based on the boiler load command 19. The feedwater flow rate correction set value 37 of the high-pressure feedwater heater 3 is obtained by adding the minimum feedwater flow rate of the high-pressure feedwater heater 3 to the feedwater flow rate set value 27 of the high-pressure feedwater heater 3 to obtain the high-pressure feedwater heater. The opening degree of the flow control valve 12 of the high-pressure feed water heater 3 is adjusted according to the feed water flow deviation 39 between the feed water flow correction set value 37 of FIG. The method according to the present invention relates to a method for controlling the outlet feedwater temperature of a high-pressure gas feedwater heater in an exhaust gas reburning combined cycle plant characterized by controlling the temperature of the exhaust gas.

Further, the present invention uses the exhaust gas of the gas turbine 9 as a fuel combustion gas in the boiler main body 1, and supplies water to the boiler main body 1 by the high pressure feed water heater 3 and the gas high pressure feed water heater 11. An outlet feedwater temperature control device of a gas high pressure feedwater heater in an exhaust reburn type combined cycle plant that is heated, and a function of outputting an outlet feedwater temperature set value 25 of the gas high pressure feedwater heater 11 based on a boiler load command 19. A function generator 26 for outputting a feed water flow rate set value 27 of the high-pressure feed water heater 3 based on the boiler load command 19;
A subtractor 28 for calculating a difference between an outlet feedwater temperature set value 25 of the gas high-pressure feedwater heater 11 and an outlet feedwater temperature 18 of the gas high-pressure feedwater heater 11 and outputting an outlet feedwater temperature deviation 29; Set value of minimum feed water flow 3 of feed water heater 3
1 and a difference between a feed water flow rate set value 27 of the high-pressure feed water heater 3 output from the function generator 26 and a subtractor 32 for outputting a flow rate set value deviation 33, and an output from the subtracter 28. Outlet feedwater temperature deviation 2 of gas high pressure feedwater heater 11
9 is proportionally integrated to obtain a feedwater flow correction value of the high-pressure feedwater heater 3. If the feedwater flow correction value of the high-pressure feedwater heater 3 is larger than the flow rate set value deviation 33 output from the subtractor 32, When the correction value of the feedwater flow rate of the high-pressure feedwater heater 3 is output as it is as the correction command 35, the correction value of the feedwater flow rate of the high-pressure feedwater heater 3 is equal to or less than the flow rate set value deviation 33 output from the subtractor 32. The proportional integral controller 34 with a low signal limiter that outputs the flow rate set value deviation 33 as a correction command 35 and the feed water flow rate set value 27 of the high pressure feed water heater 3 output from the function generator 26 An adder 36 for adding a correction command 35 output from the proportional-integral controller 34 with the low-signal limiter and outputting a set value 37 of a feedwater flow rate correction of the high-pressure feedwater heater 3; Flow 23 and a subtractor 38 for obtaining a difference between a feed water flow correction set value 37 of the high pressure feed water heater 3 outputted from the adder 36 and outputting a feed water flow deviation 39 of the high pressure feed water heater 3; A proportional-integral controller 40 for proportionally integrating the feedwater flow rate deviation 39 of the high-pressure feedwater heater 3 output from 38 and outputting the opening degree command 21 to the flow control valve 12 of the high-pressure feedwater heater 3. The present invention relates to an outlet feedwater temperature control device for a gas high-pressure feedwater heater in an exhaust gas reburning combined cycle plant.

According to the above means, the following effects can be obtained.

In the method of controlling the outlet water temperature of the gas high pressure feed water heater in the exhaust gas reburning combined cycle plant according to the present invention, the outlet water temperature setting value 25 of the gas high pressure feed water heater 11 based on the boiler load command 19 and the gas high pressure feed water A feedwater flow correction value of the high-pressure feedwater heater 3 is determined from an outlet feedwater temperature deviation 29 from the actual outlet feedwater temperature 18 of the heater 11, and the feedwater flow correction value of the high-pressure feedwater heater 3 is converted into a boiler load command 19. The high-pressure feed water heater 3 is added to the feed water flow rate set value 27 of the high-pressure feed water heater 3 so that the minimum feed water flow rate of the high-pressure feed water heater 3 is secured.
The water supply flow rate correction set value 37 of the high pressure water supply heater 3 is obtained, and the flow rate adjustment valve 12 of the high pressure water supply heater 3 is adjusted according to the water supply flow rate deviation 39 between the water supply flow rate correction set value 37 of the high pressure water supply heater 3 and the actual water supply flow rate 23. The opening is adjusted, and the outlet feedwater temperature 18 of the gas high-pressure feedwater heater 11 is controlled.

In the control apparatus for controlling the outlet water temperature of the gas high pressure feed water heater in the exhaust gas reburning combined cycle plant according to the present invention, the outlet water temperature of the gas high pressure feed water heater 11 is generated by the function generator 24 based on the boiler load command 19. The set value 25 is obtained and output to the subtracter 28,
Based on the boiler load command 19, a function generator 26 calculates a feedwater flow rate set value 27 of the high-pressure feedwater heater 3, outputs it to a subtractor 32 and an adder 36, and outputs the subtractor 28 from the function generator 24. Gas high pressure feed water heater 1
1 and the outlet water temperature 18 of the gas high-pressure water heater 11 detected by the temperature detector 17.
Is output to a proportional-integral controller 34 with a low-signal limiter, and a subtractor 32 sets a minimum feedwater flow rate setting value 31 of the high-pressure feedwater heater 3 to:
The difference from the feed water flow rate set value 27 of the high pressure feed water heater 3 output from the function generator 26 is obtained, and the flow rate set value deviation 33 is output to the proportional signal integral controller 34 with a low signal limiter.
In the proportional-integral controller 34 with the low signal limiter, the outlet feedwater temperature deviation 29 of the gas high-pressure feedwater heater 11 output from the subtracter 28 is proportionally integrated, and the high-pressure feedwater heater 3 is processed.
If the feedwater flow correction value of the high-pressure feedwater heater 3 is larger than the flow rate set value deviation 33 output from the subtractor 32, the high-pressure feedwater heater 3
Is output to the adder 36 as the correction command 35 as it is, while the feedwater flow correction value of the high-pressure feedwater heater 3 is equal to or less than the flow rate set value deviation 33 output from the subtractor 32. The flow rate set value deviation 33 is output as a correction command 35 to the adder 36, and the adder 36 outputs the low signal limit value for the feed water flow rate set value 27 of the high pressure feed water heater 3 output from the function generator 26. The correction command 35 output from the proportional integral adjuster 34 is added, and the feed water flow rate correction set value 37 of the high-pressure feed water heater 3 is output to the subtractor 38.
Feed water flow 2 flowing through high pressure feed water heater 3 output from 2
3 and the high pressure feed water heater 3 output from the adder 36
Of the feed water flow correction set value 37 is obtained, and the feed water flow deviation 39 of the high-pressure feed water heater 3 is output to the proportional-integral controller 40, where the subtracter 38
Is proportionally integrated and the opening command 21 is output to the flow control valve 12, and the opening of the flow control valve 12 is adjusted according to the opening command 21. High-pressure feed water heater 3 and gas high-pressure feed water heater 1
The flow rate of feed water distributed to 1 is adjusted, and the outlet feed water temperature of the gas high-pressure feed water heater 11 is controlled to be the outlet feed water temperature set value 25.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 show an embodiment of the present invention, in which the same reference numerals as those in FIG. 6 denote the same parts, and reference numeral 13 denotes a discharge flow rate of the water supply pump 2. 14
15 is a gas high pressure feed water heater 11
A flow detector for detecting a feed water flow rate 16 flowing through the heater, 17 a temperature detector for detecting an outlet feed water temperature 18 of the gas high-pressure feed water heater 11, and 20 a discharge flow rate 14 of the feed water pump 2 detected by the flow detector 13. And a feed water flow 16 flowing through the gas high-pressure feed water heater 11 detected by the flow detector 15.
The outlet water temperature 18 of the gas high-pressure feed water heater 11 detected by the temperature detector 17, and the boiler load command (MW
D) Based on 19, the flow control valve 1 of the high pressure feed water heater 3
2 is a controller that outputs an opening command 21 to the controller 2.

As shown in FIG. 2, the controller 20 controls the discharge flow rate 1 of the feed water pump 2 detected by the flow rate detector 13.
4 and the flow rate of the feed water flowing through the high-pressure feed water heater 11 detected by the flow rate detector 15, and a subtracter 22 that outputs a flow rate 23 of the feed water flowing through the high-pressure feed water heater 3.
And the gas high pressure feed water heater 1 based on the boiler load command 19
1 is a function generator 24 for obtaining and outputting an outlet feedwater temperature set value 25, and a function generator 2 for obtaining and outputting a feedwater flow rate set value 27 of the high-pressure feedwater heater 3 based on a boiler load command 19.
6, the difference between the outlet feedwater temperature set value 25 of the gas high-pressure feedwater heater 11 output from the function generator 24 and the outlet feedwater temperature 18 of the gas high-pressure feedwater heater 11 detected by the temperature detector 17. And a subtractor 28 for outputting an outlet feedwater temperature deviation 29, and a high-pressure feedwater heater 3 from the steam turbine 4.
Before the steam extraction to the high pressure feed water heater 3, 0 [ton / h] is output as the minimum feed water flow rate setting value 31 of the high pressure feed water heater 3 (switched to the a side), while the steam from the steam turbine 4 to the high pressure feed water heater 3 is output. After bleeding, a switch 30 that outputs α [ton / h] as the minimum feed water flow rate setting value 31 of the high pressure feed water heater 3 (switched to the b side), and a high pressure feed water heater 3 output from the switch 30 Minimum supply water flow set value 31
And a subtractor 32 that calculates a difference between a set value 27 of the feed water flow rate of the high-pressure feed water heater 3 output from the function generator 26 and outputs a deviation 33 of the set flow value, and a gas output from the subtracter 28. Outlet feedwater temperature deviation 29 of high pressure feedwater heater 11
Is proportionally integrated to obtain a feedwater flow correction value of the high-pressure feedwater heater 3. If the feedwater flow correction value of the high-pressure feedwater heater 3 is larger than the flow set value deviation 33 output from the subtractor 32, When the feedwater flow correction value of the high-pressure feedwater heater 3 is output as it is as the correction command 35, while the feedwater flow correction value of the high-pressure feedwater heater 3 is equal to or less than the flow set value deviation 33 output from the subtractor 32, The proportional integral controller 34 with a low signal limiter that outputs the flow rate set value deviation 33 as a correction command 35 and the feed water flow rate set value 27 of the high pressure feed water heater 3 output from the function generator 26 An adder 36 for adding a correction command 35 output from a proportional-integral controller 34 with a low-signal limiter and outputting a set value 37 of a feedwater flow rate correction of the high-pressure feedwater heater 3, and a high-pressure feedwater output from the subtractor 22. The difference between the feedwater flow rate 23 flowing through the heater 3 and the feedwater flow correction set value 37 of the high-pressure feedwater heater 3 output from the adder 36 is obtained, and a subtraction for outputting a feedwater flow rate deviation 39 of the high-pressure feedwater heater 3 is performed. And the subtractor 38
And a proportional-integral controller 40 for proportionally integrating the feedwater flow rate deviation 39 of the high-pressure feedwater heater 3 and outputting the opening command 21 to the flow control valve 12.

[0015] Incidentally, the function generator 24, the function F ₁ (x) as shown in FIG. 3 is input, The function F ₁
(X) indicates that the outlet feedwater temperature set value 25 of the gas high-pressure feedwater heater 11 is increased or decreased substantially in proportion to the increase or decrease of the boiler load command 19.

[0016] Also, in the function generator 26, the function F ₂ (x) as shown in FIG. 4 is input, the function number F ₂
(X) indicates that the feedwater flow rate setting value 27 of the high-pressure feedwater heater 3 is increased / decreased in substantially proportion to the increase / decrease of the boiler load command 19.

Next, the operation of the illustrated example will be described.

In operation, the difference between the discharge flow rate 14 of the feed water pump 2 detected by the flow rate detector 13 and the flow rate 16 of the feed water flowing through the gas high-pressure feed water heater 11 detected by the flow rate detector 15 is determined by the controller 20. The feedwater flow rate 23 obtained in the subtractor 22 and flowing through the high-pressure feedwater heater 3 is output to the subtractor 38, and based on the boiler load command 19, the function generator 24 sets the outlet feedwater temperature set value 25 of the gas high-pressure feedwater heater 11.
Is output to the subtractor 28, and the boiler load command 1
9, the function generator 26 calculates the feedwater flow rate setting value 27 of the high-pressure feedwater heater 3, and the subtractor 32 and the adder 3
6 and the function generator 24
The difference between the set value 25 of the outlet feed water temperature of the gas high pressure feed water heater 11 output from the sensor and the outlet feed water temperature 18 of the gas high pressure feed water heater 11 detected by the temperature detector 17 is obtained, and the outlet feed water temperature deviation 29 is output to a proportional-integral controller 34 with a low signal limiter.

Before the steam is extracted from the steam turbine 4 to the high-pressure feed water heater 3, the input of the switch 30 is switched to a side, and 0 [ton / h] is switched from the switch 30 to high-pressure feed water heating. Subtractor 3 as the minimum water supply flow rate setting value 31
2 and the set value 3 of the minimum feed water flow rate of the high pressure feed water heater 3 output from the switch 30 in the subtracter 32.
The difference between 1 and the set value 27 of the feed water flow rate of the high-pressure feed water heater 3 output from the function generator 26 is obtained, and the flow rate set value deviation 33 is output to the proportional-integral controller 34 with a low signal limiter. In the proportional-integral controller 34 with the low signal limiter, the outlet feedwater temperature deviation 29 of the gas high-pressure feedwater heater 11 output from the subtractor 28 is proportionally integrated to obtain a feedwater flow correction value of the high-pressure feedwater heater 3. When the feedwater flow rate correction value of the high-pressure feedwater heater 3 is larger than the flow rate set value deviation 33 output from the subtractor 32, the feedwater flow rate correction value of the high-pressure feedwater heater 3 is directly used as the correction command 35. On the other hand, when the correction value of the feed water flow rate of the high-pressure feed water heater 3 is equal to or smaller than the flow rate set value deviation 33 output from the subtractor 32, the flow rate set value deviation 33 is output to the adder 36. age Is output to the adder 36, the adder 3
In 6, a correction command 35 output from the proportional-integral controller 34 with the low-signal limiter is added to the water supply flow rate set value 27 of the high-pressure water heater 3 output from the function generator 26, and the high-pressure water heater 3 is output to the subtractor 38, where the feedwater flow rate 23 flowing from the high-pressure feedwater heater 3 output from the subtractor 22 and the high-pressure output from the adder 36 are output. The difference from the feed water flow rate correction set value 37 of the feed water heater 3 is obtained, and the feed water flow rate deviation 39 of the high pressure feed water heater 3 is calculated by the proportional integral controller 40.
And the feed-in flow rate deviation 3 of the high-pressure feed water heater 3 output from the subtractor 38 in the proportional-integral controller 40.
9 is proportionally integrated and the opening degree command 21 is sent to the flow regulating valve 12.
Is output, the opening degree of the flow control valve 12 is adjusted according to the opening degree command 21, the flow rate of the feed water distributed to the high pressure feed water heater 3 and the gas high pressure feed water heater 11 is adjusted, and the gas high pressure feed water heating is performed. Outlet water temperature of vessel 11 is outlet water temperature set value 25
It is controlled so that

Incidentally, the actual outlet feed water temperature 18 of the gas high-pressure feed water heater 11 becomes very high, and it becomes necessary to greatly increase the flow rate of feed water flowing to the gas high-pressure feed water heater 11, and the low signal Gas high-pressure feed water heater 11 output from subtractor 28 in proportional-integral controller with limiter 34
If the correction value of the feed water flow rate of the high-pressure feed water heater 3 obtained by performing the proportional integration process on the outlet feed water temperature deviation 29 becomes equal to or less than the flow set value deviation 33 output from the subtractor 32, the flow set value The deviation 33 is output as a correction command 35 to an adder 36, and the adder 36 adjusts the proportional-integral adjustment with the low-signal limiter for the feedwater flow rate set value 27 of the high-pressure feedwater heater 3 output from the function generator 26. Since the correction command 35 output from the heater 34 is added, 0
[Ton / h] is output to the subtracter 38 as the feedwater flow rate correction set value 37 of the high-pressure feedwater heater 3, the flow control valve 12 is fully closed, and the feedwater is completely supplied to the high-pressure feedwater heater 3. Although it does not circulate, the steam is not extracted from the steam turbine 4 to the high-pressure feed water heater 3 at this time, so there is no fear that the high-pressure feed water heater 3 is damaged by heat.

On the other hand, after steam extraction from the steam turbine 4 to the high-pressure feed water heater 3, the input of the switch 30 is switched to the b side, and α [ton / h] is changed from the switch 30 to α [ton / h]. Subtracter 32 as the minimum supply flow rate setting value 31
And the minimum feed water flow rate setting value 31 of the high-pressure feed water heater 3 output from the switch 30 in the subtractor 32.
And the feed water flow rate set value 27 of the high-pressure feed water heater 3 output from the function generator 26 is obtained, and a flow rate set value deviation 33 is output to a proportional-integral controller 34 with a low signal limiter. In the proportional-integral controller 34 with the low-signal limiter, the outlet feedwater temperature deviation 29 of the gas high-pressure feedwater heater 11 output from the subtractor 28 is proportionally integrated, and the feedwater flow rate correction value of the high-pressure feedwater heater 3 is obtained. , The high pressure feed water heater 3
Is larger than the flow rate set value deviation 33 output from the subtractor 32, the feed water flow correction value of the high-pressure feed water heater 3 is directly output to the adder 36 as the correction command 35. When the feedwater flow rate correction value of the high-pressure feedwater heater 3 is equal to or less than the flow rate set value deviation 33 output from the subtractor 32, the flow rate set value deviation 33 is output to the adder 36 as a correction command 35, The adder 36
The correction command 35 output from the proportional-integral controller 34 with the low-signal limiter is added to the feed water flow rate set value 27 of the high-pressure feed water heater 3 output from the function generator 26, and the high-pressure feed water heater 3 Is supplied to the subtractor 38, and the feedwater flow rate 23 flowing through the high-pressure feedwater heater 3 output from the subtractor 22 and the high-pressure feedwater output from the adder 36 are output from the subtractor 38. The difference from the feed water flow rate correction set value 37 of the heater 3 is obtained, and the feed water flow rate deviation 39 of the high-pressure feed water heater 3 is output to the proportional-integral controller 40.
Feed water flow rate deviation 39 of the high pressure feed water heater 3 output from 8
Is proportionally integrated, and an opening command 21 is output to the flow control valve 12. The opening of the flow control valve 12 is adjusted in accordance with the opening command 21, and the high-pressure water heater 3 and the gas high-pressure water heater 11 are adjusted. The flow rate of the feedwater distributed to the heater is adjusted, and the outlet feedwater temperature of the gas high-pressure feedwater heater 11 is controlled to be the outlet feedwater temperature set value 25.

The high pressure feed water heater 3 from the steam turbine 4
After the steam extraction to the gas high-pressure feedwater heater 11, the actual outlet feedwater temperature 18 of the gas high-pressure feedwater heater 11 becomes very high, and it becomes necessary to greatly increase the flow rate of the feedwater flowing to the gas high-pressure feedwater heater 11, Gas high-pressure feed water heater 1 output from subtractor 28 in proportional-integral controller 34 with signal limiter
1, the feed water flow rate correction value of the high pressure feed water heater 3 obtained by performing the proportional integration process on the outlet feed water temperature deviation 29 is
When the flow rate set value deviation 33 output from the controller becomes equal to or less than 33, the flow rate set value deviation 33 is output to the adder 36 as a correction command 35, and the high voltage output from the function generator 26 in the adder 36 is output. Since the correction command 35 output from the proportional-integral controller 34 with the low-signal limiter is added to the feed water flow rate set value 27 of the feed water heater 3, α
[Ton / h] is output to the subtractor 38 as the feedwater flow rate correction set value 37 of the high-pressure feedwater heater 3, the flow control valve 12 is not fully closed, and α [ ton / h] of water supply always flows, the minimum supply flow rate of the high-pressure water heater 3 is secured, and the high-pressure water heater 3 is protected from heat.

In this way, by adjusting the opening of the flow control valve 12 of the high-pressure feed water heater 3, the flow rate of the feed water distributed to the high-pressure feed water heater 3 and the gas high-pressure feed water heater 11 is adjusted. 11 can control the outlet feedwater temperature;
The minimum feedwater flow rate of the high-pressure feedwater heater 3 can be secured to protect the high-pressure feedwater heater 3 from heat.

It should be noted that the method and apparatus for controlling the outlet feedwater temperature of the high-pressure gas feedwater heater in the exhaust gas reburning combined cycle plant of the present invention are not limited to the above-described example, but are detected by the flow rate detector. Instead of obtaining the flow rate of the feedwater flowing through the high-pressure feedwater heater 3 from the difference between the discharge flow rate of the feedwater pump and the flowrate of the feedwater flowing through the gas high-pressure feedwater heater 11 detected by the flow rate detector, the flow rate through the high-pressure feedwater heater 3 is changed. Such that the feedwater flow rate may be directly detected,
In addition, it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0025]

As described above, according to the method and the apparatus for controlling the outlet feedwater temperature of the gas high-pressure feedwater heater in the exhaust reburning combined cycle plant according to the present invention, the opening of the flow control valve 12 of the high-pressure feedwater heater 3 is opened. By adjusting the temperature, the flow rate of the feed water distributed to the high-pressure feed water heater 3 and the gas high-pressure feed water heater 11 can be adjusted, the outlet feed temperature of the gas high-pressure feed water heater 11 can be controlled, and the high-pressure feed water heater 3 can be controlled. , The high-pressure feedwater heater 3 can be protected from heat.

[Brief description of the drawings]

FIG. 1 is an overall schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is a block diagram illustrating details of a controller according to an example of an embodiment of the present invention;

FIG. 3 is a diagram showing functions set in a function generator 24 shown in FIG. 2;

FIG. 4 is a diagram showing functions set in a function generator 26 shown in FIG. 2;

FIG. 5 is an overall schematic configuration diagram of an example of a conventional power plant using a general boiler.

FIG. 6 is an overall schematic configuration diagram of an example of an exhaust gas reburning combined cycle plant proposed in recent years.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler main body 3 High pressure feed water heater 9 Gas turbine 11 Gas high pressure feed water heater 12 Flow control valve 16 Feed water flow 18 Outlet feed water temperature 19 Boiler load command 20 Controller 21 Opening command 23 Feed water flow 24 Function generator 25 Outlet feed water temperature Set value 26 Function generator 27 Feed water flow set value 28 Subtractor 29 Outlet feed water temperature deviation 31 Minimum feed water flow set value 32 Subtractor 33 Flow rate set value deviation 34 Proportional integration controller with low signal limiter 35 Correction command 36 Adder 37 Water supply flow rate correction set value 38 Subtractor 39 Water supply flow rate deviation 40 Proportional integral controller

Claims (2)

[Claims] An exhaust gas from a gas turbine (9) is used as a fuel combustion gas in a boiler body (1), and a high-pressure feed water heater (3) and a gas high-pressure feed water heater (1) are used.
1) A method for controlling the outlet feedwater temperature of a high-pressure gas feedwater heater in an exhaust gas reburning combined cycle plant, wherein the feedwater to a boiler main body (1) is heated by (1). A high pressure feed water heater (3) is obtained from an outlet feed water temperature deviation (29) between the outlet feed water temperature set value (25) of the feed water heater (11) and the actual outlet feed temperature (18) of the gas high pressure feed water heater (11). Of the high-pressure feed water heater (3), and the feed-water flow correction value of the high-pressure feed water heater (3) based on the boiler load command (19), The feedwater flow rate correction set value (37) of the high-pressure feedwater heater (3) is obtained by adding the minimum feedwater flow rate of the high-pressure feedwater heater (3), and the feedwater flow rate of the high-pressure feedwater heater (3) is determined. Correction setting value (37 ) And the actual feedwater flow rate (23), the opening of the flow control valve (12) of the high-pressure feedwater heater (3) is adjusted in accordance with the feedwater flow deviation (39) of the high-pressure feedwater heater (3). An outlet feedwater temperature control method for a gas high pressure feedwater heater in an exhaust gas reburning combined cycle plant, comprising controlling an outlet feedwater temperature (18). 2. The exhaust gas of a gas turbine (9) is used as fuel combustion gas in a boiler body (1), and a high-pressure feed water heater (3) and a gas high-pressure feed water heater (1) are used.
1) An outlet feedwater temperature control device of a gas high-pressure feedwater heater in an exhaust gas reburning combined cycle plant configured to heat the feedwater to a boiler body (1) by (1), wherein the gas pressure is increased based on a boiler load command (19). A function generator (24) for outputting a set value (25) of outlet feed water temperature of the feed water heater (11), and a high pressure feed water heater (3) based on a boiler load command (19)
Function generator (2) that outputs the set water supply flow rate (27)
6), an outlet feedwater temperature set value (25) of the gas high-pressure feedwater heater (11) output from the function generator (24), and an outlet feedwater temperature (18) of the gas high-pressure feedwater heater (11). Subtractor (2) that calculates the difference between
8), and the minimum feed water flow rate setting value of the high pressure feed water heater (3) (31)
And a subtracter (32) for calculating a difference between a feed water flow set value (27) of the high-pressure feed water heater (3) output from the function generator (26) and outputting a flow set value deviation (33). A proportional integration process is performed on the outlet feedwater temperature deviation (29) of the gas high-pressure feedwater heater (11) output from the subtracter (28) to obtain a feedwater flow rate correction value of the high-pressure feedwater heater (3). The correction value of the feed water flow rate of the feed water heater (3) is calculated by the subtracter (3).
When the flow rate set value deviation (33) output from 2) is larger than the high-pressure feed water heater (3), the correction value (35) is output as it is as the correction command (35), while the high-pressure feed water heater (3) is output. If the water supply flow rate correction value of 3) is equal to or smaller than the flow rate set value deviation (33) output from the subtracter (32), the flow rate set value deviation (33) is corrected by the correction command (3).
5) Proportional integral controller with low signal limiter (3)
4) and a correction output from the proportional-integral controller with low-signal limiter (34) to the feedwater flow rate set value (27) of the high-pressure feedwater heater (3) output from the function generator (26). An adder (36) for adding a command (35) and outputting a set value (37) of a feedwater flow correction of the high-pressure feedwater heater (3); and a feedwater flow (23) flowing through the high-pressure feedwater heater (3).
Of the high-pressure feed water heater (3) output from the adder (36) and the correction value (37) of the high-pressure feed water heater (3), and outputs the feed water flow deviation (39) of the high-pressure feed water heater (3). And a high-pressure feedwater heater (3) output from the subtractor (38).
The feed water flow deviation (39) is proportionally integrated and the opening degree command (2) is sent to the flow control valve (12) of the high pressure feed water heater (3).
An outlet feedwater temperature control device for a gas high-pressure feedwater heater in an exhaust gas reburning combined cycle plant, comprising a proportional-integral controller (40) that outputs 1).