JP3056880B2 - Feedwater heater controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a feed water heater control device of a repowering power plant or the like for introducing exhaust gas from a gas turbine into a boiler and reburning the gas turbine, and more particularly to a gas cooler juxtaposed with a feed water heater. The present invention relates to a feed water heater control device that controls a distribution ratio of flowing feed water flow.

[0002]

2. Description of the Related Art For example, the prior art will be described with reference to FIG. 7. Although not shown in the drawing, steam rotating a steam turbine is cooled and condensed by a condenser to be condensed. Then, after the condensate water is boosted by the condensate pump, the condensate water is boosted by the condensate booster pumps 1a and 1b provided in parallel, and the low-pressure first feedwater heater 3 and the low-pressure first feedwater heater 3 pass through the low-pressure feedwater heater inlet valve 2a. 2 Enter the feed water heater 4. Each of the low-pressure feedwater heaters 3 and 4 is heated by the extraction of the steam turbine.

On the other hand, the condensed water pressurized by the condensing booster pumps 1a and 1b enters the low-pressure gas cooler 6 via a low-pressure gas cooler inlet valve 2b provided in parallel with the low-pressure feed water heater inlet valve 2a. Thereafter, the condensed water is heated and exchanged by the low-pressure gas cooler 6 with boiler outlet gas of a boiler system not shown. Thus, the condensate heated by the low-pressure feed water heaters 3 and 4 and the low-pressure gas cooler 6 enters the deaerator 7 and is deaerated.

[0004] Further, the deaerated water supply is pressurized by two water supply pumps 8a and 8b. Here, the pressurized feedwater enters the high-pressure first feedwater heater 10, the high-pressure second feedwater heater 11, and the high-pressure third feedwater heater 12 sequentially through the high-pressure feedwater heater inlet valve 9a. The water supply enters the high-pressure gas cooler 14 via the high-pressure gas cooler inlet valve 9b. Here, in the high-pressure feedwater heater groups 10, 11, and 12, the steam is extracted by the steam turbine, and the high-pressure gas cooler 14 is heated by the exhaust gas of the boiler, and is fed to the boiler under pressure. In addition, 5 shows a low pressure feed water heater bypass valve, and 13 shows a high pressure feed water heater bypass valve.

[0005] Next, an outline of a method of operating a high-pressure / low-pressure gas cooler and a feed water heater of a power plant such as repowering provided with the above-mentioned condensing / water supply system will be described. Since the basic operation method is the same for both the high-pressure system and the low-pressure system, only the high-pressure system will be described here to simplify the description.

First, at the time of startup, the feedwater pumps 8a and 8b are started, and both the high-pressure feedwater heater inlet valve 9a and the high-pressure gas cooler inlet valve 9b are fully opened to supply water. Thereafter, the gas turbine is ignited and started. In addition, start the boiler and establish steam.

[0007] When the power plant is started, the temperature of the boiler precedes. Therefore, the temperature of the feedwater is increased on the high-pressure gas cooler 14 side.
In the steam turbine system, since the bleeding operation has not been started, the temperature is not raised in the high-pressure feedwater heater groups 10, 11, and 12. Then, after the load is gradually increased and the bleeding is started, the temperature of the high-pressure feedwater heater groups 10, 11, and 12 also starts increasing.

[0008]

However, in the above-mentioned prior art, there is a problem that the temperature of the water supply becomes low at the time of starting and heat loss occurs.

That is, the high-pressure / low-pressure feed water heater inlet valve and the high-pressure / low-pressure gas cooler inlet valve are fully opened at the same time at startup, and high-temperature gas is supplied to the high-pressure / low-pressure gas cooler for a short time after bleeding is started. The feedwater is heated, but the feedwater is not heated because no bleed air is extracted into the high / low pressure feedwater heater group. Therefore, when the feedwater heated by the high-pressure / low-pressure gas cooler also joins at the outlet of the high-pressure / low-pressure feedwater heater group, the temperature of the feedwater becomes low, causing a problem that heat loss occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a feed water heater control device that cools feed water heated by a high-pressure / low-pressure gas cooler so that heat loss does not occur even at startup.

[0011]

A first aspect of the present invention is a water supply system comprising a feed water heater system in which feed water is heated by extraction of a steam turbine, and a gas cooler system in which feed water is heated by exhaust gas from a gas turbine in a gas cooler. And controls a feedwater heater provided at a repowering power plant or the like that branches into the feedwater heater system and the gas cooler system on the inlet side of the feedwater system, and merges on the outlet side of the feedwater system. In the feedwater heater control device, a feedwater heater control valve that controls a supply flow rate of the feedwater heater system is disposed in the feedwater heater system, and the amount of heat extracted from the steam turbine supplied to the feedwater heater and supplied to the gas cooler. A control means is provided for controlling the opening and closing of the feed water heater control valve in accordance with the calorific value of the exhaust gas calorific value of the gas turbine.

The invention of claim 3 has a feedwater heater system in which feedwater is heated by bleeding of the steam turbine, and a feedwater system consisting of a gas cooler system in which feedwater is heated by exhaust gas of the gas turbine by a gas cooler. A feedwater heater control device that controls a feedwater heater provided at a repowering power plant or the like that branches into the feedwater heater system and the gas cooler system at the inlet side of the feedwater system, and merges at the outlet side of the feedwater system. A feed water heater control valve for controlling the supply flow rate of this system is provided in the feed water heater system, and a gas cooler control valve for controlling the supply flow rate of this system is provided in the gas cooler system to supply the feed water heater. The feed water heater according to a calorific ratio of the extracted calorific value of the steam turbine and the calorific value of the exhaust gas of the gas turbine supplied to the gas cooler. And it said the Fushiben gas cooler regulating valve is obtained by the provided control means for opening and closing control.

[0013]

With the above arrangement, the amount of water flowing into the feed water heater and the gas cooler is controlled based on the ratio of the amount of heat of the bleed air supplied to the feed water heater to the amount of heat of the gas supplied to the gas cooler. As a result, before the start of the bleeding, the feedwater flows only into the gas cooler, and does not flow into the feedwater heater. For this reason, low-temperature feedwater does not flow in from the feedwater heating system at the outlet of the feedwater system, thereby reducing heat loss. And
After the start of the bleeding, the feedwater gradually flows into the feedwater heating system. Therefore, at the outlet of the feedwater system, the feedwater temperature of the feedwater heating system is mixed while approaching the feedwater temperature of the gas cooler outlet,
Heat loss can be kept extremely small.

[0014]

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

FIG. 1 is a system diagram of a feed water heater control device showing one embodiment of the present invention, and FIG. 2 is an example of a control block diagram of FIG. The same reference numerals as those in FIG. 7 indicate the same or corresponding parts. FIG. 1 differs from FIG. 7 in that a low-pressure feed water heater inlet flow rate control valve 15a is provided on the outlet side of the low-pressure gas cooler inlet valve 2a and on the inlet side of the low-pressure first feed water heater 3.
The high pressure feed water heater inlet flow rate control valve 16a is provided on the pipe between the outlet side of the high pressure feed water heater inlet valve 9a and the inlet side of the high pressure first feed water heater 10.

Also, a low pressure feed water heater inlet flow control valve 15
The control block of the feed water heater control device that controls the flow rate control valve 16a and the high-pressure feed water heater inlet flow rate control valve 16a includes a bleed calorie calculator 17, a gas calorie calculator 18, a calorie ratio calculator 19, and a flow rate as shown in FIG. It comprises a setting device 20 and a controller 21.

The high-pressure feed water heater inlet flow control valve 16
The control block for controlling the flow rate control valve a and the control block for controlling the low-pressure feed water heater inlet flow rate control valve 15a have the same basic logic. Therefore, here, the control block for the high-pressure feed water heater inlet flow rate control valve 16a will be described.

Here, the extracted heat calorie calculator 17 inputs the steam turbine load signal a, calculates the total heat input of the extracted steam, and outputs a total extracted steam heat input signal. Gas calorie calculator 1
8 inputs the gas turbine load signal b, calculates the total heat input to the high-pressure gas cooler 14, and outputs a high-pressure gas cooler total heat input signal. The calorific-ratio calculator 19 calculates the ratio between the extracted steam total heat input signal and the high-pressure gas cooler total heat input signal, and outputs a calorific ratio calculation signal. The flow rate setter 20 calculates the feed water flow rate of the high pressure feed water heater group based on the calorific value ratio calculation signal and the feed water flow rate signal c, and outputs a flow rate setting signal. The controller 21 controls the flow rate setting signal and the opening
An opening signal is output to the high-pressure feedwater heater inlet flow rate control valve 16a in response to the opening feedback signal from the second unit.

Next, the operation of the high-pressure system of this embodiment will be described. The operation is almost the same for the low pressure system.

First, when starting up the power plant, the water supply pump 8a,
With the start of 8b, both the high pressure feed water heater inlet valve 9a and the high pressure gas cooler inlet valve 9b are fully opened. After ignition of the gas turbine, the boiler is started. At this point, the gas turbine is unloaded and the steam turbine is unloaded. At this time, the steam turbine load signal a is input to the extracted heat amount calculator 17, and the value of the extracted steam total heat input amount signal is output to the heat amount ratio calculator 19 as zero.

On the other hand, the gas turbine load signal b is input to the gas calorie calculator 18, and the high-pressure gas cooler total heat input signal is output to the calorie ratio calculator 19. The calorie ratio calculator 19 calculates the ratio between the zero of the extracted steam total heat input signal and the high pressure gas cooler total heat input signal, and outputs the calorific value ratio calculation signal as zero. When the calorie ratio calculation signal of zero is input to the calorie ratio calculator 19, the calorie ratio calculator 19 outputs the flow rate setting signal to the controller 21 as zero. As a result, the opening signal to the high-pressure feedwater heater inlet flow control valve 16a becomes zero, and the high-pressure feedwater heater inlet flow control valve 16a is fully closed.

Accordingly, when no load is applied to the steam turbine, all feedwater flows on the high-pressure gas cooler 14 side. Thereafter, the steam turbine also takes a load, and when the bleed operation is performed, the total heat input of the bleed steam is calculated by the bleed heat calculator 17 based on the steam turbine load signal a. The extracted steam total heat input signal and the high-pressure gas cooler total heat input signal calculated based on the gas turbine load signal b are input to a heat amount ratio calculator 19, where the ratio between the two is calculated, and a heat amount ratio calculation signal is output. Then, the calorific value calculation signal is input to the flow rate setting device 20, and the flow rate setting signal is output according to the gas turbine load signal b.

The controller 21 controls the opening of the high-pressure feed water heater inlet flow control valve 16a based on the flow setting signal and the opening signal of the opening meter 22. Thereby, the high-pressure feed water heater inlet flow rate control valve 16 is adjusted so that a flow rate corresponding to the ratio of the total heat input of the extracted steam to the total heat input of the high-pressure gas cooler is obtained.
a is controlled. That is, for example, the opening degree of the high-pressure feed water heater inlet flow control valve 16a is controlled such that the amount of extracted heat becomes 1: 2 between the high-pressure feed water heater side and the high-pressure gas cooler 14 side.

As described above, by controlling the flow rate of the water flowing into the feed water heater group and the gas cooler based on the ratio of the amount of heat extracted and the heat of the gas, the feed water heated at the outlet of the feed water heater group and the outlet of the gas cooler is joined. Even so, heat loss can be extremely reduced.

FIG. 3 shows another embodiment of the present invention.

In the embodiment shown in FIG. 2, the gas turbine load signal b is used. In the embodiment shown in FIG. 3, however, a gas temperature signal d at the inlet of the high-pressure gas cooler is inputted, and the gas calorie calculator 23 outputs the high-pressure gas cooler. The total amount of heat of the gas to 14 is calculated, and the total heat input of the high-pressure gas cooler is output. Other configurations and operations are the same as those of the embodiment of FIG.

FIG. 4 shows another embodiment of the present invention.

Although the opening meter 22 is used in the embodiment shown in FIG. 2, the controller 21 does not use the opening meter 22 but uses the flow rate setting signal from the flow rate setting device 20 to control the flow rate at the inlet of the high pressure feed water heater. The opening of the control valve 16a may be controlled. Thus, the high-pressure feedwater heater inlet flow valve 16 is controlled so that a flow rate corresponding to the ratio of the total heat input of the extracted steam to the total heat input of the high-pressure gas cooler is obtained. Other configurations and operations are the same as those of the embodiment of FIG.

Next, another embodiment of the present invention will be described with reference to FIGS.

FIG. 5 differs from FIG. 1 in that a low-pressure gas cooler inlet flow control valve 15b is provided at the inlet of the low-pressure gas cooler 6.
And a high-pressure gas cooler inlet flow control valve 16b provided at the inlet of the high-pressure gas cooler 14.

Feed water heater control device of this embodiment (for high pressure)
Receives a steam turbine load signal a, calculates the total heat input of the extracted steam based on the input signal, and a gas turbine load signal b receives the total heat input to the high-pressure gas cooler 14. A gas calorie calculator 18 for calculating
A calorie ratio calculator 19 for calculating the ratio between the extracted heat quantity and the gas heat quantity based on the calculation results of these two calculators 17 and 18, a high-pressure feed water heater group and a high-pressure gas cooler 14 obtained from the calculation results of the heat quantity ratio calculator 19 Controller 21 that obtains the respective feed water flow ratios and uses the opening signals of the respective inlet flow control valves 16a and 16b as opening feedback signals to control the opening of the two inlet flow control valves 16a and 16b.
And the controller 24. Even in this case, the operation and effect are the same as those in the embodiment of FIGS. In addition, 25 is an opening meter.

[0032]

As described above, according to the present invention, the ratio between the amount of water supplied to the feed water heater and the amount of water supplied to the gas cooler is determined by the calorific ratio of the amount of extracted air supplied to the feed water heater and the amount of gas heat supplied to the gas cooler. Is calculated and controlled, heat loss can be suppressed to be extremely small because the feed water temperature is brought close to and mixed at the junction of the feed water heater outlet and the gas cooler outlet.

[Brief description of the drawings]

FIG. 1 is a system diagram of a feed water heater control device showing one embodiment of the present invention.

FIG. 2 is a control block diagram of FIG.

FIG. 3 is a control block diagram showing another embodiment of FIG. 2;

FIG. 4 is a control block diagram showing another embodiment of FIG. 2 or FIG. 3;

FIG. 5 is a system diagram of a feed water heater control device showing another embodiment of the present invention.

FIG. 6 is a control block diagram of FIG. 5;

FIG. 7 is a system diagram of a feed water heater control device corresponding to FIG. 1 or 5 showing a conventional example.

[Explanation of symbols]

 3 Low-pressure first feedwater heater 4 Low-pressure second feedwater heater 6 Low-pressure gas cooler 10 High-pressure first feedwater heater 11 High-pressure second feedwater heater 12 High-pressure third feedwater heater 14 High-pressure gas cooler 15a Low-pressure feedwater heater inlet flow control valve 15b Low-pressure gas cooler inlet flow control valve 16a High-pressure feed water heater inlet flow control valve 16b High-pressure gas cooler inlet flow control valve 17 Bleed calorie calculator 18 Gas calorie calculator 19 Calorimetric ratio calculator 20 Flow rate setter 21 Controller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F01K 7/38 102 F01K 7/14 F01K 23/10 F01K 7/40-7/42 F22D 11/00

Claims (4)

(57) [Claims] 1. A water supply system comprising a feedwater heater system in which feedwater is heated by extraction of a steam turbine and a gas cooler system in which feedwater is heated by exhaust gas from a gas turbine in a gas cooler, and an inlet side of the water supply system. A feed water heater control device that controls a feed water heater provided at a repowering power plant or the like that branches into the feed water heater system and the gas cooler system and that joins at the outlet side of the feed water system; A feed water heater control valve for controlling the supply flow rate of this system is arranged in the system, and the calorific value of the calorific value of the steam turbine supplied to the feed water heater and the calorific value of the exhaust gas of the gas turbine supplied to the gas cooler. A feed water heater control device, further comprising control means for opening and closing the feed water heater control valve in accordance with the ratio. Means for calculating the amount of heat extracted from the steam turbine based on a steam turbine load signal; means for calculating the amount of exhaust gas heat of the gas turbine based on a gas turbine load signal or the inlet temperature of the gas cooler; Means for calculating a calorific ratio between the extracted calorific value of the steam turbine and the calorific value of the exhaust gas of the gas turbine; and the feedwater heater control valve based on the calorific ratio calculated by the means and the flow rate of the feedwater system. 2. The feed water heater control device according to claim 1, wherein the control unit controls the feed water heater. 3. A water supply system comprising a feed water heater system in which feed water is heated by extraction of a steam turbine and a gas cooler system in which feed water is heated by exhaust gas from a gas turbine in a gas cooler, and an inlet side of the water supply system. A feed water heater control device that controls a feed water heater provided at a repowering power plant or the like that branches into the feed water heater system and the gas cooler system and that joins at the outlet side of the feed water system; A feed water heater control valve for controlling a supply flow rate of this system is disposed in a system, and a gas cooler control valve for controlling a supply flow amount of this system is disposed in the gas cooler system, and the steam turbine supplied to the feed water heater is provided. The feed water heater control valve and the gas according to a calorific ratio between the calorific value of the extracted air and the calorific value of the exhaust gas of the gas turbine supplied to the gas cooler. Feedwater heater control apparatus characterized in that a control means for opening and closing control and over La regulating valve. 4. A means for calculating the calorific value of the steam turbine based on a steam turbine load signal, a means for calculating the calorific value of the exhaust gas of the gas turbine based on a gas turbine load signal or an inlet temperature of the gas cooler, and a means for calculating by these means. Means for calculating a calorific ratio between the extracted calorific value of the steam turbine and the calorific value of the exhaust gas of the gas turbine; and the feedwater heater control valve based on the calorific ratio calculated by the means and the flow rate of the feedwater system. 4. The feed water heater control device according to claim 3, wherein the control unit controls the gas cooler control valve.