JPH0743089B2 - Degasser internal pressure control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) [0001] The present invention relates to an internal pressure control system for a deaerator incorporated in a rechargeable water system of a thermal power plant or a nuclear power plant.

(Prior Art) FIG. 4 is a schematic system diagram of a power plant.

First, the normal operation of the steam turbine cycle will be described.

Condensate collected in the hot well of the condenser 1 is boosted by the condensate pump 2, passes through the deaerator water level control valve 3, and is heat-exchanged by the low-pressure heater 4 heated by turbine steam. 5
Sent to. The deaerator 5 guides the turbine extracted air from the turbine extraction pipe 19 and directly heats the condensed water introduced from the low-pressure heater 4 by the turbine extracted air to deaerate it. Further, the deaerator water level control valve 3 acts so as to keep the water level of the deaerator 5 constant.

The condensed water deaerated by the deaerator 5 is further pressurized by the water supply pump 6 to be supplied. The supplied water is heat-exchanged by the high-pressure heater 7 heated by turbine extraction air, guided to the boiler 8 and further heated to be steam. This steam is guided to the high-pressure turbine 11 through the main steam stop valve 9 and the main steam control valve 10. In the high-pressure turbine 11, the thermal energy of steam is converted into kinetic energy, and a generator (not shown) is rotated to generate electricity.

The steam discharged from the high-pressure turbine 11 is guided to the reheater 13 to be reheated, passes through the intermediate steam valve 14, and is introduced into the intermediate-pressure turbine 15 to perform work. The steam discharged from the medium-pressure turbine 15 is guided to the low-pressure turbine 16 to do more work. The exhaust steam from the low-pressure turbine 16 is cooled by the condenser 1 to be condensed water.

Next, a case will be described in which a problem occurs in the steam turbines 11, 15, 16 and the turbines 11, 15, 16 are tripped.

In this case, the main steam stop valve 9 is fully closed, the high pressure turbine bypass valve 12 is opened instead, the high pressure turbine 11 is bypassed, and the steam from the boiler 8 is directly led to the reheater 13. Further, the intermediate steam valve 14 is fully closed, and the low pressure turbine bypass valve 17
Is opened to guide the steam from the reheater 13 directly into the condenser 1. In this way, the steam turbines 11, 15 and 16 are stopped, and at the same time, the boiler 8 is stopped to eliminate the malfunction of the steam turbine.

Next, when the malfunction of the steam turbines 11, 15 and 16 is removed and these steam turbines are started, the boiler 8 is first started. At this time, since turbine bleed air is not supplied from the turbine bleeder tube 19 into the deaerator 5, the deaerator pressure control valve 18 is opened to guide steam from another steam generation source into the deaerator 5, and The steam from the condenser 1 is degassed by steam. Then, the deaerator pressure control valve 18 is closed when the turbine extraction from the steam turbines 11, 15 and 16 is sufficient. After that, the condensate in the deaerator 5 is deaerated by turbine extraction from the turbine extraction pipe 19.

(Problems to be Solved by the Invention) However, every time a failure occurs in the steam turbines 11, 15, 16 as described above, not only these steam turbines 11, 15, 16 but also the boiler 8 are stopped. In operation, a large amount of heat loss occurs when the boiler 8 is restarted, and there are many problems in terms of the thermal economy of the plant.

This invention was made in consideration of the above circumstances,
An object of the present invention is to provide an internal pressure control system for a deaerator, which enables independent operation of a boiler while maintaining a temperature of water supplied to the boiler at a predetermined value or more during a turbine trip.

[Structure of Invention]

(Means for Solving the Problem) The present invention makes it possible to introduce steam from another steam generation source into a deaerator that heats and degasses condensed water from a condenser by turbine bleeding. A deaerator pressure control valve, a pressure detector for detecting the pressure in the deaerator, and a temperature detector for detecting the temperature of the feed water supplied to the boiler arranged on the downstream side of the deaerator. A deaerator pressure control device that determines the opening degree of the deaerator pressure control valve based on detection signals from the pressure detector and the temperature detector during turbine trip, and the deaerator pressure control The device includes a temperature controller that sets the valve opening degree of the deaerator pressure control valve based on the detection signal from the temperature detector, and the deaerator pressure based on the detection signal from the pressure detector. The pressure controller that sets the valve opening of the control valve and these temperature controllers and And a high value selector that selects a signal having a large valve opening value among the valve opening signals from the pressure controller.

(Operation) During turbine stripping, the main steam stop valve is closed to reduce the supply of turbine bleed air into the deaerator and the internal pressure of the deaerator drops, so the pressure of the deaerator pressure control device is reduced. The controller sets the valve opening degree of the deaerator pressure control valve based on the detection signal from the pressure detector. At the same time, the turbine extraction air to the deaerator is reduced, so the temperature of the feed water supplied to the boiler is also reduced. Therefore, the temperature controller of the deaerator pressure control device sets the valve opening degree of the deaerator pressure control valve based on the detection signal from the temperature detector.

The deaerator pressure control valve is controlled by a valve opening signal from the pressure controller or the temperature controller having a larger value. As a result, when the turbine trips, a large amount of steam from other steam generation sources flows into the deaerator via the deaerator pressure control valve, and the deaerator internal pressure is controlled to an appropriate value. .
Therefore, the temperature of water supplied to the boiler can be maintained at a predetermined value or higher, and the boiler can be operated independently.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a partial system diagram of a turbine power plant to which an embodiment of a deaerator internal pressure control system according to the present invention is applied, and FIG. 1 is a deaerator pressure control device of FIG. 3 is a block diagram showing the configuration of FIG. In this embodiment, the same parts as those in the conventional example are designated by the same reference numerals.

As shown in FIG. 2, the deaerator 5 heats the condensate from the condenser 1 by turbine extraction to deaerate it. This deaerator 5
Is connected to a steam pipe 20 in which a deaerator pressure control valve 18 is arranged. By opening the deaerator pressure control valve 18, steam can be introduced into the deaerator 5 from another steam generation source. It is provided in. A turbine extraction pipe 19 is connected to the steam pipe 20, and an extraction check valve 21 is installed in the turbine extraction pipe 19. Turbine extraction pipe 19
The turbine bleed air from the steam turbines 11, 15 and 16 is provided so as to be able to be supplied into the deaerator 5 via.

Now, the deaerator pressure control device 22 is connected to the deaerator pressure control valve 18. This deaerator pressure control device 22 has a pressure detector
23 and the temperature detector 24 are connected. This pressure detector 23
Is attached to the deaerator 5 and detects the pressure in the deaerator 5. The temperature detector 24 is installed upstream of the boiler 8 and detects the temperature of the feed water supplied to the boiler 8.

The deaerator pressure control device 22 has a temperature controller 25 and a pressure controller 26, as shown in FIG.
7. A pressure setting switch 28 and a high price selector 29 are provided.

The temperature detection signal A from the temperature detector 24 is supplied to the temperature controller 25.
And the temperature set value signal B is input. Temperature controller 25
Calculates the valve opening of the deaerator pressure control valve 18 from the deviation between these signals A and B, and outputs the temperature side valve opening signal C to the temperature switch 27. The temperature switching device 27 outputs the temperature side valve opening signal C from the temperature controller 25 to the high value selector 29 only when the boiler 8 is operated alone during a turbine trip.

In the pressure setting switch 28, the pressure set value 30 in the deaerator 5 at the time of normal operation of the turbine is used as the pressure setting signal D at the time of normal operation, and the inside of the deaerator 5 when the turbine trips and the boiler 8 is operated independently. The pressure set value 31 of 1 is input as the pressure setting signal E for the boiler independent operation. The pressure setting switch 28 switches the normal operation pressure setting signal D during the turbine normal operation, and switches the boiler independent operation pressure setting signal E to the pressure controller 26 when the turbine trips and operates the boiler 8 alone.

Here, as shown in FIG. 3, the pressure set value 30 during turbine normal operation is set to about 0.35 atg, and the pressure set value 31 during boiler independent operation is set to about 8 atg. In addition,
The solid line in FIG. 3 is a graph showing the relationship between the pressure inside the deaerator 5 and the turbine load, which changes due to turbine extraction during normal turbine operation.

The pressure controller 26 shown in FIG. 1 compares the pressure detection signal F from the pressure detector 23 with the pressure setting signal D during the normal operation or the pressure setting signal E during the boiler independent operation to obtain the deviation. The valve opening of the deaerator pressure control valve 18 is set based on the deviation, and is output to the high value selector 29 as a pressure side valve opening signal G.

The high value selector 29 is a pressure controller 26 during normal turbine operation.
The valve opening of the deaerator pressure control valve 18 is determined and controlled based only on the pressure side valve opening signal G from Further, during the boiler independent operation, the high value selector 29 selects one of the pressure side valve opening signal G and the temperature side valve opening signal C having a larger valve opening value, and selects this signal as the selection signal H. Based on this, the valve opening degree of the deaerator pressure control valve 18 is controlled.

Next, the operation will be described.

During normal turbine operation, the pressure setting switch 28 outputs a normal operation pressure set value signal D to the pressure controller 26. Also,
Since no signal is output from the temperature switching device 27 to the high value selector 29, the high value selector 29 uses the pressure side valve opening signal G from the pressure controller 26 as the selection signal H to select the valve of the deaerator pressure control valve 18. Control the opening. When the turbine extraction amount from the turbine extraction pipe 19 increases, the pressure controller 26 outputs a signal to close the deaerator pressure control valve 18. Therefore, thereafter, the inside of the deaerator 5 is controlled only by the turbine extraction air from the turbine extraction air 19.

Next, a case where a problem occurs in the steam turbine and it is desired to trip only the steam turbine to operate the boiler 8 independently will be described.

In this case, the pressure setting switching device of the deaerator pressure control device 22
Boiler independent operation signal I is output to 28 and temperature switch 27. In response to the boiler independent operation signal I, the pressure setting switch 28 sends the boiler independent operation pressure setting signal E to the pressure controller 26.
In addition, the temperature switching device 27 outputs the signal from the temperature controller 25 to the high price selector 29. Pressure controller 26
Compares the pressure detection signal F from the pressure detector 23 with the pressure setting signal E during boiler independent operation, sets the valve opening degree of the deaerator pressure control valve 18 based on the deviation, and opens the pressure side valve. The frequency signal G is output to the high price selector 29.

Further, the temperature controller 25 uses the temperature set value signal B and the temperature detector 24.
The temperature side valve opening signal C based on the deviation is output to the temperature switching unit 27. The temperature switch 27 outputs the temperature side valve opening signal C to the high value selector 29.

The high value selector 29 selects one of the pressure side valve opening signal G and the temperature side valve opening signal C having a larger valve opening value as the selection signal H, and the selection signal H causes the deaerator to select. The valve opening of the pressure control valve 18 is controlled.

As a result, at the time of turbine top, a large amount of steam is supplied from the other steam generation source to the deaerator 5 through the steam pipe 20 even when the turbine bleed air is not supplied from the turbine bleeder pipe 19 to the deaerator 5. Therefore, the inside of the deaerator 5 is controlled to an appropriate pressure which is approximately the same as the pressure set value 31 during the boiler independent operation. As a result, the temperature of water supplied to the boiler 8 can be controlled to a predetermined value of about 180 ° C. or higher, and the boiler can be operated independently.

In the above-described boiler independent operation, generally, the pressure inside the deaerator 5 is controlled to be constant by the pressure side valve opening signal G, but the inlet feed water temperature of the boiler 8 is transiently lowered. In this case, since the value of the temperature side valve opening signal C becomes larger than the pressure side valve opening signal G, the valve opening of the deaerator pressure control valve 18 is controlled based on this temperature side valve opening signal C. Will be done.

〔The invention's effect〕

As described above, according to the in-vessel pressure control system for a deaerator according to the present invention, the deaerator pressure control device, based on the detection signal from the temperature detector, the opening degree of the deaerator pressure control valve. From the temperature controller that sets the pressure controller that sets the valve opening degree of the deaerator pressure control valve based on the valve opening signal from the pressure detector, and from these temperature controller and pressure controller Since it has a high value selector that selects a large valve opening value among the valve opening signals of the above, a large amount of steam is released from other steam generation sources through the deaerator pressure control valve during turbine trip. The pressure inside the deaerator is controlled to an appropriate value by flowing into the air. Therefore, the temperature of the water supplied to the boiler can be maintained at a predetermined position or higher, and the boiler can be operated independently.

[Brief description of drawings]

FIG. 1 is a block diagram showing the deaerator pressure control device of FIG. 2, and FIG. 2 shows a part of a turbine plant to which an embodiment of the deaerator internal pressure control system according to the present invention is applied. The system diagram shown in FIG. 3 is a diagram showing the pressure set value during normal operation and the pressure set value during boiler independent operation, respectively, and FIG. 4 is a schematic system diagram showing a power plant to which the present invention is applied. 22 …… Deaerator pressure control device, 23 …… Pressure detector, 25 ……
Temperature controller, 26 …… Pressure controller, 29 …… High value selector, C
…… Temperature side valve opening signal, G …… Pressure side valve opening signal.

Claims (1)

[Claims] 1. A deaerator for heating condensate from a condenser by turbine bleeding to deaerate it, and a deaerator pressure control valve for introducing steam from another vapor generation source to the deaerator. , A pressure detector for detecting the pressure in the deaerator, a temperature detector for detecting the temperature of the feed water supplied to the boiler arranged on the downstream side of the deaerator, and the pressure detector at the time of turbine trip And a deaerator pressure control device that determines the valve opening of the deaerator pressure control valve based on a detection signal from the temperature detector, and the deaerator pressure control device includes the temperature detector A temperature controller that sets the valve opening of the deaerator pressure control valve based on the detection signal from, and the valve opening of the deaerator pressure control valve based on the detection signal from the pressure detector Pressure controller and valve opening signals from these temperature controller and pressure controller Deaerator vessel internal pressure control system in which the values of the out valve opening, characterized in that it is configured to have a high value selector for selecting the larger signal.