JPH0820045B2 - Feed water heater Drain collection control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a steam turbine plant, and in particular, in a plant adopting a regeneration cycle system, failure of equipment in which feed water heater drain constitutes a system. The present invention relates to a feedwater heater drain recovery control device that allows the drainage of the feedwater heater to escape to a device outside the system when the increase exceeds the design value, thereby avoiding a situation such as an operation stop.

(Prior art) In a steam turbine plant that adopts a regeneration cycle method, a feed water heater is used to heat boiler feed water or reactor feed water, and the steam turbine bleed air is guided to the feed water heater to exchange heat there. Be used for. During this heat exchange, the vapor condenses to produce drainage, but this drainage (hereinafter,
The feed water heater drain) maintains a high temperature even after heat exchange, and is sequentially supplied to the low-pressure side feed water heater through the feed water heater drain system in order to perform heat exchange with the feed water again. The feed water from the high-pressure side to the low-pressure side of the feed water heater drain is in a predetermined order, and is called a cascade method. Fig. 3 shows an example of a cascade system in a nuclear turbine plant. The feedwater heater drain is a high-pressure feedwater heater 2a, 2b near the reactor 1 side, and a next-stage feedwater heater 3a, 3b and low pressure. It is generated in the feed water heaters 4a and 4b of each stage, is sequentially supplied to the low pressure side through the drain pipes 6a, 6b, 7a and 7b each equipped with the control valve 5, and is finally collected in the condenser 9 through the drain pipes 8a and 8b. To be done. In addition, we will recover heat other than the feed water heater drain, and use a moisture separator.
The drain of 10 is collected by the feed water heaters 3a and 3b through the moisture separator drain pipe 12 having the control valve 11 and used for heat exchange with the feed water there.

In addition, reference numerals 13a and 13b in the drawing denote supply / condensate inlet valves, and reference numerals 14a and 1b.
4b shows each of the water supply / condensate outlet valves, and is used as follows. That is, in general, the steam turbine plant does not stop the plant in the case of a minor accident of the equipment constituting the cycle, but the plant output is reduced to continue the operation.
For example, when an accident such as a water leak occurs in the heat transfer pipe of the feed water heater 2b, a certain series of the feed water heater 2b (hereinafter referred to as B series) is connected to the feed / condensate inlet valve 13b and the feed / condensate outlet valve 14b.
Is completely closed and is separated from the water supply / condensation system.
The method such as continuing the operation by taking advantage of only the series) is adopted.

In the figure, reference numeral 15 indicates a branch drain pipe, and 16 indicates a control valve.

(Problems to be Solved by the Invention) By the way, in the above-described cascade feed water heater drain recovery system, when it is attempted to continue operation by disconnecting the B series from the feed / condensation system, each remaining A series feed water heating An amount of bleed air that is almost commensurate with the plant output before the B-series disconnection is introduced to the units 2a, 3a, and 4a, while the amount of drain from the moisture separator 10 does not change, and thus each A-series feed water heater 2a, 3
The amount of drainage of the feed water heater flowing to a and 4a increases, and the equipment in the planned system will be adversely affected without presuming separation of the series by design.

Above all, feed water heater 2 into which the feed water heater drain flows
When the feedwater heater drain flows, a, 3a, and 4a have a risk that the fluid excitation force of the heat transfer tube increases due to the increase of the feedwater heater drain, the vibration amplitude increases, and damage occurs. For this reason, conventionally, in order to disconnect the above-mentioned one series, the plant output has been greatly reduced, but in the reduction of the plant output, it is troublesome to affect the entire plant including the restriction of the feed water flow rate. It is necessary to perform various driving operations, and the burden on the operator is increasing.

Therefore, the object of the present invention, in the water supply / condensation system composed of a plurality of series of feed water heaters, in the case of attempting to disconnect one of them, complete the disconnection promptly without significantly reducing the plant output, Accordingly, it is an object of the present invention to provide a feed water heater drain recovery control device that reduces the burden on the driving operation.

[Structure of the Invention] (Means for Solving the Problems) The first invention for achieving the above object is to extract a moisture separator and a plurality of feed water heater drain recovery systems from the moisture separator. A control valve to control the amount of drained
The detected water level of the moisture separator is compared with the set value, and the water level adjusting means outputs each control signal to the control valve according to the deviation. When disconnecting the feed water heater provided in the equipment drain recovery system from the supply / condensation system in units of series, when both the supply / condensation inlet valve and the outlet valve of the series to be disconnected are closed,
The present invention is characterized in that a signal switching means is provided so as to switch the control signal to the control valve from the control signal based on the deviation from the water level adjusting means to the control signal which makes the valve opening zero.

A second invention is a moisture separator, a control valve for adjusting the amount of drain extracted from each of the moisture separators into a plurality of feed water heater drain recovery systems, and heating the feed water from the moisture separator. Other control valve that controls the amount of drain extracted outside the drain recovery system is compared with the detected drain water level of the moisture separator and the value set for emergency, and other adjustment is made according to the deviation. A water level adjusting means for outputting a control signal to the valve is provided, and the water level adjusting means is disconnected when disconnecting the water heaters provided in the plurality of feed water heater drain recovery systems from the water supply / condensation system in series units. When both the supply / condensate inlet and outlet valves of the series are closed, the control signal to the other control valve is switched from the control signal based on the deviation from the water level adjusting means to the control signal with the valve opening as the upper limit. And a signal switching means Is shall.

(Operation) During normal operation, the drain water level of the moisture separator is kept constant by controlling the extracted drain amount by the control valve. For this water level adjustment, the moisture separation is provided with water level adjusting means including, for example, a water level detector, a deviation calculator, and a water level calculator, and a control signal is sent to the adjusting valve. here,
When a failure of the feed water heater is found, the entire line is disconnected from the feed / condensation system leaving a healthy line, but at this time the line of the feed / condensation inlet and outlet valves that are disconnected are fully closed. Therefore, this fully closed position is detected by, for example, a position detector, and the operation of the control valve for adjusting the water level of the moisture separator is stopped by this signal. That is, the signal switching means provided in the water level adjusting means is operated to set the valve opening of the adjusting valve to zero so as to disconnect the moisture separator and the feed water heater drain recovery system. After that, by guiding the drain from the moisture separator to the outside of the feed water heater drain recovery system, the amount of feed water heater drain flowing through the feed water heater drain recovery system can be reduced.

(Embodiment) An embodiment according to the first invention will be described below with reference to FIG.

Although the present embodiment describes the case where the disconnection of the B series in FIG. 3 is intended, it goes without saying that the disconnection of the A series is assumed, and exactly the same configuration is used for each device of the A series. Be prepared for.

In FIG. 1, in order to make the drain water level of the moisture separator 10 constant, the water level signal from the water level detector 17 and the regular water level set value signal are compared in the deviation calculator 18, and the water level calculator calculates the water level deviation signal. It is output to 19. The water level calculator 19 produces a control signal for making the deviation zero, and outputs the control signal to the control valve 11 via one contact a of the signal switch 20 to adjust the valve opening.

On the other hand, position detectors 21 provided on the feed / condensate inlet valve 13b and the feed / condensate outlet valve 14b respectively in order to allow the drain from the moisture separator 10 to escape to the condenser 9 before the separation of the B series is attempted, twenty two
The output of the feed / condensate inlet / outlet valve fully closed signal is output to the signal switch 20, and the valve opening of the control valve 11 is changed to zero by changing the control signal sent from the water level calculator 19 to zero deviation. The contact of the signal switch 20 is switched to another contact b so as to output the opening signal. Note that reference numeral 23 in the drawing indicates an AND circuit.

Next, the operation of the control element will be described together with the operation of the feed water heater drain recovery system.

Supply / condensate inlet valve 13b and supply / condensate outlet valve 14b during normal operation
Both are fully open, and the feed water sequentially flows through the feed water heater 4b, the feed water heater 3b, and the feed water heater 2b, and is heated by the extraction air from the steam turbine to raise the temperature. At this time, the feedwater heater drain flows in the order of the feedwater heaters 2b, 3b, and 4b in the order opposite to the feedwater flow, and is finally collected in the condenser 9. here,
If there is a water leakage accident in the heat transfer pipe of the feed water heater 2b and it is necessary to disconnect the B series for repair, the feed / condensate inlet valve
When the valve 13b and the condensate / water condensate outlet valve 14b are closed and the valve opening becomes zero, the position detectors 21 and 22 detect this. This detection signal is used as a signal for fully closing the inlet / outlet valve of the water supply / condensation signal and a signal switch.
It is transmitted to 20 and switches the contact. That is, during normal operation, the contact “a” is kept “closed” and the control signal from the water level calculator 19 for making the water level deviation zero is output to the control valve 11, but the contact “b” is switched to “closed”. And contact a is "open"
Then, a signal for making the valve opening degree zero is issued to the control valve 11. As a result, the control valve 11 is fully closed, and the drain flowing from the moisture separator 10 to the feed water heater 3a (see FIG. 3) can be guided to the condenser 9 by opening the control valve 16. After that, the drain water level of the moisture separator 10 is adjusted by adjusting the valve opening of the control valve 16.

Thus, the amount of drainage of the feedwater heater flowing in each of the A-series feedwater heaters 2a, 3a, 4a is reduced by the amount of the drainage from the moisture separator 10 being reduced, and the fluid exciting force is applied to the heat transfer tubes. In addition, the vibration amplitude is reduced and the damage is prevented. Therefore, it is not necessary to drastically reduce the plant output, and the operator is not forced to perform useless driving operation for output adjustment.

Next, an embodiment according to the second invention will be described with reference to FIG. In the first aspect of the invention, the control valve 11 is fully closed, whereby the drain from the moisture separator 10 is collected in the condenser 9. However, unlike the embodiment of the first invention, the control valve 11 does not necessarily have to be fully closed. That is, as shown in FIG. 2, the position detector 21,
There is a method in which the control valve 16 is fully opened by a signal for fully closing the inlet / outlet valve of the feed / condensate from 22 and the drain flowing from the moisture separator 10 to the feed water heater 3a is collected in the condenser 9. This is because there is a large pressure difference between the internal pressure of the condenser 9 and that of the feed water heater 3a, and most of the pressure is reduced toward the condenser 9 having a low pressure despite the release of the control valve 11. It is feasible because the drain flows. In the present embodiment, since the water level signal from the water level detector 24 and the emergency water level set value signal are compared in the deviation calculator 18, the output signal of the water level detector 17 compared with the normal water level set value signal is It is guided to a calculator 25 which produces a control signal for making the water level deviation zero. Further, the upper limit opening signal is guided to the contact b of the signal switch 20.

Also in this embodiment, the amount of drainage from the moisture separator 10 is reduced and the amount of drainage of the feed water heater is reduced, so that the same effect as the first aspect of the invention can be obtained.

[Effects of the Invention] As described above, in the present invention, in the feed / condensation system composed of a plurality of series of feed water heaters, the amount of feed water heater drain flowing through the feed water heater drain recovery system when one of them is to be disconnected. Is suppressed and the plant output does not have to be reduced. Therefore, there is an effect that the burden on the operator in driving is significantly reduced.

[Brief description of drawings]

1 and 2 are configuration diagrams showing an embodiment of a feedwater heater drain recovery control device according to the present invention, and FIG. 3 is a system diagram showing a feedwater heater drain recovery system of a conventional nuclear turbine plant. . 2a, 3a, 4a …… A series feed water heater 2b, 3b, 4b …… B series feed heater 5, 11, 16 …… Control valve 6a, 7a, 8a …… A series drain pipe 6b, 7b, 8b… … B series drain pipe 9 …… Condenser 10 …… Moisture separator 12 …… Moisture separator drain pipe 13a, 13b …… Supply / condensate inlet valve 14a, 14b …… Supply / condensate outlet valve 17, 24 ...... Water level detector 18 …… Deviation calculator 19 …… Water level calculator 20 …… Signal changer 21, 22 …… Position detector 25 …… Calculator

Claims (2)

[Claims] 1. A moisture separator, a control valve for adjusting the amount of drain extracted from the moisture separator into a plurality of feed water heater drain recovery systems, and a detected drain water level of the moisture separator. And a water level adjusting means for comparing the set value with each other and outputting a control signal to each of the control valves according to the deviation, the water level adjusting means being provided in the plurality of feed water heater drain recovery systems. When disconnecting the supplied water heater from the supply / condensation system in units of series, when both the supply / condensation water inlet valve and the outlet valve of the separated series are closed, the control signal to the control valve is supplied to the water level adjusting means. The feed water heater drain recovery control device is provided with a signal switching means for switching a control signal based on a deviation from the control signal to a control signal for zeroing the valve opening degree. 2. A moisture separator, a control valve for adjusting the amount of drain extracted from the moisture separator into a plurality of feed water heater drain recovery systems, and the moisture separator to the feed water heater. Another control valve for controlling the amount of drain extracted outside the drain recovery system is compared with the detected drain water level of the moisture separator and the value set as an emergency, and the other of the above is determined according to the deviation. A water level adjusting means for outputting a control signal to the control valve, wherein the water level adjusting means separates the water supply heater provided in the plurality of water supply heater drain recovery systems from the water supply / condensation system in units of a series, When both the supply / condensate water inlet valve and the outlet valve of the series to be disconnected are closed, the control signal to the other control valve is set to the upper limit of the valve opening degree from the control signal based on the deviation from the water level adjusting means. Signal switching hand to switch to control signal Feed water heater drain recovery control device, characterized in that it comprises a.