JPS6387505A - Drain level controller - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an improvement of a drain water level control device suitable for a drain treatment system that generates relatively little drain water, such as a nuclear power generation facility.

(Conventional technology) For example, nuclear power generation! ! In the case of 2-equipment systems, the temperature and pressure of the generated steam are relatively low, so when converting carbon thermal energy into work, much of the working steam is converted into condensate.

Various measures have been taken to properly deal with drain water. FIG. 5 shows a conventional embodiment for appropriately disposing of generated drain water, and reference numeral 1 indicates a moisture layer reheater.

The moisture separator reheater 1 is connected to a drain tank 3 through a drain pipe 2.
It is equipped with

The drain tank 3 is connected to a heat exchanger 1 such as a feed water heater 7 through which a regulating valve 5 and drain pipes 4 and 5 are inserted, and the drain water flowing into the feed water heater 7 must open the regulating valve 5. This ensures that the appropriate amount is sent. That is, the drain tank 3 is provided with a water level detector 8, and the detection signal of the water level detector 8 is sent to the water level controller 9, where when the value exceeds a predetermined set value, the deviation signal is output. The calculated signal is produced as a valve opening signal, and the regulating valve 5 is opened with the produced valve opening signal. Therefore, the drain water generated in the moisture separation reheater 1 is
- Although the drain water is initially stored in the drain tank 3, when it exceeds a predetermined water level, the water level regulator 9 opens the regulating valve 5, so that the drain water is effectively used as a heat source for the feed water heater 7.

(Problem to be solved by the invention) By the way, in this type of operation, the drain water generated from the moisture separator reheater 1 is almost stable at the rated time, and the control required for drain treatment is difficult. Although the system works smoothly without any problems, if drain water abnormally accumulates in the drain tank 3, such as during startup, the conventional control system may no longer be able to properly process the drain water.

For example, while the operation is stopped, the moisture separator reheater 1, drain pipe 2, etc. are in a cold state, so the working steam rapidly turns into drain,
Drain water in excess of the planned amount flows into drain tank 3.
As a result, the conventional control system scales up beyond its operating range, making it unable to properly process drain water and causing the feed water heater 7 to overflow, which, if left untreated, will result in water induction. Drain water flows from the feedwater heater to the steam turbine (not shown), which is also a factor in causing supercooling.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a drain water level control device that eliminates the above-mentioned factors so that the drain water in a drain tank is always maintained within a predetermined value.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention temporarily stores drain water generated in a moisture separation reheater in a drain tank, so that the drain water in the drain tank reaches a predetermined water level. In a drain water level control device that opens a regulating valve to flow water to a heat exchanger when the water exceeds a predetermined water level, when the drain water in the drain tank exceeds a predetermined water level, the drain water is not only flowed to the heat exchanger but also flows to the condenser. The present invention is characterized in that a water level adjustment device is provided to allow the water to flow, and a control valve on the inlet side of the condenser is opened in response to an output signal from the water level adjustment device.

(Function) When the water level in the drain tank reaches an abnormally high level, the regulating valve connected to the heat exchanger opens. In this case, the drain water flowing into the heat exchanger is controlled to an appropriate amount.

On the other hand, the remaining drain water is sent to the condenser through the control valve on the condenser inlet side. Therefore, even if a large amount of drain water accumulates in the drain tank such as during startup, the drain water is separated into the heat exchanger and condenser in an appropriate amount, so the drain water in the drain tank is always kept within the specified value. Retained.

(Example) An embodiment of the present invention will be described below based on the drawings.

FIG. 1 shows an example of a drain water level control device to which the present invention is applied. In FIG. 1, reference numeral 1 indicates a moisture separator and reheater. Continuing to 3. The drain tank 3 is connected at one end to a regulating valve 5 and a heat exchanger 7, such as a feed water heater, through a drain pipe 4. The other drain pipe 4 is connected to a condenser 12 through a control valve 10 and a conduit 11.

The drain tank 3 is provided with a first water level adjusting device A consisting of a first water level detector 8 and a first water level regulator 9. This first water level adjustment device A is a control device required for processing drain water in the drain tank 3 during rated operation, and its details are shown in FIG. The water level signal is sent to the first water level controller 9, where the actual water level signal and the signal from the setting device 21 are compared through a comparator 22. If there is a deviation, the deviation signal is converted into a proportional signal by a PID calculator 23. Integral and differential calculations are performed to generate an opening signal for the regulating valve 5. In this way, the regulating valve 5 opens, and the drain water sent to the heat exchanger is adjusted to an appropriate value.

The drain tank 3 is further provided with a second water level adjustment device B comprising another second water level detector 13 and a second water level controller 14. The second water level adjustment device [B is a device that operates when the drain tank 3 is at an abnormal water level, and its details are shown in FIG.
The actual water level signal from the high value setter 24 is sent to the comparator 25, where a signal higher than the standard water level signal is given from the high value setter 24, and a higher deviation appears in the actual water level signal than the signal from the high value setter 24. The PID calculator 26 performs proportional, integral, and differential calculations on the deviation signal. This calculation signal is sent to the switch 28, where the opening signal generator 27 conducts contacts a-e, and a valve opening signal is given to the control valve 10 through the conduction path. In this way, the abnormal water level in the drain tank 3 is appropriately distributed to the heat exchanger and the condenser. Even during startup, when the water level in the drain tank 3 is relatively low, the signal from the second water level detector 13 is sent to the low value signal generator 29, and as shown in FIG. It is cut by the NOT logic circuit 30. The AND logic circuit 32 operates on the condition that the startup wait forced open signal 33 is input and the signal of the NOT logic circuit 30 is not input, and this output causes the contact a- of the switch 28 to be closed.
C passes through 4, and the control valve 10 opens as described above. Note that when the water level in the drain tank 3 returns to normal, the 4th
The sign of the output signal is inverted by the NOT logic circuit 31 shown in the figure, and b and c of the switch 28 are rendered conductive. This closes the control valve 10 and returns to normal drain water treatment.

〔Effect of the invention〕

As explained above, in the present invention, when the drain tank has an abnormal water level, a water level adjustment device is newly installed so that drain water can flow not only to the heat exchanger but also to the condenser. The drain tank can always maintain a predetermined water level, making it possible to perform stable water level control for this type of water level control. Therefore, unexpected problems such as water induction due to an abnormal water level in the heat exchanger can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic control system diagram showing one embodiment of the present invention, and FIG.
The figure is a schematic block diagram of the first water level regulator, Figure 3 is a schematic block diagram of the second water level regulator, Figure 4 is a schematic block diagram showing the logic circuit of the switch, and Figure 5 is a conventional implementation. It is a schematic control system diagram showing an example. 1... Moisture separation reheater 3... Drain tank 5.
...Adjusting valve 7...Heat exchanger 8...First
Water level detector 9...First water level regulator lO...Control valve 12...Condenser 13...Second water level detector 14...Second water level regulator A...・First water level adjustment device B...Second water level adjustment device agent Patent attorney Noriyuki Chika Yudo Hirofumi Mitsumata' / No. 1, Figure 4, Figure 5

Claims (1)

[Claims] In the drain water level control device, drain water generated in the moisture separation reheater is temporarily stored in a don tank, and when the drain water in the drain tank exceeds a predetermined water level, a regulating valve is opened to flow the drain water to a heat exchanger. When the drain water exceeds a predetermined water level, the drain water is not only passed through the heat exchanger, but also
A drain water level control device characterized in that a water level adjustment device is provided so that the water also flows into the condenser, and a control valve on the inlet side of the condenser is opened in response to an output signal of the water level adjustment device.