JPS5949484B2 - Steam generator water level control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water level control device for a steam generator in a nuclear power plant.

In order to operate a steam generator efficiently and safely, it is necessary to maintain the water level in the steam generator within a desired range at all times.

For this reason, conventionally, the main steam flow rate, drum water level, and water supply flow rate to the steam generator at the steam generator outlet side were detected, and the water level in the steam generator was controlled by operating the water supply valve based on these detected values. was.

However, such a conventional device has a problem in that when the turbine is under extremely low load, the main steam flow rate and the feed water flow rate are small, and it is difficult to accurately detect them, so that automatic control cannot be performed.

As a solution to this problem, a method was devised to automatically control the water level based only on the detected value of the drum water level, but since turbine bleed air cannot be taken in at low loads, the feed water temperature is low, and the main steam at low loads is Due to the characteristic of nuclear power plants that the temperature is conversely high, increasing the feed water flow rate will result in a large amount of low temperature feed water being carried into the steam generator.

In this type of steam generator, the flow rate of the high-temperature heating fluid, that is, the reactor coolant, is held constant and its temperature is also held substantially constant, so the amount of heat exchanged does not change immediately, so the steam The water temperature in the generator becomes temporarily low.

The inside of a steam generator is generally divided into a lower heating area where there are no steam bubbles, and an upper boiling area where steam bubbles are generated and a two-phase state of gas and liquid phases. As the water temperature in the generator decreases, the boundary between the two zones moves upward and the volume of the boiling zone decreases.

In other words, a so-called reverse response occurs in which the water level decreases.

This causes a new problem of not being able to follow load fluctuations, so this method has not been used for anything other than long-term constant load operation.

The present invention was made in view of the above-mentioned problems of the conventional device, and includes a main steam temperature detector provided on the steam outlet side of the steam generator and a feed water temperature detector provided on the feed water inlet side of the steam generator. An arithmetic circuit calculates the amount of heat transferred in the steam generator from the output of the main steam temperature detector and the output of the feed water temperature detector, and further calculates the amount of heat transferred in the steam generator from the output of the reactor power detector and the amount of transferred heat. A second calculation circuit calculates a water supply flow rate setting value, and uses the water supply flow rate setting value to operate a water supply valve provided in a pipe communicating with the water supply inlet of the steam generator to raise the water level of the steam generator. Control is performed automatically, and the temperature measurement of main steam and feed water according to the present invention is easy and accurate, and enables automatic water level control of the steam generator in the low load region of the turbine.

Embodiments of the present invention will be described below based on the drawings.

In the drawing, a reactor coolant circulation system 1 is composed of a circulation pump 2, a nuclear reactor 3, a steam generator 4, and piping 5.6.7.

On the other hand, the water supply or steam circulation system 8 includes a water supply pump 9, a water supply valve 10. Steam generator 4. It is composed of a turbine 11 and pipes 12, 13, 14, and 15.

A flow meter 16 is installed in the pipe 13 adjacent to the water supply valve 10. Feed water temperature detectors 17 are disposed close to the steam generators 4, respectively.

Furthermore, a main steam temperature detector 18 is provided in the piping 14 in close proximity to the steam generator 4 .

On the other hand, the reactor 3 is provided with a reactor power device 19, and the steam generator 4 is provided with a water level detector 20, respectively.

The feed water temperature detector 17 and the main steam temperature detector 1
8 are each independently electrically connected to the same first arithmetic circuit 21, and furthermore, the first arithmetic circuit 21 and the reactor power detector 19 are also independently connected to the same second arithmetic circuit 21. It is electrically connected to circuit 22.

The second arithmetic circuit 22 is electrically connected to a compensation circuit 23, and the compensation circuit 23 is further electrically connected to the water level detector 20 via a comparison circuit 24, and the flowmeter 1
6 and the controller 25, respectively.

The controller 25 is electrically connected to the water supply valve 10.

In this embodiment with the above configuration, the reactor coolant flows through the circulation system 1 in the direction of the arrow, and at this time, it receives heat in the reactor 3, heats the feed water flowing through the circulation system 8 in the steam generator 4, and generates steam. to occur.

Correspondingly, the feed water flows into the steam generator 4 from the piping 13, receives heat from the reactor coolant, becomes steam, and enters the piping 13.
4.

As described above, the amount of heat is exchanged within the steam generator 4, and the amount of transferred heat is determined by the temperature of the feed water being detected by the feed water temperature detector 17, and at the same time, the steam flowing out from the steam generator 4 is the main steam, which is saturated steam. Main steam temperature detector 1
8, and the rain detection value is sent to the first arithmetic unit 21, where it is calculated.

The output signal of the first arithmetic unit 21 is sent to the second arithmetic circuit 22.
The theoretical feed water flow rate is calculated from the output signal and the output signal sent from the reactor power detector.

Thereafter, the theoretical water supply flow rate is sent to the compensation circuit 23, where it is compared with the actual water supply flow rate sent from the flow meter 16, and the difference between the theoretical water supply flow rate and the actual water supply flow rate, that is, the flow rate difference, is calculated.

On the other hand, the water level of the steam generator 4 is detected by the water level detector 20, and the actual water level signal is sent to the comparison circuit 24, where it is compared with a predetermined standard water level, and the water level difference between the actual water level and the standard water level is calculated. be done.

The same water level difference is sent to the compensation circuit 23, where the adjustment flow rate to maintain the water level of the steam generator 4 at the standard water level is calculated from the above-mentioned flow rate difference and the water level difference.This result is sent to the control circuit 25.
A control signal for the water supply valve 10 is generated, the control signal is sent to the water supply valve 10, and the water supply valve 10 is operated in accordance with the adjusted flow rate.

Since this embodiment has the above-described configuration and operation, when the reactor output increases or decreases in proportion to the turbine load, the feed water flow rate is immediately adjusted and the main steam flow rate changes.
That is, by preparing for changes in the water level of the steam generator 4, it has the advantage that automatic control is possible in the low load region, which could not be adequately controlled with conventional devices.

[Brief explanation of drawings]

The figure is a system explanatory diagram showing one embodiment of the present invention. 4...Steam generator 1.17...Feed water temperature detector, 1
8... Main steam temperature detector, 19... Reactor output detector, 21... First arithmetic circuit, 22... Second arithmetic circuit.

Claims (1)

[Claims] 1. A main steam temperature detector on the steam generator outlet side, a feed water temperature detector on the steam generator inlet side, the output of the feed water temperature detector, and the output of the main steam temperature detector in the steam generator. A first arithmetic circuit that calculates the amount of transferred heat, a reactor power detector, an output of the reactor power detector, and the first arithmetic circuit.
A water level control device for a steam generator, comprising: a second arithmetic circuit that calculates a flow rate setting value of feed water supplied to the steam generator from the output of the arithmetic circuit.