JPS62250901A - Controller for concentrator - Google Patents

Abstract

PURPOSE:To suppress carry-over by changing a water level determined by a water level setter of an evaporator wherein waste liquid is introduced via a water supply control valve and a heater into the lower-limit preset water level by means of a signal of the height of the water level detected by a liquid contact type water level setter. CONSTITUTION:A pressure differential type water level detector 10 and a liquid contact type electrostatic capacity water level setter 11 are provided for detection of the water level of an evaporator 5. The displacement which does not appear in apparent specific gravity due to the void of liquid and carry-over can not be detected by the water level detector 10 and therefore the titled controller is constituted so that this displacement is detected by the water level setter 11. As the control of the water level, a signal output from the water level detector 10 is sent to a water level setter 20 and a water supply control valve 2 is automatically controlled by a water supply controller 22 so that the difference of the preset water level and the measured water level is made to zero. In such a case that carry-over is caused on the liquid level, the height of the water level is detected by the water level setter 11 and the signal is sent to the water level setter 20 and the preset water level is changed into a lower- limit preset water level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a concentrator control device installed in a radioactive waste treatment facility of a nuclear power plant.

(Prior Art) A conventional concentrator control device controls the water level of an evaporator into which wastewater flows through a water supply control valve and a heater.
The water level measured by the differential pressure type water level detector installed in the evaporator is density-corrected, and the opening degree of the water supply control valve is adjusted to eliminate the deviation between this measured water level signal and the set water level set on the water level setting device. Control - configured to Such a concentrator control device keeps the water level in the evaporator constant.

In addition, in conventional concentrator control devices, carryover may occur due to foaming depending on the liquid concentration and liquid properties in the evaporator, but carryover cannot be detected with a differential pressure water level detector, so a differential pressure type water level detector cannot detect carryover. A wetted capacitance water level detector detects this and issues an alarm. When an alarm is issued, the operator uses manual remote control to control the evaporator water level, monitor the differential pressure water level detector of the steam canister, and the heating steam m meter of the steam sent to the heater, in order to suppress carryover.
The amount of water supplied to the evaporator and the amount of heated air to the heater are appropriately controlled.

However, such operations require a single operator to perform them manually, and if these operations are performed incorrectly, the concentrator in operation may stop abnormally, affecting the equipment operating rate. occurs. In addition, when carryover occurs, the radioactive decontamination coefficient of the evaporated steam in the evaporator deteriorates significantly, and the treated water that has condensed from the evaporation in the evaporator cannot be used as water for release into the environment or as water for reuse within the plant. Therefore, it is necessary to suppress carryover as soon as possible.

(Problems to be Solved by the Invention) As described above, in the conventional concentrator control device, when carryover occurs, the operator must appropriately control the evaporator water level, water supply u, etc. by manual remote control. Calming carryover.

However, since such operations are manual operations, there is a problem in that if the operator makes a mistake, the concentrator may stop abnormally. Further, when carryover occurs, the above-mentioned disadvantages occur, so it is necessary to suppress carryover as soon as possible.

The present invention has been made in view of the above circumstances, and is capable of suppressing carryover by optimally and automatically controlling the evaporator water level, water supply amount, etc. even when the evaporator causes carryover. The present invention aims to provide a concentrator control device.

[Structure of the invention]

(Means for Solving the Problems) The present invention sets the water level of an evaporator into which waste liquid flows through a water supply control valve and a heater by measuring and setting the water level using a differential pressure type water level detector provided in the evaporator. A concentrator control device that controls the water supply by adjusting the opening degree of the water supply control valve so as to eliminate deviation from a set water level set in the water level setting device, wherein the set water level set in the water level setting device is It is characterized in that the water level is changed to the lower limit set by a water level high signal from a wetted water level setting device installed in the evaporator.

(Function) According to the present invention, when carryover occurs in the evaporator, the wetted water level setter detects the high water level due to this carryover, and the set water level set in the water level setter becomes the lower limit set water level. Since the water supply groove valve opening degree is adjusted in accordance with this lower limit set water level and the water level of the evaporator is controlled, carryover can be automatically and quickly suppressed.

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

FIG. 1 is a diagram showing an embodiment of a concentrator control device according to the present invention.

The waste liquid flowing through the water supply 111i5 valve 2 is sent to the circulation pump 3 via the heater 4 and the evaporator 5.
It is recirculated in the flow path that returns to the A part of the waste liquid heated in the heater 4 is evaporated in the evaporator 5, exits from the evaporative steam outlet 6, and is condensed into condensate in the next stage equipment. The heated steam flowing in through the steam control valve 7 undergoes heat exchange within the heater 4 and is sent to the steam return system 8 .

The concentrator 1 is constituted by devices having such functions.

The evaporator 5 is provided with a differential pressure type water level detector 10 and a liquid contact type capacitance water level setting device 11.

The differential pressure type water level detector 10 is a differential pressure type water level detector based on the liquid pressure inside the evaporator 5, and cannot detect liquid voids or carryover that does not appear in the specific gravity.
It is suitable for preventing cavitation, etc. of the circulation pump 3 because it reliably detects the liquid layer inside. The capacitance water level detector 11 is an electrostatic capacitive water level detector that comes into contact with liquid, and in order to reliably detect a foam layer that does not appear in the apparent specific gravity, it detects expansion of voids in the liquid in the evaporator 5. Suitable for detecting carryover bubbles.

Normally, the waste liquid that flows into the water supply control valve 2 is forcibly circulated through the heater 4 and the evaporator 5 by the circulation pump 3, and the waste liquid that has been heated to steam in the heater 4 is transferred to the evaporator 5.
It evaporates inside the tank and exits to the evaporation steam outlet 6.

The concentrator control device according to the present invention controls the water level of the evaporator 5 to be constant, and a differential pressure type water level detector 10 sends a signal to the water level setting device 20 to set the evaporator water level in the water level setting device 20. (The deviation between the set value and the indicated value is O
The water supply control valve 2 is automatically adjusted and controlled by the water supply controller 22 so that the water supply controller 22 controls the water supply control valve 2 .

Further, when carryover occurs in the evaporator, the water level signal detected by the capacitance water level detector 11 is sent to the water level setting device 20.
The set water level of the water level setter 20 is changed to the lower limit set water level.

Furthermore, the opening degree of the steam control valve 7 can be adjusted in accordance with a signal from a steam controller 21 from a differential pressure type water level detector 10. In addition, when the water level height is detected by the capacitance water level detector 11 and the set water level of the water level setting device 20 is changed to the lower limit setting water level, this steam control valve 7 detects the water level by the signal from the differential pressure type water level detector 10. When the water level signal from the capacitance water level detector 11 is not released even if the water level falls to the lower limit set value of the capacitance water level detector 11, the valve opening is closed.

Next, the operation of the concentrator control device according to the present invention will be explained. FIG. 2 shows an explanatory diagram of the operation of the concentrator control device according to the present invention. When carryover occurs in the evaporator 5 during operation, the capacitance water level detector 11 detects the water level due to foaming. Turn on the water level to the capacitance water level detector 11 (block S
When the signal 1) is input, the water level controller 20 sets back the water level set value to the lower limit position than normal (block S
2). As the set value decreases, the differential pressure type water level detector 10
When a deviation occurs between the indicated value and the set value of the liquid level in the evaporator 5, which is inputted by
3). If the water supply is stopped, the water level in the evaporator 5 will continue to drop unless the heating steam G is reduced. During this process, when the OFF (block S9) signal is input to the capacitance water level detector 11, the water level controller 20 starts to control the lower limit setting value from 1M to block $4) and sets the water level of the evaporator 5 to the lower limit. The set value is kept constant and operation continues (block S5).

At this time, the amount of heating steam continues to flow as before the carryover occurs, and the opening degree of the steam control valve 7 is adjusted and controlled according to the water level signal from the differential pressure type water level detector 10 (third
Fig. Heating steam amount).

In this way, the water level in the evaporator 5 can be maintained at a low level and the carryover phenomenon can be suppressed.

-Even if the signal of the force differential pressure type water level detector 10 reaches the lower limit set value of the water level controller 20, the capacitance water level detector 11 remains 0FF.
If L is not present (block S6), the heating steam controller 21:
The heating steam flow rate control valve 7 is automatically adjusted to reduce the amount of heating steam and the process is stopped (block S7). When the amount of heating steam decreases, the foam layer decreases and carryover is suppressed. The carryover is suppressed by stopping the heating steam, and when an OFF (block S9) signal is input to the capacitance water level detector 11, the water level is controlled at the lower limit set value of the water level setting device. In addition, the steam control valve 2 is operated manually, and the steam control valve 2 is operated manually.
The amount of heated steam is automatically adjusted by the steam regulator 21 and gradually increases to the set value (block 58) (heated steam M in FIG. 4), and the ventilation of the steam is restarted. At this time, if a high water level occurs again in the capacitance water level detector 11, the evaporator 5
It is determined that there is a component that causes carryover in the waste liquid being processed, the system operation is stopped, and the cause is removed.

〔Effect of the invention〕

According to the present invention, when carryover occurs in the evaporator, the wetted water level detector detects the high water level due to this carryover, and the set water level set in the water level setting device becomes the lower limit set water level, and this lower limit setting Since the water level in the evaporator is controlled by adjusting the opening degree of the water supply control valve according to the water level, carryover can be automatically and quickly suppressed.

Therefore, it is possible to suppress carryover and prevent deterioration of the radioactive moisture content of the treated water in the concentrator, and it is possible to appropriately control the concentrator, which reduces the burden on the operator and prevents operator malfunction. .

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the concentrator control device according to the present invention, FIG. 2 is an explanatory diagram of the operation of the concentrator control device according to the present invention, and FIG. 3 is a system diagram showing an embodiment of the concentrator control device according to the present invention. FIG. 4 is a characteristic diagram of the liquid level in the evaporator at each stage in the control via blocks S and S7. DESCRIPTION OF SYMBOLS 1...Concentrator, 2...Water supply control valve, 3...Circulation pump, 4...Heater, 5...Evaporator, 6...Evaporation steam outlet, 7...Steam control Valve, 8...steam return system,
10... Differential pressure type % type %

Claims (1)

[Claims] 1. The water level of the evaporator into which waste liquid flows through the water supply control valve and the heater is determined by the water level measured by a differential pressure type water level detector provided in the evaporator and the setting determined by the water level setting device. In a concentrator control device that controls the water supply by adjusting the opening degree of the water supply control valve so as to eliminate deviation from the water level, the water level set in the water level setting device is set to the water level set in the water level setting device. A concentrator control device characterized in that the water level is changed to a lower limit setting based on a water level high signal from a water level setting device. 2. The concentrator control according to claim 1, characterized in that the steam pipe to the heater is provided with a steam control valve whose opening degree is adjusted according to the water level measured by the differential pressure type water level detector. Device. 3. In the steam control valve, the set water level of the water level setting device becomes the lower limit set water level due to the high water level signal from the wetted water level detector.
and when the high water level signal from the wetted water level detector is not released even if the water level measured by the differential pressure type water level detector falls to the lower limit set water level, the concentration is opened. instrument control device.