JPH0632804B2 - Waste liquid concentrator - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an apparatus for concentrating waste liquid discharged from a nuclear power plant or the like.

[Technical background of the invention]

Generally, for example, a waste liquid discharged from a nuclear power generation facility is concentrated by a waste liquid concentrating device to reduce its volume and stored as radioactive waste. This waste liquid concentrating device has been conventionally constructed as shown in FIGS. That is, 1 is an evaporator, and the waste liquid is supplied into the evaporator 1 from a waste liquid tank 2 or the like. Then, the waste liquid in the evaporator 1 is circulated through the heater 4 by the circulation pump 3. Also,
The heater 4 includes a steam supply source 5 for heating and a steam supply pipe 6
The heating steam is supplied via the. And this heater 4
Heats the waste liquid by exchanging heat between the heating steam and the waste liquid,
It is configured to be sent to the steam can 1. The heated waste liquid is evaporated and concentrated in the evaporator 1. A steam flow rate adjusting valve 7 and a warm-up bypass valve 8 bypassing the steam flow rate adjusting valve 7 are provided in the middle of the steam supply pipe 6, and the steam for controlling the flow rate of the heating steam is also provided. A flow rate detector 9 is provided. The steam flow rate adjusting valve 7 and the warm-up bypass valve 8 are the steam flow rate control device.
Controlled by 10 , the flow rate of the heating steam supplied to the heater 4 is controlled.

This steam flow control device 10 is constructed as shown in FIG. That is, 11 is an operating device, and the operation command signal output from the operating device 11 by the operation of the operator is sent to the warm-up bypass valve 8 and the warm-up bypass valve 8 opens. A small amount of steam for heating is sent to the heater 4 for warm-up operation. Further, the operation command signal output from the operation unit 11 is the AND circuit 1
2 is also configured to be sent. Further, the warm-up bypass valve 8 is provided with a limit switch 8a which operates when the warm-up bypass valve 8 is opened. When the warm-up bypass valve 8 is completely opened, the limit switch 8a switches to the AND circuit 12. It is configured to be signaled. Therefore, when the operation unit 11 is operated to output the operation command signal and the warm-up bypass valve 8 is completely opened, a signal is sent from the AND circuit 12 to the timer 13.
This timer 13 starts. The operating time of the timer 13 is set to a time required for the warm-up operation, and when the warm-up operation is completed, the timer 13 sends a warm-up completion signal to the function generator 14. The function generator 14 outputs the steam flow rate target value signal from the time when the warm-up completion signal is input. As shown in FIG. 3, the vapor flow rate target value signal rises at a constant rate with the lapse of time from the time of completion of warm-up, and after reaching the target value, the target value is kept constant. It is configured. And this function generator 1
The steam flow rate target value signal output from 4 is the deviation calculator 15
Sent to. Further, the steam flow rate signal from the steam flow rate detector 9 is input to the deviation calculator 15. The deviation calculator 15 calculates the deviation between the steam flow rate target value signal and the steam flow rate signal, and uses this deviation signal as the valve opening adjuster 16
Send to. The valve opening adjuster 16 is configured to adjust the opening of the steam flow rate adjusting valve 7 so that the deviation becomes zero and control the flow rate of the heating steam supplied to the heater 4. There is. Therefore, the flow rate of the heating steam supplied to the heater 4 increases at a constant rate over time, and reaches a predetermined target flow rate. Therefore, abrupt heating of the waste liquid at the start of operation is prevented.

[Problems of background technology]

In the conventional waste liquid concentrating device, when the waste liquid is heated at the start of operation and reaches a temperature near the boiling temperature of the waste liquid, a bumping phenomenon may occur, which may cause damage to equipment. To prevent such problems, the rate of increase in the flow rate of the heating steam at the start of operation should be reduced and the rate of increase in the temperature of the waste liquid should be reduced. It causes a problem.

[Object of the Invention]

The present invention has been made based on the above circumstances, and an object thereof is to provide a waste liquid concentrating device that can reliably prevent the bumping phenomenon and that does not increase the heating time of the waste liquid at the start of operation. To do.

[Outline of Invention]

The present invention controls an evaporating can for evaporating and condensing a waste liquid, a heater for exchanging heat of the waste liquid in the evaporating can with heating steam, and a flow rate of the heating steam supplied to the heater. Based on signals from the steam flow rate control valve, the steam flow rate detector that detects the flow rate of the heating steam, the waste liquid temperature detector that detects the temperature of the waste liquid, and the steam flow detector and the waste liquid temperature detector. When the waste liquid temperature detected by the waste liquid temperature detector reaches the vicinity of the boiling temperature by controlling the steam flow control valve, the signal for temporarily narrowing the valve opening of the steam flow control valve is output to change the steam flow rate. And a steam flow control device for reducing the flow rate. Therefore, when the temperature of the waste liquid reaches near the boiling temperature and the bumping phenomenon can occur, the flow rate of the heating steam decreases and the temperature rise rate of the waste liquid becomes small, so that the bumping phenomenon can be prevented. . Further, it is only when the temperature of the waste liquid reaches near the boiling temperature that the flow rate of the heating vapor is reduced to decrease the temperature rise rate of the waste liquid, and therefore the heating time of the waste liquid does not become long.

Example of Invention

An embodiment of the present invention will be described below with reference to FIGS. 4 to 7.

In the figure, reference numeral 101 denotes an evaporator, and waste liquid is supplied from the waste liquid tank 102 or the like into the evaporator 101. Then, the waste liquid in the evaporator 101 is circulated through the heater 104 by the circulation pump 103. Also, this heater 10
4, heating steam is supplied from a heating steam supply source 105 through a steam supply pipe 106. And this heater 10
Reference numeral 4 is configured to exchange heat between the heating vapor and the waste liquid, heat the waste liquid, and send it to the evaporator 101. The heated waste liquid is evaporated and concentrated in the vapor evaporator 101.
A steam flow rate adjusting valve 107 and a warm-up bypass valve 108 bypassing the steam flow rate adjusting valve 107 are provided in the middle of the steam supply pipe 106, and steam for controlling the flow rate of heating steam is provided. A flow rate detector 109 is provided. In addition, the evaporation can 101 includes the evaporation can 1
A waste liquid temperature detector 110 for detecting the temperature of the waste liquid in 01 is provided. The steam flow rate adjusting valve 107 and the warm-up bypass valve 108 are connected to the steam flow rate control device 111.
And the flow rate of the heating steam supplied to the heater 104 is controlled.

This steam flow control device 111 is constructed as shown in FIG. That is, 112 is an operating device, and the operation command signal output from the operating device 112 by the operation of the operator is sent to the valve controller 113 of the warm-up bypass valve 108, and the warm-up bypass valve 108 is The valve is opened and a small amount of heating steam is sent to the heater 104 to perform warm-up operation. Further, the operation command signal output from the operation unit 112 is also sent to the AND circuit 114. In addition, the warm-up bypass valve 10
8 is provided with a limit switch 108a that operates when it is opened. When the warm-up bypass valve 108 is completely opened, a signal is sent from the limit switch 108a to the AND circuit 114. ing. Therefore, when the operation unit 112 is operated to output the operation command signal and the warm-up bypass valve 108 is completely opened, a signal is sent from the AND circuit 114 to the timer 115 and the timer 115 is activated. The operating time of the timer 115 is set to the time required for the warm-up operation, and when the warm-up operation is completed, the timer 15 sends a warm-up completion signal to the signal switch 116. The waste liquid temperature signal from the waste liquid temperature detector 110 is sent to the function generator 117. The function generator 117 is configured to output a vapor flow rate target value signal corresponding to the waste liquid temperature. This vapor flow rate target value signal is set so as to rise stepwise in accordance with the rise of the waste liquid temperature in the evaporator 101 as shown in FIG. 6, and the waste liquid temperature is set to the boiling temperature. It is set so that the temperature once drops to a low level in the region where it reaches the vicinity of, and it returns to the target value again when the waste liquid temperature is above the boiling temperature. The steam flow rate target value signal output from the function generator 117 is sent to the change rate limiter 118. The rate-of-change limiter 118 is the steam function generator 1
The rate of change when the level of the vapor flow rate target value signal sent from 17 rises is regulated to a predetermined rate of change or less. Therefore, this change rate limiter 118
As shown in FIG. 7, the vapor flow rate target value signal output from the engine has a rate of change at the time of its rise limited to a predetermined rate of change α or less. Then, the steam flow rate target value signal output from the change rate limiter 118 is sent to the deviation calculator 119. Further, a steam flow rate signal from the steam flow rate detector 109 is input to the deviation calculator 119. The deviation calculator 119 obtains the deviation between the steam flow rate target value signal and the steam flow rate signal, and sends the deviation signal to the above-mentioned signal switch 116 via the change rate limiter 120. The signal switch 116 is connected to the timer 115.
The deviation signal is sent to the valve opening adjuster 121 when the warm-up completion signal is input. The valve opening adjuster 121 adjusts the opening of the steam flow rate adjusting valve 107 so that the deviation becomes zero, and the heater 104
It is configured to control the flow rate of the heating steam supplied to the. Therefore, the flow rate of the heating steam supplied to the heater 104 is controlled in accordance with the steam flow rate target value signal as shown in FIG.

An embodiment of the present invention configured as described above is an operating unit 112.
Is operated, the warm-up bypass valve 108 is opened, heating steam is supplied to the heater 104 through the warm-up bypass valve 108, and the warm-up operation is performed. When the warm-up operation is completed, the warm-up completion signal is sent from the timer 115 to the signal switch 116. Therefore, the function generator 11
From the deviation calculator 119, a deviation signal corresponding to the deviation between the steam flow rate target value signal sent from 7 to the deviation calculator 119 via the change rate limiter 118 and the steam flow rate signal sent from the steam flow detector 109 is output. It is sent to the valve opening adjuster 121 via the switch 116, and the steam flow rate adjusting valve 107 is controlled. Therefore, the flow rate of the heating steam supplied to the heater 104 is controlled in accordance with the steam flow rate target value signal as shown in FIG. Therefore, when the waste liquid is heated and the temperature thereof reaches the vicinity of the boiling temperature, the flow rate of the heating steam once decreases, and the temperature rising rate of the waste liquid decreases, so that the bumping phenomenon can be prevented. In addition, once the waste liquid reaches the boiling temperature and once it has boiled, a large number of vapor bubbles are formed in the waste liquid, and stable boiling is maintained with these vapor bubbles as the core. Even if it returns to the value, bumping does not occur. Further, since the flow rate of the heating steam is reduced only in the region near the boiling temperature, the heating time of the waste liquid does not become unnecessarily long.

〔The invention's effect〕

As described above, the present invention includes an evaporator that evaporates and concentrates a waste liquid, a heater that heats the waste liquid in the evaporator by exchanging heat with the heating steam, and a flow rate of the heating steam supplied to the heater. A flow rate adjusting valve for controlling the flow rate, a steam flow rate detector for detecting the flow rate of the heating steam, a waste liquid temperature detector for detecting the temperature of the waste liquid, and a signal from the steam flow rate detector and the waste liquid temperature detector. When the waste liquid temperature detected by the waste liquid temperature detector reaches the vicinity of the boiling temperature by controlling the steam flow control valve based on the above, a signal for temporarily narrowing the valve opening of the steam flow control valve is output. And a steam flow rate control device for reducing the steam flow rate. Therefore, when the temperature of the waste liquid reaches near the boiling temperature and the bumping phenomenon can occur, the flow rate of the heating steam decreases and the temperature rise rate of the waste liquid becomes small, so that the bumping phenomenon can be prevented. . Further, the flow rate of the heating steam is reduced to decrease the temperature rise rate of the waste liquid only when the temperature of the waste liquid reaches the boiling temperature, so that the heating time of the waste liquid does not become long and the effect thereof is not increased. Is large.

[Brief description of drawings]

1 to 3 show a conventional example, FIG. 1 is an overall schematic configuration diagram, FIG. 2 is a schematic configuration diagram of a steam flow rate control device, and FIG. 3 is a characteristic diagram of a steam flow rate target value signal. . 4 to 7 show an embodiment of the present invention, FIG. 4 is a schematic configuration diagram of the whole, FIG. 5 is a schematic configuration diagram of a steam flow control device, and FIGS. 6 and 7 are steam flow rates. It is a characteristic view of a target value signal. 101 ... Evaporator, 104 ... Heater, 107 ... Steam flow rate adjusting valve, 109 ... Flow rate detector, 110 ... Waste liquid temperature detector, 111 ... Steam flow rate control device, 117 ... Function generator, 119 ... Deviation calculator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-17601 (JP, A) JP-A-55-31414 (JP, A) JP-A-54-10871 (JP, A)

Claims (1)

[Claims] 1. An evaporation can for evaporating and condensing a waste liquid, a heater for exchanging heat of the waste liquid in the evaporation can with a heating steam, and a flow rate of the heating steam supplied to the heater. A steam flow rate control valve, a steam flow rate detector for detecting the flow rate of the heating steam, a waste liquid temperature detector for detecting the temperature of the waste liquid, and a signal from the steam flow rate detector and the waste liquid temperature detector. When the waste liquid temperature detected by the waste liquid temperature detector reaches the vicinity of the boiling temperature by controlling the steam flow control valve based on the above, the steam is output by outputting a signal for temporarily narrowing the valve opening of the steam flow control valve. A waste liquid concentrating device, comprising: a vapor flow rate control device for reducing a flow rate.