JPS5819901A - Temperature controller - Google Patents

Abstract

PURPOSE:To heat a liquid uniformly and to prevent the corrosion due to thermal stress, by heating the liquid from the external of a tank by divided electric heaters and turning on only required heaters in accordance with the liquid level and operating measured values of plural thermometers to agitate the liquid. CONSTITUTION:Divided electric heaters 2 are installed around a tank 1, and a liquid level measurer 3, thermometers 4 the number of which is equal to the number of divided heaters,and an agitater 9 are provided in the tank. A liquid signal and temperature signals are inputted to a liquid level range deciding part 5 and a tempeature control setting part 6. In the liquid level range deciding part 5, the heater whose range the measured liquid level corresponds to is decided. In the temperature control setting part 6, turn-on and off temperatures of heaters are set. These signals are inputted to a heater controlling part 8, and the control for only required heaters is executed in accordance with the range of the liquid level. In an agitater controlling part 7, the temperature difference between the upper part and the lower part is operated in accordance with the liquid level; and when this difference becomes a set value or more, the agitater 9 is started to keep the temperature of the liquid uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature control device for a tank, and particularly to a control device suitable for application as a radioactive waste treatment control device for a nuclear power plant.

Conventionally, temperature control of concentrated waste liquid storage tanks in radioactive waste treatment facilities has been carried out by controlling the temperature of the liquid by turning heating steam on and off using measurements taken by a single temperature measuring device and a liquid level measuring device. The value was kept within a certain range, but with this method, there is a large temperature difference between the heating source and the tank, and there is a risk of corrosion of the tank due to thermal stress, as well as local heating and damage to the thermometer side. There were 7 drawbacks.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and provide a tank temperature control device with good control performance.

In order to avoid heating the tank and liquid locally, instead of the conventional heating using steam, we used an electric heater to heat the tank from outside.Also, we divided the heater into several locations and used it to control the liquid level. In conjunction, only the necessary heaters are turned on. Furthermore, the liquid is uniformly heated by calculating the measured values from a plurality of temperature measuring instruments and stirring the liquid accordingly.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, an electric heater 2 divided into a plurality of parts is installed around the circumference of a tank 1. As shown in FIG. 2, inside the tank 1, a liquid level measuring device 3, a number of temperature measuring devices 4 equal in number to one division of the heater, and a stirrer 9 are installed. The liquid level signal and the temperature signal are input to a liquid level range determination unit 5 and a temperature control setting unit 6, respectively.

The liquid level range determination section 5 determines which heater range the measured liquid level corresponds to. The temperature control setting section 6 sets the ON-OFF temperature of the heater.

These signals are input to the heater control section 8, and as shown in FIG. 3, only the necessary heaters are controlled according to the range of the liquid level. In addition, the stirrer control unit 7 calculates the temperature difference between the upper and lower portions in accordance with the liquid level, and when the temperature difference exceeds a set value, the stirrer 9 is activated to stir the layer to keep the layer temperature uniform.

According to this embodiment, uniform and good temperature control can be performed without locally heating the liquid and the tank.

According to the present invention, since the liquid and the tank are not locally heated, there is no fear of corrosion due to thermal stress, and fine temperature control is possible by split control of the heater. This has the effect of controlling temperature.

[Brief explanation of the drawings] Figure 1 is an external view of a tank with multiple heaters installed;
The figure is an overall configuration diagram of the present control device, and FIG. 3 is a diagram showing the operational relationship of the control switch with respect to the liquid level. 5... Liquid level range determination section, 7... Stirrer control section, 8.
・Himan f diagram No. 20 ′ Kaya 3rd eye

Claims (1)

[Claims] 1. In a temperature control device consisting of a temperature and liquid level measuring instrument, an arithmetic unit, and a control circuit, a liquid level range determining section determines the measured value range, and a heater's 0N-
A temperature control device comprising a heater control section for performing OFF control and a stirring control section for uniformly stirring a liquid.