JPS63241616A - Temperature controller - Google Patents

Abstract

PURPOSE:To reduce a temperature detector/temperature detecting cable and a temperature control unit, etc., of thermocouple, etc. by utilizing that a heat sensitive resistance element (PTC) also has the functions of the temperature detector and the temperature control unit. CONSTITUTION:A vessel, equipment and piping, etc., are needed to be previously heated to be in a specified temperature in a fast breeder, etc., and it is realized by using an electric heater 2 consisting of the PTC. If the temperature of the piping 1 is lower than a curie point which is decided by the composition of the PTCs, the resistance value of the electric heater 2 becomes comparatively small, so that the electric heater 2 generates heat by applying a current so as to heat the piping 1. But if the temperature of the piping 1 becomes higher than 300 deg.C, the resistance value of the electric heater 2 remarkably increases to cut off the current. Therefore, the electric heater 2 stops the generation of heat and the temperature of the piping 1 lowers by radiating heat from the piping 1. It is possible to hold the previously heated temperature by repeating the above-mentioned operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a temperature control device installed in a preheating control system for, for example, sodium container equipment, piping, etc., especially in a fast breeder reactor.

(Prior Art) In fast breeder reactors, liquid sodium is usually used as a coolant. Since sodium is solid at temperatures below 98°C, it is usually heated to above 200°C and used as liquid sodium. The sodium itself is heated in the dump tank, but the parts where sodium is filled and circulated, such as various reactor containers, equipment, and piping, need to be heated uniformly at a predetermined rate of change depending on the state of sodium filling. .

In this case, an electric heater is usually used as the heating source. In order to control the temperature of the containers, equipment, piping, etc., a thermocouple is installed to detect the temperature corresponding to the electric heater installed in the container, equipment, piping, etc., and this thermocouple is installed in the control room to control the temperature. When connected to a controller, if the temperature of containers, equipment, piping, etc. is below the temperature set value, a power-on signal for the electric heater is output, and if it is above, a power-off signal for the electric heater is output from the temperature controller. That's what I do.

(Problem to be solved by the invention) However, this method requires a huge amount of preheating control equipment such as temperature detectors, electric heaters, cables, and temperature controllers, and there is a strong demand for rationalization of equipment from an economical perspective. It has been.

The purpose of the present invention is to reduce the number of temperature detectors, temperature detection cables, temperature controllers, etc., and to reduce the number of containers to nine devices.

An object of the present invention is to provide a temperature control device that can raise the temperature of piping, etc. at a predetermined rate of change.

[Structure of the invention]

(Means for Solving the Problems) The temperature control device of the present invention uses a thermosensitive resistance element (Positive Temperature Resistance Element) having a positive resistance-temperature characteristic in which the resistance value rapidly increases when the temperature exceeds a specified value.
Perature Coefficient Ther
mistor.

The present invention is characterized in that it uses a PTC (hereinafter referred to as PTC) and is equipped with a thyristor inverter device to change the voltage of the preheating power supply supplied to the electric heater.

(Function) In the present invention, the electric heater using PTC is a heat-sensitive resistance element that also has a temperature control function, and it is possible to reduce the need for temperature detectors such as thermocouples, temperature detection cables, temperature controllers, etc. It becomes possible.

Also, an electric heater using PTC is not enough.

Although it is impossible to raise the temperature of equipment, piping, etc. at a predetermined rate of change, this is achieved by changing the voltage of the preheating power source using a thyristor inverter device.

(Embodiments) The present invention will be described below with reference to embodiments shown in the drawings. In FIG. 1, an electric heater 2 made of a heat-sensitive resistance element PTC having a positive resistance-temperature characteristic whose resistance value increases as the temperature rises is installed on an object to be heated such as a pipe 1.

This PTC is a semiconductor having a composition such as barium titanate, and has resistance-temperature characteristics as shown in FIG.

In other words, the resistance-temperature characteristic curve of a PTC is expressed by the temperature T on the horizontal axis and the logarithm of the resistance R on the vertical axis.The lower the temperature, the lower the resistance, and the threshold is the Curie point determined by the composition of the PTC. It has a characteristic that the resistance value increases sharply when it exceeds the set temperature (approximately 300° C. in the case of FIG. 2).

A temperature detector 3 such as a thermocouple is also installed at a typical temperature monitoring point of the heated object, such as the pipe 1, and is covered with a heat insulating material 4 and an exterior plate 5.

Preheating power supplied to the electric heater 2 is supplied via a thyristor inverter device 6 and a preheating power supply board 7.

The thyristor inverter device 6 houses a rectifier circuit 6a for obtaining a variable DC voltage, a DC reactor 6b for smoothing the DC voltage, an inverter circuit 60 for converting DC power into AC power, and the like. Thyrist inverter device 6
The variable AC voltage generated is supplied to a plurality of preheating power supply panels 7. The preheating power supply panel 7 houses a circuit breaker 7a, a fuse 7b, and the like.

The equipment for giving variable voltage commands to the thyristor inverter device 6 includes a temperature setting circuit 8 that outputs temperature settings in time series. A temperature control circuit 9 that generates a temperature increase command signal based on signals from the temperature detector 3 and temperature setting circuit 8. and the thyristor inverter device 6 based on the signal from the temperature control circuit 9.
There is a phase control circuit 10 for controlling the firing angle of the thyristor.

Next, the operation of the temperature control device of the present invention configured as described above will be explained. For example, in a fast breeder reactor, two vessels and equipment,
It is necessary to preheat piping etc. to a specified temperature, but this
This is realized by an electric heater 2 made of TC. In other words, if the temperature of the pipe 1 is below the Curie point (approximately 300°C in the case of Figure 2) determined by the composition of the PTC, the resistance value of the electric heater 2 is relatively small, and therefore the electric heater 2 is generates heat and the pipe 1 is heated. However, when the temperature of the pipe 1 becomes 300° C. or higher, the resistance value of the electric heater 2 increases sharply and the current is cut off. Therefore, the electric heater 2 stops generating heat, and the temperature of the pipe 1 decreases due to heat radiation from the pipe 1. By repeating the above steps, it becomes possible to maintain the preheating temperature of the piping even without a temperature detector, temperature detection cable, temperature controller, etc.

When using the electric heater 2 made of PTC, consideration must be given to providing a method for raising the temperature at a predetermined rate of change. In FIG. 3, the horizontal axis is time t, and the vertical axis is temperature T, and shows the temperature increase characteristics of the pipe 1. here,
When a PTC electric heater 2 having a single Curie point of 300° C. is used, the temperature is raised to 300° C. in a short time as shown by the broken line, giving thermal stress to the pipe 1.

In order to raise the temperature at a predetermined rate of change, it is necessary to change the voltage of the preheating power source. In other words, in FIG. 2, the resistance value is approximately constant below 300° C., so it is possible to control the amount of heat generated by the electric heater 2 by changing the voltage of the pre-value power source. The equipment for changing the voltage of the preheating power source is the thyristor inverter device 6, and the temperature detector 3. Temperature setting device8. A temperature control circuit 99 and a phase control circuit 10 are used.

A temperature detector 3 such as a thermocouple is provided at a typical temperature monitoring point of a heated object such as a pipe. The temperature setting circuit 8 has a temperature rise characteristic as shown by the solid line in Figure 3, and the temperature control circuit 9 compares the temperature setting value from the temperature setting circuit 8 with the temperature detection value from the temperature detector 3. and generates a temperature increase command signal. The temperature increase command signal is input to the phase control circuit 10,
The thyristor firing angle of the thyristor inverter device 6 is controlled to change the voltage of the preheating power source.

That is, at the start of temperature rise, the preheating power source is set to a low voltage to reduce the heat generation of the electric heater 2, and over time, the preheating power source is brought closer to the rated voltage, and finally the temperature can be shifted to self-temperature control by the electric heater 2 made of PTC. .

In the embodiment shown in FIG. 1, a case has been described in which a temperature detector 3 such as a thermocouple is provided at a typical temperature monitoring point of a heated object such as a pipe 1, and the temperature is raised by feedback thereof. However, if the heat dissipation characteristics of the object to be heated are known, it is possible to control the temperature increase without feedback from the temperature detector 3, and an example thereof is shown in FIG.

In FIG. 4, the temperature increase command signal from the voltage setting circuit 11 which outputs voltage signals in time series changes the firing angle of the thyristor of the thyristor inverter device 6 through the phase control circuit 10, thereby changing the voltage of the preheating power source. Is possible.

Moreover, as the electric heater 2, it is of course possible to use one in which a PTC and a sheathed heater are connected in series. Furthermore, although the piping of a fast breeder reactor has been mentioned as an object to be heated, the present invention can be applied to equipment other than fast breeder reactors.

〔Effect of the invention〕

As described above, in the present invention, the PTC electric heater has both the functions of a temperature detector and a temperature controller, and a very simple and economical preheating control device can be realized. Further, by changing the voltage of the preheating power source using a thyristor inverter device, it is possible to raise the temperature at a predetermined rate of change, and it is possible to reduce the thermal stress applied to the container 2 equipment and piping.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing one embodiment of the temperature control device of the present invention, FIGS. 2 and 3 are resistance temperature characteristic diagrams and temperature rise characteristic diagrams of PTC, and FIG. 4 is another embodiment of the present invention. FIG. 1... Heated object (piping) 2... Electric heater using PTC 3... Temperature detector 4... Heat insulating material 5... Exterior plate 6... Thyristor inverter device 7... Preheating power supply panel 8...Temperature setting circuit 9...
・Temperature control circuit 10... Phase control circuit 11...
Voltage setting circuit representative Patent attorney Nori Chika Ken Yudo Hirofumi Mitsumata Figure 1 The return T ('C) Figure 2 θ construction Figure 3

Claims (3)

[Claims] (1) An electric heater consisting of a heat-sensitive resistance element with a positive resistance-temperature characteristic, in which the resistance is small when the temperature of the heated object is below a set value, and the resistance increases sharply when it is above the set value, and this electric heater A temperature control device comprising: a thyristor inverter device that changes the power supply voltage; and an electric circuit that provides a time-series temperature increase command signal to the thyristor inverter device. (2) The objects to be heated are fast breeder reactor sodium containers, equipment,
The temperature control device according to claim 1, which is a pipe or the like. (3) The temperature control device according to claim 1, wherein the heat-sensitive resistance element having positive temperature characteristics is a semiconductor having a composition such as barium titanate.