JPH0756609B2 - Temperature control device - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a temperature control device, and more particularly to a temperature control device installed for preheating control of sodium equipment, pipes, valves and the like in a fast breeder reactor.

[Technical background of the invention and its problems] In a fast breeder reactor, liquid sodium is usually used as a coolant. Since sodium is a solid at 98 ° C or lower, it is usually heated to 200 ° C or higher and used as liquid sodium. Sodium itself is heated in the dump tank, but it is necessary to uniformly heat the parts such as various reactor vessels, equipment and pipes where sodium is filled and circulated at a predetermined rate of change depending on the filled state of sodium. in this case,
An electric heater is usually used as a heating source. And
The electric power may be supplied to the electric heater by controlling the firing angle of the thyristor or the like, but is usually controlled by the on / off control by the switch.

Next, the configuration of the conventional temperature control device will be described with reference to FIG. A temperature detector 2 and an electric heater 3 are installed on an object to be heated such as the pipe 1, and a heat insulating material 4 is further provided on the temperature detector 2.
Is provided. The temperature measurement value PV detected by the temperature detector 2 is input to the preheat control device 5 and compared with the temperature setting unit SV. Then, the subtraction value SV-PV between the temperature set value SV and the temperature measured value PV is input to the on / off control unit 6, and an on / off control signal MV that turns on MV when SV ≧ PV and turns off MV when SV <PV is input. Input to the preheating power supply 7 and use a semiconductor type relay
Turns on / off SSR (Solid State Relay) 8. The power supplied to the electric heater 3 is opened / closed according to the on / off state of the relay SSR8. Although FIG. 3 illustrates one temperature control loop, a temperature control device typically includes a plurality of temperature detectors 2.
The temperature measurement value PV is input from to control a plurality of electric heaters 3.

By the way, the case where a microprocessor is used as the preheating control device 5 is shown, and the on / off control signal MV is the digital output 9 of the microprocessor. This digital output 9 is transmitted to the input side of the SSR8 housed in the preheating power supply device 7, and by turning on and off the SSR8, the power supplied to the electric heater 3 is opened and closed.

However, in the temperature control device having the above-mentioned configuration, if the preheating control device 5 fails, the digital output 9 is lost and the preheating operation cannot be interrupted. In this case, especially in small-diameter pipes, the heat radiation is large, so that the temperature drops rapidly and sodium freezing may occur. Therefore, as a means for solving such a problem, there are countermeasures such as multiplexing the preheating control device 5 or providing a backup controller, but both of them have a problem of increasing the space and the quantity. In addition, a measure of forcibly applying the electric power supplied from the preheating power supply device 7 to the electric heater 3 can be considered, but since the signal of the temperature detector 2 is lost, it is in an uncontrolled state, and conversely, the pipe 1 etc. Another problem is that there is a risk that the temperature will rise too high.

[Object of the Invention] The present invention has been made in view of the above circumstances, and an object thereof is to freeze the sodium by maintaining the temperature of an object to be heated such as a pipe by the preheating power supply device even when the preheating control device fails. An object of the present invention is to provide a temperature control device having a simple structure capable of preventing the above.

SUMMARY OF THE INVENTION The present invention relates to an electric heater and a temperature detector installed near an object to be heated, and a temperature measurement value of the object to be heated detected by the temperature detector. A preheat control device for performing a comparison calculation with a predetermined temperature set value and issuing an on / off control signal according to the temperature difference, and an on / off control signal output from this preheat control device is input and the preheat control device outputs the on / off control signal according to the on / off control signal. In a temperature control device having a preheating power supply device having an opening / closing device for turning on and off an electric circuit including an electric heater, a thermosensitive resistance element having a positive temperature characteristic in which a resistance value increases with temperature rise is provided in the vicinity of the object to be heated. And a switch that becomes conductive when the preheat control device fails, connected in series with the thermal resistance element, and in series with the thermal resistance element and switch. A first diode for preventing the sneak of a current passing through the preheat control device is connected, and the heat-sensitive resistance element, the switch, and the first diode are connected to an on / off control signal input section of the switchgear, and A second diode for preventing current from flowing through the heat-sensitive resistance element is interposed in series between the preheat control device and an on / off control signal input section of the switchgear, and the second diode for preventing the sneak of a current passing through the heat sensitive resistance device is connected in series when the preheat control device fails. When the heated object reaches a temperature not higher than the temperature set value or not higher than the temperature set value,
The resistance value of the heat-sensitive resistance element is changed in response thereto, and an ON or OFF control signal is given to the switchgear to maintain the temperature of the object to be heated at the temperature set value. .

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

FIG. 1 shows a circuit configuration diagram of an embodiment of the present invention. As shown in FIG. 1, in addition to the temperature detector 11 and the electric heater 12, the temperature of the object to be heated such as the pipe 10 increases as the temperature rises. A thermal resistance element (Positive) with positive temperature characteristics whose resistance value increases.
Temperature Coefficient Thermistor (hereinafter referred to as PTC) 13 is installed and is covered with a heat insulating material 14. PT
C13 is a semiconductor having a composition such as barium titanate and has a characteristic having a curve as shown in FIG. That is, in the figure, the characteristic curve of PTC is represented by the temperature T on the horizontal axis and the resistance R on the vertical axis. The resistance is small when the temperature is low, and the resistance rapidly increases when the temperature exceeds a certain threshold Ts. It has the property of The signal of the PTC 13 is input to the preheat power supply device 15, is connected to the input side of the SSR 17 via the diode 16 for preventing current sneak, and the power supply of the electric heater 12 can be opened and closed. That is,
One end of PTC13 is connected to the input section 31 of SSR via the first diode.
By connecting to the
Try to prevent it from getting around to PTC13. Further, by interposing the second diode 16B between the on / off control section 21 and the input section 31 of the SSR, the current passing through the PTC 13 is prevented from flowing into the on / off control section 21. A relay 18 is inserted in series with the PTC 13, which is normally open so that no current flows through the PTC 13, but is closed when the preheat controller 19 fails. In addition, the temperature detector 11
The temperature measurement value PV detected by is input to the preheat control device 19 and is compared with the temperature set value SV. Then, the subtraction value SV-PV is input to the on / off control unit 21, and the on / off control signal MV described below is output. That is, if SV ≧ PV
On / off control signal MV that turns off MV when MV is on and SV <PV
Is input to the preheat power supply unit 15, and the semiconductor type relay SSR17
Is turned on and off, and the power supplied to the electric heater 12 is opened and closed to maintain the object to be heated such as the pipe 10 at the temperature setting value SV.

Next, the operation of this embodiment will be described.

Sodium equipment, valves, piping during preheat operation of fast breeder reactor
The object to be heated such as 10 is heated to a predetermined temperature by the electric heater 12 as described above. If the preheat controller 19 fails now, the digital output 20 is lost. Preheat control device 19
Detects the loss of digital output 20. That is, the failure is detected by self-diagnosis of the microprocessor in the preheat control device 19. Then, in response to this failure detection, the relay 18 of the preheating power supply device 15 is automatically closed. At this point, the temperature of the piping 10 etc. is above Ts in Fig. 2, so PTC13
Has a large resistance, so that no current flows through PTC13. Since the digital output 20 is also lost, the current in the input section 31 of the SSR becomes zero. Therefore, the SSR 17 is turned off, the electric power is not supplied to the electric heater 12, and the temperature of the pipe 12 and the like decreases. When the temperature of the pipe 10 etc. further decreases and becomes Ts or less, the resistance of the PTC 13 sharply decreases and a current flows through the circuit including the PTC 13, the relay 18, the first diode 16A and the input part 31 of the SSR. Is turned on, and electric power is supplied to the electric heater 12. When electric power is supplied to the heater 12 and the temperature of the pipe 10 etc. rises and the temperature rises above Ts this time, the resistance of the PTC 13 rapidly increases.
No current flows to SSR17 and it turns off. Therefore,
The electric power to the electric heater 12 is cut off, and the temperature of the pipe 10 and the like decreases. In this way, when the preheat control device 19 fails,
Due to the function of PTC 13, the temperature of the pipe 10 and the like is kept at the temperature Ts, and the freezing of sodium is prevented. Here, as the PTC 13, it is necessary to select an element whose temperature Ts is slightly higher than the freezing temperature of sodium.

Further, according to the present embodiment, the additional equipment to the conventional temperature control device is achieved by only adding the PTC13 and the diodes 16A, 16B and the cables connecting them, so that the preheating control device 19 It is very simple and economical compared to multiplexing. Moreover, since the PTC 13 is configured to be connected to the control circuit side by connecting to the input section 31 of the SSR via the first diode 16A, the current flowing through the PTC 13 is small and the PTC 13 is connected to the electric heater 12 in series. Like when connecting to the power circuit side by connecting to
PTC13 does not generate heat.

Further, the PTC 13 also has the functions of a detector and a controller, and the pipe 10 and the like are kept at a substantially constant temperature, and the controllability is good. Furthermore, since the PTC13 is controlled to be turned on and off by the change in resistance, the on / off of this electric heater continuously shifts,
It operates with accurate temperature and can improve controllability. Further, since there is no electrical contact, it does not open or close due to corrosion and does not operate, so that reliability and maintainability can be improved.

In the above embodiment, the case where the microprocessor is used as the preheat control device is described, but the same applies to the case where the analog controller is used, and in the above embodiment, the power switch of the preheat power supply device is used. However, it is needless to say that the same can be applied to the case where an electromagnetic contactor is used.

[Effects of the Invention] As described above, according to the temperature control device of the present invention,
Even when the preheating control device fails, the temperature of the sodium equipment, pipes, valves, etc. in the fast breeder reactor can be maintained, and the freezing of sodium can be prevented. Moreover, since the equipment for that purpose only needs the PTC, the diode, and the cables for connecting them, it has an excellent effect that it has a simple configuration and very good controllability. Furthermore, since the resistance continuously changes due to the temperature change of the heat-sensitive resistance element and the on / off of the electric heater continuously changes, the electric heater operates at an accurate temperature and the controllability can be improved. Also,
Since there is no electrical contact, it will not open and close due to corrosion and will not malfunction, thus improving reliability and maintainability.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention, FIG. 2 is a diagram showing characteristics of PTC, and FIG. 3 is a configuration diagram of a conventional temperature control device. 10 …… Piping 11 …… Temperature detector 12 …… Electric heater 13 …… PTC 14 …… Heat insulation material 15 …… Preheat power supply 16A, 16B …… Diode 17 …… SSR 18 …… Relay 19 …… Preheat controller 21 …… ON / OFF control section 31 …… SSR input section

Claims (3)

[Claims] 1. An electric heater and a temperature detector installed in the vicinity of an object to be heated, and a temperature measurement value of the object to be heated detected by the temperature detector are input and predetermined with the temperature measurement value. A preheat control device that performs a comparison calculation with a temperature set value and issues an on / off control signal according to the temperature difference, and an on / off control signal output from this preheat control device are input, and the electric heater is included according to this on / off control signal. In a temperature control device having a preheating power supply device having a switchgear for turning on and off an electric circuit, a thermosensitive resistance element having a positive temperature characteristic in which a resistance value increases with temperature rise is installed near the object to be heated, A switch that becomes conductive when the preheat control device fails is connected in series with the thermosensitive resistance element, and the preheat control is connected in series with the thermosensitive resistance element and switch. A first diode for preventing a current from flowing through the switch is connected, and these heat-sensitive resistance element, switch and first diode are connected to an on / off control signal input section of the switchgear, and the preheat control is further provided. A second diode for preventing the sneak of the current passing through the heat-sensitive resistance element is interposed in series between the device and the on / off control signal input section of the switchgear, and the object to be heated is operated when the preheat control device fails. When the temperature is equal to or lower than the temperature set value or not equal to or lower than the temperature set value,
According to it, the resistance value of the heat-sensitive resistance element is changed to give an ON or OFF control signal to the switchgear to maintain the temperature of the object to be heated at the temperature set value. Temperature control device. 2. The object to be heated is sodium equipment of a fast breeder reactor,
The temperature control device according to claim 1, which is a pipe or a valve. 3. The temperature control device according to claim 1, wherein the heat-sensitive resistance element having a positive temperature characteristic is a semiconductor having a composition such as barium titanate.