JPH103320A - Tank temperature control device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide a highly reliable tank temperature control device. A tank temperature control device according to the present invention includes a multiplier for calculating a deviation value a between an actual measured tank temperature and a target tank temperature, a predetermined judgment value b or a correction for correcting the judgment value. A determination device 5 that compares the value bc with the deviation value a to determine whether the output is acceptable or not, and a steam valve connected to an output circuit of the determination device 5 and the temperature control device 3 and output by the determination device 5 7, a full-open command circuit 6 for giving a full-open command to the steam valve 7, a fall detector 18 for detecting the fall of the output signal, and a full-close command circuit 17 for giving a full-close command to the steam valve 7 by a signal from the fall detector 18. It is characterized by having. According to the present invention, the operational safety of the tank temperature control device can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tank temperature control device for controlling a temperature in a tank for storing a liquid to be sprayed on an iron plate in a lower process line of a steel facility.

[0002]

2. Description of the Related Art In a conventional tank temperature control device, a liquid to be sprayed on a material is maintained at a predetermined temperature in a tank, and when a liquid in a tank is heated without a heat loss element before spraying, When the set temperature in the tank is changed, the set temperature is compared with the measured temperature, and the control is performed by feedback control.

[0003]

When the temperature of the liquid in the tank in which the spraying of the material is stopped is increased, the tank is sealed without any heat-dissipating elements, so that the feedback control is performed in a one-way process. , Conventional simple PID
In the control (proportional element, integral element, differential element), if the temperature rise time is too fast, the temperature rises excessively, and the target value is exceeded (exceeded).
Was.

[0004] Further, if the target value is not exceeded, there is a problem that the temperature rise takes time and the working efficiency deteriorates. Further, the controllability of the tank temperature has a problem that the process gain changes between when the spraying of the material is stopped and when the spraying of the material is started.

The present invention solves the above-mentioned problems of the prior art,
The control at the temperature rise stage when the spraying stops on the material allows the target value to be reached in the shortest possible time without overshooting (overshoot phenomenon) the target value. It is an object of the present invention to provide a tank temperature control device having a fastest temperature rise and an automatic gain switching function which enables stable control without fluctuations in the control response at the time.

[0006]

According to the present invention, there is provided a tank temperature control device comprising: a steam valve for controlling a temperature of a coolant by inserting heated steam into a tank for storing the coolant; A temperature detector that measures and outputs an actual measured temperature in the tank, a temperature control device that compares the predetermined measured target temperature in the tank with the measured actual temperature in the tank and controls the degree of opening and closing of the steam valve; A multiplier for calculating a deviation value between the measured temperature value and the target temperature in the tank, and a determination device for determining whether the output is acceptable or not by comparing the deviation value with a predetermined determination value or a correction value obtained by correcting the determination value. A fully open command circuit that is connected to an output circuit of the determination device and the temperature control device and that provides a fully open command to the steam valve by an output signal output from the determination device; a fall detector that detects a fall of the output signal; Depending on the signal from the detector It is characterized in that a total closing command circuit for providing a full closing command to the steam valve Te.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a tank temperature control device according to the present invention will be described. FIG. 1 shows equipment for spraying a cooling liquid onto the material 13 conveyed by the material conveying roll 9, and the temperature of the tank 1 for storing the cooling liquid to be sprayed is controlled by the degree of opening and closing of the steam valve 7. That is, the steam valve 7
Is to control the temperature of the coolant by inserting heated steam into the tank 1 for storing the coolant. The temperature detector 8 is a device that measures the temperature of the coolant and outputs a measured value of the temperature in the tank, and the temperature control device 3 is configured as shown in FIG.
This is a device that controls the degree of opening and closing of the steam valve 7 by comparing a predetermined tank internal temperature target value SV and a tank internal temperature measured value PV.

A multiplier 4 is connected to the temperature detector 8 and is a circuit for obtaining a deviation value a between the measured tank temperature PV and the target tank temperature SV. This is an apparatus for comparing a correction value bc obtained by correcting the determination value b with a hysteresis value c and a deviation value a to determine whether the output is acceptable or not.

A fully open command circuit 6 is connected to the output circuit of the judging device 5 and the temperature control device 3 and gives a 100% full open command to the steam valve 7 by an output signal output from the judging device 5, and falls. The detector 18 is a circuit that is connected to the determination device 5 and detects the falling of the output signal. Then, the fully-closed command circuit 17 gives a fully-closed command to the steam valve 7 based on a signal from the falling detector 18 to output 0%. The gain switching device 10 is a device for adjusting the control gain of the temperature control device 3.

FIG. 2 shows an embodiment of the fastest temperature rise control device and a tank temperature control device with an automatic gain switching function. In the state where the pump 2 is stopped and before spraying, the liquid in the tank is moved by the steam valve 7 at the highest speed. Raise the temperature to the target value at the speed.

The multiplier 4 calculates (the liquid temperature set value-the liquid temperature value in the tank) to obtain the deviation, and determines the deviation.
The command for fully opening the steam valve is determined based on the judgment value of the above. The determined full-open command is actually sent to the full-open command circuit 6 by the steam valve 10.
0% and the fastest temperature rise. The determination that the temperature has been raised is obtained by the determination device 5, and the steam detector 7 is fully closed once by the falling detector 18 and the fully closed command circuit 17, thereby eliminating overshoot to the target temperature and preventing excessive temperature rise. doing.

The stable control thereafter is performed by the temperature control device 3
Is implemented by feedback PID control, but by switching the gain (gain) when the spray (spraying) pump 2 is stopped by the gain switching device 10, stable feedback PID control before spraying is realized. I have. When the pump 2 is operated, the coolant is sprayed from the spray nozzle 14 to the material 13, the cooled liquid sprayed by the return pipe 16 is returned to the tank 1, and the process gain of the liquid temperature control in the tank is changed. The switching device 10 switches the gain of the feedback PID control by stopping / operating the spray pump to perform stable liquid temperature control in the tank during spraying.

FIG. 3 is a diagram showing an apparatus for controlling the temperature of a liquid to be sprayed on a material in a tank.
A tank temperature control device equipped with a means for raising the temperature in the fastest time,
In addition, even if the process gain is different between the fluid temperature control in the tank without heat loss before spraying and the tank temperature control when heat loss during spraying is applied, the optimum PID control for the change is obtained. FIG. 7 is an explanatory diagram showing control characteristics of a tank temperature control device having an automatic gain switching function provided with a means for automatically changing the gain of a PID parameter so that the temperature rise start signal can be obtained; Operation signal, 35 is a temperature rise completion range signal, 3
Reference numeral 6 denotes an opening signal of the steam valve 7, reference numeral 37 denotes PID control at the gain A shown in FIG.

Thus, in order to achieve the above object,
In the present embodiment, the following controls (1) to (4) are provided in the control at the temperature raising stage before spraying.

(1) The difference between the target liquid temperature rise value in the tank and the liquid temperature value in the tank is calculated, and if there is a deviation equal to or greater than the judgment value, the steam valve is fully opened and the maximum capacity of the equipment is used. By raising the temperature, the temperature can be raised in the shortest time.

(2) When the difference between the target liquid temperature in the tank and the liquid temperature in the tank is within the judgment value after the start of the temperature increase, the steam valve is fully closed once and the temperature is raised due to excessive temperature rise. It is possible to prevent shoots.

(3) Thereafter, no-load gain (optimum gain in a state where the heat loss is small without spraying)
, It is possible to stabilize the liquid temperature in the tank before spraying.

(4) Since heat loss increases during spraying, the response is changed to a PID parameter with improved responsiveness, and control can be performed to keep the liquid temperature in the tank constant during spraying.

As described above, the present invention comprises a means for raising the temperature of the liquid in the tank at the highest speed, and a means for stabilizing the controllability by switching the gain of the PID between the time of temperature rise and the time of spraying. The control at the temperature rise stage before spraying does not overshoot the target value and can be controlled in the shortest time, and the PID gain is constantly switched in consideration of the difference in process gain between before and during spraying the material. It has stable control.

That is, in the tank temperature control device having the fastest temperature rising and gain automatic switching functions of the present invention, the temperature rising time can be shortened in a short time, and the feedback PID control with stability corresponding to the load fluctuation can be performed. realizable. As a result, there is an effect that the operation efficiency is improved by shortening the temperature rise time and energy is saved by preventing excessive temperature rise.

[0021]

According to the present invention, the operational safety of the tank temperature control device can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a tank temperature control device showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a control function of FIG. 1;

FIG. 3 is an explanatory diagram showing the operation of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 2 Pump 3 Temperature control device 4 Multiplier 5 Judgment device 6 Fully open command circuit 6 7 Steam valve 8 Temperature detector 10 Gain switching device 10 17 Fully closed command circuit 18 Falling detector

Claims (1)

[Claims] 1. A steam valve for controlling the temperature of a coolant by inserting heated steam into a tank for storing the coolant, and measuring the temperature of the coolant to output an actual measured value of the temperature in the tank. A temperature detector, a temperature controller that compares a predetermined target tank temperature value and the actual tank temperature measurement value to control the degree of opening and closing of the steam valve, the actual tank temperature value and the internal tank temperature A multiplier for determining a deviation value from a target value; a determination device for determining whether the output is acceptable or not by comparing the deviation value with a predetermined determination value or a correction value obtained by correcting the determination value; A fully open command circuit that is connected to an output circuit of a temperature control device and provides a fully open command to the steam valve by an output signal output from the determination device; a falling detector that detects a fall of the output signal; Signal from detector Tank temperature control device comprising anda total closing command circuit for providing a full closing command to the steam valve by.