JPS6130198B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic temperature control system in a heat exchanger used when heating and sterilizing liquor, soy sauce, youth, and other liquid foods and filling them into a filling machine. When the fluid is filled but the flow rate is 0 due to a failure of the filling machine, etc. or a failure of subsequent equipment, or when the fluid is not flowing or when it starts flowing, automatic control from sequence control It is possible to control the fluctuations in the temperature of the fluid in which heat is exchanged such as liquid food to a minimum (approximately ±2℃) during steady as well as unsteady conditions, such as when switching to the control of a temperature controller. The aim is to improve operation and quality.

Conventionally, an automatic temperature control device for a heat exchanger has had a configuration as shown in FIG. 1 is a heat exchanger, and on the side of the fluid (liquid food, etc.) to be heat exchanged,
Via the pump 2, the fluid 3 is supplied directly to the filling machine 5 through one side of the heat exchanger 1.
6 is a liquid level alarm. On the heat medium side, a circulation circuit for the medium 11 is formed which includes a steam mixing device 12, a tank 13, and a pump 14. The temperature of the medium 11 is detected by a temperature sensor 28 provided in front of the heat exchanger 1, Automatic temperature controller 19 via wiring 27
is connected to. The automatic temperature controller 19 operates a cooling water solenoid valve 40 via an electric wiring 39 to inject water 41 into the circulation circuit. The control valve 43 is operated through the steam 44
is configured to inject into the steam mixing device 12. 45 is a liquid food temperature recorder.

With the above configuration, when the flow rate of the fluid 3 is in a steady state, temperature control is smoothly performed by adjustment by the automatic temperature controller 19. However, if the filling machine 5 malfunctions or the filling machine becomes full of fluid due to trouble after the filling machine, the pump 2 is stopped by the signal from the liquid level alarm 6, and the fluid supply is stopped (flow rate is 0), or the filling machine is then stopped. If the machine is driven and the pump is driven again by the signal from the liquid level alarm and the fluid starts flowing (flow rate 100), such a flow rate fluctuation occurs, the adjustment by the automatic temperature controller will not be performed smoothly. I saw some shortcomings. In other words, due to the characteristics of the automatic temperature controller (TRCA, which does not have an external feedback function), it cannot be controlled by proportional, differential, or integral operation functions due to the time constant, dead time, etc. If the adjustment is delayed, there is a risk that the temperature of the heat medium will be disturbed and the state of heat exchange with the fluid will become abnormal, resulting in large fluctuations in temperature. The example shown in Figure 6 is for heating and sterilizing sake, with the temperature set at 70°C starting from 8am to 12pm.
Even when heated for 4 hours, a temperature difference of ±5°C was recorded, which caused a quality control problem.

The system of the present invention eliminates the drawbacks of the conventional automatic temperature controller as described above, and will be described in detail below. In other words, when the fluid (alcohol, youth, and other liquid foods) is filled and stopped, the temperature fluctuation of the heat medium (temperature) is minimized, and the fluid reaches zero.
By installing a control unit with functions such as responding instantly to extreme flow rate fluctuations from 100% to 100%, and switching from sequence-based predictive control to automatic temperature control, temperature fluctuations in the medium can be reduced. This is an attempt to control the temperature fluctuations of the fluid and to minimize the temperature fluctuations of the fluid. In FIG. 1, reference numeral 1 denotes a heat exchanger, and on the side of the fluid to be heat exchanged, a pump 2 supplies fluid 3 through an automatic valve 4 and the heat exchanger 1 to a filling machine 5. Reference numeral 6 denotes a liquid level alarm LA attached to the filling machine 5 or a signal generator corresponding thereto, which operates a solenoid valve 7 that controls the automatic valve 4 based on this signal to adjust the flow of the fluid. 8,
9 is an air pipe, and 10 is a speed control. 11 is a medium flowing through the other side of the heat exchanger 1;
Hot water is used, and a circulation circuit including a steam mixing device 12, a tank 13, and a pump 14 is formed on the medium side. Reference numeral 15 denotes steam, and 16 denotes a control valve. Steam is supplied to the steam mixing device 12 by controlling the control valve. 17 is water, 1
Reference numeral 8 denotes a solenoid valve, which constitutes a cold water supply section that supplies water to the circulation circuit for cooling. 19 is an automatic temperature controller (TRCA), 20 is a temperature alarm (TIA), and the electrical wiring 2 is detected by the temperature sensor 28.
7, 26. 21 and 22 are electromagnetic valves that control the steam control valve 16. Reference numeral 23 denotes a solenoid valve for switching the automatic temperature controller 19, which is operated by a signal from the signal generator 6 on the fluid side. 24 and 25 are electromagnetic valves, 26 and 27 are electrical wiring from the temperature sensor 28, 29 and 30 are electrical wiring from the temperature alarm 20, 31 to 34 are air piping,
35 to 38 indicate air pressure reducing valves.

Since the system of the present invention uses the control device configured as described above, it has the following effects.

First, when the supply of the fluid 1 is stopped, the temperature of the hot water 11 is detected by the temperature sensor 28, and the temperature alarm 20 is activated via the electric wiring 26. This temperature alarm controls the steam control valve 16 via the air solenoid valves 25, 22, 21 and the air pipe 31,
The cooling water solenoid valve 18 is regulated via the electrical wiring 28 . In other words, when the upper limit of the temperature alarm is set to +1°C and the lower limit is set to -°C, and the supply of liquid food is stopped, if the temperature drops by 1°C from the setting due to heat radiation from the hot water piping, the air pressure will be reduced. The solenoid valves 25, 22, 21 are activated by the air pressure set by the valve 35.
Open the steam control valve and raise the hot water by 1°C.
Further, if the temperature of the hot water becomes 1° C. higher than the set value due to leakage of steam from the control valve, the water solenoid valve 18 is opened and cooling water is injected to lower the hot water temperature. Therefore, while the supply of liquid food is stopped, the temperature of hot water is maintained at the set value ±1°C. Further, the temperature of the liquid food contained in the heat exchanger is approximately the same as the temperature of the hot water, and is maintained at ±1°C of the set temperature.

Next, when the signal generator 6 of the filling machine issues a signal to start supplying liquid food, the hot water temperature alarm 2
Check the temperature of the hot water at 0. If it is 2℃ higher than the setting
If the temperature is higher than that, open the water solenoid valve 18 and inject cooling water, and if it is 2°C lower than the setting, open the air solenoid valve 24,
The steam control valve 16 is opened via 22 and 21, and steam is injected to bring the temperature of the hot water within ±2° C. of the set temperature. Then, the pump 2 is driven, and the automatic valve 4 is gradually opened via the air solenoid valve 7 and the speed control 170 to improve responsiveness. When the hot water, whose temperature has decreased due to heat exchange with the liquid food, enters the steam mixing device 12, the air pressure reducing valve 37, which is set at the same pressure as the control output value of the automatic temperature controller 19 during normal operation, and the air electromagnetic Valve 23, 22, 2
1 to open the steam control valve 16. After being opened for a certain period of time (until the flow rate of the liquid food becomes constant), the air solenoid valve 23 is switched to the circuit of the automatic temperature controller 19 and the steam control valve 16 is adjusted via the solenoid valves 22 and 21. When adjusting the temperature by sequence control, the automatic temperature controller 19 suppresses the integral operation function among proportional, integral, and differential functions as the adjustment operation, stabilizes the output signal only for proportional operation, and performs the automatic temperature controller's function rather than sequence control. Prevents disturbance when switching to control. The internal integral operation of the automatic temperature control function is stopped by externally filling the integral bellows with the same pressure as the steady state output pressure from the air pipe 34.

While the temperature is being controlled by the automatic temperature controller, it is in a steady state and the temperature is sufficiently controlled.

In addition, if filling is stopped due to trouble with the filling machine or trouble in subsequent processes, the filling machine is filled with liquid food, and the signal generator 6 issues a signal to stop the supply of liquid food, the automatic valve 4 is closed. , the pump 2 is stopped, and the steam control valve 16 is closed after a certain period of time.

As mentioned above, in the method of the present invention, (a) hot water temperature control while liquid food supply is stopped, (b) hot water temperature rechecking when liquid food supply starts, and (c) hot water temperature control by sequence control method when liquid food supply starts. Temperature control, (d) Preventing disturbances when switching from sequence control to automatic temperature controller, (e) Preventing fluctuations in hot water temperature when stopping the supply of liquid food (see Figures 2 and 3). It has the following effects (see (a) to (e)), and can keep the amplitude of temperature control of liquid food within ±2°C of the set temperature not only in steady state but also in unsteady state. (Figure 4). Therefore, it has become possible to operate safely with automatic temperature control and to improve the quality of products.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the automatic temperature control device used in the method of the present invention, Figure 2 is a characteristic diagram of hot water temperature controlled by the method of the present invention, Figure 3 is a characteristic diagram of temperature of liquid food, and Figure 4 is a diagram of temperature characteristics of liquid food. FIG. 5 is a circuit diagram of an automatic temperature control device showing a conventional example, and FIG. 6 is a temperature record diagram during heat sterilization of sake using the conventional method. DESCRIPTION OF SYMBOLS 1...Heat exchanger, 2...Pump, 3...Fluid, 4...Automatic valve, 5...Filling machine, 6...Liquid level alarm or signal generation unit equivalent to it, 11...Medium, 12...Steam mixing device, 13... Tank, 14...Pump, 15...Steam, 16...Control valve, 17...Cold water, 18...Solenoid valve,
19... Automatic temperature controller, 20... Temperature alarm, 23
...Switching solenoid valve, 28...Temperature sensor, 45...Liquid food temperature recorder.

Claims (1)

[Claims] 1. On the medium side of the heat exchanger, the heat exchanger includes a steam mixing device that supplies steam through a control valve, a cold water supply section that supplies cold water through a solenoid valve, a tank, and a pump. A circulating circuit is provided, and an automatic temperature controller operates via a temperature sensor to control the control valve and the solenoid valve to obtain a predetermined temperature. A circuit is installed to supply fluid directly to the filling machine, and an automatic temperature control device equipped with a liquid level alarm or equivalent signal generator is used to prevent extreme fluid flow fluctuations from 0 to 100% that occur on the fluid side. The flow condition of the fluid is adjusted via an automatic valve according to the signal from the signal generator, and on the medium side, the temperature is set in front of the heat exchanger so as to supply steam as a heating source or cold water as a cooling source. It is operated via a sensor, performs predictive temperature control in a fixed time sequence, maintains the medium near the set temperature, and then switches to temperature control by an automatic temperature controller with an external feedback function, until the fluid is filled. , When the flow rate is 0, the temperature of the medium is controlled to a predetermined temperature by the temperature alarm via the steam regulating valve, switching valve, and cooling water solenoid valve, and when the fluid is not flowing and when the fluid starts flowing,
An automatic temperature control method for a heat exchanger, characterized in that the fluctuation in fluid temperature is controlled to approximately ±2°C at each time of switching from sequence control to automatic temperature controller control.