JP2001125650A - Tank temperature control method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dynamically control the temperature in a tank without complicating a mechanism. SOLUTION: A control part 18 performs temperature control by opening and closing a heating valve 13 and a cooling valve 14 according to in-tank temperature information from a temperature measuring instrument 15. Here, C1=m/M and C2=qi/m, where Tk is a measured value of in-tank temperature, SV is a target value of the in-tank temperature, ΔTk is the rate of variation in the temperature in the tank, M is the heating capacity of the tank, (m) is the heat capacity of a thermostatic chamber, qi is supply heating value, and K is the heat conductivity of the tank. In quick heating, the heating valve 13 is fully closed once a conditional expression C1.(1-ΔTk/C2).ΔTk+Tk>=SV is satisfied. Then the temperature Tk in the tank is made to gradually approach the target value SV thereafter under fixed-temperature control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the internal temperature of a tank accompanying a rise or fall in temperature in the production of photosensitive materials used in photographic films and related materials.

[0002]

2. Description of the Related Art In a device for controlling the internal temperature of a tank storing a liquid, a value immediately before a target temperature is set in advance in order to prevent an overshoot that may occur near the end of heating and cooling. When the internal temperature reaches this set value, the control state is automatically shifted. Also, in the invention disclosed in Japanese Patent Application Laid-Open No. 10-3320, a method is proposed in which a deviation value between a measured temperature inside a tank and a target temperature is calculated, and the control method is changed based on the result.

[0003]

In the above method, since the number of parameters required for performing temperature control is large,
The temperature control mechanism itself tends to be complicated. Also,
For each control method, it is necessary to derive the optimum value of the parameter, which imposes a burden on parameter conditions.

In the above method, the optimum values of the parameters are derived on the assumption that the type and volume of the liquid in the tank are constant, and the method is adapted to the case where the state of the system changes dynamically. Not. For this reason, it is necessary to change the state of the system in various ways and to incorporate the optimum values of the parameters in each state in advance.

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and provides a method and apparatus for controlling a tank temperature which can dynamically control the temperature in the tank without complicating the mechanism. With the goal.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, a physical analysis was conducted on the change in the tank internal temperature.
As shown in the heat conduction model of FIG. 1, a model in which a heat quantity of qi is added to a constant temperature bath (temperature Tb) having a heat capacity of m and a heat quantity of qc is transmitted to a tank (temperature Tk) having a heat capacity of M through a heat transfer surface. Assume.

The equation for the heat balance in a thermostat is as follows. Tb ′ = (qi−qc) / m (1) qc = K · (Tb−Tk) (2) where Tb ′ is the first-order time derivative of Tb, and K is the tank time. It represents the thermal conductivity. On the other hand, the equation of the heat balance in the tank is as follows. Tk '= qc / M (3)

From equations (1) to (3), the following equation is obtained by eliminating qc. m · Tb ′ = qi−K · (Tb−Tk) (4) M · Tk ′ = K (Tb−Tk) (5) By transforming this equation (5), the equation (6) becomes can get. Tb = (M / K) · Tk ′ + Tk (6) By time-differentiating both sides of the equation (6), the equation (7) is obtained. Tb ′ = (M / K) · Tk ″ + Tk ′ (7) Here, Tk ″ represents a second-order time derivative of Tk. By substituting equation (7) into equation (4), a tank heat equation represented by the following equation is obtained. (M · M / K) · Tk ″ + (M + m) · Tk′−qi = 0 (8)

When equation (8) is analytically solved for Tk,
The following solution is obtained. Tk (t) = Tk0 + A ・ ΔTk0 ｛{1-exp (−t / A)} + qit ・ / (M + m) (9) In the above equation, Tk0 is the initial value of the tank temperature at t = 0. And ΔTk0 represents the rate of change in the tank temperature at t = 0. A is the tank temperature time constant represented by A = M · m / {K · (M + m)} (10)

When the heating time has sufficiently passed, the equation (9)
Exp (−t / A) = 0 (11) To the time derivative of both sides of equation (9),
By substituting equation (11), Tk ′ = qi / (M + m) (12) By selecting this time point as an initial value, ΔTk0 = qi / (M + m) (13) From the above equation, M = qi / ΔTk0-m (14) The tank heat capacity M is a variable parameter that changes according to the type and capacity of the liquid stored in the tank. M can be calculated from the temperature rise rate ΔTk0 by Expression (14).

Using equation (14), A in equation (10) is transformed as follows. A = M · m / {K · (M + m)} = (m / K) · (1−m · ΔTk0 / qi) (15) where, the heat transfer time constant C1 and the constant temperature bath temperature rise rate C2 Are defined as C1 = m / K (16) and C2 = qi / m (17), respectively, and the equation (15) becomes as follows. A = C1 · (1−ΔTk0 / C2) (18)

Using equation (9), the change in the tank temperature after the heating is stopped will be considered. By substituting qi = 0 into equation (9), Tk (t) = Tk0 + A · ΔTk0 · {1-exp (−t / A)} (19) FIG. 2 shows a change in Tk expressed by the equation (19). In the figure, the horizontal axis indicates time t, and the vertical axis indicates the tank temperature Tk. The time t is 0 when the heating is stopped. For this reason, Tk0 and ΔTk0 are values when heating is stopped. From the equation (19), the overshoot amount Td after the stop of the heating is as follows: Td = AＡΔTk0 = C1 ・ (1ΔΔTk0 / C2) ・ ΔTk0 (20)

As shown in FIG. 2, when the supply heat quantity qi = 0, the tank temperature becomes the overshoot quantity T with the time constant A.
It can be seen that the value approaches d. That is, by estimating the value of the overshoot amount Td and cutting off the heat supply,
It is possible to prevent the occurrence of overshoot.

The parameters required for temperature control are C1,
C2, ΔTk0, where ΔTk0 can be calculated from a measured value of the tank temperature during heating. Also, C
As is clear from Equations (16) and (17), 1, and C2 are values unique to the system, and thus can be easily derived from the test operation results.

This temperature control method is performed as follows. At the time of heating, it is determined whether or not the following condition is satisfied, and heating is performed until the condition is satisfied. C1 · (1−ΔTk / C2) · ΔTk + Tk ≧ SV (21) Here, SV is a target value of the tank internal temperature, which is a predetermined value.

When the above equation is satisfied, the heating is stopped in order to reduce the amount of supplied heat to zero. After that, the temperature control method of the thermostat is switched to the stationary control at the set temperature SV. Equation (2
Since ΔTk and Tk in 1) are values when heating is stopped, Tk gradually approaches the target value SV according to the equation (19).

The tank temperature change rate ΔTk is calculated by measuring the tank temperature every second and calculating the change amount.
It may be calculated from a moving average in 0 seconds. By calculating ΔTk from the average value of 100 change amounts, more accurate temperature control can be performed.

Further, by controlling the amount of heat qi supplied to the constant temperature bath to a constant value, the value of C2 can be kept constant irrespective of the state of the system, and more stable temperature control becomes possible.

[0019]

Embodiments of the present invention will be described below. FIG. 3 shows the structure of the tank temperature control device of the present invention. A thermostat 11 is attached around the tank 10 for raising or lowering the temperature of the liquid. Circulating water circulated by a pump 12 is sealed in the thermostatic bath 11, and the temperature of the tank 10 is controlled by heating and cooling the circulating water. A heating valve 13 for inserting high-temperature steam into the circulation path of the circulating water;
A cooling valve 14 into which low-temperature cooling water is inserted is connected, and the circulating water can be heated and cooled by opening and closing the heating valve and the cooling valve.

The tank 10 and the thermostat 11 are provided with a thermometer 1
5 and 16 are attached, and the temperature of the tank 10 and the thermostat 11 is constantly measured. Thermometer 15 on the tank side
Is provided with an arithmetic unit 17. The computing unit 17 takes in the measured value of the temperature in the tank at one-second intervals and compares the measured value with the immediately preceding measured value to calculate the amount of change. And
The moving average of the immediately preceding 100 pieces is calculated, and the temperature change rate ΔTk
To the control unit 18.

An arithmetic unit 17 and a thermometer 16 on the thermostatic chamber side are connected to the input side of the control unit 18.
And the temperature information of the thermostat 11 are input. The heating valve 13 and the cooling valve 14 are connected to the output side of the control unit 18 and determine the opening and closing amount of the valve. The control method by the control unit 18 includes three methods: a rapid heating mode in which only the heating valve 13 is fully opened, a rapid cooling mode in which only the cooling valve 14 is fully opened, and a constant temperature control mode in which the temperature of the thermostat 11 is kept constant. is there.

In the rapid heating mode, the control unit 18 determines the temperature information from the arithmetic unit 17 and C1 and C2 determined during the test operation.
The following calculation is performed from the above parameters and the predetermined target value SV to calculate the mode switching temperature T. T = SV−C1 · (1−ΔTk / C2) · ΔTk (22) By comparing the mode switching temperature T calculated by the above equation with the current tank temperature Tk, Tk ≧ T ... At the moment when the conditional expression (23) is satisfied, the heating valve 13 is fully closed. On the other hand, in the rapid cooling mode, the cooling valve 14 is fully closed at the moment when the following conditional expression is satisfied: Tk ≦ T (24)

In the constant temperature control mode, the control unit 18 controls the opening and closing amounts of the heating valve 13 and the cooling valve 14 based on the temperature information from the constant temperature bath 11 so that the constant temperature bath 11 is maintained at the set temperature. Adjust.

A method of controlling the temperature during heating will be described with reference to the flowchart of FIG. After measuring the temperatures of the tank 10 and the thermostat 11, the measured value Tk of the tank temperature is compared with the target value SV. The control unit 18 calculates Tk−
When it is detected that the SV is equal to or less than the predetermined value, it is determined that the temperature in the tank is sufficiently away from the target value. Then, the control unit 18 operates in the rapid heating mode, and heats the constant temperature bath 11 by fully opening only the heating valve 13.

At the time of rapid heating, the controller 18 always calculates T represented by the equation (22) based on the tank temperature information. Then, when detecting that the value of the actually measured value Tk is equal to or greater than T, the control unit 18 shifts from the rapid heating mode to the constant temperature control mode, and performs temperature adjustment so that the temperature of the constant temperature bath 11 becomes SV. At this time, when the supplied heat amount qi becomes zero and the rapid heating ends, the supplied heat amount qi becomes zero and the values of ΔTk0 and Tk0 are determined. For this reason,
The change in the tank temperature Tk after the heating is stopped is calculated by the equation (1)
9), and asymptotically approaches the target value SV without causing overshoot.

At the time when the rapid heating is completed, a timer built in the control unit 18 is operated, and the elapsed time T1 is measured thereafter. When T1 exceeds a certain value, the control unit 18 determines that the tank temperature has become substantially equal to the SV, and ends the temperature control.

In the above embodiment, the method of controlling the temperature at the time of heating has been described. However, the temperature can be controlled similarly at the time of cooling.

Although the above embodiment has been described with the supplied heat quantity qi being constant, the temperature control method of the present invention can be used even when the value of qi is not constant and changes with time. In this case, since the parameter C2 fluctuates according to the equation (17), it is necessary to provide a device for measuring and controlling the supplied heat amount qi, and to connect the device to the control unit 18 to perform temperature control.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the tank temperature control device of the present invention will be described below. In the present embodiment, a process is performed in which the low-temperature additive liquid is added 200 (L) at a time while controlling the tank temperature to 30 ° C. Before the process, make a trial run,
The values of the parameters C1 and C2 are defined as C1 = 8.0 (min) and C2 = 50.0 (° C./min).

FIG. 5 shows the changes over time in the tank temperature, the temperature of the thermostatic chamber, and the temperature output of the thermostat set temperature. Immediately after the start of the process, the apparatus operates in the constant temperature control mode. However, when the temperature of the tank is reduced by adding the additive liquid, the mode is shifted to the rapid heating mode. At this time, the mode switching temperature is constantly calculated by performing the calculation according to the equation (22). When the amount of liquid in the tank is 2000 (L), at time A, the mode switching temperature matches the temperature in the tank at 26.7 ° C., and the mode shifts from the rapid heating mode to the constant temperature control mode. When the liquid volume in the tank is 2200 (L), the mode switching temperature matches the temperature in the tank at 27.5 ° C. at time A, and the mode shifts from the rapid heating mode to the constant temperature control mode. Approaches 30 ° C.

[0031]

As described above, according to the present invention,
Since the amount of overshoot is predicted by physically analyzing the temperature change in the tank, dynamic temperature control can be performed simply and efficiently.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a heat conduction model of a tank.

FIG. 2 is an explanatory diagram showing a time change of a temperature in a tank.

FIG. 3 is a configuration diagram of a tank temperature control device.

FIG. 4 is a flowchart illustrating a temperature control method during heating.

FIG. 5 is a graph showing a temperature change in the tank in the embodiment of the tank temperature control device of the present invention.

[Explanation of symbols]

 Reference Signs List 10 tank 11 constant temperature bath 13 heating valve 14 cooling valve 17 arithmetic unit 18 control unit

Claims (4)

[Claims] 1. A tank temperature control method for adjusting a temperature in a tank by heating and cooling a constant temperature bath provided around the tank according to an internal temperature of the tank for storing a liquid. Is the actual measured value of Tk, the target value of the tank temperature is SV, the change rate of the tank temperature is ΔTk, the heat capacity of the tank is M, the heat capacity of the constant temperature bath is m, the heat supply amount is qi, and the heat conductivity of the tank is K, Assuming that C1 = m / M and C2 = qi / m, the amount of heat supplied to the constant temperature chamber is set to zero when the condition of C1 · (1−ΔTk / C2) · ΔTk + Tk ≧ SV is satisfied during rapid heating, and When the condition of C1 · (1−ΔTk / C2) · ΔTk + Tk ≦ SV is satisfied during cooling, the amount of heat supplied to the constant temperature bath is set to zero, thereby causing an overshoot in the tank temperature during heating and cooling. Prevent Tank temperature control method according to claim Rukoto. 2. A thermostat provided around a tank in which a liquid is stored; a thermometer for measuring an internal temperature of the tank and the thermostat; and a high-temperature steam flowing into the thermostat to form a thermostat. A heating valve for heating, a cooling valve for flowing cooling water into the thermostat to cool the thermostat, and a thermometer connected to the thermometer, from the temperature of the tank and the thermostat,
A control unit for adjusting the opening and closing amounts of the heating valve and the cooling valve, wherein the measured value of the temperature in the tank is Tk, the target value of the temperature in the tank is SV, the temperature change rate in the tank is ΔTk, and the heat capacity of the tank is M If the heat capacity of the thermostatic chamber is m, the amount of heat supplied is qi, and the thermal conductivity of the tank is K, and C1 = m / M and C2 = qi / m, C1 · (1−ΔTk / C2) · The heating valve is fully closed when the condition of ΔTk + Tk ≧ SV is satisfied, and the cooling valve is fully closed when the condition of C1 · (1−ΔTk / C2) · ΔTk + Tk ≦ SV is satisfied during rapid cooling; Thereafter, the tank temperature control device performs constant temperature control to prevent occurrence of overshoot in the tank temperature. 3. The temperature measuring device according to claim 1, wherein the temperature measuring device measures the temperature inside the tank every second, calculates a change amount thereof, and calculates a temperature change rate ΔTk in the tank from a moving average for 100 seconds. Item 3. A tank temperature control device according to Item 2. 4. The tank temperature control device according to claim 2, wherein a device that measures the amount of heat qi supplied to the constant temperature bath and a device that controls the same are connected to the control unit. .