JPH03190902A - Reaction temperature control of reactor - Google Patents

Abstract

PURPOSE:To efficiently control reaction temperature by making a reaction temperature adjuster regulate a flow rate of refrigerant by a function calculator to increase and reduce a change ratio depending upon output of reaction temperature detector and letting a raw material temperature adjuster control a flow rate of refrigerant by output of a raw material temperature detector. CONSTITUTION:Raw materials are fed through a preheater 6 to a reaction tank 22 equipped with a cooling jacket 2, reacted, reaction temperature in the reaction tank 22 discovered by a reaction temperature detector 19 is inputted to a function calculator 5, a signal to increase a change rate by rise in reaction temperature is outputted, the outputted signal is multiplied by the reaction temperature by a reaction temperature regulator 20 having inputted the signal and outputted to regulate a flow rate of refrigerant. A first coefficient subtractor 1 having inputted reaction temperature outputted from the reaction temperature detector 19 subtracts given temperature from the reaction temperature and outputs the difference. A signal regulator 2 having inputted the deviation signal outputs a compensation signal proportional to the deviation signal only when the deviation signal is positive, a second coefficient subtractor 3 having inputted the outputted compensation signal outputs a set value of compensation, inputted to a raw material temperature adjuster 13 and a flow rate of refrigerant is regulated to control the reaction temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a reaction temperature control method for a reaction device that involves an exothermic reaction, such as a polystyrene polymerization reaction device.

[Conventional technology]

A conventional reaction temperature control method for a reactor will be explained using an example of a polystyrene polymerization reactor shown in FIG.

In FIG. 3, a raw material mixture (styrene monomer, recovered monomer, ethylhenzene, catalyst solution, etc.) is supplied from a pipe 25 via a preheater 6 to a reaction tank 22 provided with a cooling jacket 23. The polymer liquid reacted in the reaction tank 22 after the polymerization reaction is taken out to the outside of the yarn through the pipe 7. The temperature of the raw material solution at the outlet of the preheater 6 is detected by a raw material temperature detector (thermometer) 12, and this detected value is input to a raw material temperature controller 13, which has the detected value set in advance. The operating output is output to the control valve 14 so that the set temperature is reached. Therefore, the opening degree of the control valve 14,
That is, the heat medium flow rate of the preheater 6 is changed according to the operational output of the controller 13. Through the functions of each of the above-mentioned devices, the temperature of the raw material solution at the outlet of the preheater 6 is stably maintained at a predetermined value, and conditions are provided to the reaction tank 22 to enable stable operation.

In order to maintain the polymerization rate of the polymer liquid (polystyrene) after the reaction in the reaction tank 22 at a desired value, the temperature of the polymer liquid (reaction temperature) in the reaction tank 22, which is correlated with the polymerization rate, is controlled to a predetermined value. The mechanism is as follows. The reaction temperature in the reaction tank 22 is measured by the reaction temperature detector 19.
Detected by This detection signal is detected by the reaction temperature controller 20.
The reaction temperature controller 20 compares it with the reaction temperature set value, and so that the two match, the reaction temperature controller 20 gives its output to the refrigerant temperature controller 16 as the refrigerant temperature set value. The refrigerant temperature controller 16 calculates a correction signal to make the refrigerant temperature detected by the refrigerant thermometer 15 equal to the refrigerant temperature set value outputted by the reaction temperature controller 20, and sends a correction signal to the piping 8 that supplies hot oil as a refrigerant. A calculated value is output via the function calculator 21 to both the installed control valve 17 and the control valve 18 installed in the pipe 9 that also supplies cold oil, which is a refrigerant. Said control valve 17.1
8, the opening degree is adjusted by the two calculated values, and the flow rates of the oil and cold oil are adjusted, respectively. The hot oil and cold oil, which are the refrigerants whose flow rates have been adjusted, pass through the supply pipe 89, join together at the supply pipe 10, and are supplied to the jacket 23, and are then supplied to the reaction tank 2 at Jakela I/23.
After cooling 2, the pipe 11 leads to the outside of the thread. The function calculator 21 is for operating the control valves 17 and 18 in a split range according to the output of the refrigerant temperature controller 16, and a setting example is shown in FIG. Output 5 of refrigerant temperature controller 16
Control valve 17 in the range of 50% to 100% with 0% as the border
The opening degree of the control valve 18 is operated from 0 to 100%, and in the range from 0 to 50%, the opening degree of the control valve 18 is operated from 100 to 0%. By doing this, in a region where the output of the refrigerant temperature controller 16 is 50% or more, the flow rate of the high temperature Hola I/oil increases (the amount of cooling decreases) in accordance with the increase in the output of the refrigerant temperature controller 16. . Output of refrigerant temperature controller 16 is 50%
In the following range, the flow rate of low-temperature cold oil increases (the amount of cooling increases) in accordance with the decrease in the output of the refrigerant temperature controller 16. Therefore, the cooling amount is changed almost continuously according to the output of the refrigerant temperature controller 16.

Since each device operates as described above, for example, if the reaction temperature rises due to some disturbance during steady operation, the reaction temperature controller 20 acts on the refrigerant temperature controller 16 to decrease the refrigerant temperature set value.

The refrigerant temperature controller 16 reduces the output of the refrigerant temperature controller 16 in order to match the output of the thermometer 15 with the refrigerant temperature set value, and when the output of the refrigerant temperature controller 16 at that time is in the region of 50% or less, increases the opening degree of the control valve 18 in order to increase the cold oil flow rate. As a result of the above, the refrigerant temperature (output of the thermometer 15) decreases, the amount of cooling increases, and the rise in reaction temperature is suppressed.

Contrary to the above, when the reaction temperature is about to drop, the reaction temperature controller 20 increases the refrigerant temperature set value, the refrigerant temperature controller 16 decreases the opening degree of the control valve 18 to increase the output, and the cold oil flow rate increases. decreases (refrigerant temperature controller 16
(in the area where the output is less than 50%). Since the amount of cooling is reduced as described above, the drop in reaction temperature is suppressed.

[Problem to be solved by the invention]

What is important in a polymerization reactor is to appropriately maintain the reaction temperature at a predetermined value. However, in conventional apparatuses, although the polymerization reaction of polystyrene is accompanied by high temperature heat generation, the viscosity of the polymerization liquid is high, so a large heat transfer coefficient cannot be achieved, resulting in large operational delays. With these,
There was a risk that the fluctuations in the reaction temperature would increase, or the control system would not be able to follow the fluctuations in the reaction heat, leading to a runaway reaction.

The present invention is intended to solve the above-mentioned problems, to minimize fluctuations in reaction temperature, and to eliminate production of defective products due to runaway reactions, as well as plant shutdowns.

1. Means for Solving the Problems] In the reaction temperature control method for a reaction apparatus of the present invention, a raw material is supplied via a preheater to a reaction tank equipped with a cooling jacket 1-, and a reaction temperature detector detects the temperature. The reaction temperature controller inputting the reaction temperature in the reaction tank controls the flow rate of the refrigerant supplied to the cooling jacket marked -1°, and the raw material temperature detected by the raw material temperature detector is recorded at the preheater outlet [1]. In a reaction device in which a feedstock temperature controller controls the heat medium flow rate to adjust the feedstock temperature, a function calculator inputs the reaction temperature output from the reaction temperature detector described in 1-6 and calculates the increase in reaction temperature. The reaction temperature controller that inputs the signal outputs a signal in which the rate of change increases, and the reaction temperature controller multiplies the reaction temperature by the signal indicated by - and outputs it to control the refrigerant flow rate. The first coefficient H)? ] The device subtracts a predetermined temperature from the reaction temperature and outputs the same, and the signal limiter inputting the same deviation signal outputs a correction signal proportional to the same deviation signal only when the deviation signal is iE, and inputs the same correction signal. The second coefficient subtracter outputs the corrected set value and inputs it to the raw material temperature controller to control the heat medium flow rate.

[Effect]

In the above, when the reaction temperature in the reaction tank increases, the reaction temperature output from the reaction temperature detector is input to the function calculator, and the function calculator increases the rate of change as the reaction temperature increases. Output a signal.

The output signal of the functional calculator is input to a reaction temperature controller, which outputs a signal obtained by multiplying the reaction temperature by the output signal to control the refrigerant flow rate. Since the above controller outputs a signal multiplied by the output signal of the functional calculator, the rate of change of the output signal increases as the reaction temperature increases, and the refrigerant flow rate increases as the reaction temperature increases. The cooling effect is enhanced.

The reaction temperature output by the reaction temperature detector is input to the first coefficient subtracter, and the subtracter outputs a deviation signal obtained by subtracting a predetermined temperature from the reaction temperature and inputs it to the signal limiter. When the deviation signal is positive, the device outputs a correction signal proportional to the deviation signal and inputs it to the second coefficient subtracter, and the subtracter outputs the corrected set value and inputs it to the raw material temperature controller. The raw material temperature controller controls the heat medium flow rate, and the raw material temperature decreases in accordance with the reaction temperature.

In contrast to the above, when the reaction temperature decreases, the rate of change output by the functional calculator decreases, so that the decrease in the refrigerant flow rate is suppressed to a small extent.

Regarding the heat medium flow rate, if the reaction temperature is below a predetermined temperature, the signal limiter will not output a correction signal.
Controlled regardless of reaction temperature.

According to L, when the reaction temperature rises, the refrigerant supplied to the jacket and the heating medium supplied to the preheater will greatly increase the cooling effect, and when the reaction temperature decreases, the refrigerant supplied to the jacket will slightly reduce the cooling effect. This makes it possible to reduce fluctuations in reaction temperature, and when producing polystyrene, etc., it is possible to achieve uniform quality, and it is also possible to prevent the production of defective products and plant shutdowns due to runaway reactions. Become.

〔Example〕

An embodiment of the present invention is shown in FIG.

In the wooden embodiment shown in FIG. The oil and the cold oil supplied through the pipe 9 join together in the pipe 10, are supplied to the cooling jacket 23, cool the reaction tank 22, and are discharged through the pipe 11, and the raw material temperature at the outlet of the preheater 6 is changed to the raw material temperature. The detector 12 detects the temperature and inputs it to the raw material temperature controller 13, which controls the amount of heat medium supplied to the preheater 6 via the control valve 14, and adjusts the temperature of the reaction tank 22 to the reaction temperature. The temperature detected by the detector 19 is inputted to the refrigerant temperature controller 16 via the reaction temperature controller 20, and the refrigerant temperature controller 16 inputs the temperature of the refrigerant flowing through the pipe 10 detected by the refrigerant thermometer 15, and performs a function calculation. In a reaction apparatus that controls the openings of the regulating valve 17 provided in the piping 8 and the regulating valve provided in the piping 9 during the day via the reactor 21, the output signal of the reaction temperature 0 detector 19 is inputted. a function calculator 5 that inputs an output signal to the reaction temperature controller 20; a first signal setter 4a that outputs a preset predetermined temperature; The first step is to input a predetermined temperature from the container 4a and subtract the predetermined temperature from the reaction temperature.
coefficient subtractor 1, signal limiter 2 which inputs the deviation signal from the subtracter 1, outputs zero if it is negative and outputs a signal equal to the input if it is a positive value, and preheating in steady state. a second signal setting device 4 that outputs the set value of the temperature of the device 6;
In this embodiment, the output signals from the signal limiter 2 and the second signal setting device 4 are input, and the output temperature of the preheater 6 is input. Subtractor 3, 1st. The operations of devices other than the second signal setters 4a, 4 and the function calculator 5 are the same as in the prior art, and therefore their explanation will be omitted.

In the above, when the reaction temperature rises due to some disturbance during steady operation, the output of the function calculator 5 increases as shown in FIG. 2 in accordance with the increase in the output of the reaction temperature detector 19.
In order to multiply and correct the proportional key of the reaction temperature controller 20,
The reaction temperature controller 20 outputs a significantly lower correction signal than the conventional method to the refrigerant temperature controller 16 as a set value. Therefore, the refrigerant temperature controller 16 significantly increases the opening of the control valve 18 more quickly than in the past, and increases the amount of cooling (when the output of the refrigerant temperature controller 16 is in the range of 50% or less).

In addition, the reaction temperature detector 19 inputs the reaction temperature to the first coefficient subtracter 1, and the subtracter 1 inputs a predetermined temperature from the first signal setting device 4a and subtracts the predetermined temperature from the reaction temperature. The deviation signal is input to the signal limiter 2, and only when it is positive, the deviation signal is given to the second coefficient subtracter 3, and the coefficient subtracter 3 uses the set value input from the second signal setter 4. The two deviation signals are subtracted and output, and the output (setting value of the raw material temperature controller 13) decreases, and the raw material temperature controller 13 makes the output of the raw material temperature detector 12 and the coefficient subtracter 3 equal. The opening degree of the control valve 14 is decreased to adjust the diluent flow rate. Therefore, the temperature of the raw material mixture to the reaction tank 22 decreases, the amount of heat input to the reaction tank decreases, and the reaction temperature is prevented from rising too much.

The above operation keeps the rise in reaction temperature to a slight level.

2, when the reaction temperature is decreasing, the set value input to the refrigerant temperature IQiJ 1Ifj total 16 increases slightly compared to the conventional method, and the opening degree of the control valve 18 increases slightly compared to the conventional method. The amount of cooling is reduced to provide an appropriate amount of cooling. Further, when the reaction temperature is below a predetermined temperature, the signal limiter 2 outputs zero, so the preheating of the raw material by the preheater 6 is performed at a temperature that is not affected by changes in the temperature output by the reaction temperature detector 19. It will be done.

These effects keep the downward fluctuations in reaction temperature to a minimum.

The above embodiment focuses on the fact that the process characteristics vary depending on the reaction temperature, which is the main reason why the reaction temperature in the reaction tank 22 is difficult to control.

Specifically, as the reaction temperature increases, the amount of heat generated also increases. That is, as the reaction temperature increases, the reaction rate (k: moff/r
rt'·h) increases. In addition, the calorific value q (kcaρ
/bo・h) and the reaction rate have a relationship shown in equation (1).

Therefore, as the reaction temperature increases, the exothermic Mq also increases.

q oc k−ΔH−−−−−−−−−−1111−−−−−−−−−−−−−(111However, ΔH(kca
17moff) is the reaction heat In order to take advantage of this process characteristic and effectively control the reaction temperature, when the reaction temperature rises, the amount of cooling is increased more quickly than when it falls, to ensure the necessary amount of cooling, and then the reaction temperature is lowered. When the temperature rises, the cooling amount is reduced by a small amount compared to when the temperature rises, thereby ensuring an appropriate cooling amount that does not cause fluctuations in the reaction temperature due to excessive throttling.

In addition, fluctuations in the reaction temperature of the reaction tank 22 are monitored, and if the reaction temperature is in a region exceeding a predetermined value, the calorific value increases,
Since there is a possibility that the reaction temperature may rise, in order to suppress this, the temperature of the raw material mixture to the reaction tank 22 (the setting value of the preheater 6 and the raw material temperature controller 13) is adjusted in proportion to the fluctuation of the reaction temperature. This is to reduce the amount of heat input into the reaction tank 22 and stabilize it thermally.

-1- allows for less fluctuation in the reaction temperature of the reaction tank (
Polystyrene of uniform quality can be obtained. In addition, production of defective products and plan 1 stoppage due to runaway reactions are eliminated, and a decrease in operating rate due to plant stoppage and recovery operations can be prevented.

〔Effect of the invention〕

The temperature control method for a reaction apparatus of the present invention is such that the flow rate of the refrigerant for cooling the reaction tank is made to correspond to the output of a function calculator whose rate of change increases or decreases according to changes in the reaction temperature, and the flow rate of the heat medium for heating the raw materials is made to correspond to the output of a function calculator whose rate of change increases or decreases according to changes in the reaction temperature. is supplied to the jacket only when the reaction temperature exceeds a predetermined temperature by controlling it with a set value corrected by a deviation signal obtained by subtracting the predetermined temperature from the reaction temperature. The refrigerant supplied to the jacket and the heating medium supplied to the preheater greatly enhance the cooling effect, and when descending, the refrigerant supplied to the jacket slightly stops the cooling effect, making it possible to reduce fluctuations in reaction temperature. When producing polystyrene etc.
Uniform quality can be achieved, and it is also possible to prevent production of defective products and stoppage of Plan 1 due to runaway reactions.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an embodiment of the present invention, Fig. 2 is a characteristic diagram of a functional arithmetic unit used in the above embodiment, Fig. 3 is an explanatory diagram of a conventional method, and Fig. 4 is an explanatory diagram of the above conventional method. It is a characteristic diagram of the refrigerant temperature controller in . 1... Coefficient subtractor, 2-6... Preheater, 7.8, 9, 10.11... Piping, 12... Raw material temperature detector, 13... Raw material temperature controller, 14 ...Control valve, 15.Refrigerant thermometer, 16.
...Refrigerant temperature controller, 17.18...Control valve, 19...Reaction temperature detector, 20...Reaction temperature controller, 21...Function calculator, 22...Reaction tank, 23・・・
- Cooling jacket. 7 84 countries rθ0 16 nail powers and phrases that are 1 nail exposed

Claims (1)

[Claims] Raw materials are supplied to a reaction tank equipped with a cooling jacket via a preheater, and a reaction temperature controller inputting the reaction temperature in the reaction tank detected by a reaction temperature detector is supplied to the cooling jacket. In a reactor that controls a heat medium flow rate, a feed temperature controller that controls the refrigerant flow rate and inputs the feedstock temperature at the outlet of the preheater detected by the feedstock temperature detector adjusts the feedstock temperature. A function calculator inputs the reaction temperature and outputs a signal whose rate of change increases as the reaction temperature increases, and a reaction temperature controller that inputs that signal multiplies the reaction temperature by the above signal and outputs it. A first coefficient subtracter that controls the refrigerant flow rate and inputs the reaction temperature outputted by the reaction temperature detector subtracts a predetermined temperature from the reaction temperature and outputs the result, and a signal limiter inputs the same deviation signal. Only when the above deviation signal is positive, a correction signal proportional to the deviation signal is output, and the second coefficient subtracter which inputs the correction signal outputs the corrected setting value and inputs it to the raw material temperature controller. A method for controlling a reaction temperature of a reactor, the method comprising controlling the flow rate of a medium.