JPH03190901A - Reaction temperature control of reactor - Google Patents

Abstract

PURPOSE:To efficiently control reaction temperature by making a change rate calculator operate by a signal of a function calculator to increase and reduce a change ratio depending upon reaction temperature discovered by a reaction temperature detector and making a reaction temperature adjuster add judgment by a sign determining device to regulate flow rate of refrigerant. CONSTITUTION:Reaction temperature of a reaction tank 22 equipped with a cooling jacket 23 is discovered by a reaction temperature detector 19, the detected temperature 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, a change rate of reaction temperature is outputted by a change rate calculator 1 having inputted reaction temperature outputted from the reaction temperature detector 19, a sign determining device 2 having inputted the outputted change rate outputs a signal proportional tp the change rate only when the change rate is positive, the signal is inputted to the the reaction temperature calculator 20, added and a flow rate of refrigerant is regulated to control the reaction temperature of reactor.

Description

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

[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, ethyl henzene, catalyst solution, etc.) is supplied from a pipe 25 via a preheater 6 to a reaction tank 22 equipped with a cooling jacket 1-23. 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 manually input to a raw material temperature controller 13, where the detected value is preset. 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 flow rate of the heat medium of the preheater 6, is changed according to the operation 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.
Conditions that enable stable operation of the reaction tank 22 are provided.

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, must be kept at a predetermined value. It needs to be controlled, and 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. ”-Regulating valve 17.
The opening degree of 18 is adjusted based on the above-mentioned calculated value, and the flow rates of hot oil and cold oil are adjusted respectively. 2. Pot oil and cold oil, which are 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 fed to the jacket 23 at the reaction rod 1.
22 is cooled down, the pipe T1 leads to the outside of the thread. The function calculator 21 is used to operate the control valves 7 and 18 in a split range according to the output of the refrigerant temperature controller 16, and a setting example is shown in FIG. 4.Refrigerant temperature controller 16 With the output of 50% as the boundary, the opening degree of the control valve 17 is operated from 0 to 100% in the range of 50% to 100%, and the opening degree of the control valve 18 is operated from 100 to 0% in the range of 0 to 50%. By doing this, the refrigerant temperature controller 16
In the second region where the output of the refrigerant temperature controller 16 is 50% or more, the flow rate of high temperature hot oil increases (the amount of cooling decreases) in accordance with the increase in the output of the refrigerant temperature controller 16. The output of the refrigerant temperature controller 16 is 5
In the region below 0%, 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 control IT 1.6. Therefore, refrigerant temperature controller 1
The system is designed to change the amount of cooling almost continuously according to the output of 6.

Since each device operates as described in , 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 fear that either the fluctuations in reaction temperature would increase or the control system would not be able to follow the fluctuations in 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 Plan I stoppages.

[Means to solve the problem]

In the reaction temperature control method of the reaction apparatus of the present invention, a reaction temperature detector detects the reaction temperature of a reaction tank equipped with a cooling jacket I, and the reaction temperature is input from the reaction temperature detector. In a reaction apparatus in which a reaction temperature controller controls the flow rate of refrigerant supplied to a 2L cooling jacket,
A function calculator inputs the reaction temperature output by the reaction temperature detector and outputs a signal whose rate of change increases as the reaction temperature increases, and the reaction temperature controller that inputs that signal changes the reaction temperature to the above signal. In addition, the rate of change calculator that inputs the reaction temperature output from the reaction temperature detector outputs the rate of change of the reaction temperature, and the sign/negative determiner that inputs the same rate of change determines whether the rate of change is positive. A signal proportional to the rate of change is output only when the reaction temperature controller is input and added to the reaction temperature controller to control the refrigerant 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 source 'g', and the function calculator calculates the rate of change with respect to the increase in reaction temperature. Outputs an increasing signal.

The output signal of the function calculator is input to the reaction temperature controller, where the reaction temperature is multiplied by the distribution output signal. In addition, a rate-of-change calculator that manually calculates the reaction temperature from the reaction temperature detector outputs the rate of change in the reaction temperature, which is input to the reaction temperature controller via the sign/negative determiner. The reaction temperature controller performs an operation in which the proportional operation, integral operation, and differential operation are added according to signals manually inputted from the function calculator and the +'E fl-determiner to control the refrigerant flow rate.

Since the Kitaki controller performs an operation that is a combination of proportional action, integral action, and differential action, the refrigerant flow shown in I-1 increases cumulatively as the reaction temperature increases (-1 and increases as the reaction temperature increases). It responds quickly and has an enhanced cooling effect.

In contrast to the above, if the reaction temperature drops by one, FE
i4+, there is no output from the determiner, and the rate of change output from the function calculator decreases, so the decrease in the refrigerant flow rate is suppressed to a small extent.

As a result of the above, when the reaction temperature increases by -L, the cooling effect of the refrigerant supplied to the jaguget is greatly enhanced, and when it decreases, the cooling effect is slightly reduced to 1, thereby reducing fluctuations in the reaction temperature. When polystyrene or the like is produced, it is possible to achieve uniform quality, and it is also possible to prevent the production of defective products and stoppage of Plan 1 due to runaway reactions.

〔Example〕

An embodiment of the present invention is shown in FIG.

In the present embodiment shown in FIG.
The raw material is supplied and discharged through piping 7, and the bond oil supplied through piping 8 and the cold oil supplied through piping 9 join together in piping 10, and are supplied to the cooling jacket 23 to form a reaction tank. 22 and pipe 11
The raw material temperature at the outlet of the preheater 6 is detected by the raw material temperature detector 12 and inputted to the raw material temperature detector 13.
The controller 13 controls the amount of heat medium supplied to the preheater 6 via the control valve 14, and the reaction temperature detector 19 detects the temperature of the reaction tank 22, and the temperature is detected via the reaction temperature controller 20. The temperature of the refrigerant flowing through the pipe 10 detected by the refrigerant thermometer 15 is inputted to the refrigerant temperature controller 16, and the temperature of the refrigerant flowing through the pipe 10 detected by the refrigerant thermometer 15 is input to the refrigerant temperature controller 16. Control valve 7 provided in the pipe 9 and control valve 1 provided in the piping 9
8, a function calculator 5 inputs the output signal of the reaction temperature detector 19 and manually inputs the output signal to the reaction temperature controller 20;
A rate-of-change calculator 1 inputs the reaction temperature detected by 9 and calculates the rate of change of the reaction temperature 7, and a rate-of-change calculator 1 manually calculates the rate of change from the calculator 1 and outputs it only when it is positive to the reaction temperature controller 20. It is equipped with a sign/negative determiner 2 that performs a differential operation.

In this embodiment, a change rate calculator 1, a positive/negative determiner 2,
The operations of devices other than the function calculator 5 are the same as in the prior art, and therefore their explanations will be omitted.

-, 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,
The proportional gain of the reaction temperature controller 20 is multiplied and corrected. In addition, the rate of change calculator 1, which inputs the reaction temperature from the reaction temperature detector j9, outputs the rate of change of the reaction temperature and inputs it into the positive/negative determiner 2. The reaction temperature controller 20 performs an operation in which the proportional operation, integral operation, and differential operation are added based on the signals input from the function calculator 5 and the positive/negative judger 2, which is faster than the conventional method. A large decrease correction signal is output to the refrigerant temperature controller 16 as a set value. Therefore, the refrigerant temperature controller 16 significantly increases the opening degree 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 region of 50% or less).

Due to the above operation, fluctuations in the rise in reaction temperature are kept to a minimum.

In contrast to the above, when the reaction temperature is decreasing, the set value input to the refrigerant temperature controller 16 will increase slightly compared to the conventional method because only the signal from the function calculator 5 is input, and the control valve The opening degree of No. 18 is slightly reduced compared to the conventional one, and an appropriate amount of cooling is provided. This keeps the drop in reaction temperature to a minimum.

Note: This embodiment focuses on the fact that the process characteristics differ depending on the reaction temperature as the main reason why the reaction temperature in the reaction tank 22 is difficult to control.

Specifically, as the reaction temperature rises, the amount of heat generated also increases. That is, as the reaction temperature increases, the reaction rate (k: mol, /r
r(-h) increases. In addition, the calorific value, ' Q (kc
There is a relationship between a E/, (·h) and the reaction rate as shown in equation (1).

Therefore, as the reaction temperature increases, the calorific value q also increases.

qock・△H----------------------
111---(1) However, 8H (kcal/mo(2
) is the reaction heat.In order to take advantage of this process characteristic and control the reaction temperature well, when the reaction temperature rises, the amount of cooling must be increased more quickly and more frequently than when it falls, to ensure the necessary amount of cooling, and to reduce the temperature. Sometimes, the amount of cooling is reduced by a small amount compared to when the temperature is increased to maintain an appropriate level of cooling that will not cause fluctuations in the reaction temperature due to excessive throttling.

In addition, the rate of change in the reaction temperature of the reaction tank 22 is monitored, and when the rate of change is positive (increase), the amount of cooling is increased early according to the rate of change in the reaction temperature by the differential operation of the reaction temperature controller. (decrease), no operation is performed, the amount of cooling is suppressed, and good control that is compatible with the process can be performed.

As a result of the above, fluctuations in the reaction temperature of the reaction tank are reduced and polystyrene of uniform quality can be obtained. It also eliminates the production of defective products and plant shutdowns due to runaway reactions.
It is possible to prevent a decrease in the operating rate due to plant stoppages and restoration operations.

〔Effect of the invention〕

The temperature control method for a reaction apparatus of the present invention uses an output signal from a function calculator whose rate of change increases or decreases according to changes in the reaction temperature, and a rate of change of the reaction temperature from a rate-of-change calculator to determine the flow rate of refrigerant for cooling the reaction tank. By controlling by the output signal of the positive/negative determiner which inputs and outputs it when the reaction temperature is positive, the cooling effect of the refrigerant supplied to the jacket increases significantly when the reaction temperature increases, and decreases when the reaction temperature decreases. Since the effect is kept to a small level, it is possible to reduce fluctuations in reaction temperature, and when producing polystyrene, etc., it is possible to achieve uniform quality, and it also prevents the production of defective products and plant shutdowns due to runaway reactions. becomes possible.

[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 . ■... Change rate calculator, 2... Positive/negative judge, 5...
...Function calculator, 6...Preheater, 7 8.9.10
．． DESCRIPTION OF SYMBOLS 11... Piping, 12... Raw material temperature detector, 13... Raw material temperature controller, 14... Control valve, 15... Refrigerant thermometer, 16.
...Refrigerant temperature controller, 1718...Control valve, 19...Reaction temperature detector, 20...Reaction temperature controller, 21...Function calculator, 22...Reaction tank, 23...
- Cooling jacket. 3 4 Corner 4 Ward-6-

Claims (1)

[Claims] A reaction temperature detector detects the reaction temperature of a reaction tank equipped with a cooling jacket, and a reaction temperature controller that receives the reaction temperature from the reaction temperature detector controls the flow rate of refrigerant supplied to the cooling jacket. In the reaction apparatus, a function calculator inputs the reaction temperature output from the reaction temperature detector and outputs a signal whose rate of change increases as the reaction temperature increases. The temperature is multiplied by the above signal, and the rate of change calculator inputting the reaction temperature output from the reaction temperature detector outputs the rate of change of the reaction temperature, and the sign/negative determiner inputting the same rate of change calculates the rate of change. 1. A reaction temperature control method for a reaction apparatus, comprising: outputting a signal proportional to the rate of change only when is positive, and inputting and adding the signal to the reaction temperature controller to control the flow rate of the refrigerant.