JPH03181331A - Reaction temperature control method for reactor - Google Patents

Abstract

PURPOSE:To reduce the fluctuation of reaction temp. and to prevent the production of inferior product, etc., due to run-away reaction by sharply raising the cooling effect when the reaction temp. is rising with the coolant supplied to a jacket, and restraining the cooling effect to be in a small range when the reaction temp. is lowering. CONSTITUTION:Raw material is supplied through a preheater 6 into a reaction vessel 22 provided with a cooling jacket 23, and the reaction temp. controller 20 inputted with the reaction temp. in the reaction vessel 22 detected by a reaction temp. detector 19 controls the flow rate of coolant to be supplied to the jacket 23, and the raw material temp. controller 13 inputted with the raw material temp. detected by a raw material temp. detector 12 at the outlet of the preheater 6 controls the flow rate of heat medium by which the raw material temp. is controlled. The reaction temp. outputted from the reaction temp. detector 19 is inputted to a functional processor 5 which outputs the signal to increase the changing rate to the rise of reaction temp., and the reaction temp. controller 20 inputted with the signal outputs the value of the reaction temp. multiplied with the signal to control the flow rate of coolant. By this method, the fluctuation of reaction temp. is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reaction temperature control method for 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 beads, ethylbenzene, 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 I4,
That is, the heat medium flow rate 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, 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.
is given as an input to the reaction temperature set value by the reaction temperature controller 20, and the reaction l! is adjusted so that the two agree.
! The temperature controller 20 provides its output to the refrigerant temperature controller 16 as a refrigerant temperature set value. The refrigerant temperature controller 16 converts the refrigerant temperature detected by the refrigerant thermometer 15 into the reaction temperature controller 20.
A correction signal is calculated to make it equal to the refrigerant temperature set value outputted by the controller, and a control valve 17 installed in the pipe 8 that supplies hot oil, which is a refrigerant, and a regulator installed in the pipe 9, which also supplies cold oil, which is a refrigerant. A calculated value is output to both valves 18 via a function calculator 21. The above control valve 17
, 1B have their opening degrees adjusted by the above-mentioned calculated values, and adjust the flow of hot oil and cold oil, respectively. The hot oil and cold oil, which are refrigerants whose flow rates have been adjusted, pass through the supply pipe 8゜9, join together at the supply pipe 10, and are supplied to the jacket 23.
After cooling the fibers 2, the pipes 11 lead to the outside of the yarn. The function /ii1'u unit 21 is for operating the control valves 17' and 18 in the sprint range according to the output of the refrigerant temperature controller 16, and a setting example is shown in FIG. Refrigerant temperature controller 1
6, 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%. I try to operate it. By doing this, in a region where the output of the refrigerant temperature controller 16 is 50% or more, the refrigerant temperature controller 1
6, the flow rate of high temperature hot oil increases (the amount of cooling decreases). In a region where the output of the refrigerant temperature controller 16 is 50% or less, the flow rate of low-temperature cold oil increases (the amount of cooling increases) as the output of the refrigerant temperature controller 16 decreases. Therefore, the refrigerant temperature controller 16
The system is designed to change the amount of cooling almost continuously according to the output.

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 decreases the output of the refrigerant temperature controller 16 in order to match the output of the thermometer 15 with the refrigerant temperature color distribution setting value, and at that time, the output of the refrigerant temperature controller 16 is lower than 50%. In this case, the opening degree of the control valve 18 is increased 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. (if the output of the refrigerant temperature controller 16 is below 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. As a result, there is a risk that the fluctuations in the reaction temperature will increase or the control system will 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 reduce the lateral force of fluctuations in reaction temperature, and to eliminate the production of defective products due to runaway reactions, as well as plant stoppages.

[Means to solve the problem]

In the reaction temperature control method of the reaction apparatus of the present invention, raw materials are supplied through a preheater to a reaction tank provided with a cooling jacket, and the reaction temperature in the reaction tank detected by a reaction temperature detector is input. A temperature controller controls the flow rate of refrigerant supplied to the cooling jacket, and a raw material temperature controller that inputs the raw material temperature at the outlet of the preheater detected by the raw material temperature detector controls the flow rate of heat medium to adjust the raw material temperature. In a reaction apparatus, a function calculator inputs the reaction temperature outputted by the reaction temperature detector and outputs a signal whose rate of change increases as the reaction temperature increases, and a reaction temperature controller inputs the signal. is characterized in that the reaction temperature is multiplied by the above signal and outputted to control the refrigerant flow rate.

[Effect]

-, when the reaction temperature in the reaction tank increases, the reaction salinity output from the reaction temperature detector is input to the function calculator, and the function calculator calculates the rate of change with respect to the increase in reaction temperature. outputs a signal that increases.

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 one of the output signals to control the refrigerant flow rate. Since the above controller outputs a signal multiplied by the output signal of the function calculator, the rate of change of the output signal increases as the reaction temperature increases, and the refrigerant flow rate increases cumulatively as the reaction temperature increases. The cooling effect is enhanced.

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.

As a result of the above, when the reaction temperature rises, the refrigerant supplied to the jugget greatly increases the cooling effect, and when it falls, it is stopped slightly, making it possible to reduce fluctuations in the reaction temperature, producing polystyrene, etc. In this case, it is possible to achieve uniform quality, and it is also possible to prevent production of defective products and plant shutdowns due to runaway reactions.

〔Example〕

An embodiment of the present invention is shown in FIG.

The present embodiment shown in FIG. The oil and the cold oil supplied through the pipe 9 join together in the pipe IO, 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 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 of the refrigerant flowing through the pipe 10 detected by the refrigerant thermometer 15 is input to the refrigerant temperature controller 16, which is detected by the refrigerant thermometer 15, and is input to the refrigerant temperature controller 16 via the reaction temperature controller 20. In the reaction apparatus that controls the opening degrees of the control valve 17 provided in the pipe 8 and the control valve 18 provided in the pipe 9 via the i4 calculator 21, the reaction temperature detector 1
The function of the device is the same as that of the conventional device, and its 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. In order to perform the multiplication correction of the proportional gain, 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 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).

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

In contrast to the above, when the reaction temperature is decreasing, the set value input to the refrigerant temperature controller 16 increases slightly compared to the conventional method, and the opening degree of the control valve 18 decreases slightly compared to the conventional method. Appropriate amount of cooling is provided. This keeps the drop in reaction temperature to a minimum.

The above embodiment focuses on the fact that the process characteristics differ 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: mol/rT
?・h) increases. In addition, fever 1iq (kcaffi
/bo・h) and the reaction rate have a relationship shown in equation (1).

Therefore, as the reaction temperature increases, the calorific value 9 also increases.

9ωk・ΔH−・−・・−−−−−−−111・・・・
・・・－－－－－－－－・・・・－－－－(1) However,
ΔH (kcaf/moffi) is the reaction heat In order to take advantage of this process characteristic and control it well, the amount of cooling required is increased more quickly when the reaction temperature rises than when it falls. When the temperature is lowered, the amount of cooling is reduced by a small amount compared to when the temperature is raised, thereby ensuring an appropriate amount of cooling that will not cause fluctuations in the reaction temperature due to excessive throttling.

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 is such that when the reaction temperature rises, the flow rate of refrigerant for cooling the reaction tank is made to correspond to the output of a function calculator whose rate of change increases or decreases in response to changes in the reaction temperature. In this case, the cooling effect of the refrigerant supplied to the jacket is greatly increased, and when it descends, it is stopped slightly, making it possible to reduce fluctuations in reaction temperature.
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.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of one embodiment of the present invention, Fig. 2 is a characteristic diagram of the functional arithmetic unit used in the above embodiment, Fig. 3 & l is an explanatory diagram of the conventional method, and Fig. 4 is an explanatory diagram of the conventional method. It is a characteristic diagram of a refrigerant temperature controller. 5...Function calculator, 6...Preheater, 7.8,9,1
0.11... 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.
...Functional calculator.

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 method for controlling a reaction temperature in a reaction device, the method comprising controlling the flow rate of a refrigerant.