JP2883103B2 - Reactor temperature controller - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a reactor temperature controller, and more particularly, to a reactor temperature controller excellent in removing reaction heat.

[Conventional technology]

Conventionally, as a device for producing polyethylene by a solution polymerization method, for example, a reaction device as shown in FIG. 4 is known.

For this, a gas circulation path 2 is connected to a reactor 1, and the gas circulation path 2 is connected to a condenser 3, a receiver 4 for storing the condensed liquid obtained in the condenser 3, a gas circulation blower 5, a blower 5 And an adjustment valve 6 for adjusting the amount of air blown from the air. The gas in the reactor 1 vaporized during the reaction is cooled by the condenser 3 and condensed, and the condensed liquid is stored in the receiver 4 and then returned to the reaction vessel by the pump 21. . On the other hand, the gas that has passed through the condenser 3 is returned to the solution in the reaction vessel again by the blower 5, and the solution in the reactor 1 is stirred and cooled by gas bubbles generated at that time. . Further, a temperature controller is provided for monitoring the temperature of the solution in the reactor 1 and adjusting the degree of opening of the air flow regulating valve 6 according to the fluctuation.

[Problems to be solved by the invention]

The above-mentioned temperature control device of the reactor 1 has a problem that it is very difficult to control the temperature of the solution reaction of a highly viscous substance such as solution polymerization of ethylene.

That is, when the reaction proceeds suddenly due to an unexpected disturbance and the reaction heat rises, the amount of air blown for cooling increases in proportion to the temperature change, and at this time, the solution becomes even more violent due to the increased bubbles. It was agitated, and the polymerization reaction further proceeded by the agitation, resulting in a situation that the temperature was rather increased. In addition, as the amount of air blown increases, the amount of polymer and solution scattered along with the gas increases, thereby contaminating the condenser in the circulation path and increasing the gas volume in the solution, causing the reaction liquid level to rise. After that, when the reaction returns to a steady state and the liquid level drops, the polymer solution adheres to the inner wall of the reactor 1, and the polymer further polymerizes on the wall surface and mixes into the solution, eventually lowering the reaction efficiency. And the quality of the polymer deteriorated.

In order to avoid such a situation, even if the reaction heat rises sharply, the amount of air blow cannot be extremely increased. However, when the reaction temperature suddenly rises, if the amount of air blow is reduced, the reflux of the condensate alone cannot sufficiently reduce the heat of reaction. As a result, inconveniences such as runaway of the reaction and stagnation of the reaction occur.

For this reason, the conventional temperature control device for the reactor 1 has a problem that it is very difficult to control the temperature of a solution reaction of a highly viscous substance such as ethylene polymerization.

SUMMARY OF THE INVENTION It is a technical object of the present invention to provide a reactor temperature control device capable of effectively controlling the temperature in a reactor in consideration of the conventional problems as described above.

[Means for solving the problem]

In order to solve the above-mentioned problems, a gas circulation path 2 is connected to a reactor 1, and the gas circulation path 2 includes a condenser 3 and a gas circulation blower 5, and a reaction vaporized during the reaction. Vessel 1
The condensed liquid is stored in the receiver 4 and the condensed liquid is returned from the receiver 4 into the reaction vessel, and the solution in the reactor 1 is cooled. While cooling the gas, the gas passed through the condenser 3 is returned to the solution in the reaction vessel again by the blower 5, and the solution in the reactor 1 is stirred and cooled by bubbles of gas generated at that time. First temperature control means for controlling the amount of air blown by the blower 5 based on the service temperature in the reactor 1 and second temperature control means for adjusting the cooling temperature in the condenser 3 based on the solution temperature in the reactor 1 Temperature control means, and weighting means for lowering the cooling temperature of the condenser 3 by the second temperature control means prior to an increase in the amount of air blown by the first temperature control means. A temperature controller was used.

Here, in addition to the first temperature control means, a third temperature control means for adjusting the amount of air blown may be added so that the condensate temperature in the receiver 4 does not reach a predetermined lower limit.

Further, in the above description, when the second temperature control means is a means for adjusting the temperature of the solvent supplied to the reactor 1, when the plurality of receivers 4 are installed in series, at least one of them is used. One example is a temperature adjusting unit for adjusting the temperature, and a case of a temperature adjusting unit for adjusting the temperature of the recirculated gas based on the temperature of the solution in the reactor 1. Further, a fourth temperature control means for independently controlling the temperature of the circulating gas may be provided.

[Action]

When the temperature in the reactor 1 rises sharply, the temperature of the condensate is lowered and cooling by this condensate is performed more than the increase in the amount of air blown. Therefore, the above-mentioned adverse effects due to an increase in the amount of air can be avoided.

By the way, it is not necessary to increase the amount of air blow so as to lower the temperature of the condensate. In some cases, the temperature of the solution in the reactor 1 can be lowered without increasing the amount of air blow. If the condensate having a lower temperature than the above (depending on the type of solution in the reactor) is returned into the reactor 1, the reaction of the solution in the reactor 1 becomes abnormal, which is not preferable. Therefore, if the air flow rate is adjusted by the first temperature control means or other means under the condition that the condensate temperature in the receiver 4 has reached a predetermined lower limit, the air flow rate increases, and the condenser 3 The amount of gas passing per unit time increases, and consequently the temperature of the condensate rises. At this time, the cooling of the solution, which can no longer be covered by the condensed liquid, is covered by an increase in the amount of air blown.

As described above, the temperature of the condensate rises only by increasing the amount of gas passing through the condenser 3, but instead of such an indirect operation, the condensate temperature in the receiver 4 becomes a predetermined lower limit. On the condition that the air flow rate is increased in addition to the first temperature control means,
A control such as limiting the flow rate of the refrigerant may be performed so as to directly increase the cooling temperature of the refrigerant.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1 As shown in FIG. 1, a gas circulation path 2 is connected to a reactor 1. The gas circulation path 2 includes a condenser 3 for taking in and condensing the gas generated in the reactor 1, a receiver 4 for storing the condensed liquid obtained in the condenser 3, a blower 5 for circulating the gas, An air volume adjusting valve 6 for controlling the air volume from the blower 5 is sequentially connected.

A condensed liquid return path 7 for returning the condensed liquid into the reactor 1 is connected to the receiver 4, and the condensed liquid is returned from the condensed liquid back into the reactor 1 so that the solution in the reactor 1 is cooled. It has become.

Further, the gas that has passed through the condenser 3 is returned to the solution in the reactor 1 again by the blower 5, and the solution in the reactor 1 is stirred and cooled by gas bubbles generated at that time. I have.

Further, a first temperature controller 10 for monitoring the temperature of the solution in the reactor 1 is provided. The temperature controller 10 sets a target value in the air volume controller 11 that controls the opening of the air volume adjusting valve 6, monitors the temperature of the condensed liquid, and adjusts the opening of the refrigerant flow adjusting valve 8 of the condenser 3. The target value of the condensate temperature is set in the second temperature control 12 for adjusting the refrigerant flow rate.

That is, the ratio of the cooling by the air flow and the cooling by the condensed liquid is changed by the distribution of each target value. Here, the cooling ratio by the condensed liquid is set to be as large as possible.

From the above, the first temperature controller 10 functions as first temperature control means for controlling the amount of air blown by the blower 5 based on the temperature of the solution in the reactor 1, A role as second temperature control means for adjusting the cooling temperature in the condenser 3 based on the temperature;
The weight control means also lowers the cooling temperature of the condenser 3 by the second temperature control means in preference to the increase in the amount of air blown by the temperature control means. Also,
It can be said that the second temperature controller 12 also constitutes second temperature control means.

Each of the controllers (10, 11, 12) is a so-called PID calculation controller, which sets a target value in accordance with the fluctuation of the solution temperature and controls the control target to the target value.

 Hereinafter, an operation example of the present embodiment will be described.

A catalyst and a monomer (hereinafter, simply referred to as a solution) are supplied into the reactor 1 to start polymerization.

To control the temperature of the solution, a first temperature controller 10 constantly monitors the temperature in the reactor 1. In addition, the blower 5 is constantly operated, and the blown air introduces gas into the condenser 3, and the condensed liquid is stored in the receiver 4 and then returned to the reactor 1 to cool the solution. The gas that has passed through the condenser 3 is returned to the solution in the reactor 1 by the blower 5, and the solution is stirred and cooled by bubbles generated at that time. By such cooling, the reactor 1
Here, the temperature inside is maintained at 170 ° C.

Here, it is assumed that the temperature during the operation of the reactor 1 rises sharply by 10 ° C. Then, in order for the first temperature controller 10 to perform cooling according to the fluctuation, the air volume controller 11
And a command (SET2) to increase the refrigerant flow rate of the condenser 3 to the second temperature controller 12. Here, SET1 and SET2 are SET values (target values) in the PID control, and the air volume is increased toward the target values, and the condensate temperature is lowered.

That is, the air volume controller 11 opens the air volume adjustment valve 6 toward SET1, and the second temperature controller
The refrigerant flow control valve 8 is opened until the temperature of the condensate in the tank reaches the temperature of SET2.

The increase in the temperature of the reactor 1 is absorbed by the increase in the air volume and the cooling due to the decrease in the temperature of the condensate. If the cooling in this case is set to 100, for example, the cooling by the increase in the air volume bears 30 and the condensation Weighting is performed so that the cooling due to the temperature drop of the liquid bears 70. The burden rate is such that the solution in the reactor 1 is rapidly agitated due to the rapid increase in the air volume, and the polymerization rate of the solution is rather accelerated, and the air volume is increased slowly so as not to cause a temperature rise in the reactor 1. Distribution.

As described above, the temperature in the reactor 1 is kept constant, and the increase in the air volume is minimized.

Second Embodiment As shown in FIG. 2, in the second embodiment, in addition to the configuration of the first embodiment, a third temperature controller 13 for monitoring the condensate temperature in the receiver 4 is provided. The third temperature controller 13 is also a PID calculator, and is the third temperature control means described above.

In the first embodiment, the cooling of the condensate temperature is performed with priority given to the increase of the air volume. However, if the temperature is too high, the condensate having a temperature too low as compared with the solution temperature in the reactor 1 may be cooled. 1
May be returned to the solution polymerization to cause adverse effects such as polymer precipitation.

Therefore, in the third controller 13, the operation amount (SET1) by the first temperature controller 10 is set to the operation amount (SET3) to the effect of increasing the air blowing amount so as not to reach the lower limit of the condensate temperature causing such a problem. Are added by the adder 14.

This amount of SET3 should take over the amount of cooling by (lower limit of condensate temperature-condensate temperature targeted by SET2).

Since SET2 is given to the second temperature controller 11, the condensate temperature is controlled to the target value (SET2) which is the lower limit. Since the amount of gas per unit area increases, as a result, the temperature of the condensate is reduced and the temperature of the reactor 1 rises gently.
Output to T2 is also reduced. As a result, the condensate temperature does not reach the lower limit. The cooling of the solution that can no longer be covered by the condensed liquid is covered by an increase in the amount of air blown.

In the embodiment, if the original lower limit is 70 ° C., the third temperature controller 13
Was set at 75 ° C.

Also in the case of the second embodiment, the cooling is first performed with priority given to the reduction of the condensate temperature, and when it reaches the lower limit, the SE1
Since T3 is added, it is possible to perform appropriate temperature control without a sudden increase in air volume.

<Other Embodiments> As shown in FIG. 3, the receivers 4 may be provided in multiple stages to control the temperature of the receivers.
May be provided. By doing so, the temperature control can be performed more finely.

〔The invention's effect〕

ADVANTAGE OF THE INVENTION According to this invention, temperature control in a reactor can be performed stably and effectively.

[Brief description of the drawings]

1 is a schematic diagram showing a first embodiment, FIG. 2 is a schematic diagram showing a second embodiment, FIG. 3 is a diagram showing another example, and FIG. 4 is a concept showing a conventional example. FIG. DESCRIPTION OF SYMBOLS 1 ... reactor, 2 ... gas circulation path, 3 ... condenser, 4 ... receiver, 5 ... gas circulation blower, 10 ... 1st temperature controller (1st temperature control means,
Weighting means), 11 ... airflow controller (first
, A second temperature controller (second temperature control means), and a third temperature controller (third temperature control means).

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Satoshi Yamamoto 3 Chigusa Coast, Ichihara-shi, Chiba Mitsui Oil Chemical Industry Co., Ltd. (58) Field surveyed (Int. Cl. ⁶ , DB name) B01J 19/00 G05D 23/00

Claims (5)

(57) [Claims] 1. A gas circulation path 2 is connected to a reactor 1. The gas circulation path 2 includes a condenser 3 and a gas circulation blower 5, and the gas in the reactor 1 vaporized during the reaction. After the gas is cooled and condensed by the condenser 3, the condensed liquid is stored in the receiver 4, and the condensed liquid is returned from the receiver 4 into the reaction vessel to cool the solution in the reactor 1. On the other hand, the gas which has passed through the condenser 3 is returned to the solution in the reaction vessel again by the blower 5, and the solution in the reactor 1 is stirred and cooled by gas bubbles generated at that time. First temperature control means for controlling the amount of air blown by the blower 5 based on the temperature of the solution in the reactor, and second temperature control for adjusting the cooling temperature in the condenser 3 based on the temperature of the solution in the reactor 1 Means for increasing the amount of air blown by the first temperature control means. Previously and the reactor temperature control apparatus and a weighting means for so as to lower the cooling temperature of the condenser 3 by the second temperature control means. 2. The method according to claim 1, further comprising: adding an operation amount to increase an air blowing amount to the operation amount by said first temperature control means so that the condensate temperature in said receiver 4 does not reach a predetermined lower limit. A temperature control device for a reactor provided with a temperature control means. 3. The temperature control means according to claim 1, wherein said second temperature control means adjusts at least one of the plurality of receivers when a plurality of said receivers are installed in series. Some reactor temperature controllers. 4. A reactor according to claim 1, wherein said second temperature control means is a temperature adjustment means for adjusting a temperature of a recirculated gas based on a solution temperature in said reactor. Adjustment device. 5. The reactor temperature controller according to claim 1, further comprising a fourth temperature controller for independently controlling the temperature of the recirculated gas.