SU763356A1 - Device for automatic control of polymerization process in solution - Google Patents

Description

The invention relates to the field of automation of polymerization processes and can be used in the processes of polymerization of olefins in a liquid monomer medium. A device for automated control of a solution polymerization process is known, comprising flow and concentration sensors installed on the monomer feed line to the reactor, and flow and concentration sensors mounted on the drain line of unreacted monomer connected through multipliers to the inputs of the velocity determining unit. reaction, the other input of which is connected through a differentiation unit with a temperature sensor installed in the reactor. The output of the unit for determining the reaction rate through the unit of comparison is connected to the regulator of the flow rate of the catalyst Щ. A disadvantage of the known device is the low accuracy of controlling the concentration of the polymer in the reaction zone, since the fluctuation of the density of the liquid monomer is not taken into account. change in the ratio of temperatures and pressures in the reactor and in the monomer feed line to the reactor. Closest to the invention, the technical entity is an automatic solution polymerization process control device comprising temperature and pressure sensors installed in the reactor and in the monomer feed pipeline to the reactor connected to the inputs of the correction unit, one of the inputs of the correction unit being connected to the determination unit reaction rate, the output of the correction unit through the comparison unit is connected to the first input of the flow controller, the second input and the output of the catalyst flow controller are connected according to Actually, with a catalysis flow sensor and an actuator mounted on the catalyst supply pipe to the reactor, the flow sensor connected to the reaction rate determining unit 2 is installed on the suspension discharge line of the reactor. The known device does not provide sufficient performance of the polymerization process, since the measurement of the suspension flow rate at the reactor exit is carried out with a significant error in a number of cases, which is determined by the fact that the suspension can greatly change the properties of the flow sensor due to adhesion of the polymer on the sensor surface at the contact method, the measurement, and in the non-contact method of measurement, an error occurs due to a change in the properties of the suspension when the volume fraction of the polymer changes in it.

The aim of the invention is to increase the productivity of the polymerization process by increasing the control accuracy.

This goal is achieved by the fact that the known device for automatic control of the solution polymerization process, containing temperature and pressure sensors installed in the reactor and in the monomer feed pipeline to the reactor, is connected to the inputs of the correction unit, the output of which is connected to the first input of the catalyst consumption regulator , the second input and output of the catalyst consumption regulator are connected respectively to the catalyst consumption sensor and q actuator installed on the pipe The catalyst feed into the reactor, the reaction rate detection unit, is equipped with a reaction rate correction unit and a polymer concentration sensor installed in the reactor, with the first and second inputs of the reaction rate detection and correction unit connected to the polymer concentration and temperature sensors, the speed correction unit output reaction is connected to the third input of the reaction rate determination unit, and the output of the reaction speed determination unit is connected to the third input of the correction unit.

FIG. 1 shows a block diagram of a solution polymerization process control device; in fig. 2 is a block diagram of the reaction rate correction unit.

The process solution control unit of the polymerization comprises a temperature sensor 1 and a pressure sensor 2 installed on the monomer feed pipe 3 to the reactor 4, in which a temperature sensor 5, a pressure sensor b and a polymer concentration sensor 7 are installed. The output of the temperature sensor 5 is connected to the first input of the reaction speed correction unit 8, the second input of which is connected to the polymer concentration sensor 7, and the output of the reaction speed correction block 8 is connected to the third input of the reaction speed detection unit 9, the second and first inputs of which are connected respectively to the sensor 7 polymer concentration and with temperature sensor 5. The output of the reaction rate determining unit 9 is connected to the first input of the correction unit 10, the second input of which is connected to the temperature sensor 5, the third input to the pressure sensor 6, the fourth input to the temperature sensor 1, the fifth input to the pressure sensor 2.

The output of the correction unit 10 through the comparison unit 11 is connected to the first input of the flow controller 12, the second input of which is connected to. a flow sensor 13 installed on the catalyst supply pipe 14 to the reactor 4. The pipeline 14 also has an actuator 15 connected to the output of the flow controller 12.

The reaction rate correction unit 8 contains a memory unit 16, the outputs of which are connected to the first input of the polymer concentration error detection unit 17, the first input of the reactor temperature error detection unit 18 and the input of the block 19 are determined. the concentration of catalyst in the reaction zone, the output of which is connected with the first input of the switch 20 and the second input of the polymer concentration error detection unit 17, as well as the second input of the reactor temperature error detection unit 18. The third input of the polymer concentration error detection unit 17 is connected through the first amplifier 21 to the first input of the adder 22, and the output of the temperature error error detection unit 18 in the reactor via the second amplifier 23 is connected to the second input of the adder 22, the output of which is connected to the second through the comparison unit 24 input switch 20 to determine the reaction rate.

The control unit of the solution polymerization process works as follows.

When the density and composition of the liquid monomer in pipeline 3 is constant and the catalyst activity in pipeline 14 is constant, the response speed correction unit 8 signals the sensor 5 and the polymer concentration sensor 7 to generate a signal as follows (see Fig. 2). The signal from sensor 5 temperature is fed to the first input of memory 16 and simultaneously to the third input of block 18 for determining the temperature error in the reactor, and the signal from polymer concentration sensor 7 is fed to the second input of memory 16 and simultaneously to the third input concentration error determination unit 17 polymer. The stored signals from the output of memory 16 are simultaneously received at the first input of the polymer concentration error determination unit 17, the first input of the reactor temperature error detection unit 18 and the input of the catalyst concentration determination unit 19 in the reaction zone, the output of which is proportional to the current value of the catalyst concentration The reaction zone simultaneously arrives at the second input of the block 17 for determining the polymer concentration error and the second input for the block 1.8 for determining the temperature error in the reactor. In block 17 9, the determination of the polymer concentration error using signals from the output of the memory block 16 and from the output of the catalyst concentration determination unit 19 in the reaction zone determines the current polymer concentration in the reactor, resulting in a signal at the output of the control unit 17 proportional to the concentration determination error polymer in reactor 4. In block 18, the determination of the temperature error in the reactor using signals from the output of memory block 16 and from the output of block 19 for determining the concentration of catalyst in the reactor In this case, the current temperature in the reactor 4 is determined, compared with the measured temperature in reactor 4, resulting in a signal at the output of block 18 proportional to the error in determining the temperature in reactor 4. The output signal of the polymer concentration error determining 17 the amplifier 21 is fed to the first input of the adder 22, where it is summed up with the output signal of the unit 18 for determining the temperature error in the reactor amplified by the second amplifier 23 outputted to the second input. of the adder 22 is proportional to the current value given error arrives at the input of the block comparator 24, which is compared with a set value given error. The output signal of the comparator unit 24 is fed to the second input of the switch 20, the first input of which receives the output signal of the unit 19 for determining the concentration of the catalyst in the reaction zone. In the case where the reduced error value obtained in the adder 22 is greater than the specified value, the output signal of the switch 20 is not generated, and the operation of the reaction rate correction block 8 continues as described above. In the case when the value of the reduced error obtained in the adder 22 is less than or equal to the specified value, the output of the switch 20 generates a signal equal to the output signal of the catalyst concentration determining unit 19 in the reaction zone, which is used further as a correction signal to the third input block 9 for determining the reaction rate (see Fig. 1), the second input of which receives a signal from the sensor 7 of polymer concentration, and the first input - a signal from the sensor 5 of the temperature. The output signal from block 9 to determine the reaction rate, pass

through correction block 10, without change, is fed to comparison block 11, where the current reaction rate is compared with the set one and, depending on their difference, the task is set to the catalyst consumption controller 12 controlling the actuator 15, which changes the catalyst feed to the reactor 4 until the current reaction rate is compared with the desired one.

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When changing the density and (or) the composition of the liquid monomer in the pipeline 3 and (or) the activity of the catalyst in the pipeline 14, in accordance with the change of signals from the sensor

five

5 temperature and the polymer concentration sensor 7 changes the value of the output signal of the reaction speed correction unit 8, as a result of which the output signal of the block 9 changes

0 determine the reaction speed, which is fed to the first input of the correction unit 10, in accordance with the change in the output signal of the reaction speed detecting unit 9, as well as the change in the signals of the temperature sensors 1 and 5 and the pressure sensors 2 and

6, the output signal of the correction unit 10 is proportional to the corrected value of the current reaction rate. This signal arrives at the input of the comparator unit-11, where the current reaction rate is compared with the set one, and, depending on their difference, the setting of the catalyst consumption controller 12 varies, controlling 5 liters of the actuator 15, which changes the catalyst feed to the reactor 4 until the current reaction rate is comparable to the set one. Due to the fact that

0 device for automatic control of mortar polymerization process; speed correction unit is inserted.

The reactions performed according to the described scheme made it possible to improve the performance of the polymerization process, since it was possible to exclude from the device for controlling the polymerization process the suspension flow sensor at the reactor exit, which in some cases is a source

0 errors in determining the rate of reaction, which is the main characteristic of the polymerization process. The described control unit allows the reaction rate to be determined based on the knowledge of the state of the process instead of indirectly calculating the reaction rate from the monomer consumption at the reactor inlet and the suspension at the reactor outlet.

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Claims (2)

1. US patent number 3130187, class. 260-94.9, 04.21.64. 2. USSR author's certificate No. 488194, cl. G 05 D 21/00, 16.04.74.