SU246844A1 - METHOD OF REGULATING THE CONTINUOUS PROCESS OF COPOLYMERIZATION - Google Patents

Description

There is a method of controlling the continuous copolymerization of ethylene with alpha-olefins in a battery of reactors without a gas phase by stabilizing the concentration and ratio of monomers in the polymerisation charge introduced, the total heat removal from the reactor and the temperature in the reaction zone by influencing the feed to the catalytic complex.

However, one stabilization of the temperature in the reactor does not lead to a constant reaction rate, which may vary due to a number of extraneous effects.

The change in the reaction rate due to the different reactivity of the monomers ultimately leads to a change in the ratio of monomers in the resulting copolymer.

The proposed method involves carrying out an additional regulation of the process by automatically changing the temperature in the reactor and the ratio of fresh monomers fed to the next reactor, depending on the deviation of the amount of unreacted monomers in the reaction mass from the reactor from the specified value.

This makes it possible to better stabilize the reaction rate and, consequently, to obtain copolymers of a constant and a given composition and, moreover, to ensure maximum performance under given conditions.

The drawing shows a schematic diagram of the automatic control of the continuous process of copolymerizing ethylene with propylene in apparatus without a gas phase. 5 Example. The technological scheme of the copolymerization process consists of several reactors operating in series.

For simplicity, the schematic diagram of the automatic control of the copolymerization process is considered on the example of two successive reactors.

In the first reactor (apparatus /), a constant amount of the reaction mixture is fed,

5 concentration and proportion of monomers in which are constant. The catalytic complex is fed to the same reactor. With a constant monomer concentration, the reaction rate depends only on the amount of

0 of the active catalyst, therefore, the maintenance of a constant reaction rate is possible only by changing the amount of the nodal catalytic complex. Since the copolymerization of alpha-olefins produces a significant amount of heat, the magnitude of the reaction rate is easy to judge by the temperature change in the reactor, provided it is heat-removed from it. Since the copolymerization of olefins

the amount of heat removed, then in order to ensure a constant maximum polymerization rate, the following are measured: 1) refrigerant consumption using a refrigerant consumption sensor (RR); this flow rate is maintained at the maximum permissible level with the help of the refrigerant flow controller (PP); 2) the flow rate of the supplied reaction mixture using the flow sensor (D / C); 3) the temperature of the initial reaction mixture, the temperature of the incoming and outgoing refrigerant and the temperature in the reactor with the help of temperature sensors (DGyDG, DGsD74).

Signals proportional to these parameters, as well as the assignment of a temperature controller (PT are entered into a computing device (-6V), in which the total amount of heat taken by the refrigerant and the reaction mixture is calculated and compared with a predetermined value.

When a mismatch occurs at the output of the computing device, the temperature of the reaction mixture changes with the help of a temperature controller (PTU), thereby stabilizing the total heat removal from the reactor. The flow rate of the catalytic complex is controlled by a temperature regulator (PTi) in the reaction zone, acting on the catalytic comilex (POISON) metering pump, thereby ensuring a constant reaction rate.

However, due to a number of extraneous effects (e.g., changes in the amount of reactor heat loss), the reaction rate, controlled by stabilizing the temperature in the reactor, will also change. A change in the reaction rate due to the different reactivity of the monomers leads to a change in their ratio in the exit solution.

To eliminate the influence of extraneous influences, the reaction rate is adjusted by affecting the setpoint temperature regulator (PTi) in the reaction zone by a signal proportional to the deviation of the ratio of unreacted monomers from a given value, taken by the composition analyzer (AC) of the reaction mixture in the reactor, for example, a chromatograph device. The same signal is fed to the regulator (PPz) for the consumption of fresh ethylene, measured by the DPR sensor, to maintain the concentration at a given level and the ratio of monomers at the inlet to the second reactor (apparatus //).

The regulation of the reaction rate in the apparatus and the stabilization of the heat removed by the refrigerant is carried out according to a scheme similar to that described for the apparatus. Thus, the proposed method for controlling the continuous copolymerization of ethylene with alpha-olefins allows the process to be carried out at a constant, predetermined rate at

maximum equipment productivity and the required ratio of reacting monomers, regardless of any extraneous influences. A similar regulation scheme can be

performed in the first approximation and without a computing device. In this case, the heat introduced by the reaction mixture is stabilized by the refrigerant, and since the change in the heat transfer coefficient in the reactor

Due to the deposition of the polymer on the walls, this occurs at an insignificant rate; correction for this can be introduced periodically.

Subject invention

The method of controlling the continuous copolymerization of ethylene with alpha-olefins in a reactor battery without a gas phase by means of stabilizing the concentration and ratio of monomers in the polymerisation introduced, the total heat removal from the reactor and the temperature in the reaction zone by influencing the catalytic complex therein, the purpose

obtaining copolymers of constant and predetermined composition and ensuring maximum performance under given conditions, the ratio of unreacted monomers to the output from each reactor is measured

the reaction mass and when this value deviates from the set one, the temperature in the reactor and the ratio of the fresh monomers fed to the next reactor are automatically changed.

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