SU937466A1 - Method for controlling process of solution polymerization of butadiene - Google Patents

Description

The invention relates to the control of production processes, in particular, to methods for controlling the process of solution polymerization of butadiene in the production of stereoregular polybutadiene rubber, and can be used in the chemical and petrochemical industry.

There is a method for controlling the continuous polymerization process by affecting the flow rate of the components of the catalytic complex depending on the intermediate parameter, for example, the temperature in the reaction zone, the conversion of the monomer or the viscosity of the polymerizate, and the setting on this parameter is adjusted depending on the shutdown of the polymer quality index, for example, viscosity from a given value of D.

However, this method has disadvantages, since the stabilization of one of the intermediate parameters is insufficient to stabilize the overall polymerization process.

There is also known a method for controlling the process of a polygluerization solution of bootschchen on a complex catalyst consisting of aluminum and titanium components, with separate

introducing the components into the reaction zone by stabilizing the temperature in this zone, measuring the average molecular weight or Mooney viscosity of the polymer, as well as its plasticity and acting upon the deviation of the first two parameters from the nominal value to the consumption of the aluminum catacizer;

10 cm from nominal value for consumption of titanium catalyst component 2.

The disadvantage of this method is the low quality of stabilization of Mooney rubber in the rubber at the end of the process due to the large transport delay in the control loops, in the case of the polymerization process being carried out in a battery of consistently installed polymerization agents.

The closest to the invention to the technical essence is the method of controlling the process of solution polymerization of butadiene, carried out

25 in a battery of sequentially installed polymerizers, when the hydrocarbon charge is fed into the first two polymerizers and. components of the catalyst: titanium halides and tililuminium triisobu-30 to the first polymerizer by changing the consumption of titanium ha / jugenide depending on the conversion of the monomer. According to this method, it is ensured that the viscosity of the reaction medium and the concentration of the polymer N conversion in it is maintained at the head of the polymerization battery 3j.

However, the stabilization of the indicated slip parameters does not always ensure that Mooney rubber viscosity is maintained at a given value at the end of the process. This is due to the fact that the viscosity of the polymer Mooney at the end of the polymerization process is strongly influenced by the change in the monomer conversion at the top of the battery.

The purpose of the invention is to improve the viscosity of the polymer viscosity.

This goal is achieved by the method of controlling the solution polymerization process of butadiene carried out in a battery of sequentially installed polymerization agents, by supplying the hydrocarbon charge to the first two polymerization agents and catalyst components — titanium halides and triisrbutyl aluminum c. the first polymerization agent, by changing the consumption of titanium halides depending on the monomer conversion, measures the viscosity of the reaction medium to the polymer concentration at the outlet of the second polymerization agent, determines the monomer conversion and the residence time of the reaction mass in the third and subsequent polymerizers, according to the obtained values of chemical-chemical parameters determine the predicted value of Mooney viscosity of the polymer at the outlet of the polymer battery and, depending on the value obtained, adjust the consumption of triisobutylaluminum .

The drawing shows a flowchart that implements the proposed method.

The block diagram contains a mixer 1, rakers 2, - 2d, flow sensors of butadiene 3, solvent 4, three types of titanium aluminum 5 and titanium b halides, as well as a viscometer 7, a refractometer 8, a computing device 9, viscosity regulators according to Mooney 10, conversions 11, the cost of triisobutyl aluminum 12 and titanium halides 13.

Example. The initial products of the polymerization process — butadiene (concentration not lower than 99%) and solvent (toluene) —precooled, respectively, to temperatures (-10) q: 2 and (-25) + 5 ° C, are continuously fed to the inlet of the mixer 1. Formed polymerization The charge is distributed in a predetermined ratio between the two first in the course of the process polymerization battery reactors.

 Butadiene consumption 2.5 ± 0.5 t / h, solvent 18 t 2.5 t / h. Charge distribution: 60% in the first and 40% in the second sector. The process proceeds in the presence of a complex catalyst, which is formed directly in the reaction medium.

At the exit of the second reactor 2g. The polymer concentration in the reaction medium Cu is measured using an automatic liquid refractometer (wt.%) and the viscosity of the reaction medium using a low-frequency vibration viscometer.

Determine the amount of polymerized monomer in the first two reactors K by the formula C 100

K 2r. (one)

sh

where C is the concentration of the charge, which is (determined by calculation from the consumption of butadiene C and solvent C p

formula, wt.%:

100

d

2)

sh

The time required for the reaction mass to pass through the third and subsequent reactors is determined before the battery T arrives at the output using the formula:

V

(3)

T

where G is the amount of the fed reaction mass, m / h; “V is the volume of polymerization agents, m. From these parameters, the value of the Mooney viscosity is determined at the output of the second reactor, which will have half the output of the battery after the time T has expired, using the formula

M 13.1 / 1- 1.71 С - 0.184 K +

(four)

+ 1.2.5 T + 24

The conversion of the monomer K is stabilized at a given value by a change in the consumption of halides. titanium.

The predicted value of Mooney polymer viscosity calculated by the formula (4) is compared with the set Mooney polymer viscosity value on the battery (m).

Claims (3)

If the difference between them is greater in absolute value than the predetermined value of E, then the consumption of triisobutylaluminum is affected. Moreover, if, then the consumption of triisobutylaluminum is increased, if M-M.jcE is decreased. The value of E is determined on the basis of the accuracy of adjusting the Mooney viscosity. If the control range is 44-48 units, 5 then E 0, 25, if 42-50, then E 0.5, Determination of the values of values is carried out using a computing device 9. The first output signal of the device is fed to the input of the regulator 10, the OUTPUT signal of which is used as a task to control the flow controller of triisobutylaluminum 12 to the input of KOTopoi; o the signal from the sensor 5. The second output signal from the device is fed to the input of the regulator 11, the output signal of which comes to quality setting the consumption controller of titanium halogen 13 to which the signal from sensor 6 is input. During the experimental verification of the method, the quality of the polymer was improved by reducing the range of Mooney rubber viscosity at the end of the process. The Mooney range of viscosity decreased. from 38g55 to 43-49 units. An increase in monomer conversion by an average of 1.5% has been achieved. Implementing the method will eliminate the formation of substandard (Mooney viscosity below 40 and above 50 units) rubber, and increase the efficiency of the process. Due to the increase in monomer conversion, a reduction in the consumption of toluene applied to the polymerization was achieved to obtain 1 ton of rubber by 0.6 tons. EFFECT OF THE INVENTION Method for controlling the process of solution polymerization of butadiene carried out in a battery of sequentially installed polymerization agents when the hydrocarbon mixture is fed into the first two polymerization agent and catalyst components - titanium halides and triisobutylaluminum in the first polymerization agent by changing the consumption of titanium halides depending on the monomer conversion; This, in order to improve the uniformity of polymer viscosity, measures the viscosity of the reaction medium and the polymer concentration at the output of the second polymerizer, determines the monomer conversion and the residence time of the reaction mass in the third and subsequent Atomic polymerization, based on the obtained physicochemical parameters, the predicted value of Mooney viscosity of the polymer at the output of the polymerisation battery is determined, and the consumption of triisobutylaluminum is adjusted depending on the value obtained. Sources of information taken into account during the examination 1. USSR author's certificate W 388666, cl. From 08 F 2/00, 1970. 2. Authors certificate of the USSR 402527, cl. C 08 F 136/06, 1972. 3., Copyright Jsvidetelstv USSR № 413785, C 08 F 136/04, 1974 (prototype).