SU798110A1 - Method of automatic control of synthetic rubber aqueous degassing process - Google Patents

Description

one

The invention relates to the automation of the production process of polymeric materials, in particular, to a method for automatically controlling the process of water degassing of synthetic rubber, and can be used in the petrochemical industry.

The closest in technical essence to the present invention is a method for automatically controlling the process of water-degassing synthetic rubber in a continuous degasser, consisting in stabilizing flow rates at the inlet to the degasser, and controlling the steam flow to the degasser depending on the change in the content of residual solvent in degassed rubber Jl.

However, due to the complexity of the automatic determination of the solvent content in degassed rubber, its practical implementation has failed. In the process control method, nci-epacxon tiapo nl degassing is possible due to the formation of stagnant zones in the degasser and the unrepresentativeness of the sample being analyzed, as well as the incomplete use of steam. In addition, the method is not used to control the process of water degassing of the polymer, carried out in a cyclic mode, since it does not allow to take into account the forced fluctuations of the steam consumption in the mixer, which are necessary to create the corresponding hydrodynamic conditions in the degasser.

The purpose of the invention is to improve the technical and economic indicators by reducing the specific steam consumption.

The goal is achieved by affecting the maximum steam flow rate at periodically excited oscillations of the said flow rate depending on the pressure drop across the plates in the working zone of degassing.

FIG. 1 shows a scheme for implementing the method; in fig. 2 - change of steam span in a degasser in time.

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The scheme of the avgomatic control of the degasser 1 and the pump 2 consists of the restricting regulator 3, the regulator 4 and the actuator 5 on the water line to the degasser 1, the restricting device. 6, the regulator 7 and the actuator 8 on the polymer solution line in degazatf 1, the restriction device 9, the regulator 10, and follow the mechanism 11 on the vapor line on

crumb formation in the degasser 1, pressure sensors 12 and 13, regulator 14, actuator 15 on the pulp line, pressure sensors 16 and 17, jumpers 18 and 19, cc | of the control unit 20, the controller 21, the unit 22 for instantaneous memory storage, the generation of 23 pneumocompulators, the controller 24 for the maximum mass flow rate of the unit

25pami tees, actuators

26 and 27 of the restriction device 28. The polymer solution, water and steam are continuously fed to the upper part of the degasser 1 for crumb formation. Inside the degasser, in its working zone, there are contact plates, under which steam is supplied from the bottom for degassing. The polymer crumb formed in the upper part of the degasser together with the water in the form of a pulp will mix down. In this case, steam is supplied from the crumb, fed 1M to the lower part of the degassed material and directed towards it, the residual solvent is removed.

Steam is supplied to a degasser with a periodically varying flow rate — cyclically. With an increase in the steam flow rate, the pulp flow downwards is delayed, and with a decrease in the steam flow rate, the pulp gradually moves to the underlying stages.

Since, when operating in such a cyclic mode, the steam moves at a high speed, it is cropping. polymer makes sharp random movements. In this case, the interacting Potszhi are turbulized, a multitude of internal eddies arise, and the contacting surfaces are exposed. Due to the non-stationarity of flows, the driving force of the process increases. All this leads to an increase in the interfacial mass transfer rate, a sharp intensification of the process and, as a consequence, to a decrease in the specific steam consumption.

The finished slurry is discharged from the bottom of the degasser 1 by the pump 2, and solvent and water are discharged from the top of the degasser.

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Automagic process control of the polymer water degassing is produced as follows.

The flow rate of water supplied to the vertical part of the column is stabilized by means of a circuit consisting of a clamping device 3, regulator 4 to the actuator 5. Similarly, the flow rate of the polymer solution (respectively blocks 6–8) and steam consumption for crumb formation (respectively blocks 9- eleven). The level in the degasser cube is maintained at a predetermined value by means of an adjustment circuit consisting of a pressure sensor 12 and 13, a regulator 14, and an actuator 15.

Cyclic mode in the degasser is provided by changing the flow rate of the aar supplied for degassing, for example, the form of a square wave (fcg. 2) of which is characterized by a period T, a duty cycle t (J / T (L and pulse feed time), a minimum instantaneous flow, a pair Grnin tvfaK .cH: Ma / ibHbiM c-g The steam flow rate Qmax-P conducts the degassing process on the plates in the working area of the degasser, a certain pressure drop is established,

The required mode of operation of the degasser and the required degree of degassing of the polymer is achieved when these parameters are maintained at the set values.

The period to the duty cycle is set rigidly with the help of RC by the generator of the 23 pneumoivvtpuls generator (Fig. 1). The minimum instant steam consumption, as well as the maximum instant steam consumption, depended on the pressure drop across the plates in the working zone of the degasser, are subject to random disturbances - pressure and steam measures, the state of the packing glands, etc. These parameters are kept constant by means of regulating units and the corresponding mechanics.

The steam led to degassing passes through the constriction device 28 and the actuators 2.6 and 27. The signal from the constriction device is fed to the appropriate blocks for storing minimal O and maximum costs.

To stabilize the minimum instantaneous flow rate, use is made of gauge 19, pneumatic proportional regulator 21, unit 22 for storing instantaneous mass flow, generator 23 of pionochmpo.chs and actuator 26. The controller 21 is supplied with control buttons of unit 19 and unit 22 for storing minimum instantaneous flow. If there is a mismatch between these MU signals on the output controller 21, a command action is generated, which through the generator 23 of pulses is directed to the actuator 26, moving its regulator towards the smart1: the resulting mismatch. Block 22, the memorized 1;: k-ginkkalny instant solution, is at one time used to convert a discrete pneumatic {atic signal to an analog signal. The maximum instantaneous consumption of steam supplied to the degasser varies, depending on the pressure drop, not on the plates in the working zone of the pegasifier. This transducer is sensed via pressure sensors 16 and 17 by a correcting block 2O, which also receives a reference from setpoint 18. Output from block 2.0 and a signal proportional to the maximum instantaneous flow through memory block 25 are fed to a pei-lator

24 maximal instant - and-ho; and 24, which is developed according to the corresponding command influence, which is perpetuating the executive system of change. 27.

Form ula invention

A method for automatically controlling the process of water degassing of synthetic rubber in a continuous degasser that consists in stabilizing the flow rates of the HQ process streams entering the Degasser and regulating the steam flow to the degasser, in order to reduce the specific steam consumption , affect the value of the maximum steam flow rate at periodically excited oscillations of the said flow rate depending on the pressure drop across the plates in the working zone of the degasser.

Sources of information taken into account in the examination

1. USSR author's certificate No. 421698, cl. С О8 F 6/12, 197О (prototype).

Parbg pacmSapameAa and Water Steam for degassing - O-% J-% 31 per drying

Fil2

Claims (1)

Claim Automatic control method 10 by the process of water degassing of synthetic rubber in a continuous degasser, which consists in stabilizing the flow of process flows at the inlet of the degasser and regulating the flow of steam into the degasser, characterized in that, in order to reduce the specific steam flow, they affect the maximum steam flow for periodically excited fluctuations in the flow rate, depending on the differential pressure on the plates in the working area of the degasser.