Polychloroethylene production reaction temperature control method for small-sized polymerization kettle DCS

Abstract

The invention discloses a control method for the reaction temperature of polyvinyl chloride production by a small polymerizing pot DCS; the DCS controls the processes of the polymerizing pot such as temperature increasing, transition, temperature keeping and pot stopping; a steam shut-off value in front of the reaction pot is changed into an adjusting valve; during the temperature increment stage, the DCS control comprises the sequences as follows: reaction time D value is prearranged, three auxiliary parameter values A, B and C are prearranged, sequential material pouring is carried out, then the steam adjusting valve is opened to specific valve position control, and the judgment of A and B is carried out by program; the transition stage is carried out if the B value is achieved; during the transition stage, the programs closes the steam adjusting valve firstly, and starts a reaction pot jack circulation water valve single circuit, and the judgment of C and D value is carries out by the program; the reaction stage is carried out if the D value is achieved. The relationship of the values A, B, C and D is that A is less than B which is less than C which is less than D; the D value is 52-65 DEG C. Therefore, the reaction temperature can achieve ideal control standard, thus leading the reaction to be stable and ensuring and optimizing the product quality; simultaneously, the control method has the advantages of convenient and quick operation, overcoming the effects of the artificial factors on the product quality, reducing the accident incidence rate, realizing the automatic control of the key procedure of aggregated production, and improving the process parameter detection precision and control precision, etc.

Description

technical field [0001] The invention relates to a method for controlling the reaction temperature of polyvinyl chloride produced by DCS in a small polymerization kettle, in particular to a DCS control method for temperature rise and transition process during polymerization reaction. Background technique [0002] At present, the known polyvinyl chloride suspension polymerization production technology has been very mature. The main process flow is: Put the raw materials containing ion-free water, vinyl chloride monomer, initiator, dispersant, auxiliary agent, etc. The material enters the warehouse pump after stripping, centrifuging and drying to qualified products. The above processes are mostly controlled by DCS distributed control system. The DCS distributed control system is composed of hardware and software. The hardware includes on-site control station, operation station, engineer station, communication network cable, etc.; the software includes the operating system plat...

AI Technical Summary

Problems solved by technology

The above technology is directly applied to the production process and control of polyvinyl chloride in small polymerization kettles (industry practice, the polymerization kettle with less than 20 cubic meters is a small kettle). The main problem is that the original heating steam valve is a shut-off valve, which can only be fully opened or fully closed. , when the temperature rises, the valve opens, and the DCS only judges whether the reaction temperature is reached. When it is close to the reaction set temperature, the heating rate is too fast, which causes large temperature fluctuations during the constant temperature reaction, and it is difficult to control. It is difficult to achieve the ideal temperature. Reaction set temperature value, affect product quality

There are also PLC industrial control technology. The disadvantage is that the control panel setting and calling parameters are complicated, the operation is inconvenient, and it cannot be adjusted in real time according to the reaction status, making the response unstable and difficult to achieve the expected response status, which affects product quality.

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