Application of defoaming agent in PVC production-Iota

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Service > Application of defoaming agent in PVC production

Application of defoaming agent in PVC production

Today we will introduce you to: elimination of specific application of foaming agent PVC at all stages of production, so that we better understand the PVC production of excellentperformance of defoaming agent.

Summary

Defoaming agent is a kind of a wide variety of industrial applications of agent, is widely used in various fields of the national economy. However, many problems need to solve.The bubble at various occasions, the myriads of changes, in order to solve the problemof many system defoaming, defoaming and need more varieties of forms. According to the manufacture of defoaming agent of raw materials and the structure of raw materials,can be divided into the following 3 categories:

(1) as a natural product based products, plant oil and mineral oil and compound ofcommon, due to multiple sources, cheap price, many varieties are still in use;

(2) polyether to petrochemical product based defoamer, a common block copolymerpolyoxyethylene polyoxypropylene polymer, or both, as the development of the petrochemical industry, become since twentieth Century since the 60's of a type of defoaming agent;

(3) with polysiloxane as the main raw material of organic silicon defoaming agent,because of its excellent surface properties, widely used in various fields..

Aiming at the particularity of PVC production industry, defoaming agent in each process stage application of excellent performance of PVC production process.

L, defoaming agent in the preparation process of distributed application.

The first stage in the production of PVC was prepared by dispersing agent, in HPMC andPVA suspension agent, must be prepared. The preparation of stirring, the solution oftenfroth. The cause of these bubbles overflow and dispersion agent loss. Cannot observethe height of the liquid level, the use of foam can be eliminated as the bubble. Foaming agent can disperse well in HPMC and PVA as dispersant in the suspension system ofelimination of polyether block, does not destroy the system stability, and has good defoaming and antifoaming performance.

2, application of defoaming agent in the polymerization process

In the polymerization, the polymerization system is to use HPMC and PVA as dispersant,the dispersant has a surface tension. As the polymerization kettle will produce foam, the foam can be called the "wet bulb". "Wet bulb" produced in the reaction system on thesurface, resulting in VCM gas phase polymerization kettle, the inner wall of the liquid levelabove the kettle, adhesion to fall from the kettle, the resin of black and yellow spots.Influence of resin product quality. In the kettle with a reflux condenser, in order to increase the cooling effect, the reaction to a large number of VCM gas through the liquid layer and the condenser, the condenser is condensed into liquid, back to the reaction system. In the process of VCM vapor volatilization, resulting in a large number of foam.This process often takes place in the intense period of reaction, the foam can be referred to as a "dry foam". Produced in the reaction system and the "wet" bubble "bubble" to eliminate the need for defoaming agent. Since the suspension of reaction liquid is anunstable system, so the defoamer selection is reasonable. Will have a greater impact onthe reaction process. In addition, the defoaming agent adding method should also be carefully considered, should be at the beginning of the reaction of 2h, began to use thecontinuous adding way of adding defoaming agent, and should make appropriatedilution. Because of the high concentration of defoaming agent is added in the reaction system, there may be suspended system local failure in the reaction kettle, coarseparticles, resin, affecting product quality. Using defoamer is a good choice, the product has excellent stability and dilution, defoaming speed is fast, and the suspension has good compatibility.

3, application of defoaming agent in the discharge.

After the polymerization reaction, the slurry after discharged to the discharging worse,unreacted VCM to drain away. In removing unreacted gas, which will produce a large amount of foam tank, the foam with unreacted gas discharge, often cause many problems such as pipeline blockage, the waste of the material, the use of defoaming agent can eliminate the bubble. This process uses the defoaming agent, general manufacturers are adding and terminating agent. The antifoaming agent should have a wide pH value range, good defoaming and antifoaming performance best, because for most of the small and medium-sized enterprises, recovery of VCM monomer is not astripper recovery, and no amount of defoaming agent in the recovery of VCM monomerin the process, the process requires considerable recovery a period of time, therefore,defoamers defoaming performance has a direct impact on the recovery of VCMmonomer and the speed of time. Defoaming agent used in the production stage.Demonstrate good defoaming and antifoaming performance, in the recovery process can effectively eliminate and inhibit foam.

4, application of defoaming agent in the stripper in operation

The stripper VCM monomer recovery business, at the end of the reaction of strippingremoval of slurry VCM. The general was a stripper, slurry by the flow to the bottom of the tower, and the steam from the bottom up and slurry was sufficient heat exchange, in this process, each layer of the slurry on the tray will produce foam. These bubbles will be a serious impediment to paste the volatilization of VCM, increase the power of removal of VCM, the bubble in the tower wall long will produce "black yellow particles", affecting the quality of the products. In order to eliminate the steam bubble extraction operation. Usingdefoamer. Antifoaming agent should be added to the appropriate dilution, even strippingdevice, because of the high concentration of anti foaming agent is added, may make the PVC particles increased adsorption effect, recovery and post-processing of VCM monomer. Therefore the use of defoaming agent diluted continuous adding. Can eliminate a large number of bubbles generated when stripping, increase the recoveryrate, to speed up the recovery process. Defoaming agent with excellent performance has been recognized by the user.