Vinyl chloride low-boiling tower autopolymerization
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In the production of vinyl chloride, self-polymerization in the low-boiling tower often occurs. I would like to ask fellow experts what are the causes of this phenomenon? What preventive measures should be taken?
May I ask if your factory uses the same gas holder for recycling monomer and fresh monomer? In my opinion, adding an anti-polymerization agent before the low-pressure tower, or drying the solids and placing them after the rear cooler, can effectively prevent self-polymerization in the low-pressure tower
The recovered monomer contains other additives, and the moisture content in the gas entering the tower is high.
Reply to 2# Leng Shan: The monomers we aggregate and recycle do not reach the level present in vinyl chloride gas tanks. I also added polymerization inhibitors in my previous factory, but it didn’t help at all
Replacing solid-alkali dehydration with molecular sieve dehydration can resolve the self-polymerization problem in the high and low boiling towers and improve the quality of the monomer.
To improve the water removal efficiency of distillation, it is recommended to add a polymerization inhibitor system to the distillation system
Reply to 4# Forgotten Oath: Has the gas recovered from the polymer stripping unit been sent to the vinyl chloride gas tank or fed into the compressor there?
Reply to 7# Xinxin: The vinyl chloride monomer in our polymerized gas is condensed in the polymerization cooler, and it does not return to the vinyl chloride gas tank.
Well, the monomer recovered from the stripping tower should go to the gas holder.
The main reason is probably excessive moisture in the monomer; it is necessary to improve the drainage system after the compressor. Both the iron ions and water present in the monomer contribute to its polymerization, which leads to self-polymerization in the low-pressure tower. If I’m correct, the self-polymers formed in your low-pressure tower should take on a bubble-like, sponge-like structure, rather than being just a regular layer of self-polymer material.
The last edit to this post was made by Xinxin on 2010-12-30 at 02:56. Reply 9# Listening to the Rain Last Night: I agree; the reason for self-polymerization must lie here. The vinyl chloride gas recovered through distillation enters the compressor and then the low-pressure tower, and the presence of self-polymers in its composition causes self-polymerization in the low-pressure tower. The gas recovered may not go directly into the gas tank but instead enters the pipelines leading to the compression unit, or perhaps the concentration of self-polymers in the gas recovered at the distillation unit is too high