Reasons for self-polymerization in the monomer tank
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The self-polymerization phenomenon in the monomer tank is severe; the pH of the monomer sample is 5.8, and the iron ion content is within acceptable limits
Was the non-condensable monomer released after polymerization recovery, or was it recovered and sent to the vinyl chloride gas tank? Due to the slightly acidic nature of the monomer, along with the presence of water and iron ions in the water separator, it tends to undergo slight self-polymerization. Iron ions act as initiators for self-polymerization in the aqueous phase.
When non-condensable gases enter the vinyl chloride gas tank, self-polymerization occurs on a severe scale; the monomer tank must be cleaned every six months or so. Otherwise, the level gauges, pressure gauges, and discharge valves will all stop functioning. The pH value and iron ion content in the water samples are within acceptable limits, and the water separator drains water every two hours
The monomer has a high water content and is acidic; over time, the iron ion level will definitely exceed the permissible limits, leading to catalyzed self-polymerization – it’s necessary to reduce the water content
Appropriately consider adding an inhibitor to the water separator; it is also possible to install a demister after the compressor, and there are companies in China that do this. Another consideration is how to remove the residual additives from the monomer; currently, many companies use an alkali scrubbing tower process for this purpose.
From what you say, it seems to be self-polymerization in the monomer recovery tank; isn’t any inhibitor added to the recovery system? It is recommended to add a polymerization inhibitor. One thing is to pay attention to drainage; during transfer, drain the water first before sending it to the monomer tank. The compressor’s vapor-water separator is equipped with a wire mesh demister; check to see if it has come apart.