Problem of pipe blockage due to icing in the tail condenser
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Regarding the problem of the discharge port of the tail condenser in VCM distillation getting clogged easily, I was wondering how everyone addresses it? Steam tracing is generally used, but its effectiveness is not very good. I’ve heard that increasing the diameter of the feed pipe can help prevent freezing; I wonder if any companies use this method?
The possibility of the discharge pipe being blocked by the exhaust gas condenser is very low; usually, it is the tubes inside the condenser that freeze up and cause blockages. It is possible to discharge material from each condenser separately; after one of them is blocked, melt the ice using the other one
Is the blockage in the feed pipe caused by the accumulation of iron shavings? We have encountered this issue: due to acidity in the system, iron filings accumulate at the bends, causing problems with the support structure of the exhaust gas condenser.
Enhance water removal, particularly the cooling efficiency of the after-cooler. If conditions permit, it is advisable to install a set of pressure swing adsorption dehydration unit or solid alkali drying and dehydration unit after the after-cooler.
If freezing occurs frequently, it may be related to the structure of the material feed pipes (the connections between branch pipes and the main pipe, elbows, etc.), or it could be that your water removal system is not effective enough.
The tail cooler in our distillation system has experienced blockages; it’s not the feed pipe or the cooling coil tubes, but rather the vent pipes and valves that are blocked. Upon disassembling the program-controlled valve on site, it was found to be clogged with ice; the issue was resolved after flushing it with hot water. After analysis, it is believed that the blockage occurs at the lowest point of the pipeline, and the blockage does not happen all the time. Therefore, we determined that the blockage of the vent pipe was caused by fluctuations in water content in the crude vinyl chloride. When the moisture content in crude vinyl chloride exceeds a certain threshold, the very low temperature of the aftercooling system (using -35°C saline) combined with the possibility of a liquid seal at the lowest point of the vent line can lead to liquid-induced blockages.
This situation happens frequently! Currently, there are designs that do not use -35-degree saline, and such situations have not occurred.