Where does the methanol in imported propane come from? How to remove it?
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The propane used as raw material in propane dehydrogenation units is generally imported from the Middle East, and this propane usually contains a certain amount of methanol. Where does this methanol come from? Is it related to the low-temperature storage of propane? What methods can be used to remove methanol here?
Since the imported propane is obtained from associated gas in oil fields and wet natural gas condensates, was methanol used in the earlier stages via the low-temperature methanol washing process to remove hydrogen sulfide and carbonyl sulfide, which is why the final propane product contains a certain amount of methanol?
Methanol can be removed using 13X molecular sieve, but attention must be paid to the content of unsaturated hydrocarbons to prevent safety accidents
Why do unsaturated hydrocarbons cause safety accidents? Could the endothermic nature of molecular sieves cause a spike in bed temperature?
Last year, I had discussions with a molecular sieve factory in Shanghai. They shared a case of an Iranian plant that used molecular sieves for desulfurization; it seems that the issue arose because the operating procedures were not followed, resulting in an excessively high concentration of olefins in the feed material. This not only generated adsorption heat but also could lead to the polymerization of olefins (which releases heat). Together, these factors caused the temperature to soar, ultimately destroying the reactor. I think so, I can’t remember clearly.
In that case, polypropylene plants have restrictions on the sulfur content in the raw materials; if desulfurization is required, molecular sieves cannot be used, right? It’s all olefins.