On the issue of recycling LPG containing DME in the catalytic cracking riser
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The gas coming out of the alkylation light-end removal tower contains about 2% dimethyl ether; it currently enters the catalytic absorption stabilization unit for the recovery of liquefied gas, which results in an excess level of dimethyl ether in the catalytically liquefied gas. This in turn leads to an excess level of propyl dimethyl ether, preventing the domestically produced propane from being used in propane dehydrogenation. Now, I wonder whether recycling this portion of the gas through a catalytic riser can cause the dimethyl ether to react and decompose. Please ask a professional for clarification.
The possibility of dimethyl ether decomposing during catalytic cracking is very low; the absorption and stabilization stages, as well as the subsequent desulfurization and gas separation processes, cannot remove dimethyl ether. It is recommended to separate this process from the catalytic unit or to consider other processes instead. It is even less likely for dimethyl ether to decompose in the riser, as dimethyl ether has a very stable structure. Even if it were possible to deepen the reaction depth, one must also consider the increase in dry gas, coke formation, and losses; the costs would outweigh the benefits.
I consulted a research-oriented supervisor, and he said that 400-odd degrees is fine. I didn’t feel comfortable saying anything more. But the company thought the professor was right, and arranged for me to carry out the modifications; it was a very difficult task. I also have no better methods or academic support to prove whether he can actually be decomposed or not; I don’t know what to do.
It is recommended that you keep working on improving the process for use in the lift pipe; conversion should be no problem