Olefin separation and demethanization tower for methanol to olefins process
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This post was last edited by liaifeng on 2018-7-29 at 15:32. Do any experts have good methods to reduce the ethylene content at the top of the demethanizer to below 1%, with the design target being below 2.5%? Are there any effective strategies to achieve an even lower level? It has now dropped to 1.3%; I have no other options, seeking help.
It is already in operation; do you want to further reduce ethylene losses? Generally, this involves increasing the reflux ratio and lowering the reflux temperature. Increasing the reflux ratio is more effective. Additionally, reducing the feed rate to the demethanizer is also an option. However, a comparison is needed to determine whether these measures, which all increase energy consumption, are worthwhile when weighed against the reduction in ethylene losses.
Increase the reflux ratio and the number of trays.
I’m not sure what your manufacturing process is
Pre-depropanization followed by hydrogenation, Lummus process
3.jpg Our unit is a DMTO plant; to reduce ethylene losses, the top of the demethanization tower is flushed with propane! I wonder what your propane flow rate is?
Generally, increasing the reflux is necessary; for processes that involve propane washing, the amount of propane used can be increased accordingly. In our case, propane washing is available, so this approach can be employed, but it’s difficult to maintain balance when the load is high, making control challenging. Control is mainly carried out based on the temperature at the top of the tower
DMTO unit, using propane washing to reduce ethylene loss
It is necessary to comprehensively evaluate the relationship between ethylene loss and the increased energy consumption resulting from higher propane levels