Is there any vapor separation unit that doesn’t connect to the ethane tower?
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The carbon content in the feed gas used in our gas treatment unit has always been below 1% (usually around 0.3%), which results in a low load on the deethanization tower. The plant now wants to shut down this tower in order to save some steam and energy consumption. What are your opinions on this, dear colleagues?
It is possible to do so, but the deethanizer is not only used for removing C2 compounds; it also serves to remove water, thereby reducing the water content in the C3 compounds at the bottom of the tower (primarily propylene). The requirements for the water content in propylene are now very strict (10 ppm in our company); if the ethane removal tower is shut down, there will be no way to adjust the water content in propylene!
It causes difficulties in subsequent separation, and the costs outweigh the benefits.
In the event of an accident, if carbon dioxide enters the propylene tower, it will take a long time to deal with it, which is not worth the effort.
I want to know why the deethanization reflux tank can remove the most water
It should be an deethanizer, which primarily serves the function of dehydration; the moisture content in crude propylene can be kept below 10PPM, thus reducing the pressure on the polypropylene refining system.
So much carbon dioxide entering the propylene column reduces the quality of propylene; it is therefore necessary to vent it at the top of the column, which is not cost-effective. You can reduce the backflow, or operate at a lower tower pressure.
Is C2 in C3 not being removed? Do you plan to burn liquefied gas? A C3 failure means it can’t leave the factory. It consumes some steam, but it is necessary to ensure the quality of liquefied gas.
It’s better to keep it running. The deethanizer is primarily used to remove C2 compounds and water from the system; if it’s not turned on, any fluctuations will be difficult to handle, and the consequences would outweigh the benefits. Besides, heat transfer water is now being used in place of it
It can be tried; in our wax oil hydrocracking process, we don’t use an ethane removal tower, and the liquefied gas produced meets all the required standards