Oil and water remain emulsified and do not separate
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In the cold high-pressure and cold low-pressure vessels of the residue hydrocracking unit, oil-water emulsion does not separate; water is often present in the cold low-pressure oil. This leads to fluctuations in the atmospheric pressure tower and results in substandard products. Could everyone please analyze the reasons for this failure to separate oil from water, as well as possible solutions? Our production parameters are: high-pressure water injection at 52 tons per hour (design value: 56), with a temperature of 42 degrees. Cold low-pressure water injection at 5 tons/hour (design rate), temperature 45.
Our residue unit has also had problems with poor oil-water separation for some time; I’ll ask around for you.
In our case, the residue is due to a slightly smaller design for the hot high-pressure section, along with a higher liquid level control, which causes the heavier components to enter the cold high-pressure section; the similar densities make separation difficult. The situation improved somewhat after the liquid level was adjusted to 50. It’s also possible that there is an issue with the internal components within your high-pressure system, which could also lead to poor oil-water separation.
It’s possible that there is too much sludge in the high-pressure coalescer, resulting in incomplete separation of oil and water. It is recommended to remove the coalescer and clean it during shutdown. Sometimes it also depends on the type of raw material; for some types, it is difficult to separate oil from water.