Dehydrogenation separation unit with mixed refrigerant cooling

A method for separating olefinic hydrocarbon and hydrogen in an effluent fluid stream from a dehydrogenation reactor comprising the steps of:

• a. partially condensing the effluent fluid stream so that a mixed phase effluent stream is formed;
• b. separating the mixed phase effluent stream into a separated vapor stream containing hydrogen and a separated liquid stream containing an olefin product;
• c. dividing the separated vapor stream as a single phase vapor stream into a recycle gas stream and a net vapor stream, wherein both of the recycle gas stream and the net vapor stream are single phase vapor streams;
• d. combining at least a portion of the recycle gas stream with a propane stream that is independent of the effluent stream to form a combined stream;
• e. warming the net vapor stream, the combined stream, the separated liquid stream and a refrigerant stream to provide refrigeration for partially condensing the effluent fluid stream.

A system for separating an olefinic hydrocarbon and hydrogen in an effluent fluid stream from a dehydrogenation reactor comprising:

• a. a main heat exchanger configured to receive and partially condense the effluent fluid stream so that a mixed phase effluent stream is formed;
• b. a separation system configured to receive and separate the mixed phase effluent stream into a separated vapor stream including hydrogen and a separated liquid stream including an olefinic hydrocarbon;
• c. a split configured to receive and divide the separated vapor stream as a single phase vapor stream into a recycle gas stream and a net vapor stream, wherein both of the recycle gas stream and the net vapor stream are single phase vapor streams;
• d. a junction configured to receive and combine a propane stream, where the propane stream is independent of the effluent stream, and at least a portion of the recycle gas stream so that a combined stream is formed;
• e. said main heat exchanger configured to receive and warm the net vapor stream, the combined stream and the separated liquid stream to provide refrigeration in the main heat exchanger;
• f. a refrigerant compression system configured to provide refrigeration in the main heat exchanger.