Cryogenic separation process for the recovery of components from the products of a dehydrogenation reactor

A process for the separation of an olefinic hydrocarbon and hydrogen in a compressed effluent vapor stream from a dehydrogenation reactor, which process comprises:

• a) partially condensing the compressed effluent vapor stream in a first warm heat exchanger having a warm end and a cold end;
• b) separating the partially condensed compressed effluent vapor stream in a first primary separator to provide a first vapor product and a first liquid olefinic product;
• c) partially condensing the first vapor product in a second cold heat exchanger having a warm end and a cold end;
• d) separating the partially condensed first vapor product in a second separator to provide a second vapor product and a second liquid olefinic product;
• e) isentropically expanding, in a high pressure expander, the second vapor product to provide a third liquid olefin product and a third vapor product;
• f) reheating the third vapor product in the second cold heat exchanger;
• g) dividing the reheated third vapor product into a first portion and a second portion;
• h) reheating the first portion in the first warm heat exchanger and withdrawing a process vapor product comprising essentially hydrogen;
• i) expanding the second portion in a low pressure expander;
• j) reheating the expanded second portion in the second cold heat exchanger;
• k) subcooling a liquid paraffinic feed for use in the reactor in the first warm heat exchanger;
• l) combining the subcooled liquid paraffinic feed with the expanded reheated second portion to provide a combined stream;
• m) revaporizing the combined stream in the first warm heat exchanger;
• n) withdrawing the revaporized combined stream;
• o) combining the first, second, and third liquid olefinic products to provide a liquid combined stream;
• p) rewarming the liquid combined stream to an intermediate temperature between a warm end temperature and a cold end temperature in the first warm heat exchanger;
• q) flashing the rewarmed liquid combined stream in a liquid product drum to provide flashed vapor stream;
• r) pumping the flashed, rewarmed, liquid combined stream to a high pressure;
• s) reheating the pumped, high pressure, liquid combined stream in the first warm heat exchanger;
• and
• t) withdrawing the reheated, pumped, liquid combined stream from the first warm heat exchanger.