Process for separating hydrogen from an olefin hydrocarbon effluent vapor stream

A process for the separation of hydrogen from an olefin hydrocarbon rich compressed effluent vapor stream from a dehydrogenation unit, which process comprises:

• a. introducing a compressed effluent vapor stream into a processing unit;
• b. cooling a compressed effluent vapor stream in a heat exchanger, wherein the heat exchanger comprises a warm section and a cold section;
• c. separating hydrogen from olefin and heavy paraffinic components in the cooled compressed effluent vapor stream in a first separator to provide a first vapor stream and a first liquid stream;
• d. cooling the first vapor stream in the heat exchanger;
• e. separating hydrogen from olefin and heavy paraffinic components in the cooled first vapor stream in a second separator to provide a second vapor stream and a second liquid stream;
• f. warming the second vapor stream in the heat exchanger;
• g. isentropically expanding, in a first expander, the warmed second vapor stream, wherein the pressure and temperature of the warmed second vapor stream are lowered;
• h. warming the isentropically expanded second vapor stream in the heat exchanger;
• i. compressing, in a first compressor, the warmed, isentropically expanded second vapor stream;
• j. cooling the compressed second vapor stream in a first discharge cooler;
• k. dividing the cooled second vapor stream into a gas product and a split stream;
• l. withdrawing a gas product from the processing unit;
• m. compressing, in a second compressor, the split stream;
• n. cooling the compressed split stream in a second discharge cooler and further cooling the cooled split stream in the heat exchanger;
• o. isentropically expanding, in a second expander, the further cooled split stream, wherein the pressure and temperature of the further cooled split stream are lowered;
• p. cooling a liquid paraffinic stream in the heat exchanger;
• q. combining the cooled liquid paraffinic stream with the isentropically expanded split stream to provide a combined feed;
• r. vaporizing the combined feed in the heat exchanger;
• s. withdrawing the vaporized combined feed from the processing unit;
• t. lowering the pressure of the first liquid stream in a control valve;
• u. partially vaporizing the lowered-pressure first liquid stream in the heat exchanger;
• v. flashing the partially vaporized first liquid stream in a liquid product drum to provide a hydrogen-rich gas, wherein the hydrogen-rich gas travels to a rectifier connected to the liquid product drum;
• w. combining the hydrogen-rich gas and the second liquid stream in the rectifier, further purifying the hydrogen-rich gas;
• x. warming the purified hydrogen-rich gas from the rectifier in the heat exchanger to provide a flashed vapor stream;
• y. pumping a third liquid stream from the liquid product drum to the heat exchanger, wherein the third liquid stream is warmed;
• and
• z. providing a liquid product.