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 the olefin hydrocarbon rich compressed effluent vapor stream into a heat exchanger;
• b. cooling the olefin hydrocarbon rich compressed effluent vapor stream in the heat exchanger;
• c. separating hydrogen from olefin and heavy paraffinic components in the cooled olefin hydrocarbon rich 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 to produce a gas product;
• g. lowering the pressure of the first liquid stream in a first control valve to provide a pressure-reduced first liquid stream;
• h. dividing the second liquid stream into a first liquid split stream and a second liquid split stream;
• i. lowering the pressure of the first liquid split stream in a second control valve to provide a pressure-reduced first liquid split stream;
• j. warming the pressure-reduced first liquid split stream in the heat exchanger to provide a partially vaporized stream;
• k. lowering the pressure of the second liquid split stream in a third control valve to provide a pressure-reduced second liquid split stream;
• l. combining the pressure-reduced first liquid stream and the partially vaporized stream to provide a combined liquid stream;
• m. flashing the combined liquid stream in a liquid product drum to provide a hydrogen-rich gas, which travels to a rectifier connected to the liquid product drum;
• n. combining the hydrogen-rich gas and the pressure-reduced second liquid split stream in the rectifier, further purifying the hydrogen-rich gas;
• o. warming a third vapor stream exiting from the rectifier in the heat exchanger to provide a flashed vapor stream;
• p. pumping a third liquid stream from the liquid product drum to the heat exchanger, wherein it is warmed to provide a liquid product;
• q. providing a liquid paraffinic stream;
• r. dividing the liquid paraffinic stream into a plurality of split streams;
• s. lowering the pressure of the plurality of split streams in a plurality of control valves to provide a plurality of pressure-reduced split streams;
• t. introducing the plurality of pressure-reduced split streams into a plurality of thermosiphon vessels, respectively, to provide a plurality of vapor paraffinic streams and a plurality of secondary liquid paraffinic streams;
• u. circulating the plurality of secondary liquid paraffinic streams from bottoms of the plurality of thermosiphon vessels, through the heat exchanger, and then back to upper inlets of the plurality of thermosiphon vessels, wherein the heat exchanger partially vaporizes the plurality of secondary liquid paraffinic streams to provide cooling to warm streams in the heat exchanger, and to further provide a plurality of two-phase paraffinic streams, wherein a vapor phase of each of the plurality of two-phase paraffinic streams combines with each of the plurality of vapor paraffinic streams, and wherein a liquid phase of each of the plurality of two-phase paraffinic streams combines with each of the plurality of secondary liquid paraffinic streams;
• v. heating each of the plurality of vapor paraffinic streams in the heat exchanger to provide a plurality of heated vapor paraffinic streams;
• and
• W. combining each of the plurality of heated vapor paraffinic streams to provide a combined feed stream, wherein each of the plurality of heated vapor paraffinic streams are optionally compressed by one or more compressors, respectively, prior to being combined, and
• wherein cooling of the olefin hydrocarbon rich compressed effluent vapor stream and the first vapor stream in the heat exchanger is provided by various streams in the heat exchanger and a refrigeration system comprising:
• a mixed refrigerant composition;
• at least one refrigerant compressor;
• at least one discharge cooler;
• at least one discharge vapor/liquid separator;
• and
• at least one control valve.