Process for separating hydrogen from an olefin hydrocarbon effluent vapor stream

1. 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.

2. The process of claim 1 , wherein the warm section and the cold section each comprise one or more brazed aluminum heat exchanger cores.

3. The process of claim 1 , which further comprises combining one or more liquid paraffinic side streams with the combined feed.

4. The process of claim 3 , which includes employing a booster compressor to provide additional pressure to the compressed second vapor stream from the first compressor.

5. The process of claim 3 , which includes mounting the first expander, the second expander, the first compressor, and the second expander to a bull gear.

6. The process of claim 5 , which includes employing a motor to drive the bull gear.

7. The process of claim 3 , which includes driving one or more electric generators by the power produced in the first expander, second expander, or both expanders.

8. The process of claim 3 , wherein the one or more liquid paraffinic side streams comprises two liquid paraffinic side streams.

9. The process of claim 8 , which includes employing a booster compressor to provide additional pressure to the compressed second vapor stream from the first compressor.

10. The process of claim 8 , which includes mounting the first expander, the second expander, the first compressor, and the second expander to a bull gear.

11. The process of claim 10 , which includes employing a motor to drive the bull gear.

12. The process of claim 8 , which includes driving one or more electric generators by the power produced in the first expander, second expander, or both expanders.