Hydrogen recovery in a distributed distillation system
A process for recovering hydrogen from a mixed hydrocarbon stream wherein the mixed hydrocarbon stream is subjected to a separation technique to produce a substantially hydrogen enriched stream, which is then recovered as hydrogen product. A process for providing refrigeration duty to the process is also disclosed, wherein a substantially methane enriched stream arising from the separation technique is expanded to provide cooling duty for the process.
1 . A process for recovering hydrogen comprising the steps of:
a. Introducing a mixed hydrocarbon feed stream comprising a mixture of hydrogen, methane, and C2 components into an ethylene distributor column to obtain a first stream;
b. Subjecting at least a portion of said first stream to a separation technique to produce a second stream substantially hydrogen enriched and substantially methane depleted and a third stream substantially hydrogen depleted and substantially methane enriched;
c. Recovering a hydrogen product from said second stream.
2 . The process of claim 1 wherein said first stream enters at least one partial condenser to provide at least a portion of the reflux to said ethylene distributor column prior to step (b).
3 . The process of claim 1 wherein said third stream is introduced into a second separation column to produce a fourth stream substantially methane enriched and a fifth stream substantially ethylene enriched.
4 . The process of claim 1 wherein said first stream comprises a mixture of hydrogen, C1, and ethylene and is substantially free of ethane.
5 . The process of claim 3 wherein said second separation column is a demethanizer.
6 . The process of claim 1 wherein said separation step comprises rectification, condensation, membrane separation, dephlegmation, adsorption, either individually or in combinations thereof.
7 . The process of claim 3 wherein said fourth stream comprises essentially little or no ethylene.
8 . A process for recovering hydrogen and providing refrigeration duty comprising the steps of:
a. Introducing a mixed hydrocarbon feed stream comprising a mixture of hydrogen, methane, and C2 components into an ethylene distributor to obtain a first stream;
b. Subjecting at least a portion of said first stream to a separation technique to produce a second stream substantially hydrogen enriched and substantially methane depleted and a third stream substantially hydrogen depleted and substantially methane enriched;
c. Introducing said third stream into a second separation column to recover a fourth stream substantially methane enriched;
d. Directing said fourth stream to an expansion device to produce a lower-temperature, lower pressure fifth stream
e. Reheating said lower-temperature, lower-pressure fifth stream to provide cooling duty to the overall process.
f. Recovering a hydrogen product from said second stream.
9 . The process of claim 8 wherein said first stream enters at least one partial condenser to provide at least a portion of the reflux to said ethylene distributor column prior to step (b).
10 . The process of claim 8 wherein said first stream comprises a mixture of hydrogen, C1, and ethylene and is substantially free of ethane.
11 . The process of claim 8 wherein said second separation column is a demethanizer.
12 . The process of claim 8 wherein said separation step comprises rectification, condensation, membrane separation, dephlegmation, adsorption, either individually or in combinations thereof.
13 . The process of claim 8 wherein said fourth stream comprises essentially little or no ethylene.
14 . The process of claim 8 wherein a portion of said second stream of step (b) may be directed to said expansion device of step (d).