초록 ▼

A process is disclosed for the recovery of hydrogen and C 6 -plus product hydrocarbons from the effluent stream of a hydrogen-producing hydrocarbon conversion process. The effluent stream of the reaction zone is partially condensed to remove the bulk of the heavy C 6 -plus hydrocarbons, which are th

A process is disclosed for the recovery of hydrogen and C 6 -plus product hydrocarbons from the effluent stream of a hydrogen-producing hydrocarbon conversion process. The effluent stream of the reaction zone is partially condensed to remove the bulk of the heavy C 6 -plus hydrocarbons, which are then sent to a fractionation zone. The remaining vapor is compressed to a substantially higher pressure. The compressed vapor is then passed into a membrane separation zone in which a hydrogen-rich stream is separated from the compressed vapor. The relatively high pressure nonpermeate portion of the vapor stream which emerges from the membrane separation zone is partially condensed by autorefrigeration. The still high pressure mixed phase fluid is separated into vapor and liquid portions. The liquid phase material is then flashed to produce coolant used to perform the partial condensation.

대표청구항 ▼

1. A process for the recovery of hydrogen from a vapor phase stream derived from a reactor effluent of a hydrocarbon conversion process which comprises the steps of: (a) compressing a vapor phase first process stream which comprises hydrogen and C 1 -C 3 hydrocarbons; (b) passing the first proce

1. A process for the recovery of hydrogen from a vapor phase stream derived from a reactor effluent of a hydrocarbon conversion process which comprises the steps of: (a) compressing a vapor phase first process stream which comprises hydrogen and C 1 -C 3 hydrocarbons; (b) passing the first process stream into a membrane separation zone in which the first process stream is contacted with at least one selective membrane through which hydrogen selectively permeates and thereby producing a hydrogen-rich product stream which is removed from the process and a vapor phase second process stream which comprises C 1 -C 3 hydrocarbons; (c) forming a vapor phase third process stream comprising methane and a liquid phase fourth process stream which comprises ethane and propane by partially condensing the second process stream by indirect heat exchange against a cooling medium followed by vapor-liquid separation; (d) flashing the fourth process stream to a substantially lower pressure and thereby forming a vapor phase sixth process stream, which comprises methane and a liquid phase fifth process stream, which comprises propane; (e) employing the fifth process stream to cool the second process stream; and (f) removing the fifth and sixth process streams from the process. 2. The process of claim 1 further characterized in that the pressure of the fourth process stream prior to being flashed is within 75 psi of the pressure of the first process stream as it is passed into the membrane separation zone. 3. A process for the recovery of hydrogen from the effluent stream of a hydrogen-producing hydrocarbon conversion process which comprises the steps of: (a) separating a reaction zone effluent stream, which comprises hydrogen and a mixture of C 1 -C 7 hydrocarbons, into a vapor phase first process stream, which comprises hydrogen and C 1 -C 3 hydrocarbons, and a condensate stream, which comprises C 6 -plus hydrocarbons, in a first vapor-liquid separation zone; (b) passing the condensate stream into a fractionation zone in which a C 6 -plus product of the hydrocarbon conversion process is recovered; (c) compressing the first process stream to a pressure above about 300 psig; (d) passing the first process stream into a membrane separation zone in which the first process stream is contacted with semi-permeable membrane which selectively allows the permeation of hydrogen and thereby producing a hydrogen-rich product stream which is removed from the process and a vapor phase second process stream which comprises C 1 -C 3 hydrocarbons; (d) forming a vapor phase third process stream, which comprises methane, and a liquid phase fourth process stream, which comprises ethane and propane by partially condensing the second process stream by indirect heat exchange against a cooling medium followed by vapor-liquid separation in a second vapor-liquid separation zone at a pressure above about 300 psig; (e) flashing the fourth process stream to a substantially lower pressure and thereby forming a vapor phase sixth process stream, which comprises methane, and a liquid phase fifth process stream, which comprises propane, with the fourth and fifth process streams being substantially cooler than the second process stream; (f) employing the fifth process stream as at least a part of the previously referred to coolant medium used to partially condense the second process stream; and (g) withdrawing the fifth process stream and the sixth process stream from the process. 4. The process of claim 3 further characterized in that the reaction zone effluent stream comprises benzene and toluene which are recovered as products of the hydrocarbon conversion process in the fractionation zone. 5. The process of claim 4 further characterized in that benzene is removed from the first process stream by contact with an absorption liquid after the first process stream has been compressed and prior to the passage of the first process stream into the membrane separation zone. 6. The process of claim 5 further characterized in that substantially all C 6 -plus aromatic compounds are removed from the first process stream prior to the passage of the first process stream into the membrane separation zone. 7. The process of claim 3 further characterized in that the first process stream is compressed from a pressure less than 70 psig to a pressure greater than 430 psig prior to passage into the membrane separation zone. 8. A process for the separation of the effluent stream of a dehydrocyclodimerization process which comprises the steps of: (a) partially condensing a vapor phase dehydrocyclodimerization reaction zone effluent stream, which comprises hydrogen, methane, ethane, propane, butane, benzene, toluene and xylene, and separating the resultant fluids in a first vapor-liquid separation zone into a vapor phase first process stream, which comprises hydrogen and C 1 -C 7 hydrocarbons, and a condensate stream which comprises benzene, toluene and xylenes; (b) passing the condensate stream into a fractionation zone, and recovering benzene, toluene and xylenes from the fractionation zone; (c) compressing the first process stream to a pressure above about 430 psig; (d) removing benzene from the first process stream in an absorption zone; (e) passing the first process stream into a membrane separation zone in which the first process stream is contacted with a hydrogen selective permeation membrane under membrane separation conditions, and thereby producing a hydrogen-rich effluent stream which is removed from the process and a vapor phase second process stream, which comprises methane, ethane and propane; (f) forming a vapor phase third process stream comprising methane and a liquid phase fourth process stream, comprising ethane and propane, by partially condensing the second process stream by indirect heat exchange against a coolant medium followed by vapor-liquid separation in a second separation zone operated at a pressure above about 400 psig; (g) flashing the fourth process stream to substantially lower pressure and thereby forming a vapor phase sixth process stream comprising methane, and a liquid phase fifth process stream, which comprises propane, with the fifth and sixth process streams being substantially cooler than the second process stream; and (h) employing the fifth process stream as at least a part of the previously referred to coolant medium used to partially condense the second process stream. 9. The process of claim 8 further characterized in that at least a portion of the fifth process stream is passed into the dehydrocyclodimerization reaction zone as a recycle stream. 10. The process of claim 9 further characterized in that the condensate stream comprises propane, propane present in the condensate stream is concentrated into a net overhead stream within the fractionation zone, and in that at least a part of the net overhead stream is passed into the dehydrocyclodimerization reaction zone. 11. The process of claim 10 further characterized in that a liquid phase stream comprising C 7 -plus hydrocarbons is produced in the fractionation zone and passed into the absorption zone as a lean absorption liquid for the purpose of removing toluene from the vapor phase first process stream. 12. The process of claim 11 further characterized in that the second vapor-liquid separation zone is operated at a pressure within 75 psi of the pressure of the first process stream as it enters the membrane separation zone.