Dehydrogenation Separation Unit with Mixed Refrigerant Cooling

Abstract

A system for separating olefinic hydrocarbon and hydrogen in an effluent fluid stream from a dehydrogenation reactor includes a heat exchanger that receives and partially condenses the effluent fluid stream so that a mixed phase effluent stream is formed. A primary separation device receives and separates the mixed phase effluent stream into a primary vapor stream and a primary liquid product stream. A heat exchanger receives and partially condenses the primary vapor stream so that a mixed phase primary stream is formed. A secondary separation device receives and separates the mixed phase primary stream into a secondary vapor stream and a secondary liquid product stream. A heat exchanger receives and warms the secondary vapor stream to provide refrigeration for partially condensing the effluent fluid stream and a heat exchanger receives and warms the secondary vapor stream to provide refrigeration for partially condensing the primary vapor stream. A mixed refrigerant compression system provides refrigerant to a heat exchanger to provide refrigeration

What is claimed is: 
     
         1 . A method for separating olefinic hydrocarbon and hydrogen in an effluent fluid stream from a dehydrogenation reactor comprising the steps of:
 a. partially condensing the effluent fluid stream so that a mixed phase effluent stream is formed;   b. separating the mixed phase effluent stream into a separated vapor stream containing hydrogen and a separated liquid product stream containing an olefin product;   c. combining a fresh feed stream and a first portion of the separated vapor stream so that a combined stream is formed;   d. warming the combined stream, the separated liquid stream and a refrigerant stream to provide refrigeration for partially condensing the effluent fluid stream.   
     
     
         2 . The method of  claim 1  wherein the fresh feed stream includes propane. 
     
     
         3 . The method of  claim 1  wherein the fresh feed stream includes n-butane. 
     
     
         4 . The method of  claim 1  wherein the refrigerant stream is a mixed refrigerant stream. 
     
     
         5 . The method of  claim 4  wherein the mixed refrigerant is primarily made up of methane, ethylene and propane. 
     
     
         6 . The method of  claim 1  further comprising the step of warming a second portion of the separated vapor stream to provide refrigeration for partially condensing the effluent fluid stream. 
     
     
         7 . The method of  claim 1  wherein the effluent fluid stream is a gas or vapor. 
     
     
         8 . A method for separating olefinic hydrocarbon and hydrogen in an effluent fluid stream from a dehydrogenation reactor comprising the steps of:
 a. partially condensing the effluent fluid stream so that a mixed phase effluent stream is formed;   b. separating the mixed phase effluent stream into a separated vapor stream containing hydrogen and a separated liquid stream containing an olefin product;   c. dividing at least a portion of the separated vapor stream into a recycle gas stream and a net vapor stream;   d. combining the recycle gas stream with a propane stream to form a combined stream;   e. warming the net vapor stream, the combined stream, the separated liquid stream and a refrigerant stream to provide refrigeration for partially condensing the effluent fluid stream.   
     
     
         9 . The method of  claim 8  wherein the refrigerant stream used in step e. includes a mixed refrigerant. 
     
     
         10 . The method of  claim 9  wherein the mixed refrigerant is primarily made up of methane, ethylene and propane. 
     
     
         11 . The method of  claim 9  wherein the mixed refrigerant is vaporized during step e so that a mixed refrigerant vapor stream is formed, and further comprising the steps of compressing and cooling the mixed refrigerant stream for reuse in step e. 
     
     
         12 . The method of  claim 8  wherein the effluent fluid stream is a gas or vapor. 
     
     
         13 . A method for separating olefanic hydrocarbon and hydrogen in an effluent fluid stream from a dehydrogenation reactor comprising the steps of:
 a. partially condensing the effluent fluid stream so that a mixed phase effluent stream is formed;   b. separating the mixed phase effluent stream into a separated vapor stream containing hydrogen and a separated liquid stream containing an olefin product;   c. dividing at least a portion of the separated vapor stream into a recycle gas stream and a net vapor stream;   combining the recycle gas stream with a fresh feed stream to form a combined stream;   e. warming the net vapor stream, the combined stream, the separated liquid stream and a refrigerant stream to provide refrigeration for cooling the effluent fluid stream.   
     
     
         14 . The method of  claim 13  wherein the refrigerant stream used in step e. includes a mixed refrigerant. 
     
     
         15 . The method of  claim 14  wherein the mixed refrigerant is primarily made up of methane, ethylene and propane. 
     
     
         16 . The method of  claim 14  wherein the mixed refrigerant is vaporized during step e so that a mixed refrigerant vapor stream is formed, and further comprising the steps of compressing and cooling the mixed refrigerant stream for reuse in step e. 
     
     
         17 . The method of  claim 13  wherein the fresh feed stream includes propane. 
     
     
         18 . The method of  claim 13  wherein the fresh feed stream includes n-butane. 
     
     
         19 . The method of  claim 13  wherein the effluent fluid stream is partially condensed during step e. 
     
     
         20 . The method of  claim 13  wherein the effluent fluid stream is a gas or vapor.