Overhead recycle process apparatus and method of overhead recycle processing of hydrocarbons

Abstract

An overhead recycle process apparatus (100) comprises a heat exchange arrangement (116, 118, 120, 146, 150, 198) and a separator (110) in fluid communication with an absorber (104) and a de-ethaniser (106), the absorber (104) having a reflux inlet port (164). An ethane rectifier (170) in fluid communication with the de-ethaniser (106) is also provided, the de-ethaniser (106) being arranged to provide cooling by heat exchange to an overhead stream path (194) of the ethane rectifier (170). The ethane rectifier (170) comprises a reflux drum (182) having an ethane outlet port (184) and a vapour phase outlet port (185) in fluid communication with the reflux inlet port (164) of the absorber (104).

1 . An overhead recycle process apparatus ( 100 ) comprising:
 a heat exchange arrangement ( 116 ,  118 ,  120 ,  146 ,  150 ,  198 );   a separator ( 110 ) in fluid communication with an absorber ( 104 ) and a de-ethaniser ( 106 ), the absorber ( 104 ) having a reflux inlet port ( 164 ); and   an ethane rectifier ( 170 ) in fluid communication with the de-ethaniser ( 106 ), the de-ethaniser ( 106 ) being arranged to provide cooling by heat exchange to an overhead stream path ( 194 ) of the ethane rectifier ( 170 ); and   the ethane rectifier ( 170 ) comprises a reflux drum ( 182 ) having an ethane outlet port ( 184 ) and a vapour outlet port ( 185 ) in fluid communication with the reflux inlet port ( 164 ) of the absorber ( 104 ).   
     
     
         2 . An apparatus as claimed in  claim 1 , wherein the de-ethaniser ( 106 ) comprises a bottom product outlet port ( 197 ) arranged to provide hydrocarbon fractions having a molecular weight heavier than a molecular weight of ethane. 
     
     
         3 . An apparatus as claimed in  claim 1 , further comprising:
 a side stream circuit ( 172 ,  174 ,  176 ,  178 ,  180 ); wherein   the de-ethaniser ( 106 ) comprises a side stream inlet port ( 172 ) and a side stream outlet port ( 174 ), the side stream outlet port ( 174 ) being disposed above the side stream inlet port ( 172 ) of the de-ethaniser ( 106 );   the ethane rectifier ( 170 ) comprises a rectifier bottom product inlet port ( 176 ), a rectifier bottom product outlet port ( 178 ) and a bottom product reservoir ( 180 );   the side stream circuit ( 172 ,  174 ,  176 ,  178 ,  180 ) extends from the side stream outlet port ( 174 ) into the bottom product reservoir ( 180 ) via the rectifier bottom product inlet port ( 176 ) and returns to the side stream inlet port ( 172 ) via the rectifier bottom product outlet port ( 178 ); and   the side stream outlet port ( 174 ) is located at a location along the de-ethaniser ( 170 ) corresponding to an expected presence of elevated levels of ethane content in the de-ethaniser ( 106 ).   
     
     
         4 . An apparatus as claimed in  claim 1 , wherein the reflux drum ( 182 ) of the ethane rectifier ( 170 ) comprises a reflux inlet port ( 186 ) and a rectification portion ( 190 ) of the ethane rectifier ( 170 ) comprises an overhead stream outlet port ( 192 ), the overhead stream path ( 194 ) extending from the overhead stream outlet port ( 192 ) to the reflux inlet port ( 186 ) via the heat exchange arrangement ( 120 ) so as to define an ethane reflux path. 
     
     
         5 . An apparatus as claimed in  claim 4 , wherein
 the de-ethaniser ( 106 ) comprises a primary reflux inlet port ( 154 ), a secondary reflux inlet port ( 161 ) and an overhead stream outlet port ( 156 );   a primary de-ethaniser reflux path ( 158 ) extends from the overhead stream outlet port ( 156 ) of the de-ethaniser ( 106 ) to the primary reflux inlet port ( 154 ) of the de-ethaniser ( 106 ) via the heat exchange arrangement ( 118 ) and the separator ( 110 );   a secondary de-ethaniser reflux path ( 159 ) branching from the primary de-ethaniser reflux path ( 158 ) and extending to the secondary reflux inlet port ( 161 ) via the heat exchange arrangement ( 120 ); and   the heat exchange arrangement ( 120 ) comprises an ethane reflux heat exchanger ( 120 ), the secondary de-ethaniser reflux path ( 159 ) and the ethane reflux path passing through the ethane reflux heat exchanger ( 120 ).   
     
     
         6 . An apparatus as claimed in  claim 1 , further comprising:
 a lean gas outlet path ( 142 );   a lean gas outlet port ( 144 ) in fluid communication with the lean gas outlet path ( 142 ); wherein   the heat exchange arrangement ( 116 ,  118 ,  120 ,  146 ,  150 ,  198 ) comprises a first heat exchanger ( 116 ) and a second heat exchanger ( 118 ); and   a compressor ( 112 ); wherein   the lean gas outlet path ( 142 ) extends from an overhead stream outlet port ( 140 ) of the absorber to the lean gas outlet port ( 144 ), passing through the second heat exchanger ( 118 ) and the first heat exchanger ( 116 ); and   the compressor ( 112 ) is in the lean gas outlet path ( 142 ) after the first heat exchanger ( 116 ).   
     
     
         7 . An apparatus as claimed in  claim 6 , further comprising:
 a gas feed inlet port ( 102 );   another separator ( 108 ) having an inlet port in fluid communication with the gas feed inlet port ( 102 ) via the first heat exchanger ( 116 ), the another separator ( 108 ) having a vapour outlet port and a liquid outlet port.   
     
     
         8 . An apparatus as claimed in  claim 7 , further comprising:
 an expander ( 114 ) operably coupled to the compressor ( 112 ); wherein   the vapour outlet port of the another separator ( 108 ) is in fluid communication with the expander ( 114 ) and the expander ( 114 ) is in fluid communication with a bottom product reservoir of the absorber ( 104 ); and   the liquid outlet port of the another separator ( 108 ) is in fluid communication with a first feed inlet port ( 126 ) of the de-ethaniser ( 106 ).   
     
     
         9 . An apparatus as claimed in  claim 6 , further comprising:
 a second feed fluid path ( 130 ) in fluid communication at one end thereof with a bottom fraction outlet port ( 132 ) of the absorber ( 104 ) and in fluid communication at another end thereof with a second feed inlet port ( 134 ) of the de-ethaniser ( 106 ); wherein   the second feed fluid path ( 130 ) passes through the first heat exchanger ( 116 ).   
     
     
         10 . An apparatus as claimed in  claim 6 , wherein the separator ( 110 ) comprises a vapour outlet port and a liquid outlet port, the vapour outlet port being in fluid communication with the reflux inlet port ( 164 ) of the absorber ( 104 ) via the second heat exchanger ( 118 ) and the liquid outlet port being in fluid communication with the primary reflux inlet port ( 154 ) of the de-ethaniser ( 106 ). 
     
     
         11 . An apparatus as claimed in  claim 10 , wherein the overhead outlet stream port ( 156 ) of the de-ethaniser ( 106 ) is in fluid communication with an inlet port of the separator ( 110 ) via the second heat exchanger ( 118 ). 
     
     
         12 . An apparatus as claimed in  claim 1 , wherein
 the de-ethaniser ( 106 ) comprises a bottom fraction reservoir ( 195 ), and a bottom fraction inlet port ( 196 ) and a bottom fraction outlet port ( 197 ) in fluid communication with the bottom fraction reservoir ( 195 ); and   a reboiler circuit path extends from the bottom fraction outlet port ( 197 ) and returns to the bottom fraction reservoir ( 195 ) via the bottom fraction inlet port ( 196 ), the reboiler circuit path passing through the heat exchange arrangement ( 198 ).   
     
     
         13 . An apparatus as claimed in  claim 1 , wherein the de-ethaniser ( 106 ) comprises a heavy hydrocarbon fractions outlet port ( 199 ) for hydrocarbon fractions having a molecular weight heavier than the molecular weight of ethane. 
     
     
         14 . An apparatus as claimed in  claim 6 , further comprising:
 a light fractions compression and cooling arrangement ( 112 ,  146 ,  148 ,  150 ) in fluid communication at a first end thereof with the lean gas outlet port ( 144 ) and at a second end thereof with the first heat exchanger ( 116 ); wherein   the compression and cooling arrangement ( 112 ,  146 ,  148 ,  150 ) comprises the compressor ( 112 ).   
     
     
         15 . A method of overhead recycle processing of hydrocarbons, the method comprising:
 drawing off ( 240 ) ethane from a de-ethaniser ( 106 );   rectifying the drawn off ethane in a rectifier ( 170 );   generating reflux ( 242 ) from an overhead stream path of the rectifier ( 170 ); and   introducing the reflux into a reflux drum ( 182 ) of the rectifier ( 170 ).