Systems and methods for low-temperature gas separation

Abstract

One of the drawbacks common to many currently available low-temperature gas mixture separation techniques is that known systems and methods that embody the techniques are inefficient. In contrast to known systems and methods for low-temperature gas mixture separation, some embodiments of the present invention provide a system for low-temperature gas mixture separation that recycles energy and reduces power consumption by re-circulating heated and/or cooled flows (e.g. gas, liquid and mixed-phase flows) within the system. Accordingly, in some embodiments efficiency is somewhat improved, as compared to comparable systems that do not include the re-circulation of heat energy. In some embodiments the heat energy that is re-circulated is a combination of heat added to the system (i.e. inputs to the system) and heat released within the system (i.e. byproducts from within the system) that are subsequently recovered. In particular, some systems and methods provided in accordance with embodiments of the invention are suited for separating the constituent components of natural gas and other hydrocarbon gas mixtures.

1 . A method of low-temperature gas mixture separation, suitable for separating components of a hydrocarbon gas mixture, comprising: 
 cooling a gas mixture;    condensing a gas mixture to produce a liquid stream and a gas/vapor;    rectifying at least a portion of the liquid stream thereby producing respective gas-phase products;    transferring heat energy to or from at least one of the liquid stream, the gas/vapor stream and gas-phase products from or to at least another one of the gas mixture, the liquid stream, the gas/vapor stream, gas-phase products and another flow in order to recycle energy.    
   
   
       2 . A method according to  claim 1 , further comprising: 
 expanding and swirling the gas/vapor stream to produce first and second flows, wherein the first flow primarily includes heavy components of the gas/vapor stream and the second flow primarily includes lighter components of the gas/vapor stream; and    transferring heat energy to or from at least one of the liquid stream, the gas/vapor stream, gas-phase products and the first and second flows from or to at least another one of the gas mixture, the liquid stream, the gas/vapor stream, gas-phase products, the another flow and the first and second flows in order to recycle energy.    
   
   
       3 . A method according to  2  further comprising rectifying at least a portion of the first flow in conjunction with the liquid stream.  
   
   
       4 . A method according to  claim 2  wherein cooling the gas mixture includes at least partially mixing the gas mixture with at least a portion of at least one of the liquid stream, the gas/vapor stream, gas-phase products, the another flow and the first and second flows.  
   
   
       5 . A method according to  claim 2 , wherein cooling the gas mixture includes at least partially transferring heat from the gas mixture to at least a portion of at least one of the liquid stream, the gas/vapor stream, gas-phase products, the another flow and the first and second flows.  
   
   
       6 . A method according to  claim 2 , further comprising compressing at least a portion of the gas-phase products.  
   
   
       7 . A method according to  claim 2  further comprising cooling at least a portion the gas/vapor stream.  
   
   
       8 . A method according to  claim 2 , further comprising compressing at least a portion of the first flow.  
   
   
       9 . A method according to  claim 2 , further comprising compressing at least a portion of the second flow.  
   
   
       10 . A method according to  claim 2 , further comprising cooling at least a portion of the first flow.  
   
   
       11 . A method according to  claim 10 , further comprising cooling at least a portion of the second flow.  
   
   
       12 . A method according to  claim 1 , wherein the transfer of heat energy includes mixing at least a portion of the at least two streams or flows between which the heat is transferred.  
   
   
       13 . A method according to  claim 1 , wherein the transfer of heat energy includes exchanging heat energy without mixing the at least two streams or flows between which the heat is transferred.  
   
   
       14 . A method according to  claim 1 , further comprising passing at least a portion of the gas/vapor stream through a turbine.  
   
   
       15 . A method according to  claim 1 , further comprising passing at least a portion of the second flow through a turbine.  
   
   
       16 . A method according to  claim 1 , further comprising condensing at least a portion of the gas-phase products.  
   
   
       17 . A method according to  claim 1 , further comprising further condensing at least a portion of the liquid stream.  
   
   
       18 . A method according to  claim 1 , further comprising condensing at least a portion of the gas/vapor stream.  
   
   
       19 . A method according to  claim 1 , further comprising expanding and swirling at least a portion of the gas-phase products.  
   
   
       20 . A system for low-temperature gas mixture separation, suitable for separating components of a hydrocarbon gas mixture, comprising: 
 a first gas/liquid separator for separating an incoming gas mixture into a liquid stream and a gas/vapor stream;    a first expander, for producing first and second flows, coupled the first gas/liquid separator to receive the gas/vapor stream, the first expander also including a swirling means for swirling the gas/vapor stream to thereby separate heavy components of the gas/vapor stream from the light components of the gas/vapor stream, wherein the heavy components primarily comprise the first flow and the lighter components primarily comprise the second flow;    a rectifying tower, for producing at least gas-phase products, coupled to the first gas/liquid separator to receive the liquid stream; and    at least one heat exchanger for transferring heat energy to or from at least one of the liquid stream, the gas/vapor stream, gas-phase products and the first and second flows from or to at least another one of the gas mixture, the liquid stream, the gas/vapor stream, gas-phase products, the another flow and the first and second flows in order to recycle energy within the system.    
   
   
       21 . A system according to  claim 20  wherein the first expander is coupled to the rectifying tower to provide at least a portion of the first flow to the rectifying tower.  
   
   
       22 . A system according to  claim 21 , further comprising a first mixer for mixing the incoming gas mixture with a feedback flow, the feedback flow comprising at least a portion of at least one the liquid stream, the gas/vapor stream, gas-phase products, the first and second flows and another flow.  
   
   
       23 . A system according to  claim 22 , further comprising a first compressor for compressing at least a portion of the gas-phase products.  
   
   
       24 . A system according to  claim 22 , further comprising a first compressor for compressing at least a portion of the gas/vapor stream.  
   
   
       25 . A system according to  claim 22 , further comprising a first compressor for compressing at least a portion of the first flow.  
   
   
       26 . A system according to  claim 22 , further comprising a first compressor for compressing at least a portion of the second flow.  
   
   
       27 . A system according to  claim 20 , further comprising a first chiller for cooling at least a portion of the first flow.  
   
   
       28 . A system according to  claim 20 , further comprising a first chiller for cooling at least a portion of the second flow.  
   
   
       29 . A system according to  claim 20 , wherein the transfer of heat energy includes mixing at least a portion of the at least two streams or flows between which the heat is transferred.  
   
   
       30 . A system according to  claim 20 , wherein the transfer of heat energy includes exchanging heat energy without mixing the at least two streams or flows between which the heat is transferred.  
   
   
       31 . A system according to  claim 20 , further comprising a turbine, for expanding at least a portion of the gas/vapor stream, coupled to the first gas/liquid separator to receive at least a portion of the gas/vapor stream.  
   
   
       32 . A system according to  claim 20 , further comprising a turbine through which at least a portion of the second flow passes, the turbine coupled to receive at least a portion of the second flow.  
   
   
       33 . A system according to  claim 20 , further comprising at least one other gas/liquid separator for separating at least one of a liquid or a gas/vapor stream within the system.  
   
   
       34 . A system according to  claim 20 , further comprising another condenser for further condensing at least a portion of the liquid stream.  
   
   
       35 . A system according to  claim 20 , further comprising another condenser for condensing at least a portion of the gas/vapor stream.  
   
   
       36 . A system according to  claim 20 , further comprising another expander for expanding and swirling at least a portion of the gas-phase products.