Process and device for recovering argon by low-temperature separation of air

Abstract

The process and the device are used for recovering argon by low-temperature separation of air. Process air ( 1 ) is compressed ( 3 ) and is introduced into a distilling-column system for nitrogen-oxygen separation ( 13, 14 ). An argon-containing stream ( 72 ) is removed in the distilling-column system for nitrogen-oxygen separation. The argon-containing stream ( 72 ) is sent to a crude argon column ( 25 ). The crude argon column ( 25 ) has a top condenser ( 24 ), in which a top gas from the crude argon column ( 25 ) is at least partially condensed. At least one part of the condensate that is recovered in this case is released as reflux liquid to the crude argon column ( 25 ). A crude argon stream ( 76, 176, 276 a, 276 b ) is removed from the crude argon column ( 25 ) or the top condenser ( 24 ). The crude argon stream ( 76, 176, 276 a, 276 b ) is sent to a pure argon column ( 20 ). A pure argon product stream ( 81 ) is removed from the pure argon column ( 20 ). The top condenser ( 24 ) of the crude argon column ( 25 ) is designed as a reflux condenser, and top gas from the crude argon column is introduced into the reflux passages of the reflux condenser.

1 . In a process for recovering argon by low-temperature separation of air, in which
 Process air ( 1 ) is compressed ( 3 ) and is introduced into a distillation-column system for nitrogen-oxygen separation ( 13 ,  14 ),   An argon-containing stream ( 72 ) is removed from said distillation-column system for nitrogen-oxygen separation,   The argon-containing stream ( 72 ) is sent to a crude argon column ( 25 ),   The crude argon column ( 25 ) has a top condenser ( 24 ), formed by at least one plate heat exchanger block, which has liquefaction passages and evaporation passages,   A top gas from the crude argon column ( 25 ) is introduced into the liquefaction passages of the top condenser and is at least partially condensed there,   At least one part of the condensate that is recovered in this case is released as reflux liquid to the crude argon column ( 25 ),   The top condenser represents the only source for reflux of the crude argon column,   A liquid coolant is sent to the evaporation passages at a first end and is partially evaporated there,   A mixture consists essentially of evaporated coolant and coolant that remains in liquid form is drawn off from a second end of the evaporation passages,   A crude argon stream ( 76 ,  176 ,  276   a ,  276   b ) is removed from the crude argon column ( 25 ) or the top condenser ( 24 ),   The crude argon stream ( 76 ,  176 ,  276   a ,  276   b ) is sent to a pure argon column ( 20 ), and   A pure argon product stream ( 81 ) is removed form the pure argon column ( 20 ), the improvement wherein the top condenser ( 24 ) of the crude argon column ( 25 ) is a reflux condenser having reflux passages, and top gas from the crude argon column is introduced into the reflux passages of the reflux condenser.   
   
   
       2 . A process according to  claim 1 , wherein the liquid coolant is returned to the evaporation passages at their lower end, and the mixture that consists essentially of evaporated coolant and coolant that remains in liquid form is drawn off from the lower end of the evaporation passages. 
   
   
       3 . A process according to  claim 1 , wherein the top condenser is formed by a single plate heat exchanger block. 
   
   
       4 . A process according to  claim 1 , wherein the crude argon stream ( 76 ,  276   b ) is drawn off from the upper area of the reflux passages. 
   
   
       5 . A process according to  claim 1 , wherein no residual gas stream is drawn off from the upper area of the crude argon column ( 25 ) and from the reflux passages. 
   
   
       6 . A process according to  claim 1 , wherein the crude argon stream ( 276   b ) is removed from the crude argon column or the top condenser ( 24 ) in gas form and is at least partially condensed upstream from its introduction ( 282 ) into the pure argon column ( 20 ) in an additional condenser ( 227 ). 
   
   
       7 . A process according to  claim 6 , wherein the top condenser ( 24 ) and the additional condenser ( 227 ) are condenser-evaporators, whereby the two evaporation passages are fed with the same coolant ( 23 ). 
   
   
       8 . A process according to  claim 7 , wherein the top condenser ( 24 ) and the additional condenser ( 227 ) are liquid bath evaporators and are arranged in the same liquid bath. 
   
   
       9 . A process according to  claim 1 , wherein the crude argon stream ( 176 ,  282 ) is released in the liquid state to the top of the pure argon column ( 20 ). 
   
   
       10 . A process according to  claim 1 , wherein a residual gas stream ( 78 ,  178 ,  278 ) is drawn off from the top of the pure argon column ( 20 ) or from the upper area of the reflux passages, and mixed with the process air, before compression ( 3 ). 
   
   
       11 . A process according to  claim 1 , wherein the reflux condenser comprises at least one heat exchanger block, in the form of a plate heat exchanger. 
   
   
       12 . Apparatus for recovering argon by low-temperature separation of air comprising
 An air compressor ( 3 ) for compressing process air ( 1 ),   Conduit for introducing the compressed process air ( 8 ,  10 ,  12 ) into a distillation-column system for nitrogen-oxygen separation ( 13 ,  14 ),   Conduit for removal of an argon-containing stream ( 72 ) from the distillation-column system for nitrogen-oxygen separation,   Conduit for introducing the argon-containing stream ( 72 ) into a crude argon column ( 25 ),   Said crude argon column ( 25 ) being mounted with a top condenser ( 24 ), is formed by at least one plate heat exchanger block, having liquefaction passages and evaporation passages,   Means for introducing a top gas from the crude argon column ( 25 ) into the liquefaction passages of the top condenser,   Means for releasing at least a portion of the condensate that is recovered in the top condenser ( 24 ) as a reflux liquid to the crude argon column ( 25 ),   Whereby the top condenser represents the only source for reflux of the crude argon column,   Means for introducing a liquid coolant into the evaporation passages at a first end of the top condenser,   Means for removing a mixture that consists essentially of evaporated coolant and coolant that remains in liquid form from the evaporation passages of a second end of the top condenser,   Conduit for removing a crude argon stream ( 76 ,  176 ,  276   a ,  276   b ) from the crude argon column ( 25 ) or the top condenser ( 24 ),   Means Conduit for introducing the crude argon stream ( 76 ,  176 ,  276   a ,  276   b ) into a pure argon column ( 20 ),   Means for removing a pure argon product stream ( 81 ) from the pure argon column ( 20 ),   wherein the top condenser ( 24 ) of the crude argon column ( 25 ) is a reflux condenser having means for introducing top gas of the crude argon column into the reflux passages of the reflux condenser.   
   
   
       13 . Apparatus according to  claim 12 , wherein the means for introducing a liquid coolant into the evaporation passages at the lower end of the top condenser and the means for removing a mixture that consists of evaporated coolant and coolant that remains in liquid form from the evaporation passages are arranged at the lower end of the top condenser. 
   
   
       14 . Apparatus according to  claim 12 , wherein the top condenser is comprises a single plate heat exchanger block. 
   
   
       15 . A process according to  claim 13 , wherein the crude argon stream ( 76 ,  276   b ) is drawn off from the upper area of the reflux passages.