Process and Apparatus for the Separation of Air by Cryogenic Distillation

Abstract

A process and apparatus for the separation of air by cryogenic distillation is provided.

1 - 11 . (canceled) 
     
     
         12 . A process for the production of at least one liquid product and at least one gaseous product by cryogenic distillation of air under a first mode of operation and a second mode of operation, wherein in all modes of operation the process comprises;
 cooling compressed and purified gaseous air in a heat exchange line,   sending said cooled compressed gaseous air to at least one column of a column system,   removing a liquid stream enriched in a component of air from a column of the column system,   vaporizing the removed liquid stream in the heat exchange line,   sending air at an elevated pressure to the heat exchange line, wherein it is condensed and sent to the column system   sending part of the feed air to one of at least two expanders and thereafter to a column of the column system wherein;
 a) according to the first mode, the process further comprises,
 removing at least part of the feed air from an intermediate point of the heat exchange line, 
 compressing the removed feed air at a cryogenic temperature in a cold compressor 
 sending the compressed cryogenic feed air to the heat exchange line to be further cooled, 
 sending the further cooled compressed cryogenic feed air to the column system, 
 sending part of the feed air to the first expander; and 
 
 b) according to the second mode, the process further comprises,
 compressing all of the feed air to a high pressure that is at least 20 bars higher than the highest column pressure of the column system in a second compressor, 
 cooling the compressed feed air in the heat exchange line, 
 sending a first part of the cooled compressed feed air to a column system, 
 sending a second part of the cooled compressed feed air to the second expander, and thereby 
 
   producing more liquid as final product during the second mode than during the first mode   
     
     
         13 . The process of  claim 12 , wherein according to the first mode, part of the feed air at the outlet pressure of the cold compressor is cooled and sent to the first expander. 
     
     
         14 . The process of  claim 12 , wherein the cold compressor is coupled to the first expander. 
     
     
         15 . The process of  claim 12 , wherein the second compressor is coupled to the second expander. 
     
     
         16 . The process of  claim 12 , wherein air treated in the second compressor in the second mode and in the cold compressor in the first mode is subsequently sent to a common transfer means upstream of the column system. 
     
     
         17 . The process of  claim 16 , wherein in the first mode the air is sent from the cold compressor to the heat exchange line via a conduit and in the second mode the air is sent from the second compressor to the second expander via the same conduit. 
     
     
         18 . The process of  claim 16 , wherein in the first mode the air is sent from the cold compressor via a passage of the heat exchange line to the cold end thereof and in the second mode the air is sent from the second compressor to the cold end of the heat exchange line via the same passage. 
     
     
         19 . An apparatus for the separation of air by cryogenic distillation comprising:
 a) a column system,   b) a heat exchange line,   c) a main compressor,   d) a cold compressor connected to the outlet of the main compressor,   e) a second compressor connected to the outlet of the main compressor,   f) first and second expanders,   g) means for sending air from the cold compressor to the first expander,   h) means for sending air from the second compressor to the second expander,   i) means for sending air from the first and second expanders to the column system, and   j) means for sending air from the cold compressor and the second compressor to the column system via the heat exchange means without traversing either of the first and second expanders.   
     
     
         20 . The apparatus of  claim 19 , wherein the means for sending air from the cold compressor to the first expander and means for sending air from the second compressor to the second expander include a common section of conduit. 
     
     
         21 . The apparatus of  claim 19 , wherein the means for sending air from the cold compressor and the second compressor to the column system via the heat exchange means without traversing either of the first and second expanders includes at least one common passage in the heat exchange means. 
     
     
         22 . The apparatus of  claim 19 , further comprising a third expander and means for sending air from the column system to the third expander and thence to the heat exchange means.