Process And Apparatus For The Separation Of Air By Cryogenic Distillation

Abstract

An apparatus for the separation of air by cryogenic distillation comprises a column system including a double column, an intermediate pressure column, and an argon column having a top condenser, a heat exchanger, means for pressurizing and vaporizing oxygen rich liquid and nitrogen rich liquid from the double column, conduits configured to: send argon enriched gas from the low pressure column to the argon column, remove argon rich fluid from the top of the argon column, send a liquid air stream at least in part to a top condenser of the intermediate pressure column where it is partially vaporized to form a vapor and a liquid, send the vapor formed in the top condenser of the intermediate pressure column to the low pressure column, and send the liquid from the top condenser of the intermediate pressure column to the intermediate pressure column to be separated.

1 - 15 . (canceled) 
     
     
         16 . A process for the separation of air by cryogenic distillation in a column system including a high pressure column, a low pressure column, the bottom of the low pressure column being thermally coupled with the top of the high pressure column, an intermediate pressure column, operating at a pressure between that of the high pressure column and that of the low pressure column, and an argon column, the method comprising the steps of:
 i) cooling a purified compressed air in a heat exchanger and sending at least in part to the high pressure column for separation therein;   ii) sending a nitrogen enriched liquid from the top of the high pressure column to the top of the low pressure column;   iii) removing an oxygen rich liquid from the low pressure column, and then pressurizing and vaporizing said oxygen rich liquid in the heat exchanger or another heat exchanger;   iv) removing a nitrogen rich liquid from the column system, and then pressurizing and vaporizing said nitrogen rich liquid in the heat exchanger or another heat exchanger;   v) sending an argon enriched gas from the low pressure column to the argon column, said argon column having a top condenser, and removing an argon rich fluid from the top of the argon column;   vi) partially vaporizing an oxygen enriched liquid from the bottom of the high pressure column in the top condenser of the argon column and then sending a gas thereby formed to the low pressure column;   vii) withdrawing a liquid air stream or a stream containing between 18 and 25 mol. % oxygen from an intermediate point of the high pressure column and sending at least in part to a top condenser of the intermediate pressure column wherein the liquid air stream or the stream containing between 18 and 25 mol. % oxygen is partially vaporized to form a vapor and a liquid;   viii) sending a vapor formed in the top condenser of the intermediate pressure column to the low pressure column;   ix) sending a liquid from the top condenser of the intermediate pressure column to the intermediate pressure column to be separated;   x) sending a liquid from the bottom of the intermediate pressure column to the low pressure column; and   xi) sending a liquid from the top of the intermediate pressure column to the top of the low pressure column.   
     
     
         17 . The process according to  claim 16 , wherein the intermediate pressure column has a bottom reboiler and wherein the argon enriched gas from the low pressure column is condensed in the bottom reboiler. 
     
     
         18 . The process according to  claim 16 , wherein the liquid sent from the top condenser of the intermediate pressure column is the only feed separated in the intermediate pressure column. 
     
     
         19 . The process according to  claim 16 , wherein all the oxygen enriched liquid from the high pressure column is sent to the argon column top condenser or to the low pressure column and the argon column top condenser, without passing through the intermediate pressure column top condenser. 
     
     
         20 . The process according to  claim 16 , wherein all the bottom liquid of the intermediate pressure column is sent to the low pressure column without passing through the intermediate pressure column top condenser. 
     
     
         21 . The process according to  claim 16 , wherein part of the liquid from the intermediate pressure column top condenser is sent to the low pressure column. 
     
     
         22 . The process according to  claim 16 , wherein the liquid from the top condenser is sent to the intermediate pressure column between 2 and 5 theoretical trays above the bottom of the intermediate pressure column. 
     
     
         23 . The process according to  claim 16 , wherein at least part of the air is cooled to an intermediate temperature of the heat exchanger, compressed in a compressor, further cooled in the heat exchanger and sent to at least the high pressure column. 
     
     
         24 . The process according to  claim 16 , wherein the bottom liquid of the intermediate pressure column contains at least 70% mol. oxygen. 
     
     
         25 . The process according to  claim 16 , wherein at least one of the bottom reboiler and the top condenser of the intermediate pressure column is a falling film reboiler. 
     
     
         26 . The process according to  claim 16 , wherein at least one part of the feed air is compressed from a first pressure to a second pressure in a warm booster, fed to the heat exchanger at the second pressure, cooled, expanded in a first turboexpander and sent to the high pressure column and at least another part of the feed air is sent to the heat exchanger at the first pressure, divided into three portions, the first portion being compressed from the first pressure to a third pressure in a cold booster, cooled, expanded and sent to the high pressure column, the second portion being expanded in a second turboexpander and sent to the high pressure column and the third portion being cooled to the cold end of the heat exchanger and sent to the high pressure column. 
     
     
         27 . An apparatus for the separation of air by cryogenic distillation comprising:
 a column system having a high pressure column; a low pressure column, the bottom of the low pressure column being thermally coupled with the top of the high pressure column; an intermediate pressure column, operating a pressure between that of the high pressure column and that of the low pressure column; and an argon column;   a heat exchanger;   a conduit configured to send purified compressed air to be cooled in the heat exchanger;   a conduit configured to send cooled purified compressed air from the heat exchanger at least in part to the high pressure column;   a conduit configured to send nitrogen enriched liquid from the top of the high pressure column to the top of the low pressure column;   a conduit configured to remove oxygen rich liquid from the low pressure column, said conduit being connected to first pressurization means;   a conduit configured to send pressurized oxygen rich liquid from the first pressurization means to the heat exchanger or another heat exchanger;   a conduit configured to remove nitrogen rich liquid from the column system connected to second pressurization means;   a conduit connecting the second pressurization means to the heat exchanger or another heat exchanger;   a conduit configured to send argon enriched gas from the low pressure column to the argon column, said argon column having a top condenser;   a conduit configured to remove argon rich fluid from the top of the argon column;   a conduit configured to send oxygen enriched liquid from the bottom of the high pressure column to the top condenser of the argon column to be partially vaporized;   a conduit configured to send the gas thereby formed to the low pressure column;   a conduit configured to send a liquid air stream or a liquid stream containing between 18 and 25% oxygen removed at an intermediate point of the high pressure column at least in part to a top condenser of the intermediate pressure column where it is partially vaporized to form a vapor and a liquid;   a conduit configured to send the vapor formed in the top condenser of the intermediate pressure column to the low pressure column;   a conduit configured to send the liquid from the top condenser of the intermediate pressure column to the intermediate pressure column to be separated;   a conduit configured to send a liquid from the bottom of the intermediate pressure column to the low pressure column; and   a conduit configured to send a liquid from the top of the intermediate pressure column to the top of the low pressure column.   
     
     
         28 . The apparatus according to  claim 27 , wherein the intermediate pressure column has a bottom reboiler and comprising a conduit configured to send argon enriched gas from the low pressure column to be condensed in the bottom reboiler. 
     
     
         29 . The apparatus according to  claim 27 , wherein the top condenser is in fluid communication with the intermediate pressure column, such that the apparatus is configured to send the liquid from the top condenser to the intermediate pressure column between 2 and 5 theoretical trays above the bottom of the intermediate pressure column. 
     
     
         30 . The apparatus according to  claim 27 , further comprising a compressor, a conduit configured to send at least part of the air cooled to an intermediate temperature of the heat exchanger to the compressor, a conduit configured to send air from the compressor to be further cooled in the heat exchanger and a conduit configured to send the air from the compressor via the heat exchanger to at least the high pressure column.