Method for the cryogenic separation of air, and air separation plant

Abstract

The invention relates to an air separation plant for cryogenic separation, said plant being designed to carry out a high-air-pressure process, wherein nitrogen is removed from the pressure column, expanded in a turbine that is coupled to a cold booster, and heated. Separately from the nitrogen which is removed from the pressure column, nitrogen is removed from the low-pressure column and heated to the same temperature. Before expansion in the turbine that is coupled to the cold booster, the nitrogen removed from the pressure column is heated to a temperature in a temperature range of −100 to 50° C. During expansion, the nitrogen cools down to a temperature in a temperature range of −150 to −40° C. and is then heated again. The invention also relates to a corresponding air separation plant.

1 . A method for the cryogenic separation of air using an air separation plant comprising a rectification column arrangement with a pressure column and a low-pressure column, wherein
 the pressure column is operated in a first pressure range and the low-pressure column is operated in a second pressure range, which is below the first pressure range, and at least 90% of a total quantity of air separated in the rectification column arrangement is compressed to a pressure in a third pressure range that is more than 4 bar above the first pressure range,   a partial quantity of the total separated air quantity is successively supplied to a first booster driven by a first turbine at a temperature in a first temperature range of −30 to 100° C., compressed using the first booster from the pressure in the third pressure range to a pressure in a fourth pressure range, which is above the third pressure range, cooled to a temperature in a second temperature range of −160 to −60° C., supplied at the temperature in the second temperature range to a second booster driven by a second turbine, compressed using the second booster from the pressure in the fourth pressure range to a pressure in a fifth pressure range, which is above the fourth pressure range, cooled to a temperature in a third temperature range of −200 to −150° C., and fed into the pressure column,   gaseous nitrogen is removed from the pressure column at a pressure in the first pressure range and successively heated to a temperature in a fourth temperature range, expanded in the second turbine while cooling to a temperature in a fifth temperature range to a pressure in the second pressure range, and heated to a temperature in a sixth temperature range from 0 to 50° C., and   gaseous nitrogen is removed from the low-pressure column and heated to the temperature in the sixth temperature range,   wherein   the gaseous nitrogen removed from the low-pressure column is heated separately from the gaseous nitrogen removed from the pressure column to the temperature in the sixth temperature range, and   the fourth temperature range is from −100 to 50° C. and the fifth temperature range is from −150 to −40° C.   
     
     
         2 . The method according to  claim 1 , with which the first pressure range is 4 to 7 bar, the second pressure range is 1 to 2 bar, the third pressure range is 10 to 18 bar, the fourth pressure range is in a pressure range of 1.2 times to 1.5 times the third pressure range and the fifth pressure range is in a pressure range of 1.6 times to 2.5 times the fourth pressure range. 
     
     
         3 . The method according to  claim 1 , with which a further partial quantity of the total separated air quantity is successively supplied to the first booster at the temperature in the first temperature range, compressed using the first booster from the pressure in the third pressure range to the pressure in the fourth pressure range, cooled to the temperature in the second temperature range or a further temperature range, expanded in the first turbine to a pressure in the first pressure range and fed into the pressure column. 
     
     
         4 . The method according to  claim 1 , with which a further partial quantity of the total separated air quantity at the pressure in the third pressure range is cooled to the temperature in the third temperature range and fed into the pressure column. 
     
     
         5 . The method according to  claim 1 , with which the gaseous nitrogen removed from the low-pressure column and the gaseous nitrogen removed from the pressure column are combined at the temperature in the sixth temperature range after separate heating to the temperature in the sixth temperature range. 
     
     
         6 . The method according to  claim 1 , with which one or more liquids are removed from the rectification column arrangement, subjected to one or each internal compression, and discharged from the air separation plant in the form of one or more gaseous internal compression products. 
     
     
         7 . The method according to  claim 6 , with which the one or more gaseous internal compression products is or comprises a gaseous internal compression product produced using oxygen-rich liquid from the low-pressure column. 
     
     
         8 . The method according to  claim 6 , with which no liquid products are removed from the air separation plant or with which one or more liquid products are removed from the air separation plant in a total amount that does not exceed 10% of a total amount of the one or more gaseous internal compression products. 
     
     
         9 . The method according to  claim 1 , with which an argon-rich liquid is removed from the low-pressure column and supplied to an argon recovery system for the recovery of argon. 
     
     
         10 . The method according to  claim 1 , with which gaseous nitrogen is removed from the pressure column, heated to a temperature in the sixth temperature range and recovered at a pressure in the first pressure range as nitrogen-rich air product. 
     
     
         11 . An air separation plant for the cryogenic separation of air, which has a rectification column arrangement with a pressure column and a low-pressure column, wherein the air separation plant is designed
 to operate the pressure column in a first pressure range and the low-pressure column in a second pressure range that is below the first pressure range, and to compress at least 90% of a total quantity of air separated in the rectification column arrangement to a pressure in a third pressure range, which is more than 5 bar above the first pressure range,   to supply a partial quantity of the total quantity of separated air successively at a temperature in a first temperature range of −30 to 100° C. to a first booster driven by a first turbine, using the first booster to compress it from the pressure in the third pressure range to a pressure in a fourth pressure range, which is above the third pressure range, to cool it to a temperature in a second temperature range of −160 to −60° C., to supply it at the temperature in the second temperature range to a second booster driven by a second turbine, using the second booster to compress it from the pressure in the fourth pressure range to a pressure in a fifth pressure range. which is above the fourth pressure range, to cool it to a temperature in a third temperature range of −200 to −150° C., and to feed it into the pressure column,   to remove gaseous nitrogen from the pressure column at a pressure in the first pressure range and to heat it successively to a temperature in a fourth temperature range, to expand it in the second turbine while cooling it to a temperature in a fifth temperature range to a pressure in the second pressure range, and to heat it to a temperature in a sixth temperature range of 0 to 50° C., and   to remove gaseous nitrogen from the low-pressure column and heat it to the temperature in the sixth temperature range,   wherein the air separation plant is designed   heating the gaseous nitrogen removed from the low-pressure column separately from the gaseous nitrogen removed from the pressure column to the temperature in the sixth temperature range, wherein   the fourth temperature range is from −100 to 50° C. and the fifth temperature range is from −150 to −40° C.