Method and plant for the cryogenic separation of air

Abstract

A method and air separation plant for the distillative cryogenic separation of feed air in a distillation column system of an air separation plant at different distillation pressures, wherein all of the feed air in a total air quantity is compressed to a first pressure level that is at least 4 to 5 bar above the highest of the distillation pressures, and from the total air quantity a first part air quantity is first cooled to a first temperature level of 130 to 170 K and then compressed to a second pressure level that is at least 10 bar above the first pressure level, and a second part air quantity is first cooled to a second temperature level of 110 to 150 K and then expanded to a third pressure level that is below the first pressure level.

What I claim is: 
     
         1 . A method for the distillative cryogenic separation of feed air in a distillation column system of an air separation plant at different distillation pressures, wherein all of the feed air in a total air quantity is compressed to a first pressure level that is at least 4 to 5 bar above the highest of the distillation pressures, and from the total air quantity
 a first part air quantity is first cooled to a first temperature level of 130 to 170 K and then compressed to a second pressure level that is at least 10 bar above the first pressure level, and   a second part air quantity is first cooled to a second temperature level of 110 to 150 K and then expanded to a third pressure level that is below the first pressure level, wherein   a compression/expansion arrangement with a gearing, in which a driving wheel engages with a gear wheel and the gear wheel engages with a driven wheel is provided, wherein   the rotor blades of two or more turbo expanders are coupled to the driving wheel and the rotor blades of two or more turbo compressors are coupled to the driven wheel, wherein both couplings are rotationally fixedly coupled, and   the first part air quantity is fed, for compression to the second pressure level, in series through the turbo compressors and the second part air quantity is fed, for expansion to the third pressure level, in parallel through the turbo expanders.   
     
     
         2 . The method according to  claim 1 , in which a torque transmitted by means of the driving wheel to the gear wheel is greater than or equal to a torque transmitted by means of the gear wheel to the driven wheel. 
     
     
         3 . The method according to  claim 1 , in which, as the turbo compressors, use is made of two turbo compressors of which the rotor blades are respectively coupled to a first shaft coupled to the driven wheel, on either side of the driven wheel. 
     
     
         4 . The method according to  claim 1 , in which the first pressure level is 10 to 17 bar, and/or in which the second pressure level is 40 to 70 bar. 
     
     
         5 . The method according to  claim 1 , in which the third pressure level deviates by no more than 1 bar from the highest of the distillation pressures in the distillation column arrangement. 
     
     
         6 . The method according to  claim 1 , in which a normal volume flow of the first part air quantity corresponds to 0.2 to 0.5 times a normal volume flow of the second part air quantity, and/or in which normal volume flows of the first and second part air quantities together correspond to 0.4 to 0.6 times a normal volume flow of the total air quantity. 
     
     
         7 . The method according to  claim 1 , in which the second part air quantity is compressed, prior to cooling to the second temperature level, from the first pressure level to an intermediate pressure level below the second pressure level. 
     
     
         8 . The method according to  claim 1 , in which a liquid, oxygen-rich air product is extracted from the distillation column system, is pressurized in liquid form and is then converted, by heating, from the liquid to the supercritical or gaseous state. 
     
     
         9 . The method according to  claim 8 , in which the liquid, oxygen-rich air product is pressurized in liquid form to the first pressure level. 
     
     
         10 . The method according to  claim 4 , in which the first pressure level is 13 to 16 bar, and/or in which the second pressure level is 50 to 60 bar. 
     
     
         11 . An air separation plant which is set up for the distillative cryogenic separation of feed air in a distillation column system at different distillation pressures, there being provided means which are set up to compress all of the feed air in a total air quantity to a first pressure level that is at least 5 bar above the highest of the distillation pressures, and from the total air quantity
 to first cool a first part air quantity to a first temperature level of 130 to 170 K and then to compress this to a second pressure level that is at least 10 bar above the first pressure level, and   to first cool a second part air quantity to a second temperature level of 110 to 150 K and then to expand this to a third pressure level that is below the first pressure level, wherein   a compression/expansion arrangement with a gearing, in which a driving wheel engages with a gear wheel and the gear wheel engages with a driven wheel is provided, wherein   the rotor blades of two or more turbo expanders are coupled to the driving wheel and the rotor blades of two or more turbo compressors are coupled to the driven wheel, wherein both couplings are rotationally fixedly coupled, and   there are provided means which are set up to feed the first part air quantity, for compression to the second pressure level, in series through the turbo compressors and to feed the second part air quantity, for expansion to the third pressure level, in parallel through the turbo expanders.   
     
     
         12 . The air separation plant according to  claim 11 , in which at least one other driving wheel and/or at least one other driven wheel engages with the gear wheel. 
     
     
         13 . The air separation plant according to  claim 11 , in which there are provided two turbo compressors of which the rotor blades are respectively coupled to a first shaft coupled to the driven wheel, on either side of the driven wheel. 
     
     
         14 . The air separation plant according to  claim 11 , in which there are provided two turbo expanders of which the rotor blades are respectively coupled to a second shaft coupled to the driving wheel, on either side of the driving wheel. 
     
     
         15 . The air separation plant according to  claim 11 , for performing the distillative cryogenic separation of feed air.