Method and apparatus for compressing and cooling air

Abstract

The invention relates to a method for compressing and cooling air upstream from a facility for cryogenic separation of air, with no means for exchange by indirect heat, in which humid air is compressed in a compressor, the air compressed in the compressor is cooled in a first exchanger having indirect heat exchange, water is recovered from the air upstream and/or downstream from cooling in the first exchanger, the air cooled in the first exchanger is sent to a purification unit in order to produce air purified of carbon dioxide and/or water, the purified air is sent to the cryogenic separation facility, and at least one gas is recovered from the cryogenic separation facility.

1 - 16 . (canceled) 
     
     
         17 . A process for compressing and cooling air upstream of a cryogenic air separation plant, comprising:
 i. compressing wet air a compressor; thereby producing a compressed air stream,   ii. cooling the compressed air stream in a first heat exchanger by indirect heat exchange; thereby producing a cooled air stream comprising water,   iii. recovering the water contained in the cooled air stream upstream and/or downstream of the cooling in step ii), without having cooled the air upstream of the first exchanger by a cooling step by direct heat exchange; thereby producing a dry air stream,   iv. sending the dry air stream to a purification unit in order to produce a purified air stream that is purified of carbon dioxide and/or of water;   v. sending the purified air stream to a cryogenic separation plant; thereby producing at least an oxygen rich stream and an oxygen depleted stream,   vi. recovering at least one of the oxygen rich stream or the oxygen depleted stream;   vii. mixing the water recovered in step iii) with the gas removed in step vi), the mixture produced being at a temperature above the solidification point of the water in the mixture;   viii. heating the water mixed with the gas in the first heat exchanger; and   ix. cooling the air recovered upstream of the first heat exchanger in a precooler upstream of the recovery of water by indirect heat exchange, if water contained in the air is recovered upstream of the first heat exchanger.   
     
     
         18 . The process of  claim 17 , wherein the compression of step i) is isothermal. 
     
     
         19 . The process of  claim 17 , wherein the oxygen rich stream or the oxygen depleted stream recovered instep vi) is heated. 
     
     
         20 . The process of  claim 17 , wherein the production temperature in step vii) is above 0° C. if the pressure of the mixture is close to atmospheric pressure. 
     
     
         21 . The process of  claim 17 , wherein the water mixed with the gas in the first heat exchanger is mixed with the gas upstream of the first exchanger) and/or at an intermediate point of the first heat exchanger. 
     
     
         22 . The process of  claim 17 , wherein water contained in the air is recovered downstream of the cooling in the first heat exchanger and upstream of the purification unit . 
     
     
         23 . The process of  claim 17 , wherein the amount of water mixed with the gas is such that, at the inlet point of the water mixed with the gas of the first heat exchanger and/or at the intermediate point of the first heat exchanger where the mixing takes place, the mixture of gas and water is above the water saturation point. 
     
     
         24 . The process of  claim 17 , wherein water contained in the air is recovered upstream of the first heat exchanger and the air is cooled in a precooler by indirect heat exchange. 
     
     
         25 . The process of  claim 17 , wherein the gas is mixed solely with water produced by condensation of water contained in the air. 
     
     
         26 . The process of  claim 17 , wherein at least one other gas, not mixed with water, is heated in the first heat exchanger. 
     
     
         27 . The process of  claim 17 , wherein the gas mixed with the water is nitrogen and a stream of oxygen and/or another stream of nitrogen is heated in the first heat exchanger. 
     
     
         28 . An air separation process comprising a process for compressing and cooling air as claimed in one of the preceding claims, wherein the purified air is cooled in a second heat exchanger and sent to a column of the cryogenic separation plant, at least one product is withdrawn from the plant and heated in the second heat exchanger and then in the first heat exchanger and at least one product is withdrawn from the plant, heated, optionally vaporized, in the second heat exchanger and then, in gas form, in the first heat exchanger. 
     
     
         29 . An apparatus for compressing and cooling air intended for a cryogenic separation plant comprising a compressor, a first heat exchanger by indirect heat exchange, a purification unit, one or two separators, the compressor being connected to the first heat exchanger and the first heat exchanger being connected to the purification unit, the apparatus not comprising means of cooling air by direct exchange upstream of the first heat exchanger, the purification unit being suitable for sending purified air to the plant, the separator(s) being connected
 i. between the compressor and the first heat exchanger, downstream of a precooler ( 6 ) suitable for cooling the air by indirect heat exchange; and/or   ii. between the first heat exchanger and the purification unit,   at least a first line for conveying gas originating from the plant to the first heat exchanger, at least a second line for conveying water from the separator to the first line and/or the heat exchanger in order to mix water with the gas.   
     
     
         30 . The apparatus of  claim 29 , wherein the pump connecting the first heat exchanger with the separator. 
     
     
         31 . The apparatus of  claim 29 , further comprising a line for sending a dry gas heated in the first heat exchanger to the purification unit. 
     
     
         32 . The apparatus of  claim 29 , further comprising lines for sending at least one other gas from the plant to the first heat exchanger in order to be heated therein. 
     
     
         33 . A plant for the cryogenic separation of air by distillation, comprising an apparatus of  claim 29 , wherein a system comprising at least one column, a second heat exchanger, a line for conveying air from the second heat exchanger to a column of the system and a line for conveying a distillation product to the second heat exchanger.