Method and facility for producing oxygen through air distillation

Abstract

In a method for producing oxygen through the distillation of air supplied by air at atmospheric pressure so as to produce a first and second compressed air flow, and through a first purification unit ( 5 ) and a second purification unit ( 7 ), the first and second compressed air flows at different pressures: the first compressed air flow is sent from a first outlet of the compression means to the first purifying unit at the first pressure; the first purified air flow is sent to a column of the column system ( 15 ); the second purified air flow is sent, in an at least partially condensed form, from the second purifying unit to the column system; an oxygen-rich liquid is bled off the column system; said oxygen-rich liquid is vaporized through heat exchange with at least the second purified air flow.

1 - 14 . (canceled) 
     
     
         15 . A method for producing oxygen by distilling air in an apparatus comprising at least one system of columns ( 15 ), at least one exchange line ( 13 ), at least one compression means driven by an electric motor and/or by a steam turbine and supplied with air at atmospheric pressure to produce one first and one second pressurized air flow, one first purification unit ( 5 ), one second purification unit ( 7 ), the first and second pressurized air flows leaving the compression means at a first and a second pressure, the second pressure being higher than the first by at least 0.5 bar, possibly by at least 5 bar, potentially by at least 10 bar, even by at least 25 bar, and the second pressure being the highest pressure of any air flow intended to be fed into the system of columns; in which method the first pressurized air flow is sent from a first outlet of the compression means to the first purification unit ( 5 ) substantially at the first pressure in order to produce a first air flow that is purified in terms of water and in terms of carbon dioxide, the second pressurized air flow is sent from a second outlet of the compression means to the second purification unit ( 7 ) substantially at the second pressure in order to produce a second air flow that is purified in terms of water and in terms of carbon dioxide, the purified first flow is cooled in the exchange line ( 13 ), possibly at the first pressure, the purified second flow is cooled in the exchange line ( 13 ), possibly at the second pressure, the purified first air flow is sent from the first purification unit to one column of the system of columns ( 15 ), the purified second air flow from the second purification unit is sent to one column of the system of columns ( 15 ) at least in partially condensed form, an oxygen-rich liquid is tapped off from the system of columns, vaporized, possibly in the exchange line or in an auxiliary vaporizer ( 25 ) by exchanging heat at least with the purified second flow at the second pressure and is delivered as product. 
     
     
         16 . The method of  claim 15 , in which the difference in pressure between the two pressurized air flows is at most 4 bar or possibly at least 1 bar and at most 3 bar. 
     
     
         17 . The method of  claim 15 , in which the difference in pressure between the two pressurized air flows is at least 5 bar and at most 30 bar, or possibly at least 15 bar and at most 25 bar. 
     
     
         18 . The method of  claim 15 , in which at least some of the purified first air flow is sent into the same column of the system of columns as the purified second air flow. 
     
     
         19 . The method of  claim 15 , in which no part of the second flow is sent into a reboiler of the system of columns. 
     
     
         20 . The method of  claim 15 , in which the second pressure is higher than the first by at least 5 bar. 
     
     
         21 . The method of  claim 15 , in which the second pressure is higher than the first by at least 10 bar. 
     
     
         22 . The method of  claim 15 , in which the second pressure is higher than the first by at most 25 bar. 
     
     
         23 . A facility for producing oxygen by distilling air, comprising at least one system of columns ( 15 ), at least one exchange line ( 13 ), at least one compression means driven by a steam turbine and/or by an electric motor, the compression means having a first and a second outlet, one first purification unit ( 5 ), one second purification unit ( 7 ), the compression means being designed to be supplied with air at atmospheric pressure and to produce, from the first outlet, a first pressurized air flow at a first pressure and from the second outlet a second pressurized air flow at a second pressure, the second pressurized air flow being at a pressure that is higher, by at least 0.5 bar, possibly by at least 5 bar, potentially by at least 10 bar, even by at least 25 bar, than the pressure of the first pressurized air flow, a first pipe for connecting the first outlet to the first purification unit, a second pipe for connecting the second outlet to the second purification unit, a third pipe ( 11 ) for connecting the first purification unit to the exchange line, a fourth pipe ( 9 ) for connecting the second purification unit to the exchange line, no means of boosting the air pressure being connected downstream of the second purification unit, a fifth pipe connecting the exchange line to one column of the system of columns, a sixth pipe for connecting the exchange line to one column of the system of columns, a pipe ( 17 ) for tapping off an oxygen-rich liquid from the system of columns and for sending to a vaporizer ( 25 ), possibly consisting of the exchange line, means for sending at least part of the purified second flow to the vaporizer where it condenses and in which facility there is no means of compressing air between the first outlet and the first purification unit and there is no means of compressing air between the second outlet and the exchange line, or potentially the system of columns. 
     
     
         24 . The facility of  claim 23 , in which the compression means comprises a first compressor ( 1 ) and a second compressor ( 3 ), means for supplying the first compressor and the second compressor with air at atmospheric pressure, the first and second compressors possibly being driven by a common steam turbine ( 39 ). 
     
     
         25 . The facility of  claim 23 , in which just one of the first and second air compressors comprises intermediate coolants (isothermal compression). 
     
     
         26 . The facility of  claim 25 , comprising means for sending air from the outlet of that one of the two air compressors that does not have an intermediate coolant to a heat exchanger ( 31 ), and means for sending at least one fluid from the system of columns and/or water to the exchanger where it is heated up. 
     
     
         27 . A method of producing oxygen by distilling air in an apparatus comprising n systems of columns, where n≧2, n exchange lines ( 13 ,  13 ′), at least one first compressor ( 1 , 1 ′) compressing atmospheric air in order to produce an air flow at a first pressure, at least one second compressor ( 3 , 3 ′) compressing atmospheric air to produce an air flow at a second pressure, the first pressure being lower by at least 0.5 bar, possibly by at least 5 bar, potentially by at least 10 bar, or even by at least 25 bar, than the second pressure, and the second pressure being the highest pressure of any air pressure intended for distillation, in which method air at the first pressure is sent from at least one first compressor to at least one first purification unit ( 5 , 5 ′), air at the second pressure is sent from at least one second compressor to at least one second purification unit ( 7 , 7 ′), air at the first pressure is sent from the first purification unit to at least two systems of columns ( 15 ,  15 ′), air at the second pressure is sent from the second purification unit to at least two systems of columns, and oxygen is produced from at least one of the systems of columns. 
     
     
         28 . A facility for producing oxygen by distilling air in an apparatus comprising n systems of columns, where n≧2, n exchange lines ( 13 ,  13 ′), at least one first compressor ( 1 , 1 ′) compressing atmospheric air in order to produce an air flow at a first pressure, at least one second compressor ( 3 , 3 ′) compressing atmospheric air to produce an air flow at a second pressure, the first pressure being lower by at least 0.5 bar, possibly by at least 5 bar, potentially by at least 10 bar, or even by at least 25 bar, than the second pressure, at least one first purification unit ( 5 , 5 ′), at least one second purification unit ( 7 , 7 ′), means for sending air at the first pressure from the first compressor(s) to the first purification unit(s), means for sending air at the second pressure from the second compressor(s) to the second purification unit(s), means for sending air to at least two systems of columns ( 15 ,  15 ′) from the first purification unit(s) and means for sending air to the two systems of columns from the second purification unit(s), in which facility there is no compression means between the first compressor(s) and the first purification unit(s) and there is no compression means between the second compressor(s) and the exchange lines, or potentially the systems of columns.