Method and facility for producing oxygen through air distillation

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.

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.