Pump for a cryogenic liquid and pump unit and distillation column which are equipped with such a pump

A unit for pumping a cryogenic liquid, comprising:

• a first pump (1A) and a second pump (1B) arranged in parallel in a duct and carrying a motor liquid under pressure,
• each of the first and second pumps for pumping a cryogenic liquid (3) and including
• a hydraulic motor (9) with a motor inlet for receipt of the motor liquid (15) under pressure and a driving wheel (13) driven by the motor liquid (15) and mounted on a shaft (27),
• a pumping wheel (21) mounted commonly with the hydraulic motor on the shaft for pumping the cryogenic liquid (3), and
• a relative sealing means (33) preventing contamination of the cryogenic liquid (3) by transfer of the motor liquid (15) from the hydraulic motor to the pumping wheel, the relative sealing means (33) including a labyrinth seal (35) arranged around the shaft (27) between the driving wheel (13) and the pumping wheel (21);
• and
• a thermally insulated compartment (2) containing the first and second pumps and means for transporting the cryogenic liquid (3) to and from the first and second pumps,
• wherein there is arranged in the duct carrying the motor liquid a means (88, 90) for switching between a supply of the motor liquid to one (1A) or the other (1B) of the first and second pumps.

Plant (50;

• 101) for distillation of a gas comprising:
• at least a first (60;
• 102) and a second (62;
• 103) column, the first column (60;
• 101) being pressurized at a first pressure higher than a second pressure prevailing in the second column (62;
• 103);
• at least one pump (1) comprising
• a hydraulic motor (9) with a motor inlet and a driving wheel, the motor inlet receiving a pressurized motor liquid (15) with a density in excess of 400 kg/M3, the driving wheel (13) driven by the motor liquid (15) and mounted on a shaft (27),
• a pumping wheel (21) mounted commonly with the hydraulic motor on the shaft for pumping the cryogenic liquid (3), and
• a relative sealing means (33) preventing contamination of the cryogenic liquid (3) by transfer of the motor liquid (15) from the hydraulic motor to the pumping wheel, the relative sealing means (33) including a labyrinth seal (35) arranged around the shaft (27) between the driving wheel (13) and the pumping wheel (21);
• a thermally insulated compartment (2) containing the at least one pump and means for transporting the cryogenic liquid to and from the at least one pump,
• wherein the at least one pump pumps a cryogenic liquid delivered by one of the said first and second columns (60, 62;
• 102, 103),
• the at least one pump (1) being driven by the motor liquid delivered by the plant (50;
• 101).

Plant for distillation of a gas comprising:

• at least a first and a second column, the first column being pressurized at a first pressure higher than a second pressure prevailing in the second column;
• at least one pump (1) comprising
• a hydraulic motor (9) with a motor inlet and a driving wheel, the motor inlet receiving a pressurized motor liquid (15), the driving wheel (13) driven by the motor liquid (15) and mounted on a shaft (27),
• a pumping wheel (21) mounted commonly with the hydraulic motor on the shaft for pumping the cryogenic liquid (3), and
• a relative sealing means (33) preventing contamination of the cryogenic liquid (3) by transfer of the motor liquid (15) from the hydraulic motor to the pumping wheel, the relative sealing means (33) including a labyrinth seal (35) arranged around the shaft (27) between the driving wheel (13) and the pumping wheel (21);
• a thermally insulated compartment (2) containing the at least one pump and means for transporting the cryogenic liquid to and from the at least one pump,
• wherein the at least one pump pumps a cryogenic liquid delivered by one of the said first and second columns,
• the at least one pump (1) being driven by the motor liquid delivered by the slant (50;
• 101), and
• the said motor liquid is liquid air delivered by a heat-exchange line (54).

A pump for a cryogenic liquid, comprising:

• a shaft;
• a hydraulic motor with a motor liquid feed accepting a pressurized motor liquid and a driving wheel mounted of the shaft and driven by the motor liquid;
• a pumping wheel mounted on the shaft and driven by the hydraulic motor, for pumping the cryogenic liquid;
• a relative sealing means, associated with the wheel, for preventing contamination of the cryogenic liquid by transfer of the motor liquid from the hydraulic motor to the pumping wheel, the relative sealing means including a labyrinth seal arranged around the shaft between the driving wheel and the pumping wheel,
• wherein the relative sealing means transfers the cryogenic liquid from the pumping wheel to the motor.