Method and device for the low-temperature separation of air at variable energy consumption

  • US 10,458,702 B2
  • Filed: 06/25/2015
  • Issued: 10/29/2019
  • Est. Priority Date: 07/05/2014
  • Status: Active Grant
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First Claim
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1. A method for obtaining a pressurized-gas product by means of the low-temperature separation of air in a distillation column system, which has a high-pressure column and a low-pressure column, said method comprising:

  • compressing feed air, containing at least 78 mol % of nitrogen, in a main air compressor from an inlet pressure to a first pressure, wherein said first pressure is at least 4 bar higher than an operating pressure of the high-pressure column, said feed air constituting a first process stream and wherein said main air compressor is a multi-stage compressor,cooling a first partial stream of the compressed feed air in the main air compressor to an intermediate temperature in a main heat exchanger and expanding the cooled first partial stream in a first air turbine whereby work is performed,introducing at least a first part of the expanded first partial stream into the distillation column system,compressing a second partial stream of the compressed feed air from the main air compressor to a second pressure, which is higher than the first pressure, in a first booster air compressor, which is driven by the first air turbine, cooling the compressed second partial stream in the main heat exchanger, and subsequently expanding the second partial stream and introducing the second partial stream into the distillation column system,removing a first product stream in liquid form from the distillation column system and increasing the pressure of the first product stream to a first product pressure,evaporating or pseudo-evaporating the first product stream under the first product pressure and warming the first product stream in the main heat exchanger,removing the warmed first product stream as first pressurized-gas product, andwherein, in a first operating mode, a first amount of said first pressurized-gas product is obtained, and a first amount of a second process stream containing at least 78 mol % of nitrogen is mixed with the first process stream downstream of a first stage of the multi-stage compressor, wherein said second process stream is a part of the expanded first partial stream, and wherein said first amount of said second process stream can be zero, andwherein, in a second operating mode, a second amount of said first pressurized-gas product is obtained, wherein said second amount of said first pressurized-gas product is smaller than said first amount of said first pressurized-gas product, and a second amount of said second process stream is mixed with the first process stream downstream of a first stage of the multi-stage compressor, wherein said second amount of said second process stream is greater than said first amount of the second process stream.

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