Method and device for the low-temperature separation of air at variable energy consumption
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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Abstract
A method and device used to variably obtain a compressed-gas product by means low-temperature separation of air in a distillation column system. In a first operating mode, a first amount of first compressed-gas product is obtained, and, in a second operating mode, a second, smaller amount is obtained. In the first operating mode, a first amount of air is compressed in the main air compressor, and in the second operating mode, a second, larger amount is compressed in the main air compressor.
5 Citations
12 Claims
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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:
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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, and wherein, 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, and wherein, 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 10, 11, 12)
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9. An apparatus for producing a pressurized-gas product by means of low-temperature separation of air, said apparatus comprising:
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a distillation column system having a high-pressure column and a low-pressure column, a main air compressor which is a multi-stage compressor for compressing feed air to a first pressure, which is at least 4 bar higher than an operating pressure of the high-pressure column, a main heat exchanger comprising means for cooling a first partial stream of compressed feed air to an intermediate temperature, a first air turbine for expanding the cooled first partial stream such that work is performed, means for introducing the expanded first partial stream into the distillation column system, a first booster air compressor for further compressing a second partial stream of compressed feed air to a second pressure, which is higher than the first pressure, wherein the booster air compressor is driven by the first turbine, said main heat exchanger further comprising means for cooling the further compressed second partial stream, means for expanding the cooled second partial stream and means for introducing the expanded second partial stream into the distillation column system, means for removing a first product stream in a liquid form from the distillation column system and means for increasing the pressure of the first product stream to a first product pressure, said main heat exchanger further comprising means for evaporating or pseudo-evaporating the first product stream under the first product pressure and then warming the first product stream, means for obtaining the warmed first product stream as a first pressurized-gas product, said multi-stage compressor compressing a first process stream which is said feed air and which contains at least 78 mol % of nitrogen, from an inlet pressure to a final pressure, means for mixing a second process stream, which contains at least 78 mol % of nitrogen, with the first process stream downstream of a first stage of the multi-stage compressor, the second process stream being formed by part of the expanded first partial stream, means for switching over between a first operating mode and a second operating mode, wherein said means for switching over provides for; in the first operating mode, obtaining a first amount of first pressurized-gas product, and compressing a first amount of the second process stream in the multi-stage compressor from an inlet pressure to a final pressure, wherein said first amount of the second process stream can be zero, and in a second operating mode, obtaining a second amount of first pressurized-gas product, which is smaller than the first amount first pressurized-gas product, and compressing a second amount of the second process stream, which is greater than the first amount of the second process stream, in the multi-stage compressor.
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Specification