Method and apparatus for obtaining a compressed gas product by cryogenic separation of air

Patent metadata

Field	Value
Publication number	US-10995983-B2
Application number	US-201514788909-A
Country	US
Kind code	B2
Filing date	Jul 1, 2015
Priority date	Jul 5, 2014
Publication date	May 4, 2021
Grant date	May 4, 2021

Abstract

A method and the apparatus for obtaining a compressed gas product by means of cryogenic separation of air in a distillation column system which has a high-pressure column and a low-pressure column. All of the feed air is compressed in a main air compressor to a first pressure which is at least 4 bar higher than the operating pressure of the high-pressure column. A first partial flow of the feed air compressed in the main air compressor is cooled to an intermediate temperature in a main heat exchanger and is expanded so as to perform work in a first air turbine. At least a first part of the first partial flow expanded so as to perform work is introduced into the distillation column system.

First claim

What I claim is:

1. A method for obtaining a compressed gas product by means of cryogenic separation of air in a distillation column system which has a high-pressure column, a low-pressure column, and a main condenser, said method comprising:
compressing all of a feed air in a main air compressor to a first pressure which is at least 4 bar higher than an operating pressure of the high-pressure column,
cooling a first partial flow of the feed air compressed in the main air compressor to a first intermediate temperature in a main heat exchanger to produce a cooled first partial flow, and expanding the cooled first partial flow to perform work in a first air turbine to produce an expanded first partial flow,
introducing at least a first part of the expanded first partial flow into the distillation column system,
compressing a second partial flow of the feed air compressed in the main air compressor in a first booster compressor, which is driven by the first air turbine, to a second pressure which is higher than the first pressure,
cooling the second partial flow in the main heat exchanger to a second intermediate temperature to form a cooled second partial flow, compressing the cooled second partial flow in a second booster compressor, which is driven by a second air turbine, to a third pressure which is higher than the second pressure, to produce a further compressed second partial flow,
cooling said further compressed second partial flow in the main heat exchanger and then expanding said further compressed second partial flow to produce an expanded second partial flow, and introducing said expanded second partial flow into the distillation column system,
cooling a third partial flow of the feed air compressed in the main air compressor in the main heat exchanger to a third intermediate temperature to produce a cooled third partial flow, expanding said cooled third partial flow to perform work in the second air turbine to produce an expanded third partial flow, and introducing at least a first part of the expanded third partial flow into the distillation column system,
removing a first product flow in liquid form from the distillation column system and pressurizing the first product flow to a first product pressure,
evaporating or pseudo-evaporating the first product flow at the first product pressure in the main heat exchanger and heating evaporated or pseudo-evaporated first product flow in the main heat exchanger to form said compressed gas product, and
removing a second product flow from the high-pressure column or from the main condenser, pressurizing the second product flow to a second product pressure, heating the second product flow in the main heat exchanger at the second product pressure to form a further compressed gas product,
wherein:
wherein the main condenser provides heat exchange between gas from an upper region of the high-pressure column and liquid from a bottom region of the low-pressure column,
the cooled third partial flow is expanded in the second air turbine to a pressure which is at least 1 bar higher than the operating pressure of the high-pressure column,
an inlet pressure of the first air turbine is at least 1 bar lower than the third pressure, and
before being introduced into the distillation column system, said at least a first part of the expanded third partial flow is cooled and liquefied in the main heat exchanger and then expanded.

2. The method according to claim 1 , further comprising cooling a fourth partial flow of the air compressed in the main air compressor in the main heat exchanger at the first pressure to produce a cooled fourth partial flow, expanding said cooled fourth partial flow, and introducing expanded fourth partial flow into the distillation column system.

3. The method according to claim 1 , wherein the third partial flow, together with the second partial flow, is compressed in the first booster compressor to the second pressure before the third partial flow is introduced into the second air turbine at the second pressure.

4. The method according to claim 1 , wherein the third partial flow is introduced into the second air turbine at the first pressure.

5. The method according to claim 1 , wherein a second part of the expanded third partial flow is not introduced into the main heat exchanger, and wherein said second part of the expanded third partial flow is introduced into a liquefaction space of a sump evaporator of the high-pressure column which is a condenser-evaporator and at last partially condensed therein.

6. The method according to claim 5 , wherein the second part of the expanded third partial flow that is at least partially condensed in the sump evaporator is introduced into the high-pressure column at an intermediate point thereof.

7. An apparatus for obtaining a compressed gas product by means of cryogenic separation of air comprising:
a distillation column system which has a high-pressure column, a low-pressure column, and a main condenser wherein the main condenser provides heat exchange between gas from an upper region of the high-pressure column and liquid from a bottom region of the low-pressure column,
a main air compressor for compressing all of a feed air to a first pressure which is at least 4 bar higher than an operating pressure of the high-pressure column,
a line for introducing a first partial flow of the feed air compressed in the main air compressor into a main heat exchanger,
a line for removing the first partial flow, cooled to a first intermediate temperature, from the main heat exchanger,
a line for introducing the first partial flow cooled to the first intermediate temperature into a first air turbine where the first partial flow is expanded to perform work,
a line for introducing the first partial flow from the first air turbine into the distillation column system,
a first booster compressor, driven by the first air turbine, for further compressing a second partial flow of the feed air compressed in the main air compressor to a second pressure, which is higher than the first pressure, to produce a further compressed second partial flow,
a line for introducing the further compressed second partial flow into the main heat exchanger, and a line for removing the further compressed second partial flow from the main heat exchanger at a second intermediate temperature,
a second booster compressor, driven by a second air turbine, for compressing the second partial flow, removed from the main heat exchanger at the second intermediate temperature, to a third pressure which is higher than the second pressure, and wherein the first partial flow of the feed air is introduced into the first air turbine at an inlet pressure which is at least 1 bar lower than the third pressure,
a line for introducing the second partial flow at the third pressure into the main heat exchanger, a line for removing the second partial flow at the third pressure from the main heat exchanger,
means for expanding the second partial flow removed from the main heat exchanger to produce an expanded second partial flow, and a line for introducing the expanded second partial flow into the distillation column system,
a line for introducing a third partial flow of the feed air compressed in the main air compressor into the main heat exchanger, and a line for removing the third partial flow from the main heat exchanger at a third intermediate temperature,
a second air turbine for work-performing expansion of the third partial flow removed from the main heat exchanger at the third intermediate temperature to produce an expanded third partial flow at a pressure which is at least 1 bar higher than the operating pressure of the high-pressure column, a line for introducing the expanded third partial flow into the main heat

Assignees

• Linde Ag

Inventors

• Goloubev Dimitri

Classifications

• F25J3/04296

  Claude expansion, i.e. expanded into the main or high pressure column · CPC title

• F25J3/04393

  using multiple or multistage gas work expansion · CPC title

• F25J3/04412 Primary

  in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column · CPC title

• F25J3/04678

  cooled by oxygen enriched liquid from high pressure column bottoms · CPC title

• F25J3/04721

  Producing pure argon, e.g. recovered from a crude argon column · CPC title