Separation of air

• US 4,380,457 A
• Filed: 06/01/1979
• Issued: 04/19/1983
• Est. Priority Date: 05/25/1978
• Status: Expired due to Term

• Current Assignee: BOC Limited (Linde Plc)
• Original Assignee: BOC Limited (Linde Plc)
• Inventors: Ryan, Bruce R., Rathborne, Brian A.
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US06/044,826
• Time in Patent Office: 1,418 Days
• Field of Search: 55/31, 55/33, 55/62, 55/74, 55/75, 55/82, 55/179, 55/387, 55/389, 62/13, 62/14, 62/18, 62/31
• US Class Current: 95/114
• CPC Class Codes: B01D 2256/10 Nitrogen
• CPC Class Codes: B01D 2256/12 Oxygen
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 53/04 with stationary adsorbents B01D53/025 takes precedence
• CPC Class Codes: F25J 2205/24 using regenerators, cold accumulators or reversible heat exchangers
• CPC Class Codes: F25J 2205/60 using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
• CPC Class Codes: F25J 3/04242 Cold end purification of the feed air
• CPC Class Codes: F25J 3/04412 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 Class Codes: Y02C 20/40 of CO2

Abstract

An air separation process for obtaining high purity oxygen and nitrogen comprises the steps of cooling compressed air in a heat exchanger to remove its water content; removing carbon dioxide from the dried air in an adsorption unit; further cooling the dry CO₂ -free air and passing the residue to a rectification column; regenerating the beds of the adsorption unit with waste nitrogen from the rectification column; and purging water from the heat exchanger with the effluent gas obtained from regeneration in the adsorption unit.

Claims

1. An air separation process comprising:

(1) passing an air supply under pressure through a passage of a reversing heat exchanger to cool said air to a temperature of about 180°

to 230°

K. and deposit water in the form of ice in said passage and to form cooled dried air;

(2) contacting said cooled dried air with at least one bed containing an adsorbent material to remove at least a carbon dioxide component therefrom and to form a residue of cooled dried air and component adsorbed material;

(3) further cooling said residue of cooled dried air in a heat exchanger to form cooled rectifiable air;

(4) rectifying said cooled rectifiable air to form separate fractions of product gaseous nitrogen, product gaseous oxygen and waste nitrogen;

(5) treating said component adsorbed material with said waste nitrogen fraction at a pressure less than the pressure of said cooled dried air to regenerate said adsorbent material and to form a residual waste nitrogen fraction; and

(6) passing said residual waste nitrogen fraction through said passage of said reversing heat exchanger in reverse direction to the passing of said air supply to purge said water from said exchanger.

2. The process of claim 1 wherein said treating is conducted under substantially adiabatic conditions.

3. The process of claim 1 wherein said cooled rectifiable air formed in step (3) is at a temperature below 110 degrees Kelvin.

4. An air separation process comprising:

(1) passing an air supply under pressure through a passage of a first reversing heat exchanger to cool said air to a temperature of about 180°

to 230°

K. and deposit water in the form of ice in said passage and to form cooled dried air;

(2) contacting said cooled dried air under pressure with at least one bed containing an adsorbent material to remove at least a carbon dioxide component therefrom and to form a residue of cooled dried air and component adsorbed material;

(3) further cooling said residue of cooled dried air in a second heat exchanger to form cooled rectifiable air;

(4) rectifying said cooled rectifiable air to form separate fractions of product gaseous nitrogen, product gaseous oxygen and waste nitrogen;

(5) passing at least one of said fractions through said second heat exchanger to supply the cooling medium therefor;

(6) interrupting said contacting of said cooled dried air in said at least one bed containing an adsorbent material;

(7) treating said component adsorbed material with said waste nitrogen fraction under adiabatic conditions and at a pressure less than the pressure of said cooled dried air in said contacting step to regenerate said adsorbent material and to form a residual waste nitrogen fraction;

(8) interrupting said passing of said air supply through said first reversing heat exchanger;

(9) passing said residual waste nitrogen fraction through said passage of said first reversing heat exchanger in reverse direction to the passing of said air supply to purge said water from said exchanger.