Adsorptive process for the removal of carbon dioxide from a gas

• US 4,472,178 A
• Filed: 07/05/1983
• Issued: 09/18/1984
• Est. Priority Date: 07/05/1983
• Status: Expired due to Fees

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Kumar, Ravi, Sircar, Shivaji, Kratz, Wilbur C.
• Primary Examiner(s): Spitzer, Robert H.
• Application Number:
  US06/511,119
• Time in Patent Office: 441 Days
• Field of Search: 55/28, 55/31, 55/33, 55/35, 55/58, 55/62, 55/68, 55/75, 55/25, 55/26
• US Class Current: 95/99
• CPC Class Codes: B01D 2253/104 Alumina
• CPC Class Codes: B01D 2253/106 Silica or silicates
• CPC Class Codes: B01D 2253/108 Zeolites
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/80 Water
• CPC Class Codes: B01D 2259/40037 with two sub-steps
• CPC Class Codes: B01D 2259/40052 Recycled product or process gas
• CPC Class Codes: B01D 2259/40062 Four
• CPC Class Codes: B01D 2259/40081 Counter-current
• CPC Class Codes: B01D 2259/40086 by using a purge gas B01D2259/4009 takes precedence
• CPC Class Codes: B01D 2259/4009 using hot gas
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 2259/416 involving cryogenic temperature treatment
• CPC Class Codes: B01D 2259/655 using heat storage materials
• CPC Class Codes: B01D 53/0462 Temperature swing adsorption
• CPC Class Codes: B01D 53/047 Pressure swing adsorption
• CPC Class Codes: B01D 53/261 by adsorption
• CPC Class Codes: Y02C 20/40 of CO2

Abstract

A process is set forth for the removal of carbon dioxide from air in an adsorption bed wherein the regeneration energy is reduced by the use of a heat recuperator and a purge sequence which avoids the removal of heat from the adsorption bed during regeneration.

Claims

1. In a process for removing carbon dioxide from a gas stream in an adsorbent bed by temperature swing adsorption comprising flowing a water-depleted gas feed stream containing carbon dioxide through said bed to selectively adsorb carbon dioxide, the improvement comprising the steps of:

(a) passing the carbon dioxide-depleted gas product of the adsorbent bed through a recuperator to retain heat from said adsorbent bed;

(b) bypassing the flow of carbon dioxide-depleted gas product around said recuperator after the gas reaches a predetermined lower temperature level, but while continuing the adsorption;

(c) discontinuing the flow of water-depleted feed gas through said bed when the gas product of said bed reaches a predetermined level of carbon dioxide;

(d) reducing the pressure of the bed and initiating the purging of the bed countercurrently with a heated water and carbon dioxide-depleted purge gas, which is heated to an elevated temperature by externally supplied heat and heat recovered from said recuperator until a thermal zone exists in said bed;

(e) continuing the purge of the adsorbent bed without externally supplied heat until the thermal zone in said bed is approximately at the feed end of the bed;

(f) discontinuing the flow of purge gas, and

(g) repressurizing the bed countercurrently with water and carbon dioxide-depleted gas until the bed reaches a preset pressure level such that the adsorption cycle can be initiated again.

2. The process of claim 1 wherein the water-depleted feed gas stream is introduced into the adsorbent bed at 50-150 psia.

3. The process of claim 2 wherein the water-depleted feed gas stream is introduced into the adsorbent bed at 40°

-150°

F.

4. The process of claim 3 wherein the adsorption is discontinued when the gas product obtains a carbon dioxide level of up to 1 PPM.

5. The process of claim 1 wherein a plurality of adsorbent beds are utilized in which at least one bed is an adsorption mode while at least one other bed is in a regeneration mode.

6. The process of claim 5 wherein the water-depleted feed gas stream is delivered from a plurality of switching pressure swing adsorption beds.

7. The process of claim 6 wherein the water-depleted gas feed stream is air.

8. The process of claim 6 wherein the water and carbon dioxide-depleted gas product is supplied to an air separation system to recover oxygen and or nitrogen.