Method for the adsorptive drying of purified biogas and for regenerating laden adsorbents

• US 8,747,522 B2
• Filed: 03/08/2011
• Issued: 06/10/2014
• Est. Priority Date: 03/12/2010
• Status: Active Grant

• Current Assignee: Dge Dr.-Ing. Guenther Engineering GmbH
• Original Assignee: Dge Dr.-Ing. Guenther Engineering GmbH
• Inventors: Guenther, Lothar
• Primary Examiner(s): LAWRENCE JR, FRANK M
• Application Number:
  US13/634,326
• Publication Number:
  US 20130000486A1
• Time in Patent Office: 1,190 Days
• Field of Search: 95/14, 95 95- 99, 951/05, 951/06, 95117-120, 95123-125, 961/12, 961/32
• US Class Current: 95/99
• CPC Class Codes: B01D 2253/106 Silica or silicates
• CPC Class Codes: B01D 2256/245 Methane
• CPC Class Codes: B01D 2258/05 Biogas
• CPC Class Codes: B01D 2259/40052 Recycled product or process gas
• CPC Class Codes: B01D 2259/40081 Counter-current
• CPC Class Codes: B01D 2259/4009 using hot gas
• CPC Class Codes: B01D 2259/402 using two beds
• CPC Class Codes: B01D 53/0462 Temperature swing adsorption
• CPC Class Codes: B01D 53/261 by adsorption
• CPC Class Codes: B01D 53/263 by absorption
• CPC Class Codes: B01D 53/265 by refrigeration (condensation)
• CPC Class Codes: B01J 20/103 comprising silica
• CPC Class Codes: B01J 20/18 Synthetic zeolitic molecular sieves
• CPC Class Codes: B01J 20/28052 Several layers of identical or different sorbents stacked in a housing, e.g. in a column
• CPC Class Codes: B01J 20/2808 being less than 2 nm, i.e. micropores or nanopores
• CPC Class Codes: B01J 20/28083 being in the range 2-50 nm, i.e. mesopores
• CPC Class Codes: B01J 20/28085 being more than 50 nm, i.e. macropores
• CPC Class Codes: B01J 20/3408 of aluminosilicate molecular sieves
• CPC Class Codes: B01J 20/3433 of sorbents or filter aids other than those covered by B01J20/3408 - B01J20/3425
• CPC Class Codes: B01J 20/3483 by thermal treatment not covered by groups B01J20/3441 - B01J20/3475, e.g. by heating or cooling
• CPC Class Codes: B01J 2220/42 : Materials comprising a mixture of inorganic materials materials coated or impregnated on a carrier B01J20/32
• CPC Class Codes: B01J 2220/606 : parallel disposed columns
• CPC Class Codes: C10L 3/106 : of water
• CPC Class Codes: C12M 47/18 : Gas cleaning, e.g. scrubbers; Separation of different gases separating dispersed particles from gases or vapours B01D45/00; separation of gases or vapours B01D53/00; gas washing apparatus for laboratory uses B01L5/04
• CPC Class Codes: E01C 11/005 : Methods or materials for repairing pavings E01C7/35 takes precedence; for concrete coverings E01C7/147; for bituminous coverings E01C7/187; devices for repair works E01C23/06; repairing bridge floorings E01D22/00
• CPC Class Codes: E01C 23/096 : for forming, opening-out, cleaning, drying or heating and filling E01C23/0993 takes precedence
• CPC Class Codes: E01C 5/003 : characterised by material or composition used for beds or joints; characterised by the way of laying
• CPC Class Codes: Y02C 20/40 : of CO2
• CPC Class Codes: Y02E 50/30 : Fuel from waste, e.g. synthetic alcohol or diesel
• CPC Class Codes: Y02P 20/59 : Biological synthesis; Biological purification

Abstract

In a method for adsorptively drying purified biogas and regenerating laden absorbents, foreign matter is not allowed to enter the purified biogas, the content of methane in the gas remains virtually unchanged and the effort involved in regenerating the laden adsorbent is reduced. Drying and regeneration are effected in a closed biogas cycle, wherein separate layers based on silica gel and molecular sieves are used as the adsorbent. The biogas to be dried first flows through the silica gel layer. The adsorbent is regenerated with exclusively heated, dried biomethane having a temperature of up to 150° C. which, after contact with adsorbent, is recirculated to the outflow of purified biogas. After regeneration, the bed is cooled by biomethane, which is subsequently recirculated to the outflow of purified biogas. Methane-containing water accumulating during drying and regeneration is recirculated to the biogas generation and/or purification.

Claims

1. A gas drying process, comprising:

providing a purified biogas having a methane content of at least 90% by volume;

providing an adsorber with adsorbents in the form of separate layers based on silica gel and molecular sieves;

adsorptively drying the purified biogas with the adsorbents and regenerating laden adsorbents in a closed biogas circuit; and

conducting the biogas to be dried first through a layer of silica gel, and wherein regenerating further comprises regenerating the adsorbent using exclusively heated dried biomethane having a temperature of up to 150°

C. and, after contact with the adsorbent, recycling the biomethane back into a starting stream of the purified biogas; and

on completion of regeneration, contacting cooled dried biomethane with the adsorbent and recycling back into the starting stream of the purified biogas, and conducting methane-containing water obtained during the drying and regeneration back to a biogas production and/or purification.

2. The process according to claim 1, which comprises removing a portion of water by cooling the purified biogas prior to supplying the purified biogas to the adsorber.

3. The process according to claim 1, wherein the layer of silica gel is formed from at least two layers including a lower macroporous layer and an upper mesoporous layer, with a volume ratio between the lower layer to the upper layer lying between 1:

1 and 1;

4.

4. The process according to claim 1, which comprises passing the biomethane for the regeneration through a bed of the adsorbent at a temperature of 110 to 150°

C., with a continuous measurement of the temperature of the exiting biomethane, and a shutdown of a supply of biomethane after a rise in the exit temperature to 40 to 50°

C.

5. The process according to claim 1, which comprises pumping the biogas to be dried through the adsorber at ambient pressure or with a slightly elevated pressure of up to 1 bar.

6. The process according to claim 1, wherein a volume ratio of a first layer being the silica gel layer to a second layer being the molecular sieves is 20:

1 to 3;

1.

7. The process according to claim 1, which comprises carrying out the adsorption during an adsorption time between 12 and 14 hours and thereby reducing a water content in the dried biomethane to below 20 mg/m³ (STP).

8. The process according to claim 1, which comprises cooling the regenerated adsorbents, prior to reuse, down to 10 to 30°

C. with cooled biomethane.

9. The process according to claim 8, which comprises cooling the regenerated adsorbents with cooled biomethane having a temperature of between 5 and 15°

C.

10. The process according to claim 1, which comprises indirectly heating at least a lower region of the adsorber during the regeneration.

11. The process according to claim 1, which comprises regenerating the laden adsorber under reduced pressure.