Efficient use of adsorbents for indoor air scrubbing

• US 9,566,545 B2
• Filed: 05/22/2013
• Issued: 02/14/2017
• Est. Priority Date: 05/22/2012
• Status: Active Grant

• Current Assignee: Enverid Systems, Inc.
• Original Assignee: Enverid Systems, Inc.
• Inventors: Meirav, Udi, Biran, Israel
• Primary Examiner(s): LAWRENCE JR, FRANK M
• Application Number:
  US14/403,562
• Publication Number:
  US 20150321135A1
• Time in Patent Office: 1,364 Days
• Field of Search: 95/8, 95/11, 951/39, 951/41, 951/43, 951/37, 951/27, 951/29, 951/40, 951/48, 961/11, 961/21, 961/44, 423/230
• US Class Current: 1/1
• CPC Class Codes: B01D 2252/204 Amines
• CPC Class Codes: B01D 2253/102 Carbon
• 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 2253/11 Clays
• CPC Class Codes: B01D 2253/1124 Metal oxides
• CPC Class Codes: B01D 2253/116 Molecular sieves other than zeolites
• CPC Class Codes: B01D 2253/20 Organic adsorbents
• CPC Class Codes: B01D 2253/202 Polymeric adsorbents
• CPC Class Codes: B01D 2253/204 Metal organic frameworks (MOF's)
• CPC Class Codes: B01D 2253/25 Coated, impregnated or composite adsorbents
• CPC Class Codes: B01D 2255/20707 Titanium
• CPC Class Codes: B01D 2257/11 Noble gases
• CPC Class Codes: B01D 2257/302 Sulfur oxides
• CPC Class Codes: B01D 2257/404 Nitrogen oxides other than dinitrogen oxide
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/504 Carbon dioxide
• CPC Class Codes: B01D 2257/708 Volatile organic compounds V.O.C.'s
• CPC Class Codes: B01D 2258/0283 Flue gases
• CPC Class Codes: B01D 2258/06 : Polluted air
• CPC Class Codes: B01D 2259/4145 : arranged in series
• CPC Class Codes: B01D 2259/4508 : for cleaning air in buildings
• CPC Class Codes: B01D 53/0407 : Constructional details of adsorbing systems
• CPC Class Codes: B01D 53/0446 : Means for feeding or distributing gases
• CPC Class Codes: B01D 53/0454 : Controlling adsorption controlling temperature swing adsorption B01D53/0462, controlling pressure swing adsorption B01D53/047
• CPC Class Codes: B01D 53/346 : Controlling the process
• CPC Class Codes: B01D 53/82 : with stationary reactants
• CPC Class Codes: B01D 53/96 : Regeneration, reactivation or recycling of reactants
• CPC Class Codes: Y02C 20/10 : of nitrous oxide (N2O)
• CPC Class Codes: Y02C 20/40 : of CO2

Abstract

Some embodiments of the disclosure correspond to, for example, a method for controlling a scrubber containing an adsorbent. The scrubber may be configured to cycle between scrubbing at least one pollutant/gas from a stream of gases with the pollutant/gas being adsorbed onto the adsorbent, and regenerating at least some of the adsorbent and thereby purging at least some of the one pollutant and/or first gas from the adsorbent via a regeneration gas flow. The method may include flowing a stream of gases through the scrubber, the scrubber including the adsorbent and adsorbing at least some of the one pollutant/gas from the stream of gases onto the adsorbent during an adsorption phase over a first time period. The method may also include purging at least a portion of the one pollutant/gas from the adsorbent during a regeneration phase over a second time period with a regeneration gas flow, and cycling therebetween.

Claims

1. A method for controlling a scrubber containing an adsorbent, the scrubber configured to cycle between scrubbing at least one pollutant and/or first gas from a stream of gases with the at least one pollutant and/or first gas being adsorbed onto the adsorbent, and regenerating at least some of the adsorbent and thereby purging at least some of the at least one pollutant and/or first gas from the adsorbent via a regeneration gas flow, the method comprising:

flowing a stream of gases through the scrubber, the scrubber comprising the adsorbent;

adsorbing at least some of the one pollutant and/or first gas from the stream of gases onto the adsorbent during an adsorption phase over a first time period;

purging a portion of the at least one pollutant and/or first gas from the adsorbent during a regeneration phase over a second time period with a regeneration gas flow, and cycling between the adsorption phase and the regeneration phase, wherein

one cycle comprises at least an adsorption phase followed by a regeneration phase,

one cycle period comprises the total time elapsed during one cycle,

the at least one pollutant and/or first gas purged from the adsorbent is carried away by the regeneration gas flow,

a complete regeneration phase comprises a time period for removing substantially all of the pollutant and/or first gas from the adsorbent during the regeneration phase, and

a complete adsorption phase comprises a time period for substantially saturating all the adsorbent during the adsorption;

and

limiting at least one of;

the duration of the first time period to a period of time T_a which is less than the complete adsorption phase, and

the duration of the second time period to a period of time T_r which is less than the complete regeneration phase, wherein

a productivity of the scrubber is optimized as a function of at least one of T_a and T_r, with productivity comprising an amount of the at least one pollutant and/or first gas removed over the one cycle period.

2. The method of claim 1, wherein the first time period comprises about 95% of a complete adsorption phase.

3. The method of claim 1, wherein the first time period is about 90% of a complete adsorption phase.

4. The method of claim 1, wherein the first time period is about 80% of a complete adsorption phase.

5. The method of claim 1, wherein the first time period is about 50% of a complete adsorption phase.

6. The method of claim 1, wherein the first time period is about 20% of a complete adsorption phase.

7. The method of claim 1, wherein the first time period comprises about 20% to about 95% of a complete adsorption phase.

8. The method of claim 1, wherein the second time period comprises about 95% of a complete regeneration phase.

9. The method of claim 1, wherein the second time period is about 90% of a complete regeneration phase.

10. The method of claim 1, wherein the second time period is about 80% of a complete regeneration phase.

11. The method of claim 1, wherein the second time period is about 50% of a complete regeneration phase.

12. The method of claim 1, wherein the second time period is about 20% of a complete regeneration phase.

13. The method of claim 1, wherein the second time period comprises about 20% to about 95% of a complete regeneration phase.

14. The method of claim 1, wherein:

the regeneration phase is terminated upon a regeneration rate R(t_r) of the adsorbent being between about equal to and a predetermined amount less than a productivity p of the complete regeneration phase, wherein

productivity p=C/T, and

C equals an amount of the pollutant and/or first gas adsorbed by the adsorbent from the stream of gases during one cycle and T is the duration of one cycle period.

15. The method of claim 1, wherein:

the regeneration phase is terminated upon a regeneration rate R(t_r) being between about equal to and about twice a productivity p of the complete regeneration phase, wherein productivity p=C/T, and

C equals an amount of the pollutant and/or first gas adsorbed by the adsorbent from the stream of gases during one cycle and Tis the duration of one cycle period.

16. The method of claim 1, wherein the pollutant and/or first gas is selected from the group consisting of:

carbon dioxide, volatile organic compounds, sulfur oxides, radon, nitrous oxides and carbon monoxide.

17. The method of claim 1, wherein the adsorbent comprises at least one of :

an amine supported by a solid, activated carbon, clay, carbon fibers, silica, alumina, zeolites, molecular sieves, titanium oxide, polymer, porous polymers, polymer fibers and metal organic frameworks.

18. The method of claim 17, wherein the supporting solid is at least one of silica, carbon, clay or metal oxide.

19. The method of claim 1, wherein the adsorbent comprises granular solids or pelleted shaped solids.

20. The method of claim 1, wherein the stream of gases comprises air from an enclosed environment, outdoor air, flue gases, or nitrogen with elevated levels of carbon dioxide or organic contaminants, relative to substantially unpolluted air.

21. The method of claim 1, wherein the one cycle further comprises at least one of:

(i) a first switchover phase prior to the regeneration phase, and

(ii) a second switchover phase following the regeneration phase.

22. The method of claim 21, wherein the second switch over phase comprises a period of time to bring the adsorbent to a temperature to adsorb the at least one pollutant and/or first gas during the adsorption phase.

23. The method of claim 21, wherein the first switchover phase comprises a period of time to bring the adsorbent to a temperature to release the at least one pollutant and/or first gas from the adsorbent during the regeneration phase.

24. The method of claim 1, wherein prior to streaming the regeneration gas flow the method further includes determining a level of an adsorption efficiency, wherein the adsorption efficiency at any point in time during the one cycle has a value of 1−

C_in/C_out, wherein C_in is the concentration of the pollutant in the incoming air flow and C_out is the concentration of the pollutant in an outgoing air flow, and wherein an initial adsorption efficiency value is the adsorption efficiency value at the beginning of the adsorption phase, wherein the adsorption efficiency value is less than the initial adsorption efficiency value, streaming of the regeneration gas flow over and/or through the adsorbent is performed.

25. A system for controlling a scrubber, the system comprising:

a scrubber containing an adsorbent, the scrubber configured to cycle between scrubbing at least one pollutant and/or first gas from a stream of gases with the at least one pollutant and/or first gas being adsorbed onto the adsorbent, and purging the at least one pollutant and/or first gas from the adsorbent via a regeneration gas flow;

means for flowing the stream of gases through the scrubber and over and/or through the adsorbent, wherein the adsorbent adsorbs at least one pollutant and/or first gas from the stream of gases during an adsorption phase over a first time period;

means for flowing the regeneration gas flow over the adsorbent for purging a portion of the pollutant and/or first gas from the adsorbent during a regeneration phase over a second time period with a regeneration gas flow, and

means for cycling between the adsorption phase and the regeneration phase,

wherein;

one cycle comprises one adsorption phase followed by one regeneration phase,

one cycle period comprises the total time elapsed during one cycle;

the pollutant and/or first gas purged from the adsorbent is carried away by the regeneration gas flow,

a complete regeneration phase comprises a time period for removing substantially all of the pollutant and/or first gas from the adsorbent during the regeneration phase,

a complete adsorption phase comprises a time period for substantially saturating all the adsorbant during the adsorption,

the duration of at least one of the following is limited;

the duration of the first time to a period of time T_a which is less than the complete adsorption phase, and

the duration of the second time period of time T_r which is less than the complete regeneration phase, and

productivity of the scrubber is optimized as a function of at least one of T_a and T_r, with productivity comprising an amount of the at least one pollutant and/or first gas removed over the one cycle period, wherein the means for cycling comprises a processor and a non-transitory machine-readable medium having computer instructions operating thereon for controlling cycling between the adsorption and regeneration phases.