Efficient use of adsorbents for indoor air scrubbing

• US 10,525,401 B2
• Filed: 02/10/2017
• Issued: 01/07/2020
• 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:
  US15/430,359
• Publication Number:
  US 20170225114A1
• Time in Patent Office: 1,061 Days
• Field of Search: 95 8, 95 11, 95139, 95141, 95143, 95137, 95127, 95129, 95140, 95148, 96111, 96121, 96144
• 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. An HVAC 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;

at least one of a damper, a fan, a valve, a shutter, a duct, an inlet, and an outlet configured for flowing the stream of gases through the scrubber and over and/or through the adsorbent, wherein the adsorbent adsorbs the at least one pollutant and/or first gas from the stream of gases during an adsorption phase over a first time period;

at least one of a damper, a fan, a valve, a shutter, a duct, an inlet, and an outlet configured for flowing the regeneration gas flow over the adsorbent for purging a portion of the adsorbed 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

a control unit for cycling between the adsorption phase and the regeneration phase including at least one processor and a non-transitory machine-readable medium storing instructions that, when executed by the at least one processor, perform the method comprising;

terminating the adsorption phase prior to a complete adsorption phase when an amount of the first time period that elapsed since a start of the adsorption phase indicates an adsorption efficiency value that is no greater than a fraction of an initial adsorption efficiency value of the adsorbent at the start of the adsorption phase; and

terminating the regeneration phase prior to a complete regeneration phase when an amount of the second time period that elapsed since a start of the regeneration phase indicates a regeneration rate that is within a predetermined range of a productivity of a complete regeneration phase of the adsorbent, wherein

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

the 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.

2. The system of claim 1, wherein the fraction is about 80%.

3. The system of claim 1, wherein the fraction is about 70%.

4. The system of claim 1, wherein the fraction is about 50%.

5. The system of claim 1, wherein the predetermined range lies between a lower limit about equal to the productivity of the complete regeneration phase and an upper limit about equal to twice the productivity of the complete regeneration phase.

6. The system of claim 1, wherein the predetermined range lies between a lower limit less than the productivity of the complete regeneration phase by a predetermined amount and an upper limit about equal to the productivity of the complete regeneration phase.

7. The system of claim 6, wherein the predetermined amount is in a range from about 20% of the productivity of the complete regeneration phase to about 98% of the productivity of the complete regeneration phase.

8. A method, comprising:

flowing a stream of gases through a scrubber, the scrubber including an adsorbent configured to adsorb at least one pollutant and/or first gas from a stream of gases containing the at least one pollutant and/or first gas 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 configured to carry away the purged portion, and

cycling between the adsorption phase and the regeneration phase while limiting at least one of;

a duration of the first time period to a period of time T_a which is less than a complete adsorption phase, the period of time T_a selected so as to improve a productivity of the scrubber in comparison to when the scrubber is cycled between the complete adsorption phase and a regeneration phase; and

a duration of the second time period to a period of time T_r which is less than a complete regeneration phase, the period of time T_r selected so as to improve the productivity of the scrubber in comparison to when the scrubber is cycled between the complete regeneration phase and an adsorption phase, wherein

a complete regeneration phase includes a time period for removing substantially all adsorbed 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.

9. The method of claim 8, wherein the first time period corresponds to a period of time in which about 90% of complete adsorption of the at least one pollutant and/or first gas by the adsorbent occurs.

10. The method of claim 8, wherein the first time period corresponds to a period of time in which about 80% of complete adsorption of the at least one pollutant and/or first gas by the adsorbent occurs.

11. The method of claim 8, wherein the first time period corresponds to a period of time in which about 50% of the complete adsorption of the at least one pollutant and/or first gas by the adsorbent occurs.

12. The method of claim 8, wherein the second time period corresponds to a period of time in which about 80% of complete regeneration of the adsorption occurs.

13. The method of claim 8, wherein the second time period corresponds to a period of time in which about 50% of complete regeneration of the adsorption occurs.

14. 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 improved as a function of at least one of T_a and T_r, with productivity comprising an average amount of the at least one pollutant and/or first gas removed per unit time.