Patent Application
20230321587
The disclosed subject matter relates to an air purification and circulation system that removes ammonia, dust, and pathogens from air being recirculated within a facility for rearing/sheltering animals. Specifically, the subject matter described herein relates to a multistage system in which the particulate matter (dust), pathogens and ammonia are removed from the air inside a poultry or swine facility preferably using recycled liquids (water and acid, respectively), which are kept virtually particulate-free via a filtration system.
One of the biggest environmental and production challenges associated with raising animals in confined conditions is the production and emission of ammonia (NH3)—which frequently reaches high concentrations in the air within an animal confinement facility. High concentrations of ammonia in poultry facilities cause reduced growth rates, poor feed conversion, reduced egg production and increase the animals' susceptibility to diseases, such as Newcastle disease and airsaculitis in poultry. High levels of ammonia also pose health issues for humans who work in the facilities.
Ammonia emissions from animal rearing facilities also result in air, soil, and water pollution. Ammonia reacts with sulfate and nitrate in the atmosphere to form fine particulates which can cause human respiratory problems and haze. Ammonia deposition can result in eutrophication due to excessive nitrogen loading via wet and dry fallout in both aquatic and terrestrial systems. Once deposited from the atmosphere, ammonia can be converted to nitrate in soils via nitrification—a process which can cause serious soil acidification. In some European countries (e.g. the Netherlands), ammonia emissions are closely regulated by the government. As a result, many of the European swine barns and some poultry barns have utilized expensive ammonia scrubbers for decades. These scrubbers purify the air as it is exhausted from these facilities (i.e.—end of pipe technology) using sulfuric acid to capture ammonia. Since the air inside these facilities is not being purified, the only economic benefit to farmers from these systems is the capture of nitrogen, which can be used as fertilizer. However, nitrogen fertilizer is relatively inexpensive and has about the same value as the acid used to scrub the nitrogen from the air. Consequently, from an economic perspective, these scrubbers are not cost-effective.
Similarly, the ammonia scrubbers developed by the US Department of Agriculture (USDA), Agricultural Research Service (ARS) (e.g. U.S. Pat. Nos. 7,194,170 and 8,663,551), the Ohio State University (e.g. U.S. Pat. Nos. 8,961,915, 9,364,787, and 9,808,758), North Carolina State University (Shah et al., 2008; Trans. ASABE 51:243-250), Purdue University (Lahav et al., 2008; Water Air Soil Pollut 191:183-197) and the University of Arkansas (Bandekar et al., 2008; ASABE paper 083945) are also all “end of pipe” technology which use sulfuric acid, other acids or water to remove ammonia from the air after it is exhausted from poultry and swine facilities. Since the only economic benefit from these end-of-pipe ammonia scrubbers is the capture of nitrogen, which is relatively cheap, these scrubbers are not currently used in the United States.
The only technology that is widely used in the US for controlling ammonia levels in poultry houses is treating poultry litter with acidifying chemicals, such as aluminum sulfate (alum) or sodium bisulfate, which shift the ammonia/ammonium equilibrium in the litter towards ammonium as a result of lower litter pH, which reduces ammonia emissions. Lowering ammonia levels results in heavier birds, better feed conversion, and a lower mortality rate. Lowering the ammonia level with acidifying chemicals also lowers propane use (relative to “end of pipe” ventilation) due to decreased ventilation requirements. However, acid litter amendments only work for the first 2-4 weeks of a flock when the litter pH is below 7. After that time, ammonia emissions resume, and much of the ammonia that was captured can be released into the air. Consequently, other methods of controlling ammonia inside chicken houses are needed that will control ammonia concentrations throughout the flock
The biggest hurdle for the development of ammonia scrubbers for poultry houses (particularly broiler houses) is the tremendous amount of dust present in the air, which quickly builds up inside scrubbers, causing clogging of nozzles used for spraying water or acid, and clogging of demisters. Simple filters, such as the filters used in conventional air conditioning and heating systems, are not at all feasible for broiler houses because they would clog almost immediately due to excessive dust. In order to develop an ammonia scrubber for broiler houses, a radical change in the entire scrubber system is needed that can remove all particulate material from the air without causing any clogging in the system.
Therefore, the need exists for a cost-effective and efficient air purification system for removing the ammonia, dust and pathogens from the air inside animal rearing/housing facilities that recirculates the treated air within the facility. The current invention is an innovative air scrubbing system which removes ammonia, particulate material and pathogens from the air during the purification process. The system preferably utilizes fast sand-type filters to remove particulate matter from liquids being sprayed to prevent clogging in the system. Lower ammonia levels inside animal rearing facilities will result in several economic benefits, including improved animal weight gains and feed conversion, reduced susceptibility to disease, lower mortality and decreased ventilation rates, which result in less propane needed for heating. Lower propane use will result in significant reductions in carbon dioxide emissions, thereby improving the operation's carbon footprint. The lower ammonia, dust and pathogen concentrations in the air will also provide a healthier working environment for the people working in the affected facilities.
This disclosure is directed to an air purification and circulation system designed to purify and circulate air within an animal rearing/sheltering facility. In accordance with the current invention, air from inside the facility is drawn into the air purification and circulation system. Specifically, the air is first drawn into a dust scrubbing section of the system. The dust scrubbing section includes at least one dust scrubbing water sprayer that sprays a fine mist of particulate-free water. In the dust scrubbing section, airborne particulate matter (including dust and pathogens) collides with water droplets and is removed from the air by absorption. The water with entrained dust then falls to the bottom of the dust scrubbing section. The system is structured so that the contaminated water then flows via gravity to a fast sand filter where the particulate matter is removed from the water. The resulting particulate-free water is then recycled back through the dust scrubbing water sprayers.
After the air leaves the dust scrubbing section, the air flows into an ammonia scrubbing section that is positioned in tandem with the dust scrubbing section. The ammonia scrubbing section comprises at least one ammonia scrubbing acid sprayer that sprays a fine particulate-free acidic treatment solution. In the ammonia scrubbing section, airborne ammonia collides with fine droplets of the acid solution and is removed from the air by absorption. The droplets then fall to the bottom of the ammonia scrubbing section. Fugitive dust which was not collected in the dust scrubbing section will also be captured via collision with the acid droplets and will also fall to the bottom of this chamber. The system is structured so that the acidic solution containing captured ammonia and particulate matter flows by gravity to a second fast sand filter where the particulate matter is removed from the acidic solution. The resulting particulate-free acidic treatment solution is then recycled back through the ammonia scrubbing acid sprayers.
After the air leaves the ammonia scrubbing section, the air flows into an acid scrubbing section that is positioned in tandem with the ammonia scrubbing section. The acid scrubbing section comprises at least one acid scrubbing water sprayer spraying a particulate-free fine water mist. In the acid scrubbing section, the nozzles will be spraying medium-sized water droplets to capture fugitive acid droplets that drifted into this section via absorption. The increase in the size of the droplets from fine (145 to 225) to medium sized (226 to 325 um) will greatly increase the droplet weight. Heavier droplets fall more quickly and are less affected by air movement, which will result in less drift of water droplets into the final section. The medium sized water droplets will also combine with fugitive particulate matter and ammonia that was not removed in the dust scrubbing or ammonia scrubbing sections. The water containing fugitive acid, dust and ammonia will fall to the floor and flow to a drain, where it will flow back to first fast sand filter, where any particulate matter is removed before it is recycled back into the dust scrubbing and the acid scrubbing sections.
After the air leaves the acid scrubbing section, it will pass into the demisting section that is positioned in tandem with the acid scrubbing section. The airflow will change from horizontal to vertical in this section, then the air will pass through a demister before exiting the scrubber.
Wherein, the system is structured so that, as air is drawn into the system, the dust scrubbing section of the system removes airborne dust from the air, and the ammonia scrubbing section removes airborne ammonia from the air. The air then flows into the acid scrubbing section which removes any remaining acid fumes from the air. After the air leaves the acid scrubbing section, the purified air then passes through one or more demisters to remove water droplets and the air is exhausted back into the animal rearing/housing facility.
Note that some assemblies/systems in the FIGs. may contain multiple examples of essentially the same component. For simplicity and clarity, only one (or a few) of the example components may be identified with a reference number. Unless otherwise specified, other non-referenced components with essentially the same structure as the exemplary component should be considered to be identified by the same reference number as the exemplary component. Also note that the FIGs. are not intended to be to scale.
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For the purposes of this disclosure, an “animal rearing/housing facility” 14 may comprise a conventional barn-type facility having a roof and walls enclosing an animal housing/rearing area. This definition encompasses essentially all animal containment facilities 14 having a roof and walls enclosing the animal containment area. In the preferred embodiment, the facility 14 is structured so that the air treatment apparatus 15 of the system 10 is enclosed within the animal rearing/housing facility 14. In alternative embodiments, the water and acid filter systems 70, 100, and the concentrated acid tank 115 may also be enclosed within the facility 14.
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The variable speed fan 26 pushes the incoming air through an air inlet partition 28 and into a dust scrubbing section 30. In the preferred embodiment, the air inlet partition 28 comprises a planar, vertical, wall-type slotted structure with angled slats 27 extending from the wall. The partition 28 is configured so that most of the liquid in the dust scrubbing section 30 is retained and stays within the section 30. In alternative embodiments, the dust scrubbing section partition 28 may comprise any structure known in the art consistent with the function of retaining spray and moisture within the dust scrubbing section 30 while allowing incoming air to flow into the section 30.
In the dust scrubbing section 30, a system of water sprayers 32 continuously sprays fine, particle-free water droplets that collide with and remove airborne particulate matter (dust) and pathogens from the incoming air via absorption. The “muddy” water with entrained dust particles then falls to the bottom of the dust scrubbing section 30, and then runs out of the air treatment apparatus 15 through the dust scrubbing section drain 37 in the direction of the arrow 39.
For the purposes of this disclosure, a “sprayer” is defined as essentially anything that sprays. The term “sprayer” includes all types of nozzles (including jet nozzles), as well as configurations that only comprise an aperture and may not include a conventional nozzle at all. In the preferred embodiment, the sprayers described herein (32, 33, 42, 43, 52, 53) are fitted with cone or hollow cone spray tips that produce fine or medium sized droplets. Anti-clogging nozzles could also be utilized, but should not be needed since the water and acid solution being sprayed will be virtually particulate-free.
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For the purposes of this disclosure, a “fast sand water filter” comprises a filter structure wherein incoming liquid is filtered through at least one layer (and preferably multiple layers) of sand and/or rock as a means of removing (at least) particulate material from the incoming liquid.
In the preferred embodiment, the fast sand water filter medium 73 comprises a first layer of fine sand 72; a layer of coarse sand 74; a layer of pea gravel 76; and a layer of large stones 78. A separating grate/screen may cover the top of the fine sand layer 72 and separate the other filter layers 74, 76, 78. A pour-over drain 80 extends between the large stone layer 78 and a water reservoir 83 where the filtered water 84 collects. In alternative embodiments, the filter medium 72, 74, 76, 78 of the fast sand water filter may also comprise other materials in addition to (or instead of) sand, stone, or rock. For example, the fast sand water filter may comprise multiple materials including (but not limited to) metals, plastics, glass, composites, diatomaceous earth, or essentially any other filtering material capable of filtering dust and/or pathogens from a water solution.
For the purposes of this disclosure, a “pour over drain” comprises a drain configured to enable a fluid to drain laterally from one discrete area to another. In the preferred embodiment, the pour-over drain 80 comprises a perforated pipe, however in alternative embodiments, the pour-over drain 80 may comprise a tubular length of wire mesh, or any other permeable means of transferring filtered water/liquid from the lowest filter medium 78 to the reservoir 83 side of the filter system 70. Ultimately filtered/recycled particulate-free water 84 flows from the coarse filtering medium 78 into the water reservoir 83. For the purposes of this disclosure, “filtered/recycled fluid” comprises a fluid (such as acid or water) that has been through a filtration process. For example, a fluid that been through a fast sand water filter or a fast sand-type acid filter. In the preferred embodiment, the filter process removes at least particulate matter such as dust and/or pathogens.
In the preferred embodiment, the reservoir side 83 of the fast sand water filter system 70 preferably includes a float switch 92 that activates a valve 93 (connected to the fast sand water filter system controller 95) that opens when the water level gets below a predetermined level and introduces “tap” water into the reservoir 83 from an outlet 82 in the direction of the arrow 81 until the water level in the reservoir 83 reaches the desired depth at which time the valve 93 closes and turns the tap water off. The tap water that flows into the reservoir 83 may be from municipal sources or water from wells, rainfall collected from animal housing roofs, or surface water from ponds, lakes, rivers, or streams. The float switch 92, which is identical in function to that used inside of a commode or toilet, is needed to replenish water losses from evaporation or other loss mechanisms. In at least one alternative embodiment, the water filter system controller 95 communicates via a wired or wireless link 94 with the main system controller 65 (shown in
The fast sand filter reservoir 83 also comprises an overflow pipe 97 which controls the upper limit of the water level in the reservoir 83. In the preferred embodiment, this pipe 97 is connected to a filter field (not shown) adjacent to facility 14—which is very similar to that utilized for wastewater disposal in sewage systems utilizing septic tanks. The system 70 is designed so that if water enters the system 70 at an unanticipated rate (for example when the inside of the air scrubber 15 is being cleaned by power-washing), then the reservoir water 84 will flow (preferably via gravity) out of the filter system 70 via the outlet 97 in the direction of the arrow 99. In the preferred embodiment, the overflow water is directed to a filter field (not shown) adjacent to the facility 14.
The dust in the air of poultry houses 14 includes large quantities of poultry manure, which has high concentrations of many nutrients, including ammonium, magnesium and phosphate which can precipitate in pipes under certain conditions as the mineral struvite (NH4MgPO4·6H2O) causing blockage of the pipes. Hence, it is possible that this could occur in pipes leading to or from the fast sand filter 70 if the pH and nutrient levels of the water were right for its formation. One solution to this problem would be for the operator to allow “tap” water to continuously flow into the reservoir 83 at a very slow rate, such as a few gallons per day, diluting the nutrient concentration so that struvite will not form. The excess water would flow through the pipe 97 into the filter field.
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The dust scrubbing section 30 may also comprise an electrostatic charging system 31 that imparts an electrical charge to the water droplets that comprise the fine water mist. Multiple types of electrostatic charging systems 31 are available. All electrostatic charging systems 31 capable of imparting an electrical charge to the fine water mist as the mist is sprayed within the dust scrubbing section 30 should be considered to be within the scope of the invention.
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In alternative embodiments, other types of partition 34 structures may be used. In further alternative embodiments demister(s) may be used rather than a simple slatted partition 34. As will be described infra, the structure and description of the ammonia scrubbing section partition 44, and the acid scrubbing section partition 54 are essentially identical to the structure of the dust scrubbing section partition 34 as shown in
The ammonia scrubbing section 40 is preferably positioned in tandem with the dust scrubbing section 30. In the ammonia scrubbing section 40, a particle-free dilute “acidic treatment solution” is sprayed from multiple acid sprayers 42, 43. For the purposes of this disclosure, an “acidic treatment solution” is defined as an acid/water solution having a pH of less than 7.0. In the preferred embodiment, the pH of the solution is less than 4.0. Further, in the preferred embodiment, the acid used in the ammonia scrubber section 40 should be a strong acid, such as sulfuric acid. However, in alternative embodiments, hydrochloric acid, phosphoric acid, nitric acid or multiple other types of acid may alternatively be used. The structure and basic spraying function of the acid sprayers 42, 43 in the ammonia scrubbing section 40 is essentially identical to the structure and function of the water sprayers 32, 33 described supra—except that the acid sprayers 42, 43 in the ammonia scrubbing section 40 spray an acidic treatment solution. The sprayers 42, 43 are designed to continuously deliver a particle-free fine spray of acidic treatment solution across the diameter of the ammonia scrubbing section 40. In the ammonia scrubbing section 40, the airborne ammonia and “fugitive dust” is removed from the incoming air by colliding with the fine acid droplets being sprayed via absorption. The resulting (ammonia-containing) acid treatment solution and fugitive dust then falls to the bottom of the ammonia scrubbing section 40. and ultimately flows out of the section 40 through a drain 47 in the direction of the arrow 49. For the purposes of this disclosure, “fugitive dust” is defined as any dust that remains airborne and is not successfully removed from the incoming air in the dust scrubbing section 30. Fugitive dust may be present in the ammonia scrubbing section 40, the acid scrubbing section 50, or the outlet section 60. An objective of the current invention is to remove all dust (including fugitive dust) from the air before the (treated) air is exhausted back into the animal rearing facility 14. Significantly, the amount of acidity present in acidic treatment solution that is sprayed in the ammonia scrubbing section 40 is significantly greater than the alkalinity that results from the absorption of the airborne ammonia. Eventually, as best shown in
Significantly, the filtering materials 102 of the acid filter system 100 are not limited to sand/rock, but the acid filter system 100 may comprise any nodules/grains of the appropriately sized medium/materials consistent with the functions of filtering the liquid and remaining impervious to the type of acid sprayed in the ammonia scrubbing section 40. For example, the acid filter medium/materials 102 may comprise multiple other materials including (but not limited to) metals, plastics, glass, composites, stone, sand, rock, diatomaceous earth, or essentially any other acid resistant filtering particulate materials from the water solution. Ultimately, filtered/recycled acidic treatment solution 106 flows from the filtering medium 102 through a pour-over drain 80 and into the filtered/recycled acid reservoir 113. Similar to the water filter system 70, the acid filter system 100 includes a float switch 101 that opens a valve 103 attached to the acid filter system controller 105 when the acid level gets below a predetermined level. When the valve opens, “tap” water flows into the reservoir 113, 106, through the outlet 110 in the direction of the arrow 109 until the acid/water level reaches the desired depth—at which time the valve 103 closes and the flow of tap water is stopped. This type of float switch, which is almost identical to that used inside of a commode or toilet, is needed to replenish losses due to evaporation or other mechanisms. In at least one alternative embodiment, the acid filter system controller 105 communicates via a wired or wireless link 114 with the main system controller 65 (shown in
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In alternative embodiments, the acid pump in the concentrated acid tank 115 may be outside of the acid tank 115, and/or the pump may be manually operated to add additional acid to the acid filter reservoir 113. In an alternative embodiment acid can simply be added to the reservoir 113 manually without the aid of a pump.
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Over time the ammonium concentration in the acid solution 106 will increase until it reaches very high levels. When the ammonium concentration in the acid solution 106 reaches the desired level for fertilization of crops, then the operator could program the acid filter system controller 105 to stop adding acid to the reservoir 113. After some time, the ammonia being scrubbed from the air would neutralize the acidity of the acid solution 106 and the pH of this solution would increase. When the pH reached levels acceptable for crop fertilization (preferably between pH 5 and 7), the operator would be notified by the main system controller 65. The pH preferably should be above 5 to prevent soil acidification and below 7 to prevent ammonia volatilization during or after fertilization. If sulfuric acid is being used as the acid source, then the liquid ammonium fertilizer would be in the form of ammonium sulfate, whereas if nitric acid were used then the fertilizer would be ammonium nitrate, likewise if phosphoric acid was used then ammonium phosphate fertilizer would be formed, or if hydrochloric acid were used then ammonium chloride would be formed.
In an alternative embodiment, when the ammonium concentration in the acid solution 106 reaches the desired level for fertilization of crops, then the operator could program the pH control to stop adding acid to reservoir 113 and add base, such as, but not limited to, sodium hydroxide or sodium bicarbonate, to speed up the process of acid neutralization to pH 5-7.
In the preferred embodiment the neutralized ammonium solution would be pumped into a tank on a truck, which is driven to nearby fields in pastures or row crops and the liquid ammonium fertilizer can be applied as needed for crop growth.
In an alternative embodiment the neutralized ammonium solution can be pumped directly from the reservoir 113 onto pastures or row crops using irrigation equipment (i.e.—fertigation).
In an alternative embodiment, the ammonium solution can be pumped into trucks and transported to fertilizer plants where it can be further processed into solid ammonium fertilizers, such as ammonium sulfate, ammonium nitrate or ammonium phosphate.
In an alternative embodiment, when the ammonium concentration of the acid solution 106 reaches the desired level, but weather conditions or other variables are not favorable for fertilization of crops, then the operator could pump the contents into a much larger storage reservoir or a holding pond prior to neutralization.
The ammonia scrubbing section 40 may also comprise an electrostatic charging system 41 that imparts an electrical charge to the acidic treatment solution droplets being sprayed. Multiple types of electrostatic charging systems 41 are available. All electrostatic charging systems 41 capable of imparting an electrical charge to the fine water mist as the mist is sprayed within the ammonia scrubbing section 40 should be considered to be within the scope of the invention.
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The acid scrubbing section 50 is configured to remove any remaining acid droplets or fumes from the air. The acid scrubbing section 50 is preferably positioned in tandem with the ammonia scrubbing section 40. In the acid scrubbing section 50, a fine particle-free water mist is sprayed from multiple water sprayers 52, 53. The structure and basic spraying function of the acid scrubbing section water sprayers 52, 53 is essentially identical to the structure and spraying function of the dust scrubbing water sprayers 32, 33 in the dust scrubbing section 30, except the size of the water droplets is larger (medium rather than fine) so that the drift of the water droplets into section 50 is minimized. The water sprayers 52, 53 in the acid scrubbing section 50 are designed to continuously deliver medium-sized water droplets across the diameter of the acid scrubbing section 50.
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The acid scrubbing section 50 may also comprise an electrostatic charging system 51 that imparts an electrical charge to the water droplets being sprayed. Multiple types of electrostatic charging systems 51 are available. All electrostatic charging systems 51 capable of imparting an electrical charge to the fine water mist as the mist is sprayed within the acid scrubbing section 50 should be considered to be within the scope of the invention.
In further alternative embodiments, the liquid from acid scrubbing section 50 may be recycled through other means, or the liquid may be used for other purposes that are not associated with the air purification and recirculation system 10 so that the liquid flowing out of the acid scrubbing section 50 is not connected to a water filter system 70.
Air then flows through the acid scrubbing section partition 54 and leaves the acid scrubbing section 50. The design of the acid scrubbing section partition 54 is essentially identical to the design of the dust and ammonia scrubbing section partitions 34, 44 described supra and may or may not have a demister.
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In the preferred embodiment, the demister 64 comprises a mist eliminator that is a vertically oriented chevron blade separator. After the air leaves the outlet section, the “treated air” is preferably directed to the front of the facility. For the purposes of this disclosure, “treated air” is defined as air that is essentially free of at least dust and ammonia.
Any water droplets formed in the demister will fall out of the air outlet section 60 and flow out of the air outlet section drain 67 in the direction of the arrow 69. As best shown in
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The air purification and circulation system 10 comprises various feedback systems that may monitor and/or control the function of the system 10. For example, a main system controller 65 comprises a processor and an operator's visual display 66 (such as a computer screen), a means of alerting an operator (such as a tone, bells, lights, or a prompt on another electronic device such as a cell phone), and a means for the operator to input instructions into the system (such as a touchscreen, keyboard, or mouse). The main system controller 65 may monitor the pressure in each air treatment apparatus section 20, 30, 40, 50, 60 and the ammonia and/or acid content of the treated air passing through the outlet section. The main system controller 65 may also monitor (as required) the conditions and status of the fast sand water filter system and the acid filter system via the associated controllers 95, 105.
Additionally, the operator's processor and visual display 66 is in communication (via the main system controller 65) with at least the variable speed fan 26 as well as the fast sand water filter system controller 95 and the acid filter system controller 105. Based on the ammonia content of the air flowing through the outlet section 60 (as measured by an ammonia sensor 71), the operator may manually or automatically adjust at least the speed of the fan 26 (if ammonia levels are high, then the fan speed is reduced), and the operator may also adjust other system parameters.
Additionally, the system 10 includes pressure sensors 38, 48, 58, 68 positioned in each air treatment apparatus section 30, 40, 50, 60 and outside of air treatment mechanism 15. The main system controller 65 monitors the pressure drop between each of the sensors 38, 48, 58, 68, and the ambient conditions outside of the scrubber. If reduced air flow occurs, as indicated by a slight pressure drop, then the fan speed may be automatically varied by the main system controller 65. Likewise, a significant pressure drop may indicate a blockage or other significant problems requiring the main system controller 65 to shut down at least the fan 26 and alert the operator.
In the preferred embodiment, the diameter/width and the length of each of the treatment sections 20, 30, 40, 50, 60 is 60″ (1.524 m)— depending upon the needs of an operator and the specific dimensions and characteristics of the housing/rearing facility 14. The variable speed fan 26 preferably operates at 7,500 cfm (212.4 m3/min or 3.54 m3/s) and the air speed through the system 10 is 1.524 m/s so that the air residence time in each section 30, 40, 50, 60 would be 1.0 second.
In an alternative embodiment, particularly in an application in which the poultry producer has no land in pastures or crop production or does not wish to utilize the captured ammonia or cannot afford the system described above or for other reasons, the system described herein can be simplified (reduced) so that there is only one fast sand filter (fast sand filter 100) rather than two, which is used for acidic water purification. In this embodiment, referred to as the “one filter system”, the drains 39, 49, 59, and 69 from sections 30, 40, 50 and 60 drain directly to the acid sand filter 100, and acidified water from reservoir 113 is pumped to all of the nozzles in sections 30, 40, and 50.
In a further embodiment of the one filter system described above, the captured ammonia is not utilized for pasture or crop production but is disposed of in the filter field. In this embodiment, water is slowly added either continuously or semi-continuously to reservoir 113 so that drainage is always occurring from pipe 107 into the filter field. In this case, the filter field should be properly designed so that it is large enough to process such a high nitrogen loading rate and the land should be limed regularly to avoid soil acidification. While disposing of an important nutrient resource in this manner is not as sustainable as using it for fertilizer, it is still far better for the environment than allowing the ammonia to escape the animal rearing facility into the atmosphere where it pollutes air, soil and water resources. From an economic point of view, the value of the ammonium being captured with this technology is relatively insignificant when compared to the tremendous economic gains from improved poultry production and reduced energy costs due to lower ammonia levels in the rearing facilities.
In another embodiment of the one filter system with “tap” water running continuously, the “tap” water source is from a well or surface water source (river, stream, pond or lake) with water that consistently has a pH at or below pH 7 is utilized so that no acid is added to reservoir 106. Such a system would not only require far lower investment costs but may also have lower operating costs since it does not use acid, even if the ammonium is not being utilized for fertilizer. It should be noted that the length of the air purification unit 15 would not likely be shortened with this system, even though there would not be separate sections for dust, ammonia and acid fume removal. The kinetics of ammonia scrubbing with solutions having pHs from 4 to 7 are much slower than when the pH is much more acidic, such as 2 to 4, hence, more residence time would be needed to remove the ammonia. This can be achieved by either slowing down the air flow of the variable speed fan or by increasing the area of the ammonia scrubber. Since sections 30, 40, and 50 would all be spraying slightly acidic water, the residence time of ammonia scrubbing would basically be tripled which would be needed for ammonia removal using water with low acidity.
In another embodiment of the one filter system, water is pumped directly from reservoir 113 and used for irrigation (fertigation) onto row crops or pastures. In another embodiment the water is pumped into a container or holding pond from which it is pumped onto row crops or pastures, providing both irrigation water and nitrogen fertilizer.
For the foregoing reasons, it is clear that the subject matter described herein provides an innovative air purification and circulation system 10 for air inside an animal rearing/sheltering facility 14. The current system may be modified in multiple ways and applied in various technological applications. The disclosed system may be modified and customized as required by a specific operation or application, and the individual components may be modified and defined, as required, to achieve the desired result.
Although the materials of construction are generally described, they may also include a variety of compositions consistent with the function described herein. Such variations are not to be regarded as a departure from the spirit and scope of this disclosure, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
The amounts, percentages and ranges disclosed in this specification are not meant to be limiting, and increments between the recited amounts, percentages and ranges are specifically envisioned as part of the invention. All ranges and parameters disclosed herein are understood to encompass any and all sub-ranges subsumed therein, and every number between the endpoints. For example, a stated range of “1 to 10” should be considered to include any and all sub-ranges between (and inclusive of) the minimum value of 1 and the maximum value of 10 including all integer values and decimal values; that is, all sub-ranges beginning with a minimum value of 1 or more, (e.g., 1 to 6.1), and ending with a maximum value of 10 or less, (e.g. 2.3 to 9.4, 3 to 8, 4 to 7), and finally to each number 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 contained within the range.
Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth as used in the specification and claims are to be understood as being modified in all instances by the implied term “about.” If the (stated or implied) term “about” precedes a numerically quantifiable measurement, that measurement is assumed to vary by as much as 10%. Essentially, as used herein, the term “about” refers to a quantity, level, value, or amount that varies by as much 10% to a reference quantity, level, value, or amount. Accordingly, unless otherwise indicated, the numerical properties set forth in the following specification and claims are approximations that may vary depending on the desired properties sought to be obtained in embodiments of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are now described.
The term “consisting essentially of” or excludes additional method (or process) steps or composition components that substantially interfere with the intended activity of the method (or process) or composition and can be readily determined by those skilled in the art (for example, from a consideration of this specification or practice of the invention disclosed herein). The invention illustratively disclosed herein suitably may be practiced in the absence of any element which is not specifically disclosed herein. The term “an effective amount” as applied to a component or a function excludes trace amounts of the component, or the presence of a component or a function in a form or a way that one of ordinary skill would consider not to have a material effect on an associated product or process.
