Patent Application
20140338539
References Cited
U.S. Patent Documents
Foreign Patent Documents
Other Publications
Not Applicable.
Not Applicable.
1. Filed of the Invention
The present invention relates to simultaneous removal of ammonia gas and cooling air in livestock production confined facilities. More precisely, the present invention relates to Ammonia Gas Removal and Evaporative Air Cooling Apparatuses for use inside of the livestock houses and the ventilation fan ammonia removal device to be installed on the wall of the livestock houses, utilizing plastic rod screen media. The plastic rod screen media is fabricated with plastic rods using the unique characteristics of plastic rod: flowing down of water on the surface of the vertical plastic rods by gravity, surface tension of the plastic rod strong enough to hold the water on the surface of plastic rod against the strength of draughts in ventilation fans, and capability of contacting water and air on the surface of the plastic rods with barely resisting air flowing through the plastic rod screen media.
2. Description of the Related Art
The ammonia-gas-removal-and-air-cooling-apparatuses (ARAC) of the present invention is an apparatus simultaneously removing ammonia gas and cooling air in livestock confined facilities, which has three major purposes of its operation: the removal of NH3 which has two major purposes, one of them is to remove a precursor of greenhouse gas generating from livestock production facilities (i.e. reducing of greenhouse gases) and the other is to remove one of causes harmful for growing of livestock animals (i.e. increasing of livestock productions), and the third major purpose is to cool the livestock confined houses (i.e. preventing of thermal shock death of the livestock animals during hot weather). The NH3 producing during feeding of the livestock is harmful for growing of the livestock animals (significant to poultry), so that it should be removed to maintain its concentration in the livestock houses below its allowable level. During the summer time, the NH3 gas is removed along with operation of the tunnel ventilation, but in the winter time, its concentration usually rises higher than its allowable level, because the ventilation system is rarely operated to save the heating bill. High concentration of NH3 causes slow growing of animals leading to the reduction of the animal production. The tunnel ventilation system currently used for cooling the livestock confined houses does not have an enough cooling function during hot weather so occasionally a thermal shock death of the livestock occur. Eventually, the lost of the animal production increases.
Airborne contaminants generated from livestock production facilities include ammonia (NH3) and hydrogen sulfide (H2S), dust, and microorganisms. Among them, the NH3 and H2S are more affecting to environment than the other contaminants. Especially, the NH3 is an indirect source of greenhouse gas. Most of the NH3 and H2S generated in the livestock production confined houses, where the animals are mainly growing, are ventilated to surrounding environment without filtering as in open facilities. Such ventilated NH3 and H2S gases may add the sources of damage to environment and also residents' complaints due to their sharp, pungent, rotten egg smell. The NH3 gas is identified as one of the important noxious gases and causes a degradation or damage of water and soil quality, and ecosystem, when deposited over surrounding natural water bodies and land. Deposited NH3 on the soil is reacted with soil moist to produce NH4+ in the soil and decomposed by the consecutive denitrification processes of organic matter in soil to form nitrous oxide (N2O), long-lived greenhouse gas, see in “Nitrogen in the Environment.” Therefore, it is understood that the atmospheric NH3 releasing from the livestock facilities is converted to greenhouse gas N2O. Hydrogen sulfide (H2S) is also toxic gas to human health and its extremely low concentration irritates human nose, resulting in that residents living surrounding the livestock facilities complain the production of livestock near to their residents. Therefore, the H2S should be removed from the ventilated air to reduce the source of the residents' complaints due to the operations of the livestock. Eventually, both of NH3 and H2S should be removed from the ventilated air to protect natural environment and to reduce the complaints of the residents around the livestock production houses.
Currently, to reduce the amount of the NH3 gas ventilated from the livestock houses, several operating practices such as reducing of protein contents in feeding or often uses of new litter at every flock of poultry are applied. Such practices may have disadvantage of increasing the poultry or swine prices. But it is reported that such methods can reduce up to 30 to 45% of ventilated NH3 gas depending on controlling diet, see more information in “PSCI and IRDA, 2003.” This means that a large amount of NH3 gas is still ventilated. The modern poultry houses are cooled by tunnel ventilation system assisted with wall cooling pad. This system has a weak cooling function of hot air. To meet the cooling condition of the poultry house, the thickness of the cooling pad should be adjusted. Namely, the hotter outside air is, the thicker cooling pad should be used. In turn, a bigger ventilation fan is required. In other words, the cooling pad thickness and fan size should be automatically changed depending on the changing of the hot weather. But the current cooling pad assisted cooling ventilation is not possible to change the thickness of its wall cooling pad. To eliminate such disadvantages, the more accurate and effective removal of NH3 than animal feeding diet control method currently in use is required and also the higher efficient air cooling apparatus is required to be installed inside of poultry houses.
The purpose of the present invention is a fabrication of ammonia-gas-removal-and-evaporative-air-cooling-apparatus (ARAC) being free of the disadvantages being exhibited in the cooling pad currently in use and preventing the thermal shock death of the animals as well as removing NH3 and H2S gases ventilating to environment from the live stock confined facilities and additional purpose is a fabrication of ventilation-fan-ammonia-gas-removal-apparatus (VFAR) being able to remove the NH3 and H2S gases only out of ventilating air. The VFAR can be installed on the walls of the livestock confined facilities to remove NH3 and H2S gases out of ventilating air and the ARAC installed inside of the livestock confined facilities to carry out both removal of gases and cooling of air in the facilities at the same time.
To remove NH3 generating from livestock production operation and to cool livestock confined facilities, the ventilation-fan-ammonia-removal-equipment (VFAR) and ammonia-gas-removal-and-evaporative-air-cooling-Apparatus (ARAC) of the present invention are invented and proved to be adequate for their application to the livestock confined facilities, since they have several advantages given as follows.
The key materials used for the VFAR and ARAC to remove NH3 and H2S (later on, NH3 is used for both meaning of NH3 and H2S) and to cool air are water and plastic rods or strings (later on, rod is used for both meaning of plastic spiral corrugated rod, non-spiral corrugated rod, and string). The water is normal ground water and the rods are polyester materials which are hardly stretched. The schematic pictures of the VFAR and ARAC are shown in
<Fabrication of VFAR and ARAC>
The VFAR of the present invention is fabricated by combining a commercial tunnel ventilation fan and the AWC of the present invention. Therefore, the cross section of the AWC is designed to fit with that of the commercial tunnel ventilation fan or axial motor fan blower used in the livestock facilities. The exact depth of the AWC and WVRD, however, are designed by counting on the air blowing rate of the axial motor fan blower. The dimension of the VFAR is in the range of 100(W)×100(H)×120(D) to 150(W)×150(H)×160(D) cm (other dimensions are possible) and the dimension of the AWC in the range of 100(W)×100(H)×75(D) to 140(W)×140(H)×100(D) cm (other dimensions are possible). While the VFAR is large as given above, the ARAC of the present invention is rather small because 32 of them are installed in a case of poultry house of 50(W)×500(L) ft (each fan has air flowing rate of 20 m3/min). The dimension of the DFARE is 75(W)×75(H)×105(D) cm, which has air flow rate of 20 to 50 m3/min (634 m3/min/32=20 m3/min/each). The fabrication of the ARAC employing the WVRD of the present invention with a dimension of 75(W)×75(H)×25(D) cm is accomplished by joining 2 of AWC of 75(W)×75(H)×25(D), and axial motor fan blower of 75(W)×75(H)×30(D) as shown in
<Fabrication of PRSF and PRSFs Pack for AWC and WVRD>
The AWC of the present invention is fabricated by assembling several PRSFs packs shown in
The PRSFs pack used for the ARAC are in same shape and dimension with those used for the fabrication of VFAR except for the intervals between the adjacent strings. The intervals between the adjacent rods of the PRSF are shorter and so the rods are packed closer than in the VFAR, since the air blowing rate in the ARAC is lower than in the VFAR and a larger specific surface area of the rods is necessary for an effective cooling air and absorbing water vapor. The intervals are reduces to 16.5 mm, 82.5% of those used in the VFAR, and the thickness of hole is reduced to 2.5 mm from 3 mm so that the interval between the centers of the adjacent rod is 33 mm. Then, the specific number, 200, of rods in the PRSFs pack used in the ARAC increases by 1.14 times as many as 157 rods in, the VFAR, resulting in increasing the specific surface area of the rods in the ARAC by the same rate, namely, the specific surface area of ARAC is 1 cm2/cm3, compared with 0.88 cm2/cm3 of VFAR, which are computed using dimension 25(W)×50(H)×25(D) cm of the standard PRSFs pack.
As shown in
<Fabrication of VFAR and ARAC>
The AWCs are installed in the VFAR as shown in
The
<Installation of VFAR and ARAC in Poultry House>
The VFARs of the present invention are installed on the wall of the livestock confined facilities as shown in
There are several factors for designing of the PRSF 15 and PRSFs pack 20 to be determined by conducting experiments and using out sources. However, since the physical characteristics for designing of the PRSF 15 and PRSFs pack 20 are similar with those of the SSP and SSPs pack, the design factors used for designing and fabrication of the SSP and SSPs pack are applied to designing and fabrication of the PRSF 15 and PRSFs pack 20 without any significant modification. Preparation of the design factors of SSP and SSPs pack are extensively described in U.S. patent application Ser. No. 13/053,382 recently applied by the inventor of the present invention. The factors for designing the PRSF 15 and PRSFs pack 20 are the number of rods 19 per unit cross section of the PRSFs pack 20, diameter of holes 18 on the perforated plate 21, 22 of the PRSFs pack 20, diameter of the rods 19, effective length of the rods 19 for effectively absorbing NH3 and cooling water, verification of flying away of water out of rod 19 due to the air blowing rate of fan, absorbing water vapor by cold water, and absorbing NH3 into water. The function of the PRSFs pack 20 to contact water with air on the surface of the rods 19 is briefly described here. The water is sprayed on the top perforated plate 21 of the PRSFs pack 20 which has uniformly distributed holes 18 on it and passing through the holes 19, and then flowing down on the surface of the rods 19 suspending between the top and bottom perforated plates 22 of the PRSFs pack 20. While the water is flowing down on the surface of rods 19, the water is absorbing NH3 gas or water vapor or cooling warm or hot air by contacting with the air entering the PRSFs pack 20 from its one side and passing through the PRSFs 355 pack 20 towards the opposite side. Such functions of the PRSFs pack 20 are verified in the present invention as described below.
<Absorption Mechanism of NH3 into Water>
The NH3 gas has high solubility in water, which is 400 to 800 g gas per kg water at the temperature of water 30 to 50° C., respectively, and is fast absorbed on the surface of water, see the solubility of NH3 in “The Engineering ToolBox, http://www.Engineering ToolBox.com.” Hence, a large amount of the NH3 gas can be absorbed into water at room temperature and the NH3 gas is rapidly dissolved into water when it is contacted with water, Therefore, the wider surface for the water to be contacted with NH3 gas is, the more amount of NH3 gas is absorbed. To meet such an absorption criteria of NH3 over the water, to continuously dissolve the NH3 into the water, and to remove the NH3 from the NH3 contaminated air stream, the NH3 contaminated air should perpendicularly pass through as many vertical rods 19 as possible, on the surface of which the water flows down by gravity. While passing transversely through the vertical rods 19, the NH3 contaminated air contacts with the water flowing down on the surface of the rods 19. Then, the water absorbs the NH3 gas from the air stream before discharging out of the AWC 2.
<Cooling Mechanism of Air by Water>
The air cooling of the PRSFs pack 20 is based on an evaporation and convection heat exchanging mechanism between air and water. The water to be used is the ground water, whose temperature is around 11-22° C. over the southern part of the Northern America, see the temperature of ground water in Northern America described in “Formisano B., Tankless Water Heater.” The evaporation of such water needs some energy or heat, which is absorbed from the air contacted on the surface of water. In turn, the air is cooled as much as heat lost. For instance, supposing the temperatures of the water and air are 18 and 28° C., respectively, the heat preserved in the air is transferred into the water, while the surface of the water of lower temperature is contacted with the air of higher temperature. Then, some of water molecules near the surface of water absorb the transferred heat until their temperatures rise up to that of the air and then they are evaporated after they absorb the transferred heat as much as latent heat of water. More precisely, the temperatures of the water surface molecules may rise up to a lower temperature (let's say 25° C.) than that of the air, due to heat resistance of the water surface and short contacting time of air and water (a short passing time of water through the PRSFs pack). Hence, specific heat of water per one gram to need for rising from 18° C. to 25° C. is 7 Cal/g and its latent heat for vaporization is 540 Cal/g. Namely, for the evaporation of one gram of water of 18° C., 547 Cal/g is necessary. Eventually, the air loses as much amount of heat as that of the gained heat of the water and in turn the air is cooled. In order to transfer more heat, the longer contacting time of air and water is needed. However, the PRSF 15 should be designed within a limited length. Therefore, the optimizing length of the PRSF 15 should be determined from its experiment. While the water passes through the PRSFs pack 20, some of the heated water molecules on the water surface evaporate into the air, but most of the heated water molecules pass out of the PRSFs pack 20. Consequently, most of heat transferred to water gets out of the ARAC 9 without evaporating, resulting in cooling the air within the poultry houses and warming water.
<Absorption of Water Vapor>
While the indoor air is cooled by evaporation heat exchanging of water in case of cooling the house using evaporative technology, the water vapor is generated and dispersed into the house and accumulated. Operating the ARAC 9 without removal of water vapor, the accumulated water vapor may be deposited on the floor and cause to generate NH3 gas. To prevent such unexpected cause of the water vapor, the WVRD 10 is equipped by attaching at the rear side of the AWC 2 in the ARAC 9. The function of the WVRD 10 is to contact the water vapor with the surface of cold water flowing down on the surface of the rods 19 to condense the water vapor into the cold water. While the air including the water vapor generated during passing through the AWC 2 is traveling through the WVRD 10, the air contacts with colder water. As a result of such an interaction, the temperature of the air is getting lower. Then, the water vapor in the air is condensed into water as much as amount of water vapor higher than saturated vapor density of water. For instance, assuming that the temperatures of the water vapor and cold water in the WVRD 10 are 30 and 20° C., respectively, and that they are saturated vapors at those temperatures, it can be understood that water vapor is reduced by 43% (0.43=(30.4−17.3)/30.4, saturated vapor densities of water at 30 and 20° C., are 30.4 and 17.3 g/m3, respectively).
<Conversion of Wet NH3 to Fertilizer>
Most of the NH3 dissolved in water remains as a unionized NH3 (free NH3) and the free NH3 is ready to volatilize back into atmosphere again. A natural zeolite ion exchanger 33, clinoptilolite, has a high chemical affinity of aqueous NH4+, read the property of the clinoptilolite described in “Denes Kallo.” To adsorb all of NH3 in water on the clinoptilolite and to prevent the release of the NH3 into the atmosphere, the circulating water maintains acid to convert free NH3 into NH4+. To make the water acidic, phosphoric acid is added to the water. Then, some of NH4+ formed in water is reacted with phosphoric acid to produce an ammonium hydrogen phosphate ((NH4)2HPO4), and also the ammonium hydrogen phosphate produced when the spent clinoptilolite is regenerated. This ammonium hydrogen phosphate can be used as fertilizer, see more information on production of fertilizer from regeneration of spent clinoptilolite in “Denes Kallo.” The NH3 dissolved in water should be removed out of the system and then converted to a stable state or destructed to other stable components, because most of the NH3 in water remains as free NH3 and is ready to volatilize into the atmosphere. The technologies to be used for such purposes are usages of natural zeolite ion exchanger column, ozone oxidizer, and EC-2556 biotechnology, which are currently used in industries for the same purposes. The ion exchanger column 33 converts such free NH3 to a stable state like ammonium hydrogen phosphate, the ozone oxidizer oxidizes the NH3 to ammonium nitrate (NH4NO3), see “the Engineering ToolBox,” and EC-2556 bacteria destructs the NH3 into nitrate or nitrite, see destruction of ammonia by bacteria in http://www.ecochem.com/t2556.html. The natural zeolite ion exchanger column 33 is more in detail described below, because it has a couple of advantages, compared with the other technologies. The ion exchanger column 33 uses natural zeolite clinoptilolite, which has several advantages such as a high chemical affinity for NH4+, high adsorption capacity of ions, low cost, simplicity of application and operation, compared to the other ion exchanger and conventional methods like biological treatment, oxidizer, etc, read more information on ammonia destruction technologies in “Anonis A. Zorpas, et al.”
<Determination of Optimum Number of Rods in VFAR and ARAC>
The wider surface of water to be contacted with NH3 gas is, the more amount of NH3 gas is absorbed, so that the more number of rods 19 should be used in the AWC 2 of the VFAR 1 and ARAC 9 to provide much larger contacting surface between air and water. But too many rods may cause the pressure drop of air flow passing through the rods because the open area for air to pass is reduced and because the small open area resists the passing of the air. Then, the flowing rate of air passing the PRSFs pack 20 is reduced. Eventually, the air is not cooled enough and the removal of NH3 is reduced by the reduction of the air flow rate. To avoid this problem, an optimum number of rods 19 should be used in the AWC 2 and WVRD 10. The optimum number of rods 19 means the maximum number of rods 19 per unit cross area not to reduce the air flowing rate as well as to maximize contacting surface of the rods 19, The optimum number of rods 19 used in the present invention is 7 rods per 25 cm2 for rods 19 of 1.0 cm in diameter by employing the data used in other field related with optimum number of rods 19.
<Operation of ARAC (Simultaneous NH3 Removal and Air Cooling System)>
The operating schematic diagram of the Simultaneous NH3 Removal and Air Cooling System (SAAS) is shown in
<Operation of VFAR>
The schematic picture of the operating of the ammonia gas removal system (AGRS) using the VFAR 1 is shown in
