Abstract:
A process for treating waste products discharged in a waste water from an animal operation, such as a swine confinement facility includes a holding tank for receiving waste water from the flushing of the facility in which solids to accumulate at the bottom thereof; wherein as conveyor transfers solids from said bottom at a rate preventing agitation of the waste water, to a compactor for removing additional water content and to a product dryer for converting the solids into a dry product. The product dryer includes a water heating system with water lines connected in a closed loop to the holding tank. The heating system thermal treats the circulating waste water and waste solids to a temperature sufficient to reduce undesired constituents therein. The product dryer is vented to a separator for recovering ammonia contents in the waste material.

Description:
RELATED APPLICATION 
     This application claims the benefit under 35 USC 121 of U.S. Provisional Application No. 60/267,394 filed on Feb. 9, 2001 in the name of David Ralph Newsome and entitled “Basic System For Separating And Sterilizing Animal Waste Including Human, For Incineration Of Combustible Material, For Drying, Curing And Roasting Of Crops And Steaming And Roasting Of Foods”. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to equipment and systems for thermal processing of waste material, crops and foods. 
     BACKGROUND OF INVENTION 
     For hundreds of years and more, hogs were allowed to roam freely in the woods or were penned in fenced pastures. This use of open space allowed the random placement of swine fecal waste and urine to be spread over a rather large area. There was not, usually, a heavy enough build up of waste in one area to cause anything other than a short term, often minor problem. The last few decades, however, have witnessed a radical change in the method of producing swine for market. The modern swine farm utilizes long confinement houses containing several hundred hogs at one time. 
     In a typical facility, the animals are grown on slotted concrete floors called “slats”. Therein, an upper floor is raised above a concrete subfloor that receives the waste from the animals through the slots in the upper floor. The lower floor accumulates the swine fecal and urinary waste until such time as the waste is flushed by wastewater from a flushing tank. The flushing cycle can vary from a few hours to as much as a week depending upon the type of flushing system. 
     Other swine facilities use a solid, sloped floor having a gutter along the outside wall. With such a system, the pigs have direct access to the gutter and the flush water. The flush water in both of the above facilities is pumped from the top of a waste holding lagoon. When the pigs confined in a gutter type facility hear the flush water being released, they will run into the gutter, often lie in it and proceed to drink the flush water and eat the fecal matter in it. So many pigs will stand or lie in the gutter that it interferes with the adequate cleaning of the gutter. 
     The houses are flushed by several hundred gallons of water released from the flush holding tanks supplied from the lagoon. The flushed waste water is recycled, without treatment, to the waste holding lagoon. 
     The flush holding tanks located at the end of the houses opposite the lagoon are refilled from the top area of the lagoon to be ready for the next flush cycle. The lagoon is a man-made pond for collecting and storing the waste from the confinement houses and from which, after partial settling of the solids, wastewater is obtained for the next flushing cycle. Resultantly, modern swine production and the attendant holding lagoons generate substantial odors and present dangers of ground, ground water, and stream pollution. Other adverse results include lowered property values for adjacent properties and ground water depletion. 
     To get rid of excess water from the lagoon, the producer must pump the wastewater onto fields that have enough area to absorb and retain the effluent. This is especially critical during periods of heavy rainfall, such as that associated with a tropical storm or hurricane. Accordingly, the farmer must purchase and maintain an expensive irrigation system, fence and maintain a pasture, buy or build a small herd of cattle, purchase hay rakes, balers, and mowers just to service the lagoon. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention provides a closed loop thermal processing system that eliminates, in swine production, the need for a holding lagoon. The waste water and solids resulting from the flushing system are transferred to a holding tank for settling of the solids. A porous belt conveyor system transfers the solids from the holding tank while allowing solids drainage during transfer. At the end of the conveyor system, the partially drained solids are fed through a compaction roller assembly for additional drainage. They are pulverized and fed into a collection hopper from which they move into a shaker bed dryer unit maintained at an elevated temperature. The shaker bed progressively transfers and mixes the solids to promote thermal drying of the solids at a temperature eliminating bacterial and pathogenic contents. The resulting dry product is suitable for animal food supplement and fertilizer applications. The heating system for the dryer uses wastewater from the holding tank and raises the temperature to a sterilizing level also sufficient to remove harmful constituents. The heated water is fed to a separator for extraction of ammonia constituents, drained from the separator, cooled, filtered and recycled to a flush storage holding tank. The flushing system is thus fed from a thermal processed reservoir, from which solids and harmful constituents have been removed, resulting in an elimination of the adverse consequence of the lagoon and substantially better water quality for the flushing value. In addition, the recovered dry product and ammonia provide economic return to the facility operator. 
     The present invention in various configurations and attachments available can be employed as a swine, cattle and poultry waste processor, a human waste incinerator/processor, and in hospitals and veterinary hospitals as an incinerating system for human and animal body parts and medical refuse that otherwise is generally destroyed by incineration. The system can be adapted to process bones and meat scraps in a meat packing plant and to process the shells and scraps in a seafood plant. Whole fish and animals can be processed. Crops such as flue cured tobacco can be taken from the curing barn and run directly through the system to humidify and soften the leaves so that they can be sheeted or baled for market. In addition, the system can be used as a stationary or mobile dryer for grain, corn, and oil seed, as well as a roaster for sweet corn and oysters and a steamer for seafood. 
     Moreover, the system can be used as a stationary processor by small municipalities and satellite subdivisions as a disposal for human waste. Mobile units can be employed by the military. Relief organizations can preposition systems near earthquake, tornado, hurricane or other disaster prone areas for servicing showers, latrines, laundry, and food preparation to alleviate the stress and danger of disease associated with natural disasters. 
     Accordingly, it is an object of the present invention to provide a closed loop thermal processing system for animal wastes that eliminates waste holding lagoons. 
     Another object of the invention is to provide a drying system for animal waste that yields recoverable economic materials. 
     A further object is to provide a waste processing system that thermally eliminates the solids content of animal waste and improves the water quality to enable recycling. 
     Yet another object is to provide an agricultural dryer that can be used for processing a plurality of waste products, crops, and foods. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The above and other features and advantages of the present invention will become apparent upon reading the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a side elevational view of a processing system in accordance with a preferred embodiment of the invention; 
         FIG. 2  is a schematic drawing of an open loop processing system in accordance with the invention; 
         FIG. 3A  is an end view of the dryer of the processing system with the product doors in the closed position; 
         FIG. 3B  is an end view of the dryer of the processing system with the product doors in the open position; 
         FIG. 4  is a horizontal sectional view showing the lower water heating tubes for the dryer mounted upon the top of the lower heat exchanger; 
         FIG. 5  is a fragmentary view showing the conveyor and processing head for removing solids material from the holding tank; 
         FIG. 6  is a side elevational view of the conveyor system for routing solids material from the holding tank to the shaker tray assembly of the dryer; 
         FIG. 7  is a side elevational view of the holding tank and the conveyor system; 
         FIG. 8  is a side view of the shaker tray assembly; 
         FIG. 9  is a side cross sectional view of the ammonia separator for the processing system; 
         FIG. 10  is a side view of the loading conveyor for transferring tobacco leaves to the dryer; and 
         FIG. 11  is a side view of the loading conveyor for transferring crops to the dryer. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to the drawings for the purpose of describing the preferred embodiment and not for limiting same,  FIG. 2  shows a swine confinement facility  10  having a conventional flushing system for directing water from a flushing tank  12  through the facility to remove waste accumulations therefrom for deposit in a holding tank  14 . The wastewater in the holding tank  14  comprises liquid and solids in partial suspension. In the holding tank  14 , the solids accumulate gradually at the base thereof, with fine particulate solids remaining in suspension. 
     A conveyor system  20 , as described below, transports the solids to a product dryer  22 . Liquids removed from the solids on the conveyor system  20  are returned by to the holding tank  14 . In the dryer,  22 , the solids are dried and discharged as recycled product  24 . The interior of the dryer  22  is heated to a controlled temperature by heating system  26 , which also heats wastewater from the holding tank  14  as described below. The dryer  22  heats the air in the interior to dry the solids material and is vented by line  28  to an ammonia separator  30 . The gaseous products, including recovered ammonia, is passed through a condenser  32 , liquefied and routed to a storage tank  34 . Water fed to the separator from the dryer along line  147  is returned by line  36  to the holding tank  14 . 
     Referring to  FIGS. 5 and 7 , the holding tank  14  comprises a covered enclosure  40  having spaced vertical end walls  42  and spaced side walls  44  having a vertical upper section  46  and an inwardly inclined lower section  48  establishing a narrow rectangular base  50  on which the solids material  51  settle and accumulate. 
     The conveyor system  20  includes a horizontal conveyor  52  positioned longitudinally along the base  50  of the holding tank  14  that routes solids material to an inclined vertical conveyor  54  attached exteriorally to a side wall  42  of the holding tank  14 , and extending through and enclosed by housing  55 . The conveyor  54  extends vertically and outwardly from the holding tank. The conveyors  52  and  54  each have a perforated or porous belt for removing and carrying the settled solids from the bottom of holding tank  14 . The porosity of the belts permit the drainage of liquid from the solids without particulate transfer therethrough. The conveyor belts may be provided with transverse flights  56  to assist in the transport of material. The conveyors operate at a low belt speed of  ½ ft/min. to  1½ ft/min variable. The slow belt speed prevents agitating the solids in the wastewater as solids settle on the belt, thereby minimizing the generation of fine particulate suspension, which is difficult to settle in normal holding tanks. Further, the fine particulates are effectively filtered by the solids during travel on the conveyors, additionally reducing fine particulate buildup. 
     The bottom side sections  48  of the holding tank  14  are sloped at least about 60° to ensure that solid matter does not adhere to the sidewalls, thereby overcoming any problems attendant to solids build up. The vertical conveyor  54  is also inclined at a similar angle of about 60°. As the conveyor belt of conveyor  54  rises out of the holding tank  14 , the water content is drained from the solids through the conveyor belt perforations, and directed back to the holding tank  14  by the walls of a chute  60  enclosing the conveyor  54 . A compactor assembly  62  is located at the upper end of the chute  60 . The solids carried on the vertical conveyor  54  are discharged to a roller system  70 , operated by motor driven belt  72 , for compacting the solids to thereby remove additional water content therefrom. The solids are initially fed from the conveyor  54  to entry rollers  74 . The initially compacted solids are removed from the lower roller by scrapers  76  and fed through a rotating separator flail  78  to secondary rollers  80 . The further compacted and drained solids are discharged and removed from the secondary rollers  80  by scrapers  82  for gravity discharge through discharge outlet  84  and through discharge chute  86  into a feed tank for dryer and then moved by conventional conveyor into intake hopper  88  of a product dryer  22 . A secondary rotating flail  8 , 9  driven by belt  91  and motor  120 , is operatively positioned in the discharge chute  86  and serves to pulverize any clumps in the solids resulting from the rolling operations. 
     The dryer  22  comprises an insulated housing  90  defined by rectangular sidewalls  92  and end wall  94 , a top wall  96  and a base wall  98 . The hopper  88  is located at an upper lateral end thereof. Referring to  FIGS. 6 and 8 , a dryer rack assembly  100  is carried in the interior of the housing  90  above a serpentine heating coil  146  ( FIG. 4 ) carried in the base thereof. The dryer rack assembly  100  includes a frame  110  connected to the sides of the housing and connected to an oscillating shaker bed  112  by pivotal links  114 . The shaker bed  112  includes a plurality of alternating, downwardly inclined reciprocating trays  114 ,  116 ,  118  carried by shaker frame  119 . As shown in  FIG. 1 , an electric motor  120  and speed variator  122  drive crank wheel  122  to actuate linkage  124  and oscillate through shaft  126 , which is connected to the lower end of lever arm  128 . The lever arm  128  is pivotally connected at an upper end to the shaker frame  119 . Accordingly, in operation, the shaker frame  119  is reciprocated about pivotal links  114 . The solids, under reciprocation of the trays, progressively move, as shown by the arrows, down the slope of the top tray  114  and are deposited upon the upper end of the second tray  116 . The process is repeated through lower tray  118  at which location the solids are substantially dried with the remaining dried product no longer possessing fecal properties and becoming an organic material suitable for fertilizer or animal feed base. The dried, sterilized product can then be moved from the dryer through discharge auger for use or storage by conventional handling equipment. 
     The heating system  26  includes a heat source  140  including a heat exchanger that routes waste water along inlet line  142  from holding tank  14 . A low volume pump  144  in line  142  fluidly connects the inlet of the serpentine heating pipe array  146  in the base of the dryer  22  and the holding tank  14  along return line  142 . A branch line  147  is routed to the separator  30  as described below. The heating system heats the conveyed wastewater to elevated temperatures sufficient to kill any germs, bacteria, worm eggs, larva or other pathogens. The three heat exchangers  102  serve to heat the interior of the dryer to elevated temperatures sufficient for drying the solids at temperatures necessary to dry and sterilize the product in the shaker trays. The resultant steam is vented to the separator  30  along exhaust line  28 . 
     As shown in  FIG. 9 , the line  147  is routed through a rear wall of the dryer and directed to the ammonia separator  30 . The separator  30  includes a cylindrical center housing  150 , an upper frustoconical dome  152  and a lower frustoconical base  154 . The separator  30  is positioned adjacent the dryer and supported on legs  156 . The line  147  enters at the top of the housing  150  and terminates with a downwardly directed 360° scrubbing nozzle  158  positioned at the housing axis. The exhaust line  28  is connected at one end to the dryer and routes process steam therefrom into the center of the separator housing  150  through an upwardly directed outlet  160  positioned below the nozzle  158 . A downwardly opening conical diffuser  160  is carried on the steam outlet  160  intermediate the outlet and the nozzle  158  and serves to radially distribute the wastewater and steam for extraction of ammonia constituents from the admixture. Condensed wastewater, stripped essentially of ammonia constituents, is routed through drainpipe  162  in the base  154  for return to the holding tank  14  along the return line  36 . The process steam with the ammonia content is withdrawn from the dome  152  at outlet pipe  164 , passed through condenser  32  and routed to a collection tank  34  for removal for ancillary purposes. This “gray ammonia” can be used by a solvents recovery company as raw material for pure ammonia and other products of commercial value. 
     The discharge water from the drain pipe is pumped through filter  174  to the holding tank  14  along line  36 . From the holding tank  14 , the processed waste water is passed through an optional secondary commercial sand filter  172  and back to the flush holding tank  12  ready for the next flushing cycle. 
     After a period of time, the continual recycling of the wastewater will result in a build-up of minerals that will require replacement with fresh water. 
     Accordingly, mineralized water may be transferred to a suitable auxiliary tank on the farm for future use such as direct application to farm crops using existing fertilizer distribution systems, thereby supplementing expensive commercial fertilizers. 
     The heat system for the dryer may be natural or LP gas, kerosene or fuel oil, or any fuel source providing a steady, reliable, safe, and usable temperature to allow the system to function correctly. Regardless of source, heated air from the heat source enters a lower heat exchanger and passes to a front heat exchanger. From the front heat exchanger the flow moves by pipe into the matching rear heat exchanger and from there it moves into the rear end of the top heat exchanger and is exhausted out of the other end. 
     It will be appreciated that the above-described closed-loop processing system eliminates the need for a holding lagoon and the problems and dangers associated therewith. Further, based on testing, the dried-sterilized product yields a feed value of about 65–75% of new feed; and a fertilizer value of 8-4-8, which is of commercial value and is organic. Moreover, the system is environmentally beneficial and cost effective, eliminating the costly expense of building and maintaining swine lagoons, as well as the need for expensive high volume pumps and pumping units, irrigation systems, and fuel. Furthermore, the use and/or sale of the resultant products not only defrays the cost for the system and its operation and maintenance, but actually provides a net profit for the farmer. 
     The system may also be adapted for processing poultry litter. A poultry system will not generally require a holding tank with the belt conveyor, beater and water system. Therein, the poultry litter removed from the poultry houses will be delivered to the dryer hopper, after being processed by a hammermill. The litter will be processed through the shaker trays for discharge in the manner described above. Misting nozzles may be located as needed to control the dust from the processing operations. 
     The system may also be used for processing cattle waste, either as a “dry” system like the poultry litter processor or a “wet” system like the swine waste processor. For a wet system, a conventional hammer mill may be substituted for the mechanical flail and the roller system at the dryer intake hopper. Such mechanical disruption will grind or pulverize any hay, straw, corn cobs or husks that may have been wasted by the cattle or have been used as bedding. The dryer and downstream subsystem would remain the same. 
     For the processing of human waste, a much higher temperature will be maintained in the dryer to incinerate the solids, thus leaving only a small amount of ash for disposal. The water from the system can be collected and disposed in the same manner as the conventional systems. The difference will be that the solids will have been removed and the water will have been boiled. These processors can be stationary or mobile. 
     The dryer can be stationary or mobile. If mobile, the fuel tank and a small gas or diesel generator will be located on the system. The combine operator would unload the combine grain tank into the hopper above the dryer. The crop may be metered to the trays to provide a feed rate that will ensure proper drying prior to discharge. 
     As a roaster for oilseed such soybean, peanut, sunflower, cottonseed, and the like, the temperature and dryer dwell time can be adjusted to produce the desired product. The roasted product would then be processed for oil and meal as is conventionally being done now. 
     Farmers lose a lot of money each year at harvest time. There are times when a crop such as corn, soybeans, or grain could be harvested but deferred because excessive product moisture seriously lowers the selling price. Conventionally, the farmer waits for nature to dry the crop. Often, however, nature does not cooperate. Instead of sunny days there can be an extended period of rain or snow, even a flood, and the farmer could lose everything. The present drying system enables the farmer to harvest and dry crops ahead of inclement weather thereby avoiding moisture dockage costs. 
     A system for human and veterinary hospitals would include the basic processor components, with or without pulverizing, depending upon the nature of the waste being processed. An incinerating unit would maintain a temperature required to destroy hospital waste. The units will not require the pipe array that is necessary in a “wet” system such as a swine processor. Resulting ash from these systems can be disposed of by conventional methods such as in a landfill. 
     The old style type of flue cured tobacco curing and drying barns are a thing of the past, and have been replaced by “bulk” barns. The bulk barn is much simpler, faster, and easier to fill and empty than the older “stick” barn. These newer barns will hold around three times as much tobacco as the obsolete barns they replaced. 
     Even though the new barn is vastly superior to the old, they share a common problem. When the tobacco curing/drying process is completed, the tobacco leaves crumble into pieces if some form of moisture is not introduced to soften the leaves. This is necessary to enable the tobacco leaves to be removed and sheeted or baled for sale. With the old stick barn, this was accomplished by opening the doors and vents and letting the night air soften the leaves. If this was not sufficient to do the job due to dry night air, coolness, or wind, the farmer would be forced to haul water and pour it onto the floor of the barn. 
     The bulk barn cannot be handled this way because of its construction and the tobacco being packed in such a manner as to not allow the circulation of air through the leaves. The bulk barn is humidified by connecting a water hose to a water supply. The barn has a controlled system for distributing the water and moistening the tobacco. The primary problem with this system is that it can take from 24 to 36 hours for this process to be completed. This is time that can be critical for a farmer especially during times of heavy harvest or approaching tropical storms, hurricanes, or frost. 
     The present drying system will reduce this time consuming process to only a few hours, perhaps to no more than is usually required to ready the leaves for market, usually around 3 hours. 
     A flue cured tobacco humidifying system uses the above described dryer. As shown in  FIG. 10 , instead of the agitator or beater within the feed hopper arrangement located above the dryer inlet as used in the swine unit, the tobacco moves by a very slow moving covered conveyor  200  of conventional design for delivery through discharge chute  202  directly into the top of the dryer as delivered from the bulk barn  204  by hopper  206 . Instead of utilizing several shaker tray levels, the dryer unit requires only the top most level. Above the standard top level tray, a perforated sheet or screen is provided that allows more air circulation around and through the leaves than if they were only allowed to move along the floor of the upper level rack. Any sand or fine foreign matter will be removed by the action of the tobacco across the perforated top or screen. This sand and fine foreign matter will continue on through the levels of the oven and be discharged via the standard dryer discharge auger. With the dryer outfitted for tobacco, the leaves will leave the dryer by conveyor through the door located on the upper rear of the dryer. This “shelf-type item” conveyor will move the now moistened and softened tobacco to the sheeting or baling area. 
     Moisture is supplied within the dryer by fresh water being sprayed or dripped, by control, upon the top of the bottom heat exchanger located within the dryer. Upon completion of the tobacco process, the “tobacco mode” components can be removed in minutes and the dryer returned to processing fecal waste or drying grain etc. In other words, the farmer can use the basic drying system on several crops by the use of the various quick change components designed for the dryer and different crops. 
     For food crops, the standard dryer is constructed of FDA required construction materials. The only other basic change is that the product is discharged upon a stainless mesh belt conveyor arrangement for exit from the dryer instead of the usual discharge auger. Such product may be loaded into the dryer, as shown in  FIG. 10 , by a conveyor  200  accessing the dryer interior via intake hopper  86  without beater  89 . 
     Having thus described a presently preferred embodiment of the present invention, it will now be appreciated that the objects of the invention have been fully achieved, and it will be understood by those skilled in the art that many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the sprit and scope of the present invention. The disclosures and description herein are intended to be illustrative and are not in any sense limiting of the invention, which is defined solely in accordance with the following claims.