Solid/liquid mixing system

Information

  • Patent Grant
  • 6536939
  • Patent Number
    6,536,939
  • Date Filed
    Friday, September 15, 2000
    24 years ago
  • Date Issued
    Tuesday, March 25, 2003
    21 years ago
Abstract
A mixing system with a vessel for supplying a liquid and a device for supplying solid pieces to mix with the liquid. The system has an elongate enclosure with a first end opposing a second end. The enclosure defines a chamber in fluid communication with the vessel to receive the liquid. The chamber also has a inlet and an outlet with the inlet being closer to the first end than the outlet. The chamber receives the pieces from the device through the inlet and issues the pieces through the outlet. A motor driven mixing auger positioned in the chamber between the first and second ends rotates a selected direction about a rotational axis to intermix the liquid and pieces. The auger includes a first helical flight between the inlet and the outlet to convey the pieces from the inlet to the outlet when the shaft is rotated the selected direction. The auger also includes a second helical flight between the first flight and the second end to urge the solid pieces in a direction opposite the first flight. The second flight has a length along the rotational axis of the auger shorter than the first flight. In one variation of this system, the liquid may be a colorant and the solid pieces may include wood chips to be intermixed with the liquid to attain a uniform visual appearance.
Description




BACKGROUND OF THE INVENTION




The present invention relates to mixing solid pieces with a liquid, and more particularly, but not exclusively, relates to coating and coloration of landscaping materials.




The problem of landfill crowding has grown steadily. One way to reduce this crowding is to recycle as many materials as possible. One type of material suitable for recycling is wood. Wood may arrive at the landfill from a natural source, such as discarded tree branches, or it may be derived from various discarded products, such as shipping crates and furniture.




One way to recycle wood is to reduce the wood to a number of pieces of generally uniform size with a shredder, chipper, or grinder. Such comminuted wood is often suitable for use as a landscaping mulch. However, the varied types of wood typically obtained from a landfill often result in a non-uniform coloration that significantly changes with age and exposure to the elements. To alleviate this problem, recycled wood pieces are sometimes treated with a colorant to provided a more pleasing appearance. U.S. Pat. No. 5,308,653 to Rondy describes one coloring process.




One problem often encountered with coloring processes is excessive run-off of liquid colorants used to impart a uniform appearance to the wood pieces. This run-off adversely impacts cost effectiveness. To address this problem, there is a need to optimize the coloration process by determining the minimum amount of liquid colorant needed for a given amount of wood. There also remains a need to provide a more cost effective way to uniformly color landscaping material.




Another problem with the coloration process is that mixers used to blend liquid colorant and wood pieces are subject to frequent jamming. Typically, the mixer becomes packed with a mass of wood chips that are stuck together. This mass of chips often prevents discharge of the treated product from the mixer. Equipment down time to unclog the mixer generally increases processing costs and may result in excessive colorant run-off. Thus, there is also a need for a mixing system which resists packing and still economically imparts a uniform color to landscaping materials.




SUMMARY OF THE INVENTION




One form of the present invention is a system with a mixer defining a chamber that has an opening for inserting solid pieces therein. The chamber is in fluid communication with a conduit. Furthermore, the system has a source of a liquid agent and a metering device to selectively provide the agent from the source to the conduit. A water supply is coupled to the conduit to dilute the agent prior to reaching the pieces in the chamber. A controller is operatively coupled to the metering device to provide a delivery signal. The metering device responds to the delivery signal to adjust delivery of the agent to the conduit from a first non-zero rate to a second non-zero rate.




In an alternative form of the present invention, water and a colorant are mixed to produce a colorant liquid mixture during the movement of wood chips within a mixing chamber. Colorant supply to the liquid mixture is metered to control colorant amount or concentration in the mixture. The liquid mixture is put into the chamber to color at least a portion of the chips. The chips are discharged from the chamber. In one variation of this feature, landscaping gravel or rocks may be colored with the mixing process. In another variation, the mixture imparts a clear coating to rocks or another landscaping material to provide a high gloss appearance.




Among other alternative forms of the present invention are a mixing system with a vessel for supplying a liquid and a device for supplying solid pieces to mix with the liquid. The system has an elongated enclosure with a first end opposing a second end. The enclosure defines a chamber in fluid communication with the vessel to receive the liquid. The chamber also has an inlet and an outlet with the inlet being closer to the first end than the outlet. The chamber receives the pieces from the device through the inlet and discharges the pieces through the outlet. A motor driven mixing auger positioned in the chamber between the first and second ends rotates about a rotational axis to intermix the liquid and pieces. The auger includes a first helical flight between the inlet and the outlet to convey the pieces from the inlet to the outlet when the auger is rotated. The auger also includes a second helical flight between the first flight and the second end. The second flight has a length along the rotational axis shorter than the first flight. The second flight may have a rotational direction opposite the first flight and be positioned at least partially over the outlet to reduce clogging. In one variation of this system, the liquid may be a colorant and the solid pieces may include wood chips to be intermixed with the liquid to attain a generally uniform color.




In yet another alternative form, the first and second flights are mounted about an elongated shaft configured to rotate about the rotational axis and a portion of the first flight does not contact the shaft while turning about the rotational axis for at least three revolutions, defining a space therebetween. This structure enhances intermixing of the wood pieces with the liquid.




In still another alternative form, a mixing technique includes moving a number of wood chips through a generally horizontal, elongated passage of a mixer from a top inlet adjacent a first end of the mixer to a bottom outlet adjacent a second end of the mixer. This movement is performed by turning a pair of augers disposed within the passage. The inlet and outlet are spaced apart from one another along a longitudinal axis of the mixer. A liquid colorant and water are mixed to provide a liquid coloring mixture during movement of the wood chips. This mixing is regulated with a controller. The mixture is provided to a spray hood to impart color to the wood chips while moving. The spray hood defines a chamber projecting above the passage and having a plurality of nozzles that deliver the mixture to the chamber under pressure. The chamber intersects the passage to define an area for contacting the wood chips with the mixture. This area is positioned generally opposite the nozzles to extend along the longitudinal axis of the mixture at least about two-thirds of a distance between the inlet and the outlet. Further, this area transversely spans across at least about three-fourths of a top width of the passage occupiable by the wood chips. The wood chips are discharged through the outlet. It has been found that this arrangement facilitates reduction of the amount of water needed to adequately color the wood chips.




In a further alternative form, a mixing technique includes moving a number of wood chips within a mixing chamber and blending water and a colorant in a static mixer while the wood chips are moving to produce a generally homogenous liquid colorant mixture for supply to the chamber. The mixer includes a cavity containing one or more internal baffles oriented to mix the water and colorant. The colorant is metered to the mixture with a variable rate pump responsive to a controller while maintaining a generally constant flow rate of the water to the mixture with a flow rate regulator. A coloring property of the wood chips is determined and concentration of the colorant in the mixture is adjusted from a first non-zero amount to a second non-zero amount in accordance with the coloring property. This adjustment includes changing delivery rate of the colorant to the mixture with the controller. At least a portion of the wood chips are colored in the chamber with the mixture. The wood chips are then discharged from the chamber.




Accordingly, it is one object of the present invention to provide a system that dispenses a liquid to a mixer for blending with solid pieces therein.




It is another object of the present invention to optimize the mixing of a concentrated liquid agent with water to create a liquid mixture for supply to the chamber of a mixer for blending with solid pieces. The agent may include a colorant or clear coat material and the solid pieces may comprise landscaping material such as wood chips or rocks.




It is still another object to color wood chips to provide a mulch. Preferably, the coloration technique reduces the amount of water needed to apply a water-based colorant mixture to the chips and the amount of colorant mixture run-off.




An additional object of the present invention is to provide a mixer which resists packing of solid pieces being blended with a liquid therein.




Further objects, features, aspects, benefits, and advantages of the present invention shall be apparent from the detailed drawings and descriptions provided herein.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a schematic top view of a colorant mixing system of one preferred embodiment of the present invention.





FIG. 2

is a diagrammatic view of the colorant dispensing system of the embodiment of FIG.


1


.





FIG. 3

is a partial cut-away side view of the mixer of the embodiment of FIG.


1


.





FIG. 4

is a side sectional view of the mixer shown in FIG.


3


.





FIG. 5

is a top sectional view of the mixer shown in FIG.


3


.





FIG. 6

is a partial, cut-away side view of a mixing system of another embodiment of the present invention.





FIG. 7

is a partial sectional view of the mixer taken along section line


7





7


of FIG.


6


.





FIG. 8

is a partial, top view of the manifold shown in

FIGS. 6 and 7

.











DESCRIPTION OF THE PREFERRED EMBODIMENTS




For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the described embodiments, and any further applications of the principles of the invention as described herein are contemplated as would normally occur to one skilled in the art to which the invention relates.





FIG. 1

depicts a colorant mixing system


10


of the present invention. In system


10


, a number of wood chips


12


are transported by conveyer


14


in a direction along arrow I to mixer


60


. The chips


12


enter chamber


70


of mixer


60


through inlet


72


and are processed therein. This processing includes mixing with a water-based colorant from dispensing system


20


. Processed wood chips


16


exit through outlet


74


of mixer


60


and are carried away by conveyer


18


in a direction along arrow O.




Dispensing system


20


combines concentrated colorant from source


22


with water from water supply


24


to provide a liquid mixture for delivery to chamber


70


via conduit


26


. Preferably, source


22


includes a vessel holding an ample supply of the concentrated colorant. Source


22


may include a plurality of vessels or a colorant dispensing sub-system. Water supply


24


is preferably a well water source or city water source of a conventional type.




Dispensing system


20


includes control panel


30


with a display


32


indicating the rate colorant is being delivered for mixing. This rate may be continuously adjusted by an operator with rotary control


34


. Control panel


30


also includes a control key pad


33


, a master start switch


36


, and a master stop switch


37


. Switches


36


,


37


start and stop delivery system


20


, respectively. In addition, control panel


30


has switch


38


corresponding to water supply


24


and switch


39


corresponding to colorant source


22


. Each switch


38


,


39


has three positions: on, off, and automatic (or “auto”). When each switch


38


,


39


is in the auto position, delivery system


20


operates normally. The on/off positions are used to separately start and stop water or colorant, respectively, for calibration purposes.




Delivery system


20


is also operatively coupled to sensor


35


. Sensor


35


provides a stop signal corresponding to the absence of material on conveyer


14


. This stop signal is then used to halt delivery system


20


. Sensor


35


may be a microswitch with an actuation arm positioned above conveyer


14


a selected distance. This arm is configured to either open or close the microswitch when material on conveyor


14


of a selected height no longer contacts it. Opening or closing of this microswitch sends the corresponding stop signal. Other types of sensors as would occur to one skilled in the art are also contemplated.




Referring additionally to

FIG. 2

, further details of delivery system


20


are described. Controller


31


is operatively coupled to display


32


, key pad


33


, rotary control


34


, sensor


35


and switches


36


,


37


,


38


, and


39


to coordinate and supervise operation of delivery system


20


. Controller


31


may be an electronic circuit comprised of one or more components. Similarly, controller


31


may be comprised of digital circuitry, analog circuitry, or both. Also, controller


31


may be programmable, an integrated state machine, or a hybrid combination thereof. However, preferably controller


31


is microprocessor with a known construction and has a control program loaded in non-volatile memory. In one embodiment a microcontroller/keyboard combination is supplied as Durant Model No. 5881-5 with part no. 5881-5-400 by Eaton Corporation of Waterloo, Wis., 53094.




Controller


31


is also coupled to pump system


40


. Pump system


40


includes positive cavity control pump


41


coupled to source


22


and driven by motor


42


. Controller


31


provides a delivery signal to motor


41


corresponding to a selected rate of delivery of concentrated colorant input to controller


31


with rotary control


34


. In one embodiment, controller


31


responds to a stop signal from sensor


35


to generate a delivery signal which shuts down pump system


40


. This delivery signal may alternatively be characterized as a “shut down” signal.




The colorant output by pump


41


encounters valves,


26




a


,


26




b


. Under usual operating conditions, valve


26




a


is open and valve


26




b


is closed so that colorant flows through check valve


43


. Check valve


43


generally maintains “one way” flow of colorant away from pump


41


. Colorant from check valve


43


empties into joining conduit


48


. During calibration of pump system


40


, valve


26




a


is closed, and valve


26




b


is open so that colorant flows through calibration outlet


27


for collection and possible reuse. Besides pump system


40


, other metering devices as would occur to one skilled in the art are also contemplated.




Controller


31


is also operatively coupled to on/off valve


44


having inlet


44




a


in fluid communication with water supply


24


, and outlet


44




b


for supplying water therefrom. Valve


44


is responsive to a signal from controller


31


to correspondingly start or stop water flow from supply


24


. In one embodiment, controller


31


responds to a stop signal from sensor


35


to shut down water supply


24


by closing valve


44


via a shut down signal. Valve


44


may be a conventional solenoid activated stop valve.




Outlet


44




b


of valve


44


is in fluid communication with inlet


46




a


of flow regulator


46


. Flow regulator


46


has outlet


46




b


in fluid communication with check valve


47


. Check valve


47


maintains water flow away from flow regulator


46


to joining conduit


48


. Flow regulator


46


maintains a generally constant flow rate of water despite varying pressures at inlet


46




a


and/or outlet


46




b


. Accordingly, flow regulator


46


adjusts to maintain a generally constant pressure differential between inlet


46




a


and outlet


46




b


. Flow regulator


46


has an adjustable orifice to correspondingly select the regulated rate of flow from a given range of flow rates. In one embodiment, model no. JB11T-BDM from W.A. Kates, Co., 1450 Jarvis Avenue, Ferndale, Mich. 48220 is used for flow regulator


46


to provide a desired water flow rate selected from between 3 and 80 gallons per minute. In other embodiments, a different flow regulator may be used or a flow regulator may not be used at all.




Although water and concentrated colorant may begin mixing in joining conduit


48


, static in-line liquid mixer


50


provides a substantially homogenous liquid mixture of concentrated colorant diluted by water which is not generally provided by a conduit of generally constant internal cross-section. Concentrated colorant and water enter static liquid mixer


50


through inlet


50




a


and exit through outlet


50




b


. Static liquid mixer


50


is preferably made from a transparent PVC material so that blending cavity


51


therein may be observed. Within blending cavity


51


are a number of interconnected internal baffles


52


. Baffles


52


are arranged to split the stream of liquid entering through inlet


50




a


and force it to opposite outside walls of mixer


50


. A vortex is created axial to the center line of mixer


50


by the arrangement of baffles


52


. The vortex is sheared and the process re-occurs but with opposite rotation several times along the length of static liquid mixer


50


. This clockwise/counterclockwise motion mixes the liquid to provide a substantially homogenous mixture through outlet


50




b


and into conduit


26


. Notably, static liquid mixer


50


operates without moving internal parts other than the liquid being mixed. This homogenous premixed liquid enhances uniform coloring of wood chips. Cole-Parmer Instrument Company of Niles, Ill. 60714 provides a PVC static liquid mixer model no. H-04669-59 which is preferred for one embodiment of the present invention.




In other embodiments, a static mixing cavity arranged to promote mixing without internal baffles may be used. U.S. Pat. No. 4,516,524 to McClellan et al. is cited as a source of additional information concerning a dedicated static mixing cavity of this type. In still other embodiments, premixing of colorant and water prior to entry into chamber


70


is not necessary.




By controlling the rate of delivery of colorant with control


34


to static liquid mixer


50


and maintaining a generally constant flow rate of water with flow regulator


46


, a desired concentration of water based colorant mixture may be selected. This concentration, and the rate of flow of the mixture to chamber


70


of mixer


60


may be matched to the rate of transport of wood chips therethrough to optimize colorant system


10


performance. As a result, the minimum amount of water necessary to provide uniform coloration for the wood chips may be determined by taking into account the absorbency of the liquid by the wood chips


12


, the rate of flow of the liquid into chamber


70


, and the rate of passage of wood chips


12


through mixer


60


. Notably, the rate of liquid flow can be adjusted with flow regulator


46


and with rotary control


34


, and the ratio of water to colorant can likewise be adjusted to assure a concentration which will provide uniform coloration. By optimizing these amounts, the amount of liquid runoff can be minimized and this optimal performance can be reliably reproduced. Also, an adjustable flow rate and colorant delivery rate permits re-optimization of the process when various parameters change; including, but not limited to, a different colorant type, different wood chip delivery rate, or different type of wood chips.




Besides optimizing colorant mixture delivery to mixer


60


, in other embodiments controller


31


may also be used for a variety of record keeping functions, such as maintaining a record of the amount of colorant dispensed over a given period of time. The amount dispensed may be displayed or otherwise accessed by an operator using keypad


33


. Controller


31


may be configured to provide an operator preferred parameters for flow regulator


46


and metering of colorant with pump system


40


via display


32


and keypad


33


. Also, it may be configured to assist the operator with adjustments relating to different wood chip types, sizes, or delivery rates. In this embodiment, the speed of conveyer


14


may also be sensed with controller


31


to ascertain optimum liquid mixture parameters of delivery system


20


. Also, controller


31


may control speed of conveyer


14


or


18


, or otherwise be coupled to mixer


60


to control various operational aspects thereof. In one alternative embodiment, control panel


30


, controller


31


, display


32


, control


34


, and switches


36


,


37


,


38


,


39


are embodied in a ruggedized personal computer customized with appropriate hardware and software to controllably interface with the other components of delivery system


20


and including a conventional video display and keyboard.




In an alternative embodiment, operator control via controller


31


is provided over the rate of water flow to the mixture instead of colorant. In this embodiment, colorant concentration is regulated by adjusting the amount of water with controller


31


, and the colorant flow is kept generally constant. In other embodiments, both water supply


24


and source


22


are operatively coupled to controller


31


to provide dynamic adjustment over the relative flow rate and amount of from each. In still other embodiments, more than two sources of liquid components may be operatively coupled to controller


31


to provide a desired liquid mixture.




Delivery system


30


may also be used to control delivery of various other mixtures of liquid agents or mixing components. Also, besides wood chips, other solid pieces may be treated with a given liquid mixture from delivery system


20


in mixer


60


. For example, a high gloss transparent coating on certain types of landscaping rocks or gravel may also be provided with system


10


. Preferably, this clear coat is provided by a mixture of water and an organic-based polymer component. Similarly, other solid pieces and liquid mixtures containing various components may be used with system


10


as would occur to one skilled in the art.




Referring next to FIG.


1


and

FIGS. 3-5

, additional details concerning mixer


60


are next described. Mixer


60


includes enclosure


61


defining chamber


70


. Enclosure


61


is elongated and has end


61




a


opposing end


61




b


along its length. Enclosure


61


has top


62


opposing base


64


. Opposing sides


66


and


68


join top


62


and base


64


. Top


62


defines inlet


72


and grated observation window


76


. Preferably, top


62


is provided by panels which may be removed to gain access to chamber


70


for maintenance purposes. Base


64


defines discharge outlet


74


.




In

FIG. 3

specifically, internal transverse support members


77




a


,


77




b


are shown in crosssection. Members


77




a


,


77




b


include a square cross-section and are preferably manufactured from carbon steel. Also, support flange


78


is illustrated between ends


61




a


and


61




b


of enclosure


61


. Adjacent end


61




a


,


62




b


is a right angle bearing flange


79




a


,


79




b


which supports mixer


60


.





FIGS. 1

,


3


and


4


illustrate a spray manifold


80


. Spray manifold


80


is in fluid communication with spray nozzles


82




a


,


82




b


,


82




c


(collectively designated nozzles


82


). In other embodiments, more or less nozzles may be used. Nozzles


82


are in fluid communication with chamber


70


. Manifold


80


has intake


84


configured to receive liquid through conduit


26


for distribution within manifold


80


to nozzles


82


. Excess liquid within chamber


70


may be drained through drain plugs


88




a


,


88




b


, as particularly illustrated in

FIGS. 3 and 4

.




Referring specifically to

FIG. 4

, a cross-section of chamber


70


is shown. Also, protruding end flange


86




a


is illustrated with a number of attachment sights


87


along its periphery. End flange


86




a


is joined to bearing flange


79




a


using conventional methods. A similar structure at end


61




b


is formed with end flange


86




b


and bearing flange


79




b


. At the bottom of chamber


70


is a triangular partition


89


. Preferably, enclosure


61


and manifold


80


are manufactured from a metallic material, such as carbon steel; however, other materials as occur to one skilled in the art are also contemplated.





FIGS. 1

,


3


, and


5


depict various features of drive mechanism


90


. Drive mechanism


90


includes motor


92


mounted to enclosure


61


by support


94


. Also drive mechanism


90


includes drive box


100


and gear box


110


. Preferably, motor


92


is electrically powered, but other types of motors may also be employed, such as a gasoline-fueled internal combustion engine. A shaft from motor


92


extends into drive box


100


and is connected to sprocket


102


therein. Sprocket


102


is operatively coupled to sprocket


104


by drive chain


106


.




Sprocket


104


is attached to auger


120


by coupling shaft


129




b


at the end of auger


120


closest to end


61




b


of enclosure


61


. An opposing end of auger


120


is attached to coupling shaft


129




a


which extends into gear box


110


. Within gear box


110


, gear wheel


112


is coupled to coupling shaft


129




a


and intermeshes with gear wheel


114


coupled to coupling shaft


149




a


. Shaft


149




a


is coupled to auger


140


at the end of auger


140


closest to end


61




a


of enclosure


61


. At the opposing end of auger


140


, coupling shaft


149




b


is coupled thereto. Coupling shafts


129




a


,


149




a


are rigidly attached to shafts


122


,


142


, respectively, and are journaled to enclosure


61


at end


61




a


by appropriate bearings. Coupling shafts


129




b


,


149




b


are rigidly attached to shafts


122


,


142


and are journaled to enclosure


61


at end


61




b


by appropriate bearings.




Referring specifically to

FIGS. 3-5

, auger


120


,


140


are further described. Auger


120


includes a shaft


122


generally oriented along the length of enclosure


61


. Attached to auger


120


is helical or spiral flight


124


. Flight


124


is configured to turn about shaft


122


in a counterclockwise direction as it advances from end


61




a


toward end


61




b


. Preferably, flight


124


makes at least three revolutions about shaft


122


. More preferably, flight


124


makes at least five revolutions about shaft


122


. Most preferably, flight


124


makes at least nine revolutions about shaft


122


.




Preferably, the pitch angle of flight


124


is at least 45°. More preferably, the pitch angle of flight


124


is in the range of 65° to 80°. Most preferably, the pitch angle of flight


124


is about 75°. As used herein, “pitch angle” means the angle formed between a tangent to an edge of the helical flight and the rotational axis of the flight.

FIG. 3

illustrates a pitch angle of flight


124


as angle A. In one embodiment, the pitch angle of flight


124


varies, with a portion closest to end


61




a


having a different pitch angle than the rest of flight


124


. In other embodiments, the pitch angle varies in a different fashion or is generally constant.




Referring specifically to

FIG. 3

, auger


120


includes mixing paddles


125


interposed along flight


124


. Each mixing paddle


125


is attached to shaft


122


by fastener


127


. Each fastener


127


has bolt


127




a


extending through shaft


122


and secured thereto by nut


127




b


. By loosening nut


127




b


, the pitch of mixing paddle


125


relative to flight


124


may be adjusted. Nut


127




b


is then re-tightened to secure the newly selected paddle pitch. Preferably, mixing paddles


125


do not extend as far from shaft


122


as flight


124


. It is also preferred that auger


140


include mixing paddles distributed along shaft


142


which are interposed with flight


144


(not shown).




In one embodiment, about twelve mixing paddles


125


are distributed along shaft


122


, being spaced along the segment of axis R


1


corresponding to flight


124


at approximately equal intervals. From one to the next, mixing paddles


125


of this embodiment are positioned about axis R


1


approximately 75 degrees apart. In addition, each mixing paddle has a portion extending from shaft


122


that has a generally planar sector shape. This sector shape sweeps about a 40 degree angle between radii extending from axis R


1


. Preferably, auger


140


is similarly configured for this embodiment.




Referring again to

FIGS. 3-5

, auger


120


also has a reverse spiral flight


128


spaced apart from flight


124


by gap


126


along shaft


122


. Preferably, flight


128


turns around axis R


1


at least 180 degrees. More preferably, flight


128


turns about axis R


1


at least 330 degrees. Most preferably, flight


128


turns about axis R


1


approximately 360 degrees or makes about one revolution around shaft


122


(including axis R


1


) between flight


124


and end


61




b


. Flight


128


advances in a direction from end


61




a


to


61




b


with a clockwise spiral rotation. Thus, the rotational direction of flight


128


is opposite the rotational direction of flight


124


.




Generally, shaft


122


along gap


126


is flightless. The length of gap


126


along shaft


122


is preferably about the length of flight


124


along shaft


122


corresponding to one revolution about shaft


122


. Gap


126


and flight


128


both partially overlap or overhang outlet


74


so that at least a portion of flight


128


is positioned over outlet


74


.




Auger


140


is configured similar to auger


128


except the rotational orientation of the flighting is reversed. Specifically, helical flight


144


of auger


140


turns about shaft


142


in a clockwise direction as it advances from end


61




a


to end


61




b


. Flight


148


turns about shaft


142


in a counterclockwise direction as it advances in a direction from end


61




a


toward end


61




b


. Augers


120


and


140


preferably intermesh a slight amount as most clearly depicted in FIG.


4


. This intermeshing is accomplished by slightly offsetting the maximum extension point of the flights relative to each other.





FIG. 4

illustrates additional characteristics of flight


124


,


144


. Shaft


122


has a maximum cross-sectional dimension (M) perpendicular to the plane of view of

FIG. 4

, and flight


124


has a distance D extending from shaft


122


along this plane. Preferably, the extension ratio (ER), of D to M is greater than 1; where ER×D÷M. More preferably, ER is at least 1.5, and most preferably ER is at least 2.0. The quantity M is determined as the maximum cross-sectional dimension of the shaft for its given shape along a cross-sectional plane perpendicular to its rotational axis. Similarly, D is determined as the distance the flight extends from the shaft along an axis perpendicular to the rotational axis of the shaft. Preferably, shafts


122


,


144


each have a generally right cylindrical shape, presenting an approximate circular cross-section perpendicular to rotational axes R


1


, R


2


; and flights


124


,


128


,


144


,


148


present a generally circular cross-section along a plane perpendicular to the rotational axes R


1


, R


2


of the shafts


122


,


142


, respectively.




Generally referring to

FIGS. 1-5

, selected operational features of mixer


60


are next discussed. Chips


12


enter inlet


72


of enclosure


61


via conveyer


14


. When activated, motor


92


turns sprocket


102


which rotates sprocket


104


via chain


106


. Rotation of sprocket


104


turns auger


120


about rotational axis R


1


in the direction RD


1


, driving auger


120


in a counterclockwise or “left hand” direction. Rotational axes R


1


, R


2


are shown in

FIG. 4

as cross-hair points generally concentric with the cross-section of shafts


122


,


142


, respectively. Notably, these axes are generally parallel to each other and are parallel to the longitudinal axis of augers


120


,


140


, and enclosure


61


.




The rotation of auger


120


turns gear wheel


112


contained in gear box


110


. Gear wheel


112


rotates gear wheel


114


in response in the opposite direction. Correspondingly, auger


140


rotates along with gear wheel


114


in a clockwise or “right hand” direction indicated by arrow RD


2


.




Rotation of flights


124


,


144


of auger


120


,


140


about axes R


1


, R


2


provides an “archimedes screw” type of conveyer which transports wood chips


12


entering inlet


72


along the direction indicated by arrow F, from end


61




a


toward end


61




b


. At the same time that flights


124


,


144


move material along arrow F, flights


124


,


144


also tumble and intermix the solid pieces with a liquid colorant mixture sprayed into chamber


70


via nozzles


82


. The liquid mixture is supplied by dispensing system


20


to manifold


80


. The mixing of the liquid and solid pieces continues as it travels past manifold


80


and by window


76


along arrow F. Mixing paddles


125


assist intermixing by agitating the mixture of solid pieces and liquid. Preferably, mixing paddles


125


are pitched to oppose the flow of material along arrow F; and thereby enhance mixing. By adjusting the pitch of mixing paddles


125


relative to flight


124


, the average dwell time in chamber


70


of a given material may be changed. This feature further assists in controlling absorption of the liquid mixture by the wood chips to minimize run-off.




As gap


126


is encountered by material moving through chamber


70


, processed wood chips


16


begin to exit through outlet


74


to be carried away by conveyer


18


in a direction indicated by arrow O.




Unfortunately, the wet mass of material at gap


126


has a tendency to stick together—despite gravity urging it to fall through outlet


74


. As a result, material may occasionally bridge gap


126


and encounter either or both of flights


128


and


148


. Because flights


128


,


148


oppose the rotational orientation of flights


124


,


144


, respectively; flights


128


,


148


both tend to move material opposite the direction of arrow F—that is in a direction away from end


61




b


. The opposing configurations of flights


124


,


144


with respect to flights


128


,


148


tend to break up a mass of material bridging gap


126


to thereby facilitate discharge through outlet


74


. Consequently, the auger configuration of mixer


60


tends to reduce the incidence of material packing in outlet


74


and so reduces the number of mixing interruptions due to jamming or clogging.




Mixer


60


may be used with a variety of liquid mixture types for coating or adhering a desired substance to wood chips. Likewise, various solid pieces other than wood chips may be processed in this manner. Preferably, mixer


60


is used so that the direction of the flow along arrow F is generally horizontal. However, in other embodiments, mixer


60


may be inclined in varying amounts as would occur to one skilled in the art.





FIGS. 6 and 7

depict mixing system


210


of another embodiment of the present invention; where certain reference numerals are the same as those used in connection with system


10


and are intended to represent like features. System


210


includes dispensing system


20


, spray hood


250


, and mixer


260


. Dispensing system


20


delivers a liquid mixture to spray hood


50


via conduit


26


that is dispersed within chamber


252


of spray hood


250


and then contacts solid pieces passing through mixer


260


. As previously described, system


20


is controller-based and regulates the blending of a mixture of an agent from source


22


with water from supply


24


. Likewise, as described in connection with mixing system


10


, the regulation and control processes implemented with dispensing system


20


also apply to system


210


.




Mixer


260


is coupled to spray hood


250


and includes a mixing trough


261


extending along its longitudinal axis L with opposing ends


261




a


,


261




b


. Trough


261


is partially covered by top


262


. Top


262


is opposite base


264


. Trough


261


is bounded by opposing side walls


266


,


268


and defines a mixing passage


270


. Trough


261


has inlet


272


defined through top


262


adjacent end


261




a


and outlet


274


defined through base


264


adjacent end


261




b


. Inlet


272


and outlet


274


intersect passage


270


. Inlet


272


and outlet


274


are separated from each other along axis L by distance LD


1


.




Disposed within passage


270


are augers


120


,


140


. Augers


120


,


140


extend from inlet


272


to outlet


274


and are turned by drive mechanism


90


via drive box


100


and gear box


110


as described in connection with mixer


60


of system


10


. Augers


120


,


140


have shafts is


122


,


142


and helical flights


124


,


144


, respectively, as previously described. As shown in

FIG. 6

, a space


223


is defined between flight


124


and shaft


122


except at the ends


225


,


227


which are connected to shaft


122


. Space


223


corresponds to a cross-section along axis L having a generally circular outer and inner contour bounded by flight


124


and shaft


122


, respectively. A like space is preferably defined between flight


144


and shaft


142


of auger


140


. To accommodate mixing, it is also preferred that space


223


extend between shaft


122


and flight


124


for a distance corresponding to at least three revolutions of flight


124


about shaft


122


. More preferably, this distance corresponds to at least six revolutions of flight


124


about shaft


122


. Most preferably, flight


124


is separated from shaft


122


and does not make contact therewith, defining space


223


therebetween, except where connected at ends


225


and


227


.




Further,

FIG. 6

depicts flight


128


overlapping outlet


274


with an opposite rotational direction relative to flight


124


. Flight


124


is separated from flight


128


by a flightless gap


126


along shaft


122


. Preferably, auger


140


has a second flight sized and positioned like flight


128


with a rotational direction opposite flight


144


as described in connection with system


10


. The second flights


128


,


148


for each auger


120


,


140


, respectively, have been found to reduce clogging at outlet


274


. Also as described in connection with system


10


, augers


120


,


140


preferably include adjustable mixing paddles


125


. Paddles


125


may be utilized to adjust dwell time of products being mixed in trough


261


.




Spray hood


250


defines chamber


252


and has a hinged access door


254


to facilitate maintenance as is best depicted in FIG.


7


. Manifold


280


is connected to the top of hood


250


and includes a number of spray nozzles


282


for delivering the liquid from system


20


to chamber


252


via supply conduit


284


. Conduit


284


receives and distributes the liquid from system


20


via conduit


26


coupled thereto. Several brackets


283


support conduit


284


along hood


250


above nozzles


282


. Conduit


284


terminates in end cap


284




a.






Referring to

FIG. 7

, it is preferred that each nozzle


282


have a spray pattern SP that subtends an angle A. Preferably, angle A is at least 60 degrees. More preferably, angle A is at least 80 degrees. One preferred nozzle


282


is model no. USS8060 provided by Spraying Systems Company having a business address of P.O. Box 7900, Wheaton, Ill. 60189-7900. This model is of the VEEJET line and sprays about 6 gallons per minute when supplied liquid at a pressure of about 40 lbs. per square inch (psi). Preferably, at least 8 nozzles are utilized. More preferably, at least 12 nozzles are utilized as depicted in FIG.


6


.




Referring additionally to

FIG. 8

, conduit


284


of manifold


280


includes a four-way conduit junction


286


for every four nozzles


282


. Each junction


286


is in fluid communication with two valves


287


on opposite sides thereof. Each valve


287


is in fluid communication with a “T” junction coupling


288


. A hose


289


is coupled to each opposite end of coupling


288


to a corresponding valve


290


in fluid communication with one of nozzles


282


. Thus, for the configuration depicted in

FIG. 6

, three junctions


286


, six valves


287


, and six “T” junction couplings


288


are utilized. Further, there are twelve hoses


289


and twelve valves


290


each corresponding to one of nozzles


282


.




In one preferred embodiment of hood


250


, chamber


252


is defined by a metal enclosure and door


254


is similarly formed from metal. For this embodiment, conduit


284


of manifold


280


is preferably formed from a two-inch diameter PVC pipe and junctions


286


are each provided as a four-way two-inch PVC connector. Valves


287


and


290


are of a half-inch variety and may be adjusted by hand. For this embodiment, transition members/reducers are used between values


287


and corresponding junctions


286


. Couplings


288


are likewise formed from PVC and hoses


289


are of a standard reinforced rubber type for this embodiment.




At the intersection of chamber


252


with passage


270


an area for contacting pieces in trough


261


is defined. This area is designated as contact area CA in

FIGS. 6 and 7

. Area CA has a length LD


2


along the distance LD


1


as shown in FIG.


6


. Preferably, distance LD


2


is at least about half of distance LD


1


. More preferably, distance LD


2


is at least two-thirds of distance LD


1


. Augers


120


,


140


occupy a maximum width across passage


270


below spray hood


250


represented as width W


1


in FIG.


7


. W


1


is the maximum transverse distance across axis L collectively occupied by augers


120


,


140


. Area CA preferably has a width that is at least one-half the width W


1


. More preferably, the width of area CA is at least about three-fourths of the width W


1


. Most preferably, the width of area CA is substantially all of width W


1


as shown FIG.


7


.




In correspondence with area CA, nozzles


282


are spaced at intervals along axis L to provide a collective spray pattern along distance LD


2


. Preferably, the spray pattern has a length of at least about one-half of distance LD


1


and a width at least about one-half of width W


1


. More preferably, the length of the spray pattern along axis L is at least about two-thirds the distance LD


1


and a maximum width of at least about three-fourths of width W


1


. Most preferably, the spray pattern has a length generally the same as distance LD


2


that is greater than or equal to about two-thirds of the distance LD


1


and a width that is substantially all of the width W


1


at a number of intervals along the distance LD


2


. As depicted in

FIG. 7

, it is also preferred that nozzles


282


be separated from augers


120


,


140


by a height of at least one-half W


1


to facilitate dispersal of the liquid from system


20


in chamber


252


before contacting solid pieces being carried through passage


270


.




In operation, mixer


260


is configured to accept solid pieces through inlet


272


which are then advanced along passage


270


towards outlet


274


in the direction indicated by arrow F by turning augers


120


,


140


with drive mechanism


90


. As the pieces are advanced with augers


120


,


140


, they are tumbled and intermixed facilitating coating, coloring, or another mixing process with a liquid introduced through spray hood


250


. The pieces passing through mixer


260


may be, for example, wood chips of a suitable size and consistency for use as a mulch and the liquid delivered with system


20


may be a mixture of a liquid colorant and water to impart a desired color to the wood chips.




Collectively, the valves


287


,


290


may be adjusted to provide a desired spray pattern within chamber


252


with nozzles


282


. For example, each valve


290


may be adjusted to selectively reduce or shut-off the spray from the nozzle


282


coupled thereto. Valves


287


may each be used to shut-off or adjust flow to each respective pair of nozzles


282


coupled thereto via a corresponding coupling


288


, pair of hoses


289


, and pair of valves


290


. In one mode of operation, valves


287


are used to make coarse adjustments and valves


290


are used to make fine adjustments. By selectively adjusting valves


287


,


290


and parameters of system


20


previously described, greater control over the mixing process may be obtained. In one alternative embodiment, these nozzles are electronically controlled by a controller to establish various predetermined patterns (not shown).




Moreover, it has been found that the expansive spray pattern of system


210


facilitates a reduction in water usage needed in order to color wood chips to provide a suitable mulch with a generally uniform color. It is believed this reduction in water consumption results because the amount of chip surface area contacted by the color-imparting spray is greater than with existing systems, so that the amount of color-imparting liquid that needs to freely flow in trough


261


to properly color the wood chips is comparatively less. However, it should be understood that it is not intended that the claimed invention be limited to any stated mechanism or theory.




Several experiments were performed using equipment arranged as described for system


210


. A number of different types of wood based products were colored in a manner suitable to serve as a mulch. The tested products may be as much as 40% by volume saw dust with the balance being wood pieces having a maximum dimension in a range of about ½ inch to about 2 inches. Also, the tested product has a widely varying moisture content. Coloration was performed by contacting the wood product with a liquid coloring mixture obtained by mixing a concentrated liquid colorant with water. Water consumption of 10 gallons or less per cubic yard of wood product colored was observed under these conditions. This result indicates at least a 20% reduction in water consumption compared to other coloration systems.




In one preferred embodiment, system


210


is used to color wood chips provided in a consistency suitable for application as a mulch; however, in another embodiment, a scent is additionally supplied in order to simulate a known type of mulch such as eucalyptus, cedar, or pine. For this embodiment, scent may be dispensed in a liquid form from a separate system comparable to system


20


and may be introduced into chamber


252


through one or more nozzles


282


instead of the colorant mixture. Alternatively, the scent may be homogeneously mixed with colorant and water before being dispensed to hood


250


, or a single vessel containing concentrated liquid colorant and scent that has been premixed may be mixed with water in dispensing system


20


and subsequently supplied to hood


250


.




In still other embodiments, system


210


may be used with a variety of liquid mixture types for coating or adhering a desired substance to solid pieces. Indeed, solid pieces other than wood chips may be processed in this manner, such as rocks, cardboard, synthetic resin pieces, and the like. Moreover, while it is preferred that mixer


260


generally be maintained in a horizontal position, in other embodiments, trough


261


may be inclined in varying amounts as would occur to one skilled in the art. In addition, it is envisioned that various components and operations described in connection with systems


10


and


210


may be interchanged, deleted, substituted, combined, modified, divided or reordered as would occur to one skilled in the art without departing from the spirit of the invention.




All publications and patent applications cited in this specification are herein incorporated by reference as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference, including, but not limited to, commonly owned U.S. patent application Ser. No. 08/650,871, filed May 20, 1996.




While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes, modifications, and equivalents that come within the spirit of the invention as defined by the following claims are desired to be protected.



Claims
  • 1. A mixing system, comprising:a vessel configured to supply a liquid; a device configured to supply a number of wood pieces for mixing with the liquid; an elongate enclosure having a first end opposing a second end and defining a chamber in fluid communication with said vessel to receive the liquid, said chamber having an inlet and an outlet, said inlet being closer to said first end than said outlet, said chamber being configured to receive the pieces from said device through said inlet and to discharge the pieces through said outlet; a first motor-driven mixing auger positioned in said chamber and being configured to rotate about a rotational axis to intermix the liquid and the pieces, said first auger including: a first helical flight between said inlet and said outlet configured to convey the pieces in said chamber from said inlet to said outlet when rotated, said first flight turning about said rotational axis at least three revolutions between said inlet and said outlet; and a second helical flight between said first flight and said second end, said second flight having a length along the rotational axis shorter than said first flight, said second flight turning about said rotational axis at least 180 degrees and being at least partially positioned over said outlet, said second flight having a rotational orientation opposite the first flight.
  • 2. The system of claim 1, wherein said first flight and said second flight are mounted about an elongated shaft configured to rotate about said rotational axis and a portion of said first flight does not contact said shaft while turning about said rotational axis for said at least three revolutions, defining a space therebetween.
  • 3. The system of claim 1, further including an exit conveyor to move said pieces away from said outlet.
  • 4. The system of claim 1, wherein the liquid includes a colorant.
  • 5. The system of claim 1, further comprising a second motor-driven auger in said chamber.
  • 6. The system of claim 1, wherein said first auger includes a number of mixing paddles, each of said mixing paddles being configured with an adjustable pitch relative to said rotational axis.
  • 7. The system of claim 1, wherein said second flight makes at least about one revolution about said rotational axis.
  • 8. The system of claim 1, wherein said auger has a shaft portion between said first flight and said second flight without flighting.
  • 9. A mixing system, comprising:a vessel configured to supply a liquid; an elongated enclosure having a first end opposing a second end and defining a chamber in fluid communication with said vessel to receive the liquid, said chamber having an inlet and an outlet, said inlet being closer to said first end than said outlet, said chamber being configured to receive a number of wood pieces through said inlet and to discharge the pieces through said outlet; and a first motor-driven mixing auger operable to rotate about a rotational axis and intermix the liquid and the pieces, said first auger including a first flight positioned between said inlet and said outlet, said first flight being operable to advance the pieces in said chamber from said inlet toward said outlet when said first auger is rotated, a first conveying member positioned along said first auger between said first flight and said second end, said first conveying member being operable to advance the pieces in a direction opposite said first flight when said first auger is rotated, said first conveying member at least partially overlapping said outlet, and a number of mixing paddles, each of said mixing paddles being configured with an adjustable pitch relative to said rotational axis.
  • 10. The system of claim 9, wherein said first conveying member includes a second flight with a rotational orientation opposite said first flight.
  • 11. The system of claim 9, further comprising a second motor-driven conveying auger positioned in said chamber having a second flight and a second conveying member, said second flight and said second conveying member being configured to urge the pieces in the chamber in opposite directions when said second auger is rotated.
  • 12. The system of claim 9, wherein said first auger includes an elongated shaft and a portion of said first flight does not contact said shaft while turning about said shaft at least three revolutions, defining a space therebetween.
  • 13. A mixing system, comprising:a liquid dispensing system operable to deliver a mixture of water and colorant to a mixing chamber to impart color to wood chips, said liquid dispensing system including, a pump operable to selectively receive a colorant from a colorant source, a controller operable to control metering of the colorant with the pump a conduit coupled to said pump and configured for coupling to a water source to deliver the mixture to said chamber, the liquid dispensing system being operable to change the colorant provided to the mixture by said pump from a first non-zero rate to a second non-zero rate the mixing chamber comprising an elongate enclosure having a first end opposing a second end and being in fluid communication with said liquid dispensing system to receive the mixture, said chamber having an inlet and an outlet, said inlet being closer to said first end than said outlet, said chamber being configured to receive a number of wood pieces through said inlet and to discharge the pieces through said outlet; and a first motor-driven mixing auger operable to rotate about a rotational axis and intermix the liquid and the pieces, said first auger including, a first flight positioned between said inlet and said outlet, said first flight being operable to advance the pieces in said chamber from said inlet toward said outlet when said first auger is rotated, and a first conveying member positioned along said first auger between said first flight and said second end, said first conveying member being operable to advance the pieces in a direction opposite said first flight when said first auger is rotated, said first conveying member at least partially overlapping said outlet.
CROSS-REFERENCE TO RELATED APPLICATIONS

The present Application is a divisional of U.S. patent application Ser. No. 09/231,691 filed Jan. 14, 1999, which is a continuation-in-part of U.S. patent application Ser. No. 08/650,871 filed May 20, 1996 (now U.S. Pat. No. 5,866,201).

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Entry
*The Revolutionary Second Harvester, Mulch Coloring System, by Becker-Underwood, Inc., Marketing brochure, dated Oct. 1996.
“Marion Mixers, Engineered Solutions for Unique Mixing Application Since 1938”, http://www.marionmixers.com/co.htm, visited on Aug. 10, 2000.
Continuation in Parts (1)
Number Date Country
Parent 08/650871 May 1996 US
Child 09/231691 US