US2350096A - Forage drying method - Google Patents

Description

May 30, 9 4- F. s. CHILTON FORAGE DRYING METHOD Filed March 14, 1941 4 Sheets-Sheet 1 May 30, 1944. F. s. CHILTON FORAGE DRYING METHOD Filed March 14, 1941 4 Sheets-Sheet 2 INVENTOR. smwuwww May 30, 1944. F. s. CHILTON FORAGE DRYING METHOD Filed March 14, 1941 4 Sheets-Sheet 3 IN V EN TOR.

4 Sheets-Sheet 4 IN VEN TOR.

F. S. CHILTON Filed March 14, 1941 FORAGE DRYING METHOD May 30, 1944.

Patented May 30, 1944 UNITED STATES PATENT OFFICE roman name METHOD Forrest S. Chilton, Pompton Plains, N. J.

Application March 14, 1941, Serial No. 383,273

Claims. (Cl. 99-8) This invention relates to forage drying methods and more particularly to methods of forage drying by artificial heat.

As generally practiced, the art is properly divisible into carrier method systems and pneumatic method systems.

In the carrier method systems a continuous supply of forage is treated by hot gases while being conveyed by foraminous endless belts through oblong rectangular kilns. In the pneumatic method systems a continuous supply of forage is treated by hot gases while travelling therewith through stationary drum kilns or revolving drum kilns. The systems are called co-flow when the hot gases travel in the same general direction as the forage and counter-flow when the hot gases travel in the opposite direction. The co-flow systems use a higher initial temperature in the drying medium than the counter-flow systems do and are also known as high temperature systems while the counter-flow systems are generally known as low temperature systems.

In both classes of systems the fresh forage enters the kilns through hopper inlets or equivalents. The finished product is removed therefrom by materially differing devices.

The continuous supplies of forage formed for treatment are generally called layers or mats.

Mats must be at least 6" thick to be of practical use in an apparatus of practical size. Gen erally they are thicker. The term matlet as used herein means a layer so thin that it would require a substantial multiple thereof to equal the thickness of a mat. An initial thickness of about 2" is preferred. After going through the steps hereinafter set forth the final thickness will be between and l".

The systems in both classes have long been confronted and still are confronted with the difilcult problems of preventing over-drying of leaves and under-drying of stems and of preventing spotty over-drying and spotty under-drying,- problems that must be solved before forage dry-- ing by artificial heat can come into general use or even be considered reasonably satisfactory. Moreover the importance of preserving the vitamin content and the color content is now recognized.

The objects of this invention are (l) to prevent or, at least, materially lessen said over-drying of leaves and under-drying of stems, (2) to prevent or, at least, materially lessen said spotty over-drying and spotty under-drying and (3) to prevent or, at least, materially reduce injury to the vitamin content and the color content.

Over-drying of leaves and under-drying o] stems In seeking a solution of the leaf over-drying and stem under-drying problem it became evident that, to a very high degree, leaves and small stems were amenable to the law that closely contacting bodies equalize their heat content and their moisture content, but that coarse stems were not amenable to that law because of their tough non-porous integuments.

It also developed that, if the coarse stems were adequately lacerated or crushed and then compressed into close contact with the leaves and small stems, no discoverable over-drying of leaves or under-drying of stems took place and that, even where close contact was not brought about, over-drying of leaves and under-drying of stems are materially lessened by lacerating or crushing the coarse stems whereby the non-porous integuments lost their integrality. By crushing they are cracked. The term lacerate, as used herein, includes cutting, slicing, ripping and abrasing.

A comparison of results between lacerating and crushing favors lacerating. It is very difficult to adequately crack the coarse stems by crushing without destruction of stem and leaf cells, loss of valuable water soluble food material and a material decrease in the palatability of the stems. Those drawbacks never result from lacerating the coarse stems.

Moreover, it was found that adequately lacerated coarse stems may be compacted by compression into close contact with the leaves and small stems without any injury to their cells or loss of water soluble content. There is some advantage and no harm in compacting the supply for the pneumatic system. The velocity of the drying medium soon disintegrates the matlet or mat. In the meantime, stem and leaf drying tend to equalize.

Spotty over-drying and spotty under-drying The failure to find a way to form mats of uniformity in depth and density accounts for spotty over-drying and spotty under-drying in the carrier systems. Likewise the failure to find a way to supply pneumatic systems with a stream of uniform volume and density accounts for the same unsatisfactory result in those systems. Hot gases insist on selecting the path of least resistance.

It became apparent that the reason for such failure to attain such uniformity in depth and density lies in bunches due to knots, snarls, varying mixtures of species and other causes which are always present in layers as initially formed and will even, to a considerable extent, survive a comminution step.

The only remedy found for such bunch difficulty is an added step for disintegrating them. However, disintegrating a bunch increases its volume and this upsets such uniformity of depth there may have been. Absolute freedom from spotty over-drying and spotty under-drying cannot generally be attained without adding a depth uniforming step following the disintegration of the bunches.

It was found practical to completely disintegrate such bunches on a scale of practical utility.

Matlets The outer layers of full depth mats so thoroughly operate as cushions to protect the inner that adequate compacting is not attainable unless such compacting proceed to the crushing stage which I desire to avoid for. the reasons above stated.

Moreover, the depth uniforming step following the disintegrating and lacerating step is much simpler and more certain where matlets are involved. To a considerable extent knots and twists are torn and distributed by the initial formation oi matlets.

However. treatment in the kiln of single matlets would require prohibitively large apparatus to give an' adequate output. This difficulty is overcome by forming a supply for treatment in the klins composed of successive accumulations of equal multiples of the compacted matlet. The passages between the successive accumulation, the passages between the layers of the matlet in the accumulations and the thinness of matlets all combine to give a supply extremely permeable to the gases regardlessof the depth. Fortunately, such a mat may be formed mechanically as well as manually.

Color content and vitamin content Neither nitrogen nor carbon dioxide will injure chlorophyll, carotene or the vitamins. The degree of heat in the drying medium seems to be of no importance except to shorten the exposure time. The extent of their injury or loss depends solely on the relative amount of free oxygen IJIICS- ent and the exposure time.

There is always some oxygen present in combustion gases. It decreases and there is acorresponding increase in carbon dioxide in direct proportion to the oxidation that take place during the use of the medium.

By using a drying medium composed of recirculated used gases raised to the desired temperature by an infusion of hot combustion gases the relative free oxygen content gradually decreases and the relative carbon dioxide content gradually increases to a point where but little injury to the vitamin or color content occurs in a low temperature system and practically none occurs in a high temperature system. Only enough used gases is expelled from the apparatus to permit the infusion of suflicient hot combustion gases to secure the desired temperature.

The advantage seems to be on the side of the high temperature recirculatory systems. The exposure time is generally less than one fifth of that in the low temperature systems. It is easy to obtain temperatures of much over 2,500 degrees F. in the combustion gases. The initial high temperature of the medium in the carrier system will generally be below 1000 degrees F. The recirculated gases start at over 212 degrees F. At least two-thirds of the used gases may be recirculated. The incoming fresh free oxygen is correspondingly lessened. Many heat units are saved.

There are no dangers connected with high temperatures that cannot be guarded against and there are advantages other than those above mentioned.

Practically speaking, no degreeof gas temperature can injure the forage so long as a substantial amount of moisture is oozing therefrom. There is no danger of'any harm to the sufficiently dried forage from gas temperature not exceeding 300 degrees F., unless long exposed thereto. Precipitation of moisture on the cured fodder will not occur if the finishing gas temperature is kept substantially above 212 degrees F. superheated steam is an excellent dehydrating medium and will carry almost an unlimited amount of moisture without danger of precipitation. Moreover, it seems no virus, bacterium, fungus or spore can survive a drying process starting with a temperature substantially over 700 F.

A preferred apparatus for utilizing the above mentioned improvements and principles will now be described.

Figure l is a longitudinal sectional view of a. fragment of the feeding combination. Figure 2 is a longitudinal sectional view of the fragment complementary to that shown in Figure 1 when used in carrier systems. Figure 3 is a sketch of the feed end of a drier of a pneumatic kiln type.

Figure'4 is a fragmentary sectional view on lines 4-4 of Figure 1. Figure 5 is a portion of Figure 1 slightly enlarged. Figure 6 is a side elevation view of the fragment represented by Figure 1. Figure 7 is a fragmentary top view of the hinged portion of the conveyor shown in Figure 6.

Figure 8 is a top plan view of the apparatus with parts of the feeding combination omitted. Figure 9 is a fragmentary longitudinal view of the aft part of the furnace on line 9-9 of Figure 8. Figure 10 is a vertical sectional view of the kiln enclosure on lines Ill-l0 of Figure 8.

Figure 11 is a longitudinal sectional view of the whole drier. partly schematic. Figure 12 is a diagrammatic representation of the method of supporting furnace brick positioned on the sides and ends.

Figure 13 is a side elevation view of the whole drier. Figure 14 is a fragmentary horizontal sectional view of the kiln enclosure on line I 4- of Figure 13.

In Figure 1, endless floor belt 20, mounted on drums 28 and 32, supported by rollers 30 and bearing teeth 22, is positioned for moving toward the kiln of the apparatus. Hackle 26 is positioned transversely over said floor belt. Then follows a drum 36, bearing teeth 38, partly surrounded by hood 34 and transversely positioned over floor belt 20. Teeth 38 are positioned for passing between floor teeth 22 and just clearing floor 20. On the kiln side of drum 36, a row of knives 46 is positioned so that drum teeth 38 pass between them and just clear knife shank 44. Knives 48 just clear drum 38.

' Floor 20, hackle 26, drum 36 and knives 46 are enclosed in reservoir ii of which I6 is the back wall, 42 the front wall and 34 a cross wall. Guide l8, supported by timber l9 and back wall It, extends severalfeet beyond the top of It. Instead of supplying floor 20 with fresh forage by the usual manually manipulated fork method, forage in bulk is lodged between l8 and 24, If preferred, the enclosure may be omitted and the hand method substituted. If this is skillfully done, hackle 26 may be omitted.

Hackle 26 is set so that a very thin'matlet emerges from thereunder. The linear velocity of drums 36 should be a substantial multiple of that of floor 28. The more teeth on drum 36 and the greater its velocity, the better it performs. The thicker the matlet, the greater the velocity of, and the greater the power required to revolve 36 must be.

Teeth 38 pick to pieces and completely disintegrate all surviving bunches in the matlet. Hood 34 prevents centrifugal diflioulties.

The coarse stems in the forage passing around under hood 34 are lacerated as they pass through knives 46. The small stems and the leaves remain substantially unaffected.

From knives 46 the forage falls on endless conveying belt 58, bearing teeth 52 and positioned between said floor belt 28 and forage inlet 58 to the kiln, as shown in Figures 1 and 2. It is mounted on clockwise revolving drums 48 and 58. While the matlet, at this point, is uniform in density it is not uniform in depth. Hackle 54 is positioned transversely over belt 58. The oblique and trembling movements of belt 58, combined with belt teeth 52 and hackle 54, uniforms the depth of the matlet.

Clockwise involving roller 68 and anti-clockwise revolving roller 62 are positioned in forage inlet 58 as shown in Figure 2. These rollers compress and closely compact the matlet. After being so compacted the matlet is conducted by guides 64 and 66 to top foraminous carrier belt 18. The linear velocities of floor 28, conveying belt 58 and rollers 68 and 62 are the same, but are substantial multiples of the linear velocity of carrier belts I8 in the kiln. The mat 68 formed on top carrier I8 is composed of successive equal accumulations of said compacted matlet measured by said multiple. Guide 64 terminates just below the top of the mat 68, Guide 66 terminates slightly above the desired top of the mat. Seeking the line of least resistance the gas stream forces the bases of the forming accumulations under guide 66. This results in a mat 68' of substantially upright successive accumulations of equal multiples of the matlet.

If a pneumatic apparatus is used, the matlet may be deposited at the multiple rate in hopper I2 shown in Figure 3.

The explanations of drum 36 in Figure l are applicable to Figure 4. The knives 46 and teeth 38 must be frequent enough so that the coarse stems will he lacerated as distinguished from chopped and crushed. One-half inch space between knives seems satisfactory.

Drums 36 as shown in Figure 5 may be conveniently made of sheet iron. The teeth may be conveniently made by bolts passing through the sheet iron and fastened down by nuts. The same is true as to teeth 22 on floor belt 28 and teeth 52 on belt 58. Hackles 26 and 54 may be conveniently made of drilled angle irons and common nails.

Figure 6 portrays the detachable construction of the disintegrating and stem lacerating elements of Figure 1. Hinged joint 88 of Figures 6 and 7 is provided to facilitate portability when desired. 82 is a block supported by the sides I8 of the conveyor and to which is attached hackle 54 as shown in Figure 1.

In top plan view shown in Figure 8, 58 is the conveying belt shown in Figure l. 84 is the furnace. 86 indicates a steel jacket surrounding the furnace. 88 is the outet flue of furnace 84. 98 is a duct connecting flue 88 with inlet 84 in gas induction chamber 82.

I88 indicates the vas.

steel wire woven into a mesh. The bolt teeth belt from output shaft 88 for driving jackshait I82. I84 indicates the exhaust chamber at end of kiln. I86 represents the outlet from exhaust chamber I84 into duct I88 connected with intake I89 of suction fan H8. H2 shows fan outlet connected by duct II6 to flue 88. Belt H4 is driven by jackshaft I82 and, in turn, revolves fan shaft I I I. H8 is a vari-speed transmission driven by :belt I28 from jackshaft I82. I22 is the transmission output shaft by which belt I23 and others are driven for revolving the various drums and the compressing rollers.

In Figure 9, 88, 86 and H6 are the flue, jacket, duct respectively indicated in Figure 8.

The explanation of Figure 18 will be better understood by comparing it with Figures 13 and 14. The framework consists of angle irons I26. To this framework are attached removable top panels I28 and side panels I32 framed in angle irons I38. All side panels and all end panels except those connected with exhaust chamber I84 are fastened by angle irons I38 to plank foundation I34. The panels may be made of marinite boards. These are excellent for high temperature systerns, but most have additional insulation at any point where the temperature is constantly at 1080 F. or higher and should have if above 900 F.

Nearly all the elements in Figure 11 have already been fully explained. As in many rectangular kilns, the forage passes from one foraminous carrier to the other, is turned over at each elbow and moves alternately in opposite directions until discharged. Gas'inlet chamber 92 extends the full width of the kiln. Baifles I36 serv to equalize the gas flow over carrier I8. I38 is a screen belt positioned and moved for separating the forage from the gas stream and conducting it into rotary valve I48. Flexible tins I4I on the blades of the rotor portion serve as seals against air intake, as brushes to keep belt I38 clean of air obstructing particles, as ladles to remove the mat from the screen belt I38, as minimizers of friction and as springs to catapult the mat through openings I42. I43 guides the mat to I44 which may convey it to any desired spot. Guide I45 prevents accumulation on floor.

As shown in Figure 12 steel jacket 86, surrounding the furnace, serves to hold in position the steel hangers I46 that support the fire bricks I48 on the sides and ends of furnace 84. Air enters through openings (not shown) in jacket 86 at the back of the furnace. The air passes between jacket and the furnace brick back to the oil burner supplementary air inlet I53, shown in Figure 13. There are,also air passages I52 under the furnace leading back to I53.

In side elevation Figure 13, take-up bearings I54 keep the kiln carrier belts taut. Chain I62 is driven by a sprocketon output shaft I22 and in turn drives the sprocket wheels I63, which revolve drums II of Figure 11. Chain I64 is driven by an extra sprocket wheel on the shaft fourth drum II down and in turn drives the sprocket wheels which operate the discharge combination.

Another sprocket wheel on output shaft I22 drives chain I23 which, in turn, drives sprocket wheels 51, I56, I58 which rotate drum 56 and rollers 68 and 62 of Figure 2. Take-up bearings I59 support and furnish a way to vary the distance between rollers 68. and 62 of Figure 2. Drum 48 and drum 56 shown in Figures 1 and 2 and 11 are large and heavily lagged with can- Conveying belt 58 is composed of heavy have their heads on the underside. All this resuits in ,sumcient traction for transmitting to drum 48 of Figure 1 adequate power for revolving drums 32 and 36 of Figure 1 by means of sprocket wheels on shafts 40, 33 and 41 .and sprocket chains 14 and 16.

As before said, Figure 14 is a fragmentary horizontal section line H-Il of Figure 13. Steel plates I" are welded to angle irons I30 of the panels I51 and support the bearings for sprocket wheels I83. As to the other items the explanation of Figure 10 applies.

Suction fan I I draws combustion gases from the furnace 84 and recirculated used gas from duct H6 through flue 88, duct 90, gas inlet chamber 92, carrier belts 10, screen belt I 38, exhaust chamber I04, outlet I06, duct I08 and fan intake I09 and then compresses it through outlet H2 into duct 6. A portion of the used gases is vented through a port (not shown) in duct 6 near outlet H2 and the balance compressed through duct H6 into flue 88. Thermostatic control of the oil feed to keep the finishing temperature between 250 and 275 is provided.

The matlet, disintegrating, lacerating, uniforming and matting features make a combination that not only eliminates substantial leaf overdrying, stem under-drying, spotty over-drying and under-drying but, also materially reduces the required kiln space. These features, combined with a high temperature system, enable a kiln 12' x 6' x 6' to eliminate between 1500 and 2000 pounds of moisture per hour.

Such a drier may be easily mounted on a truck. The conveyor may be folded at hinge 80. The detachable disintegrating and lacerating combination may be put on a trailer. The oil burner may have a separate detachable mounting that can be loaded on the trailer or a less bulky furnace may be installed.

The discharge above described is the subject of pending application for Patent No. 320,230, filed March 14, 1941. elimination of the necessity of a comminuting step. The downward movement of the hot gases eliminates possibility of blow-outs and consequent loss of uniformity in depth.

1 claim:

1. A method of forage drying in kiln apparatus which includes the step of combing the forage into a matlet and the step of disintegrating the bunches and lacerating the coarse stems in the matlet followed by the steps of uniforming its depth, compacting it, forming a supply for treatment in the kiln'composed of successive accumulations of equal multiples thereof an subjecting the supply so formed to drying medium consisting of recirculated used gases raised to the desired temperature by an infusion of hot combustion gases.

2. A method of forage drying in kiln apparatus which includes the step of combing the forage into a matlet and the step of disintegrating the bunches and lacerating the coarse stems in the matlet followed by the steps of uniforming its depth, compacting it and forming a supply for treatment in the kiln composed of successive accumulations of equal multiples thereof.

3. The method of drying forage in kiln apparatus which includes steps comprising combing the forage into a matlet, disintegrating the bunches therein and then uniforming the density thereof, followed by steps comprising compacting the matlet and forming a supply to be subjected to hot gas treatment composed of successive accumulations of equal multiples thereof.

This feature completes the I 4. The method of drying forage in kiln apparatus which includes steps comprising combing the forage into a matlet and disintegrating the bunches therein, followed by a step comprising forming a supply to be subjected to hot gas treatment composed of successive accumulations of equal multiples of said matlet.

5. An improvement in the art of drying forage in driers of carrier type comisting in forming a uniformly deep and dense thin continuous matlet of stem lacerated forage, compacting said matlet and then forming a mat to be processed composed of successive accumulation of equal multiples of the compacted matlet whereby uniformity in depth and density and a high degree of permeability by the hot gases are attained and the principle of closely contacting forage bodies equalizing their water and heat content is utilized.

6. An improvement in the art of drying forage in driers of the carrier type consisting in forming a uniformly deep and dense thin continuous matlet of the forage, compacting said matlet and then forming a mat for treatment composed of successive accumulations of equal multiples of the compacted matlet whereby uniformity in depth and density and a high degree of permeability by hot gases are attained and the principle that closely contacting forage bodies equalize their water and heat content is utilized.

''7. In a forage drying kiln of the endless belt carrier type the new and useful method of supplying the carrier belts with mats of uniform depth and density which consists in combing the knots, snarls and bunches out of the forage followedvby steps comprising recombing the supply into a matlet of uniform depth, compacting said matlet and then depositing the matlet on the upper carrier belt in successive accumulation of equal multiples thereof.

8. In a forage drying kiln of the endless belt carrier type the new and useful method of supplying the carrier belts with mats of uniform depth and density which consists in combing the knots, snarls and bunches out of the forage followed by steps comprising recombingthe supply into a matlet of uniform depth and then depositing said matlet on the upper carrier belt in successive accumulations of equal multiples thereof.

9. In a forage drying kiln of the endless foraminous belt carrier type, the new and useful method of supplying the carrier belt with, and maintaining thereon, mats of uniform depth and density which consists in combing the knots, snarls and bunches out of forage followed by steps comprising recombing the supply into a matlet of uniform depth, compacting said matlet, depositing it on the upper carrier belt in successive accumulations of equal multiples thereof and causing the hot gases to move downwardly through the mat so formed.

10. In a forage drying kiln of the endless foraminous belt carrier type, the new and useful method of supplying the belts with, and maintaining thereon, mats of uniform depth and density which consists in combing the knots, snarls and bunches out'of the forage followed by steps comprising recombing the supply into matlets of uniform depth, depositing said matlet on the upper carrier belt in successive accumulations of equal multiples thereof and causing the hot gases to move downwardly through the mat so formed.

FORREST S. CHILTON.

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