CA1161245A - Method of spraying liquids on the surfaces of particles - Google Patents
Method of spraying liquids on the surfaces of particlesInfo
- Publication number
- CA1161245A CA1161245A CA000390315A CA390315A CA1161245A CA 1161245 A CA1161245 A CA 1161245A CA 000390315 A CA000390315 A CA 000390315A CA 390315 A CA390315 A CA 390315A CA 1161245 A CA1161245 A CA 1161245A
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- blender
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- hollow drum
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Abstract
ABSTRACT OF THE DISCLOSURE
To uniformly and economically disperse liquids, via sprays of droplets, on surfaces of particles a method of moving the particles involves their rotary lifting, followed by their free falling, with a spray of droplets originating from a central area of the overall motion path of the particles. In a preferred embodiment of the method and a preferred embodiment of the blending apparatus, a hollow drum is rotated about a near horizontal axis. Inside the drum on a common rotating shaft spaced slightly conical discs ultimately dis-perse respective sprays of droplets from a central area. This central area is defined by particles being lifted while centrifugally held to the interior of the drum and then at a zenith locale the gravita-tional force becomes effective enough so the particles drop in an arcuate cascade path back to the interior surface of the drum to start another cycle. The cycles are predetermined to continue until the particles acquire the selective quantity of dispersed droplets on all of their surfaces. Then the particles leave the interior of the rotating hollow drum opposite the end of their entry into the drum.
This method and apparatus is particularly useful in treating, with liquid resin binders, and/or wax emulsions, thin wood wafers, wood flakes, wood shavings, sawdust and other particles of like respective sizes, which often are subsequently collectively formed and pressed into products, such as wood wafer boards.
To uniformly and economically disperse liquids, via sprays of droplets, on surfaces of particles a method of moving the particles involves their rotary lifting, followed by their free falling, with a spray of droplets originating from a central area of the overall motion path of the particles. In a preferred embodiment of the method and a preferred embodiment of the blending apparatus, a hollow drum is rotated about a near horizontal axis. Inside the drum on a common rotating shaft spaced slightly conical discs ultimately dis-perse respective sprays of droplets from a central area. This central area is defined by particles being lifted while centrifugally held to the interior of the drum and then at a zenith locale the gravita-tional force becomes effective enough so the particles drop in an arcuate cascade path back to the interior surface of the drum to start another cycle. The cycles are predetermined to continue until the particles acquire the selective quantity of dispersed droplets on all of their surfaces. Then the particles leave the interior of the rotating hollow drum opposite the end of their entry into the drum.
This method and apparatus is particularly useful in treating, with liquid resin binders, and/or wax emulsions, thin wood wafers, wood flakes, wood shavings, sawdust and other particles of like respective sizes, which often are subsequently collectively formed and pressed into products, such as wood wafer boards.
Description
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BAC~GROUND OF THE INVENTION
Throughout industry there is of-ten the requiremen-t to effi-ciently and economically disperse liquids on the surface of particles which should not undergo mechanical damage or abrasion. Moreover, many of these particles are collectively crowded together to form a composite product. The integral strength success of the composite product, where for example the liquids are binders, is based on the unirorm or near uniform dispersemen-t of the liquid throughout all the surface areas of -the par-ticles.
These factors are especially true when wood produc-ts are being manufactured. However, presen-t methods and available appara-tus do no-t completely fulfill all of the currently desired economic, quali-ty and efficiency objec-tives.
For example in respec-t -to the wood wafer board industry disperse~ment of resin binders is under-taken in blenders, wherein finely pulverized dry resin is applied to wood wafers via -tumbling wi-thin an inclined ro-ta-ting drum. The dry resin, so pulverized, is obtained a-t a higher cost than liquid resins. In -the par-ticle board industry wood chips are sprayed wi-th liquid resins while -the wood chips undergo in-tense agitation. The liquid resin is sprayed into the turbuLen-t mass of wood chips via air atomization or via fluid pressure nozz:Les. These wood chip blender-s have nozzles which produce droplets in an unwan-ted wide dispersion of drop:Let sizes. Their air driven atomization sprays tend -to carry -the finest drople-ts of resin ou-t in air ven-ting streams, thus creating a nuisance while wasting resin.
Moreover, in these wood chip blenders, -the in-tense agita-tion produces heat and creates more fine material from -the particles, -tha-t in turn, -tends -to absorb a dispropor-tiona-te frac-tion of the consumed resin.
In addition, resin-par-ticle agglomerates tend -to build up on -the walls and paddles of -these blenders requiring frequen-t cos-t:Ly cleaning ~6~24~
main-tenance.
T. M. Maloney in 1977 in a Miller-Freeman publica-tion on pages 438 through 457 in discussing modern par-ticleboard and dry pro-cess fiberboard, said labora-tory experimen-tation has shown -that indus-trial blenders do no-t perform near optimum conditions. Thus important developments can ye-t be made in -this critical production step.
In respect to information presen-ted in United States patents, W. Wirz in his Uni-ted S-tates patent No. 4,193,700 of March 18, 1980 disclosed a shor-t leng-th drum wi-th in-ternal vanes or lifters rotated -to yield an intermittent cascade of particles, while a spray nozzle dispersed a binder in an axial direction, from the feed end of the drum into the particle cascade. Also K. Engels in his United S-tates pa-ten-t No. 4,188,130 of February 12, 1980 illus-tra-ted and described a drum wi-th in-ternal lif-ters -to ro-tary lif-t partic:les for -their sub-sequen-t cascading, while a-t -the feed end of -the drum, nozzlex axially sprayed liquid resin toward -the particles. Although Messrs. Wirz and Enge:Ls' apparatus compara-tively gen~tly handled the particles, -the reliance on axially direc-ted sprays required a high drople-t concen-tra-tion of liquid resin -to achieve a reasonable output rate of treated particles. Such high concentration of resin drople-ts tends to yield a wide range in droplet size and reduces the opportunity for uniform coverage of the par-ticles. Moreover, because one third -to two thirds of -their in-terior drum surfaces and lifters are also exposed to the spray of resin, there is the wasteful accumulation of resin on these exposed in-terior surfaces, also incurring cleaning maintenance cos-ts.
Improved dispersemen-t of liquid resins is also needed in -the emerging s-tructural board manufac-turing processes, wherein carefully sliced wood wafers and Flakes are used. To attain maximum panel strengths of these s-tructural boards the sliced wood wafers and fla]ces should remain undamaged in blending opera-tions and -thereaf-ter -they ~-- .
should be aligned, as described by ~1. D. Turner in an article entitled '-Structural Flakeboard Stiffness Rela-tion -to De:Flection Criteria and Economic Performance', as published in Fores-t Produc-ts Journal Volume 27, Number 12, December, 1977.
In respect -to all such rela-ted uses of resins, -the distribu-tion of the resins mus-t be very efficient. Resin, at five percent of -the dry wood weight, has a resin cost which is about one half of the wood cost. Usually the resin cost is -the second largest cos-t element in wood board manufacturing.
Therefore, gentle handling of flakes and maximum efficiency of -the resin dis-tribution with minimum losses of resin are bo-th impor-tant objectives in operating wood board processes, and especially in operating s-truc-tural board processes wherein the wood wafers and wood flakes are aligned.
SUMMARY OF INVENTION
A new blending me-thod and new blending apparatus are provided to more efficien-tly utulize liquids such as resin binders and wax emulsions, par-ticularly in -the wood produc-ts indus-try, by crea-ting controllable sprays of drople-ts having a high propor-tion of uniform sized droplets leaving the dges of spinning discs. The particles are moved via a gen-tle action and in reEerence to wood wafers, wood flakes, -there is minimal damage or change to these particles. There are no high speed agitation forces or high pressure agitation forces involved. Moreover, blender main-tenance is very minimal in respect to misdirected sprays of liquids and -the accumula-tion of f;nes, both of which would o-therwise cause plugging or jamming of a blender. This is true for -the spray is essentially always in-tercep-ted by -the par-tic'Les, which shield -the in-terior walls of -the blender. By using the new blending me-thod and apparatus, i-t is es-tima-ted -the liquid savings, i.e. resin binder savings, e-tc., will range from three 6-~ 2~
thousand to five thousand dollars a day, at 1980 price levels, during the operation of a typical three hundred ton capacity plant, i.e. a wafer board mill.
In respect to the method, the uniform and economical disperse-ment of the liquids, via sprays of droplets, on surfaces of particles is undertaken by moving the par-ticles via rotary lifting, followed by their free falling, with a spray of droplets originating from a central area of the overall mo-tion path of the partlcles.
In a preferred embodimen-t of the blending appara-tus, a hollow drum is rotated about a near horizontal axis. Inside the drum, moun-ted on a common rotating shaft, are spaced slightly conical discs, which ul-tima-tely disperse respec-tive sprays of drople-ts from a cen-tral area. This cen-tral area is de-termined or defined by -the par-ticles being lif~ted, while centrifugally held to the interior of the drum and then at the zenith locale near -the top of the drum in-terior, -the gravitational force becomes effective enough so the par-ticles drop in an arcuate ¢ascade path back down to the interior surface of the drum -to star-t another cycle. These cycles of lifting and cascading are predetermined in number to con-tinue until the particles acquire -the selective and sufficient quan-tity of dispersed droplets on all -their surfaces. Then the -trea-ted particles leave -the in-terior of the rota-ting hollow drum a-t -the exi-t end, opposi-te -the end of -their en-try in-to -the drum. This me-thod and appara-tus is par-ticularly useful in -treating, wi-th liquid binders and/or wax emulsiQns, -thin wood wafers, wood flakes, wood shavings, sawdus-t, ancl o-ther particles of li]ce respec-tive sizes, which often are subse~
quen-tly collec-tively :Eormed and pressed in-to produc-ts such as wood ~afer boards and s-truc-tural boards.
ESCRIPTION OF _ ~WINGS
~ preferred embodiment and o-ther embodiments of the blending _ L~ _ L 2 ~ ~
appar-atus are illustrated in the drawings supplemented by illus-tra-tive manufac-turing facility schematic flow charts, and graphs concern-ing the working r-ange of droplet size and travel, wherein:
Figure 1 is a schematic flow char-t of a composite wood pro-duct manufacturing facility indicating where the blending apparatus and method are utilized with respect to -the order of the overall.
apparatus and method;
Figure 2 is a graph illustrating the desirable working range in respec-t to -the size and travel of the droplets of -the l.i~uids, such as resin binders and wax emulsions;
Figures 3 and 4 are cross sectional views illustrating the me-thod and apparatus with respect to the ro-tary lifting of the par-ticles, followed by their free falling in an arcuate cascade, with a spray of drople-ts originating from a cen-tral area of -the overall motion pa-th of the particles, also showing differen-t interior surface configurations o:F -the drums;
Figure 5 is an isome-tric view of a pre:Ferred embodimen-t of -the b:Lending apparatus, i.e. the blender, wi-th por-tions removed for i]lustrating the interior of the drum, and the arrangemen-t on the shaf-t and the multiple discs;
Figure 6 is a side view of another embodiment of the blender illus-trating a -tapered drum and also showing -the entry and exit for -the par-ticles;
Figure 7 i.s a side view of another embodimen-t of the blender illus-trating a three section drum, with each sec-tion being of a differen-t diameter and having a respec-tive drive assembly opera-ting a-t a differen-t ro-tating speed, and also showing the entry and exi-t for -the par-ticles;
Figure 8 is a pa:r-tial. longi-tudinal cross sec-tional view -taken near -the en-try end of -the blender showing -the long ro-ta-ting ~ 3 ~
shaft that carries spray discs illustrating the supply and s-tarting distribu-tion o:F both a resin binder and a wax emulsion;
Figure 9 is a par-tial -transverse cross sectional view show-ing the starting dis-tribu-tion of -the wax emulsion, with this view being taken along line 9-9 of Figure 8;
Figure 10 is a partial -transverse cross sec-tional view showing the starting distribution of the resin binder, with this view being taken along line 10-10 of Figure 8;
Figure 11 is a partial transverse cross sectional view show-ing -the s-tarting distribution of both the resin binder and wax emulsion wi-th -this view being -taken along line 11-11 of Figure 8; and Figure 12 is a partial longitudinal cross sectional view illus-tra-ting how a liquid, either the wax emulsion or -the resin binder, is dis-tributed -to -the ou-ter periphery, i.e. the rim, of -the rotating, sligh-tly conical, disc, for depar-ture in a spray of droplets enrou-te to dispersion on -the su-rfaces of -the particles.
DESCRIPTION OF THE INVENTION
-One Environmen-t oE Where the Blending Me-thod and Blender are Utilized The preferred embodiment o~ -this inven-tion is described in reference -to its u~tilization in a manufacturing process wherein wood par-ticles are formed and pressed in-to wood products. In Figure 1 the overall me-thod s-teps and rela-ted apparatus of such a manufac-turing process are illustrated in char-t form. Logs are debarked and cut to length 10; ho-t soaked 11; flakes or other particles are made 12; they are dried 14; and as necessary the dried flakes are s-tored in a bunker 16, for subsequent processing. These inven-tions, i.e. both a blending me-thod and a blender 18, are used in the nex-t step of -the overall process, wherein -the par-ticles are efficien-tly, economically, and uni~orm:ly -treated in -the b:Lender being sprayed wi-th drople-ts of resin binder and/or wax emulsions. The -trea-tecl par-tic:les are, if necessary, 2 4 ~
s-tored in a bunker 20; then formed 22 in ma-t; ho-t pressed 24, adjusted for moisture content in a humidifier 26; trimmed by saws 28; stored, as necessary in a warehouse 30; and shipped 32 upon an order of a customer.
Preferred Liquid Drople-ts Sizes and Their Travel in Reference to Their Creation and to Their Dispersion, Reference to a Disc Spraying Theory In the practice of this method and the ar-rangemen-t and opera-tion of the apparatus, -the crea-tion of the liquid droplets in all r-espects, and especially in reference to their si~es and travel, is very important. Also, as discussed subsequently, the movemen-t of the particles to receive the dispersed droplets is likewise very impor-tant.
In reference to a disc spraying theory, -the production of sprays and mis-ts by means of spinning discs, is believed to have been first investigated experimen-tally and -theore-tically by Messrs. Walton and Prewet-t and later in more de-tail by Mr. Drummond. These earlier experimen-ts may have per-tained -to spinning discs used commercially to spray insecticides and paints; however -the observa-tions are deemed pertinent to understanding why and how rotating, i.e., spinning, discs are used in -the method and blender of this inven-tion.
The forma-tion of drops leaving from the edge of a spinning dics is analogous in many ways to drop forma-tion leaving from a sta-tionary -tip. Liquid flows -to the edge of -the disc and accumula-tes until the centrifugal force on the collected mass is greater -than the re-taining forces due to surface tension, and then -the drop is thrown off. Thus, it is reasonable -to expect -the produc-t of the surface tension and linear dimension of the drop to -the propor-tional -to -the cen-trifugal force.
In symbols: (~d3 p ) ( w2 D ~ ~ Td or rearranging ( 6 ) ( 2 ~ ~ 6~245 dw (TP) = constant where d = drop diame-ter T - liquid surface tension p = liquid specific D = disc diameter gravity w = disc angular velocity Extensive experiments by Messrs. Wal-ton and Prewett resulted in an average value for the constant of 3.8, wi-th a range of 2.67 to 6.55. Their experimen-ts also showed, the sharpness or edge profile of the disc was of minor importance. In the range of viscosity investigated, 0.01 to 15 poise, viscosi-ty had lit-tle effect on tne spraying process, although high viscosi-ty did tend to reduce the maximum flow ra-te a-t which homoegenous drops are formed. At small drop sizes, the drops or drople-ts become airborne, forming a mis-t.
Mr. Drummond presented his experimental resul-ts showing the effec-ts of flow ra-te Q, kinema-tic viscosi-ty u, and spin rate w, on the drop size d and ra-te of drop produc-tion. Drop volume is shown to exceed the volume predic-ted by Messrs. Wal-ton and Prewe-tt's sta-tic model, indica-ting that -the dynamics of drop forma-tion mus-t be included in the model.
In -the course of perfecting this invention a number of exper-iments were conducted in which a paper -tape was exposed to the spray pa-t-tern for a short in-terval, thus recording -the droplet size distri-bu-tion and spray pattern. Bo-th water and high viscosity liquid phenol formaldehyde resin were used. U-tilizing equation, and -the following parame-ters: D = 250 mm, w = 53L~ radians/second, T = 7.3 dyne/mm, and p = 1.1, -the theore-tical drop size was predicted a-t 0.12 mm as compared -to experimen-tal values of 0.20 to 0.30 mm. This agreement was con-siclered sa-tisfac-tory, and i-t was no-ted -the drops inevi-tably -tend to spread ou-t, ra-ther than retain -their spherical shape upon reaching a surface of a par-ticle -to be -trea-ted.
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In Figure 2, the liquid droplet size and travel are illus-tra-ted in a graph to indicate the working range selected in reference -to the method and operation of the blender of this inven-tion. The drople-t size graph line has a y ordina-te regarding size expressed in microns and an x ordina-te regarding centrifugal force expressed in multiples of the gravitational force. The drople-t size graph line has a y ordinate regarding dis-tance to -travel in centimeters and an x ordinate regarding centrifugal force expressed in multiples of the gravi-ta-tional force. The droplet size range is from approximately 200 -to 50 microns and the droplet travel range is from about 90 cm to 20 cm depending on liquid proper-ties and gravi-ty force multiples at the spray disc rim.
Thus, volume per drop may range from 4200 x 103 cubic microns to 65 x 103 cubic microns, i.e. a 64 fold range in drop size.
The Con-trolled Movemen-t of Particles as They are Being Trea-ted wi-th -the Sprayed Liquids, Commencing with Ro-tary Lifting and Then at a Zeni-th Locale Free Falling at an Arcuate Cascade, Wi-th the Spray Coming from Spinning Discs Located on -the Central Area Defined by the Overall Movement Path of -the Particles In Figures 3 and 4, -the contr-olled movemen-t of par-ticles 13 is illustra-ted as viewed in a -transverse sec-tion -taken -through a rotating drum 17 of a blender 18. The drum 17 rotates in a clockwise rotational direction on bearings 15 mounted on an adjus-table frame 19, shown in par-t. In a central area 21 or volume of the interior of the drum 17 -there are spaced ro-tating, i.e. spinning, discs 52 which create the spray of drople-ts of liquids such as resin binders or wax emulsions.
The interior walls 23 of -the drum 17 are coated with a plas-tic finish so -the par-ticles 13 will not adhere to -these in-terior wall surfaces. Also even-tually when cleaning becomes necessary, the plastic covered walls are readily cleaned. Thereforel as viewed in Figures 3 and ~, longi--tudinal ribs 25 or raised portions 27, i.e. lands and grooves are u-tilized in assis-ting iTI -the ro-tary lif-ting of -the par-ticles 13 -to compensa-te when necessary for -the effec-ts of -the plas-tic finish. They _ g_ insure -the radial in-termixing of the par-ticles as -they traverse the blender.
As illustrated in bo-th Figures 3 and 4, the particles 13 are rotary lifted while positioned adjacent -to the interior wall 23 of the drum, un-til gravitational forces become effec-tive in causing the particles 13 to freely fall in an arcuate cascade un-til reaching again the interior wall 23 to begin ano-ther cycle. Each respec-tive spinning disc is located, in reference to a par-ticular -transverse cross sectional view, within -the central area defined by the overall movement of the collective particles 13. As observed in Figures 3 and ~ the sprayed droplets 29 reach the particles without any appreciable amount of them escaping on through to unwantedly contact the in-terior wall 23 of the blender 18.
The Addi-tional Controlled Movemen-t of -the Par-ticles Under Trea-tment to Move them on Through the Blender While Being Sprayed wi-th Liquids and Reference to Speed Changes at -the Circumference of the Interior of the Drum In Figures 5, 6, and 7, -the longi-tudinal observations indi-ca-te -the drum 17 of -the blender 18, in various embod;men-ts, always ro-tates abou-t a near horizon-tal axis, with the entry end receiving -the particles 13 being higher than the exit end discharging the particles 13. The reten-tion -time of the par-ticles 13 in -the blender 18 is con--trollable by adjus-ting the angle of inclination of the blender in respect to its near horizon-tal axis. Generally depending on the inclina-tion angle the par-ticles make from twenty -to forty revolutions while being -treated in the blender 18. For example in a ten foot diame-ter blender twen-ty fee-t long a one minu-te re-ten-tion time, when -the drum 17 is ro-ta-ting at twenty five revolu-tions per minute, requires an inclina-tion angle of about four and one half degrees.
In reference -to -the ro-ta-tional speed of -the drum 17 of a blender 18, under some circumstances, as wood wafers, for example, ~ 3 ~4~
acquired resin binder on -their surfaces the drum speed preferably has to be gradually decreased -to achieve -the most desirable cascading free falling ac-tion of the particles 13. Therefore, in reference to -the entire length of a drum 7, and realizing as the particles progress from the en-try -to the exit they gain in their receipt of resin binder, -the peripheral or circumferential speed is automatically reduced by utilizing a -tapered drum 33 as illustrated in Figure 6. Or a sectional drum 34 is used as shown in Figure 7 for a mu1ti-stage operation wi-th the telescoping sections 35, 36, 37 being opera-ted at different rotational speeds so their respec-tive peripheral or circumferential speeds may be reduced as necessary.
The Arrangement of the Componen-ts of the Blender as Illus-trated in E'igure 5 The blender 18 illus-tra-ted in Figure 5, has a drum 17 of constant outside diameter. As necessary -the in-terior diame-ter changed by -the addi-tion of prperly sized liners, not shown, to accommodate -the possible need for a reduc-tion in the peripheral speed, i.e. speed a-t -the circumference of -the in-terior. The overall suppor-ting frame 19 is adjustable to change the retention time of -the particles 13 within the drum 17. A-t the exit end -there is a pivota] frame mounting 38 and at the forward end there is a level changing frame mounting 39.
Such angular adjus-tment of frame lg likewise adjus-ts the en-tire compo-nents of the blender 18 through -the small angle of inclina-tion.
A motor 40, via a power transmission bel-t ro-tates ahft 42.
Spray discs 52, 53, 54, 55, 56 and 57 are mounted a-t spaced intervals a]ong large diame-ter -tubular shaf-t 42 and their spinning speed is controlled by opera-ting mo-tor 40.
An adjus-table speed mo-tor 43, via a power -transmission bel-t of change 44, drives a line shaft 45 moun-ted on bearings 46 secured -to :Frame 19. Near -the ends of shaf-t 45 are fric-tiona:L drive wheels 47 which ro-tate within circumferen-tial track channels or rails 48 secured around -the drum 17, thereby rotating the drum 17 in a clock-wise direction, as indicated by the motion arrow in Figure 5.
The Arrangement of -the Components of the Blender as Illustrated in Figure 6, and the Entry and Exi-t of -the Par-ticles The blender 18 illus-tra-ted in Figure 6, has a tapered drum 33 which serves to automa-tically reduce the peripheral speed, i.e.
speed at the circumference of the in-terior, -to compensa-te for -the particles nearing the exit which have changed in dynamic behavior in respect to their adhering resin binder droplets 29. The angular adjustments of the horizontal inclination of the drum 33 are similar to those indica-ted in Figure 5. Also the power transmissions respec-tively -to both the shaft 42 and the tapered drum 33 are similar to -those described in regard -to -the blender 17 shown in Figure 5. As is also true~ bu-t not shown in Figure 5, the particles 13 are illustrated in Figure 6, being delivered via a loading conveyor 49 and direc-ted into a loading chute 50 secured to -the non-rota-ting entry end enclo-sure 51. After passage through -their various advancing cycles within -the drum 17, -the particles :L3 with -their accumulated resin binder leave the drum 33 via the exi-t chute 58 positioned by the non-rotating exit end enclosure 59 and then they drop onto the discharge conveyor 60.
The Arrangement of the Components of the Blender as Illus-trated in Figure 7 and the Entry and Exit of -the Particles The blender 18 is illustrated in Figure 7, has a sectional drum 34 having three sections 35, 36, and 37 increasing in diameter and -telescoping. Many of the componen-ts are siMilar to -those illustra-ted in Figures 5 and 6 and are indicated by like numerals. Each sec-tion 35, 36 and 37 is driven a-t a different speed so the peripheral speed, i.e. speed a-t -the circumference of -the respec-tive -three different diame-ter interiors may be independen-tly con-trolled decreasing 2 ~ ~
in speed f-rom -the en-try -to -the exi-t of -the sectional drum. This speed reduction is under-taken -to accommoda-te -the par-ticles receiving -the resin binde-r which a-t -the slower speed will -then commence -their free fall in -the cascade a-t -the proper zeni.-th locale on -the respective in-teriors oF -the drum sections 35, 36 and 37. The power being dis-tri-bu-ted by the line shaf-t ~5 is dis-tributed via -three -transmission bel-t or chain assemblies 6:1., 62, 63 -to respec-tive secondary power distri-bu-tion shaf-ts 64, 65, 66 a-t -the respec-tive drum sec-tions 35, 36 and 37.
The drive whee:Ls ~7 Follow channels or rails ~8.
The Dis-tribu-tion and Supply o:E -the Liquids, For Example, the Resin Binders and Wax Emulsions, -to -the Spinning or Rotating Discs Which Crea-te -the Spray of Drople-ts I:n :Figures 6, 8, 9, 10, 11~ and 12, -the distribution and supply of -the liquids, i.e. resin binder R and wax emulsion W, to the spinning discs, such as disc 52, are i.l.lus-tra-ted. ~s shown in Figures 6 and 8, concen-tric s-ta-tionary supply -tubes 67 and 63, respectively receive -t'he resin binde:r R and the wax emuls.iorl W, received -through hoses 69 and 70 being fed by pUlllpS 71 and 72 from conve:n-tional supp:Ly sources of each which are no-t shown. Thereaf-ter -the resin binder R
and the wax emulsion W, af-ter directional changes shown in Figure 8 leave -the s-ta-tionary supply -tubes 67 and 68. These liquids leave -through downwa:rd poin-ting s-tub ~tubes 73, 7~, which have exit holes 75 direc-ted -to nearby pla-tes 76 and 77 which are :ro-tating rapidly with -the shaf-t ~i2.
Bearing '78 is used in posi-tioning -the stationary supply -tubes 67 and 68 rela-tive -to -these por-tions, inclusive of pla-tes 76 and 77, which are ro-ta-ting wi-th -the sha:F-t ~2. Bearing 79 is used -to posi--tion the :ro-ta-t:ing s'ha~-t re:La-ti,ve -to ~the frame 19 of -the blender 13.
The resin binder R and the wax emulsion W, respec-tively upon 3n :Leaving exi,-t holes 75 t:ravel throug}l space un-til. reachi:ng pla-tes 76 al-ld 7'7. T~le:reclf-ter cerxtr:i.:Fuga~ or:~ce moves l,he ~I.;quids :radia:l.ly outwardly -to -the inner wall 80 of a cylindrical sec-tion 81. Pla-te 82, installed with the aid of grooves 108 and sealing rings 109 similarly -to the ins-tallation of pla-te 76 serves -to keep the resin binder R and wax emulsion W separated -throughou-t -the opera~tions as -these liquids from the respec-tive rota-ting shallow toroidal pools 83, 84. Continu-ously during operations, -the liquids depart from -these supply pools 83, 84 and enter respective dis-tribution -tubes 85, 86, 87, 88, 89, and 90, which longitudinally distribute the resin blender R and wax emul-si.on W to spinning discs 52, 53, and 54 being supplied from -the entry end of the blender 18. Spinning discs 55, 56 and 57 are supplied in like manner from the exit end of -the blender 18. These dis-tribu-tion -tubes are located within the protec-tive longitudinal cylindrical shaft 91 secured by fas-teners 93, af-ter being posi-tioned in plate 92 which also seals off the liquids :F:rom -the interiors of the shaft associated componen-ts such as tubular shaft 91. The cross sec-tional views of Figures 9, 10 and 11 Fur-ther illustrate -the dis-tribution of liquids R
and W.
In Figure 1.2 distribution of liquid resin binder ~ to a spinning disc 53 is shown. This liquid is directed through conduits 85 and 89~ then caused -to change direc-tion into stub tubes 94, 95 and discharged in-to a first shallow -toroidal supply pool 96. Af-ter reach-ing a pre-se-t level, -the liquid is longitudinally drained in-to a larger shallow toroidal pool 97 via a series of annular holes 98 in a dividing par-tial bulkhead, flange, or annular orifice :ring 99. Thereafte:r in an adher-ing ou-twardly flow path 100~ -the liquid moves -to -the rim 101 of -the spinning disc 52. The flow of liquid in pa-th 1.00 uni.formly ex-tends -throughou-t the circular conical surface area of -the disc 52 -to even-tuall.y con-tinuous:Ly depar-t in a spray o:F drople-ts 29. The peri-me-ter speed o:F disc 52 is abou-t four-teen -thousand Eee-t a minu-te for a disc 20 inches in diame-ter~ Circu:lar- pla-te :L03 secured by fas-teners ~ 3 ~3~ 2~ 5 104 shields the f]ow path 100 of liquid from wind and dust. Fasteners 105 secure the disc assembly 106 to the tubular shaf-t 91. Fas~teners 107 secure the disc to the disc assembly 106.
Though six spinning discs are illus-trated in Figure 5, i-t is feasible -to use as few as two or up to -twelve depending on the capa-city requiremen-ts. The effective spray travel, as indicated in Figure 2 is governed by -the size of the drople-t and disc speed. A-t a cons-tant G factor, for example, of 2000, the spray -torus diameter is changed rela-tively little in size, whether the disc is -ten inches or -twenty inches in diameter.
Information Concerning the Design Considerations in Respect to a Selected Shaft on Which -the Spinning Discs are Mounted The natural resonan-t frequency of a long, rotating shaft de-termines limi-ts on sha:Ft size, speed and span between bearings.
The applicable formula for this embodiment is:
N = 69~ ~ Where: N = natural frequency in V - 8 circles per second E = shaE-t modulus o:F elas-tici-ty: for s-teel - 29,000,000 psi I = moment of inertia of shaft (Inch4) ~0 W = total weight between bearings (Lbs) L = span between bearings (inches) For a 12 inch steel shaf-t wi-th a 0.50 wall thickness with a span of 18 ft. between bearings carrying six twenty inch diameter discs -the natural frequency speed is about 3,500 RPM. To at-tain 2,000 times gravi-ty force a-t disc rim requires abou-t 2,650 RPM. This operating speed provides a wide safety margin below cri-tical resonant speed.
Information Concerning Design Considera-tions in Respect to Drum Speeds as They eEfect -the Peripheral Speed, i.e. ~the Speed a-t the Circumference of -the Interior of -the Drum In pilo-t scale -testing using a 94.5 inch diame-ter drum, dry wood wafers, i.e. zero percen-t resin binder, had -the op-timum free 2 ~ ~
falling arcuate cascading action a-t twenty eight and three -tenths revolutions per minute. This op-timum speed decreased, in an exponen-tial fashion, to twen-ty six and -thir-ty -three hundredths revolutions per minute at a six percent resin binder content.
If the ~ree falling arcuate cascading action is not properly maintained, an unwanted loosely compac-ted layer of wood wafer, i.e.
particles, wi-th their resin binder, may form within the drum. This layer could periodically disintegrate and cause opera-tional control problems. However, if the drum is too slow, the wafers start falling pr-ematurely and may fall directly onto long tubular shaf-t and spinning discs, thus degrading quali-ty of resin distribu-tion while allowing resin to reach inner wall of -the drum.
~ .
BAC~GROUND OF THE INVENTION
Throughout industry there is of-ten the requiremen-t to effi-ciently and economically disperse liquids on the surface of particles which should not undergo mechanical damage or abrasion. Moreover, many of these particles are collectively crowded together to form a composite product. The integral strength success of the composite product, where for example the liquids are binders, is based on the unirorm or near uniform dispersemen-t of the liquid throughout all the surface areas of -the par-ticles.
These factors are especially true when wood produc-ts are being manufactured. However, presen-t methods and available appara-tus do no-t completely fulfill all of the currently desired economic, quali-ty and efficiency objec-tives.
For example in respec-t -to the wood wafer board industry disperse~ment of resin binders is under-taken in blenders, wherein finely pulverized dry resin is applied to wood wafers via -tumbling wi-thin an inclined ro-ta-ting drum. The dry resin, so pulverized, is obtained a-t a higher cost than liquid resins. In -the par-ticle board industry wood chips are sprayed wi-th liquid resins while -the wood chips undergo in-tense agitation. The liquid resin is sprayed into the turbuLen-t mass of wood chips via air atomization or via fluid pressure nozz:Les. These wood chip blender-s have nozzles which produce droplets in an unwan-ted wide dispersion of drop:Let sizes. Their air driven atomization sprays tend -to carry -the finest drople-ts of resin ou-t in air ven-ting streams, thus creating a nuisance while wasting resin.
Moreover, in these wood chip blenders, -the in-tense agita-tion produces heat and creates more fine material from -the particles, -tha-t in turn, -tends -to absorb a dispropor-tiona-te frac-tion of the consumed resin.
In addition, resin-par-ticle agglomerates tend -to build up on -the walls and paddles of -these blenders requiring frequen-t cos-t:Ly cleaning ~6~24~
main-tenance.
T. M. Maloney in 1977 in a Miller-Freeman publica-tion on pages 438 through 457 in discussing modern par-ticleboard and dry pro-cess fiberboard, said labora-tory experimen-tation has shown -that indus-trial blenders do no-t perform near optimum conditions. Thus important developments can ye-t be made in -this critical production step.
In respect to information presen-ted in United States patents, W. Wirz in his Uni-ted S-tates patent No. 4,193,700 of March 18, 1980 disclosed a shor-t leng-th drum wi-th in-ternal vanes or lifters rotated -to yield an intermittent cascade of particles, while a spray nozzle dispersed a binder in an axial direction, from the feed end of the drum into the particle cascade. Also K. Engels in his United S-tates pa-ten-t No. 4,188,130 of February 12, 1980 illus-tra-ted and described a drum wi-th in-ternal lif-ters -to ro-tary lif-t partic:les for -their sub-sequen-t cascading, while a-t -the feed end of -the drum, nozzlex axially sprayed liquid resin toward -the particles. Although Messrs. Wirz and Enge:Ls' apparatus compara-tively gen~tly handled the particles, -the reliance on axially direc-ted sprays required a high drople-t concen-tra-tion of liquid resin -to achieve a reasonable output rate of treated particles. Such high concentration of resin drople-ts tends to yield a wide range in droplet size and reduces the opportunity for uniform coverage of the par-ticles. Moreover, because one third -to two thirds of -their in-terior drum surfaces and lifters are also exposed to the spray of resin, there is the wasteful accumulation of resin on these exposed in-terior surfaces, also incurring cleaning maintenance cos-ts.
Improved dispersemen-t of liquid resins is also needed in -the emerging s-tructural board manufac-turing processes, wherein carefully sliced wood wafers and Flakes are used. To attain maximum panel strengths of these s-tructural boards the sliced wood wafers and fla]ces should remain undamaged in blending opera-tions and -thereaf-ter -they ~-- .
should be aligned, as described by ~1. D. Turner in an article entitled '-Structural Flakeboard Stiffness Rela-tion -to De:Flection Criteria and Economic Performance', as published in Fores-t Produc-ts Journal Volume 27, Number 12, December, 1977.
In respect -to all such rela-ted uses of resins, -the distribu-tion of the resins mus-t be very efficient. Resin, at five percent of -the dry wood weight, has a resin cost which is about one half of the wood cost. Usually the resin cost is -the second largest cos-t element in wood board manufacturing.
Therefore, gentle handling of flakes and maximum efficiency of -the resin dis-tribution with minimum losses of resin are bo-th impor-tant objectives in operating wood board processes, and especially in operating s-truc-tural board processes wherein the wood wafers and wood flakes are aligned.
SUMMARY OF INVENTION
A new blending me-thod and new blending apparatus are provided to more efficien-tly utulize liquids such as resin binders and wax emulsions, par-ticularly in -the wood produc-ts indus-try, by crea-ting controllable sprays of drople-ts having a high propor-tion of uniform sized droplets leaving the dges of spinning discs. The particles are moved via a gen-tle action and in reEerence to wood wafers, wood flakes, -there is minimal damage or change to these particles. There are no high speed agitation forces or high pressure agitation forces involved. Moreover, blender main-tenance is very minimal in respect to misdirected sprays of liquids and -the accumula-tion of f;nes, both of which would o-therwise cause plugging or jamming of a blender. This is true for -the spray is essentially always in-tercep-ted by -the par-tic'Les, which shield -the in-terior walls of -the blender. By using the new blending me-thod and apparatus, i-t is es-tima-ted -the liquid savings, i.e. resin binder savings, e-tc., will range from three 6-~ 2~
thousand to five thousand dollars a day, at 1980 price levels, during the operation of a typical three hundred ton capacity plant, i.e. a wafer board mill.
In respect to the method, the uniform and economical disperse-ment of the liquids, via sprays of droplets, on surfaces of particles is undertaken by moving the par-ticles via rotary lifting, followed by their free falling, with a spray of droplets originating from a central area of the overall mo-tion path of the partlcles.
In a preferred embodimen-t of the blending appara-tus, a hollow drum is rotated about a near horizontal axis. Inside the drum, moun-ted on a common rotating shaft, are spaced slightly conical discs, which ul-tima-tely disperse respec-tive sprays of drople-ts from a cen-tral area. This cen-tral area is de-termined or defined by -the par-ticles being lif~ted, while centrifugally held to the interior of the drum and then at the zenith locale near -the top of the drum in-terior, -the gravitational force becomes effective enough so the par-ticles drop in an arcuate ¢ascade path back down to the interior surface of the drum -to star-t another cycle. These cycles of lifting and cascading are predetermined in number to con-tinue until the particles acquire -the selective and sufficient quan-tity of dispersed droplets on all -their surfaces. Then the -trea-ted particles leave -the in-terior of the rota-ting hollow drum a-t -the exi-t end, opposi-te -the end of -their en-try in-to -the drum. This me-thod and appara-tus is par-ticularly useful in -treating, wi-th liquid binders and/or wax emulsiQns, -thin wood wafers, wood flakes, wood shavings, sawdus-t, ancl o-ther particles of li]ce respec-tive sizes, which often are subse~
quen-tly collec-tively :Eormed and pressed in-to produc-ts such as wood ~afer boards and s-truc-tural boards.
ESCRIPTION OF _ ~WINGS
~ preferred embodiment and o-ther embodiments of the blending _ L~ _ L 2 ~ ~
appar-atus are illustrated in the drawings supplemented by illus-tra-tive manufac-turing facility schematic flow charts, and graphs concern-ing the working r-ange of droplet size and travel, wherein:
Figure 1 is a schematic flow char-t of a composite wood pro-duct manufacturing facility indicating where the blending apparatus and method are utilized with respect to -the order of the overall.
apparatus and method;
Figure 2 is a graph illustrating the desirable working range in respec-t to -the size and travel of the droplets of -the l.i~uids, such as resin binders and wax emulsions;
Figures 3 and 4 are cross sectional views illustrating the me-thod and apparatus with respect to the ro-tary lifting of the par-ticles, followed by their free falling in an arcuate cascade, with a spray of drople-ts originating from a cen-tral area of -the overall motion pa-th of the particles, also showing differen-t interior surface configurations o:F -the drums;
Figure 5 is an isome-tric view of a pre:Ferred embodimen-t of -the b:Lending apparatus, i.e. the blender, wi-th por-tions removed for i]lustrating the interior of the drum, and the arrangemen-t on the shaf-t and the multiple discs;
Figure 6 is a side view of another embodiment of the blender illus-trating a -tapered drum and also showing -the entry and exit for -the par-ticles;
Figure 7 i.s a side view of another embodimen-t of the blender illus-trating a three section drum, with each sec-tion being of a differen-t diameter and having a respec-tive drive assembly opera-ting a-t a differen-t ro-tating speed, and also showing the entry and exi-t for -the par-ticles;
Figure 8 is a pa:r-tial. longi-tudinal cross sec-tional view -taken near -the en-try end of -the blender showing -the long ro-ta-ting ~ 3 ~
shaft that carries spray discs illustrating the supply and s-tarting distribu-tion o:F both a resin binder and a wax emulsion;
Figure 9 is a par-tial -transverse cross sectional view show-ing the starting dis-tribu-tion of -the wax emulsion, with this view being taken along line 9-9 of Figure 8;
Figure 10 is a partial -transverse cross sec-tional view showing the starting distribution of the resin binder, with this view being taken along line 10-10 of Figure 8;
Figure 11 is a partial transverse cross sectional view show-ing -the s-tarting distribution of both the resin binder and wax emulsion wi-th -this view being -taken along line 11-11 of Figure 8; and Figure 12 is a partial longitudinal cross sectional view illus-tra-ting how a liquid, either the wax emulsion or -the resin binder, is dis-tributed -to -the ou-ter periphery, i.e. the rim, of -the rotating, sligh-tly conical, disc, for depar-ture in a spray of droplets enrou-te to dispersion on -the su-rfaces of -the particles.
DESCRIPTION OF THE INVENTION
-One Environmen-t oE Where the Blending Me-thod and Blender are Utilized The preferred embodiment o~ -this inven-tion is described in reference -to its u~tilization in a manufacturing process wherein wood par-ticles are formed and pressed in-to wood products. In Figure 1 the overall me-thod s-teps and rela-ted apparatus of such a manufac-turing process are illustrated in char-t form. Logs are debarked and cut to length 10; ho-t soaked 11; flakes or other particles are made 12; they are dried 14; and as necessary the dried flakes are s-tored in a bunker 16, for subsequent processing. These inven-tions, i.e. both a blending me-thod and a blender 18, are used in the nex-t step of -the overall process, wherein -the par-ticles are efficien-tly, economically, and uni~orm:ly -treated in -the b:Lender being sprayed wi-th drople-ts of resin binder and/or wax emulsions. The -trea-tecl par-tic:les are, if necessary, 2 4 ~
s-tored in a bunker 20; then formed 22 in ma-t; ho-t pressed 24, adjusted for moisture content in a humidifier 26; trimmed by saws 28; stored, as necessary in a warehouse 30; and shipped 32 upon an order of a customer.
Preferred Liquid Drople-ts Sizes and Their Travel in Reference to Their Creation and to Their Dispersion, Reference to a Disc Spraying Theory In the practice of this method and the ar-rangemen-t and opera-tion of the apparatus, -the crea-tion of the liquid droplets in all r-espects, and especially in reference to their si~es and travel, is very important. Also, as discussed subsequently, the movemen-t of the particles to receive the dispersed droplets is likewise very impor-tant.
In reference to a disc spraying theory, -the production of sprays and mis-ts by means of spinning discs, is believed to have been first investigated experimen-tally and -theore-tically by Messrs. Walton and Prewet-t and later in more de-tail by Mr. Drummond. These earlier experimen-ts may have per-tained -to spinning discs used commercially to spray insecticides and paints; however -the observa-tions are deemed pertinent to understanding why and how rotating, i.e., spinning, discs are used in -the method and blender of this inven-tion.
The forma-tion of drops leaving from the edge of a spinning dics is analogous in many ways to drop forma-tion leaving from a sta-tionary -tip. Liquid flows -to the edge of -the disc and accumula-tes until the centrifugal force on the collected mass is greater -than the re-taining forces due to surface tension, and then -the drop is thrown off. Thus, it is reasonable -to expect -the produc-t of the surface tension and linear dimension of the drop to -the propor-tional -to -the cen-trifugal force.
In symbols: (~d3 p ) ( w2 D ~ ~ Td or rearranging ( 6 ) ( 2 ~ ~ 6~245 dw (TP) = constant where d = drop diame-ter T - liquid surface tension p = liquid specific D = disc diameter gravity w = disc angular velocity Extensive experiments by Messrs. Wal-ton and Prewett resulted in an average value for the constant of 3.8, wi-th a range of 2.67 to 6.55. Their experimen-ts also showed, the sharpness or edge profile of the disc was of minor importance. In the range of viscosity investigated, 0.01 to 15 poise, viscosi-ty had lit-tle effect on tne spraying process, although high viscosi-ty did tend to reduce the maximum flow ra-te a-t which homoegenous drops are formed. At small drop sizes, the drops or drople-ts become airborne, forming a mis-t.
Mr. Drummond presented his experimental resul-ts showing the effec-ts of flow ra-te Q, kinema-tic viscosi-ty u, and spin rate w, on the drop size d and ra-te of drop produc-tion. Drop volume is shown to exceed the volume predic-ted by Messrs. Wal-ton and Prewe-tt's sta-tic model, indica-ting that -the dynamics of drop forma-tion mus-t be included in the model.
In -the course of perfecting this invention a number of exper-iments were conducted in which a paper -tape was exposed to the spray pa-t-tern for a short in-terval, thus recording -the droplet size distri-bu-tion and spray pattern. Bo-th water and high viscosity liquid phenol formaldehyde resin were used. U-tilizing equation, and -the following parame-ters: D = 250 mm, w = 53L~ radians/second, T = 7.3 dyne/mm, and p = 1.1, -the theore-tical drop size was predicted a-t 0.12 mm as compared -to experimen-tal values of 0.20 to 0.30 mm. This agreement was con-siclered sa-tisfac-tory, and i-t was no-ted -the drops inevi-tably -tend to spread ou-t, ra-ther than retain -their spherical shape upon reaching a surface of a par-ticle -to be -trea-ted.
~ 3 6 ~
In Figure 2, the liquid droplet size and travel are illus-tra-ted in a graph to indicate the working range selected in reference -to the method and operation of the blender of this inven-tion. The drople-t size graph line has a y ordina-te regarding size expressed in microns and an x ordina-te regarding centrifugal force expressed in multiples of the gravitational force. The drople-t size graph line has a y ordinate regarding dis-tance to -travel in centimeters and an x ordinate regarding centrifugal force expressed in multiples of the gravi-ta-tional force. The droplet size range is from approximately 200 -to 50 microns and the droplet travel range is from about 90 cm to 20 cm depending on liquid proper-ties and gravi-ty force multiples at the spray disc rim.
Thus, volume per drop may range from 4200 x 103 cubic microns to 65 x 103 cubic microns, i.e. a 64 fold range in drop size.
The Con-trolled Movemen-t of Particles as They are Being Trea-ted wi-th -the Sprayed Liquids, Commencing with Ro-tary Lifting and Then at a Zeni-th Locale Free Falling at an Arcuate Cascade, Wi-th the Spray Coming from Spinning Discs Located on -the Central Area Defined by the Overall Movement Path of -the Particles In Figures 3 and 4, -the contr-olled movemen-t of par-ticles 13 is illustra-ted as viewed in a -transverse sec-tion -taken -through a rotating drum 17 of a blender 18. The drum 17 rotates in a clockwise rotational direction on bearings 15 mounted on an adjus-table frame 19, shown in par-t. In a central area 21 or volume of the interior of the drum 17 -there are spaced ro-tating, i.e. spinning, discs 52 which create the spray of drople-ts of liquids such as resin binders or wax emulsions.
The interior walls 23 of -the drum 17 are coated with a plas-tic finish so -the par-ticles 13 will not adhere to -these in-terior wall surfaces. Also even-tually when cleaning becomes necessary, the plastic covered walls are readily cleaned. Thereforel as viewed in Figures 3 and ~, longi--tudinal ribs 25 or raised portions 27, i.e. lands and grooves are u-tilized in assis-ting iTI -the ro-tary lif-ting of -the par-ticles 13 -to compensa-te when necessary for -the effec-ts of -the plas-tic finish. They _ g_ insure -the radial in-termixing of the par-ticles as -they traverse the blender.
As illustrated in bo-th Figures 3 and 4, the particles 13 are rotary lifted while positioned adjacent -to the interior wall 23 of the drum, un-til gravitational forces become effec-tive in causing the particles 13 to freely fall in an arcuate cascade un-til reaching again the interior wall 23 to begin ano-ther cycle. Each respec-tive spinning disc is located, in reference to a par-ticular -transverse cross sectional view, within -the central area defined by the overall movement of the collective particles 13. As observed in Figures 3 and ~ the sprayed droplets 29 reach the particles without any appreciable amount of them escaping on through to unwantedly contact the in-terior wall 23 of the blender 18.
The Addi-tional Controlled Movemen-t of -the Par-ticles Under Trea-tment to Move them on Through the Blender While Being Sprayed wi-th Liquids and Reference to Speed Changes at -the Circumference of the Interior of the Drum In Figures 5, 6, and 7, -the longi-tudinal observations indi-ca-te -the drum 17 of -the blender 18, in various embod;men-ts, always ro-tates abou-t a near horizon-tal axis, with the entry end receiving -the particles 13 being higher than the exit end discharging the particles 13. The reten-tion -time of the par-ticles 13 in -the blender 18 is con--trollable by adjus-ting the angle of inclination of the blender in respect to its near horizon-tal axis. Generally depending on the inclina-tion angle the par-ticles make from twenty -to forty revolutions while being -treated in the blender 18. For example in a ten foot diame-ter blender twen-ty fee-t long a one minu-te re-ten-tion time, when -the drum 17 is ro-ta-ting at twenty five revolu-tions per minute, requires an inclina-tion angle of about four and one half degrees.
In reference -to -the ro-ta-tional speed of -the drum 17 of a blender 18, under some circumstances, as wood wafers, for example, ~ 3 ~4~
acquired resin binder on -their surfaces the drum speed preferably has to be gradually decreased -to achieve -the most desirable cascading free falling ac-tion of the particles 13. Therefore, in reference to -the entire length of a drum 7, and realizing as the particles progress from the en-try -to the exit they gain in their receipt of resin binder, -the peripheral or circumferential speed is automatically reduced by utilizing a -tapered drum 33 as illustrated in Figure 6. Or a sectional drum 34 is used as shown in Figure 7 for a mu1ti-stage operation wi-th the telescoping sections 35, 36, 37 being opera-ted at different rotational speeds so their respec-tive peripheral or circumferential speeds may be reduced as necessary.
The Arrangement of the Componen-ts of the Blender as Illus-trated in E'igure 5 The blender 18 illus-tra-ted in Figure 5, has a drum 17 of constant outside diameter. As necessary -the in-terior diame-ter changed by -the addi-tion of prperly sized liners, not shown, to accommodate -the possible need for a reduc-tion in the peripheral speed, i.e. speed a-t -the circumference of -the in-terior. The overall suppor-ting frame 19 is adjustable to change the retention time of -the particles 13 within the drum 17. A-t the exit end -there is a pivota] frame mounting 38 and at the forward end there is a level changing frame mounting 39.
Such angular adjus-tment of frame lg likewise adjus-ts the en-tire compo-nents of the blender 18 through -the small angle of inclina-tion.
A motor 40, via a power transmission bel-t ro-tates ahft 42.
Spray discs 52, 53, 54, 55, 56 and 57 are mounted a-t spaced intervals a]ong large diame-ter -tubular shaf-t 42 and their spinning speed is controlled by opera-ting mo-tor 40.
An adjus-table speed mo-tor 43, via a power -transmission bel-t of change 44, drives a line shaft 45 moun-ted on bearings 46 secured -to :Frame 19. Near -the ends of shaf-t 45 are fric-tiona:L drive wheels 47 which ro-tate within circumferen-tial track channels or rails 48 secured around -the drum 17, thereby rotating the drum 17 in a clock-wise direction, as indicated by the motion arrow in Figure 5.
The Arrangement of -the Components of the Blender as Illustrated in Figure 6, and the Entry and Exi-t of -the Par-ticles The blender 18 illus-tra-ted in Figure 6, has a tapered drum 33 which serves to automa-tically reduce the peripheral speed, i.e.
speed at the circumference of the in-terior, -to compensa-te for -the particles nearing the exit which have changed in dynamic behavior in respect to their adhering resin binder droplets 29. The angular adjustments of the horizontal inclination of the drum 33 are similar to those indica-ted in Figure 5. Also the power transmissions respec-tively -to both the shaft 42 and the tapered drum 33 are similar to -those described in regard -to -the blender 17 shown in Figure 5. As is also true~ bu-t not shown in Figure 5, the particles 13 are illustrated in Figure 6, being delivered via a loading conveyor 49 and direc-ted into a loading chute 50 secured to -the non-rota-ting entry end enclo-sure 51. After passage through -their various advancing cycles within -the drum 17, -the particles :L3 with -their accumulated resin binder leave the drum 33 via the exi-t chute 58 positioned by the non-rotating exit end enclosure 59 and then they drop onto the discharge conveyor 60.
The Arrangement of the Components of the Blender as Illus-trated in Figure 7 and the Entry and Exit of -the Particles The blender 18 is illustrated in Figure 7, has a sectional drum 34 having three sections 35, 36, and 37 increasing in diameter and -telescoping. Many of the componen-ts are siMilar to -those illustra-ted in Figures 5 and 6 and are indicated by like numerals. Each sec-tion 35, 36 and 37 is driven a-t a different speed so the peripheral speed, i.e. speed a-t -the circumference of -the respec-tive -three different diame-ter interiors may be independen-tly con-trolled decreasing 2 ~ ~
in speed f-rom -the en-try -to -the exi-t of -the sectional drum. This speed reduction is under-taken -to accommoda-te -the par-ticles receiving -the resin binde-r which a-t -the slower speed will -then commence -their free fall in -the cascade a-t -the proper zeni.-th locale on -the respective in-teriors oF -the drum sections 35, 36 and 37. The power being dis-tri-bu-ted by the line shaf-t ~5 is dis-tributed via -three -transmission bel-t or chain assemblies 6:1., 62, 63 -to respec-tive secondary power distri-bu-tion shaf-ts 64, 65, 66 a-t -the respec-tive drum sec-tions 35, 36 and 37.
The drive whee:Ls ~7 Follow channels or rails ~8.
The Dis-tribu-tion and Supply o:E -the Liquids, For Example, the Resin Binders and Wax Emulsions, -to -the Spinning or Rotating Discs Which Crea-te -the Spray of Drople-ts I:n :Figures 6, 8, 9, 10, 11~ and 12, -the distribution and supply of -the liquids, i.e. resin binder R and wax emulsion W, to the spinning discs, such as disc 52, are i.l.lus-tra-ted. ~s shown in Figures 6 and 8, concen-tric s-ta-tionary supply -tubes 67 and 63, respectively receive -t'he resin binde:r R and the wax emuls.iorl W, received -through hoses 69 and 70 being fed by pUlllpS 71 and 72 from conve:n-tional supp:Ly sources of each which are no-t shown. Thereaf-ter -the resin binder R
and the wax emulsion W, af-ter directional changes shown in Figure 8 leave -the s-ta-tionary supply -tubes 67 and 68. These liquids leave -through downwa:rd poin-ting s-tub ~tubes 73, 7~, which have exit holes 75 direc-ted -to nearby pla-tes 76 and 77 which are :ro-tating rapidly with -the shaf-t ~i2.
Bearing '78 is used in posi-tioning -the stationary supply -tubes 67 and 68 rela-tive -to -these por-tions, inclusive of pla-tes 76 and 77, which are ro-ta-ting wi-th -the sha:F-t ~2. Bearing 79 is used -to posi--tion the :ro-ta-t:ing s'ha~-t re:La-ti,ve -to ~the frame 19 of -the blender 13.
The resin binder R and the wax emulsion W, respec-tively upon 3n :Leaving exi,-t holes 75 t:ravel throug}l space un-til. reachi:ng pla-tes 76 al-ld 7'7. T~le:reclf-ter cerxtr:i.:Fuga~ or:~ce moves l,he ~I.;quids :radia:l.ly outwardly -to -the inner wall 80 of a cylindrical sec-tion 81. Pla-te 82, installed with the aid of grooves 108 and sealing rings 109 similarly -to the ins-tallation of pla-te 76 serves -to keep the resin binder R and wax emulsion W separated -throughou-t -the opera~tions as -these liquids from the respec-tive rota-ting shallow toroidal pools 83, 84. Continu-ously during operations, -the liquids depart from -these supply pools 83, 84 and enter respective dis-tribution -tubes 85, 86, 87, 88, 89, and 90, which longitudinally distribute the resin blender R and wax emul-si.on W to spinning discs 52, 53, and 54 being supplied from -the entry end of the blender 18. Spinning discs 55, 56 and 57 are supplied in like manner from the exit end of -the blender 18. These dis-tribu-tion -tubes are located within the protec-tive longitudinal cylindrical shaft 91 secured by fas-teners 93, af-ter being posi-tioned in plate 92 which also seals off the liquids :F:rom -the interiors of the shaft associated componen-ts such as tubular shaft 91. The cross sec-tional views of Figures 9, 10 and 11 Fur-ther illustrate -the dis-tribution of liquids R
and W.
In Figure 1.2 distribution of liquid resin binder ~ to a spinning disc 53 is shown. This liquid is directed through conduits 85 and 89~ then caused -to change direc-tion into stub tubes 94, 95 and discharged in-to a first shallow -toroidal supply pool 96. Af-ter reach-ing a pre-se-t level, -the liquid is longitudinally drained in-to a larger shallow toroidal pool 97 via a series of annular holes 98 in a dividing par-tial bulkhead, flange, or annular orifice :ring 99. Thereafte:r in an adher-ing ou-twardly flow path 100~ -the liquid moves -to -the rim 101 of -the spinning disc 52. The flow of liquid in pa-th 1.00 uni.formly ex-tends -throughou-t the circular conical surface area of -the disc 52 -to even-tuall.y con-tinuous:Ly depar-t in a spray o:F drople-ts 29. The peri-me-ter speed o:F disc 52 is abou-t four-teen -thousand Eee-t a minu-te for a disc 20 inches in diame-ter~ Circu:lar- pla-te :L03 secured by fas-teners ~ 3 ~3~ 2~ 5 104 shields the f]ow path 100 of liquid from wind and dust. Fasteners 105 secure the disc assembly 106 to the tubular shaf-t 91. Fas~teners 107 secure the disc to the disc assembly 106.
Though six spinning discs are illus-trated in Figure 5, i-t is feasible -to use as few as two or up to -twelve depending on the capa-city requiremen-ts. The effective spray travel, as indicated in Figure 2 is governed by -the size of the drople-t and disc speed. A-t a cons-tant G factor, for example, of 2000, the spray -torus diameter is changed rela-tively little in size, whether the disc is -ten inches or -twenty inches in diameter.
Information Concerning the Design Considerations in Respect to a Selected Shaft on Which -the Spinning Discs are Mounted The natural resonan-t frequency of a long, rotating shaft de-termines limi-ts on sha:Ft size, speed and span between bearings.
The applicable formula for this embodiment is:
N = 69~ ~ Where: N = natural frequency in V - 8 circles per second E = shaE-t modulus o:F elas-tici-ty: for s-teel - 29,000,000 psi I = moment of inertia of shaft (Inch4) ~0 W = total weight between bearings (Lbs) L = span between bearings (inches) For a 12 inch steel shaf-t wi-th a 0.50 wall thickness with a span of 18 ft. between bearings carrying six twenty inch diameter discs -the natural frequency speed is about 3,500 RPM. To at-tain 2,000 times gravi-ty force a-t disc rim requires abou-t 2,650 RPM. This operating speed provides a wide safety margin below cri-tical resonant speed.
Information Concerning Design Considera-tions in Respect to Drum Speeds as They eEfect -the Peripheral Speed, i.e. ~the Speed a-t the Circumference of -the Interior of -the Drum In pilo-t scale -testing using a 94.5 inch diame-ter drum, dry wood wafers, i.e. zero percen-t resin binder, had -the op-timum free 2 ~ ~
falling arcuate cascading action a-t twenty eight and three -tenths revolutions per minute. This op-timum speed decreased, in an exponen-tial fashion, to twen-ty six and -thir-ty -three hundredths revolutions per minute at a six percent resin binder content.
If the ~ree falling arcuate cascading action is not properly maintained, an unwanted loosely compac-ted layer of wood wafer, i.e.
particles, wi-th their resin binder, may form within the drum. This layer could periodically disintegrate and cause opera-tional control problems. However, if the drum is too slow, the wafers start falling pr-ematurely and may fall directly onto long tubular shaf-t and spinning discs, thus degrading quali-ty of resin distribu-tion while allowing resin to reach inner wall of -the drum.
~ .
Claims (25)
1. A blender used to efficiently and uniformly apply finely dispersed liquid droplets upon the surfaces of particulate materials comprising:
(a) a hollow drum rotatably supported on a frame to rotate essentially about a horizontal axis to provide an upwardly moving inner wall and a downwardly moving inner wall;
(b) a particulate material receiving assembly at one end of the rotatable hollow drum;, (c) a particulate material discharging assembly at the other end of the rotatable hollow drum;
(d) a high-speed rotating spray assembly means for producing a circular spray of small droplets which travel outwardly therefrom toward the outer periphery of the drum and is disposed within the upper quadrant of the drum which, such quadrant including the upper portion of the upwardly moving inner drum wall;
(e) power drive assembly means for rotating the hollow drum at a speed which produces a relatively uniform thin layer of lifted particulate material along the upwardly moving drum wall and a free-falling cascade of particulate material which separates from the drum wall shortly before reaching the uppermost point and falls to the bottom of the drum again to be lifted for subsequent free-falls until discharged from the drum;
(f) the free-falling cascade forming a curtain which is disposed between the rotating spray assembly and the downwardly moving inner wall of the hollow drum for intercepting the droplets and completing formation of a closed hollow zone substantially free of particles within the central part of the drum and within which the rotating spray assembly is substantially centrally located; and (g) a power drive assembly connected to the high-speed rotating spray assembly means for producing rotation thereof at a selected speed which will produce an outwardly moving spray of small droplets which will impinge on and coat the particulate material.
(a) a hollow drum rotatably supported on a frame to rotate essentially about a horizontal axis to provide an upwardly moving inner wall and a downwardly moving inner wall;
(b) a particulate material receiving assembly at one end of the rotatable hollow drum;, (c) a particulate material discharging assembly at the other end of the rotatable hollow drum;
(d) a high-speed rotating spray assembly means for producing a circular spray of small droplets which travel outwardly therefrom toward the outer periphery of the drum and is disposed within the upper quadrant of the drum which, such quadrant including the upper portion of the upwardly moving inner drum wall;
(e) power drive assembly means for rotating the hollow drum at a speed which produces a relatively uniform thin layer of lifted particulate material along the upwardly moving drum wall and a free-falling cascade of particulate material which separates from the drum wall shortly before reaching the uppermost point and falls to the bottom of the drum again to be lifted for subsequent free-falls until discharged from the drum;
(f) the free-falling cascade forming a curtain which is disposed between the rotating spray assembly and the downwardly moving inner wall of the hollow drum for intercepting the droplets and completing formation of a closed hollow zone substantially free of particles within the central part of the drum and within which the rotating spray assembly is substantially centrally located; and (g) a power drive assembly connected to the high-speed rotating spray assembly means for producing rotation thereof at a selected speed which will produce an outwardly moving spray of small droplets which will impinge on and coat the particulate material.
2. The blender as set forth in claim 1, wherein: the diameter of the drum is dependent upon droplet travel velocity produced by the spray assembly and the distance of the inner wall of the hollow drum being from 50 to 130 centimeters from the periphery of the spray assembly.
3. The blender as set forth in claim 2, wherein: the diameter of the drum can vary from 4 to 10 feet.
4. The blender as set forth in claim 2, wherein: the spray assembly means includes at least one rotating circular spray disc which is mounted on a supporting hollow shaft which extends axially into the drum and through which spray material is supplied.
5. The blender as set forth in claim 4, wherein: the diameter of the drum is dependent upon the droplet travel distance from the spray assembly, and droplet size and travel distance is governed by spray assembly perimeter centrifugal force which is within the range of from 1,500 to 5,000 G force, and droplet size is given by the equation
6. The blender as set forth in claim 4, wherein: the periphery of the disc is from 50 to 130 centimeters and the diameter of the disc is from 4 to 30 inches.
7. The blender as set forth in claim 1, wherein: the drum diameter is progressively reduced from the feed input depending upon cohesion behavior of the treated material as it moves progressively from the larger diameter end of the drum to the smaller diameter output of the drum.
8. The blender as set forth in claim 1, wherein: the drum is rotatably supported on a frame and has its interior surfaces arranged in adjacent contiguous independently revolvable sections which are individually adjustable to create successively different interior surface speeds between adjacent sections to compensate for change in cohesive and frictional properties of the particulate material as it progresses through the drum in multiple lift and free-fall cycles.
9. A blender as claimed in claim 1 comprising, in addi-tion, an adjustable frame to rotatably support the hollow drum at selective angles from a horizontal axis.
10. A blender as claimed in claim 1 wherein additional disc sprayers are mounted to rotate with the hollow shaft.
11. A blender as claimed in claim 10, wherein the liquid supply assembly delivers the liquid through the hollow shaft and then on to all the respective sides of the disc sprayers.
12. A blender as claimed in claim 11, wherein the hollow shaft on which the disc sprayers are mounted is positioned within one upper transverse quadrant of the drum.
13. A blender as claimed in claim 12, wherein the drum is specifically rotated at a speed to lift the particulate wood material along the interior surface of the drum to an upper zenith locale within the drum, where the gravitational force becomes effective to cause the particulate wood material to freely fall in a cascade down to the interior surface of the drum, again to be lifted for subsequent free falls until discharged from the hollow drum.
14. A blender as claimed in claim 13, wherein the drum is rotated at a selected angle relative to the horizontal plane and at a selected speed to create a selected number of adjacent cycles, wherein in each cycle some of the particulate wood material is lifted along the interior surface of the hollow drum to an upper zenith locale within the hollow drum, where the gravitational force becomes effective to cause the particles to freely fall in a cascade down to the interior surface of the drum, wherein at substantially all times the particulate wood material is intercepting all of the dispersed liquid droplets, so the droplets do not reach the interior of the hollow drum, nor drop down on the spray discs.
15. A blender as claimed in claim 12 wherein the hollow drum includes means to selectively reduce the peripheral speed at the interior surface of the hollow drum at selective longitudinal places along the hollow drum to create a selected number of adjacent cycles wherein in each cycle some of the particulate wood material is lifted along the interior surface of the hollow drum to an upper zenith locale within the hollow drum, where the gravitational force becomes effective to cause the particles to freely fall in a cascade down to the interior surface of the hollow drum.
16. A blender as claimed in claim 1 wherein the hollow drum is tapered from a larger inside diameter where the particulate wood material is received to a smaller inside diameter where the particulate wood material is discharged, to compensate for changing cohesive and friction properties of the particulate wood materials as they progress through the hollow drum going through multiple lift and free fall cycles.
17. A blender as claimed in claim 1 wherein the hollow drum has telescoping separately rotatable sections rotated at selected speeds to compensate for changing cohesive frictional properties of the particulate wood materials as they progress through the hollow drum going through multiple lift and free fall cycles.
18. A blender as claimed in claim 10 wherein the hollow shaft on which the spray discs are mounted is positioned within one upper transverse quadrant of the hollow drum and the hollow drum is rotated at a selected angle relative to the horizontal plane and a selected speed to create a selected number of cycles, wherein each cycle, some of the particulate wood materials are lifted along the interior surface of the hollow drum to an upper zenith locale within the hollow drum, where the gravitational force becomes effective to cause the particulate wood materials to freely fall in an arcuate cascade down to the interior surface of the hollow drum.
19. A blender as claimed in claim 18 wherein the hollow drum includes means to selectively reduce the peripheral speed at the interior surface of the hollow drum at selective longitudinal places along the hollow drum, to compensate for changing cohesive and frictional properties of the particulate wood material, and thereby maintaining the uniform cascading of the particulate wood material.
20. A blender as claimed in claim 19 wherein the liquid supply assembly supplies two different liquids with some spray discs receiving one liquid and other spray discs receiving the other liquid.
21. A blender as claimed in claim 4, wherein the drive assembly to rotate the hollow drum rotates in one direction, and power assembly to operate the hollow shaft rotates in the other direction.
22. A blender as claimed in claim 18 wherein shields are mounted adjacent to the sides of the disc sprayers to protect the liquid film from wind and dust prior to their leaving the disc sprayers.
23. A blender used to efficiently apply finely dispersed liquid droplets of resins and/or waxes spaced throughout surfaces of particles of wood materials, comprising:
(a) a hollow drum to be rotatably supported on a frame and having its interior surfaces arranged in adjacent sections which are adjustable to create different interior surface speeds to compensate for changing cohesive and frictional properties of the particles of wood materials, as they progress through the hollow drum going through multiple lift and free fall cycles;
(b) an adjustable frame to rotatably support the hollow drum at selective angles from a horizontal position to angles from a horizontal axis;
(c) a receiving assembly for particles of wood material at one end of the rotatable hollow drum;
(d) a discharging assembly for particles of wood materials at the other end of the rotatable hollow drum;
(e) a large diameter rotatable hollow shaft positioned longitudinally within the rotatable hollow drum throughout an upper transverse quadrant of the hollow drum and adjustable from a hori-zontal position to angles from a horizontal axis;
(f) spray discs spaced and mounted on the hollow longitudinal shaft to rotate with the hollow shaft, each spray disc to receive a respective liquid on a respective side, and each spray disc having a respective spaced shield to protect the liquid on the respective side of each spray disc from wind and dust prior to the liquid leaving the respective spray disc in dispersed droplets;
(g) liquid supply assemblies to deliver liquid resins and/or waxes through the rotatable hollow shaft to the respective spray discs;
(h) a power assembly to rotate the hollow shaft at selective optimum speeds;
(i) a variable speed drive assembly to rotate the hollow drum at selectable optimum speeds to produce side by side free falling cascades of particles of wood materials intermediate between spray discs and downwardly moving inner walls of the hollow drum throughout the adjacent sections along the interior of the hollow drum, and to produce side by side returning lifts of particles of wood on the moving inner hollow drum surfaces, whereby the finely dispersed liquid droplets essentially always first reach the surfaces of the particles of wood materials and do not directly reach the inner surfaces of the rotating drum.
(a) a hollow drum to be rotatably supported on a frame and having its interior surfaces arranged in adjacent sections which are adjustable to create different interior surface speeds to compensate for changing cohesive and frictional properties of the particles of wood materials, as they progress through the hollow drum going through multiple lift and free fall cycles;
(b) an adjustable frame to rotatably support the hollow drum at selective angles from a horizontal position to angles from a horizontal axis;
(c) a receiving assembly for particles of wood material at one end of the rotatable hollow drum;
(d) a discharging assembly for particles of wood materials at the other end of the rotatable hollow drum;
(e) a large diameter rotatable hollow shaft positioned longitudinally within the rotatable hollow drum throughout an upper transverse quadrant of the hollow drum and adjustable from a hori-zontal position to angles from a horizontal axis;
(f) spray discs spaced and mounted on the hollow longitudinal shaft to rotate with the hollow shaft, each spray disc to receive a respective liquid on a respective side, and each spray disc having a respective spaced shield to protect the liquid on the respective side of each spray disc from wind and dust prior to the liquid leaving the respective spray disc in dispersed droplets;
(g) liquid supply assemblies to deliver liquid resins and/or waxes through the rotatable hollow shaft to the respective spray discs;
(h) a power assembly to rotate the hollow shaft at selective optimum speeds;
(i) a variable speed drive assembly to rotate the hollow drum at selectable optimum speeds to produce side by side free falling cascades of particles of wood materials intermediate between spray discs and downwardly moving inner walls of the hollow drum throughout the adjacent sections along the interior of the hollow drum, and to produce side by side returning lifts of particles of wood on the moving inner hollow drum surfaces, whereby the finely dispersed liquid droplets essentially always first reach the surfaces of the particles of wood materials and do not directly reach the inner surfaces of the rotating drum.
24. A blender as claimed in claim 23 wherein the hollow drum is rotatable in one direction, and the hollow shaft is rotatable in the other direction.
25. A blender as claimed in claims 23 or 24 wherein each spray disc is slightly dished.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US20830780A | 1980-11-19 | 1980-11-19 | |
| US208,307 | 1980-11-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1161245A true CA1161245A (en) | 1984-01-31 |
Family
ID=22774104
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000390315A Expired CA1161245A (en) | 1980-11-19 | 1981-11-18 | Method of spraying liquids on the surfaces of particles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1161245A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101879488A (en) * | 2010-07-07 | 2010-11-10 | 句容市三圆制桶有限公司 | Integral automatic inner spray coating device for steel barrel bottom, cover and barrel frame |
-
1981
- 1981-11-18 CA CA000390315A patent/CA1161245A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101879488A (en) * | 2010-07-07 | 2010-11-10 | 句容市三圆制桶有限公司 | Integral automatic inner spray coating device for steel barrel bottom, cover and barrel frame |
| CN101879488B (en) * | 2010-07-07 | 2012-01-18 | 句容市三圆制桶有限公司 | Integral automatic inner spray coating device for steel barrel bottom, cover and barrel frame |
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