US2630310A

US2630310A - Apparatus for processing fusible materials

Info

Publication number: US2630310A
Application number: US642766A
Authority: US
Inventors: Norman P Harshberger
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-01-22
Filing date: 1946-01-22
Publication date: 1953-03-03
Anticipated expiration: 1970-03-03

Description

March 3, 1953 N. P. HARSHBERGIER APPARATUS FOR PROCESSING FUSIBLE. MATERIALS Filed Jan. 22, 1946 4 Sheets-Sheet l INVENTOR Norman P. Hers/Merger BY W4? Azfornc gs.

N. P. HARSHBERGER APPARATUS FOR PROCESSING FUSIBLE MATERIALS March 3, 1953 '4 Sheets-Sheet 2 Filed Jan. 22, 1946 INVENTOR Norman R Harsh ber ger BY WW5:-

Attorreys.

N. P. HARSHBERGER APPARATUS FOR PROCESSING FUSIBLE MATERIALS Map-ch 3, 1953 4 Sheets-Sheet 3 Filed Jan. 22, 1946 INVENTOI? Norman R liarsllbcrger W A- Attorneys.

March 3, 1953 N. P. HARSHBERGER APPARATUS FOR PROCESSING FUSIBLEI MATERIALS 4 Sheets-Sheet 4 Filed Jan. 22, 1946 INVENTOR Norman R Harslrbe BY A ttorneys.

Patented Mar. 3, 1953 UNITED STATES PATENT OFFICE APPARATUS FOR PRocEs si NG FUSIBLE MATERIALS Norman P. Harshberger, Pasadena, Calif.

Application January 22, 1946,- Serial No. 642,766

Claims.

flexible than the methods and machines of the prior art as to control of the characteristics of the treated product.

Another object of the invention is to provide a method of the stated character wherein the particles of the fusible material undergoing processing may be subjected while in suspension and in substantially positive dispersion to a constant heating at the fusing temperature for selectively predetermined periods, and further, to provide apparatus having provision for effecting such treatment of the particles.

Still another object of the invention is to provide a novel method and apparatus of the stated type wherein the particles of fusible materials in suspension are first fused and then automatically separated from the suspending medium.

A further object of the invention is to provide an apparatus of the stated class having novel means for preventing accretions of the fused particles on the walls of the combustion chamber, said means obviating necessity for maintaining the said walls at temperatures below the fusion point of said particles.

A still further object of the invention is to provide apparatus of the stated class wherein provision is made for varying the dimensions of the combustion chamber as a means 'for'regulating the conditions under which the treatment of the fusible particles takes place in accordance with the nature of the said particles and the desired characteristics of the end product.

The invention also contemplates the provision in the aforesaid apparatus of means for adequately cooling the working parts and for arranging and adjusting the burners as may be required to afford conditions of maximum efficiency.

The invention resides further in certain details of method and apparatus hereinafter set forth and illustrated in the attached drawings wherein:

Fig. 1 is an 'elevational view of an apparatus made in accordance with the invention;

Fig. :2 :is an enlarged vertical sectional view of the apparatus shown in Fig. '1;

Fig. :3 is an enlarged sectional view on the line 33 Fig. 2;

Fig. 4 is an :elevational view partlyin section illustrating a modified form of combustion chamber and clinker chaser;

Figs. 5 and 6 are vertical sectional views showing still different forms of clinker chaser;

Fig. 7 is a fragmentary sectional view illustrating another form of clinker-inhibiting means;

Figs. 8 and .9 are, respectively, fragmentary vertical cross-sectional and plan views of a desirable :form of combustion chamber :of sectional desigmand 1 Fig. 10 is a vertical sectional View of "still another form of apparatus embodying the invention.

With reference to Figs. .1, 2, and 3 of the drawings, the apparatus therein illustrated comprises an outer cylindrical casing l which is supported on and communicates at .its lower end with the interior of a casing 2, the latter casing containing a chamber 3 which receives the processed materials 'from'the casing I, as hereinafter more fully set forth, and comprising also .a suction duct 4 by means of which the said materials may be withdrawn from the chamber 3 to a remote ,point of discharge. Extending into thetop of the casing l is a duct 5, said duct being of smaller diameter than the casing so as to provide a chamber t between its own wall and that of the casing. The duct .5 is adjustable vertically with respect to the casing I so as to provide for variation and adjustment of the efiective length of the chamber 6 within the casingand in the present instance the duct is shown as provided with a rack 5a which is engaged by a pinion I mounted for manual actuation upon a fixed bracket -8.

A hopper 9 is supported at the top -:of the casing i for reception of the material which is to undergo processing, said material :being ground to particle form of a screen size, say of approximately 40 to mesh or finer, and these particles may be transferred from the hopper 9 to the upper end of the casing I and of the chamber 6 through the medium in the present instance of a screw conveyor ll, said screw being actuated by a motor l2 through the medium of a speed change unit l3.

Associated with the chamber 6 is a plurality of burner units arranged in the present instance in two series designated 14 and I5 respectively, and through these burners combustion gases are projected into the chamber 6 at high pressure and velocity, said burners being arranged tan-- gentially with respect to said chamber as illustrated in Fig. 3. The resulting high velocity cyclonic action of the combustion gases in the chamber 6 has the effect of positively dispersing the particles of solid material introduced as described above and of maintaining them in a state of suspension within the chamber 6 subject to the action of the burning gases at temperatures in excess of the fusion point of said particles. The velocity of the combustible gases introduced by way of the burners l4 and I5 is sufficiently high to maintain the particles in suspension in the chamber for a period permitting complete fusion of the particles, and during this operation the particles are difiused and scrubbed by the hot gases. The fused particles move generally in a downward direction and eventually pass from the lower end of the chamber 6 at which point they are separated from the gases, the latter being withdrawn upwardly through the stack 5. The particles continue their downward movement by gravity through the lower end of the casing l and are collected in the chamber 3, and from this chamber the product may be withdrawn through the duct 4 as previously set forth.

To augment the action of the swirling g-ases within the chamber 6 in dispersing the particles through the gas and to subject them to the fusion temperatures for the required period, the chamher 6 is provided with a spiral structure l6, said structure extending upwardly from the lower end of the casing around the duct 5 as best illustrated in Fig. 2. This structure is mounted for rotation about a vertical axis corresponding with the longitudinal center line of the chamber 6 so as to permit it to function not only for the purposes set forth above, but also as a means for precluding the formation on the walls of the combustion chamber 6 of clinker in the form of clusters of spherulized particles of glass. The spiral, in rotating, wipes the surfaces of the walls of the combustion chamber and thereby precludes clinker formation.

In order to preclude the formation of clinker on the spiral structure l6 itself, the latter is made of tubular form and means is provided for passing through the interior of said spiral tube a cooling agent such as air which will function to maintain the temperature of the structure sufficiently below the fusion temperature of the particles under treatment to discourage occlusion of the spherulized particles on the relatively cooled surface. Referring to Fig. 2, it will be noted that the structure I6 is supported at its lower end upon a shaft I1 and that this shaft is supported on anti-friction bearings l8 and i9 within a cylindrical sleeve 2|, said sleeve being supported in turn within a casing 22 in the lower end of the casing l. The lower end of the shaft I1 is provided with a bevel gear 23 which is operatively connected through a corresponding gear 24 with a shaft 25 which extends through the wall of the casing l and which is connected in the present instance through a suitable speed change unit 26, see Fig. 1, with a driving motor 27. The tubular structure l6 consists of an upward and a return spiral which are designated in Fig. 2 by the

reference numerals

28 and 29 respectively, the lower end of the upward run communicating with the interior of the sleeve 2! and the lower end of the return spiral 29 discharging at 31 against the wall of the casing I. Air is introduced to the interior of the sleeve 2! at a point about the bearing [8 through a duct 32 and this air after passing upwardly through the spiral 28 returning downwardly through the spiral 29 to the discharge point 3!. The air thus discharged against the inner surface of the wall of the casing I aids in discouraging the formation of clinker below the convolutions of the spiral structure Hi. The housing 22 is made liquid-tight so that suitable coolant may be circulated through the interior of thi housing by way of

ducts

33 and 34 for the purpose of maintaining the bearings i8 and the running portions of the transmission within the casing l at a reasonably low temperature.

In operation of the apparatus described above, the particles of material under processing are introduced into the top of the combustion chamber 6 and are immediately picked up by the combustion gases swirling with cyclonic action and at high velocity within the chamber. The action of these high velocity swirling gases effects an immediate dispersion of the particles in the combustion gases and subjects them simultaneously and thoroughly to the high fusion temperatures. The length of time to which the particles are thus subjected in the highly dispersed state to the action of the burning gases may be controlled by regulation of the velocities at which the combustion gases are introduced into the chamber 6 through the burners l4 and [5, by regulation of the effective length of the chamber 6 through longitudinal adjustment of the duct 5 in the casing l, and by regulation of the speed of rotation of the clinker chaser 16. Such regulation of the period of treatment of the said particles will depend upon the nature of the material under processing and the size of the said particles, it being noted that the heavier the particle, the higher the velocity of the burning gases required to maintain the particle in suspension. Obviously the particles will vary materially as to size, but since the velocity of the gases is a function in part of the presence under which the gases are introduced, and since the temperature of the combustion increases with the pressure, there is in the aforedescribed system an automatic compensation which insures efficient treatment of the variable particles. I have found in practice that a water column pressure between 20 and 40" with the proper proportion of gas and air thoroughly mixed produces favorable conditions for the processing of glass-like particles of 40 mesh and lower. It will be clear that the aforedescribed design meets the primary factor in furnaces adapted to expand and/or spherulize fusible particles as described, namely, the factor of setting up and maintaining a combination of conditions suited to the requirements of the product under process and of the end product.

I have found further that in a device operating as described above, the high centrifugal forces set up by the high velocity tangentially introduced combustion gas-es tends actually to prevent adherence of the fused particles to the walls of the furnace. This is due probably to the fact that while the centrifugal force tends to throw the particles toward and against the walls, there is apparently a cushion of air immediately adjoining the wall which prevents the intimate contact of the fused particles with the wall itself. By reason of this phenomenon I have found it possible to construct combustion chambers of alloy steel instead of the refractory materials previously considered necessary in apparatus of this general character. I have found it feasible further to maintain a temperature range within the furnace of between 1400 and 2400 F. with a velocity range of between 48 and 100' per second within which ranges the gases "and solid particles may readily be separated by the principle of cyclonic separation, particularly in a structure such as described above wherein the stack return pipe, constituted by the duct 5, may be lowered and raised as required to reduce or enlarge the combustion chamber area. By such adjustment the temperature of the furnace, the velocity of the gas flow, and the collection efliciency of the solid particles may be increased by a simple and rapid adjustmentof the combustion chamber area. In general I have found it desirable that the chamber size for proper combustion of 44,000 cu. fee-t of gas should be 29 cubic inches or more to maintain a temperature of approximately 1850" F., and with that size chamber, it is desirable, if not necessary, to maintain 32" water column pressure at the burner to eliminate back pressure.

Obviously, the area of the combustion chamber might be regulated by other .means than that described above, as for example by change in the diameter of the stack return duct 5, and

provision for such change may readily be incorporated in the apparatus if desired.

I have found further that in an apparatus of the aforedescribed type it is practicable and advantageous to employ silicon carbide or like material in the walls of the furnace in that avoids the tendency exhibited by all alloy metals to scale at a temperature of 2000 F., particularly where the flame itself is impinged against the surface of the material. My invention contemplates the use of such refractory liner in a cyclonic furnace of the type described either alone or with a cleaning device of the type of the clinker chaser herein described. Another advantage of the furnace liner such as silicon carbide is its high conductivity and resulting uniform distribution of heat conducted and radiated therefrom.

I have found also that there are material advantages in coating the particles of the material under processing with graphite. This may be accomplished by mixing with the pulverulent work material, say from 5% to by weight of pulverized or colloidal graphite. The graphite adhering to the work material aids as a lubricant in the flow of the particles of the material through the feeding device, and tends to prevent packing of the material in said device. The graphite coating also aids in dispersing the particles when they come in contact with the flame within the combustion chamber. Further, the graphite has little or no affinity for the refractory wall of the chamber, and aids materially in preventing adherence of the particles to the furnace wall when they reach the fusion temperature.

It is practicable to mix with finely ground work material, such for example as perlitic rock, varying percentages of lime, Portland cement, calcium aluminate cement, oxychloride cement, powdered clay, gypsum, or other cementing substance, and to then process the mixture in the aforedescribed furnace to produce a composition that may be set by combining with moisture and allowed to dry. Such compounds, combining low density spherulized particles of substantially silica to which adhere, under the influence of fusion tem- 6 :peratures, particles :of cement, afford a ready mixed product having unique flow properties as well as wetting properties not obtainable :in any of the ingredients wetted alone.

Short fibred asbestos of :low grade, .or longer fibre asbestos known to the trade .as Rhodesian blue, may also be mixed and readily processed with the work material as described to produce a loose fill material having non-settling characteristics. Any of the aforesaid combinations may readily be handled through the heating process described above and collected together for packaging.

Most of the fusible materials that are used in ceramics may be treated in accordance with my invention with the furnace adjusted in accordance with the characteristics of the particular material. In some cases it may be desirable to completely spherulize the particles, and, in other instances the temperature may be adjusted so that the particles are merely calcined, for the forming of a cement for example.

Some of the materials which may be heat treated to advantage, either alone or in combination, in apparatus constructed in accordance with my invention are as follows:

Pulverulent silica of substantially the following:

Percent Loss of ignition 2.16 Silica 73.72 Aluminum oxide (A1203) 1- 15.10 Iron oxide (F6203) 0.16 Titanium oxide (TiOz) 0.32 Calcium oxide (CaO) 0.88 Magnesium oxide (MgO) 0.69 Alkalis as sodium oxide (NazO) 6.76 Sulphuric anhydride (S03) 0*.01 Chloride (Cl) 0.06

This material is known as perlite and when it contains a sufficient percentage of combined water or water of crystallization, as the case may be, will expand many times its normal size, and under proper control will form hollow glass-like spherules of extremely low density. Thus, at a temperature around 2200 F. the material has produced a loose fill spherulized product weighing as little as 2 lbs. to the cubic foot (loose fill). Material having a similar formula and ground to mesh and finer may, before processing, be mixed with lime, Portland cement etc., as described above, to produce a cementitious compound of desirable characteristics.

Obsidian of the following formula will expand under heat treatment to many times its original volume, forming a multiplicity of nonint'ercommunicating cells:

Per cent H2O at 0' 0.34 Loss at red heat 0.16 S102 80.98 F9203 (A1203) 1 13.85 CaO 1.15 MgO 0.0 2

Such a material apparently expands as a result of releases of strains rather than from the influence of expanding water of crystallization. The expansion takes place when the fusion point of the material is reached.

Pitchstone, another form of obsidian, may also be treated to advantage in the hereindescribed furnace. This material, and the others, including perlite, which are particularly well suited for forming into low density insulation products, I

7 prefer to classify under the general term hydrosilicates."

Scoria, another form of volcanic material sometimes termed a form of pumice, is another material that is more suitably handled by my process than by others by reason of the high velocity gases retaining the material in suspension sufficiently long to bring the particles to the fusion point and to spherulize. This particular type of material may merely be spherulized rather than expanded and is particularly well suited as an aggregate in building materials, or as road bend markers because of its glass-like surface highly refractive under the influence of even small amounts of light.

In Fig. 4 I have illustrated a modified form of apparatus wherein the casing la, corresponding to the casing I of the previously described embodiment, tapers from the mid section towards both top and bottom. The clinker chaser in this case takes the form of pipe elements 35 which extend upwardly into the casing la from a support member 36 which is secured to the upper end of a rotary shaft 31. The elements 35 of which two are shown in the illustration, extend vertically upwardly to a point near the upper end of the combustion chamber and then downwardly along the inclined outer walls of the casing. The upward run 38 of the e ement 35 functions to keep the surface of the duct 5a free from clinker occlusions, and the downwardly extending portion 39 of the element 35 functions similarly with respect to the inner surface of the wall of the casing la. Means is provided for circulating a cooling fluid through the element 35, the fluid being introduced through a pipe 4| into the hollow interior of the member 36 and thence upwardly through the upper run 38 of the member 35 and downwardly through the downward run 39 to the lower end 42 of the latter, at which point it is discharged against the inner surface of the casing la adjacent the lower end of the latter.

In essential respects the device corresponds to that embodiment of the invention shown in Figs. 1, 2, and 3. It is to be noted, however, that by reason of the inverted conical shape of the lower portion of the casing l the opening between the lower end of the stack 5a and the casing wall becomes progressively smaller as the stack is lowered into said lower portion. This has the effect of restricting the outlet from the combustion chamber and correspondingly. increasing the velocity of the gases at that point. A highly efflcient separation of the solids from the gases results.

In Fig. 5 a somewhat different form of clinker chaser is employed. In this case the flue duct 5b does not extend into the casing lb but extends upwardly from the top of the latter. The clinker chaser takes the form of a hollow open-ended cylinder 43 which is reciprocated in the casing lb in proximity to the wall of the latter through the medium of a crank shaft 44 and connecting rod 45, said crank shaft extending through the wall of the casing lb and being connected to a suitable source of power through the medium in the present instance of a gear element 46.

In the embodiment shown in Fig. 6, the flue element 50, which corresponds to the flue 5 of the embodiment shown in Fig. 2, is provided with a double wall, as illustrated, and the outer wall 41 is provided with spiral fins 48 which project into proximity to the inner surface of the inner wall lc of the outer casing. The inner wall of the flue 5c is indicated by the reference numeral 49, and

it will be noted that a baffle 5| is provided in the space between the walls 41 and 49 whereby the said space is divided into two vertical sections. By this means a cooling fluid may be passed downwardly through one portion of the channel under the baffle 5| and upwardly in the outer channel thereby effecting an adequate circulation of the fluid in the jacket. Fins 52 on the inner wall project into the interiors of the fins 48 of the outer wall so as to direct the cooling agent against the surfaces of the latter fins. In this case also it will be noted that the casing la is provided with an outer jacket 53 forming in effect a double walled casing, and this space 54 may be utilized either for insulation or for reception of a coolant as circumstances may require.

In Fig. '7 the casing ld is provided with a spiral groove within the combustion chamber area so that the high velocity combustion gases will be caused to move downwardly in the chamber in spiral flow. This high velocity spiral movement of the gases has an effect described above wherein the particles undergoing heat treatment and entrained in the stream of heated gases are prevented from contacting the surfaces of the casing by a film of the gases which acts as a buffer. The centrifugal action in this case tends to throw the particles away from the surface of the flue duct 5d and toward the surface of the casing Id and both surfaces are thereby protected against clinker formation.

In Figs. 8 and 9 I have illustrated a desirable form of furnace structure wherein the casing I6 is made in sections which are superimposed one upon another around the flue duct 56. In Fig. 8, three such casing sections are illustrated, said sections being identical in form and being shaped so that each of the sections interlock mechanically with the adjoining sections. Each of the sections, which are designated by the reference numerals 55, 5S, and 51, comprises a pair of nozzles spaced apart or at opposite sides of the section and arranged to discharge into the chamber 5e tangentially or substantially so for the purposes set forth above. In the present instance, the sections 55 and 51 are provided with burner nozzles designated in Fig. 9 by the reference numerals 58-58 and the nozzles associated with the section 55 which communicate with the chamber 6e through elongated ports 59 are designed to inject the particles of material to be processed. By this means the burner nozzles 58 which discharge through relatively narrow slots 6! to the chamber 6e are interspersed with the nozzles which introduce the said particles whereby an intimate mixture and dissemination of the particles with the combustion gases is obtained with a pronounced mixing action near the burners where the flame from the latter intersects the gas stream.

The embodiment of the invention shown in Fig. 10 utilizes a somewhat different method of introducing the particles of solid material. In this case the material is introduced into a hopper 62 which is positioned at the top of the casing If and embraces the flue duct 5 The lower end of the hopper 52 is connected with the upper end of the casing If through ports 63 which are controlled and can be regulated as to uncovered area by a valve plate 64 rotatable around the axis of the duct 5f. The bottom of the hopper 62 is formed by a screen 65 which overlies the ports 63, and by regulating the amount of openmg of the said ports by adjustment of the valve 9 64, the flow of the particles into the top of the casing I J may be regulated accordingly.

In order to obtain a smooth uniform fiow of the particles from the hopper into the casing, the said hopper is provided with paddle elements 66 which are mountedfor rotation upon a sleeve 61 embracing the duct The upper end of the sleeve 67 is provided with a sprocket 68 and this is connected through a chain 69 which a sprocket H on the output shaft of a variable speed unit 12, said unit being operatively connected with a driving motor 13. In this case three sets of burners 14 are provided in the wall of the casing I said burners embracing substantially the full length of the combustion chamber, and this wall is jacketed as indicated at 15 for circulation therethrough of a cooling agent, said agent being introduced through a pipe 1'6 and discharged through a pipe 7'! respectively at top and bottom of the combustion area. In all other respects the device corresponds to the embodiment of the invention illustrated in Figs. 1 and 2.

It will be apparent that the device is subject to further modification without departure from the invention as defined in the appended claims.

I claim:

1. In apparatus for processing fusible materials, a combustion chamber, means for creating a flow of combustion gases through said chamber from one end thereof to the other, means for feeding fusible material as small particles into the chamber for entrainment in said gases, and means for adjusting the length of said chamber to thereby afford a regulation of the period of exposure of said particles to the heat within the combustion chamber.

2. In apparatus for processing fusible materials, a cylindrical casing, a duct of relatively small diameter extending into an end of said casing and forming with the wall of the latter a combustion chamber of annular cross section, means for relatively adjusting said duct and casing to vary the length of said combustion chamber, means for introducing fuel to said chamber, means for feeding fusible material as small particles into the chamber, a spiral structure embracing said duct and constituting a means for preventing accretion of fused particles upon the walls of the chamber, said spiral constituting also a baffle for regulating the flow of combustion gases and the suspended particles through the chamber, means for rotating said spiral structure and for varying the speed of said rotation, and means for circulating a fluid cooling agent through said structure.

3. In apparatus for processing fusible materials, a cylindrical casing, a stack duct extending into one end of said casing in spaced relation to the wall of the latter, a burner in the wall of said casing adjoining said stack, the inner end of said burner being directed substantially tangentially into the space between the stack and said casing, and means for longitudinally adjusting the stack in the casing to vary the effective length of said space, and means for introducing work material into said space for movement with the combustion gases through the latter.

4. In apparatus for processing fusible materials, an elongated casing of circular cross section and tapering toward one end thereof, a stack duct in the other end of the casing, means for introducing the said Work material as small particles into the casing toward the stack end thereof, said stack forming with the said wall of the casing a combustion chamber for reception of said material, a burner in the wall of the casing to project a flame into said chamber, and means for longitudinally adjusting the said duct in the casing to vary the position of the inner end thereof within the tapered end of the casing and to thereby regulate the area of the discharge end of said chamber.

5. In apparatus for processing fusible materials, a furnace having an elongated combustion chamber of annular cross section, means for introducing said material as small particles into said chamber, combustion means for setting up a turbulent flow of hot gases in the chamber from one end thereof to the other, and means for adjusting the cross sectional area of the latter end of the chamber.

NORMAN P. HARSHBERGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 107,600 Duvall Sept. 20, 1870 1,276,866 Boyle Aug. 27, 1918 1,513,622 Manning Oct. 28, 1924 1,532,451 Smith Apr. 7, 1925 1,846,991 Carlson Feb. 23, 1932 1,862,869 Tainton June 14, 1932 1,868,512 Ahlmann July 26, 1932 1,910,101 Frischer May 23, 1933 1,992,669 Labus Feb. 26, 1935 2,026,622 Fleming Jan. 7, 1936 2,131,905 Strezynski Oct. 4, 1938 2,271,485 Parsons Feb. 3, 1942 2,300,042 Caldwell Oct. 27, 1942 2,306,462 Moorman Dec. 29, 1942 2,511,293 Patrick June 13, 1950 FOREIGN PATENTS Number Country Date 20,759 Great Britain Sept. 11, 1912