US2415527A - Method of atomizing and desiccating substances and apparatus therefor - Google Patents

Description

Feb. 11, 1947. D, D: PEEBLES I 2,415,527

METHOD OF ATOMIZING AND DESICCATING SUBSTANCES, AND APPARATUS THEREFOR Filed July 3, 1942 5 Sheets-Sheet l fi 49 I x l f i L i 54 14a 24 .19 g3 23 10a w g1 22 INVENTOR.

Feb. 11', 1947.

D. D. PEEBLES METHOD OF ATOMIZING AND DESICGATING SUBSTANCES, AND APPARATUS THEREFOR Filed July 3, 1942 3 Sheets-Sheet 2 I l 69 I v 69 17 I 1 7 17 Q I 71 I '70 j y n l 3 E I II 1 1i F T I J I I I y I 60 J6 I; 3+ A; 5 a3 J4 a0 61 INVENTOR.

9/ 61 fiazjddlfl wbles,

dywd/QW METHOD OF ATOMIZING AND DESICCATING SUBSTANCES, AND

Feb. 11, 1947. =E BLE 2,415,527

APPARATUS THEREFOR Filed July 3, 1942 '3 Sheets-Sheet 3 INVENTOR. David 172 666565,

" a method action into minute Patented Feb. 11, 1947 2.415.527 METHOD or ATOMIZING AND nnsrooa'rmc.

SUBSTANCES FOR.

AND APPARATUS THERE- David D. Peebles, Hillsborough, Calif., asslgnor to Golden State Compan Calif.,a corporation of y, Ltd., San Delaware Francisco,

Application July 3, 1942, Serial No. 449,653

14 Claims.

This invention relates to a new and improved method of atomizing various liquid substances, as well as to a novel method of drying or desiccating such substances in atomized or finely divided orm.

This invention also relates to the novel product resulting from this method.

This invention further relates to new and improved apparatus for carrying out the atomization and drying methods of thisinventlon.

- It is an object of this invention to provide a new and improved method of atomizing and drying viscous substances in an efiicient, satisfactory, and relatively inexpensive manner, with the result that the finished product has the desired properties and is free from damage or deterioration produced during the atomizing and drying treatment.

A further object of this invention is to provide and means for drying highly viscous substances, such as, for instance, corn syrup, mo-

leases and the like, by the combined action of surface evaporation and simultaneous boiling-of moisture from the interior of minute particles of such materials.

. In the accomplishment of this object, the viscous material to be treated is projected at high speed into an atmosphere of drying gas which has been heated to a temperature above the boiling point of the viscous material being treated.

In addition, the viscous material so projected is previously heated to a temperature at or near the boiling point of such material at atmospheric pressure and, while at such temperature, .it is held under suflicient ing Of the liquid therefrom until the instant of release for projection. Furthermore, the viscous material is subdivided by mechanical or other and the course of such bring each of the particles instant of projection, projection is such as to so projected progressively into the environment of new hot drying gas. The accomplishment of the above stated object is productive of dry, fragmentary, minute particles of the material desiccated, resembling in appearance 'and shape the fragments of broken,

pressure to prevent the boilglobules or particles at the in such manner that at the outset the individual particles tend to form themselves into hollow globular bodies. These hollow bodies next undergo a certain amount of case hardening accompanying evaporation of moisture from their surfaces. Subsequently, the hollow bodies so formed are shattered or ruptured by the further boiling of the moisture located in' the interior thereof. This boiling occurs on the interior of such particles rather than in the exterior regions thereof, for the reason that the boiling point of the material in the exterior region is elevated by virtue of the increased concentration resulting from surface evaporation. Furthermore, the boiling action is accelerated by the rise in temperature of the individual particles, due to the conversion of kinetic energy of the moving particles to heat energy, as the high speed ofmovement of the projected particles is diminished.

This process utilizes kinetic energy supplied by the movement of a high speed rotary device for imparting to the material to be atomized and dried, energy in the form of heat which serves to qulcklyand effectively raise the temperature of the material to be dried above the boiling point, and in such manner effects an immediate boiling of a portion of the water at the instant the material is cast oil into the drying space.

It is a further object of this invention to provide a novel dried or desiccated product produced from various viscous materials, such as, for instance, corn syrup, molasses, or the like, which product is characterized as having a substantial portion made up of particles in shape and appearance like fragments of hollow globular bodies.

This invention is particularly useful in connection with the desiccation of highly viscous materials. It is found in practice that it is much more economical to remove water from liquid substances by evaporation, such as evaporation under reduced pressure, than it is to dry the same by atomizing the material in atmospheres of heated gases. On the other hand, complete hollow globular bodies which vary somewhat in size and shape.

-- The desiccation '6: 'such material is accomplished through the conjoint and simultaneous actions of surface evaporation, produced by the hot drying gas. and the boiling fromthe interior of the subdivided particles of a portionof the moisture present. These conjoint actions occur drying or removal of the final moisture cannot be carried out by theevaporation method with the same results accomplished by the spraying method. An ideal procedure, therefore, is that of utilizin the evaporation method to the desired extent to produce an extremely viscous material, and then removing the residual moisture from the viscous material by the spray-drying method. This requires a satisfactory method and 'means'for handling extremely viscous materials,

and consequently the provision of the method and ing the runner.

runner and eventually means of this invention constitutes an important and valuable contribution to this art.

Other objects not specifically mentioned are contemplated for this invention, as will be apparent to one skilled in the artas the following description proceeds.

The process of this invention is based upon the discovery that an effective atomizing and drying can be carried out, particularly with various viscous substances such as corn syrup, molasses and the like, when the same is subjected to conditions which cause a substantially instantaneous boiling of the water contained therein, at the moment the same is projected in a finely divided or atomized form into an atmosphere of drying gas. More specifically, the process is predicated upon the discovery that drying or desiccating of such substances can be effectively accomplished by eliminating the water by boiling in the manner referred to. by feeding the liquid to be dried to a rotary nozzle or atomizing device, at a temperature closely approaching the boiling temperature of the substance, and by causing it to undergo an increase in temperature in amount sufficient to raise its temperature to a point above the boiling point, through the action of kinetic energy supplied by the motion of the rotary atomizing device.

The invention may e illustrated by pointing out that the additional heat derived from kinetic energy required to raise the temperature of the substance above its boiling point can be imparted to the substance through the action of a rotary device hereinafter referred to as a runner" or basket, which is adapted to rotate at relativel high speed, and which is provided with outlet openings adjacent its periphery disposed at such an angle with respect to the direction of rotation as to establish a substantial pressure within the runner itself in oppos'tion to the centrifugal force which acts on the substance to ultimately discharge the same into azone of drying atmosphere. It is found that pressure established by the novel characteristics of the runner ultimately is effectively opposed and overcome by the centrifugal force, with the result that the substance drawings in to avoid the danger perature which is too high, or, in other words,

at a temperature which would cause boiling to occur in the runner. Even when the operation is carried out by feeding the substance to the runner at a temperature too closely approaching the boiling point, some boiling may'occur in the runner itself. When boiling occurs in the runner, the material being treated may become unequally distributedin the runner, with the result that the runner is unbalanced. Such unbalancing of the runner at operating speeds is detrimental to the success of the procedure and ultimately results in a complete breakdown and failure. Further more, any appreciable boiling in the runner will unduly increas the pressure in the runner and thereby damage the runner and cause failure whether or not the runner has become unbalanced.

The present invention, therefore, has for one of its objects, the provision of a method and means whereby various substances, especially viscous substances, may be fed to a runner or rotary atomizer of special construction, at a temperature sufficiently below the boiling point of unwanted boiling in the runner and yet at a temperature sufliciently high to permit the same to be raised to a point above the boiling point, and, in addition, cause the increase in temperature to occur through the action of kinetic energy supplied by the motion-of the runner itself.

The process of this invention will be more readily understood by reference to th accompanying which one apparatus is shown as illustrative and by which the process may be carried out. The apparatus itself constitutes a new is cast off tangentially at a relatively high speed and that the kinetic energy is converted into heat in amount sumcient to raise the temperature of the substance to a point above the boiling p The success of this invention is believed to be attributable to the fact that the additional heat which elevates the temperature of the substance being treated, from a point slightly below the boiling point to a point above the boiling point, is derived entirely from the kinetic energy imparted to the substance as a result of its movement through the drying atmosphere surround- In other words, the rise in temperature is the result of the movement of the substance through the drying zone at the speed established to overcome the pressure created by the movement of the runner itself. This action prevents the substance being treated from reaching a temperature above the boiling point while in the runner or at any time when it is likely to dry on the walls or in the outlet openings of the runner, such as would be likely to cause the dried substance to adhere to the surface of the clog the passages therethrough and interfere with the success of the operation. Such a detrimental result would also occur with viscous substances, if the product should be introduced into'the runner at a temand useful invention which-is covered hereby.

In the drawings- Figure l is a side elevational view, partly in cross section, of a drying apparatus constructed in accordance with this invention and which is capable of carrying out the process herein described and claimed.

Figure 2 is an enlarged levational view in cross section, of the upper central portion of the drying apparatus shown in Figure 1, which more clearly shows the construtcion of the rotary runner or so-called basket and it associated parts.

Figure 3 is a cross sectional view taken on the lin 3--3 of Figure 2 and looking in the direction of the arrows.

Figure 4 is a slightly enlarged view of the upper end of the drier shown in Figure 1; and

Figure 5 is a fragmentary plan view showing the upper part of the drier as it would appear when looking down upon it.

The process of this invention will be better understood by reference to the -following description of one form of apparatus by which the same may be practiced. It is to be understood, however, that the process ticular means,.as it will be clear to one skilled in the art that other devices may be used with success. 7 p

The apparatus illustrated in the drawings consists of a desiccating chamber l0 which preferportion Illa,

ably includes an upper substantially cylindrical shaped portion lilb. At the lower end of the portion Illb there is a cylindrical portionlllc which has a lower'cone H connected to the discharge conduit l2. A centrifugal atomizin'g nozzle I3 is located at the upper end of the chamber aligned with the vertical axis of the chamber. This atomizing nozzle is herein sometimes referred to is not limited to thi parand a lower substantially conicale I effective in impartin duct Ila on top of the drier, for c conical-shaped c v the wall 2I and and also with air filters 3 terial along with s through the condui as'the runner or basket and is of a special construction hereinafter described in detail. The construction of the runner is such that it .will be g energy, derived from the motion of the runner, in the form of heat to the material being treated.

A hot drying gas, such duced into the upper pc the region surroundin as heated-air, is intro-' rtion of the chamber in g the atomizing nozzle I3. Thus, with the construction illustrated, hot air is introduced through the conduit I4 which terminates in a suitable duct, such as the horizontal onducting the air duct I4 has suitable heater an air filter I6. ion is of horse-v ommunicates with the air chamopenings in the top wall I1 of This chamber is formed by an -shaped wall I9, together with lower horizontal wall 2I. The ollar 22 is mounted centrally of serves to conduct the hot gas downwardly about the centrifuge atomizing zle I3. The lower walls of the chamber preferably lined with a heat insulating m 20.

air into the air chamber I8. Th'e its opposite end connected to a It which is in turn connected to The air duct I ia in this illustrat shoe shape and her I8 through the air chamber. inverted, conical the 'wall I! and aterial A certain amount of air upper portion of the chamber through the exhaust conduits 23, which communicate through the conical-shaped wall l9 and connect with the inlets of the blowers 24. A common conduit 26 is connected to the exhaust of the blowers and extends to and communicates with a cyclone separator 39.

In conjunction with th cating chambe tional introdu duits 21 com the conical p discharge ar ing chamber.

is removed from the e lower part of the desicr, means is provided for the addiction of drying gas. Thus, the conmunicate through the side wall of ortion Illb at several points with the ranged tangentially of the desiccat- In this instance, two general points of introduction of gas are shown for each'conduit 21, with the flow of gas being in a tangential direction. Conduits 21 connect with heaters 3i 2. Additional drying gas is intr lower extension I00, and for this purpose conduits 33 are provided which communicate through the side walls of the extension I00 in such manner that the flow of gas is directed in a tangential direction. The direction gas into the extension conduits 21. Gas intr 33 is likewise heated an of convenience, the con heaters 3| and filters 3 of the drawings.

Some of the materi the base of the desic oduced into the IIlc is the same as for the oduced through conduits d filtered and, as a matter dults may be fed from the 2,- as illustrated in Figure 1 a1 being dried falls down to cater, and some of the maome of the gas is removed t I2. This removal prevents the accumulation of any appreciable amount of the material at the bottom of the desiccator.

As representative of a suitable apparatus that may be employed to separate the dried material from the treated gas. there is shown a blower 37 having an intake which connects with the con-' duit I2, and a discharge which connects with the cyclone separator 39 through the conducting pipe 38. Thus, through the pipes 26 and 38 all of the dried material and treating gas are conveyed to the cyclone separator 39, where the ultimate separation of the material and gas is effected.

I3 are of introduction of 1 6 e v The separator 38 maybe of any suitable type but is here shown as a cyclone type having an -exhaust conduit 4| connected to a washer 42 which serves to remove any solid material which has not been separated in the separator itself. The material collected in the separator 39 feeds downwardly and passes into the discharge pipe 43 which'may serve to conduct it to any suitable place for desired.

Referring now more closure .of Figure 2, it wi ner or rotary atomizing zontally disposed circu a lower part and a periphery of the lower spaced lugs 53 which a particularly to the disll be noted that the rundevice comprises a horilar member 50 formed of 21 upper part I52. At the part 5| are a plurality of re separated one from the other by angularly disposed slots 54, (see Figure 3). These lugs collectively form an annular support on which rests the outer edge of the upper member 62. The upper member 52 has a series of similarly formed lugs 54 which are separated by angularly dispos As clearly shown in Fi gure 2, the upper half 52 of the runner is entire ly supported on the lower f, and the lower half provides the means of attachment oi the runneron the shaft '60. The runner is fitted on the sleeve 3| and held by means of the nut 62. The sleeve BI is held on the shaft by means of the n is locked in position the upper member tween the inner edge of the for the purpose of accommo dating a feeding bowl, hereinafter more fully des cribed.

nated generally 61, a support 68 moun the upper wall II .support 68 also s vdownwardly exte wer end of the It will be noted that this entire assembly storage, cooling, and sacking, as may be ted to receive the material runner and the sleeve ted by means of bolts. 69 on 1e antifriction derives its main support from the upper support member 68, and that it is hung on the upper wall of the drying chamber. It will also be noted that it extends down through the central opening provided in the upper wall I! into what constitutes a cylindrical space defined by the wall 80. .This wall is attached to the upper wall ll of the drying chamber and it constitutes the inner wall of an annular feeding passage for hot drying gas.

As more clearly shown in Figure 5, the pulley 65 on the upper end of the shaft 60 may be driven by a suitable motor 8| connected by means of the belt or other gearing element 82. The container 83, shown in Figures 2 and 5, are for lubricant for the upper and lower antifriction bearings, respec- 1 tively.

From the above description, that the runner is adapted to it will be apparent be mounted in the upper end of the drying chamber substantiallyv as shown in Figure 1, and that it is capable of being given a relatively high speed of rotation by means of the electric motor.

The material to be desiccated is fed to the runner by means of pipes 90-80 which extend downwardly from a point above desiccating chamber into the annular space defined by the cylindrical wall 80. These pipes extend down below the lower edge of the wall 80, or, in other words, into the upper portion of the drying chamber, and are caused to bend at right angles so as to extend horizontally and then to communicate tangentially with the upper, outer edges of an annular feeding bowl 0|. This feeding bowl fits within the space provided between the inner surface of the upper wall 52 of the runner and the collar 5! of the shaft, and it serves to efiectively close such 9| is provided with a series of windows 92 around its outer cylindrical face, which communicate directly with the interior space 51 of the bowl. Any suitable number of windows may be employed, but it is found that good results are obtained when six windows are employed.

The tangential feed of the material to be desiccated through the pipes 90-90 acts to give the material being treated a rotary motion within the annular bowl, the direction of which is opposite to that of the direction of rotation of the runner itself. 'It is to be understood that the runner rotates in .the direction indicated by the arrow of Figure 3, or, in other words, a direction opposing the outlet openings at the ends of the slots 53.

The manner of feeding .and discharging the material through the runner, according to this invention, is effective to impart to the material undergoing treatment the energy required to raise its temperature to and above the boiling point in the manner hereinbefore pointed out. The heated air which comes in at the top through the duct l4, passes through the annular air space provided by the sleeve 22 and the inner wall 80, and in passing therethrough it is preferably given at least a. slight rotary motion which in most instances will be concurrent with the direction of rotation of the runner. In addition, the best results will be obtained when the currents of air introduced at the lower part of the drying chamher, that is, through the pipes'fl and 33, respectively, are introduced so as to create a swirl rotating in a direction opposite or counter to the direction ofv rotation of the runner.

By means of the foregoing apparatus, it is found that the high speed of rotation which is employed serves to build up a pressure opposing the upper wall of the space. The annular bowl ing is eflected at the instant the material is atomized and exists in finely divided form in the dry- 1 ing space. v

For purposes of illustration, the following specific examples of actual runs carried out in accordance with this invention will now be given. These operations involved the treatment of corn syrup, which was sprayed from'the nozzle at approximately 38.5" Baum and 40 Baum, respectively:

Example 1 The first run is the 38.5" Baum run, which was carried out under the following conditions: The temperature of the material fed to the runner was approximately 210 F. The inlet temperature of the air fed into the drying chamber was between 326 F. and 344 F. The temperature of the tangent inlets was approximately 189 F. to 192 F. The temperature of the outlet gas was approximately 229 F. to 238 F. Approximately 71.37% of solids were recovered, and the output of commercial product for the unit as run was 2525 pounds per hour. 7

The atomizing runner was 12 inches in diameter and was operated by a, 50 horsepower motor, which was operatedat 3450 revolutions per minute when the runner was under load.

The atomizer was operated by a 3 inch pulley carried on the runner shaft, which in turn was driven by a 10% inch pulley on the motor.

Example 2 Example 3 A run was conducted in all respects like the run of Example 1, with the exception however, that the material was fed to the runner at a temperature of approximately 213 F. A product having a slightly different physical form resulted, and the product was in all respects an excellent commercial product.

Example 4 Example 5 A run was conducted in all respects like the run of Example 1, with the exception, however that the material was fed to the runner at a temperature of approximately 228 F. A produci From the foregoing, it will be seen that this-- invention provides a method as well as means by which the substance to -be desiccated, such as syrup, is brought to the nozzle under a temperature and pressure relationship which is closely approaching the boiling point of the substance treated, and that through the action of the nozzle itself, additional energy derived fromthe motion of the nozzle is imparted to the material, with the result that heat i added to the material and the temperature thereof is increased; and finally, that the material is suddenly released into the zone of low pressure, whereby an instantaneous flashing and boiling of the water present takes place, which is productive of an instantaneous drying of the material.

It is recognized that it is old to deliver sub-. stances of this type to nozzles under pressures and at temperatures above the boiling point, and applicant does not make any claim to such procedure, but the applicant does contend that it is novel to subject material being treated to the action of a nozzle or atomizing device while the same is undergoing a rapid and extensive movement at a temperature-pressure relationship below the boiling point of the material, and to impart to the material kinetic energy derived from the motion of the nozzle or atomizing device, and finally to cause the substance to be suddenly released into an atmosphere of lower pressure with the result that its temperature is instantaneously raised above the boiling point through the energy conversion and a consequent boiling and drying of the product occurs.

This application is a continuation-in-part of applicants copending application Serial No. 315,432, which on November 2, 1943, matured into Patent No. 2,333,333.

What is claimed is:

1. In a desiccating apparatus of the character described, a desiccating chamber, atomizing means in the upper portion of the chamber, and means for introducing a hot chamber in a region adjacent the atomizing means, and discharge means connected to said chamber, said atomizing means comprising a high speed, centrifugal rotor having openings in the periphery thereof disposed at an angle inclined in the direction of rotation in such manner as to maintain a pressure in said atomizer to be overcome in the discharge of substances therefrom.

2. In a desiccating apparatus of the character described, a desiccating means in the upper portion of the chamber, and means for introducing a hot drying gas into the chamber in the region adjacent the atomizing means, and discharge means connected to said chamber, said atomizing means comprising a horizontally disposed centrifugal rotor having an internal space adapted to receive the substance to be atomized, slots in the lateral face area of said rotor communicating with sa'd internal space, said slots extending at an angle to the radii and being inclined in the direction of rotation and spaced and angled in such manner that the wall between adjacent slots prevents material moving along a radial path from escaping unimpeded into the drying zone.

3. In a desiccating apparatus of the character described, a desiccating chamber, atomizing means in the upper portion of the chamber, and means for introducing a hot drying gas into the drying gas into the,

chamber, atomizing 10 chamber in a region adjacent the atomizing means, .and discharge means connected to said chamber, said atomizing means comprising a horizontally disposed centrifugal rotor having an internal space adapted to receive the substance to be atomized, and peripheral discharge passages communicating with said space and extending at an angle to the radii of said rotor, the angularity of said discharge passages being in opposition to of said rotor, whereby a pressure is the movement created in said atomizer during operation thereof, and means 6. The process defined in claim 4, further characterized in that said drying zone comprises an atmosphere of heated gas.

The process defined in claim 4, further charpoint of discharge said rotated at an together withthe pre-discharge pressure on said having a pressure less than sure on said substance, imparts to said superatmospheric pressure and of predetermined value, said pressure or value and said initial elevated temperature bein related in suchmanner that said substance, upon being discharged, will not be dried without the introduction therein of additional heat, converting the kinetic energy possessed by said substance into heat energy in said drying zone, said predetermined velocity being such that the kinetic energy so converted to heat energy produces heat in quantity suiiicient to elevate the temperature of said substance to a point above the boiling point of said substance at said pressure or predetermined value, and thereby instantaneously boiling and drying said substance in said drying zone while in an atomized state- 9. The process defined in claim 8, further char acterized in that at said point of discharge said substance is rotated at an angular velocity which, together with the superatmospheric pressure on said substance, imparts to said substance said Dredetermined velocity.

10. The process defined in claim 8, further characterized in that said drying zone comprises an atmosphere of heated gas.

11. The process defined in claim 8, further characterized in that at said point of discharge said substance is rotated at an angular velocity which, together with. the superatmospheric pressaid substance said predetermined velocity, and in that said substance is discharged into an atmosphere of heated gas.

12. The method of desiccating aviscous substance, which comprises the steps of heating the substance to be desiccated to an'initial elevated temperature, supplying the substance so heated to a point of discharge and subjecting said substance at said point of discharge to a pre-discharge pressure slightly in excess of the vapor said substance at said point of distrates, predetermined pressure or waterat' 212 charge, rotating said substance at a predetermined angular velocity and tangentially casting of! said substance in a fine spray into a drying zone of drying gas having a pressurelower than said pro-discharge pressure and of predetermined value, said pressure of predetermined value and said initial elevated temperature being related in such manner that said substance upon being cast off, will not be dried without the introduction therein of additional heat, and converting kinetic energy possessed by said substance into heat ensaid drying zone, said predetermined angular velocity being such that said substance will be so cast off tangentially by centrifugal force and that the spray droplets will have imparted to them convertible kinetic energy productive, when converted, of heat in quantity suiiicient to elevate the temperature of said substance to a point above the boiling point of said substance at said pressure of predetermined value, and said initial elevated temperature being close to but below the point where said substance will boil at said predischarge pressure, and thereby simultaneously boiling and drying the sprayed droplets of said 6 substance in said drying zone.

13. The method of desiccating milk concen- UNITED STATES PATENTS Number Name Date 1,779,516 Stevenson et a1 Oct. 28, 1930 2,222,396 Bowen Nov. 19, 1940 1,759,629 Riley May 20, 1930 2,003,575 Bowen June 4, 1935 2,294,221 Bowen et al Aug. 25, 1942 2,333,333 Peebles et al. Nov. 2, 1943 1,939,364 Peebles et al. Dec. 12, 1933 2,004,840 Van Suchtelen June 11, 1935 2,321,835 Walsh et al Feb. 11, 1941 2,216,815 Hall Oct. 8, 1940 1,971,479 Dubinbaum et a1 Aug. 28, 1934 FOREIGN PATENTS Number Country Date 761,881 French Jan. 13, 1934 which comprises the steps or heating the concentrate to an initial elevated temperature close to the boiling point oi water, conducting the heated concentrate to a point or discharge, subjecting said substance at saidpoint of discharge to a predischarge pressure in excess of the vapor F., imparting a high speed of movement thereto in a circular path until the concentrate is cast ofl tangentially in a fine spray into a drying zone of drying gas havin a pressure lower than said pre-discharge pressure and of predetermined value, said pressure of predetermined value and said initial elevated temperature being related in such manner substance, upon being cast 011, will not be dried without the introduction therein or additional heat, and converting the kinetic energy possessed by said substance into heat energy, said high speed being suflicient to elevate, by said energy conversion, the temperature 01 the spray droplets to a point above the boiling point of water at said pressure of predetermined value and causing boiling and drying of said concentrate to produce a dry powder.

14. In a desiccating apparatus of the character described, a desiccating chamber, atomizin means in the upper portion of the chamber, and means for introducing a hot drying gas into the chamber in a region adjacent the atomizing means, and discharging means connected to said chamber, said atomizing means comprising a horizontally disposed centrifugal rotor having an internal space adapted to receive the substance to be atomized, and slots extending from the inner to the outer circumferential surfaces or said rctor communicating with said internal space, said slots being inclined in an outward direction at an angle to the radii of said rotor, said angle being a leading angle in the direction of rotation, said slots being spaced and angles so that the outer opening of each slot is in radial alignment with the inner opening of the next adjacent slot preceding with respect to the direction of rotation.

. DAVID D. PEEBLES.

REFERENCES, CITED that said

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