US1794978A - Art of desiccating liquids - Google Patents

Description

March 3, 1931. PEASE 1,794,978

ART OFDESICCATIN G LIQUIDS Filed June 9 1925 3 Sheets-Sheet l Kali/726.29:

March 3, 1931. F. F. PEASE ART OF DESIGCATING LIQUIDS Filed June 9 1925 3 Sheets-Sheet 2 March 3, 1931. F. F. PEASE ART OFDESVICCATING mourns Filed June 9, 25 3 Sheets-Sheet 5 Patented Mar. 3, 1931 UNITED STATES PATENT OFFICE FRED FORREST PEASE, F SQUANTUM, MASSACHUSETTS, ASSIGNOR TO I. I. TEASE, INC., 01' BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS ART 0! DESICCATING LIQUIDS Application filed June a,

The present invention relates to drying liquid and semi-liquid products and more particularly to drying liquid products delivered to the drying air in the form of a spray.

Various expedients have been suggested for drying liquids, such as milk, liquid soap, etc., sprayed into drying air for the purpose of removing the water and collecting the remaining solid substance in the form of a merlo chantable product. Difiiculty has been experienced, however, in removing the water from the liquid product and thereafter separating the product from the air without injury either to the product or without employing a complicated or elaborate apparatus.

One object of the present invention is to provide a relatively simple and compact apparatus for drying liquid products and recovering the dry residue in a single operation and without injury to the product.

With this and other objects in view, one feature of the present invention contemplates delivering the liquid to be dried into'a stream of drying air from the lip or edge of a rotating nozzle in such a manner that the liquid is intimately associated with the dryin air without substantial contact with the wa is of the container.

A further feature of the invention contemplates means for maintaining the drying air and entrained liquid in continuous motion throughout the drying chamber and thereafter permitting a substantially free passage of air with entrained liquid from the chamher while forcibly separating the dried residue therefrom.

Still further features of the invention consist in certain novel features of construction, combinations. and arrangements of parts hereinafter described and claimed, the advantages of which will be obvious to those skilled in the art from the following description.

In the accompanying drawings illustrating the preferred form of the invention in its apparatus aspect, Fig. 1 represents a longitudinal section in elevation of the drying apparatus embodying the features of the invention; Fig. 2 is a detail illustrating a par- 60 tial front elevation of the apparatus; Fig. 3

1925. Serial No. 35,884.

is a detail illustrating a sideelevation partly in section of the means for spraying liquid into the drying air and for deliverin air to the chamber; and Fig. 4 is a detail s owing the air seal for the separator.

In the embodiment of the invention il1ustrated'in the drawings a substantially cylindrical drying chamber 10 is provided with means at one end for delivering liquid and drying air thereto and at the opposite end for separatin the dried residue from the air. The cylindrical drying chamber may have a length approximating three or more times the diameter. The liquid substance to be dried is delivered into one end of the chamber at approximately the axis in the form of a funnel shaped spray which immediately encounters the drying air. The direction of the liquid in the air is such that the liquid is caused to intimately associate with the air without impingin on the adjacent walls of the container or ecoming immediately subjected to an excessive volume of hot dry air, which would cause the immediate formation of a dry residue on the walls of the container adjacent the delivery point of the liquid. In actual practice, the drying of the liquid is progressive and uniform as it traverses the length of the drying chamber and is substantially wholly completed when the air and entrained substances reach the opposite end of the chamber and encounter the means for separating and recovering the dry residue.

As indicated more particularly in Fi s. 1 and "3, a nozzle 20 projects inwardly rom an end wall 22 of the container. This nozzle 7 is detachably connected by screws 24. with a hollow supporting head 26 mounted in the wall 22 as indicated. Journaled within the nozzle and projecting slightly beyond the inner edge of the nozzle is a rotary atomizing cup 28 supported upon the end of'a tubular enclosed by an end casting 40. The cup is rotated through the pulley in any convenient manner as by an electric motor, not shown, which may be connected to the pulley through a belt. Supported concentrically within the rotating cup is a feed tube 42 having an inner down turned delivery end 44, which feeds the liquid on to the bottom of the cup back of the outer delivery edge. This feed tube is supported within the end castin and is adjustably secured in place by a t umb screw 46 which permits the position of the delivery end to be varied with respect to the interior of the cup. The feed tube is connected with a liquid storage tank 50 through a connecting pipe 52 and valve 54. The storage tank. contalns the liquid-to be dried, the flow of which may be regulated through *ately engaged by air emerging from the nozzle about'the cup, which diverts the spray of liquid and causes it to flow outwardly in a generally funnel shaped stream. In addition to the air sup lied about. the rotary cup 28 air in materially larger volume is suphed about the nozzle through a duct 70 as indicated more particularly in Figs. 2 and 3.

This air passes through a heater indicated at 72 andhas capacity comparatively large quantity of liquid. Operating in con unction with the two sources of air supply previousl mentioned 4 is a third current of air supplie 'to the conical end wall 7 6throu h an air duct 78 which entersthe conical en wall from the outside nearly tangentially, the elongate orifice dotted lines, at 78 cointherem, shown in cidin with the similarly shaped terminus .Of-Sflld duct 7 8. This air duct, as indicated in Figs 1 and 2, is designed to suppl air tangentially to the container, the com inatlon of the two air currents serving to cause a spiraling movement of the entire body of air with entrained liquid in a direction lengthwise of the container. The air duct 78 is also connected with the heater 72, which serves to suplpl heated drying air delivered through bot t e ducts 7 8 and 70. The control of the drying air in this manner serves to remove moisture from the liquid substance and maintain the substance to be dried out of contact with the walls of the container until substantially all of the liquid hasbeen exposed by the air. This prevents incrustmounted in a similar 'a discharge passage 104.

action initiated by the for absorption of a ing the walls of the container by partially dried substances and permits the recovery of substantially all of the dried residue. Any small percentage of the dried residue which contacts and remains on the inner wall of the container may be readily removed therefrom in its dry, granular or powdered state. After its traverse throughout the length of the container, the air with the dry residue carried thereby encounters a rapidly revolving separator 90, which comprises a tubular screen basket having a mesh suited to the degree of fineness of the dried residue.

. The exit of the drying chamber is completely closed except through the screen 90 and all of the drying air is compelled to pass therethrough. --This separator screen, as indicated moreparticularly in Fig. 1, consists of a slightly conical member closed at the inner end 92 and mounted upon a shaft 94 which is journaled at its opposite ends in bearings 96 and 98. The inner bearing 96 is supported in a skeleton spider 100' mounted within the container in such a manner as not to interfere with the flow of ai r therethrough and the outer bearing 1s spider 102 enclosed in The basket is revolved at high speed from a pulley 106 sup-- ported outside of the casing 104- and driven in any suitable manner. The casing 104 com-. municates with a discharge duct 108 connectedwitha blower of ample capacity to maintain the desired flow of air through the container. The dried residue either through direct contact with the surface of the rapidly revolving screen or through centrifugal screen is discharged from the air and collects in major portion in a receiving pocket 110' formed in the lower portion of the cylindrical container beneath the separator me her.

It is very-important that leakage of. air laden with solid materialhetween the revolving se arator and the ed e of the casingshall be e ectually prevente This is accomplished in the present invention in a unique and practical manner by providing fora counter-current of air between the outer edge of the separator and the adjacent wall of the casing. To this end, as shown more particularly in Figs. 1 and 4, the outer edge of the screen basket is supported on a ring 120 having an outwardly extending flange 122 which is substantially cent to the stationaryarallel to and adja- Eange 124 forming a part of the casing. The flange 122'is provided with blades 126 preferably cast thereon and adapted to insure a current of air in the direction of the arrow in Fig. 1. With this construction, the rotation of the separator causes the blade 126 to act as'a .fan and introduce clean air from beyond the separator back into the main drying chamber. This countercurrent of air is suflicient to efl'ectually prevent leakage of dust laden air from the drying chamber into the exhaust passage and dis )enses with the necessity of packing joints an similar devices for closing the openings.

If desired, in order to conserve heat, the exterior of the cylindrical drying chamber may be covered by a layer of heat insulating material 112, such as asbestos packing or similar material.

The present invention provides an eflicient and self-contained apparatus for effectually drying and recovering materials originally in a liquid form. In actual practice, the

drying chamber enclosed by the casing has a diameter approximating six feet and a length of sixteen feet and is employed for drying liquid hemoglobin and liquid blood serum. The apparatus as employed for this purpose effectually dries and recovers the serum and hemoglobin in a granular merchantable form without oxidizing or causing incrusting on the the walls of the container or moving parts. By utilizing the current of relatively cool air about the atomizing cup, the latter is maintained cool and incrustation upon the walls of the cup prevented. In drying certain other liquid products, it may be possible to dispense with the current of relatively cool air about the cup and heat the air for this purpose.

Although the apparatus as illustrated and described is particularly designed for the spray drying of products originally in a liquid form, it will be nevertheless obvious that the apparatus could be employed, if so desired, for cleaning or washing dirty air by spraying into the dirty vair Washing liquid which would moisten and agglomerate the solid particles and permit them to be separated.

The character of the liquid spray delivered from the front edge 62 of the atomizing cup may be varied by altering the position of the delivery end 44 of the feed tube 42 lengthwise of the interior of the cup. 13 suitably ad justing the position of the eed tube, the spray may be governed to cause a thorough intermingling with the drying air and yet not penetrate the surrounding envelope of air in a manner to engage with and form incrustation on the wall of the container. The control of the liquid spray in this manner is an important and desirable adjunct of this class of apparatus.

It will be evident to those skilled in the 'art that with this form of appartus the drying of the liquid product'is uniform and continuous throughout the length of the drying chamber. This is due in part to the fact that the liquid spray, as delivered, encounters the entering main stream of drying air when said drying air is hottest, and is thereafter di-- rected concurrently with the direction of air flow, being removed from objectionable contact with the walls of the drying chamber air delivered'tangentially to the inner wall of the chamber and spiraling thereabout in a lengthwise direction. Furthermore, the employment of a substantially horizontal drying chamber with the product supported therein during its traverse lengthwise of the chamber, precludes the precipitation of', a part of the dried material to the bottom of the drying chamber as frequently happens with a vertical chamber in which the movement of the product during the drying period is downward and concurrent with the flow of drying air. In drying liquidsolutions such as blood, milk or liquid soap, the use of the heated drying air inevitably produces dried hollow particles or granules which may be accompanied by a certain degree of swelling or enlargement of the dried particles or granules, probably dueto the initial and superficial drying of the liquid drops with a subsequent expansion and evaporation of moisture from the interior, these materials having a composition such as to resist complete fracture of the granules into a powdered form during the progress of the drying action. The resulting product is characterized by an interior void or voids, may be described as granular rather than powdered, and due to a comparatively large superficial area is more readily soluble than would be a product not so constituted. Obviously such a product, if not subsequently powdered or ground into a powdered state, bulks larger than a finelydivided powder.

I claim: .1. The process of producing a dried product from liquid solutions of materials such as blood, milk or soap, in an enclosed treating space, which comprises the preparation of the material in the form of liquid stock, forcibly centrifugally spinning the liquid stock radially in all directions from a central and generally horizontal axis, projecting an annular current of gas about and in proximity to the delivery region of the spray, the current of gas having a direction and velocity such that it intercepts and diverts the spray and continues therebeyond in a generally axial direction, supplying a further volume of drying gas annularly about the central axis and the first mentioned current and projected generally in an axial direction such that the two currents of gas with the combined s ray continue with a like manner of flow, w ich persists in a well defined axially-moving column entraining the gas-borne spray in process of drying, supplying a further current of as in proximity and tangentially to the wal of the treating space in a manner to coact with said first named currents to entrain and propel spirally and axially spray parthrough the surrounding envelope of heated blood, milk or soap,

completed, and subsequently separating dried particles from the gas.

2. Apparatus for producing a dried product from liquid solutions of materials suchas comprising an enclosed drying chamber, a rotary cup spray member at one end of the chamber for-spinning liquid stock centrifugally and radially from a central and generally horizontal axis, means for projecting an annular current of drying gas about the spray member with sufficient velocity to move it axially throu bout the length of the chamber in a well de ned and persisting stream, means intermediate the rotary spray member and first. mentioned projecting means for directing upon and intercepting the spray with an annular gas current mov- 1n me ntioned current and diverting the spray into a generally axial direction the combined gas currents and entraine spray to be propelled axially throughout the chamber in a well defined streamwhich mailitains the spray gas borne until completion of drying, and means for thereafter separating the dried particles from the drying gas.

3. Apparatus uct from liquid solutions of materials such as blood, milk or soap, comprising an enclosed drying chamber, a rotary cup spray member at one end of the chamber for s mmng liquid stock centrifugally and radia y from a central and generally horizontal axis, means for pro ecting an annular current of drying gas about the spray member with suflicient veloc 1t to move it axially throughout the l h o the chamber in a well defined and persisting streamimmeans intermediate the rotary traine spra mem r and first mentioned pro]ect-. ing means for directing upon and intercepting the spray with an annular gas current moving in like manner of flow with the first mentioned current and diverting the spray into a generally axial direction ior causing the combined gas currents and enspray to be propelled axially throughout the. chamber in a well defined stream which maintains the spray gas borne until completion of drying, means for tengentially introducing a stream of spray end of the chamber adjacent the wall thereof and outside said annular current projecting means, and means for thereafter separating the dried particles from the drying gas.

In testimony whereof I have signed my. name to this specification. v

- FRED FORREST PEASE.

in like mannerof flow with the first 1 for causin for producing a dried prod-- gas at the v

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