US2515665A

US2515665A - Spray drying device

Info

Publication number: US2515665A
Application number: US696233A
Authority: US
Inventors: Oliver T Pieper
Original assignee: AMERICAN DYEWOOD Co
Current assignee: AMERICAN DYEWOOD Co
Priority date: 1946-09-11
Filing date: 1946-09-11
Publication date: 1950-07-18
Anticipated expiration: 1967-07-18

Description

July 1 8, 1950 o. T. PIEPER- 2,515,665

SPRAY DRYING DEVICE Filed Sept. 11, 1946 2 Sheets-Sheet 1 INVENTOR Oliver I Pz'eyver BY W ATTORNEYS y 950 o. T. PIEPER 2,515,665

SPRAY DRYING DEVICE Filed Sept. 11, 1946 2 Sheets-Sheet 2 FIG. 4

INVENTOR filz'uer 7. Pie var ATTORN EYS Patented July 18, 1 950 Oliver T. Pieper, Edgewood Hills, Del., assignor ,to American Dyewood Company, Chester, Pa., a corporation of Pennsylvania,

Application September 11, 1946, Serial No. 696,233

This invention relates to spray drying and particularly' to improvements in apparatus for separating material in a dry condition from liquids containing such material.

Spray drying, in which a liquid is distributed into a current of heated gas such for example as combustion products, with or without added air, for the purpose of rapidly evaporating the liquid and obtaining a dry product, has been practised for many years with various types of apparatus. The most modern and eifective apparatus utilizes a whirling disc or wheel. to which the liquid is fed and from which it is distributed by centrifugal force applied by the rapid rotation of the wheel. In such apparatus, the problem of obtaining proper distribution of the liquid from the wheel has never been completely solved. proper distribution of the liquid from the wheel has'resulted in failure to evaporate all of the liquid in portions of the material, and deposits of partially evaporated material are built up on the walls of the evaporation chamber. This in turnv necessitates frequent stoppage of the apparatus for cleaning and additional expense due to cleaning and to the loss of material which is not recovered in the desired form. Improper distribution of the liquid from the wheel has also resulted in atomization of the liquid leaving the spray head, so that a mist of liquidglobules is formed. Although such globules dryquickly and do not adhere to the walls of the drying chamber, they dry to form particles of very small size, which are objectionable, e. g., in soap powders where they cause discomfort to the user. These and other disadvantages of the known types of apparatus have limited the application of spray drying, which in many cases has proved to be uneconomical.

It is an object of the present invention to provide an improved spray drying head in which proper distribution of the liquid is maintained and the disadvantages mentioned are avoided.

Another object ofthis invention is the provision of a spray drying head which is so designed that when rotated at high speeds (e. g, 5000- 15,000 E. P. M.) it distributes into the drying chamber a substantially uniform sheet of liquid which is depressed in the form of an umbrella by the stream of hot gas entering the drying chamber. For further information concerning the details of a complete spray drying apparatus in which the spray drying head of this invention maybe installed, reference is made to my prior patent applications serial Nos. 581,476 and 581,- 477, filed March 7, 1945,1'10W Patent 2,478,779.

8Claims. (01.2995-63),

- These and other objects are accomplished in accordance with the invention by constructing a spray dryinghead comprising a primary flange having a vertical circumferential baflle and a secondary or auxiliary flange placed in such relationshipto the primary flange as to provide an.

annular spacebetween them through which the liquid to be spray dried is thrown by centrifugal force. In accordance with this invention I have discovered that it is essential that the outer circumferential face of the auxiliary flange should not extend above the adjacent inner vertical face Fig."1 represents in section an elevation of a circular spray drying head having an external diameter of about 6 inches;

Fig.2 represents a modification of the primary flange by providing an intermediate baffle to assist inproviding a uniform sheet of liquid leaving the spraying device;

Fig. 3 represents a modification of the secondary or auxiliary flange, shown in relationship to the primary flange; and

Fig. 4 represents a sectional view taken on line 44 of Fig.v 1.

Referrin to Fig. 1,.the numeral l represents a rotatably mounted chamber to which the liquid to be spray dried is fed through the stationary pipe 2 containing a control valve 3 to regulate the rate of liquid feed to thespray head 4. A series of radially'directed holes 5 is provided at the base of the chamber l. The liquid being dried is thrown by centrifugal force through these holes 5, then through the radial passages 6 and 1 in theprimary flange 8, and then through the annular spaces 9 located between the primary flange 8. and the auxiliary flanges 10. The auxiliary flanges l0 arespaced in such relationship to the vertical circumferential baffle II on the flange 8 so as to direct the liquid thrown through the annular spaces 9 against the baffle 11. The liquid flows along the vertical face of the bafile H and is thence thrown in the form of a uniform sheet should preferably be staggered (as shown) and should be at least IS in number, in order to provide a liquid sheet having the greatest uniformity. The number of passages 6 and 1 should not be so great, however, as to result in excessive weakening of the apparatus, and the passages should be of sufficient diameter to prevent their clogging. The number' and size of the passages 6 and I will depend upon the capacity desired for the apparatus, upon the materials used in its manufacture, upon the liquid being spray dried,- and upon other factors, and may be determinedby simple experiments.

Referring to Fig. 2, an intermediate bafll'a I2- has been provided on the flange 8; to assist in the production of a more uniform sheet of liquid leaving the spray head and thus result ina reduction in the content of dust in the final product.

Fig. 3 shows a modification of the auxiliary flange H) which has been found to be useful in the preparation of a spray dried product of desirable properties. Preferably, however, the inner face: of the. verticalbaffle: H should extend 0000- 0.125: inch beyondithe adjacent face-of: the flange 10. Generally; the distance between the inner face: of' the vertical baffle H: and the outer edge of the: flange. II) :should not be greater. than about A depending upon the rateoffeed of thezliqe uid to theisprayhead'; uponthe particular liquid. being'spray dried, etc.

With a spray head of: the: type. described installed in-a suitable drying'chamber, I have: eiflciently spray driedi many materials (e. g:, ex tracts. of quebracho; wattle; dividivi, logwood; fustic, licorice, and coffee, and solutions of'a' wide: variety of detergents) to produce a free flowing, uniform product of high bulk' density containing a minimum proportion of products of. extremely small particle size.

I-claim 1. A- spray' drying device for distributin liq uid into a drying chamber, comprising a rotate-- ably'mounted shaft having a-head secureci thereto for rotationtherewith, andmeans. for conduct ing liquid to said head, saidhead" comprising an' outwardly-extending primar-y'flange andtwo outwardly-extending auxiliary flanges all mounted: for rotation with the head, the primary flange having smooth substantially planar upper and lower faces and the auxiliary flanges having smooth substantially planar faces spaced from the respective upper and lower faces of the' primary flange to provide upper'and lowera'nnul'ar chambers, said primary flange havingtransverse ly-extendi'ng upper and lower baffles. positioned beyond the outer peripheries of the auxiliary flanges, said bafiles extending from said smooth faces of the primary flange transversely-at least as far as the outer extremities of the auxiliary flanges, whereby liquid conducted to-the head: is thrown by centrifugal force through the upper and lower annular chambers against the-upper? and lower baffles and along said bafiles into' the: drying chamber in the form of asubstantially uniform sheet;

2 A spray drying device -as defined in claim I inwhich the primary flange has a plurality of generally radially -ex-tendi'ng passages there through communicatingwithsaid annularch'ambers, and the body'of the headhas'a-plurality'of 7 1 holes through which liquid introduced through the liquid conducti'ngmeans may-flowto said pas sages and to the annular chambers.

3; A- spray dr-yingd'evice as definediin claim. 1 in which the primary flange has'anupperxand; at

.4 lower annular baffling face spaced inwardly of said outer bafiles.

4. A spray drying device for distributing liquid into a drying chamber, comprising a rotatably mounted shaft having a head secured thereto for rotation therewith, and means for conducting liquid to said head, said head comprising a primary flange substantially perpendicular. to said shaft and mounted for rotation therewith, said flange having a hub portion with upper and lower faces, an intermediate portion of less thickness than said hub portion having smooth substantially planar upper and lower faces and a baflle at its periphery extending: substantially perpendicularlyabove and below the intermediate portion, an

upper and a lower auxiliary flange mounted for rotation with the shaft and having smooth substantially planar faces contiguous to the respective upper and lower faces of the hub portion of the primary flange over part of their extents and substantially parallel'but' spaced from the respectiveupper and lower faces of the intermediate portion of the primary flange. over. the remainder of their extents to provide upper and lower annular: chambers between the primary flange and the upper and lower auxiliary flanges and between. the hub and the baffle of theprimary flange, said baiile being, positioned beyond the outer: peripheries-of! theupper and lowerauxiliary flanges-and extending from the. intermediate portiorr ofv the primary flange above. and below perpendicularly at least. as far as the outer extremitieszofrthe upper andclower auxiliary flanges, respectively, and. a plurality of passageways. for

'- conducting liquid through said hub from the liquid. conducting-'means'to the upper. and lower annular chambers, whereby liquid conducted to the head. is .thrown' by centrifugal force through the:

upper. andthe: lower annular'chambers against the. baffle and along" the baffle into the drying chamber'in the. form of a substantially uniform.

sheet/L 5. Azspray: drying device as. defined in'claim 4 in. which said passageways extend alternately around the. peripheryofisaid hub portion to the upper/and; the'lower: annular chambers.

6-. A: spray drying device-for distributing liquid into: adrying: chamber, comprising a rotatably.

mounted shafthaving a head secured thereto for rotationv therewith, and: means for conducting liquidztosaid head, said head comprising an outwardly-extending primary flange and an outwardly-extending. auxiliary flange, both mounted for/rotation with the head, said flanges having.

smooth substantially planar annular opposing faces2spaced apart to form an annular chamber between. them, said. primary flange having a transversely-extending baffle positioned beyond but: adjacent' the. outer. periphery of said auxiliary flange,.saidl baffle-extending from the smoothfacexof said primary flange; transversely at least as faras the outer: extremity of the auxiliary flange, whereby liquid: conducted to. the head is thrown bycentrifugal force through said annular chamber against said baffle and along said bafiie into the drying chamber inv theform of a sub-- stantially uniform sheet;

7.. Alspray'drying device as defined in claim 6 in which the primary flange has a plurality of generally radiallyextending, passages therethrough communicating with the annular cham-- ber; and the body of the head has a plurality of holes. through which liquid introduced through the liquid conducting means may flow to said passageszandto the annular chamber,

8. A spray drying device for distributing 1iquid into a dryin chamber, comprising a rotatably mounted shaft having a head secured thereto for rotation therewith, and means for conducting liquid to said head, said head comprising an outwardly-extending primary flange and an outwardly-extending auxiliary flange both mounted for rotation with said head, said flanges having smooth substantially planar opposing faces spaced apart to form an annular chamber between them, said primary flange and said auxiliary flange each having a second face at the outer periphery of the respective first-mentioned faces extending transversely thereof and spaced relative to each other to provide a discharge channel communicating with the drying chamber, the second face of the primary flange being mounted beyond the second face of the auxiliary flange and extending transversely from the first face of the primary flange at least as far as the outer extremity of the second face of the auxiliary flange, whereby liquid conducted to the head is thrown by centrifugal force through said annular chamberagainst the second face of the primary flange and through said channel into the drying chamber in the form of a substantially uniform sheet.

OLIVER T. PIEPER.

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

UNITED STATES PATENTS Number Name Date 442,865 Kinder Dec. 16, 1890 1,779,296 Spross Oct. 21, 1930 1,779,336 Riley Oct. 21, 1930 1,870,099 Croan Aug. 2, 1932