US3878991A

US3878991A - Steam nozzle

Info

Publication number: US3878991A
Application number: US442540A
Authority: US
Inventors: Joseph L Sabadics; John F Ewald
Original assignee: General Foods Corp
Current assignee: General Foods Corp
Priority date: 1974-02-14
Filing date: 1974-02-14
Publication date: 1975-04-22
Anticipated expiration: 1992-04-22
Also published as: CA1015003A

Abstract

A nozzle designed for the uniform distribution of steam comprised of an elongated or slot-shaped discharge opening located in a nozzle nose section, steam being fed into said nose section by a header conduit, usually comparable in length to the nose section. The steam exits from the header into the nose section through a plurality of spaced-apart holes, the open area toward the two ends of the nose section being proportionately greater than at the center. The nozzle nose section is provided with a fixed foil member which provides divergent steam channels between the foil and upper and lower nozzle plates.

Description

United States Patent [1 1 Sabadics et al.

1 Apr. 22, 1975 STEAM NOZZLE [73] Assignee: General Foods Corporation, White Plains, NY.

[22] Filed: Feb. 14, 1974 [21] Appl. N0.: 442,540

[52] US. Cl. 239/456; 239/566; 239/592;

239/597; 426/453: 239/590.3 [51] Int. Cl. A231 1/08; B05b 7/14 ['58] Field of Search 239/5903, 597, 590.5,

[56] References Cited UNITED STATES PATENTS 1,248.565 12/1917 Slattery 239/597 X FOREIGN PATENTS OR APPLICATIONS 1,193,191 4/1959 1 France 239/597 1,179,416 10/1963 Germany. 239/592 U.S.S.R 239/597 Primary Examiner-Robert S. Ward, Jr. Attorney, Agent, or Firm-Th.omas R. Savoie; Bruno P. Struzzi [57] ABSTRACT A nozzle designed for the uniform distribution of steam comprised of an elongated or slot-shaped discharge opening located ina nozzle nose section, steam being fed into said nose section by a header conduit, usually comparable in length to the nose section. The steam exits from the header into the nose section through a plurality of spaced-apart holes, the open area toward the two ends 011" the nose section being proportionately greater than at the center. The nozzle nose section is provided with a fixed foil member which provides divergent steam channels between the foil and upper and lower nozzle plates.

6 Claims, 4 Drawing Figures STEAM NOZZLE BACKGROUND OF THE INVENTION The present invention relates to a nozzle for use in agglomerating water-soluble powders and more particularly to a steam nozzle for use in an agglomerating process wherein falling curtains of powder are projected by means of steam in a horizontal direction and into a drying tower. Such a process is well-known in the art and is specifically described in U.S. Pat. No. 3,554,760 to Sienkiewicz et al.

The effect of agglomerating a soluble powder is to improve its reconstitution properties. It is also frequently desirable to increase the average particle size of the powder, especially spray-dried powders. in order to regulate appearance, density, color and other physical properties of the product. When appearance is of concern such as when a uniformly appearing granular product is desired. it is important that the particles of powder be uniformly wetted prior to or during the actual agglomeration step. This uniform wetting will minimize the presence of fines in and also improve the particle hardness and friability of the agglomerated product.

A high percentage of fines in especially undesirable with food products, such as instant tea or coffee. which are packed in transparent containers. as the fines tend to stick to the inside wall of the container. This considerably reduces the consumer appeal of the product.

Steam agglomeration of powdered materials generally comprises two principal stages. The first of these is wetting, in which the particle surfaces are rendered sticky by the application of moisture, and the second is afterdrying in which excess moisture is removed. During and/or after wetting, the particles are generally maintained under turbulent conditions to promote contact and sticking. Wetting may be accomplished by means of steam exiting through a mozzle. the steam flow from the nozzle intersecting the path of a falling stream of powder. Preferably the powder will be cooled in order to promote condensation on the particle surfaces; this procedure is described in U.S. Pat. No. 3,485,637 issued to Adler et al.

For uniform agglomeration (i.e.. low level of fines) to occur, uniform wetting must be accomplished. It has been found that when using a slot-type nozzle or a plurality of such nozzles, such as depicted in the Sienkiewicz et al. patent, the nozzle does not provide a uniform distribution of steam. Steam exits from the elongated opening of the nozzle in such a manner that the steam flow is greater at the middle of the slot than at the two ends. This non-uniform distribution of steam across the length of the nozzle will produce uneven wetting of the particles. Reducing the width of the powder flow so that powder will only fall through the center portion of the steam flow would significantly reduce the capacity of the agglomeration unit. Increasing the width of the nozzle and steam flow to extend far outside the path of falling powder would be wasteful of steam.

SUMMARY OF THE INVENTION This invention is directed to a slot-type steam nozzle which is designed to provide a uniform steam flow across the entire length of the nozzle. The nozzle is designed to evenly distribute steam flow by controlling passage of steam from a steam header into an elongated nozzle nose section by means of non-uniformly distributed or sized holes which connect the interior of the header conduit with the interior of the nose section. A unique feature of the nozzle of this invention is that the holes at the two outer extremities of thenozzle provide more open area per unit of face length than the holes at the center portion of the nozzle. Although the holes impart a streaming effect to the steam flow exiting from the discharge opening of the nozzle. this problem can be cured by means of a fixed foil member within the nose portion of the nozzle. This foil member forms two divergent steam channels between the faces of the foil and upper and lower nozzle plates. The divergent channels, which are in direct communication with the holes in the header conduit. permit gentle expansion of steam within the nozzle nose prior to discharge and insure-a smooth, nonturbulent and uniform flow of steam through the discharge opening of the nozzle.

The upper and lower nozzle plates will usually constitute the top and bottom portions of the nozzle nose section; however, it would be possible to employ separate plates within a nozzle housing as the members which form the divergent channels with the fixed foil member. The plates will usually be tapered down toward the discharge end of the nozzle and be adjustable so that one plate can be set to lead or trail the other plate. thereby imparting an upward or downward direction to the steam jet. Extension or retraction of both the plates could also be used to slightly vary the size of opening between the two plates.

The fixed. preferably tear drop-shaped. foil member will extend across the entire length of the nozzle nose between the upper and lower plates and will provide tapered or inclined surfaces which diverge from the surfaces of the upper and lower plates. Typically the foil will be shaped such that a tapered or narrow edge of the foil will be adjacent the discharge end of the nozzle. It will be apparent to those skilled in the art, however. that a different arrangement would be possible. The critical requirement of this invention being only that two divergent steam channels are provided within the nozzle nose section. V

The holes or apertures which are provided in the header conduit for passage of the steam into the nose section are. as previously indicated, not uniform across the entire length of the nozzle, the aperturestoward the two sides of the nozzle being either larger or more numerous than those at the center of the face. Typically the apertures will be circular holes arranged across the center line of the nozzle nose, although other arrangements would, of course, be possible. Most preferably the holes will be located in the header conduit and will be uniformly spaced across the nozzle. but varying in size. such that larger diameter holes are present at the outer extremities and smaller diameter holes are at the center portion.

Although it will be possible to have the holes continuously increasing in size from the center of the nozzle nose section to the two ends, such that each adjacent hole is larger than the preceding hole. it will be sufficient that the holes in the outer one-sixth section of the nozzle be larger than the holes in the middle-half section of the nozzle.

DESCRIPTION OF THE DRAWINGS nozzle taken along line 33 of FIG. 1.

FIG. 4 is a partial. front elevation view. in section. taken along line 4-4 of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The features of the invention which are believed to be novel are set forth with particularity and distinctly claimed in the'claims which constitute part of this disclosure. The invention. however. both as to its organization and operation may be best appreciated by reference to the following description when read in connection with the drawings.

Referring to FIG. 1. the components which form a nozzle assembly for uniformly distributing a flow of steamto. a curtain of falling soluble powder (e.g. soluble coffee) which is to be agglomerated is set forth. It will be readily appreciated by those skilled in the art 'th at th'e nozzle of this invention may be employed for other uses. wherein a uniform flow of fluid across the length of a nozzle is desired. The elongated nozzle 1 is equipped with a steam manifold 2 which supplies steam to both ends of the'nozzle at ports 4. Of course. other arrangements for supplying steam to the nozzle will be possible. Mounting fixtures 3 may also be attached to the nozzle to facilitate the incorporation of the nozzle into an agglomeration apparatus (not shown). The elongated nozzle.l composed of two principal sections. namely. aheader conduit 5 and a tapered nose sectionb. l I r The nose section is formed of two side walls 7 and upper

lower plate members

9 and 10. The plate members are preferably aligned or carried by side walls 7 suchas by a side wall shoulder portion most clearly illustrated inFlGS/l and 4.

As illustrated in FIGS. 2 and 3, the nose section 6 of the "nozzle" isprovided with a tear drop-shaped foil 'niember' '8-g depicted here as a hollow member. and upper

and'lower face plates

9 and 10. Upper and lower

divergent steam channels

11 and 12 are formed betweenthe foil Sand the upper and

lower plates

9 and 10. The plate members 9 and are adjustably secured to the header conduit 5 of the nozzle by means of fassection 6 of the nozzle. As illustrated in FIG. 2, the header conduit is provided with 29 equally-spaced holes distributed across the length of the nozzle along the center line'of the nozzle nose section, i.e.. equally spaced between the upper and bottom plate members 9 and "10. The outer holes 16 at each end of the nozzle header and/or nose sections will be larger than the holes 17 located in the middle of the nozzle.

FIG. 4 depicts a preferred manner of assembly for the various members included in the nozzle nose section, specifically showing

plates

9 and 10 contacting a shoulder portion of the side wall 7.

It has been found that the area for steam flow through the nozzle of this invention should be reduced both when the steam flows from the header conduit into the nose section and again when the steam enters into the two divergent channels. Thus the crosssectional area of the header conduit will be greater than the total area provided by the spaced-apart holes. and this hole area will be greater than the initial steam flow area provided by the two divergent channels. Typically the steam flow area is reduced by at least about 25% during passage into the nose section and by at least about 20% during passage into the divergent channels. Preferably steam flow area increases by at least two-fold during passage through the divergent channels.

In operation a uniform distribution of steam was provided by the nozzle depicted in the Figures, having a header conduit of4 inch 0D. (1 1.04 sq. in. steam flow area) stainless steel tubing which contains 29 steam holes with 13/16 inch center spacing. the six outer holes on each side having a /8 inch diameter and the 17 central holes having a 9/16 inch diameter (7.907 sq. in. total hole area). A tapered nose section. 23 /2 inches in length. extends from header to a distance of 7 inches. This nose section contains a tear drop-shaped foil and provides two divergent steam channels for the flow of steam. Each of the channels has an initial slit thickness of one-eighth inch (5.875 sq. in. total steam flow area for both channels) and diverges to a thickness of five/- sixteenth inch (14.688 sq. in. total steam flow area). Using various steam flow rates. steam impact readings. measured in inches of water. were taken at a distance of 2 inches from the discharge opening across the length of the nozzle at equal spacings. The following data was obtained:

Steam These readings were considerably improved over conventional nozzles having slot-shaped discharge openings where impact readings across the length of the nozzle were found to vary by up to or more. As a result of more uniform wetting, agglomerates produced from ground. spray-dried coffee were found to be significantly harder and less friable when using the nozzle of this invention rather than conventional. similarly-size. slot-type nozzles.

Having thus described the invention what is claimed 1. An elongated steam nozzle for agglomerating soluble powder comprising in combination;

a. a header conduit through which steam exits into a nozzle nose section. said header provided with spaced-apart holes which extend across the length of the nozzle. said holes providing more open area per unit of length at the two outer extremities of the nozzle than at the center portion. and

3,878,991 6 b. a fixed foil member within the nozzle nose section. shaped.

extending the entire length of the nozzle. and 4. The nozzle ofclaim 2 wherein the nozzle plates are which forms two divergent steam channels between adjustable plates within a nozzle housing. the faces of the foil and upper and lower nozzle 5. The nozzle of claim 4 wherein the holes in the plates. said channels diverging in the direction of 5 header conduit are equally-spaced circular holes dissteam flow and permitting gentle steam expansion tributed across the center line of the nozzle nose. the within the nozzle immediately prior to discharge. outer holes having a larger diameter than the center and said channels being in direct communication holes. with the holes in the header conduit. 6. The nozzle of claim 5 wherein the holes in the 2. The nozzle of claim 1 wherein the fixed foil memn outer one-sixth sections of the header conduit are her is tapered in the direction of the discharge face. larger than the holes in the middle-half section.

3. The nozzle of claim 2 wherein the foil is tear drop-

Claims

1. An elongated steam nozzle for agglomerating soluble powder comprising in combination; a. a header conduit through which steam exits into a nozzle nose section, said header provided with spaced-apart holes which extend across the length of the nozzle, said holes providing more open area per unit of length at the two outer extremities of the nozzle than at the center portion, and b. a fixed foil member within the nozzle nose section, extending the entire length of the nozzle, and which forms two divergent steam channels between the faces of the foil and upper and lower nozzle plates, said channels diverging in the direction of steam flow and permitting gentle steam expansion within the nozzle immediately prior to discharge, and said channels being in direct communication with the holes in the header conduit.

2. The nozzle of claim 1 wherein the fixed foil member is tapered in the direction of the discharge face.

3. The nozzle of claim 2 wherein the foil is tear drop-shaped.

4. The nozzle of claim 2 wherein the nozzle plates are adjustable plates within a nozzle housing.

5. The nozzle of claim 4 wherein the holes in the header conduit are equally-spaced circular holes distributed across the center line of the nozzle nose, the outer holes having a larger diameter than the center holes.