US2383694A - Method for drying materials - Google Patents

Description

Aug- 28,,1945- J. E. STEINER 2,383,694.

, METHOD FOR DRYING MATERIAL Filed Sept. 15, 1942 2 Sheets-Sheet 1 I5 I 21 4 CHARGE 7 DISCHARGE 5 i 5 J a t i a J h @QQQGQ A Jo/m E. Sfe/ner INVENIOR.

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ATTORNEY Auig- 1945- J. E. STEINER 2,383,694

METHOD FOR DRYING MATERIAL Filed'Sept. 15, 1942 2 Sheets-"Sheet 2 8 INVENTOR.

' BY W h-QXM ATTORNEY Patented Aug. 28, 1945 2,383,694 METHOD FDR. name. MATERIALS John E. Steiner, Cambridge, Minn, assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware Application September 15, 1942, Serial No. 458,416

3 Claims. (01. 18-48) This invention relates to a method for drying materials of various kinds and, more particularly, to a method for drying materials of the wet-solids type, such as, curd in the manufacture of casein.

Wet-solids, as they usually come to a drying machine, are in extremely poor form for either eflicient or uniform drying. The most common forms are lumpy masses, large slabs of filter cake, or broken filter cake with particles of widely varying sizes. In any of these forms there is very little surface area exposed in proportion to the total mass of material. As a result, drying is a slow process because evaporation of moisture from the material can take place only at the exposed surface. The variation in the sizes of the units or pieces of material results in a lack of uniformity in drying. Where this variation in size is great, the drying problem is complex, and the time of drying cycle is increased in order to sumciently dry the largest of the various units.

Furthermore, in the drying of material wherein tralized. These packed areas under the same pressure of drying medium as the unpacked areas, ofier considerably more resistance to the passage of the drying medium therethrough. As a result, holes are blownthrough the areas of least resistance and the drying medium passes therethrough without eflectively contacting the other areas. This, of course, causes uneven drying and wet spots in the layer of treated material.

An object of this invention is the provision of a method for conveying material in layer form of predetermined thickness through a drying chamber without substantially disturbing the thickness of the layer and with scoring of the layer to insure the uniform passage of drying medium therethrough.

Another object of this invention is the provision of a method for conveying material in layer form through a portion of a drying char and then reducing the layer of material into individual units of a predetermined size and conveying said individual units through a remai portion of the drying chamber.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

Generally described, the present invention provides a method of continuously drying wet-solids material which comprises distributing the material in a layer of uniform depth and scoring the distributed material to permit a dryingmedium to be freely circulated therethrough.

A preferred embodiment of the invention has been chosen forpurposes of illustration and description and is shown in the accompanying drawings forming a part of the specification wherein reference symbols refer to like parts wherever they occur.

. Figure 1 is a diagrammatical vertical sectional view taken lengthwise of the run of the conveyor, of one form of apparatus for the embodiment of the invention. Figure 2 is an enlargedsectional view taken along the section 2-2 of Figure 1; Figure 3 is a front elevational view of a comb for channeling material, with the material and the conveying belt shown in section; Figure 4 is a sectional View taken along the section M of Figure 3; Figure 5 is a front'elevational view of two reciprocating combs for uniformly channeling material, with the comb-supporting members, the material, and the conveying belt shown in section; Figure 6 is a fragmentary plan view of Figure 5; Figure 7 is a sectional view en along the section l-l of Figure 5; Figure 8 is a fragmentary plan view of finger-like members for engaging partially dried layer material and reducing it to individual units; and Figure 9 is a v sectional view taken along i i-t of Figure 8.

In Figure 1, Figure 2, Figure 3, and Figure d a drier l of conventional design has an endless conveyor belt t'of open mesh top extending therethrough. The conveyor belt 3 is preferably of the sectional type with continuous side guards and with sections oi the mesh fastened to and carried by roller chains at the sides. This type conveyor permits but very little sag in the individual sections of the conveyor belt. A material 5 to be dried is charged in a layer of uniform depth, by suitable means (not shown), upon the conveyor belt 8. This material is progressed by the conveyor belt and encounters a comb "5 provided with a plurality of teeth t. The comb l is rigidly amxed to the bench la of the drier l or other suitable supporting means so that the lower extremity of the teeth 9 barely clear the top surface of the t combs 55 and through the layer of material, without creating any "blows." This same air then goes backto the fans and the cycle of recirculation is continuously repeated, as represented by the arrows l5, during-the passage of the material 5 through the drying chamber I3.

From the drying chamber 13, the material 5 passes into drying chamber 2! which has motordriven fans and steam heaters i'I disposed below and above, respectively, of the conveyor belt 3. Circulation is similar to that discussed above for chamber It, with the exception that the direction of flow of the air is opposite, as represented by the arrows 23. By the time the mate rial 5 enters the chamber 2|, it is partially dried and becomes somewhat brittle and as the material continues to pass through chamber 2 I, the material encounters a plurality of finger-like members 25 (see Figures 1, 8, and 9). These members are supported by rods 21 which in turn are rigidly secured to the sides of the drier lb, or other suitable means. The members 25 are inclined, having their lower extremities in proximity to the top of the conveyor .belt 3, so that the partially dried material 5, upon encountering the members 25, rides thereupon, causing the material 5 to be broken into units of substantially uniform size (see Figure 9). The material 5 is thereafter treated in the form of individual units in the remaining portion of the drying chamber 2| from which it is discharged in the conventional manner.

Referring now more specifically to Figures 5, 6, and 7, another embodiment of'the invention is presented for positively reducing a material to be dried into individual units of uniform size. A comb50 and a comb 52 are slidably aflixed to the bench la of the drier l or other suitable means. These combs 5D and 52 have a plurality of teeth 54 and 56, respectively, the lower extremity of which barely clears the top surface of.the.conveyor belt 3. The combs should be preferably in spaced relationship, as shown, because if the teeth of the comb or combs are too closely spaced a piling up of material will result, thereby destroying uniformity. The slidably affixed combs 50 and 52 are actuated with a reciprocative movement by earns 58 and 50, and cams 52 and 54, respectively. The earns 58 and 52 are rigidly secured to a drive shaft 56 and the cams and 54 are rigidly secured to a drive shaft 58. These drive shafts may be driven from a separate source of power or may \be driven in association with the driving mechanism for actuating the c veyor belt 3. The reciprocative movement of 52 may also be accomplished by providing protrusions on the apron of the conveyor belt 3. The specific means for reciprocating the combs does not constitute a part of this invention, as such expedients are obvious to those skilled in the art, however, the particular arrangement of the combs to. achieve a uniform scoring or channeling of the material to be dried does constitute a part of this invention. In this respect, the teeth 550i comb 52 channel the material 5 as it advances, as represented by the arrow 15. The teeth 54 of the comb 55, being spaced equidistant and intermediate of the teeth 55, channel the material 5 as it advances, as rep- 2,sea,ec4 I resented by the arrow 12. This combination, in association with the cams 55, 50, 52, and M in synchronous association with the rate of travel developing 'tially throughout of the conveyor belt 3, gives a square-like configuration of channeling (see Figure 6). It is evident that other uniform configurations in the material may be employed, such asan intersecting wave-like configuration depending upon the particular cut of the cams and/or the cyclic method of rotating said cams, but the square-like configuration is preferable from a standpoint of uniformity of moisture travel to the exposed surface where evaporation takes place and a standpoint of ease of breaking the layer of material into individual units. The material 5 having a uniform configuration of scoring or channeling is reduced to individual units in the same manner as set forth above in the description of the preferred embodiment.

For the drying of some materials, it is unnec- I essary to reduce the material to individual units to accomplish effective drying, as the scoring of the material alone will suflice. For example, in the drying of curd for the manufacture of casein a uniform layer of rennet casein was placed upon the conveyor belt 3. The comb 1 had its teeth 9 spaced at one and one-half inch intervals. The curd was progressed through the drier and was scored with longitudinal channels which were found suiiicient to prevent the layer of curd from blows which had occurred when the curd was unscored. For the drying of acid casein it was found preferable to have the teeth 9 spaced at three-fourth inch intervals. In both cases the casein was effectively dried with a high degree of uniformity.

Generally, however, materials of many kinds, such as sulphur sludge, phosphate fertilizer, calcium carbonate, magnesium carbonate, and lime putty, are more efliciently dried by scoring the material and reducing the scored material to individual units for complete drying.

The advantages of the present invention reside in the speed of drying, the uniformity of drying, and the drying of the material in shapes of uniform size, whereby all the shapes are dried perfectly alike.

What I claim and desire to protect by Letters Patent is:

1. A method of continuously drying wet-solids material of a semiplastic nature which is sumciently stiff to retain channels after they have been formed in said material which comprises distributing the material in a, layer of uniform depth; scoring the distributed material substanits depth to form channels therein, and subjecting the scored material to a drying medium under sufiicient pressure to cause passage of said drying medium through the bottom wall of each of said channels.

2. A method of continuously drying wet-solids material of a semiplastic nature which is sufficientlystiff to retain channels after they have been formed in said material which comprises distributing the material in a layer of uniform depth, scoring the distributed material substantially throughout its depth to form channels therein, subjecting the scored material to a drying medium under suflicient pressure to cause passage of tom wall of each of said channels to partially dry the scored material, breaking the partially dried scored material into individual units, and subjecting the individual units to the drying medium to complete drying.

said drying medium through the boting the scored material to a drying medium under sufllcient pressure to cause passage of said drying medium through the bottom wall of each oi said channels to partially dry the scored material, breaking the partially dried scored material into individual units of uniform configuration along said channels, and subjecting the individual units to the drying medium to complete drying.

JOHN E. STEINER.

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