US2307995A - Drying apparatus and method - Google Patents

Description

Jan. 12, 1943. w; DAVEY 2,307,995

DRYINGAPPARATUS AND METHOD Filed Feb., 13, 1940 ATTORNEY Patented Jan. 12,

UNITED STATES p PATENT OFFICE DRYING APPARATUS AND METHOD Warren Davey, Montclair, N. .L, assignor to C01- gate-Palmolive-Peet Company, Jersey City, N. J., a corporation of Delaware Application February 13, 1940, Serial No. 318,669

8 Claims.

This invention relates to a new method of drying material which is undesirably affected by usual drying temperatures, particularly when maintained at those temperatures for an appreciable period of time; and to apparatus for'carrying out this invention. This invention more particularly relates to a novel method of dryin material of the organic detergent type such as salts of organic sulphonic and organic sulphuric acids.

Soaps and organic detergents other than in bars or cakes are generally prepared in two forms: small particles, as powders and beads, and flakes or chips. The former ismade by spraying and similar types of drying, whilethe latter is produced by many variations of drying which usually involve depositing a solution or slurry of the material on a smooth surface where it is dried by removal of all or a substantial quantity of the liquid, and removing the dried sheet or flake from the surface.

The production of detergents in flake, chip or sheet form is commonly achieved by means of drying rolls such as drum dryers.

The conventional type of drum dryer consists of a revolving hollow roll, mounted on trunnions at each end. Steam is admitted to theinterior of the roll through suitable stufiing boxes at the trunnions, with provision for the removal of con densate. By varying the steam pressure within prescribed limits, the roll may be heated to a desired temperature. Liquids, pastes, solutions, suspensions, etc., to be dried are fed onto the roll in a relatively thin film by various methods; such as having a roll partly immersed in a tank containing the liquid to be dried, wherein the revolving roll will pick up a film, or by spraying or otherwise depositing the liquid to be dried directb onto a roll or rolls, or, in the case of a double set of rolls running in opposite directions, the liquid to be dried is fed down between the rolls, and the thickness of film is adjusted by spacing the rolls the proper distance apart. By

ture of the surface of the roll.- It not infrequently happens that this relatively high temperature is detrimental to the finished product, and means must be provided to cool the-dried material immediately in order to avoid undesirable consequences. Especially is this true of the new type detergents such as organic sulphonates and sulphates, which may undergo decomposition, become darker in color, or otherwise be rendered less desirable for sale or use as a domestic or industrial commodity. If this heated material is collected in bulk at a temperature near that at which it leaves the drying surface, it will not, in many cases, be cooled soon enough to prevent decomposition, darkening or other .consequences incident to such continued heated condition.

In the case of some kinds of soap or waxy materials, the film instead of being scraped off in chips or sheets has a tendency to roll up into a scroll and falls oflf only when it breaks loose of its own weight. These scrolls may be relatively large and quite compact, and will retain their heat for a considerable time and are therefore difiicult to cool quickly. Again, some materials retain their waxy consistency until quite cool, which condition prevents their breaking up into small particles which are usually desired.

Not infrequently material being dried adheres to the knife or scraping element, which, because of the high temperature to which it is heated by contact with the roll, decomposes or chars the adhering material. This charred material breaks off when a large quantity is accumulated, thus contributing to an undesirable product.

The applicant has found that a jet or strong current of air directed toward the scraping edge of the knife not only prevents the rolling up of th film into a scroll but also removes a substantial amount of heat therefrom.

varying the speed of the roll, the steam pressure and the thickness of the film,-a desired speed of evaporation of the liquid may be obtained, and

' this may be controlled within close limits. Thus a final product of practically any desired moisture content may be produced.

As the roll revolves the liquid content of the material rapidly evaporates leaving the solid portlon sticking to the roll which is scraped off'by means of a suitable knife or other device. This film which in most cases is exceedingly thin, acquires a temperature approaching the tempera- On some dried materials the product thus removed comes ofi in thin sheets several inches wide along the full length of the knife. These large thin sheets fioat in the air stream; and due to their physical condition cool very rapidly.

They are also so light and fluffy as to be readily conveyed in the air stream for a considerable distance, thereby effecting further cooling and facilitating conveyance to any desired location. This cooling may be regulated by themethod of this invention to reduce the temperature of the dried material to a degree at which it is safe to collect the product in bulk without danger of undesirable consequence from storage.

This inventionv also serves to prevent the accumulation of material at or on the scraping knife or element, thus preventing or inhibiting the charring incident to such collection and further contributing to a more salable and efiicient product.

With a proper regulation of air supply and air stream velocity, with a possible precooling of the air, the dried product may be delivered to the deextending the full length of the knife directs a stream of, air toward its scraping edge, .thereby lifting the ribbons, flakes or chips from further contact with either the roll or knife. By varying the width of the slotted opening and air supply, any desired velocity may be obtained at the jet, and the desired cooling obtained.

' The above description illustrates the principle involved, but some slight modifications may be advantageous in adapting it to a commercial apparatus.

Figures 2 and 3 show a simple modification of the device, wherein it is desired to remove and cool the product and drop the material into a hopper or onto a conveyor belt.

Figure 2 is a view of the apparatus looking toward the drum drying roll and Figure 3 is a cross section through the plane XX of Figure 2. In Figures 2 and 3, Iv is the drum dryer roll carrying the drying film 2. The scraper or knife 3 removes the ribbons, flakes or chips 4 as the roll passes under it. The slotted orifice 5 extends the full length of the knife and is supplied with air by means of plenum chamber 6. which is formed by the front and back. curved members I and 8 andends I. Air is supplied to the plenum chamber by means of pipe I from a suitable blower (not shown) or other source. The curved deflector ll reverses the'upward flow of the air'and delivers the dried ribbons or chips downwardly over the curved member 1, which acts as a chute or slide where they drop either directly into a hopper or onto a conveyor belt.

A further development of the apparatus may be made by completely enclosing the chute or slide and converging the sides into a vertical pipe of suitable size. The air and flakes or chips are then conveyed into this pipe and may be carried to any desirable receptacle without further handling.

Figures 4 and show such an arrangement. Figure 4 is a view looking toward the drum dryer roll and Figure 5 is a section through the plane YY. In Figures 4 and 5, I is the drum dryer roll carrying the drying film 2. The scraper or knife tremoves the ribbons or flakes l as the roll under it. The slotted orifice 5 preferablyextends the full length of the knife and is supplied with air by means of plenum "chamber 6 which is formed by the front and back curved members I and 8 and ends 9. Air is supplied to the plenum chamberby means of pipe N from a suitable blower (not shown). The air and flakes are confined in the discharge chute by means 9f cover I: and sloping en'd pieces lt, which taper down to the pipe i4. Pipe may be extended, thus conveying, theproduct to any'desired point. In the'above arrangement each; assumes a otted orifice suppliedwith air under moderate" pressure. A further method and arrangement of carrying out the principles of this invention may be accomplished by means of an induced current of air at the slotted orifice. Figures 6 and .7 show a desirable arrangement for employing this method. Figure 6 is a view looking toward the drum dryer roll and Figure 7 is a section through the plane ZZ of Figure 6. in Figures 6 and 7, I is the drum dryer roll-carrying the drying film 2. The scraper or knife 3 removes the ribbons or flakes 4 as the roll passes beneath it.

The device for removing, cooling and conveying the flakes comprises pipe i5. This pipe is slotted along one element at l6 and formed so that one edge I! is in contact with the knife, just above its scraping edge along its entire length, and the other edge I8 is formed to produce a suitableaperture or slot. The roll acts as one surface and the edge 18 of pipe l5 as the of air in the form of a jet to impinge on the roll at or near the toe of the knife. The ribbons, flakes or chips are thus removed and are carried into the pipe along with the air stream in pipe l5 and may be delivered to any desired point, either by passing the air and flakes directly through the exhaustfan, or by interposing a suitable separator collector (not shown) ahead of the fan. a

The opposite end 20 of the pipe I5 may be fitted with a damper or adjustable opening to allow additional air to enter the pipe, thus imparting a longitudinal motion thereto. 7

This air may also be precooled to augment the cooling required if deemed advisable.

Although the above illustrations, for sake of simplicity, show only one dryer roll, the invention is not so limited. A plurality of rolls may be employed in many arrangements and the device and method disclosed hereinbefore applied to any or all of the rolls.

Although in the apparatus depicted for carrying but the process of this invention only rolls are shown for drying, both the process and apparatus may be readily modified to include other means for dryin such as a traveling belt or other drying surface. With an understanding of this invention, adaptation to any drying surface will be within the province of a skilled mechanic.

The above embodiments or any other modifications of the present invention may be used alone or in any combination. The cooling medium, ordinarily, is air because ofthe cost factor.

However, when working with materials sensitive to oxidation, other gases, such as carbon dioxide,

nitrogen or cooled waste flue gases, or mixtures thereof, may be employed. In such cases it may I be desirable to exclude air from the drying operdirecting a current of a relatively c001 gas against the material at the point of removal to aid in the removal and to effect a reduction of the temperature of the material.

2. A method of drying organic material which comprises-depositing a slurry of said material upon a heated drying surface and after a portion of the liquid of the slurry has been evaporated but before the organic material has been adversely affected by heat from the drying surface, mechanically removing said material from the drying surface and blowing a current of air against the material at the point of removal to aid in removal and to cool it. r

3. A method of drying organic materials which comprises forming a film of a slurry'of said organic materials on a drying surface, causing asubstantial portion of said liquid to evaporate,

and mechanically removing said material from.

the drying surface while blowing the material at the point of removal from the drying surfaoe'wi'th a current of relatively cool gas whereby the material is cooled as it is removed.

4. A method of dryingjorganic material which is deleteriously aifected 'by continued high temperatures which comprises depositing a slurry of the material upon a drying surface, heating said drying surface, and removing 'said material from said drying surface by the co-action of doctor blade means and a current of air blown against the material at the point of removal, after a por-- tion of the liquid has been evaporated.

5. A method of removing a substantially dried material from a drying roll and simultaneously cooling said material which comprises scraping the material from the drying roll and directing a jet of air against the roll at the point where the material is being removed from the roll.

6. A method of drying organic sulphonate detergent material which comprises depositing a slurry containing said material and a liquid onto a drying roll, causing a major portion of said liquid to evaporate from the material, and mechanically removing said material from the drying roll while aiding said mechanical removal by blowing the material on the roll with a current of relatively cool air at the point of removal, whereby the material is cooled as it is removed.

7. The process of drying heat-sensitive organic detergent material which comprises depositing a film ofsaid material and water upon a drying roll, .causing a portion of the liquid to be evaporated physically assist in the removal of the dried material from the drying surface and to reduce the temperature of the material.

WARREN DAVEY.

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