US3387383A - Method and apparatus for removing moisture from material - Google Patents

Description

METHOD AND APPARATUS FOR REMOVING MOISTURE FROM MATERIAL 2 Sheets-Sheet 1 Filed Aug. .1, 1965 REEVES ATTORNEY mm s 1 EEE @523 E ow g quw fi w wp w Llr M Y E 8 mm v0 r7 |IY /7 Y7? A. N m mw mm C. STAMOS ET AL 2 Sheets-Sheet 2 June 11, 1968 METHOD AND APPARATUS FOR REMOVING MOISTURE FROM MATERIAL Filed Aug. 11, 1965 United States Patent 0 3,387,383 METHUD AND APPARATUS FDR REMGVENG MOHSTURE FRUM MATERlAlL Chris Stamos, Chicago, Philip (I. Reeves, Arlington Heights, and flames D. Wander, in, Lombard, lllli., assignors to Roberts & Schaetter iCoinpany, Di vision of Thompson-Starred Company, lino, hicago, 11]., a corporation of llilnois Filed Aug. 11, 1%5, Scr. No. 478,943 1 Claim. (El. El i-90) AESTRAQT GK THE DEELOSURE A method and means for removing moisture from wet material comprising depositing moist material on one side of a filter cloth; subjecting the other side of the filter cloth to sub-atmospheric pressure to remove a portion of the moisture from the material; subjecting the material to high energy sound vibrations; and removing moisture from the air surrounding the material.

This invention relates to a method of and apparatus for removing moisture from material such as coal and other material.

The invention comprehends an improved method and apparatus for dehydrating or drying solid material which includes the use of sonic or ultra-sonic energy in combination with a vacuum filter.

There are numerous types of dryers more or less efiicient and with varying degrees of initial and operating costs. The cost of thermal drying is high in both respects but to date is the only practical means of reducing the moisture content of extremely small size particles to the lower ranges of dryness. Mechanical dryers such as centrifuges, vacuum dryers, etc. will not handle this material and reduce the moisture content to the desired level.

For example, in the drying of coal particles, which have been accumulated after coal has been subjected to a washing or cleaning process, with the use of known vacuum filters it is not possible to reduce the moisture content of the mass below twenty (20) percent; Whereas, it is extremely desirable to reduce the moisture content to fifteen percent or less, without the use of conventional thermal drying means which are expensive.

According to the present invention, a sonic field is provided and positioned relative to the moist material so that the intense, powerful acoustic emissions create a very strong gas turbulence about the liquid carrying particles, and also a succession of compressions and expansions which produces strong surface cavitation. These two actions in part break the surface tension of the moisture, and the whole efiect is to facilitate the flow rate from the particles. The sonic waves also provide energy to induce the flow of liquid from the interior of the particles to the surface from whence it is dispersed into the surrounding atmosphere. Thus, the present invention obviates the disadvantages of prior thermal drying.

It is an object of the present invention to provide improved means for the removal of moisture from wet material in such a quantity as to render it compatible with ease of handling and accomplishing said object in a more economical manner than has heretofore been ace-on plished.

In particular, it is an object of the present invention to dry fine, moist material to lower ranges of moisture content than has heretofore been accomplished without restoring to the use of heat in some manner or form.

Another object of the invention is the drying of moist material by the use of a high energy (sonic or ultra sonic) sound field directed toward the moist material to facilitate 3,337,383 Patented June 11, I968 the removal of moisture (either wholly or in part) from the solid particles.

Another object of the present invention is to provide a means for transporting the moist material into the sound field. A very fine mesh filter cloth is provided for this pur pose and used in such a manner as to dip the filter cloth (carried on a suitable transporter) into a slurry tank containing said moist material. A constantly maintained partial vacuum on one side of the filter cloth draws the moist material onto and retains it in place in the form of a film or cake on the filter media.

A further object of the invention is to provide a means for removing a portion of the water content before the material enters the sound field. To accomplish this end, a partial vacuum is maintained on one side of the filter cloth. This negative pressure causes a portion of the liquid to move through the material being treated, through the filter cloth, and towards the source of the vacuum. The flow of fiuid is intercepted and drained olt in a well known manner.

It is a still further object to provide a means for agitating the moist material so that due to the particles being continually turned over, their surfaces are better exposed to more drying air and sound energy, and thus increasing the flow and evaporation rate.

It is another object to provide means .for the removal of the treated material from the filter cloth at the end of the cycle. According to the present invention, a scraper and/ or a means for providing a stream of compresed air is located at the end of the drying cycle. This equipment removes the dried material from the filter media from whence it is directed to another conveying means that transport it away from the immediate area.

It is again another object to provide means for deflecting the sound waves onto the material to be treated by means of baflle plates so constructed and arranged as to change the direction of the sound approximately 90 degrees.

These and other objects of the invention will be apparent from an examination of the following description and drawings, wherein:

FIGURE 1 is a side elevational view, party in section, of an acoustical-vacutun dryer arrangement embodying features of the invention;

FIGURE 2 is a horizontal section taken on line 2-2 of FIGURE 1;

FEGURE 3 is a vertical section taken on line 3-3 of FIGURE 2;

FIGURE 4 is an enlarged side elevational view of a portion of the structure of FIGURE 1;

FIGURE 5 is a vertical section taken on line 5--5 of FIGURE 4;

FIGURE 6 is an end elevational view, partly in section, of a modified form of the invention;

FIGURE 7 is a fragmentary side elevational view of a portion of the structure illustrated in FIGURE 6; and

FIGURE 8 is an enlarged side view of another portion of the structure of FIGURE 6.

It will be understood that, for purposes of clarity, certain elements have been intentionally omitted from certain views where they are illustrated to better advantage in other views.

Referring now to the drawings for a better understanding of the invention, and particularly to FIGURE 1, it will be seen that the arrangement embodying the invention includes a frame indicated generally at ltl, mounted on a fioor 12, and adapted to support a conveyor mechanism, indicated generally at Id.

The conveying mechanism includes a fine mesh filter cloth to which is supported on and carried by an open mesh transporting or conveyor belt 18.

Conveyor belt 18 is supported on and moved over a plurality of main rollers or pulleys 20, 22 and 24 as well as secondary rollers or pulleys 26 and 28. Pulley 20 is the driving pulley and may be driven by a motor 39 mounted on the frame and connected to pulley by a chain or belt 32.

Still referring to FIGURE 1, it will be seen a tank or reservoir 34 containing a slurry 36 of moist material is mounted at the right hand side of frame it), and that the conveyor mechanism is so mounted that conveyor belt 18 and filter cloth 16 will pass into and out of reservoir 34 as the conveyor mechanism is driven in a counter-clockwise direction.

As filter cloth 16 is carried through tank 34 on conveyor belt 18 it picks up an accumulation of the slurry of moist material on its upper surface.

Supported on frame 10 immediately forward of the place where the filter cloth passes out of reservoir 34 are a pair of vacuum tanks 40 disposed immediately under the conveyor belt 18 of the conveyor mechanism, so that the belt will slide over a relatively flat, perforated, grill plate or cover plate 42 on each tank 40.

The interior vacuum tanks 40 are connected by vacuum lines 44 to a vacuum pump (not shown) so that a subatmospheric pressure can be provided in the vacuum tank as a result of this sub-atmospheric pressure a substantial amount of moisture is withdrawn from the wet material deposited on the filter cloth in reservoir 34. This water may be drained from the tank 40 by the drain pipes 46. In actual practice the moisture content of the material can be reduced by this vacuum-filter operation to approximately twenty-five percent As the moisture is withdrawn from the material the particles of the material on the filter cloth tend to cohere to each other to form a solid mass or filter cake 38, as best seen in FIGURE 4.

While the filter cake 38 is still on the conveyor filter cloth and over a vacuum tank it is subjected to high energy sonic or super-sonic vibrations from one or more high energy sound generators 62 which may be supported on upper frame 60 and which are mounted directly adjacent, and preferably above, the filter cake.

These vibrations greatly increase the amount of moisture removed from the filter cake in two ways. The vibrations tend to break the surface tension which holds the moisture on the surface of the individual particles of the moist material so that it can be withdrawn. Also, the vibrations create cavitation-like action whereby the minute air bubbles in the moisture surrounding the individual particles of moist material collapse with an impulsive force that causes severe agitation of the particles and surrounding moisture to free up more moisture which is withdrawn.

In order to increase the amount of dehydration which is taking place, it is often desirable to further agitate the moist material and to break up the filter cake into smaller particles and to subject the material to further treatments of high energy sound vibrations.

This is accomplished by an agitating and/ or crushing device, indicated generally at 64, which includes a plurality of plows 70 arranged in a row extending transversely across the filter cloth of the conveyor mechanism and also a plurality of crusher rollers 72 spaced from each other transversely across the filter cloth and supported on a shaft 74 carried by the frame 10.

To facilitate the carrying away of the moisture from the material there may be provided over the agitating devices 64 one or more hoods 66 which are connected by ducts 68 to exhaust fans (not shown).

To further increase the extent of the dehydration of the moist material, the apparatus may include additional sets of sound generators 62 and agitating devices 64 alternately disposed in series over the conveyor mechanism.

It has been discovered that by use of the high energy sound generators and/or the agitating devices in combination with the vacuum-filter mechanism it is possible to re duce the moisture content of the material to within the range of approximately ten to fifteen percent (10%15%) of moisture content. Dehydration of moist material to this extent without loss of the fine (minus 150 mesh) materially, has not been possible without the use of thermal dehydrating means which is hazardous, expensive to operate and maintain, and which contributes heavily to air pollution especially when the dryer is subjected to reducing moisture of material of this size range.

After the dehydrated material has passed by the vibration and agitating stations it is deposited by the conveyor mechanism into a collecting bin 48 which is located at the forward end of the conveyor mechanism remote from res ervoir 34.

If it is desired to clean the filter cloth before it enters the reservoir, it may be subjected to an air or water bath by the cleaning apparatus 5b which is carried by frame 10 immediately adjacent reservoir 34-. Cleaning apparatus 50 includes an air or water spray nozzle 52 disposed over a portion of the conveyor mechanism, which at this point is upside-down with the filter cloth below the conveyor belt, and a tank 54 having a drain 56.

Thus, it will be seen that the invention provides a fully automatic method and apparatus including vacuum-filter, high energy sound vibrations, and mechanical agitation which in combination with each other produce a degree of dehydration not heretofore available without the use of some type of thermal treatment.

Turning now to FIGURES 6-8 of the drawings, it will be seen that a modified form of the invention is shown. Although this embodiment performs the same operations and utilizes the same principles of operation as the previous embodiment, the vacuum-filter portion apparatus of this embodiment is in a different form.

As seen in FIGURE 6, the vacuum-filter mechanism is a disc type filter arrangement which includes a tank or reservoir 100 containing a slurry 102 of moist material to be dehydrated.

Rotatably mounted at its ends in the reservoir 100 is a horizontally disposed hollow shaft 104 which may be driven by a motor 106 through a chain or belt 108.

Mounted on the shaft for rotation therewith in a vertical plane are a plurality of disc filters, indicated generally at 110, each of which includes a hollow disc 112 having perforated side plates 114 on the outsides of which are carried filter cloths 116. The interiors of the discs are open to the interior of shaft 104 which is connected by a vacuum line 118 to a vacuum pump (not shown).

The disc-filters operate in the same manner as the vacuurn-filters of the previous embodiment. As a sub-atmospheric pressure is created within the discs the moist material is drawn against the outside surfaces of the filter cloths and a portion of the moisture is drawn into the disc and may be withdrawn through the same line 118 that is connected to the vacuum pump.

As the material builds up on the filter cloths of the discs it forms a filter cake 119 which is subjected to high energy sonic or supersonic vibrations by the sound generators 120 disposed over and at the sides of the disc filters.

In order to direct the sound energy directly toward the flat surfaces of the discs there may be non-rotatably mounted over the shafts, between adjacent filter-discs, bafile devices, indicated generally at 122, each of which includes a post or column 124 having a plurality of inclined baflle plates 126 mounted thereon.

In order to remove the filter cake from the filter-discs there may be provided a scraper device or doctor blade 130 which both removes the filter cake from the filter cloth and, where desired, deposits it on -a conveyor mechanism of the type disclosed in FIGURE 1 where it may be subjected to further sonic vibration and agitation treatment in the same manner as was described in connection with the previous embodiment of the invention.

We claim:

1. Apparatus for removing moisture from wet material,

comprising in combination:

(a) a reservoir for retaining a slurry of moist material;

(b) an endless conveyor mechanism passing into and out of the reservoir, including:

(i) an open mesh conveyor belt; (ii) a filter cloth carried on said belt;

(c) at least one vacuum tank disposed immediately under said conveyor mechanism at a location forward of the place where the conveyor mechanism passes out of said tank;

(d) vacuum means connected to said tank operable to produce a sub-atmospheric pressure therein and thereby draw a portion of the moisture from said material, as it passes over the tank, through said cloth and belt and into said tank;

(e) sound producing devices disposed over said conveyor mechanism at a plurality of locations, spaced forward of said vacuum tank, for directing high energy sonic vibrations toward the material;

(f) material agitating means disposed over said con veyor mechanism adjacent said sound producing devices for breaking up said material, which has caked, into small particles to expose greater surface areas thereof for cooperation with said sound producing devices.

References Cited UNITED STATES PATENTS 583,361 5/1897 Droeshout 34-69 X 2,452,983 1 1/1948 Birdseye. 2,490,176 2/ 1949 Tomlinson et al. 2,720,315 10/1955 Peterson 21919 2,963,158 12/1960 Jung 210 19 X 2,996,808 8/1961 Fleissner 34-60 FREDERICK L. MATTESON, JR., Primary Examiner.

D. A. TAMBURRO, Assistant Examiner.

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