USRE23608E

USRE23608E - Sheetsxsheet i

Info

Publication number: USRE23608E
Authority: US
Priority date: 1948-10-08
Publication date: 1952-12-30
Also published as: US2578355A

Description

Dec. 30, 1952 A. A. HOLLAND DEHYDRATION 0F MINERAL sALTs AND THE LIKE 2 SHEETS--SHEET 1 Original Filed Nov. 3, 1948 Dec. 30, 1952 A. A. HOLLAND Re 23,608

DEHYDRATION 0F MINERAL sALTs AND THE LIKE:-

original Filed Nov. s, 1948 2 SHEETS- SHEET 2 BMM #Horn ey,

Resaued Dec. 30, 1952 DEHYMDRA'I'IOIT` OF MINERAL SALTS AND THE LIKE Arthur A. Holland, Pensacola, Fla.

Original No. 2,578,355, dated December 11, 1951,

Serial No. 58,097, November 3. 1948. Application for reissue June 19, 1952, Serial No. 294,525. In Canadav October 8, 1948 s claims. (c1. 15s- 2) Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to the dehydration of salts in aqueous solution and is particularly directed to the treatment of salts, Alike sodium sulphate, which melt in their own Water of crystallization.

Many methods have been proposed for the extraction of sodium sulphate from its naturally occurring aqueous solutions but-there are difficulties in the economical extraction of the salt. Much heat is required and the caking of the salt on the walls and other parts of the drier offers diiliculty and adds to the cost of the operation.

The object of the presentinvention is to providean improved method and apparatus for vdehydrating of such salts. While the invention is particularly described with ,reference to the ex-v traction of sodium sulphate it will be ajgnparent` that it is useful for dehydrating other materials and is to be so interpreted.

It has been found that the encrusting or caking of the salt on the drying equipment as well as the evaporation, and thus the efficiency of the procedure, is largely determined by the particular manner in which the body of salt solution is handled and the particles thereof. projected into f the drying atmosphere.

The invention will be described with reference to the accompanying drawings in which Figurel is a side elevation in section of the apparatus,

Figure 2 is a plan view in section,

Figure 3 is an end elevationin section, and

Figure 4 is an end elevation offtlie spray de- In the drawing, I represents a drying chamber having the confined zone 2 and the larger zone 3 in communication through the opening 4. The brinefeed inlet is at 5 and the hot gases inlet at 6. A spray device 'I is located longitudinally of zone 2 and preferably at each side-thereof as best shown in Figures 2 and 3. Located between and parallel with the spray devices is a scraper conveyor 8 mounted on a sprocket 9 carried by a shaft I driven by the pulley I3 and ,a tail sprocket II on the shaft I2. Scrapers I4 are carried by the conveyor. The spray zone 2 is vertically oonfined by the top wall I which is curved downwardly at its forward end to the outlet passage 4 leading to the larger expansion zoned in the rear end of which is the drainage* battle I5. The

height of the expansion zone is preferably twice that of the spray zone. K

The spray device, two of which are used in the form shown in Figures l, 2 and 3, comprises a drum IT mounted for rotation on a driven shaft I8. Circumferentially arranged on the drum are spiral blades I9 and between the adjacent blades is formed a series of cup-like compartments 20 by means of the transverse walls 2|.

At the outlet end of the drier the conveyor 8 discharges over the upwardly inclined ramp 22 and lip 23 into a collecting chamber .24 in which is a discharging conveyor 25, 261s the outlet for the expansionvchamber 3 through which. vapors are exhausted.

In operation the'material to be dried is fed into the drying .chamber through the inlet conveyor 5.. preferablyat a rate to'provide a liquid level below the surface of the drum 1 on which the spiral blades and cup-like compartments are arranged. The amount of liquid Apicked up` by each cup-like .compartment in the spray device and the speed at which the spray device is rotated determines the size of the sprayed liquid particles andthe extent to which caking or encrustation of the salt is prevented within the conned spray zone. 'I'his cup-like arrangement of the spray device provides a relatively coarse rain-like spray which is much more effective in preventing caking than a iine spray, such as that delivered by a drum revolving in contact with the solution. It has been found that when the linear velocity of solution leaving the cups is at least 8,000 feet per minute encrustation is effectively` prevented by use of this spraying device. The actual velocity varies with the size of the confined.` spray chamber as this affects the distance the, sprayed particles have to travel to contact theA wallsqof the chamber. Hot gases passedinto the spray chamberpick up the moisture from the sprayed particles and carry it through the,v expansion zone 3 to the exhaust outlet 2E. ,Because ofthe reduced rate of travel through.. the .expansion zone mechanically sus'- pended particles of solution are segregated and rain back-into the mass under treatment.

As the solution is concentrated the salt crystallizes out and is continuously removed by the scraper conveyor and discharged from the drier, thus avoiding the tendency for it to redissolve in the remaining mass. The drying gas used may be from direct fired burner or the exhaust gases from other source.

This manner of spraying the mass to be dried and of vcirculating the drying gases is found efcientlyto utilize the heat energy in the drying gaseous medium as indicated by the fact that the temperature of the exhaust gases is normally not more than 20 higher than that of the solution being sprayed.

It will be apparent that the spray device may be used in other specific forms of the drying chamber.

What is claimed is:

1. Dehydrating apparatus comprising a-drying chamber, a spray device mounted longitudinally of the chamber at each side adjacent the bottom thereof, said spray device comprising a rotatably mounted drum, a. spiral blade mounted longitudinally on the drum, and a plurality of the transverse wallsI between adjacent flights of the blade each extending. from the .periphery thereof to the drum to form cup-like compartik ments circumferentially disposed between adjacent flights of the blade, and a conveyor extending longitudinally of the chamber and located between the spray devices. c

2. Dehydrating apparatus comprising means for drying gases, means for'feeding material to be dried to the drying chamber, and a conveyor for discharging dried material extending longitudinally of said .spray zone and "below said spraying device.

3. Dehydrating apparatus comprising a'drying chamber, a spray .device'mounted longitudinally of the chamber adjacent the bottom thereof, said spray device comprising a .rotatably` mounted drum, a spiral blade mounted longitudinally on the drum, and a plurality of transverse walls between adjacent nights of the blade each extending from the periphery thereof to the drum to form cup-like compartments circumferentially disposed between adjacent ilights of the blade, and a conveyor extending longitudinally of the .chamber and located below the spray device.

e. Dehydrating apparatus comprising a drying chamber, aspray device mounted longitudinally of the chamber adjacent the bottom thereof and in widely spaced relation to the top thereof to provide a spraying' vzone in said chamber above said device, said spray device 'comprising arotat-A ably mounted drum. extending from end to 'end of the chamber, a spiral blade mounted longitudinally on the drum andextending from end to end thereof, and a plurality of imperforate transverse walls between eac-h adjacent flight of the blade each extending from the 'periphery thereof to the drum to form cup-like compartments circumferentially disposed between. adjacent flights of the blade.

5. Apparatus for treating fluid materials comprising a chamber arranged to receive a current of gases, a liquid spraying device mounted in the chamber `adjacent the bottom thereof and in widely spaced relation to the top thereof to provide a spraying sone in said chamber above said device, said spray device `comprising a rotatably mounted drum extending from end to end of the chamber, a spiral blade mounted longitudinally onl the drum and extending from end to end thereof, and a plurality of imperforate transverse walls between each adjacent flight of the blade leach extending from the periphery thereof to the. drum to form cup-like compartments circumferentially disposed between adjacent flights of the blade.

6'. Apparatus-for. treating fluid materials -ernpris-ing a chamber -having an ,inletspaced from thev bottom thereof and arranged to deliver a current of gases to said chamber, a liquid spraying device mounted in the' chamber adjacent the bottom thereof, below said inlet, and lin widely spaced relation to the topY thereof to provide' a spraying zone in 'said' chamber above said device vfor traversal by said current 0f gases, said spray de vice comprising a 'rotatably' mounted drum `esctending from end to end of the chamber, and a spiral blade mounted longitudinally on the drum and extending from endto end thereof, anda plurality of transverse walls between each ad# jacent flight of the blade forming cup-like compartments Acircamferentiallg/ disposed between adjacent flights of the vblactejsaid chamber havingan inlet for 'supplying liquid to the bottom portionv of said chamber for entrainment by said compartments, said compartments being in free. communication with said 'spraying eonefor def` livery thereto of rain-like particles of said liquid.-v

l ARTHUR 1A, HOLLAND." "i

'REFERENCES onEn l UNITED STATES PATENTS Number Name Date 426,361 Buttne'r et al. Apr. 22, 189D 501,048 Bassett July'll, 1893 1,091,464 Wagner Mar. v24, .1914

. 1,190,127 Dsdier July 4, 1916' 1,720,786 1i'ast'ing V July 16, 1929 i 1,730,902 Rugh Oct. 8, 1929 :1,992,520 Colton et al.-` Feb. '26, 1935 Pranke June 2, 1936 VogelJorgensen Jan. 26, 1937 vfilari' et al. f 'Ma11..10.,.111942 `:Eat'ockharn Apr. .7, ..1942 Davey Jan. 12, ..1943

Peebles` Mar. 2, 1943 l'2,384,998 lHal'igh' Sept; 18, 1945 2,397,818 Tausch Apr. 2, 1946