US2384891A - Apparatus for cooling, drying, and desilting granular material - Google Patents

Description

Sept. 18, 1945. J. N. COLLINS: ETAL 2,384,891

APPARATUS FOR COOLING, DRYING, AND DESILTING GRANULAR MATERIAL Filed' Aug; 31, 1943 2 sh ts-sheet 1 ATTORNEYS P 1945- J. N. COLLINS ETAL 2,384,891

APPARATUS FOR COOLING, DRYING, AND DESILTING GRANULAR MATERIAL Filed Aug. 31, 1943 2 Sheets-Sheet 2 3* mun 3%? ATTORNEYS Patented Sept. 18, 1945 'APPARATUS FOR COOLING, DRYING, AND DESILTING GRANULAR MATERIAL John Newton Collins, Birmingham,'and Clifford Ashton, Wakefield, England Application August 31, 1943, Serial No. 500,704 In Great Britain September 18, 1942 2 Claims. (Cl. 209-135) This invention has reference to plant or machinery for effecting cooling and/or drying and desilting operations on granular materials.

Broadly the invention resides in plant or machinery for the purpose aforesaid characterised in that it embodies a tower or chamber into the upper end whereof the granular material to be treated is delivered from a continuous belt conveyor or by other suitable means, the said chamber being furnished interiorly with a series of plates or shelves so disposed relative to each other that the material introduced into the upper end of the chamber is caused to'descend therein in the form of a series of vertical curtain-like streams or cascades, the said chamber being provided with air admission apertures so located in one side thereof and relative to the curtain-like streams or cascades of the granular material that air currents induced into the chamber pass through the descending material, the chamber having in combination or association therewith means or mechanism such as is hereinafter described whereby the induction of air into the chamber and through the screens or cascades of material for the purpose of cooling and/or dry ing the material and desilting, that is to say, removing any undesirably fine particles, dust or other light refuse therefrom, before discharging the material from the lower end of the chamber is very efficiently affected and controlled.

The invention is especially useful for the performance of the cooling, drying and desilting operations involved in" the re-conditioning of the sand removed from the moulding boxes employed in casting foundries and will be hereinafter more particularly described in this connection with reference to th accompanying drawings but it is to be understood that it may be employed in the treatment of other granular material involving analogous operations. a

Figure 1 of th drawings represents in front elevaticnpartly in section a convenient-embodiment of plant or machinery in accordance with the invention for use in the said connection, the parts being shown more or less diagrammatically owing to: the small scale to which they are drawn and which is imposed by the size of the sheets.

Figure 2 is a side elevation of th same. Figure 3 represents the said plant or machinery in plan.

Figures 4 and 5 represent in side elevation and sectional plan respectively a fragmentary portion of the mechanism hereinafter more particularly referred to, drawn to a larger scale than Figures 1, 2' and 3.

Figure 6 illustrates a modified construction of the nozzle devices incorporated in plant or machinery in accordance with the invention, and

Figure 7 shows the said modification in elevation and partly in section on the line 1--'|-and looking in the direction of the arrows in Figure 6.

Th same numerals of reference indicate the same parts in the several figures of the drawings.

In the embodiment illustrated and designed for the use aforesaid the tower or chamber marked .8-'and into the upper end of which the sand to be re-conditioned is delivered, as for example,

from a suitably disposed belt conveyor 9, is of a rectangular figure in cross section and the plurality of plates or shelves i0 provided therein for the purpose aforesaid are disposed at suitably spaced apart intervals on two opposite walls of the chamber, the plates or shelves on the one side being staggered or alternating with respect to those on the other side of the chamber after the manner of baflie plates, as is best seen in Figure 1 in which figure the said chamber is shown in vertical section.

The inwardly presented edges of the successive plates on the one side somewhat overhang the corresponding edges of the successive plates or shelves disposed on the opposite side, so that the sand which is delivered from the conveyor 9 on to the uppermost plate of the series on each wall and piles thereon to a certain degree, de-

scends by gravity therefrom on to the succeeding alternating plates in the form of a vertical curtain-like stream or cascade as indicated by the stippling in Figure 1 until it reaches the lowermost plate or shelf in.the chamber from which it is passed through a suitably shaped outlet 8 to a travelling belt or other conveyor l2 whereby it is removed to any desired place for storage. or for immediate use.

The air admission apertures denoted by the references I3 which are provided in one side wall of the tower or chamber 8 are located in the parts thereof intermediate the series of plates IIJ disposed on the said wall and so that the induced air currents will pass through the curtains of sand formed between the plates on the respective walls. The air currents which pass through the curtains formed in the upper part or section of the ticles or dust undesirable in the conditioned sand and which are thus removed before discharge of the sand from the lower end 8 of the chamber.

The means or mechanism combined or associated with the chamber 8 for effecting the induction of air thereinto and through the curtains or cascades of sand for the purposes specified embodies a centrifugal fan the casing whereof is marked it in the drawings, the said fan being power driven as for example by an electromotor l5.

The fan M and motor l5 are locatedin appropriate relationship to the tower or cber 8 by mounting them on a staging embodying a platform It which may be constituted by a metal.- lic' grid carried by horizontal members W supported on vertical members or standards it, the said horizontal and vertical members being conveniently constituted by metallic bars of girderlike formation in cross section. Access is gained to the platform It, which is preferably furnished with a railing ill, by a ladder l9.

The casing ll of the centrifugal fan has connection at its intake side with a casing 28 of volute formation provided on the upper end of a centrifugal separator of any appropriate construction adapted for the separation of comminuted matter or particles from air, the casing of which separator is denoted in the drawings by the reference 2| and is conveniently supported in a framing 2 I carried by the vertical standards 2|.

The upper part of the centrifugal separator 2! is in communication through an aperture 29" therein with a vertically disposed conduit 22 furnished with a plurality of branch pipes 22 terminating in nozzles 23 which extend into the lower section of the chamber 8 through the wall thereof opposite to that in which the air induction apertures l3 are provided, the open ends of air passing into the nozzles, thus avoiding undue restriction of the air supply to the centrifugal the nozzles which are preferably of a narrow slot formation being presented to the curtains or cascades of sand in the said lower section of the chamber on the side or face of the curtains opposite to that which is presented to the air induc tion apertures.

It will be appreciated that when the centrifugal fan is in operation it'serves, through the connection of the intake side of its casing Id with the volute casing 20 on the upper end of the centrifugal separator casing 2|, to induce the posi-.

tive suction-of air from the tower or chamber 3 into the nozzles 23 of the branch pipes 22' of the conduit 22 and the currents of air thus created will pass through the curtains or cascades of sand to which the said nozzles are presented and carry therewith such particles or refuse as it is desired shall be extracted from the sand in its passage through the tower.

The nozzles 23 which operate to extract undesirable fine particles or dust from the lower ourtains or cascades of sand are or may be adapted for a slidable adjustment relative to the supporting branch pipes 22 so as to permit their ends to be set to any desired distance from the streams or cascades of sand to which they are respectively presented and each branch pipe is provided with a damper or valve 24 for regulating the velocity V of the air drawn into the males.

The said dampers or valves 24 may be adapted also'to control secondary air admission openings in the branch pipes which are opened proportionately to the extent to which the dampers or valves may be adjusted to reduce the velocity of separator.

In a convenient construction of the adjustable nozzles 23, as illustrated by the enlarged Figures 4 and 5, the flattened end thereof is formed or provided on a cylindrical portion 23 adapted for a telescopic sliding motion in the branch tube 22 with which it is associated, the telescopic adjustment being effected through the medium of screwed rods 25 rotatable in bearings furnished in brackets 26 disposed on diametrically opposite sides of the branch tube, the screwed ends of the said rods 25 engaging in tapped holes in a flange 23 on the part 23 of the nozzle.

Or in lieu of providing the branch suction tubes 22 with telescopically adjustable nozzles as described the said branch tubes may, as is illustrated by the fragmentary views Figures 6 and '7, terminate in flattened nozzle-like parts 22 having a fixed connection with the side wall of the chamber 8 into which they open, each branch tube nozzle-like part 22 or some only thereof, as for example those of alternate branch tubes, having a virtual extension of its open end into the interior of the chamber, the said extension bein constituted by a pocket 21 formed by the plates 21 and 21 disposed transversely between the front and rear walls of the chamber.

The upper plate 21 which preferably lies in a horizontal plane as shown may be fixed to the front and rear walls of the chamber between which it extends by riveting .flanges provided on the respective ends of the plate to the said walls, and the plate is of such width that its inner edge lies adjacent to the curtain or cascade of sand to which it is presented.

The lower plate 21* is disposed in a plane inclined to the upper plate 2'8 and is adapted for a sliding motion on inclined angle bars or brackets 21 provided for its support on the front and rear walls respectively of the chamber.

The said lower plate 21' which is of greater width than the upper plate extends and works through a slot 8 in that wall of the chamber to the curtain or cascade of sand may be varied as may be required for controlling the air currents induced into the chamber 8 through the apertures l 3 and thence through the sand curtains or cascades.

The particles or refuse extracted from the sand curtains or cascades pass from the conduit 22 into the separator 2| and descend to the bottom thereof from which they pass by way of a suitable rotary air-lock valve indicated at 29 and adapted for operation by an electromotor 30 into a reservoir or bin 3| and thence to a travelling belt 32 or other conveyor forflnal disposal.

The cleaned air is drawn from the separator 2| into the volute casing 20 at its upper end which end as aforesaid is connected to the suction inlet of the casing I4 of the centrifugal fan.

The said fan casing has connection 'on its discharge side with an outlet or diffuser tube 33 which is of tapering formation, its smaller end being disposed adjacent the fan and designed to act as a venturi for increasing the velocity of the air at this part, and the venturi or throttlecl section is provided with a lateral branch 33 with 'which it co-acts to operate as an ejector, the said branch tube being placed in communication, through a pipe 34 fitted with an air regulating valve, with the top of a casing 35 provided on the upper part of the chamber 8 through which the sand is cascaded, the'said casing 35 being disposed on the wall of the chamber 8 opposite to that furnished with the aforesaid air induction apertures l3. The wall whereon the casing 35 is provided has apertures 53 opening into the saidcasing and the ejector afforded by the diffuser tube 33 and its lateral branch 33 operates to eifect the induction of currents of air through the upper apertures l3 in the chamber 8 and thence through the curtains or cascades of sand i'alling in the upper part of the said chamber, and through the apertures I3 the sand being thereby cooled and dried prior to its descent into the part of the chamber in which the desilting operation is eifected.

The plates or shelves l whereon the layers or piles of sand fall in the descent of the sand through the chamber are preferably disposed in a horizontal planes and may conveniently be supported by L or angle iron bars or brackets I0 riveted or otherwise secured in the requisite positions on the walls of the chamber, and as the impact of the curtains or cascades of sand is on the sand which has been already deposited on the respective plates the wear on the plates or shelves is almost negligible.

By the use of plant or machinery in accordance with the invention the separation of fines can be adjusted to-give any desired grading of the sand or other granular material passed into the cascade chamber and the fines extracted in the desilting process do not pass through the fan, thus avoiding wear thereon.

Further, units in accordance with the invention can be designed to deal with any quantity 'of sand, or other granular material, and as the whole unit operates under partial vacuum conditions no dust can escape to cause an unpleasant working atmosphere in the vicinity of the plant or machinery.

We claim:

1. Apparatus for cooling, drying and desilting granular material comprising a tower having upper and lower sections, means for delivering material to be treated to the upper section of the tower, the tower having apertures therein for induction of air thereinto and a series of baiiies arranged in sta gered relation for causing the ma-- terial to descend therein in the form of cascades, a centrifugal separator having a volute casing at its upper end and an air-lock discharge valve at its lower end, a conduit connected to the separator and having branch tubes communicating with the lower section ofthe tower, nozzles for at least some of said branch tubes, said noz'zles being presented to the material descending in the tower to effect the induction of air currents therethrough, a centrifugal fan having a casing connected at its intake with the volute casing of the separator, a housing communicatin with the upper section of the tower, a diffuser tube connected to the discharge of the centrifugal fan and having a Venturi section therein, and a branch pipe leading from said housing to said Venturi section for the induction of air through the apertures in the upper section of the tower.

2. Apparatus according to claim 1, including'a valve in said branch pipe for regulating the induction of air by said Venturi section into the upper section of the tower.

JOHN NEWTON COLLINS. CLIFFORD ASHTON.

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