US3004349A - Drier with circular stages and oscillating flow air inlet nozzles - Google Patents

Description

Oct. 17, 1961 A. BIANCHI 3,

DRIER WITH CIRCULAR STAGES AND OSCILLATING FLOW AIR INLET NOZZLES Filed Aug. 27, 1957 4 Sheets-Sheet 1 IEVENTOR. M

W Sfwh M Oct. 17, 1961 A. BIANCHI DRIER WITH CIRCULAR STAGES AND OSCILLATING 110w AIR INLET NOZZLES 4 Sheets-Sheet 2 Filed Aug. 2'7, 1957 IN V EN TOR.

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6 A. BIANCHI 3,004,349

DRIER WITH CIRCULAR STAGES AND OSCILLATING FLOW AIR INLET NOZZLES Filed Aug. 27, 1957 4 Sheets-Sheet 3 INVENTOR.

Oct. 17, 1961 BlANCHl 3,004,349

DRlER WITH CIRCULAR STAGES AND OSCILLATING FLOW AIR INLET NOZZLES Filed Aug. 27, 1957 4 Sheets-Sheet 4 i INVENTOR. Mm 5 BY ans/MAW,

rates The present invention relates to a drier with circular stages and oscillating air inlet nozzles.

Driers are known, having circular superposed stages in which the material is moved by blades or other suitable means, usually fixed to a central driving shaft.

The object of the present invention is a drier of this type possessing novel particular characteristics which increase its efficiency.

In the known types the air is usually introduced by radial or tangential nozzles, single or subdivided into two or three branches, or also by means of horizontal conduits conveying the air to several outlets spaced around the circumference.

These systems are defective in that they create some zones more ventilated or heated than others.

This defect is the more pronounced in the case of materials which should not be heated above a certain temperature and which require more time to dry, or in the case of materials which during the drying process present a critical point constituted by the passage from a given physical state to another (for example, pasty or liquid materials which will undergo hardening at a certain condition of drying).

The drier according to the invention is substantially characterized by the fact that some, at least, of the hot drying air inlet nozzles will produce a flow of constantly variable direction with an alternating repeating cycle.

The invention will now be described with reference to the accompanying drawings, description and drawings being given only by way of indicative example, non limitative of the scope of the invention.

FIG. 1 shows in a vertical axial section a preferred form of the invention;

FIG. 2 is a partial horizontal section at one of the nozzles;

FIGS. 3 and 4 are respectively vertical sections of the material discharge devices at the center and at the periphery of the arrangement shown in FIG. 1;

FIG. 5 is a vertical section of a second embodiment of the drier;

FIG. 6 is a vertical section of a third embodiment of a drier according to the present invention.

Referring to FIGS. 1 to 4, by A is indicated the cylindrical shell of the drier, provided in a known way with the superposed circular stages .as drying floors 1, 2, 3 and 4 over which the material is distributed which during the drying operation passes from one stage to the stage next below.

The humid material falls through the inlet nozzle 5 onto the circular channel 6 and hence, moved by the rotating paddle 7 is discharged onto the periphery of the first stage 1. The radial arms 8 are fastened to a rotating vertical shaft 9 (driven by a motor 10') and carry paddles 1t} designed to mix up the material and drag it centerwards where it is discharged (as will later on be described) onto the stage 2 beneath stage 1. Stage 2 is also served by rotating arms 11, while paddles 12 which shove the material forwards, to the periphery, discharging it onto the next lower stage 3.

The rotating arms 13 with paddles 14 mix up the material on stage 3 and carry it centerwards, discharging it onto the last stage 4, whence the dried material pushed by the blades 16 fastened to the rotating arms is discharged to the outside of the shell A through the conduit 17.

The stages 1, 2, 3 and 4 are perforated, so that dry air coming from the conduit 18 and distributed by the three conduits 19, 2t) and 21 ending respectively beneath the stages 1, 2, and 3 may be sucked by the fan 22 placed at the top of the shell A through the perforated stages and be discharged to the outside of the shell.

The conduits 19, 2t} and 21 have a divergent shape (FIG. 2) and are radially arranged with respect to the shell. In each conduit 19, 2t) and 22 a nozzle 23, 24 and 25 is disposed, each intended for distributing the drying air. The nozzles 23, 24 and 25 are attached to a single vertical shaft 26 which is provided at the lower end thereof with a radial arm 27 having its end pivoted to a connecting rod 28. The other end of the connecting rod 28 is actuated by an eccentric 29 keyed on the shaft 9 driving the arms and paddles.

Rotation of the shaft 9 produces an alternating oscillation of the shaft 26 and nozzles 23, 24 and 25. In other words, there is obtained a continuous variation of the gaseous flow between the two extreme directions indicated by the arrows X and Y in FIG. 2.

That is, the flow starts from a tangential direction (or a substantially tangential one) X which generates a circular current in the shell A in one direction; during the oscillation of the nozzle a flow is produced which gradually becomes radial and lastly tangential but in the direction of Y, that is, such as to create a circular current opposite the preceding one.

Currents are, therefore, obtained which are continually changing.

The continuous change of direction of the hot air flow in addition to ensuring a good heat distribution avoids overheated zones and permits, therefore, an increase in the temperature of the incoming air, thus improving the thermal efiiciency, productive capacity and reducing power costs.

Obviously, the oscillating nozzle control can be realized with different mechanical means and eventually with devices adapted to vary the transmission ratio between the shafts 9 and 26.

Air tightness between nozzles and their conduits is realized in a sufficient manner by the side fins 3t hinged at 31 to the vertical borders of the nozzles and each is guided at the free end thereof by an oscillating arm 32 fulcr'urned at 31 to the conduit and fin.

This particular construction will result in a minimum of frictional resistances, even in the absence of lubrication, and is therefore suitable even for a relatively high air temperature.

The efficiency of the drier according to the present invention is increased by a special device for discharging the stages.

Materials subject to temperature limitations and slow to dry require great drying surfaces, i.e. many stages, upon which the material is kept in a thin layer and quick movement.

The efficient heat distribution secured through the oscillating nozzles permits to increase the thickness of the layers of the material to be dried and to slow down its movement, thus reducing the dimensions of the drier. The increase of thickness is made possible with the new discharge devices as illustrated in the FIGS. 3 and 4.

The discharge device at the center (FIG. 3) is constituted by a tubular element 34 fixed to the stage 1, in which can axially slide a second tubular element 35. The latter can be fixed in the desired position, for instance by means of pressure screws 36, so as to form a kind of adjustable height weir, over which the material must flow (arrow Z), before falling into the conduits leading towards the subjacent layer, protected in a known way by air tight valves 37. Rotating paddles of a suitable shape, in the proximity of the device 34, 35 facilitate the passage of the material to the outlet and prevent the formation of dead points. 7

FIG. 4 illustrates a similar device for the peripheral discharge. The outlet conduit 38 is provided with an adjustable height plate 39 constituting the weir and is tightly closed at the top by the oscillating vane valve 49.

The peripheral paddle l2 intended to facilitate the discharge of the material has the shape of a plough share or flat helicoidal sector so that the paddle continually mixes up the lower material and carries it to the surface.

The mixing paddles lli, 12, 14, 16 may be constructed similar as paddle 12.

FIGS. 5 and 6 relate to a drier similar to the drier described above, but suitable for soft or liquid but not sticky material.

Soft or liquid materials cannot generally be treated with the circular stage drier because at a certain instant they harden and stick to the paddles and stages forming lumps and stacks.

On account of the very good heat distribution secured through the oscillating nozzles, the treatment of these materials becomes possible with the following devices.

The material is distributed over a horizontal circular stage in a continuous way by at least one distributing means following a substantially radial line; distributor and stage rotate relatively to each other around the stage axis so as to build up a uniform layer at each revolution, while movable pressure means press the layer down upon the stage which is provided with holes and apertures through which the material descends to be treated by the gaesous drying current.

FIG. 5 shows a cylindrical shell B of the drier, and a vertical revolving shaft 41 driven by a motor means 42 and extending along the axis of the shell.

The material to be dried is axially introduced from above through the conduit 43 communicating with one or more radial conduits 44 provided with downwardly directed holes or apertures through which the material is radially discharged, falling upon the circular stage 45 solidary with the shell B.

The conduits 44 are connected to the shaft 41 and therefore rotate therewith so that each conduit builds up at each revolution a uniform layer of material upon stage 45. The latter is served by'one or more pressure taper rollers 46 loosely supported by the radial arm 47, fixed to the shaft 1 and, therefore, revolving with it.

The rollers 46 can be arranged below the conduit 44, so that the material falls first upon the rollers and is then spread upon the stage 45, or the rollers 46 can be offset relative to the conduits 44 in such a way that the material will fall directly upon the stage 45 as a thin layer or jet-like (according to the consistency of the material and the characteristics of the conduits 44) and is then compressed by the rollers 46, the task of which is to laminate it and let it drip through the holes or apertures provided in the stage 45. The material is uniformly distributed over the stage 45 thus ensuring the best utilization of the stage itself. The material is impinged on by the hot air entering through the nozzle 48, coming from the main conduit 49 carrying the drying gas, loses a portion of its humidity and gets denser before falling upon the subjacent stage 50, where the taper rollers 51 (similar to the rollers 46) carried by the rotating arms 52 compel it to pass through the holes or apertures in the stage 50.

On the stage 50* the material may reach the critical hardening phase only after having remained suspended in the shape of vermicelli from the stage.

This uniform result is such as to prevent the formation of crusts and will, of course, be conditioned by a good heat distribution due to the oscillating nozzles, as

well as to the correct dosing of the material and the quantity of heat introduced into the various stages.

Most materials, after having been passed through two or three stages become so dense as to remain broken down and they can therefore be collected on the subjacent stage 61 (after having been once more invested by the gaseous drying current coming from the nozzle 62) servedby the paddles 63 carried by the radial revolving arms 64. The paddles 63 convey the material to the finishing subjacent stages 65 and 66, Where drying is completed with the normal systems of rotating paddles 67 and 6S transporting the material center-or peripherywards, discharging it to the subjacent stage through air tight nozzles 69 and 70. The number of laminating and finishing stages depends, of course, on the character of the material to be dried.

The stages 61, 65 and 66 are perforated in such a way that the hot air issuing from the nozzles 71, 72 and 73 may pass through the same due to the suction from the fan 74 situated at the top of the shell B. A portion of the aspirated air may be recycled by means of a second fan B. The laminating stages 45, 50 and 54 are only partly traversed by the air coming from the sub-jacent stages, which passes instead through apertures 76 and 77 of the stages alternately disposed centerand peripherywards so "as to flow over the stages themselves. The air circulation system may also difier from the described one.

The dried material is distributed over the non-perforated bottom 78 and, pushed by the rotating paddles 79, is discharged through the chute 80.

The stages 61, 6-5 and 66 may, if necessary, have discharging devices for the thick layer like those already described.

In such a case also, as described for FIG. 1, the hot air inlet nozzles are of the oscillating variety.

In the embodiment shownin FIG. 6, where the parts corresponding to the described ones have been designated the same reference numerals provided with a mark the laminating stages 45', 50 and 54 are fixed to the shaft 41 and revolve with the same, whereas the distributing conduits 44', the pressure rollers 46, 51', and 55 are stationary and fixed to the shell B by means of cross pieces 81.

It is, of course, understood that the construction details of the drier may vary from the illustrated ones without departing in any way from the spirit of the invention.

For instance, a portion of the drying stages may be of the rotating and a portion of them of the stationary type.

I claim:

1. A drier comprising, in combination, a housing having a circular peripheral wall; at least one drying floor extending transversely through said housing and dividing said housing into at least two chambers, said drying fioor being formed with at least one discharge opening; a distributor means for distributing material to be dried in a substantially even layer over said floor and for moving the material through said discharge opening of said floor to the chamber located beneath said floor; conduit means communicating with at least one of said chambers for feeding a stream of hot gas in a direction substantially parallel to said floor over said layer, said conduit means having an inlet end; a nozzle located at and communicating with said inlet end and being movable in a plane substantially parallel to said floor from an intermediate position in which said movable nozzle is directed toward the center of said housing to a first end position at one side of said intermediate position in which said movable nozzle extends substantially tangential to said peripheral Wall of said housing and back over said intermediate position to a second end position in which said movable nozzle extends on the other side of said intermediate position also substantially tangential to said peripheral wall; moying means for continuously moving said movable nozzle between said positions thereof; and exhaust means for exhausing the hot gas from said housing, whereby the hot gas will sweep over said layer in a turbulent stream continuously changing its direction so that an intimate contact between the hot gas and the material to be dried is obtained without overheating the material.

2. A drier comprising, in combination, a housing having a circular peripheral wall and a top Wall formed with a substantially centrally located opening therethrough; at least one drying floor extending transversely through said housing and dividing said housing into at least two chambers, said drying floor being formed with at least one discharge opening; distributor means for distributing material to be dried in a substantially even layer over said floor and for moving the material through said discharge opening of said floor to the chamber located beneath said floor; conduit means communicating with at least one of said chambers for feeding a stream of hot gas in a direction substantially parallel to said floor over said layer, said conduit means having an inlet end; a nozzle located at and communicating with said inlet end and being movable in a plane substantially parallel to said floor from an intenmediate position in which said movable nozzle is directed toward the center of said housing to a first end position at one side of said intermediate position in which said movable nozzle extends substantially tangential to said peripheral wall of said housing and back over said intermediate position to a second end position in which said movable nozzle extends on the other side of said intermediate position also substantially tangential to said peripheral wall; moving means for continuously moving said movable nozzle between said positions thereof; and exhaust means communicating with said central opening in said top wall for exhausting the hot gas from said housing, whereby the hot gas will sweep over said layer in a turbulent stream continuously changing its direction so that an intimate contact between the hot gas and the material to be dried is obtained without overheating the material.

References Cited in the file of this patent UNITED STATES PATENTS 1,136,933 Cameron Apr. 27, 1915 1,585,387 Hulse May 18, 1926 2,050,597 Younger Aug. 11, 1936 2,835,050 Janetti May 20, 1958

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