US2240854A - Desiccating apparatus - Google Patents

Description

y 1941- D. D. PEEBLES 2,240,854

. Q DESICGATING APPARATUS Original Filed Apiil 12, 1933 V 2 Sheets-Sheet 1' INVENTOR I 0; via 0. Peeb/es ATTORNEY May 6, 1941. PEEBLES 2,240,854

DESICCATING APPARATUS Original Filed April 12, 1933 2 Sheets-Sheet 2 FllE- E ,2 l

' lllllllllllln INVENTOR ATTORNEY Patented May 6, 1941 UNITED STATE nasrccarmc arr-lma'rus David D. Peeblcs, Berkeley, Calif assignor, by

mes'ne assignments, to Golden State Company;

Ltd., a corporation oi Delaware Original application April 12, 1933, Serial No.

Divided and this application December 23, 1939, Serial No. 310,846

Claims. (01.159 4) This invention relates generally to apparatus for desiccating various substances, whereby substances normally in liquid or fluid form can be converted into divided solid products.

It is an object of the invention to provide desiceating equipment particularly applicable to mafit terial having relatively low softening or melting points, and materials whose softening points tend to lower as the moisture content is. increased. I have particular reference to substances such as molasses, corn sugar, corn syrup solids, malt sugar, and-other sugarsv or sugar containing materials.

Another object of the invention is to provide a desiccating apparatus having novel provision within the desiccating chamber for insuring the final discharge of a free flowing divided material, as distinguished from an agglomerated mass or material tending to agglomerate together.

Referring to the drawings- 1 Figure 1 is a diagrammatic view illustrating apparatus incorporating the present invention-and which can be used in the desiccation ofwarious substances, including molasses;

Figure 2 is a side elevaticnal view in cross section illustrating the structural features of the desiccator illustrated diagrammatically in Figure 1; and

Figure 3 is a cross sectional view the line 3-3 of Figure 2.

Referring to Figure 1, the apparatus illustrated includes a desiccator iii of a novel construction as will be presently explained, but which can be generally identified as being of the spray type. While a latitude ispermissible with respect to the construction of this desiccator, the particular type illustrated in detail in Figure 2, and which will be presently'explained in detail, is desirable. With respect toFigure 1, it will suflice to point out that the desiccator includes a treatment chamber ll into which the material to be desiccated can be introduced by way of pipe l2.

In order to maintain'a region of desiccation within the chamber i I, hot drying gas such as air is introduced into'this chamber by way or two sets of conduits identified by letters-a. and b. In order that this air may be of the proper elevated temperature, I have indicated a heater ISthroughchamber, as will-be presently explained. Conduit I4 is for the removal of the desiccating material, together with a portion of the gaswithin taken along chamber ll. Lines I6 represent the conduits for introduction of additional cool air.

Figure 1 also diagrammatically represents equipment used in conjunction with the desiccator for the handling of a material such as mo-' Briefly, this additional equipment in-' lasses. cludes a storage container II for the material to be desiccated. In the handling of material like molasses it is desirable that the stored molasses be maintained at an elevated temperature to insure proper fluidity. For this purpose, I have illustrated a re-circulation .path formed by a pump II and heater l9. Another pump 20 serves to remove material from container I1 and to deliver it under pressure through the heater 22 to the pipe I2. Heater 22 can be supplied with steam or any other suitable heating medium.

Pump 20 can be provided with suitable means for maintaining a substantially constant pressure in the pipe l2. For this purpose, I haveshown a by-pass pipe 2| about pump 2., controlled by throttling means 2hr. A pressure responsive device 2lb connected to pipe I! has a mechanical connection 25 with throttling means Zla. A rise in pressure beyond a desired value in pipe I! .causes pressure responsive device Zlb to effect a compensating adjustment of throttling means 2 In, to decrease the rate of flow of material from pump 20 to heater 22.

It is desirable to handle the discharge from conduit It in such a manner as to permit removal, thorough cooling and sacking of the desiccated product, Thus, conduit it is shown connected to the inflow ide of a blower 23. The discharge side of this blower is shown connected to a suitable cyclone separator 24. This separator is provided with the usual air exhaust pipe 28 and a lower conduit 21 for the discharge 01 separated material. The discharge from conduit 21 atmosphere may ,be drawn in through conduit 2| if its moisture content is relatively low. However, if the moisture content is relatively high, which may occur under certain climatic conditions, then the air should first be conditioned to reduce its relative humidity. The outflow side of blower 29 is shown connected to a second cyclone separator II, and air exhausted from this separator as indicated by line 32 can be-introduced back into separator 24. The separated desiccated material removed from the separator 3|, by way of conduit 33,- can be delivered directly into sacks. Referring now to Figure 2, the conduits corresponding to lines designated by letters a to e tially into the desiccating chamber at different levels. Conduits i'a. discharge into a supplemental chamber 36 which communicates through the upper wall 31 of the main chamber Ii at a point concentric with the vertical chamber axis. The J main chamber II can be substantially cylindrical in. horizontal cross section, and for good results should be of substantial height with respect to "its diameter. Pipe I! for introducing the material to be desiccated is provided with a nozzle 39 at its lower end which afl'ords what can be termed a "spray orifice. It should be understood that in place of utilizing such a spray orifice, I may make use 01' so-called centrifugal atomizers such as are iii common use with spray type desiccators.

The lower chamber wall 4| can be conlcally shaped, as illustrated, with its lower central portion communicating with the discharge conduit H. In that region immediately above the lower wall ii, a transverse baffle 42 is provided to serve both as a cool air inlet, and to minimize swirling movement of air within the lowerportion of the chamber before this air, together with the desiccated material, is removed by way of conduit l4.

Referring to Figure 3, it will be noted that baflle 42 is in the form of a trough with its lower wall in communication with conduits [6a for introducing relatively cool air. It should be understood that the'air" introduced at this point may be air from the atmosphere or atmospheric air which has been conditioned by either lowering its temperature by removal of moisture, or both.

The number of conduits'provided for the introduction of air into the main desiccating chamber at various levels may vary in practice. For example, for the desiccation of molasses, I

the particles to be discharged downwardly through the chamber without proper treatment.

The hot gas within the desiccating chamber progresses downwardly, together with the par.- ticles being desiccated while the particles being desiccated are in the liquid phase, the temperature'being reduced somewhat by evaporation of moisture from the material. At or near the level of conduits 3c, the temperature is further reduced by dilution with the relatively cool gas introduced through these conduits. Further dilution and cooling appears as the gas proresses to the lower levels of conduits 4d and 5e, although the particles ofdesiccated material are maintained in suspension throughout their progression through the desiccating chamber and are prevented from adhering to the sidewalls of the chamber by virtue of the sweeping action occasioned by the tangential introduction of gas through conduits 3d, 4d and 5e, and because their surfaces, having been cooled, are hardened. Also, gas introduced by way or conduits 3c, 4d and 5e serves to maintain the side walls of the chamber relatively cool, thus preventing buming in the event particles of material contact with the walls.

As a result of the dilution and cooling eflected by introducing cool air throughthe conduits 3c, 4d and 5e, and by 'the progression oi. the material downwardly through the successive levels or theseconduits, the particles are converted to the solid phase. This, of course, assumes operation oi the apparatus in conjunction with mahave used two conduits 2b, two conduits 3c,

i'our conduits 4d, and four conduits 5e. It has been found desirable to provide adjustable shutters 43 at the points of discharge oi. these conduits into the main desiccating chamber toafford better control of the air introduced.

Operation of the desiccator described above is as follows: The drying gas heated tov a suit- I able elevated temperature is introduced into the conduits In and also into the conduits 2b, in the event the latter conduits are also employed. In a typical instance, the temperature of this hot-gasgat the point of introduction may be about 700 F. Such introduction of hot gas establishes a zone orregion of desiccation in the upper portion of the desiccating chamber terials such as molasses, sugar syrups and sugar containing materials, and the like. In other words, assuming for example use of the equipment in desiccating molasses, atomized particles of molasses discharged from nozzle 35 are first desiccated while the particles are retained in the liquid phase, and then these desiccated particles are immediately caused to progress into a region where they are'caused to be converted into the solid phase by contact with relatively cool gas. As the particles are removed through conduit it, they are inthe solid phase.

The baflie 42 plays a desirable part in operation of the desiccator. Because of the area of the surfaces which it presents to the swirling currents of gas, it functions to minimize swirling movements in a region immediately above the point of communication of the outlet con- Y duit M with the treatment chamber. This avoids and in a region surrounding the discharge noz- 'zle 39. That portion of the hot gas introduced by way of conduit 38 is discharged downwardly and about nozzle 39,\while any additional hot gas introduced by way of conduits 2b' causes swirling movement within the upper portion of the desiccating chamber. The particles of material discharged from nozzle 39 are received within this region of desiccation, and the atomized particles are caught up and carried in suspension by the gascurrents. While it is desirable to have the particles of material spread outwardlysomewhat and also p logressed downwardly, the air flow into the treatment chamber should not impart swirling movement of such intensity as 'to cause the particles to be immediately. thrown outwardly against the side walls,

nor should the air now impart a downward velocity component of such intensity as to cause the formation of a str'ong vortex within the lower portion of the treatment chamber, such as would interfere with proper removal of the finished product, and in addition it causes the deslocated product to more eflectively drop out of the swirling as within the desiccating chamber into the outflow conduit M. In addition, the positioning oi this battle, together with introduction of cool air through the baille, tends toform a definite zone of demarcation between themain portion of the chamber where the particles are suspended by the swirling gas, and the lower I end portion of the chamber where it is desirable to remove th particles as rapidly as possible.

In the desiccation of all materials such asmolasses, the humidity of the gas in the treatment chamber l I, and particularly in that region in which the particles are converted to the solid phase, should be sufliciently low as to avoid causing the solid particles to become sticky and adhere together. Thus, it climatic conditions are such that the atmosphere is relatively humid, the cool atmosphere introduced by way of comneighborhood of 158 F., at which temperature solid molasses begins to harden;

When handling materials like molasses, I can make use of the method disclosed and claimed in co-pending Patent No. 2,184,314 oi. which this application is a division. Briefly, I have reference to heating the molasses to such a temperature by means of its flow through heater 22 as to cause partial degradation of its sugar content with resulting gas formation and building up of pressure. With other materials such as corn syrup,-or other sugar syrups, or sugar containing materials, it may not be desirable to attempt partial degradation of the sugar content, in which event the material is simply heated to a temperature sufficient to promote proper atomization when discharged from the nozzle 39 under pressure. Also as previously pointed out, I may make use of atomizing nozzles 01 the centrifugal type such as are known to those skilled in the art.

When using such atomizing nozzles, it will suffice to provide the material at a temperature suflicient to render it free flowing and to sup-" ing gas introduced into the chamber, mean -for maintaining swirling movement of gas within the chamber, and baille means within said chamber disposed adjacent the point of communication.

of the chamber with said conduit, for minimizing the swirling of gas and entrained material.

2. In a desiccating apparatus, a treatment chamber having an outlet and an outflow conduit connected to saidoutlet, said outflow conduit serving to effect removal of desiccatedmaterial together with drying gas introduced into the chamber, means for maintaining swirling movement of gas within the chamber, and baflle means located adjacent said outlet for minimizing swirling 0! gas within a region in the chamber adjacent the point of communication with said conduit, said -baiile means having provision for introducing relatively cool gas into the chamber.

3. In a desiccating apparatus, an upright means for maintaining swirling currents of gas within the chamber, means for introducing material to be desiccated into the chamber, and bafllemeans within the chamber and located immediately above the point of communication with said conduit for minimizing swirling of gas, said baiiie means forming a conduit for introducing relatively cool gas into the chamber.

4. In a desiccating apparatus, a treatment chamber, means for introducing divided material to be desiccated into one portion 01' said chamber, means for maintaining swirlingcurrents of hot drying gas in the chamber in a zone into which said material is introduced, an outflow conduit communicating with said chamber,

means for maintaining a zone or relatively cool gas between the zone oi! hot drying gasand the piont of communication of the outflow conduit with said chamber, and heme means disposed within said chamber and adjacent the point oi. communication of the chamber with saidconduit, for minimizing the swirling or gas and en- -flrst named means, an ,outflow conduit communicating with the lower portion or said chamber through which desiccating material and gas irom the chamber are withdrawn, and baiiie means disposed within the chamber and adja-.

cent the region of communicationot'the chamber with said outflow conduit for, minimizing swirling of gas and entrainment of material en tering the conduit.

DAVID D. PEEBLES.

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