US1919229A - Rotary drier - Google Patents

Description

c. o. LAVETT July 25, 1933 ROTARY DRIER Original Filed July 30, 1926 Sheefs-Sheej'. .1

2 Sheets-Sheet 2 July 25, 1933. c, o, LAVETT ROTARY DRIER Original Filed July 30, 1926 III Patented July 25, 1933 UNITED STATES PATENT OFFICE cameras 0. LAVETT, or BUFFALO, NEW YORK, Assrenon, BYnE'sNE ASSIGNMENTS,

TO BUFFALO FOUNDRY 8c MACHINE CO.,

OF NEW YORK OF BUFFALO, NEW YORK, A CORPORATION ROTARY DRIER Continuation of application Serial No. 125,947, filed July, 30, 1926. This application 'flled June a, 1931.

Serial N0. 541,960.

This invention relates to a rotary drier wherebymaterialsare dried in batches and preferably under vacuum and is a continuation of my co-pending application, Ser. No. 125,947, filed July 30, 1926.

In machines of this character, as heretofore constructed the material had a tendency to pack or gather in lumps which not only consumed an undue amount of power for operating the machine but also prevented complete and intimate mixing of the materials during the drying operation and also produced an undue amount of dust which latter when separated in a dust separator required constant re-filling of the dust separator with water in order to compensate for the rapid evaporation of the water.

It is the object of this invention to provide I a rotary drier which is strong and durable in construction and eflicient in operation, which can be operated with less power and which will maintain the material in a comparatively loose condition in which -it can not only be dried rapidly and thoroughly mixed but also produce a minimum amount of dust so that an undue amount of water is not required in the separator for re-claiming this dust.

In the accompanying drawings:

Figure 1 is a 'side elevation of a rotary drier embodying my invention.

Figure 2 is an end elevation of the same;

Figures 3 and 4 are fragmentary longitu- :7 dinal sections of the end portions of the drier.

tudinal section of'the intermediate portion inder 'or shell whichis arranged horizontally I Figure 5 is a fragmentary vertical longiof the drier. Figure 6 is a. vertical sectiontaken on the correspondingly numbered line in Fig. 5.

, Similar characters of reference indicate: like parts in the several views.

The numeral 10 represents the drying cylandprovided at its opposite ends with heads 11, 12 so as to form a cylindrical dryingchamber in which the material to be mixed and dried is arranged while the same is being treated. This'dryingcylinder is comparatively long and the material to be treated may be introduced into the same through one or more inlets depending upon the length of themachine. I In the present case this material is introduced through two charging openings 13 in the upper side of the cylinder which are locatedat suitably spaced points in the length .of the cylinder in order to introduce material and distribute the same within this cylinder to the best advantage. This material is directed to these openings through upright tubes 14 which are connected at their lower ends with the charging openings 13' while the upper ends of these tubes are procharging openings and controlled by means of a cover 17 which is closed when the machine is in operation but which may be opened for the purpose of providing an exit for the material from the cylinder after the same has been dried. A vacuum ma be produced within the drying cylinder many suitable manner for the purpose of facilitating the drying operation. Forthis purpose one of the material feed pipes 14' is provided with a, lateral branch 18 which is adapted to'b connected by a pipe 19 as shown in Fig. 6, with a suction apparatus of any suitable character which exhausts the air or vapors from the interior of the cylinder and produces a vacuum therein. In order to permit of conveniently breaking this vacuuman air inlet valve 20 is provided which in this instance connects with a lateral branch 18 on one of the material feed pipes 14:, as shown in Fig. 2.

The drying cylinder may be externallyheated in any suitable manner but preferably bymeans of a steam acket 22 which is formed between the exterior of the cylinder lOand a shell 23 surrounding this cylinder. Steam-or other heating agent may be introduced into this-steam or heating jacket through inlets 2 k in the top thereof, and the water of condensation may be removed from this jacket through. outlets 25 in the bottom thereof, as shown in Fig. 5.

Within the cylinder are arranged the agitating and stirring means whereby the material after being fed into the cylinder is lifted, tumbled about and moved lengthwise so as to-expedite the'mixing and drying of the same. These agitating or stirring means in their preferred form are constructed as follows:

The numeral 26 represents av tube or hollow shaft which is arranged lengthwise in the cylinder and coaxially therewith and pro vided at its opposite ends with hollow trunnions 27, 28 which turn in suitable bearings 29, 30 at opposite ends of the cylinder. This tube or hollow shaft may be turned in any i the trunnion 28, a rotary oint being produced between the steam inlet and the condensation outlet and the respective trunnions in a man- 7 her common to this type of machinery.

On the periphery of this internally heated tube are arranged at suitable intervals a plurality of supporting collars each of which preferably consists of two sections 34, 34 which embrace opposite sides of the tube 26 and are connected with each other and clamped against this tube by means of bolts 35 which connect corresponding ends of these collar sections, as shown in Figs. 5 and 6.

1 Each of these supporting collars is provided with a plurality of radial supporting arms 36 which are preferably formed integrally with the collar sections and suitably spaced circumferentially relative to each other. The inner part or body of each of these arms is preferably arranged radially relative to the axis of the heating tube but the outer end portion 37 thereof forming an attaching lug, is bent or deflected at an angle relative to the body of the respective arm so that the outer edge of this lug is arranged in advance of its inner end or point of connection with the respective arm in the direction of rotation of the tube 26. For a purpose which will presently appear the several collars are so arranged on the heating tube. 26 that the arms of each are offset about onesixth of a turn circumferentially relative to the arms of an adjacent collar.

In the space between the heating tube and the cylinder are-arranged a'plurality of sets --.of paddles or blades 38, 39. Each of these sets of paddles is arranged to form a circum- .face and the saine is mounted for rotation with the tube 26 by connecting its rear side adjacent to one end thereof with the front side of an attaching lug 37'of one of the supporting collars while the opposite end portion thereof is connected on its rear side with the front side of an attaching lug 37 of an arm on an adjacent supporting collar, the respective arms of the two collars sup: porting the same paddle or blade being ofi'set circumferentially relatively to each other the requisite extent to support the blade in a position in which it forms part of a helix around the axis of the tube 26. Each of the paddles or blades is mounted on the respective supporting arms so that the same-travels close to the under side of the cylinder during the rotation of the same and operates most effectively upon the material lying on the lower part of the cylinder. Due to the mounting of the paddle on the inclined outer parts or lugs of its supporting arms the front or working face of this paddle is inclined relatively to a radial line from the axis of the tube so that the outer edge of each paddle or blade is in advance and the inner edge of the same trails. By this arrangementeach paddle or blade upon engaging the material in the lower part of the cylinder causes the same -to be moved circumferenti ally due to the rotation of the paddle or blade in this direction, also lengthwise of the cylinderdue to the helical form of the paddle or blade and also causes the material to be lifted or moved radially inward toward the axis of rotation due to the inclination of the front or working face of theblade relatively to a radial line.

When the material is thus operated upon by the paddles the same is not moved circumferentially with such positive action as would be the case if the paddles were arranged radially and consequently the material is not lifted so high and caused to gather in large masses, portions, or lumps in the upper part of the cylinder and then drop back again into the lower part of the cylinder and produce considerable dust. Instead of this the material is mildly agitated and moved about in the lower part of the cylinder due to the lifting action of the inclined paddles which latter therefore serve more effectively to mix the material instead of carrying the inaterial to the upper part of the cvlinder. During such rotation of each paddle its front side continues to operate upon the material while in engagement therewith. During such engagement the material is shifted lengthwise due to the helical form of the paddle until the material escapes from the trailing end of Ill the paddle. After the material escapes from the trailing end of one paddle the same is not immediately engaged by a paddle in an adjacent annular sefv by reason of each paddle in one annular row being spaced apart circumferentially from the corresponding ends of the paddles in adjacent'annular rows. By

this means the material is momentarily permitted to re-adjustitself and assume new positions after escaping from one paddle and before. being engaged by another paddle, thereby not only avoiding carrying the ma terial an unnecessary extent toward the top of the cylinder but also promoting the mixing of the material and the drying of the same. In order to insure engagement of the material by the paddles of one annular row or set after escaping from the paddles of another annular row or.setthe ends of the paddles in one annular row overlap or extend beyond the ends of the paddles in adjacent sets, as shown in Fig. 5, thereby insuring the most effective engagement of thelseveral paddles with the material and expediting the mixing and drying of the same.

In order to avoid the production of an end thrust of the heating tube 26 on the bearings in the heads of the cylinder the several blades or paddles are so constructed and mounted that the helix formation of some of the 'paddles'trend in one direction and other blades or paddles are so arranged that the helix of which they form parts trends in the opposite direction and in the preferred contion of the oppositel; trending paddles also causes the material to be shufiled back and forth within the cylinder znd thereby cause the same to be mixed uniformly and thoroughly in less time. Byinclining the paddles relative to radial lines from the axis 26, the actionof the paddles is similar in effect to that of-a knife which is drawn through a mass of material inasmuch as the mainetfect is to cut the material and separate the same instead of propelling the same in the directlOll'Of the m'ovementof the knife. This will be apparent when comparing a paddle of this form with. one in which the paddle is arranged parallel with or perpendicular to the line of travel in which last mentioned,

case considerable power is required and a large portion of the material, in the case of a pasty substance, would be liable to stick to the flat surface of the paddle due to the pressure exerted upon the surface in order to move the material. In the case however, of an inclined blade such as employed in the present case very little efiort is required to move the mass asmuch as the paddle merely lifts the mass slightly and then permits the same to again -ing thereto.

On account of the angle at whlch the paddles are set the combi'hcd circumferential and lengthwise movements of the material in the drier is slight andyet suflicient to produce thorough mixing and drying which by the paddle or blade incombined movement further tends to keep the material from adhering to the paddles. The slight movement of the material as the paddles pass .under it, does not pack nor carry it to the top of the drier and then dump it to the bottom thereof, but instead keeps the same in a substantially disintegrated condition, thereby not only reducing theamount of power required for operating the machine but also reducing to a minimum the troublesome problem of disposing of' an excessive amount of dust which otherwise would be I formed.

.The inclination of the blades in this manner is for two purposes. First, it enables movement of the blades through the material close to the wall of the drier in the manner of 'a knife that is to say, the blades slice through the material, andsecond, it produces a slight lateral movement of the material in the direction of the axis of the drier. The action of the blades in the manner described is particularly advantageous because of the reduced power required for the operation of the blades. The helical form of the blades also tends to produce movement of the material lengthwise of the cylinder, it being noted that the material which is moved in this manner is the material close against the inner-wall of the drier throu hout the entire length of the blades. T is cannot be accomplished by straight blades for such blades would not be of a uniform dis-- tance throughout their extent from the inner wall of the drier and although this may not be necessary where violent agitation is contemplated,.in accordance with the customary practice, it is highly desirable where the m'a-- terial is agitated gently in the manner,

disclosed.

It will, therefore, be apparent that a specific feature of applicants invention is that the blades in each group of the series act upon the material and urge it in opposite directions. In other words, one of the blades in a group tends to move the material in one wise of the drier.

direction .While the other blade tends to counteract such movement. This is particularly desirable as it insures a thorough gentle agitation of the material within each group without movingit to any great extent-length- Inasmuch as the material is agitated in zones because of this construction, that is to say, each group of blades treating a particular portion of the material in the drier it is desirable, in order to insure the uniform agitation of all the material, that the zones overlap to some extent. To this end, therefore, the blades in each zone project into the paths traversed by the blades of adjacent groups.-

I claim as my inventlonz 1. A drier comprising a cylinder having an inlet opening through which the material a move the material in one direction length- 'wise of the cylinder while another of the blades in said group tends to move the material in the opposite. direction lengthwise of said cylinder, the corresponding ends of the blades of each group extending into the spaces between the blades of the adjacent group whereby the path traversed by each group of said blades overlaps the paths of adjacent groups of blades thereby insuring uniform agitation cylinder.

2. A drier comprising a cylinder having an inlet opening through which the material to be treated is fed and an outlet opening through which the treated material'is discharged, a shaft arranged lengthwise in said cylinder, a series of groups of helical blades within the cylinder.

of the material within thecarried by said shaft, one of the blades in each groupof said series trending circumferentially in one direction about the axis of said shaft and another of the blades in each group tends to move the material, in one di- 4 recti on lengthwise of the cylinder while another of the blades in said group tends to move the, material in the opposite direction lengthwise of said cylinder, the path traversed by each group of said blades overlaps the paths of adjacent groups of blades thereby insuring uniform agitation of the material 3. A drier comprising a horizontal hollow internally heated cylinder provided on its upper side with an inlet'for the material to be dried and on its bottom with an outlet for the dried material, a hollow internally heated shaft arranged lengthwise in said cylinder and j ournaled in the ends thereof, a plurality of supports mountedon said shaft, and-a series of groups of helical blades mounted on the outer ends of said supports, the face of each blade being arranged at an oblique angle to a radial line from the axis of the shaft with the outer edge of the blade in advance andclose to the inner side of the cylinder throughout the length of the blade while the rear edge of the blade trails and is removed from the inner side of the cylinder, one of the blades in each group of said series trend- 1 ing circumferentially in onedirection about the axis of the shaft and another of the blades in each group of said series trending circumferentially in the opposite direction about the axis of said shaft,*the corresponding ends of the blades of each group extending into the spaces between the blades of the'adjacent group whereby the path traversed by each group of said blades overlaps the paths of adjacent groups of blades thereby insuring uniform agitation of all the material within said cylinder.

CHAS. 0.. LAVET L

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