US2716290A - Drier - Google Patents

Description

H. F. IRVING Aug. 30, 1955 DRIER 4 Sheets-Sheet 1 Filed June 21, 1951 INVENTOR. f/ffl/ld/ 77 .2 ryz r1 TTJ/r/VA'KS Aug. 30, 1955 H. F. IRVING DRIER Filed June 21, 1951 4 Sheets-Sheet 2 -Z INVENTOR.

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H. F. lRVlNG DRIER 4 Sheets-Sheet 4 Filed June 21 1951 United States Patent 0 DRIER Henry F. Irving, Saginaw, RIich, assignor to Baker Perkins Inc., Saginaw, Mich, a corporation of New York Application June 21, 1951, Serial No. 232,685

7 Claims. (CI. 3457) This invention relates to apparatus for drying solid materials such as various types of salts or other crystalline or granular materials, and is an improvement of applicants copending patent application Serial No. 50,856, filed September 23, 1948, for improvements in Drier, now patent #2,634,5l2.

It is an object of this invention to provide apparatus of the aforementioned type, which will remove quantities of liquid from solid materials in a much more efficient, economical and simple manner than has been heretofore known in the art.

In the field of drying various salts, such as sodium chloride, ammonium phosphate, and the like, there is a great need for an economical, compact machine or device which will completely dry the salt, or other suitable material, from its initial slurry state, wherein a large percentage of water is mixed with the solid material, in a rapid and efficient manner. While centrifugal separators satisfactorily remove the major portion of the liquid from a slurry, there is a residual film of liquid on the solid particles which cannot be removed by centrifugal action. Accordingly, it is the general object of the present invention to provide means to completely dry solid materials containing minor quantities of liquid and which, therefore, is effective to complete the drying of slurries or the like which have been partially dried by other forms of driers, such as centrifugal driers. In general, the device of this invention is primarily adapted for use to complete the drying of material containing ten per cent of liquid or less and is readily adaptable to remove varying quantities of moisture and to discharge the dried material at a desired temperature. The device of this invention furthermore effects the final drying operation by the use of hot gases for a very brief period of time, in a more efiicient manner than has been heretofore known.

it is a further object of this invention to provide in apparatus of the aforementioned type, a more or less cylindrical chute into which partially dried solid materials are rotatably and axially fed, which chute is provided with a baffle to direct the material along a helical path as it moves from the inlet end of the chute to the discharge end thereof, while heated gases are passed through the material so as to dry the same.

It is a still further object of this invention to provide in a chute of the aforementioned type, a novel waterrepellant and heat abrasive resistant liner for the battle and chute wall, so that the solid materials flowing through the chute will not adhere to the baiile or the wall.

It is a still further object of this invention to provide an apparatus of the aforementioned type, a tangential heated gas inlet in the chute which will direct heated gases into the chute tangentially thereof at a relatively high velocity so that the material to be dried which is passing through the chute is directed into the path of the heated gases during each revolution and so that the circular motion of the heated gases inside the chute will act as a motivating force to keep the material in motion through the chute.

It is a still further object of this invention to provide in apparatus of the aforementioned type, means for adjusting the amount or velocity of heated gases flowing to the chute so that the speed of travel of the material through the chute may be varied, as well as the drying action and the discharge temperature of the dried material.

It is a still further object of this invention to provide apparatus of the aforementioned type which will act as an efiicient dust collector so that no objectionable amount of dust will be present in the air discharged from or in the vicinity of the chute.

It is a still further object of this invention to provide apparatus of the aforementioned type, in which the heat transfer from the heated gases to the material is so efficient that it is not always necessary to recirculate the heated gases through the heater and blower system, thus eliminating the necessity of providing expensive corrosion resistant blowers and heater units.

These and other objects of this invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which:

Figure l is a sectional view of one form of the final drying apparatus of this invention and means for axially and centrifugally feeding solid materials thereto, taken along the line 11 of Fig. 2;

Fig. 2 is an end elevational view, taken in the direction of the arrow 2 of Fig. 1, with parts broken away in section;

Fig. 3 is an enlarged sectional view of the structure illustrated in Fig. 1, taken within the area or circle 3 of Fig. 1;

Fig. 4 is an enlarged sectional view of the structure illustrated in Fig. 1, taken within the area or circle 4 of Fig. 1;

Fig. 5 is an enlarged sectional view of the structure illustrated in Fig. 2, taken along the line 5-5 thereof;

Fig. 6 is an enlarged sectional view of the structure illustrated in Fig. 2, taken along the line 6-6 thereof; and

Fig. 7 is a sectional view of a further embodiment of the invention, illustrating a drying device including a centrifugal drier associated with a final drier.

Referring now to the embodiment of the invention illustrated in Figs. l-6, it will be seen that a feeding mechanism 9 is provided for axially and centrifugally feeding solid materials from a suitable partial drying device into a generally cylindrically shaped chute 11. The chute 11 is stationarily supported by suitable framework 13 and surrounded by a housing 15. The feeding device 9 includes a conduit 17 having a feed screw 19 therein, which axially feeds the material from the partial drying device through the conduit. In order to impart a rotary and axial motion to the materials being discharged from the feeding mechanism into the chute 11, a rotating sleeve 21,

' having a frusto conical inner wall 23 and fins 25, is rotatably supported on the framework 13. The outer end of the sleeve 21 overlaps the discharge end of the conduit 17 so that the solid material will be fed from the conduit into the sleeve. The sleeve 21 is rotatably driven at high H speed by any suitable means such as roller 27, which is connected in a conventional manner with a suitable driving means and which frictionally engages an annular ring or track 29 on the outer periphery of the sleeve 21. The material therefore will be moved from the partial drying i device by the feed mechanism 9 and will be discharged from the sleeve 21 through an inlet opening into one end of the chute 11 with a high velocity tangentially of the sleeve, which will tend to cause the material to engage the wall of the chute and slide helically therethrough.

The chute 11 is provided with a peripheral wall 31 which is generally circular in cross section. Extending around the inner periphery of the chute Wall 31 is a spiral opening or end of the chute 11 to a point adjacent the outlet end or opening of the chute, which in the illustrated embodiment, is at the opposite end of the wall 31.

The chute 11 is provided with a tangentially extending inlet 37 for heated gases. The inlet 37 may be formed in any suitable manner such as by cutting out a portion of wall 31, but is illustrated as being formed by in effect unwrapping the lower portion of the chute wall 31, so that a portion 41 of the chute wall extends horizontally below and beyond the lower end 42 of the adjacent curved or circular portion of the wall, disposed above the wall portion 41, as can be seen in Fig. 2. The outer end of the wall portion 41 is upwardly bent at 43 to provide a support for a vertical wall or plate 45 which extends from the front to the rear of the chute to close and define one side of a heated gas or plenum chamber 46. The wall 45 is connected at its upper end with the outer periphery of the wall 31 at 47 and is connected with the upwardly bent portion 43, as can be seen in Fig. 2. Front and rear end walls 48 and 49 close the opposite ends of the plenum chamber and a conduit or inlet 50 communicates with the chamber and is connected to a blower and heater unit (not shown), for delivering heated gases to the chamber.

The inlet opening 37 extends the entire length of the chute so that heated gases will flow through the inlet opening 37 from the inlet end of the chute to the outlet end thereof. A vertical plate member 51 is connected to the chute, in the plenum chamber between the walls 48 and 49, and a rear inlet opening adjusting plate 52 is disposed between wall 48 and plate 51, while a front inlet opening adjusting plate 53 is disposed between plate 51 and wall 49. The adjusting plates 52 and 53 extend horizontally, substantially parallel to the wall portion 41, in a side-byside relationship, so that their inner ends extend into the inlet opening 37. The adjusting plates are provided with vertically extending plate portions 55 at each end thereof, each of which has a vertical slot 57 therein. A bolt 59 extends through each of the slots and an aperture in the adjacent wall or plate, and a nut'61 is provided for clamping the adjusting plate vertical portions 55 in any desired vertical position on the walls and plates 48, 49 and 51. By loosening the nuts or bolts 59 or 61, the adjusting plates 52 and 53 can be adjusted vertically toward or away from the edge 42 of the chute inlet opening 37 to control the size of the opening and the velocity of hot gases that will flow into the chute. The inner end portions of the adjusting plates are slotted at 62 to permit portions of the baflle 33 to extend downwardly therethrough to engage and abut the chute wall portion 41. The extreme inner ends of the adjusting plates are bent down and notched out to provide a plurality of short vertical legs 63 disposed in spaced relationship from the front to the rear of the chute, as shown in Figs. 2, 4 and 6. The lower ends of the legs 63 are adapted to abut the chute wall portion 41, when the plates are in their downwardmost adjusted position to provide drainage gaps between the adjusting plates and the wall portion 41 of the chute. By providing two adjusting plates 52 and 53, the flow of heated gases to the front and rear of the chute can be varied and thus provide a more variable gas control for the device.

The blower and heater unit (not shown) force heated gases, at a relatively high velocity, into the plenum chamber, and through the inlet 37 tangentially into the chute 11. Therefore, material which is traveling helically through the chute in engagement with the peripheral wall thereof,

will pass the inlet 37 once during each revolution of its movement, and the velocity of the heated gases flowing tangentially into the chute will act as a motivating force to helically move the particles through the chute toward the discharge end thereof, while the gases also act to dry the material. Therefore, depending upon the temperature of the heated gases and the type of material being dried, the retention time of the material in the chute can be easily altered by varying the velocity at which the heated gases enter the chute.

The chute housing 15 is provided with a suitable gas outlet 61 in the upper portion thereof, so that the gases which pass from the chute will flow out of the open end thereof into the outlet 61. The outlet 61 may be connected by a suitable conduit to the main blower of the apparatus, or where it is not desired to recirculate the gases, to an exhaustblower which creates a slight negative pressure in the chute preventing the escape of any dust to the immediate vicinity of the drier. The circular motion of gases inside the chute keeps the solid particles in motion and as they travel around the inside of the chute centrifugal force holds them against the peripheral wall 31. The chute therefore approximates a cyclone dust collector placed horizontally so that very little dust is carried out with the exhaust air and no additional dust collecting equipment is normally required to prevent the dust from flowing out with the heated gases through the opening 61.

Due to the fact that the heated gases enter the chute throughout its length and flow in a circular motion around the chute, and due to the fact that the particles are directed past and into the inlet stream of hot gases, the heattransfer from the air to the material is excellent and the air can be discharged from the drier at a temperature of only ten to twenty degrees F. higher than the temperature of the discharged dried material. This means,

of course, that. the drier will operate economically at a high heat efficiency, without the necessity of always recirculating the heated gases, so that where corrosive materials are to be dried in the device the main blower and heating units need not be made of corrosion resistant materials and only the relatively inexpensive exhaust blower should be made of corrosive resistant material. If the heat transfer efliciency of the system were not excellent, as described, it would be advantageous and desirable to recirculate the heated gases through the main blower and heater unit and in such case, if corrosive material were being dried the same would have to be corrosion resistant. Therefore, the drier of this invention eliminates the necessity of expensive corrosion resistant equipment.

Furthermore, due to the fact that the outlet gas tem= perature is close to that of the temperature of the discharged material, simple means may be devised for controlling the temperature of the discharged material. By using a control having a sensitive element in the outlet gas stream and controlling the inlet gas temperature, the heat input can be varied to take care of the fluctuations in the material load so that the material can be discharged as a dried solid at a desired given temperature- Thus, the drier can bring the material to almost any desired final moisture content and tests have been run in which the material leaving the sleeve 21 had a moisture content of from 5% to 7%, while the material leaving the chute 11 was dried to a moisture content of only .1%

If the drier is to be used for drying materials such as salt, it has been found that the relatively high temperature of the chute walls tends to dry out the film of solid material so that the material tends to adhere to the wall of the chute and thereby increases the coefficient of friction of the walls so that the material will not slide freely thereon. Clogging within the drier may result in such cases and therefore the peripheral wall 31 of the chute and the baffle 33 are lined with an abrasive resistant, water repellant materialGS which will withstand at least 350 F. of. heat.

5.. The preferred lining material for this purpose is polytetrafluoroethylene, a plastic which is sold under the trade name Teflon, but other suitable materials such as glass, which have the aforementioned characteristics, may be used.

In order to line the baffle 33 and the chute wall 31 in a simple, economical manner, a one-piece channel shaped Teflon liner or strip, is extended around the inner periphery of the chute wall, in engagement with the side faces of the baflle. The liner includes a pair 'of inwardly extending leg portions 67 and a bight portion 69. The bight portion 69 engages the chute wall 31 between adjacent side faces of the baflle and the leg portions 67 of the liner engage the opposed side faces of the adjacent portions or members of the baifle 33. The liner 65 is secured to the bafile by any suitable means such as clips 71, which extend over the inner or free ends of the adjacent liner leg portions 67 and the inner end of the baflie portion therebetween. A bolt and nut 73 may be employed to positively connect each clip 71 to the liner and baflie or the clip may be c'rimped to retain the liner in position such as shown at the opposite ends of the chute in Fig. 1. In addition, the top faces of the adjusting plates 52 and 53, in the inlet opening 37 are covered by a Teflon liner strip 75, which strip may be attached to the adjusting plates by means of screws or the like. The bight portion of the Teflon liner above the chute inlet opening 37 is cut out and pressed down to engage or cover the sides of the adjacent baflle portions so as not to interfere with or prevent heated gases flowing through the gas inlet opening into the chute, as described. Thus a continuous channel shaped liner is easily connected to the baflle to provide a water repellant, abrasive and heat resistant liner for the baflle and the peripheral wall of the chute.

In the embodiment of the invention illustrated in Fig. 7, a centrifugal separator 77, of known construction, is illustrated for partially drying the solid materials and feeding hem into the drier with a desired tangential velocity. With the centrifugal separator of this device, a slurry of material consisting of a large percentage of liquid, is fed into an inlet tube or conduit 79. The slurry flows through the tube 79 into a funnel shaped member 31 which discharges it into a rotating basket or housing 83,

having a plurality of openings 85 in the peripheral wall thereof, through which liquid may be discharged. A peripheral screen 87 is secured to the housing 83 inwardly of the peripheral wall thereof, so as to prevent the solid material from passing through the housing openings 85. The housing 83 is rotatably driven in any suitable manner through a hollow shaft 88, so that the majority of the liquid in the slurry will be centrifugally discharged and separated from the solid material through the openings 85. The centrifugal separator will, however, not remove all of the liquid from the solid material. The partially dried material is axially discharged more or less continuously from the open end of the housing 83 past a chamfered lip 89, by means of a reciprocating disk plate 91 which is axially reciprocated in any suitable manner by a shaft 93 which extends through the rotatable shaft 88. A wash Water inlet conduit 95 has one end extending into the drier for use in cleaning the same. The chute 11 and centrifugal separator 77 are supported on a suitable stand and framework 97 and housings and 99 close to chute 11 and separator 77.

The chute 11 is generally the same as that previously described, and has its inlet end or opening disposed adjacent to the centrifugal separator 77 so as to receive the material discharged therefrom. The inlet end of the chute 11 is supported on the framework 97 by means of member 101 and the discharge end of the chute is connected with the housing 15 in any suitable manner. Since the centrifugal separator may discharge the material into the chute at a higher velocity than is necessary, and thus cause undesirable Wear of the.

Teflon liner 65', a deflector 103 is provided in the inlet end of the chute adjacent the centrifugal separator 77 and a coolant jacket 105 surrounds the outer periphery of the deflector and is adapted to contain coolant for maintaining the deflector at a temperature which will prevent the solid material from adhering thereto. The partially dried material will be fed into the chute 11 by the centrifugal separator so that the material will slide around the liner 65' at the peripheral wall of the chute 11 by centrifugal force and the spiral baflies 33' will cause the material to follow a helical path through the chute to the discharge end thereof. The tangential air inlet 37 will direct heated gases tangentially into the chute in the manner previously described to aid in moving the material through the chute and to dry the same. The heated gases will, after passing through the material, flow out the discharge end of the chute and into an outlet conduit which may be connected with the main blower of the apparatus for recirculation, or with an exhaust blower as previously described.

It will thus be seen that the drier of this invention may be used with any form of centrifugal separator or means for feeding material into the chute, so as to cause the same to rotatably slide against the peripheral wall of the chute, and it will also be appreciated that in all cases the lining of water repellant and abrasive and heat resistant material may not be necessary, and also that While the chutes are illustrated as being disposed on a horizontal axis, a chute could be vertically mounted and discharge either upwardly or downwardly. In any event, the drier of this invention will dry the material to any desired moisture content in the most efiicient, simple and rapid manner heretofore known.

What is claimed is:

1. Apparatus for removing liquid from moist solid material, including a stationary chute having a peripheral surface, said chute having an inlet opening adjacent one end thereof and an outlet opening adjacent the opposite end thereof, a bafile connected with said chute and extending helically around said peripheral surface from a point adjacent the chute inlet opening to a point a jacent the chute outlet opening for directing material helically through the chute, mechanism for feeding said moist material into one end of said chute with a rotary component of motion and suflicient velocity to at least initially cause the material to slide around the walls of the chute in contact therewith means providing an opening in the peripheral surface of said chute through which heated gases may flow into said chute, a member connected with said chute and extending through said opening into said chute substantially tangentially to said peripheral surface, a plenum chamber adjacent said chute, means supporting said member in said plenum chamber so that the same may be adjusted therein to vary the size of said opening and thus control the flow of gases into said chute.

2. Apparatus for removing moisture from solid materials including a stationary chute having a peripheral wall which is generally circular in cross section, means rotating relative to said chute for feeding partially dried material into one end of said chute with a rotary component of motion to at least initially cause the material to engage and slide around the wall of the chute in contact therewith, a baflle connected with said chute, and extending helically around said chute peripheral surface from a point adjacent said one end of said chute to a point spaced therefrom, said chute having an outlet 3. Apparatus for removing liquid from moist solid material, comprising a stationary chute having a peripheral surface which is circular in cross section, a channel-sectioned, troughlike baflie connected with said chute and open to the interior thereof, said baffle eX- tending helically around said peripheral surface from a point adjacent one end of said chute to a point ad-,

jacent the opposite end thereof, means rotating relative to said chute for feeding the moist material into one end of said chute with a rotary component of motion and sufiicient velocity to at least initially cause the material to slide around the walls of the chute in contact therewith, said chute having an opening in said peripheral surface, and means for directing heated gas through said opening and the material moving thereover.

4. Apparatus for removing liquid from moist solid material, comprising a stationary chute having a peripheral surface which is circular in cross section, said chute having an inlet opening adjacent one end thereof and an outlet opening adjacent the opposite end thereof, a channel-sectioned, troughlike liner connected with said chute and open to the interior thereof, said liner extending helically around said peripheral surface from a point adjacent said chute inlet opening to a point adjacent said outlet opening, for directing material helically through said chute, said liner being formed of a material which is water repellant-and resistant to heat and abrasion, means rotating relative to said chute for feeding the moist material into one end of said chute with a rotary component of motion and suificient velocity to at least initially cause the material to slide around said chute liner in contact therewith, said peripheral surface and said liner having an opening therein, and means for directing heated gas through said opening and the material moving thereover.

5. Apparatus for removing liquid from moist solid material, comprising a stationary chute having a peripheral surface which is circular incross section, said chute hava ing an inlet opening adjacent one end thereof and an outlet opening adjacent the opposite end thereof, a channelsectioned, troughlike polytetrafluoroethylene liner connected with said chute and open to the interior thereof, said liner extending helically around said peripheral surface from a point adjacent said chute inlet opening to a point adjacent said outlet opening, for directing material helically through said chute, means rotating relative to said chute for feeding the moist material into one end of said chute with a rotary component of motion and sufficient velocity to at least initially cause the material to slide around said chute liner in contact therewith, .said peripheral surface and said liner having an opening therein, and means for directing heated gas through said opening and the material moving thereover.

6. Apparatus for removing liquid from moist solid material, comprising a stationary chute having a peripheral surface which is circular in cross section, a baflle connected with said chute and extending helically around said peripheral surface from a point adjacent one end of said chute to a point adjacent the opposite end thereof, means rotating relative to said chute for feeding said moist mate rial into one end of said chute with a rotary component of motion and suflicient velocity to at leastinitially cause the material to slide around the walls of the chute in contact therewith, said chute having a tangential opening in the peripheral surface thereof, and means adjacent said opening for directing heated gases therethrough generally tangentially to the chute peripheral surface, so that the heated gases will .flow in a circular path around said chute surface to aid in moving thematen'al through said chute, dry the same, and maintain the material in engagement with said peripheral surface. 1 r

7. Apparatus for removing liquid from moist solid material, comprising a stationary chute having a peripheral surface which is circular in cross section, said chute having an inlet opening adjacent one end thereof and an outlet opening adjacent the opposite end thereof, a channelsectioned, troughlike liner connected with said chute and open to the interior thereof, said liner extending helically around said peripheral surface from a pointadjacent said chute inlet opening to a point adjacent said outlet opening, for directing material helically through said chute, said liner being formed of a material which is water repellant and resistant to heat and abrasion, means rotating relative to said chute for feeding the moist material into one end of said chute with a rotary component of motion and suflicient velocity to at least initially cause the material to slide around said chute liner in contact therewith, said peripheral surface and said chute liner having a tan gential opening therein, and means adjacent said opening for directing heated gases therethrough generally tangentially to the chute peripheral surface so that the heated gases will flow in a circular path around said liner to aid in moving the material through said chute to dry the same and maintain the material in-engagement with said liner throughout its travel through said chute.

References Cited in the file of this patent UNITED STATES PATENTS 2,050,626 Otis Aug. 11, 1936 2,456,674 Caughey Dec. 21, 1948 2,461,134 Arnold Feb. 8, 1949 2,497,978 Carlson Feb. 21, 1950 2,520,747 Van Den Brock Aug. 29, 1950 FOREIGN PATENTS 426,951 Great Britain Apr. 8, 1935 OTHER REFERENCES Plastics, Teflon makes its debut, pages 32, 33 and 97, July 1, 1946. i

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