US3341949A

US3341949A - Dryer seals

Info

Publication number: US3341949A
Application number: US446593A
Authority: US
Inventors: Flaith George Donald; Charles E Hoffman
Original assignee: Proctor and Schwartz Inc
Current assignee: Proctor and Schwartz Inc
Priority date: 1965-04-08
Filing date: 1965-04-08
Publication date: 1967-09-19
Anticipated expiration: 1984-09-19
Also published as: DE1629038B1; GB1091378A

Description

Sept. 19, 1967 G. D. FLAITH ETAL DRYER SEALS 4 Sheets-Sheet 1 Filed April 8, 1965 FIG. I.

FIG.3..

FIGZ.

FLAITH CHARLES E. HOF'F MAN INVENTOR Si GEORGE DONALD ATTYS' DRYER SEALS Filed April 8, 1965 I 4 Sheets-Sheet 2 FIG. 5.

FIG4

INVENTORSZ GEORGE DONAL D FLAITH BY CHARLES E. HOFFMAN ATTYS' Sept. 19, 1967 G. D. FLAITH ETAL DRYER SEALS 4 Sheets-Sheet 5 Filed April 8, 1965 FIG? FIQIO.

FIGS

INVENTORS.

GEORGE DONALD FLAITH CHARLES E,HOFFMAN 'W ATTYSI G. D. FLAITH ETAL Sept. 19, 1967 DRYER SEALS 4 Sheets-Sheet 4 Filed April 8, 1965 FIGIZ.

e ewewe e e o c a e e e o e e 6 e e mm fir vm mm S R O T N E V N GEORGE DONALD FLAITH CHARLES E. HOFFMAN ATTYS' United States Patent 3,341,949 DRYER SEALS George Donald Flaith, Wyndmoor, and Charles E. Hoffman, Hatboro, Pa, assignors to Proctor 8: Schwartz, Inc, Philadelphia, Pa., a corporation of Pennsylvania Filed Apr. 8, 1965, Ser. No. 446,593 17 Claims. (Cl. 34218) The present invention relates to improvements in conveyor and drum dryers and is particularly adapted to dryers for drying loose, fibrous, granular and like materials.

In conveyor and drum dryers, the material to be dried is transported through a drying chamber on a foraminous supporting surface and is dried by passing heated air vertically through the material as it moves through the chamber. The drying of loose, fibrous, granular and like materials creates difliculties due to the tendency of these materials to become entrained in air passing around the edges of the material supporting surface. In conveyor type dryers a small portion of the material tends to slip past the supporting surface and collect and dry upon the conveyor side chains greatly increasing the cost of chain maintenance and requiring periodic shutdowns for cleaning purposes. In drum type dryers the material tends to collect upon the drum rollers causing similar difliculties. In both types of dryers, the accumulation of material around the drive elements increases the fire hazard due to increased friction, and results in a contamination and loss of substantial amounts of material.

Earlier attempts at overcoming this problem have utilized various types of mechanical side guards including combinations of fixed and traveling guards. More recent attempts have employed auxiliary air flows adjacent the edge of the material supporting surface to control the material particles. In one arrangement, for example, a separate duct network and air supply is provided to direct an air flow across the conveyor chains to clear the chains of stray material. None of the previous developments, however, has proven entirely satisfactory for drying loose materials of low density. For the most part, proposed arrangements have been complex structures which are expensive to manufacture and maintain.

In view of the above it is a primary object of the present invention to provide a dryer seal construction which effectively prevents the escape of material particles along the side edges of the material supporting means.

An additional object of the invention is to provide a dryer seal as described which may be employed with a conveyor dryer, hold-down conveyor dryer or a drum dryer.

Another object of the invention is to provide a dryer seal as described of a simple and inexpensive construction which requires a minimum amount of maintenance.

Still another object of the invention is to provide a dryer seal as described which is adapted for use with conveyors having upward or downward drying air flows.

A still further object of the invention is to provide a dryer seal as described which, by regulation of the air flow therethrough, may be adapted for use with a variety of conveyed materials.

Additional objects and advantages of the invention will be more readily apparent from the following detailed description thereof when taken together with the accompanying drawings in which:

FIG. 1 is a transverse sectional view of a conveyor dryer having conveyor seals in accordance with the present invention;

FIG. 2 is an enlarged view showing the details of one of the conveyor seals shown in FIG. 1;

FIG. 3 is a View taken along line 3-3 of FIG. 2;

FIGS. 4 and 5 are views similar to FIG. 2 showing Patented Sept. 19, 1967 "ice modified airflow control arrangements which may be employed with the conveyor seal;

FIG. 6 is an enlarged fragmentary sectional view of the flexible seal means utilized in all of the illustrated embodiments of the invention;

FIG. 7 is a transverse sectional View of a conveyor dryer having an upward drying air flow which employs conveyor seals embodying the present invention;

FIG. 8 is an enlarged view showing the details of one of the conveyor seals of the conveyor dryer of FIG. 7;

FIG. 9 is a transverse sectional view showing a conveyor dryer having a hold-down conveyor, both the material supporting conveyor and the hold-down conveyor employing seals in accordance with the present invention;

FIG. 10 is an enlarged fragmentary sectional view of the seals of the dryer shown in FIG. 9;

FIG. 11 is a fragmentary sectional view illustrating an adjustable baflle arrangement for controlling air flow through a seal;

FIG. 12 is a transverse sectional view of a drum type dryer utilizing the present seal arrangement; and

FIG. 13 is a simplified sectional view taken along line 13-13 of FIG. 12.

Referring to the drawings, FIG. 1 shows a conveyor dryer of a conventional type including a dryer housing 14 defining a drying chamber 16 therewithin in conjunction with the housing floor 18 and partition 20. The upper run 22 of a foraminous conveyor extends transversely across the drying chamber 16, the conveyor chains 24 thereof being supported by tracks 26 on the housing. The lower return run 28 of the conveyor travels beneath the floor 18 on the tracks 30.

Openings 32 in the partition 24) below the conveyor upper run permit air flow from the drying chamber into the conditioning chamber 34 wherein the air passes 'upwardly through heaters 36 into the fan 38 driven by motor 40. The fan discharges the heated air through the openings 42 in the partition 20 into the upper region of the drying chamber. Heated air is thus circulated downwardly through the drying chamber to dry materials conveyed therethrough on the upper run 22 of the conveyor.

Referring additionally to FIGS. 2 and 3, wherein one side of the conveyor and details of the seal arrangement are shown, an inner guard element 44 of sheet material is vertically mounted with its lower edge 46 spaced above the conveyor run 22 by attachment at its upper end to an inclined perforated sheet 48 secured to the housing partition 20. An outer guard element 50 attached to the housing partition 20 is spaced outwardly from the inner guard element 44 and includes an inclined portion 52 parallel to the perforated sheet 48 and a vertical portion 54 parallel to the inner guard element 44. As shown most clearly in FIG. 6, an inwardly inclined lower edge portion 56 of the outer guard element 50 includes a flexible seal strip 58 extending downwardly therefrom which is attached thereto by means of bolts 60 A Teflon-impregnated cloth has been utilized for the flexible seal strip with excellent results although other suitable materials could be employed.

Secured along the edge of the conveyor run in opposed relation to the inner and

outer guard elements

44 and 50 is a sealing plate 62 which extends inwardly beyond the plane of the inner guard element 44. The flexible seal strip 58 is in sealing engagement with the plate 62, the bolts 60 being spaced a suflicient distance from the lower edge of the seal strip to permit a certain deformation of the seal strip to insure a continuous sealing contact with the plate.

Nozzles 64 extending transversely between the upper edges of the inner guard elements 44 provide a regulated distribution of the drying air flow onto the conveyed material. During operation of the dryer, heated drying air flows from the upper regions of the drying chamber through '3 Q) the nozzles 64 onto the material carried by the forarninous conveyor run 22. A portion of the drying air flow is diverted through the perforated sheet 48 into the sealing air channel 65 formed between the inner and

outer guard elements

44 and 50. The air flowing through this channel passes through the narrow slot formed between the lower end 46 of the inner guard element and the upper surface of the plate 62. Due to the inward extent of the plate 62 beyond the plane of the inner guard element, an air flow parallel to the plate is provided in this region which serves to clear material from the edge 46 of the inner guard element and prevents material from entering between the inner guard element and the sealing plate.

Air leakage from the sealing air channel to the low pressure region behind the outer guard element is prevented by the flexible seal strip 58 which is in continuous contact with the plate 62. The possibility of leakage is further reduced by the location of this seal strip at the narrowest part of the sealing air channel, at which point the pressure on the seal is low due to the increased velocity of the air flow.

Since too pronounced a sealing air flow along the plate 62 may have a disrupting effect on the conveyed materials and particularly those of low density, the air flow through the sealing channel is controlled by selection of an appropriate perforated sheet 48. For dryer installations wherein a variety of materials are to be dried, an adjustable bafile arrangement, such as that shown in FIG. 11, may be substituted for the perforated sheet 48. In FIG. 11, the baflle plates 67 mounted between the inner and

outer guard elements

44 and 50 may be rotated to provide the desired air fiow through the sealing air channel.

Related modifications for controlling the drying air flow are shown in FIGS. 4 and 5. In FIG. 4, an air distribution plate 68 is substituted for the nozzles 64 shown in FIGS. 1-3 to distribute the air flow over the conveyed material while the sealing air channel is open to the upper region of the drying chamber. In this arrangement the air pressure in the sealing air channel will be slightly greater than that over the material due to a pressure drop through plate 68. In the arrangement shown in FIG. 5, an air distribution plate 70 extends the entire width of the drying chamber and thus regulates the air flow over the material to be dried as well as into the sealing air channels. The air pressure at the bottom of the sealing air channel should of course be at least equal to and is preferably greater than the air pressure acting on the lower layers of the conveyed material to insure that an air flow will be maintained through the sealing air channel.

Referring to FIGS. 7 and 8, the described seal arrangement is shown adapted for use with a conveyor dryer wherein the drying air flow passes upwardly rather than downwardly through the conveyed material. The positions of the heaters 36' and the fan 38' are reversed from that of the embodiment of FIG. 1 so that heated air is introduced beneath the conveyor run 22'. As shown in FIG. 8, the inner guard element 44' is supported by an imperforate inclined sheet 72 secured to the housing. The air flow into the sealing air channel 65' passes upwardly around the conveyor chains 24' and over the upper edge of the vertical portion 54 of the outer guard element 50', there being no inclined portion equivalent to the portion 52 shown in FIG. 2. The outer guard element 50' is supported by means of spaced transverse members (not shown) extending from the housing partition 20'. The seal functions in the embodiment of FIGS. 7 and 8 in the same manner as that described above.

With reference to FIGS. 9 and 10, a conveyor similar to that shown in FIGS. 8 and 9 but including a hold-down conveyor 74 is illustrated and the corresponding elements are numerically identified with a double prime. The lower and upper runs 76 and 78 of the hold-down conveyor are supported by conveyor chains 80 on tracks 82 secured to the housing. The material to be dried is carried on the conveyor run 22' and is prevented from becoming entrained in the upwardly directed drying air flow by the lower run 76 of the hold-down conveyor.

As shown in FIG. 10, the edges of both the

conveyor run

22 and 76 are provided with a seal in accordance with the present invention. The inner guard element 84 serves the dual purpose of forming one side of the lower sealing air channel 65 as well as an upper sealing air channel 86. An upper outer guard element 88 supports a flexible seal strip 90 in contact with a sealing plate 92 on the underside of the hold-down conveyor run 76. The operation of the seals is the same as that described above, the seals providing an air flow through the sealing air channels 65" and 86 to prevent material particles from reaching the conveyor chains 24" and 80.

In FIGS. 12 and 13, the invention is shown applied to one drum of a drum type dryer. A foraminous drum 94 is supported by the wheels 96 extending from the dryer housing 98 and driven in rotation by chain means (not shown). In this instance, material to be dried is carried over only the upper half of the drum and a fan assembly 100 is accordingly mounted internally of the drum to draw air inwardly through the upper half of the drum and exhaust the air into the housing through the lower half of the drum.

The seal arrangement illustrated is similar to that shown in FIG. 2, inner guard elements 102 extending parallel with the edges of the drum and being secured to the housing by the perforated sheets 1M. Nozzles 106 extending between the inner guard elements distribute the flow of drying air uniformly across the foraminous drum. Outer guard elements 108 extending from the housing establish sealing air channels 110 in conjunction with the inner sealing elements 102. Sealing plates 112 on the edges of the drum cooperate with flexible seal strips 114 on the inclined lower edge portions of the outer guard elements to effect an air tight seal around the upper of the drum as illustrated in FIG. 13.

In operation, the fan assembly 100 creates an air flow through the nozzles 106 into the upper half of the drum and, at the same time, draws air through the perforated sheets 104 and channels 110 to provide the above-described sealing effect. Since in the typical drum dryer there are normally at least two adjacent drums arranged to transfer material for example from the lower half of one to the upper half of the other, it should be understood that the type of seal arrangement illustrated would also be utilized to seal such additional drum or drums.

Manifestly, changes in details of construction can be effected by those skilled in the art without departing from the spirit and the scope of the invention as defined in and limited solely by the appended claims.

We claim:

1. In a dryer including a housing defining a drying chamber, a foraminous conveyor means disposed within said drying chamber, and means for directing a flow of drying air through the foraminous conveyor means for drying material carried thereon, the improvement comprising a seal along an edge of the conveyor means for preventing escape of material therealong, said seal comprising an inner guard element secured to the housing and extending parallel to an edge of the conveyor means, an outer guard element secured to the housing and spaced outwardly from said inner guard element, said inner and outer guard elements defining therebetween a sealing air channel, a flat horizontal sealing plate on the conveyor means extending in opposed relation beneath the edge of both said inner and outer guard elements, a flexible sealing means extending along the length of said outer guard element at the narrowest part of said sealing channel, said flexible sealing means being in sealing contact with said sealing plate along the length thereof, and means providing an air flow between said inner and outer guard elements to direct a sealing flow of air between said inner guard element and said sealing plate thereby preventing the entrance of conveyed materials therebetween. i

2. In a dryer including a housing defining a drying chamber, a foraminous conveyor means disposed within said drying chamber, and means for directing a flow of drying air through the foraminous conveyor means for dying material carried thereon, the improvement comprising a seal along an edge of the conveyor means for preventing escape of material therealong, said seal comprising an inner guard element secured to the housing and extending parallel to an edge of the conveyor means, an outer guard element secured to the housing and spaced outwardly from said inner guard element, said inner and outer guard elements defining therebetween a sealing air channel, a flat horizontal sealing plate extending along the edge of the conveyor means beneath the edges of both said inner and outer guard elements, said inner guard element being disposed in substantially perpendicular relation to the conveyor means with the adjacent edge thereof terminating in spaced relation from said sealing plate, Said-sealing plate extending inwardly beyond the plane of said inner guard element, a flexible sealing means extending along the length of said outer guard element at the narrowest part of said sealing channel, said flexible sealing means being in sealing contact with said sealing plate along the length thereof, and means providing an air flow between said inner and outer guard elements to direct a sealing flow of air between said inner guard element and said sealing plate thereby preventing the entrance of conveyed materials therebetween.

3. In a dryer including a housing defining a drying chamber, a foraminous conveyor means disposed within said drying chamber, and means for directing a flow of drying air through the foraminous conveyor means for drying material carried thereon, the improvement comprising a seal along an edge of the conveyor means for preventing escape of material therealong, said seal comprising an inner guard element secured to the housing and extending parallel to an edge of the conveyor means, an outer guard element secured to the housing and spaced outwardly from said inner guard element, a flat sealing plate extending along the edge of the conveyor means in opposed relation to said inner and outer guard elements, said inner guard element being disposed in substantially perpendicular relation to the conveyor means with the adjacent edge thereof terminating in spaced relation from said sealing plate, said sealing plate extending inwardly beyond the plane of said inner guard element, a flexible sealing means extending along the length of said outer guard element, said flexible sealing means being in sealing contact with said sealing plate along the length thereof, said inner and outer guard elements defining a channel for a sealing air flow directed between said inner guard element and said sealing plate, said outer guard element being inwardly inclined adjacent said flexible sealing means so that said flexible sealing means contacts said sealing plate at the narrowest part of said channel, and means providing an air flow through said channel to prevent the entrance of conveyed materials between said inner guard element and said sealing plate.

4. The invention as claimed in claim 3 wherein said means providing an air flow through said channel comprises means for diverting a portion of the flow of drying air from the drying chamber through said channel.

5. The invention as claimed in claim 3 including means for regulating the flow of air through said channel.

6. The invention as claimed in claim 5 wherein said means for regulating the air flow through said channel comprises a perforated sheet extending between said inner and outer guard elements.

7. The invention as claimed in claim 5 wherein said means for regulating the flow of air through said channel comprises adjustable baflle means between said inner and outer guard elements.

8. In a conveyor dryer including a housing defining a drying chamber, a foraminous conveyor run horizontally disposed within said drying chamber, and means for directing a flow of drying air through the foraminous conveyor run for drying material carried thereon, the improvement comprising a seal along an edge of the conveyor run for preventing escape of material therealong, said seal comprising a vertical inner guard element secured to the housing and extending parallel to an edge of the conveyor run, an outer guard element secured to the housing and spaced outwardly from said inner guard element, a flat horizontal sealing plate on the conveyor run in opposed relation to said inner and outer guard elements, said sealing plate extending inwardly beyond the plane of said inner guard element, each of said guard elements terminating in a lower edge spaced above said sealing plate, a flexible seal strip extending along the lower edge of said outer guard element, said flexible seal strip being in sealing contact with said sealing plate along the length thereof, and means for diverting a portion of the flow of drying air from the drying chamber between said inner and outer guard elements to direct a sealing flow of air between said inner guard element and said sealing plate thereby preventing the entrance of conveyed materials therebetween.

9. The invention as claimed in claim 8 wherein said inner and outer guard elements define a channel for a sealing air flow and wherein said outer guard element is inwardly inclined so that said flexible seal strip contacts said sealing plate at the narrowest part of said channel.

10. The invention as claimed in claim 9 including means for regulating the air flow through said channel.

11. The invention as claimed in claim 10 wherein said means for regulating the air flow through said channel comprises a perforated sheet extending between said inner and outer guard elements.

12. The invention as claimed in claim 10 wherein said means for regulating the air flow through said channel includes adjustable bafile means spaced between said inner and outer guard elements.

13. In a conveyor dryer including a housing defining a drying chamber, a first foraminous conveyor run hori zontally disposed within said drying chamber for conveying material therethrough, a second foraminous conveyor run parallel with and spaced above said first conveyor run to contain the material on said first conveyor run, and means for directing a flow of drying air upwardly through the foraminous runs for drying material carried therebetween, the improvement comprising seals along the edges of the spaced conveyor runs for preventing escape of material therealong, each said seal comprising a vertical inner guard element secured to the housing and extending parallel to the edges of the conveyor runs, upper and lower outer guard elements secured to the housing and spaced outwardly from said inner guard element, flat sealing plates along the edges of the upper and lower conveyor runs in opposed relation to said inner and outer guard elements, a flexible seal strip extending along the length of each said outer guard element, each said flexible seal strip being in sealing contact with the respective opposed sealing plate along the length thereof, said sealing plates extending inwardly beyond the plane of said inner guard element, said inner guard element terminating in spaced relation from each said sealing plate, and means for diverting a portion of the flow of drying air from said drying chamber into the channels between said inner and outer guard elements to direct a sealing flow of air between said inner guard element and said sealing plates thereby preventing the entrance of conveyed materials therebetween.

14. The invention as claimed in claim 13 wherein said .outer guard elements are inwardly inclined so that said flexible seal strips contact said sealing plates at the narrowest part of the channels between said inner and outer guard elements.

15. In a drum dryer including a housing defining a drying chamber, a foraminous drum rotatably disposed within said drying chamber, and means for directing a flow of drying air through said foraminous drum for drying material carried thereon, the improvement comprising a seal along an edge of the drum for preventing escape of material therealong, said seal comprising an inner guard element secured to the housing and extending parallel to an edge of the drum, an outer guard element secured to the housing and spaced outwardly from said inner guard element, a flat sealing plate extending along the edge of the drum in opposed relation to said inner and outer guard elements, said inner guard element being disposed in substantially perpendicular relation to the drum with the adjacent edge thereof terminating in spaced relation from said sealing plate, said sealing plate extending inwardly beyond the plane of said inner guard element, a flexible sealing means extending along the length of said outer guard element, said flexible sealing means being in sealing contact with said sealing plate along the length thereof, and means providing an air flow between said inner and outer guard elements :to prevent the entrance of ma. terials between said inner guard element and said sealing plate.

16. The invention as claimed in claim 15 wherein said inner and outer guard elements define a channel for a sealing air flow directed therebetween, said outer guard element being inwardly inclined adjacent said flexible sealing means so that said sealing means contacts said sealing plate at the narrowest part of said channel.

17. The invention as claimed in claim 15 wherein said means providing an air flow between said inner and outer guard elements comprises means for diverting a portion of the flow of drying air from the drying chamber into said channel between said inner and outer guard elements.

References Cited UNITED STATES PATENTS 2,336,698 12/ 1943 Morrill 34242 X 2,758,389 8/1956 Kelley 34242 X 2,773,312 12/1956 Peck 34242 X 2,981,007 4/1961 Fleissner 34-115 3,084,447 4/1963 Fleissner 34ll5 FREDERICK L. MATTESON, 111., Primary Examiner.

JAMES W. WESTHAVER, Examiner.

C. R. REMKE, H. B. RAMEY, Assistant Examiner

Claims

8. IN A CONVEYOR DRYER INCLUDING A HOUSING DEFINING A DRYING CHAMBER, A FORAMINOUS CONVEYOR RUN HORIZONTALLY DISPOSED WITHIN SAID DRYING CHAMBER, AND MEANS FOR DISRECTING A FLOW OF DRYING AIR THROUGH THE FORAMINOUS VEYOR RUN FOR DRYING MATERIAL CARRIED THEREON, THE IMPROVEMENT COMPRISING A SEAL ALONG AN EDGE OF THE CONVEYOR RUN FOR PREVENTING ESCAPE OF MATERIAL THEREALONG, SAID SEAL COMPRISING A VERTICAL INNER GUARD ELEMENT SECURED TO THE HOUSING AND EXTENDING PARALLEL TO AN EDGE OF THE CONVEYOR RUN, AN OUTER GUARD ELEMENT SECURED TO THE HOUSING AND SPACED OUTWARDLY FROM SAID INNER GUARD ELEMENT, A FLAT HORIZONTAL SEALING PLATE ON THE CONVEYOR RUN IN OPPOSED RELATION TO SAID INNER AND OUTER GUARD ELEMENTS, SAID SEALING PLATE EXTENDING INWARDLY BEYOND THE PLANE OF SAID INNER GUARD ELEMENT, EACH OF SAID GUARD ELEMENTS TERMINATING IN A LOWER EDGE SPACED ABOVE SAID