Segmented seal for rotary equipment.

(74) Proxy Onsagers Patentkontor AS, Oslo.

(JO) Priority Requested 08.06.86, US, 618904.

(54) NAME OF THE INVENTION IN SEGMENTS DIVIDED TEIN INSTALLATION FOR ROTARY EQUIPMENT.

(57) Summary

A sealing device (10) for effecting a seal between a stationary housing (12) and a rotatable cylinder (16) comprises a plurality of arcuate segments (40) arranged radially around the outer circumference of the cylinder (16). Each segment (40) has an axial sealing surface (100) with a radius approximately equal to the rotatable cylinder (16) and furthermore has end portions (102, 104) for overlapping adjacent segments (40) and thus providing a gap (103) and radial interface between said adjacent peripherally arranged segments. The sealing device (10) further comprises elastomeric elements (64) for sealing the gaps (103) formed by the adjacent overlapping segments (40), a spring-loaded cable (52) for tightening the segments (40) radially around the outer surface of the cylinder (16). circumference and threaded pins (44) for securely securing each segment (40) to the housing (12) while allowing radial displacement of each segment (12) independently of its adjacent segments.

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(56) Cited Publications U.S. (U.S.) Patent No. 2071914 286/20; 2937057 285/253; 4342555 (F 27 B 7/24) 4109924 (277/165), 3335643 (92/182).

The invention relates to a sealing device for providing a seal between a stationary housing and a rotatable cylinder, wherein the sealing device has a plurality of arcuate segments arranged radially around the outer circumference of the cylinder, each segment having an axial sealing surface with a radius equal to the radius of the rotatable cylinder. where the sealing device i.a. consists of a cable for tensioning the segments radially around the outer circumference of the cylinder, and further provided with devices for releasably fastening each segment to the housing and at the same time allowing radial displacement of each segment independently of the adjacent segments.

The grain processing and chemical industries have a need to remove moisture from raw materials, by-products and finished products. For example, breweries produce large quantities of brewery waste grains which constitute a very moist and very proteinaceous by-product of the brewing process. This by-product is useful in the cattle feed industry if the water is removed before the cattle are fed. Therefore, cost-saving techniques have been developed for removing moisture from such waste grains, using rotary steam pipe dryers. Such dryers are composed of a rotating cylindrical body with tubes arranged longitudinally in them and fed with steam to raise the temperature of the contents of the dryer and thereby remove moisture from it by evaporation. Alternatively, the contents of the dryer are heated by direct flame firing. This type of dryer is referred to as direct firing dryers.

Common to all rotating equipment used in the grain processing and chemical industries to dry or cool is a stationary intake housing to receive the product. The dried product exits the rotating equipment of a stationary drain housing. Consequently, in the prior art, devices have been developed to seal the stationary intake and drain housings relative to the rotating cylinder so that the product to be dried is not lost or the efficiency of the equipment is reduced.

Furthermore, a pressure gradient often develops from inside the equipment in relation to the atmosphere outside. These pressure gradients can be caused by the speed of the product in the equipment as well as by increases in the volume of heated, humid waste air. These pressure gradients make the problem of sealing the inlet and outlet ends of the equipment more serious, as they can cause either unfortunate loss of product through the sealing device or alternatively excessively strong intake of air, which reduces the efficiency of the equipment.

Prior art sealing devices are composed of articulated ring segments distributed around the circumference of the rotating cylinder and attached to the stationary housing of the rotating equipment. This device provides axial and radial sealing with respect to the rotating cylinder. However, this known apparatus becomes inefficient as the axial and radial sealing surfaces are worn. Furthermore, the older technique allows limited compensation for irregularities in the circular shape of the rotating cylinder, but this possibility is reduced when the known apparatus is worn during use.

In addition, the rotating equipment, when due to externally generated heat for drying, undergoes significant increases in dimension as its temperature is raised. This thermal expansion causes the previously known seal to have maximum efficiency in a limited temperature range, while it becomes less effective at temperatures outside this.

It is therefore desirable to provide a sealing device which allows for wear along the axial sealing surface of the rotating cylinder and also absorbs leaks due to irregularities in the axial sealing surface of the rotating cylinder. Furthermore, it is desirable to provide a sealing device that operates with maximum efficiency within a wide operating temperature range and can occupy a correspondingly wide range of thermal expansion and contraction of the rotating equipment.

Finally, it is desirable to provide a sealing device that reduces the leakage of product or atmosphere to a minimum at the axial and radial sealing surfaces where pressure gradients can be assumed to occur.

From U.S. Pat. No. 4,109,924 and U.S. Pat. No. 3,335,643 a circular seal is known which is arranged between a piston and a cylinder, and from U.S. Pat. No. 4,342,555 a sealing device for a rotating cylinder. In 4 109 924, however, overlapping connections are secured by means of a pin which does not allow mutual movement of the overlapping portions, neither in the radial direction nor in the circumferential direction.

U.S. Pat. No. 3,335,643 discloses an overlapping joint which can be moved in the circumferential direction, but in which radial relative movement of the parts is impeded due to a pin.

U.S. Pat. No. 4,342,555 discloses a sealing device for a dryer, comprising several segments arranged next to each other and having opposite, overlapping end portions, the segments being held in place by means of a bolt, and the device for tensioning of the segments consist of a cable.

However, even with an overall application of the prior art, an overlapping structure is not obtained which remains dense during radial movement as well as movement in the circumferential direction.

Therefore, in the practice of the present invention, in a presently preferred embodiment, a sealing device is provided for effecting sealing between a stationary housing and a rotating cylinder with a plurality of arcuate segments arranged radially around the outer circumference of the cylinder. Each segment has an axial sealing surface with a radius approximately equal to the rotating cylinder and in addition has an end portion for overlapping adjacent segments so that a gap and radial interface is formed between said adjacent peripherally extending segments. The sealing device further comprises means for sealing the gaps formed by the adjacent overlapping segments, means for tightening the segments radially around the outer circumference of the cylinder and means for attaching each segment removably to the housing, while at the same time allowing radial displacement of each segment regardless of its adjacent segments.

The mentioned and other features and advantages of the invention will be better understood from the following description and drawing which show embodiments of the sealing device according to the invention.

Fig. 1 is an elevational view of a rotary steam pipe dryer illustrating three separate sealing devices each constructed in accordance with the principles of this invention.

FIG. 2 is an elevational view of a typical sealing device taken along line 2-2 of FIG. ΐ.

Fig. 3 is a front view of a typical sealing segment.

Fig. 4 shows a typical sealing segment from the back.

FIG. 5 is a plan view taken from line 5-5 of FIG. 4.

FIG. 6 is a sectional view taken along line 6-6 of FIG. 2 on a larger scale.

FIG. 7 shows sections along line 7-7 of FIG. 2, also on a larger scale.

<td>Fig.</td><td>8 is an isometric view of a sealing block of</td>

<td>elastomer</td><td>and</td>

<td>FIG.</td><td>9 is a plan view taken along line 9-9 of FIG. 2.</td>

Figs. 1, 2, 3, 4, 5, 6, 7, 8 and 9 illustrate a preferred form of the sealing device 10, made in accordance with the principles of the invention. Three examples of the preferred embodiment 10 in connection with the typical rotary steam pipe dryer 11 are shown. Other embodiments of the invention are also contemplated within the scope of its applications, used in directly fired dryers, coolers and all types of rotary equipment used in the grain treatment and chemical industries to remove moisture by evaporation or alternatively to remove heat by convection. wire and radiation. Furthermore, it is believed that embodiments of this invention may be adapted to rotating equipment used in other industries, e.g. for sewage treatment and cement manufacturing. These alternative industries likewise have a continuing need for rotating equipment, and such equipment could be readily modified to include the preferred embodiment of the sealing device described and claimed herein.

Fig. 1 shows a rotary steam pipe dryer 11 with an intake housing 12 which is carried in a stationary position by an intake housing buckle 14. A rotatable cylindrical part or jacket 16 is inserted between the intake housing 12 and a drain housing 30 which is carried stationary by a drain housing buck 32.

The jacket 16 is rotatably supported by two pairs of rollers 20, each in turn stationary mounted on bearing brackets 18. The roller pairs 20 are rotatably connected to their respective running rings 22 attached to each end of the jacket 16. The jacket is driven by a motor 24 which with a drive 26 is connected to a ring gear 28 attached to the outside of the jacket 16.

The equipment is used by continuously rotating the jacket 16 by means of the motor 24 and by feeding steam pipes (not shown) located inside the jacket 16. After the equipment has reached the correct operating temperature, the desired product is brought to continuously enter the intake housing 12. The product is rotated in the jacket and passes through it at a fixed speed so that a suitable drying time is obtained.

The dried product then exits the jacket 16 through openings (not shown) therein, covered by the stationary drain housing 30. The product is then conveniently collected from the drain housing 30 for further treatment.

As moisture is removed from the product by evaporation due to contact with the hot steam pipes and other hot surfaces, the volume of gases inside the jacket 16 increases and causes a pressure gradient relative to the atmosphere outside. Gravity as well as the pressure gradient from the inside to the outside of the casing would cause loss of goods at the transition between the rotating casing 16 and the stationary drain housing 30 if this peripheral transition was not properly sealed. The seal provided at the drain housing 30 needs two separate sealing devices 10, one at a distance from and one just at the outlet end of the jacket.

In addition, a sealing device 10 is needed between the intake housing 12 and the intake end of the jacket 16. This sealing device acts to prevent loss and spillage of the product through the gap between the intake housing 12 and the intake end of the jacket 16. This loss is caused by gravity and pressure gradients which may develop at the jacket inlet. .

Fig. 2 illustrates an example of the preferred embodiment of the sealing device 10, made in accordance with the principles of the invention. The sealing device shown is the one located near the drain end of the jacket 16. However, the sealing device 10 of the drain housing 30 at a distance from the outlet end of the jacket 16 has the same design as the one shown. Furthermore, the sealing device 10 located at the intake end of the jacket 16 is also similar to the one in fig. 2 with respect to the execution.

A plurality of arcuate segments 40 are arranged peripherally around the outer circumference of the jacket 16 by attachment to a sealing mounting ring 34. This mounting ring 34 is preferably welded to the associated drain or intake house 30 resp. 12. Alternatively, the mounting ring 34 may be bolted or otherwise removably attached to the associated housing to allow proper installation and periodic adjustment if necessary. The ring 34 and the housings 30 and 12 are preferably made of ferrous materials to facilitate normal arc welding and the like.

The segments 40 are made of non-ferrous material such as e.g. epoxy impregnated cloth or fiberglass. Preferably Sythane-Taylor (Philadelphia) Synthane is used. Alternatively, brass, bronze, Teflon, plastic or other bearing materials can also be used.

Each arcuate segment 40 is mounted on the mounting ring 34 with a pin 44 fixedly inserted in the mounting ring 34. This fastening is performed by welding to or threaded connection with the mounting ring. Each pin 44 passes through a long hole 42 in the respective sealing segment 40. A donut-shaped bushing 48 consisting of elastomer with a steel disc on each side is inserted between the sealing segment 40 and a nut 46. The nut 46 has threaded engagement with the pin 44 and is tightened with suitable torque so that a suitable pressure is developed in the elastomeric sleeve 48 with a component coaxial with the pin 44. This coaxial pressure provides sufficient force to maintain a radial seal between the radial sealing surface 110 on the segment 40 and the sealing mounting ring 34.

Elastomers, as used herein, include materials preferably selected from the group of styrene butadiene rubbers, natural rubbers, cis-polybutadiene rubbers, cis-polyisoprene rubbers, ethylene-propylene rubbers, butyl rubbers, polyacrylates, polysulfide rubbers, silicones, fluorophores, fluorocarbons, fluorocarbons, .

The long hole 42 in the segment 40 lies radially directly in front of the curved axial sealing surface 100 on the segment 40. The radius of the axial sealing surface 100 is chosen to be approximately the same as for the jacket 16, and the curved axial sealing surface 100 thus comprises a part of the overall axial seal at the sealing device 10. The length of the long hole 42 is selected to allow sufficient radial displacement of the segment 40 to take into account assumed or measured irregularities with respect to the circular shape of the jacket 16 and also to take into account wear on the sealing segments 40 along their axial sealing surfaces 100. FIG. . 6 illustrates by the reference letters X and Y the relative area for movement of a round or ovoid shell 16 which can be covered by corresponding radial displacement of the sealing segment 40 and the associated long hole 42.

Each segment 40 is further formed with a first and a second overlapping portion 102 and 104, respectively. Each of these portions preferably has a thickness approximately equal to half the thickness of the segment 40 near the long hole 42. The first and second overlapping portions 102, 104 are intended to overlap. second and first portions 104, 102, respectively, of adjacent segments 40. The width of each of the portions 102 and 104 is also selected to cover wear on the curved axial sealing surface 100 with consequent gradual radial displacement of the segments inwardly.

The first and second overlapping portions 102 and 104, respectively, further form first and second radial sealing surfaces 106 and 108. which touch second and first radial overlapping sealing surfaces 108 and 106, respectively, on adjacent segments 40. The overlapping sealing surfaces 106 and 108 comprise an integral part of the radial seal provided by the sealing device 10;

Along the outer edge of each segment 40, a first and a second block bearing 112 and 114, respectively, of square or rectangular cross-section are taken out in the plane of the segment 40. The location of these first and second bearings 112 and 114 is chosen to cover with the slots 103. formed by said first and second overlapping portions 102 and 104, respectively, of adjacent segments 40. In each complete sealing block bearing formed by the combination of adjacent segments 40 and associated adjacent first and second sealing block bearings 112 and 114, respectively, sits a sealing block 64 of elastomer.

This sealing block 64 is selected to have a thickness equal to or less than the thickness of the segment 40 near the long hole 42. The width of the block 64 is selected to provide a suitable seal in place of the gap 103 formed by the adjacent segments 40. The width is also selected for not to influence the radial displacement of the segments 40 over the entire area allowed due to the length of the long hole 42. This width is also chosen to cover wear along the curved axial sealing surfaces 100 of the segments 40 by allowing gradual radial displacement thereof inwards towards the longitudinal axis of the jacket 16.

J. the outside of each arcuate segment 40 there is taken out a peripheral alignment groove for a cable 52 which at each end is attached to an associated anchoring bracket 38 via an associated tension fish 56 with spring 58.

The anchoring brackets 38 are preferably made of ferrous metal and fixed near each of the upper corners of the associated inlet or drain housing 12 or 30, respectively, by arc welding or otherwise. One end of the cable 52 is connected to one of the jacks 38 via a spring 58 and a tension fish 56. The tension fish 56 has hooks at each end, one passing through an anchoring hole 39 in the respective jack 38, and one passing through a hook 59 formed. of one end of the spring 58. The other end of the spring 58 forms another hook 59 which passes through a loop at the end of the cable 52, formed by a clamp 53.

The other end of the cable 52 is anchored in a similar manner to the other anchoring bracket 38 with the addition of an eye screw 60 through which one hook 57 of the tension fish passes. The eye screw 60 has a threaded portion which passes through an anchoring hole 39 in the jack 38. On each side of the jack is a nut 62 for removably attaching the eye screw to the jack 38. This device makes it possible to adjust the distance between the eye in the eye screw 60 and the jack. This adjustment ensures that the cable 52 does not touch itself at the point where it intersects.

A feature of the preferred embodiment is that the cable 52 surrounds the entire sealing device almost completely without rubbing against itself at the crossing point. The cable 52 is threaded through a cylindrical sleeve 66 extending through each sealing block 64. The tension provided by the spring 58 and the cable 52 provides along the circumference of the sealing device 10 a radial component which is transmitted to the sealing device through the sealing block 64. The tension in the cable provided by the springs 58 is adjusted by appropriate adjustment of the tension fish 56.

The said cable tensioning has a dual purpose. Firstly, it serves to ensure that each segment 40 has a suitable radial force load to have a properly correct abutment against the axial sealing surface of the casing 16. Secondly, this radial force ensures that each gap 103 is properly sealed by its associated sealing block 64. to make a complete axial seal perfect.

Furthermore, means for tightening the cable 52 could alternatively comprise weights connected to the ends of the cable via pulleys. In addition, the number of segments that can be used may vary depending on the outer dimensions of the jacket. For example, further mantles would require a larger number of segments than narrower ones. Where small deviations in the circular shape of the jacket 16 can be expected, fewer arcuate segments with a correspondingly larger cord length can be used, since the expected displacement of the segments is reduced.

Finally, the axial and radial sealing surfaces can be lubricated when extra sealing ability is required. Such use of lubricant further increases the ability of the seal to withstand pressure gradients and also lubricates the axial and radial surfaces which are subject to wear.