US2715517A - Rotary, tubular heat exchanger - Google Patents

Description

Aug. 16, 1955 G. BOJNER ROTARY, TUBULAR HEAT EXCHANGER Filed March 27, 1951 fl ifibys 3 Vi a 2 /4z: I 3a United States Patent Ofilice 2,715,517 Patented Aug. 16, 1955 ROTARY, TUBULAR HEAT EXCHANGER Gustav Bcjner, Steckhcim, Sweden Application March 27, 1951, Serial No. 217,741

5 Claims. (Cl. 257241) This invention relates to an apparatus for transferring heat indirectly from one medium to another, for instance heating air or other gases, or drying or heating granular, pulverulent or similar goods by using gases of combustion as a heating medium, or cooling any pulverulent goods by using air or other medium for absorbing heat. In particular; this invention relates to apparatus of the aforementioned type comprising a stationary system and a rotary system employing heat transfer that occurs through metallic walls constituting parts of each system.

The object of this invention is to provide an improved apparatus of the aforesaid type by increasing the eifective heat transfer area of the rotary system and reducing the number of sealing points that are required between the two systems to only a single seal at each end of the apparatus and furthermore to provide a rigid metallic wall extending uninterruptedly from one point of scaling to the other and constituting a boundary between the two systems.

A related object of this invention is to provide an improved apparatus having substantially increased total eflective metallic area of heat transfer or exchange.

A further object is to provide a simple and economically constructed heat exchange apparatus for drying or cooling.

A feature of this invention consists in the provision of a rotary tube structure comprising a shell and annular tube plates at the opposite ends of the shell together with longitudinally extending tubes mounted within the shell. Central collars are attached to each annular tube plate and this rotary structure is disposed within a stationary casing and spaced therefrom at the circumferential side wall and at each end wall with this spacing constituting a free annular space around the shell and annular end chambers around the collars in communication with stationary eccentrically disposed inlet and outlet openings in the stationary casing through which passes a gaseous medium through the tubes and around the shell thereby including said shell into the effective heat transferring area. Said collars extend through central openings in the stationary end walls and have a gas sealed rotary feed therein. One collar constitutes an inlet for a flowable material and the opposite collar constitutes an outlet for the flowable material that passes through the interior of the rotary structure and around the tubes embodied therewith.

The apparatus chiefly comprising a rotatable structure, consisting of tubes, the ends of which are fastened in circular tube plates, fixed to a cylindrical shell, the latter enclosing the set of tubes. In one embodiment this structure is rotatably journalled in a stationary container, provided with end-walls, the container axially enclosing the structure and its tube plates in such a way that there will be two chambers in each end of the apparatus between the container and the two tube plates. The end chambers being provided with an inlet and outlet, respectively for the medium, which is to pass through the tubes from one chamber to the other. Additionally, the tube plates of the rotatable structure are each provided with a collar or a channel extending through the respective end chambers and which collars respectively constitute an inlet and an outlet for the medium, solid, fluid or gaseous, which is to pass through the interior space of the structure, that is, externally of the tubes. This space is accordingly designed to receive the medium, which may be a divided or powdered solid material to be dried or cooled, or a gaseous medium for air heating.

The invention also refers to other arrangements of this apparatus which increase the value and eificiency of the same. Some embodiments of the invention are by way 'of examples illustrated in the accompanying drawings,

in which:

Fig. l is a longitudinal central section of one embodiment, meant for heat-exchange between gases and Fig. 2 is a cross-section on the line 11-11 in Fig. 1.

Fig. 3 illustrates a longitudinal central section of another embodiment, designed for drying crushed or powdered material by means of combustion gases, or cooling such material by means of a suitable medium. Fig. 4 is a cross-section on the line IV-IV in Fig. 3.

In these embodiments, the rotatable structure chiefly consists of tubes or pipes 1, circular tube plates 2 and a cylindrical shell 3. The ends of the tubes are mounted in the tube plates and the shell 3 is enclosing the whole set of tubes. The tube plates are provided with collars 4. in the embodiments according to Figs. 1 and 3 the rotatable structure is journalled on its collars at 11 and driven by means of a transmission including sprocket 12a, chain 121: and sprocket 120. The sprocket 12a is mounted on the right collar 4 in Fig. l and on the left collar 4 in Fig. 3.

In Figs. 1 and 2 the collars are constituted by the opposite end portions of a tube in passing through the apparatus. This tube is provided with openings or slits 5 for the passage of the medium, in this case gas, that passes externally of the tubes. In order to direct the passage of gas against the tubes and to reduce the gas-resistance, there are conical bodies 6 placed with their apices directed respectively toward the inlet and outlet ends of the tube 4a so that the gas flowing from the inlet through the tube 4a has its direction changed so that it passes out through the slits 5 and then flows back in through the slits 5 adjacent the outlet end of the tube 4a. The direction of gas flow is illustrated in Figure l by the arrows. course a suitable fan, not shown, is utilized to pump the gas through the rotary structure constituted by the shell, the tube plates, the spaced tubes connected therebctween and the tube 4a.

In the embodiments illustrated in Figs. 1-4 the rotatable structure is enclosed by a stationary container, that consists of a mantle 7 and gable-ends 8. In these gables there are openings for the collars 4 and the container is provided with conduit parts 9 and 10 for the respective inlet and outlet of the gas, that passes through the tubes 1 in the direction shown by the arrows. The mantle 7, which does not take part in the rotation, extends axially outside the tube-plates 2 of the rotatable structure and constitutes beween its gables 8 and the tube plates 2 two header chambers 14a and 14b, distributing the passing gas to the tubes and in communication with each other through the tubes.

Between the mantle 7 of the container and the shell of the rotatable structure 3 there is a small annular space 3a through which the gas may pass in order to make the shell 3 an effective heating or cooling surface. For constructive reasons the mantle of the container ought to be divided horizontally suitably at 17, as shown in Figs. 2 and 4.

The inlet and outlet for the material being treated are passing through the rotatable structure.

respectively arranged centrally of the tube plates 2 and extend through the collars 4, around which a packing of I known construction is easy to arrange.

down the spout, through the rotatable structure and out through the left collar 4.

As for the embodiment in Figs. 3 and 4, there are no fundamental differences from the embodiment in Figs.

1 and 2, although it is not provided with the tube 4a In lieu thereof, shovels 16 facilitate thedischarge of the material from the apparatus through the collar 4 during the rotation of the rotary system or structure. I

When the'apparatus is used as a dryer, by using for instance gases of combustion, said gases are led into the stationary container through the conduit elements 9. Because of the rotation, the temperature in each'part of the cross-section of the rotatable structure will be equalized and dangerous tensions avoided. The contact between the material and the heat transmitting surface will be most effective during the rotation.

. In order to effect a rapid drying it may be necessary to lead ventilating-gas through the drying room to take away the moisture evaporated. This gas may very well be supplied through one of the collars 4 and led off through the other.

It is clear therefore that the present invention provides a rotary heat exchanger for subjecting flowable material, by which term is included gases, powders, grain and the like, to the action of a gaseous medium in counter-flow in direct heat exchange relationship therewith. By the provision of the rotary structure Within a stationary casing and spaced from the walls of the casing, the outer surface of the shell 3 constitutes a heat exchange surface since the gas or steam that flows through inlet 9 not only passes through the tubes 1 but through the space between the shell and the casing wall 7. The provision of the collars extending at least from the ends of the shell provide the support for the rotary shell and one of them also constitutes one of the components of the drive mechanism.

In the arrangement shown in Figure 1 the unique relationship of the baflies 6 directs the gas flowing through the tube 4a radially outward of the tube through the openings 5 so that it efiectively contacts the tubes 1 within the shell 'to facilitate the heat exchange relationship. In

thismodification it is a further important feature that with the tube 4:: passing entirely through the rotary shell adequate support is provided for the rotary structure and exceptionally heavy structures, including casings and tube arrangements, can be suitably supported and rotated by this central tubular support.

The embodiments described are only some examples of performances of the invention and various changes and substitution of mechanical equivalents may be made without departing from the invention as defined in the ap pended claims, Thus the'tube-plates 2 and the gable plates. may be joined with each other at the circumference as well as at the center by being bent in such a way that two ringformed chambers are achieved, communieating through the tubes. The apparatus may be mounted with or without elevation. Further, it may be important to make the driving of the apparatus reversible if the material to be treated would'have any tendency to adhere spaced end walls, a rotary structure within the casing including a cylindrical substantially horizontally disposed thereof within the shell, bathe means within the tube ineluding oppositely disposed cone-shaped elements having the 'apices directed respectively toward the opposite ends of said tube so that material that enters one end of the tube is deflected by one apex of the cone-shaped elements to flow outwardly through the slits in said centrally disposed tube into heat exchange relationship with the tubes disposed betwen the end plates and the material being directed toward the outlet end of the tube by the other;

and oppositely disposed apex after it has re-entered the centrally disposed tube through the slits, said casing having greater axial extent than the shell so that the end walls of the casing in combination with the tube plates define end chambers, fluid inlet-and'outlet means communicated with each end chamber with the fluid inlet means being at the end opposite the collar means constituting the inletv for material, means journalling the collars at areasexteriorly of the casing for reversible rotation, and drive means for rotating the collars and thereby the shell in:

eluding a driven element carried by one of the collars.

2. A rotary heat exchanger for passing a fiowable within the stationary casing including a cylindrical substantially horizontally disposed shell, tube plates at theends of the shell and a plurality of tubes secured to the tube plates and extending longitudinally within the shell,'

centrally disposed collar means attached to each annular tube plate extending beyond the adjacent end wall of.

the casing and providing communication with the interior of the shell, said rotary structure being spaced from'the stationary casing at the side wall and at each end wall thereof, said longitudinally extending tubes communicating with the spaces beyond the tube plates, the rotary structure defining in combination with'the stationary casing an annular chamber around the shell and annular end chambers around the collar means in communication with said inlet and outlet for passing said gaseous medium through the tubes and around the shell, said collar means extending through the central openings of the end walls of the stationary casing and having a gas-sealed rotary fit therein, one collar means constituting an inlet for flowable material and the opposite collar means consti: tuting an outlet for said flowable material for passing the same through the interior of the rotary structure around the longitudinally extending tubes thereof, means journalling said rotary structure exteriorly of the stationary casing at the collar means, and drive means applied to at least one collar means for rotating said structure.

3. A rotary heat exchanger for passing a first gaseous medium in indirect heat-exchange relationship with a second gaseous medium comprising, in combination, a' stationary casing including a circumferential side wall' and spaced annular end walls each having a central open ing, an inlet for said first gaseous medium at oneend of the stationary casing and an outlet for said 'first gaseous medium at the opposite end of the stationary casing, a rotary structure within the stationary casing including a cylindrical substantially horizontally disposed shell, tube plates at the ends of the shell and a plurality of tubes secured to the tube plates and extending longitudinally through the shell, each tube plate having a central opening therein, a centrally disposed tube extending through the shell and attached to each tube plate at the edge of the central opening therein, said centrally disposed tube further including portions extending beyond each tube plate and constituting collars thereon, apertures being provided in the central tube in the portion thereof within the shell, said rotary structure being spaced from the stationary casing at the side wall and at each end wall thereof, thereby defining in combination with the stationary casing an annular chamber around the shell and annular end chambers around the collars in communication with said inlet and outlet for passing said first gaseous medium through the longitudinally extending tubes and around the shell, said collars extending through and beyond the central openings of the end walls of the stationary casing and having a gas-sealed rotary fit therein, one collar constituting an inlet for said second gaseous medium and the opposite collar constituting an outlet for said second gaseous medium, baffle means within the central tube in the portion thereof that is within the shell, said baffle means including oppositely disposed coneshaped elements having the apices directed respectively toward the opposite ends of said tube for directing said second gaseous medium in a path through said apertures and around the longitudinally extending tubes, means journalling said rotary structure exteriorly of the stationary casing at the collars, and drive means applied to at least one collar for rotating said structure.

4. A rotary heat exchanger for passing one flowable substance such as a flowable solid material in indirect heat exchange relationship with another flowable sub stance such as a gaseous medium comprising a stationary casing including a substantially horizontal drum and opposite end walls, a rotary structure within the casing including a shell of circular cross-section mounted within the casing substantially concentrically thereof and spaced from the drum, a tube plate at each end of the shell spaced axially from the adjacent end wall of the casing, a central tube like collar means projecting from the tube plates, extending through each end wall of the casing and being in communication with the interior of the rotary structure and furthermore constituting the center of rotation thereof and also inlet and outlet means for the first mentioned flowable substance, a plurality of spaced, horizontally disposed tubes connected to and extending from one tube plate to the other and communicating with the r spaces beyond the tube plates, the spaces beyond the tube plates constituting a stationary distributing header at one end of the rotary structure and a stationary collecting header at the other end of the rotary structure, the walls of each header being constituted by a portion of the drum adjacent each end wall, the end wall, the adjacent tube plate and the respectively collar means, said headers being in communication with each other through the tubes as well as through the space between the drum and the shell for passing the second flowable substance therethrough, the distributing header having an inlet and the collecting header having an outlet for the second flowable substance, said inlet and outlet being located in the stationary casing.

5. A rotary heat exchanger for passing one flowable substance such as a flowable solid material in indirect heat exchange relationship with another flowable substance such as a gaseous medium comprising a stationary casing including a substantially horizontal drum and opposite end walls, a rotary structure, within the casing including a shell of circular section mounted within the drum, substantially concentrically thereof and spaced from the drum, a tube plate at each end of the shell spaced axially from the adjacent end wall of the casing, a central tube extending through the rotary structure beyond the end walls of the casing and constituting a passage for one of the flowable substances, and including a portion between the end walls having longitudinally extending slits therein in the portion thereof within the shell, a plurality of eccentrically disposed tubes connected to and extending from one tube plate to the other, a stationary distributing header at one end of the rotary structure and a stationary collecting header at the other end of the rotary structure, the walls of each header being constituted by the drum, the adjacent end wall, the tube plate and the central tube, said headers being in communication with each other through the eccentrically disposed tubes as well as through the space between the drum and the shell for passing the second flowable substance therethrough, the distributing header having an eccentrically disposed inlet and the collecting header having an eccentrically disposed outlet for the second flowable substance, said inlet and outlet being located in the stationary casing.

References Cited in the file of this patent UNITED STATES PATENTS 412,539 Preston et al Oct. 8, 1889 1,038,511 Anderson Sept. 17, 1912 1,556,230 Lisk Oct. 6, 1925 1,617,815 Lissauer et a1 Feb. 15, 1927 1,671,798 Vermilye May 29, 1928 1,728,496 Lindhard Sept. 17, 1929 1,823,189 Carpenter Sept. 15, 1931 1,828,799 Carlson Oct. 27, 1931 1,928,004 Bullerjahn Sept. 26, 1937 2,311,984 Guild Feb. 23, 1943 2,362,539 Cheesman Nov. 14, 1944 FOREIGN PATENTS 15,334 Norway Nov. 24, 1905 117,085 Sweden Aug. 27, 1946 249,534 Great Britain Aug. 12, 1926 622,899 Great Britain May 9, 1949

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