US3280894A

US3280894A - Rotary regenerative heat exchanger

Info

Publication number: US3280894A
Application number: US439504A
Authority: US
Inventors: Frank W Hochmuth
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1965-02-23
Filing date: 1965-02-23
Publication date: 1966-10-25
Anticipated expiration: 1983-10-25

Description

Oct. 25, 1966 F. w. HOCHMUTH ROTARY REGENERATIVE HEAT EXCHANGER 5 Sheets-Sheet 1 Filed Feb. 23, 1965 Oct. 25, 1966 F. W. HOCHMUTH ROTARY REGENERATIVE HEAT EXCHANGER 5 Sheets-Sheet 2 Filed Feb. 23, 1965 AGE/V7 Oct. 25, 1966 F. w. HOCHMUTH 3,230,394

ROTARY REGENERATIVE HEAT EXCHANGER Filed Feb. 23, 1965 5 Sheets-Sheet 5 United States Patent 3,280,894 ROTARY REGENERATIVE HEAT EXCHANGER Frank W. Hochmuth, West Simsbury, Conn., assignor to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Feb. 23, 1965, Ser. No. 439,504 13 Claims. (Cl. 165-6) This is a continuation-in-part application of application Serial No. 204,092 filed June 21, 1962, now abandoned.

The present invention relates to regenerative heat exchange apparatus of the type used to utilize the heat in waste gases by transmitting the heat to air or other gaseous fluid to be heated. More particularly the invention relates to a unique form of heat absorbing surface having special application in regenerative heat exchange apparatus of the rotary type.

A conventional rotary regenerative heat exchanger includes a rotor on a vertical or horizontal axis that carries heat absorbent elements in the form of metallic plates that are first positioned in a gas passage to absorb heat from hot exhaust gases passing therethrough and upon turning the rotor about its axis, the hot metallic plates are disposed in an air or heated gas passage where they give up their heat to the surrounding air or other gas that is to be heated. Such heat absorbing elements require periodic cleaning to remove fly-ash and other impurities that become deposited thereon by the gases passing therethrough, and for this purpose, it is customary to use cleaning nozzles that project streams of compressed air or steam on to the elements. In certain applications involving gases having an unusually heavy dust loading, or where the nature of impurities deposited on the heat absorbing surface causes them to cling tenaciously thereto, it becames impossible to clean the surfaces satisfactorily in the usual manner, and installation of such heat exchangers cannot be considered practical. In other cases where conditions are slightly less severe the energy expended to clean conventional heat absorbent surfaces becomes so great that thermal gain from the heat exchanger is substantially negated.

The principle object of this invention therefore is to provide a self-cleaning heat absorbing surface for a rotary regenerative heat exchanger that is adapted for use in installations where conditions of element fouling substantially preclude the use of regenerative heat exchange apparatus having heat absorbing elements of the usual type.

Other ancillary objects of my invention will become more apparent to those skilled in the art as the description proceeds.

With this object in view, the manner in which it is best carried out will be best understood upon consideration of the following detailed description when read in conjunction with the accompanying drawings in which:

FIGURE 1 is a side view of a rotary regenerative heat exchange apparatus mounted upon a horizontal axis in accordance with the invention.

FIGURE 2 is a sectional elevation of the apparatus as seen from line 2-2 of FIGURE 1.

FIGURE 3 is a perspective view of a sectorial compartment of the rotor including a chain type heat absorbent element.

FIGURE 4 illustrates a proposed chain element arrangement as viewed from line 4-4 of FIGURE 3.

FIGURE 5 illustrates an axially spaced layer of chain elements as seen from line 5-5 of FIGURE 3.

FIGURE 6 illustrates a preferred arrangement for securing strands of chain element to the compartment Walls.

FIGURES 7 and 8 illustrate a modified arrangement for varying the chain density at axially spaced planes of the compartment, while 3,280,894 Patented Oct. 25, 1966 FIGURE 9 illustrates an arrangement for bonding a continuous length of chain in zig-zag fashion to the compartment walls.

FIGURE 10 illustrates an arrangement of chain elements including a single slack chain.

Referring now to the drawings, the rotary regenerative heat exchanger disclosed therein includes a rotor that comprises a rotor shell 10 joined to a rotor post 16 by radial partitions 14 to form a series of sectorial compartments 12 therebetween. The rotor compartments are each adapted to carry a perforate mass of elongate, flexible heat absorbent element that permits fluid flow therethrough. The rotor post 16 must necessarily be inclined from the vertical position to obtain proper agitation of said elements, but it may lie in any other of an infinite number of positions that range to a full horizontal. It will be appreciated however that maximum element agitation and effectiveness of the element cleaning operation defined herein will occur when the rotor post is mounted in a full horizontal position and the heat absorbent element is subected to maximum lateral displacement during rotation of the rotor. The rotor is surrounded by a fixed housing 20 which is provided with a pair of axially spaced

ducts

26 and 28 that direct a heating fluid through the intervening compartments of the rotor. A similar pair of axially spaced

ducts

32 and 34 simultaneously direct a fluid to be heated through spaced compartments of the rotor. By means of suitable driving means 18 the rotor is intermittently or continuously rotated about its axis in order that the mass of heat absorbent elements carried in the individual compartments of the rotor may alternately traverse the heating fluid and the fluid to be heated. While thus traversing the stream of heating fluid, the heat absorbent element absorbs heat therefrom and in turn gives it up to the fluid to be heated during its passage therethrough.

In accordance with the present invention the heat absorbent element comprises essentially a series of closely spaced flexible cables, chains, or chain-like elements 24 that are disposed across the several compartments in a plurality of successive planes that lie between the inlet and the outlet ducts to the heat exchanger. These elements 24 may be attached to the side walls of the compartments or they may be attached to the side walls of frame-like subdivisions commonly termed baskets that are adapted to fit into the several compartments of the rotor.

The elements 24 are secured to the side walls of the compartments or baskets with a degree of looseness that permits each strand thereof to assume a sag that will approximate a catenary curve. The ends of the elements are preferably connected to end supports on the side walls of the compartments so that the elements extend in other than an axial direction whereby rotation of the rotor about its axis will vary the curvature of each element strand with respect to a fixed line drawn between end supports thereof. As the curvature of each element strand 24 is varied, deposits will be continuously removed from the contracting portions of adjacent links and the element 24 will be maintained completely flexible.

By arranging successive planes of chains or other elements 24 in an angularly displaced relationship in the manner shown by FIGURES 3, 4 and 5, or even at right angles to one another and with varying degrees of sag, it is possible that the elements 24 of one plane may be arranged to interfere with elements of an adjoining plane or planes so as to produce an abrading action therebetween that results in the release of deposits from the elements.

In most heat exchanger applications the heaviest deposits of dust occur on the heat absorbent surfaces which are first touched by the dirty gas entering the heat exchanger. This adverse situation may be accommodated by adjusting the spacing and the sag of the chains that lie in axially spaced planes between inlet and outlet ducts of the heat exchanger so that the cleaning action may be amplified in those areas of heaviest deposits. Thus as shown in FIGURE 7, the radial spacing and catenary sag of the chains in an area of maximum dust loading may be exaggerated as compared to an axially spaced zone shown in FIGURE 8.

In a similar manner it is possible to arrange the rotor compartments to be packed with flexible element having a sag that affords an amplified cleaning action during a predetermined portion of their rotative cycle whereby a majority of the deposited particles may be dislodged se lectively in either the heating fluid or the fluid to be heated and then removed from the rotor. For example, in an application considered in connection with a chemical recovery unit it would be desirable to have the deposits released in a heated air stream so they could be later recovered in a subsequent step of the process.

Although the precise arrangement by which the chaintype elements are secured to the compartment walls is not critical, a very satisfactory arrangement is shown in FIGURE 6 where a series of apertured studs 36 are connected to the compartment walls and adapted to receive a linking bar 38 that is directed through a link of the chain. Spacers 42 inserted between chains can provide any predetermined spacing therebetween. Thus by increasing the thickness of the spacers the distance between chains may be increased, while by reducing the thickness of spacers 42 or by even eliminating them completely, adjacent chains may be spaced further or even placed in abutment to produce a mutual interference.

A further modified form of the invention includes the use of a continuous length of chain bonded in zig-zag fashion between spaced walls of a compartment in the manner illustrated by FIGURE 9. Here intermediate loops of the chain are anchored to the spaced walls by welding directly thereto, or they may be linked by means of an arrangement similar to that illustrated in FIGURE 6. This zig-zag pattern may be used exclusively in the several planes of the rotor, or it may be used in combination with other chain arrangements to attain any predetermined chain density or relationship.

When a number of strands of flexible element 30 lying in substantially the same plane normal to the axis of a horizontally disposed rotor are made sufificiently long that they hang down and overlap conventianal elements 24 lying directly adjacent thereto, rotation of the rotor will induce a degree of interference between overlapping elements that abrades any but the most tenacious of deposits therefrom. Moreover, one or more slack chain type elements 33 positioned in or adjacent to a layer of element where maximum fouling conditions occur may be arranged in the manner shown in FIGURE 10 to provide a still greater degree of mutual interference between spaced elements, and accordingly, additional cleaning action may be imparted to those elements which are subjected to maximum fouling conditions.

A single slack chain-like element 33 may be arranged to depend from a particular end of the sectorial compartment in the manner shown in FIGURE 10, or several such slack chain-like elements 33 may be disposed on spaced sides of each compartment to provide an even greater element agitation as the rotor is turned about its axis.

The single slack chain 33 may moreover be arranged to depend from any one of the several compartment walls in order that maximum movement of the slack chain may be induced during a predetermined portion of the cycle of rotation through which the rotor is turned. Thus duct means directing the gas or air away from the rotor may be positioned adjacent zones of maximum chain movement to permit gas or air exhausting from the rotor to carry with it the particulate matter being released from the chains during periods of maximum agitation.

While this invention has been described with reference to the embodiment illustrated in the drawing, it is evident that various changes may be made in the physical characteristics of the heat absorbent element or in its specific arrangement without departing from the spirit of the invention, and it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. Rotary regenerative heat exchange apparatus having a rotor including a cylindrical rotor shell and a central rotor post mounted for rotation about an axis displaced from vertical, radial partitions extending from the rotor post to the rotor shell forming lateral walls for a series of sectorial compartments therebetween, a housing surrounding the rotor provided at opposite ends with plate members having imperforate portions between spaced apertures that comprise inlet and outlet ports for a heating fiuid and a fluid to be heated, means for rotating the rotor about its axis, a quantity of heat absorbent material carried by each compartment of the rotor, said heat absorbent material comprising a multiplicity of flexible elements suspended loosely between spaced walls of each compartment whereby said elements are free to assume a sag having a line of curvature that varies as the rotor is rotated about its axis so as to effect self-cleaning of the elements.

2. Rotary regenerative heat exchange apparatus having a rotor with a horizontal axis of rotation including a cylindrical rotor shell and a central rotor post, radial partitions extending from the rotor post to the rotor shell forming lateral walls for a series of sectorial compartments therebetween, a housing surrounding the rotor including apertured end plates that direct a heating fluid and a fluid to be heated through the rotor, means for rotating the rotor about its axis, a quantity of heat absorbent material carried in each compartment of the rotor, said heat absorbent material comprising a multiplicity of elongate flexible elements loosely supported by walls of said compartments whereby said elements are free to assume a sag on alternate sides of a fixed line drawn between ends of said elements as the rotor is rotated about its axis.

3. Rotary regenerative heat exchange apparatus having a rotor with an axis of rotation displaced from vertical including a cylinder rotor shell and a central rotor post, radial partitions extending from the rotor post to the rotor shell forming lateral walls for a series of sectorial compartments therebetween, a housing surrounding the rotor provided at opposite ends with end plates having imperforate portions between spaced apertures that comprise inlet and outlet ports for a heating fluid and a fluid to be heated, means for rotating the rotor about its axis, and a quantity of heat absorbent material carried in each compartment of the rotor, said heat absorbent material comprising a multiplicity of flexible chain-like elements loosely suspended between spaced walls of said compartments whereby links of said elements are moved relative to adjoining links as the rotor is rotated about its axis.

4. Rotary regenerative heat exchange apparatus having a rotor including a cylindrical rotor shell joined to a central rotor post by radial partitions to form a series of sectorial compartments therebetween, a housing surrounding the rotor provided at composite ends with end plates having imperforate portions between spaced apertures that direct a heating fluid and a fluid to be heated through spaced compartments of the rotor, means for rotating the rotor about its axis, a quantity of heat transfer material carried in each compartment of the rotor, said heat transfer material comprising a series of axially spaced element layers each having a multiplicity of chain-like elements suspended between sides of said compartments, said chainlike elements of each layer being disposed similarly and angularly displaced from the elements of other layers adjacent thereto.

5. Rotary regenerative heat exchange apparatus having a rotor including a cylindrical rotor shell joined to a central rotor post by radial partitions to form a series of sectorial compartments therebetween, a housing surrounding the rotor provided at opposite ends with end plates having imperforate portions between spaced apertures that direct a heating fluid and a fluid to be heated through the spaced compartments of the rotor, means for rotating the rotor about its axis, and a quantity of heat absorbent material carried in each compartment of the rotor comprising layers of chain-like elements loosely suspended between sides of said compartments, said layers of elements being arranged to extend alternately between circumferentially and radialiy spaced sides of said compartments.

6. Rotary regenerative heat exchange apparatus having a rotor including a cylindrical rotor shell joined to a central rotor post by radial partitions to form a series of sectorial compartments therebetween, a housing surrounding the rotor provided at opposite ends with end plates having impe-rforate portions between spaced apertures that direct a heating fluid and a fluid to be heated simultaneously through spaced compartments of the rotor, means for rotating the rotor about its axis, and a quantity of heat absorbent material mounted in the compartments of the rotor comprising a multiplicity of chain-like elements suspended between walls of said compartments, said elements having varying amplitudes of sag that induce interference between elements when the rotor is rotated about its axis.

7. Rotary regenerative heat exchange apparatus having a rotor including a cylindrical rotor shell joined to a rotor post by radial partitions to provide a series of sectorial compartments therebetween, means for rotating the rotor about its axis, a mass of heat absorbent material carried in the compartments of the rotor comprising a plurality of axially spaced layers of elongate chain-like elements suspended between spaced walls of said compartments, the chain elements of each layer comprising a continuous length of chain lying in zig-zag manner and having spaced links thereof secured to spaced compartment walls.

8. Rotary regenerative heat exchange apparatus having a rotor including a cylindrical rotor shell joined to a rotor post by radial partitions to form a series of sectorial compartments therebetween, a housing surrounding the rotor provided at opposite ends with end plates having imperforate portions between spaced apertures that direct fluid and a fluid to be heated simultaneously through spaced compartments of the rotor, means for rotating the rotor about its axis, and a quantity of heat absorbent material carried in each compartment of the rotor comprising a multiplicity of flexible cables suspended loosely between spaced walls of said compartments.

9. Rotary regenerative heat exchange apparatus as defined in claim 8 wherein the loosely suspended cables are provided with various degrees of sag to induce interference between predetermined cables.

10. Rotary regenerative heat exchange apparatus having a rotor including a cylindrical rotor shell and a central rotor post mounted for rotation about an axis displaced from vertical, radial partitions extending from the rotor post to the rotor shell to form walls for a series of sectorial compartments therebetween, a housing surrounding the rotor provided at opposite ends with end plates having imperforate portions between spaced apertures that comprise inlet and outlet ports for a heating fluid and a fluid to be heated, means for rotating the rotor about its axis, and a quantity of heat absorbing material carried in each compartment of the rotor comprising a multiplicity of elongate flexible elements suspended loosely between walls of said compartments, each of said compartments having at least one slack element with a degree of sag that permits it to intermittently overlap a majority of the elements in said compartment lying in substantially the same vertical plane when the rotor is rotated about its axis.

11. Rotary regenerative apparatus as defined in claim 10 wherein the flexible heat absorbent elements are comprised of linked chains.

12. Rotary regenerative apparatus as defined in claim 10 wherein the heat absorbent elements of each compartment comprise flexible cables.

13. Rotary regenerative heat exchange apparatus as defined in claim 10 wherein the slack element is secured at its ends to radially outer walls of said compartment.

References Cited by the Examiner UNITED STATES PATENTS 2,001,258 5/1935 Lindhard 263-33 2,183,936 12/1939 Karlsson et al 5 2,230,601 2/1941 Puerner et al. 26332 FOREIGN PATENTS 1,259,464 3/ 1961 France.

561,599 10/1932 Germany. 29,587 3/ 1919 Norway.

ROBERT A. OLEARY, Primary Examiner.

T. W. STREULE, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 ,280 ,894 October 25, 1966 Frank W. Hochmuth It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 58, for "contracting" read contacting column 3, line 47, for "conventianal" read conventional column 4, line 47, for "cylinder" read cylindrical line 66, for "composite" read opposite column 5, lines 15 and 16, for "radialiy" read radially Signed and sealed this 5th day of September 1967.

( AL) Attest:

ERNEST W. SWIDER Arresting Officer EDWARD J. BRENNER Commissioner of Patents

Claims

1. ROTARY REGENERATIVE HEAT EXCHANGE APPARATUS HAVING A ROTOR INCLUDING A CYLINDRICAL ROTOR SHELL AND A CENTRAL ROTOR POST MOUNTED FOR ROTATION ABOUT AN AXIS DISPLACED FROM VERTICAL, RADIAL PARTITIONS EXTENDING FROM THE ROTOR POST TO THE ROTOR SHELL FORMING LATERAL WALLS FOR A SERIES OF SECTORIAL COMPARTMENTS THEREBETWEEN, A HOUSING SURROUNDING THE ROTOR PROVIDED AT OPPOSITE ENDS WITH PLATE MEMBERS HAVING IMPERFORATE PORTIONS BETWEEN SPACED APERTURES THAT COMPRISES INLET AND OUTLET PORTS FOR A HEATING FLUID AND A FLUID TO BE HEATED, MEANS FOR ROTATING THE ROTOR ABOUT ITS AXIS, A QUANTITY OF HEAT ABSORBENT MATERIAL CARRIED BY EACH COMPARTMENT OF THE ROTOR, SAID HEAT ABSORBENT MATERIAL COMPRISING A MULTIPLICITY OF FLEXIBLE ELEMENTS SUSPENDED LOOSELY BETWEEN SPACED WALLS OF EACH COMPARTMENT WHEREBY SAID ELEMENTS ARE FREE TO ASSUME A SAG HAVING A LINE OF CURVATURE THAT VARIES AS THE ROTOR IS ROTATED ABOUT ITS AXIS SO AS TO EFFECT SELF-CLEANING OF THE ELEMENTS.