US2911197A

US2911197A - Rotating heat exchanger

Info

Publication number: US2911197A
Application number: US673306A
Authority: US
Inventors: Hans O Scherenberg
Original assignee: Daimler Benz AG
Current assignee: Daimler Benz AG
Priority date: 1956-07-25
Filing date: 1957-07-22
Publication date: 1959-11-03
Anticipated expiration: 1976-11-03

Description

Nov 3,' 1959 H. o. SCHERENBERG 3 1 ROTATING HEAT EXCHANGER 2 Sheets-Sheet 1 Filed July 22, 1957 IIIIl,"I I

INVENTOR HANS O. SCHERENBERG IIIIlFI' ATTORNEYS Nov. 3, 1959 7' H. o. SCHERENBERG 2,911,197

ROTATING HEAT EXCHANGER Filed July 22, 1957 2 Sheets-Sheet 2 INVENTOR HANS O. SCHERENBERG ATTORNEYS Unite States Patent I 2,911,197 ROTATING HEAT EXCHANGER Hans O. Scherenberg, Stuttgart-Heurnaden, Germany, assignorto Daimler-Benz Aktiengesellschaft, Stuttgart- Unterturkheim, Germany The present invention relates to a rotating heat exchanger of drum-like construction for heating the combustion air of gas turbines, and more particularly 7 relates to a rotating heat exchanger of drum-like construction provided with stationary connecting studs for the supply and discharge of air and/or gas and with a rotating heat exchanger body formed of a stack of annularly-shaped lamellae or disks, and wherein a sector of the heat exchanger body is traversed by the gas as, for example, the exhaust gases of a gas turbine while the remaining sector is traversed by the air, for example, the combustion air of the turbine to be heated. Furthermore, the present invention relates to a rotating heat exchanger of drum-like construction in which spacer sheet-metal strips or the like are arranged between the annularly-shaped lamellae or disks so as to simultaneously maintain predetermined distances between the disks and wipe off any foreign particles which may have collected or been deposited at the disks.

In the known heat exchanger of the prior art, which included stacks of annularly-shaped lamellae or disks, the disks or lamellae became dirty oftentimes after a short period of operation thereof which resulted in a reduction of the exchange of heat therein so as to make necessary repeated exchange in cleaning of the stacks of disks. However, each exchange or cleaning of the disks is accompanied by an interruption of the operating or working time of the gas turbine which has a disadvantageous eifect on the overall efiiciency and economy of the particular installation.

In the copending United States patent application, Serial No. 670,082, filed July 5, 1957, and entitled Rotating HeatExchanger, a rotating heat exchanger. was described in which the exchange or transfer of heat takes place over a stack of annularly-shaped disks which during rotation absorb heat from the hot gases in a first partial sector of the annularly-shaped heat exchanger portion and which give off the heat to the combustion air in another sector of the heat exchanger portion. The individual disks or lamellae of the stack of lamellae or disks are thereby arranged at a slight distance from one another, and in order to avoid the accumulation of dirt thereon, are provided with spacer sheet-metal strips or the like arranged between two adjacent disks or lamellae which simultaneously maintain the disks at a predetermined distance and wipe off the foreign particles deposited at the disks. p

The present invention constitutes an improvement over the rotary heat exchanger of the aforementioned copending patent application and aims at an increased efficiency of the heat exchanger by improving the exchange'or transfer of heat between the annularly-shaped disks and the gases serving for purposes of heating, on the one hand, and the air to be heated, on the other, while simultaneously maintaining all the advantages obtained in the aforementioned copending patent application which is assigned to the same assignee as the present application.

Accordingly, it is an object of the present invention to provide a heat exchanger of greatly increased efiiciency which automatically prevents the collection of dirt or other foreign particles at the disks and thereby precludes any reduction of the capacity of the heat exchanger to transfer heat or exchange heat between the two fluid media by reason of collection of dirt or other foreign particles at the heat transferring lamellae or disks.

It is another object of the present invention to provide a particularly simple and effective constructionof the heat exchanger seals between the two compartments for the two gases or fluid media whereby the seals simultaneously are efiective to wipe off any dirt from the annularly-shaped lamellae or disks to thereby maintain the same clean at all times.

It is still another object of the present invention to provide a heat exchanger which has greatlyimproved efficiency while simultaneously therewith minimizing the down-time of the gas turbine due to the necessity for disassembling theheat exchanger to clean the annularlyshaped lamellae or disks thereof because of clogging up or collection of dirt thereon.

Another object of the present invention resides in the provision of annularly-shaped heat exchanger disks which, by reason of their particular configuration offer a much larger heat-exchange surface and thereby increase the efficiency of the heat exchange made possible thereby.

Still a further object of the present invention resides in the provision of spacing and cleaning elements in the form of sheet-metal strips which have the same particular configuration as the annularly-shaped disks of the heat exchanger body which themselves are shaped in a corrugated-like manner with the corrugations coaxial with the axis of rotation of the heat exchanger.

These and other objects, features and advantages of the present invention will become more obvious from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, one preferred embodiment in accordance with the present invention, and wherein:

Figure 1 is an axial cross-sectional View of a rotary,

self-cleaning heat exchanger in accordance with the present invention;

Figure 2 is a front view of the heat exchanger shown in. Figure l as seen in direction of the axis of rotation thereof with certain parts thereof broken away for the sake of clarity; and

I Figure 3 is an enlarged partial cross-sectional view taken along line 3?? of Figure 2.

The present invention essentially consists in that spacer sheet-metal strips or the like are arranged between the annularly-shaped lamellae or disks of the heat exchanger body which have the task of maintaining the lamellae or' disks at a predetermined distance and to wipe off any foreign particles deposited or collected at the disks, whereby both the lamellae or disks and the sheet metal strips are of corrugated or undulated construction with the corrugations coaxial to the axis of rotation of the heat exchanger.

In accordance with a further feature of the present invention, the spacer sheet-metal strips may be combined into combs provided with a plurality of teeth as viewed in the longitudinal cross section thereof whereby the teeth which constitute the spacers are preferably provided with side surfaces extending conically toward each other so that in the direction of rotation the width thereof decreases. As a result of such a construction, the edges formed by the interaction of the conical side walls and the widest transverse wall of each tooth or spacer strip are disposed opposite to and thereby encounter first the disk portions arriving at the sheet metal strips in the direction of rotation thereof, and therefore, wipe oif any dirt or foreign particles which may have collected thereon. It is essential in connection" therewith that not only a clogging up of the heat exchanger but also already a slight deposit of dirt at the disks is avoided which in certain cases might considerably reduce the heat transfer and therewith the efiiciency of the heat exchanger.

If the sheet-metal strips are combined at the lower end thereof into a comb-like structure, then it is possible to secure the same thereat in a particularly simple manner. Preferably, for purposes of securing a row of sheet-metal strips in the heat exchanger a place located within the annularly-shaped disks is selected. The combs formed by the sheet-metal strips may also be secured in the circumferen'tial direction thereof in an inclined manner, and more particularly in such a manner that an edge of the sheet-metal strip first intersects a radius of the annular disk at the side thereof closer to the center and only thereafter on the outer side thereof, i.e., in such a manner that the leading edge of the strip is inclined upwardly and forms an angle with the radius in the direction of rotation of the disks.

Referring now to the drawing, wherein like reference numerals are used throughout the various views to designate like parts, the reference numeral 1 designates a round housing in which the heat exchanger is accommodated. Starting with the center point of the housing 1, as viewed in Figure 2, the heat exchanger is subdivided into three concentric sections. The inlet or discharge of the air and gas takes place in the inner disk-shaped section 2. An annularly-shaped center section, constituting the heat exchange section 3, properly speaking, adjoins the center section 2 outwardly thereof, and another annularly-shaped outer section 3 radially outwardly thereof.

The inner section 2 is subdivided by the separating wall portions 5, 6, 7 and 8 essentially into two sectors which together with the other housing wall parts 9 and 10, which in turn enclose the inner section 2, form the connections for the admission or discharge of the air and gas. For example, air enters into the interior of the heat exchanger through the channel 11 in the direction of the arrow 11' (Figure 1), and traverses that portion of the heat exchanger section 3 in the direction of arrow C which lies within the annular sector 12 and which is defined by the sheet-metal strips forming the

sealing boundary walls

13 and 14 thereof in the circumferential direction. After passage through the heat exchanger part 3, and more particularly after passage through the annular sector 12 of the heat exchager part 3 properly speaking, the air arrives in the outer annular sector 15 which is in communication with the air discharge channel 16 and the air discharge connecting member 17 through which heated air is then conducted away.

In the illustrated embodiment, the gas serving for purposes of heating, derived, for example, from the exhaust of a gas turbine, traverses the heat exchanger in the counterflow principle, i.e., the gas flows in the opposite direction as the air through the stack of lamellae or disks.

Consequently, the gas serving as heating medium enters over the connecting member 18 through the channel 19 into the outer annular sector 20, flows from there in the direction of arrow B over the annular sector 21 intended for the gas which is limited by the

boundary walls

13 and 14, through the stack of disks disposed therein, and is thereupon collected in the sector space 22 formed by a part of the inner section 2 and is discharged therefrom through the funnel-shaped sector defined by Walls 5, 6 and S. It should also be noted that the concentrically disposed two inner sections 2 and 3 of the heat exchanger are arranged eccentrically to the outermost section 4 thereof so that from the end formed by the transversely extending separating wall portion 14 to the air connecting member 17 or gas connecting member 18, respectively,

i.e., approximately to the separating wall portion 13, increasingly larger annular channels are formed, i.e.,-

channels

15 and 29 of increasingly larger cross section are provided. 7 y

The exchange or transfer of heat between gas and air takes place upon rotation of the stack of disks 28 which are of undulated or corrugatedconfiguration with the rings of undulations or corrugations coaxial to the axis of rotation of the heat exchanger. The stack of individual disks or lamellae 28 is retained between rigidly or springily supported rollers 24 carried by shafts 23 of which at least one is driven from any suitable external source (not shown) such as from an electric motor or the like. In the illustrated embodiment, the roller 24 is provided with external gear teeth 25 which mesh with the external gear teeth 26 of the outer disk ring 27.

The individual undulated or corrugated disks 28 are connected with the disk ring 27, for example, by means of transversely extending spacer bars or support elements 41 disposed at an acute angle to the axis of rotation of the disks. The spacer bars 41 are provided with appropriate grooves to accommodate therein the individual disks 28. The spacer bars or support elements 41 are suitably supported and secured on one side thereof in the disk ring 27. The other side of the spacer bars 41 may also be suitably supported and secured in any appropriate manner, for example, in a ring similar to ring 27 which is disposed on the opposite side of the heat exchanger.

If the disk ring 27 together with the individual disks 28 are set into rotation in the direction of arrow A by rotating roll 24 then the individual disks 28 continuously receive or absorb heat from the gases flowing therethrough within the sector 21 defined by the boundary Wall 13 to the boundary wall portion 14. Beginning with the boundary wall 14 to the boundary wall 13 the stack of disks 28 then gives up again the heat absorbed from the gas to the air flowing from space 11 over the annular sector 12 in the direction of arrow C toward the outer annular sector 15.

Foreign bodies as Well as dirt particles and other impurities, primarily taken along by the combustion gases but also by the unfiltered air deposit themselves readily at the disks 28 which themselves are relatively thin, for example, 0.10 mm. in thickness, and which are spaced from one another only at a very slight distance, for example, at a distance of 0.25 mm., and thereby clog up the same or at least contribute considerably to the reduction of the capacity to transfer heat. In order to avoid deposition of these foreign particles, sheet-metal strips 29 of similar undulated or corrugated configuration as disks 28 are arranged between the individual disks 28 which strips also form the

separating walls

13 and 14. As best shown in Figure 3, the sheet-metal strips 29 are of decreasing Width in the direction of rotation, i.e., have a wedge-shaped cross section as viewed in Figure 3, so that each time the edge 30 (Figure 2) which is first touched by the disks 28 in the direction of rotation thereof offers a larger cross section than the rear edge 31 thereof. The edges formed by the intersection of the side surfaces of the sheet-metal strips 29 and of the surfaces 30, therefore, produce a wiping action along the annular disk surfaces and thereby continuously clean the same.

The individual sheet-metal strips 29 are combined in a comb-like manner in the respective base portions thereof disposed toward the center in a manner not indicated in detail and are connected with the base portion 32 of the comb in any suitable manner. The base portion 32 of the comb-like assembly is held together in any suitable manner, for example, by means of the bolts or the like also used to hold the same in assembled position in the heat exchanger. The inclined arrangement of the sheetmetal strips 29, whereby the strips 29 are arranged slightly slantingly with the outer ends thereof in relation to the inner ends thereof in the direction of rotation, is particularly advantageous for purposes of cleaning. As a result of such an inclined arrangement, the inner parts of the disk stack disposed in a given radial plane, therefore, reach or encounter earlier the sheet-metal strip comb anthe outer parts thereof which are disposed in the same radial plane. Such an arrangement is particularly advantageous for the removal of foreign particles.

As shown in Figure 1, the corrugated or undulated construction of the disks 28 and of the spacer sheet-metal strips 29 for the disks 28 are such that they are matched to each other so that the edges of the corrugated sheetmetal strips serving as spacer pieces contact the abutting disks over the entire length of the edge thereof. Consequently, any dirt which may adhere to the disks is wiped off by these edges. Furthermore, by the increase of the heat-exchange surface of the disks 28 thus obtained the disks 28 can absorb more heat and correspondingly may give off more heat whereby the efficiency of the heat exchanger is considerably increased.

By reason of the corrugated or undulated shape of the disks 28 and of the sheet-metal strips 29 arranged therebetween, the exchange of heat between the individual media is considerably increased. The corrugated or undulated sheet-metal strips 29 are arranged coaxial to the axis of rotation of the heat exchanger with the rings of the corrugations thereof and are shaped essentially triangularly as shown in the cross-sectional view of Figure 3.

Consequently, an improvement of the heat exchange process according to the present invention is achieved by two means, namely by the arrangement of the sheet metal strips 29 between the disks 28 which effect continuous cleaning thereof and, on the other, by the identical corrugated configuration of the sheet-metal strips 29 and of the disks 28 to thereby increase the heat capacity thereof.

While I have shown and described one preferred embodiment in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of many modifications and changes within the scope of the present invention, and I intend to'cover all such changes and modifications as encompassed by the ap pended claims.

I claim:

1. A rotating heat exchanger for transferring heat from a first fluid medium to a second fluid medium comprising 1 rotary heat exchange means formed by a plurality of annularly-shaped rotatable disks, means including said disks forming a first sector for the passage therethrough of one of said fluid media in a radial direction and for forming a second sector for the passage therethrough of the other of said fluid media in a radial direction to transfer'heat to said other medium from said one medium by said disks, and means located between said disks and including a plurality of stationary spacer sheet-metal strips for simultaneously spacing said disks and continuously wiping off foreign particles deposited at said disks, both said rotatable disks and said sheet-metal strips being of matching wave shape in a radial direction thereof, said waves being arranged concentrically with regard to the center of rotation of said disks.

2. A rotating heat exchanger according to claim 1, further comprising stationary inlet and outlet connections for said media. a

3. A rotating heat exchanger according to claim. 1, wherein said sheet-metal strips are combined into a comblike assembly at the base portions thereof provided with a plurality of teeth formed by said strips.

4. A rotating heat exchanger according to claim 1, wherein said sheet-metal strips are essentially conically shaped in cross section with the apex thereof disposed in the direction of rotation of said disks in relation to the base thereof, so that the edges formed by the intersections of the base surface and side surface of the comb wipe off any foreign particles at said disks.

5. A rotating heat exchanger according to claim 1. wherein said sheet-metal strips assume the function of seals between said two media and define a boundary be tween said two sectors.

6. A rotating heat exchanger of drum-shaped construction for heating the combustion air of a gas turbine by the exhaust gases thereof comprising rotary heat exchange means formed by a plurality of annularly-shaped rotatable disks, stationary inlet and discharge means for each of said combustion air and said exhaust gases, means in said heat exchanger for subdividing the same into a first sector traversed by said gases in an essentially radial direction and into another sector traversed by said combustion air in an essentially radial direction for transferring heat from said gases to said air by said disks upon rotation thereof, and means including a plurality of Wedge-shaped stationary spacer sheet-metal strips located between'said annularly-shaped disks extending outwardly and inclined with respect to said radial direction for simultaneously spacing said disks and continuously wip' ing oif foreign particles deposited at said disks, both said rotatable disks and said sheet-metal strips being of matching corrugated shape with the corrugations disposed coaxially to the axis of rotation of said rotary heat exchanger.

7. A rotary heat exchanger of drum-shaped construction according to claim 6, wherein said sheet-metal strips also form the seals for defining the boundary between said sectors.

8. A rotary heat exchanger according to claim 6, wherein said sheetmetal strips are essentially conically shaped in cross section to provide a base surface and two side surfaces slanting towards each other to form wiping edges.

9. A rotating heat exchanger according to claim 1, wherein at least one of said spacing means is arranged within each said sector.

10. A rotating heat exchanger for transferring heat from a first fluid medium to a second fluid medium comprising a cylindrical casing, rotary heat exchange means formed by a plurality of annularly-shaped rotatable disks disposed eccentrically within said casing thereby forming diffuser-like annulus between the periphery of said disks and the cylindrical casing, means including said disks forming a first sector for the passage therethrough of one of said fluid media and for forming. a second sector for the passage therethrough of the other of said fiuid media to transfer heat to said other medium from said one medium by said disks, and means located between said disks and including a plurality of sheet metal strips for simul taneously spacing said disks and continuously wiping ofi foreign particles deposited at said disks, said annulus being provided with boundary means aligned with said strips and defining inlet and outlet passages between said first and said second media both said rotatable disks and said sheet metal strips being of matching wave shape in a radial direction thereof, said waves being arranged concentrically with regard to the center of rotation of said disks.

11. A rotating heat exchanger according to claim 1, wherein roller means are provided for supporting said annular disks, external ring means for connecting said individual disks thereto being provided with external tooth means, at least one of said roller means being provided with tooth means engaging the tooth means of said ring means for rotation thereof.

References Cited in the file of this patent UNITED STATES PATENTS 1,843,252 Toensfeldt Feb. 2, 1932 2,064,931 Lysholm Dec. 22, 1936 FOREIGN PATENTS 7 234,198 Great Britain May 28, 1925