US3308876A - Regenerative heat exchanger's plate heat transfer surface details - Google Patents

Description

March 14, 1967 A. J. GRAM, JR.

REGENERATIVE HEAT EXCHANGERS PLATE HEAT TRANSFER SURFACE DETAILS 2 Sheets-Sheet 1 Filed Aug. 30, 1965 INVENTORS Arrhur J. Gram,Jr

Andrew P. Lecon Ai'ToRNEY A. J. GRAM, JR, ETAL. 3,308,876 REGENERATIVE HEAT EXCHANGERS PLATE HEAT TRANSFER SURFACE DETAILS March 14, 1967 Filed Aug. 30, 1965 2 Sheets-Sheet 2 FIG.3

FIG.4

FIG.6

FIGS

n m 8 Y m -L E Y N N R E. O VJW T N e .l r n TA r A Y B U v v United States Patent 3,308,876 REGENERATIVE HEAT EXCHANGERS PLATE HEAT TRANSFER SURFACE DETAILS Arthur J. Gram, Jr., Wadsworth, and Andrew P. Lecon,

Akron, Ohio, assignors to The Babcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Aug. 30, 1965, Ser. No. 433,620 Claims. (Cl. 16510) The present invention relates to regenerative heat exchangers, and more particularly to an improved construction of closely spaced heat exchange elements for rotary regenerative heat exchangers.

Rotary regenerative air heaters are well known wherein heat exchange elements are arranged in sector shaped compartments within a cylindrical drum where a heating fluid and a fluid to be heated are passed in countercurrent relationship through separate compartments containing the heat exchange elements. Ordinarily the heat exchange elements are formed of parallel plates spaced for turbulent flow therethrough of the heating fluid and the fluid to be heated. It is also known to utilize various forms of spacers to establish the desired spacing between the parallel plates of the heat exchange elements. When using turbulent flow conditions for the fluid passing through the heat exchanger it is frequently desirable to arrange the heat exchange elements so as to permit limited vibration of plates during cleaning or soot blowing periods to aid in cleaning the heat exchange surfaces of the elements.

It has been found that heat exchange elements formed of closely spaced parallel plates are highly effective for heat exchange purposes where the fluid flow velocity through the heat exchange elements is of a non-turbulent or laminar flow characteristic. In such heat exchangers the depth of the heating surfaces can be substantially less than the depth of surface in turbulent flow heaters with equal heat exchange efliciency.

It has been found that it is essential to assemble the heat exchange surfaces of a non-turbulent or laminar flow heater so as to maintain the desired plate spacing under all operating conditions. This has been accomplished in accordance with the present invention by use of a rigid structure which reinforces the assembly of heat exchange elements to maintain the desired spacing and the desired fluid flow characteristics through the heat exchange elements during operation. More specifically the invention involves the construction of heat exchanger elements where the plates are stamped from a continuous strip of metal to form a selected pattern of perforations and indentations. The strip is bent along the perforations with the remaining metal providing hinges and the indentations providing a definite spacing when the plates are compacted. The length of the assembled package of heat exchange elements is dependent upon the number of plates in the assembly. The assembled package of spaced heat exchan e plates is attached to an element positioned along the top and bottom of the plates and welded to the edges thereof to form a rigid-and rugged package which will establish and maintain the desired fluid flow area between the heat exchange plates.

The various features of novelty which characterize our invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which we have illustrated and described a preferred embodiment of the invention.

3,308,876 Patented Mar. 14, 1967 0f the drawings:

FIG. 1 is an isometric view, partly in section, of a regenerative heat exchanger containing heat exchange elements constructed and arranged according to the present invention;

FIG. 2 is an enlarged isometric view of heat exchange elements constructed and arranged according to the invention;

FIG. 3 is an elevation view of the heat exchange plates shown in FIG. 2;

FIG. 4 is a plan view of the heat exchange plates shown in FIG. 2;

FIG. 5 is a schematic illustration of a die arrangement for manufacturing the heat exchange plates; and

FIG. 6 is an enlarged plan of the heat exchange plates as produced in the die shown in FIG. 5.

The rotary regenerative heater illustrated in FIG. 1 includes a stationary housing 10 arranged for the separate introduction and discharge of a heating fluid and a fluid to be heated. A cylindrical rotor 11 is mounted for rotation about a horizontal axis within the housing 10 and is constructed with radial partitions 12 extending substantially the full axial or longitudinal length of the rotor 11. The partitions 12 separate the cylindrical rotor into a plurality of sectors which are provided with heat transfer elements constructed in accordance with the present invention and arranged in axially spaced disk-like masses 13 adjacent the opposite ends of the rotor. Suitable seals, such as disclosed in copending application S.N. 249,736, are mounted on the housing to cooperate with the rotor in directing separate countercurrent fluid flows through the housing and the sectors of the cylindrical rotor. As the rotor is rotated about a shaft 14, the sectors of heat transfer material are alternately heated by contact with the heating fluid and then cooled by contact with the fluid to be heated.

As shown specifically in FIG. 1, the housing 10 is provided with an upper heating fluid inlet 15 radially arranged relative to the rotor so that the incoming fluid enters the axial mid-portion of the flow compartments formed between adjacent partitions 12 of the rotor, divides as it turns to flow through the disk-like masses 13 of heat transfer material positioned adjacent the opposite ends of the rotor 11, and discharges upwardly through radial outlet ducts 16 positioned in the housing 10 outwardly adjacent the opposite ends of the rotor 11. The flow of heating fluid is illustrated by the arrows 17.

Radial inlets 20 are provided in the opposite ends of the lower portion of the housing 10, for the admission of the fluid to be heated. The incoming fluid flows axially of the rotor through the disk-like masses 13 to combine in the mid-portion of the rotor and to discharge radially through an outlet 21 formed in the lower portion of the housing 10. The direction of flow of the fluid to be heated is illustrated by the arrows 22.

In a regenerative heater of the type disclosed, the depth of the disk-like mass 13 of heat transfer material positioned in the sectors is advantageously minimal in the direction of gas flow, i.e. longitudinally or axially of the shaft 14, and may be of the order of 6 to 16 inches, for example, to meet heat exchange requirements in the usual installation. The thickness of the mass 13 may be divided into two or more layers of elements for ease of installation and removal. For example, the cold end of the heat exchange mass, i.e. the outermost layer, may be only 2 or 3 inches in depth and may be constructed of low alloy metal to resist corrosion. The remaining layer or layers of heat exchange elements may be constructed of carbon steel, for example, 2 to 6 inches in thickness.

3 Each layer may be assembled of a plurality of packaged elements positioned in side by side and end to end relationship and assembled as a pie shaped mass to fit in the sector formed between adjacent partitions 12.

When installed in the rotor 11 the sector shaped layers may be spaced in the direction of gas flow to provide a clearance for separate insertion or removal of each layer and to provide a mixing and distribution effect for the fluids passing through one layer into another layer of heat exchange surfaces. The space between layers may be of the order of A inch.

The heat exchange elements forming the masses .13 are constructed and arranged to provide closely spaced surfaces between which the fluids flow. As shown in Fig. 6 a strip of steel 30, having the desired thickness and width, is passed between upper and lower dies 31 and 32 respectively, where the strip is formed to the desired configuration. The width of the strip 30 corresponds to the depth (in the direction of fluid flow) of the layer of heat exchange surface installed in the regenerative heater. For example, the width of the strip may be 2 to 6 inches and the thickness may be 26 gage (0.0179 inch).

The dies 31 and 32 are vertically relatively movable by the usual stamping mechanism (not shown) to perforate and emboss the strip therebetween in a pattern such as shown in FIG. 6, for example. As shown, the strip is perforated to form slotted openings 33 of, for example, 0.045 inch in the longitudinal dimension of the strip, and inch in the transverse direction and so spaced as to leave metal connecting adjoining portions A and B of. the strip. The connecting metal 36 provides hinges so that the strip may be bent at the hinges to form parallel plate surfaces corresponding to the portions A and B.

When the strip is perforated or cut to form the portions A and B each portion is simultaneously deformed or embossed to form dimples 37. As shown, in FIGS. and 6 the dimples 37 formed in portion A are displaced downwardly from the plane of the strip while the dimples in portion B are oppositely, or upwardly, displaced. The dimples may be of the order of Ms inch diameter and extend 0.045 inch beyond the plane of the strip portion A or B so as to establish a plate spacing of 0.045 inch between surfaces of the heat exchange mass when the elements are assembled for the flow of fluid therethrough. The spacing between dimples is arranged to maintain the interplate spacing with a minimum of fluid flow restriction between the plates. In a typical arrangement the dimples are transversely spaced /2 inch while the longitudinal spacing may be approximately 1 inch.

As shown oin FIGS. 3, 4, 5 and 6 the dimples 37 may be arranged in portions A and B to a common longitudinal spacing, as each is measured from a corresponding maintained by welding transverse metal elements, such as rods or strips 46 and 48 in edge relationship with the plates 40 to 45 on opposite sides of the package. The strips 46 and 47 are positioned between the metal hinges 36 and not only rigidly hold the plate to plate relationship of the package, but also provide structural strength to the assembly.

In the embodiment shown the width of the strip 30, and thus the depth in a fluid flow direction of the package 38 is 2 inches while the height of each package is 3 /2 inches. When a package is formed 4 to 6 inches in depth, more than one of the strips 46 and 47 are welded between hinges to the edges of the plates to increase the rigidity of the package.

While in accordance with the provisions of the statutes we have illustrated and described herein the best form and mode of operation of the invention now known to us, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes be used to advantage without a corresponding hinge end. The transverse spacing in portion B will be displaced with respect to the transverse spacing in portion A so that a dimple in one portion will not correspond in transverse location with the dimple in an adjoining portion. a

With two portions A and B of the strip 30 formed simultaneously, the strip is advanced a distance equal to the length. of portions A and B after each action of the die press. After leaving the dies 31 and 32, the successive portions A and B are folded in alternate directions at the hinges to form a package of parallel spaced plates. The bending of the successive portions A and B may be performed manually or mechanically and the number of plates so arranged will be dependent on the length of the package of heat exchange elements desired.

As illustrated in FIGS. 3, 4 and 5 a portion of a package 38 of heat exchange elements is formed by arranging successive bent portions A and B in abutting relationship.

As shown the plates 40, 42 and 44 correspond with the plates B while the plates 41, 43 and correspond with the plates A. The dimples 37B of plates 40, 42 and 44 bear against the adjoining surfaces of the plates 41, 43 and 45 to establish the spacing therebetween which is use of other features.

What is claimed is:

1. In a rotary regenerative fluid heater having a stationary housing, a cylindrical rot-or having radial partitions forming a plurality of sector shaped compartments therein, regenerative heat exchange material positioned in each of said compartments, means for passing a heating fluid and a fluid to be heated in counterflow relationship separately through said compartments containing said regenerative heat exchange material, said regenerative heat exchange material comprising a plurality of rows of metallic plates arranged in stacked rows, the plates in each row being connected by a perforate 'hinge at opposite ends with an opposite adjacent plate, each plate being dimpled in the same assembled direction to provide a closely spaced fluid flow passageway between adjacent.

plates, and metallic means transversely positioned along and between opposite connected ends of and welded to each of said plates for rigidly attaching said plates in each row of plates to maintain said closely spaced relationship therebetween.

2. A heat exchange package adapted for rotors in a regenerative heater comprising a plurality of closely spaced parallel plates formed from a continuous strip of metal, said strip being perforated at longitudinally equally spaced transverse locations and bent in opposite directions at the perforations to form the connecting end portions of said parallel plates, means for substantially uniformly spacing said plates, and means for maintaining in said package the spaced relation of said parallel plates including a metal element extending transversely along and between the connecting end portions of said plates,

said element being welded to the edge of each of said plates.

3. A heat exchange package adapted for rotors in a regenerative heater comprising a plurality of closely spaced substantially parallel plates, each plate connected by a perforate hinge portion at opposite ends with an opposite adjacent plate, each plate having spaced portions thereof displaced in one direction, said displaced portions providing a substantially uniform spacing between said plates when the displaced portions of one plate contact the surface of a next adjacent plate, and a metal element extending transversely along and between the connected ends of said plates and engaged with the edges of said plates to rigidly hold the plates in said package.

4. A heat exchange package adapted for rotors in a laminar flow regenerative fluid heater comprising a plurality of flat plates, each plate integrally connected by a perforate hinge at opposite ends with an opposite adjacent plate, each plate being dimpled in one direction, said dimples providing a substantially uniform transverse spacing between said plates when the dimples of one plate contact the flat surface of a next adjacent plate, and a metal element extending the length of said package adjacent opposite connected ends between the integral connections thereof and welded to the edges of said plates to rigidly connect the plates in each package.

5. A heat exchange package adapted for rotors in a laminar flow regenerative fluid heater comprising a plurality of substantially uniformly spaced parallel plates, each plate connected by a perforate hinge at opposite ends with an opposite adjacent plate, each plate being dimpled in one direction, the dimples in one plate being transversely displaced relative to the dimples in the adjoining plate to engage the flat surface of the adjoining plate, said dimples providing a substantially uniform transverse laminar flow spacing between said plates when the dimples of one plate contact the surface of a next adjacent parallel plate, and at least one flat metal element extending across said package between the connected ends of said plates and Welded to the edge of each plate to rigidly connect the plates in each package.

References Cited by the Examiner UNITED STATES PATENTS 3/1905 Shiels et a1; 165167 5/1932 Riley 1654 9/1942 Peterson 165167 X 12/1947 Karlsson et a1. 165-5 2/1954 Lundstrom 165-166 9/1954 Boyd 29-33.6 11/1959 Kritzer 29-33.6 6/1960 Ramen 165166 X 7/1960 Slemmons 165166 X 6/1965 Brandt 165-4 FOREIGN PATENTS 1/1957 Great Britain.

ROBERT A. OLEARY, Primary Examiner.

0 T. W. STREUEL, Assistant Examiner.

Claims (1)

1. IN A ROTARY REGENERATIVE FLUID HEATER HAVING A STATIONARY HOUSING, A CYLINDRICAL ROTOR HAVING RADIAL PARTITIONS FORMING A PLURALITY OF SECTOR SHAPED COMPARTMENTS THEREIN, REGENERATIVE HEAT EXCHANGE MATERIAL POSITIONED IN EACH OF SAID COMPARTMENTS, MEANS FOR PASSING A HEATING FLUID AND A FLUID TO BE HEATED IN COUNTERFLOW RELATIONSHIP SEPARATELY THROUGH SAID COMPARTMENTS CONTAINING SAID REGENERATIVE HEAT EXCHANGE MATERIAL, SAID REGENERATIVE HEAT EXCHANGE MATERIAL COMPRISING A PLURALITY OF ROWS OF METALLIC PLATES ARRANGED IN STACKED ROWS, THE PLATES IN EACH ROW BEING CONNECTED BY A PERFORATE HINGE AT OPPOSITE ENDS WITH AN OPPOSITE ADJACENT PLATE, EACH PLATE BEING DIMPLED IN THE SAME ASSEMBLED DIRECTION TO PROVIDE A CLOSELY SPACED FLUID FLOW PASSAGEWAY BETWEEN ADJACENT PLATES, AND METALLIC MEANS TRANSVERSELY POSITIONED ALONG AND BETWEEN OPPOSITE CONNECTED ENDS OF AND WELDED TO EACH OF SAID PLATES FOR RIGIDLY ATTACHING SAID PLATES IN EACH ROW OF PLATES TO MAINTAIN SAID CLOSELY SPACED RELATIONSHIP THEREBETWEEN.

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