US3786862A - Heat exchange oil construction - Google Patents

Abstract

A heat exchange coil having a removable header which includes a peripheral rim having edgewise engagement with the tube sheet. Special clamp devices located outside the rim act to apply controlled compressive forces on an endless deformable seal element squeezably interposed between the edge of the rim and the face of the tube sheet. Total surface area of the rim edge is small so that a given compressive force provides a comparatively large p.s.i. sealing force. The lessened edge contact area also advantageously minimizes the possibility of leakage due to local surface imperfections such as ridges, bumps, nicks, depressions, etc.

Description

United States Patent 1 Zipser et a1.

[ Jan. 22, 1974 41 HEAT EXCHANGE OIL CONSTRUCTION [75] Inventors: David Bernard Zipser; Russell H.

Bullard, both of Wilmington, NC.

[73] Assignee: The Singer Company, New York,

[22] Filed: Apr. 30, 1971 [21] Appl. No.: 138,957

[52] US. Cl. 165/158 [51] Int. Cl F28f 9/14 [58] Field of Search 165/143-145, l58162,

[56] References Cited UNITED STATES PATENTS 3,151,674 10/1964 Heller et a1. 165/158 1,997,194 4/1935 Leach 165/161 X 2,900,173 8/1959 Pickford 165/161 2,762,611 9/1956 Monroe et 211.. 2,061,429 11/1936 Leach 165/70 X Primary ExaminerCharles J. Myhre Assistant ExaminerTheophil W. Streule, Jr. Attorney, Agent, or FirmMarshall .l. Breen; Chester A. Wiliams, Jr.; William V. Ebs

[57] I ABSTRACT A heat exchange coil having a removable header which includes a peripheral rim having edgewise engagement with the tube sheet. Special clamp devices located outside the rim act to apply controlled compressive forces on an endless deformable seal element squeezably interposed between the edge of the rim and the face of the tube sheet. Total surface area of the rim edge is small so that a given compressive force provides a comparatively large p.s.i. sealing force. The lessened edge contact area also advantageously minimizes the possibility of leakage due to local surface imperfections such as ridges, bumps, nicks, depressions, etc.

2 Claims, 7 Drawing Figures Pmmanmw I I 3.786.862

65 IN VENTOR.

DAVID B. ZIPSEE HEAT EXCHANGE OIL CONSTRUCTION THE DRAWINGS FIG. 1 is a transverse sectional view taken through a heat exchange coil embodying the invention.

FIGS. 2 and 3 are sectional views taken on lines 2-2 and 3-3 in FIG. I.

FIGS. 4, 5 and 6 illustrate structural details that can be employed in the FIG. 1 device.

FIG. 7 is an enlarged view in the direction of FIG. 3, but illustrating another embodiment of the invention.

FIGS. 1 THROUGH 3 FIG. 1 shows a finned-tube heat exchange coil 10 having four rows of heat exchange tubes 12 adapted to have hot water, cold water or similar heat transfer liquid flow therethrough for exchange of heat with air or other gas flowing past plate fins 11 located on the tube outer surfaces. Tubes- 12 extend between a first tube sheet 14 (FIG. 3) and a second similar tube sheet, not shown, at the remote side of the coil.

As illustratively shown in FIG. 2, each tube sheet 14 is welded or otherwise secured to an upper transverse baffle sheet 16 and a lower transverse baffle sheet 18; similar welded connections are provided between the non-illustrated tube sheet and other ends of the baffle sheets, such that the assembly forms a rectangular due when viewed in the direction of FIG. 2.

' The baffle sheets are provided with full length flanges 20, and the tube sheets are provided with full length flanges 22, so that the rectangular duct presents picture-frame attachment surfaces to the flanges 24 and 26 of adjacent duets 28 and 30. Suitable nut-bolt assemblies (not shown) can be extended through holes in the mating flanges to operatively locate coil 10 between air supply duct 28 and air exhaust duct 28. In practice, duct 28 and/or duct 30 may be a filter, sprayed coil humidifier, reheat coil, blower scroll, transition duct, straight duct, or duct elbow, etc.

Water or other heat transfer liquid is supplied to the leftmost row of tubes 12 through a supply pipe 32 connected to flat end wall 34 of a header generally designated by numeral 36. The header includesa peripheral sheet metal rim member 38 of hoop-like character. As shown in FIGS. 2 and 3, rim member 38 is positioned with its opposite end edges against the flat faces of tube sheet 14 and header end wall 34. Suitable gaskets or deformable seals are interposed between the rim edges and the opposed walls 14 and 34 to form fluid tight joints.

. The FIG. 3 header is formed to include a full length partition 40 between the first and second row of tubes, and a second full length partition 42 between the third and fourth row of tubes. The other header (not shown) is formed with a single full length partition between the second and third rows of tubes. Accordingly liquid admitted through pipe 32 is caused to flow in a sinuous path through the various rows of tubes, as denoted by the directional arrows in FIG. 3. Liquid exits from the coil through return pipe 35.

Rim member 38 is formed of one or more lengths of sheet steel bent around smooth radii into a four sided rectangular construction, comprising a rim top wall 44, rim side walls 46 and 48, and rim bottom wall 50. The abutting ends of the steel sheet may be welded, as to 52, to form an endless hoop. The rim wall thickness (dimension A) and rim wall length (dimension B) are preferably constant along the entire rim cross section such that deformable elastomeric seals 54 and 56 can be positioned thereon to seal the respective peripheral joints between the rim and walls 14 and 34. Sufficient axial compressive forces may be applied to the seals by means of threaded devices of the type shown in FIGS. 4 and 5.

As shown in FIG. 4, the force-applying device consists of an elongated spacer block 58 having bolts 60 and 62 threaded into taped holes in its end faces: after bolt 60 has been fully threaded into block 58, bolt 62 can be screwed into block 58 to force wall 34 toward wall 14 so as to apply a compressive force on seals 54 and 56. A number of the FIG. 4 spacer blocks are provided outside rim 38 in accordance with the size of the heat exchange coil; as shown in FIG. 1, there are a total of 10 spacer blocks, arranged three along each coil edge vertical edge and two along each coil horizontal edge.

The illustrated coil is of the removable-header type wherein each rim 38 and header end wall 34 can be removed from the coil to gain access to the interiors of tubes 12 for cleanout purposes. Thus, when each of the bolts 62 has been unthreaded from its spacer block 58, the header end wall 34 can be lifted away from the coil tube sheet. Rim 38 is then left in a floating position such that it too can be lifted off the tube sheet. Seals 54 and 56 are sized to frictionally grip the side surfaces of the rim 38 wall and therefore they come off with the rim during header removal; spacers 58 stay in place on tube sheet 14. When the illustrated header (comprising members 34 and 38) and the non-illustrated header are removed from the coil it is possible to clean the tube interiors with conventional elongated cleaning devices.

THE INVENTION One feature of the invention resides from the fact that only the end edges of rim 38 are required to press against deformable seals 54 and 56. Formerly it was common practice to flange the rim outwardly and to attempt to seal across the entire flange face; with such an arrangement the axial forces provided by the clamping devices were sometimes insufficient to produce satisfactory unit pressure sealing forces. By using only the end edges of rims 38 as seal-deforming surfaces it is possible to achieve relatively high compressions or deformations of thesealing element and correspondingly higher sealing resistances.

The axial compressive clamping forces are relatively high on the block 58 axis and on the adjacent portions of rim wall 38. If blocks 58 were spaced too far apart the high internal hydraulic pressure within header 36 (in excess of 200 p.s.i.) could bow or bend rim wall 38 outwardly. To prevent bow-out of the rim wall the blocks 58 are preferably formed with flat side surfaces in close adjacency to the outer faces of the rim wall; outward stress on the rim wall is thus resisted by the rim material and also by the back-up spacer blocks. The areas of the rim wall midway between adjacent ones of the spacer blocks are not directly supported by the blocks, and are thus more apt to bow or bend outwardly. It is believed that the high clamping pressures imposed on seal elements 54 and 56 by the rim end edges will set up frictional locks between the seal elements and the faces of walls 14 and 34 such as to reinforce the rim wall areas midway between the spacer blocks. As a result of the improved frictional lock and back-up spacer blocks it should be possible in some cases to reduce the number of blocks required (i.e., to increase the block spacing).

An advantageous feature of the FIG. 4 block construction is that it automatically controls the compression imposed on the seal elements. Thus, the block length can be chosen to be a known dimension, sufficiently larger than the rim length B so that seals 54 and 56 are each compressed a predetermined amount. With such an arrangement the bolts 62 can be field-tightened as far as they can be tightened, with assurance that the actual seal compression corresponds with the design value specified by the manufacturer; this avoids the need for torque wrenching and eleminates the possibility of uneven seal compression around the rim periphery.

It will be noted that each seal 54 or 56 has a flap portion lying against the inner face of rim wall 38. It is theorized that high hydraulic pressures will tend to impact the flap wall tightly against the rim wall-face to further increase the sealing effect. Thus, it is believed that the sealing action is produced not only by axial compression of the seal elements against the end edges of the rim, but also by outward pressure of the seal flap areas against the rim inner face. Should there by any slight imperfections or disruptions in the rim edges which the compressed elastomer cannot effectively seal then the flap areas give added seal insurance.

FIG. 5

FIG. 5 illustrates a slight variation of the FIG. 4 structure, wherein each spacer block 58a is of circular cross section rather than square cross section. Also, each block 58a includes a threaded end 60a which goes into a taped hole in wall 14, and a threaded end 61 which receives a nut 62a for applying axial force on the sealing elements 54 and 56a. The rim 38a in FIG. 5 is formed from a thickened steel sheet having its ends chamfered or tapered at 59 so that the rim end edges have relatively small cross sectional areas presented to the elastomeric sealing elements 54a and 56a. The thickened nature of the rim serves to mechanically reinforce the rim against outward bowing tendencies, and the chamfering 59 serves to provide the desired high axial sealing pressures on the elastomeric seal elements.

FIG. 7

FIG. 7 illustrates an embodiment of the invention wherein the rim 38b is formed integrally with header end wall 34b. The clamping devices comprise bolts 58b having threaded ends 61b adapted to receive nuts 62b located on the outer faces of plates 63 carried by the header. Annular collars 65 provide the sealcompression control function; the collars also may be used as a back-up devices to curtail bow-out of the rim 38b. The operation of the FIG. 7 device is generally similar to that previously described in connection with FIGS. 1 through 4.

I claim:

1. In a heat exchange coil having a flat tube sheet, an improved header assembly comprising a flat header end wall paralleling the-tube sheet, a peripheral sheet material rim interposed between said tube sheet and said header end wall, an endless deformable seal of elastomeric material positioned between the tube sheet and one edge of the rim, said seal having a contiguous flap in sealing engagement with the internal wall of said rim, means for drawing the header end wall toward the tube sheet to apply a compressive force on said seal said means including individual spacer members of a length greater than the rim length affixed to the tube sheet at peripherally spaced points outside the rim, and clamping means operative axially to draw said header end wall toward said tube sheet until said axial movement is precluded by said spacer members, thereby to apply a predetermined compressive force on said first seal.

2. The coil of claim 1 wherein a second endless deformable seal of elastomeric material is positioned between said header wall and the other edge of said peripheral rim, and second seal having a contiguous flap in sealing engagement with the internal wall of said rim and said clamping means being operative to apply a predetermined compressive force on both said first and second seals.

Claims (2)

1. In a heat exchange coil having a flat tube sheet, an improved header assembly comprising a flat header end wall paralleling the tube sheet, a peripheral sheet material rim interposed between said tube sheet and said header end wall, an endless deformable seal of elastomeric material positioned between the tube sheet and one edge of the rim, said seal having a contiguous flap in sealing engagement with the internal wall of said rim, means for drawing the header end wall toward the tube sheet to apply a compressive force on said seal said means including individual spacer members of a length greater than the rim length affixed to the tube sheet at peripherally spaced points outside the rim, and clamping means operative axially to draw said header end wall toward said tube sheet until said axial movement is precluded by said spacer members, thereby to apply a predetermined compressive force on said first seal.

2. The coil of claim 1 wherein a second endless deformable seal of elastomeric material is positioned between said header wall and the other edge of said peripheral rim, and second seal having a contiguous flap in sealing engagement with the internal wall of said rim and said clamping means being operative to apply a predetermined compressive force on both said first and second seals.

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