TW201437600A - Shell and tube heat exchanger, end cover and method of manufacturing same - Google Patents

Abstract

A shell and tube heat exchanger, an end cover and a method of manufacturing the same are disclosed. The shell and tube heat exchanger (1) comprises a shell and at least one end cover (1) attached to an end of the shell (5). The end cover (100) comprises a plastics or plastic composite body (105) and a metal plate member (110) encased by the plastics body to provide structural rigidity to the plastics body.

Description

Shell and tube heat exchanger and method for manufacturing end cap

The present invention relates to a shell and tube heat exchanger, an end cap for a shell and tube heat exchanger, and a method of making an end cap for a heat exchanger. The preferred embodiment is particularly applicable to shell and tube heat exchangers and heat exchangers for use in marine or other corrosive environments.

In the prior art, shell and tube heat exchangers are known per se and many types of such heat exchangers are commercially available. Now, the operation of a shell-and-tube heat exchanger will be briefly explained with reference to the example shown in FIG. 1; FIG. 2A shows a longitudinal sectional view of the heat exchanger shown in FIG. 1; and FIG. 2B shows the heat exchange shown in FIG. An exploded view of the device. The heat exchanger 1 comprises: an outer casing in the form of a substantially cylindrical casing 5; and two end caps fixed to each end of the casing 5. The housing 5 has an inlet 11 at one end and an outlet 12 at the other end. The inlet 11 and outlet 12 are commonly referred to as housing side turns or nozzles. A tube stack 13 is provided in the housing 5. The tube set 13 includes a plurality of tubes 14 extending longitudinally from one end of the housing 5 to the other end. The tube 14 is secured at either end thereof by a tube sheet 15 which extends through the tube sheet 15 and is secured by the tube sheet 15. This is used to hold the tube 14 in position and form a sealing engagement with the inner surface of the housing 5. Thus, the tube 14 provides a series of passages through the housing 5 that are sealingly provided by the housing side turns, the inlet 11 and the outlet 12. The conduits through the housing are isolated. One or more baffles 16 may be included in the tube set 13 to direct fluid flow along the tubes 14 along the tube side to increase speed and heat transfer efficiency. The baffle 16 is also used to support the tube 14 and prevent vibration.

The end cap 10 includes a plurality of substantially circular plates with a plurality of spaced bolt holes distributed along the periphery of the plate. The end cap 10 is screwed to the flange at either end of the housing 5 via a bolt 19 that is threaded into a threaded bore 20 in the end of the flange. An O-ring 22 is disposed between the end cap 10 and the flange 21 at the end of the housing 5 to assist in sealing the end cap to the housing 5. The end cap has an internal thread 埠 24 that provides an inlet 25 and an outlet 26 in fluid communication with the tube in the tube set 13. These defects are often referred to as tube side defects.

A tube set 13 can be floated to minimize thermal stress or can have a bellows configuration. In operation, the fluid to be cooled is pumped into the housing 5 via the housing side turns 11 and 12. The fluid for cooling is pumped into the tube 14 via the tube side turns 25, 26. Tube 14 provides a heat transfer surface between a fluid flowing through tube 14 and another fluid flowing outside of tube 14. Therefore, heat exchange can be performed between the two fluids.

The end cap can also have a threaded bore 28 therethrough, with a drain plug screwed into the threaded bore 28. By unscrewing the bleeder plug 29 from the end cap 10, fluid can be vented from the tube side passage through the heat exchanger 1.

Many variations of this basic example of a shell-and-tube heat exchanger 1 are known. For example, the tube side fluid can form more than one tube side passage. In this case, one or both of the end caps 10 can provide a pass divider to isolate fluids on different passages from one another.

Shell and tube heat exchanger 1 is often used in a corrosive environment. For example, the shell The tube heat exchanger 1 can be used with a marine engine to cool various fluids associated with the engine. Figure 3 is a typical configuration showing the location of various heat exchangers 1 for cooling a marine engine 500. As indicated by arrow 501, seawater is pumped through the tube side turns 25, 26. As indicated by arrow 502, the fluid to be cooled from the exhaust manifold and the oil cooler located on the engine 500 is pumped into a closed loop via the housing side turns 11, 12 in each heat exchanger 1. The road is cooled by seawater flowing through the tube 14 in the heat exchanger 1.

As will be appreciated, the use of seawater as a cooling fluid means that the tube side conduits through the heat exchanger 1 must be corrosion resistant. The end cap 10 is removable so that when the tube set 13 is damaged or corroded, the tube set 13 can be removed or replaced. At present, it is known to manufacture the end cap 10 with brass to resist corrosion. Figures 4A and 4B show an example of one of the end caps made of brass as known in the prior art. It is particularly preferable to use naval brass containing 40% zinc and 1% tin because of its seawater corrosion resistance. However, the use of brass as a material is relatively expensive, so it would be helpful to use a cheaper alternative material.

Cast iron end caps are sometimes used with fresh water, ie for corrosion reasons, not for use with sewage or sea water. In less demanding applications, it is known to use plastic end caps, such as glass filled nylon. However, in many applications, the pressure applied to the fluid on the housing side when pumping into the heat exchanger means that the plastic end cap is not suitable because the plastic end cap can be deformed or broken by the pressure applied thereto. Furthermore, the strength of the inlet made of plastic may not be sufficient to support the coupling with the outer tube for guiding the fluid to the tube side of the heat exchanger.

There is a need for an end cap that provides sufficient strength and rigidity for demanding applications while maintaining corrosion resistance to, for example, seawater, as compared to using conventional materials (eg, Brass) is cheaper. Specifically, it is preferable to use a brass connection system for the seawater inlet and the bleeder plug. The material used needs to have sufficient rigidity in the area of the bolt holes. At pressures up to 30 bar or more, the end cap should not deflect around the O-ring sealing surface.

According to a first aspect of the present invention, a shell and tube heat exchanger is provided, the shell and tube heat exchanger comprising a casing and at least one end cover attached to one end of the casing, the end cap comprising: a plastic body or a plastic composite body; and a metal plate member covered by the plastic body to provide structural rigidity to the plastic body.

The use of plastics reduces the cost of the end caps and renders the end caps resistant to the application of corrosive fluids (e.g., seawater) through the heat exchanger. The sheet metal member provides structural rigidity to the plastic body and means that the end cap can handle pressures higher than the plastic itself can handle. The metal does not need to be corrosion resistant because it can be completely enclosed by the plastic, or at least largely enclosed by the plastic, so that at least the portion of the metal sheet that will contact the corrosive fluid is obscured. Thereby, the end cap is formed at a lower cost, which is capable of coping with higher pressure and having corrosion resistance compared to the prior art end cap for the shell and tube heat exchanger.

Preferably, the thickness of the metal plate is between 0.5 mm (mm) and 3 mm.

Preferably, the metal sheet extends over a substantial portion of the radial extent of the end cap.

Preferably, the sheet metal member is formed from press-formed steel having a zinc coating as needed.

Preferably, the sheet metal member has a generally dome shape having a flange at a periphery thereof, the flange being located at a position corresponding to a bearing surface between the end cap and the housing.

In an embodiment, the end cap has a sealing surface for receiving the housing, the housing having two or more bolt holes for screwing the end cap to the housing, Wherein the bearing surface is bent between the bolt holes, and the bearing surface bears a resilient bias against the housing when the end cap is screwed to the housing. Elasticity of the end cap means that the curved portion "resiliently" abuts against the housing to form a better seal in the region further away from the bolt hole and thus not less directly clamped by the bolted connection. The degree of bending is preferably smoothly increased to a maximum height at a centered position substantially between the bolt holes. Preferably, the curved portion is configured to maintain a substantially similar sealing pressure around the periphery of the end cap. This means that for a given clamping force, the end cap can advantageously handle greater pressure.

In one embodiment, the end cap includes at least one metal insert adapted to receive a fastener and be covered by the plastic body. This provides a means of achieving a more secure and reliable connection of the end caps, for whatever reason, as compared to direct connection to plastic materials.

In one embodiment, the at least one metal insert is a weir member for providing an inlet to the tube side of the heat exchanger.

In an embodiment, the jaw member has internal threads for connection.

In one embodiment, at least one of the provided metal inserts has a threaded connection for receiving a bleed plug.

Preferably, the at least one metal insert comprises a metal sleeve having a consistent perforation in a bearing portion of the end cap, wherein a threaded fastener clamps the end cap by the metal sleeve To the housing of the heat exchanger. This helps achieve a greater clamping force without damaging the plastic material around the perimeter of the end cap and bearing surface.

In an embodiment, at least one metal sleeve is mechanically coupled to the metal plate Interlocking. This helps to stabilize the metal sleeve during manufacture and helps to direct the force from the bolt connection from the bolt to the metal sheet, thereby reducing stress on the plastic material.

In one embodiment, the at least one metal sleeve has a circumferential groove around at least a portion of its outer surface, and wherein the metal plate member has at least one cut-away portion at its periphery, the at least one cut-away portion for Mechanically interlocked with the circumferential groove. This is a preferred way to interlock the sleeve with the plate.

In an embodiment, the plastic body is overmoulded to the metal sheet member and/or at least one metal insert.

In an embodiment, the metal insert is formed from brass.

According to a second aspect of the present invention, a method for manufacturing a shell and tube heat exchanger as described above is provided, the method comprising: positioning the sheet metal member in an injection molding tool, and coating the plastic Formed on the metal plate member.

Preferably, the heat exchanger comprises at least one metal insert adapted to receive and be partially covered by the plastic body, the method comprising: molding the plastic into the insert Prior to the sheet metal member, the at least one metal insert is positioned on a dowel to accurately position the insert in the injection molding tool.

In one embodiment, the metal inserts comprise a plurality of metal sleeves, the metal sleeves providing a plurality of through holes in the bearing portion of the end cap for passing through the metal sleeves A plurality of threaded fasteners of the tube clamp the end cap to the housing of the heat exchanger, the method comprising: mechanically interlocking the metal sleeve with the sheet metal member prior to forming the plastic .

According to a third aspect of the present invention, a heat exchanger for a shell and tube is provided The end cover comprises: a plastic body; a metal plate member covered by the plastic body to provide structural rigidity to the plastic body.

In an embodiment, the end cap includes additional features of any of the embodiments described above.

The use of the various embodiments for the heat exchange method may have particular advantages when the tube side passing through the heat exchanger is corroded, for example when using seawater as a cooling fluid in a heat exchanger for cooling a marine engine or the like. .

It should be understood that any feature that is expressed herein as being "in one embodiment" or "better" can be combined with any one or more of the other features and any one or more aspects of the invention. Provided in combination.

1‧‧‧Shell tube heat exchanger

5‧‧‧Shell

10‧‧‧End cover

11‧‧‧ Entrance

12‧‧‧Export

13‧‧‧ tube group

14‧‧‧ tube

15‧‧‧ tube plate

16‧‧‧Baffle

19‧‧‧ bolts

20‧‧‧Threaded holes

21‧‧‧Flange

22‧‧‧O-ring seal ring

24‧‧‧Internal thread

25‧‧‧ entrance

26‧‧‧Export

29‧‧‧Relief plug

100‧‧‧End cover

101‧‧‧ tube side

102‧‧‧Bolt holes

103‧‧‧ venting plug

105‧‧‧Plastic body

106‧‧‧Central Dome

107‧‧‧ sealing surface

107a‧‧‧Bend

108‧‧‧ inner lip

109‧‧‧Central rib

110‧‧‧Thin metal components

111‧‧‧Bottom flange

112‧‧‧cutting section

113‧‧‧cut section

115‧‧‧Inlays

119‧‧‧ axial ribs

120‧‧‧Inlays

121‧‧‧Ontology

122‧‧‧Threaded inner surface

123‧‧‧Flange

125‧‧‧Inlays

126‧‧‧ Ontology

127‧‧‧circular groove

500‧‧‧ Marine Engine

502‧‧‧ arrow

A-A, B-B‧‧ lines

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: FIG. 1 shows one of the prior art shell-and-tube heat exchangers; and FIG. 2A shows one of the heat exchanges shown in FIG. Longitudinal sectional view of the apparatus; FIG. 2B shows an exploded view of the heat exchanger shown in FIG. 1; FIG. 3 shows a heat exchanger for cooling a marine engine; FIGS. 4A and 4B are respectively shown in the prior art. A cross-sectional view and a plan view of an end cap for a heat exchanger; FIGS. 5A and 5B respectively show a front end view and a rear end view of an example of an end cap according to an embodiment of the present invention; FIGS. 6A and 6B The figure shows the longitudinal direction of the insert of the end cap shown in Figures 5A and 5B, respectively. Cross-sectional view and plan end view; FIGS. 7A and 7B are respectively a longitudinal cross-sectional view and a plan end view of the insert for the bleeder plugs in the end caps shown in FIGS. 5A and 5B; FIGS. 8A and 8B; The figure shows a longitudinal sectional view and a plan end view of one of the inserts for the bleeder plugs shown in Figs. 5A and 5B; Fig. 9A shows a plan view of the end caps shown in Figs. 5A and 5B; The end caps are shown from the rear side; the 9C and 9D figures show cross-sectional views of the end caps; and the 10th graph shows a perspective view of the steel for press forming of one of the end caps shown in Figs. 5A and 5B.

5A and 5B show an example of an end cap 100 in accordance with an embodiment of the present invention. Fig. 5A shows a perspective view of the observation from the front side, and Fig. 5B shows a perspective view of the same from the rear side. The end cap 100 can be used, for example, with the shell and tube heat exchanger 1 shown in Figures 1 to 3. As will be understood by those skilled in the art, many types of shell and tube heat exchangers are known, and the end cap 100 of the present invention can be modified for use with different heat exchanger designs utilizing the well-known principles.

The end cap 100 is a substantially dome-shaped member for attaching to or covering one end of the housing 5 of the heat exchanger, and has a tube side sill 101, which can be attached to the end cap 100 as needed Which end of the housing 5 is used as an inlet or opening. Referring to Figure 5B, which shows the end cap 100 as viewed from the rear side (i.e., from the side of the housing), the end cap 100 has a central dome portion 106 that is positioned around one of the perimeters of the dome portion 105. 107 surround, sealing surface 107 bears hot The end of the housing of the changer 10 forms a seal with the end of the housing. The end cap 100 has three bolt holes 102 extending through the sealing surface 107 for screwing the end cap 100 to the housing 5 of the heat exchanger 1. The end cap 100 also has an optional aperture for receiving a bleeder plug 103.

Continuing with reference to Figure 5B, the rear end of the end cap 100 has an inner lip 108 for receiving the tube set of the heat exchanger 1. The rear portion of the end cap 100 also has a central rib 109 adjacent the crucible 101 that extends from the surface of the central dome portion 106 toward the housing 5 and aids in directing fluid flow through the heat exchanger 1.

The end cap 100 includes a thin metal member 110 formed in a plastic body or a plastic composite body 105. Preferably, a glass filled nylon (GFN) is used for the plastic molding to form the plastic body 105. 50% GFN or any other suitable molded plastic or plastic composite can be used. Figure 10 shows a thin metal member 110. The thin metal member 100 has a dome-shaped central portion and a planar peripheral flange that corresponds to the dome shape 106 and the sealing surface 107 of the entire end cap 100. The thin metal member 110 is preferably a press formed mild steel pressing which is optionally coated with zinc to have improved chemical resistance. The inserts 115, 120, 125 are formed in the plastic to reinforce the various holes 101, 102, 103 in the end cap 100.

The tube side jaw 101 has an internally threaded insert 115 that is formed in the plastic body of the end cap 100. Figures 6A and 6B show the insert 115. As shown, the insert 115 includes a generally tubular body 116 having internal threads 117 to provide internal threaded connection to the inlet jaw 101. The tubular body 116 has a flanged end 118 and a plurality of axial ribs 119 to assist in securing the insert 115 to the location in the molded plastic body. The insert 115 is preferably made of brass or some other strong, corrosion resistant material.

Similarly, the bleeder plug 103 has an insert 120 that includes a generally tubular body 121 having a threaded inner surface 122. The body 121 also has a flange 123 at one end and, if desired, ribs or other external features to help prevent the insert 120 from moving within the molded plastic. Figures 8A and 8B show the inserts. The insert 120 is preferably made of brass or some other strong, corrosion resistant material.

A reinforcement insert 125 is also provided for the bolt hole 102. 7A and 7B show a plan view and a cross-sectional view of the insert 125. The insert 125 includes a generally tubular body 126 that extends through the bolt bore 102. The insert 125 also has one or more circumferential grooves in the body 126 that can help hold the insert 125 in place in the molded plastic body. The insert 125 is preferably made of metal.

Referring again to Figure 10, the thickness of the dome-shaped metal insert 110 is preferably between 0.5 mm and 3 mm, in this example 1.5 mm thick, and has a bottom flange 111 having a radius of 5 mm, bottom convex The rim 111 corresponds to the sealing surface of the end cap 100 to provide additional support. The flange 111 preferably has a cutout portion 112 to support the threaded hole insert 125. The cutout portion 112 forms a substantially semi-circular insert in the thin metal member 110 that fits into the slot 127 in the insert 125. This enables the force from the bolted connection to be transmitted to the dome-shaped steel member 110 via the bolt hole insert 125, thereby distributing the stress over the entire end cap 100.

The dome member 110 also has an additional cutout portion 113 that corresponds to the position of the tube side jaw insert 115 and the bleed plug insert 120 such that the inserts can protrude through the member 110.

Fig. 9A and Fig. 9B show plan views of the end caps as viewed from the front side and the rear side, respectively, and Figs. 9C and 9D show cross-sectional views taken along lines A-A and B-B. The figures show The position of the various inserts in the plastic body.

Referring to Fig. 9B, the sealing surface 107 is preferably substantially flat, but is slightly outwardly curved in a direction toward the housing 5 in a region 107a between the bolt holes 102. As a result, when the cover 100 is bolted to the casing 5 of the heat exchanger 1, the bent portion 107a abuts against the casing of the heat exchanger 1 to be elastically biased. This helps to form a good seal around the entire perimeter of the end cap 100, particularly in the region of the sealing surface 107 that is further away from the clamping force of the bolt.

To manufacture the end cap 100, the dome-shaped metal member 110 and the five inserts 115, 120, and 125 for the bolt holes, the bleed plug insert, and the tube side raft can be assembled into an injection molding tool, and then The six components are completely covered in a plastic molding (preferably a 50% glass filled nylon) to form the end cap 100. The precision dowels in the injection molding tool are used to secure the bolt hole inserts to improve the accuracy of the bolt hole circle. Additional dowels may be used for the tube side weir inlet insert 115 and the bleed plug insert 120. As noted above, the dome member 110 preferably engages the circumferential groove 127 in the bolt hole insert 125 and thereby is secured in the injection molding tool.

Thereby, an end cap 100 that is relatively simple and inexpensive to manufacture and still has the advantages of using a full naval brass end cap is provided. In particular, a brass connection and preferably a naval brass connection is provided for the beryllium insert 115 and the bleed plug insert 120. This helps to prevent corrosion when seawater is pumped into the tubes of the heat exchanger 1 via such weirs and contributes to providing a strong corrosion resistant threaded connection to the externally threaded connections of the heat exchanger 1. At the same time, the use of relatively expensive brass is minimized. The plastic used for the body of the end cap is reinforced by the press formed steel 110. The press formed steel 110 provides the end cap 100 with rigidity that the plastic itself cannot provide. The end cap 100 can thus be used in high pressure applications (e.g., in the preferred embodiment, operating pressures up to 20 bar and tested over 30 bar) without deflection about the O-ring sealing surface of the housing. a snail that is preferably interlocked with the press-formed steel 110 The configuration of the pinhole insert 125 provides rigidity around the bolt hole clamping portion and distributes stress throughout the end cap 100. Accordingly, the preferred embodiment of the present invention provides an end cap 100 that is low cost and simple to manufacture and that can be used in high pressure, highly corrosive applications, such as in heat exchangers for marine engines or the like.

Embodiments of the invention have been described with particular reference to the illustrated examples. However, it is to be understood that various modifications and refinements can be made to the examples described within the scope of the invention.

100‧‧‧End cover

101‧‧‧ tube side

102‧‧‧Bolt holes

103‧‧‧ venting plug

105‧‧‧Plastic body

115‧‧‧Inlays

120‧‧‧Inlays

125‧‧‧Inlays

Claims (19)

A shell and tube heat exchanger includes a casing and at least one end cover attached to one end of the casing, the end cover comprising: a plastic body or a plastic composite body; and a metal plate member, which is wrapped by the plastic body Covered to provide structural rigidity to the plastic body. The heat exchanger of claim 1 wherein the metal plate extends over a substantial portion of the radial extent of the end cap. The heat exchanger according to claim 1 or 2, wherein the metal plate is formed of a press-formed steel having a zinc coating as needed. The heat exchanger according to any one of claims 1 to 3, wherein the metal plate member has a substantially dome shape, the substantially dome shape having a flange at a periphery thereof, the position of the flange corresponding to the a sealing surface between the end cap and the housing. The heat exchanger according to any one of claims 1 to 4, wherein the end cap has a sealing surface for supporting the housing, the housing having two or more bolt holes for use The end cap is screwed to the housing, wherein the bearing surface is bent between the bolt holes, and the bearing surface bears against the housing when the end cover is screwed to the housing Elastic bias. A heat exchanger according to any of the preceding claims, comprising at least one metal insert adapted to receive and be covered by a plastic body. The heat exchanger of claim 6, wherein the at least one metal insert is a weir member for providing an inlet to the tube side of the heat exchanger. The heat exchanger of claim 7, wherein the weir member has internal threads for connection. A heat exchanger according to claim 7 or 8, wherein at least one of the provided inserts has a threaded connection for receiving a drain plug. The heat exchanger according to any one of claims 6 to 9, wherein the at least one metal insert comprises a metal sleeve having a consistent perforation in one of the end portions of the end cap, wherein one of the threads The fastener clamps the end cap to the housing of the heat exchanger by the metal sleeve. The heat exchanger of claim 10, wherein the at least one metal sleeve is mechanically interlocked with the sheet metal member. The heat exchanger of claim 11, wherein the at least one metal sleeve has a circumferential groove around at least a portion of an outer surface thereof, and wherein the metal plate has at least one cut-away portion at a periphery thereof, the at least one being The cutout is for mechanically interlocking with the circumferential groove. A heat exchanger according to any of the preceding claims, wherein the plastic is overmoulded to the sheet metal member and/or at least one metal insert. A heat exchanger according to any of the preceding claims, wherein the insert is formed from brass. A method of manufacturing a shell and tube heat exchanger according to any of the preceding claims, the method comprising: positioning the sheet metal member in an injection molding tool, and overmolding the plastic to the sheet metal member on. The method of claim 15, wherein the heat exchanger comprises at least one metal insert adapted to receive and be partially covered by the plastic body, the method comprising: Prior to molding the plastic onto the insert and the sheet metal member, the at least one metal insert is positioned on a dowel to precisely position the insert in the injection molding tool. The method of claim 16, wherein the metal insert comprises a plurality of metal sleeves, the metal sleeves providing a plurality of through holes in the bearing portion of the end cap for passage therethrough A plurality of threaded fasteners of the metal sleeve clamp the end cap to the housing of the heat exchanger, the method comprising: mechanically joining the metal sleeve to the metal prior to molding the plastic The board members are interlocked. An end cap for a shell-and-tube heat exchanger, the end cap comprising: a plastic body or a plastic composite body; a metal plate member covered by the plastic body to provide structural rigidity to the plastic body. The end cap of claim 18, comprising the additional features of any one of claims 2 to 14.