This disclosure relates to the shell and plate heat exchanger having a core that is removable from a shell.
The feedwater for steam generators in nuclear power plants is typically preheated before being introduced into the secondary side of the steam generators. Similarly, feedwater is preheated before being introduced into boilers for non-nuclear power plant applications. Conventional shell and tube heat exchangers have been used for decades in nuclear and non-nuclear power plants to preheat feedwater. Such shell and tube exchangers experience degradation over time from tube vibration, flow accelerated corrosion, and loss of efficiency due to plugging of leaking tubes and high fouling rates. Repair or replacement of such equipment is time consuming and expensive.
In at least some implementations, a shell and plate heat exchanger includes a shell and a core. The shell defines at least part of an interior and has a lid and a main body to which the lid is coupled in assembly. The core may be received in the interior and have a plurality of modules. Each module may include a plurality of cassettes of heat transfer plates, and the modules may be releasably coupled together to enable nondestructive decoupling of at least one module from the core. To permit nondestructive removal of the lid from the main body, the lid and main body may be releasable coupled together.
A method of making a heat exchanger may include the steps of:
grouping a plurality of cassettes of heat exchanger plates into a module;
releasably coupling together a plurality of modules into a core; and
releasably mounting the core within the shell to permit nondestructive removal of the core from the shell and nondestructive removal of at least one module from the core. In at least some implementations, the shell includes a body and a lid releasably coupled to the body to define an interior and the core may be mounted to the lid prior to coupling the lid to the body. In this way, the core may be accurately aligned with the body and retained in place within the shell when the lid is coupled to the body.
In at least some forms, the core of the heat exchanger may be removed from the shell, preferably without damaging the shell or the core. The core generally, and/or modules of the core may be cleaned, separated, repaired, rebuilt and/or replaced, and a core may be replaced within the shell for continued use after such operations on any or all of the core modules. The modular construction of the core also facilitates building differently sized heat exchangers, where more modules may be included in a larger core and fewer modules in a smaller core. Of course, the modules need not be of the same size and construction and can vary as desired. For example, the modules may include different numbers of cassettes or plates, if desired, and the modules may have different diameters or shapes, to fit a particular application.
The following detailed description of preferred embodiments and best mode will be set forth with reference to the accompanying drawings, in which:
Referring in more detail to the drawings,
The shell 14 may include a main body 20 and a lid 22 that is connectable to the main body to define an interior or enclosure in which the heat exchanger plates 16 are received. As shown, the lid 22 may be a flat plate adapted to be sealed to the main body, as will be discussed below. The main body 20 and lid 22 may be of any suitable shape and construction to contain the heat exchanger plates 16 and permit desired fluid flows and are not limited to the shape and construction shown in the drawings and further described herein.
In the implementation shown, the main body 20 has a hollow cylindrical sidewall 24, is open at one end 26 and closed at its other end by an end plate 28 to define an open-ended interior 30. The main body 20 may be formed from one or several interconnected pieces of material. As shown in
A first zone 42 (
A second zone 54 (
Either or both of the first and second zones 42, 54 may include level gauges 64 to facilitate determination of fluid levels in these zones. The level gauges 64 may be of any construction and arrangement suitable to provide or enable an indication of fluid level. In the example shown, both the first and second zones 42, 54 include level gauges 64 and both gauges include fluid taps 48, 60 through the sidewall 24, a sight tube 66 (transparent tube in which fluid level can be viewed) and conduit 68 leading from the taps to the sight tubes 66.
The shell 14 may be carried by a base 70 that may include one or more legs 72 coupled to the shell, for example, at or near the flange 36 and end plate 28, as shown. The legs 72 may extend to a floor or base plate 74, and with a base plate, the entire assembly may be unitized and capable of being moved as a unit. For this purpose, lugs 76 or other attachment features may be provided for moving the unit. To facilitate and/or control movement of the core 12 relative to the base 70, as will be described in more detail later, a guide, which may include guide rails 78, tracks or other features, may be associated with the base 70, such as by being connected to or carried by the floor or base plate 74.
The lid 22 and core 12 may be operably coupled to rails 78 for guided movement of the core 12 relative to the main body 20 of the shell 14 to permit insertion and withdrawal of the core 12 from the main body 20. In the implementation shown, the core 12 is connected to a carriage 80 that has an upright support 82 coupled to the lid 22 and a base 84 with a plurality of wheels 86 that roll along the rails 78. The rails 78 may be an inverted v-shape and the wheels 86 may have complementary grooves therein to retain and more precisely guide the carriage movement. Movement of the carriage 80 and an assembly of the lid 22 and core 12 may be achieved manually, or with a powered assist such as an electric, pneumatic or hydraulic mover (e.g. a motor or cylinder). The carriage and guide (e.g. rails 78) may be located outside of the shell, if desired. This may facilitate alteration, cleaning or repair of the carriage and guide without having to disassembly the heat exchanger. Of course, other arrangements of guided movement, linear or otherwise, may be utilized and the above are merely examples of certain possible types. If desired, one or more stops 88 may be provided along or at an end of the rails 78 to limit movement of the core 12 away from the main body 20.
As noted above, the core 12 is coupled to the carriage 80 for movement relative to the shell interior 30 between assembled and disassembled positions. The core 12 can be any suitable heat exchanger core but, as shown, preferably includes a plurality of stacked plates 16. Referring to FIGS. 4 and 6-11, the core 12 may have a plurality of corrugated plates 16 stacked along a longitudinal axis 90. The plates 16 may have any suitable shape and are shown as having a round periphery of a size for receipt within the shell interior 30. In particular, in one implementation the plates 16 are arranged in a group of cassettes 92 defining a cylinder of connected plates, as best shown in
In the example shown, a pair of openings 104 are formed through each plate 16, and the plates 16 are oriented so that the openings 104 define an inlet passage 106 and an outlet passage 108 through the group of cassettes, and through which the working fluid flows. The inlet and outlet passages 106, 108 may also extend through the lid 22 and, if desired, include fittings 107 and 109 received in corresponding openings 111, 113 in the lid. The working fluid inlet, at least in the example shown, may be considered to include one or both of the fitting 107 and opening 111, and the working fluid outlet may likewise be considered to include one or both of the fitting 109 and opening 113.
As best shown in FIGS. 4 and 8-11, a group of cassettes 92 may be at least partially enclosed by end plates 110 located outboard of and overlying the outermost plates 16 and one or more retainers 112 at or over the sides of the plates to define at least part of a plate pack module 114. The end plates 110 may be complementary in shape to the plates 16 and include ports 116 aligned with the openings 104 in the plates 16. The retainers 112 may overlie or cover at least a portion of the plate peripheries and be connected to at least one end plate 110 to maintain the cassettes 92 within the module 114, provide structural support, acts as a fluid flow director/baffle and/or facilitate movement and handling of the module 114 as a single unit. The end plates 110 and retainers 112 may be welded together or otherwise connected permanently or releasably, and the releasable attachment may or may not require breaking a weld or component to release the components. In the implementation shown, the retainers 112 include arcuate sidewall segments that are connected to both end plates and span a portion of the perimeter of the module. One or more straps 118 (
To inhibit or prevent fluid leakage between adjacent end plates, gaskets 122 or other seals may be provided between adjacent plate pack module end plates 110, as shown in
To provide a fluid flow circuit that enables the desired heat exchange between the treatment and working fluids, the core 12 may include one or more than one plate pack module 114, each plate pack module 114 may include any number of cassettes 92, and the modules within a core may have a different number of cassettes, as desired. In the implementation shown in
The modules 114 may be held together by any suitable arrangement, including a permanent or releasable connection. In the implementation shown, adjacent modules 114 are releasably coupled by fasteners 126 (
In this way, the plate pack modules 114 are carried by the lid 22 and move with the lid and its carriage 80 as shown by comparison of
Referring to
In the implementation shown, each diverter 140 includes two circumferentially spaced apart flanges 144, one at each edge of the wall 142, although other arrangements may be used. Also in the implementation shown, two such diverters 140 are provided, generally evenly spaced about the periphery of the core 12. The flanges 144, or other portion of a diverter 140 may be coupled to one or both clamping plates 130, 132. In the implementation shown, the clamping plates 130, 132 include shoulders 148 (
To further limit or prevent fluid from flowing all the way around a flow diverter 140, between the flow diverter 140 and the shell 14, one or more seals 151 may be disposed adjacent to and extending radially outwardly from the flow diverter walls 142. The seals 151 may extend axially between the lid 22 and second clamping plate 132 or divider plate 32, and may engage the shell sidewall 24 to prevent or substantially inhibit fluid flow past the seals 151. This further promotes fluid flow into the plate pack modules 114 rather than around the periphery of the plate pack modules 114. The seals 151 may be flexible and resilient such that at least part of the seals is resiliently bent or flexed upon engagement with the shell 14 to ensure good contact and a good seal between them. This arrangement may also provide a reactionary force that holds the diverters 140 more tightly against the clamping plates 130, 132 to inhibit or prevent fluid flow between the diverter and clamping plates. If desired, a seal may be located between the diverters and clamping plates. The diverters 140 and/or seals 151 may also act as guides for the core 12 during installation of the core 12 into the shell 14.
In addition to the flow diverters 140 and seals 151, at least when two treatment fluids are provided, the core 12 may include a structure, shown as a baffle plate 152 (
As shown in
Accordingly, partitioned fluid flow into and through the core 12 may be provided between two treatment fluids. In the example of a heat exchanger for a feedwater heater, a first treatment fluid may include steam and a second treatment fluid may include condensate from an upstream heat exchanger that is at an elevated temperature. The condensate from the upstream heat exchanger may be at a higher temperature than the working fluid so that heat transfer from that second treatment fluid to the working fluid is beneficial and more efficient than not using the second treatment fluid at all and wasting its heat. However, it may be desirable to keep the steam (first treatment fluid) separate from the second treatment fluid so that heat from the first treatment fluid is not wasted in heating the second treatment fluid and is instead primarily used to heat the working fluid. The number of plates or plate pack modules 114 devoted to each treatment fluid may be determined based on the relative volume of the fluids entering the fluid inlets, or otherwise, as desired. While a 2:1 ratio of plates/modules has been shown and described, any ratio may be used (e.g. 8:1, 100:1 or more). The treatment fluids may be maintained separate throughout their flow paths in the heat exchanger 10, or the treatment fluids may be combined within the heat exchanger 10. In the implementation shown, the treatment fluids are combined near a bottom of the heat exchanger 10 and both fluids flow out of a common outlet 56.
To assemble the heat exchanger 10, the core 12 is connected to the lid such as by connecting the modules to the first clamping plate 130 via the tie rods 134 and second clamping plate 132. The core and lid assembly is then advanced via the carriage 80 and rails 78 until the core 12 is received within the shell interior 30 and the lid 22 engages the shell flange 36. The lid 22 and flange 36 are releasably coupled together, such as by nuts and bolts 160 as shown, or in any other suitable manner. In reverse order, the core 12 may be removed from the shell 14 to permit cleaning, repair or replacement of any part of or all of the core 12 and its components or the shell 14, and access to the interior of the shell and its internal features or components. The carriage 80 and rails 78 provide controlled, guided movement of the core 12 relative to the shell 14 to facilitate insertion and withdrawal of the core without damaging the heat exchanger components.
Further, in at least certain implementations, the partitioned fluid flow paths are automatically created when the core 12 itself is assembled and when the core is assembled into the shell 14, and all seals 151 and flow directors 140 are in proper position without requiring further or separate handling or manipulation such as connection of tubes, headers or the like. This may be accomplished, for example without limitation, but disposing the baffle flange 52 and baffle plate 152 at an angle not parallel to the path of movement of the core as it is inserted into the shell. As shown, the baffle flange 52 and baffle plate 152 seal at an interface that is perpendicular to the path of movement (and the path of movement in this example is parallel to the longitudinal axis 90). This is also true for the lid 22 to flange 36 seal interface. Of course, other angles can be used. Likewise, the seals between adjacent modules 114 in the core 12, are due to surface-to-surface engagement when the core is assembled and do not require separate connection of tubes, or connection of the modules to a tube or header or the like. And the same is true for the sealed connection between the lid 22 and core 12 which is created by surface-to-surface contact between the clamping plate 130 and the lid 22 when the clamping plate and/or core is coupled to the lid. In this way, when the lid 22 is removed from the main body 20, the core 12 can be easily removed from the shell interior 30 without having to decouple tubes, headers or the like.
When the core 12 is removed from the shell 14, in at least certain embodiments, the core may be completely disassembled for repair, cleaning or replacement of some or all parts. And removal of the core from the shell as well as disassembly of the core can be accomplished nondestructively, which is to say that components or connections between components need not be broken, cut or otherwise altered (e.g. bending, breaking or cutting a weld or component, severing a seam or adhesive/chemical bond, or any other separation process that requires replacing one or more components, connection features or servicing of any components to render them suitable for use again after separation). In this way, the components can be reassembled with minimal additional effort (in at least some applications, it may be desirable to replace at least certain gaskets with new gaskets), and due to the modular nature of the components, they may be readily exchanged for other components as desired. As described and shown, fasteners connect together the lid 22 and main body 20 of the shell 14, fasteners hold the plate pack modules 114 together via the mounting tabs 120, clamping plates 130, 132 and tie rods 134, and fasteners retain the diverters 140 to the clamping plates 130, 132 or other core component(s). All of these fasteners are removable and may be reused (or replaced with like fasteners, if desired) to facilitate assembly and disassembly of the heat exchanger 10 and provide increased utility and versatility in use.
When assembled, the heat exchanger 10 provides fluid flow paths for the treatment fluid and working fluid(s) that are adjacent to each other and separated by the heat transfer plates 16 or other components through which heat may be exchanged/transferred. In this way, heat from the treatment fluid(s) is transferred to the working fluid to increase the temperature of the working fluid. In other implementations, it may be desirable to reduce the temperature of a treatment fluid and this may be done by providing working fluid(s) at an inlet temperature that is less than the inlet temperature of the treatment fluid.
In the implementation shown, the working fluid enters the heat exchanger 10 through its inlet fitting 107 which is located below its outlet fitting 109. The flow path for the working fluid is defined by includes internal passages 102 of the core 12 that open inwardly toward the inlet and outlet passages 106, 108 in the plate pack modules 114 and fluid generally flows from the bottom of the heat exchanger 10 to the top of the heat exchanger 10 in that flow path. Conversely, the treatment fluid inlets 44, 46 are provided at the top of the heat exchanger 10 and flow from the top toward the bottom of the heat exchanger 10. The treatment fluid flow paths originate between the shell 14 and the core 12 and flow through the core 12 in flow passages 103 open to the shell 14 (that is, the gap between the shell and core periphery) and typically alternate or are interleaved with the passages for the working fluid. This provides a counterflow between the working and treatment fluids within the heat exchanger 10 that more effectively transfers heat between the fluids, at least in certain heat exchangers.
To provide even greater surface area for the heat transfer fluid flows, a greater number of plates/plate pack modules 114 may be used. Additionally, as shown in
In the embodiment of
Accordingly, heat exchangers have been described that include a shell and a core. The shell defines an interior and includes a lid and a main body to which the lid is coupled in assembly. The core is received in the shell interior and has a plurality of modules, each module including a plurality of cassettes of heat transfer plates, and the modules being releasably coupled together to enable nondestructive decoupling of at least one module from the core. Further, the lid and main body may be releasably coupled together to permit nondestructive removal of the lid from the main body. In this way, the heat exchanger components can be readily assembled and disassembled, serviced, cleaned or replaced, and then reassembled for further use. In some implementations, the core may be carried by the lid so that the core is assembled into the interior when the lid is coupled to the main body. Additionally, all fluid paths and partitions may be fully positioned and operational by merely coupling the lid to the main body, and without having to manually or by another process make fluid connections (e.g. between the core and conduits or headers) within the shell interior.
A representative method of assembling such heat exchangers may involve grouping a plurality of cassettes of heat exchanger plates into a module, releasably coupling together a plurality of modules into a core, and releasably mounting the core within the shell to permit nondestructive removal of the core from the shell and nondestructive removal of at least one module from the core. In at least some implementations, the core may be assembled to the lid and then the lid with the core thereon may be assembled to the main body. When the lid includes a fluid port for admission of fluid into the shell interior and the core includes a passage aligned with the fluid port to receive fluid into the core, surface-to-surface contact of planar surfaces of the core and lid may provide a fluid tight seal between the fluid port and passage. An example of this is shown in
While the forms of the invention herein disclosed constitute presently preferred embodiments, many others are possible. For example, without limitation, the fluid flows can be reversed so that the described outlets become inlets and the described inlets function as outlets. Further, the working fluid could be routed through a flow path described with regard to a treatment fluid, and vice versa. It is not intended herein to mention all the possible equivalent forms or ramifications of the invention. It is understood that the terms used herein are merely descriptive, rather than limiting, and that various changes may be made without departing from the spirit or scope of the invention. Terms like “radially”, “axially” and “circumferentially” are used with reference to an axis of the core and/or shell interior. In instances where the shell and/or core are not generally round/circular, “axially” may be taken to mean parallel to the direction of insertion of the core into the shell, “radially” may be taken to mean perpendicular to “axially” and “circumferentially” can be taken to mean a dimension or direction taken from a given radial distance from an axis, plane or other reference point. Finally, terms like above, below, top and bottom refer to the orientation of the device as shown in the drawings with the understanding that a heat exchanger may be used in a different orientation and this description applies equally to all possible orientations.
This application claims the benefit of U.S. Provisional Application No. 61/902,548 filed Nov. 11, 2013, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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61902548 | Nov 2013 | US |