Patent Grant
6866093
The present invention is generally directed to heat exchangers, and more particularly to a method and apparatus utilizing isolation and flow direction/control plates for a shell and tube type heat exchanger.
Heating and cooling systems often contain a variety of heat exchangers for heating and cooling of liquids and gases, e.g. water, steam and/or air. In general, the various types of heat exchangers may be broken down into three main categories: Shell and Tube Heat Exchangers, Plate and Frame Heat Exchangers, and Air Coils.
Shell and Tube Heat Exchangers are the most common type of heat exchanger found in the background art. Normally, a bundle(s) of tubes is (are) enclosed within an outer shell. The tubes are joined to a tubesheet that prevents a fluid contained within the tube-side of the heat exchanger from becoming contaminated with a fluid contained in the shell side of the heat exchanger. Heat transfer is typically conducted across the tube walls separating the two fluids.
Baffle plates are commonly used to hold the tube bundles in their desired positions. The baffle plates will also serve the function of directing the shell side fluid across the exterior of the tube walls in order to achieve efficient heat transfer. The fluid passing within the tubes may make several passes through the heat exchanger in a common U-type arrangement involving U-shaped tube bundles and end plates/headers, or may make only a single pass through the heat exchanger.
The use of baffle plates on the shell side of heat exchangers has been in existence for many years. These baffle plate arrangements may utilize circular plates fitted within the shell enclosure that additionally have holes cut within the surface of the plate to secure the tubes that pass therethrough.
The baffle arrangement shown in
Depending on the arrangement desired in the heat exchanger, the resulting shell side fluid flow can be either parallel flow (in parallel with and in the same flow direction of tube side flows), counterflow (in parallel with but counter to the flow direction of tube side flows), or cross-flow (tangential or normal to the direction of tube side flows). As seen in
A first tube side flow path is defined by and extends from, as viewed from left to right in
One shell and tube type heat exchanger is currently used for the cooling of CVD/CVI furnaces. This type of heat exchanger may have multiple banks of heat exchangers with several tube side fluid inlets and tube side fluid outlets. The heat exchanger may also have a turbine installed in the same heat exchanger housing that draws upon fluid leaving the shell side fluid outlet of the heat exchanger. The heat exchanger may even be separated from the turbine inlet using a circular baffle plate, e.g. having a hole in the center of the plate for permitting controlled flow to the turbine inlet.
However, this type of arrangement does not permit isolation or control of the individual banks of heat exchangers when multiple tube banks are utilized in the heat exchanger.
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
The present invention, in part, is a recognition that it will be advantageous to direct and control heat exchanger cross-flow on the shell side between small heat exchangers in a multi-bank heat exchanger arrangement.
The present invention, in part, is a recognition that it is desirable to control and balance pressure drops across both shell and tube side flows of a heat exchanger.
The present invention, in part, provides a heat exchanger assembly comprising a shell; a plurality of tubes; a shell side fluid inlet; a shell side fluid outlet; at least one tube side fluid inlet; at least one tube side fluid outlet; and at least one isolation and flow direction control plate positioned in the shell of the heat exchanger assembly for creating a plurality of smaller heat exchangers, each of said isolation and flow direction control plates including at least one fluid slot for permitting a passage of a shell side fluid flow through said isolation and flow direction control plate.
The present invention, also in part, provides a method of controlling a fluid flow for a heat exchanger assembly comprising creating a plurality of smaller heat exchangers by providing at least one isolation and flow direction control plate in a shell side of the heat exchanger assembly; and isolating and directing the fluid flow on the shell side of the heat exchanger assembly between each of said smaller heat exchangers.
The present invention, also in part, provides an isolation and flow direction control plate for controlling fluid flow on a shell side of a shell and tube heat exchanger comprising a base plate; and at least one fluid slot for permitting a passage of a shell side fluid flow through said isolation and flow direction control plate.
Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinafter and the accompanying drawings which are given by way of illustration only, and thus do not limit the present invention.
FIG. 6(a) is an enlarged view of a portion of first isolation and flow direction control plate shown in
FIG. 6(b) is an enlarged view of a portion of second isolation and flow direction control plate shown in
FIG. 6(c) is an enlarged view of a portion of third isolation and flow direction control plate shown in FIG. 5.
The present invention will now be described in detail with reference to the accompanying drawings.
A first isolation and flow direction control plate 40, a second isolation and flow direction plate 41 and a third isolation and flow direction control plate 42 are provided in the embodiment shown in FIG. 4 and FIG. 5. However, one of skill in the art will appreciate that the number of IFDC plates 40, 41, 42 can be increased or decreased in order to form alternative (more or less, respectively) multiples of heat exchangers 50 and in accordance with the desired control of shell side fluid path.
As seen in FIG. 6(a) through FIG. 6(c), each of the IFDC plates 40, 41, 42 is provided with a rectangular fluid slot 45 positioned in a portion, e.g. at various heights or levels, of each respective IFDC plate. This deliberate positioning of the rectangular slots 45 permits a controlled introduction of shell side fluid flow to a successive heat exchanger 50. The rectangular fluid slots 45 are individually sized and positioned to achieve a desired pressure drop, extend or retard the period of time available for heat transfer in each individual heat exchanger 50, and to control the direction or point of introduction of shell side fluid flow to each successive heat exchanger 50.
In contrast to the semi-circular or circular baffle plates 30 of the background art having tubular holes 35 for engaging tubes 21 of a heat exchanger, the present invention utilizes a series of IFDC plates 40, 41, 42 having rectangular fluid slots 45 that permit greater control over the shell side fluid flow. As seen in FIG. 6(c), IFDC plates 42 can also be provided with a plurality of rectangular slots 45, including alternatively sized rectangular slots 46. The alternatively sized rectangular slots 46 can be larger or smaller based on desired heat transfer effects and acceptable pressure losses.
As seen in FIG. 4 through
Materials for the IFDC plates 40, 41, 42 of the present invention can be virtually any material suitable for baffle plates 30 of the background art. Some exemplary materials are various arrangements of CuNi, Bronze, Steel (including, but not limited to stainless steel, forged and/or cast steel), and Titanium. The IFDC plates and their respective fluid slots 45, 46 can be machined, cast or forged.
Although the fluid slots 45 are depicted as being rectangular in shape, other shapes can be readily incorporated into the present embodiments, including but not limiting to triangular, trapezoidal, circular, or other polygonal slot shapes permitting sufficient flow control (e.g., area of slot, pressure drop, location/positioning of slot on IFDC plate).
One of skill in the art will appreciate that the actual heat exchanger design will vary depending upon the types and quantities of fluids/systems involved, e.g. type of fluid, viscosity, thermal conductivity, etc . . . , system temperatures and pressures, allowable pressure drops, weight and material considerations and preferences, and/or fouling factor/flow resistance considerations. Further, several additional industry technical standards and/or codes may govern the applicable commercial use, design or implementation of heat exchangers incorporating the present invention.
A method according to the present invention will now be described with reference to the accompanying drawings and foregoing description of FIGS. 3-6(c). The present invention is directed toward a method of controlling and isolating shell side fluid in a heat exchanger(s), particularly in a cross flow type shell and tube heat exchanger.
One of skill in the art will appreciate that the IFDC plates of the present invention can be incorporated during the initial design and manufacture of a heat exchanger assembly 1, however, it will also be possible to retrofit or upgrade an existing heat exchanger assembly with IFDC plates to create a series of smaller, heat exchangers.
In general, the method of controlling a fluid flow for a heat exchanger assembly 1 includes creating a plurality of smaller heat exchangers 50 by providing at least one isolation and flow direction control plate 40 in a shell side 22, 23 of the heat exchanger assembly 1 and isolating and directing the fluid flow on the shell side of the heat exchanger assembly 1 between each of the smaller heat exchangers 50. In a preferred embodiment, the heat exchanger assembly is a shell and tube heat exchanger assembly 1, however it will be possible to incorporate the present invention into other types of heat exchanger designs.
Each of the isolation and flow direction control plates includes at least one fluid slot for permitting the fluid flow to pass through each of the isolation and flow direction control plates. Although the slots are rectangular slots in a preferred embodiment, as aforementioned, other shapes can be incorporated into the present invention. Further, a designer may wish to vary a period of time or residence time during which the fluid flow on the shell side 22, 23 of the heat exchanger assembly 1 resides in the smaller heat exchangers 50. This can be accomplished by the sizing and positioning of each of the IFDC plates 40, 41, 42.
As aforementioned, one of the design considerations with respect to the isolation and flow direction control plates 40, 41, 42 is a balance between effective heat transfer and acceptable pressure losses. One of skill in the art will appreciate that pressure drop considerations on both the shell and tube side of the heat exchanger will significantly impact heat exchanger sizing, required pumping capacity and will often be a necessary design tradeoff between idealized heat transfer rates, or more specifically, a desirable heat transfer film coefficient. The film coefficient may be influenced by such factors as fluid velocity, material selection and fluid tube diameter.
Tube side pressure drops are the realized pressure losses experienced across the tube side fluid inlet 22 and the tube side fluid outlet 23. These losses may be associated with pressure losses due to flow acceleration, deceleration, changes in direction, or frictional pressure losses (scaling or tube material).
Shell side pressure drops are the realized pressure losses experienced across the shell side fluid inlet 11 and the shell side fluid outlet 12. These pressure losses may be associated with fluid velocity (flow acceleration and deceleration), pressure loss coefficients for each of the fluid slots 45 of the IFDC plates 40, 41, 42, pressure loss coefficients due to flow area expansion and contraction and flow redirection, tube geometry (pitch, length and diameter), and fluid characteristics.
When either of the shell side or tube side fluid flows are subdivided with the use of the IFDC plates of the present invention, the total or sum of the individual shell or tube side pressure drops in each of the individual shell/tube stages will be the total realized pressure losses. One of skill in the art will appreciate that the pressure loss coefficients for each of the fluid slots 45 and IFDC plates 40, 41, 42 will vary depending on the surface area of each of the slots 45 or plates. Further, the shape and edges of the slots 45 may be chamfered, angled or arcuately shaped in order to prevent flow erosion and smoother flow transitions.
Accordingly, the method and apparatus of the present invention further includes calculating a plurality of acceptable pressure losses through each of the smaller heat exchangers; and sizing the isolation and flow direction control plates to permit fluid flow within the calculated acceptable pressure losses.
Further examples of suitable and applicable materials, heat exchanger design considerations and steps, such as the use of either of LMTD (Log Mean Temperature Difference) or NTU (Number of Transfer Units) Methods, modeling software and iterative solvers, and potential applications of the present invention are described in the many of the standards of the Tubular Exchanger Manufacturers Association, particularly the “Standards of the Tubular Exchanger Manufacturers Association, 8th Edition (July 1999),” and the American Society of Mechanical Engineers; the entirety of each of which is hereby incorporated by reference. As such, the actual configurations shown in the accompanying figures are presented by way of example, and are not intended to limit the invention to the specific arrangement(s) presented.
This application claims priority on U.S. Provisional Application for “Isolation and Flow Direction/Control Plates of a Heat Exchanger,” [No. 60/268,295 application No.] filed on Feb. 13, 2001, the entire contents of which are hereby incorporated by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 79931 | Agate | Jul 1868 | A |
| 1289350 | Zimmermann | Dec 1918 | A |
| 1401717 | Halleck | Dec 1921 | A |
| 1489932 | Dickey | Apr 1924 | A |
| 1979975 | Maniscalco | Nov 1934 | A |
| 2147719 | Simons | Feb 1939 | A |
| 2424795 | Burns | Jul 1947 | A |
| 2530443 | Walker | Nov 1950 | A |
| 3679194 | Jones | Jul 1972 | A |
| 3724212 | Bell | Apr 1973 | A |
| 3735811 | Moser et al. | May 1973 | A |
| 3942589 | Opitzer | Mar 1976 | A |
| 4016929 | Pfluger et al. | Apr 1977 | A |
| 4114684 | Jenis et al. | Sep 1978 | A |
| 4293755 | Hill | Oct 1981 | A |
| 4357214 | La Mori et al. | Nov 1982 | A |
| 4630669 | Kessler | Dec 1986 | A |
| 4642149 | Harper | Feb 1987 | A |
| 4744368 | Brien | May 1988 | A |
| 4753192 | Goldsmith | Jun 1988 | A |
| 4802441 | Waugh | Feb 1989 | A |
| 5261963 | Basta | Nov 1993 | A |
| 5645694 | Stewart et al. | Jul 1997 | A |
| 5782980 | Allen | Jul 1998 | A |
| 5814192 | Pittmon et al. | Sep 1998 | A |
| 5819683 | Ikeda | Oct 1998 | A |
| 6099649 | Schmitt | Aug 2000 | A |
| Number | Date | Country |
|---|---|---|
| 572169 | Sep 1945 | GB |
| Number | Date | Country | |
|---|---|---|---|
| 20020108741 A1 | Aug 2002 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60268295 | Feb 2001 | US |
