This application claims foreign priority benefits under 35 U.S.C. § 119 to Danish Patent Application No. PA201901288 filed on Nov. 4, 2019, the content of which is hereby incorporated by reference in its entirety.
The present invention relates to a plate-and-shell heat exchanger and a channel blocking plate for a plate-and-shell heat exchanger.
Plate-and-shell heat exchangers comprise a plurality of stacked structured plates positioned within a shell or casing. The plates are connected in pairs such that a first fluid flow path for a first fluid is provided at least partially within the connected pairs of plates. The pairs of connected plates are designed to fluidly connect a first inlet opening to a first outlet opening of the heat exchanger, thereby forming the first fluid flow path. A second fluid flow path for a second fluid is provided outside of the connected pairs of plates and separated from the first fluid flow path by the plates. The second fluid flow path fluidly connects a second inlet opening to a second outlet opening.
The second fluid enters the shell of the heat exchanger through the second inlet opening and it flows along the complex second fluid flow path inside the shell and out through the second outlet opening. A part of the second fluid bypasses central regions of the heat transfer plates and flows from the second inlet opening to the second outlet opening along radially exterior peripheral regions of the heat transfer plates. This is due to the flow resistance being lower at the peripheral regions than at the central regions of the heat transfer plates. This bypassing of the central regions of the heat transfer plates results in a detrimental distribution of the second fluid and therefore in a problematic suboptimal heat transfer rate.
This problem is solved by the present invention's heat exchanger according to claim 1 and by a channel blocking plate for a heat exchanger according to claim 10. Further embodiments of the invention are subject of the dependent claims.
According to the first claim, a plate-and-shell heat exchanger is provided, which comprises a shell and a plurality of heat transfer plates within the shell. The shell and the plates may be of any shape, but a cylindrical or circular shape of the shell and the plates is preferred. The plates form fluidly connected first cavities for providing a first fluid flow path for a first fluid flow. The shell forms a second cavity in which the plates are arranged and a second fluid flow path is provided for a second fluid flow separated from the first fluid flow path by the plates. Two adjacent plates are connected to form an enclosed volume such that a first cavity is provided between them.
According to the invention, at least one channel blocking plate is provided between at least some of the plates and the shell, said channel blocking plate comprising a plurality of protrusions extending in a direction radially inwards of the shell and reaching between two adjacent plates.
The protrusions reach into the second fluid flow path and pose as an obstacle or barrier to the second fluid flow in a radially exterior peripheral region of the heat transfer plates. The second fluid flow is thus directed away from the radially exterior peripheral region and towards the central region of the heat transfer plates. The present invention therefore solves the bypass problem and helps increasing the heat transfer rate of the heat exchanger.
In a preferred embodiment the channel blocking plate extends over 60° ±30°, in particular ±15°, in a circumferential direction of the shell. In another embodiment, the channel blocking plate may extend over 60°±5° in a circumferential direction of the shell. As the channel blocking plate extends not all way around the heat transfer plates, it allows for sufficient distribution of the second flow between the heat transfer plates while at the same time limiting or blocking any undesired bypass flows.
The channel blocking plate may extend along the entire inner length of the shell in an axial direction of the shell and/or the channel blocking plate may comprise a plurality of separated, preferably identical, sub-plates. The channel blocking plate may be curved such that it aligns with the curvature of the shell and the curvature of the outside edges of the heat transfer plates. The channel blocking plate may be press-fit, welded or otherwise connected to the heat transfer plates. Alternatively, a loose fit may be provided between the channel blocking plate and the heat transfer plates for ease of manufacture and assembly.
In another preferred embodiment at least two channel blocking plates are provided which are positioned opposite each other with respect to a central axis of the shell. The two channel blocking plates may thus be spaced apart by 180° around the longitudinal axis of the shell. Such an arrangement of the channel blocking plates provides a simple way of blocking undesired bypass flows through the heat exchanger.
In another preferred embodiment the protrusions are formed by bent cuts. The channel blocking plate may be made of a sheet metal into which a plurality of cuts has been introduced. The cut areas may then be bent by about 90° to create the protrusion. For fitting the channel blocking plate between the shell and the heat transfer plates it may be bent as a whole, such that its curvature matches the curvature of the shell and the heat transfer plates.
In another preferred embodiment a sealing plate is positioned radially outwards of the channel blocking plate for sealing openings in the channel blocking plate, wherein the sealing plate is preferably held tight against the channel blocking plate by means of a spring mechanism. The sealing plate may be made from a sheet metal or from a synthetic material. The spring mechanism may be an elastic and/or synthetic component which is positioned between the shell and the sealing plate. The spring mechanism may be formed integrally with the sealing plate. In particular, the sealing plate may be made from a bent sheet metal. The sealing plate and/or the spring mechanism may be compressed upon insertion between the shell and the channel blocking plate, thus providing a force acting on the channel blocking plate and sealing the openings in the channel blocking plate.
In another preferred embodiment the protrusions on the at least one channel blocking plate are arranged shifted to each other and/or are arranged in parallel lines and/or the shapes of the protrusions match the shapes of the spaces between two adjacent plates. The shifted arrangement of the protrusions ensures that the distances between adjacent protrusions are sufficiently large to provide structural support during e.g. the manufacture of the channel blocking plate.
The arrangement of the protrusions in parallel lines which are parallel to the longitudinal axis of the shell facilitates the bending of the channel blocking plate for adapting its shape to the curvature of the shell and of the heat transfer plates.
Two adjacent protrusions which are spaced apart from each other in an axial direction of the shell may be spaced apart such that four radially most outward portions of four heat transfer plates are positioned between them. When manufacturing the channel blocking plate, the shape of the cuts can be chosen so as to create a close fit between the protrusions and the heat transfer plates. By doing so, the gap between the protrusions and the heat transfer plates can be minimized, thereby minimizing the undesired bypass fluid flow.
In another preferred embodiment at least two channel blocking plates are provided which are spaced apart from each other in an axial direction of the shell, and which preferably are at least partially separated and/or surrounded by radially extending support structures and/or axially extending support structures.
In another preferred embodiment the protrusions comprise a rectangular portion and a tapered portion, wherein the tapered portion is positioned radially more inwards of the rectangular portion. The rectangular portion of the protrusion is designed to fit closely to the radially most outward portions of the heat transfer plates. These radially most outward portions of the heat transfer plates may be aligned in parallel to each other and perpendicular to the longitudinal axis of the shell. The tapered portions of the protrusions are designed to fit closely to a radially more inward portion of the heat transfer plates. The radially more inward portion of the heat transfer plates may be at an angle to the radially most outward portion of the heat transfer plate, thereby necessitating an accordingly tapered shape of the protrusion. In a particularly preferred embodiment, the tapered portion is a triangular, arched or circular portion.
The present invention also relates to a channel blocking plate for a plate-and-shell heat exchanger according to any of claims 1 to 9. The channel blocking plate may feature any or all of the characteristics described above with respect to the heat exchanger and the corresponding channel blocking plate.
Further details and advantages of the invention are described with reference to the following figures:
1
a: an exploded view of a plate-and-shell heat exchanger;
1
b: a sectional schematic view of a plate-and-shell heat exchanger;
2
a: a detailed view of a heat transfer plate of a plate-and-shell heat exchanger;
2
b: a detailed sectional view of a plurality of connected heat transfer plates;
3
a: a schematic view of a first fluid flow path through the heat exchanger;
3
b: a schematic view of a second fluid flow path through the heat exchanger;
4
a: a detailed view of a partially manufactured channel blocking plate of the heat exchanger;
4
b: another detailed view of a partially manufactured channel blocking plate;
4
c: a partially assembled heat exchanger with visible channel blocking plates;
5
a: a sectional view of a channel blocking plate positioned between heat transfer plates and a shell of the heat exchanger; and
5
b: a sectional view showing the positioning of the channel blocking plates within the heat exchanger.
The shell 20 may be of a hollow cylindrical shape and the plates 10 may be of a corresponding shape and size such that they can be fit into the shell 20. Other shapes of the shell 20 and plates 10 are also possible, however shapes are preferred, which allow for close positioning of the plates 10 to the shell 20.
The plates 10 form fluidly connected first cavities 11 for providing a first fluid flow path 12 for a first fluid flow indicated by the corresponding arrows. The first fluid flow enters and leaves the heat exchanger through first inlet and outlet openings 23, 23′. The first cavities 11 are surrounded by two adjacent plates 10, which are connected to each other, as is shown more clearly in
The plates 10 are connected e.g. by welding or brazing at their rims in pairs, two and two, forming first cavities 11 for a sealed first fluid flow path 12 from a first inlet opening 23 to a first outlet opening 23′. A plurality of such stacks are stacked and e.g. welded or brazed around the first inlet and outlet openings 23, 23′. The connected first inlet and outlet openings 23, 23′ form hollow volumes such as e.g. hollow cylinders reaching through the stack to distribute and circulate a first fluid through the sealed first fluid flow path 12. The second fluid flow path 22 formed outside of the sealed pairs of plates 10 and inside of the shell 20 is connected to second inlet and outlet openings 24, 24′. A second fluid flow enters and leaves the heat exchanger 100 through second inlet and outlet openings 24, 24′.
The shell 20 forms a second cavity 21 in which the plates 10 are arranged and in which a second fluid flow path 22 for a second fluid flow is provided. The second fluid flow enters and leaves the heat exchanger 100 through second inlet and outlet openings 24, 24′. The second fluid flow path 22 is separated from the first fluid flow path 12 by the plates 10. The heat exchange occurs between the two fluids flowing separated from each other by the plates 10.
The plates 10 may comprise plate openings 13 for connecting fluidly adjacent plates 10 to each other and to the first inlet and outlet opening 23, 23′. Two adjacent plates 10 may be connected and sealed together by e.g. a welding or brazing along the edge of the plate opening 13 and/or along the outer perimeter of the two plates 10.
The second fluid flow path 22 is guided between two adjacent pairs of connected plates 10 and separated from the first fluid flow path 12 by the plates 10. It comprises flat, narrow channels between closely positioned plates 10. For efficient heat exchange, the second fluid flow rate in the vertical direction and between the pairs of connected plates 10 as shown in
As can be seen in
The second fluid flow path 22 fills the second cavity 21. The second cavity 21 is bounded by the inside of the shell 20, the outsides of the pairs of connected plates 10, one of which is shown in
A part of the second flow passes in a mostly radial direction between the two second openings 24, 24′. However, as the bypass cavity 15 is present at the outer circumference of the second cavity 21, another part of the second flow passes in a mostly circumferential direction between the two second openings 24, 24′ and without entering the narrow space between two adjacent pairs of connected plates 10. Therefore, at the edges of the plates 10, where the connected pairs of plates 10 are connected and/or welded and/or brazed, the undesired bypass for the second fluid flow is formed, which reduces the overall efficiency of the heat exchanger 100.
The channel blocking plate 30 comprises a plurality of protrusions 31, extending in a direction radially inwards of the shell 20. Although the channel blocking plate 30 of
As can be seen in
The protrusions 31 may be arranged shifted to each other and/or may be arranged in parallel lines on the channel blocking plate 30 as shown in
The shapes of the protrusions 31 may be designed to match the shapes of the spaces between two adjacent plates 10. The protrusions 31 may comprise a rectangular portion 311 and a tapered portion 312. In a state shown in
The tapered portion 312 may comprise triangular, arched and/or circular sub-portions, such that the whole protrusions align as closely as possible to the plates 10 adjacent to it.
The embodiment of
As is also shown in
The channel blocking plates 30 may stretch over 60° ±30° or ±15° in a circumferential direction of the shell 20. The areas beyond those covered by the channel blocking plates 30 can be left free for the second fluid flow to pass between the second inlet and outlet openings 24, 24′ shown in
The channel blocking plate 30 may extend along the entire inner length of the shell 20 in an axial direction of the shell 20. This corresponds to the channel blocking plate 30 of
The channel blocking plates 30 visible in
The protrusions shown in
The heat exchanger 100 may comprise one or more sealing plates 50 which may be positioned radially outwards of the channel blocking plate 30 for reducing or eliminating undesired fluid flow through or past the channel blocking plate 30. The sealing plates 50 may be compressed between the inside of the shell 20 (not shown in
The sealing plate 50 may comprise a radially inwards sealing portion which fits snugly onto the radially outward side of the channel blocking plate 30. One or more separation portions may be connected to the sealing portion, said separation portions extending in a radial direction and away from the sealing portion. One or more spring portions may be connected to the separation portions. The spring portion of the sealing plate may be the spring mechanism for pressing the sealing plate 50 against the channel blocking plate.
The spring portions may be positioned at an angle with respect to the separation portion and may be designed to be deformed upon insertion into the shell 20. The deformation of the spring portion results in a force pushing the sealing plate 50 on the channel blocking plate 30, thereby sealing at least some of the leakage occurring past the channel blocking plate 30.
The sealing plate 50 may be smaller than the channel blocking plate 30. In particular, the sealing plate 50 may be dimensioned such that the channel blocking plate 30 may be two, three or more times wider in a circumferential direction than a single sealing plate 50. Smaller sealing plates 50 and a corresponding higher number of sealing plates and spring mechanisms make it possible to exert a more uniform cross on the channel blocking plate 30, thereby improving the sealing function of the sealing plate 50.
The invention is not limited to the above-mentioned embodiments but may be varied in manifold ways. In particular, features of the above-mentioned embodiments may be combined in any logically possible manner. All features and advantages including construction details and spatial configurations, which are disclosed in the claims, in the description and in the figures, may be essential to the invention, both, individually and in combination with each other.
Number | Date | Country | Kind |
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PA201901288 | Nov 2019 | DK | national |