ASSEMBLY OF HEAT TRANSFER ELEMENT FOR ROTARY REGENERATIVE AIR PREHEATER

FIELD OF INVENTION:
[001] The present subject matter described herein, relates to a heat transfer element, and, in particular, to an assembly of heat transfer element for a rotary regenerative air-preheater in thermal power station/industrial applications wherein the sensible heat is transferred by means of the heat transfer plates from hot heat exchange fluid to cold air or gases.
BACKGROUND AND PRIOR ART:
[002] Generally, one type of heat exchange apparatus to which the present invention has a particular application is a well-known rotary regenerative air-preheater. A typical rotary regenerative air-preheater transfers the sensible heat from the flue gas leaving a boiler/furnace to entering combustion air through a regenerative heat transfer surface in a rotor which turns continuously through air and gas streams. The air-preheater has a cylindrical rotor divided into a plurality of sector shaped compartments in which are disposed and supported spaced heat transfer plates which as the rotor turns are alternately exposed to a stream of hot gas and then upon rotation of the rotor to a stream of cold air or other gaseous fluid to be heated. The plurality of sector shaped compartments is loaded with heat exchange baskets which contain the mass of heat absorbent material commonly formed of stacked plate-like heat transfer elements.
[003] As the heat transfer plates are exposed to the hot gas, the heat transfer plates absorb heat there from and then when exposed to the cold air or other gaseous fluid to be heated, the heat absorbed from the hot gas by the heat transfer plates is transferred to the cold air or gas. Most heat exchangers of this type have their heat transfer plates closely stacked in spaced relationship to provide a plurality of passageways between adjacent plates for flowing the heat exchange fluid therebetween.
[004] In such a heat exchanger, the heat transfer capability of a heat exchanger of a given size is a function of the rate of heat transfer between the heat exchange fluid and the plate structure. However for commercial devices, the utility of a device is determined not alone by the coefficient of heat transfer obtained, but also by other factors such as the resistance to flow of the heat exchange fluid through the device, i.e., the pressure drop, the ease of cleaning the flow passages, the structural integrity of the heat transfer plates, as well as factors, such as cost and weight of the plate structure. Ideally, the heat transfer plates will induce a highly turbulent flow through the passages therebetween in order to increase heat transfer from the heat exchange fluid to the plates while at the same time providing relatively low resistance to flow between the passages and also presenting a surface configuration which is readily cleanable.
[005] To clean the heat transfer plates, it has been customary to provide soot blowers which deliver a blast of high-pressure air or steam through the passages between the stacked heat transfer plates to dislodge any particulate deposits from the surface thereof and carry them away leaving a relatively clean surface. One problem encountered with this method of cleaning is that the force of the high-pressure blowing medium on the relatively thin heat transfer plates can lead to cracking of the plates unless a certain amount of structural rigidity is designed into the stack assembly of heat transfer plates.
[006] It is, therefore, an object of the present invention to provide an improved heat transfer element assembly wherein the structural integrity of the heat transfer plates is enhanced by notching while at the same time providing a design wherein nesting is precluded.
OBJECTS OF THE INVENTION:
[007] The principal objective of the present subject matter is to provide an assembly of heat transfer element to reduce the pressure drop and to optimize the size of the air-preheater.
[008] Another object of the present subject matter is to provide a heat transfer element having high heat transfer area to improve effectiveness of the air-preheater. Accordingly, the air-preheater size can be reduced.
[009] Another object of the present subject matter is to provide the heat transfer elements have longitudinal notches in the direction of fluid flow. In addition to the notches, the heat transfer element having a series of undulations between the notches to an angle to the fluid flow direction. The undulation in one element is in one direction and undulation in other element are in opposite direction.
[0010] Yet another object of the invention is to have more number of undulations because of wider pitch (P) between notches. This will lead to high heat transfer area and improved effectiveness of the air-preheater.
SUMMARY OF THE INVENTION:
[0011] The subject matter disclosed herein relates to an assembly of a heat transfer element for a rotary regenerative air-preheater. The assembly comprises a plurality of first heat absorbent plates having a plurality of notches transversely spaced apart from each other along longitudinal direction and a plurality of undulations provided in between two consecutive notches. A plurality of second heat absorbent plates having a plurality of undulations such that the plurality of first heat absorbent plates and the plurality of second heat absorbent plates are stacked alternately in spaced relationship thereby providing a plurality of passageways adjacent between the plurality of first heat absorbent plates and the plurality of second heat absorbent plates for flowing heat exchange fluid therebetween. The plurality of undulations of the plurality of first heat absorbent plates are in opposite direction of the plurality of undulations of the plurality of second heat absorbent plates.
[0012] In order to further understand the characteristics and technical contents of the present subject matter, a description relating thereto will be made with reference to the accompanying drawings. However, the drawings are illustrative only but not used to limit scope of the present subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS
[0013] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0014] Fig. 1 illustrates a diagrammatic view of a plurality of first heat absorbent plates having series of undulations with an angle to fluid flow direction, in accordance with an embodiment of the present subject matter;
[0015] Fig. 2 illustrates a diagrammatic view of a plurality of second heat absorbent plates having series of undulations with an angle to fluid flow direction, in accordance with an embodiment of the present subject matter; and
[0016] Fig. 3 illustrates an enlarged perspective view of heat transfer elements, in accordance with an embodiment of the present subject matter.
[0017] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0018] The subject matter disclosed herein relates to an assembly of a heat transfer element for a rotary regenerative air-preheater. The assembly comprises a plurality of first heat absorbent plates having a plurality of notches transversely spaced apart from each other along longitudinal direction (X) and a plurality of undulations provided in between two consecutive notches. A plurality of second heat absorbent plates having a plurality of undulations such that the plurality of first heat absorbent plates and the plurality of second heat absorbent plates are stacked alternately in spaced relationship thereby providing a plurality of passageways adjacent between the plurality of first heat absorbent plates and the plurality of second heat absorbent plates for flowing heat exchange fluid therebetween. The plurality of undulations of the plurality of first heat absorbent plates are in opposite direction of the plurality of undulations of the plurality of second heat absorbent plates.
[0019] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0020] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0021] FIG. 3 illustrates an enlarged perspective view of heat transfer elements, in accordance with the present invention to achieve the high heat transfer and reduced pressure drop and to optimize the size of the air-preheater.
[0022] In accordance with the present invention, the assembly (10) has a plurality of first heat absorbent plates (1) having a plurality of notches (2) transversely spaced apart from each other along longitudinal direction (X) and a plurality of undulations (3) provided in between two consecutive notches (2). A plurality of second heat absorbent plates (4) having a plurality of undulations (5). The plurality of first and second heat absorbent plates (1, 4) are stacked alternately in spaced relationship thereby providing a plurality of passageways adjacent between the plurality of first and the second heat absorbent plates (1, 4) for flowing heat exchange fluid therebetween.
[0023] The plurality of undulations (3) of the plurality of first heat absorbent plates (1) are in opposite direction of the plurality of undulations (5) of the plurality of second heat absorbent plates (4). The plurality of undulations (3) of the plurality of first heat absorbent plates (1) are at an angle (?1) to the heat exchange fluid flow direction (X), as shown in FIG. 1. The plurality of undulations (5) of the plurality of second heat absorbent plates (4) are at an angle (?2) to the heat exchange fluid flow direction (X), as shown in FIG. 2. The angles (?1, ?2) of the plurality of undulations (3, 5) are equal and in opposite direction to each other.
[0024] The plurality of notches (2) are in parallel direction with the heat exchanging fluid flow direction (X) and placed on the plurality of undulations (5) of the plurality of second heat absorbent plates (4). such that the plurality of notches (2) define a sinusoidal wave shaped cross section.
[0025] Further, the assembly (10) has a pitch (P) which is defined in between two consecutive notches (2a, 2b) which is equal to at least two number of undulations (3).
[0026] The plurality of first and second heat absorbent plates (1, 4) are usually of thin sheet metal capable of being rolled or stamped to the desired configuration; however, the invention is not necessarily limited to use of metallic plates. The plurality of first and second heat absorbent plates (1, 4) may be of various surface configurations such as, but not limited to, preferably, a corrugated surface as illustrated in FIGS. 3.
[0027] A plurality of spacers is maintained to a predetermined distance between the plurality of first and second heat absorbent plates (1, 4). The spacers are formed by crimping the heat absorbent plates (1, 4) to produce folds in the plurality of first and second heat absorbent plates (1, 4) at spaced intervals. The folds have first and second lobes, respectively, projecting outwardly from the surface of the plurality of first and second heat absorbent plates (1, 4) in opposite directions. Preferably, each lobe is in the form of a substantially V-shaped groove with the apex of the groove directed outwardly from the plurality of first and second heat absorbent plates (1, 4). Additionally, it is preferred that the folds are aligned with a line of flow through the heat transfer element assembly so that flow will be along the grooves so that the grooves do not offer a significant resistance to fluid flow through the heat transfer element assembly.
[0028] In the present invention achieves the high heat transfer area and improved effectiveness of the air-preheater. Accordingly, the air-preheater size can be reduced due to improved effectiveness.
[0029] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0030] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.

We claim:

1. An assembly (10) of heat transfer element for a rotary regenerative air-preheater for increasing heat transfer, the assembly (10) comprising:
a plurality of first heat absorbent plates (1) having a plurality of notches (2) transversely spaced apart from each other along longitudinal direction (X) and a plurality of undulations (3) provided in between two consecutive notches (2);
a plurality of second heat absorbent plates (4) having a plurality of undulations (5); and
the plurality of first heat absorbent plates (1) and the plurality of second heat absorbent plates (4) are stacked alternately in spaced relationship thereby providing a plurality of passageways adjacent between the plurality of first heat absorbent plates (1) and the plurality of second heat absorbent plates (4) for flowing heat exchange fluid therebetween.
2. The assembly (10) as claimed in claim 1, wherein the plurality of undulations (3) of the plurality of first heat absorbent plates (1) are in opposite direction of the plurality of undulations (5) of the plurality of second heat absorbent plates (4).
3. The assembly (10) as claimed in claim 1, wherein the plurality of undulations (3) of the plurality of first heat absorbent plates (1) are at an angle (?1) to the heat exchange fluid flow direction (X).

4. The assembly (10) as claimed in claim 1, wherein the plurality of undulations (5) of the plurality of second heat absorbent plates (4) are at an angle (?2) to the heat exchange fluid flow direction (X).

5. The assembly (10) as claimed in claim 1, wherein the angle (?1) of the plurality of undulations (3) and the angle (?2) the plurality of undulations (5) are equal and in opposite direction to each other.

6. The assembly (10) as claimed in claim 1, wherein the plurality of notches (2) are in parallel direction with the heat exchanging fluid flow direction (X).

7. The assembly (10) as claimed in claim 1, wherein the plurality of notches (2) define a sinusoidal wave shaped cross section.

8. The assembly (10) as claimed in claim 1, wherein the assembly (10) further comprising a pitch (P) is defined in between two consecutive notches (2a, 2b) which is equal to at least two number of undulations (3).

9. The assembly (10) as claimed in claim 1, wherein the plurality of notches (2) are placed on the plurality of undulations (5) of the plurality of second heat absorbent plates (4).

10. The assembly of heat transfer elements for Rotary Regenerative Air Preheater as explained and as illustrated in the accompanying drawings.