A dust-accumulation-proof heat exchanger

Abstract

The present invention provides an anti-ash accumulation heat exchanger comprising heat exchange tubes, including circular and elliptical tubes. The elliptical tubes are arranged alternately with the circular tubes. The circular tubes are perfectly circular, the major axis of the ellipse corresponding to the cross-section of the elliptical tube is twice the length of the minor axis of the ellipse corresponding to the cross-section of the elliptical tube, and the circumference of the circle corresponding to the cross-section of the circular tube is equal to the circumference of the ellipse corresponding to the cross-section of the elliptical tube. The heat exchanger of the present invention solves the serious ash accumulation problem in industrial exhaust waste heat recovery systems while ensuring good heat transfer performance and low flow pressure drop.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial exhaust waste heat recovery / heat exchangers, and in particular to an anti-dust accumulation heat exchanger. Background Art

[0002] my country has enormous potential for energy conservation from industrial exhaust waste heat. Industrial energy consumption accounts for nearly 70% of my country's total energy consumption, of which waste heat resources account for 17%-67% of total industrial fuel consumption, and flue gas waste heat accounts for over 50% of total industrial waste heat resources. In some industrial kilns, the waste heat from flue gas can even reach 30%-60% of the kiln's own fuel consumption. With my country's waste heat recovery rate at less than 20%, fully recycling and utilizing industrial exhaust waste heat has become a crucial measure to alleviate my country's energy crisis and is closely linked to national economic development.

[0003] Industrial exhaust typically contains a large amount of soot, and even after dust removal, it still contains small amounts of fly ash particles. These fly ash particles accumulate on the heat exchanger surfaces, causing a decrease in the heat transfer coefficient. This impact is particularly significant for heat exchangers that recover waste heat from medium- and low-temperature sources. Currently, exhaust heat recovery devices such as power plant economizers typically use physical or chemical methods to remove ash deposits after shutdown. Because some low-temperature flue gas waste heat recovery equipment is coated with an anti-corrosion coating, physical methods such as high-speed soot blowing or chemical cleaning processes may damage the coating to a certain extent, shortening the life of the heat exchanger.

[0004] Therefore, in order to reduce the impact of dust accumulation on heat transfer performance and reduce the damage of dust cleaning measures to the heat exchanger, it is urgent to develop a heat exchanger with anti-dust accumulation function. Summary of the Invention

[0005] The present invention provides an anti-dust accumulation heat exchanger to solve the defects in the prior art.

[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions.

[0007] An embodiment of the present invention provides an anti-dust accumulation heat exchanger, comprising: a heat exchange tube, wherein the heat exchange tube comprises a circular tube and an elliptical tube; the elliptical tube and the circular tube are arranged alternately, the circular tube is a perfect circular tube, the major axis of the elliptical tube corresponding to the cross section of the elliptical tube is twice the length of the minor axis of the elliptical tube corresponding to the cross section of the elliptical tube, and the circumference of the circle corresponding to the cross section of the circular tube is equal to the circumference of the elliptical tube corresponding to the cross section of the elliptical tube.

[0008] Preferably, the center distance between adjacent heat exchange tubes is twice the outer diameter of the circular tube.

[0009] Preferably, the heat exchange tubes are arranged in a sequential manner.

[0010] Preferably, the elliptical tube is installed in such a way that the major axis of the ellipse corresponding to the cross section is along the downstream direction of the heat exchange fluid outside the tube, and the minor axis of the ellipse corresponding to the cross section is arranged perpendicular to the incoming flow direction.

[0011] It can be seen from the technical solution provided by the above-mentioned anti-dust heat exchanger of the present invention that the heat exchanger of the present invention arranges the elliptical tubes and circular tubes in an alternating manner. The long axis of the cross section of the elliptical tube is along the downstream direction of the heat exchange fluid outside the tube, and the short axis is arranged perpendicular to the incoming flow direction, which reduces the area of ​​the windward surface and enhances the disturbance. The special elliptical tube setting can effectively reduce the deposition of dust on the surface of the heat exchange tube. At the same time, it has better heat transfer performance and lower flow resistance.

[0012] Additional aspects and advantages of the present invention will be set forth in part in the following description, will become apparent from the following description, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0014] Figure 1 This is a schematic structural diagram of the dust accumulation prevention heat exchanger of this embodiment;

[0015] Figure 2 A cross-sectional diagram of the tube design and arrangement of the dust-proof heat exchanger provided in this embodiment;

[0016] Figure 3 A three-dimensional schematic diagram of the tube design and arrangement of the anti-dust heat exchanger provided in this embodiment.

[0017] Description of reference numerals:

[0018] 1. Round tube; 2. Oval tube; 3. Flue gas inlet; 4. Casing; 5. Cooling water inlet; 6. Cooling water return area; 7. Flue gas outlet; 8. Cooling water outlet DETAILED DESCRIPTION

[0019] The embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0020] It will be understood by those skilled in the art that, unless expressly stated otherwise, the singular forms "a", "an", "said" and "the" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the description of the present invention refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof. It should be understood that when we refer to an element as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or there may be intermediate elements. In addition, "connected" or "coupled" as used herein may include wireless connections or couplings. The term "and / or" used herein includes any unit and all combinations of one or more associated listed items.

[0021] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art in the art to which the present invention pertains. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art and, unless defined as such herein, will not be interpreted in an idealized or overly formal sense.

[0022] To facilitate understanding of the embodiments of the present invention, several specific embodiments will be further explained below with reference to the accompanying drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0023] Example

[0024] Figure 1 This is a schematic diagram of the structure of the anti-dust heat exchanger of this embodiment, refer to Figure 1 The heat exchanger includes a heat exchange tube, a flue gas inlet 3, a shell 4, a cooling water inlet 5, a cooling water return area 6, a flue gas outlet 7 and a cooling water outlet 8: the heat exchange tube includes a circular tube 1 and an elliptical tube 2.

[0025] Figure 2 This is a cross-sectional diagram of the tube design and arrangement of the dust-proof heat exchanger provided in this embodiment. Figure 3 The three-dimensional schematic diagram of the anti-dust heat exchanger tube design and arrangement provided in this embodiment, refer to Figure 2 and Figure 3 The elliptical tubes 2 and circular tubes 1 are arranged alternately. Circular tube 1 is a perfect circular tube. The cross section of elliptical tube 2 corresponds to the major axis of the ellipse, which is twice the length of the minor axis of the ellipse. The cross section of circular tube 1 corresponds to the circumference of the circle, which is equal to the circumference of the ellipse, which is equal to the cross section of elliptical tube 2. 2b is the minor axis of the ellipse, which is equal to the cross section of elliptical tube 2. 2a is the major axis of the ellipse, which is equal to the cross section of elliptical tube 2.

[0026] The center distance between adjacent heat exchange tubes (S L 、S T ) is twice the outer diameter D of the tube, S L is the distance between pipes in the downstream direction, S T It is the pipe spacing perpendicular to the incoming flow direction.

[0027] The heat exchange tubes are arranged in a sequential manner.

[0028] The elliptical tube is installed in such a way that the major axis of the cross section is along the downstream direction of the heat exchange fluid outside the tube, and the minor axis is arranged perpendicular to the incoming flow direction.

[0029] High-temperature industrial exhaust smoke flows into the heat exchanger from the flue gas inlet 3, and the heat exchange tube bundle composed of the outward-swept elliptical tube 2 and the circular tube 1 exchanges heat with the cooling water entering the elliptical tube 2 and the circular tube 1 from the cooling water inlet 5 in a cross-flow manner. The flue gas after heat exchange flows out of the heat exchanger from the flue gas outlet 7; after the cooling water flows through the front row of elliptical tubes 2 and the circular tube 1 and absorbs the heat of the flue gas, it flows out from the front row of elliptical tubes 2 and the circular tube 1 and flows into the cooling water return area 6, then changes direction and flows into the rear row of elliptical tubes 2 and the circular tube 1 to further absorb the heat of the flue gas. After several turns, the cooling water that has fully absorbed the heat of the flue gas flows out from the cooling water outlet 8.

[0030] The flue gas first sweeps outwards through elliptical tube 2. Because the major axis of the elliptical cross-section of elliptical tube 2 aligns with the flue gas flow direction, the windward area of ​​elliptical tube 2 is smaller, thereby reducing the amount of ash accumulation in the first row of heat exchange tubes, where ash is most likely to accumulate. The flue gas then sweeps outwards through circular tube 1. Because circular tube 1 has a larger windward area than elliptical tube 2, the flue gas's flow velocity increases as it sweeps outwards through circular tube 1, increasing disturbance and enhancing the heat transfer effect. The elliptical tube 2 and the circular tube 1 are combined front and back, and the cross-section of the combination of the elliptical tube 2 and the circular tube 1 is teardrop-shaped along the direction of flue gas flow. On the one hand, compared with the traditional circular tube heat exchanger, the teardrop-shaped cross-section has better streamline and smaller flue gas flow pressure drop. On the other hand, it suppresses the formation of flue gas vortex at the tail of the elliptical tube 2 and the front of the circular tube 1, reducing the deposition of flue gas particles carried by the vortex on the front of the circular tube 1 with a larger windward area; the line connecting the centers of adjacent circular tubes is the narrowest section of the flue gas channel, where the flue gas flow rate is the fastest, and boundary layer separation occurs near this point, generating vortexes. The vortexes carry flue gas particles into the front of the rear elliptical tube 2. Since the windward area of ​​the elliptical tube 2 is small, the amount of ash accumulation is effectively reduced.

[0031] In summary, the heat exchanger described in this embodiment achieves dust prevention through a well-designed aerodynamic layout, while balancing heat exchange and pressure drop. Compared to traditional circular tube heat exchangers, the heat exchanger in this embodiment significantly reduces dust accumulation, reducing it by more than half. While reducing the heat exchanger's pressure drop by approximately 60%, the heat transfer coefficient only decreases by approximately 14%. Overall, the benefits outweigh the disadvantages. Furthermore, the significant reduction in pressure drop allows for a suitable increase in the heat exchanger's area to compensate for the reduced heat transfer coefficient, thereby achieving optimal overall performance.

[0032] Those skilled in the art should understand that the above-mentioned application types are only examples, and other existing or future application types that are applicable to the embodiments of the present invention should also be included in the scope of protection of the present invention and are included here by reference.

[0033] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A dust-proof heat exchanger, characterized in that: include: Heat exchange tubes, the heat exchange tubes comprising circular tubes and elliptical tubes; the elliptical tubes and the circular tubes are arranged alternately, the circular tubes are perfect circular tubes, the major axis of the ellipse corresponding to the cross section of the elliptical tube is twice the length of the minor axis of the ellipse corresponding to the cross section of the elliptical tube, and the circumference of the circle corresponding to the cross section of the circular tube is equal to the circumference of the ellipse corresponding to the cross section of the elliptical tube; The heat exchange tubes are arranged in a sequential manner; The elliptical tube is installed in such a way that the major axis of the ellipse corresponding to the cross section is along the downstream direction of the heat exchange fluid outside the tube, and the minor axis of the ellipse corresponding to the cross section is arranged perpendicular to the incoming flow direction; When the flue gas sweeps over the sequentially arranged heat exchange tubes, it first sweeps over the elliptical tubes and then the circular tubes, which can suppress the vortex formed by the flue gas at the tail of the elliptical tube and the front of the circular tube.

2. The heat exchanger according to claim 1, characterized in that The center distance between adjacent heat exchange tubes is twice the outer diameter of the circular tube.

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