Heat transfer element suitable for cold end of air preheater
By designing a flat first plate and a corrugated second plate at the cold end of the air preheater, combined with straight lines, oblique lines, and flow holes, the problems of small heat exchange area and ash blockage of the heat transfer element were solved, achieving efficient heat exchange and low-cost heat transfer effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-18
- Publication Date
- 2026-04-07
AI Technical Summary
Existing rotary air preheaters have small heat transfer areas, low heat transfer efficiency, high equipment investment and operating costs, and are also prone to ash blockage.
Design a heat transfer element suitable for the cold end of an air preheater, using a flat first plate and a corrugated second plate. The second plate has straight and diagonal lines to increase the heat exchange area, and flow holes are opened on the first plate to reduce dust accumulation.
It improves the heat exchange capacity and anti-fouling performance of heat transfer elements, reduces equipment costs, adapts to the combustion requirements of different fuels and boiler operating conditions, and improves economic efficiency.
Smart Images
Figure CN224095001U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the technical field of heat transfer elements, and in particular to a heat transfer element suitable for the cold end of an air preheater. Background Technology
[0002] A rotary air preheater is a regenerative, high-efficiency heat exchanger that uses heat storage elements to store heat from flue gas and transfer it to air. The heat transfer element plates are a key component of the preheater, typically made of thin metal sheets and housed in sector-shaped compartments within a rotating cylindrical rotor. The heat transfer elements achieve efficient heat exchange through specific plate designs, such as corrugated and slotted sections.
[0003] In existing technology, the heat transfer element of a rotary air preheater consists of two plates, one flat and the other corrugated. This element has a small heat exchange area and low heat exchange efficiency, resulting in the selection of an oversized air preheater, a significant increase in equipment investment and operating costs, and also suffers from ash blockage problems, which urgently need to be improved. Utility Model Content
[0004] To address the aforementioned technical problems, this application provides a heat transfer element suitable for the cold end of an air preheater.
[0005] The heat transfer element for the cold end of an air preheater provided by this utility model adopts the following technical solution:
[0006] A heat transfer element suitable for the cold end of an air preheater includes a first plate and a second plate; the first plate and the second plate are attached together; wherein the first plate is flat; the second plate is provided with a plurality of straight lines and a plurality of oblique lines; the straight lines protrude from the side of the second plate away from the first plate and extend along the flue gas flow direction; the plurality of straight lines are evenly spaced along a direction perpendicular to the flue gas flow direction; the oblique lines protrude from the side of the second plate away from the first plate, and the height of the protrusion is lower than the height of the straight lines; the extension direction of the oblique lines is inclined relative to the flue gas flow direction; between each two adjacent straight lines, the oblique lines are arranged side by side along the flue gas flow direction.
[0007] Optionally, the first plate is provided with multiple flow holes to reduce dust accumulation between the first plate and the second plate.
[0008] Optionally, the flow holes are arranged in a rectangular array, with the length of the array parallel to the flue gas flow direction and the width of the array perpendicular to the flue gas flow direction.
[0009] Optionally, the spacing between two adjacent flow holes is 5mm to 15mm in both the width and length directions of the array.
[0010] Optionally, the diameter of the flow hole is between 2 mm and 4 mm.
[0011] Optionally, the interval between two adjacent straight lines is between 65 mm and 75 mm.
[0012] Optionally, the height of the straight lines protruding from the second plate is between 10mm and 15mm.
[0013] Optionally, the angle between the twill and the flue gas flow direction is between 45° and 60°.
[0014] As described above, the heat transfer element of this invention, suitable for the cold end of an air preheater, has at least the following beneficial effects:
[0015] 1. The heat transfer element of this utility model, applicable to the cold end of an air preheater, has straight and diagonal lines on the second plate, which increases the surface area of the first plate. The diagonal lines can disturb the airflow, allowing the flue gas to exchange heat more fully at the diagonal lines, thereby improving the heat exchange capacity of the first plate.
[0016] 2. The ash passage groove formed between the straight lines and the first plate, as well as the flow holes opened on the first plate, can reduce the ash blockage of the heat transfer element by the dust entrained in the flue gas, keep the heat transfer element clean, and give the heat transfer element high anti-ash blockage performance, thereby helping to improve the heat exchange capacity of the heat transfer element.
[0017] 3. The heat transfer element of this utility model, applicable to the cold end of an air preheater, employs a flat first plate and a second plate with a wavy longitudinal section, resulting in a more compact overall structure. This allows for the arrangement of more heat transfer elements within the limited space of the air preheater, helping to reduce equipment costs and improve economic efficiency. Furthermore, because the heat transfer element balances heat exchange capacity and anti-ash-clogging performance, it can adapt to the combustion requirements of different fuels and boiler operating conditions, demonstrating strong adaptability. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the overall structure of the heat transfer element applicable to the cold end of an air preheater.
[0019] Figure 2 This is a longitudinal cross-sectional view of a heat transfer element suitable for the cold end of an air preheater.
[0020] Figure 3 This is a schematic diagram of the second plate structure.
[0021] Figure 4 This is a schematic diagram of the first plate structure.
[0022] Reference numerals: 1. First plate; 2. Second plate; 3. Straight grain; 4. Twill grain; 5. Ash passage groove; 6. Flow hole. Detailed Implementation
[0023] The following specific examples illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. This utility model can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this utility model. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. It should also be understood that the terminology used in the embodiments of this utility model is for describing specific implementation schemes and not for limiting the scope of protection of this utility model. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.
[0024] It should be understood that the structures, proportions, sizes, etc., illustrated in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art and are not intended to limit the scope of implementation of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of this utility model, should still fall within the scope of the technical content disclosed in this utility model. Furthermore, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity of description and are not intended to limit the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of this utility model.
[0025] The heat transfer element is the smallest structural unit in an air preheater that performs heat transfer. The air preheater has a rectangular outer shell. Flue gas flows into the shell from one of its opposite sides and exits from the other. The direction from the flue gas inlet to the flue gas outlet on the shell is the flue gas flow direction. Inside the shell, the flue gas exchanges heat with multiple stacked heat transfer elements. After absorbing and storing heat from the flue gas, the heat transfer elements transfer this heat to the air entering the boiler. Through this heat exchange process, the air is preheated to a certain temperature, thereby improving the boiler's heat exchange efficiency. The preheated air is then sent into the furnace, which increases the furnace temperature, enhances combustion, and ensures ignition stability under low loads.
[0026] Please refer to Figure 1-4 The heat transfer element of this utility model, applicable to the cold end of an air preheater, includes a first plate 1 and a second plate 2. The first plate 1 and the second plate 2 are attached together.
[0027] Specifically, the first plate 1 is flat. The second plate 2 has multiple straight lines 3 and multiple diagonal lines 4. The straight lines 3 protrude from the side of the second plate 2 away from the first plate 1 and extend along the direction of flue gas flow. The multiple straight lines 3 are evenly spaced along a direction perpendicular to the direction of flue gas flow. The diagonal lines 4 protrude from the side of the second plate 2 away from the first plate 1, and the height of the protrusion is lower than the height of the protrusion of the straight lines 3. The extension direction of the diagonal lines 4 is inclined relative to the direction of flue gas flow. Between every two adjacent straight lines 3, the diagonal lines 4 are arranged side by side along the direction of flue gas flow.
[0028] Please refer to Figures 1-3 The longitudinal section of the second plate 2 is wavy, with the top and bottom edges of the straight lines 3 corresponding to the crests and troughs of the wave, respectively. The diagonal lines 4 located between the two straight lines 3 are wavy with smaller undulations, connecting the two adjacent straight lines 3 and transitioning smoothly with the straight lines 3.
[0029] The interior of the straight-lined section 3 is hollow. A dust passage groove 5 is formed between the inner wall of the straight-lined section 3 and the side of the first plate 1 near the second plate 2. Since the diameter of the dust passage groove 5 is much larger than the diameter of the dust particles, the dust carried in the flue gas can be smoothly discharged through the dust passage groove 5 during the heat exchange process between the flue gas and the heat transfer element, and will not accumulate in the heat transfer element to form a blockage.
[0030] Both straight lines 3 and diagonal lines 4 can increase the surface area of the second plate 2, thereby increasing the heat transfer area of the heat transfer element. Furthermore, diagonal lines 4 can increase airflow turbulence, further improving the heat transfer capacity of the second plate 2.
[0031] Furthermore, if the angle between the diagonal lines 4 and the flue gas flow direction is too small, the diagonal lines 4 will not effectively disturb the airflow and will not significantly improve the heat exchange capacity of the second plate 2. Conversely, if the angle between the diagonal lines 4 and the flue gas flow direction is too large, the diagonal lines 4 will disturb the airflow too strongly, easily leading to low flue gas velocity near the surface of the diagonal lines 4 and causing ash accumulation. Therefore, in some preferred embodiments of this invention, the angle between the diagonal lines 4 and the flue gas flow direction is between 45° and 60°, for example, 45°, 50°, 55°, and 60°. In this way, the diagonal lines 4 can effectively disturb the airflow and improve the heat exchange capacity of the second plate 2, while also preventing ash accumulation.
[0032] It should be noted that the reason why the first plate 1 is flat instead of similar to the shape of the second plate 2 is that if the first plate 1 is similar to the shape of the second plate 2, although the heat exchange area is larger, the flue gas will encounter greater resistance when passing through the heat transfer element and will be very easy to clog with ash.
[0033] Excessive spacing between the straight lines 3 will reduce the number of straight lines 3 on the second plate 2, thereby reducing the number of ash-passing grooves 5 formed between the straight lines 3 and the first plate 1, which is detrimental to the ash removal of the heat transfer element. Conversely, insufficient spacing between the straight lines 3 will shorten the length of the diagonal lines 4 on the second plate 2, weakening the airflow disturbance effect of the diagonal lines 4. Therefore, in a preferred embodiment of this invention, the spacing between two adjacent straight lines 3 is between 65mm and 75mm, for example, 65mm, 67mm, 68mm, 69mm, 70mm, 72mm, and 75mm. A reasonable spacing between two adjacent straight lines 3 can reduce ash blockage in the heat transfer element while ensuring the function of the diagonal lines 4, thereby improving the heat exchange effect of the second plate 2.
[0034] On the other hand, if the height of the straight lines 3 protruding from the second plate 2 is too high, the number of heat transfer elements that can be stacked in an air preheater of the same volume will be reduced, thus decreasing the overall heat exchange effect of the air preheater. Conversely, if the height of the straight lines 3 protruding from the second plate 2 is too low, although more heat transfer elements can be stacked in the air preheater, the flow area of the ash-clearing grooves 5 on the heat transfer elements will be reduced, making it easier for ash to clog the heat transfer elements. Therefore, in some preferred embodiments of this invention, the height of the straight lines 3 protruding from the second plate 2 is between 10mm and 15mm, for example, 10mm, 12mm, 13mm, 14mm, or 15mm. This ensures both the overall heat exchange effect of the air preheater and prevents ash from clogging the heat transfer elements.
[0035] Please refer to Figures 2-4 To further reduce dust accumulation on the heat transfer elements, multiple flow holes 6 are provided on the first plate 1 to reduce dust accumulation between the first plate 1 and the second plate 2. Firstly, the flow holes 6 on the first plate 1 reduce the adhesion of dust to the first plate 1. Secondly, when flue gas passes through the gap between the first plate 1 and one of the second plates 2, the flue gas will enter the gap between the first plate 1 and another second plate 2 through the flow holes 6, increasing the disturbance to the flue gas and further reducing dust accumulation on the first plate 1.
[0036] The position of the flow holes 6 can be adaptively adjusted on the first plate 1 according to actual needs. In a preferred embodiment of this utility model, the flow holes 6 are arranged in a rectangular array, with the length direction of the array parallel to the flue gas flow direction and the width direction of the array perpendicular to the flue gas flow direction. The rectangular array arrangement can improve the uniformity of the flow hole arrangement 6 and avoid insufficient local anti-clogging performance on the first plate 1.
[0037] Furthermore, the spacing between two adjacent flow holes 6 is 5mm to 15mm in both the width and length directions of the array, for example, 5mm, 10mm, and 15mm. The diameter of the flow holes 6 is between 2mm and 4mm, for example, 2mm, 3mm, and 4mm. Properly setting the spacing between the flow holes 6 ensures that the flow holes 6 have anti-clogging properties while maintaining sufficient mechanical strength for the first plate 1. This prevents the first plate 1 from breaking or bending during stacking due to insufficient mechanical strength caused by excessively dense or large-diameter flow holes 6, thus blocking the air preheater.
[0038] In summary, the heat transfer element of this utility model suitable for the cold end of an air preheater has straight lines 3 and diagonal lines 4 on the second plate 2, which increases the surface area of the first plate 1. The diagonal lines 4 can disturb the airflow, allowing the flue gas to exchange heat more fully at the diagonal lines 4, thereby improving the heat exchange capacity of the first plate 1.
[0039] The ash passage 5 formed between the straight groove 3 and the first plate 1, and the flow hole 6 opened on the first plate 1, can reduce the ash blockage of the heat transfer element by the dust entrained in the flue gas, keep the heat transfer element clean, and make the heat transfer element have high anti-ash blockage performance, thereby helping to improve the heat exchange capacity of the heat transfer element.
[0040] On the other hand, the heat transfer element of this invention, applicable to the cold end of an air preheater, employs a flat first plate 1 and a second plate 2 with a wavy longitudinal section, resulting in a more compact overall structure. This allows for the arrangement of more heat transfer elements within the limited space of the air preheater, helping to reduce equipment costs and improve economic efficiency. Furthermore, because the heat transfer element balances heat exchange capacity and anti-ash-clogging performance, it can adapt to the combustion requirements of different fuels and the operating conditions of the boiler, demonstrating strong adaptability.
[0041] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.
Claims
1. A heat transfer element suitable for the cold end of an air preheater, characterized in that: It includes a first plate (1) and a second plate (2); the first plate (1) and the second plate (2) are attached together; wherein, The first plate (1) is flat; The second plate (2) is provided with multiple straight lines (3) and multiple diagonal lines (4); The straight lines (3) protrude from the side of the second plate (2) away from the first plate (1) and extend along the flue gas flow direction; a plurality of the straight lines (3) are evenly spaced along a direction perpendicular to the flue gas flow direction. The diagonal stripe (4) protrudes from the side of the second plate (2) away from the first plate (1), and the height of the protrusion is lower than the height of the straight stripe (3); the extension direction of the diagonal stripe (4) is inclined relative to the flue gas flow direction; between each two adjacent straight stripes (3), the diagonal stripe (4) is arranged side by side along the flue gas flow direction.
2. The heat transfer element suitable for the cold end of an air preheater according to claim 1, characterized in that: The first plate (1) has multiple flow holes (6) to reduce dust accumulation between the first plate (1) and the second plate (2).
3. The heat transfer element suitable for the cold end of an air preheater according to claim 2, characterized in that: The flow holes (6) are arranged in a rectangular array, with the length of the array parallel to the flue gas flow direction and the width of the array perpendicular to the flue gas flow direction.
4. The heat transfer element suitable for the cold end of an air preheater according to claim 3, characterized in that, In both the width and length directions of the array, the spacing between two adjacent flow holes (6) is 5mm to 15mm.
5. The heat transfer element suitable for the cold end of an air preheater according to claim 2 or 3, characterized in that, The diameter of the flow hole (6) is between 2 mm and 4 mm.
6. The heat transfer element suitable for the cold end of an air preheater according to claim 1, characterized in that: The interval between two adjacent straight lines (3) is between 65mm and 75mm.
7. The heat transfer element suitable for the cold end of an air preheater according to claim 1, characterized in that: The height of the straight lines (3) protruding from the second plate (2) is between 10mm and 15mm.
8. The heat transfer element for the cold end of an air preheater according to claim 1, characterized in that: The angle between the twill (4) and the flue gas flow direction is between 45° and 60°.