A low-temperature economizer flue system
By renovating the flue system of the low-temperature economizer and using guide devices and rectifier grids to optimize the flue gas flow field, the problem of uneven flue gas flow field was solved, the safety and reliability of the low-temperature economizer were improved, and long-term stable operation was achieved.
Patent Information
- Application Number
- CN202210327218.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-03-30
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2042-03-30
AI Technical Summary
Due to imperfect design and insufficient operating experience, the low-temperature economizer system has uneven flue gas flow field, which leads to problems such as wear and corrosion of the heating surface, ash accumulation and blockage, and leakage of the heat exchange tubes, affecting the safety and reliability of the system.
By comprehensively renovating the flue between the air preheater and the low-temperature economizer, and installing guide devices such as arc guide devices, rectifier grids and non-metallic expansion joints, the flue gas flow field is optimized and the uniformity of the flue gas at the low-temperature economizer inlet is ensured.
The uniformity of the flue gas flow field at the low-temperature economizer inlet is improved, the risk of wear and leakage of the heating surface is reduced, the safety and reliability of the system are improved, and long-term stable operation is achieved.
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Figure CN114593409B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of power station boiler flue gas waste heat recovery and relates to a low-temperature economizer flue system. Background Art
[0002] The low-temperature economizer system can recover waste heat from flue gas and improve the economic efficiency of unit operation. At the same time, it can be used in conjunction with the electrostatic precipitator modification to improve dust removal efficiency and reduce the cost of ultra-low emission modification. It has significant economic and environmental benefits and has been widely used in the context of ultra-low emissions.
[0003] Most low-temperature economizers are large-scale centralized renovations. Due to imperfect design and insufficient initial operating experience, low-temperature economizers experience problems such as wear and corrosion of the heating surface, ash accumulation and blockage, and leakage of heat exchange tubes, making it impossible for the low-temperature economizer system to be put into normal operation. Among them, the uneven and turbulent flue gas flow field at the inlet of the low-temperature economizer is the main cause of wear on the heating surface of the low-temperature economizer. By comprehensively renovating the flue between the air preheater and the low-temperature economizer and installing a guide device along the way, the uniformity of the flue gas flow field at the inlet of the low-temperature economizer can be effectively improved, the risk of wear and leakage of the heating surface can be reduced, the safety and reliability of the low-temperature economizer operation can be improved, and the long-term safe and stable operation of the low-temperature economizer can be achieved. Therefore, a reasonable flue gas modification method should be adopted in the renovation of the low-temperature economizer to improve the uniformity of the flue gas flow field at the inlet of the low-temperature economizer. Summary of the Invention
[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a low-temperature economizer flue system, which can effectively improve the uniformity of the flue gas flow field at the low-temperature economizer inlet.
[0005] To achieve the above-mentioned object, the low-temperature economizer flue system of the present invention includes an air preheater, a first variable-section rectangular elbow, a straight flue of uniform cross-section, a streamlined special-shaped elbow, a rectangular flue tee, a first arc-shaped flow guide device, a second arc-shaped flow guide device, a symmetrical rectifying grid, an asymmetrical rectifying grid, a third arc-shaped flow guide device, an eccentric rectifying grid, two second variable-section rectangular elbows, two rectangular eccentric reducers, two low-temperature economizers and two dust collectors, wherein one second variable-section rectangular elbow corresponds to one rectangular eccentric reducer, one low-temperature economizer and one dust collector;
[0006] The flue gas outlet of the air preheater is connected to the lower end of the first variable-section rectangular elbow, the upper end of the first variable-section rectangular elbow is connected to the lower end of the uniform-section straight flue, the upper end of the uniform-section straight flue is connected to the lower end of the streamlined special-shaped elbow, the upper end of the streamlined special-shaped elbow is connected to the lower part of the rectangular flue tee, the two outlets on the upper part of the rectangular flue tee are respectively connected to one end of the two second variable-section rectangular elbows, the other end of the second variable-section rectangular elbow is connected to one end of the corresponding rectangular eccentric reducer, the other end of the rectangular eccentric reducer is connected to the shell-side flue gas inlet of the corresponding low-temperature economizer, and the shell-side flue gas outlet of the low-temperature economizer is connected to the flue gas inlet of the corresponding dust collector;
[0007] The first arc-shaped flow guide device is arranged in the outlet of the air preheater and in the first variable-section rectangular elbow, the second arc-shaped flow guide device, the symmetrical rectifying grid and the asymmetrical rectifying grid are arranged in the rectangular flue tee, the third arc-shaped flow guide device is arranged in the second variable-section rectangular elbow, and the eccentric rectifying grid is arranged in the inlet of the rectangular eccentric reducer.
[0008] A first non-metallic expansion joint is provided between the flue gas side outlet of the air preheater and the first variable-section rectangular elbow.
[0009] A second non-metallic expansion joint is provided between the straight flue of uniform cross-section and the streamlined special-shaped elbow.
[0010] A third non-metallic expansion joint is provided between the rectangular eccentric reducer and the low-temperature economizer.
[0011] A fourth non-metallic expansion joint is provided between the low-temperature economizer and the dust collector.
[0012] A flue ash hopper is arranged at the lower part of the first variable-section rectangular elbow, and a heating surface ash hopper is arranged at the lower part of the low-temperature economizer.
[0013] The streamlined special-shaped elbow consists of two equal-section elbows with opposite bending directions and a section of straight flue with equal cross-section. The angle between the streamlined special-shaped elbow and the center line of the rectangular flue tee is 20°~25°.
[0014] The flaring angle of the rectangular eccentric reducer is less than 30°.
[0015] The present invention has the following beneficial effects:
[0016] During operation of the low-temperature economizer flue system described in the present invention, the outlet of the air preheater enters the vertical flue through a first variable-section rectangular elbow and a first curved flow guide, maintaining a uniform flow field for the flue gas entering the vertical flue. Subsequently, the streamlined special-shaped elbow, the second curved flow guide within the rectangular flue tee, the symmetrical flow rectifier, and the asymmetrical flow rectifier, evenly distribute the flue gas flow entering the low-temperature economizers on both sides. The flue gas on both sides flows through the second variable-section rectangular elbow and the rectangular eccentric reducer, where it diffuses and slows down uniformly to prevent ash accumulation in the flue. Simultaneously, the flow is guided by the curved flow guide and rectified by the eccentric flow rectifier to improve the uniformity of the flue gas flow field at the low-temperature economizer inlet. The low-temperature economizer is arranged at the inlet of the dust collector. This allows accumulated ash in the low-temperature economizer area to enter the dust collector directly, reducing ash accumulation on the heating surface of the low-temperature economizer and in the flue. It also increases the length of the low-temperature economizer inlet flue gas, facilitating flue gas modification and flow field optimization. The present invention comprehensively transforms the flue between the air preheater and the low-temperature economizer and arranges a guide device along the way, which can effectively improve the uniformity of the flue gas flow field at the inlet of the low-temperature economizer, reduce the risk of wear and leakage of the heating surface, improve the safety and reliability of the low-temperature economizer operation, and realize long-term safe and stable operation of the low-temperature economizer. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 is a side view of the present invention;
[0018] Figure 2 It is the front view of the present invention;
[0019] Figure 3 It is a top view of the present invention.
[0020] Among them, 1 is an air preheater, 2 is the first non-metallic expansion joint, 3 is the first variable-section rectangular elbow, 4 is a flue ash hopper, 5 is a straight flue with equal section, 6 is a second non-metallic expansion joint, 7 is a streamlined special-shaped elbow, 8 is a rectangular flue tee, 9 is the second variable-section rectangular elbow, 10 is a rectangular eccentric reducer, 11 is a third non-metallic expansion joint, 12 is a low-temperature economizer, 13 is a fourth non-metallic expansion joint, 14 is a heated surface ash hopper, 15 is a dust collector, 16 is a first arc-shaped guide device, 17 is a second arc-shaped guide device, 18 is a symmetrical rectifier grid, 19 is an asymmetrical rectifier grid, 20 is a third arc-shaped guide device, and 21 is an eccentric rectifier grid. DETAILED DESCRIPTION
[0021] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.
[0022] The accompanying drawings illustrate schematic diagrams of the structures of the disclosed embodiments of the present invention. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.
[0023] refer to Figures 1 to 3 The low-temperature economizer flue system of the present invention includes an air preheater 1, a first non-metallic expansion joint 2, a first variable-section rectangular elbow 3, a straight flue 5 with a constant cross-section, a second non-metallic expansion joint 6, a streamlined special-shaped elbow 7, a rectangular flue tee 8, two second variable-section rectangular elbows 9, two rectangular eccentric reducers 10, two third non-metallic expansion joints 11, two low-temperature economizers 12, two fourth non-metallic expansion joints 13 and two dust collectors 15, wherein one second variable-section rectangular elbow 9 corresponds to one rectangular eccentric reducer 10, one third non-metallic expansion joint 11, one low-temperature economizer 12, one fourth non-metallic expansion joint 13 and one dust collector 15;
[0024] The flue gas side outlet of the air preheater 1 is connected to the lower end of the first variable-section rectangular elbow 3, the upper end of the first variable-section rectangular elbow 3 is connected to the lower end of the equal-section straight flue 5, the upper end of the equal-section straight flue 5 is connected to the lower end of the streamlined special-shaped elbow 7, the upper end of the streamlined special-shaped elbow 7 is connected to the lower part of the rectangular flue tee 8, the two outlets on the upper part of the rectangular flue tee 8 are respectively connected to one end of the two second variable-section rectangular elbows 9, the other end of the second variable-section rectangular elbow 9 is connected to one end of the corresponding rectangular eccentric reducer 10, the other end of the rectangular eccentric reducer 10 is connected to the shell side flue gas inlet of the corresponding low-temperature economizer 12, and the shell side flue gas outlet of the low-temperature economizer 12 is connected to the flue gas inlet of the corresponding dust collector 15.
[0025] A first non-metallic expansion joint 2 is provided between the flue gas side outlet of the air preheater 1 and the first variable-section rectangular elbow 3, a second non-metallic expansion joint 6 is provided between the uniform-section straight flue 5 and the streamlined special-shaped elbow 7, a third non-metallic expansion joint 11 is provided between the rectangular eccentric reducer 10 and the low-temperature economizer 12, and a fourth non-metallic expansion joint 13 is provided between the low-temperature economizer 12 and the dust collector 15.
[0026] A flue ash hopper 4 is arranged at the lower part of the first variable-section rectangular elbow 3 , and a heating surface ash hopper 14 is arranged at the lower part of the low-temperature economizer 12 .
[0027] The first arc-shaped flow guide device 16 is arranged in the outlet of the air preheater 1 and in the first variable-section rectangular elbow 3, the second arc-shaped flow guide device 17, the symmetrical rectifying grid 18 and the asymmetrical rectifying grid 19 are arranged in the rectangular flue tee 8, the third arc-shaped flow guide device 20 is arranged in the second variable-section rectangular elbow 9, and the eccentric rectifying grid 21 is arranged in the inlet of the rectangular eccentric reducer 10.
[0028] The center line of the original flue coincides with the center line of the tee, and is eccentric to the center line of the dust collector 15, with an eccentric distance greater than 2000 mm.
[0029] A streamlined, shaped elbow 7 is used to connect the uniform-section straight flue 5 and the rectangular flue tee 8. This allows the centerline of the modified flue tee to coincide with the centerline of the dust collector 15, facilitating uniform distribution of the flue gas flow at the inlet of the low-temperature economizer 12. The streamlined, shaped elbow 7 consists of two uniform-section elbows with opposite bends and a section of uniform-section straight flue. The angle between the streamlined elbow 7 and the centerline of the rectangular flue tee 8 is between 20° and 25°.
[0030] The second variable cross-section rectangular elbow 9 is divided into four sections with gradually enlarging cross-sectional areas to prevent a sudden decrease in flue gas velocity from causing dust accumulation. At the same time, the cross-sectional area of the second variable cross-section rectangular elbow 9 is gradually enlarged, which is conducive to a uniform flue gas flow field.
[0031] The flaring angle of the rectangular eccentric reducer 10 is less than 30° and should not exceed 45° to prevent the sudden decrease in the flue gas flow rate from causing ash accumulation.
[0032] The low-temperature economizer 12 is arranged at the inlet bell mouth of the dust collector 15 and is directly connected to the bell mouth of the dust collector 15 through the fourth non-metallic expansion joint 13, so that the dust accumulated in the area of the low-temperature economizer 12 directly enters the dust collector 15, reducing the dust accumulation on the heating surface and flue of the low-temperature economizer 12.
[0033] The symmetrical rectifying grid 18 and the asymmetrical rectifying grid 19 are respectively arranged in the rectangular flue tee 8 and on one side close to the original flue center line and the other side away from the original flue center line.
[0034] During operation, the flue gas first flows through the third arc-shaped flow guide device 20 , then flows through the eccentric rectifying grid 21 , and enters the low-temperature economizer 12 through the rectangular eccentric reducer 10 .
[0035] The specific working process of the present invention is:
[0036] The flue gas output from the air preheater 1 enters the first variable-section rectangular elbow 3 through the first non-metallic expansion joint 2. Under the guiding action of the first arc-shaped guide device 16, the flue gas flow field entering the uniform-section straight flue 5 is kept uniform. The uniform-section straight flue 5 is connected to the rectangular flue tee 8 by a streamlined special-shaped elbow 7. On the one hand, the streamlined special-shaped elbow 7 can make the center line of the flue tee coincide with the center line of the dust collector 15 after the flue modification, which is conducive to the uniform distribution of the flue gas flow at the inlet of the low-temperature economizer 12 on both sides. On the other hand, it can make the flue gas flow evenly along the streamline direction. A second arc-shaped guide device 17, a symmetrical rectifying grid 18 and an asymmetrical rectifying grid 19 are arranged in the rectangular flue tee 8. The second arc-shaped guide device 17 is arranged symmetrically, with the symmetrical rectifying grid 18 arranged on the side close to the original flue center line and the asymmetrical rectifying grid 19 arranged on the side away from the original flue center line. By matching the flue gas flow resistance on both sides, the flue gas flow entering the low-temperature economizers 12 on both sides is evenly distributed while ensuring the uniformity of the flue gas flow field. The flue gas flows through the second variable-section rectangular elbow 9, the third arc-shaped flow guide device 20, the eccentric rectifying grid 21 and the rectangular eccentric reducer 10 in sequence and enters the low-temperature economizer 12 for heat exchange.
[0037] Along the flue gas flow direction, the cross-sectional areas of the second variable-section rectangular elbow 9 and the rectangular eccentric reducer 10 gradually increase to prevent sudden drops in flue gas velocity that could cause ash accumulation and promote uniform flue gas diffusion. Simultaneously, the flue gas is guided by the third curved flow guide 20 and rectified by the eccentric rectifier grid 21, improving the uniformity of the flue gas flow field at the inlet of the low-temperature economizer 12.
[0038] The flue gas enters the dust collector 15 after heat exchange in the low-temperature economizer 12. The low-temperature economizer 12 is arranged at the inlet bell mouth of the dust collector 15. The dust accumulated in the low-temperature economizer 12 area can directly enter the dust collector 15, reducing the dust accumulation on the heating surface of the low-temperature economizer 12 and the flue.
Claims
1. A low-temperature economizer flue system, characterized in that: The invention comprises an air preheater (1), a first variable-section rectangular elbow (3), a straight flue of uniform cross section (5), a streamlined special-shaped elbow (7), a rectangular flue tee (8), a first arc-shaped flow guide device (16), a second arc-shaped flow guide device (17), a symmetrical rectifying grid (18), an asymmetrical rectifying grid (19), a third arc-shaped flow guide device (20), an eccentric rectifying grid (21), two second variable-section rectangular elbows (9), two rectangular eccentric reducers (10), two low-temperature economizers (12) and two dust collectors (15), wherein one second variable-section rectangular elbow (9) corresponds to one rectangular eccentric reducer (10), one low-temperature economizer (12) and one dust collector (15); The flue gas outlet of the air preheater (1) is connected to the lower end of the first variable cross-section rectangular elbow (3), the upper end of the first variable cross-section rectangular elbow (3) is connected to the lower end of the uniform cross-section straight flue (5), the upper end of the uniform cross-section straight flue (5) is connected to the lower end of the streamlined special-shaped elbow (7), the upper end of the streamlined special-shaped elbow (7) is connected to the lower part of the rectangular flue tee (8), the two outlets of the upper part of the rectangular flue tee (8) are respectively connected to one end of two second variable cross-section rectangular elbows (9), the other end of the second variable cross-section rectangular elbow (9) is connected to one end of the corresponding rectangular eccentric reducer (10), the other end of the rectangular eccentric reducer (10) is connected to the shell side flue gas inlet of the corresponding low-temperature economizer (12), and the shell side flue gas outlet of the low-temperature economizer (12) is connected to the flue gas inlet of the corresponding dust collector (15); The first arc-shaped flow guide device (16) is arranged in the outlet of the air preheater (1) and in the first variable-section rectangular elbow (3); the second arc-shaped flow guide device (17), the symmetrical flow rectifying grid (18) and the asymmetrical flow rectifying grid (19) are arranged in the rectangular flue tee (8); the third arc-shaped flow guide device (20) is arranged in the second variable-section rectangular elbow (9); and the eccentric flow rectifying grid (21) is arranged in the inlet of the rectangular eccentric reducer (10); The streamlined special-shaped elbow (7) is composed of two elbows with equal cross-sections and opposite bending directions and a straight flue with equal cross-sections. The angle between the streamlined special-shaped elbow (7) and the center line of the rectangular flue tee (8) is 20° to 25°. The flaring angle of the rectangular eccentric reducer (10) is less than 30°.
2. The low-temperature economizer flue system according to claim 1, characterized in that: A first non-metallic expansion joint (2) is provided between the flue gas side outlet of the air preheater (1) and the first variable-section rectangular elbow (3).
3. The low-temperature economizer flue system according to claim 2, characterized in that: A second non-metallic expansion joint (6) is provided between the straight flue (5) with a uniform cross section and the streamlined special-shaped elbow (7).
4. The low-temperature economizer flue system according to claim 3, characterized in that: A third non-metallic expansion joint (11) is provided between the rectangular eccentric reducer (10) and the low-temperature economizer (12).
5. The low-temperature economizer flue system according to claim 4, characterized in that: A fourth non-metallic expansion joint (13) is provided between the low-temperature economizer (12) and the dust collector (15).
6. The low-temperature economizer flue system according to claim 1, characterized in that: A flue ash collecting hopper (4) is arranged at the lower part of the first variable-section rectangular elbow (3), and a heating surface ash collecting hopper (14) is arranged at the lower part of the low-temperature economizer (12).