Smoke and air mixing device
By designing a strong vortex structure and support structure for the smoke-air mixing device, the problems of unstable combustion at low load and increased NOx emissions in the boiler were solved, achieving combustion stability and low-cost operation.
Patent Information
- Application Number
- CN202422175004.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2025-09-16
- Estimated Expiration
- 2034-09-05
AI Technical Summary
The existing smoke-air mixing device has unstable combustion when the boiler is running at low load, resulting in increased NOx emissions and large resistance, which increases the company's operating costs.
A smoke-air mixing device is designed, which adopts a strong vortex structure composed of a mixing cylinder, a necked cylinder and a blunt body, combined with a supporting structure to achieve uniform mixing of recycled smoke and air and reduce resistance.
It achieves combustion stability and low NOx emissions under low load conditions, reduces fan power consumption and saves operating costs.
Smart Images
Figure CN223345381U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of low NOx emission of boilers, in particular to a smoke-air mixing device. Background Art
[0002] In the field of gas-fired boilers, in order to reduce the initial emission concentration of NOx, gas-fired boilers generally choose to use flue gas recirculation technology to meet national emission standards. Especially when the boiler is running at low load, due to factors such as unstable combustion and uneven mixing of fuel and air, local over-oxygen combustion will occur, leading to increased NOx emissions. The flue gas recirculation technology mainly introduces the flue gas from the boiler outlet into the burner inlet air duct to reduce the oxygen content and thus reduce NOx emissions. However, the uneven mixing of recycled flue gas and air will cause the burner to extinguish, causing certain economic losses to the enterprise. For this reason, the degree of sufficient mixing of recycled flue gas and air determines the key to combustion stability and NOx emissions. At the same time, if the existing smoke and air mixing device requires uniform mixing of smoke and air at both high and low loads, the mixer itself generally has a large resistance, which will increase the pressure head of the blower and the recirculation fan, increasing the operating costs of the enterprise. The above problems have always been problems that need to be solved urgently in this field. Utility Model Content
[0003] In order to solve the above technical problems, the utility model designs a smoke-air mixing device. By utilizing a special structural design, the recycled smoke and air can be fully mixed before entering the burner, ensuring stable operation of the burner and the initial NOx emission target. At the same time, the smoke-air mixing device has low resistance and, compared with conventional smoke-air mixing devices, has the advantage of saving fan power consumption and reducing operating costs.
[0004] The utility model adopts the following technical solutions:
[0005] A smoke-air mixing device comprises an air duct, a flue, a smoke-air mixer, a blunt body and a supporting structure. The smoke-air mixer and the blunt body are arranged in the air duct, and the smoke-air mixer and the blunt body are fixedly supported to the air duct by the supporting structure respectively. The smoke-air mixer comprises a mixing cylinder, a necked cylinder and a smoke branch. The mixing cylinder and the necked cylinder are arranged parallel to the air duct, and the end of the mixing cylinder is fixedly connected to the necked cylinder. The necked opening of the necked cylinder faces the conical body of the blunt body. The necked cylinder and the blunt body form a strong vortex structure. The mixing cylinder is connected to the flue through the smoke branch.
[0006] Preferably, the front and rear ends of the mixing cylinder are straight.
[0007] Preferably, the angle between the flue gas branch and the mixing cylinder is 60°.
[0008] Preferably, the necking angle of the necked cylinder and the taper angle of the blunt body are 60° and 120° respectively.
[0009] Preferably, the extension line of the necked barrel busbar intersects with the blunt body busbar at 1 / 2.
[0010] Preferably, the support structure is a cross-shaped support, which is welded to the bluff body, the air duct and the smoke-air mixing device respectively.
[0011] Preferably, the cross-sectional area between the blunt body and the necked cylinder is greater than the cross-sectional area of the necked cylinder.
[0012] Preferably, gas expansion holes are provided on the circular plate of the bluff body and on the leeward side of the supporting structure.
[0013] The beneficial effects of the present invention are as follows: (1) the smoke-air mixing device of the present invention can not only make the smoke and air mix evenly under the low-load working condition of the boiler, thus meeting the requirements of stable combustion and low NOx emission; at the same time, compared with conventional smoke-air mixing devices, it has relatively small resistance under any load condition, thus saving power consumption; (2) the smoke-air mixer is assembled and welded in the factory by the mixing cylinder, the necking cylinder and the smoke branch, and then shipped as an integral module, providing convenient on-site installation conditions; (3) the supporting structure not only provides support for the blunt body and the smoke-air mixer, but also plays a turbulent role to a certain extent, thereby improving the mixing degree of the smoke and air. In addition, a gas expansion hole needs to be opened on the leeward side of the support pipe to meet the gas expansion requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a structural schematic diagram of the utility model;
[0015] Figure 2 yes Figure 1 Cross-sectional view in the AA direction;
[0016] Figure 3 This is a structural diagram of the cone in the present invention;
[0017] Figure 4 This is a structural diagram of a circular plate in the utility model;
[0018] In the figure: 100, air duct, 200, flue, 300, smoke-air mixer, 301, mixing cylinder, 302, necked cylinder, 303, flue gas branch, 400, blunt body, 401, circular plate, 402, conical body, 500, supporting structure, 600, gas expansion hole. DETAILED DESCRIPTION
[0019] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:
[0020] Example: Figures 1-4As shown, a smoke-air mixing device includes an air duct 100, a flue duct 200, a smoke-air mixer 300, a bluff body 400, and a support structure 500. The smoke-air mixer 300 includes a mixing cylinder 301, a conical cylinder 302, and a smoke branch 303; the bluff body 400 includes a circular plate 401 and a conical body 402; gas expansion holes 600 are opened on the circular plate 401 and on the leeward side of the support structure 500.
[0021] A smoke-air mixer and a blunt body are arranged in the air duct. The smoke-air mixer and the blunt body are fixedly supported to the air duct through a supporting structure respectively. The smoke-air mixer includes a mixing cylinder, a necking cylinder and a smoke branch. The mixing cylinder and the necking cylinder are arranged parallel to the air duct. The end of the mixing cylinder is fixedly connected to the necking cylinder. The necking of the necking cylinder faces the conical body of the blunt body. The necking cylinder and the blunt body form a strong vortex structure. The mixing cylinder is connected to the flue through the smoke branch.
[0022] The mixing cylinder is straight from front to back and is not sealed. The air duct resistance here is very small, and part of the air and smoke can be pre-mixed.
[0023] The included angle between the flue gas branch and the main mixing cylinder is 60°, which reduces the backflow of some recirculated flue gas from the upstream inlet of the mixing cylinder.
[0024] The necking angle of the necked cylinder is 60°, forming a strong vortex structure with the blunt body with a cone angle of 120°, which enhances the mixing effect of the recycled flue gas and air. The extension line of the necked cylinder busbar should intersect with the blunt body busbar at about 1 / 2 to ensure the vortex intensity.
[0025] The utility model proposes that the supporting structure is welded with the air duct and the smoke-air mixing device, so as to prevent the air duct, the smoke-air mixer and the blunt body from vibrating.
[0026] The cross-sectional area between the blunt body and the tapered cylinder should be slightly higher than the cross-sectional area of the tapered cylinder, again ensuring the low resistance characteristics of the smoke-air mixing device.
[0027] Gas expansion holes are provided on the leeward side of the circular plate and the supporting structure to meet the gas expansion requirements. At the same time, the supporting structure plays a certain role in turbulence, improving the mixing degree of smoke and air.
[0028] After adopting the smoke-air mixing device of the utility model, the air and recirculated smoke are evenly mixed, the boiler combustion is stable, and NOx emissions meet the standard regardless of high or low load conditions. At the same time, the smoke-air mixing device has low resistance, saves fan power consumption, and reduces operating costs.
[0029] When the smoke-air mixing device is in use, air flows in through air duct 100 and is primarily divided into two paths: a small portion of air enters the mixing cylinder 301 of the smoke-air mixer 300, while the majority of air enters the gap between the mixing cylinder 301 and the air duct 100. Recirculated smoke passes through the flue duct 200 and the flue gas branch 301 and enters the smoke-air mixer 300. The three gases are intensely mixed between the outlet of the tapered cylinder 302 and the blunt body 400, ultimately forming a uniform mixed gas that enters the burner.
[0030] The embodiment described above is only a preferred solution of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.
Claims
1. A smoke-air mixing device, characterized in that: It includes an air duct, a flue, a smoke-air mixer, a blunt body and a supporting structure. The smoke-air mixer and the blunt body are arranged in the air duct, and the smoke-air mixer and the blunt body are fixedly supported to the air duct through the supporting structure respectively. The smoke-air mixer includes a mixing cylinder, a necking cylinder and a flue gas branch. The mixing cylinder and the necking cylinder are arranged parallel to the air duct. The end of the mixing cylinder is fixedly connected to the necking cylinder. The necking of the necking cylinder faces the conical body of the blunt body. The necking cylinder and the blunt body form a strong vortex structure. The mixing cylinder is connected to the flue through the flue gas branch.
2. A smoke-air mixing device according to claim 1, characterized in that: The front and rear ends of the mixing cylinder are straight.
3. The smoke-air mixing device according to claim 1, characterized in that: The included angle between the smoke branch and the mixing cylinder is 60°.
4. The smoke-air mixing device according to claim 1, characterized in that: The necking angle of the necked cylinder and the taper angle of the blunt body are 60° and 120° respectively.
5. The smoke-air mixing device according to claim 1, characterized in that: The extension line of the necked barrel busbar intersects with the 1 / 2 position of the blunt body busbar.
6. The smoke-air mixing device according to claim 1, characterized in that: The support structure is a cross-shaped support, which is welded to the bluff body, the air duct and the smoke-air mixing device respectively.
7. The smoke-air mixing device according to claim 1, characterized in that: The cross-sectional area between the blunt body and the necked cylinder is greater than the cross-sectional area of the necked cylinder.
8. The smoke-air mixing device according to claim 1, characterized in that: Gas expansion holes are provided on the circular plate of the bluff body and on the leeward side of the supporting structure.