Novel flue gas and air mixing device
By designing a new type of smoke-air mixing device, the problems of unstable combustion and increased NOx emissions caused by uneven smoke-air mixing were solved, uniform mixing and low-resistance operation under different loads were achieved, and operating costs were reduced.
Patent Information
- Application Number
- CN202422673070.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-04
- Publication Date
- 2025-09-16
- Estimated Expiration
- 2034-11-04
AI Technical Summary
The existing smoke-air mixing device mixes unevenly under high and low loads, resulting in unstable combustion and increased NOx emissions. At the same time, the resistance is large, which increases the operating cost.
A new type of smoke-air mixing device is adopted, including air duct, flue, smoke-air mixer, bluff body and supporting structure. The special design of bluff body and supporting structure is used to achieve uniform mixing of recycled smoke and air, reduce resistance, ensure combustion stability and low NOx emissions.
It achieves uniform mixing of flue gas and air under high and low loads, ensures combustion stability, reduces NOx emissions, reduces fan power consumption, and reduces operating costs.
Smart Images
Figure CN223345382U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of low NOx emission of boilers, in particular to a novel 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 will generally have 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] The technical problem to be solved by the present invention is to provide a new type of smoke-air mixing device, which, by utilizing a special structural design, can fully mix the recycled smoke and air before entering the burner, thereby 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 novel 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. The blunt body comprises a circular plate and a conical body. The blunt body and the smoke-air mixer are fixedly supported to the air duct by the supporting structure respectively. The smoke-air mixer comprises a smoke distribution box and a smoke distribution pipe opening. The smoke distribution pipe openings are respectively located at the center of the side of the flue and are symmetrically arranged in the smoke distribution box. Inner and outer side channels are arranged in the smoke distribution box. The inner channel and the outer channel are connected through the smoke distribution pipe opening. The bottom of the outer channel is connected to the flue. The front and rear ends of the inner channel of the smoke distribution box are open and connected to the air duct. The outlet end of the inner channel faces the conical body of the blunt body.
[0006] Preferably, a guide plate is provided at the elbow of the air duct upstream of the smoke-air mixer.
[0007] Preferably, the cone angle of the conical body of the blunt body is 120°.
[0008] Preferably, the support structure is a cross-shaped support, which is welded to the bluff body and the air duct.
[0009] Preferably, gas expansion holes are provided on the circular plate of the bluff body and on the leeward side of the supporting structure.
[0010] Preferably, the cross-sectional area of the flue gas distribution pipe opening is the same as the cross-sectional area of the flue channel.
[0011] 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.
[0012] The beneficial effects of the utility model are:
[0013] (1) The smoke-air mixing device of the utility model can not only mix the smoke and air evenly under the low-load condition of the boiler, thus meeting the requirements of stable combustion and low NOx emission; at the same time, compared with the conventional smoke-air mixing device, it has the characteristics of relatively small resistance under any load condition and saves electricity consumption.
[0014] (2) The support structure not only provides support for the bluff body and smoke-air mixer, but also plays a turbulent role to a certain extent, improving the mixing degree of smoke and air. In addition, a gas expansion hole is opened on the leeward side of the support pipe to meet the gas expansion requirements. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 It is a structural schematic diagram of the utility model;
[0016] Figure 2 yes Figure 1 A left view of
[0017] Figure 3 yes Figure 1 A cross-sectional view in the AA direction;
[0018] Figure 4 This is a structural diagram of the cone in the present invention;
[0019] Figure 5 This is a structural diagram of a circular plate in the utility model;
[0020] In the figure: 100, air duct, 200, flue, 300, smoke-air mixer, 301, flue gas distribution box, 302, flue gas distribution pipe mouth, 400, blunt body, 401, circular plate, 402, conical body, 500, supporting structure, 600, guide plate, 700, gas expansion hole. DETAILED DESCRIPTION
[0021] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings.
[0022] Example: Figure 1-Figure 5 As shown, a novel 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 and the bluff body are disposed within the air duct. The bluff body comprises a circular plate 401 and a conical body 402. The bluff body and the smoke-air mixer are fixedly supported by the support structure to the air duct. The smoke-air mixer comprises a smoke distribution box 301 and a smoke distribution nozzle 302. The smoke distribution nozzles are located at the center of the side of the flue and are symmetrically arranged within the smoke distribution box. The smoke distribution box is provided with inner and outer channels. The inner and outer channels are connected by the smoke distribution nozzles. The bottom of the outer channel is connected to the flue. The inner channel of the smoke distribution box is open at the front and rear ends and connected to the air duct. The outlet of the inner channel faces the conical body of the bluff body. The smoke distribution nozzle is located at the horizontal centerline of the flue side wall to prevent uneven upper and lower airflow of the smoke, which affects the mixing effect.
[0023] A guide plate 600 is provided at the elbow of the air duct upstream of the smoke-air mixer to avoid eddy currents and uneven distribution of air.
[0024] The cone angle of the blunt body is 120°, which facilitates smooth transition of airflow and creates strong mixing of gas in front of the blunt body and low pressure atmosphere in the rear, achieving a good mixing effect.
[0025] The support structure is a cross-shaped support, welded to the bluff body and the air duct to prevent the air duct and the bluff body from vibrating.
[0026] Gas expansion holes 700 are provided on the circular plate of the bluff body and on the leeward side of the support structure to meet gas expansion requirements. The support structure also acts as a turbulent flow to enhance the mixing of smoke and air.
[0027] The cross-sectional area of the flue gas distribution pipe opening is the same as that of the flue gas channel, ensuring that the resistance does not increase significantly and the flue gas flow rate is within a reasonable range without affecting the mixing effect.
[0028] like Figure 1 As shown, when the new smoke-air mixing device is in use, air flows in through the air duct 100, and the recycled smoke flows out through the smoke distribution box 301 to the smoke distribution pipe 302. The air and smoke are strongly mixed between the smoke-air mixer 300 outlet and the bluff body 400, and finally form a uniform mixed gas that enters the burner.
[0029] 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 new type of smoke and air mixing device, characterized in that: The smoke-air mixer 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. The blunt body comprises a circular plate and a conical body. The blunt body and the smoke-air mixer are fixedly supported on the air duct by the supporting structure respectively. The smoke-air mixer comprises a smoke distribution box and a smoke distribution pipe opening. The smoke distribution pipe openings are respectively located at the center of the side of the flue and are symmetrically arranged in the smoke distribution box. Inner and outer side channels are arranged in the smoke distribution box. The inner channel and the outer channel are connected through the smoke distribution pipe opening. The bottom of the outer channel is connected to the flue. The front and rear ends of the inner channel of the smoke distribution box are open and connected to the air duct. The outlet end of the inner channel faces the conical body of the blunt body.
2. A novel smoke-air mixing device according to claim 1, characterized in that: A guide plate is provided at the elbow of the air duct upstream of the smoke-air mixer.
3. A novel smoke-air mixing device according to claim 1, characterized in that: The cone angle of the conical body of the blunt body is 120°.
4. A novel smoke-air mixing device according to claim 1, characterized in that: The support structure is a cross-shaped support and is welded to the bluff body and the air duct.
5. A novel 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.
6. A novel smoke-air mixing device according to claim 1, characterized in that: The cross-sectional area of the smoke distribution pipe opening is the same as the channel cross-sectional area of the smoke duct.