A new type of air premixed flue gas internal circulation ultra-low emission gas combustion device

Abstract

The application discloses a novel air premixing flue gas internal circulation ultra-low emission gas combustion device and relates to the technical field of burners.The application solves the problem of excessive initial emission of nitrogen oxides of the existing gas boiler.The main flame injection nozzle is externally sleeved with a main flame gas nozzle;the main flame gas nozzle is provided with a plurality of flue gas entraining holes;the air passage end is provided with an air passage necking portion;the end of the duty flame gas pipe extends into the gas mixing cylinder and is provided with a plurality of duty flame short pipes at the end;the duty flame gas pipe is internally provided with a duty flame nozzle;and the air premixing holes are arranged on the front pipe wall of the duty flame nozzle.The application completes the partial air premixing in the duty flame gas pipe, improves the duty class gas combustion speed, introduces the flue gas into the combustion device, increases the inert gas content in the combustion zone, dilutes the oxygen concentration through heat absorption of the flue gas, reduces the combustion speed and temperature, and thus inhibits the generation of NOx.

Description

Technical Field

[0001] This invention relates to the field of burner technology, specifically to a novel air-premixed flue gas internal circulation ultra-low emission gas combustion device. Background Technology

[0002] Compared to coal, natural gas combustion produces lower emissions of sulfur dioxide and particulate matter, and its carbon dioxide emissions are significantly lower than those of coal and petroleum fuels. However, due to the high combustion temperature, nitrogen oxide emissions are a prominent issue during natural gas combustion. Nitrogen oxides are among the most significant atmospheric pollutants, contributing not only to photochemical smog but also being a major contributor to ozone layer depletion, posing serious threats to the ecological environment and human health. However, the development of oil and gas burners in my country lags behind that of other countries. In recent years, my country's environmental protection requirements have become increasingly stringent, with many developed provinces and cities proposing stricter NOx emission standards, requiring urban gas-fired boilers to control NOx emissions to 30 mg / m³. 3 However, the initial nitrogen oxide emissions of the vast majority of currently used gas-fired boilers are generally between 150 and 200 mg / m³. 3 The levels of nitrogen oxides (NOx) in the initial emissions are severely exceeding standards. With the implementation of new boiler emission standards, low-NOx control has received significant attention from governments at all levels and the public. Therefore, there is a need to develop a gas burner device that can effectively control the initial NOx emissions. Summary of the Invention

[0003] To address the aforementioned problem of excessive initial nitrogen oxide emissions from existing gas-fired boilers, this invention proposes a novel air-premixed flue gas internal circulation ultra-low emission gas combustion device. This invention utilizes a narrowed air passage and the high-speed fluid ejection effect created by the main flame ejector nozzle to introduce flue gas into the furnace through the main flue gas inlet, rear flue gas entrainment hole, and front flue gas entrainment hole. This increases the inert gas content in the combustion zone. Because the flue gas absorbs heat and dilutes the oxygen concentration, the combustion rate and temperature decrease, thereby suppressing NOx formation.

[0004] This invention proposes a novel air-premixed flue gas internal circulation ultra-low emission gas combustion device, which specifically includes a standby flame gas pipe, a burner air box, a main gas passage, an air passage, a main flame support frame, several main flame gas pipes, several main flame gas nozzles, a gas mixing cylinder, and a standby sleeve. The burner air box and the air passage are connected. The main gas passage and the main flame support frame are concentrically arranged around the outer ring of the air passage, and the main gas passage and the main flame support frame are connected. After passing through the main flame support frame, the air passage has an air passage constriction at its end. Several main flame gas pipes are arranged inside the main flame support frame. One end of each main flame gas pipe is connected to the main gas passage, and the other end passes through the main flame support frame and has a main flame ejector nozzle at its end. The main flame ejector nozzle is fitted with a main flame gas nozzle. Several flue gas entrainment holes are provided on the main flame gas nozzle. The gas mixing cylinder is fitted outside the standby flame gas pipe and inside the several main flame gas nozzles, and is located in front of the air passage constriction.

[0005] The duty flame gas pipe passes through the center of the burner air box and air passage and extends into the gas mixing cylinder; the duty sleeve is fitted on the duty flame gas pipe, and the front end of the duty sleeve extends out of the gas mixing cylinder; several duty flame short pipes are provided on the duty flame gas pipe, and several duty flame short pipes are set inside the duty sleeve.

[0006] The duty flame gas pipe is equipped with a duty flame nozzle inside, and several air premixing holes are provided on the pipe wall in front of the duty flame nozzle.

[0007] Furthermore, the air passage is provided with several isolation plates, which are mounted on the duty flame gas pipe. Duty flame venturis are provided on the inner side of the isolation plates at positions corresponding to several air premixing holes.

[0008] Furthermore, a radial injection port for the duty flame is provided on the side wall of the end of the duty flame short tube.

[0009] Furthermore, the plurality of flue gas entrainment holes include a plurality of rear flue gas entrainment holes and a plurality of front flue gas entrainment holes. The plurality of rear flue gas entrainment holes are disposed on the main flame gas nozzle pipe wall on the outer periphery of the main flame ejector nozzle, and the plurality of front flue gas entrainment holes are disposed on the main flame gas nozzle pipe wall in front of the main flame ejector nozzle.

[0010] Furthermore, the width of the rear smoke entrainment hole is greater than that of the front smoke entrainment hole, and the length of the rear smoke entrainment hole is less than that of the front smoke entrainment hole.

[0011] Furthermore, the gas mixing cylinder is provided with a main flue gas inlet at one end facing the narrowing of the air channel, and an air vent at the other end.

[0012] Furthermore, the end of the duty flame gas pipe is provided with duty swirl vanes.

[0013] Furthermore, the duty flame short tube passes through the duty swirl blade.

[0014] Furthermore, the duty swirl blades are provided with several duty flame axial injection holes.

[0015] Furthermore, several swirl vanes are provided between the duty sleeve and the gas mixing cylinder.

[0016] The beneficial effects of the novel air-premixed flue gas internal circulation ultra-low emission gas combustion device described in this invention are as follows:

[0017] (1) The novel air premixed flue gas internal circulation ultra-low emission gas combustion device of the present invention divides the gas into the duty flame and the main flame through the set duty flame gas pipe and the main flame gas delivery pipe, completes the fuel classification, controls the equivalent ratio of the combustion zone, i.e. the flame temperature, thereby suppressing the main thermal NO in NOx during the combustion process.

[0018] (2) The novel air premixed flue gas internal circulation ultra-low emission gas combustion device of the present invention completes part of the air premixing inside the duty flame gas pipe through components such as duty flame gas pipe, air channel, isolation plate, duty flame venturi, duty flame nozzle, and air premixing hole, thereby improving the combustion speed of the duty flame gas and providing support and guarantee for the combustion of the main flame gas nozzle.

[0019] (3) The novel air-premixed flue gas internal circulation ultra-low emission gas combustion device of the present invention introduces flue gas into the combustion device through the high-speed fluid formed by the air channel narrowing and the main flame ejector nozzle, through the main flue gas entrainment inlet, the rear flue gas entrainment hole and the front flue gas entrainment hole, thereby increasing the inert gas content in the combustion zone. Because the flue gas absorbs heat and dilutes the oxygen concentration, the combustion speed and temperature are reduced, thereby inhibiting the formation of NOx. Attached Figure Description

[0020] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0021] In the attached diagram:

[0022] Figure 1 This is a schematic diagram of the structure of a novel air-premixed flue gas internal circulation ultra-low emission gas combustion device according to the present invention;

[0023] Figure 2 This is a side view of a novel air-premixed flue gas internal circulation ultra-low emission gas combustion device according to the present invention;

[0024] Figure 3 This is a schematic diagram of the main flame gas nozzle of a novel air-premixed flue gas internal circulation ultra-low emission gas combustion device according to the present invention.

[0025] The components are: 1-Stationary flame gas pipe, 2-Burner air box, 3-Main flame gas delivery pipe, 4-Main gas passage, 5-Air passage, 6-Isolation plate, 7-Stationary flame nozzle, 8-Stationary flame venturi, 9-Air premixing hole, 10-Isolation plate support, 11-Main flame support frame, 12-Main flame support plate, 13-Main flame ejector nozzle, 14-Air passage narrowing, 15-Rear flue gas entrainment hole, 16-Main flue gas entrainment inlet, 17-Front flue gas entrainment hole, 18-Main flame gas nozzle, 19-Main flame venturi, 20-Swirl vane, 21-Gas mixing cylinder, 22-Stationary sleeve, 23-Stationary flame short pipe, 24-Stationary flame radial injection hole, 25-Air flare, 26-Stationary flare, 27-Stationary swirling vane, 28-Stationary flame axial injection hole, 29-Main flame gas pipe. Detailed Implementation

[0026] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings:

[0027] Specific implementation method one: See Figures 1-3This embodiment is described in detail. The novel air-premixed flue gas internal circulation ultra-low emission gas combustion device described in this embodiment specifically includes a standby flame gas pipe 1, a burner air box 2, a main gas passage 4, an air passage 5, a main flame support frame 11, several main flame gas pipes 29, several main flame gas nozzles 18, a gas mixing cylinder 21, and a standby sleeve 22. The burner air box 2 and the air passage 5 are connected to provide oxygen for the combustion process. The main gas passage 4 and the main flame support frame 11 are concentrically arranged on the outer ring of the air passage 5. One end of the main gas passage 4 is connected to the burner air box 2, and the other end is connected to the main flame support frame 11. A main flame support plate 12 is provided at the end of the main flame support frame 11, which supports the air passage 5 and the several main flame gas pipes 29. After passing through the main flame support frame 11, the air passage 5 has an air passage constriction 14 at its end, allowing air to flow out of the air passage 5. The flow velocity is increased, forming a high-speed fluid that generates an ejector effect, entraining the smoke gas; the main flame support frame 11 is provided with several main flame gas pipes 29, one end of which is connected to the main gas channel 4, and the other end passes through the main flame support frame 11 and is provided with a main flame ejector nozzle 13 at the end; the several main flame gas pipes 29 are evenly distributed on the outer ring of the air channel 5; the main flame ejector nozzle 13 is fitted with a main flame gas nozzle 18; the main flame gas nozzle 18 is provided with several smoke gas entrainment holes, and the gas is injected into the main flame gas nozzle 18 through the main flame ejector nozzle 13 to increase the gas flow velocity, forming a high-speed fluid that generates an ejector effect, drawing the smoke gas from the front and rear smoke gas entrainment holes into the main flame gas nozzle 18; the gas mixing cylinder 21 is fitted on the outside of the duty flame gas pipe 1 and the inside of several main flame gas nozzles 18, and is located in front of the air channel constriction 14;

[0028] The duty flame gas pipe 1 passes through the center of the burner air box 2 and the air passage 5 and extends into the gas mixing cylinder 21; the duty sleeve 22 is fitted onto the duty flame gas pipe 1, the main body of the duty sleeve 22 is inside the gas mixing cylinder 21, and the duty flare 26 at the front end of the duty sleeve 22 extends out from the front end of the gas mixing cylinder 21; a number of duty flame short pipes 23 are provided on the duty flame gas pipe 1, and the number of duty flame short pipes 23 are provided inside the duty sleeve 22; the duty flame short pipes 23 are L-shaped pipes, the short side of the L-shape of the duty flame short pipe 23 is vertically connected to the duty flame gas pipe 1, and the long side of the L-shape of the duty flame short pipe 23 is parallel to the duty flame gas pipe 1.

[0029] The area of ​​the duty flame gas pipe 1 corresponding to the air channel 5 is equipped with a duty flame nozzle 7. Several air premixing holes 9 are provided on the pipe wall of the duty flame gas pipe 1 in front of the duty flame nozzle 7. Several isolation plates 6 are also provided in the air channel 5. The isolation plates 6 are supported on the duty flame gas pipe 1 by several isolation plate supports 10. Duty flame venturis 8 are provided on the inner side of the isolation plates 6 at the positions corresponding to the several air premixing holes 9. Through the isolation plates 6 and the duty flame venturis 8, some air in the air channel 5 is gathered into the duty flame gas pipe 1. The duty flame gas increases the gas flow rate through the duty flame nozzle 7 to generate an ejector effect, thereby drawing some air in the air channel 5 into the duty flame gas pipe 1 through the several air premixing holes 9 to achieve preliminary premixing.

[0030] The duty flame short pipe 23 is provided with a duty flame radial injection port 24 on the end side wall. The duty flame gas is injected from the duty flame radial injection port 24 into the duty sleeve 22 in the radial direction of the duty flame short pipe 23 to enhance the mixing effect of gas, flue gas and air.

[0031] The plurality of flue gas entrainment holes include a plurality of rear flue gas entrainment holes 15 and a plurality of front flue gas entrainment holes 17. The plurality of rear flue gas entrainment holes 15 are disposed on the pipe wall of the main flame gas injection pipe 18 on the outer periphery of the main flame ejector nozzle 13, and the plurality of front flue gas entrainment holes 17 are disposed on the pipe wall of the main flame gas injection pipe 18 in front of the main flame ejector nozzle 13. When the main combustion stage gas is ejected from the main flame ejector nozzle 13, the flow velocity of the main combustion stage gas increases, becoming a high-speed fluid and generating an ejection effect, drawing the flue gas from the plurality of rear flue gas entrainment holes 15 and the plurality of front flue gas entrainment holes 17 into the main flame gas injection pipe 18; at the same time, a main flame venturi 19 is also disposed on the inner wall of the main flame gas injection pipe 18, which improves the mixing effect of the main combustion stage gas and the flue gas; the width of the rear flue gas entrainment hole 15 is greater than that of the front flue gas entrainment hole 17, and the length of the rear flue gas entrainment hole 15 is less than that of the front flue gas entrainment hole 17.

[0032] The gas mixing cylinder 21 is provided with a main flue gas inlet 16 at one end facing the air channel constriction 14 and an air expansion port 25 at the other end. A certain distance is left between the air channel constriction 14 and the main flue gas inlet 16, so that after the air is accelerated and ejected through the air channel constriction 14, more flue gas can be attracted into the main flue gas inlet 16 through the ejector effect.

[0033] The end of the duty flame gas pipe 1 is provided with a duty swirl vane 27, and a certain gap is left between the edge of the duty swirl vane 27 and the inner wall of the duty sleeve 22. Several duty flame axial injection ports 28 are provided on the duty swirl vane 27. After the flue gas and air pass through the duty swirl vane 27, they rotate in the duty sleeve 22 and fully mix with a part of the duty class gas flow ejected from the duty flame radial injection port 24. Under the action of this part of the gas flow, it rotates forward along the inner wall of the duty sleeve 22. Another part of the duty class gas flow is ejected from the end of the duty flame gas pipe 1 through the several duty flame axial injection ports 28 provided on the duty swirl vane 27, which drives the mixed gas to move forward and extend into the furnace for combustion. At the same time, the duty flare 25 is used to delay its mixing with the external combustion-supporting gas, reduce the formation of the high temperature zone at the nozzle, and generate flame superposition with the gas ejected from the main flame gas pipe 18 at a certain position, which plays a role in stabilizing combustion.

[0034] The position where the duty flame short pipe 23 connects to the duty flame gas pipe 1 is located on one side of the duty swirl vane 27, while the end of the duty flame short pipe 23 with the duty flame radial injection port 24 passes through the duty swirl vane 27, placing it on the other side of the duty swirl vane 27. The mixture of flue gas and air adheres to the inner wall of the duty sleeve 22 and rotates forward after passing through the duty swirl vane 27, while the duty gas ejected from the duty flame radial injection port 24 does not pass through the duty swirl vane 27 and therefore does not rotate. This portion of the duty gas comes into full contact with the flue gas and air, further enhancing the mixing effect between the three gases.

[0035] A number of swirl vanes 20 are provided between the duty sleeve 22 and the gas mixing cylinder 21. The flue gas and air that have not entered the duty sleeve 22 are rotated by the action of the swirl vanes 20, thereby improving the mixing effect of this part of the flue gas and air.

[0036] The main gas pipeline 4 is equipped with a main flame gas delivery pipe 3, which provides main combustion stage gas to the combustion device.

[0037] The specific working process of the novel air-premixed flue gas internal circulation ultra-low emission gas combustion device described in this invention is as follows:

[0038] Gas is introduced into the duty flame gas pipe 1 and the main gas pipe 4, and air is introduced into the combustion device from the burner air box 2. The air passes through the burner air box 2 and the air passage 5 to the air passage constriction 14. Under the action of the air passage constriction 14, the air velocity increases, generating an entrainment effect that drives the external flue gas through the main flue gas entrainment inlet 16 into the gas mixing cylinder 21 for mixing, realizing the primary entrainment of flue gas by air. In the gas mixing cylinder 21, a portion of the mixed gas is rotated and mixed evenly by the action of the swirl vanes 20 and then exits from the air expansion port 25 at the front end of the gas mixing cylinder 21. One portion is directly ejected, while the other portion enters the duty sleeve 22 and mixes with the duty gas. Finally, it is injected into the furnace through the duty flare 26 to aid combustion. The mixing of flue gas reduces the oxygen partial pressure in the combustion-supporting gas, thus reducing NOx formation. Simultaneously, the gas entering from the main gas pipeline 4 passes through the main flame gas pipe 29 and reaches the main flame ejector nozzle 13. From the main flame ejector nozzle 13, it is injected into the main flame gas nozzle 18. Under the action of the main flame ejector nozzle 13, the flow velocity of the main combustion stage gas increases, generating an ejector effect. The gas then passes through several rear flue gas entrainment holes 15 provided on the main flame gas nozzle 18 and... Several front flue gas entrainment holes 17 draw external flue gas into the main flame gas nozzle 18, where it mixes with the main combustion stage gas, achieving secondary entrainment of the flue gas by the gas. The gas and flue gas are uniformly mixed in the main flame gas nozzle 18 via the main flame venturi 19 before being injected into the furnace for combustion. A small amount of flue gas participates in secondary combustion, reducing the flame temperature. The resulting strong internal recirculation increases the mass flow rate of the medium-temperature endothermic working fluid in the flame zone, thereby reducing the amount of nitrogen oxides produced. The standby gas in the standby flame gas pipe 1 flows forward continuously, and at the end of the standby flame gas pipe 1, a portion of the standby gas enters... The gas is ejected from the duty flame short pipe 23 through the duty flame radial injection port 24, where it mixes with the flue gas and air that have been rotated by the duty flame swirl blades 27. The remaining duty flame gas is ejected directly from the duty flame axial injection port 28. The mixed gas inside the duty sleeve 22 rotates along the inner wall of the duty sleeve 22 and extends axially into the furnace for combustion. Under the action of the duty flame flare 26, the mixing with the external combustion-supporting gas is delayed, reducing the formation of the high-temperature zone at the nozzle. At a certain position, it overlaps with the gas ejected from the main flame gas nozzle 18 to achieve flame stabilization.

[0039] In summary, the novel air-premixed flue gas recirculation ultra-low emission gas combustion device of this invention divides the gas into a shift flame and a main combustion stage flame through a shift flame gas pipe 1 and a main flame gas delivery pipe 3, thereby completing fuel grading and controlling the equivalence ratio of the combustion zone, i.e., the flame temperature, thus suppressing the main thermal NO in NOx during combustion. The novel air-premixed flue gas recirculation ultra-low emission gas combustion device of this invention utilizes components such as the shift flame gas pipe 1, air passage 5, isolation plate 6, shift flame venturi 8, shift flame nozzle 7, and air premixing orifice 9 to achieve shift flame combustion. The flame gas pipe 1 completes partial air premixing inside, improving the combustion speed of the gas during operation and providing support and guarantee for the combustion of the main flame gas nozzle 18. The novel air premixed flue gas internal circulation ultra-low emission gas combustion device of the present invention, through the ejection effect of the high-speed fluid formed by the air channel constriction 14 and the main flame ejector nozzle 13, introduces the flue gas into the combustion device through the main flue gas entrainment inlet 16, the rear flue gas entrainment hole 15, and the front flue gas entrainment hole 17, which increases the inert gas content in the combustion zone. Because the flue gas absorbs heat and dilutes the oxygen concentration, the combustion speed and temperature are reduced, thereby inhibiting the formation of NOx.

[0040] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the invention. They can also be reasonable combinations of the features described in the above embodiments. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A novel air-premixed flue gas internal circulation ultra-low emission gas combustion device, characterized in that: The system includes a standby flame gas pipe (1), a burner air box (2), a main gas passage (4), an air passage (5), a main flame support frame (11), several main flame gas pipes (29), several main flame gas nozzles (18), a gas mixing cylinder (21), and a standby sleeve (22). The burner air box (2) and the air passage (5) are connected. The main gas passage (4) and the main flame support frame (11) are concentrically arranged on the outer ring of the air passage (5). The main gas passage (4) and the main flame support frame (11) are connected. The air passage (5) passes through the main flame support frame (11) and has an air passage at its end. The main flame support frame (11) is equipped with several main flame gas pipes (29). One end of the main flame gas pipe (29) is connected to the main gas passage (4), and the other end passes through the main flame support frame (11) and is equipped with a main flame ejector nozzle (13) at the end. The main flame ejector nozzle (13) is fitted with a main flame gas nozzle (18) on the outside. Several flue gas suction ports are provided on the main flame gas nozzle (18). The gas mixing cylinder (21) is fitted outside the duty flame gas pipe (1) and inside the several main flame gas nozzles (18), and is located in front of the air passage narrowing (14). The duty flame gas pipe (1) passes through the center of the burner wind box (2) and the air passage (5) and extends into the gas mixing cylinder (21); the duty sleeve (22) is fitted on the duty flame gas pipe (1), and the front end of the duty sleeve (22) extends out of the gas mixing cylinder (21); a number of duty flame short pipes (23) are provided on the duty flame gas pipe (1), and the number of duty flame short pipes (23) are provided inside the duty sleeve (22); The duty flame gas pipe (1) is equipped with a duty flame nozzle (7), and the duty flame gas pipe (1) in front of the duty flame nozzle (7) is equipped with several air premixing holes (9). The plurality of flue gas suction ports include a plurality of rear flue gas suction holes (15) and a plurality of front flue gas suction holes (17). The plurality of rear flue gas suction holes (15) are disposed on the pipe wall of the main flame gas injection pipe (18) on the outer periphery of the main flame ejector nozzle (13), and the plurality of front flue gas suction holes (17) are disposed on the pipe wall of the main flame gas injection pipe (18) in front of the main flame ejector nozzle (13). The width of the rear flue gas suction holes (15) is greater than that of the front flue gas suction holes (17), and the length of the rear flue gas suction holes (15) is less than that of the front flue gas suction holes (17). The end of the duty flame gas pipe (1) is provided with a duty swirl vane (27); the duty flame short pipe (23) passes through the duty swirl vane (27); a gap is provided between the edge of the duty swirl vane (27) and the inner wall of the duty sleeve (22); A radial jet nozzle (24) for the duty flame is provided on the side wall of the end of the duty flame short tube (23).

2. The novel air-premixed flue gas internal circulation ultra-low emission gas combustion device according to claim 1, characterized in that: The air passage (5) is provided with several isolation plates (6), which are mounted on the duty flame gas pipe (1). The duty flame venturi (8) is provided on the inner side of the isolation plate (6) at the position corresponding to several air premixing holes (9).

3. The novel air-premixed flue gas internal circulation ultra-low emission gas combustion device according to claim 1 or 2, characterized in that: The gas mixing cylinder (21) is provided with a main flue gas inlet (16) at one end facing the air channel constriction (14), and an air vent (25) at the other end.

4. The novel air-premixed flue gas internal circulation ultra-low emission gas combustion device according to claim 1, characterized in that: The duty swirling blade (27) is provided with several duty flame axial injection holes (28).

5. The novel air-premixed flue gas internal circulation ultra-low emission gas combustion device according to claim 1, characterized in that: Several swirl blades (20) are provided between the duty sleeve (22) and the gas mixing cylinder (21).

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