CN217875840U - Air-gas mixing device and combustion system - Google Patents

Abstract

The utility model relates to an air-gas mixing arrangement and combustion system, this air-gas mixing arrangement includes: a mixing chamber; a gas input part communicated with the mixing cavity; at least two air passages in communication with the mixing chamber; the air flowing from the at least two air channels can inject the fuel gas input from the fuel gas input part into the mixing cavity. The utility model discloses a venturi effect that two at least air ducts produced draws the gas to penetrate to the hybrid chamber in, when guaranteeing load, can also realize the homogeneous mixing of air and gas in the extremely short distance, has guaranteed combustion system's the emission to reach standard of ignition success rate and flue gas.

Description

Air-gas mixing device and combustion system

Technical Field

The utility model relates to a gas hot water technical field especially relates to an air-gas mixing arrangement and combustion system.

Background

In a gas water heater, for example, a hot water boiler generally adopts a pre-mixing burner, after air and a single-hole venturi device of a gas channel are mixed before a fan, mixed gas is conveyed to a combustion chamber to be ignited together for combustion. The pre-premixing system has higher requirements on the specification of the fan (an explosion-proof fan is needed), the price is also higher, and boiler products are limited by limited fan types and are difficult to expand to product types with higher load.

It is therefore considered to provide a mixing device for air and gas downstream of the fan to form a post-premixed combustion system. However, the venturi device for mixing air and gas is arranged at the outlet of the fan (namely: a post-premixing system), and has two technical problems to be overcome: 1. because the back premixing combustion system obviously improves the negative pressure of the throat of the venturi, and the throat can not suck enough fuel gas, the input load of the whole machine is insufficient, the wind resistance of the combustion system is required to be as small as possible, and the throat needs to generate enough negative pressure to meet the input of enough fuel gas, so that the whole machine can meet the operation requirement of the load; 2. the ignition success rate of the combustion system and the performance and reliability requirements of the combustion system such as reaching the standard of smoke emission need to be considered, so that the uniform mixing of air and fuel gas needs to be realized within a limited distance. The existing single-hole Venturi structure, the Venturi structure with a turning plate and the like can not meet the requirements.

Therefore, the inventor provides an air-gas mixing device and a combustion system by virtue of experience and practice of related industries for many years, so as to overcome the defects in the prior art.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide an air-gas mixing arrangement and combustion system, the venturi effect that produces through two at least air ducts will satisfy the gas that the load volume required and draw and penetrate to the hybrid chamber, when guaranteeing load, can also realize the homogeneous mixing of air and gas in the extremely short distance, guaranteed combustion system's the emission up to standard of ignition success rate and flue gas.

The purpose of the utility model can be realized by adopting the following technical scheme:

the utility model provides an air-gas mixing arrangement, air-gas mixing arrangement includes:

a mixing chamber;

the gas input part is communicated with the mixing cavity;

at least two air passages in communication with the mixing chamber;

the air flowing in from the at least two air channels can inject the fuel gas input from the fuel gas input part into the mixing cavity.

In a preferred embodiment of the present invention, the air-gas mixing device further comprises:

a mixing member in which the mixing chamber is formed;

the fuel gas inlet is arranged on the mixing component and is communicated with the mixing cavity and the fuel gas input part;

the ejection part is formed by matching the outlets of the at least two air channels with the fuel gas inlet; the injection part can enable the fuel gas entering the fuel gas inlet to be injected into the mixing cavity by the air flowing out of the outlets of the at least two air channels.

In a preferred embodiment of the present invention, the air-gas mixing device further comprises at least two air input pipes, and the air channel is formed in the air input pipes; the at least two air input pipes have a gap between them.

In a preferred embodiment of the present invention, the gap distance between the at least two air input pipes is 0.1 times to 0.9 times the distance between the central axes of the at least two air input pipes.

In a preferred embodiment of the present invention, the mixing chamber inlet includes at least two mutually isolated gas inlets, and the at least two mutually isolated gas inlets correspond to the outlets of the at least two air passages.

In a preferred embodiment of the present invention, the gas inlet is a part of the mixing chamber inlet, and the outlets of the at least two air passages and at least a part of the gas inlet are located in the same plane to cooperate to form the injecting part.

In a preferred embodiment of the present invention, the air input pipe is located outside the mixing chamber, and the outlets of the at least two air passages are located at the upstream of the gas inlet to cooperate to form the injection portion.

In a preferred embodiment of the present invention, the air inlet pipe passes through the mixing chamber inlet and extends into the mixing chamber, and the outlets of the at least two air passages are located at the downstream of the gas inlet to cooperate to form the injection part.

In a preferred embodiment of the present invention, the flow area of the mixing chamber inlet is 1.1 times to 2.1 times the flow area of the air channel outlet.

In a preferred embodiment of the present invention, at least one protrusion is provided on the inner wall of the air inlet pipe and at least near the outlet of the air inlet pipe.

In a preferred embodiment of the present invention, at least one recess is provided on the outer wall of the air inlet pipe and at least near the outlet of the air inlet pipe.

In a preferred embodiment of the present invention, the air-gas mixing device further comprises:

an air input component comprising the at least two air input tubes;

the casing, the gas input part is located on the casing, the air input part with mixing unit at least part set up in the casing, the air input part with mixing unit is located part in the casing includes at least draw the portion of penetrating.

In a preferred embodiment of the present invention, a gas passage is formed between the inner wall of the housing and the air input part and the mixing part, and the gas passage communicates with the gas input part and the gas inlet.

In a preferred embodiment of the present invention, an air chamber is formed in the air input part, and the at least two air passage inlets are communicated with the air chamber.

In a preferred embodiment of the present invention, the mixing component is provided with an outlet communicated with the mixing chamber, and the outlet of the mixing chamber is opposite to the inlet of the mixing chamber.

The utility model provides a combustion system, combustion system includes fan and foretell air-gas mixing arrangement, air-gas mixing arrangement connect in the low reaches or the upper reaches of fan.

In a preferred embodiment of the present invention, the combustion system further includes a burner, the air channel inlet of the air-gas mixing device is connected to the air outlet of the fan, and the mixed gas outlet of the air-gas mixing device is connected to the inlet of the burner.

In a preferred embodiment of the present invention, a gap formed between at least two air input pipes in the air-gas mixing device is formed by an angle smaller than 45 ° from the gas input portion to the extending direction away from the gas input portion.

In a preferred embodiment of the present invention, the shape of the inlet of the air chamber in the air-gas mixing device matches the shape of the outlet of the fan.

In a preferred embodiment of the present invention, the combustion system further includes a burner, the mixed gas outlet of the air-gas mixing device is connected to the air inlet of the fan, and the air outlet of the fan is connected to the inlet of the burner.

From the above, the utility model discloses an air-gas mixing arrangement and combustion system's characteristics and advantage are: the utility model discloses a gas is sent into to the hybrid chamber to the gas input portion that is linked together with the hybrid chamber, and send into the air to the hybrid chamber through the air passage who is linked together with the hybrid chamber, the air that flows in through the air passage can draw the gas of gas input portion input to penetrate to get into the hybrid chamber and mix, the venturi effect that produces through two at least air passages draws the gas that satisfies the load requirement to penetrate to the hybrid chamber in, the air of flowing through every air passage is fast rather than drawing the gas intensive mixing who penetrates the correspondence that gets into, air passage's quantity is more, the better mixing effect is better, when guaranteeing the load requirement, also guaranteed that the gas mixture just has accomplished the intensive mixing before reacing the combustor, better mixing effect also satisfies the product design requirement of each aspect such as combustion system's ignition success rate and lower fume emission.

Drawings

The following drawings are only intended to illustrate and explain the present invention, and do not limit the scope of the present invention. Wherein:

FIG. 1: is one of the partial sectional views of the air-gas mixing device of the utility model.

FIG. 2 is a schematic diagram: is one of the front cross-sectional views of the air-gas mixing device of the utility model.

FIG. 3: is a second partial sectional view of the air-gas mixing device of the present invention.

FIG. 4 is a schematic view of: is a second front sectional view of the air-gas mixing device of the present invention.

FIG. 5: is one of the exploded schematic diagrams of the air-gas mixing device of the present invention.

FIG. 6: is the third front cross section of the air-gas mixing device of the utility model.

FIG. 7: is the second exploded schematic diagram of the air-gas mixing device of the present invention.

FIG. 8: is the third partial sectional view of the air-gas mixing device of the utility model.

FIG. 9: do the utility model discloses the perspective view of preceding premix mode among the combustion system.

FIG. 10: do the front view of the combustion system with the pre-mixing mode.

FIG. 11: do the utility model discloses before among the combustion system decompose the schematic diagram of mixing the mode in advance.

FIG. 12: do the utility model discloses the front view of back premix mode among the combustion system.

FIG. 13: do the utility model discloses the decomposition schematic diagram of back premix mode among the combustion system.

The utility model provides a reference numeral does:

1. a mixing component; 101. A mixing chamber;

102. a gas inlet; 103. An inlet of the mixing chamber;

104. an outlet of the mixing chamber; 2. A gas input section;

3. an air input pipe; 301. An air passage;

302. a convex portion; 303. A recess;

4. an air input component; 401. An air chamber;

5. a housing; 6. A gas channel;

10. an air-gas mixing device; 20. A fan;

30. a burner.

Detailed Description

In order to clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in fig. 1 to 8, the utility model provides an air-gas mixing device, this air-gas mixing device include hybrid chamber 101, gas input part 2 and two at least air passages 301, and gas input part 2 and two at least air passages 301 are linked together with hybrid chamber 101 respectively, and the air that flows in from two at least air passages 301 can draw the gas of following the 2 input of gas input part to penetrate and get into hybrid chamber 101, mixes.

The utility model discloses in, send into the gas through 2 gas input portions that are linked together with mixing chamber 101 in to mixing chamber 101, and through the air passage 301 that is linked together with mixing chamber 101 inflow air in to mixing chamber 101, the air that flows in through air passage 301 can draw the gas of 2 inputs of gas input portions to penetrate and get into mixing chamber 101 and mix, because air passage 301's quantity is at least two, the air just can draw the gas that gets into with this part air when the initial entering mixing chamber 101 and carry out the intensive mixing, when guaranteeing gas load input capacity, still guaranteed the improvement air, the gas is quick, effective mixture, satisfy combustion system to load, the reliability of ignition and the requirement of flue gas discharge to reach standard.

The utility model discloses an optional embodiment, as shown in fig. 1 to 8, air-gas mixing arrangement still includes hybrid component 1, gas entry 102 and draws the portion of penetrating, mixing chamber 101 is formed in hybrid component 1, gas entry 102 sets up on hybrid component 1, and gas entry 102 is linked together with hybrid chamber 101 and gas input portion 2 respectively, draw the portion of penetrating to form by the export of two at least air passage 301 and gas entry 102 phase-match, draw the portion of penetrating through what form, can make the gas that gets into gas entry 102 draw the air that flows out by two at least air passage 301 exports and draw and penetrate entering mixing chamber 101.

Further, as shown in fig. 1 to 8, the number of the mixing chambers 101 formed in the mixing part 1 is only one, and the input air and the gas are collected in one mixing chamber 101 to be mixed.

In an alternative embodiment of the present invention, as shown in fig. 1 to 8, the air-gas mixing device further includes at least two air input pipes 3, the number of the air input pipes 3 is the same as the number of the air channels 301, and each air channel 301 is formed in the corresponding air input pipe 3; at least two air input pipes 3 are provided with gaps, and the gaps are communicated with the gas inlets 102 at corresponding positions. The gas that inputs through gas input part 2, wherein a part of gas directly gets into mixing chamber 101 through gas entry 102 under the injection effect of injection portion, and another part gas then gets into the clearance between two adjacent air input pipes 3 earlier, later passes through clearance and gas entry 102 under the injection effect of injection portion and gets into mixing chamber 101 in proper order, realizes the mixing of gas and air in mixing chamber 101.

Further, the gap distance between the at least two air input pipes 3 is 0.1 to 0.9 times the distance between the central axes of the at least two air input pipes, so that the mixing proportion of the gas quantity entering the mixing cavity 101 sequentially through the gap and the gas inlet 102 and the air quantity entering the mixing cavity 101 through the air channel 301 can be ensured, the operation requirement of the combustion system can be met, the rapid and effective mixing of the air and the gas can be further ensured, and the product design requirement of the combustion system for meeting the load, the ignition reliability and the smoke emission standard can be finally met.

Further, as shown in fig. 1 to 8, a mixing chamber inlet 103 is provided on the mixing component 1, the mixing chamber inlet 103 is communicated with the mixing chamber 101, the gas enters the mixing chamber 101 through the mixing chamber inlet 103, the air also enters the mixing chamber 101 through the mixing chamber inlet 103 through at least two air input pipes 3, and the air and the gas are fully mixed in the mixer 101. Wherein the mixing chamber inlet 103 comprises at least two mutually isolated gas inlets 102 (i.e. the gas inlets 102 may be part of the mixing chamber inlet 103), and the at least two mutually isolated gas inlets 102 are arranged corresponding to the outlets of the at least two air channels 301. It should be noted that the gas inlets 102 and the outlets of the air channels 301 which are isolated from each other are correspondingly arranged in position, but the number of the gas inlets 102 and the outlets of the air channels 301 is not limited to one-to-one arrangement (i.e. one gas inlet 102 is provided with one outlet of one corresponding air channel 301), and at least two air channels 301 may correspond to one gas inlet 102.

In an optional embodiment of the utility model, as shown in fig. 3 and 4, at least two air input pipes 3 extend towards the mixing chamber inlet 103, and when the air input pipe 3 extends into the mixing chamber inlet 103 (the air input pipe 3 does not enter into the mixing chamber 101), or when the air input pipe 3 extends to the position that the outlet of the air passage 301 is just level with the mixing chamber inlet 103, the partial region of the mixing chamber inlet 103 is occupied along the projection of the extending direction in the outlet of at least two air passages 301, at this moment, at least two mutually isolated gas inlets 102 are the remaining partial region of the mixing chamber inlet 103, so that the injection of the gas through the outlet of the air passage 301, the mixing chamber inlet 103 and the air is used for the mixing chamber inlet 103 and/or forms the injection part near the mixing chamber inlet 103, so as to achieve the effect of injecting the gas into the mixing chamber 101.

Further, as shown in fig. 3 and 4, when the air input pipe 3 extends into the mixing cavity inlet 103 (the air input pipe 3 does not enter the mixing cavity 101), the outlets of at least two air passages 301 are located downstream of the gas inlet 102 to form the above-mentioned injection part in cooperation.

Further, when the air input pipe 3 extends to a position where the outlets of the air passages 301 are flush with the mixing chamber inlet 103 (not shown in the drawings), the gas inlet 102 is a part of the mixing chamber inlet 103, and the outlets of at least two air passages 301 and at least a part of the gas inlet 102 are in the same plane to form the injection part in cooperation.

In another optional embodiment of the present invention, as shown in fig. 1, fig. 2, and fig. 6, at least two air input pipes 3 extend toward the mixing chamber inlet 103, and when the air input pipes 3 do not extend to the mixing chamber inlet 103 (i.e., a certain gap is formed between the outlet of the air channel 301 and the mixing chamber inlet 103 in the extending direction of the air input pipes 3), at this time, the area where the air and gas share the mixing chamber inlet enters the mixing chamber, so that an injection portion is formed at the mixing chamber inlet 103 and/or the position close to the mixing chamber inlet 103 by the outlet of the air channel 301, the mixing chamber inlet 103, and the injection action of the air on the gas, so as to inject the gas into the mixing chamber 101.

Further, as shown in fig. 1, 2 and 6, when the air input pipe 3 does not extend to the mixing chamber inlet 103, the air input pipe 3 is located outside the mixing chamber 101, and the outlets of at least two air passages 301 are located upstream of the gas inlet 102 to cooperatively form the above-mentioned injection portion.

It should be noted that, the outlets of the at least two air channels 301, no matter which position relationship is adopted between the gas inlet 102 and the mixing chamber inlet 103, it is necessary to ensure that the gas flow area of the gas inlet 102 is 1.1 times to 2.1 times of the air flow area of the outlet of the air channel 301, so that the resistance of the gas entering the mixing chamber 101 is the minimum, the air and the gas can smoothly enter the mixing chamber 101 and be fully mixed, the purposes of safety, sufficient combustion and standard emission are achieved, and the input of the gas quantity is ensured to meet the requirements of load and ignition combustion.

In an optional embodiment of the present invention, as shown in fig. 5, 7 and 8, at least one protrusion 302 is disposed on the inner wall of the air input pipe 3 and at the outlet at least close to the air input pipe 3, so that more contact surfaces can be generated with the gas at the outlet close to the air input pipe 3, thereby ensuring better mixing effect.

Further, the convex portion 302 may be an elongated protrusion extending along the axial direction of the air input tube 3, and the convex portion 302 may be disposed by punching through the air input tubes 3 with circular cross-sections arranged in a matrix, so as to form the convex portion 302 between two adjacent rows of the air input tubes 3.

Further, as shown in fig. 5, 7, and 8, at least one concave portion 303 is provided on the outer wall of the air inlet pipe 3 at least near the outlet of the air inlet pipe 3, the concave portion 303 corresponds to the position and shape of the convex portion 302, and a gap through which the gas passes is formed between the two concave portions 303.

In an alternative embodiment of the present invention, as shown in fig. 1 to 8, the air-gas mixing device further comprises an air input part 4 and a housing 5, the air input part 4 comprising at least two air input pipes 3; the casing 5 is the cylindric structure of both ends open-ended, and gas input part 2 is located on the lateral wall of casing 5, as shown in fig. 1-4, and air input part 4 and mixing element 1 set up in casing 5 at least partially, and the part that air input part 4 and mixing element 1 are located casing 5 draws the portion of penetrating at least to reach the air and draw the gas and draw the effect of penetrating to fully mix in mixing chamber 101. Of course, the air input component 4 and the mixing component 1 may be both disposed in the casing 5, the openings at the two ends of the casing 5 are respectively communicated with the inlet of the air input pipe 3 and the outlet 104 of the mixing chamber, so that the input of air and fuel gas, the injection of air to fuel gas and the mixing of air and fuel gas are all performed in the casing 5, and the mixed gas is input into the downstream combustor through the outlet 104 of the mixing chamber for combustion.

Further, as shown in fig. 1 to 4, 6 and 8, an annular gas passage 6 is formed between the inner wall of the casing 5 and the outer surfaces of the air input part 4 and the mixing part 1, the gas passage 6 is communicated with the gas input part 2 and the gas inlet 102, and the gas passage 6 is filled with gas during the mixing process.

Further, as shown in fig. 1 to 8, an air cavity 401 is formed in the air input component 4, inlets of at least two air channels are communicated with the air cavity 401, air firstly enters the air cavity 401 in a concentrated manner, and then enters the at least two air channels 301, and the air cavity 401 plays a role in storing and uniformly distributing the air, so that the air is ensured to be uniformly input into each air channel 301.

Further, as shown in fig. 2, 4 and 6, the mixing component 1 is provided with an outlet (i.e., a mixing chamber outlet 104) communicated with the mixing chamber 101, and the mixing chamber outlet 104 is arranged opposite to the mixing chamber inlet 103, so that the mixed gas can flow out of the mixing chamber outlet 104 along the original flow direction after mixing, and on the premise of ensuring sufficient mixing, the gas flow direction is not changed as much as possible, thereby achieving the purpose of reducing the system resistance.

The utility model discloses an air-gas mixing arrangement's characteristics and advantage are:

1. this air-gas mixing arrangement can inject the gas through a plurality of air passage 301 of looks spaced apart and penetrate into mixing chamber 101 and mix, and the negative pressure that the export of a plurality of air passage 301 produced not only can guarantee the input of enough gas volume, but also guaranteed that the inspiratory gas in export of a plurality of air passage 301 can mix with the air flash mixed that gets into to the effect of air and gas homogeneous mixing in the extremely short distance has been reached.

2. In the air-gas mixing device, the mixing effect of air and gas can be effectively improved by setting the number and the layout mode of the air channels 301, so that the ignition reliability of a combustion system and the standard emission requirement of smoke are ensured.

As shown in fig. 9 to 13, the present invention provides a combustion system, which includes a fan 20 and the above-mentioned air-gas mixing device 10, wherein the air-gas mixing device 10 is connected to the downstream or upstream of the fan 20 to achieve the effect of fully mixing air and gas.

In the combustion system of the utility model, two connection modes of front premixing and rear premixing are provided according to the connection position of the air-gas mixing device 10 and the fan 20, wherein,

the pre-premixing connection mode is as follows: as shown in fig. 12 and 13, the combustion system further includes a burner 30, the mixed gas outlet (i.e., the mixing chamber outlet 104) of the air-gas mixing device 10 is connected to the air inlet of the blower 20, and the air outlet of the blower 20 is connected to the inlet of the burner 30. The gas and the air are mixed in the air-gas mixing device 10 before entering the fan 20, and then enter the burner 30 through the fan 20 to be burned. Because the combustible gas needs to pass through the fan 20 and then enter the combustor 30, the safety of the fan 20 needs to be considered in the connection mode, and an explosion-proof fan is used.

The post-premixing connection mode: as shown in fig. 9 to 11, the combustion system further includes a burner 30, an air passage inlet of the air-gas mixing device 10 is connected to an air outlet of the blower 20, and a mixture outlet (i.e., the mixing chamber outlet 104) of the air-gas mixing device 10 is connected to an inlet of the burner 30. By arranging the air-gas mixing device 10 at the downstream of the fan 20, the fan 20 can provide suction force for the air-gas mixing device 10 in a working state, which is beneficial to improving the formation of negative pressure in the air-gas mixing device 10, thereby ensuring the smooth suction and mixing of gas properly mixed with air; in addition, the explosion-proof problem of the fan 20 does not need to be considered (namely, the explosion-proof fan does not need to be adopted), the cost of the combustion system is favorably reduced, the fan is not limited by the type of the fan, and the fan has better applicability.

Further, the shape of the inlet of the air cavity in the air-gas mixing device 10 is matched with the shape of the air outlet of the fan 20, so that the air-gas mixing device 10 can make full use of the high wind speed of the outlet of the fan 20, the resistance of the mixing device 10 is reduced, and meanwhile, enough negative pressure can be generated in the injection part to ensure the suction of enough gas quantity.

Further, the clearance that forms between two at least air input pipes 3 among the air-gas mixing arrangement 10 becomes to have an contained angle that is less than 45 with the gas input direction by being close to gas input part 2 to the extending direction who keeps away from gas input part 2 to the gas input direction, so that the gas of carrying through gas input part 2 can get into the clearance that forms between two at least air input pipes 3 smoothly, and then in being drawn and penetrate the entering mixing chamber 101, reduce the resistance on the gas input route and guarantee the input of enough gas volume, improve gas delivery efficiency.

The utility model discloses a combustion system's advantage and characteristics are:

the combustion system can inject the fuel gas meeting the load requirement into the mixing cavity 101 through the Venturi effect generated by the at least two mutually separated air channels 301, so that the fuel gas and the air can be uniformly mixed in a very short distance while the load is ensured, the air-fuel gas mixing device is suitable for a post-premixing connection mode of the combustion system, and the ignition success rate of the post-premixing combustion system and the standard emission of the flue gas are ensured; in addition, the air-gas mixing device is also suitable for the front premixing connection mode of the combustion system.

The above description is only exemplary of the present invention, and is not intended to limit the scope of the present invention. Any person skilled in the art should also realize that such equivalent changes and modifications can be made without departing from the spirit and principles of the present invention.

Claims (20)

1. An air-gas mixing device, characterized in that it comprises:

a mixing chamber;

the gas input part is communicated with the mixing cavity;

at least two air passages in communication with the mixing chamber;

the air flowing in from the at least two air channels can inject the fuel gas input from the fuel gas input part into the mixing cavity.

2. The air-gas mixing device of claim 1, further comprising:

a mixing member in which the mixing chamber is formed;

the gas inlet is arranged on the mixing component and communicated with the mixing cavity and the gas input part;

the ejection part is formed by matching the outlets of the at least two air channels with the fuel gas inlet; the injection part can enable the fuel gas entering the fuel gas inlet to be injected into the mixing cavity by the air flowing out of the outlets of the at least two air channels.

3. The air-gas mixing device of claim 2, further comprising at least two air input pipes, the air channel being formed in the air input pipes; the at least two air input pipes have a gap between them.

4. The air-gas mixing device of claim 3, wherein the gap distance of the at least two air inlet pipes is 0.1 to 0.9 times the distance between the central axes of the at least two air inlet pipes.

5. The air-gas mixing device according to claim 3, wherein said mixing chamber inlet comprises at least two mutually isolated gas inlets arranged in correspondence with the outlets of said at least two air passages.

6. The air-gas mixing device of claim 5, wherein the gas inlet is part of the mixing chamber inlet, and the outlets of the at least two air passages are in the same plane as at least part of the gas inlet to cooperate to form the eductor part.

7. The air-gas mixing device according to claim 5, wherein the air inlet duct is located outside the mixing chamber and the outlets of the at least two air passages are located upstream of the gas inlet to cooperate to form the eductor part.

8. The air-gas mixing device of claim 5, wherein the air inlet tube extends into the mixing chamber through the mixing chamber inlet, and the outlets of the at least two air passages are located downstream of the gas inlet to cooperate to form the eductor portion.

9. The air-gas mixing device according to any one of claims 6 to 8, wherein the flow area of the mixing chamber inlet is 1.1 to 2.1 times the flow area of the air channel outlet.

10. An air-gas mixing device according to claim 3, wherein at least one protrusion is provided on the inner wall of the air inlet pipe at least near the outlet of the air inlet pipe.

11. The air-gas mixing device of claim 10, wherein at least one recess is provided on an outer wall of the air inlet pipe at least near an outlet of the air inlet pipe.

12. The air-gas mixing device of claim 2, further comprising:

an air input component comprising the at least two air input tubes;

the casing, the gas input part is located on the casing, the air input part with mixing unit at least part set up in the casing, the air input part with mixing unit is located part in the casing includes at least draw the portion of penetrating.

13. The air-gas mixing device of claim 12, wherein a gas passage is formed between the inner wall of the housing and the air input member and the mixing member, the gas passage communicating with the gas input portion and the gas inlet.

14. The air-gas mixing device of claim 12, wherein an air chamber is formed in the air input member, and the at least two air passage inlets communicate with the air chamber.

15. The air-gas mixing device of claim 2, wherein the mixing element has an outlet in communication with the mixing chamber, the mixing chamber outlet being opposite the mixing chamber inlet.

16. A combustion system, characterized in that it comprises a fan and an air-gas mixing device according to any one of claims 1 to 15, connected downstream or upstream of said fan.

17. The combustion system of claim 16, further comprising a burner, wherein the air channel inlet of the air-gas mixing device is connected to the air outlet of the fan, and the mixture outlet of the air-gas mixing device is connected to the inlet of the burner.

18. The combustion system of claim 17 wherein the gap formed between at least two air inlet tubes in said air-gas mixing device extends from adjacent the gas inlet to remote from said gas inlet at an angle of less than 45 ° to the gas inlet.

19. The combustion system of claim 17, wherein the air chamber in the air-gas mixing device has an inlet shape that matches the shape of the air outlet of the blower.

20. The combustion system of claim 16, further comprising a burner, wherein the mixture outlet of the air-gas mixing device is connected to the air inlet of the blower, and the air outlet of the blower is connected to the inlet of the burner.

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