CN112610366B

CN112610366B - Multi-point type gas injection mixing system of gas engine

Info

Publication number: CN112610366B
Application number: CN202011525167.1A
Authority: CN
Inventors: 张旭龙
Original assignee: Individual
Current assignee: Zhang Xulong
Priority date: 2020-12-22
Filing date: 2020-12-22
Publication date: 2021-09-21
Anticipated expiration: 2040-12-22
Also published as: CN112610366A

Abstract

A multi-point gas injection mixing system of a gas engine comprises a gas injection valve, a multi-way pipe, an air inlet pipe, a mixing pipe and a mixed flow piece; the input end of the gas injection valve is connected with a connecting pipe, the multi-way pipe is provided with an input end and a plurality of output ends, a plurality of gas conveying pipes are communicated between the input end of the multi-way pipe and the output end of the gas injection valve, the gas inlet pipes are in one-to-one correspondence with the output ends of the multi-way pipe, two ends of each gas inlet pipe are respectively communicated with the output end of the multi-way pipe and the mixing pipe, and a plurality of communicated positions of the plurality of gas inlet pipes and the mixing pipe are uniformly arranged around the central shaft of the mixing pipe; the front side of the mixing pipe is an air inflow end, and the rear side of the mixing pipe is a gas and air mixed gas outflow end; the mixed flow piece is of a rotary structure, the mixed flow piece and the mixing pipe are coaxially arranged, and the mixed flow piece is connected with the inner wall of the mixing pipe. The invention can mix the fuel gas and the air uniformly for the engine, and improves the utilization rate of the fuel gas energy.

Description

Multi-point type gas injection mixing system of gas engine

Technical Field

The invention relates to the technical field of gas engines, in particular to a multi-point type gas injection mixing system of a gas engine.

Background

As a clean energy source, the fuel gas has the advantages of wide source, low price and the like, and is an ideal alternative fuel for the internal combustion engine. The gas engine belongs to a heat engine, takes gas as a power source, and is an environment-friendly engine.

When the existing gas engine mixes gas and air in a multi-point injection mixing mode, the gas is simply injected to an air circulation position and cannot be uniformly mixed with the air, so that the engine cannot effectively utilize mixed gas to manufacture power, and the utilization rate of gas energy is low.

Disclosure of Invention

Objects of the invention

In order to solve the technical problems in the background art, the invention provides a multi-point gas injection mixing system of a gas engine, which can uniformly mix gas and air for the use of the engine and improve the utilization rate of gas energy.

(II) technical scheme

The invention provides a multi-point gas injection mixing system of a gas engine, which comprises a gas injection valve, a multi-way pipe, an air inlet pipe, a mixing pipe and a mixed flow piece, wherein the gas injection valve is arranged on the multi-way pipe;

the input end of the gas injection valve is connected with a connecting pipe, the multi-way pipe is provided with an input end and a plurality of output ends, a plurality of gas conveying pipes are communicated between the input end of the multi-way pipe and the output end of the gas injection valve, the gas inlet pipes are in one-to-one correspondence with the output ends of the multi-way pipe, two ends of each gas inlet pipe are respectively communicated with the output end of the multi-way pipe and the mixing pipe, and a plurality of communicated positions of the plurality of gas inlet pipes and the mixing pipe are uniformly arranged around the central shaft of the mixing pipe; the front side of the mixing pipe is an air inflow end, and the rear side of the mixing pipe is a gas and air mixed gas outflow end; the mixed flow piece is of a rotary structure, the mixed flow piece and the mixing pipe are coaxially arranged, the mixed flow piece is connected with the inner wall of the mixing pipe, the connection position is positioned at the rear side of the connection position of the air inlet pipe and the mixing pipe, the mixed flow piece comprises a guide groove and a diversion surface, the guide groove and the diversion surface are connected and arranged along the direction from the gas-air mixed gas outlet end to the air inlet end, a primary mixed circulation channel is formed between the connection position and the inner wall of the mixing pipe, the other side end part of the guide groove, which is opposite to the side end where the diversion surface is positioned, is contacted with the inner wall of the mixing pipe, the guide groove is an annular groove, the guide groove is gradually inwards sunken along the directions from the front side to the rear side to the middle part, a first mixing area is formed between the guide groove and the inner wall of the mixing pipe, a second mixing area is formed on the inner side of the mixed flow piece, a plurality of first, the flow dividing surface is gradually bent towards the air inflow end from the radial two ends to the middle part, a second through hole is formed in the mixed flow piece and is located at one end, far away from the guide groove, of the flow dividing surface, and the second through hole and the mixing pipe are coaxially arranged.

Preferably, the multi-way pipe is a four-way pipe, and the plurality of air inlet pipes are a first air inlet pipe, a second air inlet pipe and a third air inlet pipe respectively.

Preferably, the direction of giving vent to anger of intake pipe inclines to the reposition of redundant personnel face direction along the direction from the multi-pass pipe to the mixing tube gradually.

Preferably, the first through holes are inclined towards the front side of the mixed flow piece gradually along the direction from the air inlet end to the air outlet end, and the inclination angles of the plurality of first through holes are gradually increased from back to front.

Preferably, a guide ring is coaxially arranged on the inner wall of the mixing pipe, the guide ring is positioned on the outer peripheral side of the joint of the guide groove and the flow dividing surface, an air circulation channel is formed between the guide ring and the flow mixing piece, and the guide ring comprises a second guide surface used for guiding air flowing from the flow dividing surface to the first mixing area and a first guide surface used for guiding gas flowing from the guide groove to the first mixing area and preventing gas-air mixed gas in the first mixing area from flowing back through the air circulation channel.

Preferably, the inner side surface of the mixed flow piece is provided with a plurality of separation strips along the axial direction in a fitting manner, two ends of each separation strip are respectively located at two side edges of the mixed flow piece, the separation strips are uniformly arranged around the central shaft of the mixed flow piece, a gas circulation channel is formed between every two adjacent separation strips, and the gas circulation channel is located on the inner side of the first through hole.

Preferably, the division strip is provided with two inner inclined planes, the two inner inclined planes are arranged in a radial symmetry mode relative to the flow mixing piece, the gas circulation channel is an area between two adjacent inner inclined planes on two adjacent division strips, and the size of the gas circulation channel in the radial inward direction of the flow mixing piece is gradually reduced.

Preferably, the inner side surface of the mixed flow piece is provided with a positioning groove, and the separation strip is provided with a positioning table for embedding the positioning groove.

Preferably, the operation steps are as follows:

s1, supplying air into the mixing pipe from the air inflow end, blowing the air to the second through hole and the flow dividing surface, and respectively flowing the air divided by the flow dividing surface to the second through hole and the primary mixing flow channel; simultaneously, a gas injection valve is opened, receives gas through a connecting pipe and conveys the gas to a multi-way pipe through a gas conveying pipe;

s2, conveying the fuel gas to the guide grooves uniformly through the multi-way pipe and the air inlet pipe, wherein a part of the fuel gas flows in the first mixing area along the guide grooves, and the air flowing from the primary mixing flow channel is primarily mixed with the part of the fuel gas in the first mixing area; the rest fuel gas and the fuel gas-air mixed gas after primary mixing circulate from the first mixing area to the second mixing area through the first through hole, and are mixed for the second time in the circulating process; and is mixed with the air circulating from the second through hole for the third time in the second mixing area;

and S3, the gas-air mixed gas after the three mixing processes flows out of the second mixing area and is conveyed out through the gas-air mixed gas outflow end.

Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects: the invention can mix the fuel gas and the air uniformly for the engine, and improves the utilization rate of the fuel gas energy. When the fuel gas circulates into the mixing pipe from the plurality of gas inlet pipes, the fuel gas can be uniformly sprayed to the guide groove, because the gas circulation has the coanda effect, the fuel gas can uniformly circulate along the surface of the guide groove, and the air can be distributed uniformly in the first mixing area and the second mixing area through the distribution surface; the gas and the air can be uniformly distributed and are more uniformly mixed after being uniformly distributed, so that the uniform mixing degree of the gas and the air is effectively ensured; gas and air can carry out the primary mixing in first mixed zone, and the gas of primary mixing can circulate to the second mixed zone in from first mixed zone through first through-hole along with partly direct to carry out the secondary mixing at the circulation in-process, the gas through the secondary mixing can carry out the tertiary mixing with the air that flows through from the second through-hole, and the gas-air mixture's after the tertiary mixing misce bene degree is high.

Drawings

Fig. 1 is a schematic structural diagram of a multi-point gas injection hybrid system of a gas engine according to the present invention.

Fig. 2 is a sectional view showing an internal structure of a multi-point gas injection hybrid system of a gas engine according to the present invention.

Fig. 3 is an enlarged view of the structure of fig. 2 at a.

Fig. 4 is an enlarged view of the structure of fig. 2 at B according to the present invention.

Fig. 5 is a schematic diagram of a distribution structure of a first air inlet pipe, a second air inlet pipe and a third air inlet pipe in a multi-point gas injection hybrid system of a gas engine according to the present invention.

Fig. 6 is a schematic structural diagram of a mixed flow member in a multi-point gas injection hybrid system of a gas engine according to the present invention.

Fig. 7 is a schematic structural diagram of a guide ring in a multi-point gas injection hybrid system of a gas engine according to the present invention.

Fig. 8 is a schematic structural diagram of a guide strip in a multi-point gas injection hybrid system of a gas engine according to the present invention.

Fig. 9 is a schematic view showing the gas and air flow directions of the multi-point gas injection hybrid system of the gas engine without the guide ring according to the present invention.

Fig. 10 is a schematic view showing the gas and air flow directions when the guide ring is installed in the multi-point gas injection hybrid system of the gas engine according to the present invention.

Reference numerals: 1. a gas injection valve; 101. a connecting pipe; 102. a gas delivery pipe; 2. a four-way pipe; 301. a first intake pipe; 302. a second intake pipe; 303. a third intake pipe; 4. a mixing tube; 5. a flow mixing member; 51. a guide groove; 52. a flow dividing surface; 501. a first through hole; 502. a second through hole; 503. a first mixing zone; 504. a second mixing zone; 505. positioning a groove; 6. a guide ring; 601. a first guide surface; 602. a second guide surface; 7. a dividing strip; 701. an inner bevel; 8. a positioning table; 91. the gas flow direction; 92. the direction of air circulation; 93. the flow direction of the mixed gas.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings in conjunction with the following detailed description. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention.

As shown in fig. 1-10, the multi-point gas injection hybrid system of a gas engine according to the present invention includes a gas injection valve 1, a multi-way pipe, an air inlet pipe, a hybrid pipe 4 and a flow mixer 5;

the input end of the gas injection valve 1 is connected with a connecting pipe 101, the multi-way pipe is provided with an input end and a plurality of output ends, a plurality of gas conveying pipes 102 are communicated between the input end of the multi-way pipe and the output end of the gas injection valve 1, the gas inlet pipes correspond to the output ends of the multi-way pipe one by one, two ends of each gas inlet pipe are respectively communicated with the output ends of the multi-way pipe and the mixing pipe 4, and a plurality of communicated positions of the plurality of gas inlet pipes and the mixing pipe 4 are uniformly arranged around the central shaft of the mixing pipe 4; the front side of the mixing pipe 4 is an air inflow end, and the rear side of the mixing pipe 4 is a gas and air mixed gas outflow end; the mixed flow piece 5 is a rotary structure, the mixed flow piece 5 and the mixing pipe 4 are coaxially arranged, the mixed flow piece 5 is connected with the inner wall of the mixing pipe 4, the connection position is positioned at the rear side of the connection position of the air inlet pipe and the mixing pipe 4, the mixed flow piece 5 comprises a guide groove 51 and a diversion surface 52, the guide groove 51 and the diversion surface 52 are connected and arranged along the direction from the gas-air mixed gas outlet end to the air inlet end, an initial mixed circulation channel is formed between the connection position and the inner wall of the mixing pipe 4, the other side end part of the guide groove 51 opposite to the side end of the diversion surface 52 is contacted with the inner wall of the mixing pipe 4, the guide groove 51 is an annular groove, the guide groove 51 is gradually inwards sunken along the directions from the front side to the middle part, a first mixing area 503 is formed between the guide groove 51 and the inner wall of the mixing pipe 4, a second mixing area 504 is formed on the inner side surface of the mixed flow piece 5, a plurality of first through holes 501 for communicating the first mixing area 503 and the second mixing area 504 are uniformly arranged on the bottom of the guide groove 51, the shunting surface 52 is an arc surface, the shunting surface 52 is gradually bent towards the air inflow end along the direction from the two radial ends to the middle part, the mixed flow piece 5 is provided with a second through hole 502, the second through hole 502 is positioned at one end of the shunting surface 52 far away from the guide groove 51, and the second through hole 502 and the mixing pipe 4 are coaxially arranged.

In an alternative embodiment, the multi-way pipe is a four-way pipe 2, and the plurality of air inlet pipes are a first air inlet pipe 301, a second air inlet pipe 302 and a third air inlet pipe 303 respectively, so that the gas can be uniformly conveyed into the mixing pipe 4 from three directions.

In an alternative embodiment, the gas outlet direction of the inlet pipe is gradually inclined towards the diversion surface 52 along the direction from the multi-way pipe to the mixing pipe 4, and the gas flowing from the inlet pipe to the mixing pipe 4 can uniformly circulate on the guide groove 51 and be uniformly distributed.

In an optional embodiment, the first through holes 501 are inclined toward the front side of the flow mixing member 5 from the inlet end to the outlet end, and the inclination angles of the first through holes 501 are gradually increased from back to front, so that the gas and the gas-air mixed gas after primary mixing can enter the second mixing area 504 from the first mixing area 503 more smoothly, which is more beneficial to mixing of the gas and improves the mixing efficiency.

In an alternative embodiment, the inner wall of the mixing tube 4 is coaxially provided with a guide ring 6, the guide ring 6 is located at the outer periphery side where the guide groove 51 and the diverging surface 52 join, an air flow passage is formed between the guide ring 6 and the flow mixing member 5, the guide ring 6 includes a second guide surface 602 for guiding the air flowing from the diverging surface 52 to the first mixing region 503, thereby enabling the gas to be circularly mixed with the air in the first mixing area 503, ensuring the mixing effect, and a first guide surface 601 for guiding the gas flown from the guide groove 51 into the first mixing zone 503 and preventing the gas-air mixture gas in the first mixing zone 503 from flowing backward through the air flow passage, so that the air and the gas can be sufficiently mixed in the first mixing zone 503, and the reverse flow along the direction opposite to the air circulation direction from the air circulation channel can not be generated, and the mixing efficiency and the effect are ensured.

It should be noted that the gas flowing direction 91 is indicated by a V-shaped arrow, the air flowing direction 92 is indicated by a hollow arrow, and the mixed gas flowing direction 93 is indicated by a solid arrow, and the flowing process of the three types of gases can be visually seen in the drawing, and after the guide ring 6 is arranged, the gas backflow can be prevented, and the gas mixing efficiency and effect can be improved.

In an optional embodiment, the inner side surface of the mixed flow piece 5 is provided with a plurality of separation strips 7 in an axially attached manner, two ends of each separation strip 7 are respectively located at two side edges of the mixed flow piece 5, the separation strips 7 are uniformly arranged around the central axis of the mixed flow piece 5, a gas circulation channel is formed between every two adjacent separation strips 7 and is located inside the first through hole 501, and gas and air mixed gas circulates at the gas circulation channel and can be distributed more uniformly, so that the gas and the air which circulate from the second through hole 502 can be further mixed for the third time.

In an alternative embodiment, two inner inclined surfaces 701 are arranged on the division bar 7, the two inner inclined surfaces 701 are arranged in a radial symmetry manner with respect to the flow mixing piece 5, the gas flow passage is an area between two adjacent inner inclined surfaces 701 on two adjacent division bars 7, and the size of the gas flow passage along the radial inward direction of the flow mixing piece 5 is gradually reduced, so that the gas-air mixture can flow at the gas flow passage more smoothly.

In an alternative embodiment, the flow mixing element 5 is provided with a positioning groove 505 on the inner side surface, and the division bar 7 is provided with a positioning platform 8 for embedding the positioning groove 505, so that the arrangement of the division bar 7 is convenient to position, the division bar 7 is uniformly distributed, and the connection of the division bar 7 and the flow mixing element 5 is convenient.

In an alternative embodiment, the operation steps are as follows:

s1, supplying air into the mixing tube 4 from the air inflow end, the air blowing to the second through hole 502 and the diversion surface 52, the air diverted by the diversion surface 52 flowing to the second through hole 502 and the primary mixing flow channel, respectively; simultaneously, the gas injection valve 1 is opened, the gas injection valve 1 receives gas through the connecting pipe 101 and transmits the gas to the multi-way pipe through the gas transmission pipe 102, and therefore the gas can be uniformly distributed in the guide groove 51;

s2, the fuel gas is uniformly conveyed to the guide groove 51 through the multi-way pipe and the air inlet pipe, a part of the fuel gas circulates in the first mixing area 503 along the guide groove 51, and the air which flows from the primary mixing circulation channel is primarily mixed with the part of the fuel gas in the first mixing area 503; the rest gas and the gas-air mixed gas after the preliminary mixing circulate from the first mixing area 503 to the second mixing area 504 through the first through hole 501, and are mixed for the second time in the circulating process; and is mixed with the air circulating from the second through-hole 502 for the third time in the second mixing zone 504; after the three components are mixed, the gas and the air are mixed more uniformly;

s3, the gas-air mixture after the third mixing process flows out from the second mixing area 504 and is delivered out through the gas-air mixture outflow end for engine operation.

The invention can mix the fuel gas and the air uniformly for the engine, and improves the utilization rate of the fuel gas energy. When the gas flows into the mixing pipe 4 from the plurality of gas inlet pipes, the gas can be uniformly sprayed to the guide groove 51, because the gas flows through the coanda effect, the gas can uniformly flow along the surface of the guide groove 51, and the air can be divided by the dividing surface 52 to be uniformly distributed in the first mixing area 503 and the second mixing area 504; the gas and the air can be uniformly distributed and are more uniformly mixed after being uniformly distributed, so that the uniform mixing degree of the gas and the air is effectively ensured; the gas and the air can be primarily mixed in the first mixing area 503, the primarily mixed gas can directly flow into the second mixing area 504 from the first mixing area 503 through the first through hole 501 along with a part of the gas, and is secondarily mixed in the flowing process, the secondarily mixed gas can be secondarily mixed with the air flowing from the second through hole 502, and the gas-air mixed gas after tertiary mixing is high in mixing uniformity.

It is to be understood that the above-described embodiments of the present invention are merely illustrative of or explaining the principles of the invention and are not to be construed as limiting the invention. Therefore, any modification, equivalent replacement, improvement and the like made without departing from the spirit and scope of the present invention should be included in the protection scope of the present invention. Further, it is intended that the appended claims cover all such variations and modifications as fall within the scope and boundaries of the appended claims or the equivalents of such scope and boundaries.

Claims

1. A multi-point gas injection mixing system of a gas engine is characterized by comprising a gas injection valve (1), a multi-way pipe, an air inlet pipe, a mixing pipe (4) and a mixed flow piece (5);

the input end of the gas injection valve (1) is connected with a connecting pipe (101), the multi-way pipe is provided with one input end and a plurality of output ends, a plurality of gas conveying pipes (102) are communicated between the input end of the multi-way pipe and the output end of the gas injection valve (1), the gas inlet pipes are arranged in a plurality, the gas inlet pipes correspond to the output ends of the multi-way pipe one by one, two ends of each gas inlet pipe are respectively communicated with the output ends of the multi-way pipe and the mixing pipe (4), and a plurality of communicated positions of the plurality of gas inlet pipes and the mixing pipe (4) are uniformly arranged around the central shaft of the mixing pipe (4); the front side of the mixing pipe (4) is an air inflow end, and the rear side of the mixing pipe (4) is a gas-air mixed gas outflow end; the mixed flow piece (5) is of a rotary structure, the mixed flow piece (5) and the mixing pipe (4) are coaxially arranged, the mixed flow piece (5) is connected with the inner wall of the mixing pipe (4), the connection position is positioned at the rear side of the communication position of the air inlet pipe and the mixing pipe (4), the mixed flow piece (5) comprises a guide groove (51) and a flow dividing surface (52), the guide groove (51) and the flow dividing surface (52) are connected and arranged along the direction from the gas-air mixed gas outlet end to the air inlet end, a primary mixed circulation channel is formed between the connection position and the inner wall of the mixing pipe (4), the other side end part, opposite to the end on the side where the flow dividing surface (52) is positioned, of the guide groove (51) is in contact with the inner wall of the mixing pipe (4), the guide groove (51) is an annular groove, the guide groove (51) is gradually inwards sunken along the direction from the front side to the middle part, a first mixing area (503) is formed between the guide groove (51) and the inner wall of the mixing pipe (4), the inboard second mixed region (504) that forms of mixed flow piece (5) medial surface, guide way (51) tank bottom evenly is provided with a plurality of first through-holes (501) that are used for communicateing first mixed region (503) and second mixed region (504), reposition of redundant personnel face (52) are the arcwall face, reposition of redundant personnel face (52) are along being crooked to the air inflow end gradually by radial both ends to middle part direction, be provided with second through-hole (502) on mixed flow piece (5), one end that guide way (51) were kept away from in second through-hole (502) lie in reposition of redundant personnel face (52), second through-hole (502) and mixing tube (4) coaxial setting.

2. The multipoint gas injection hybrid system of a gas engine as claimed in claim 1, wherein the multi-way pipe is a four-way pipe (2), and the plurality of inlet pipes are a first inlet pipe (301), a second inlet pipe (302) and a third inlet pipe (303), respectively.

3. The multipoint gas injection mixing system of the gas engine as claimed in claim 1, wherein the outlet direction of the inlet pipe is gradually inclined toward the diverging surface (52) in the direction from the multi-way pipe to the mixing pipe (4).

4. A multi-point gas injection mixing system of a gas engine according to claim 3, wherein the first through holes (501) are inclined toward the front side of the flow mixing member (5) gradually in a direction from the inlet end to the outlet end, and the inclination angles of the plurality of first through holes (501) are gradually increased from the rear to the front.

5. The multipoint gas injection mixing system of the gas engine according to claim 1, wherein the inner wall of the mixing tube (4) is coaxially provided with a guide ring (6), the guide ring (6) is positioned at the outer peripheral side of the junction of the guide groove (51) and the diverging surface (52), an air flow passage is formed between the guide ring (6) and the mixing member (5), the guide ring (6) comprises a second guide surface (602) for guiding the air flowing from the diverging surface (52) to the first mixing region (503), and a first guide surface (601) for guiding the air flowing from the guide groove (51) to the first mixing region (503) and preventing the gas-air mixture gas in the first mixing region (503) from flowing back through the air flow passage.

6. The multi-point gas injection mixing system of the gas engine according to claim 1, wherein a plurality of separation strips (7) are axially attached to the inner side surface of the mixed flow member (5), two ends of each separation strip (7) are respectively located at two side edges of the mixed flow member (5), the separation strips (7) are uniformly arranged around the central axis of the mixed flow member (5), a gas flow passage is formed between every two adjacent separation strips (7), and the gas flow passage is located inside the first through hole (501).

7. A multi-point gas injection hybrid system for a gas engine according to claim 6, characterized in that the inner side of the flow mixer (5) is provided with a positioning groove (505), and the division bar (7) is provided with a positioning table (8) for embedding the positioning groove (505).

8. A multi-point gas injection hybrid system for a gas engine according to any one of claims 1 to 7, characterized by the following operating steps:

s1, supplying air into the mixing pipe (4) from the air inflow end, blowing the air to the second through hole (502) and the flow dividing surface (52), and respectively flowing the air divided by the flow dividing surface (52) to the second through hole (502) and the primary mixing flow channel; simultaneously, the gas injection valve (1) is opened, the gas injection valve (1) receives gas through the connecting pipe (101) and transmits the gas to the multi-way pipe through the gas transmission pipe (102);

s2, the fuel gas is uniformly conveyed to the guide groove (51) through the multi-way pipe and the air inlet pipe, a part of the fuel gas circulates in the first mixing area (503) along the guide groove (51), and air which flows from the primary mixing circulation channel is primarily mixed with the part of the fuel gas in the first mixing area (503); the rest fuel gas and the fuel gas-air mixed gas after primary mixing circulate from the first mixing area (503) to the second mixing area (504) through the first through hole (501), and are mixed for the second time in the circulating process; and is mixed for the third time with the air circulated from the second through hole (502) in the second mixing zone (504);

and S3, the gas-air mixed gas after the three mixing processes flows out of the second mixing area (504) and is conveyed out through the gas-air mixed gas outflow end.