Fire grate, burner and water heater

Abstract

The application discloses a fire grate, a burner and a water heater, and relates to the technical field of water heaters. The fire grate comprises a fire grate body provided with a first air inlet channel, a mixing chamber and a fire hole. The first air inlet channel is provided with a first air inlet. The exhaust end of the first air inlet channel, the mixing chamber and the fire hole are sequentially communicated. A flow guide member is arranged on the fire grate body. The flow guide member and the fire grate body surround to form a second air inlet channel. The second air inlet channel is provided with a second air inlet. The second air inlet channel comprises a first channel section, a second channel section and a third channel section which are sequentially arranged from the second air inlet to the mixing chamber. The flow area of the first channel section is gradually reduced towards the side close to the second channel section. The flow area of the second channel section is gradually increased towards the side close to the third channel section. The third channel section is communicated with the mixing chamber. The technical scheme of the application can improve the air content in the fire grate, improve the mixing degree of the gas and the air, realize sufficient combustion, and reduce the emission of nitrogen oxides in the flue gas.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water heaters, in particular to a fire grate, a burner and a water heater. BACKGROUND

[0002] The conventional fire grate of the burner usually has the problems of insufficient ejection air content, and insufficient mixing of the gas and air in the process of ejection and flow inside the fire grate, which finally leads to insufficient combustion and excessive emission of nitrogen oxides in flue gas. SUMMARY

[0003] The main purpose of the present application is to provide a fire grate, a burner and a water heater, which aims to solve the problems of easy insufficient combustion and excessive emission of nitrogen oxides in flue gas of the conventional fire grate.

[0004] To achieve the above-mentioned purpose, the fire grate provided by the present application comprises:

[0005] a fire grate body provided with a first air inlet channel, a mixing chamber and a fire hole, the first air inlet channel is provided with a first air inlet, the exhaust end of the first air inlet channel is communicated with the mixing chamber, the mixing chamber is communicated with the fire hole, and the first air inlet is used for conveying air and gas to the first air inlet channel; and

[0006] a flow guide member arranged in the fire grate body, the flow guide member and the fire grate body jointly form a second air inlet channel, the second air inlet channel is provided with a second air inlet, the second air inlet is used for conveying air to the second air inlet channel, the second air inlet channel comprises a first channel section, a second channel section and a third channel section arranged in sequence from the second air inlet to the mixing chamber, the flow area of the first channel section decreases towards the side close to the second channel section, the flow area of the second channel section increases towards the side close to the third channel section, and the third channel section is communicated with the mixing chamber.

[0007] In an embodiment, the fire grate body comprises a fire hole plate and two side plates arranged on opposite sides of the fire hole plate, the fire hole plate is provided with a plurality of fire holes, the fire hole plate and the two side plates jointly define the mixing chamber, the flow guide member comprises two oppositely arranged flow guide plates, the flow guide plates are arranged one by one on the side of the side plates away from the mixing chamber, each flow guide plate and the adjacent side plate jointly form the second air inlet channel, and each side plate is provided with a flow guide hole for communicating the second air inlet channel with the mixing chamber.

[0008] In an embodiment, the flow guide hole extends from the second air inlet channel to the mixing chamber and is arranged obliquely towards the side close to the fire hole plate.

[0009] In an embodiment, a first included angle is formed between the extending direction of the flow guide hole and the thickness direction of the side plate, and the first included angle is not less than 35° and not more than 50°.

[0010] In an embodiment, each of the side plates is provided with a plurality of flow guide holes arranged at intervals along the length direction of the mixing cavity.

[0011] In an embodiment, a ratio of the total area of the second air inlet of each of the second air inlets to the total area of the flow guide holes on the adjacent side plate is not less than 18 and not more than 22.

[0012] In an embodiment, each of the flow guide plates comprises a main plate body and a folded edge bent relative to the main plate body, the main plate body is arranged opposite to the side plate, the folded edge is arranged on a side of the main plate body close to the fire hole plate and is bent towards the fire hole plate, the main plate body, the folded edge and the side plate form the second air inlet around the second air inlet.

[0013] In an embodiment, the main plate body comprises a first plate segment, a second plate segment and a third plate segment arranged in sequence from the second air inlet towards the folded edge, the second plate segment is arranged obliquely towards a side close to the side plate relative to the third plate segment, and the first plate segment is arranged obliquely towards a side away from the side plate relative to the second plate segment.

[0014] In an embodiment, the second air inlet and the folded edge are arranged opposite in a first direction, the first plate segment is arranged obliquely towards a side close to the side plate in a direction from the second air inlet towards the folded edge, a second included angle is formed between the first plate segment and the first direction, and the second included angle is not less than 30° and not more than 45°.

[0015] In an embodiment, the third plate segment is provided with a convex bump protruding towards the side plate.

[0016] In an embodiment, the fire hole plate is located on a side of the fire row body along a first direction, the two flow guide plates are respectively located on opposite sides of the fire row body along a second direction, the main plate body of each of the flow guide plates is respectively provided with a folded edge plate on both sides along a third direction, the folded edge plate is arranged bent towards a side close to the fire row body relative to the main plate body, and the folded edge plate abuts against the outer wall of the fire row body; the first direction, the second direction and the third direction are arranged perpendicular to each other.

[0017] In an embodiment, the flow guide member further comprises a connecting arm connecting the two flow guide plates, a plurality of the connecting arms are arranged at intervals along the length direction of the fire hole plate, and the plurality of the connecting arms abut against a side of the fire hole plate away from the mixing cavity.

[0018] The present application also provides a burner comprising the fire grate as described above.

[0019] The present application also provides a water heater comprising the burner as described above.

[0020] The technical scheme of the present application is to provide a fire grate body with a flow guide, the fire grate body is provided with a first air inlet channel, a mixing chamber and a fire hole, the first air inlet channel is provided with a first air inlet for introducing air and fuel gas, the flow guide and the fire grate body form at least one second air inlet channel, the second air inlet channel is provided with a second air inlet for introducing air, the exhaust end of the first air inlet channel and the exhaust end of the second air inlet channel are respectively communicated with the mixing chamber, and the mixing chamber is communicated with the fire hole. The second air inlet channel comprises a first channel section, a second channel section and a third channel section arranged in sequence from the second air inlet to the mixing chamber, the cross-sectional area of the first channel section decreases towards the side close to the second channel section, the cross-sectional area of the second channel section increases towards the side close to the third channel section, and the third channel section is communicated with the mixing chamber. When the fire grate is burning, air (i.e. primary air) and fuel gas are transported into the mixing chamber through the first air inlet and the first air inlet channel to mix and form a mixed gas in the mixing chamber, while air (i.e. secondary air) is transported into the mixing chamber through the second air inlet and the second air inlet channel to mix with the mixed gas in the mixing chamber again. Finally, the mixed gas of air and fuel gas in the mixing chamber is transported to the fire hole for ignition and combustion. Due to the presence of the second air inlet channel to supplement secondary air into the mixing chamber, on the one hand, the air content in the mixing chamber can be increased, and the primary air coefficient of the fire grate can be increased, on the other hand, by configuring the second air inlet channel as a Venturi channel structure, the air entraining capacity can be enhanced, high-speed jet flow can be realized, so that the second air inlet channel can be mixed with the mixed gas in the mixing chamber during the process of transporting air to the mixing chamber, the air flow disturbance in the mixing chamber can be enhanced, and the mixing degree of air and fuel gas in the mixing chamber can be improved, so that the mixing of fuel gas and air is more sufficient. In this way, the dual purposes of increasing the primary air coefficient in the fire grate and promoting the mixing of fuel gas and air can be achieved, and finally the lean premixed combustion of fuel on the fire grate can be realized. Lean premixed combustion is a technology that forms a homogeneous lean mixture by premixing fuel and excess air, and then burns the mixture. By forming lean premixed combustion of fuel on the fire grate, the combustion of fuel is more sufficient, and the combustion temperature can be greatly reduced, which can significantly inhibit the generation of nitrogen oxides, thereby reducing the emission of nitrogen oxides in flue gas. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only show some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from the structures shown in the drawings without any creative effort.

[0022] Figure 1 A cross-sectional structure schematic diagram of a fire grate in an embodiment of the prior art;

[0023] Figure 2 A cross-sectional structure schematic diagram of a fire grate in an embodiment of the prior art; Figure 1

[0024] Figure 3 A structure schematic diagram of a fire grate in an embodiment provided by the present application;

[0025] Figure 4 A cross-sectional structure schematic diagram of a fire grate in an embodiment provided by the present application; Figure 3

[0026] A cross-sectional structure schematic diagram of a fire grate in an embodiment provided by the present application; Figure 5 Figure 4

[0027] An oxygen mole fraction cloud diagram of a fire hole of a fire grate in an embodiment of the prior art; Figure 6

[0028] An oxygen mole fraction cloud diagram of a fire hole of a fire grate in an embodiment provided by the present application; Figure 7

[0029] A cross-sectional oxygen mole fraction cloud diagram of a fire grate in an embodiment of the prior art; Figure 8

[0030] A cross-sectional oxygen mole fraction cloud diagram of a fire grate in an embodiment provided by the present application; Figure 9

[0031] A cross-sectional velocity cloud diagram of a fire hole of a fire grate in an embodiment of the prior art; Figure 10

[0032] A cross-sectional velocity cloud diagram of a fire hole of a fire grate in an embodiment provided by the present application; Figure 11

[0033] A cross-sectional local enlarged velocity vector diagram of a fire grate in an embodiment of the prior art; Figure 12

[0034] A cross-sectional local enlarged velocity vector diagram of a fire grate in an embodiment provided by the present application. Figure 13 Explanation of the reference signs in the drawings:

[0035] ​​​

[0036] 101, air inlet channel; 102, main fire port; 103, branch flow channel; 104, branch flow hole; 105, side fire port; 11, flame stabilizer plate;

[0037] 200, fire grate; 201, first air inlet channel; 201a, first air inlet; 2011, injection section; 2012, flow guide section; 202, mixing chamber; 203, fire hole; 204, second air inlet channel; 204a, second air inlet; 2041, first flow channel section; 2042, second flow channel section; 2043, third flow channel section; 2044, transition flow channel section; 20, fire grate body; 21, fire hole plate; 22, side plate; 221, flow guide hole; 30, flow guide; 31, flow guide plate; 311, main plate body; 3111, first plate section; 3112, second plate section; 3113, third plate section; 3114, transition plate section; 31131, convex; 312, flange; 313, folded edge plate; 32, connecting arm.

[0038] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0039] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0040] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement condition, etc. between components in a certain posture, and if the certain posture changes, the directional indications also change accordingly.

[0041] In addition, if the description of "first", "second" and the like is involved in the embodiments of the present application, the description of "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second" can be explicitly or implicitly included at least one of the features. In addition, if "and / or" or "and / or" appears throughout the text, it means that the three parallel schemes are included, for example, "A and / or B" includes A scheme, or B scheme, or A and B scheme. In addition, the technical solutions of each embodiment can be combined with each other, but it must be based on the realization of the ordinary skilled in the art, when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application.

[0042] The combustion mode of the household gas water heater on the market at present is mainly atmospheric combustion, which mainly realizes mixing by venturi air entrainment when fuel jet is implemented, so as to carry out combustion on the fire grate. Therefore, the air content in the fire grate and the mixing degree of fuel gas and air determine the combustion performance and emission performance.

[0043] The fire grate of the conventional combustor cannot carry out combustion by venturi air entrainment when fuel jet is implemented, and during the air entrainment and the flow in the fire grate, the fuel and air cannot be well mixed, which finally leads to insufficient combustion, so that the emission such as nitrogen oxides in the flue gas exceeds the standard.

[0044] As shown in Figure 1 A fire grate 200 of an embodiment in the prior art is provided. The fire grate 200 includes a fire grate body 20 and a flame stabilizer plate 11 arranged at the top of the fire grate body 20. The fire grate body 20 has an air inlet flow channel 101 and a mixing chamber 202. The air inlet flow channel 101 has an air inlet for introducing air and fuel gas. The exhaust end of the air inlet flow channel 101 is communicated with the mixing chamber 202. The top of the fire grate body 20 is provided with a main fire port 102 communicated with the mixing chamber 202. The flame stabilizer plate 11 and the fire grate body 20 define a split flow channel 103. The fire grate body 20 is provided with a split hole 104 communicated with the mixing chamber 202 and the split flow channel 103. The bottom side of the flame stabilizer plate 11 is attached to the outer wall of the fire grate body 20. The top side of the flame stabilizer plate 11 and the fire grate body 20 form a side fire port 105. The exhaust end of the split flow channel 103 is communicated with the side fire port 105.

[0045] The gas flow path of the fire grate 200 in the above embodiment is shown in Figure 2As shown, the air and gas at the air inlet are delivered into the mixing chamber 202 through the air inlet flow channel 101, and the air and gas are mixed in the mixing chamber 202 to form a mixed gas. Part of the mixed gas in the mixing chamber 202 flows upward to the main fire port 102 for combustion, and the other part of the mixed gas flows to the shunt flow channel 103 through the shunt hole 104 at the side of the fire grate body 20, and then is delivered to the side fire port 105 for combustion through the shunt flow channel 103. The secondary air in the external environment can only flow upward along the outer side wall of the fire grate 200 to the side fire port 105, and cannot supplement the secondary air to the inside of the fire grate 200. Due to the insufficient amount of primary air injection at the air inlet of the fire grate 200, and the lack of disturbance of the mixed gas flowing in the fire grate 200, the air content in the fire grate 200 is low, and the gas and air cannot be fully mixed, which finally leads to incomplete combustion, and the emission of pollutants in the flue gas exceeds the standard.

[0046] The present application provides a fire grate 200, which can increase the air content in the fire grate 200, improve the mixing degree of air and gas in the fire grate 200, and thus realize sufficient combustion and reduce the emission of nitrogen oxides in the flue gas.

[0047] Please refer to Figures 3 to 5 In an embodiment of the present application, the fire grate 200 includes a fire grate body 20 and a flow guide 30. The fire grate body 20 is provided with a first air inlet flow channel 201, a mixing chamber 202 and a fire hole 203, the first air inlet flow channel 201 has a first air inlet 201a, the exhaust end of the first air inlet flow channel 201 is communicated with the mixing chamber 202, the mixing chamber 202 is communicated with the fire hole 203, and the first air inlet 201a is used for delivering air and gas to the first air inlet flow channel 201; the flow guide 30 is arranged on the fire grate body 20, and the flow guide 30 and the fire grate body 20 surround to form a second air inlet flow channel 204, the second air inlet flow channel 204 has a second air inlet 204a, the second air inlet 204a is used for delivering air to the second air inlet flow channel 204, the second air inlet flow channel 204 includes a first flow channel section 2041, a second flow channel section 2042 and a third flow channel section 2043 arranged in sequence from the second air inlet 204a to the mixing chamber 202, the flow area of the first flow channel section 2041 decreases towards the side close to the second flow channel section 2042, the flow area of the second flow channel section 2042 increases towards the side close to the third flow channel section 2043, and the third flow channel section 2043 is communicated with the mixing chamber 202.

[0048] The burner 200 includes a burner body 20, which constitutes the main structure of the burner 200. The burner body 20 is provided with a first air intake channel 201, a mixing chamber 202, and flame holes 203. The first air intake channel 201 has a first air inlet 201a, which is used to supply fuel gas and air into the first air intake channel 201. The first air intake channel 201 may be at least partially constructed as a Venturi channel, so that the high-speed flow of fuel gas in the first air intake channel 201 generates a local low-pressure zone. The suction generated by the local low-pressure zone draws external air from the first air inlet 201a into the first air intake channel 201, thereby enabling the first air intake channel 201 to supply fuel gas and air. Alternatively, air may be blown into the first air inlet 201a by a fan. The mixing chamber 202 provides a place for mixing air and fuel gas. The flame holes 203 are used to output the mixture of air and fuel gas in the mixing chamber 202 for combustion. Multiple flame holes 203 are usually provided, and the multiple flame holes 203 are arranged at intervals along the length of the flame bar body 20 to increase the combustion area.

[0049] The burner 200 also includes a guide member 30 disposed on the burner body 20. The guide member 30 is connected to the burner body 20 by methods including but not limited to welding, fastener connection, snap-fit, and plug-in; alternatively, the guide member 30 and the burner body 20 can be constructed as an integral structure. The guide member 30, together with the burner body 20, defines a second air intake channel 204. The number of second air intake channels 204 is not limited; there can be one, two, or more. The air intake end of the second air intake channel 204 is provided with a second air inlet 204a for introducing air, and the exhaust end of the second air intake channel 204 connects to the mixing chamber 202. This allows external air to be delivered to the second air intake channel 204 via the second air inlet 204a, and then to the mixing chamber 202 via the second air intake channel 204.

[0050] like Figure 5 As shown, in this embodiment, the gas flow path of the burner 200 is as follows: When the burner 200 is burning, air (i.e., primary air) and fuel gas are transported to the mixing chamber 202 through the first air inlet 201a and the first air intake channel 201 to mix and form a mixed gas. At the same time, air (i.e., secondary air) is transported to the mixing chamber 202 through the second air inlet 204a and the second air intake channel 204 to form a counter-mixing with the mixed gas in the mixing chamber 202. Finally, the air and fuel gas mixture in the mixing chamber 202 is transported to the burner hole 203 for ignition and combustion.

[0051] The air at the second air inlet 204a can be sequentially delivered into the mixing chamber 202 through the first flow channel section 2041, the second flow channel section 2042 and the third flow channel section 2043. The flow area of the first flow channel section 2041 is gradually reduced towards the side close to the second flow channel section 2042, and the flow area of the second flow channel section 2042 is gradually increased towards the side close to the third flow channel section 2043, so that the second air inlet flow channel 204 is configured as a Venturi flow channel structure. When the air passes through the first flow channel section 2041, the flow rate of the air in the first flow channel section 2041 gradually increases, and a low pressure area can be formed at the end of the first flow channel section 2041. When the pressure at the second air inlet 204a is greater than the pressure of the low pressure area at the end of the first flow channel section 2041, the air in the external environment can be self-sucked into the second air inlet flow channel 204 through the second air inlet 204a under the action of the pressure difference, thereby improving the air intake amount. When the air passes through the second flow channel section 2042, the flow rate of the air in the second flow channel section 2042 gradually decreases, and the pressure gradually recovers, which is beneficial to reduce the mechanical energy loss and ensure the injection capacity. In this way, by configuring the second air inlet flow channel 204 as a Venturi flow channel structure, the air injection capacity can be enhanced, and a high-speed jet flow can be realized, so that the air delivered through the second air inlet flow channel 204 can be mixed with the mixed gas in the mixing chamber 202.

[0052] The technical scheme of the present application is characterized in that a flow guide 30 is arranged on the fire grate body 20, the fire grate body 20 is provided with a first air inlet channel 201, a mixing chamber 202 and a fire hole 203, the first air inlet channel 201 is provided with a first air inlet 201a for introducing air and fuel gas, the flow guide 30 and the fire grate body 20 form a second air inlet channel 204, the second air inlet channel 204 is provided with a second air inlet 204a for introducing air, the exhaust end of the first air inlet channel 201 and the exhaust end of the second air inlet channel 204 are communicated with the mixing chamber 202 respectively, and the mixing chamber 202 is communicated with the fire hole 203. In this way, when the fire grate 200 is burning, air (i.e. primary air) and fuel gas are transported into the mixing chamber 202 through the first air inlet 201a and the first air inlet channel 201 to mix and form a mixed gas in the mixing chamber 202, and at the same time, air (i.e. secondary air) is transported into the mixing chamber 202 through the second air inlet 204a and the second air inlet channel 204 to form a counterflow mixing with the mixed gas in the mixing chamber 202. Finally, the mixed gas of air and fuel gas in the mixing chamber 202 is transported to the fire hole 203 for ignition and combustion. Since the second air inlet channel 204 supplements the secondary air into the mixing chamber 202, on the one hand, the air content in the mixing chamber 202 can be increased, and the primary air coefficient of the fire grate 200 can be increased, and on the other hand, by configuring the second air inlet channel 204 as a structure similar to a Venturi channel, the air entraining capacity can be enhanced, high-speed jet flow can be realized, and the second air inlet channel 204 can perform counterflow mixing with the mixed gas in the mixing chamber 202 during the process of transporting air into the mixing chamber 202, the air flow disturbance in the mixing chamber 202 can be enhanced, and thus the mixing degree of air and fuel gas in the mixing chamber 202 can be improved, so that the mixing of air and fuel gas is more sufficient. In this way, the dual purposes of increasing the primary air coefficient in the fire grate 200 and promoting the mixing of air and fuel gas can be achieved, and finally the lean premixed combustion of fuel on the fire grate 200 can be realized. Lean premixed combustion is a technology of forming a homogeneous lean mixed gas by premixing fuel and excess air and then performing combustion. By forming lean premixed combustion of fuel on the fire grate 200, the combustion of fuel is more sufficient, the combustion temperature can be greatly reduced, the generation of nitrogen oxides can be significantly inhibited, and thus the emission amount of nitrogen oxides in flue gas can be reduced.

[0053] As Figure 3As shown, the fire grate body 20 has a first side and a second side opposite in length direction, the first side of the fire grate body 20 is provided with a first air inlet 201a at a position close to the bottom, a first air flow channel 201 and a mixing chamber 202 are constructed inside the fire grate body 20, and the top of the fire grate body 20 is provided with a plurality of fire holes 203 arranged at intervals along the length direction thereof. The first air flow channel 201 can include an injection section 2011 and a guide section 2012, the injection section 2011 is arranged extending from the first air inlet 201a towards the second side of the fire grate body 20, the guide section 2012 is arranged extending from an end of the injection section 2011 away from the first air inlet 201a, bending towards the top of the fire grate body 20 and extending towards the first side of the fire grate body 20, and the mixing chamber 202 is arranged at the top of the guide section 2012. In this way, the air and the gas at the first air inlet 201a are transported to the guide section 2012 via the injection section 2011, and then transported to the mixing chamber 202 by the guide section 2012. Since the extension directions of the injection section 2011 and the guide section 2012 are different, the flow path of the gas is extended without increasing the volume of the fire grate body 20, the gas and the air can be preliminarily mixed in the first air flow channel 201 before being transported into the mixing chamber 202 for re-mixing, and the degree of gas mixing is enhanced.

[0054] Optionally, the injection section 2011 includes a converging section and a diverging section arranged in sequence in the air inlet direction, the flow area of the converging section is arranged decreasing from the first air inlet 201a towards the diverging section, and the flow area of the diverging section is arranged increasing from the converging section away from the first air inlet 201a. In this way, the injection section 2011 is constructed as a Venturi flow channel, when the gas passes through the converging section, the flow rate of the gas gradually increases, and a low-pressure area can be formed at the end of the converging section. When the pressure at the first air inlet 201a is greater than the pressure of the low-pressure area at the end of the converging section, the air in the external environment can be self-sucked into the first air flow channel 201 through the first air inlet 201a under the action of the pressure difference. When the gas passes through the diverging section, the flow rate gradually decreases, and the pressure gradually recovers. By arranging the diverging section, the mechanical energy loss is reduced, and the injection capacity is ensured. In this way, when the gas and the air are transported in the first air flow channel 201, the gas and the air can be fully mixed, thereby improving the uniformity of the gas and the air mixing when the gas is introduced into the first air flow channel 201.

[0055] Optionally, the maximum flow cross-sectional area of ​​the second flow channel section 2042 is smaller than the flow cross-sectional area of ​​the second air inlet 204a, and the maximum flow cross-sectional area of ​​the third flow channel section 2043 is smaller than the flow cross-sectional area of ​​the second air inlet 204a. This results in a relatively large flow cross-sectional area at the second air inlet 204a, ensuring a larger airflow area at the second air inlet 204a and increasing the amount of air entering the second air intake channel 204. After being accelerated through the first flow channel section 2041, the air enters the second flow channel section 2042 and the third flow channel section 2043. Since the cross-sectional area of ​​the second flow channel section 2042 and the third flow channel section 2043 is smaller than that of the second air inlet 204a, the gas velocity in the second flow channel section 2042 and the third flow channel section 2043 can still be higher than that at the second air inlet 204a. This allows the air to flow into the mixing chamber 202 at a higher velocity, so as to counteract and mix with the mixed gas in the mixing chamber 202, thereby improving the mixing uniformity. Optionally, a transition flow section 2044 is provided between the first flow section 2041 and the second flow section 2042. The cross-sectional area of ​​the transition flow section 2044 decreases from the side closer to the first flow section 2041 to the side closer to the second flow section 2042. In this way, the air accelerated in the first flow section 2041 can be accelerated again through the transition flow section 2044 before entering the second flow section 2042, further enhancing the jetting capability.

[0056] like Figure 3 and Figure 4 As shown, in one embodiment, the burner body 20 includes a burner plate 21 and two side plates 22 disposed on opposite sides of the burner plate 21. The burner plate 21 is provided with a plurality of burner holes 203. The burner plate 21 and the two side plates 22 together define a mixing chamber 202. The flow guide 30 includes two flow guide plates 31 disposed opposite to each other. The flow guide plates 31 are disposed one-to-one on the side of the side plate 22 away from the mixing chamber 202. Each flow guide plate 31 and the adjacent side plate 22 surround to form a second air intake channel 204. Each side plate 22 is provided with a flow guide hole 221 that connects the second air intake channel 204 and the mixing chamber 202.

[0057] In the embodiment, the fire grate body 20 comprises a fire hole plate 21 and two side plates 22 arranged on both sides of the fire hole plate 21. The fire hole plate 21 can be arranged on one side in the height direction of the fire grate body 20, and the two side plates 22 can be arranged on both sides in the width direction of the fire hole plate 21. The fire hole plate 21 is arranged along the length direction of the fire grate body 20, and the fire hole plate 21 has a plurality of fire holes 203 arranged at intervals along the length direction thereof. The fire hole plate 21 can be integrally formed with the two side plates 22, or the fire hole plate 21 can be connected with the side plates 22 by welding, riveting, fastening, or the like. For example, in actual application, the fire hole plate 21 and the two side plates 22 can be integrally formed by bending a sheet metal plate, and the edges of the two side plates 22 can be welded to be fixed, so that the fire hole plate 21 and the two side plates 22 form the first air inlet flow channel 201 and the mixing chamber 202. Generally, the fire hole plate 21 is located at the top of the fire grate body 20, and correspondingly, the mixing chamber 202 is located near the fire hole plate 21 of the fire grate body 20.

[0058] The flow guide 30 comprises two flow guide plates 31 arranged oppositely, and each flow guide plate 31 is arranged on the side of the side plate 22 away from the mixing chamber 202. Each flow guide plate 31 forms a second air inlet flow channel 204 together with the adjacent side plate 22, and each side plate 22 is provided with a flow guide hole 221 for connecting the second air inlet flow channel 204 and the mixing chamber 202. In this way, the second air inlet flow channel 204 is formed on each side of the fire grate body 20, and each second air inlet flow channel 204 can deliver air into the mixing chamber 202 through the flow guide hole 221 on the adjacent side plate 22, so as to further increase the air delivery amount and more favorably increase the air content in the mixing chamber 202. Moreover, the air in the mixing chamber 202 is more uniformly distributed by simultaneously delivering air into the mixing chamber 202 through the second air inlet flow channels 204 on both sides of the fire grate body 20, which is favorable for further improving the mixing uniformity of the air and the mixed gas in the mixing chamber 202, and can also avoid the adverse effect of the temperature distribution in the mixing chamber 202 caused by the single-sided second air inlet flow channel 204 on the combustion sufficiency.

[0059] It is worth noting that the two guide plates 31 of the flow guide 30 can be set separately, or they can be connected as one unit by a connecting structure (such as a connecting arm 32), as long as each side plate 22 has a guide plate 31 on its outer side. For example, when the two guide plates 31 are set separately, they can be welded to the corresponding side plate 22 respectively. When the two guide plates 31 are connected together by the connecting arm 32, the connecting arm 32 can be directly attached to the top surface of the fire hole plate 21, so that the two guide plates 31 are placed on both sides of the fire bar body 20. This eliminates the welding step and simplifies the assembly process. The cross-sectional shape of the flow holes 221 on the side plate 22 includes, but is not limited to, circular, elliptical, rectangular or other irregular cross-sections. The number of flow holes 221 on each side plate 22 can be one, two or more, and is not specifically limited here.

[0060] Understandably, the flow cross-sectional area of ​​the guide hole 221 on the side plate 22 is relatively small compared to the second air inlet channel 204. Thus, when air enters the relatively small flow cross-sectional area of ​​the guide hole 221 from a larger space, a high-speed jet is generated. This facilitates the air in the second air inlet channel 204 flowing towards the mixing chamber 202 at a higher velocity, forming a high-speed opposing mixing with the mixed gas in the mixing chamber 202. This further enhances the gas turbulence within the mixing chamber 202 and improves the uniformity of gas mixing within the mixing chamber 202.

[0061] Furthermore, such as Figure 4 As shown, in one embodiment, the guide hole 221 extends from the second air inlet channel 204 toward the mixing chamber 202 and is inclined toward the side near the flame orifice plate 21. By setting the guide hole 221 as an oblique hole, with the outlet end of the guide hole 221 facing the flame orifice plate 21, air in the second air inlet channel 204 can be obliquely ejected upward through the inclined guide hole 221 to the side of the mixing chamber 202 near the flame orifice plate 21. By setting the inclined guide hole 221, on the one hand, it is beneficial to guide the air to move towards the side closer to the flame plate 21 to the flame hole 203 to achieve secondary air replenishment, so as to ensure the air content at the flame hole 203 and facilitate complete combustion; on the other hand, if the guide holes 221 on the two side plates 22 directly face each other for air jetting, or if the guide holes 221 on the two side plates 22 are both inclined downwards for air jetting, it will generate greater resistance to the gas in the incoming flow direction, thereby blocking the normal path of the mixed gas in the mixing chamber 202 towards the flame hole 203, which may cause the flame hole 203 to be extinguished due to insufficient gas supply. By designing the guide hole 221 to be inclined upwards towards the side closer to the flame plate 21, the airflow resistance can be reduced and the flameout can be prevented.

[0062] It can be understood that the first included angle a is formed between the extending direction of the flow guide hole 221 and the thickness direction of the side plate 22. If the angle of the first included angle a is too small, the inclination angle of the flow guide hole 221 relative to the thickness direction of the side plate 22 is too small, and the flow guide hole 221 tends to extend horizontally along the thickness direction of the side plate 22. In this way, the air flow emitted by the flow guide hole 221 directly impacts the opposite side plate 22, and cannot well guide the air flow to the fire hole plate. If the angle of the first included angle a is too large, the inclination angle of the flow guide hole 221 relative to the thickness direction of the side plate 22 is too large, and the air flow emitted by the flow guide hole 221 flows closer to the side plate 22 on the same side, and cannot well form a head-on mixing with the mixed gas at the center of the mixing chamber 202, affecting the mixing effect.

[0063] Alternatively, the first included angle is formed between the extending direction of the flow guide hole 221 and the thickness direction of the side plate 22, and the first included angle is not less than 35° and not greater than 50°. That is, the first included angle a is formed between the extending direction of the flow guide hole 221 and the thickness direction of the side plate 22, and satisfies 35°≤a≤50°. In this way, the angle of the first included angle a is moderate, which is conducive to guiding the air to flow towards the fire hole plate through the inclined flow guide hole 221 to supplement the air at the fire hole 203 of the fire hole plate, and also conducive to guiding the air to flow towards the center of the mixing chamber 202 to form a head-on mixing with the mixed gas at the center of the mixing chamber 202, thereby improving the mixing effect. In this way, the air content and the mixing uniformity can be more improved, the combustion can be ensured to be sufficient, and the emission amount of nitrogen oxides in the flue gas can be reduced. For example, the first included angle a can be 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44°, 45°, 46°, 47°, 48°, 49°, 50°, or any angle in the above range.

[0064] In order to further improve the air content and the gas mixing uniformity in the mixing chamber 202, in some embodiments, each side plate 22 is provided with a plurality of flow guide holes 221 arranged at intervals along the length direction of the mixing chamber 202. And / or, the ratio of the total area of the second air inlet 204a of each second air inlet flow channel 204 to the total area of the flow guide holes 221 on the adjacent side plate 22 is not less than 18 and not greater than 22.

[0065] In an embodiment, each side plate 22 is provided with a plurality of flow guide holes 221 arranged along the length direction of the mixing chamber 202. For example, the mixing chamber 202 extends along the length direction of the fire bed body 20, and each side plate 22 is provided with a plurality of flow guide holes 221 arranged along the length direction of the mixing chamber 202. In this way, the air delivered by the second air inlet channel 204 can be simultaneously ejected into the mixing chamber 202 through the plurality of flow guide holes 221 on the side plate 22, thereby increasing the air content of the single entry into the mixing chamber 202. Moreover, the plurality of flow guide holes 221 are arranged along the length of the mixing chamber 202, so that multi-point jet flow can be achieved, so that the mixing chamber 202 has a high air content at each part of its length direction, and the air in the mixing chamber 202 is mixed at multiple points, thereby more beneficially improving the air content and gas mixing uniformity of the mixing chamber 202 as a whole, and further improving combustion.

[0066] In an embodiment, the ratio of the total area of the second air inlet 204a of each second air inlet channel 204 to the total area of the flow guide holes 221 on the adjacent side plate 22 is not less than 18 and not greater than 22. That is, the total area of the second air inlet 204a of each second air inlet channel 204 is S1, and the total area of all flow guide holes 221 on the side plate 22 adjacent to the second air inlet channel 204 is S2, which satisfies: 18≤S1 / S2≤22. In this way, the total area of the second air inlet 204a is relatively large, which can be beneficial to improve the air content entering the second air inlet channel 204 from the second air inlet 204a. Moreover, the total area of all flow guide holes 221 on the side plate 22 adjacent to the second air inlet channel 204 is smaller than the total area of the second air inlet 204a, so that the air in the second air inlet channel 204 will accelerate when entering the flow guide holes 221, thereby achieving high-speed jet flow, which is beneficial to further enhance the air mixing effect in the mixing chamber 202, thereby improving the mixing degree and mixing uniformity. For example, S1 / S2 can be 18, 19, 20, 21, 22, or any value within the above range.

[0067] As Figure 3 and Figure 4As shown, in an embodiment, each deflector 31 comprises a main plate body 311 and a bent edge 312 bent relative to the main plate body 311, the main plate body 311 is arranged opposite to the side plate 22, the bent edge 312 is arranged on a side of the main plate body 311 close to the fire hole plate 21 and is bent towards the fire hole plate 21, the main plate body 311, the bent edge 312 and the side plate 22 form a second air inlet channel 204, and an end of the second air inlet channel 204 away from the bent edge 312 is provided with a second air inlet 204a.

[0068] In the embodiment, the top of the main plate body 311 is provided with the bent edge 312, the bent edge 312 is substantially flush with the fire hole plate 21, the main plate body 311, the bent edge 312 and the side plate 22 form the second air inlet channel 204, and an end of the second air inlet channel 204 away from the bent edge 312 is provided with the second air inlet 204a. The end of the second air inlet channel 204 away from the second air inlet 204a can be blocked by the bent edge 312, so that the air in the second air inlet channel 204 can only enter the mixing chamber 202 through the flow guide hole 221 on the side plate 22 of the fire grate body 20, which can improve the air content entering the mixing chamber 202 from the second air inlet channel 204, so that the combustion is more sufficient, and the nitrogen oxide emission content in the flue gas is further reduced.

[0069] Further, as shown, Figure 4 In an embodiment, the main plate body 311 comprises a first plate segment 3111, a second plate segment 3112 and a third plate segment 3113 arranged in sequence from the second air inlet 204a towards the bent edge 312, the second plate segment 3112 is arranged inclined towards the side plate 22 relative to the third plate segment 3113, and the first plate segment 3111 is arranged inclined away from the side plate 22 relative to the second plate segment 3112.

[0070] In the embodiment, the third plate segment 3113 extends downwards from a side of the bent edge 312 away from the fire hole plate 21, the second plate segment 3112 is bent and extends downwards from a bottom side of the third plate segment 3113 towards the side plate 22, and the first plate segment 3111 is bent and extends downwards from a bottom side of the second plate segment 3112 away from the side plate 22. The first plate segment 3111 and the side plate 22 form a first flow channel segment 2041, the second plate segment 3112 and the side plate 22 form a second flow channel segment 2042, and the third plate segment 3113 and the side plate 22 form a third flow channel segment 2043. The second air inlet 204a, the first flow channel segment 2041, the second flow channel segment 2042 and the third flow channel segment 2043 are sequentially communicated to form the second air inlet channel 204.

[0071] Due to the first plate segment 3111 is arranged to be inclined relative to the second plate segment 3112 towards the side away from the side plate 22, the flow area of the first flow passage segment 2041 is arranged to be reduced towards the side close to the second flow passage segment 2042, when the air passes through the first flow passage segment 2041, the flow rate of the air in the first flow passage segment 2041 gradually increases, and a low pressure area can be formed at the end of the first flow passage segment 2041, when the pressure at the second air inlet 204a is greater than the pressure of the low pressure area at the end of the first flow passage segment 2041, the air in the external environment can be self-sucked into the second air inlet flow passage 204 through the second air inlet 204a under the action of the pressure difference, and the air intake amount is improved. And, by making the first plate segment 3111 inclined relative to the second plate segment 3112 towards the side away from the side plate 22, the first flow passage segment 2041 is arranged to be flared, so that the opening area of the second air inlet 204a is larger, which is more conducive to the air entering the second air inlet flow passage 204. In addition, the first plate segment 3111 is arranged as an outwardly flared inclined plate body, so that the inner wall surface of the first plate segment 3111 forms an inclined flow guide surface, which can guide the air in the first flow passage segment 2041 to flow towards the side close to the side plate 22, so that the air can flow along the side plate 22 to the flow guide hole 221 and be jetted into the mixing chamber 202 through the flow guide hole 221.

[0072] Due to the second plate segment 3112 is arranged to be inclined relative to the third plate segment 3113 towards the side close to the side plate 22, the flow area of the second flow passage segment 2042 is arranged to be increased towards the side close to the third flow passage segment 2043. When the air passes through the second flow passage segment 2042, the flow rate of the air in the second flow passage segment 2042 gradually decreases, and the pressure gradually recovers, which is conducive to reducing mechanical energy loss and ensuring the injection capacity. In this way, by configuring the second air inlet flow passage 204 as a Venturi flow passage structure, the air injection capacity is improved, and high-speed jet flow is realized, so that the air transported through the second air inlet flow passage 204 can be mixed with the mixed gas in the mixing chamber 202, thereby improving the mixing degree and uniformity.

[0073] Optionally, the main plate body 311 further includes a transition plate segment 3114 arranged between the first plate segment 3111 and the second plate segment 3112, and the transition plate segment 3114 and the side plate 22 form a transition flow passage segment 2044, and the transition flow passage segment 2044 communicates the first flow passage segment 2041 and the second flow passage segment 2042. Optionally, the flow area of the transition flow passage segment 2044 is arranged to be reduced from the side close to the first flow passage segment 2041 towards the side close to the second flow passage segment 2042, so that the air accelerated in the first flow passage segment 2041 can be accelerated again through the transition flow passage segment 2044 and then enter the second flow passage segment 2042, thereby further improving the jet flow capacity.

[0074] The second air inlet 204a is arranged opposite to the flange 312 along the first direction, the first plate segment 3111 is inclined to the side close to the side plate 22 in the direction from the second air inlet 204a to the flange 312, and a second included angle is formed between the first plate segment 3111 and the first direction. It can be understood that if the second included angle is too small, the opening area of the second air inlet 204a is too small, the flow resistance at the second air inlet 204a is relatively large, which is not conducive to guiding the external air to enter the first flow channel segment 2041 through the second air inlet 204a. If the second included angle is too large, it is easy to cause flow separation and uneven flow field, thereby seriously reducing the injection efficiency. Alternatively, the second included angle is not less than 30° and not greater than 45°. That is, the angle between the first plate segment 3111 and the first direction is the second included angle β, which satisfies: 30°≤β≤45°. In this way, the angle of the second included angle β is moderate, which is conducive to improving the injection efficiency of the second air inlet flow channel 204, so that the external air can enter the second air inlet flow channel 204 through the second air inlet 204a more, so as to improve the air content and mixing degree in the fire row 200. For example, the second included angle β can be 30°, 31°, 32°, 33°, 34°, 35°, 36°, 37°, 38°, 39°, 40°, 41°, 42°, 43°, 44°, 45°, and any angle value in the above interval.

[0075] As shown in the drawings, Figure 3 In an embodiment, the third plate segment 3113 is provided with a convex 31131 protruding towards the side plate 22, so that the flow area of the third flow channel segment 2043 corresponding to the position where the third plate segment 3113 is provided with the convex 31131 is smaller, thereby facilitating the improvement of air flow rate, so that the air in the third flow channel segment 2043 can flow towards the flow guide hole 221 at a higher speed to realize high-speed jet flow, thereby further enhancing the disturbance to the gas in the mixing chamber 202 and improving the mixing uniformity. Alternatively, a plurality of convexes 31131 are arranged along the length direction of the fire row body 20, a plurality of flow guide holes 221 are arranged along the length direction of the fire row body 20, and the convexes 31131 and the flow guide holes 221 are arranged opposite to each other one by one, so that each flow guide hole 221 can realize high-speed jet flow. In actual application, the convex 31131 can be formed by punching from the outer surface of the flow guide plate 31 towards the side close to the side plate 22, which can simplify the manufacturing process and improve the production efficiency.

[0076] As shown in the drawings, Figure 3As shown, in one embodiment, the fire hole plate 21 is located on one side of the fire duct body 20 along the first direction, and the two guide plates 31 are respectively located on opposite sides of the fire duct body 20 along the second direction. Each guide plate 31 has a main body 311 with a folded edge plate 313 on both sides along the third direction. The folded edge plate 313 is bent relative to the main body 311 towards the side closer to the fire duct body 20, and the folded edge plate 313 abuts against the outer wall of the fire duct body 20. The first direction, the second direction and the third direction are arranged perpendicularly to each other.

[0077] In this embodiment, the first direction can be the height direction of the burner body 20, the second direction can be the width direction of the burner body 20, and the third direction can be the length direction of the burner body 20. The burner plate 21 is located at the top of the burner body 20, and two guide plates 31 are respectively located on both sides of the burner body 20 in the width direction and are disposed close to the burner plate 21. The main body 311 of each guide plate 31 defines a second air intake channel 204 between itself and the burner body 20. Each main body 311 has a flange 312 on its top and folded plates 313 on both sides along the length of the burner body 20. The flange 312 is connected to the burner plate 21 and can block the top of the second air intake channel 204. The folded plates 313 are in contact with the outer wall of the burner body 20 and can block both sides of the second air intake channel 204 along the length of the burner body 20. This ensures that the air in the second air intake channel 204 can enter the mixing chamber 202 through the guide hole 221 on the side plate 22 as much as possible, thereby increasing the air content and gas mixing degree in the mixing chamber 202.

[0078] like Figure 3 As shown, in one embodiment, the flow guide 30 further includes a connecting arm 32 that connects the two flow guide plates 31. Multiple connecting arms 32 are spaced apart along the length direction of the fire hole plate 21, and multiple connecting arms 32 abut against the side of the fire hole plate 21 away from the mixing chamber 202.

[0079] In the embodiment, the flow guide 30 includes two flow guide plates 31 oppositely and spacedly arranged, and a connecting arm 32 arranged between the two flow guide plates 31. Thus, when assembling, the flow guide 30 can be buckled as a whole from top to bottom on the top of the fire grate body 20 until the connecting arm 32 abuts against the side of the fire hole plate 21 away from the mixing chamber 202, and the two flow guide plates 31 are separately arranged on the two sides of the fire grate body 20, and the connecting arm 32 can be supported by the fire hole plate 21, thereby supporting the flow guide 30, so that the flow guide 30 does not need to be fixed by other ways (such as welding, riveting, etc.), thereby realizing quick assembly and disassembly of the flow guide 30. In addition, the connecting arm 32 is spacedly arranged along the length direction of the fire hole plate 21, which can further improve the connection stability between the two flow guide plates 31 and the assembly reliability of the flow guide 30 and the fire grate body 20. Optionally, the flow guide 30 is configured as an integral structure. For example, the flow guide 30 can be made of sheet metal by bending and blanking processes to integrally form the two flow guide plates 31 and the connecting arm 32 connected between the two flow guide plates 31.

[0080] Please refer to Figures 6 to 13 , the prior art fire grate 200 (hereinafter referred to as the existing fire grate 200) and Figure 1 , the fire grate 200 (hereinafter referred to as the new fire grate 200) provided by the embodiment of the present application are simulated to obtain simulation calculation result cloud maps. Among them, Figure 3 is the oxygen molar fraction cloud map of the existing fire grate 200 at the fire hole; Figure 6 is the oxygen molar fraction cloud map of the new fire grate 200 at the fire hole; Figure 7 is the oxygen molar fraction cloud map of the existing fire grate 200 at the cross section; Figure 8 is the oxygen molar fraction cloud map of the new fire grate 200 at the cross section; Figure 9 is the cross section velocity cloud map of the existing fire grate 200 at the fire hole; Figure 10 is the cross section velocity cloud map of the new fire grate 200 at the fire hole; Figure 11 is the cross section local enlarged velocity vector diagram of the existing fire grate 200; Figure 12 is the cross section local enlarged velocity vector diagram of the new fire grate 200. Figure 13 According to

[0081] , it can be seen that the oxygen molar fraction at the fire hole and the cross section of the new fire grate 200 is obviously higher than that of the existing fire grate 200. According to Figures 6 to 9 , it can be seen that the jet velocity at the fire hole of the new fire grate 200 is obviously greater than that of the existing fire grate 200, and the average jet velocity is just matched with the laminar flame propagation speed of methane at the equivalence ratio of 1, which is beneficial to the stability of combustion. In addition, according to Figures 10 to 13 and Figure 12 , it can be seen that the jet velocity at the fire hole of the new fire grate 200 is obviously greater than that of the existing fire grate 200, and the average jet velocity is just matched with the laminar flame propagation speed of methane at the equivalence ratio of 1, which is beneficial to the stability of combustion. In addition, according to Figure 13It can be seen that the velocity distribution of the new fire grate 200 at the fire hole is more stable and uniform, there is no large difference, and there is no large vortex, which is conducive to stable combustion of the flame. Therefore, the technical scheme of the present application expands the secondary air flow channel (i.e. the second air inlet flow channel 204) by providing the flow guide plate 31 on the fire grate body 20, so that the gas in the upper part of the fire grate 200 and the mixed cavity 202 can be mixed by opposing, thereby achieving the dual purposes of improving the primary air coefficient in the fire grate 200 and promoting the mixing of gas and air, and then realizing lean premixed combustion of the gas on the fire grate 200 burner, so that the gas water heater has good combustion characteristics and emission characteristics during operation.

[0082] The present application also provides a burner, which comprises the fire grate 200, the specific structure of which is referred to the above-mentioned embodiments. Since the present burner adopts all the technical schemes of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical schemes of the above-mentioned embodiments, which will not be repeated here. The burner can comprise a frame and the fire grate 200 arranged in the frame. The fire grate 200 can be arranged in multiple.

[0083] The present application also provides a burner, which comprises the fire grate 200, the specific structure of which is referred to the above-mentioned embodiments. Since the present burner adopts all the technical schemes of the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical schemes of the above-mentioned embodiments, which will not be repeated here. The burner can comprise a frame and the fire grate 200 arranged in the frame. The fire grate 200 can be arranged in multiple.

[0084] The above-mentioned is only an exemplary embodiment of the present application, and does not limit the protection scope of the present application, and any equivalent structural transformation made by the present application specification and drawings, or direct / indirect application in other related technical fields is included in the protection scope of the present application.

Claims

1. A fire grill, characterized in that, include: The burner body is provided with a first air intake channel, a mixing chamber and a flame hole. The first air intake channel has a first air inlet. The exhaust end of the first air intake channel is connected to the mixing chamber. The mixing chamber is connected to the flame hole. The first air inlet is used to supply air and fuel gas to the first air intake channel. as well as A flow guide is disposed on the burner body, and the flow guide and the burner body surround to form a second air intake channel. The second air intake channel has a second air inlet for supplying air to the second air intake channel. The second air intake channel includes a first channel section, a second channel section and a third channel section arranged sequentially from the second air inlet toward the mixing chamber. The cross-sectional area of ​​the first channel section decreases towards the side closer to the second channel section, and the cross-sectional area of ​​the second channel section increases towards the side closer to the third channel section. The third channel section communicates with the mixing chamber. The burner body includes a burner plate and two side plates disposed on opposite sides of the burner plate. The burner plate has a plurality of burner holes. The burner plate and the two side plates together define the mixing chamber. The flow guide includes two flow guide plates disposed opposite to each other. The flow guide plates are disposed one-to-one on the side of the side plate away from the mixing chamber. Each flow guide plate and the adjacent side plate form a second air intake channel. Each side plate has a flow guide hole that connects the second air intake channel to the mixing chamber. Each second air intake channel can deliver air into the mixing chamber through the flow guide hole on the adjacent side plate. The ratio of the total area of ​​the second air inlet of each second air intake channel to the total area of ​​the flow guide hole on the adjacent side plate is not less than 18 and not greater than 22.

2. The fire grill as described in claim 1, characterized in that, The guide hole extends from the second air intake channel toward the mixing chamber and is inclined toward the side closer to the fire orifice plate.

3. The fire grill as described in claim 2, characterized in that, The extension direction of the flow guide hole forms a first angle with the thickness direction of the side plate, and the first angle is not less than 35° and not greater than 50°.

4. The fire grill as described in claim 1, characterized in that, Each of the side plates is provided with a plurality of flow guide holes spaced apart along the length of the mixing chamber.

5. The fire grill as described in claim 1, characterized in that, Each of the aforementioned guide plates includes a main body and a flange bent relative to the main body. The main body is disposed opposite to the side plate. The flange is disposed on the side of the main body near the fire hole plate and bent toward the fire hole plate. The main body, the flange, and the side plate surround to form a second air intake channel. The second air intake channel is provided at the end away from the flange.

6. The fire grill as described in claim 5, characterized in that, The main body includes a first plate segment, a second plate segment, and a third plate segment arranged sequentially from the second air inlet toward the flange. The second plate segment is inclined relative to the third plate segment toward the side closer to the side plate, and the first plate segment is inclined relative to the second plate segment toward the side farther away from the side plate.

7. The fire grill as described in claim 6, characterized in that, The second air inlet is disposed opposite to the flange along the first direction. The first plate segment is inclined toward the side plate in the direction from the second air inlet toward the flange. The first plate segment forms a second angle with the first direction. The second angle is not less than 30° and not greater than 45°.

8. The fire briquette as described in claim 6, characterized in that, The third plate segment is provided with a protrusion that protrudes toward the side plate.

9. The fire grill as described in claim 5, characterized in that, The fire hole plate is located on one side of the fire duct body along the first direction, and the two guide plates are respectively located on opposite sides of the fire duct body along the second direction. Each guide plate has a main body with a folded edge plate on both sides along the third direction. The folded edge plate is bent relative to the main body towards the side closer to the fire duct body, and the folded edge plate abuts against the outer wall of the fire duct body. The first direction, the second direction, and the third direction are arranged perpendicularly to each other.

10. The fire rack according to any one of claims 1 to 9, characterized in that, The flow guide further includes a connecting arm that connects the two flow guide plates. Multiple connecting arms are spaced apart along the length of the fire orifice plate, and multiple connecting arms abut against the side of the fire orifice plate away from the mixing chamber.

11. A burner, characterized in that, Includes the fire rack as described in any one of claims 1 to 10.

12. A water heater, characterized in that, Including the burner as described in claim 11.

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