Anti-backfire full-premixing burner and main heat exchanger thereof

Abstract

The invention discloses an anti-backfire full-premixing combustor and a main heat exchanger thereof, the full-premixing combustor comprises a fixed flange, a premixed gas diffusion cylinder and a combustion cylinder, the premixed gas diffusion cylinder comprises an abutting part, a connecting part and a diffusion part, the diffusion part extends to the fixed flange, and a gas flowing gap is formed between the diffusion part and the combustion cylinder; one end of the combustion cylinder is connected with the abutting part in a sealed mode, and the other end of the combustion cylinder is communicated with the fixing flange. According to the full-premixing burner, the premixing gas diffusing barrel with the diffusing function is arranged, the process that gas is firstly conveyed to the center of the burning barrel and then diffused to the periphery in the conveying process is avoided, therefore, the burning distance is shortened, it is guaranteed that the gas pressure is stable in the soft fire state, and when it is guaranteed that big fire is converted into soft fire, the combustion efficiency is improved. And the tempering phenomenon caused by the reduction of the gas pressure can be avoided.

Description

Technical Field

[0001] The invention relates to the technical field of full premix burners, and in particular to a flashback-proof full premix burner and a main heat exchanger thereof. Background Art

[0002] A fully premixed burner is one that achieves full premixing of gas and air in proportion before the gas is burned. Since the combustion speed of a fully premixed burner is not limited by mixing time and mixing space, it has the advantages of fast combustion speed, instant combustion of the mixed gas after leaving the burner fire hole, full combustion, low nitrogen oxide emissions, and low noise. It has been used more and more, especially in condensing water heaters and condensing heating furnaces. At present, the mainstream heating furnace market is still non-fully premixed conventional gas heating furnaces. The technology of fully premixed burners is not mature enough, and there are still many unreasonable aspects in the design of existing burners.

[0003] In the prior art, a fully premixed burner and a main heat exchanger thereof are disclosed. The fully premixed burner is provided with a distribution tube and a combustion tube, and the premixed combustion gas is first distributed in the distribution tube, and then evenly distributed through the ventilation gap, and then burned through the combustion tube. The stability of flame combustion and the combustion efficiency are improved by reasonable arrangement of gas distribution holes and combustion holes. However, in the above technology, since the gas has a decompression effect after passing through the gas distribution holes of the distribution tube, it will affect the combustion speed of the gas, so that in the process of switching from high fire to low fire, there is an unstable gas pressure, which may cause flashback and flameout, affecting the normal operation of the water heater. Summary of the invention

[0004] In order to overcome the deficiencies of the prior art, one of the objectives of the present invention is to provide a fully premixed burner with anti-flashback to solve the above-mentioned traditional problems.

[0005] A second object of the present invention is to provide a main heat exchanger using the anti-flashback full premix burner.

[0006] One of the purposes of the present invention is achieved by the following technical solution: A backfire-proof full premix burner comprises a fixed flange, a premix diffuser mounted on the fixed flange, and a combustion tube sleeved outside the premix diffuser, the premix diffuser comprising an abutment portion, a connection portion, and a diffuser extending from the connection portion toward the combustion tube, the diffuser extending to the fixed flange, and a gas flow gap being provided between the diffuser and the combustion tube; one end of the combustion tube is sealedly connected to the abutment portion, and the other end of the combustion tube is communicated with the fixed flange.

[0007] Preferably, the fixing flange includes a seat body and a mounting portion extending from the seat body toward the combustion tube, the seat body is provided with an air inlet hole and fixing holes arranged around the air inlet hole, the air inlet hole longitudinally passes through the middle of the mounting portion, and the fixing holes are evenly distributed.

[0008] Preferably, the diffuser portion is provided with an arc diffuser head portion and a cylindrical portion, the arc diffuser head portion is semi-arc-shaped or semi-circular, and the cylindrical portion is cylindrical.

[0009] Preferably, the gap distance between the cylindrical portion and the combustion tube is greater than (1 / 4-1 / 3) of the radius of the combustion tube, and the gap distance between the cylindrical portion and the combustion tube is less than (1 / 3-1 / 2) of the arc-shaped diffuser head portion.

[0010] Preferably, the combustion tube is provided with a plurality of combustion hole groups consisting of repeating units, and the combustion hole groups are in a U-shape, and each of the combustion hole groups includes a main fire hole, a fire stabilizing hole and an anti-flashback hole. The main fire hole is arranged at the four corners of the combustion hole group, the fire stabilizing hole is arranged in the middle of the combustion hole group, and the anti-flashback hole is arranged between adjacent main fire holes. In the longitudinal direction, adjacent combustion hole groups are provided with overlapping parts, and in the transverse direction, adjacent combustion hole groups are provided with combustion gaps.

[0011] Preferably, the main fire hole and the anti-flashback hole are both circular holes, the diameter of the main fire hole is larger than the diameter of the anti-flashback hole, the fire stabilizing hole is an elongated strip, and the width of the fire stabilizing hole is equal to the diameter of the anti-flashback hole.

[0012] Preferably, the total area occupied by the anti-flashback holes is smaller than the total area occupied by the fire stabilizing holes, and the total area occupied by the fire stabilizing holes is smaller than the total area occupied by the main fire holes.

[0013] Preferably, the total area of ​​the anti-flashback holes is (0.5-0.9) of the total area of ​​the fire stabilizing holes.

[0014] Preferably, the total area occupied by the fire stabilizing holes is (0.5-0.9) of the total area occupied by the main fire holes.

[0015] The second object of the present invention is achieved by adopting the following technical solution: A main heat exchanger comprises the anti-flashback full premix burner described above.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The fully premixed burner of the present invention avoids the process in which the gas is first transported to the center of the combustion tube and then diffused to the surroundings by providing a premixed gas diffusion tube with a diffusion effect, thereby shortening the combustion distance, ensuring the stability of the gas pressure under low fire conditions, and avoiding the flashback phenomenon caused by the reduction of gas pressure when ensuring that the high fire is turned into low fire.

[0017] 2. The combustion tube of the present invention is designed and arranged with the main fire hole, the flame stabilizing hole and the anti-flashback hole. The three holes are rationally cross-arranged, which can maintain stable combustion under low-fire conditions and prevent the main fire hole from flashing back under low-load conditions. Thus, the full premix burner can maintain stable flame operation under all conditions, making the combustion more complete and the combustion efficiency higher, and can solve the problems of unstable combustion, flashback and flameout of the full premix burner. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a three-dimensional structural diagram of the full premixed burner of the present invention; Figure 2 for Figure 1 A bottom view of a fully premixed burner is shown; Figure 3 for Figure 1 An exploded view of a fully premixed burner is shown; Figure 4 for Figure 1 A cross-sectional view of a fully premixed burner is shown; Figure 5 for Figure 1 An expanded view of the combustion tube shown; Figure 6 for Figure 5 An enlarged view of point A is shown; Figure 7 for Figure 1 A cross-sectional view of a fully premixed burner is shown mounted on a main heat exchanger.

[0019] In the figure: 100, full premix burner; 10, fixing flange; 11, seat body; 12, mounting portion; 13, fixing hole; 14, positioning hole; 20, premix gas diffuser; 21, abutment portion; 22, connecting portion; 23, diffuser; 30, combustion tube; 31, main fire hole; 32, fire stabilizing hole; 33, anti-backfire hole. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0021] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0022] In the description of the present invention, it should be understood that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be intermediate elements at the same time. On the contrary, when an element is said to be "directly" connected to another element, there are no intermediate elements.

[0023] See also Figure 1-Figure 7 , which is a preferred embodiment of a backfire-proof full premix burner 100 of the present invention, is used to be installed on a condensing water heater or a condensing heating furnace. The condensing water heater or the condensing heating furnace includes a main heat exchanger. By igniting the gas on the full premix burner 100, the heat energy generated is exchanged with the system water of the main heat exchanger to obtain heated system water.

[0024] Specifically, the main heat exchanger includes a premixing chamber, a fan, a mixed gas delivery channel, a full premixing burner 100, a stainless steel coil and a smoke collecting chamber arranged in sequence along the flow direction of the airflow. The premixing chamber has an air inlet and a gas inlet, and the air and gas are sucked into the premixing chamber for mixing. The main heat exchanger is equipped with an ignition needle and a flame detection needle located on one side of the full premixing burner 100. The ignition needle is used to ignite the mixed gas, and the flame detection needle is used to detect whether the flame is ignited or extinguished. There is a flue gas discharge channel between the stainless steel coil and the full premixing burner 100, which is used for the high-temperature flue gas to be concentratedly discharged into the smoke collecting chamber after heat exchange with the stainless steel coil. The working principle of the main heat exchanger is: the air and gas are preliminarily mixed in the premixing chamber, the fan conveys the mixed mixed gas to the full premixing burner 100, evenly distributes it, and then ignites it under the action of the ignition needle, transfers the heat to the cold water in the stainless steel coil, and the flue gas after heat exchange is collected in the smoke collecting chamber and discharged.

[0025] In one embodiment, the full premix burner 100 includes a fixing flange 10 , a premix diffuser 20 mounted on the fixing flange 10 , and a combustion tube 30 sleeved outside the premix diffuser 20 .

[0026] Please refer again Figure 1-Figure 3 and Figure 7 The fixing flange 10 includes a seat body 11 and a mounting portion 12 extending from the seat body 11 toward the combustion tube 30. The seat body 11 is roughly disc-shaped. The seat body 11 is provided with an air inlet hole and a fixing hole 13 arranged around the air inlet hole. The air inlet hole runs through the middle of the mounting portion 12 longitudinally, and is used for the mixed gas to flow into the full premixed burner 100. There are four fixing holes 13, and each fixing hole 13 is evenly distributed, so that the mounting seat can be fixed to the mixed gas inlet of the main heat exchanger by bolts. In other embodiments, the number of fixing holes 13 can be determined according to demand. The mounting portion 12 is used to install the combustion tube 30, and is fixed or sealed by welding such as spot welding or full welding. Among them, the outer diameter of the mounting portion 12 is smaller than the inner diameter of the combustion tube 30, so that the combustion tube 30 is sleeved on the mounting portion 12, so as to prevent the mixed gas from flowing out from the connection between the mounting portion 12 and the combustion tube 30, and also avoid affecting the flow rate of the mixed gas. In other embodiments, the seat body 11 is further provided with a positioning hole 14 for positioning the seat body 11 to facilitate its installation.

[0027] Please refer again Figure 3 and Figure 4The premixed gas diffuser 20 is used to divert the mixed gas coming in from the air inlet hole of the fixed flange 10, so that the mixed gas can be dispersed to the combustion tube 30 for ignition and combustion. Specifically, the premixed gas diffuser 20 includes an abutment portion 21, a connection portion 22, and a diffuser portion 23 extending from the connection portion 22 toward the combustion tube 30. The abutment portion 21 is roughly disc-shaped and embedded in the combustion tube 30. It is sealed by welding such as spot welding or full welding. The abutting portion 21 and the connecting portion 22 are bent in sequence to form a stepped structure. The diffuser 23 is roughly in the shape of a hollow arc-head cylindrical tube. The diffuser 23 extends to the mounting portion 12 of the fixed flange 10 and does not extend out of the air inlet of the seat body 11. A gas flow gap is provided between the diffuser 23 and the combustion tube 30. It can be understood that the diffuser 23 is provided with an arc-shaped diffuser head portion and a cylindrical portion. The arc-shaped diffuser head portion is roughly in a semi-arc shape or a semi-circular shape, and the cylindrical portion is roughly in a cylindrical shape, so that after the mixed gas collides on the diffuser 23, it is diverted into the gas flow gap, and then flows out of the combustion tube 30 to ignite and burn. In one embodiment, the gap distance between the cylindrical portion and the combustion tube 30 is greater than (1 / 4-1 / 3) of the radius of the combustion tube 30, and the gap distance between the cylindrical portion and the combustion tube 30 is less than (1 / 3-1 / 2) of the arc-shaped diffuser head portion. In the above structure, by providing the diffuser 23, the combustion distance is shortened, the gas pressure is kept stable under low fire conditions, and the flashback phenomenon caused by the reduction of gas pressure can be avoided when ensuring that the high fire is switched to the low fire.

[0028] Please refer again Figure 4-Figure 6 The combustion tube 30 is roughly cylindrical and is mounted on the mounting portion 12 of the fixed flange 10. The combustion tube 30 and the premixed gas diffuser 20 are concentric cylinders. One end of the combustion tube 30 is sealed by the abutment portion 21 of the premixed gas diffuser 20, and the other end of the combustion tube 30 is connected to the air inlet of the fixed flange 10. Specifically, the combustion tube 30 is provided with a plurality of combustion hole groups composed of repeated units (such as Figure 6 As shown in a and b), the combustion hole groups are roughly in the shape of a U, and each combustion hole group includes a main fire hole 31, a fire stabilizing hole 32 and an anti-flashback hole 33. The main fire hole 31 is arranged at the four corners of the combustion hole group, the fire stabilizing hole 32 is arranged in the middle of the combustion hole group, and the anti-flashback hole 33 is arranged between adjacent main fire holes 31, that is, the main fire hole 31 and the anti-flashback hole 33 are alternately arranged around the fire stabilizing hole 32 to improve the stability of the flame, wherein in the longitudinal direction, adjacent combustion hole groups are provided with overlapping parts, and in the transverse direction, adjacent combustion hole groups are provided with combustion gaps. In one embodiment, the main fire hole 31 and the anti-flashback hole 33 are both circular holes, the diameter of the main fire hole 31 is larger than the diameter of the anti-flashback hole 33, the fire stabilizing hole 32 is long strip, and the width of the fire stabilizing hole 32 is equal to the diameter of the anti-flashback hole 33, wherein in the longitudinal direction, the number of the anti-flashback hole 33 is one, and in the transverse direction, the number of the anti-flashback hole 33 is two.

[0029] Specifically, Figure 6 As shown, the combustion tube 30 is a rectangular metal plate in the unfolded state, with a thickness of 0.7-1.5mm and made of stainless steel; large and small round holes + long strip holes are evenly arranged in the X and Y directions of the metal plate, the first row is composed of two large round holes sandwiched between two small round holes along the X-axis array in the X-axis direction, and the second row is composed of two small round holes + one long strip hole along the X-axis array in the X-axis direction, the long strip holes on the combustion tube 30 are the fire stabilizing holes 32 of the burner, the large round holes are the main fire holes 31, and the small round holes are the anti-flashback holes 33; wherein the total area of ​​the anti-flashback holes 33 is less than the total area of ​​the fire stabilizing holes 32 and less than the total area of ​​the main fire holes 31, and preferably, the total area of ​​the anti-flashback holes 33 is (0 .5-0.9), such as 0.5, 0.6, 0.7, 0.8, 0.9, etc., the total area of ​​the stabilizing holes 32 is (0.5-0.9) of the total area of ​​the main fire holes 31, such as 0.5, 0.6, 0.7, 0.8, 0.9, etc.; the stabilizing holes 32 are designed to be small long holes, which can stabilize the flame combustion. If the stabilizing holes 32 are too small, it is easy to cause flameout, resulting in unstable combustion and easy flameout. Therefore, in order to prevent the flameout that may be caused locally when the burner is under full load and high fire; flashback occurs because when the speed of the gas fire hole is lower than the combustion speed, the flame will shrink into the fire hole, causing the mixed gas to burn and heat inside the burner, and forming incomplete combustion, causing the burner to burn out. Because the premixed burner has a fast combustion speed, a flame stabilizing hole 32 designed too large can easily cause flashback. Therefore, the anti-flashback hole 33 is set to the smallest circular hole, which can increase the flow rate while avoiding flashback in the burner, making the combustion more complete and improving the combustion efficiency. The three holes are reasonably cross-arranged, which can maintain stable combustion under low-fire conditions and prevent the main fire hole 31 from flashing under low-load conditions. This allows the fully premixed burner 100 to maintain stable flame operation in all conditions, making the combustion more complete and the combustion efficiency higher, and can solve the problems of unstable combustion, flashback and flameout of the fully premixed burner 100.

[0030] The operating principle of the hot water boiler is as follows: gas enters the premixing chamber through the gas control proportional valve, and air enters the premixing chamber inside the furnace through the outer shaft of the balanced chimney. After the gas and air are mixed in the premixing chamber, they enter the fan. The fan rotates to send the mixed gas of gas and air to the burner, and ignites the mixed gas through the ignition needle discharge. Flame is generated around the burner, and the flame detection needle checks the ion signal generated by the flame. When the flame detection needle fails to detect the flame signal, it is fed back to the main control board to shut down the furnace operation. Therefore, the flame stability of the ignition area and the flame detection area of ​​the burner directly determines the combustion stability of the furnace. In particular, the full premixed combustion mode, under the low fire state, has the characteristics of low flame burning height and burning speed, which is particularly prone to flashback or flameout. In order to solve the current technical shortcomings, the new technology burner sets small round holes in the ignition area and the flame detection area as the flame stabilization area, which greatly provides full premixed combustion under the low fire state. Due to the unstable state of the combustion flame, the flame cannot be detected, causing the furnace to malfunction. At the same time, reduce the power of the small fire and improve the power regulation ratio of the furnace operation.

[0031] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0032] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A fully premixed burner with anti-flashback, characterized in that: It includes a fixed flange, a premixed gas diffuser installed on the fixed flange, and a combustion tube sleeved outside the premixed gas diffuser, the premixed gas diffuser includes an abutment portion, a connection portion, and a diffuser portion extending from the connection portion toward the combustion tube, the diffuser portion extends to the fixed flange, and a gas flow gap is provided between the diffuser portion and the combustion tube; one end of the combustion tube is sealedly connected to the abutment portion, and the other end of the combustion tube is communicated with the fixed flange.

2. The anti-flashback full premix burner according to claim 1, characterized in that: The fixing flange includes a seat body and a mounting portion extending from the seat body toward the combustion tube. The seat body is provided with an air inlet hole and fixing holes arranged around the air inlet hole. The air inlet hole longitudinally passes through the middle of the mounting portion, and the fixing holes are evenly distributed.

3. The anti-flashback full premix burner according to claim 1, characterized in that: The diffuser portion is provided with an arc diffuser head portion and a cylindrical portion. The arc diffuser head portion is semi-arc-shaped or semi-circular, and the cylindrical portion is cylindrical.

4. The anti-flashback full premix burner according to claim 3, characterized in that: The gap distance between the cylindrical part and the combustion tube is greater than (1 / 4-1 / 3) of the radius of the combustion tube, and the gap distance between the cylindrical part and the combustion tube is less than (1 / 3-1 / 2) of the arc diffuser head part.

5. The anti-flashback full premix burner according to claim 1, characterized in that: The combustion tube is provided with a plurality of combustion hole groups consisting of repeating units, and the combustion hole groups are in a U-shape. Each of the combustion hole groups includes a main fire hole, a fire stabilizing hole and an anti-flashback hole. The main fire hole is arranged at the four corners of the combustion hole group, the fire stabilizing hole is arranged in the middle of the combustion hole group, and the anti-flashback hole is arranged between adjacent main fire holes. In the longitudinal direction, adjacent combustion hole groups are provided with overlapping parts, and in the transverse direction, adjacent combustion hole groups are provided with combustion gaps.

6. The anti-flashback full premix burner according to claim 5, characterized in that: The main fire hole and the anti-flashback hole are both circular holes, the diameter of the main fire hole is larger than the diameter of the anti-flashback hole, the fire stabilizing hole is an elongated strip, and the width of the fire stabilizing hole is equal to the diameter of the anti-flashback hole.

7. The anti-flashback full premix burner according to claim 5, characterized in that: The total area occupied by the anti-backfire holes is less than the total area occupied by the fire stabilizing holes, and the total area occupied by the fire stabilizing holes is less than the total area occupied by the main fire holes.

8. The anti-flashback full premix burner according to claim 7, characterized in that: The total area of ​​the anti-flashback holes is (0.5-0.9) of the total area of ​​the fire stabilizing holes.

9. The anti-flashback full premix burner according to claim 7, characterized in that: The total area of ​​the fire stabilizing holes is (0.5-0.9) of the total area of ​​the main fire holes.

10. A main heat exchanger, characterized in that: A fully premixed burner with anti-flashback as claimed in any one of claims 1 to 9.

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