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

Abstract

The utility model 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 arranged 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] This utility model relates to the field of fully premixed burners, specifically to a backfire-proof fully premixed burner and its main heat exchanger. Background Technology

[0002] A fully premixed burner is one in which gas and air are fully premixed in a specific ratio before combustion. Because the combustion speed of a fully premixed burner is not limited by mixing time or space, it offers advantages such as fast combustion, instantaneous combustion of the mixed gas after leaving the burner orifice, complete combustion, low nitrogen oxide emissions, and low noise. It has gained increasing use, especially in condensing water heaters and condensing boilers. However, the use of fully premixed condensing boilers in my country started relatively late. Currently, the mainstream boiler market still uses conventional gas-fired boilers without full premixing technology. Fully premixed burner technology is not yet mature enough, and existing burners still have many design flaws.

[0003] In the prior art, a fully premixed burner and its main heat exchanger are disclosed. The fully premixed burner distributes the premixed combustion gas in the distribution cylinder first by setting a distribution cylinder and a combustion cylinder, and then forms a uniform distribution through the ventilation gap before combustion in the combustion cylinder. The reasonable arrangement of gas distribution holes and combustion holes improves the stability and efficiency of flame combustion. However, in the above technology, the gas pressure is reduced after passing through the gas distribution holes of the distribution cylinder, which affects the combustion speed of the gas. During the process of switching from high flame to low flame, the gas pressure is unstable, which can lead to backfire and flameout, affecting the normal operation of the hot water boiler. Utility Model Content

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of this utility model is to provide a fully premixed burner that prevents backfire, thereby solving the aforementioned traditional problems.

[0005] The second objective of this utility model is to provide a main heat exchanger for a fully premixed burner that employs this anti-backfire design.

[0006] One of the objectives of this utility model is achieved through the following technical solution:

[0007] A premixed burner with backfire prevention includes a fixed flange, a premixed gas diffuser mounted on the fixed flange, and a combustion cylinder sleeved outside the premixed gas diffuser. The premixed gas diffuser includes an abutment portion, a connecting portion, and a diffuser portion extending from the connecting portion toward the combustion cylinder. The diffuser portion extends to the fixed flange, and a gas flow gap is provided between the diffuser portion and the combustion cylinder. One end of the combustion cylinder is sealed to the abutment portion, and the other end of the combustion cylinder is connected to the fixed flange.

[0008] Preferably, the fixed flange includes a seat body and a mounting portion extending from the seat body toward the combustion cylinder. The seat body is provided with an air inlet and fixing holes arranged around the air inlet. The air inlet longitudinally penetrates the middle of the mounting portion, and the fixing holes are evenly distributed.

[0009] Preferably, the diffuser section includes an arc-shaped diffuser head portion and a cylindrical portion. The arc-shaped diffuser head portion is semi-arc or semi-circular in shape, and the cylindrical portion is cylindrical in shape.

[0010] Preferably, the gap between the cylindrical portion and the combustion cylinder is greater than (1 / 4-1 / 3) of the radius of the combustion cylinder, and the gap between the cylindrical portion and the combustion cylinder is less than (1 / 3-1 / 2) of the arc-shaped diffuser portion.

[0011] Preferably, the combustion chamber is provided with multiple sets of combustion hole groups composed of repeating units. The combustion hole groups are in the shape of a "U". Each set of combustion hole groups includes a main flame hole, a flame stabilizing hole, and a backfire prevention hole. The main flame holes are located at the four corners of the combustion hole group, the flame stabilizing hole is located in the middle of the combustion hole group, and the backfire prevention hole is located between adjacent main flame holes. In the longitudinal direction, adjacent combustion hole groups have overlapping portions, and in the transverse direction, there is a combustion gap between adjacent combustion hole groups.

[0012] Preferably, both the main flame hole and the backfire prevention hole are circular holes, the diameter of the main flame hole is larger than the diameter of the backfire prevention hole, and the flame stabilizing hole is elongated, the width of the flame stabilizing hole is equal to the diameter of the backfire prevention hole.

[0013] Preferably, the total area of ​​the backfire prevention holes is less than the total area of ​​the flame stabilization holes, and the total area of ​​the flame stabilization holes is less than the total area of ​​the main flame holes.

[0014] Preferably, the total area of ​​the backfire prevention holes is (0.5-0.9) of the total area of ​​the flame stabilization holes.

[0015] Preferably, the total area of ​​the stabilizing holes is (0.5-0.9) of the total area of ​​the main ignition holes.

[0016] The second objective of this utility model is achieved by the following technical solution:

[0017] A main heat exchanger comprising the aforementioned backfire-proof fully premixed burner.

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] 1. The fully premixed burner of this utility model avoids the process of the gas being transported to the center of the combustion cylinder and then diffused to the surrounding area by setting a premixed gas diffuser with a diffuser function, thereby shortening the combustion distance, ensuring stable gas pressure in low flame state, and avoiding backfire caused by reduced gas pressure when switching from high flame to low flame.

[0020] 2. The combustion chamber of this utility model, through the design and layout of the main flame hole, the flame stabilizing hole and the backfire prevention hole, with the three holes arranged in a reasonable cross pattern, can maintain stable combustion in the low flame state and prevent backfire in the main flame hole under low load conditions. Thus, the fully premixed burner can maintain stable flame operation in all states, making combustion more complete and the combustion efficiency higher. It can solve the problems of unstable combustion, backfire and flameout in the fully premixed burner. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of the fully premixed burner of this utility model;

[0022] Figure 2 for Figure 1 The image shown is a bottom view of the fully premixed burner.

[0023] Figure 3 for Figure 1 The exploded view of the fully premixed burner shown;

[0024] Figure 4 for Figure 1 The cross-sectional view of the fully premixed burner shown;

[0025] Figure 5 for Figure 1 The diagram shows the combustion chamber in its open position.

[0026] Figure 6 for Figure 5 The enlarged view at point A is shown below;

[0027] Figure 7 for Figure 1 The diagram shows a cross-sectional view of a fully premixed burner mounted on a main heat exchanger.

[0028] In the diagram: 100, fully premixed burner; 10, fixed flange; 11, base body; 12, mounting part; 13, fixing hole; 14, positioning hole; 20, premixed gas diffuser; 21, contact part; 22, connection part; 23, diffuser; 30, combustion cylinder; 31, main flame port; 32, flame stabilization port; 33, backfire prevention port. Detailed Implementation

[0029] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0030] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0031] In the description of this utility model, 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 present. Conversely, when an element is referred to as being "directly" connected to another element, there are no intermediate elements.

[0032] Please see Figures 1-7 The premixed burner 100, which is a preferred embodiment of the present invention, is used to install on a condensing water heater or a condensing boiler. The condensing water heater or condensing boiler includes a main heat exchanger. By igniting the gas on the premixed burner 100, the generated heat energy is exchanged with the system water in the main heat exchanger to obtain heated system water.

[0033] Specifically, the main heat exchanger includes a premixing chamber, a fan, a mixed gas delivery channel, a fully premixed burner 100, a stainless steel coil, and a smoke collection chamber arranged sequentially along the airflow direction. The premixing chamber has an air inlet and a gas inlet, drawing air and gas into the premixing chamber for mixing. An ignition needle and a flame detection needle are installed on the main heat exchanger on one side of the fully premixed burner 100. The ignition needle ignites the mixed gas, and the flame detection needle detects whether the flame is ignited or extinguished. A flue gas exhaust channel is located between the stainless steel coil and the fully premixed burner 100, allowing the high-temperature flue gas to exchange heat with the stainless steel coil before being centrally discharged into the smoke collection chamber. The working principle of the main heat exchanger is as follows: air and gas are initially mixed in the premixing chamber; the fan delivers the mixed gas to the fully premixed burner 100 for uniform distribution; then, the mixture is ignited by the ignition needle, transferring heat to the cold water in the stainless steel coil; and finally, the flue gas is collected in the smoke collection chamber and discharged.

[0034] In one embodiment, the fully premixed burner 100 includes a fixed flange 10, a premixed gas diffuser 20 mounted on the fixed flange 10, and a combustion cylinder 30 sleeved around the premixed gas diffuser 20.

[0035] Please refer to this again. Figures 1-3 and Figure 7 The fixed flange 10 includes a base body 11 and a mounting portion 12 extending from the base body 11 toward the combustion cylinder 30. The base body 11 is generally disc-shaped and has an air inlet and fixing holes 13 arranged around the air inlet. The air inlet extends longitudinally through the middle of the mounting portion 12 and is used to allow the mixed gas to flow into the fully premixed burner 100. There are four fixing holes 13, which are evenly distributed so that the mounting base 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 requirements. The mounting portion 12 is used to install the combustion cylinder 30 and is fixed or sealed by welding, such as spot welding or full welding. The outer diameter of the mounting portion 12 is smaller than the inner diameter of the combustion cylinder 30, so that the combustion cylinder 30 is fitted onto the mounting portion 12, preventing the mixed gas from flowing out from the connection between the mounting portion 12 and the combustion cylinder 30, and also preventing the flow rate of the mixed gas from being affected. In some other embodiments, the base body 11 is also provided with positioning holes 14 for positioning the base body 11 to facilitate its installation.

[0036] Please refer to this again. Figure 3 and Figure 4The premixed gas diffuser 20 is used to divert the mixed gas entering from the air inlet of the fixed flange 10, so that the mixed gas can be dispersed to the combustion cylinder 30 for ignition and combustion. Specifically, the premixed gas diffuser 20 includes an abutment portion 21, a connecting portion 22, and a diffuser portion 23 extending from the connecting portion 22 toward the combustion cylinder 30. The abutment portion 21 is generally disc-shaped and is embedded in the combustion cylinder 30. It is sealed by welding, such as spot welding or full welding. The abutment part 21 and the connecting part 22 are bent in sequence to form a stepped structure. The diffuser part 23 is roughly in the shape of a hollow arc-shaped cylindrical tube. The diffuser part 23 extends to the mounting part 12 of the fixed flange 10 and does not extend out of the air inlet of the base body 11. There is a gas flow gap between the diffuser part 23 and the combustion cylinder 30. Understandably, the diffuser part 23 has an arc-shaped diffuser head part and a cylindrical part. The arc-shaped diffuser head part is roughly in the shape of a semi-arc or semi-circle, and the cylindrical part is roughly in the shape of a cylinder. This allows the mixed gas to collide on the diffuser part 23 and then be diverted into the gas flow gap before flowing out from the combustion cylinder 30 and igniting. In one embodiment, the gap between the cylindrical part and the combustion cylinder 30 is greater than (1 / 4-1 / 3) of the radius of the combustion cylinder 30, and the gap between the cylindrical part and the combustion cylinder 30 is less than (1 / 3-1 / 2) of the arc-shaped diffuser part. In the above structure, by setting the diffuser 23, the combustion distance is shortened, the gas pressure is kept stable in the low flame state, and the backfire phenomenon caused by the decrease in gas pressure can be avoided when the high flame is switched to the low flame.

[0037] Please refer to it again. Figures 4-6 The combustion cylinder 30 is roughly cylindrical and is mounted on the mounting portion 12 of the fixed flange 10. The combustion cylinder 30 and the premixed gas diffuser 20 are concentric cylinders. One end of the combustion cylinder 30 is sealed by the abutment portion 21 of the premixed gas diffuser 20, and the other end of the combustion cylinder 30 is connected to the air inlet of the fixed flange 10. Specifically, the combustion cylinder 30 is provided with multiple sets of combustion hole groups composed of repeating units (such as...). Figure 6 As shown in a and b), the combustion hole groups are roughly U-shaped. Each group of combustion holes includes a main flame hole 31, a flame stabilizing hole 32, and a backfire prevention hole 33. The main flame holes 31 are located at the four corners of the combustion hole group, the flame stabilizing hole 32 is located in the middle of the combustion hole group, and the backfire prevention hole 33 is located between adjacent main flame holes 31. That is, the main flame holes 31 and the backfire prevention hole 33 are alternately arranged around the flame stabilizing hole 32 to improve the stability of the flame. In the longitudinal direction, adjacent combustion hole groups have an overlapping part, and in the transverse direction, there is a combustion gap between adjacent combustion hole groups. In one embodiment, the main flame hole 31 and the backfire prevention hole 33 are both circular holes. The diameter of the main flame hole 31 is larger than the diameter of the backfire prevention hole 33. The flame stabilizing hole 32 is elongated, and the width of the flame stabilizing hole 32 is equal to the diameter of the backfire prevention hole 33. In the longitudinal direction, there is one backfire prevention hole 33, and in the transverse direction, there are two backfire prevention holes 33.

[0038] Specifically, such as Figure 6 As shown, the combustion chamber 30, when unfolded, is a rectangular metal plate with a thickness of 0.7-1.5mm, made of stainless steel. The metal plate has uniformly arranged large and small round holes and elongated holes in both the X and Y directions. The first row, along the X-axis, consists of two large round holes sandwiching two small round holes. The second row, along the X-axis, consists of two small round holes and one elongated hole. The elongated hole on the combustion chamber 30 serves as the burner's flame stabilization hole 32, the large round holes as the main flame holes 31, and the small round holes as anti-backfire holes 33. The total area of ​​the anti-backfire holes 33 is less than the total area of ​​the flame stabilization holes 32, which is less than the total area of ​​the main flame holes 31. Preferably, the total area of ​​the anti-backfire holes 33 is (0.5%) of the total area of ​​the flame stabilization holes 32. The area of ​​the stabilizing hole 32 is 0.5-0.9% of the total area of ​​the main burner hole 31, such as 0.5, 0.6, 0.7, 0.8, 0.9, etc. The stabilizing hole 32 is designed as a small elongated hole to stabilize the flame combustion. If the stabilizing hole 32 is too small, it is easy to cause flameout, resulting in unstable combustion and easy flameout. Therefore, in order to prevent the flameout phenomenon that may occur locally when the burner is under full load and high fire, backfire occurs because when the gas flame velocity is less than the combustion velocity, the flame will retract into the flame hole, causing the mixed gas to burn and heat inside the burner, forming incomplete combustion, which will cause the burner to burn out. Because the premixed burner has a fast combustion speed, an overly large flame stabilizer orifice 32 can easily lead to backfire. Therefore, the backfire prevention orifice 33 is set to the smallest circular orifice. This increases the flow rate while preventing backfire, resulting in more complete combustion and improved combustion efficiency. The reasonable cross-arrangement of the three orifices maintains stable combustion under low flame conditions and prevents backfire from occurring in the main flame orifice 31 under low load conditions. This allows the fully premixed burner 100 to maintain stable flame operation under various conditions, resulting in more complete combustion and higher combustion efficiency. It can solve the problems of unstable combustion, backfire, and flameout in the fully premixed burner 100.

[0039] The operating principle of the hot water boiler is as follows: Gas enters the premixing chamber through a gas control proportional valve, while air enters the premixing chamber inside the boiler through the outer shaft of the balanced chimney. After mixing in the premixing chamber, the gas and air enter the blower. The blower, by rotation, sends the gas-air mixture to the burner, where it is ignited by an ignition needle. A flame is generated around the burner, and a flame detection needle checks the ion signal generated by the flame. If the flame detection needle fails to detect a flame signal, feedback is sent to the main control board, shutting down the boiler. Therefore, the flame stability in the burner's ignition and flame detection areas directly determines the boiler's combustion stability. Especially in fully premixed combustion, the low flame height and combustion speed at low flame conditions make it particularly prone to backfire or flameout. To address these shortcomings, the new burner design incorporates small circular holes in the ignition and flame detection areas to stabilize the flame. This significantly improves the boiler's performance at low flame conditions, preventing flame instability and potential malfunctions. Simultaneously, it reduces the low flame power and increases the power adjustment ratio between high and low flames.

[0040] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0041] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A fully premixed burner with backfire prevention, characterized in that, The device includes a fixed flange, a premixed gas diffuser mounted on the fixed flange, and a combustion cylinder sleeved around the premixed gas diffuser. The premixed gas diffuser includes an abutment portion, a connecting portion, and a diffuser portion extending from the connecting portion toward the combustion cylinder. The diffuser portion extends to the fixed flange, and a gas flow gap is provided between the diffuser portion and the combustion cylinder. One end of the combustion cylinder is sealed to the abutment portion, and the other end of the combustion cylinder is connected to the fixed flange.

2. The anti-backfire fully premixed burner according to claim 1, characterized in that, The fixed flange includes a base body and a mounting portion extending from the base body toward the combustion cylinder. The base body is provided with an air inlet and fixing holes arranged around the air inlet. The air inlet longitudinally penetrates the middle of the mounting portion, and the fixing holes are evenly distributed.

3. The anti-backfire fully premixed burner according to claim 1, characterized in that, The diffuser section includes an arc-shaped diffuser head and a cylindrical section. The arc-shaped diffuser head is semi-arc or semi-circular in shape, and the cylindrical section is cylindrical in shape.

4. The anti-backfire fully premixed burner according to claim 3, characterized in that, The gap between the cylindrical portion and the combustion cylinder is greater than 1 / 4 to 1 / 3 of the radius of the combustion cylinder, and the gap between the cylindrical portion and the combustion cylinder is less than 1 / 3 to 1 / 2 of the arc-shaped diffuser portion.

5. The anti-backfire fully premixed burner according to claim 1, characterized in that, The combustion chamber is provided with multiple sets of combustion hole groups composed of repeating units. The combustion hole groups are in the shape of a "U". Each set of combustion hole groups includes a main flame hole, a flame stabilizing hole and a backfire prevention hole. The main flame holes are located at the four corners of the combustion hole group. The flame stabilizing hole is located in the middle of the combustion hole group. The backfire prevention hole is located between adjacent main flame holes. In the longitudinal direction, adjacent combustion hole groups have overlapping parts. In the transverse direction, there is a combustion gap between adjacent combustion hole groups.

6. The backfire-proof fully premixed burner according to claim 5, characterized in that, Both the main flame hole and the backfire prevention hole are circular holes, with the diameter of the main flame hole being larger than that of the backfire prevention hole. The flame stabilizing hole is elongated, with its width equal to the diameter of the backfire prevention hole.

7. The anti-backfire fully premixed burner according to claim 5, characterized in that, The total area of ​​the backfire prevention holes is less than the total area of ​​the flame stabilization holes, and the total area of ​​the flame stabilization holes is less than the total area of ​​the main flame holes.

8. The backfire-proof fully premixed burner according to claim 7, characterized in that, The total area of ​​the backfire prevention holes is 0.5-0.9 of the total area of ​​the flame stabilization holes.

9. The backfire-proof fully premixed burner according to claim 7, characterized in that, The total area of ​​the stabilizing holes is 0.5-0.9 of the total area of ​​the main fire holes.

10. A main heat exchanger, characterized in that, Including the backfire-proof fully premixed burner as described in any one of claims 1-9.

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