Regenerative graded premixing burner

Abstract

The invention relates to a backheating type graded premixing burner which is suitable for normal pressure and pressurization conditions and comprises a backheating cover, an inner wall, an outer wall, a premixing net cover cup, an ignition needle, a thermocouple, a fuel pipeline, a water receiving basin and a support under the normal pressure, and a backheating type air backheating channel is formed among the backheating cover, the inner wall and the outer wall. Fuel enters the annular premixing cavity between the inner wall and the premixing mesh cup from the bottom to be mixed with air, and then enters the central area through the premixing mesh cup to achieve secondary mixed combustion with the turn-back type return air flow. Under the pressurization condition, fuel enters the annular premixing cavity through one or more pipelines in the tangential direction, circumferential flow is formed in the annular premixing cavity, primary mixing with air is achieved, premixed gas in the annular premixing cavity is rapidly transpired under the action of high-temperature and high-pressure air, and sufficient mixed combustion is achieved; the initial temperature and the highest combustion temperature of the air can be improved by recovering heat energy under the same fuel consumption, the premixed combustion temperature of the contact assembly is relatively low, and the durability of the equipment is improved while the heat efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of burners, and in particular to a regenerative staged premixed burner. Background Art

[0002] Currently, the burners on the market mainly adjust the fire power by adjusting the gas volume and air-fuel ratio. Some commercial equipment uses blower equipment to assist combustion to increase the overall power. The mixing method is mostly single-stage direct mixing. Due to the influence of air flow velocity, it is easy to cause uneven flames or even cause the flame to go out.

[0003] Most burners use a diffusion structure and have no heat recovery function, which not only causes energy waste but also increases ambient temperature and noise. The harsh environment not only damages the health of relevant personnel, but also ultimately increases the corresponding repair and management costs. Summary of the Invention

[0004] In order to improve the thermal efficiency of the burner, improve the flame uniformity and enhance the durability of the equipment, the present invention discloses a regenerative staged premixed burner, which uses staged premixed combustion technology to improve the uniformity of the flame and uses a regenerative structure to improve the overall thermal efficiency. While recovering heat energy, it can cool related components and enhance durability.

[0005] According to the above-mentioned regenerative staged premixed burner, the following technical solutions are implemented:

[0006] A regenerative staged premixing burner comprises a regenerative cover, inner and outer walls, a premixing mesh cup, an ignition needle and a thermocouple, a fuel pipeline, a water basin and a bracket under normal pressure. A return air regenerative channel is formed between the regenerative cover and the inner and outer walls. The fuel enters the annular premixing chamber between the inner wall and the premixing mesh cup from the bottom and mixes with the air. The fuel then enters the central area through the premixing mesh cup and realizes secondary mixing and combustion with the return regenerative airflow.

[0007] The premixing mesh cup under normal pressure forms an annular premixing chamber with the inner wall. The gas enters the premixing chamber from the bottom through the hollow round feet of the inner wall component. The upper part of the premixing mesh cup has an annular fire hole array. The lowest opening position is level with or slightly lower than the top position of the ignition needle and the thermocouple. There is no hole in the lower part to prevent the gas from entering the central main combustion area without premixing.

[0008] The heat recovery cover and the inner and outer walls under normal pressure form a return heat recovery channel, wherein the channel area formed by the heat recovery cover and the outer wall, the channel area formed by the outer wall and the inner wall, and the ring formed by the top of the outer wall and the top of the heat recovery cover can be equal in area or form a gradual relationship to form a heat recovery airflow channel without sudden changes.

[0009] Under supercharging conditions, the outer duct is used as a heat recovery channel, and an annular premixing chamber is set radially with the common central axis of the inner and outer ducts as the axial direction. After the air in the outer duct is compressed, it is diffused through a hemispherical nozzle (similar to a Laval nozzle), and a high-temperature and high-pressure airflow is formed on the basis of diffusion. The gas or liquid fuel is injected into the annular premixing chamber along the tangential direction, forming a circular motion and preliminarily mixed with the air in the premixing chamber to burn. The gas of the primary premixed combustion is rapidly diffused and fully burned under the evaporation of the high-temperature and high-pressure airflow.

[0010] In some embodiments, the premixing mesh cup under normal pressure uses a circular fire hole array, the openings of which are horizontally oriented and arranged centripetally toward the central axis.

[0011] In some embodiments, the openings of the premixing mesh cup fire hole array under normal pressure have a certain horizontal inclination angle and are arranged centripetally toward the central axis.

[0012] In some embodiments, the premixing mesh cups at normal pressure use a grid array, which is perpendicular to the horizontal or forms a certain angle and is arranged centripetally toward the central axis.

[0013] In some embodiments, the heat recovery hood under normal pressure opens downward, the air intake return path is long, the thermal isolation effect is good, and the inner and outer walls can be cooled and heat energy recovered more completely at the same time.

[0014] In some embodiments, the opening of the regenerative cover at normal pressure faces horizontal directions on both sides, the air intake return path is short, the air intake efficiency is high, and the inner wall and the inner side of the outer wall are mainly cooled and heat energy is recovered.

[0015] In some embodiments, an auxiliary valve adjustment device is provided at the bottom of the outer wall assembly under normal pressure, and its adjustment range can achieve continuous adjustment from fully closed to fully open of the fan-shaped hole, which is used to assist in fine-tuning the intake to achieve the optimal air-fuel ratio, and also facilitates obstacle clearance.

[0016] In some embodiments, the annular premixing chamber under pressure forms a certain angle with the axial direction, and the opening direction of the premixing chamber forms a certain angle with the axial airflow direction.

[0017] In some embodiments, the diameter of the fuel ring in the annular premixing chamber under pressure is consistent with the diameter of the fuel pipeline, and the total cross-sectional area of the primary premixing chamber is larger than the cross-sectional area of the fuel ring and increases in a stepwise manner.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] 1. Improve thermal efficiency: Under normal pressure conditions, normal-temperature air passes through the return heat recovery channel, raising the initial air temperature. The gas is initially mixed in the annular premixing chamber and then fully mixed with the higher-temperature air before combustion. Under the premise of consuming the same fuel, the maximum combustion temperature is also higher, which can significantly improve thermal efficiency. Under supercharged conditions, the outer duct serves as a heat recovery channel. The air absorbs heat from the outer wall of the inner duct and its temperature rises. After being compressed by the compressor assembly, the temperature is further increased. Under the premise of a higher initial air temperature, the expected combustion temperature can be achieved with less fuel consumption.

[0020] 2. Improve the heat resistance and service life of the equipment: Under normal pressure conditions, the air absorbs heat through the return heat recovery channel while efficiently cooling the heat recovery cover, inner and outer walls and premixing mesh cup. The annular premixing chamber formed between the inner wall and the premixing mesh cup is small in volume. Under normal operation, the primary premixed combustion is incomplete combustion, its combustion temperature is low and there is a reducing protective atmosphere. The mixed gas of the primary premixed combustion expands into the center position of the premixing mesh cup and mixes with the heat recovery airflow for full combustion. The low-temperature combustion zone is isolated from the high-temperature combustion zone, avoiding direct high-temperature burning of the equipment; under pressurized conditions, the outer duct serves as a heat recovery channel, and the fast-flowing low-temperature air can cool the outer wall of the inner duct in real time and efficiently. The primary combustion temperature of the annular premixing chamber is low and there is a reducing protective atmosphere, which can achieve graded isolation from the high-temperature combustion gas, and can effectively extend the heat resistance and service life of the equipment.

[0021] 3. Reduce material and manufacturing costs: Under normal pressure conditions, compared with the casting or forging process of key components of traditional burners, the main components are made of thin-walled plates or tubes, and low-cost sheet metal and ordinary mechanical processing processes can be used. Whether it is the total weight of the material, manufacturing equipment or manufacturing process, there is a clear cost advantage; under pressurized conditions, since the key components are well cooled, general high-temperature resistant materials such as 310S stainless steel can be used, and there is no need to use expensive special materials, which has advantages in material costs and processing equipment costs.

[0022] 4. Optimize structure and improve environmental adaptability: Under normal pressure conditions, the burner adopts a sunken structure design, and the height of the table part used by the user can be reduced. Combined with the heat recovery design of the system, the environmental heat radiation can be significantly improved; under pressurized conditions, the outer duct is used as the heat recovery channel, and the temperature of the equipment casing will be greatly reduced. In addition to reducing environmental heat radiation, it can also expand the optional installation location and use environment of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attachment Figure 1 This is a normal pressure structural exploded view of a regenerative staged premixed burner according to the present invention.

[0024] Attachment Figure 2This is a front cross-sectional view of the normal pressure structure of a regenerative staged premixed burner of the present invention.

[0025] Attachment Figure 3 This is a schematic diagram of the bottom of the normal pressure structure of a regenerative staged premixed burner of the present invention.

[0026] Attachment Figure 4 It is a schematic front view of the normal pressure structure of a regenerative staged premixed burner of the present invention.

[0027] Attachment Figure 5 This is a front cross-sectional view of an improved version of a normal-pressure structure regenerative cover of a regenerative staged premixed burner according to the present invention.

[0028] Attachment Figure 6 This is a wireframe diagram of the boost structure of a regenerative staged premixed burner of the present invention.

[0029] Attachment Figure 7 This is a schematic diagram of the boost structure of a regenerative staged premixed burner of the present invention.

[0030] Attachment Figure 8 This is a schematic diagram of the overall framework of the boost structure of a regenerative staged premixed burner of the present invention.

[0031] Attachment Figure 9 This is a detailed schematic diagram of the premixing chamber and fuel pipe of the boost structure of a regenerative staged premixing burner of the present invention.

[0032] Explanation of the accompanying symbols: 1. gas pipe; 2. thermocouple; 3. ignition needle; 4. outer wall; 5. inner wall; 6. premixing mesh cup; 7. heat recovery cover; 8. water basin; 9. bracket. DETAILED DESCRIPTION

[0033] The following examples illustrate the present invention, but the present invention is not limited to these examples. Modifications to the specific implementation methods of the present invention or equivalent replacements of some technical features without departing from the spirit of the present invention should be included in the scope of the technical solution claimed for protection of the present invention.

[0034] Example 1:

[0035] refer to Figure 1The present embodiment discloses a regenerative staged premixing burner, comprising a gas pipe 1, an ignition needle 2, a thermocouple 3, an outer wall 4, an inner wall 5, a premixing mesh cup 6, a regenerative cover 7, a water basin 8 and a bracket 9; the gas pipe 1 is made of a standard round tube, bent according to the circumference, and the end is closed. Branch air intake pipes are evenly arranged at an angle along the vertical direction of the circumference. The diameter of the branch air intake pipe does not exceed the diameter of the gas pipe. The gas pipe is fixed to the bottom of the stove or to the bottom of the outer wall 4. Holes for the branch air pipes to pass through are reserved on the outer wall 4 as needed. An air intake pin corresponding to the branch air pipe is provided at the bottom of the inner wall 5. The inner diameter of the air intake pin is slightly larger than the outer diameter of the branch air pipe. The inner wall 5 is directly sleeved on the branch air pipe for use. The premixing mesh cup 6 is installed to the inner ring of the inner wall 5 to form an annular premixing chamber. The regenerative cover 7 is installed above the inner wall 5 and the outer wall 4 to form a return heat recovery channel. The thermocouple 2 and the ignition needle 3 are installed through the reserved holes at the bottom of the outer wall 4. The holes are within the range surrounded by the inner wall 5 and are symmetrically distributed around the central axis, maintaining a suitable distance from the premixing mesh cup 6. The water tray 8 and the bracket 9 assembly can be adjusted according to the external dimensions of the stove.

[0036] refer to Figure 2-3 After assembly, a downward-opening return heat recovery channel is formed. The air enters the annular channel between the heat recovery cover 7 and the outer wall 4 from the bottom, returns at the top to enter the annular channel between the outer wall 4 and the inner wall 5, and returns at the bottom of the inner wall 5 to enter the central area of the premixing mesh cup 6; the gas enters the air inlet pin of the inner wall 5 through the gas distribution pipe from the gas pipe fitting 1, and is premixed with the air in the annular premixing cavity between the inner wall 5 and the premixing mesh cup 6. After the primary premixed gas burns and expands, it enters the central area through the mesh of the premixing mesh cup 6, mixes with the preheated air in the heat recovery channel, and is fully burned.

[0037] refer to Figure 4 After the air passes through the return heat recovery channel, the initial temperature increases. After it is fully mixed with the primary premixed gas and burned in the central area of the premixing mesh cup 6, it is easy to form an upward straight flame. If the diameter of the premixing mesh cup 6 is too small, it is easy to cause the flame height to be too high, which may cause a safety hazard. If the diameter is too large, it is easy to form a ring flame or an uneven flame. Therefore, the optimal air-fuel ratio and flame distribution range must be determined according to the pressure and total amount of the gas, and the optimal diameter of the premixing mesh cup 6 can be calculated based on this.

[0038] Example 2:

[0039] refer to Figure 5 Based on Example 1, this embodiment simplifies the heat recovery cover. The heat recovery cover uses an annular cover plate, which covers the inner wall 5 and the outer wall 4. The air inlet direction of the heat recovery channel is horizontal, and air is taken in from the outside. The heat recovery channel path is shorter and the air intake efficiency is higher. However, compared with Example 1, the cooling protection effect on the outer wall 4 is also reduced.

[0040] Example 3:

[0041] refer to Figure 6-9 This embodiment is suitable for supercharging conditions and is mainly used in turboshaft engines or open engines with heat recovery, and can also be used in burners with supercharging components; by using the outer duct as a heat recovery channel, the air passes through the outer duct and absorbs heat from the outer wall of the inner duct, then returns through the head end and is pressurized by the supercharging component (such as a supercharged turbine), and the air temperature will increase significantly and even reach the fuel ignition point; the fuel enters the annular premixing chamber along the tangential direction through one or more pipes, forms a circumferential flow in the annular premixing chamber, and realizes primary mixing with the air. Under the action of high-temperature and high-pressure air, the premixed gas in the annular premixing chamber evaporates rapidly to achieve sufficient mixed combustion.

[0042] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the inventive concept of the present invention, which all fall within the scope of protection of the present invention.

Claims

1. A regenerative staged premixed burner, characterized in that: Under normal pressure conditions, it includes a heat recovery hood, an outer wall, an inner wall, a premixing mesh cup, a water basin and a bracket assembly; a return air heat recovery channel is formed between the heat recovery hood, the outer wall and the inner wall, and an annular premixing cavity is formed between the inner wall and the premixing mesh cup. The central area of the premixing mesh cup is the secondary mixing and main combustion area.

2. A regenerative staged premixed burner, characterized in that: Under the condition of supercharging, it includes an outer duct, an annular premixing chamber, a fuel pipeline and a combustion chamber. The outer duct serves as a heat recovery channel to absorb heat and return the airflow, and the fuel pipeline is connected to the annular premixing chamber along the tangential direction.

3. The regenerative staged premixed burner according to claim 1, characterized in that: The regenerative heat shield and the inner and outer walls under normal pressure form a return regenerative heat channel, wherein the channel area formed by the regenerative heat shield and the outer wall, the channel area formed by the outer wall and the inner wall, and the ring formed by the top of the outer wall and the top of the regenerative heat shield can be equal in area or form a gradual relationship.

4. The regenerative staged premixed burner according to claim 1, characterized in that: The regenerative cover under normal pressure and the outer wall form a bottom annular air inlet opening downward. In a simplified structure, the regenerative cover and the top of the outer wall form an outer annular air inlet in a horizontal direction.

5. The regenerative staged premixed burner according to claim 1, characterized in that: The inner wall component under normal pressure is connected to the branch gas pipe of the gas component through the circular hollow pin at the bottom and the reserved hole in the outer wall, and forms an annular premixing cavity with the premixing mesh cup. The thickness of the annular premixing cavity is equal to the hollow diameter of the circular pin at the bottom of the inner wall.

6. The regenerative staged premixed burner according to claim 1, characterized in that: A circular or grid-shaped fire hole array is used on the upper part of the premixed mesh cup under normal pressure. The openings are horizontal or have a certain horizontal angle and are arranged centripetally toward the central axis. When using grid-shaped fire holes, the grid-shaped fire hole units can be vertical or have a certain tilt angle. The bottom position of the fire hole array is level with or slightly lower than the top of the ignition needle and thermocouple assembly.

7. The regenerative staged premixed burner according to claim 1, characterized in that: The central circle area of the premixing mesh cup under normal pressure is proportional to the cross-sectional area of the heat recovery channel in the airflow direction to achieve the best air-fuel ratio. At the same time, there is an auxiliary valve adjustment device at the bottom of the outer wall. Its adjustment range can achieve continuous adjustment from fully closed to fully open of the fan-shaped hole, which is used to fine-tune the auxiliary air intake and also facilitates obstacle clearance.

8. The regenerative staged premixed burner according to claim 2, characterized in that: Under supercharging conditions, the outer duct is used as a heat recovery channel, and forced air return and compression are performed through a drive component (such as a compressor turbine), and its power can come from a coaxial power turbine or external power.

9. The regenerative staged premixed burner according to claim 2, characterized in that: Under pressurized conditions, the fuel pipeline is connected to the annular premixing chamber along the tangential direction. The outer side of the annular premixing chamber is a semicircular fuel tank with the same diameter as the fuel pipeline, and the inner side is a premixing chamber with a width greater than the diameter of the fuel pipeline. The number of stages is at least one, forming a step-by-step increase in area from the outside to the inside.

10. The regenerative staged premixed burner according to claim 2, characterized in that: Under the supercharging condition, the annular premixing chamber forms a certain angle with the axial direction, and the opening of the premixing chamber faces the central axis.

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