A direct-fired combustion structure

Abstract

This application discloses a direct-fired combustion structure, belonging to the field of combustion equipment. The combustion structure includes a combustion chamber body, with a fuel inlet at one end and a combustion outlet at the other end. An air preheating channel is arranged around the outer wall of the combustion chamber body, with one end connected to the outside air and the other end connected to the interior of the combustion chamber body. Inside the combustion chamber body, on one side of the fuel inlet, spiral guide vanes are arranged in a spiral pattern around the fuel inlet. By setting the spiral guide vanes, air can be guided to flow in a spiral direction, fully mixing with the atomized fuel, improving the mixing effect of fuel and air, promoting combustion, making combustion more complete, improving thermal efficiency, and reducing pollutant emissions. By setting the air preheating channel, the heat of the combustion chamber body can be used to preheat the air, increasing the air temperature and promoting fuel combustion.

Description

Technical Field

[0001] This application relates to the field of combustion equipment technology, specifically a direct-fired combustion structure. Background Technology

[0002] Direct-fired combustion structures are widely used in industrial heating, household heating equipment, and gas-fired power generation, and their performance directly affects energy utilization efficiency and pollutant emission levels.

[0003] Existing direct-fired combustion structures typically include a combustion chamber body, a fuel inlet, and an air inlet. Fuel and air enter the combustion chamber through independent channels and mix for combustion. Because the fuel-air mixing method is relatively simple, the mixing effect is often poor, leading to incomplete combustion and low thermal efficiency.

[0004] Therefore, this application provides a direct-fired combustion structure to solve the above problems. Utility Model Content

[0005] This application provides a direct-fired combustion structure, which aims to solve the problems of insufficient fuel-air mixing and low combustion efficiency in existing direct-fired combustion structures mentioned in the background art.

[0006] To achieve the above objectives, this application provides the following technical solution: a direct-fired combustion structure, comprising a combustion chamber body, one end of which has a fuel inlet and the other end has a combustion outlet; an air preheating channel is arranged around the outer wall of the combustion chamber body, one end of which communicates with the outside air and the other end with the interior of the combustion chamber body; a spiral guide vane is arranged inside the combustion chamber body on one side of the fuel inlet, the spiral guide vane being spirally distributed around the fuel inlet. By setting the spiral guide vane, air can be guided to flow along the spiral direction, fully mixing with the atomized fuel, improving the mixing effect of fuel and air, promoting combustion, making combustion more complete, improving thermal efficiency, and reducing pollutant emissions; by setting the air preheating channel, the heat of the combustion chamber body can be used to preheat the air, increasing the air temperature and further promoting fuel combustion.

[0007] Preferably, the combustion chamber body is cylindrical. The cylindrical design of the combustion chamber body provides a uniform flow space for the internal airflow, avoiding airflow turbulence caused by abrupt changes in cross-section. This facilitates the stable development of the spiral airflow guided by the spiral guide vanes, ensuring a uniform and continuous mixing flow field between fuel and air within the combustion chamber, thereby improving combustion stability and completeness. Furthermore, the cylindrical outer wall facilitates the surrounding arrangement of air preheating channels (spiral) or double-layer jackets, maximizing the heat exchange area and improving waste heat utilization efficiency.

[0008] Preferably, to increase the contact area between fuel and air, a fuel atomizing nozzle is provided at the fuel inlet to atomize the fuel into fine particles. The fuel atomizing nozzle can break the liquid into micron-sized fine particles, increasing the contact area between fuel and air, allowing fuel particles to collide with more oxygen molecules per unit time, accelerating the combustion reaction rate, and improving combustion completeness.

[0009] Preferably, to facilitate air preheating, the air preheating channel is a spiral channel surrounding the outer wall of the combustion chamber body. The spiral shape of the air preheating channel around the outer wall of the combustion chamber body utilizes the high temperature generated by combustion within the combustion chamber to preheat the air within the channel, causing the air temperature entering the combustion chamber to gradually increase from room temperature. The preheated air carries higher internal energy, which shortens the time required to heat the fuel to its ignition point upon entering the combustion chamber, reduces the activation energy required for combustion, promotes rapid fuel evaporation and chemical reactions, thereby improving the combustion rate and completeness. Simultaneously, it reduces the flame temperature drop caused by cold air injection and inhibits the formation of low-temperature pollutants.

[0010] Preferably, to facilitate thorough mixing of the atomized fuel and air, a spiral air channel is formed between the spiral guide vanes and the inner wall of the combustion chamber body. This spiral air channel forces the air to generate a strong swirling motion, causing the atomized fuel particles to gather towards the center of the combustion chamber under centrifugal force, while the air spirals forward near the wall, forming a gradient mixing region of "fuel enrichment in the center and air envelopment in the periphery," significantly improving the microscopic mixing uniformity of the fuel and air. Furthermore, the swirling air creates a pressure gradient along the axial direction of the combustion chamber, stabilizing the flame position, suppressing backfire or flameout, and improving combustion stability.

[0011] Preferably, to facilitate waste heat recovery: the outer wall of the combustion chamber body is fitted with a double-layer jacket, one end of which has a communicating inlet pipe, and the other end has a communicating outlet pipe. Cold water or air flows through the double-layer jacket to absorb waste heat, improving energy utilization. The double-layer jacket, fitted onto the outer wall of the combustion chamber body, forms an independent waste heat recovery channel, which can utilize the radiant and conductive heat from the outer wall of the combustion chamber to heat the medium (such as water, air, or heat transfer oil) flowing through the jacket. The recovered waste heat can be used to preheat fuel, heat process water, or provide auxiliary heating, reducing energy consumption. In addition, the jacket lowers the temperature of the outer wall of the combustion chamber, improving equipment safety and reducing the risk of burns to operators.

[0012] This application, by setting spiral guide vanes, can guide air to flow in a spiral direction, fully mix with the atomized fuel, improve the mixing effect of fuel and air, promote combustion, make combustion more complete, improve thermal efficiency, and reduce pollutant emissions; by setting an air preheating channel, the heat of the combustion chamber body can be used to preheat the air, increase the air temperature, and further promote fuel combustion.

[0013] This application utilizes a double-layered jacket fitted onto the outer wall of the combustion chamber to form an independent waste heat recovery channel. This allows the radiant and conductive heat from the outer wall of the combustion chamber to heat the medium flowing through the jacket. The recovered waste heat can be used to preheat fuel, heat process water, or provide auxiliary heating, thus reducing energy consumption. Furthermore, the jacket lowers the temperature of the outer wall of the combustion chamber, improving equipment safety and reducing the risk of burns to operators. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a direct-fired combustion structure.

[0015] Figure 2 for Figure 1 The structural sectional view in the image.

[0016] In the picture:

[0017] 1. Combustion chamber body; 11. Fuel inlet; 12. Combustion outlet; 2. Air preheating channel; 3. Spiral guide vanes; 4. Fuel atomizing nozzle; 5. Double jacket; 51. Inlet pipe; 52. Outlet pipe. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0019] Example 1

[0020] This embodiment provides a direct-fired combustion structure, such as... Figure 1-2 As shown, the combustion structure includes a combustion chamber body 1, one end of which is provided with a fuel inlet 11, and the other end of which is provided with a combustion outlet 12;

[0021] An air preheating channel 2 is arranged around the outer wall of the combustion chamber body 1. One end of the air preheating channel 2 is connected to the outside air, and the other end is connected to the interior of the combustion chamber body 1. The air preheating channel 2 uses the residual heat of the combustion chamber body 1 wall to preheat the air entering the combustion chamber, so that the air temperature gradually rises from room temperature, significantly reducing the activation energy required for fuel combustion. When the preheated air mixes with atomized fuel, it can accelerate fuel evaporation (liquid fuel) and chemical reaction rate, thereby improving combustion efficiency. At the same time, it reduces the sudden drop in flame temperature caused by cold air injection, inhibits the generation of CO and unburned carbon particles, and reduces pollutant emissions. Outside cold air enters from the inlet (the end connected to the outside) of the air preheating channel 2 and flows along the spiral channel on the outer wall of the combustion chamber body 1. The high-temperature flue gas in the combustion chamber body 1 transfers heat to the air in the channel through the metal wall (such as stainless steel or heat-resistant alloy) by conduction and radiation. The air continuously absorbs heat during the spiral flow, and its temperature gradually increases. The curvature of the spiral channel forces the air to generate centrifugal force, causing the high-temperature air near the wall to mix with the low-temperature air at the center, thus enhancing turbulent heat transfer. The preheated air enters the combustion chamber from the channel outlet (the end that connects to the interior of the combustion chamber body 1), and mixes thoroughly with the fine fuel particles ejected from the fuel atomizing nozzle 4 under the guidance of the spiral guide vanes 3, forming a high-temperature, highly active combustible mixture, laying the foundation for efficient combustion.

[0022] Inside the combustion chamber body 1, a spiral guide vane 3 is located on one side of the fuel inlet 11, arranged in a spiral pattern around the fuel inlet 11. The spiral guide vane 3, through a specific spiral angle, transforms the axially flowing air into a spiral vortex, improving the mixing efficiency of air and atomized fuel. The centrifugal force generated by the vortex motion causes fuel particles (especially liquid droplets) to gather towards the center of the combustion chamber, forming a gradient mixing region that is "fuel-rich in the center and air-rich in the periphery," significantly increasing the probability of collision between fuel and oxygen molecules per unit volume and improving the combustion reaction rate. When preheated air enters the combustion chamber body 1, it first flows through the spiral guide vane 3. The spiral surface of the vane forces the air to acquire a tangential velocity component, which, combined with the axial velocity, forms a spiral trajectory (the streamline is a spiral line). The atomized fuel particles (liquid fuel is broken into fine droplets by the fuel atomizing nozzle 4, while gaseous fuel is ejected in the form of a high-speed jet) move in a straight line under inertia, but are gradually drawn into the spiral flow field due to the viscous force and turbulent diffusion of the swirling air. Liquid droplets migrate towards the center of the swirling flow due to centrifugal force, forming a strong shear mixture with the surrounding swirling air. This shortens the evaporation time of the liquid fuel (due to the high temperature and strong turbulence of the surrounding air). Meanwhile, the gaseous fuel diffuses rapidly in the swirling flow, forming a homogeneous gas-phase mixture with the air. This "forced swirling mixing" mechanism shortens the mixing time between fuel and air, ensuring thorough mixing within the limited length of the combustion chamber and achieving a highly efficient "mixing and combustion simultaneously" process.

[0023] The combustion chamber body 1 is cylindrical. The cylindrical design of the combustion chamber body 1 provides a uniform flow space for the internal airflow, avoiding airflow turbulence caused by abrupt changes in cross-section. This facilitates the stable development of the spiral airflow guided by the spiral guide vanes 3, ensuring a uniform and continuous mixing flow field between fuel and air within the combustion chamber, thereby improving combustion stability and completeness. Furthermore, the cylindrical outer wall facilitates the surrounding arrangement of the air preheating channel 2 (spiral) or the double-layer jacket 5, maximizing the heat exchange area and improving waste heat utilization efficiency. The inner wall of the cylindrical combustion chamber body 1 provides a symmetrical installation reference for the spiral guide vanes 3. When air passes through the spiral air channel formed by the spiral guide vanes 3 and the inner wall, guided by the spiral angle of the vanes, the air moves spirally along the axis of the combustion chamber body 1, forming a stable swirling flow field. The cylindrical structure ensures uniform radial and axial flow resistance of the swirling air, avoiding local eddies or dead zones, allowing the atomized fuel particles to be fully dispersed and mixed in the swirling air, creating ideal conditions for subsequent combustion reactions.

[0024] To increase the contact area between fuel and air, a fuel atomizing nozzle 4 is installed at the fuel inlet 11 to atomize the fuel into fine particles. The fuel atomizing nozzle 4 breaks the liquid into micron-sized particles, increasing the contact area between fuel and air, allowing fuel particles to collide with more oxygen molecules per unit time, accelerating the combustion reaction rate, and improving combustion completeness. After entering the fuel atomizing nozzle 4 through the fuel inlet 11, the fuel is broken into fine droplets by the swirling chamber or atomizing holes inside the nozzle, utilizing high-speed jet kinetic energy or vibrational energy. These droplets move with the swirling air guided by the spiral guide vanes 3, and under the combined action of centrifugal force, turbulent diffusion, and molecular diffusion, they are fully mixed with the high-temperature preheated air to form a combustible mixture. Because of their large surface area and fast evaporation rate, the atomized fuel particles can quickly form a uniform gas-phase mixture with the air, significantly shortening the combustion preparation stage time and improving combustion efficiency.

[0025] To facilitate air preheating, the air preheating channel 2 is a spiral channel surrounding the outer wall of the combustion chamber body 1. The spiral shape of the air preheating channel 2 around the outer wall of the combustion chamber body 1 utilizes the high temperature generated by combustion within the combustion chamber body 1 to preheat the air within the channel, gradually increasing the temperature of the air entering the combustion chamber from room temperature. The preheated air carries higher internal energy, shortening the time required to heat the fuel to its ignition point upon entering the combustion chamber, reducing the activation energy required for combustion, promoting rapid fuel evaporation and chemical reactions, thereby improving combustion rate and completeness. Simultaneously, it reduces the flame temperature drop caused by cold air injection and inhibits the formation of low-temperature pollutants. Outside air enters through the inlet of the air preheating channel 2 and flows around the combustion chamber body 1 along the spiral channel. The outer wall of the combustion chamber body 1 radiates and conducts heat into the channel. During the spiral flow, the air fully contacts the high-temperature wall surface, absorbing heat and increasing its temperature. The spiral design creates a certain swirling flow within the channel, enhancing boundary layer disturbance, disrupting the thermal resistance layer, and improving heat exchange efficiency. Preheated air enters the combustion chamber from the channel outlet. When it mixes with atomized fuel, its high temperature enables it to initiate a combustion reaction more quickly, forming a highly efficient combustion condition of "preheated air + atomized fuel + swirling mixture".

[0026] To facilitate thorough mixing of atomized fuel and air, a spiral air channel is formed between the spiral guide vanes 3 and the inner wall of the combustion chamber body 1. This spiral air channel forces the air to generate a strong swirling motion, causing the atomized fuel particles to gather towards the center of the combustion chamber under centrifugal force, while the air spirals forward near the wall, forming a gradient mixing region of "fuel enrichment in the center and air envelopment in the periphery," significantly improving the microscopic mixing uniformity of fuel and air. Furthermore, the swirling air creates a pressure gradient along the axial direction of the combustion chamber, stabilizing the flame position, suppressing backfire or flameout, and improving combustion stability. When preheated air enters the combustion chamber body 1, it first flows through the spiral guide vanes 3. The spiral angle (e.g., 45°-60°) and distribution density of the vanes guide the air to generate a tangential velocity component, causing the airflow to simultaneously exhibit a combined axial (towards combustion outlet 12) and radial (rotation around the central axis) motion, forming a spiral trajectory. Atomized fuel particles (especially liquid droplets) undergo centrifugal motion in the swirling air due to their high inertia, converging towards the center of the combustion chamber. Meanwhile, the air spirals along the wall under the propulsion of the blades. During this spiral flow, the two are thoroughly mixed through turbulent diffusion and molecular diffusion. This "forced swirling mixing" mechanism shortens the mixing time between fuel and air, improves the mixing uniformity, and thus achieves a highly efficient "mixing and combustion simultaneously" reaction process.

[0027] Example 2

[0028] Unlike Embodiment 1, to facilitate waste heat recovery, a double-layer jacket 5 is fitted onto the outer wall of the combustion chamber body 1. One end of the double-layer jacket 5 has a connected inlet pipe 51, and the other end has a connected outlet pipe 52. Cold water or air flows through the double-layer jacket 5 to absorb waste heat, improving energy utilization. The double-layer jacket 5, fitted onto the outer wall of the combustion chamber body 1, forms an independent waste heat recovery channel, which can utilize the radiant and conductive heat from the outer wall of the combustion chamber to heat the medium (such as water, air, or heat transfer oil) flowing through the jacket. The recovered waste heat can be used to preheat fuel, heat process water, or provide auxiliary heating, reducing energy consumption. In addition, the jacket lowers the temperature of the outer wall of the combustion chamber, improving equipment safety and reducing the risk of burns to operators. Cold water (or air) enters the annular space of the double-layer jacket 5 from the inlet pipe 51, flows along the outer wall of the combustion chamber body 1, and absorbs the heat transferred from the outer wall (the high-temperature flue gas inside the combustion chamber is conducted to the outside through the wall). After being heated within the jacket, the medium is discharged from the outlet pipe 52 and can be connected to subsequent heat utilization systems (such as water heaters and preheaters). The double-layer structure of the jacket forms a closed heat exchange channel, increasing the contact area between the medium and the wall surface. Combined with the cylindrical outer wall of the combustion chamber body 1, this ensures uniform medium flow and avoids localized overheating.

[0029] The control method of this application is through a controller. The control circuit of the controller can be implemented by a person skilled in the art through simple programming. The power supply is also common knowledge in the art. Since this application is mainly used to protect mechanical devices, the control method and circuit connection will not be explained in detail here.

[0030] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and concept of this application, should be included within the scope of protection of this application.

Claims

1. A direct-fired combustion structure, comprising a combustion chamber body (1), wherein one end of the combustion chamber body (1) is provided with a fuel inlet (11) and the other end of the combustion chamber body (1) is provided with a combustion outlet (12); characterized in that An air preheating channel (2) is arranged around the outer wall of the combustion chamber body (1). One end of the air preheating channel (2) is connected to the outside air, and the other end is connected to the inside of the combustion chamber body (1). The combustion chamber body (1) is provided with a spiral guide vane (3) on one side of the fuel inlet (11), and the spiral guide vane (3) is spirally distributed around the fuel inlet (11).

2. The direct-fired combustion structure according to claim 1, characterized in that: The combustion chamber body (1) is cylindrical.

3. The direct-fired combustion structure according to claim 1, characterized in that: A fuel atomizing nozzle (4) for atomizing fuel into fine particles is provided at the fuel inlet (11).

4. The direct-fired combustion structure according to claim 1, characterized in that: The air preheating channel (2) is a spiral channel that surrounds the outer wall of the combustion chamber body (1).

5. The direct-fired combustion structure according to claim 1, characterized in that: The spiral guide vane (3) forms a spiral air passage between itself and the inner wall of the combustion chamber body (1).

6. The direct-fired combustion structure according to claim 1, characterized in that: To facilitate the recovery of waste heat: the outer wall of the combustion chamber body (1) is fitted with a double-layer jacket (5), one end of the double-layer jacket (5) is provided with a connecting inlet pipe (51), and the other end of the double-layer jacket (5) is provided with a connecting outlet pipe (52).

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