A high-efficiency low-nitrogen combustion device with gas injection air rotation variable speed premixing

Abstract

This invention relates to a high-efficiency, low-NOx combustion device with a gas-injected air swirl variable-speed premixing system. It effectively solves the problem of sufficient and uniform premixing of gas and air, improving the degree of complete combustion, effectively preventing backfire and combustion vibration, and improving energy-saving and low-NOx emission performance. A combustion-supporting fan and a premixed burner are arranged in a horizontal parallel direction and interconnected in a vertically horizontal direction via a connecting pipe. A high-pressure gas pipeline is divided into multiple branches inserted horizontally into the connecting pipe. The connecting pipe consists of a horizontal air outlet pipe for the combustion-supporting fan and a horizontal tangential inlet pipe for the burner. The nozzles of the multiple branches of the gas pipeline are located near the interface. The burner has a structure with one closed end and one open end, tapering in the middle. The closed end is a swirl premixing chamber connected to a horizontal tangential inlet pipe. A converging nozzle is connected to the swirl premixing chamber, and the outlet end of the converging nozzle has a ceramic grid. An adjusting gas pipe is inserted axially from the center of the closed end of the burner, extending to near the converging nozzle.

Description

Technical Field

[0001] This invention relates to combustion devices, and in particular to a high-efficiency, low-NOx combustion device that employs high-pressure, high-calorific-value gas injection at high speed to entrain combustion air, and uses a strong swirling and variable-speed method to rapidly and violently premix the air and gas, thereby achieving fully uniform premixed combustion of the air and gas. Background Technology

[0002] Combustion devices are essential equipment for various heat utilization systems using fossil fuels as heat sources, such as heating furnaces, boilers, and various kilns. For combustion devices (burners) using gaseous fuels, improving the thorough and uniform premixing of air and fuel gas to achieve efficient and complete combustion (thoroughly uniform premixed combustion), and reducing nitrogen oxide emissions while controlling oxygen concentration, are pressing practical issues. However, traditional combustion methods largely neglect this point. Some burners, even those that appear to be premixed burners, fail to achieve the technical effects of thorough and uniform premixing. This reflects a lack of understanding of how to achieve premixed combustion and an unclear traditional definition. Meanwhile, the uniformity of the outlet airflow distribution, the compact design of the combustion device, and the improvement of the combustion device's thermal power (heat load) are also directions worthy of continued exploration and research. Furthermore, structural problems in many burners severely affect the performance and effectiveness of thermal equipment. To address this, a high-efficiency, low-NOx combustion device with gas-injected air swirl and variable-speed premixing is proposed. This device employs high-pressure gas injection for rapid premixing of combustion air, followed by a strong swirl high (variable) speed structure to achieve fully uniform premixing, resulting in a fully premixed combustion device. By achieving thorough and uniform premixing of gas and air, the complete combustion degree of gas is improved, and the generation of nitrogen oxides is effectively controlled. At the same time, backfire and combustion vibration are effectively prevented, and the structure of the combustion device is made more compact. Its high efficiency, energy saving, and low NOx emission performance are very significant. It is a unique combustion device with stable structure and optimized performance, suitable for various heat utilization equipment, and has not been publicly reported to date. Summary of the Invention

[0003] In view of the above situation and to overcome the defects of the prior art, the purpose of this invention is to provide a high-efficiency, low-NOx combustion device with gas ejector air swirl variable speed premixing, which can effectively solve the problem of sufficient and uniform premixing of gas and air, improve the degree of complete combustion of gas, control the generation of nitrogen oxides, effectively prevent backfire and combustion vibration, promote the compact structure of the combustion device, and improve the performance of energy saving and low NOx emissions.

[0004] The technical solution provided by this invention is a high-efficiency, low-NOx combustion device with gas ejector air swirl variable speed premixing. A combustion-supporting fan and a trumpet-shaped premixed burner are arranged in a horizontal parallel direction and interconnected in a vertical and horizontal direction via a connecting pipe. A high-pressure gas pipeline is divided into multiple branch pipes inserted horizontally into the connecting pipe. The connecting pipe is composed of a horizontal air outlet pipe of the combustion-supporting fan and a horizontal tangential inlet pipe of the burner. The nozzles of the multiple branch pipes of the gas pipeline are located near their interfaces. The burner has a structure with one closed end and one open end, tapering in the middle. The closed end is a swirl premixing chamber, connected to which by a horizontal tangential inlet pipe. A converging nozzle is then connected to the swirl premixing chamber. A ceramic grid (flame stabilization device) for flame stabilization is provided at the outlet end of the converging nozzle. An adjusting gas pipe is inserted axially from the center of the closed end of the burner, extending to near the minimum cross-section of the converging nozzle.

[0005] This invention relates to a device for fully and uniformly premixed, controllable combustion and adjustable heat storage flow field. It integrates various fluid flow, gas combustion, heat transfer, and heat storage technologies, resulting in a novel hot blast stove structure that combines comprehensive and unique innovations with optimization. The swirl premixing structure of the air gas in its burner, arranged in layers and staggered, effectively achieves full and uniform premixing of the air gas (enhancing the degree of premixing). Its high-pressure airflow strong swirl combustion regulating device has the function of actively and forcibly regulating combustion during the combustion process, fully realizing active and effective control of combustion intensity, combustion mode, and combustion temperature during hot blast stove operation. Furthermore, after combustion is stopped... The high-pressure airflow purging effectively prevents and avoids residual gas deflagration during the air supply process, as well as the regulation and control of the air supply temperature. The setting of the heat storage body airflow regulating layer effectively regulates the uniformity of the heat storage body airflow distribution. In particular, it can effectively overcome the spontaneous deflection of airflow caused by the high airflow temperature and high flow resistance during the air supply cycle. Due to the heat storage body checker bricks stacked in the swirl combustion chamber, the hot blast stove structure is more compact. It effectively improves the combustion intensity and the stability of the high-temperature structure of the hot blast stove, and can also reduce the initial investment cost of the hot blast stove. It is a major innovation in combustion devices with significant economic and social benefits. Attached Figure Description

[0006] Figure 1 This is a front cross-sectional view of the structure of the present invention.

[0007] Figure 2 This is a top cross-sectional view of the structure of the present invention.

[0008] In the diagram: Gas inlet main pipe 1-0, gas branch pipe 1-1, gas branch pipe outlet 1-2, centrifugal combustion fan 2-0, combustion fan impeller 2-1, combustion fan inlet pipe 2-2, combustion fan outlet pipe 2-3, combustion fan drive motor 2-4, burner 3-0, burner premixed airflow inlet pipe 3-1, strong swirling premixed annular groove 3-2, strong swirling premixed chamber 3-3, premixed gas scaling channel 3-4, swirling premixed gas spray outlet 3-5, burner outlet 3-6, ceramic grille 3-7, regulating airflow inlet pipe 4-0, regulating gas control valve 4-1, regulating gas injection port 4-2. Implementation

[0009] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and specific circumstances.

[0010] Depend on Figure 1 , 2 As shown, this invention discloses a high-efficiency, low-NOx combustion device with gas-injected air swirl variable speed premixing, comprising a combustion-supporting fan, a burner, and a drive motor. A parallel centrifugal combustion-supporting fan 2-0 and a swirl variable speed injection burner 3-0 are interconnected via a burner premixed airflow inlet pipe 3-1. The gas inlet main pipe 1-0 is inserted into the inner end of the combustion-supporting fan outlet pipe 2-3, dividing into multiple parallel gas branch pipes 1-1. The outlet 1-2 of each gas branch pipe 1-1 is connected to the inlet of the burner premixed airflow inlet pipe 3-1. An adjustable airflow inlet pipe 4-0 is inserted along the center of the burner 3-0, and the gas injection port 4-2 is adjusted to face the burner outlet 3-6. A combustion-supporting fan impeller 2-1 is installed inside the volute-shaped casing of the centrifugal combustion-supporting fan 2-0. An combustion-supporting fan inlet pipe 2-2 and a circumferentially tangentially connected combustion-supporting fan outlet pipe 2-3 are installed along the axial direction of the combustion-supporting fan impeller 2-1. The other end of the combustion-supporting blower 2-0 is connected to the motor shaft of the combustion-supporting blower drive motor 2-4, which provides power. The shell of the burner 3-0 is a funnel-shaped shell closed at one end. Near the closed end, there is a burner premixed airflow inlet pipe 3-1 that connects to the combustion-supporting blower outlet pipe 2-3 and is tangentially connected to the strong swirling premixing annular groove 3-2 arranged circumferentially in the strong swirling premixing chamber 3-3. The scaling premixed airflow scaling channel 3-4 in the middle section of the burner is connected to the burner outlet 3-6. The burner outlet 3-6 is equipped with a ceramic grid 3-7. The narrowest part of the scaling section of the burner shell is the swirling premixed gas injection outlet 3-5. The regulating airflow inlet pipe 4-0 is equipped with a regulating gas control valve 4-1. The upper end of the regulating airflow inlet pipe 4-0 is inserted from the closed end of the burner along its axis, passes through the strong swirling premixing chamber 3-3 and the end contracts to form the regulating gas injection port 4-2, which enters and connects to the premixed gas scaling channel 3-4.

[0011] To ensure effectiveness and ease of use, the shell of the burner 3-0 is a hollow body with a circular cross-section, made of heat-resistant steel or stainless steel suitable for high-temperature environments.

[0012] The cross-section of the strong swirling premixing annular groove 3-2 is arc-shaped, so as to generate secondary vortex flow during high-speed swirling, thereby enhancing the further thorough and uniform mixing between air and fuel gas.

[0013] The ceramic grille 3-7 is a mesh structure made of high-temperature resistant ceramic material. The thickness plane forms small channels with small airflow interfaces and long lengths to prevent high-temperature heat radiation from entering the burner.

[0014] The regulating airflow inlet pipe 4-0 is inserted into the burner and gradually narrows to become the regulating gas injection port 4-2, and is connected to it near the center of the swirling premixed gas injection port 3-5 at the narrowest point of the premixed gas scaling channel 3-4, which facilitates precise adjustment and control of the airflow.

[0015] The outlet end of the adjustable gas injection port 4-2 can gradually change into an elliptical or rectangular outlet according to the furnace structure.

[0016] In use, the combustion air is driven by motor 2-4, which in turn drives the combustion air fan. The combustion air meets the gas injected from the high-pressure gas pipe branch at the fan outlet. The gas is carried by the high-pressure injection and passes through the burner's outlet and horizontal tangential inlet pipe into the burner's swirl premixing chamber. Under the action of the circumferential premixing annular groove, the air and gas are fully and uniformly premixed. The instantaneous premixing degree depends on the relative magnitude of the tangential and axial velocities (i.e., the swirl intensity); the higher the value, the better the effect. After the gas and air are fully and uniformly premixed, they enter the expanding and contracting premixed gas outlet pipe. Here, both the tangential and axial velocities of the premixed gas undergo an initial acceleration followed by deceleration to further achieve more thorough and uniform premixing. Afterward, the gas flows through ceramic grid 3-7 (flame stabilization device), where the axial velocity increases, filtering out large particles. The swirling flow achieves uniform and fully turbulent premixed airflow into the furnace to complete the preheating, ignition, and combustion processes. Due to the extremely fast chemical reaction rate, a visually flameless combustion state is formed. The regulating airflow uses high-pressure gas flow, which plays an active control role, prevents backflow in the center of the diffuser section, and weakens the premixing degree of the already formed airflow. Thus, it achieves an active regulation function for the combustion process. It integrates injection, strong swirl, speed change, flame stabilization, and regulation. It effectively utilizes high-pressure airflow injection mixing to complete the initial premixing on the basis of energy saving. Then, a vortex ring swirling flow is used to achieve full premixing. Then, it enters the scaling nozzle to achieve swirling speed change mixing to achieve almost 100% chemical equivalent level complete premixing. The swirling diffusion without separation achieves uniform distribution. Then, it passes through a ceramic mesh flame stabilizer to filter out large vortices and increase the flow velocity to form homogenized anti-backfire premixed combustion.

[0017] Compared with the prior art, the present invention has significant technical advantages, which can be summarized as follows:

[0018] 1. The combination of high-pressure gas ejector entrainment and air premixing with strong vortex flow effectively achieves full and uniform premixing between air and gas, providing favorable conditions for premixed combustion.

[0019] 2. By utilizing the contraction section of the converging nozzle, the premixing degree of the strong swirling premixed airflow is further enhanced as the circumferential and axial velocities are increased, achieving almost 100% premixed airflow. Then, the diffusion section is used to complete the swirling and separation-free homogenization of the premixed airflow. Due to the high flow velocity in the contraction section, the combustion process in the diffusion section can also effectively block the spread of combustion process to the swirling premixing chamber (deep tempering).

[0020] 3. The channel ceramic mesh flame stabilizer increases the flow rate to prevent backfire and prevents the high temperature radiation of the burner airflow from affecting the nozzle. At the same time, the high temperature of the ceramic mesh flame stabilizer on the fire surface ignites the premixed airflow to achieve stable premixed combustion. Furthermore, the minimal airflow separation of the premixed airflow also effectively prevents combustion oscillation.

[0021] 4. To achieve high-speed and variable-speed premixed combustion, a compact combustion device structure is essential, which also enables the effective heat load of the unit to be realized, thus achieving the technical effect of cost reduction and efficiency improvement.

[0022] 5. Because the combustion device can achieve fully premixed and adjustable combustion of air and fuel gas, nitrogen oxides can be effectively controlled, fully meeting the environmental protection requirements of ultra-low emissions, and effectively saving flue gas treatment costs and equipment.

[0023] It should be noted that the above-described embodiments of the hot air furnace are merely examples of specific implementations of the present invention and are not intended to limit the scope of protection of the present invention. Any technical solutions that are essentially the same as the present invention and are made by equivalent or equivalent means shall fall within the scope of protection of the present invention.

Claims

1. A gas injection air swirling variable speed premixed high efficiency low nitrogen combustion device, comprising a centrifugal combustion-supporting fan (2-0), a swirling variable speed injection burner (3-0) and a combustion-supporting fan driving motor (2-4), characterized in that, A centrifugal combustion fan (2-0) and a swirl variable speed jet burner (3-0) are set in a parallel horizontal direction and connected to each other in a vertical and horizontal direction through a connecting pipe. The high-pressure gas pipeline is divided into multiple gas branch pipes (1-1) which are inserted into the connecting pipe in a horizontal direction. The connecting pipe is composed of a horizontal combustion fan outlet pipe (2-3) and a horizontal burner premixed airflow inlet pipe (3-1). The nozzles of the multiple gas branch pipes (1-1) of the gas pipeline are located near the interface of the connecting pipe. The burner has a structure with one end closed and the other end open, and the middle section is tapered. The closed end is a strong swirl premixing chamber (3-3), which is connected to the burner premixed airflow inlet pipe (3-1). Then, the premixed airflow tapering channel (3-4) is connected to the strong swirl premixing chamber (3-3). The regulating airflow inlet pipe (4-0) is inserted axially from the center of the closed end of the burner and extends to the minimum cross-section of the premixed airflow tapering channel (3-4). A parallel centrifugal combustion fan (2-0) is connected to a swirl variable speed jet burner (3-0) via a premixed airflow inlet pipe (3-1). The main gas inlet pipe (1-0) is inserted into the end portion of the combustion fan outlet pipe (2-3), dividing into multiple parallel gas branch pipes (1-1). The outlet (1-2) of each gas branch pipe (1-1) is connected to the inlet of the premixed airflow inlet pipe (3-1). The regulating airflow inlet pipe (4-0) is inserted along the center of the burner (3-0) and the gas jet is regulated. The injection port (4-2) faces the burner outlet (3-6). A combustion fan impeller (2-1) is installed inside the casing of a volute-shaped centrifugal combustion fan (2-0). An combustion fan inlet pipe (2-2) is installed axially along the impeller (2-1), and a combustion fan outlet pipe (2-3) is tangentially connected to the periphery. The other axial end of the centrifugal combustion fan (2-0) is connected to the motor shaft of the combustion fan drive motor (2-4). The burner (3-0) casing is a funnel-shaped empty shell closed at one end, with a... The burner premixed airflow inlet pipe (3-1), which connects to the combustion fan outlet pipe (2-3), is tangentially connected to and connected to the circumferentially arranged strong swirling premixing annular groove (3-2) of the strong swirling premixing chamber (3-3). The scaling premixed airflow channel (3-4) in the middle section of the burner connects to the burner outlet (3-6). The burner outlet (3-6) is equipped with a ceramic grid (3-7). The ceramic grid (3-7) is a mesh structure made of high-temperature resistant ceramic material. The thickness plane forms small channels with small airflow interfaces and long lengths to prevent high temperature. Thermal radiation enters the burner, and the narrowest part of the burner shell is the swirl premixed gas injection outlet (3-5). The regulating gas inlet pipe (4-0) is equipped with a regulating gas control valve (4-1). The upper end of the regulating gas inlet pipe (4-0) is inserted from the closed end of the burner along its axis, passes through the strong swirl premixing chamber (3-3), and the end contracts to form the regulating gas injection port (4-2). It is connected to the center of the swirl premixed gas injection outlet (3-5) at the narrowest part of the premixed gas flow channel (3-4), which facilitates precise regulation and control of the airflow.

2. The gas entrained air swirled variable speed premixing high efficiency low NOx combustion apparatus as claimed in claim 1, wherein, The burner (3-0) shell is a hollow body with a circular cross-section made of heat-resistant steel or stainless steel, which is adapted to high-temperature environments.

3. The high-efficiency, low-NOx combustion device with gas ejection and air swirl variable speed premixing according to claim 1, characterized in that, The cross-section of the strong swirling premixing annular groove (3-2) is arc-shaped so as to generate secondary vortex flow during high-speed swirling, thereby enhancing the further thorough and uniform mixing between air and gas.

4. The high-efficiency, low-NOx combustion device with gas ejection and air swirl variable speed premixing according to claim 1, characterized in that, The outlet end of the regulating gas injection port (4-2) gradually changes to an ellipse or rectangle according to the furnace structure.

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