Ducted hot air heating furnace

Abstract

The utility model provides a ducted hot air heating furnace. The device comprises a shell, a cylinder, a plurality of turbofan guide vanes and a combustor, an outer duct is formed between the inner side wall of the shell and the outer side wall of the cylinder, a small-flow channel and a large-flow channel which are isolated from each other and are concentrically arranged are arranged in the combustor, an initial fuel inlet and a main fuel inlet are formed in the tail end of the combustor, and a plurality of small-flow diffusion type combustion spray holes are formed in the central area of the head end of the combustor. A plurality of large-flow premixing type combustion spray holes are formed in the outer edge area of the head end of the combustor. The duct type hot air heating furnace solves the problems that an existing combustion furnace is single in heat adjustment, unstable in hot air amount and simple in structure, heat loss is caused due to the fact that a combustion chamber makes direct contact with a shell, a large number of expensive materials are used, and the hot air furnace usually operates under the condition that the air amount is very excessive. The environment-friendly requirement of low generation of nitric oxide in the combustion process cannot be met, and the load adjusting means is single.

Description

Technical Field

[0001] The utility model relates to the technical field of heating furnaces, in particular to a ducted hot air heating furnace. Background Art

[0002] Hydrocarbon gas fuels, represented by natural gas, have significant advantages as heating heat sources, such as safety, ease of use, and low emission of pollutants. Hot air furnaces using hydrocarbons as fuel are thermal power machinery, which have become replacement products for electric heat sources and traditional steam power heat sources in many industries. There are many varieties of hot air furnaces, which are divided into coal, oil, gas furnaces, etc. according to the type of fuel. However, hot air furnaces using hydrocarbons as fuel have many advantages such as simple structure, few rotating parts, long life, and clean emissions, and have become the mainstream choice. Through long-term production practice, people have realized that only by using hot air as a medium and carrier can the thermal utilization rate and thermal work effect be greatly improved. Compared with the traditional electric heat source and steam thermal power, which indirectly form hot air for drying or heating operations, there are many disadvantages such as a large amount of energy waste, too many auxiliary equipment, and complex process. Hot air furnaces that directly burn heated air to generate heat medium have significant advantages of high efficiency, energy saving, and environmental protection. Especially for the drying or baking operation that requires higher temperature and larger load, the hot air furnace with direct combustion is almost the only choice. It uses direct combustion and then mixes with air for secondary mixing to form hot air, which then directly contacts with the material for heating, drying or baking. This method reduces fuel consumption by about 60% compared with steam or other indirect heaters, and has high energy efficiency. Therefore, direct hot air can be used without affecting the quality of the dried product. The high-temperature combustion gas obtained after the combustion reaction of the fuel further contacts with the secondary air, and after mixing to a certain temperature, it directly enters the drying chamber or baking room, contacts with the dried material, heats, evaporates water, and obtains a dry product.

[0003] In order to utilize the combustion reaction heat of these fuels, a fuel combustion device must be reasonably set up, that is, a burner. There are many types and structural forms of burners, which are generally composed of a combustion spray gun and an air distribution mechanism, as well as an attached fuel control system. The characteristics of the existing technology are that the fuel gas is simply sprayed out through a porous nozzle and ignited (diffusion type), or the fuel is pre-mixed with a portion of air, and the mixed gas is also sprayed out through a porous nozzle and ignited (premixed type). After the fuel is burned, the temperature of the hot blast furnace gradually increases as a whole, and hot air is sent out at the same time. Its characteristics are that the temperature of the hot blast furnace rises and falls as a whole, the higher the temperature, the greater the heat loss, and the air / fuel ratio changes greatly, which cannot be effectively controlled in the best way.

[0004] Therefore, the prior art has the following disadvantages:

[0005] 1. Common equipment using hydrocarbons as fuel - combustion furnaces (burners) have a simple and crude structure, and a single heat regulation method (gas and air regulation). The amount of hot air changes with temperature. It has poor adaptability to occasions that require a stable amount of hot air (the entire process of temperature change from low to high);

[0006] 2. The existing combustion furnace has a simple structure. The combustion chamber with the highest temperature relies on limited insulation of refractory insulation materials and directly contacts the outer shell, which inevitably causes heat loss and uses a large amount of expensive refractory materials;

[0007] 3. Hot air furnaces usually operate under conditions of very excess air. According to the basic theory of combustion, an excessively high excess air coefficient is an important factor in the generation of excessively high nitrogen oxides. Under the above working conditions, existing combustion furnaces cannot achieve the environmental protection requirements of low nitrogen oxide production during the combustion process;

[0008] 4. The existing general combustion furnace burners have a single load regulation method, which relies on the free increase or decrease of fuel gas volume to achieve load regulation. Under the conditions of large air volume, low temperature and low fuel load, the flame is unstable, which can easily cause the danger of "fireout" (explosion); under high load, due to the large amount of fuel added and the low flame propagation speed of hydrocarbon gas fuels, the flame is very long and unstable, which can easily cause incomplete combustion such as "afterburning", which also poses risks to equipment and emission environmental protection. Utility Model Content

[0009] In order to solve the above problems, the utility model provides a ducted hot air heating furnace to solve the above problems existing in the existing hot air furnaces.

[0010] According to a first aspect of the utility model, a ducted hot air heating furnace is provided, comprising: a shell, a cylinder, a plurality of turbofan guide vanes and a burner;

[0011] A cylinder is provided inside the rear end of the shell, and the shell and the cylinder are coaxially arranged, an outer duct is formed between the inner side wall of the shell and the outer side wall of the cylinder, and an inner duct is formed inside the cylinder, a plurality of turbofan guide vanes are located in the outer duct, and the plurality of turbofan guide vanes are evenly distributed along the circumferential direction of the cylinder;

[0012] The head end of the burner is arranged in the inner channel inside the cylinder, and the burner is coaxially arranged with the cylinder, the tail end of the burner extends through the tail end of the shell to the outside of the shell, the interior of the burner has a small flow channel and a large flow channel that are isolated from each other and concentrically arranged, the tail end of the burner is provided with an initial fuel inlet and a main fuel inlet, the initial fuel inlet is connected to the small flow channel, the main fuel inlet is connected to the large flow channel, a plurality of small flow diffusion type combustion nozzles are provided in the central area of ​​the head end of the burner, a plurality of large flow premixed type combustion nozzles are provided in the outer edge area of ​​the head end of the burner, a plurality of small flow diffusion type combustion nozzles are connected to the small flow channel, and a plurality of large flow premixed type combustion nozzles are connected to the large flow channel.

[0013] Optionally, the burner includes a venturi tube, a compound burner head, an inner tube and an outer tube;

[0014] The venturi tube is placed in the inner channel, the compound burner head is arranged at the head end of the venturi tube, the central area of ​​the compound burner head is provided with a plurality of small flow diffusion type combustion nozzles, and the outer edge area of ​​the compound burner head is provided with a plurality of large flow premixing type combustion nozzles;

[0015] The tail end of the venturi tube is an open end, the head end of the inner tube extends into the open end of the venturi tube and extends to the head end of the venturi tube and is sealed and welded with the composite burner head, the interior of the inner tube is connected with a plurality of small flow diffusion type combustion nozzles to form a small flow channel, the tail end of the inner tube passes through the tail end of the shell and extends to the outside of the shell, and the tail end of the inner tube is provided with an initial fuel inlet;

[0016] The outer tube is coaxially sleeved on the inner tube, and the head and tail ends of the inner tube extend outward to the outside of the outer tube respectively. The tail ends of the inner tube and the outer tube are annularly sealed and welded. The head end of the outer tube extends into the open end of the venturi tube and is close to the throat of the venturi tube, and is arranged corresponding to a plurality of large-flow premixed combustion nozzles. The tail end of the outer tube passes through the tail end of the shell and extends to the outside of the shell. A main fuel inlet is provided on the side of the rear end of the outer tube, and a large-flow channel is formed between the inner side wall of the outer tube, the outer side wall of the inner tube and the inner side wall of the venturi tube.

[0017] Optionally, a main fuel pipe is vertically provided on the side of the rear end of the outer tube, and the tail end of the main fuel pipe is a main fuel inlet.

[0018] Optionally, the inner diameter of the outer tube is equal to the inner diameter of the main fuel tube.

[0019] Optionally, the aperture of each small-flow diffusion-type combustion nozzle hole is smaller than the aperture of each large-flow premixing-type combustion nozzle hole.

[0020] Optionally, the burner further comprises a burner positioning ring, and the venturi tube is fixedly arranged in the cylinder through the burner positioning ring so as to place the venturi tube on the axis of the inner channel.

[0021] Optionally, the burner further includes a burner fixing plate, and the outer tube is fixedly arranged at the rear end of the shell through the burner fixing plate.

[0022] Optionally, the tail end area from the turbofan guide vane to the casing is a combustion air inlet distribution chamber.

[0023] Optionally, the open end of the venturi tube is located in the combustion air inlet distribution chamber.

[0024] Compared with the prior art, the beneficial effects of the utility model are:

[0025] 1. In this application, the combustion air and mixed air adopt a novel duct-type diversion structure to control the combustion air distribution amount to achieve stable combustion;

[0026] 2. In this application, the mixed air passes through the outer duct, which does not affect the stability of the flame. At the same time, it isolates the heat transfer from the high temperature of the combustion zone to the outer shell of the hot blast furnace to reduce heat loss, high thermal efficiency, and saves a lot of refractory materials. The manufacturing cost is low;

[0027] 3. In this application, the burner combination of "diffusion + premixing" combustion is used to achieve continuous and stable adjustment of the hot blast furnace load from the initial low temperature state to the high temperature state, without "de-fire, tempering" phenomenon, and good safety;

[0028] 4. The air / fuel ratio of the ducted hot air heating furnace in this application is controllable, the excess air coefficient is reasonable, and less carbon oxides are generated during combustion. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the overall structure of a burner of a ducted hot air heating furnace according to the utility model, which is displaced along the axial direction;

[0030] Figure 2 It is a schematic diagram of the internal structure of a shell of a ducted hot air heating furnace provided by the utility model;

[0031] Figure 3 The utility model is a schematic diagram of the structure of a burner of a ducted hot air heating furnace.

[0032] List of reference numerals:

[0033] 1. Shell; 2. Cylinder; 4. Turbofan guide vane; 5. Burner; 5-1. Venturi tube; 5-2. Compound burner head; 5-3. Inner tube; 5-4. Outer tube; 5-5. Burner positioning ring; 5-6. Burner fixing plate; 6. Outer duct; 7. Inner duct; 8. Initial fuel inlet; 9. Small flow diffusion type combustion nozzle; 10. Large flow premixed type combustion nozzle; 11. Main fuel pipe; 12. Main fuel inlet. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present invention more clear, the implementation methods of the present invention will be further described in detail below with reference to the accompanying drawings.

[0035] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0036] In the description of the present utility model, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0037] Reference Figures 1 to 3 The utility model provides a ducted hot air heating furnace, comprising: a shell 1, a cylinder 2, a plurality of turbofan guide vanes 4 and a burner 5;

[0038] A cylinder 2 is provided inside the rear end of the housing 1, and the housing 1 and the cylinder 2 are coaxially arranged, an outer duct 6 is formed between the inner wall of the housing 1 and the outer wall of the cylinder 2, and an inner duct 7 is formed inside the cylinder 2, a plurality of turbofan guide vanes 4 are located in the outer duct 6, and the plurality of turbofan guide vanes 4 are evenly distributed along the circumferential direction of the cylinder 2;

[0039] The head end of the burner 5 is arranged in the inner channel 7 in the cylinder 2, and the burner 5 is coaxially arranged with the cylinder 2. The tail end of the burner 5 extends through the tail end of the shell 1 to the outside of the shell 1. The interior of the burner 5 has a small flow channel and a large flow channel that are isolated from each other and concentrically arranged. The tail end of the burner 5 is provided with an initial fuel inlet 8 and a main fuel inlet 12. The initial fuel inlet 8 is connected to the small flow channel, and the main fuel inlet 12 is connected to the large flow channel. The central area of ​​the head end of the burner 5 is provided with a plurality of small flow diffusion type combustion nozzles 9, and the outer edge area of ​​the head end of the burner 5 is provided with a plurality of large flow premixed combustion nozzles 10. The plurality of small flow diffusion type combustion nozzles 9 are connected to the small flow channel, and the plurality of large flow premixed combustion nozzles 10 are connected to the large flow channel.

[0040] Among them, the present application adopts an air distribution structure of inner duct 7 + outer duct 6. The inner duct 7 formed inside the cylinder 2 is made of a thin-walled high-temperature resistant alloy material plate. The cylinder 2 is supported and fixed in the axial direction of the shell 1 by a circle of multiple turbofan guide vanes 4 evenly distributed in the outer duct 7. In the present application, the arrangement "angle" and "overlap" of the turbofan guide vanes 4 are the key control technologies for the air flow distribution of the outer duct 6, which determines the residence time of the airflow in the heating furnace and the "thickness" of the "wall flow" airflow. It is also an important means to determine the flame length and burnout rate under high load conditions. The torsion angle and overlap of the turbofan guide vanes 4 need to be coordinated with the combustion characteristics of the fuel and the maximum amount of fuel added for flow field simulation design.

[0041] In addition, the diameter and length of the inner channel 7 are designed and determined according to the combustion characteristics of the fuel and the maximum amount of fuel added. The material for making the inner channel 7 can be high-temperature resistant materials such as 304H, Cr25N i20, and Inconel 800. Although this type of material is relatively expensive, since it does not need to withstand pressure or weight, thinner materials can be used, which saves a lot of usage and has little impact on the cost of the heating furnace.

[0042] In addition, the burner 5 in the present application adopts a "dual-channel fuel supply", that is, a small flow channel and a large flow channel defined in the present application, plus a "diffusion + premixing" structure, which meets the requirements of a large adjustable ratio and can be perfectly applied to the simultaneous use of two fuels with large differences in flame propagation speeds.

[0043] Reference Figure 3 , Optionally, the burner 5 includes a venturi tube 5-1, a compound burner head 5-2, an inner tube 5-3 and an outer tube 5-4;

[0044] The venturi tube 5-1 is placed in the inner channel 7, the compound burner head 5-2 is arranged at the head end of the venturi tube 5-1, a plurality of small flow diffusion type combustion nozzles 9 are arranged in the central area of ​​the compound burner head 5-2, and a plurality of large flow premixing type combustion nozzles 10 are arranged in the outer edge area of ​​the compound burner head 5-2;

[0045] The tail end of the venturi tube 5-1 is an open end, the head end of the inner tube 5-3 extends into the open end of the venturi tube 5-1 and extends to the head end of the venturi tube 5-1 and is sealed and welded with the composite burner head 5-2, the interior of the inner tube 5-3 is connected with a plurality of small flow diffusion type combustion nozzles 9 to form a small flow channel, the tail end of the inner tube 5-3 passes through the tail end of the shell 1 and extends to the outside of the shell 1, and the tail end of the inner tube 5-3 is provided with an initial fuel inlet 8;

[0046] The outer tube 5-4 is coaxially sleeved on the inner tube 5-3, and the head and tail ends of the inner tube 5-3 extend outward to the outside of the outer tube 5-4 respectively. The tail ends of the inner tube 5-3 and the outer tube 5-4 are annularly sealed and welded. The head end of the outer tube 5-4 extends into the open end of the venturi tube 5-1 and is close to the throat of the venturi tube 5-1, and is arranged corresponding to a plurality of large-flow premixed combustion nozzles 10. The tail end of the outer tube 5-4 passes through the tail end of the shell 1 and extends to the outside of the shell 1. A main fuel inlet 12 is provided on the side of the rear end of the outer tube 5-4, and a large-flow channel is formed between the inner side wall of the outer tube 5-4, the outer side wall of the inner tube 5-3 and the inner side wall of the venturi tube 5-1.

[0047] Among them, the initial fuel inlet 8 in the present application is the fuel addition inlet when the heating furnace is started and in the initial stage of heating. It is connected to the inner tube 5-3 and sprays fuel outward through the small-flow diffusion-type combustion nozzle 9 to perform "diffusion combustion"; the main fuel inlet 12 is the main fuel inlet of the heating furnace in the middle and late stages of heating and the stable working stage. The outer tube 5-4 is coaxially installed with the inner tube 5-3 and the outer tube 5-4 extends from the open end of the venturi tube 5-1 and approaches its throat. The airflow is sprayed at this position to form a local negative pressure area, thereby inhaling more air to form a "premix" with the fuel, and then flows forward along the venturi tube 5-1 and gradually increases in pressure to finally reach the large-flow premixed combustion nozzle 10 set in the outer edge area of ​​the compound burner head 5-2. The air and fuel mixture ejected externally is ignited by the flame which is already in a burning state, and "premixed + diffusion" combustion is performed. The above-mentioned combustion process is completed inside the inner duct 7 and at the head end (outlet end) of the inner duct 7. After the high-temperature gas produced by the combustion flows out of the inner duct 7, it is mixed with the air flowing through the outer duct 6 to meet the flue gas temperature and flow rate required by the heating furnace. The air flowing through the outer duct 6 is guided by the turbofan guide vanes 4 and rotates forward along the wall. On the one hand, it cools and insulates the furnace wall. More importantly, it forms terminal "turbulence" to provide sufficient combustion-supporting air for the mixed gas ejected from the large-flow premixed nozzle, thereby ensuring the "burnout rate" of the fuel under high load and reducing the possibility of generating carbon black due to local oxygen deficiency combustion.

[0048] In addition, the fluid dynamics parameters of the venturi tube 5 - 1 are designed and determined according to the combustion characteristics of the fuel and the maximum amount of added fuel.

[0049] Reference Figure 3 Optionally, a main fuel pipe 11 is vertically provided on the side of the rear end of the outer tube 5 - 4 , and the tail end of the main fuel pipe 11 is a main fuel inlet 12 .

[0050] Among them, the above arrangement facilitates the connection of large-diameter fuel gas pipes.

[0051] Optionally, the inner diameter of the outer tube 5 - 4 is equal to the inner diameter of the main fuel tube 11 .

[0052] Optionally, the aperture of each small-flow diffusion-type combustion nozzle hole 9 is smaller than the aperture of each large-flow premixed-type combustion nozzle hole 10 .

[0053] Reference Figure 1 Optionally, the burner 5 further includes a burner positioning ring 5-5, and the venturi tube 5-1 is fixedly arranged in the cylinder 2 through the burner positioning ring 5-5 to place the venturi tube 5-1 on the axis of the inner channel 7.

[0054] The burner positioning ring 5-5 is used to fix and support the venturi tube 5-1.

[0055] Reference Figure 1 Optionally, the burner 5 further includes a burner fixing plate 5-6, and the outer tube 5-4 is fixedly arranged at the rear end of the shell 1 through the burner fixing plate 5-6.

[0056] The burner fixing plate 5-6 is used to fix and support the outer tube 5-4 and form a closed combustion air inlet and distribution chamber.

[0057] Optionally, the tail end area from the turbofan guide vane 4 to the casing 1 is a combustion air inlet distribution chamber.

[0058] Optionally, the open end of the venturi tube 5 - 1 is located in the combustion air inlet distribution chamber.

[0059] In the present application, the initial fuel is delivered from the initial fuel inlet 8. The initial fuel refers to the initial stage when the heating furnace is just ignited and heated. Since the heating furnace is in a relatively low temperature state as a whole and the heating furnace itself also needs to control the heating speed, the amount of fuel allowed to be added is relatively low. Under such working conditions, the flame of the burner of a traditional ordinary hot air heating furnace will be very unstable. The main reason is that the combustion chemical reaction speed is slow due to low temperature. Such an unstable flame is prone to the danger of "de-ignition" under a large air volume. The technical solution adopts the inner channel 7 to restrict the air volume required for the combustion of a small flame, so that the initial low-temperature stage combustion becomes stable, and the flue gas is discharged from the inner channel 7 and fully mixed with the rotating cold air flow of the outer duct 6, so as to meet the process requirements of slow initial flue gas temperature rise, and cleverly solve the requirements of stable combustion and slow initial temperature rise of the combustion furnace;

[0060] In the present application, the main fuel is delivered from the main fuel inlet 12, and the main fuel is premixed and burned by means of injection mixing in the venturi tube 5-1. When the main fuel is started, since the initial fuel burner (located in the central area of ​​the composite burner head, on which are provided a plurality of small-flow diffusion-type combustion nozzles 9) has been working normally, at this time the initial fuel burner becomes the pilot burner of the main fuel burner (located in the outer edge area of ​​the composite burner head, on which are provided a plurality of large-flow premixed combustion nozzles 10). It is very easy to ignite the main fuel burner, and the common combustion furnace avoids the "explosion" phenomenon that is easy to occur when igniting a large-flow burner, and the safety of the heating furnace is greatly enhanced. After the main fuel burner is started, since the amount of fuel added is not very large in the initial stage, the fuel produces a spray effect in the venturi tube 5-1, and the amount of air inhaled can fully meet the air required for the premixed fuel of the main fuel. At this time, the working condition of the main fuel burner is full premixed combustion. With the increase of the amount of fuel added, the throat flow velocity of the venturi tube 5-1 is further increased, and the intake amount of combustion-supporting air is also increased accordingly. The fuel operating condition of the main fuel burner enters a medium-high load state, close to the critical state of the premixed combustion condition to the premixed + diffusion condition. If the fuel amount of the main fuel burner is further increased, it is restricted by the throat cross-sectional area of ​​the venturi tube 5-1, and the amount of premixed air inhaled is limited. The operating condition of the main fuel burner is transferred to the premixed + diffusion condition. The flame shape is slightly elongated, and part of the fuel is diffused and burned at the outer edge of the flame and the air flowing through the outer duct 6. After the heating furnace is in normal working state (fuel is added to the main fuel burner), the heat load of the combustion furnace is mainly adjusted by the fuel addition amount of the main fuel burner. The high-temperature airflow ejected from the inner duct 7 and the heat radiation formed by the inner duct 7 being heated to a high temperature are isolated by the vortex cold airflow of the outer duct 6, which greatly reduces the heating of the combustion furnace shell 1, thereby making the heat loss of the combustion furnace very small.

[0061] Example:

[0062] Take a hot air heating furnace using natural gas as fuel as an example: the initial fuel burner natural gas flow rate is 2~25Nm 3 / h; natural gas flow rate of main fuel burner 15~180Nm 3 / h; load adjustment ratio 1:90; natural gas pressure 0.2MPaG; natural gas temperature 20℃; inner duct diameter 410mm, length 720mm; outer duct diameter 1815mm; outer duct turbofan guide vanes 17, twist angle 37°, overlap 21%; heat load 1800kW; hot air output temperature up to 630℃; hot air volume 28100m 3 / h; thermal efficiency 98.1%; blower shaft power 17.2kW, motor power 22kW, motor uses variable frequency controller to adjust blower speed, and air distribution is coordinated with combustion load;

[0063] The hot air heating furnace is designed for drying the heat-resistant lining of the second-stage reformer of a large chemical plant. The heat-resistant lining of the reformer is cast with special heat-resistant concrete. The total amount of lining concrete is 81m 3 , about 192t, water content 14% (wt%), about 26.9t. After the concrete is poured, it is necessary to thoroughly dry the concrete according to the strict temperature rise curve requirements. The final drying temperature is 600℃, which requires extremely high working conditions of the heating furnace. According to the user's requirements, this ducted hot air heating furnace was designed using this technical solution. After actual use, the effect is good. The entire drying operation plus the cooling operation took 22 days. The hot air furnace operates stably, whether it is low load or high load conditions, the hot air furnace operates well and successfully completes the tasks entrusted by the user.

[0064] It should be noted that not all steps and modules in the above-mentioned processes and system structure diagrams are necessary, and some steps or modules can be ignored according to actual needs. The execution order of each step is not fixed and can be adjusted as needed. The system structure described in the above-mentioned embodiments can be a physical structure or a logical structure, that is, some modules may be implemented by the same physical entity, or some modules may be implemented by multiple physical entities, or some components in multiple independent devices may be implemented together.

[0065] In the above embodiments, the hardware module can be implemented mechanically or electrically. The above text shows and describes the present invention in detail through the accompanying drawings and preferred embodiments, but the present invention is not limited to these disclosed embodiments. Based on the above multiple embodiments, those skilled in the art can know that the code review methods in the above different embodiments can be combined to obtain more embodiments of the present invention, and these embodiments are also within the protection scope of the present invention.

Claims

1. A ducted hot air heating furnace, characterized in that: include: A casing (1), a cylinder (2), a plurality of turbofan guide vanes (4) and a burner (5); The cylinder (2) is provided inside the rear end of the shell (1), and the shell (1) and the cylinder (2) are coaxially arranged, an outer duct (6) is formed between the inner wall of the shell (1) and the outer wall of the cylinder (2), and an inner duct (7) is formed inside the cylinder (2), a plurality of turbofan guide vanes (4) are located in the outer duct (6), and the plurality of turbofan guide vanes (4) are evenly distributed along the circumferential direction of the cylinder (2); The head end of the burner (5) is arranged in the inner channel (7) in the cylinder (2), and the burner (5) is coaxially arranged with the cylinder (2). The tail end of the burner (5) passes through the tail end of the shell (1) and extends to the outside of the shell (1). The interior of the burner (5) has a small flow channel and a large flow channel that are isolated from each other and concentrically arranged. The tail end of the burner (5) is provided with an initial fuel inlet (8) and a main fuel inlet (12). The initial fuel inlet (8) is connected to the small flow channel, and the main fuel inlet (12) is connected to the large flow channel. The central area of ​​the head end of the burner (5) is provided with a plurality of small flow diffusion type combustion nozzles (9). The outer edge area of ​​the head end of the burner (5) is provided with a plurality of large flow premixing type combustion nozzles (10). The plurality of small flow diffusion type combustion nozzles (9) are connected to the small flow channel, and the plurality of large flow premixing type combustion nozzles (10) are connected to the large flow channel.

2. A ducted hot air heating furnace according to claim 1, characterized in that: The burner (5) comprises a venturi tube (5-1), a compound burner head (5-2), an inner tube (5-3) and an outer tube (5-4); The venturi tube (5-1) is placed in the inner channel (7), the compound burner head (5-2) is arranged at the head end of the venturi tube (5-1), a plurality of small flow diffusion type combustion nozzles (9) are arranged in the central area of ​​the compound burner head (5-2), and a plurality of large flow premixing type combustion nozzles (10) are arranged in the outer edge area of ​​the compound burner head (5-2); The tail end of the venturi tube (5-1) is an open end, the head end of the inner tube (5-3) extends into the open end of the venturi tube (5-1) and extends to the head end of the venturi tube (5-1) and is sealed and welded with the composite burner head (5-2), the interior of the inner tube (5-3) is connected with the plurality of small flow diffusion type combustion nozzles (9) to form the small flow channel, the tail end of the inner tube (5-3) passes through the tail end of the shell (1) and extends to the outside of the shell (1), and the tail end of the inner tube (5-3) is provided with the initial fuel inlet (8); The outer tube (5-4) is coaxially sleeved on the inner tube (5-3), and the head and tail ends of the inner tube (5-3) respectively extend outward to the outside of the outer tube (5-4). The tail ends of the inner tube (5-3) and the outer tube (5-4) are annularly sealed and welded. The head end of the outer tube (5-4) extends into the open end of the venturi tube (5-1) and is close to the throat of the venturi tube (5-1), and is arranged corresponding to the multiple large-flow premixed combustion nozzles (10). The tail end of the outer tube (5-4) passes through the tail end of the shell (1) and extends to the outside of the shell (1). The side of the rear end of the outer tube (5-4) is provided with the main fuel inlet (12). The large-flow channel is formed between the inner side wall of the outer tube (5-4), the outer side wall of the inner tube (5-3) and the inner side wall of the venturi tube (5-1).

3. A ducted hot air heating furnace according to claim 2, characterized in that: A main fuel pipe (11) is vertically arranged on the side of the rear end of the outer pipe (5-4), and the tail end of the main fuel pipe (11) is the main fuel inlet (12).

4. A ducted hot air heating furnace according to claim 3, characterized in that: The inner diameter of the outer tube (5-4) is equal to the inner diameter of the main fuel tube (11).

5. A ducted hot air heating furnace according to claim 4, characterized in that: The aperture of each of the small-flow diffusion-type combustion spray holes (9) is smaller than the aperture of each of the large-flow premixing-type combustion spray holes (10).

6. A ducted hot air heating furnace according to claim 5, characterized in that: The burner (5) further comprises a burner positioning ring (5-5), and the Venturi tube (5-1) is fixedly arranged in the cylinder (2) via the burner positioning ring (5-5) so as to place the Venturi tube (5-1) on the axis of the inner channel (7).

7. A ducted hot air heating furnace according to claim 6, characterized in that: The burner (5) further comprises a burner fixing plate (5-6), and the outer tube (5-4) is fixedly arranged at the rear end of the shell (1) via the burner fixing plate (5-6).

8. A ducted hot air heating furnace according to claim 7, characterized in that: The tail end area from the turbofan guide vane (4) to the casing (1) is a combustion air inlet distribution chamber.

9. A ducted hot air heating furnace according to claim 8, characterized in that: The open end of the Venturi tube (5-1) is located in the combustion air inlet and distribution chamber.

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