A high-efficiency and energy-saving single-bell furnace for annealing silicon steel

Abstract

This invention provides a high-efficiency and energy-saving silicon steel annealing single-unit bell-type furnace, comprising a mixing chamber, a furnace body, and a waste heat recovery device arranged sequentially. The mixing chamber has a Venturi tube structure and is equipped with an ultrasonic transducer. The furnace body includes a base, an inner cover, and an outer cover. Several spirally ascending inner and outer gas channels are provided on the outer wall of the inner cover and the inner wall of the outer cover. Several air inlets and nozzles are also provided at the bottom of the outer cover. In this invention, the spiral ascent of the gas increases its residence time in the space between the inner and outer covers, improving energy utilization and making the inner cover more evenly heated. The mixing chamber at the front of the furnace body further vibrates the mixed gas and air using ultrasonic waves, allowing gas molecules to exchange positions at the molecular level, resulting in more uniform mixing at the microscopic level, thus promoting combustion, ensuring more complete combustion, and improving the utilization rate of the gas.

Description

Technical Field

[0001] This utility model relates to the technical field of silicon steel annealing equipment, and in particular to a high-efficiency and energy-saving single-unit bell furnace for silicon steel annealing. Background Technology

[0002] Silicon steel is a silicon alloy steel containing 1.0–4.5% silicon and less than 0.08% carbon. It possesses characteristics such as high magnetic permeability, low coercivity, and high resistivity, resulting in low hysteresis and eddy current losses. It is mainly used as a magnetic material in motors, transformers, electrical appliances, and electrical instruments. To meet the requirements of punching and shearing processes during electrical manufacturing, a certain degree of plasticity is also required. To improve magnetic performance and reduce hysteresis losses, the content of harmful impurities should be as low as possible, and the sheet should be flat with good surface quality.

[0003] Annealing is one of the core technologies in silicon steel production, and proper control of annealing temperature and time greatly improves the quality of silicon steel. Current silicon steel annealing processes typically utilize bell-type furnaces, which consist of a furnace platform for holding the silicon steel coils and a bell covering the platform. The annealing temperature is controlled by heating the inside of the bell. Current bell-type furnaces generally employ a closed inner and outer bell structure. The silicon steel coils are placed in the inner bell using support plates, and a high-temperature combustion mixture of gas and oxygen is introduced between the inner and outer bells. The high temperature of the combustion heats the air inside the inner bell, achieving the set annealing temperature.

[0004] However, current bell-type furnaces still have certain problems. The gas is typically introduced from a single point between the inner and outer bells, then needs to circulate within a relatively flat, curved space before exiting from the top. During this process, the gas is difficult to distribute evenly between the inner and outer bells, resulting in uneven heating of the outer wall of the inner bell, and consequently, uneven heating of the silicon steel within the inner bell, which undoubtedly affects the annealing effect. Simultaneously, the gas, due to its high temperature, rises rapidly and exits quickly, resulting in a short heating time for the inner bell and low temperature utilization. Furthermore, current methods generally use mixers to mix the gas and air before ignition and introduction between the inner and outer bells. However, ordinary mixers often fail to mix the gas molecules in the gas and air sufficiently evenly, leading to inconsistent combustion and further affecting temperature uniformity. Utility Model Content

[0005] To address the shortcomings of existing technologies, this utility model provides a high-efficiency and energy-saving silicon steel annealing single-unit bell furnace, which solves the problem that uneven distribution of gas between the inner and outer bells and uneven mixing of gas and air in existing technologies lead to inconsistent heating temperatures of the inner bell, thus affecting the annealing effect.

[0006] According to an embodiment of the present invention, a high-efficiency and energy-saving silicon steel annealing single-unit bell furnace includes a mixing chamber, a furnace body and a waste heat recovery device arranged in sequence. The mixing chamber has a Venturi tube structure and an ultrasonic transducer is also provided on the mixing chamber.

[0007] The furnace body includes a base, an inner cover mounted on the base, and an outer cover coaxially sleeved outside the inner cover. The inner cover has several spirally ascending inner air channels on its vertical outer surface. The inner air channels are concave channel structures. The outer cover has several spirally ascending outer air channels on its vertical inner surface. The outer air channels are concave channel structures, so that the inner and outer air channels are arranged opposite to each other.

[0008] The bottom of the outer cover is also provided with several air inlets, each air inlet having a nozzle facing inwards. The nozzle is connected to the outlet of the mixing chamber through an air inlet pipe. The top of the outer cover is also provided with an exhaust port, which is connected to the waste heat recovery device through an exhaust pipe.

[0009] Furthermore, the mixing chamber includes a cylindrical tube wall and a tube body with a Venturi tube structure disposed inside the tube wall. One end of the tube body is an air inlet and the other end is a mixed gas outlet. The middle of the tube body narrows to form a throat section. The throat section is also connected to a gas pipe. The ultrasonic transducer is disposed on the outer wall of the tube body and corresponds to the outlet of the throat section.

[0010] Furthermore, both the inner and outer air passages are semi-circular tube structures, with their opposite sides radially cut along the vertical direction to form semi-circular arc-shaped channels with relative openings.

[0011] Furthermore, the inner walls of the inner and outer air passages are provided with a number of equally spaced turbulence blocks, the radial length of which is much smaller than the diameter of the inner and outer air passages.

[0012] Furthermore, the nozzle is movably connected to the air inlet, allowing the nozzle to rotate in the horizontal plane. The nozzle is installed at the bottom end of the outer air passage, so that when the nozzle is in a radial state, it corresponds exactly to the bottom end of the inner air passage.

[0013] Furthermore, the waste heat recovery device includes a preheating module and a recovery module connected in sequence. The preheating module is set in the air inlet pipe between the mixing chamber and the nozzle to preheat the mixed gas. The recovery module collects and recovers the remaining heat.

[0014] Furthermore, the preheating module is a ceramic heat storage structure, including a shell and several heat storage blocks disposed inside the shell. The air inlet pipe branches into multiple parallel branch pipes inside the shell. After passing through the heat storage blocks, the branch pipes converge into a single air inlet pipe and connect to the nozzle.

[0015] Furthermore, the recycling module is an organic Rankine cycle power generation device.

[0016] Furthermore, a heat-reflective coating is also provided on the inner wall of the outer cover.

[0017] Furthermore, the base includes a support plate and a placement platform from bottom to top, and a heat insulation layer is provided between the bottom of the placement platform and the support plate.

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

[0019] 1. In this utility model, the inner cover has several spirally ascending inner gas channels on its vertical outer surface, and the outer cover has several spirally ascending outer gas channels on its vertical inner surface. This creates a spiral channel between the inner and outer covers for the gas to ascend. The high-temperature combustion gas entering between the inner and outer covers through the nozzle moves along the spiral channel under the force of the jet, thus spiraling upwards around the inner cover. This allows the gas to contact the inner cover more evenly, resulting in more uniform heating and temperature distribution within the inner cover, thereby improving the annealing effect. Simultaneously, the spiral ascent increases the gas's residence time in the space between the inner and outer covers, allowing for better heat transfer to the inner cover and improving energy utilization. Therefore, this bell-type furnace possesses the technical advantages of high efficiency, energy saving, and environmental protection.

[0020] 2. This utility model also provides a mixing chamber at the front of the furnace body. The mixing chamber has a Venturi tube structure and is equipped with an ultrasonic transducer. This allows the mixed gas and air to be further oscillated by ultrasound, enabling gas molecules to exchange positions from a molecular perspective. This makes the gas more uniformly mixed at the microscopic level, thereby promoting the combustion effect, making the gas burn more completely, and improving the utilization rate of the gas.

[0021] 3. The nozzle and air inlet in this utility model are movably connected, allowing the nozzle to rotate in the horizontal plane. This allows adjustment of the nozzle's exhaust direction relative to the inner cover surface. Considering that the gas does not completely follow the positions of the inner and outer air passages during its spiral ascent, but rather floats according to its own temperature, the gas cannot completely cover the outer surface of the inner cover during its spiral ascent, resulting in a heating blind zone. By adjusting the exhaust direction of the nozzle, the starting point of the gas's spiral ascent path and the pitch / diameter ratio can be adjusted, allowing the gas to move along different spiral paths, achieving a larger coverage area of ​​the inner cover surface and further improving heating uniformity.

[0022] Furthermore, when the gas discharge direction is tangential to the inner cover surface, it can move spirally along the inner and outer air passages to the maximum extent; while when the gas discharge direction is perpendicular to the inner cover surface, it is almost difficult to form a spiral airflow, and instead rises directly upwards. In this way, the flow pattern and residence time of the gas between the inner and outer covers can be adjusted, thereby adjusting the heating method of the inner cover according to different working conditions, providing more flexible usage.

[0023] 4. This practical waste heat recovery device also includes a preheating module and a recovery module connected in sequence. The preheating module is a ceramic heat storage structure, which can preheat the gas after the gas and air are mixed, so that it can burn better and heat up to the heating temperature quickly, thereby saving energy. The recovery module is an organic Rankine cycle power generation device, which can use the heat remaining after preheating to generate electricity, thereby maintaining the operation of the entire bell furnace electrical control system and achieving maximum energy utilization efficiency. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the process flow of an embodiment of the present utility model.

[0025] Figure 2 This is a schematic diagram of the axial cross-section of the mixing chamber in an embodiment of this utility model.

[0026] Figure 3 This is a schematic diagram of the furnace body in an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of the axial cross-section of the outer cover in an embodiment of this utility model.

[0028] Figure 5 This is a schematic diagram of the inner cover in an embodiment of this utility model.

[0029] Figure 6 This is a schematic diagram of the base in an embodiment of the present utility model.

[0030] Figure 7 This is a schematic diagram of the preheating module in an embodiment of this utility model.

[0031] In the above figures: 1. Mixing chamber; 2. Furnace body; 3. Waste heat recovery device; 4. Branch pipe; 11. Pipe wall; 12. Pipe body; 13. Gas pipe; 14. Ultrasonic transducer; 21. Base; 22. Inner cover; 23. Outer cover; 31. Preheating module; 32. Recovery module; 121. Air inlet; 122. Throat section; 123. Mixed gas outlet; 211. Support plate; 212. Placement platform; 213. Insulation layer; 221. Inner air passage; 231. Air inlet; 232. Exhaust port; 233. Nozzle; 234. Outer air passage; 311. Shell; 312. Heat storage block. Detailed Implementation

[0032] The technical solution of this utility model will be further described below with reference to the accompanying drawings and embodiments.

[0033] like Figure 1 As shown in the figure, this utility model embodiment proposes a high-efficiency and energy-saving silicon steel annealing single-cell bell furnace, which includes a mixing chamber 1, a furnace body 2 and a waste heat recovery device 3 arranged in sequence.

[0034] like Figure 2 As shown, in this embodiment, the mixing chamber 1 has a Venturi tube structure, and an ultrasonic transducer 14 is also installed on the mixing chamber 1. Specifically, the mixing chamber 1 includes a cylindrical tube wall 11 and a tube body 12 with a Venturi tube structure disposed inside the tube wall 11. One end of the tube body 12 is an air inlet 121, and the other end is a mixed gas outlet 123. The middle of the tube body 12 narrows to form a throat section 122, which is also connected to a gas pipe 13. The ultrasonic transducer 14 is disposed on the outer wall of the tube body 12, corresponding to the outlet of the throat section 122. In this embodiment, a dual-frequency ultrasonic transducer 14 is used, with parameters of a main frequency of 28kHz, an auxiliary frequency of 40kHz, and an ultrasonic power density of 8W / L, thereby achieving the optimal frequency for mixing natural gas and oxygen. The mixing efficiency of the ultrasonic transducer 14 can reach 99.2%, which is at least 22% higher than that of traditional mechanical mixing structures.

[0035] like Figure 3-5 As shown, the furnace body 2 includes a base 21, an inner cover 22 disposed on the base 21, and an outer cover 23 coaxially sleeved outside the inner cover 22. The inner cover 22 has several spirally ascending inner air channels 221 on its vertical outer surface, each inner air channel 221 being a concave channel structure. The outer cover 23 has several spirally ascending outer air channels 234 on its vertical inner surface, each outer air channel 234 being a concave channel structure, such that the inner air channels 221 and outer air channels 234 are arranged opposite to each other. In this embodiment, a total of eight inner air channels 221 and eight outer air channels 234 are provided, with a pitch / diameter ratio of 1:1.618, thus achieving optimal coverage. Preferably, both the inner air channels 221 and outer air channels 234 are semi-circular tube structures, with their opposite sides radially cut along the vertical direction to form relatively open semi-circular arc-shaped channels. In addition, several equally spaced baffles are provided on the inner walls of the inner air passage 221 and the outer air passage 234. The radial length of the baffles is much smaller than the diameter of the inner air passage 221 and the outer air passage 234. The baffles can interfere with the high-speed rotating and rising airflow, causing it to slow down, thereby prolonging the residence time of the gas between the inner cover 22 and the outer cover 23, resulting in more complete combustion.

[0036] In addition, a heat-reflective coating is provided on the inner wall of the outer cover 23. In this embodiment, an Al2O3-ZrO2-TiO2 gradient composite ceramic is used, which has the technical advantage of infrared band (3-5μm) reflectivity ≥92% and visible light reflectivity ≥85%, which can effectively reduce the heat radiation heat dissipation of the internal high-temperature gas, better maintain the internal temperature of the outer cover 23, and reduce heat loss.

[0037] The bottom of the outer cover 23 is also provided with several air inlets 231. Each air inlet 231 has a nozzle 233 facing inwards. The nozzle 233 is connected to the outlet of the mixing chamber 1 through an air inlet pipe. The top side of the outer cover 23 is also provided with an exhaust port 232, which is connected to the waste heat recovery device 3 through an exhaust pipe. In this embodiment, the nozzle 233 is movably connected to the air inlet 231, allowing the nozzle 233 to rotate in the horizontal plane. The nozzle 233 is installed at the bottom end of the outer air passage 234, so that when the nozzle 233 is in a radial state, it corresponds exactly to the bottom end of the inner air passage 221. Preferably, in this embodiment, a servo motor is used to drive the nozzle 233 to rotate between 0-90°. The servo motor is embedded inside the outer cover 23, and a heat insulation sleeve is provided outside the servo motor to prevent high temperature from affecting its operation. Furthermore, the nozzle has a built-in three-channel guide vane, which is alternately distributed along the main channel at 120° and the auxiliary channel at 60°, thereby expanding the airflow coverage area discharged from the nozzle 233.

[0038] like Figure 6 As shown, the base 21 includes a support plate 211 and a placement platform 212 from bottom to top. A heat insulation layer 213 is provided between the bottom of the placement platform 212 and the support plate 211. The heat insulation layer 213 is composed of heat insulation cotton and heat insulation bricks. This reduces the spread of heat to the support plate 211 below, further reducing heat loss.

[0039] like Figure 7 As shown, the waste heat recovery device 3 includes a preheating module 31 and a recovery module 32 connected in sequence. The preheating module 31 is set in the air inlet pipe between the mixing chamber 1 and the nozzle 233 to preheat the mixed gas. The recovery module 32 collects and recovers the remaining heat. Preferably, the preheating module 31 is a ceramic fiber heat storage structure, including a shell 311 and several heat storage blocks 312 disposed inside the shell 311. The air inlet pipe branches into multiple parallel branch pipes 4 inside the shell 311. The branch pipes 4 pass through the heat storage blocks 312 and then converge into a single air inlet pipe connected to the nozzle 233, thereby transferring the heat of the exhaust gas absorbed in the heat storage blocks 312 to the air inlet pipe, which can raise the temperature of the preheated mixed gas to 450-500℃. Specifically, the heat storage block 312 has a porosity of 75% and a specific surface area of ​​2500 m². 2 / m 3The recycling module 32 is an organic Rankine cycle power generation device, with a waste heat power generation efficiency of up to 18%.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the spirit and scope of the technical solutions of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. A high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel, characterized in that: It includes a mixing chamber, a furnace body and a waste heat recovery device arranged in sequence. The mixing chamber has a venturi tube structure and is also equipped with an ultrasonic transducer. The furnace body includes a base, an inner cover mounted on the base, and an outer cover coaxially sleeved outside the inner cover. The inner cover has several spirally ascending inner air channels on its vertical outer surface. The inner air channels are concave channel structures. The outer cover has several spirally ascending outer air channels on its vertical inner surface. The outer air channels are concave channel structures, so that the inner and outer air channels are arranged opposite to each other. The bottom of the outer cover is also provided with several air inlets, each air inlet having a nozzle facing inwards. The nozzle is connected to the outlet of the mixing chamber through an air inlet pipe. The top of the outer cover is also provided with an exhaust port, which is connected to the waste heat recovery device through an exhaust pipe.

2. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 1, characterized in that: The mixing chamber includes a cylindrical tube wall and a tube body with a Venturi tube structure disposed inside the tube wall. One end of the tube body is an air inlet and the other end is a mixed gas outlet. The middle of the tube body narrows to form a throat section. The throat section is also connected to a gas pipe. The ultrasonic transducer is disposed on the outer wall of the tube body and corresponds to the outlet of the throat section.

3. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 1, characterized in that: Both the inner and outer air passages are semi-circular tube structures, with their opposite sides radially cut along the vertical direction to form semi-circular arc-shaped channels with relative openings.

4. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 3, characterized in that: The inner walls of the inner and outer air passages are also provided with several equally spaced turbulence blocks, the radial length of which is much smaller than the diameter of the inner and outer air passages.

5. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 1, characterized in that: The nozzle is movably connected to the air inlet, allowing the nozzle to rotate in the horizontal plane. The nozzle is installed at the bottom end of the outer air passage, so that when the nozzle is in a radial state, it corresponds exactly to the bottom end of the inner air passage.

6. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 1, characterized in that: The waste heat recovery device includes a preheating module and a recovery module connected in sequence. The preheating module is set in the air inlet pipe between the mixing chamber and the nozzle to preheat the mixed gas. The recovery module collects and recovers the remaining heat.

7. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 6, characterized in that: The preheating module is a ceramic heat storage structure, including a shell and several heat storage blocks disposed inside the shell. The air inlet pipe branches into multiple parallel branch pipes inside the shell. After passing through the heat storage blocks, the branch pipes merge into a single air inlet pipe and connect to the nozzle.

8. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 6, characterized in that: The recycling module is an organic Rankine cycle power generation device.

9. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 1, characterized in that: The inner wall of the outer cover is also provided with a heat-reflective coating.

10. The high-efficiency and energy-saving single-unit bell-type furnace for annealing silicon steel as described in claim 1, characterized in that: The base includes a support plate and a placement platform from bottom to top, and a heat insulation layer is provided between the bottom of the placement platform and the support plate.

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