Efficient electric heating mantle type annealing furnace based on all-hydrogen protection and control method

Abstract

The invention discloses an efficient electric heating mantle type annealing furnace based on all-hydrogen protection and a control method, and relates to the technical field of metal heat treatment. Directional circulation of hydrogen and nitrogen mixed gas is achieved through the composite circulation coil base assembly, an annular airflow channel is formed through the synergistic effect of a hopper-shaped flow guide cavity and radial flow guide supporting triangular ribs of the composite circulation coil base assembly, and the heat exchange efficiency is enhanced in cooperation with speed-adjustable fan blades; the dynamic sealing inner cover assembly adopts a sliding sealing structure of a corrugated structure inner cover and a guide sleeve rod, so that thermal expansion self-adaptive sealing is realized; the gradient heating assembly forms partition temperature control through an alloy resistance tape with a gradually decreased spiral pitch, and precise temperature control is realized by matching with a multi-section annealing curve controlled by a PLC (Programmable Logic Controller); the intelligent control system integrates the functions of oxygen analysis, dual-mode cooling and hydrogen-nitrogen proportion dynamic adjustment, and the annealing quality is optimized through temperature-pressure closed-loop control. By improving the temperature uniformity, the hydrogen utilization rate and the safe response speed of the annealing process, the stainless steel strips are efficiently treated in batches.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal heat treatment equipment, in particular to an efficient electric heating cover annealing furnace based on full hydrogen protection and a control method, which is especially suitable for the non-oxidizing annealing process of stainless steel, silicon steel and other materials. BACKGROUND

[0002] Traditional annealing furnaces mostly use nitrogen protection or gas heating, which has problems such as poor temperature uniformity, high energy consumption, and low hydrogen utilization rate. For example, the existing flow guide structure easily leads to uneven airflow distribution in the furnace, affecting the material annealing quality; the heating element layout is single, which is difficult to meet the gradient temperature field demand; the gas protection system lacks dynamic adjustment capability, which easily causes safety hazards. In addition, the cooling process relies on a single mode, which is difficult to adapt to the process requirements of different materials. Therefore, there is an urgent need for a full hydrogen protection annealing furnace integrating efficient heating, precise temperature control, dynamic sealing, and intelligent safety monitoring. SUMMARY

[0003] The purpose of the present application is to solve the above technical problems. The present application provides an efficient electric heating cover annealing furnace based on full hydrogen protection and a control method, which realizes efficient, safe and stable annealing process through the collaborative design of the composite circulating furnace table, the gradient heating assembly and the intelligent control system.

[0004] The technical scheme adopted by the present application is as follows: an efficient electric heating cover annealing furnace based on full hydrogen protection and a control method, comprising:

[0005] The composite circulating furnace table assembly is formed into a bucket-shaped flow guide cavity by extending upward from the support base, and an annular airflow channel is formed by connecting the bucket-shaped flow guide cavity and the support base through radial flow guide support triangular ribs. The center end of the flow guide support triangular rib is provided with a fan blade driven by a motor. The support base is integrated with a gas delivery assembly and a vacuum pipeline. The gas delivery assembly includes a hydrogen delivery pipe and a nitrogen delivery pipe connected in parallel through a tee joint. Each pipe is provided with an independent electromagnetic valve.

[0006] The dynamic sealing inner cover assembly includes an annular baffle and a sealing bottom plate arranged at the bottom of the corrugated cover. The sealing bottom plate is in sliding sealing cooperation with the furnace table guide column through a guide sleeve rod. The bottom surface of the sealing bottom plate is provided with a sealing ring embedded in the annular groove of the support base.

[0007] The gradient heating assembly includes a heating cover sleeved outside the inner cover. The metal inner shell surface of the heating cover is provided with spiral arranged alloy resistance strips. The pitch of the alloy resistance strips decreases from bottom to top to form a gradient heating zone.

[0008] Preferably, the windward surface of the flow guide support triangular rib is provided with a flow guide curved surface, and the curvature radius R of the flow guide curved surface satisfies: R = 0.2D + 50mm, where D is the diameter of the bottom of the bucket-shaped flow guide cavity. The flow guide curved surface forms an inclination angle of 15-25° with the horizontal plane.

[0009] Preferably, the alloy resistance band in the gradient heating assembly is divided into three heating sections:

[0010] The bottom section has a pitch of 150-200mm, covering a height H1=0.3H;

[0011] The middle section has a pitch of 100-150mm, covering a height H2=0.5H;

[0012] The top section has a pitch of 50-100mm, covering a height H3=0.2H;

[0013] Where H is the total height of the heating cover, and H1 / H2 / H3 is the covering height of the bottom / middle / top heating section.

[0014] Preferably, the full-hydrogen-protected high-efficiency electric heating annealing furnace further comprises a detachable cooling cover, which is composed of a cooling shell as the main structure; a third hanger is fixedly arranged on the top outer wall of the cooling shell, and a spray head is installed at the center position of the top inner wall; the spray head is in communication with an external water source through a water inlet pipe penetrating through the cooling shell; a forced convection fan is symmetrically installed on both sides of the top of the cooling shell, and the air outlet of the fan faces the outside of the cooling shell; a third connecting lug is symmetrically arranged on the bottom outer edge of the cooling shell, and a collar is fixedly connected to each third connecting lug; the collar is in sliding fit with the guide sleeve rod of the dynamic sealing inner cover assembly to realize positioning and installation of the cooling cover; a drain pipe joint is further arranged at the bottom of the cooling shell, and a valve for controlling the discharge of cooling water is arranged on the drain pipe joint.

[0015] Preferably, the intelligent control system comprises a temperature sensor, an oxygen analyzer and an emergency nitrogen unit connected to a PLC controller, which presets a multi-section annealing curve and realizes temperature-pressure closed-loop control.

[0016] Preferably, the intelligent control system further comprises a safety monitoring module, which integrates a micro-weight analyzer to monitor the oxygen content in real time and trigger two-stage alarms, i.e., to start nitrogen purging when O2>0.5% and to shut down the system in emergency when O2>1%.

[0017] Preferably, the intelligent control system further comprises a dual-mode cooling unit, which comprises:

[0018] a) Active cooling mode: start the fan and spray head of the cooling cover for water mist cooling;

[0019] b) Passive cooling mode: realize natural convection heat dissipation through the expansion of the corrugated inner cover.

[0020] Preferably, the dual-mode cooling unit is provided with intelligent switching logic:

[0021] When the cooling rate requirement > 15℃ / min, start the active cooling mode;

[0022] When 5℃ / min≤cooling rate requirement≤15℃ / min, adopt active+passive composite cooling;

[0023] When the cooling rate requirement < 5℃ / min, only enable passive cooling mode.

[0024] Preferably, the gas delivery assembly is configured with a hydrogen-nitrogen ratio controller to dynamically adjust the hydrogen-nitrogen mixture ratio according to the annealing stage:

[0025] Ramp-up stage: H2:N2=8:2;

[0026] Soak stage: H2:N2=9:1;

[0027] Cooling stage: H2:N2=7:3;

[0028] A gradient ratio transition is adopted when switching between stages, and the transition rate is 1% / s.

[0029] A control method for a high-efficiency electric heating batch annealing furnace based on full-hydrogen protection, comprising:

[0030] S1. After loading, start the hydraulic seal to form a pressure self-tightening seal between the inner cover annular baffle and the furnace table annular groove;

[0031] S2. Perform three-stage atmosphere replacement:

[0032] a) Vacuum to below 10 Pa;

[0033] b) After filling nitrogen to normal pressure, perform secondary vacuumization;

[0034] c) Inject hydrogen to a slight positive pressure (1.05-1.1 atm);

[0035] S3. Start the gradient heating assembly and control the power distribution of each heating section according to the preset process curve, wherein:

[0036] The bottom section power ratio is 40±5%,

[0037] The middle section power ratio is 35±5%,

[0038] The top section power ratio is 25±5%;

[0039] S4. Real-time monitor temperature uniformity, when the temperature difference ΔT>5℃, adjust the fan blade speed to V=0.5ΔT+100rpm; wherein V is the fan blade speed (rpm), ΔT is the furnace temperature difference (ΔT unit: ℃); heat to the target temperature and soak, monitor the furnace pressure in real time during the soaking period and adjust the pressure through nitrogen shunting;

[0040] S5. After the end of the heat preservation, remove the heating cover, buckle the cooling cover for air cooling and water cooling composite cooling, start the spray water cooling when the inner cover surface temperature is less than or equal to 300 DEG C, until the material temperature is less than or equal to 80 DEG C;

[0041] S6. After cooling, the final nitrogen purge is carried out, and the inner cover is unlocked and unloaded after the furnace is restored to positive pressure.

[0042] In summary, due to the adoption of the above technical scheme, the beneficial effects of the present application are:

[0043] 1. The radial flow guide rib optimizes the heat flow path, cooperates with the gradient heating area of the heating cover with decreasing pitch, realizes directional conduction and uniform distribution of heat flow, and significantly improves the uniformity of the furnace temperature, providing a stable thermal environment for high-precision annealing.

[0044] 2. The sliding seal is formed between the corrugated inner cover and the guide sleeve rod, combined with the double-stage sealing ring of the furnace table annular groove, to build a pressure self-adaptive sealing system. This design can adapt to thermal expansion deformation under high temperature working conditions, while ensuring high airtightness, allowing a certain range of thermal expansion compensation, and significantly improving the safety of equipment operation.

[0045] 3. During cooling, two modes of integrated active water mist cooling and passive natural convection cooling are intelligently switched according to process requirements. The active mode realizes forced heat exchange through atomizing nozzles and fans, and the passive mode utilizes the corrugated inner cover to promote natural convection, and the cooling rate is flexibly adjustable.

[0046] 4. The safety monitoring module integrates a high-precision oxygen analyzer and an emergency nitrogen protection system, with a two-stage alarm and rapid response mechanism. When an abnormality is detected, nitrogen purging or emergency shutdown can be started in a short time to quickly remove the furnace atmosphere from the dangerous range.

[0047] In summary, through the deep integration of structural innovation and intelligent control, the annealing furnace realizes multiple breakthroughs in safety, efficiency, energy consumption and product quality control, and improves the comprehensive efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0048] The present application will be described by way of example and with reference to the accompanying drawings, in which:

[0049] Figure 1 is a schematic diagram of the heating state assembly structure of the present application;

[0050] Figure 2 is a schematic diagram of the cooling state assembly structure of the present application;

[0051] Figure 3 is a schematic diagram of the structure of the present application in the state of installing a steel coil and an inner cover;

[0052] Figure 4 is a schematic diagram of the main view structure of the furnace table of the present application;

[0053] Figure 5 is a schematic diagram of the top view of the furnace table of the present application;

[0054] Figure 6 is a schematic diagram of the front view of the inner cover of the present application;

[0055] Figure 7 is a schematic diagram of the top view of the inner cover of the present application;

[0056] Figure 8 is a schematic diagram of the front view of the heating cover of the present application;

[0057] Figure 9 is a schematic diagram of the top view of the heating cover of the present application;

[0058] Figure 10 is a schematic diagram of the front view of the cooling cover of the present application;

[0059] Figure 11 is a block diagram of the intelligent control system of the present application.

[0060] Marked in the figure: 1 - composite circulation furnace table assembly, 11 - annular bottom plate, 12 - flow guide support triangular rib, 13 - bucket-shaped flow guide cavity, 14 - positioning base, 15 - support base, 151 - first threaded hole, 152 - annular groove, 16 - vacuum pipeline, 17 - temperature sensor, 18 - motor, 181 - fan blade, 10 - gas conveying assembly, 101 - electromagnetic valve, 102 - nitrogen conveying pipe, 103 - hydrogen conveying pipe, 2 - dynamic sealing inner cover assembly, 21 - corrugated structure inner cover, 22 - first hanger, 23 - annular baffle, 24 - guide sleeve rod, 25 - sealing bottom plate, 26 - first connecting lug, 27 - second threaded hole, 3 - heating cover, 31 - heat insulation shell, 310 - metal outer shell, 311 - high-temperature-resistant heat preservation filling layer, 312 - metal inner shell, 313 - annular clamping groove, 32 - second hanger, 33 - alloy resistance band, 34 - electric control box, 35 - second connecting lug, 36 - guide sleeve, 4 - cooling cover, 41 - cooling shell, 42 - fan, 43 - spray head, 44 - water inlet pipe, 45 - third hanger, 46 - valve, 47 - drain pipe joint, 48 - third connecting lug, 49 - sleeve ring, 5 - guide column. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0062] The following detailed description of embodiments of the application in the accompanying drawings provides merely examples of selected embodiments of the application, and is not intended to limit the scope of the application as claimed. Based upon the embodiments of the application described herein, numerous other embodiments will be apparent to those skilled in the art without requiring creative or inventive abilities.

[0063] In one embodiment of the application, as shown in Figures 1-11 The embodiment provides a high-efficiency electric heating type annealing furnace based on full-hydrogen protection and a control method, which comprises the following steps:

[0064] The composite circulating furnace table assembly 1 is formed in a bucket shape by extending upward from the support base 15, and is connected by the radial flow guide support triangular ribs 12 to form an annular air flow channel. The center end of the flow guide support triangular ribs 12 is provided with a fan blade 181 driven by a motor 18. The support base 15 is integrated with a gas conveying assembly 10 and a vacuum pipeline 16. The gas conveying assembly 10 includes a hydrogen conveying pipe 103 and a nitrogen conveying pipe 102 connected in parallel through a tee joint. Each pipe is provided with an independent electromagnetic valve 101.

[0065] The dynamic sealing inner cover assembly 2 includes an annular baffle 23 arranged at the bottom of the corrugated cover and a sealing bottom plate 25. The sealing bottom plate 25 is in sliding sealing cooperation with the furnace table guide column 5 through a guide sleeve rod 24, and the bottom surface is provided with a sealing ring embedded in the annular groove 152 of the support base 15.

[0066] The gradient heating assembly includes a heating cover 3 sleeved outside the inner cover, and the metal inner shell 312 of the heating cover 3 is provided with alloy resistance bands 33 arranged in a spiral. The pitch of the alloy resistance bands 33 decreases from bottom to top to form a gradient heating zone.

[0067] Specifically, the composite circulating furnace base assembly 1 serves as a basic support unit, and its core components are connected and realize air circulation through a multilayer radial structure: a positioning base 14 is vertically fixed at the center of a support base 15, a bucket-shaped flow guide cavity 13 is rigidly connected with the support base 15 through the positioning base 14, a ring-shaped bottom plate 11 is horizontally installed at the top end of the positioning base 14, and the diameter of the ring-shaped bottom plate 11 is completely matched with the bottom of the bucket-shaped flow guide cavity 13. The ring-shaped bottom plate 11 and the bucket-shaped flow guide cavity 13 are connected through radially arranged flow guide support triangular ribs 12, and 12 groups of the triangular ribs are uniformly distributed at an angle of 60°, the outer ends of the triangular ribs are welded with the edges of the ring-shaped bottom plate 11, and the inner ends of the triangular ribs converge at a motor 18 mounting seat, the motor 18 is fixed on the mounting seat and drives a fan blade 181 to rotate. A vacuum pipeline 16 and a gas conveying assembly 10 of the support base 15 penetrate through the positioning base 14 and the bucket-shaped flow guide cavity 13 and are arranged along the gaps between the flow guide support triangular ribs 12: a temperature sensor 17 is installed in the vacuum pipeline 16, a gas conveying pipe is branched into a nitrogen conveying pipe 102 and a hydrogen conveying pipe 103 through a three-way pipe, and each branch pipe is provided with an independent electromagnetic valve 101. A ring-shaped groove 152 and a first screw hole 151 are processed on the upper surface of the support base 15, the ring-shaped groove 152 is embedded with a sealing ring to provide a sealing installation basis for a dynamic sealing inner cover assembly 2; guide columns 5 are vertically fixed at both ends of the support base 15 and serve as guide references for lifting of the dynamic sealing inner cover assembly 2.

[0068] The dynamic sealing inner cover assembly 2 is connected with the furnace base through a sealing structure and a guide mechanism: a first hanger 22 is welded at the top of a corrugated structure inner cover 21 for hoisting, and a sealing bottom plate 25 is integrally formed at the bottom edge of the corrugated structure inner cover 21, the bottom surface of the sealing bottom plate 25 is provided with a ring-shaped baffle 23 corresponding to the ring-shaped groove 152 of the furnace base, and an initial sealing interface is formed after the ring-shaped baffle 23 is embedded in the ring-shaped groove 152; a second screw hole 27 is formed on the surface of the sealing bottom plate 25 and is connected with the first screw hole 151 of the furnace base through a bolt to realize pressure self-tightening sealing. The sealing bottom plate 25 is fixed with guide sleeve rods 24 at both ends through first connecting ears 26, the guide sleeve rods 24 are coaxially sleeved with the guide columns 5 of the furnace base to form a vertical direction sliding pair, allowing the inner cover to move accurately along the guide columns 5 during lifting, and at the same time, the guide sleeve rods 24 can elastically compensate for a small radial deviation through a sealing ring. When the corrugated structure inner cover 21 is sleeved on the composite circulating furnace base assembly 1, the ring-shaped baffle 23 is embedded in the ring-shaped groove 152 of the support base 15, and the ring-shaped baffle 23 blocks external air together with the sealing ring, the gas conveying assembly 10 and the vacuum pipeline 16 of the furnace base to form an independent annealing atmosphere cavity.

[0069] The heating hood 3 is connected to the outside of the inner hood through a guide positioning structure to form a gradient heating system: a second hanger 32 is welded on the top of the insulation shell 31 for overall lifting, and a guide sleeve 36 is fixed to the two ends of the bottom through a second connecting ear 35. The sleeve is coaxially connected to the inner hood guide sleeve rod 24, allowing the heating hood 3 to move vertically along the inner hood and maintain radial positioning; three groups of spirally arranged alloy resistance bands 33 are set on the inner wall of the insulation shell 31, and the power switch is integrated into the side electric control box 34, which is connected to the furnace table measurement and control system through a cable. A high-temperature resistant insulation filling layer 311 of a composite structure of aluminum silicate refractory fiber modules and lightweight refractory bricks is filled between the metal outer shell 310 and the metal inner shell 312 of the insulation shell 31 to form a high-efficiency insulation layer; an annular groove 313 is set on the bottom edge, which precisely matches the annular baffle 23 on the top of the inner hood to achieve an airtight seal between the heating area and the outside world. The alloy resistance strip 33 is fixed to the surface of the metal inner shell 312 along a spiral trajectory and is controlled on and off by the switch element in the electrical control box 34. Its power output is adjusted in real time by the furnace PLC system according to the annealing process to form a gradient heating area from bottom to top.

[0070] The overall assembly connection logic: The support base 15 of the compound circulation furnace assembly 1 serves as the foundation layer, with the dynamic sealing inner cover assembly 2 and the heating cover 3 sequentially sleeved upwards: the dynamic sealing inner cover assembly 2 is inserted into the annular groove 152 of the compound circulation furnace assembly 1 through the annular baffle 23 of the sealing bottom plate 25, and the guide sleeve 24 penetrates the guide columns 5 at both ends of the support base 15, forming a sealed sliding connection; the heating cover 3 is sleeved onto the guide sleeve 24 of the dynamic sealing inner cover assembly 2 through the guide sleeve 36, and the annular groove 313 at the bottom of the heating cover 3 engages the annular baffle 23 at the top of the inner cover, forming a three-layer concentric sleeve structure. The fitting seal ring of the annular groove 152 and the annular baffle 23 forms the first airtight seal surface (leakage rate ≤ 5mL / min); the mechanical positioning and sealing material of the annular groove 313 and the annular baffle 23 form the second airtight seal surface, ensuring the integrity of the full hydrogen protective atmosphere. The inner cover is lifted and lowered by hoisting the guide sleeve 24 along the guide column 5, and the heating cover 3 is lifted and lowered by an electric hoist; the temperature sensor 17, the gas pipe solenoid valve 101, the heating cover 3 resistance belt switch, etc. are all connected to the intelligent control system through cables to form a closed-loop control network of temperature-pressure-flow.

[0071] In another embodiment of the present invention, the windward surface of the diversion support triangular rib 12 is provided with a diversion curved surface, the curvature radius R of which satisfies: R=0.2D+50mm, where D is the bottom diameter of the bucket-shaped diversion cavity 13, and the diversion curved surface forms an inclination angle of 15-25° with the horizontal plane.

[0072] In another embodiment of the present invention, the alloy resistance belt 33 in the gradient heating assembly is divided into three heating sections:

[0073] The bottom section has a pitch of 150-200mm, and the coverage height H1=0.3H;

[0074] The middle section has a pitch of 100-150mm, and the coverage height H2=0.5H;

[0075] The top section has a pitch of 50-100mm, and the coverage height H3=0.2H;

[0076] Wherein H is the total height of the heating cover 3, and H1 / H2 / H3 is the coverage height of the bottom / middle / top heating section.

[0077] In another embodiment of the present application, the high-efficiency electric heating annealing furnace based on full-hydrogen protection further comprises a detachable cooling cover 4, which is composed of a cooling shell 41 as the main structure; a third hanger 45 is fixedly arranged on the top outer wall of the cooling shell 41, and a spray head 43 is installed at the center position of the top inner wall; the spray head 43 is communicated with an external water source through a water inlet pipe 44 penetrating through the cooling shell 41; forced convection fans 42 are symmetrically installed on both sides of the top of the cooling shell 41, and the air outlets of the fans 42 are directed to the outside of the cooling shell 41; third connecting ears 48 are symmetrically arranged at the bottom outer edge of the cooling shell 41, and a collar 49 is fixedly connected to each third connecting ear 48; the collar 49 is in sliding fit with the guide sleeve rod 24 of the dynamic sealing inner cover assembly 2 to realize the positioning installation of the cooling cover 4; a drain pipe joint 47 is further arranged at the bottom of the cooling shell 41, and a valve 46 for controlling the discharge of cooling water is arranged on the drain pipe joint 47.

[0078] Specifically, the cooling hood 4, serving as the temperature control unit of the annealing furnace, is sleeved onto the outside of the inner hood via a guide and positioning structure. That is, after the heating hood 3 is removed, the cooling hood 4 is installed for cooling, achieving dual-mode cooling. The cooling shell 41 is welded from Q235B carbon steel, with axial fans 42 symmetrically mounted at both ends of the top, with the air inlet of the fans 42 facing the center of the cooling hood 4, forming a forced convection air duct. An atomizing nozzle 43 is embedded in the top inner wall and connected to an external cooling water source via a Φ20mm stainless steel water inlet pipe 44, which is equipped with a solenoid regulating valve. A third hanger 45 is welded to the center of the top of the cooling shell 41 and cooperates with the electric hoist hook to achieve overall lifting. The bottom of the cooling shell 41 is fixed with a collar 49 via symmetrically distributed third connecting ears 48. The collar 49 forms a clearance fit with the guide sleeve 24, allowing the cooling shell 4 to slide vertically along the guide sleeve 24. A drain connection 47 is located at the center of the bottom of the cooling shell 41, equipped with a manual ball valve for drainage control. The outlet of the pipe is connected to a condensate collection tank, which is equipped with a liquid level sensor and linked to the PLC system. The cooling hood 4 is mounted on the outside of the inner hood. The arrangement of the fan 42 and nozzle 43 ensures that the atomized cooling water evenly covers the top and side walls of the inner hood, achieving forced heat exchange in active cooling mode. The coaxial design of the collar 49 and the guide sleeve 24 ensures precise control of the cooling position during the annealing process.

[0079] Overall assembly connection logic: Based on the original two-layer structure of the furnace table and the inner cover, a cooling cover 4 is added on the top to form a multi-layer nested system: the support base 15 serves as the base layer, carrying the positioning base 14, the guide system and the air path components; the annular baffle 23 is embedded in the annular groove 152 of the furnace table, and the guide sleeve 24 cooperates with the guide column 5 of the support base 15 to form a sealed sliding connection; the ring 49 is sleeved on the inner cover guide sleeve 24, and the fan 42 and the nozzle 43 face the surface of the inner cover to form a cooling medium action channel. The fan 42, the solenoid valve 101 of the nozzle 43, and the drain valve 46 are connected to the furnace platform PLC system via control cables and are linked in real time with the temperature sensor 17. When the annealing curve enters the cooling phase and the required cooling rate exceeds 15°C / min, the PLC triggers the fan 42 to operate at high speed and opens the solenoid valve 101 of the nozzle 43. Cooling water is pressurized through the water inlet pipe 44 and then atomized and sprayed out by the nozzle 43. The air flow channel between the cooling hood 4 and the inner hood is designed to be 50-100mm wide. In passive cooling mode, heat is naturally dissipated through the cooling outer shell 41 and the corrugated inner hood 21, eliminating the need to activate the fan 42 and nozzle 43. The clearance between the collar 49 and the guide sleeve 24 ensures free vertical sliding. The polytetrafluoroethylene coating on the guide sleeve 24 reduces lifting resistance and prevents interference with the furnace's internal gas sealing system. The sealing surface between the annular baffle 23 and the annular groove 152 forms a fully hydrogen-protected space independent of the cooling system.

[0080] In another embodiment of the present application, the intelligent control system comprises a PLC controller connected with a temperature sensor 17, an oxygen analyzer and an emergency nitrogen unit, the PLC presets a multi-stage annealing curve and realizes temperature-pressure closed-loop control.

[0081] In another embodiment of the present application, the intelligent control system further comprises a safety monitoring module integrated with a micro-weight analyzer for real-time monitoring of oxygen content and triggering two-stage alarms, i.e., starting nitrogen purging when O2>0.5% and emergency shutdown when O2>1%;

[0082] In another embodiment of the present application, the intelligent control system further comprises a dual-mode cooling unit, which comprises:

[0083] a) Active cooling mode: starting the fan 42 and the spray head 43 of the cooling cover 4 for water mist cooling;

[0084] b) Passive cooling mode: achieving natural convection heat dissipation through the expansion of the corrugated inner cover 21.

[0085] In another embodiment of the present application, the dual-mode cooling unit is provided with intelligent switching logic:

[0086] When the cooling rate requirement is >15℃ / min, the active cooling mode is started;

[0087] When 5℃ / min≤cooling rate requirement≤15℃ / min, active+passive composite cooling is adopted, where the active cooling only uses the fan or only sprays or both, but with reduced power output;

[0088] When the cooling rate requirement is <5℃ / min, only the passive cooling mode is enabled.

[0089] In another embodiment of the present application, the gas delivery assembly 10 is configured with a hydrogen-nitrogen ratio controller for dynamically adjusting the hydrogen-nitrogen mixing ratio according to the annealing stage:

[0090] In the warming-up stage: H2:N2=8:2;

[0091] In the holding-up stage: H2:N2=9:1;

[0092] In the cooling-down stage: H2:N2=7:3;

[0093] A gradient ratio transition is adopted when switching between stages, with a transition rate of 1% / s.

[0094] In another embodiment of the present application, a control method for any of the above-mentioned high-efficiency electric heating-type annealing furnaces based on full-hydrogen protection and control methods comprises:

[0095] S1 after loading the furnace to start the hydraulic seal, so that the inner cover annular baffle 23 and the hearth annular groove 152 to form a pressure self-tightening seal;

[0096] S2. Perform three-stage atmosphere replacement:

[0097] a) Evacuate to below 10Pa;

[0098] b) Fill with nitrogen to normal pressure and then evacuate twice;

[0099] c) injecting hydrogen to a slightly positive pressure (1.05-1.1 atm);

[0100] S3. Start the gradient heating component and control the power distribution of each heating section according to the preset process curve, where:

[0101] The power of the bottom section accounts for 40±5%,

[0102] The power of the middle section accounts for 35±5%,

[0103] The power of the top section accounts for 25±5%;

[0104] S4. Monitor temperature uniformity in real time. When the temperature difference ΔT exceeds 5°C, adjust the speed of fan blade 181 to V = 0.5ΔT + 100 rpm, where V is the speed of fan blade 181 (rpm) and ΔT is the temperature difference within the furnace (ΔT in °C). Heat to the target temperature and then hold the temperature. During this holding period, monitor the furnace pressure in real time and adjust the pressure using the nitrogen shunt.

[0105] S5. After the insulation is completed, remove the heating cover and fasten the cooling cover for air cooling and water cooling. When the surface temperature of the inner cover is ≤300℃, start spraying water cooling until the material temperature is ≤80℃;

[0106] S6. After cooling is completed, perform a final nitrogen purge, unlock the inner cover and unload after the positive pressure in the furnace is restored.

[0107] It also includes exception handling procedures:

[0108] When the hydrogen leakage rate is detected to be greater than 0.1L / min, emergency nitrogen replacement is immediately started, and the replacement flow rate Q = 120m 3 / h×(1+leakage rate / 0.1); Q is the nitrogen replacement flow rate (m 3 / h), the leakage rate is the hydrogen leakage rate (L / min);

[0109] When temperature rebound occurs during the cooling stage, the cooling water flow rate is automatically increased by ΔQ = 10 × (T_actual - T_set) L / min; where ΔQ is the cooling water flow rate increment (L / min), T_actual is the actual temperature (°C), and T_set is the target temperature (°C).

[0110] Further, an annealing quality prediction model is established:

[0111] σ = a · (t_ holding / 100) + β · ln(ΔT_max) + γ · (V_ cooling) ^ 0.5

[0112] wherein σ is the material residual stress, a, β, γ are material related coefficients, t_ holding is the holding time (min), ΔT_max is the maximum temperature difference during annealing (℃), V_ cooling is the cooling rate (℃ / min), the process parameters are optimized in real time to make σ ≤ σ_target, that is, by dynamically adjusting the annealing process parameters, the residual stress (σ) of the material is always controlled within the target value (σ_target), so as to ensure the stability and consistency of product quality.

[0113] Application Example 1: Annealing of Stainless Steel Strip

[0114] 1. After loading, start the hydraulic seal, and embed the inner cover with the annular groove 152 of the furnace table;

[0115] 2. Three-stage atmosphere replacement: vacuum to 8 Pa → nitrogen to normal pressure → secondary vacuum → hydrogen to 1.08 atm;

[0116] 3. Start gradient heating, set the bottom / middle / top power ratio to 38% / 37% / 25%;

[0117] 4. Monitor the temperature difference ΔT = 3 ℃ in real time, adjust the fan blade 181 speed to V = 0.5 × 3 + 100 = 101.5 rpm;

[0118] 5. Cooling stage requires a cooling rate of 18 ℃ / min, active cooling mode is enabled, and the fan 42 frequency is adjusted to 45 Hz.

[0119] Application Example 2: Abnormal Processing

[0120] When the oxygen analyzer detects O2 = 0.6%, the system starts nitrogen purging and alarms; if the hydrogen leakage rate reaches 0.15 L / min, emergency nitrogen is injected at a flow rate of Q = 120 × (1 + 0.15 / 0.1) = 300 m 3 / h to ensure safety.

Claims

1. High-efficiency electric heating bell-type annealing furnace based on full hydrogen protection, characterized in that: include: A composite circulation furnace platform assembly (1) is formed by a support base (15) extending upward to form a bucket-shaped flow guide cavity (13), and the two are connected by radial flow guide support triangular ribs (12) to form an annular airflow channel, and the central end of the flow guide support triangular rib (12) is provided with a fan blade (181) driven by a motor (18), and the support base (15) is integrated with a gas transmission assembly (10) and a vacuum pipe (16), and the gas transmission assembly (10) includes a hydrogen transmission pipe (103) and a nitrogen transmission pipe (102) connected in parallel through a tee pipe, and each pipe is provided with an independent solenoid valve (101); A dynamic sealing inner cover assembly (2) includes an annular baffle (23) and a sealing bottom plate (25) provided at the bottom of the corrugated cover (21); the sealing bottom plate (25) forms a sliding seal with the furnace guide column (5) via a guide sleeve (24); and a sealing ring is provided on its bottom surface for engagement with an annular groove (152) of the support base (15); The gradient heating component comprises a heating cover (3) sleeved on the outside of an inner cover, wherein the surface of the metal inner shell (312) is provided with a spirally arranged alloy resistance band (33), wherein the pitch of the alloy resistance band (33) decreases from bottom to top to form a gradient heating zone.

2. The high-efficiency electric heating bell-type annealing furnace based on full hydrogen protection according to claim 1 is characterized in that: The windward surface of the diversion support triangular rib (12) is provided with a diversion curved surface, and the diversion curved surface forms an inclination angle of 15-25 degrees with the horizontal plane.

3. The high-efficiency electric heating bell-type annealing furnace based on full hydrogen protection according to claim 1 is characterized in that: The alloy resistance band (33) in the gradient heating assembly is divided into three heating sections: the bottom section has a pitch of 150-200 mm and a covering height H1 = 0.3H; The pitch of the middle section is 100-150mm, and the covering height H2=0.5H; The pitch of the top section is 50-100mm, and the covering height H3 = 0.2H; Where H is the total height of the heating hood.

4. The high-efficiency electric heating bell-type annealing furnace based on full hydrogen protection according to claim 1 is characterized in that: The invention also includes a detachable cooling cover (4), wherein the cooling cover (4) is composed of a cooling shell (42) as a main structure; a third hanger (45) is fixedly provided on the top outer wall of the cooling shell (42), and a nozzle (43) is installed at the center of the top inner wall, and the nozzle (43) is connected to the external water source through a water inlet pipe (44) passing through the cooling shell (42); forced convection fans (41) are symmetrically installed on both sides of the top of the cooling shell (42), and the air outlet of the fan (41) faces the cooling shell (42). The cooling shell (42) is externally provided with a third connecting ear (48) symmetrically arranged on the outer edge of the bottom of the cooling shell (42), and each third connecting ear (48) is fixedly connected with a collar (49), and the collar (49) is slidably matched with the guide sleeve (24) of the dynamic sealing inner cover assembly (2) to realize the positioning installation of the cooling cover (4); the bottom of the cooling shell (42) is also provided with a drain pipe joint (47), and the drain pipe joint (47) is equipped with a valve (46) for controlling the discharge of cooling water.

5. The high-efficiency electric heating bell-type annealing furnace based on full hydrogen protection according to any one of claims 1 to 4, characterized in that: The intelligent control system also includes a temperature sensor (17), an oxygen analyzer and an emergency nitrogen unit connected to a PLC controller. The PLC presets multiple annealing curves and realizes temperature-pressure closed-loop control.

6. The high-efficiency electric heating bell-type annealing furnace based on full hydrogen protection according to claim 5 is characterized in that: The intelligent control system also includes a safety monitoring module, which integrates a microgravimetric analyzer to monitor oxygen content in real time and trigger a two-level alarm. When O2>0.5%, nitrogen purge is started, and when O2>1%, emergency shutdown is triggered.

7. The high-efficiency electric heating bell-type annealing furnace based on full hydrogen protection according to claim 5 is characterized in that: The intelligent control system further comprises a dual-mode cooling unit, which comprises: a) Active cooling mode: starting the fan (42) and the nozzle (43) of the cooling hood (4) to perform water mist cooling; b) Passive cooling mode: natural convection heat dissipation is achieved through the expansion and contraction of the corrugated structure inner cover (21).

8. The high-efficiency electrically heated annealing furnace based on full hydrogen protection according to claim 7 is characterized in that: The dual-mode cooling unit features intelligent switching logic: When the cooling rate is required to be greater than 15°C / min, the active cooling mode is activated; When the cooling rate requirement is 5℃ / min≤≤15℃ / min, active + passive composite cooling is used; When the cooling rate requirement is <5℃ / min, only the passive cooling mode is enabled.

9. The high-efficiency electrically heated annealing furnace based on full hydrogen protection according to claim 1, characterized in that: The gas delivery assembly (10) is equipped with a hydrogen-nitrogen ratio controller to dynamically adjust the hydrogen-nitrogen mixing ratio according to the annealing stage: Heating stage: H2:N2=8:2; Insulation stage: H2:N2=9:1; Cooling stage: H2:N2=7:3; Gradient proportional transition is adopted when switching between stages, and the transition rate is 1% / s.

10. A control method for a high-efficiency electric heating bell-type annealing furnace based on full hydrogen protection, characterized in that: include: S1 after loading the furnace to start the hydraulic seal, so that the inner cover annular baffle (23) and the hearth annular groove (152) to form a pressure self-tightening seal; S2. Perform three-stage atmosphere replacement: a) Evacuate to below 10Pa; b) Fill with nitrogen to normal pressure and then evacuate twice; c) injecting hydrogen to a slightly positive pressure (1.05-1.1 atm); S3. Start the gradient heating component and control the power distribution of each heating section according to the preset process curve, where: The power of the bottom section accounts for 40±5%, The power of the middle section accounts for 35±5%, The power of the top section accounts for 25±5%; S4. Real-time monitoring of temperature uniformity. When the temperature difference ΔT>5°C, adjust the fan blade (181) speed to V = 0.5ΔT + 100 rpm; where V is the fan blade speed, ΔT is the temperature difference in the furnace, heat to the target temperature and then keep warm. During the holding period, monitor the pressure in the furnace in real time and adjust the pressure through the nitrogen shunt; S5. After the insulation is completed, remove the heating cover and fasten the cooling cover for air cooling and water cooling. When the surface temperature of the inner cover is ≤300℃, start spraying water cooling until the material temperature is ≤80℃; S6. After cooling is completed, perform a final nitrogen purge, unlock the inner cover and unload after the positive pressure in the furnace is restored.

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