Air distribution plate structure for a heat treatment furnace and method for designing the same

Abstract

The present application relates to the technical field of gas distribution components for heat treatment furnaces, and particularly relates to a gas distribution plate structure for heat treatment furnaces and a design method thereof. The gas distribution plate structure is arranged between a wind chamber and a particle bed in a furnace, and comprises a plate main body, which is provided with a plurality of Tesla valve type channels. Each Tesla valve type channel comprises one or more Tesla valve units combined along the thickness direction of the plate main body, which comprises an inlet section, a flow channel section, a converging section and an outlet section arranged in sequence along the gas flow direction. The flow channel section comprises a main flow passage and a bypass rotary passage located on one side of the main flow passage. After entering the inlet section from the wind chamber, the gas is divided into the main flow passage and the bypass rotary passage and then converges at the converging section, and then enters the particle bed in the furnace through the outlet section. The design method adjusts the channel structure parameters based on the furnace type and working condition constraints of the heat treatment furnace, and screens the parameter scheme in combination with the flow field evaluation index. The present application can inhibit backflow and particle backflow, improve the gas distribution uniformity at the bottom of the bed, and improve the gas distribution stability.

Description

Technical Field

[0001] This invention relates to the technical field of gas distribution components for heat treatment furnaces, and in particular to a structure and design method of an air distribution plate for heat treatment furnaces. Background Technology

[0002] Air distributors are key furnace components in heat treatment furnaces, roasting furnaces, calcining furnaces, and other thermal equipment requiring granular beds and bottom gas distribution. Their main function is to uniformly introduce gas from the air chamber into the bottom of the granular bed within the furnace, ensuring a stable gas-solid contact state and achieving stable fluidization when needed. The structure and flow resistance characteristics of the air distributor significantly impact the uniformity of gas distribution within the furnace, bed stability, operational reliability, and system energy consumption.

[0003] In existing technologies, common furnace air distribution plate structures include straight-through perforated air distribution plates, conical perforated air distribution plates, slotted air distribution plates, wind cap-type air distribution plates, and sintered perforated plates. Among them, straight-through perforated air distribution plates are widely used in various thermal equipment with requirements for bottom gas distribution in granular beds due to their simple structure, convenient processing, and low manufacturing cost.

[0004] See Figure 1 The existing heat treatment furnace structure with a perforated air distribution plate has an air chamber 1 at the bottom, and the main body 2 of the air distribution plate is located between the particle bed 5 and the air chamber 1 inside the furnace. The main body 2 has perforated channels 3. This type of air distribution plate has shortcomings in practical applications. First, the perforated structure has limited ability to regulate airflow. Gas usually passes directly through the air distribution plate along the axial direction of the channel, resulting in concentrated outlet jets and high local velocity peaks. This can easily lead to flow deviation, local strong jets, or uneven air distribution at the bottom of the particle bed, thus affecting the stable fluidization of the bed. Second, under conditions such as airflow fluctuations, start-stop switching, pulsating gas supply, or bed disturbances, the traditional perforated structure has weak ability to suppress backflow, particle backflow, and local backflow, which is not conducive to maintaining stable system operation. Third, in many engineering applications, the thickness of the air distribution plate is usually limited by factors such as furnace structure, installation space, strength requirements, and modification conditions, making it difficult to optimize by increasing the thickness or significantly changing the overall size. In this situation, simply relying on increasing the orifice size and improving the opening ratio to improve flow performance often has an adverse effect on gas distribution uniformity, structural strength, or operational stability.

[0005] Furthermore, existing research on air distribution plate channels for heat treatment furnaces largely focuses on simple geometric dimension adjustments. Effective solutions are still lacking for achieving directional airflow control, outlet flow field shaping, and passive suppression of reverse flow within a limited plate thickness through internal channel structure design. Therefore, how to improve channel flow organization, enhance bottom gas distribution stability, suppress reverse flow and particle backflow, and simultaneously consider pressure drop, gas distribution uniformity, and engineering applicability under conditions of fixed or limited air distribution plate thickness, through optimizing the internal flow channel structure without moving parts, has become a pressing technical problem to be solved in this field. Summary of the Invention

[0006] To address the shortcomings of existing furnace air distribution plates in suppressing backflow, preventing particle backflow, and ensuring uniform gas distribution at the bottom, this invention provides a structure and design method for an air distribution plate used in heat treatment furnaces. The aim is to improve the gas distribution stability at the bottom of the particle bed and the reliability of system operation while keeping the overall thickness of the air distribution plate constant or limited.

[0007] The technical solution adopted in this invention is as follows: This invention provides an air distribution plate structure for a heat treatment furnace, including a plate body disposed between the air chamber and the particle bed in the furnace. The plate body is provided with a plurality of Tesla valve-type channels, each Tesla valve-type channel including one or more Tesla valve units combined along the thickness direction of the plate body. The Tesla valve unit includes an inlet section, a flow channel section, a confluence section and an outlet section arranged sequentially along the gas flow direction; the flow channel section includes a main flow channel and a bypass rotary channel located on one side thereon. Gas enters the inlet section from the air chamber and flows along the main flow channel to form the main flow. At the same time, part of the gas flow enters the bypass rotary channel to form a rotary flow, which merges with the main flow in the confluence section and enters the particle bed in the furnace through the outlet section.

[0008] As a preferred technical solution: The multiple Tesla valve units combined along the thickness direction of the plate body have a combined structure in which the front and rear Tesla valve units are mirror images of each other and the two main channels are connected end to end to form a bending path.

[0009] The two adjacent Tesla valve-type channels on the main body of the plate are arranged in the same direction or mirror image.

[0010] The outlet section is a straight section, a gradually narrowing trumpet shape, or a gradually widening trumpet shape.

[0011] The structural parameters of the Tesla valve-type channel are adjusted according to the bottom gas distribution target of the target heat treatment furnace, and the adjustment methods include: When the bottom gas distribution objective is solely to improve the reverse backflow suppression capability, the forward and reverse impedance ratio is specifically improved through one or more of the following methods in a coordinated manner: Increase the turning radius of the bypass rotary channel; Increase the length of the bypass turnaround channel; Adjust the branch angle of the bypass turnaround channel relative to the entrance of the main channel; Adjust the convergence angle of the bypass turning channel relative to the exit of the main channel; Increase the number of Tesla valve units within a single Tesla valve-type channel; When the goal of bottom gas distribution is solely to improve the uniformity of the outlet flow field, adjust the outlet section form and the arrangement of adjacent channels.

[0012] The present invention also provides a design method for the air distribution plate structure of the heat treatment furnace, comprising: The thickness of the plate body is determined by setting constraints based on the operating conditions of the target heat treatment furnace. A target heat treatment furnace model with a Tesla valve-type perforated air distribution plate was constructed based on the thickness of the plate body. Based on the bottom gas distribution target, determine the evaluation indicators; With the thickness of the main plate fixed, multiple preliminary options are obtained by changing the adjustable structural parameters of the Tesla valve-type channel. Simulation calculations are performed on the target heat treatment furnace model to obtain the flow field information corresponding to each preliminary scheme, and the calculated values ​​of the evaluation index are obtained based on the flow field information. Based on the calculated values ​​of the evaluation indicators, the optimal parameter scheme that meets the bottom gas distribution target is selected from the preliminary schemes. The evaluation indicators include: forward flow pressure drop, reverse flow resistance, forward and reverse impedance ratio, outlet velocity uniformity, outlet flow deviation of each orifice, local high-speed zone range, recirculation zone range, pressure distribution uniformity at the bottom of the bed, particle backflow tendency, and energy consumption per unit air distribution area.

[0013] The process involves changing the adjustable structural parameters of the Tesla valve-type orifice to obtain multiple preliminary selection schemes, including: Single-factor parameter scanning was performed on each adjustable structural parameter to analyze the influence trend of each parameter change on the evaluation index and identify the key parameters that have a significant impact on the bottom gas distribution target. The key parameters are selected for orthogonal combination, and the remaining parameters are set as preset benchmark values ​​to obtain the multiple preliminary selection schemes.

[0014] The adjustable structural parameters include: inlet section length; main channel length and cross-sectional dimensions; bypass rotary channel width, length, turning radius, branch angle relative to the main channel inlet, and confluence angle relative to the main channel outlet; outlet section form and length; number of Tesla valve units in a single Tesla valve-type channel and arrangement of adjacent Tesla valve-type channels.

[0015] The flow field information includes the velocity field, pressure field, streamline distribution, recirculation region, and outlet flow field distribution.

[0016] The setting of constraints based on the operating conditions of the target heat treatment furnace includes: Based on the furnace type, bed type, bed cross-sectional dimensions, operating gas velocity, gas properties, particle characteristics, allowable pressure drop range, gas distribution uniformity requirements, air distribution plate thickness limitations, and manufacturing conditions of the target heat treatment furnace, determine the thickness of the plate body, opening ratio, number of channels, and single-hole flow distribution range.

[0017] It is understood that in this invention, "Tesla valve-type channel" refers to a flow guide channel configuration without moving parts used inside the air distributor. Through the geometric fit between the main flow channel and the bypass rotary channel, it exhibits different flow resistance characteristics under forward air distribution and reverse backflow conditions. This configuration is used in this application as an internal flow organization method for the air distributor channel, rather than as an independent valve component.

[0018] The technical solution of the present invention can achieve at least some of the following beneficial effects: This invention utilizes a Tesla valve-like flow-guiding structure within the air distribution channels to induce different flow resistance characteristics in gas under forward and reverse flow conditions. Compared to traditional straight-through orifices, this structure generates higher resistance to reverse backflow without relying on mechanical valves, thereby helping to suppress backflow of bed particles towards the air chamber, localized backflow, and reverse backflow, thus improving system operational stability.

[0019] This invention utilizes the flow diversion, redirection, and re-convergence of the main flow channel and bypass rotary channel of the Tesla valve unit to reconstruct the streamlines within the orifice, resulting in a more uniform velocity distribution at the outlet cross-section. This reduces the excessive concentration of the jet at the outlet of traditional straight-through orifices, decreases the range and peak velocity of local high-speed zones, thereby improving the gas distribution at the bottom of the particle bed and mitigating local flow deviation and jet concentration problems.

[0020] The pore structure of this invention can passively regulate the flow within the pores. Under conditions such as start-stop switching, pulsating gas supply, local pressure fluctuations, or bed disturbances, it can reduce the adverse effects of gas distribution fluctuations on the flow state at the bottom of the particle bed to a certain extent, making the initial bubbling and local bubble distribution of the bed more uniform, reducing bed pressure difference fluctuations, improving gas distribution stability, and improving the initial fluidization state of the bed.

[0021] This invention integrates functions such as flow guidance and shaping, backflow suppression, and outlet flow field adjustment within a single channel without increasing the overall thickness of the air distribution plate. It is particularly suitable for application scenarios where the thickness of the air distribution plate is fixed, the modification space is limited, or it is not advisable to significantly change the overall structure of the furnace body, and has good engineering modification adaptability.

[0022] This invention optimizes and controls the duct parameters to achieve a comprehensive balance between pressure drop, gas distribution uniformity, anti-backflow capability, and processing feasibility under specific operating conditions. In particular, by optimizing the outlet section transition form and duct array method, the gas distribution effect can be effectively improved and the risk of lateral flow deviation caused by unidirectional flow guidance can be reduced.

[0023] Other features and advantages of the invention will be set forth in the following description or may be learned by practicing the invention. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an existing heat treatment furnace that uses a perforated air distribution plate.

[0025] Figure 2 This is a schematic diagram of the structure of a heat treatment furnace with a Tesla valve-type perforated air distribution plate, as described in an embodiment of the present invention.

[0026] Figure 3 This is a schematic diagram of the structure of the Tesla valve unit according to an embodiment of the present invention.

[0027] Figure 4 This is a schematic diagram of a structure with two Tesla valve units arranged in the same direction in an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram of a structure with two Tesla valve units in an embodiment of the present invention, with adjacent channels arranged in a mirror image.

[0029] Figure 6 This is a schematic diagram of the structure of the Tesla valve orifice with three different outlet forms according to an embodiment of the present invention.

[0030] Explanation of reference numerals in the attached drawings: 1. Wind chamber; 2. Plate body; 3. Straight through hole channel; 4. Tesla valve type channel; 5. Particle bed in the furnace; 41. Inlet section; 42. Main channel; 43. Bypass rotary channel; 44. Convergence section; 45. Outlet section. Detailed Implementation

[0031] The specific embodiments of the present invention are described below with reference to the accompanying drawings.

[0032] Example 1

[0033] See Figures 2 to 6This embodiment provides a heat treatment furnace air distribution plate structure, including a plate body 2, which is disposed between the air chamber 1 and the particle bed 5 in the furnace. The plate body 2 is provided with a plurality of Tesla valve-type channels 4. Each Tesla valve-type channel 4 includes one or more Tesla valve units combined along the thickness direction of the plate body 2. The Tesla valve unit includes an inlet section 41, a flow channel section, a confluence section 44 and an outlet section 45 arranged sequentially along the gas flow direction. The flow channel section includes a main flow channel 42 and a bypass rotary channel 43 located on one side thereon. Gas enters the inlet section 41 from the air chamber 1 and flows along the main flow channel 42 to form a main flow (see...). Figure 3 (As indicated by the solid arrow in the middle), while part of the airflow enters the bypass rotary channel 43 to form a rotary flow (see...). Figure 3 (As shown by the dashed arrow in the middle), it merges with the main stream at the confluence section 44 and enters the particle bed 5 in the furnace through the outlet section 45.

[0034] As a preferred embodiment, the multiple Tesla valve units combined along the thickness direction of the plate body 2 are arranged such that the front and rear Tesla valve units are mirror images of each other and the two main channels 42 are connected end to end to form a bending path.

[0035] As a preferred method, such as Figure 2 , Figure 4 As shown, two adjacent Tesla valve-type channels 4 on the main body 2 are arranged in the same direction; or as Figure 5 As shown, two adjacent Tesla valve-type channels 4 on the plate body 2 are arranged in a mirror image. The mirror arrangement can further improve the overall gas distribution uniformity and reduce the risk of lateral flow deviation caused by unidirectional flow guidance.

[0036] As a preferred embodiment, the outlet section 45 is a straight section, a tapering trumpet shape, or a widening trumpet shape, with structures as follows: Figure 6 As shown in Figures A, B, and C. The equivalent flow size at the inlet of outlet section 45 is D1, and the equivalent flow size at the outlet is D2. When outlet section 45 is a straight section, D2 / D1 = 1.00; when outlet section 45 is a tapering funnel shape, D2 / D1 < 1.00; when outlet section 45 is a expanding funnel shape, D2 / D1 > 1.00. The tapering funnel shape gradually decreases in cross-section along the airflow direction to enhance the concentration of the outlet jet; the expanding funnel shape gradually increases in cross-section along the airflow direction to improve the diffusion of the outlet airflow and the local velocity distribution. The form and parameters of outlet section 45 are set according to the application requirements of the airflow jet shape and local velocity distribution at the outlet of the air distribution plate in different heat treatment furnaces.

[0037] In a specific manner, the shape of the bypass rotary channel 43 can be an arc-shaped rotary shape, a serpentine meandering shape, or a curved form, to create different flow resistance characteristics for forward and reverse flow.

[0038] As a specific method, the confluence section 44 is a gradually narrowing transition structure, whose cross-section gradually narrows along the airflow direction, which increases the flow velocity of the main stream and the bypass when they merge, thereby causing a stronger local impact and making the main stream and the swirling flow mix more evenly in the confluence section.

[0039] Specifically, the cross-sectional shape of the Tesla valve-type channel 4 can be circular, elliptical, rectangular, rounded rectangle, or other cross-sectional forms suitable for processing and forming.

[0040] The air distribution plate in this embodiment can be manufactured by integral machining, layered machining followed by assembly and connection, casting, welding, or additive manufacturing.

[0041] The effectiveness of the solution in this embodiment is verified through the following verification experiment.

[0042] Verification Experiment 1 right Figure 2 The air distribution effect of the air distribution plate with Tesla valve-type channels in this embodiment is compared and verified with that of the air distribution plate with traditional straight through holes.

[0043] A numerical simulation model was established, with the following parameters for the air distribution plate: the thickness of the air distribution plate is 20 mm, the opening ratio of the air distribution plate is 6%, and the equivalent hydraulic diameter of the duct is 0.30 mm. The operating parameters were set as follows: the working medium is air, at normal temperature and pressure, the apparent air velocity in the air chamber is 0.4 m / s, the bed material is quartz sand with a diameter of 0.5 mm, and the static bed height is 200 mm.

[0044] The control group adopted a traditional straight-through-hole structure, maintaining consistency with the embodiment in terms of equivalent hydraulic diameter of the channels, plate thickness, opening ratio, channel spacing, arrangement, and apparent air velocity in the wind chamber. Simulation results show that the traditional straight-through-hole outlet region forms a significant local high-speed zone, with a local peak velocity of 6.8 m / s and an outlet cross-sectional velocity variation coefficient of 0.31; in the embodiment, the local peak velocity in the channel outlet region decreases to 5.6 m / s, and the outlet cross-sectional velocity variation coefficient is 0.19. Simultaneously, under the same bed apparent air velocity conditions, the streamline distribution within the channels of the embodiment is more uniform, and the range of the high-speed zone at the outlet is significantly reduced.

[0045] An experimental testing platform was constructed, and a transparent, visualized heat treatment furnace was used for cold-state gas distribution experiments. The air distribution plate and operating parameters used in the experiment were consistent with those in the numerical simulation. The experimental results show that the traditional straight-hole air distribution plate exhibits localized flow deviation and concentrated jetting phenomena at the outlet. In this embodiment, the air distribution plate corresponds to a more uniform initial bubbling distribution in the bed, and the bed pressure difference fluctuation amplitude is reduced by approximately 10.5%.

[0046] The above verification results show that using the Tesla valve-type channel of this embodiment can improve the flow field distribution at the channel outlet and enhance the air distribution stability.

[0047] Verification Experiment 2 right Figure 2 , Figure 4 The air distribution effect of the air distribution plate with Tesla valve-type channels, the air distribution plate with traditional straight-through holes, and the air distribution plate in this embodiment are compared and verified. Figure 4 Two Tesla valve units are arranged in series along the airflow direction in each air distribution channel of the air distribution plate shown. The main flow channels of the two Tesla valve units are connected end to end and connected to the outlet section.

[0048] Numerical simulation models were established to compare forward and reverse flow under three different air distribution plate structures. Parameters were set as follows: for forward flow, the operating parameters were the same as in verification experiment 1; for reverse flow, pressure disturbance was applied from the bed side. The evaluation index was the forward pressure drop Δ. P f Reverse pressure drop △ P r and forward and reverse impedance ratio K =△ P r / △ P f Simulation results show that the Δ of the traditional straight channel P f is 1.42 kPa, △ P r is 1.47 kPa, K It is 1.04; Figure 2 The figure shows the Δ of a Tesla valve unit channel. P f is 1.76 kPa, △ P r is 5.82 kPa, K It is 3.31; Figure 4 The Δ of the two Tesla valve unit orifices shown P f is 2.15 kPa, △ P r is 13.24 kPa, K It is 6.16.

[0049] An experimental testing platform was constructed, and a transparent, visualized heat treatment furnace was used for cold-state backflow experiments. The bed material used in the experiment was wide-sieve quartz sand with a particle size of 0.20–0.50 mm, and other parameters remained consistent with those in verification experiment 1. Under conditions of an apparent air velocity of 0.4 m / s in the wind chamber and superimposed local pressure disturbances, the traditional straight-through orifice exhibited significant particle settling and short-term backflow phenomena. These phenomena were significantly reduced in a single Tesla valve unit channel, while in two Tesla valve unit channels, the number of particles entering the depth of the channel was reduced by approximately 76% compared to the traditional straight-through orifice, and the continuous backflow phenomenon within the channel was essentially suppressed.

[0050] The above verification results show that using a dual-unit series Tesla valve channel can significantly improve the ability of the air distribution plate to suppress reverse backflow, particle backflow, and local backflow.

[0051] Under the condition that other structural parameters are basically the same, appropriately increasing the number of Tesla valve units in each channel can improve the one-way resistance effect of the channel. The specific number can be determined comprehensively based on the thickness of the air distribution plate, the channel size, the properties of the fluidizing medium, the allowable pressure drop, the flow range, the flow control requirements, and the manufacturing conditions. Preferably, the number of Tesla valve units in each channel can be 2 to 6, more preferably 2 to 4; when the number of units exceeds 6, although the reverse resistance may still continue to increase, its adverse effects on the forward flow capacity, manufacturing cost, and blockage risk will also be more obvious, so it is usually no longer considered a preferred option.

[0052] Verification Experiment 3 right Figure 4 The adjacent channels shown are arranged in the same direction. Figure 5 The air distribution plate structure with mirrored adjacent channels shown is simulated and compared.

[0053] A numerical simulation model was established with a wind distribution plate size of 300 mm × 300 mm, a total of 100 holes, and the same hole spacing; all other parameters were kept the same as the wind distribution plate parameters and operating parameters of verification experiment 1.

[0054] Simulation results show that when the air distributors are arranged in the same direction, there is a lateral velocity offset in the 20 mm section above the air distributor, with the average velocity on one side of the section being about 10.8% higher than that on the other side; when they are arranged in mirror-image alternating patterns, the lateral velocity deviation is reduced to 3.6%. Cold-state gas distribution experiments show that when the air distributors are arranged in the same direction, local areas exhibit bubble formation in the low-velocity region. When the air distributors are arranged in mirror-image alternating patterns, the bubbling in the bed is more uniform, the start-up process is more stable, and the dispersion of the initial bubble formation position on the bed surface is reduced by about 14%.

[0055] The results show that using a mirrored arrangement can further improve the overall flow field uniformity of the air distribution plate and enhance operational stability.

[0056] Verification Experiment 4 right Figure 6 The air distribution plate structures of the three outlet section types shown are compared through simulation.

[0057] The simulation conditions are as follows: the outlet sections of the three sets of channels are straight, gradually narrowing horn-shaped, and gradually widening horn-shaped, respectively. Except for the outlet section shape, the air distribution plate parameters and operating parameters are the same as those in verification experiment 1.

[0058] Simulation results show that: Figure 6 The positive pressure drop of the straight section outlet channel shown in Figure A is 1.76 kPa, and the outlet velocity variation coefficient is approximately 0.23. Figure 6 The positive pressure drop of the tapered funnel-shaped outlet channel shown in Figure B is 1.84 kPa, the outlet velocity variation coefficient is about 0.27, the airflow velocity in the central region of the outlet increases by about 11.8%, the jet concentration is enhanced, and the local high-speed core region is more obvious. Figure 6 The positive pressure drop of the gradually expanding funnel-shaped outlet channel shown in Figure C is 1.69 kPa, the outlet velocity variation coefficient drops to 0.15, the local maximum velocity decreases by about 12.6%, the outlet airflow diffusion is enhanced, and the local velocity distribution is more gradual.

[0059] Simulation results demonstrate that the structural form of the outlet section 45 significantly affects the jet morphology, local velocity distribution, and forward pressure drop of the airflow at the outlet of the air distribution plate orifice. Specifically, the tapered horn-shaped outlet structure, with its gradually decreasing cross-section along the airflow direction, enhances the concentration and axial penetration of the outlet jet, but to some extent increases the local peak velocity and forward pressure drop. The expanding horn-shaped outlet structure, with its gradually increasing cross-section along the airflow direction, improves the diffusion of the outlet airflow and the uniformity of the local velocity distribution, and can reduce the intensity of the local high-speed region. The straight outlet structure falls between the two, balancing structural simplicity and basic air distribution functions.

[0060] In a specific manner, during the design of the air distribution plate structure in this embodiment, the duct parameters can be adjusted according to the bottom gas distribution target of the target heat treatment furnace. The adjustment methods include: (1) When the bottom gas distribution target is solely to improve the reverse backflow suppression capability, the forward and reverse impedance ratio is improved in a coordinated manner through one or more of the following methods: Increasing the turning radius of the bypass rotary channel allows the reverse fluid to form a longer deflection flow path in the rotary path; Increase the length of the bypass turnaround channel appropriately to increase energy loss in the reverse flow; Adjust the branch angle of the bypass turning channel relative to the entrance of the main channel to make it easier for the reverse flow to enter the bypass turning path; Adjusting the convergence angle of the bypass turning channel relative to the main channel outlet increases flow separation, collision, and local losses during reverse convergence. The number of Tesla valve units within a single Tesla valve-type channel can be appropriately increased to enhance the series unidirectional impedance effect.

[0061] (2) When the bottom gas distribution objective is solely to improve the uniformity of the outlet flow field, adjust the transition form of the confluence section and the outlet section, and coordinate with the arrangement of adjacent channels, specifically including: Convergence section adjustment method: Change the converging connection between the bypass turning channel and the main channel from a right-angle entry to a gradual slope entry or a rounded corner entry; appropriately extend the length of the converging section to slow down the sudden velocity change after the converging and reduce local deflection and eddies at the converging point.

[0062] The outlet section can be adjusted by changing the short straight section to a gradually expanding section, or by using a rounded corner expansion outlet, or by using a combination of "short straight section + expansion section" structure. By controlling the outlet expansion angle, outlet section length and rounded corner radius, the concentration of jets and local high-speed cores at the outlet can be reduced, and the fluid can be promoted to diffuse evenly above the air distribution plate.

[0063] Coordination with mirror arrangement: If the outlet flow field of a single channel tends to deflect to one side, then the two adjacent channels are arranged in a left-right mirror structure so that the lateral offset directions of the adjacent jets are opposite, thereby canceling each other out as a whole and improving the uniformity of the regional flow field.

[0064] Coordination with staggered arrangement: If a local high-speed zone is easily formed in the multi-hole array along a certain direction, a staggered arrangement is adopted in which a certain channel is in the same direction as the previous adjacent channel and is mirrored with the next channel. This makes the high-speed cores of adjacent channels staggered, weakens jet superposition, reduces strip-shaped flow deviation, and improves the overall outlet velocity uniformity.

[0065] This embodiment improves the structure of the air distributor channel, enabling gas to complete streamline reconstruction, velocity distribution adjustment, and directional flow control within a limited plate thickness. This effectively addresses the problems of concentrated outlet jet, monotonous flow field, and insufficient suppression of reverse flow in traditional straight-through orifices. The Tesla valve-type channel is set within a fixed thickness range of the air distributor, without increasing the overall thickness of the air distributor.

[0066] The air distribution plate structure of this embodiment can be widely used in roasting furnaces, calcining furnaces, drying furnaces, and other heat treatment furnaces that require gas distribution at the bottom of the particle bed. In some embodiments, the particle bed can be in a bubbling fluidized state or a circulating fluidized state. The number of Tesla valve units, orifice cross-section, branch angle, radius of rotation, confluence form, and array arrangement can be adjusted according to different heat treatment furnace types, bed types, operating gas velocities, particle characteristics, plate thickness limitations, and manufacturing conditions, thus exhibiting strong adaptability.

[0067] This embodiment employs a passive structure without moving parts, and does not rely on additional mechanical valves, elastic components, or external drive mechanisms. Therefore, it features structural stability, reliable operation, and low maintenance requirements, making it suitable for long-term, high-temperature, particulate-containing, or easily worn operating conditions. It also exhibits good parameter adjustability and engineering application value.

[0068] Example 2

[0069] This embodiment provides a design method for the air distribution plate structure of the heat treatment furnace in Embodiment 1. The target heat treatment furnace is preferably a roasting furnace, calcining furnace, drying furnace, or other thermal equipment that requires uniform bottom gas distribution, suppression of backflow, or improvement of the outlet flow field. The design method includes: S1. Set constraints based on the operating conditions of the target heat treatment furnace to determine the thickness of the plate body.

[0070] Preferably, the constraint conditions are set by: determining the overall dimensions (including thickness), opening ratio, number of channels and flow distribution range of the plate body based on the furnace type, bed type, bed cross-sectional dimensions, operating gas velocity, gas properties, particle characteristics, allowable pressure drop range, gas distribution uniformity requirements, air distribution plate thickness limit and manufacturing conditions of the target heat treatment furnace.

[0071] S2. Construct a target heat treatment furnace model with a Tesla valve-type perforated air distribution plate based on the thickness of the plate body.

[0072] S3. Determine the evaluation indicators based on the bottom gas distribution target of the target heat treatment furnace.

[0073] Preferably, the evaluation indicators include: forward flow pressure drop, reverse flow resistance, forward and reverse impedance ratio, outlet velocity uniformity, outlet flow deviation of each orifice, local high-speed zone range, reflux zone range, pressure distribution uniformity at the bottom of the bed, particle backflow tendency, and energy consumption per unit gas distribution area.

[0074] Specifically, the uniformity of the outlet velocity is characterized by the standard deviation of the velocity at each measuring point of the outlet section, the coefficient of variation, or the difference between the maximum and minimum velocity; the uniformity of the gas distribution is characterized by the flow deviation of each channel of the air distribution plate, the pressure fluctuation amplitude at the bottom of the bed, or the initial fluidization state of the bed.

[0075] S4. By changing the adjustable structural parameters of the Tesla valve-type channel, multiple preliminary selection schemes are obtained.

[0076] The initial selection of solutions can be achieved using at least one of the following methods: parameter scanning, orthogonal experiment, and response surface methodology. Preferred methods include: S41. Perform single-factor parameter scanning on each adjustable structural parameter, analyze the influence trend of each parameter change on the evaluation index, and identify the key parameters that have a significant impact on the bottom gas distribution target. S42. Select the key parameters for orthogonal combination, and set the remaining parameters as preset benchmark values ​​to obtain the multiple preliminary selection schemes.

[0077] Preferably, the adjustable structural parameters include: inlet section length; main channel length and cross-sectional dimensions; bypass rotary channel width, length, turning radius, branch angle relative to the main channel inlet, and confluence angle relative to the main channel outlet; outlet section form and length; number of Tesla valve units in a single Tesla valve-type channel and arrangement of adjacent Tesla valve-type channels.

[0078] S5. Perform simulation calculations on the target heat treatment furnace model to obtain the flow field information corresponding to each preliminary scheme, and calculate the evaluation index based on the flow field information.

[0079] Specifically, a flow model including the interior and outlet regions of the Tesla valve-type channel is established for the target heat treatment furnace model for simulation calculation; the flow field information includes: velocity field, pressure field, streamline distribution, recirculation region and outlet flow field distribution.

[0080] S6. Based on the calculated values ​​of the evaluation indicators, select the optimal parameter scheme that meets the bottom gas distribution target from the preliminary selection schemes.

[0081] The following specific examples further illustrate the technical solution of the design method in this embodiment.

[0082] This example provides a design method for the air distribution plate of a heat treatment furnace, including: (1) Set constraints according to the target working conditions: the equivalent hydraulic diameter of the duct is 0.30 mm, the thickness of the air distribution plate is 20 mm, the apparent air velocity in the air chamber is 0.4 m / s, and the bed material is quartz sand with an average particle size of 0.5 mm.

[0083] (2) Construct a target heat treatment furnace model with a Tesla valve-type perforated air distribution plate.

[0084] (3) The bottom gas distribution target is to improve the anti-counterflow capability while ensuring normal and uniform gas distribution capability. The corresponding evaluation indicators include forward pressure drop Δ P f Forward and reverse impedance ratio K = △P r / △ P f Export speed variation coefficient C v .

[0085] (4) The adjustable structural parameters of the Tesla valve-type channel include: the length of the main channel. L 1; Bypass turnaround width W 1; Bypass rotary channel turning radiusR 1; Convergence Angle θ Exit section expansion angle α Tesla valve unit quantity N ; Equivalent hydraulic diameter of the duct d e By changing the adjustable structural parameters of the Tesla valve-type channel, multiple preliminary selection schemes were obtained, including: First, with all other parameters remaining constant, a single-factor parameter scan is performed on each adjustable structural parameter to analyze the effect of changes in each parameter on the forward pressure drop Δ. P f Forward and reverse impedance ratio K and export velocity variation coefficient C v The influence trend, and based on this, identify the key parameters that have a significant impact on the ability to resist countercurrent and the gas distribution performance; Parameter scan results indicate the number of Tesla valve units. N Equivalent hydraulic diameter of the duct d e Exit section expansion angle α and confluence angle θ These parameters have a significant impact on overall performance, therefore they are considered the main factors in orthogonal analysis, while the remaining mainstream channel lengths are excluded. L 1. Bypass turning lane width W 1 and bypass turning radius R 1. Keep it at the preset baseline value; Based on the parameter scan, select N , d e , α and θ Orthogonal combination analysis was performed to reduce the number of combinations and improve screening efficiency.

[0086] (5) Perform simulation calculations on the target heat treatment furnace model to obtain the flow field information corresponding to each preliminary scheme, and calculate the corresponding Δ based on the flow field information. P f , K and C v The numerical values ​​and some preliminary selection results are shown in Table 1.

[0087] Table 1 Results of the preliminary selection

[0088] (6) Based on the calculation results of the evaluation indicators, the optimal parameter scheme is selected from the preliminary selection schemes, specifically including: Based on the results in Table 1, the following analysis and screening were conducted: First, under the premise of ensuring normal gas distribution capacity, the positive pressure drop Δ was analyzed. Pf Schemes with excessively high pressure drops or unsatisfactory outlet velocity distribution are initially eliminated; secondly, among schemes that meet the requirements for forward pressure drop and gas distribution uniformity, the forward and reverse impedance ratios are given priority. K The more advanced option. As shown in Table 1, although option P5 has the lowest forward voltage drop, its forward and reverse impedance ratio is... K With a pressure drop of only 2.94, the resistance to backflow is relatively weak; the forward pressure drops of schemes P1 and P2 are 1.70 kPa and 1.82 kPa, respectively, and the gas distribution uniformity is improved, but K is only 3.25 and 3.58, respectively, and the improvement in resistance to backflow is limited; Scheme P4... K The highest value is 7.35, and the lowest is Cv at 0.12, but its forward pressure drop increases to 2.43 kPa, indicating that although it has strong anti-reverse flow capability and good outlet uniformity, the forward flow cost is high. In contrast, scheme P3 achieves a higher forward and reverse impedance ratio of 6.28 under the condition of a forward pressure drop of 2.07 kPa, and the outlet velocity variation coefficient decreases to 0.14, indicating that it has a better comprehensive balance between anti-reverse flow capability, gas distribution uniformity, and forward pressure drop. Therefore, under the constraints set in this example, scheme P3 can be regarded as the preferred scheme. The parameter combination corresponding to this scheme is: number of Tesla valve units N=2, equivalent hydraulic diameter of the channel de=0.30 mm, outlet expansion angle α is 20°, and confluence angle θ is 45°. The results show that by combining parameter scanning and orthogonal analysis, it is possible to effectively screen out the air distribution plate channel structure parameter scheme that takes into account both normal gas distribution capability and anti-reverse flow capability.

[0089] The above adjustments to the adjustable structural parameters do not rely solely on increasing the aperture or improving the opening ratio. Instead, they involve the coordinated quantitative adjustment of parameters such as the main channel, bypass rotary channel, confluence section, and outlet section. This allows the air distributor to balance the uniformity of the outlet flow field, the ability to suppress reverse backflow, and the feasibility of processing within the allowable pressure drop range. As a result, the overall gas distribution performance of the furnace air distributor is greatly improved, and the flow field distribution at the bottom of the granular bed is improved.

[0090] It will be understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for an air distribution plate structure for a heat treatment furnace, wherein the air distribution plate structure includes a plate body disposed between the air chamber and the particle bed inside the furnace, characterized in that, The plate body is provided with a number of Tesla valve-type channels, which are set within the fixed thickness range of the air distribution plate and do not increase the overall thickness of the air distribution plate. Each Tesla valve channel includes multiple Tesla valve units combined along the thickness direction of the main body of the plate. The multiple Tesla valve units combined along the thickness direction of the main body of the plate have a combined structure in which the front and rear Tesla valve units are mirror images of each other and the two main channels are connected end to end to form a bending path. The Tesla valve unit includes an inlet section, a flow channel section, a confluence section, and an outlet section arranged sequentially along the gas flow direction; the flow channel section includes a main flow channel and a bypass rotary channel located on one side thereon; the outlet section is a gradually expanding trumpet shape with a cross-section that gradually increases along the gas flow direction. Gas enters the inlet section from the air chamber and flows along the main flow channel to form the main flow. At the same time, part of the gas flow enters the bypass rotary channel to form a rotary flow, which merges with the main flow in the confluence section and enters the particle bed in the furnace through the outlet section. The plate body has two adjacent Tesla valve-type channels arranged in a mirror image. The design method includes: The thickness of the plate body is determined by setting constraints based on the operating conditions of the target heat treatment furnace. A target heat treatment furnace model with a Tesla valve-type perforated air distribution plate was constructed based on the thickness of the plate body. Based on the bottom gas distribution target, determine the evaluation indicators; With the thickness of the main plate fixed, multiple preliminary options are obtained by changing the adjustable structural parameters of the Tesla valve-type channel. Simulation calculations are performed on the target heat treatment furnace model to obtain the flow field information corresponding to each preliminary scheme, and the calculated values ​​of the evaluation index are obtained based on the flow field information. Based on the calculated values ​​of the evaluation indicators, the optimal parameter scheme that meets the bottom gas distribution target is selected from the preliminary schemes. The evaluation indicators include: forward flow pressure drop, reverse flow resistance, forward and reverse impedance ratio, outlet velocity uniformity, outlet flow deviation of each orifice, local high-speed zone range, recirculation zone range, pressure distribution uniformity at the bottom of the bed, particle backflow tendency, and energy consumption per unit air distribution area.

2. The design method according to claim 1, characterized in that, The structural parameters of the Tesla valve-type channel are adjusted according to the bottom gas distribution target of the target heat treatment furnace, and the adjustment methods include: When the bottom gas distribution objective is solely to improve the reverse backflow suppression capability, the forward and reverse impedance ratio is specifically improved through one or more of the following methods in a coordinated manner: Increase the turning radius of the bypass rotary channel; Increase the length of the bypass turnaround channel; Adjust the branch angle of the bypass turnaround channel relative to the entrance of the main channel; Adjust the convergence angle of the bypass turning channel relative to the exit of the main channel; Increase the number of Tesla valve units within a single Tesla valve-type channel; When the goal of bottom gas distribution is solely to improve the uniformity of the outlet flow field, adjust the outlet section form and the arrangement of adjacent channels.

3. The design method according to claim 1, characterized in that, The process involves changing the adjustable structural parameters of the Tesla valve-type orifice to obtain multiple preliminary selection schemes, including: Single-factor parameter scanning was performed on each adjustable structural parameter to analyze the influence trend of each parameter change on the evaluation index and identify the key parameters that have a significant impact on the bottom gas distribution target. The key parameters are selected for orthogonal combination, and the remaining parameters are set as preset benchmark values ​​to obtain the multiple preliminary selection schemes.

4. The design method according to claim 1, characterized in that, The adjustable structural parameters include: inlet section length; main channel length and cross-sectional dimensions; bypass rotary channel width, length, turning radius, branch angle relative to the main channel inlet, and confluence angle relative to the main channel outlet; outlet section form and length; number of Tesla valve units in a single Tesla valve-type channel and arrangement of adjacent Tesla valve-type channels.

5. The design method according to claim 1, characterized in that, The flow field information includes the velocity field, pressure field, streamline distribution, recirculation region, and outlet flow field distribution.

6. The design method according to claim 1, characterized in that, The setting of constraints based on the operating conditions of the target heat treatment furnace includes: Based on the furnace type, bed type, bed cross-sectional dimensions, operating gas velocity, gas properties, particle characteristics, allowable pressure drop range, gas distribution uniformity requirements, air distribution plate thickness limitations, and manufacturing conditions of the target heat treatment furnace, determine the thickness of the plate body, opening ratio, number of channels, and single-hole flow distribution range.

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