A detachable curing barn return air filtering device

Abstract

The utility model provides a kind of detachable baking house return air filtering device, belong to baking house filtering technical field, this detachable baking house return air filtering device, including return air frame, for rectangular frame structure, for providing support for baking house return air filtering device, the inside of return air frame is provided with anti-blocking flow guide grating, filter screen component and pressure equalizing plate from top to bottom, anti-blocking flow guide grating is located above filter screen component, with return air frame fixed connection, for blocking large particle sundries into filter screen, change return air flow direction simultaneously;Filter screen component is detachably connected with return air frame, for filtering small particle impurities in return air;Pressure equalizing plate is fixedly connected with return air frame, located below filter screen component, for guiding flow to the return air filtered after filter screen component;The utility model can conveniently replace return air filtering device filter screen, and improve the efficiency of filtering in the process of baking.

Description

Technical Field

[0001] This utility model belongs to the field of drying room filtration technology, specifically, it relates to a detachable drying room return air filtration device. Background Technology

[0002] In the circulating air path of a dense curing barn, the return air vent is a crucial node for maintaining the repeated use of hot and humid air. Due to the high airflow velocity and negative pressure at the bottom of the curing barn, tobacco leaf debris, dust, and other impurities are easily sucked in and adhere to the return air vent. As the curing cycle progresses, the layer of impurities gradually thickens, the effective ventilation area decreases, and the fan's operating point drifts towards a high-resistance, low-flow area. This leads to a widening temperature and humidity difference between different tobacco layers in the same curing zone, ultimately resulting in "localized over-drying" or "suffocating" phenomena, and a decline in the commercial grade of the tobacco leaves. The traditional approach is to install a fixed metal mesh or a simple perforated plate at the return air vent. Although this can intercept some large particles, blockages require stopping the machine and removing screws for cleaning, which is time-consuming and labor-intensive. Furthermore, if cleaning is not timely, uneven blockages will further amplify the differences in airflow distribution, creating a vicious cycle. Utility Model Content

[0003] In view of this, the present invention provides a detachable oven return air filter device, which facilitates the replacement of the return air filter screen and improves the filtration efficiency during the baking process.

[0004] This utility model is implemented as follows:

[0005] This utility model provides a detachable drying oven return air filtration device, which includes a return air frame, which is a rectangular frame structure, used to support the drying oven return air filtration device. The interior of the return air frame is provided with an anti-clogging guide grille, a filter assembly, and a pressure equalizing plate from top to bottom. The anti-clogging guide grille is located above the filter assembly and is fixedly connected to the return air frame to block large particles of debris from entering the filter and to change the direction of the return air flow. The filter assembly is detachably connected to the return air frame and is used to filter small particles of impurities in the return air. The pressure equalizing plate is fixedly connected to the return air frame and is located below the filter assembly to guide the return air filtered by the filter assembly.

[0006] The technical effects of the detachable oven return air filtration device provided by this utility model are as follows: The anti-clogging guide grille, detachable filter screen assembly and pressure equalization plate are stacked inside the frame to form an integrated channel of "blocking-filtering-equalizing"; the grille pre-blocks large particles, the filter screen has a sudden drop in load on small particles, and the detachable structure allows the filter screen to be pulled out and cleaned instantly, maintaining low resistance and achieving "convenient replacement + continuous high-efficiency filtration".

[0007] Based on the above technical solution, the detachable oven return air filtration device of this utility model can be further improved as follows:

[0008] The filter assembly includes a filter frame and a filter. The filter frame is a square frame structure and is detachably connected to the return air frame via slide rails on both sides. The filter frame is fixedly connected to the filter inside, and is used to re-filter the return air filtered from the anti-clogging guide grille.

[0009] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the filter frame and the filter are solidified into an independent module. The module can be pushed and pulled out of the drying room by sliding cooperation with the slide rail and the return air frame. Farmers do not need to use tools to complete the replacement, which solves the pain point of "difficult to remove screw fixing", ensures that the filter is always clean and maintains high-efficiency filtration.

[0010] Furthermore, the slide rail includes a sliding guide rail and a fixing block. The sliding guide rail is located on the inner wall of the return air frame and corresponds to the installation position of the filter frame. The fixing block is a protrusion on both sides of the filter frame and is located on the side away from the filter frame outlet.

[0011] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the sliding guide rail and the fixed block form a self-locking slide rail. When pushed in, the limit block automatically embeds into the end face of the guide rail, and the filter screen is not sucked back under the negative pressure of the fan; when pulled out, the limit block disengages, and it can be pulled out with one pull. The operation is safe and reliable, greatly reducing the replacement time and ensuring that the filtration efficiency is not interrupted.

[0012] Furthermore, the distance between the two sliding guide rails is less than the width of the filter frame.

[0013] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the distance between the two guide rails is slightly smaller than the width of the filter screen frame, forming an interference fit, which enables the filter screen to be automatically centered and positioned during the advancement process, avoiding skew and jamming; accurate positioning ensures that the filter screen is sealed around its perimeter, preventing the bypass of dust-laden airflow, and ensuring that efficient filtration can be immediately restored each time it is reinstalled.

[0014] Furthermore, the sliding guide rail is not in contact with the filter frame on the side away from the outlet, and the distance between the side away from the outlet and the filter frame is equal to the width of the fixed block.

[0015] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the guide rail outlet end is left empty and the distance is equal to the width of the fixed block, providing room for the fixed block to be inserted. It is self-locking when pushed into the end point, without the need for additional locking parts; the structure is simplified and the number of parts is reduced, and farmers can complete the disassembly and assembly with a single push and pull, which significantly shortens the maintenance time and improves the replacement efficiency.

[0016] Furthermore, the filter screen is made of metal wire mesh or high-temperature resistant fiber mesh.

[0017] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the metal wire mesh or high-temperature resistant fiber mesh can withstand the high temperature and humidity of the drying room for a long time without softening or breaking, and the strength and precision of the filter mesh are stable; the durability of the material extends the single use cycle, reduces the frequency of replacement, and allows the "easy disassembly" advantage to be played out for a long time, and maintains high-efficiency filtration.

[0018] Furthermore, the anti-blockage guide grille is set at an angle of 2 to 5 degrees.

[0019] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the grid is tilted at 2°-5°, and after intercepting large particles, the debris will automatically slide to the lower collection area by gravity, avoiding flat mesh accumulation and blockage; the grid's self-cleaning ability reduces the burden on the filter screen, slows down the increase in resistance, and allows the filter screen to maintain a high permeability between two manual cleanings, thereby improving the filtration efficiency throughout the baking process.

[0020] Furthermore, the pressure equalizing plate has a porous structure.

[0021] The beneficial effects of adopting the above-mentioned improved scheme are as follows: the porous structure of the pressure equalizing plate divides the turbulent flow after filtration into several small streams, consumes the kinetic energy of the eddies, and makes the velocity distribution more uniform; it eliminates local high speeds and dead zones caused by blockage, ensures consistent temperature and humidity in the curing barn, and ensures uniform heating of tobacco leaves, achieving both high-efficiency filtration and high-quality curing.

[0022] Furthermore, the equalizing plate has a conical surface structure, and the cross-sectional curve of the equalizing plate is a parabola.

[0023] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: The conical parabolic pressure equalizing plate utilizes curved surface refraction and center-outer edge complementary flow guidance to further equalize the velocity field and form a vertically downward uniform flow; the improved airflow uniformity reduces local over-drying or staleness of tobacco leaves, ensures that the clean air after high-efficiency filtration is fully utilized, and improves the overall baking quality.

[0024] Furthermore, the aperture of the anti-clogging guide grille is larger than that of the filter screen, and the aperture of the pressure equalizing plate is larger than that of the filter screen.

[0025] The beneficial effects of adopting the above-mentioned improvement scheme are as follows: the grid aperture is greater than the filter screen aperture, and the pressure equalizing plate aperture is greater than the filter screen aperture, forming a gradient channel to avoid clogging at the same level; large particles stop at the grid, small particles are captured by the filter screen, clean airflow passes smoothly through the pressure equalizing plate, the pressure drop of the entire channel is minimized, the filter screen replacement cycle is extended, and the filtration efficiency remains high.

[0026] Compared with existing technologies, the beneficial effects of the detachable oven return air filtration device provided by this utility model are: the dual barrier of anti-clogging and filtration truly transforms "easy replacement" into "high efficiency and continuous operation". The anti-clogging guide grille first intercepts coarse debris such as tobacco leaf fragments and hemp fibers, and guides the debris to the edge storage area with the help of the inclined surface, significantly reducing the direct impact on the filter screen; the filter screen only needs to deal with fine dust, the surface powder cake forms slowly, and the resistance rise curve tends to be gentle. Because the clogging rate is greatly slowed down, the filter screen can maintain a larger effective ventilation area between two manual interventions, the return air volume decreases little, the fan always works in the low resistance and high efficiency zone, and the filtration efficiency throughout the entire baking cycle is thus substantially improved, instead of dropping sharply due to "not having time to clean".

[0027] The quick-assembly and disassembly structure transforms "troublesome cleaning" into "easy maintenance," providing institutional feasibility for continuous and efficient filtration. The filter frame and return air frame are connected by a drawer channel formed by sliding rails and limiting blocks. No tools or bolts are needed; farmers can simply pull out the entire filter during breaks in the drying oven when the temperature allows, rinse it with water or compressed air, and then push it back in—the entire process takes only a few minutes. This lower maintenance threshold means that cleaning frequency can be increased as needed, keeping the filter in a "low dust load" state, and filtration efficiency is no longer hampered by procrastination. Simultaneously, the fan is spared from prolonged high-resistance operation, resulting in reduced speed fluctuations and more stable airflow output, further solidifying a uniform and efficient drying environment.

[0028] The conical parabolic porous structure of the pressure equalizing plate ensures that the filtered airflow achieves uniform flow simultaneously, truly translating the advantages of high-efficiency filtration into tobacco leaf quality. Downstream of the filter, the airflow still carries eddies and velocity differences; direct return to the heating chamber could easily cause uneven temperature and humidity across the curing barn cross-section. The pressure equalizing plate, through parabolic refraction and dense perforation, disperses the high-speed core area into multiple low-speed vertical flows, eliminating local negative pressure peaks. This ensures that the return air achieves a uniform velocity and pressure field before re-entering the heating chamber. Consequently, under the same dry-bulb temperature setting, the tobacco leaves receive more consistent convective heat transfer, with color and component transformation occurring simultaneously. This avoids localized over-drying or "stale green" phenomena, binding filtration efficiency and curing quality into the same positive cycle.

[0029] The modular framework endows the "easy replacement and high-efficiency filtration" with versatility. The return air frame, slide rails, grilles, filters, and pressure equalization plates can all be prefabricated as independent modules. On-site assembly only requires plugging or bolting to adapt to dense drying barns of different widths and heights, without altering the original fan and wall structure. When the drying barn is expanded or renovated, only the number of modules needs to be increased or decreased, or the frame dimensions adjusted; the original filter components can still be used, offering high investment protection. This improved adaptability means that the "pull-out low-resistance high-efficiency filtration" technology can be quickly replicated in various drying barns, continuously saving farmers cleaning time, reducing fan load, extending equipment life, and forming a stable and reliable drying system. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A front view of a first embodiment of a detachable oven return air filtration device;

[0032] Figure 2 This is a schematic diagram of a second embodiment of a detachable oven return air filtration device;

[0033] Figure 3 A schematic diagram of a filter assembly for a detachable oven return air filtration device;

[0034] Figure 4 A schematic diagram of the slide rail for a detachable oven return air filtration device;

[0035] The attached diagram lists the components represented by each number as follows:

[0036] 1. Return air frame; 2. Anti-clogging guide grille; 3. Filter assembly; 31. Filter frame; 311. Slide rail; 3111. Sliding guide rail; 3112. Fixing block; 32. Filter; 4. Pressure equalizing plate. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings.

[0038] like Figure 1 , Figure 3 , Figure 4 The image shows a first embodiment of a detachable oven return air filtration device provided by this utility model. In this embodiment, a return air frame 1 is included, which is a rectangular frame structure used to provide support for the oven return air filtration device. The interior of the return air frame 1 is provided with an anti-clogging guide grille 2, a filter assembly 3, and a pressure equalizing plate 4 from top to bottom. The anti-clogging guide grille 2 is located above the filter assembly 3 and is fixedly connected to the return air frame 1 to block large particles of debris from entering the filter and to change the direction of the return air flow. The filter assembly 3 is detachably connected to the return air frame 1 and is used to filter small particles of impurities in the return air. The pressure equalizing plate 4 is fixedly connected to the return air frame 1 and is located below the filter assembly 3 to guide the return air filtered by the filter assembly 3.

[0039] In the above technical solution, the filter assembly 3 includes a filter frame 31 and a filter 32. The filter frame 31 is a square frame structure and is detachably connected to the return air frame 1 through slide rails 311 on both sides. The inner side of the filter frame 31 is fixedly connected to the filter 32, which is used to re-filter the return air filtered from the anti-clogging guide grille 2.

[0040] Furthermore, in the above technical solution, the slide rail 311 includes a sliding guide rail 3111 and a fixing block 3112. The sliding guide rail 3111 is located on the inner wall of the return air frame 1 and corresponds to the installation position of the filter frame 31. The fixing block 3112 is a protrusion on both sides of the filter frame 31 and is located on the side away from the outlet of the filter frame 31.

[0041] Furthermore, in the above technical solution, the distance between the two sliding guide rails 3111 is less than the width of the filter frame 31.

[0042] Furthermore, in the above technical solution, the side of the sliding guide rail 3111 away from the outlet of the filter frame 31 does not contact the filter frame 31, and the distance between the side away from the outlet and the filter frame 31 is equal to the width of the fixed block 3112.

[0043] Furthermore, in the above technical solution, the filter screen 32 is made of metal wire mesh or high-temperature resistant fiber mesh.

[0044] Furthermore, in the above technical solution, the anti-blocking guide grille 2 is set at an angle of 2~5°.

[0045] Furthermore, in the above technical solution, the equalizing plate 4 has a porous structure.

[0046] Furthermore, in the above technical solution, the aperture of the anti-blocking guide grille 2 is larger than the aperture of the filter screen 32, and the aperture of the pressure equalizing plate 4 is larger than the aperture of the filter screen 32.

[0047] Furthermore, in the above technical solution, the side wall of the return air frame 1 is also provided with an inspection port for easy opening, so that operators can easily remove the filter screen for cleaning or replacement.

[0048] like Figure 2 , Figure 3 , Figure 4 The image shows a second embodiment of a detachable oven return air filtration device provided by this utility model. In this embodiment, a return air frame 1 is included, which is a rectangular frame structure used to provide support for the oven return air filtration device. The interior of the return air frame 1 is provided with an anti-clogging guide grille 2, a filter assembly 3, and a pressure equalizing plate 4 from top to bottom. The anti-clogging guide grille 2 is located above the filter assembly 3 and is fixedly connected to the return air frame 1 to block large particles of debris from entering the filter and to change the direction of the return air flow. The filter assembly 3 is detachably connected to the return air frame 1 and is used to filter small particles of impurities in the return air. The pressure equalizing plate 4 is fixedly connected to the return air frame 1 and is located below the filter assembly 3 to guide the return air filtered by the filter assembly 3.

[0049] In the above technical solution, the filter assembly 3 includes a filter frame 31 and a filter 32. The filter frame 31 is a square frame structure and is detachably connected to the return air frame 1 through slide rails 311 on both sides. The inner side of the filter frame 31 is fixedly connected to the filter 32, which is used to re-filter the return air filtered from the anti-clogging guide grille 2.

[0050] Furthermore, in the above technical solution, the slide rail 311 includes a sliding guide rail 3111 and a fixing block 3112. The sliding guide rail 3111 is located on the inner wall of the return air frame 1 and corresponds to the installation position of the filter frame 31. The fixing block 3112 is a protrusion on both sides of the filter frame 31 and is located on the side away from the outlet of the filter frame 31.

[0051] Furthermore, in the above technical solution, the distance between the two sliding guide rails 3111 is less than the width of the filter frame 31.

[0052] Furthermore, in the above technical solution, the side of the sliding guide rail 3111 away from the outlet of the filter frame 31 does not contact the filter frame 31, and the distance between the side away from the outlet and the filter frame 31 is equal to the width of the fixed block 3112.

[0053] Furthermore, in the above technical solution, the filter screen 32 is made of metal wire mesh or high-temperature resistant fiber mesh.

[0054] Furthermore, in the above technical solution, the anti-blocking guide grille 2 is set at an angle of 2~5°.

[0055] Furthermore, in the above technical solution, the equalizing plate 4 has a conical surface structure, and the cross-sectional curve of the equalizing plate 4 is a parabola.

[0056] Furthermore, in the above technical solution, the aperture of the anti-blocking guide grille 2 is larger than the aperture of the filter screen 32, and the aperture of the pressure equalizing plate 4 is larger than the aperture of the filter screen 32.

[0057] The following is a specific application scenario provided by this device: In the hilly tobacco-growing areas of Southwest China, curing barns are mostly built on the edges of terraced fields, with a single barn holding only three to four tons of tobacco. Due to road restrictions, large maintenance equipment cannot reach them. During the curing process, the return air system often becomes clogged with debris such as broken leaves and hemp rope, causing increased fan load and decreased circulating air volume. Traditional fixed netting requires stopping the machine and removing bolts for cleaning, which takes more than half an hour. The tobacco leaves are also susceptible to temperature fluctuations. With the device in this embodiment, the anti-clogging guide grille pre-intercepts large debris and automatically slides to the edge for temporary storage using its inclined surface. When the operator observes an increase in negative pressure, they can hold the filter frame handle without stopping the machine and pull out the entire filter assembly horizontally along the sliding guide rail. The fine dust can be rinsed off with clean water outside the curing barn, and then pushed back to complete the maintenance. The entire process requires no tools or bolt removal, reducing the time to less than two minutes. The fan operating point remains stable, the temperature and humidity fluctuations inside the curing barn are significantly reduced, the tobacco leaf drying progress is consistent, and the color is uniform, achieving efficient and low-labor-intensive online filtration maintenance for small curing barns.

[0058] The following is another specific application scenario provided by this device: In the cluster curing barn base in the Huang-Huai Plain, six to seven batches of tobacco need to be cured continuously each curing season. The daily operation time of a single curing barn exceeds twenty hours. The return air system operates at high load for a long time, resulting in a high frequency of filter clogging. Traditional fixed filters can only be thoroughly cleaned after each batch, during which the filtration efficiency continues to decline, and localized high temperatures cause green marks or reddish-brown discoloration of the tobacco leaves. After installing the device of this embodiment, the anti-clogging guide grille directs large particles of debris to the edge, delaying filter clogging. The filter frame and the return air frame adopt a sliding rail-fixed block structure, allowing workers to quickly pull out the filter assembly during short-term shutdown cooling windows between batches, use compressed air to back-blown it, and then push it back into place. The pressure equalization plate conical parabolic structure re-rectifies the filtered airflow, eliminating local high-speed zones and keeping the wind speed difference across the curing barn section at a low level. This ensures consistent appearance quality of each batch of tobacco leaves during continuous operation, significantly reduces the fan current fluctuation range, and improves equipment operational stability, meeting the production needs of high-frequency curing and long-cycle operation in cluster curing barns.

[0059] Specifically, the principle of this invention is as follows: the device follows a three-stage separation approach of "first blocking large particles, then filtering small particles, and finally equalizing the flow," processing impurities in the return air in segments according to particle size. The upstream anti-clogging guide grille has a larger aperture than the filter screen and is installed at an angle of 2°–5°. When dusty, hot, and humid air is drawn down by the negative pressure of the fan and passes through the return air inlet, tobacco fragments, hemp fibers, and other particles larger than the grille aperture are first intercepted. Since the grille is not horizontally set, the intercepted material slides along the inclined surface to the edge under the combined action of gravity and airflow shearing, and is eventually temporarily stored in the collection area formed by the lower end of the grille and the frame, no longer being drawn back into the mainstream. This completes the first stage of "inertia-gravity" separation, significantly reducing the instantaneous load on the subsequent filter screen.

[0060] The airflow, after pre-separation by the grille, still carries smaller dust particles and short fibers, which then enter the removable filter assembly. The filter is made of metal wire mesh or high-temperature resistant fiber mesh, with pores smaller than the grille but larger than the pressure equalizing plate pores. The surface tension and the interwoven fiber structure form a "surface filtration" mechanism: particles are trapped on the mesh surface and form a loose powder cake, which itself also becomes a filter layer, further improving the capture efficiency. Since large particles upstream have been removed, the powder cake structure is uniform and has good air permeability, with a slow increase in resistance. The filter can maintain high permeability for a longer period of time, achieving a second-stage "deep-surface" composite filtration, providing continuously clean return air for the baking process.

[0061] Even after purification, the airflow still carries residual eddies and velocity unevenness. If it directly enters the heating chamber, it will create a high-speed core zone and a low-speed stagnation zone in the cross-section of the oven, resulting in temperature and humidity differences. The device incorporates a conical parabolic porous pressure equalizing plate downstream of the filter. When the airflow impacts the parabolic surface, it is divided and refracted, then re-converges through densely packed small holes. The geometric characteristics of the parabola force the high-speed flow at the center to diffuse outwards, while the low-speed flow at the outer edge is guided to the center. The velocity of each airflow tends to be uniform at the outlet of the small holes, forming multiple stable, vertically downward streams, completing the third stage of kinetic-static pressure conversion and flow equalization. Thus, the return air is both purified and homogenized, returning to the heating chamber with low resistance and uniform velocity, achieving simultaneous completion of "filtration" and "air equalization" within the same short channel.

[0062] The aforementioned three functional units are integrated within a single rectangular return air frame, with the filter assembly connected to the frame via a drawer-type interface consisting of a slide rail and a limiting block. This interface provides only horizontal freedom for the filter; when pulled out, the fixing block automatically disengages from the limiting block, allowing the filter to move outwards as a whole; when pushed in, the fixing block engages with the end face of the sliding guide rail, forming a self-locking mechanism that resists the reverse force generated by the negative pressure of the fan without the need for bolts. Maintenance personnel can perform the "pull-clean-push" action at any time during drying intervals without compromising the internal airtightness of the device or interrupting the hot air circulation. This extends the principle of "continuous low-resistance high-efficiency filtration" from the physical structure to the operational level, enabling the long-term filtration principle to be truly implemented in farmers' fields.

Claims

1. A detachable return air filtration device for a drying oven, characterized in that, The system includes a return air frame, a rectangular frame structure, which supports the return air filtration device in the drying oven. Inside the return air frame, from top to bottom, there are anti-clogging guide grilles, filter assemblies, and pressure equalizing plates. The anti-clogging guide grilles are located above the filter assemblies and are fixedly connected to the return air frame. They are used to block large particles of debris from entering the filter and to change the direction of the return air flow. The filter assemblies are detachably connected to the return air frame and are used to filter small particles of impurities in the return air. The pressure equalizing plate is fixedly connected to the return air frame and is located below the filter assemblies. It is used to guide the return air filtered by the filter assemblies.

2. The detachable oven return air filtration device according to claim 1, characterized in that, The filter assembly includes a filter frame and a filter. The filter frame is a square frame structure and is detachably connected to the return air frame via slide rails on both sides. The filter frame is fixedly connected to the filter inside, and is used to re-filter the return air filtered from the anti-clogging guide grille.

3. A detachable oven return air filtration device according to claim 2, characterized in that, The slide rail includes a sliding guide rail and a fixing block. The sliding guide rail is located on the inner wall of the return air frame and corresponds to the installation position of the filter frame. The fixing block is a protrusion on both sides of the filter frame and is located on the side away from the filter frame outlet.

4. A detachable oven return air filtration device according to claim 3, characterized in that, The distance between the two sliding guide rails is less than the width of the filter frame.

5. A detachable oven return air filtration device according to claim 4, characterized in that, The sliding guide rail is not in contact with the filter frame on the side away from the outlet, and the distance between the side away from the outlet and the filter frame is equal to the width of the fixed block.

6. A detachable oven return air filtration device according to claim 5, characterized in that, The filter screen is made of metal wire mesh or high-temperature resistant fiber mesh.

7. A detachable oven return air filtration device according to claim 6, characterized in that, The anti-blockage guide grille is set at an angle of 2~5°.

8. A detachable oven return air filtration device according to claim 7, characterized in that, The pressure equalizing plate has a porous structure.

9. A detachable oven return air filtration device according to claim 8, characterized in that, The equalizing plate has a conical surface structure, and its cross-sectional curve is a parabola.

10. A detachable oven return air filtration device according to claim 9, characterized in that, The aperture of the anti-clogging guide grille is larger than that of the filter screen, and the aperture of the pressure equalizing plate is larger than that of the filter screen.

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