A formaldehyde oxidation reactor with an easy-to-clean airflow distribution plate

Abstract

This invention relates to the field of chemical reaction equipment technology, specifically to a formaldehyde oxidation reactor with an easy-to-clean airflow distribution plate. The reactor includes a reactor body, an inlet chamber, an airflow distribution plate, and a cleaning system. The cleaning system includes a gas collecting hood disposed within the inlet chamber, a gas delivery mechanism that drives the gas collecting hood to rotate around the axis of the reactor body while adhering to the bottom surface of the airflow distribution plate, and a high-pressure pulse source located outside the reactor body. By setting a sliding gas collecting hood within the inlet chamber and cooperating with the external high-pressure pulse source, online cleaning is achieved without shutting down the reactor or lowering the temperature. This transforms traditional top mechanical scraping into a bottom-directed jet, eliminating the interference and jamming risks caused by mechanical scrapers moving between high-temperature, dense air caps, and solving the problems of flow deviation and localized overheating caused by pore blockage.

Description

Technical Field

[0001] This invention relates to the field of chemical reaction equipment technology, specifically to a formaldehyde oxidation reactor that facilitates the cleaning of the airflow distribution plate. Background Technology

[0002] Fluidized bed reactors are widely used in gas-solid phase catalytic reactions such as formaldehyde oxidation. A gas distribution plate is typically installed horizontally between the inlet chamber at the bottom of the fluidized bed reactor and the catalyst bed above. This plate is densely packed with gas guide pipes (i.e., air caps) with caps. Its core function is to uniformly distribute the mixed reaction gas (such as methanol vapor and air) upwards, ensuring the catalyst powder above is in a uniformly suspended fluidized state, thus guaranteeing sufficient mass and heat transfer. Existing gas distribution plates, such as the gas distributor and organosilicon fluidized bed disclosed in Chinese Patent Publication No. CN207012954U, passively prevent catalyst powder from flowing back into the gas pipes during equipment shutdowns or gas pressure fluctuations by using an air cap structure and relying on the umbrella-shaped cap top. This passive anti-clogging design can maintain basic operation under normal low-temperature or simple powder conditions. However, under the specific extreme conditions of formaldehyde oxidation, a violently exothermic reaction (typically between 300°C and 600°C), tar-like polymers and other byproducts are readily generated. These sticky byproducts, mixed with fine catalyst dust, adhere like cement to the front of the airflow distribution plate and the air outlet gaps of the hood under the combined effects of gravity and high-temperature baking. Existing hood structures can only prevent backflow and offer no resistance or self-cleaning ability against this actively generated adhesive carbon deposit. Once the hood gaps are largely sealed, the gas distribution becomes severely unbalanced, resulting in channeling. The catalyst above the blocked area will sink to the bottom due to its inability to fluidize, leading to localized heat loss and potentially causing extremely dangerous temperature increases or even explosions. Because the front of the airflow distribution plate is covered with dense hoods, any conventional mechanical scraper cannot penetrate them and is prone to thermal expansion and jamming. Therefore, to clear these blockages, chemical plants currently have to completely shut down the furnace, cool down the tanks, open the tanks, and manually crawl inside for arduous physical removal. This not only poses significant safety hazards but also causes huge economic losses due to production stoppages. Summary of the Invention

[0003] To address the aforementioned issues, a formaldehyde oxidation reactor that facilitates the cleaning of the airflow distribution plate is provided. By installing a sliding gas collection hood inside the air inlet chamber and cooperating with an external high-pressure pulse source, online cleaning is achieved without stopping the machine or cooling down. This transforms the traditional top mechanical scraping into a bottom-directed jet, eliminating the interference and jamming risks caused by mechanical scrapers moving through high-temperature, dense air caps, and solving the problems of flow deviation and localized overheating caused by pore blockage.

[0004] To address the problems of existing technologies, this invention provides a formaldehyde oxidation reactor with an easily cleanable airflow distribution plate, comprising a reactor body and an air inlet chamber disposed at its bottom; further comprising: an airflow distribution plate horizontally disposed above the air inlet chamber, wherein multiple air guide pipes with wind caps are distributed on the airflow distribution plate; a cleaning system comprising a gas collecting hood disposed within the air inlet chamber, a gas supply mechanism for driving the gas collecting hood to rotate around the axis of the reactor body while adhering to the bottom surface of the airflow distribution plate, and a high-pressure pulse source located outside the reactor body; wherein, the top surface of the gas collecting hood is provided with an opening and slides against the bottom surface of the airflow distribution plate to isolate the bottom of the air guide pipes within its coverage area from the air inlet chamber; the high-pressure pulse source delivers instantaneous high-pressure gas into the gas collecting hood through the gas supply mechanism, causing the high-pressure gas to be ejected from the covered air guide pipes and, under the guidance of the wind caps, transformed into a transverse cleaning airflow adhering to the front surface of the airflow distribution plate.

[0005] Preferably, the gas conveying mechanism includes a hollow rotating shaft vertically inserted through the bottom of the reactor body; a connecting pipe is provided on the side wall of the rotating shaft, one end of the connecting pipe is inserted into and communicates with the inner cavity of the gas collecting hood; a driving component for driving the rotation is also provided at the bottom of the rotating shaft.

[0006] Preferably, the rotating shaft includes a fixed tube and a sliding tube sleeved above the fixed tube. The sliding tube and the fixed tube are sleeved together and can slide relative to each other axially. A limiting structure for synchronous rotation torque is provided between the two.

[0007] Preferably, an elastic element is provided between the fixed tube and the sliding tube. The elastic element always applies an upward preload to the sliding tube to drive the top opening of the gas collecting hood to press against the bottom surface of the airflow distribution plate.

[0008] Preferably, the opening edge of the gas collecting hood is provided with an upwardly protruding limiting member, which abuts against the bottom surface of the airflow distribution plate, so that a constant small leakage gap is maintained between the edge of the gas collecting hood and the bottom surface of the airflow distribution plate.

[0009] Preferably, the bottom of the rotating shaft is connected to a dual gas source switching valve. One end of the dual gas source switching valve is connected to a conventional reaction gas source, and the other end is connected to the high-pressure pulse source, so as to provide conventional reaction gas that is balanced with the pressure of the inlet chamber to the gas collection hood in a non-purge state.

[0010] Preferably, the air collection hood is a long strip-shaped structure extending along the radial direction of the airflow distribution plate, with its top surface having the same inclination as the bottom surface of the airflow distribution plate, and its length extending to cover the innermost to outermost ring of the air guide pipes distributed on the airflow distribution plate.

[0011] Preferably, a lateral air outlet gap is formed between the top of the wind cap and the air guide pipe, and the air outlet gap is inclined downward to guide the instantaneous high-pressure gas to impact the front surface of the airflow distribution plate.

[0012] Preferably, the cleaning system further includes a controller and a differential pressure sensor. The differential pressure sensor is used to monitor the pressure drop across the airflow distribution plate. The controller is configured to control the air delivery mechanism to drive the air collection hood to rotate in a step-by-step manner when the pressure drop exceeds a preset threshold, and to control the dual air source switching valve to turn on the high-pressure pulse source at each step stop position.

[0013] Preferably, a support shaft for stabilizing the rotating shaft is provided at the bottom center of the airflow distribution plate, the top end of the rotating shaft is sleeved on the outside of the support shaft and rotates with it, and a rotary joint is connected to the bottom end of the rotating shaft.

[0014] The advantages of this invention compared to the prior art are: 1. This invention achieves online cleaning without shutting down the machine or cooling down by installing a sliding gas collection hood inside the air intake chamber and cooperating with an external high-pressure pulse source. It transforms traditional top-mounted mechanical scraping into a bottom-mounted, deflected jet. High-pressure gas is instantly injected from the bottom into the air guide pipe isolated by the gas collection hood, and after impacting the air cap, it is forced to change direction, transforming into a high-speed lateral airflow that conforms to the front of the airflow distribution plate. This purely hydrodynamic cleaning method completely eliminates the interference and jamming risks caused by mechanical scrapers moving between high-temperature, dense air caps, removes stubborn carbon deposits in dead corners, and fundamentally solves the problems of flow deviation and localized overheating caused by blocked air vents.

[0015] 2. This invention integrates the mechanical transmission shaft and the high-pressure pulsed gas delivery channel into a single gas delivery mechanism using a hollow rotating shaft and a lateral connecting pipe. This structure simplifies the number of openings at the bottom of the reactor and reduces internal space occupation, avoiding the need for complex independent gas pipes and transmission shaft systems on a bottom shell filled with high temperature, high pressure, and flammable gas mixture. It effectively reduces the risk of leakage from dynamic and static seals and the difficulty of equipment assembly and maintenance, providing a highly reliable hardware foundation for efficient bottom isolation and reverse jet execution. Attached Figure Description

[0016] Figure 1 This is a three-dimensional top view of a formaldehyde oxidation reactor that facilitates the cleaning of the airflow distribution plate.

[0017] Figure 2 This is a three-dimensional bottom view of a formaldehyde oxidation reactor that facilitates the cleaning of the airflow distribution plate.

[0018] Figure 3 yes Figure 2 Enlarged view of point A in the middle.

[0019] Figure 4 This is a three-dimensional structural diagram of the air inlet chamber and airflow distribution plate in a formaldehyde oxidation reactor that facilitates cleaning of the airflow distribution plate.

[0020] Figure 5 This is a schematic cross-sectional view of a formaldehyde oxidation reactor that facilitates the cleaning of the airflow distribution plate.

[0021] Figure 6 yes Figure 5 Enlarged view of point B in the middle.

[0022] Figure 7 This is a schematic diagram of a three-dimensional cross-sectional structure of a formaldehyde oxidation reactor that facilitates the cleaning of the airflow distribution plate.

[0023] Figure 8 yes Figure 7 A magnified view of point C in the middle.

[0024] Figure 9 This is a schematic cross-sectional view of a portion of the gas collection hood and rotating shaft in a formaldehyde oxidation reactor designed for easy cleaning of the airflow distribution plate.

[0025] Figure 10 yes Figure 9 Enlarged view of point D in the middle.

[0026] Figure 11 This is a three-dimensional structural diagram of the rotating shaft in a formaldehyde oxidation reactor that facilitates the cleaning of the airflow distribution plate.

[0027] The following components are labeled in the diagram: 1. Reactor body; 11. Inlet chamber; 12. Airflow distribution plate; 121. Air guide pipe; 1211. Air cap; 122. Support shaft; 13. Cleaning system; 131. Gas collection hood; 1311. Opening; 1312. Limiting component; 132. Gas delivery mechanism; 1321. Rotating shaft; 13211. Connecting pipe; 13212. Fixed pipe; 13213. Sliding pipe; 13214. Elastic component; 13215. Dual gas source switching valve; 13216. Differential pressure sensor; 13217. Rotary joint; 1322. Drive assembly. Detailed Implementation

[0028] To further understand the features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0029] like Figures 1 to 7As shown: A formaldehyde oxidation reactor with an easy-to-clean airflow distribution plate includes a reactor body 1 and an air inlet chamber 11 disposed at its bottom; it also includes: an airflow distribution plate 12, horizontally disposed above the air inlet chamber 11, with multiple air guide pipes 121 equipped with air caps 1211 distributed on the airflow distribution plate 12; a cleaning system 13, including a gas collecting hood 131 disposed in the air inlet chamber 11, a gas conveying mechanism 132 that drives the gas collecting hood 131 to rotate around the axis of the reactor body 1 while adhering to the bottom surface of the airflow distribution plate 12; and a cleaning system 13 located at the reactor body 1. A high-pressure pulse source is located outside the main body 1; wherein, the top surface of the gas collecting hood 131 is provided with an opening 1311 and slides against the bottom surface of the airflow distribution plate 12 to isolate the bottom of the air guide pipe 121 within its coverage area from the air inlet chamber 11; the high-pressure pulse source delivers instantaneous high-pressure gas into the gas collecting hood 131 through the gas delivery mechanism 132, so that the high-pressure gas is ejected from the covered air guide pipe 121 and transformed into a transverse sweeping airflow that adheres to the front of the airflow distribution plate 12 under the guidance of the wind cap 1211.

[0030] In the routine operation of a formaldehyde oxidation reactor, the mixed reaction gas is typically conveyed smoothly upwards from the bottom inlet chamber 11, passes through numerous gas guide pipes 121 on the airflow distribution plate 12, and is dispersed by the air caps 1211, ensuring a uniform fluidization or stable distribution of the catalyst bed above. However, under the intense exothermic reaction conditions reaching hundreds of degrees Celsius, catalyst dust and debris, as well as reaction byproducts such as polymers and carbon deposits, are easily deposited and adhered to the front of the airflow distribution plate 12 and the gaps in the air caps 1211 under the combined effects of gravity and high-temperature baking. Over time, this adhesion leads to large-area pore blockage, causing uneven airflow distribution (channeling) and even localized temperature rise. Traditional treatment methods often require shutdown for cooling and manual slag removal, resulting in significant production waste and safety hazards. To fundamentally solve this problem, this invention, without shutting down the system, allows the gas collecting hood 131, located within the air intake chamber 11, to slide against the bottom surface of the airflow distribution plate 12, driven by the gas delivery mechanism 132. The opening 1311 on the top surface of the gas collecting hood 131 covers the bottom opening 1311 of the gas guide pipe 121 within its current coverage area, thus physically isolating it from the mainstream gas environment within the air intake chamber 11. At this time, a high-pressure pulse source located outside the reactor body 1 injects extremely high-pressure gas into the gas collecting hood 131 instantaneously through the gas delivery mechanism 132. This instantaneously high-pressure gas has nowhere to go but violently erupts upwards along the isolated gas guide pipe 121. When this airflow bursts out of the top of the gas guide pipe 121 and impacts the inner wall of the wind cap 1211, the originally vertically upward airflow is forced to undergo a significant change in direction due to the geometric guidance of the wind cap 1211, instantly transforming into a high-speed sweeping airflow that tightly adheres to the front of the airflow distribution plate 12 and sweeps laterally. The lateral shear force of the airflow generated in this way can powerfully peel off the stubborn carbon deposits and dust adhering to the metal surface and blow them into the main airflow above in a purely hydrodynamic manner, achieving thorough cleaning of complex blind areas without adding any upper mechanical scrapers (to avoid jamming of upper mechanical parts or causing secondary deposition).

[0031] like Figures 2 to 9 As shown: The gas conveying mechanism 132 includes a hollow rotating shaft 1321 that is vertically inserted through the bottom of the reactor body 1; a connecting pipe 13211 is provided on the side wall of the rotating shaft 1321, one end of the connecting pipe 13211 is inserted into the inner cavity of the gas collecting hood 131 and communicates with it; a driving assembly 1322 for driving the rotating shaft 1321 to rotate is also provided at the bottom of the rotating shaft 1321.

[0032] To achieve a simplified integration of power transmission and gas delivery, and to avoid opening too many sealing holes in the high-temperature, high-pressure reactor body, the gas delivery mechanism 132 employs a hollow rotating shaft 1321 vertically inserted into the bottom of the reactor body 1. This rotating shaft 1321 not only serves as a framework to bear mechanical torque, but its internal cavity directly constitutes a high-pressure gas delivery channel. The top of the rotating shaft 1321 is sealed, and the gas is directly inserted laterally into and connected to the inner cavity of the gas collection hood 131 through a connecting pipe 13211 provided on the side wall, forming a closed gas path directly reaching the target area. The bottom of the rotating shaft 1321 is equipped with a drive assembly 1322 to drive its rotation. In specific implementations, this drive assembly 1322 can be a stepper motor with a planetary reducer, a servo motor gear transmission group, or a high-torque pneumatic rotary cylinder, etc. The drive assembly 1322 outputs a stable low-speed, high-torque output under normal external temperature conditions, precisely controlling the spatial sweep position of the gas collection hood 131 within the high-temperature inlet chamber 11 through the rotating shaft 1321.

[0033] like Figures 4 to 11 As shown: The rotating shaft 1321 includes a fixed tube 13212 and a sliding tube 13213 sleeved on the fixed tube 13212. The sliding tube 13213 and the fixed tube 13212 are sleeved together and can slide relative to each other axially. A limiting structure for synchronous rotation torque is provided between the two (not shown in the figure).

[0034] Considering the drastic temperature fluctuations of several hundred degrees Celsius inside the reactor, large metal components will experience significant thermal expansion and contraction. If the gas collection hood 131 and the airflow distribution plate 12 were to have an absolutely rigid contact, severe friction or even mechanical jamming could easily occur during thermal expansion or when obstructed by foreign objects. Therefore, the rotating shaft 1321 is cleverly structurally divided into a fixed tube 13212 and a sliding tube 13213 fitted above it. The sliding tube 13213 and the fixed tube 13212 are interlocked and can slide relative to each other axially. Simultaneously, a limiting structure for synchronous rotational torque is provided between them. This limiting structure can specifically adopt a spline and spline groove fit, a guide key, or a polygonal irregular tube insertion form. This electromechanical logic ensures that the rotational power output by the motor at the bottom can be transmitted to the gas collection hood 131 without loss, while also giving the gas collection hood 131 a breathing space to float freely axially.

[0035] like Figures 4 to 11 As shown: An elastic element 13214 is provided between the fixed tube 13212 and the sliding tube 13213. The elastic element 13214 always applies an upward preload to the sliding tube 13213 to drive the top opening 1311 of the air collecting hood 131 to press against the bottom surface of the airflow distribution plate 12.

[0036] Furthermore, an elastic element 13214 is added between the fixed tube 13212 and the sliding tube 13213. This elastic element 13214 can be a high-temperature resistant helical compression spring, a disc spring assembly, or a metal bellows fitting. The elastic element 13214 always applies an upward preload to the sliding tube 13213. Its underlying mechanical purpose is to resist the weight of the gas collecting hood 131 itself and the huge reverse aerodynamic downward thrust generated when high-pressure pulse gas is introduced, thereby driving the top opening 1311 of the gas collecting hood 131 to always press against the bottom surface of the airflow distribution plate 12, preventing large-area leakage of high-pressure gas from the bottom and causing cleaning failure. However, in order to avoid the endless upward thrust of the spring causing destructive metal dry friction between the edge of the gas collecting hood 131 and the bottom surface of the airflow distribution plate 12, the edge of the opening 1311 of the gas collecting hood 131 is further provided with an upwardly protruding limiting element 1312. The limiting component 1312 can specifically be a silicon carbide wear-resistant slider, a high-temperature graphite lubricating pad, or a high-temperature resistant ceramic ball. These limiting components 1312 first abut against the bottom surface of the airflow distribution plate 12, so that the edge of the gas collecting hood 131 and the bottom surface of the airflow distribution plate 12 are rigidly padded and a constant micro-leakage gap is maintained. Based on the principle of fluid resistance optimization, in the extremely short pulse burst moment, it is difficult for high-pressure gas to escape in large quantities from this extremely narrow and highly resistant micro-gap, and most of the airflow will still be forced into the air guide pipe 121; the existence of this micro-gap completely eliminates the hard frictional resistance when the gas collecting hood 131 slides, realizing a true dynamic non-destructive seal, which is the guarantee for the long-term survival of the entire mechanism under extreme working conditions.

[0037] like Figures 5 to 10 As shown: The opening 1311 of the air collection hood 131 is provided with an upwardly protruding limiting member 1312. The limiting member 1312 abuts against the bottom surface of the airflow distribution plate 12, so that a constant small air leakage gap is maintained between the edge of the air collection hood 131 and the bottom surface of the airflow distribution plate 12.

[0038] If the gas collecting hood 131 is only connected to a high-pressure pulse gas source, in a non-purge state, i.e., when the gas collecting hood 131 is stationary in a certain area, the portion of the gas guide pipe 121 covered by it will lack upward airflow support, leading to localized sedimentation of the catalyst above it, dead bed formation, or accumulation of reaction heat. To maintain the overall airflow balance of the fluidized bed, a dual gas source switching valve 13215 is connected to the bottom of the rotating shaft 1321. This dual gas source switching valve 13215 can specifically be a pneumatic three-way switching valve, an electric L-type ball valve, or a dual-way solenoid combination valve, with one end connected to a conventional reaction gas source and the other end connected to a high-pressure pulse source. In non-purge mode, the valve automatically switches to the conventional reaction gas source, continuously supplying conventional reaction gas to the gas collection hood 131 with pressure balanced with the inlet chamber 11, so that the fluidization behavior of this area is no different from the surrounding area; only when the purge command is received, the valve quickly switches to the high-pressure pulse source for a few seconds of explosive purging, and then immediately resets, thus perfectly compensating for the process blind spot caused by mechanical coverage through fluid regulation logic.

[0039] like Figures 2 to 6 As shown: The bottom of the rotating shaft 1321 is connected to a dual gas source switching valve 13215. One end of the dual gas source switching valve 13215 is connected to a conventional reaction gas source, and the other end is connected to the high-pressure pulse source, so as to provide conventional reaction gas that is pressure-balanced with the air inlet chamber 11 to the gas collection hood 131 in a non-purge state.

[0040] like Figures 4 to 9 As shown: The air collection hood 131 is a long strip-shaped structure extending along the radial direction of the airflow distribution plate 12. Its top surface has the same inclination as the bottom surface of the airflow distribution plate 12, and its length extends to cover the innermost to the outermost ring of the air guide pipes 121 distributed on the airflow distribution plate 12.

[0041] A lateral air outlet gap is formed between the top of the wind cap 1211 and the top of the air guide pipe 121. The air outlet gap is inclined downward to guide the instantaneous high-pressure gas downward to impact the front surface of the airflow distribution plate 12.

[0042] To improve the coverage efficiency of a single cleaning cycle and adapt to the fluid distribution model, the gas collection hood 131 is designed as a long strip extending along the radial direction of the airflow distribution plate 12, and its top surface has the same inclination as the bottom surface of the airflow distribution plate 12, ensuring full-fit rotation during rotation. Its length extends to cover the innermost to outermost rings of the air guide pipes 121 distributed on the airflow distribution plate 12, like radar scanning lines, achieving full coverage cleaning of the reactor body 1 cross section with one rotation. Based on this, the jet angle of the pneumatic broom has been deeply optimized by hydrodynamics, and the lateral air outlet gap formed between the top of the wind cap 1211 and the air guide pipe 121 is inclined downwards. Compared to horizontal jets, the downward tilt design gives the high-speed airflow a vertical component pointing towards the plate surface, just like a high-pressure water gun sweeping the ground at an angle. It can more violently cut into the bottom of the carbon deposit layer and scoop it up, greatly enhancing the physical impact and peeling effect on the front surface of the airflow distribution plate 12. Even without this tilt angle, horizontal airflow can achieve basic cleaning, but the introduction of this angle significantly shortens the pulse duration and reduces the energy consumption of the air source.

[0043] like Figures 1 to 3 As shown: The cleaning system 13 also includes a controller and a differential pressure sensor 13216. The differential pressure sensor 13216 is used to monitor the pressure drop across the airflow distribution plate 12. The controller is configured to control the air delivery mechanism 132 to drive the air collection hood 131 to rotate in a step-by-step manner when the pressure drop exceeds a preset threshold, and to control the dual air source switching valve 13215 to turn on the high-pressure pulse source at each step stop position.

[0044] like Figures 4 to 8 As shown: The bottom center of the airflow distribution plate 12 is provided with a support shaft 122 for stabilizing the rotating shaft 1321. The top end of the rotating shaft 1321 is sleeved on the outside of the support shaft 122 and rotates with it. The bottom end of the rotating shaft 1321 is connected to a rotary joint 13217.

[0045] The operation of the entire system relies heavily on precise automatic closed-loop control. Therefore, the cleaning system 13 is equipped with a controller (not shown in the figure), such as a PLC programmable logic controller, a DCS distributed control system, or a microcontroller. It also includes differential pressure sensors 13216, such as dual-flange differential pressure transmitters or diaphragm micro-differential pressure gauges. The differential pressure sensor 13216 monitors the gas pressure drop at both ends of the airflow distribution plate 12 in real time. When the pressure drop exceeds a preset threshold, indicating that the blockage is affecting normal processes, the controller automatically triggers intervention. Instead of using the inefficient continuous rotation and blowing mode, it controls the gas delivery mechanism 132 to rotate the gas collection hood 131 in steps, such as 15 degrees at a time. At each step stop position, the gas collection hood 131 locks the current area, and the controller then instructs the dual gas source switching valve 13215 to activate the high-pressure pulse source for targeted blasting. By using the above-described sequence of actions, the instantaneous gas pressure energy can be concentrated to an extreme within a small sector, maximizing the cleaning force and avoiding the catastrophic disturbance to the pressure system of the entire reactor body 1 caused by continuous large-area backflushing. Finally, to address the swaying and vibration of the slender rotating shaft 1321 under cantilevered stress caused by the reaction force of the high-pressure gas jet, a support shaft 122 for stabilizing the rotating shaft 1321 is specially provided at the bottom center of the airflow distribution plate 12. The top end of the rotating shaft 1321 is fitted onto the outside of the support shaft 122 and rotates with it, which is equivalent to adding a solid journal fulcrum at the end of the stressed area; together with the rotary joint 13217 connected at its bottom end, a robust shaft system with double supports at both ends is constructed, completely eliminating mechanical resonance and sealing failure.

[0046] It should be further explained that the high-pressure gas provided by the high-pressure pulse source is preferably a conventional reaction gas or an inert auxiliary gas (such as nitrogen) that has been pressurized twice, to ensure that no impurities that would disrupt the formaldehyde oxidation reaction system are introduced during jet purging. Simultaneously, because the high-pressure pulse gas is injected in an extremely short pulse pattern on the order of milliseconds to seconds, and the coverage area of ​​the gas collecting hood 131 in a single step is only a small portion of the total area of ​​the airflow distribution plate 12, this localized, instantaneous, high-speed transverse airflow, upon entering the catalyst bed with its large buffer volume above, will have its kinetic energy rapidly buffered, absorbed, and homogenized by the thick and turbulent catalyst particle group, thus smoothly integrating into the mainstream upward reaction airflow, without disrupting the dynamic balance of the global fluidization distribution within the entire reactor body 1.

[0047] Under the high shear force and jet impact of the transverse sweeping airflow, large chunks of cohesive carbon deposits are physically broken down and pulverized into tiny suspended particles the instant they detach from the surface of the airflow distribution plate 12. The apparent density of these carbon particles and organic polymer fragments is much lower than that of heavy metal catalyst powder. According to the principle of separation in the fluidized bed system, these pulverized and detached lightweight carbon particles cannot resist the upward drag force of the mainstream gas and will not redeposit in other corners of the reactor. Instead, they will be irreversibly lifted by the mainstream gas and carried into the upper mainstreamed catalyst bed. Furthermore, because the formaldehyde oxidation reactor operates under a high-temperature, oxygen-rich environment of 300°C to 600°C, the tiny organic carbon particles blown into the fluidized bed will rapidly undergo in-situ secondary oxidation and combustion reactions when they violently tumble and contact the high-temperature catalyst, directly converting into gaseous products such as carbon dioxide and being discharged from the reactor with the main airflow. Therefore, the stripped carbon particles will not remain and cause secondary blockage of the catalyst bed, nor will they adhere or sinter with the catalyst at low temperatures. Instead, they will be completely vaporized and removed through the system's own high-temperature oxygen-enriched digestion mechanism, thus achieving substantial self-cleaning for long-term operation of the fluidized bed in a closed loop.

[0048] The above embodiments only illustrate one or more implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the appended claims.

Claims

1. A formaldehyde oxidation reactor facilitating cleaning of the gas flow distribution plate, comprising a reactor main body and a gas inlet cavity arranged at the bottom of the reactor main body; characterized in that, Also includes: An airflow distribution plate is horizontally positioned above the air intake chamber, and multiple air guide pipes with wind caps are distributed on the airflow distribution plate; The cleaning system includes a gas collection hood disposed in the air inlet chamber, a gas delivery mechanism that drives the gas collection hood to rotate around the axis of the reactor body while adhering to the bottom surface of the airflow distribution plate, and a high-pressure pulse source located outside the reactor body. The top surface of the gas collection hood is provided with an opening and slides against the bottom surface of the airflow distribution plate to isolate the bottom of the air guide pipe within its coverage area from the air intake chamber. The high-pressure pulse source delivers instantaneous high-pressure gas into the gas collection hood through the gas delivery mechanism, causing the high-pressure gas to be ejected from the covered air guide pipe and transformed into a lateral sweeping airflow that fits the front of the airflow distribution plate under the guidance of the wind cap.

2. A formaldehyde oxidation reactor with a gas flow distribution plate that is easy to clean according to claim 1, characterized in that The gas conveying mechanism includes a hollow rotating shaft that is vertically inserted through the bottom of the reactor body; a connecting pipe is provided on the side wall of the rotating shaft, one end of which is inserted into and connected to the inner cavity of the gas collecting hood; a driving component for driving the rotating shaft to rotate is also provided at the bottom of the rotating shaft.

3. A formaldehyde oxidation reactor with a gas flow distribution plate that is easy to clean according to claim 2, characterized in that The rotating shaft includes a fixed tube and a sliding tube sleeved above the fixed tube. The sliding tube and the fixed tube are sleeved together and can slide relative to each other axially. A limiting structure for synchronous rotation torque is provided between the two.

4. A formaldehyde oxidation reactor with an easily cleanable airflow distribution plate according to claim 3, characterized in that, An elastic element is provided between the fixed tube and the sliding tube. The elastic element always applies an upward preload to the sliding tube to drive the top opening of the gas collection hood to press against the bottom surface of the airflow distribution plate.

5. A formaldehyde oxidation reactor with an easily cleanable airflow distribution plate according to claim 4, characterized in that, The opening edge of the gas collecting hood is provided with an upwardly protruding limiting member, which abuts against the bottom surface of the airflow distribution plate, so that a constant small air leakage gap is maintained between the edge of the gas collecting hood and the bottom surface of the airflow distribution plate.

6. A formaldehyde oxidation reactor with an easily cleanable airflow distribution plate according to claim 2, characterized in that, The bottom of the rotating shaft is connected to a dual gas source switching valve. One end of the dual gas source switching valve is connected to a conventional reaction gas source, and the other end is connected to the high-pressure pulse source, so as to provide conventional reaction gas that is balanced with the pressure of the inlet chamber to the gas collection hood in a non-purge state.

7. A formaldehyde oxidation reactor with an easily cleanable airflow distribution plate according to claim 1, characterized in that, The gas collection hood is a long strip-shaped structure extending along the radial direction of the airflow distribution plate. Its top surface has the same inclination as the bottom surface of the airflow distribution plate, and its length extends to cover the innermost to the outermost ring of the air guide pipes distributed on the airflow distribution plate.

8. A formaldehyde oxidation reactor with an easily cleanable airflow distribution plate according to claim 1, characterized in that, A lateral air outlet gap is formed between the top of the wind cap and the air guide pipe. The air outlet gap is inclined downward to guide the instantaneous high-pressure gas downward to impact the front surface of the airflow distribution plate.

9. A formaldehyde oxidation reactor with an easily cleanable airflow distribution plate according to claim 6, characterized in that, The cleaning system also includes a controller and a differential pressure sensor. The differential pressure sensor is used to monitor the pressure drop across the airflow distribution plate. The controller is configured to control the air delivery mechanism to drive the air collection hood to rotate in a step-by-step manner when the pressure drop exceeds a preset threshold, and to control the dual air source switching valve to turn on the high-pressure pulse source at each step stop position.

10. A formaldehyde oxidation reactor with an easily cleanable airflow distribution plate according to claim 2, characterized in that, The bottom center of the airflow distribution plate is provided with a support shaft for stabilizing the rotating shaft. The top end of the rotating shaft is sleeved on the outside of the support shaft and rotates with it. The bottom end of the rotating shaft is connected to a rotary joint.

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