Fluidized bed reactor for hydrocyanic acid production
By adopting an independent dense-phase reaction zone and a dilute-phase settling zone design in the hydrocyanic acid fluidized bed reactor, combined with staggered air distribution plates and guide caps, setting up independent heat removal components, and optimizing the feed gas inlet distributor and cyclone separator, the problems of uneven catalyst fluidization, local hot spots, and low heat removal efficiency were solved, and stable operation and high-efficiency production of the equipment were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI ZHIYING CHEM TECH CO LTD
- Filing Date
- 2026-04-03
- Publication Date
- 2026-07-21
AI Technical Summary
Existing fluidized bed reactors for hydrogen cyanide suffer from problems such as uneven catalyst fluidization, local hot spots, low heat removal efficiency, and large equipment vibrations, which affect the stability and efficiency of the reactor.
The design employs independent dense-phase reaction zone and dilute-phase settling zone, combined with staggered air distribution plates, flow guide caps and guide plates, and independent heat removal components, including cooling water pipes and heat transfer fins. The structure of the feed gas inlet distributor and cyclone separator is optimized to enhance the uniform fluidization and heat removal effect of the catalyst.
It improves the uniform fluidization effect of the catalyst, avoids catalyst accumulation, enhances the stable operation of the equipment, improves reaction efficiency and selectivity, and reduces the risk of catalyst deactivation.
Smart Images
Figure CN121944930B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of hydrogen cyanide production equipment, and relates to a fluidized bed reactor for hydrogen cyanide production. Background Technology
[0002] The hydrogen cyanide reactor is a vertical, skirt-supported, self-supporting fluidized bed reactor with large geometric dimensions and a complex structure. It is equipped with a gas collection chamber at the top and multiple sets of cyclone separators, a hot water pipe system, a methanol-ammonia distributor, an air distribution plate, and other components inside. This technology uses methanol, ammonia, and air as raw materials to produce hydrogen cyanide through a reaction in the presence of a catalyst, while releasing a large amount of heat.
[0003] In the methanol-to-hydrogen cyanide process via ammoxidation, the uniformity of the fluidized bed reactor is one of the core engineering challenges hindering its technological maturity and commercialization. Specifically, this manifests in the following technical difficulties:
[0004] 1. The raw materials are methanol (vapor), ammonia and air. The three have large differences in density and viscosity, making it more difficult to achieve initial uniform mixing and distribution at the distribution plate, which can easily lead to local deviations of the bed composition from the optimal ratio.
[0005] 2. The density, morphology, and wear resistance of the catalyst particles used are different from those of precious metal catalysts. Special considerations are needed when designing fluidization conditions, as particle agglomeration, breakage, or segregation are more likely to occur, exacerbating fluidization inhomogeneity.
[0006] 3. The reaction is highly exothermic, and uneven fluidization can lead to the formation of "hot spots" and "cold zones" in the bed. "Hot spots" can accelerate catalyst sintering and deactivation and may trigger side reactions such as deep oxidation of methanol; "cold zones" can lead to incomplete reaction.
[0007] For example, the fluidized bed reactor for producing hydrogen cyanide provided in Chinese patent application CN119926305A achieves uniform mixing of air and ammonia / propylene (methanol) by precisely designing the structure and relative position of the air distributor and the ammonia / propylene (methanol) mixed gas distributor, and controls the contact time between air and ammonia / propylene (methanol) to be less than 0.3 seconds at the feed concentration, thus eliminating the risk of explosion; at the same time, it increases the diameter of the settling section, reduces the linear velocity of the settling section, and improves the settling efficiency of the catalyst. Analysis revealed that while the patent reduces the risk of explosion by controlling contact time, it fails to effectively address the initial uneven mixing problem caused by the significant differences in the physical properties (density, viscosity) of air, methanol, and ammonia. This directly results in the difficulty of forming a uniform fluidization field at the bottom of the reactor, and the unevenness of the bed remains, creating potential hazards for the formation of "hot spots" and "cold zones." Simultaneously, the distribution pipes are prone to clogging, catalyst fall is obstructed, bed height and density fluctuate greatly, and reaction stability is poor. Furthermore, the large radial / axial temperature difference in the reactor bed leads to a rapid methanol-ammonia oxidation reaction rate and concentrated heat release. The more inlet points there are, the more intense the local reaction becomes, and the heat transfer rate is difficult to match the reaction rate, easily forming local hot spots, triggering catalyst sintering and a surge in side reactions. Summary of the Invention
[0008] The purpose of this invention is to provide a fluidized bed reactor for the production of hydrogen cyanide, which can effectively improve the uniform fluidization effect of the catalyst, avoid catalyst accumulation, and enhance the stable operation of the equipment. It can systematically solve at least one of the engineering problems mentioned above, such as uneven fluidization, local hot spots, low heat removal efficiency, and large equipment vibration.
[0009] The objective of this invention can be achieved through the following technical solutions:
[0010] A fluidized bed reactor for the production of hydrogen cyanide, comprising:
[0011] The reactor shell includes, from bottom to top, an air equalization chamber, a dense phase reaction zone, and a dilute phase sedimentation zone;
[0012] An air inlet distributor includes an air distribution plate and an air inlet pipe, wherein the air distribution plate is located between an air equalization chamber and a dense phase reaction zone, and the air inlet pipe extends into the air equalization chamber from the side;
[0013] A feed gas inlet distributor that extends into the dense phase reaction zone;
[0014] A cyclone separator assembly arranged in the dilute phase settling zone and fixedly connected to the top of the reactor shell;
[0015] And, a heat removal component disposed in the dense phase reaction zone and / or the dilute phase settling zone.
[0016] Furthermore, unlike conventional fluidized bed reactors, the dense phase reaction zone and the dilute phase settling zone are each equipped with independent heat removal components. Here, the heat removal components can be cooling water coils, etc.
[0017] Furthermore, the heat dissipation component includes a cooling water pipe and one or more sets of heat transfer components disposed on the outer wall of the cooling water pipe. Each set of heat transfer components includes multiple corrugated heat transfer fins distributed along the circumference of the cooling main pipe. When multiple sets of heat transfer components are provided, adjacent sets of heat transfer components are staggered in the circumference of the cooling main pipe to form a cross-turbulence structure.
[0018] Furthermore, the air distribution plate includes a distribution plate body, air distribution pipes arranged in an array and vertically fixed on the distribution plate body, and guide caps fixed on the distribution plate body and correspondingly disposed above the air distribution pipes. The guide caps and the distribution plate body form a horizontally penetrating air guiding cavity with open ends. Any two adjacent guide caps along the horizontal transverse or longitudinal direction are staggered at 90°.
[0019] Furthermore, the inner and outer surfaces of the flow guide cap along the air guide cavity are both inclined slopes, and the entire vertical cross-section is roughly triangular.
[0020] The distance between two adjacent air distribution pipes is 3.5 to 4.5 times the length of the air guide cap.
[0021] Furthermore, the outlet end of the air inlet pipe is positioned upwards and located at the center of the air equalization chamber. At the outlet end of the air inlet pipe, a guide plate with a conical umbrella-shaped surface is provided through several stiffeners, and a horizontal radial air guide is formed between adjacent stiffeners.
[0022] Furthermore, the cone angle α of the guide plate is 30~60°, and the distance H between the bottom end of the guide plate and the air distribution plate satisfies: 0.08≤H / D≤0.3, where D is the diameter of the interface between the air equalization chamber and the dense phase reaction zone.
[0023] Furthermore, the raw material gas inlet distributor includes an inlet pipe, a premixing pipe and a raw material gas distributor connected in sequence, wherein the premixing pipe is provided with a mixing auxiliary component along the axial direction to fully mix the high-temperature raw material gas;
[0024] The raw material gas distributor is equipped with downward-opening nozzles, which are used to uniformly spray the premixed high-temperature raw material gas into the dense phase reaction zone.
[0025] Furthermore, the cyclone separator assembly includes a cyclone separator, the upper part of which is connected to the top of the reactor shell via a hanger, and the lower material leg extends vertically into the dense phase reaction zone. Adjacent material legs are connected to each other, as well as the outermost material leg is connected to the side wall of the reactor shell via material leg connectors. The end of the material leg connector that connects to the side wall of the reactor shell is also provided with an elastic notch ring.
[0026] Furthermore, each material leg is connected to an adjacent material leg or the side wall of the reactor shell through at least three material leg connectors, and the included angle between any two adjacent material leg connectors connected to the same material leg does not exceed 180°.
[0027] Furthermore, the region on the reactor shell located between the dilute phase settling zone and the dense phase reaction zone adopts a variable diameter design with the diameter gradually decreasing from top to bottom.
[0028] Compared with existing technologies, this invention can effectively improve the uniform fluidization effect of the catalyst, avoid catalyst accumulation, and enhance the stable operation of the equipment by optimizing and adjusting the air inlet pipe, air distribution plate, and raw material gas inlet distributor in combination. Attached Figure Description
[0029] Figure 1 This is a schematic diagram of the structure of the fluidized bed reactor of the present invention;
[0030] Figure 2 This is a schematic diagram of the air inlet distributor.
[0031] Figure 3 This is a top view of the air distribution panel;
[0032] Figure 4 This is a schematic vertical cross-sectional view of a portion of the air distribution pipe and the air guide cap.
[0033] Figure 5 This is a schematic diagram of the air inlet pipe section;
[0034] Figure 6 This is a schematic diagram of the raw gas inlet distributor;
[0035] Figure 7 This is a schematic diagram of a partial cross-section of the premixed pipe;
[0036] Figure 8 This is a structural diagram of the material leg section;
[0037] Figure 9 This is a schematic diagram of the heat dissipation component.
[0038] Explanation of markings in the diagram:
[0039] 1-Reactor shell, 11-Air equalization chamber, 12-Dense phase reaction zone, 13-Dilute phase settling zone, 14-Heat removal assembly, 141-Cooling main pipe, 142-Heat transfer fins;
[0040] 2-Air inlet distributor, 21-Air distribution plate, 211-Distribution plate body, 212-Air distribution pipe, 213-Guide cap, 214-Air guide cavity, 22-Air inlet pipe, 221-Guide plate, 222-Firming plate;
[0041] 3-Raw gas inlet distributor, 301-Inlet pipe, 302-Premixing pipe, 303-Raw gas distributor, 304-Nozzle, 305-Mixing auxiliary component;
[0042] 4-Cyclone separator assembly, 41-Cyclone separator, 42-Hanger, 43-Material leg, 44-Material leg connector, 45-Elastic notched ring. Detailed Implementation
[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.
[0044] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0045] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0046] Unless otherwise specified, the functional components or structures in the following embodiments or examples are conventional components or structures used in the art to achieve the corresponding functions.
[0047] To effectively improve the uniform fluidization of the catalyst, avoid catalyst accumulation, and enhance the stable operation of the equipment, this invention provides a fluidized bed reactor for hydrogen cyanide production, the structure of which is described below. Figure 1 As shown, including:
[0048] The reactor shell 1 includes an air equalization chamber 11, a dense phase reaction zone 12 and a dilute phase sedimentation zone 13 arranged sequentially from bottom to top;
[0049] An air inlet distributor 2 includes an air distribution plate 21 and an air inlet pipe 22. The air distribution plate 21 is located between an air equalization chamber 11 and a dense phase reaction zone 12. The air inlet pipe 22 extends into the air equalization chamber 11 from the side.
[0050] The raw gas inlet distributor 3 extends into the dense phase reaction zone 12;
[0051] Cyclone separator assembly 4 is arranged in the dilute phase settling zone 13 and fixedly connected to the top of the reactor shell 1;
[0052] And a heat removal component disposed in the dense phase reaction zone and / or dilute phase settling zone.
[0053] For some specific implementation methods, please refer to [link / reference]. Figure 1 As shown, unlike conventional fluidized bed reactors, the dense phase reaction zone 12 and the dilute phase settling zone 13 are each equipped with independent heat dissipation components 14. Specifically, the heat dissipation component 14 includes a cooling water pipe and one or more sets of heat transfer components disposed on the outer wall of the cooling water pipe. Each set of heat transfer components includes multiple corrugated heat transfer fins 142 distributed circumferentially along the cooling main pipe 141. When multiple sets of heat transfer components are provided, adjacent sets of heat transfer components are staggered circumferentially along the cooling main pipe 141 to form a cross-turbulence structure. Meanwhile, the cooling main pipe 141 includes straight pipe sections and bent pipe sections; adjacent straight pipe sections are connected by bent pipe sections to ensure continuous flow of the cooling medium and efficient heat removal; the heat transfer components are disposed in the straight pipe sections.
[0054] Because the methanol ammonia oxidation is a strongly exothermic and rapid reaction, the reaction is intense and heat is concentrated in the dense phase region of the reactor, while secondary exothermic reactions still occur in the dilute phase region. Therefore, heat removal components are set up in the dense and dilute phase regions to match the heat distribution, precisely control the bed temperature, effectively eliminate local hot spots, and improve the selectivity and yield of hydrogen cyanide. At the same time, independent adjustment of each zone is achieved, improving operational flexibility and temperature control accuracy, avoiding problems such as catalyst deactivation and increased side reactions caused by uneven heat removal in a single zone, and ensuring stable, efficient, and long-term operation of the reactor.
[0055] Furthermore, the heat dissipation components 14 are preferably set independently in the dense phase reaction zone 12 and the dilute phase sedimentation zone 13, for the following reasons:
[0056] (1) The intensity of the exothermic reaction and the heat removal requirements are different: The dense phase reaction zone 12 is the main reaction zone, which is highly exothermic. The heat removal component needs to remove a large amount of reaction heat in time to maintain the active temperature of the catalyst and prevent the formation of "hot spots" that could lead to catalyst sintering. The dilute phase settling zone 13 has a weaker reaction, but the gas entrained catalyst particles still have a small amount of reaction and frictional heat generation here, and the outlet gas temperature needs to be controlled to meet the requirements of subsequent processes. Independent heat removal can achieve precise graded control of the temperature of the two zones.
[0057] (2) Avoid uneven heat removal affecting fluidization: If a single heat removal system is used, uneven heat removal may lead to an unstable temperature gradient in the interface between the dense and dilute phases, which may affect the fluidization state of the catalyst in that region and even cause catalyst accumulation. Independent design can ensure uniform heat removal in each zone and maintain a stable fluidized bed interface.
[0058] For some specific implementation methods, please refer to [link / reference]. Figures 2 to 4 As shown, the air distribution plate 21 includes a distribution plate body 211, air distribution pipes 212 arranged in an array and vertically fixed on the distribution plate body 211, and guide caps 213 fixed on the distribution plate body 211 and correspondingly positioned above the air distribution pipes 212. A horizontally penetrating air-guiding cavity 214 with openings at both ends is formed between the guide caps 213 and the distribution plate body 211. Any two adjacent guide caps 213 arranged horizontally or longitudinally are staggered at 90°. By setting the staggered guide caps 213, a network of interwoven and colliding horizontal scouring airflow is constructed above the distribution plate body 211. This horizontal scouring effect makes it difficult for catalyst particles to accumulate on the surface of the distribution plate body 211 and in the dead corners around the guide caps; even if a small number of particles settle, they will be dispersed and re-enter the fluidized state under the action of continuous horizontal airflow. Based on this airflow distribution structure, the catalyst accumulation defects caused by the unidirectional / uneven distribution of airflow in traditional distribution plates are effectively overcome, significantly improving the fluidization uniformity and anti-accumulation performance of the distribution plate area. In addition, for ease of processing, the guide cap 213 can be made of standard angle steel.
[0059] In a more specific embodiment, the inner and outer surfaces of the guide cap 213 along the direction of the air guide cavity 214 are both inclined slopes, and the entire vertical cross section is roughly triangular. In this way, the horizontal airflow ejected from the adjacent guide cap 213 can be swept upward along the inclined slope, generating secondary disturbance and diffusion, and it is not easy to generate dead zones.
[0060] The spacing between two adjacent air distribution pipes 212 is 3.5 to 4.5 times the length of the guide cap 213 (along the direction of the air guide cavity 214) to ensure sufficient fluidization space, ensure the interaction effect of airflow, and maximize the performance of preventing material accumulation and uniform fluidization.
[0061] During operation, when air flows out from the top of the air distribution pipe 212, it is blocked by the guide cap 213 above it, and then ejected at high speed in a horizontal direction along the gap between the guide cap 213 and the air distribution plate 21 (i.e., the air guiding cavity 214). Due to the 90° staggered arrangement of adjacent guide caps 213, specifically, if the opening direction of one guide cap 213 points to the X-axis, then the opening direction of its adjacent guide cap 213 points to either the positive or negative Y-axis. In this way, the horizontal airflow forms a mesh-like airflow field above the distribution plate body 211, where they intertwine and collide. The airflow ejected from one guide cap 213 impacts the inclined side of the adjacent guide cap 213, generating secondary disturbance and diffusion, thereby forming a uniform and strong horizontal scouring effect on the entire surface of the distribution plate body 211. This horizontal scouring effect can effectively prevent catalyst particles from accumulating on the surface of the distribution plate body 211 and in the dead corners around the guide caps 213. Even if a small amount of particles settle, they will be dispersed by the continuous horizontal airflow and re-entrained into the fluidized state, thus significantly improving the fluidization uniformity and anti-accumulation performance in the distribution plate area. At the same time, this uniform horizontal airflow distribution also ensures uniform fluidization throughout the entire bed, avoiding local overheating and channeling phenomena, and improving gas-solid contact efficiency.
[0062] For some specific implementation methods, please refer to [link / reference]. Figure 5 As shown, the outlet end of the air inlet pipe 22 is upwardly positioned and located at the center of the air equalization chamber 11. At the outlet end of the air inlet pipe 22, a guide plate 221 with a conical umbrella-shaped surface is provided via several stiffeners 222, forming a horizontal radial air guide between adjacent stiffeners 222. In a more specific embodiment, the cone angle α of the guide plate 221 is 30~60°, and the distance H between the bottom end of the guide plate 221 and the air distribution plate 21 satisfies: 0.08≤H / D≤0.3, where D is the diameter of the interface between the air equalization chamber 11 and the dense phase reaction zone 12.
[0063] In addition, depending on the actual situation, under a fixed D, the larger H is (the more room for development), the smaller the required α can be; conversely, if H is small, a larger α is needed to achieve a sufficient radial guidance effect.
[0064] This design effectively guides the incoming air to be radially and evenly dispersed from the center to the outer edge, preventing the incoming airflow from directly impacting the air distribution plate 21. This effectively achieves uniform air distribution and balances the pressure drop. In addition, the conical guide plate 221 can also reduce the accumulation and retention of catalyst particles on its upper part.
[0065] For some specific implementation methods, please refer to [link / reference]. Figure 6 and Figure 7As shown, the raw material gas inlet distributor 3 includes an inlet pipe 301, a premix pipe 302 and a raw material gas distributor 303 connected in sequence. The premix pipe 302 is provided with a mixing auxiliary component 305 along the axial direction to fully mix the high-temperature raw material gas.
[0066] The raw material gas distributor 303 is equipped with a downward-opening nozzle 304, which is used to uniformly spray the premixed high-temperature raw material gas into the dense phase reaction zone.
[0067] In the hydrogen cyanide production process, the methanol-ammonia feed distributor is constantly exposed to high temperatures. When the temperature of the mixed gas exceeds the temperature at which ammonia decomposes into active nitrogen atoms, some ammonia decomposes into active nitrogen atoms, which combine with metal atoms in the feed distributor tube to form brittle metal nitrides, causing the feed distributor to break. Therefore, this invention introduces a premixing tube 302 and a mixing auxiliary component 305 to ensure sufficient residence time and turbulence of methanol and ammonia in this space, achieving thorough premixing to form a uniform mixed gas, reducing the local ammonia concentration in the distributor area, thereby reducing the local ammonia partial pressure and the tendency of ammonia decomposition, inhibiting the generation of active nitrogen atoms from ammonia decomposition at high temperatures, reducing the formation of metal nitrides from the source, and preventing the feed distributor from breaking. Simultaneously, the built-in mixing auxiliary component of this invention can further enhance the turbulent mixing of methanol and ammonia before entering the reaction zone, significantly shortening the residence time required for molecular-level uniform mixing, thereby greatly inhibiting ammonia decomposition and subsequent nitriding corrosion reactions. The premixing tube acts as a "rapid mixing buffer," playing a crucial role in protecting the core feed distributor and extending its service life while meeting process mixing requirements.
[0068] Here, the mixing auxiliary component 305 can be selected from mixing devices such as fins according to actual needs to enhance gas mixing efficiency and improve hydrodynamic characteristics, thereby ensuring that the methanol and ammonia entering the reactor can be fully and uniformly mixed and enter the catalyst bed in an ideal flow pattern, which helps to maintain the stable fluidization state of the catalyst bed and avoid channeling or dead zones. The shape of the premixing tube 302 can be approximately inverted "L".
[0069] For some specific implementation methods, please refer to [link / reference]. Figure 1 and Figure 8As shown, the cyclone separator assembly 4 includes a cyclone separator 41. The upper part of the cyclone separator 41 is connected to the top of the reactor shell 1 via a hanger 42, and the lower material legs 43 extend vertically into the dense phase reaction zone. Adjacent material legs 43 and the outermost material leg 43 are connected to the side wall of the reactor shell 1 via material leg connectors 44. The end of the material leg connector 44 that connects to the side wall of the reactor shell 1 is also provided with an elastic notched ring 45. In a more specific embodiment, each material leg 43 is connected to an adjacent material leg 43 or the side wall of the reactor shell 1 via at least three material leg connectors 44, and the included angle between any two adjacent material leg connectors 44 connected to the same material leg 43 does not exceed 180°.
[0070] Different material legs 43 are connected as a whole by material leg connectors 44. Under the complex load of fluidized bed, stress can be effectively transferred and dispersed, avoiding structural cracking and deformation caused by local stress concentration, improving the vibration and torsional resistance of material legs 43, ensuring long-term stable alignment of material legs 43, and maintaining the material sealing function. At the same time, local vibration can be quickly dispersed to adjacent material legs 43, forming a high-rigidity bending-resistant system and suppressing the lateral sway of material legs 43 (similar to the space truss effect). In addition, an elastic notch ring 45 is set to connect with the side wall of the reactor shell 1. In this way, as a flexible interface, it can absorb energy based on the elastic deformation of its own opening, compensate for the small radial displacement of material legs 43, avoid vibration directly transmitted to the cylinder wall, reduce the fatigue damage of vibration to the material leg 43 body and connecting structure, improve the vibration resistance of material legs 43, and adapt to the dynamic load environment inside the reactor.
[0071] In some specific embodiments, the region on the reactor shell 1 located between the dilute phase settling zone 13 and the dense phase reaction zone 12 adopts a variable diameter design with the diameter gradually decreasing from top to bottom.
[0072] Each of the above implementation methods can be implemented individually, or in any combination of two or more without violating logic.
[0073] The above implementation methods will be described in more detail below with reference to specific embodiments.
[0074] Example 1:
[0075] To effectively improve the uniform fluidization of the catalyst, avoid catalyst accumulation, and enhance the stable operation of the equipment, this embodiment provides a fluidized bed reactor for hydrogen cyanide production, the structure of which is described in [reference needed]. Figure 1 As shown, including:
[0076] The reactor shell 1 includes an air equalization chamber 11, a dense phase reaction zone 12 and a dilute phase sedimentation zone 13 arranged sequentially from bottom to top;
[0077] An air inlet distributor 2 includes an air distribution plate 21 and an air inlet pipe 22. The air distribution plate 21 is located between an air equalization chamber 11 and a dense phase reaction zone 12. The air inlet pipe 22 extends into the air equalization chamber 11 from the side.
[0078] The raw gas inlet distributor 3 extends into the dense phase reaction zone 12;
[0079] Cyclone separator assembly 4 is arranged in the dilute phase settling zone 13 and fixedly connected to the top of the reactor shell 1;
[0080] And a heat removal component 14 disposed in the dense phase reaction zone and / or dilute phase settling zone.
[0081] Please see again. Figure 1 As shown, unlike conventional fluidized bed reactors, the dense phase reaction zone 12 and the dilute phase settling zone 13 are each equipped with independent heat dissipation components 14. Specifically, the heat dissipation components include cooling water pipes and one or more sets of heat transfer components disposed on the outer wall of the cooling water pipes. Each set of heat transfer components includes multiple corrugated heat transfer fins 142 distributed circumferentially along the cooling main pipe 141. When multiple sets of heat transfer components are provided, adjacent sets of heat transfer components are staggered circumferentially along the cooling main pipe 141 to form a cross-turbulence structure. Meanwhile, the cooling main pipe 141 includes straight pipe sections and bent pipe sections; adjacent straight pipe sections are connected by bent pipe sections to ensure continuous flow of the cooling medium and efficient heat removal; the heat transfer components are disposed in the straight pipe sections.
[0082] Please see again. Figures 2 to 4 As shown, the air distribution plate 21 includes a distribution plate body 211, air distribution pipes 212 arranged in an array and vertically fixed on the distribution plate body 211, and guide caps 213 fixed on the distribution plate body 211 and correspondingly positioned above the air distribution pipes 212. A horizontally penetrating air-guiding cavity 214 with openings at both ends is formed between the guide caps 213 and the distribution plate body 211. Any two adjacent guide caps 213 are arranged at a 90° angle in a staggered configuration. By setting the staggered guide caps 213, a network of interwoven and colliding airflow fields is constructed above the distribution plate body 211, effectively ensuring uniform fluidization of the entire catalyst bed, completely solving the problem of easy material accumulation in traditional distribution plates, avoiding local overheating and channeling phenomena, and improving gas-solid contact efficiency. Furthermore, for ease of processing, the guide caps 213 can be made from standard angle steel.
[0083] Meanwhile, the inner and outer surfaces of the guide cap 213 along the direction of the air guide cavity 214 are both inclined slopes, and the entire vertical cross section is roughly triangular. In this way, the horizontal airflow ejected from the adjacent guide cap 213 can be swept upward along the inclined slope, generating secondary disturbance and diffusion, and it is not easy to generate dead zones. The distance between two adjacent air distribution pipes 212 is 3.5 to 4.5 times the length of the guide cap 213 (along the direction of the air guide cavity 214) to ensure sufficient fluidization space, ensure the interaction effect of airflow, and maximize the performance of preventing material accumulation and uniform fluidization.
[0084] Based on the above design, during operation, when air flows out from the top of the air distribution pipe 212, it is blocked by the guide cap 213 above it, and then ejected at high speed in a horizontal direction along the gap between the guide cap 213 and the air distribution plate 21 (i.e., the air guiding cavity 214). Due to the 90° staggered arrangement of adjacent guide caps 213, specifically, if the opening direction of one guide cap 213 points to the X-axis direction, then the opening direction of its adjacent guide cap 213 points to the positive or negative Y-axis direction. In this way, the horizontal airflow forms a mesh-like airflow field above the distribution plate body 211, where they intertwine and collide. The airflow ejected from one guide cap 213 impacts the inclined side of the adjacent guide cap 213, generating secondary disturbance and diffusion, thereby forming a uniform and strong horizontal scouring effect on the entire surface of the distribution plate body 211. This horizontal scouring effect can effectively prevent catalyst particles from accumulating on the surface of the distribution plate body 211 and in the dead corners around the guide caps 213. Even if a small amount of particles settle, they will be dispersed by the continuous horizontal airflow and re-entrained into the fluidized state, thus completely solving the problem of easy material accumulation in traditional distribution plates. At the same time, this uniform horizontal airflow distribution also ensures uniform fluidization throughout the bed, avoiding local overheating and channeling phenomena, and improving gas-solid contact efficiency.
[0085] Please see again. Figure 5 As shown, the outlet end of the air inlet pipe 22 is upwardly positioned and located at the center of the air equalization chamber 11. At the outlet end of the air inlet pipe 22, a guide plate 221 with a conical umbrella-shaped surface is provided via several stiffeners 222, forming a horizontal radial air guide between adjacent stiffeners 222. In a more specific embodiment, the cone angle α of the guide plate 221 is 30~60°, and the distance H between the bottom end of the guide plate 221 and the air distribution plate 21 satisfies: 0.08≤H / D≤0.3, where D is the diameter of the interface between the air equalization chamber 11 and the dense phase reaction zone 12.
[0086] In addition, depending on the actual situation, under a fixed D, the larger H is (the more room for development), the smaller the required α can be; conversely, if H is small, a larger α is needed to achieve a sufficient radial guidance effect.
[0087] This design effectively guides the incoming air to be radially and evenly dispersed from the center to the outer edge, preventing the incoming airflow from directly impacting the air distribution plate 21. This effectively achieves uniform air distribution and balances the pressure drop. In addition, the conical guide plate 221 can also reduce the accumulation and retention of catalyst particles on its upper part.
[0088] Please see again. Figure 6 and Figure 7 As shown, the raw material gas inlet distributor 3 includes an inlet pipe 301, a premix pipe 302 and a raw material gas distributor 303 connected in sequence. The premix pipe 302 is provided with a mixing auxiliary component 305 along the axial direction to fully mix the high-temperature raw material gas.
[0089] The raw material gas distributor 303 is equipped with a downward-opening nozzle 304, which is used to uniformly spray the premixed high-temperature raw material gas into the dense phase reaction zone.
[0090] In the production of hydrogen cyanide, the methanol-ammonia feed distributor is constantly exposed to high temperatures. When the temperature of the mixed gas exceeds the temperature at which ammonia decomposes into active nitrogen atoms, some ammonia decomposes into active nitrogen atoms, which combine with metal atoms in the feed distributor tube to form brittle metal nitrides, causing the feed distributor to break. Therefore, this invention introduces a premixing tube 302 and a mixing auxiliary component 305 to ensure sufficient residence time and turbulence of methanol and ammonia in this space, achieving thorough premixing, forming a uniform mixed gas, reducing the local ammonia concentration in the distributor area, thereby reducing the local ammonia partial pressure and the tendency of ammonia decomposition, inhibiting the generation of active nitrogen atoms from ammonia decomposition at high temperatures, reducing the formation of metal nitrides from the source, and preventing the feed distributor from breaking. Simultaneously, the built-in mixing auxiliary component further enhances the turbulent mixing of methanol and ammonia before entering the reaction zone, significantly shortening the residence time required for molecular-level uniform mixing, thereby greatly inhibiting ammonia decomposition and subsequent nitriding corrosion reactions. The premixing tube acts as a "rapid mixing buffer," playing a crucial role in protecting the core feed distributor and extending its service life while meeting process mixing requirements. Here, the mixing auxiliary component 305 can be selected from mixing devices such as fins according to actual needs to enhance gas mixing efficiency and improve hydrodynamic characteristics, thereby ensuring that the methanol and ammonia entering the reactor can be fully and uniformly mixed and enter the catalyst bed in an ideal flow pattern, which helps to maintain the stable fluidization state of the catalyst bed and avoid channeling or dead zones. The shape of the premixing tube 302 can be approximately inverted "L".
[0091] Please see again. Figure 1 and Figure 8As shown, the cyclone separator assembly 4 includes a cyclone separator 41. The upper part of the cyclone separator 41 is connected to the top of the reactor shell 1 via a hanger 42, and the lower material legs 43 extend vertically into the dense phase reaction zone. Adjacent material legs 43 and the outermost material leg 43 are connected to the side wall of the reactor shell 1 via material leg connectors 44. The end of the material leg connector 44 that connects to the side wall of the reactor shell 1 is also provided with an elastic notched ring 45. In a more specific embodiment, each material leg 43 is connected to an adjacent material leg 43 or the side wall of the reactor shell 1 via at least three material leg connectors 44, and the included angle between any two adjacent material leg connectors 44 connected to the same material leg 43 does not exceed 180°.
[0092] Different material legs 43 are connected as a whole by material leg connectors 44. Under the complex load of fluidized bed, stress can be effectively transferred and dispersed, avoiding structural cracking and deformation caused by local stress concentration, improving the vibration and torsional resistance of material legs 43, ensuring long-term stable alignment of material legs 43, and maintaining the material sealing function. At the same time, local vibration can be quickly dispersed to adjacent material legs 43, forming a high-rigidity bending-resistant system and suppressing the lateral sway of material legs 43 (similar to the space truss effect). In addition, an elastic notch ring 45 is set to connect with the side wall of the reactor shell 1. In this way, as a flexible interface, it can absorb energy based on the elastic deformation of its own opening, compensate for the small radial displacement of material legs 43, avoid vibration directly transmitted to the cylinder wall, reduce the fatigue damage of vibration to the material leg 43 body and connecting structure, improve the vibration resistance of material legs 43, and adapt to the dynamic load environment inside the reactor.
[0093] The region on the reactor shell 1 located between the dilute phase settling zone 13 and the dense phase reaction zone 12 adopts a variable diameter design with the diameter gradually decreasing from top to bottom.
[0094] Example 2:
[0095] The structure of the hydrogen cyanide fluidized bed reactor in this embodiment is as shown in Embodiment 1, and its equipment parameters and operating parameters are as follows:
[0096] The cone angle of the air equalization chamber (i.e., the cone angle of its bottom conical head) is 45°. The distance H between the bottom of the guide plate 221 and the air distribution plate 21 satisfies: H / D=0.15. The cone angle α of the guide plate 221 is also set to 45°, and the size of D is 9500mm. The height of the dense phase reaction zone 12 is 3500mm. The distance between the raw material gas distributor 303 and the air distribution plate 21 is 480mm. When the upper and lower sets of heat removal components are running, the temperature of the dense phase reaction zone 12 is controlled at approximately 420℃, and the temperature of the dilute phase settling zone 13 is controlled at approximately 400℃. The diameter of the dilute phase settling zone 13 is 1.05~1.1 times the diameter of the dense phase reaction zone 12, and the height is approximately 5500mm.
[0097] The fluidized bed reactor is filled with hydrogen cyanide catalyst, and the catalyst bed density is approximately 350 kg / m³. 3 The feed ratio of methanol, ammonia, and air is 1:1.25:14. The air inlet temperature is approximately 130℃ and the pressure is approximately 0.15 MPa. The methanol / ammonia feed gas inlet temperature is approximately 100℃ and the pressure is approximately 0.15 MPa.
[0098] The gas velocity of the reactant gas in the empty bed of the dense phase reaction zone is about 0.7 m / s, and the pressure at the top of the fluidized bed reactor is 0.05 MPa.
[0099] The specific structural parameters of the heat dissipation component 14 are as follows: the heat-dissipating fins 142 in the same group of heat-dissipating components are arranged in a 90° annular array along the circumference of the cooling main pipe 141, that is, the same group of heat-dissipating components includes 4 heat-dissipating fins 142, and the angle between adjacent heat-dissipating fins 142 is 90°. The height of the heat-dissipating fins 142 is 0.3 times the outer diameter of the cooling main pipe 141, the thickness (i.e., width) of the heat-dissipating fins 142 is 2 mm, the length is twice the outer diameter of the cooling main pipe 141, the wave height of the heat-dissipating fins 142 is 0.25 times the outer diameter of the cooling main pipe 141, and the corrugation angle of the heat-dissipating fins 142 is 45°.
[0100] Comparative Example 1:
[0101] Compared with Example 2, most of them are the same, except that the outlet end of the air inlet pipe 22 is changed to extend horizontally from the side wall of the air equalization chamber 11, and a horizontal baffle (the length of the baffle is about 1 / 4D) is arranged above the outlet end.
[0102] Comparative Example 2:
[0103] Compared with Example 2, most of them are the same, except that the air distribution plate 21 is changed to a conventional structure, that is, the arrangement of the air guide cap 213 is omitted.
[0104] Comparative Example 3:
[0105] Compared with Example 2, most of them are the same, except that the premixing pipe 302 in the raw gas inlet distributor 3 does not have a mixing auxiliary component 305.
[0106] The partial reaction results of Example 2 and Comparative Examples 1 to 3 are shown in Table 1.
[0107] Table 1. Results of the methanol ammoxidation reaction to produce hydrogen cyanide.
[0108]
[0109] Based on the above, it can be seen that the present invention has the following innovative advantages:
[0110] (1) By using air distribution plates with staggered flow guides and air inlet pipes with central guide plates to work together, a uniform mesh-like initial fluidization field is constructed from the source to prevent catalyst accumulation.
[0111] (2) A raw material gas premixing pipe with built-in mixing auxiliary components is used to enhance the turbulent mixing of methanol and ammonia before entering the high temperature zone and suppress the nitriding corrosion of the feed distributor caused by ammonia decomposition.
[0112] (3) The cooling water pipe with interlaced corrugated strip heat transfer fins can effectively remove heat while the fins form cross turbulence, which can actively break up the rising large bubbles and guide the catalyst to circulate in an orderly manner, thus achieving the integration of efficient heat removal and flow field optimization.
[0113] (4) Multiple cyclone separator legs are flexibly interconnected by a leg connector with an elastic notch ring, which significantly improves the vibration resistance and fatigue resistance of the separator assembly.
[0114] The above optimization measures work synergistically to effectively improve the fluidization uniformity of the catalyst, avoid local overheating, enhance reaction efficiency and selectivity, and strengthen the long-term operational stability of the equipment.
[0115] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.
Claims
1. A fluidized bed reactor for the production of hydrogen cyanide, characterized in that, include: The reactor shell includes an air equalization chamber, a dense phase reaction zone, and a dilute phase sedimentation zone arranged coaxially from bottom to top; An air inlet distributor includes an air distribution plate and an air inlet pipe. The air distribution plate is horizontally disposed between the air equalization chamber and the dense phase reaction zone, and the air inlet pipe extends into the air equalization chamber from the side. A feed gas inlet distributor that extends into the dense phase reaction zone; A cyclone separator assembly arranged in the dilute phase settling zone and fixedly connected to the top of the reactor shell; And independent heat removal components are disposed in the dense phase reaction zone and the dilute phase sedimentation zone; The air distribution plate includes a distribution plate body, multiple air distribution pipes arranged in an array and vertically fixed on the distribution plate body, and guide caps fixed on the distribution plate body and correspondingly positioned above the air distribution pipes. The guide caps and the distribution plate body form a horizontally penetrating air guiding cavity with open ends. Any two adjacent guide caps along the horizontal or longitudinal direction are staggered at 90°. The inner and outer surfaces of the flow guide cap along the air guide cavity are both inclined slopes. The airflow ejected from one flow guide cap will impact the inclined side of the adjacent flow guide cap, generating secondary disturbance and diffusion. The center-to-center distance between two adjacent air distribution pipes is 3.5 to 4.5 times the length of the guide cap; The outlet end of the air inlet pipe is set upward and located on the central axis of the air equalization chamber. At the outlet end of the air inlet pipe, a guide plate with a conical umbrella-shaped surface is connected by several radial stiffeners, and a horizontal radial air guide is formed between adjacent stiffeners. The raw material gas inlet distributor includes an inlet pipe, a premixing pipe and a raw material gas distributor connected in sequence. The premixing pipe is provided with a mixing auxiliary component along the axial direction to fully mix the high-temperature raw material gas.
2. A fluidized bed reactor for hydrogen cyanide production according to claim 1, characterized in that, The heat dissipation component includes a cooling water pipe and one or more sets of heat transfer components disposed on the outer wall of the cooling water pipe. Each set of heat transfer components includes multiple corrugated heat transfer fins distributed along the circumference of the cooling main pipe. When there are multiple sets of heat transfer components, adjacent sets of heat transfer components are staggered in the circumference of the cooling main pipe to form a cross-turbulence structure.
3. A fluidized bed reactor for hydrogen cyanide production according to claim 1, characterized in that, The cone angle α of the guide plate is 30~60°, and the distance H between the bottom end of the guide plate and the air distribution plate satisfies: 0.08≤H / D≤0.3, where D is the diameter of the interface between the air equalization chamber and the dense phase reaction zone.
4. A fluidized bed reactor for hydrogen cyanide production according to claim 1, characterized in that, The raw material gas distributor is equipped with multiple downward-facing nozzles for uniformly injecting the premixed high-temperature raw material gas into the dense phase reaction zone.
5. A fluidized bed reactor for hydrogen cyanide production according to claim 1, characterized in that, The cyclone separator assembly includes multiple cyclone separators. The upper part of the cyclone separator is connected to the top of the reactor shell via a hanger, and the lower material leg extends vertically into the dense phase reaction zone. Adjacent material legs are connected to each other, as well as the outermost material leg is connected to the side wall of the reactor shell via material leg connectors. The end of the material leg connector that connects to the side wall of the reactor shell is also provided with an elastic notch ring.
6. A fluidized bed reactor for hydrogen cyanide production according to claim 5, characterized in that, Each material leg is connected to an adjacent material leg or the side wall of the reactor shell through at least three material leg connectors, and the included angle between any two adjacent material leg connectors connected to the same material leg does not exceed 180°.
7. A fluidized bed reactor for hydrogen cyanide production according to claim 1, characterized in that, The transition section on the reactor shell between the dilute phase settling zone and the dense phase reaction zone adopts a tapered variable diameter structure with a diameter that gradually decreases from top to bottom.