Fluidized bed reaction device and process method for producing acrylonitrile or hydrocyanic acid

Abstract

The invention relates to a fluidized bed reaction device for producing acrylonitrile or hydrocyanic acid and a process method thereof. The device is sequentially provided with an air pressure equalizing chamber, a concentrated phase reaction zone and a dilute phase settling zone from bottom to top. And the air pressure equalizing chamber is connected with the concentrated phase reaction zone through an air pressure drop distributor so as to realize uniform flow and distribution of gas. And a mixed gas distributor is arranged in the concentrated phase reaction zone and is responsible for uniformly spraying mixed gas of ammonia and propylene (or methanol) to be in contact with a high-temperature catalyst so as to promote the proceeding of a chemical reaction. The gas after the reaction enters a dilute-phase settling zone, the solid catalyst is separated through a cyclone separator in the zone, and the purified gas is discharged through a gas collecting chamber. According to the design, gas contact time and catalyst fluidization conditions are accurately controlled, so that the explosion risk is effectively reduced, the reaction safety and the production efficiency are improved, and the method is suitable for industrial production and has relatively high operation flexibility and production load.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical engineering process, and relates to a fluidized bed reaction device and process method of acrylonitrile and hydrocyanic acid with safety and high load operation flexibility. Background Art

[0002] The propylene ammoxidation reaction for producing acrylonitrile is a fluidized bed reaction process. The mixture ratio of the three raw materials ammonia, propylene and air is within the explosion risk range. Although ammonia / propylene and air are fed separately, there is still an explosion hazard zone in the reactor. In addition, acrylonitrile reactors mostly use bubbling beds, and the reactor sedimentation section and reaction section have the same diameter. Such a reaction structure can only achieve reaction and sedimentation within a certain linear speed range. The linear speed of the traditional acrylonitrile technology reactor can only be controlled within the range of 0.5m / s-0.8m / s. Low linear speed will lead to poor fluidization state, small processing capacity of the device, and uneconomical. High linear speed will cause catalyst loss. The device reaction load is low and the elasticity is small.

[0003] In order to increase the device load of the acrylonitrile reactor, CN106478457A improves the propylene ammoxidation process and its reactor, and the linear speed of the fluidized bed is increased to 0.7m / s-1.0m / s. The limit operation flexibility of the device is 70%-100%.

[0004] Although the research on the technology of producing hydrocyanic acid by methanol ammoxidation is very active, the industrial research progress is slow, mainly because the explosion risk of the feed mixing reaction section in the large-scale reactor has not been solved, and the problem of secondary reaction in the settling zone caused by poor catalyst settling effect has not been solved. Although patent CN106006673B proposes a single-tube small fluidized bed reaction device with a linear velocity range of 0.2m / s-0.8m / s, the patent does not propose a solution to reduce the explosion risk of the feed mixing reaction section and avoid secondary reactions in the settling zone. Summary of the invention

[0005] The purpose of the present invention is to provide a safe, high-load operation flexibility acrylonitrile / hydrocyanic acid fluidized bed reactor. Through the precise design of the structure and relative position of the air distributor and the ammonia and propylene (methanol) mixed gas distributor of the fluidized bed reactor, not only the air and ammonia / propylene (methanol) are evenly mixed, but also the contact time of the air and ammonia / propylene (methanol) is less than 0.3S at the feed concentration, eliminating the risk of explosion; by enlarging the diameter of the sedimentation section, reducing the linear speed of the sedimentation section, and improving the sedimentation efficiency of the catalyst, the load operation flexibility of the reactor in the dense phase section is improved, and the secondary reaction in the sedimentation zone is avoided.

[0006] The present invention is achieved through the following technical solutions:

[0007] A fluidized bed reaction device for producing acrylonitrile or hydrocyanic acid, characterized in that the device comprises a reactor shell and reactor internals, wherein the reactor shell comprises, from bottom to top, an air pressure equalizing chamber of a lower cone portion, a dense phase reaction zone of a middle cylindrical portion, and a dilute phase settling zone formed by a combination of a cone segment, a cylindrical segment, and a spherical segment from bottom to top; an air pressure drop distributor is arranged between the air pressure equalizing chamber and the dense phase reaction zone, and an air inlet is arranged on the air pressure equalizing chamber shell; a mixed gas distributor is arranged at the lower part of the dense phase reaction zone, and the inlet of the mixed gas distributor The end is connected with a mixed gas inlet pipe, and the mixed gas distributor divides the dense phase reaction zone into a catalyst oxidation regeneration zone below and a main dense phase reaction zone above. A cooling medium U-shaped tube bundle is arranged in the main dense phase reaction zone, and the collecting main pipe of the cooling medium U-shaped tube bundle is connected with the cooling medium inlet and outlet pipes; a cyclone separator and a gas collecting chamber are arranged in the dilute phase sedimentation zone, and the material legs of the cyclone separator extend into the dense phase reaction zone, and the top outlet of the cyclone separator is connected with the gas collecting chamber located at the top of the dilute phase sedimentation zone, and a reaction gas outlet is arranged on the top of the gas collecting chamber, and is connected with the reaction gas outlet pipe.

[0008] Preferably, the air pressure drop distributor is located 100mm-300mm above the lower tangent line of the reactor, and includes a porous plate with uniform openings and a Venturi distribution pipe arranged at the openings; the Venturi distribution pipe consists of a throat, a distribution straight pipe, and a diffusion section, and the distribution straight pipe and the porous plate are connected by a diffusion section with a smooth curved surface structure.

[0009] Preferably, the porosity of the porous plate is 10% to 20%, the aperture of the opening is 1.5 to 2 times the inner diameter of the distribution straight tube, the length of the distribution straight tube is 100mm to 200mm, the inner diameter is 15mm to 35mm, the diameter of the throat is 0.3 to 0.5 times the inner diameter of the distribution straight tube, and the diffusion angle of the connection between the throat and the distribution straight tube is 60 to 90°.

[0010] Preferably, the mixed gas distributor includes an air inlet main pipe, a gas branch pipe and a gas distribution short pipe. The number of the air inlet main pipes is 1-6. The gas branch pipes are symmetrically distributed on both sides of the air inlet main pipe. A row of gas distribution short pipes is provided at the bottom of the air inlet main pipe. Two rows of gas distribution short pipes are cross-symmetrically arranged on the lower side wall of the gas branch pipe. The angle between the two rows of gas distribution short pipes is 40-60°.

[0011] Preferably, the length of the short gas distribution pipe is 80mm to 150mm, the diameter is 15mm to 25mm, the spacing between two adjacent short gas distribution pipes in the same row on the gas branch pipe is 8-12 times the diameter of the distributed straight pipe, and the spacing follows a decreasing law, gradually decreasing from the air inlet end to the distal end.

[0012] Preferably, the cone angle of the air equalizing chamber is 60° to 120°, the air inlet is located at 1 / 3 to 1 / 2 of the cone height, a guide plate is arranged above the air inlet, the area of ​​the guide plate is 1.5 to 2 times the cross-sectional area of ​​the air inlet pipe, and the angle between the plane of the guide plate and the side of the cone is 60° to 100°; the total height of the dense phase reaction zone is 7m to 11m, of which the height of the catalyst oxidation regeneration zone is 400mm to 600mm, and the height of the main dense phase reaction zone is 6.7m to 10.5m; the diameter of the cylindrical section of the dilute phase sedimentation zone is 1.2 to 1.8 times that of the dense phase reaction zone, and the height is 0.6 to 0.9 times the height of the dense phase reaction zone, and the cone angle of the dilute phase sedimentation zone is 100° to 150°.

[0013] Preferably, the cooling medium U-shaped tube bundle is a plurality of heat exchange tube bundles arranged vertically, the diameter of the heat exchange tube is between 50mm and 150mm, the spacing between adjacent heat exchange tubes is between 100mm and 200mm, and the length of the heat exchange tube is 0.98 to 1.0 times the height of the dense phase reaction zone.

[0014] Preferably, the distance between the mixed gas distributor and the air pressure drop distributor is 400 mm-600 mm.

[0015] Preferably, the volume of the gas collecting chamber is 0.02-0.05 times that of the dilute phase settling zone (zone III).

[0016] The present invention also provides a process for producing acrylonitrile or hydrocyanic acid using a fluidized bed reaction device, characterized in that the acrylonitrile or hydrocyanic acid is produced by using the fluidized bed reaction device according to claim 1 through the following steps:

[0017] (1) Air enters the air equalizing chamber, is guided by the guide plate, is pressure-equalized in the air equalizing chamber, and is evenly distributed to the dense phase reaction zone through the air pressure drop distributor, contacts the catalyst bed, and fluidizes and regenerates the catalyst;

[0018] (2) Ammonia and propylene (methanol) mixed gas is uniformly sprayed into the catalyst oxidation regeneration zone through a mixed gas distributor, where it contacts the hot catalyst, starts the reaction, and rapidly heats the reaction mixed gas;

[0019] (3) The reaction gas stays in the catalyst oxidation regeneration zone for less than or equal to 0.3 seconds, and then enters the main dense phase reaction zone to continue the reaction. The reaction heat is taken away by the cooling medium in the U-shaped tube bundle;

[0020] (4) After the reaction is completed, the reaction gas carries the catalyst into the dilute phase settling zone, and the gas velocity is reduced to 0.3 to 0.5 times the linear velocity of the dense phase reaction zone, and the entrained catalyst is accelerated to settle;

[0021] (5) In the dilute phase settling zone, the cyclone separator separates the entrained catalyst, and the separated catalyst returns to the dense phase reaction zone to continue to participate in the reaction. The separated gas is discharged through the gas collecting chamber to eventually form acrylonitrile or hydrocyanic acid product gas;

[0022] Among them, when producing acrylonitrile, the mixed gas is ammonia and propylene, and the molar ratio of propylene:ammonia:air is 1:(1.05~1.1):(9~10); when producing hydrocyanic acid, the mixed gas is ammonia and methanol, and the molar ratio of methanol, ammonia and air is 1:(1.1~1.3):(9.8~1.3).

[0023] Beneficial Effects

[0024] 1. The fluidized bed reaction device of the present invention can be applied to the production of acrylonitrile and hydrocyanic acid in two reaction processes.

[0025] 2. The reaction structure and process are combined to ensure that the residence time of propylene (methanol), ammonia and air in the explosion range is less than 0.3m, thus avoiding the risk of explosion.

[0026] 3. Different from the traditional acrylonitrile / hydrocyanic acid fluidized bed reactor, the dilute phase settling zone and the dense phase reaction zone in the reactor structure of the present invention adopt different operating linear speeds. The linear speed of the dilute phase settling zone is low, which is conducive to the rapid sedimentation of the catalyst, and the secondary reaction of the reaction product in the dilute phase zone is avoided to the greatest extent, the occurrence rate of by-products is reduced, and the product yield is improved.

[0027] 4. When the technical solution of the present invention is used for acrylonitrile production, the reactor line speed can reach 1.2 m / s, and when it is used for hydrocyanic acid production, the reactor line speed can reach 1.0 m / s. The production load of the device can be increased by more than 30% compared with the prior art. When producing acrylonitrile, the operating flexibility of the reactor is 50%-120%; when producing hydrocyanic acid, the operating flexibility of the reactor is 30%-100%.

[0028] 5. The special air pressure drop distributor structure enables the air to be evenly distributed over the entire cross-section of the reactor at the same or even lower pressure difference, making the dense phase fluidized bed with air as the main fluidizing medium more uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of acrylonitrile (hydrocyanic acid) reaction device.

[0030] Among them, 1. reactor shell, 2. cooling medium U-shaped tube bundle, 3. cyclone separator, 4. gas collecting chamber, 5. mixed gas distributor, 6. air pressure drop distributor, 7. guide plate;

[0031] Figure 2 Air pressure drop distributor structure diagram

[0032] Among them, 6.1 perforated plate, 6.2 venturi distribution pipe, 6.21 throat, 6.22 distribution straight pipe, 6.23 diffusion section;

[0033] Figure 3A is a schematic diagram of the structure of the mixed gas distributor inlet main pipe

[0034] Among them, 5.1 is the air intake main pipe, 5.2 is the gas branch pipe;

[0035] FIG3B is a schematic diagram of short gas pipes on the gas branch pipes of the mixed gas distributor, wherein 5.3 is a gas branch pipe;

[0036] FIG3C is a schematic diagram of the structure of the short gas distribution pipe on the main pipe of the mixed gas distributor, wherein 5.3 is the short gas distribution pipe. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation methods.

[0038] A safe, high-load elastic olefin nitrile fluidized bed reaction device, such as Figure 1 As shown: It includes a reaction device, and the reactor device includes a reaction shell (1) and reactor internals. The reactor (shell) is composed of an air pressure chamber (lower cone part, zone I), a dense phase reaction zone (middle cylindrical part, zone II) and a dilute phase settling zone (zone III) from bottom to top. The dense phase reaction zone is further divided into a catalyst oxidation regeneration zone (II) according to its function. — ) and the main concentrated phase reaction zone (Ⅱ + An air pressure drop distributor (6) is provided between the air plenum chamber (zone I) and the dense phase reaction zone (zone II). An air inlet is provided on the air plenum chamber shell, and a guide plate (7) is provided above the air inlet.

[0039] Catalyst oxidation regeneration zone (Ⅱ — ) and the main concentrated phase reaction zone (Ⅱ + ) is provided with an ammonia and propylene (methanol) mixed gas distributor (5), the inlet end of the ammonia and propylene (methanol) mixed gas distributor (5) is connected to an ammonia and propylene mixed gas inlet pipe; the main dense phase reaction zone (Ⅱ + ) is also provided with a cooling medium U-shaped tube bundle (2), which is connected to the cooling medium inlet and outlet pipes; a cyclone separator (3) and a gas collecting chamber (4) are provided in the dilute phase settling zone (III zone), and the feed leg of the cyclone separator (3) extends downward into the main dense phase reaction zone (II zone). + ), the exhaust pipe of the cyclone separator (3) is connected to the gas collecting chamber (4); the top of the gas collecting chamber (4) is provided with a reaction gas outlet, and is connected to the external exhaust pipe of the product gas obtained by the reaction.

[0040] 1) Air pressure equalization chamber

[0041] The cone angle of the air plenum chamber (lower cone I) of the reactor shell is designed to be within the range of 60°-120°, the air inlet is located at 1 / 3-1 / 2 of the cone height, a guide plate (7) is arranged 200mm-500mm above the air inlet, the guide plate (7) is a rectangular, square or arched flat plate, the area of ​​the guide plate (7) is 1.5 to 2 times the cross-sectional area of ​​the air inlet pipe, the angle between the plane of the guide plate (7) and the side of the cone is 60°-100°, the guide plate (7) guides the inlet air to the cone bottom of the air plenum chamber (lower cone I), and then rises to enter the air pressure drop distributor (6), thereby improving the air pressure equalization effect.

[0042] 2) Air pressure drop distributor

[0043] The air pressure drop distributor (6) is located between the air pressure equalization chamber (zone I) and the dense phase reaction zone (zone II). It is located 100mm-300mm above the lower tangent line of the reactor. The main function of the air pressure drop distributor (6) is to evenly distribute the air on the reactor interface and evenly fluidize the catalyst in the dense phase reaction zone (zone II).

[0044] The air pressure drop distributor (6) is composed of a porous plate (6.1) and a plurality of venturi distribution pipes (6.2) fixed on the plate. The detailed structure is as follows: Figure 2 6.1 distribution plate, 6.2 Venturi distribution pipe, 6.21 throat, 6.22 distribution pipe, 6.23 diffusion section

[0045] The venturi distribution pipe (6.2) is composed of a throat nozzle (6.21), a distribution straight pipe (6.22), and a diffusion section (6.23). The length of the distribution straight pipe (6.22) is 100 mm to 200 mm, the inner diameter of the straight pipe section is 15 mm to 35 mm, the diameter of the throat nozzle (6.21) is 0.3 to 0.5 times the inner diameter of the distribution pipe (6.22), and the diffusion angle of the connection between the nozzle (6.21) and the distribution straight pipe (6.22) is 60 to 90 degrees.

[0046] The distribution plate (6.1) is evenly perforated with a perforation ratio of 10%-20%, and the aperture of the perforation is 1.5-2 times the inner diameter of the distribution pipe (6.22). The distribution straight pipe (6.22) and the distribution plate (6.1) are connected via a diffusion section (6.23), and the diffusion section (6.23) is a smooth curved surface structure. This air distributor structure has a low pressure drop and a good distribution effect.

[0047] 3) Dense phase reaction zone

[0048] The total height of the concentrated phase reaction zone (Zone II) is 7m-11m. — ) height 300mm-600mm, the main concentrated phase reaction zone (Ⅱ +) is 6.7m-10.5m in height.

[0049] Mixed gas distributor(5)

[0050] Catalyst oxidation regeneration zone (Ⅱ — ) and the main concentrated phase reaction zone (Ⅱ + ) between the ammonia and propylene (methanol) mixed gas distributor (5) as shown in Figure 3. It consists of an inlet main pipe (5.1), a gas branch pipe (5.2) and a gas distribution short pipe (5.3). According to the diameter of the reactor, 1 to 6 inlet main pipes (5.1) ( Figure 3-A ), each intake pipe (5.1) is connected to the ammonia / propylene (methanol) intake pipe, and the gas branch pipes (5.2) are symmetrically distributed on both sides of the intake pipe (5.1) ( Figure 3-A The figure shows the case of four intake manifolds). The bottom of the main pipe (5.1) is provided with a short air distribution pipe (5.3) ( Figure 3-C ), two rows of short gas distribution pipes (5.3) are arranged crosswise and symmetrically on the lower side wall of the gas branch pipe (5.2) ( Figure 3-B ). The angle between two rows of short gas distribution pipes (5.3) is 40-60°. All short gas distribution pipes (5.3) have the same structure, a length of 80mm-150mm, and a distribution pipe diameter of 15mm-25mm. The spacing between two adjacent short gas distribution pipes (5.3) in the same row on the gas branch pipe (5.2) ranges from 8 to 12 times the distribution pipe diameter. The spacing follows a decreasing law, gradually decreasing from the air inlet end to the far end.

[0051] Cooling medium U-tube bundle (4)

[0052] The cooling medium U-shaped tube bundle (4) is a plurality of heat exchange tube bundles arranged vertically, the diameter of the heat exchange tubes is between 50 mm and 150 mm, the spacing between adjacent heat exchange tubes is between 100 mm and 200 mm, and the length of the heat exchange tubes is the same as that of the concentrated phase reaction zone (II). + ) is 0.98-1.0 times the height.

[0053] Dilute phase settling zone

[0054] The diameter of the cylindrical section of the dilute phase sedimentation zone (zone III) is 1.2-1.8 times the diameter of the dense phase reaction zone (zone II), and the height is 0.6-0.9 times the height of the dense phase reaction zone (zone II); the cone angle of the conical section of the dilute phase sedimentation zone (zone III) is 100-150°.

[0055] Cyclone separator (3)

[0056] The cyclone separator (3) is located in the dilute phase settling zone (zone III) and is composed of 2-3 stages of cyclone separators. The feed leg of the cyclone separator (3) is located in the dense phase reaction zone, and the outlet of the last stage of the cyclone separator is connected to the gas collecting chamber (4). The cyclone separator adopts a commercially available model, and the gas-solid separation efficiency of the single-stage cyclone separator (3) is greater than 99.0%.

[0057] Gas chamber (4)

[0058] The gas collecting chamber (4) is located at the top of the dilute phase settling zone (zone III), and its volume is 0.02-0.05 times that of the dilute phase settling zone (zone III). The outlet of the gas collecting chamber (4) is connected to the outlet pipeline of the process gas.

[0059] Process technical parameters

[0060] 1) Acrylonitrile reaction process and parameters:

[0061] This patent is applicable to commercially available acrylonitrile catalysts: commercially available catalysts with molybdenum and bismuth as main active components, and the catalyst particle size distribution is: 45% of the catalyst particles are less than 45μm.

[0062] All three reaction raw materials are gas phase feed. To reduce safety risks, air is fed alone, and propylene gas and ammonia gas are mixed and fed from the ammonia olefin distributor. The feed ratio of the three raw materials is: propylene: ammonia: air = 1: (1.05-1.1): (9-10).

[0063] Air with a temperature of 105°C-120°C and a pressure of 0.08-0.15MPa enters the air equalizing chamber (Zone I), is guided by the guide plate (7), first flows downward and then upward, and enters the air pressure drop distributor (6) after pressure equalization. The residence time of the air in the air equalizing chamber (Zone I) is 0.3S-1.0S. The flow rate of the air rising through the distribution pipe of the air pressure drop distributor (6) is 100m / s-250m / s, and the pressure drop of the air pressure drop distributor (6) is 20KPa-50KPa. If the pressure drop is too low, it is impossible to ensure uniform distribution of the bed layer. If the pressure drop is too high, the energy consumption increases, and it does not contribute much to uniform distribution.

[0064] After passing through the air pressure drop distributor (6), the air first contacts the high-temperature catalyst bed, and while fluidizing the catalyst, it is also heated by the hot catalyst. At the same time, the oxygen in the air is adsorbed by the catalyst to replenish the catalyst's lattice oxygen, thereby regenerating the catalyst.

[0065] The ammonia / olefin mixed gas with a temperature of 65°C-80°C and a pressure of 0.1-0.2MPa is uniformly sprayed downward into the catalyst oxidation regeneration zone (Ⅱ) through the distribution short pipe of the ammonia / olefin distributor (5) at a gas velocity of 50m / s-100m / s. —), contacts the hot catalyst, and while heating itself, reacts with the lattice oxygen on the catalyst to start the acrylonitrile production reaction. The reaction exotherm further heats the catalyst and the reaction mixture, allowing the materials in the reaction system to quickly reach the set reaction temperature.

[0066] The reaction mixture is in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.2-0.3s. After the temperature rises to about 410-420°C, it enters the main dense phase reaction zone (Ⅱ + ) continues to react, and the reaction heat is taken away by the cooling medium in the U-shaped tube bundle (2). Due to the uniform gas distribution of the air pressure drop distributor (6) and the ammonia and propylene mixed gas distributor (5), the fluidized bed is uniformly fluidized in the dense phase reaction zone (Ⅱ) and has good temperature uniformity. + ) in the empty bed gas velocity range of 0.5m / s-1.2m / s. Control the main dense phase reaction zone (Ⅱ + ) bed density 300-400kg / m 3 The temperature range of the dense phase reaction zone (II) is 410-440°C, the radial temperature difference of the bed is controlled within 2°C, and the axial temperature difference is controlled within 4°C.

[0067] In the main concentrated phase reaction zone (Ⅱ + ) The reaction gas that has completed the reaction carries the catalyst into the dilute phase settling zone (Zone III) by inertia. In the dilute phase settling zone (Zone III), due to the expansion of the reactor diameter and the absence of heat exchange tubes, the gas velocity is reduced to 0.3-0.5 times the linear velocity of the dense phase reaction zone (II). The entrained catalyst settles faster. When the gas reaches the inlet of the cyclone separator, the catalyst concentration in the gas is reduced to 2-5 kg / m 3 After 2-3 levels of cyclone separation, the catalyst is recovered and returned to the main dense phase reaction zone (Ⅱ + ), the desolidified reaction product gas is discharged from the reaction device. The top pressure of the reaction is controlled at 30-60KPa. Too high pressure will lead to an increase in CO and CO2 by-products.

[0068] Under the reaction conditions, the yield of acrylonitrile is 85-90%, and the reactor load can be operated in the range of 40%-100%. The load of the device is increased by 30% compared with the prior art, and the elasticity of the device operation load is increased by 30%.

[0069] 2) Hydrocyanic acid reaction process and parameters

[0070] This patent is applicable to commercially available hydrocyanic acid catalysts: commercially available catalysts with molybdenum, iron, etc. as main active components, and the catalyst particle size distribution is: 45% of the catalyst particles are less than 45μm.

[0071] All three reaction raw materials are gaseous feed. To reduce safety risks, air is fed separately, and methanol gas and ammonia are mixed and fed from the ammonia methanol distributor. The feed ratio of the three raw materials is: the molar ratio of methanol, ammonia and air is 1: (1.1-1.3): (9.8-13)

[0072] Air with a temperature of 110°C-120°C and a pressure of 0.1-0.15MPa enters the air equalizing chamber (Zone I), is guided by the guide plate (7), first flows downward and then upward, and enters the air pressure drop distributor (6) after pressure equalization. The residence time of the air in the air equalizing chamber (Zone I) is 0.3S-1.0S. The flow rate of the air rising through the distribution pipe of the air pressure drop distributor (6) is 100m / s-250m / s, and the pressure drop of the air pressure drop distributor (6) is 20KPa-50KPa. If the pressure drop is too low, it is impossible to ensure uniform distribution of the bed layer. If the pressure drop is too high, the energy consumption increases, and it does not contribute much to uniform distribution.

[0073] After the air passes through the air pressure drop distributor (6), it first contacts the high-temperature catalyst bed. While fluidizing the catalyst, it is also heated by the hot catalyst. At the same time, the oxygen in the air is adsorbed by the catalyst to replenish the catalyst's lattice oxygen, thereby regenerating the catalyst.

[0074] Ammonia / methanol mixed gas with a temperature of 85°C-120°C and a pressure of 0.10-0.18 MPa is uniformly sprayed downward into the catalyst oxidation regeneration zone (Ⅱ) through the distribution short pipe of the ammonia / methanol distributor (5) at a gas velocity of 50m / s-100m / s. — ), contacts the hot catalyst, and while heating itself, reacts with the lattice oxygen on the catalyst to start the hydrocyanic acid production reaction. The reaction releases heat to further heat the catalyst and the reaction mixture, allowing the materials in the reaction system to quickly reach the set reaction temperature.

[0075] The reaction mixture is in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.25S-0.3S, and after the temperature rises to 380-410℃, it enters the main dense phase reaction zone (Ⅱ + ), enter the main concentrated phase reaction zone (Ⅱ + ) continues to react, and the reaction heat is taken away by the cooling medium in the U-shaped tube bundle (2). The reaction gas is in the main dense phase reaction zone (Ⅱ + ) in the empty bed gas velocity range of 0.3m / s-1.0m / s. Control the main dense phase reaction zone (Ⅱ + ) bed density 350-500kg / m 3 The temperature range of the dense phase reaction zone (II) is 400-430°C, the radial temperature difference of the bed is controlled within 2°C, and the axial temperature difference is controlled within 5°C.

[0076] In the main concentrated phase reaction zone (Ⅱ +) The reaction gas after the reaction carries the catalyst into the dilute phase settling zone (Zone III). In the dilute phase settling zone (Zone III), due to the expansion of the reactor diameter and the absence of heat exchange tubes, the gas velocity is reduced to 0.3-0.5 times the linear velocity of the dense phase reaction zone (II). The entrained catalyst settles faster. When the gas reaches the inlet of the cyclone separator, the catalyst concentration in the gas is reduced to 3-4 kg / m 3 After 2-3 levels of cyclone separation, the catalyst is recovered and returned to the main dense phase reaction zone (Ⅱ + ), the desolidified reaction product is discharged from the reaction device. The pressure at the top of the reaction is controlled at 30-60KPa. Too high a pressure will lead to an increase in CO and CO2 by-products.

[0077] The yield of hydrocyanic acid obtained by the reaction is 80-85%, and the reactor can be operated at a load of 30%-100%.

[0078] Example

[0079] The technical solution of the present invention will be described below in conjunction with specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0080] Embodiment 1:

[0081] Patented reaction device such as Figure 1 shown.

[0082] The cone angle of the air equalizing chamber (lower cone I) is 90°, the air inlet is located at 1 / 2 of the cone height, the guide plate (7) has an area twice the diameter of the air inlet pipe, and is located 300 mm above the air inlet.

[0083] The air pressure drop distributor (6) is located 200 mm above the lower tangent line of the reactor. The length of the distributor straight pipe (6.22) is 180 mm, the inner diameter of the straight pipe section is 25 mm, the diameter of the throat nozzle (6.21) is 0.4 times the inner diameter of the distribution pipe (6.22), and the diffusion angle of the connection between the nozzle (6.21) and the distribution straight pipe (6.22) is 60°. The opening rate of the porous plate (6.1) is 15%, and the aperture of the opening is 1.5 times the inner diameter of the distribution straight pipe (6.22).

[0084] The total height of the concentrated phase reaction zone (Zone II) is 10m. — ) height 600mm, the main concentrated phase reaction zone (Ⅱ + ) is 9.6m high.

[0085] The characteristic parameters of the structure of the mixed gas distributor (5) are: 4 inlet main pipes, the angle between two rows of short gas distribution pipes (5.3) on the inlet branch pipe (5.2) is 40 degrees. The length of the short gas distribution pipe (5.3) is 150 mm, and the diameter of the distribution pipe is 15 mm. The spacing between two adjacent short gas distribution pipes (5.3) in the same row is 8-5 of the distribution pipe diameter, and the spacing gradually decreases from the inlet end to the far end.

[0086] Catalyst oxidation regeneration zone (Ⅱ — ) height, that is, the distance between the mixed gas distributor (5) and the air pressure drop distributor (6) is 600 mm.

[0087] The height of the cooling medium U-shaped tube bundle (4) is 9.6 m, the diameter of the heat exchange tube is 100 mm, and the spacing between adjacent heat exchange tubes is 150 mm.

[0088] The diameter of the cylindrical section of the dilute phase sedimentation zone (Zone III) is 1.8 times the diameter of the dense phase reaction zone (Zone II), and the height is 0.6 times the height of the dense phase reaction zone (Zone II); the cone angle of the conical section of the dilute phase sedimentation zone (Zone III) is 150°

[0089] The yield of the 2-stage cyclone separator is 99.9% for single-stage cyclone separation. The volume of the gas collection chamber is 0.02 times that of the dilute phase settling zone (zone III).

[0090] The reactor is loaded with acrylonitrile catalyst, and the feed ratio of the three raw materials is: propylene: ammonia: air = 1:1.05:9.

[0091] The air inlet temperature is 108°C and the pressure is 0.09MPa; the ammonia / olefin mixed gas inlet temperature is 66°C and the pressure is 0.11MPa.

[0092] The reaction mixture is in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.28 s, the temperature of the dense phase reaction zone is controlled at 420 ± 2 °C, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 0.7 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 370kg / m 3 The pressure at the top of the reactor is 40 KPa.

[0093] The reaction results are shown in Table 1.

[0094] Example 2

[0095] In addition to the reaction gas in the main dense phase reaction zone (Ⅱ + ) is 0.8 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 360kg / m 3 Except for the above, all other steps are the same as those in Example 1. The reaction results are shown in Table 1.

[0096] Example 3

[0097] In addition to the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.23 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 1.2 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 300kg / m 3 Except for the above, all other steps are the same as those in Example 1. The reaction results are shown in Table 1.

[0098] Example 4

[0099] In addition to the reaction gas in the main dense phase reaction zone (Ⅱ + ) is 0.5 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 400kg / m 3 Except for the above, all other steps are the same as those in Example 1. The reaction results are shown in Table 1.

[0100] Example 5

[0101] The reactor structure is the same as that in Example 1.

[0102] The hydrocyanic acid catalyst is loaded, and the feed ratio of the three raw materials is: methanol: ammonia: air = 1:1.1:11.

[0103] The air inlet temperature is 110°C and the pressure is 0.1MPa; the ammonia / methanol mixed gas inlet temperature is 90°C and the pressure is 0.11MPa.

[0104] The reaction mixture is in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.29 s, the temperature of the dense phase reaction zone is controlled at 420 ± 2 °C, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 0.5 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 420kg / m 3 The pressure at the top of the reactor was 35 KPa.

[0105] The reaction results are shown in Table 2.

[0106] Example 6

[0107] In addition to the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.3 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 0.3 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 450kg / m 3Except for the above, all other steps are the same as those in Example 5. The reaction results are shown in Table 2.

[0108] Example 7

[0109] In addition to the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.27 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 0.6 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 380kg / m 3 Except for the above, all other steps are the same as those in Example 5. The reaction results are shown in Table 2.

[0110] Example 8

[0111] In addition to the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.25 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 1.0 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 320kg / m 3 Except for the above, all other steps are the same as those in Example 5. The reaction results are shown in Table 2.

[0112] Example 9

[0113] Except for the catalyst oxidation regeneration zone (Ⅱ — ) height, that is, the distance between the mixed gas distributor (5) and the air pressure drop distributor (6) is 400mm, and the length of the short gas distribution pipe (5.3) is 80mm. The reaction mixed gas in the catalyst oxidation regeneration zone (Ⅱ — ) with a residence time of 0.23 s. All other conditions are the same as those in Example 1. The reaction results are shown in Table 1.

[0114] Example 10

[0115] Remove the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.22 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 0.9 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 360kg / m 3 Except for the above, all other steps are the same as those in Example 9. The reaction results are shown in Table 1.

[0116] Embodiment 11

[0117] In addition to the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.20 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ +) in the empty bed gas velocity range of 1.2 m / s, the main dense phase reaction zone (Ⅱ + ) bed density 300kg / m 3 Except for the above, all other steps are the same as those in Example 9. The reaction results are shown in Table 1.

[0118] Example 12

[0119] The reactor structure is the same as that in Example 9.

[0120] The hydrocyanic acid catalyst is loaded, and the feed ratio of the three raw materials is: methanol: ammonia: air = 1:1.1:11.

[0121] The air inlet temperature is 110°C and the pressure is 0.1MPa; the ammonia / methanol mixed gas inlet temperature is 90°C and the pressure is 0.11MPa.

[0122] The reaction mixture is in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.22s, the temperature of the dense phase reaction zone is controlled at 420±2℃, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 0.9 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 420kg / m 3 The pressure at the top of the reactor was 35 KPa.

[0123] The reaction results are shown in Table 2.

[0124] Embodiment 13

[0125] In addition to the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.25 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) is 0.4 m / s, and the main dense phase reaction zone (Ⅱ + ) bed density 450kg / m 3 Except for the above, all other conditions are the same as those in Example 12. The reaction results are shown in Table 2.

[0126] Embodiment 14

[0127] In addition to the reaction mixture in the catalyst oxidation regeneration zone (Ⅱ — ) has a residence time of 0.21 s, and the reaction gas is in the main dense phase reaction zone (Ⅱ + ) in the empty bed gas velocity range of 0.8 m / s, the main dense phase reaction zone (Ⅱ + ) bed density 340kg / m 3 Except for the above, all other conditions are the same as those in Example 12. The reaction results are shown in Table 2.

[0128] Comparative Example 1

[0129] In addition to the reactor's dense phase reaction zone (Ⅱ) and dilute phase settling zone (Ⅲ) having the same diameter, the catalyst oxidation regeneration zone (Ⅱ — ) is 700 mm in height, the air pressure drop distributor (6) is a distribution straight pipe directly connected to the distribution plate, and no nozzle is provided at the lower end of the distribution straight pipe, and the rest is the same as in Example 1. The reaction results are shown in Table 1.

[0130] Comparative Example 2

[0131] In addition to the reactor's dense phase reaction zone (Ⅱ) and dilute phase settling zone (Ⅲ) having the same diameter, the catalyst oxidation regeneration zone (Ⅱ — ) is 700 mm in height, the air pressure drop distributor (6) is a distribution straight pipe directly connected to the distribution plate, and no nozzle is provided at the lower end of the distribution straight pipe, and the rest is the same as in Example 3. The reaction results are shown in Table 1.

[0132] Comparative Example 3

[0133] In addition to the reactor's dense phase reaction zone (Ⅱ) and dilute phase settling zone (Ⅲ) having the same diameter, the catalyst oxidation regeneration zone (Ⅱ — ) is 700mm high, the air pressure drop distributor (6) is a distribution straight pipe directly connected to the distribution plate, and no nozzle is provided at the lower end of the distribution straight pipe. The main concentrated phase reaction zone (Ⅱ + ) is 0.8 m / s, and the rest is the same as in Example 5. The reaction results are shown in Table 2.

[0134] Comparative Example 4

[0135] In addition to the reactor's dense phase reaction zone (Ⅱ) and dilute phase settling zone (Ⅲ) having the same diameter, the catalyst oxidation regeneration zone (Ⅱ — ) is 700 mm in height, the air pressure drop distributor (6) is a distribution straight pipe directly connected to the distribution plate, and no nozzle is provided at the lower end of the distribution straight pipe, and the rest is the same as in Example 8. The reaction results are shown in Table 2.

[0136] Table 1 Reaction results of propylene ammoxidation to produce acrylonitrile

[0137]

[0138]

[0139] *: A large amount of catalyst leakage occurred in Comparative Example 1, indicating that the reactor linear speed exceeded the reactor load capacity and normal production could not be achieved.

[0140] Table 2 Reaction results of methanol ammoxidation to produce hydrocyanic acid

[0141]

[0142] *: Comparative Example 3 not only has a low product yield, but also has a large amount of catalyst leakage, indicating that the reactor linear speed exceeds the reactor load capacity and cannot be produced normally.

[0143] This technical solution not only solves the explosion risk of the acrylonitrile and hydrocyanic acid fluidized bed reaction device, but also can greatly improve the production load and operation flexibility of the device.

[0144] As can be seen from Table 1, the linear speed of the acrylonitrile reaction of this patent can reach 1.2m / s, while the traditional acrylonitrile technology device has already experienced catalyst leakage when the linear speed reaches 1.0m / s, and the device cannot operate normally. At high linear speeds, the catalyst cannot be completely settled, not only does catalyst leakage occur, but also due to the high catalyst concentration in the settling section, secondary reactions will continue to occur, resulting in a decrease in the yield of acrylonitrile. The data in Table 1 illustrate: This technical solution can significantly increase the load of the device. In addition, the linear speed range of this technical solution is 0.5 to 1.2m / s, and the device operation flexibility is large.

[0145] As can be seen from Table 2, the patented hydrocyanic acid reaction line speed can reach 1.0m / s, while the traditional hydrocyanic acid technology device has already experienced a catalyst runaway phenomenon when the line speed reaches 0.8m / s, and the device cannot operate normally. At high line speeds, the hydrocyanic acid catalyst cannot be completely precipitated, not only does the catalyst runaway occur, but also due to the high catalyst concentration in the sedimentation section, secondary reactions will continue to occur, resulting in a decrease in the yield of hydrocyanic acid. The data in Table 2: This shows that the present technical solution can significantly increase the device load. In addition, the line speed range of the present technical solution is 0.3-1.0m / s, and the device has great operational flexibility.

Claims

1. A fluidized bed reaction device for producing acrylonitrile or hydrocyanic acid, characterized in that: The device comprises a reactor shell and reactor internals, wherein the reactor shell comprises, from bottom to top, an air plenum chamber of a lower cone portion, a dense phase reaction zone of a middle cylindrical portion, and a dilute phase settling zone formed by a combination of a cone section, a cylindrical section, and a spherical section from bottom to top; an air pressure drop distributor is arranged between the air plenum chamber and the dense phase reaction zone, and an air inlet is arranged on the air plenum chamber shell; a mixed gas distributor is arranged at the lower part of the dense phase reaction zone, and a mixed gas inlet pipe is connected to the inlet end of the mixed gas distributor, and the mixed gas distributor divides the dense phase reaction zone into a catalyst oxidation regeneration zone below and a main body dense phase reaction zone above, a cooling medium U-shaped tube bundle is arranged in the main body dense phase reaction zone, and a collecting main pipe of the cooling medium U-shaped tube bundle is connected to the cooling medium inlet and outlet pipes; a cyclone separator and a gas collecting chamber are arranged in the dilute phase settling zone, the material legs of the cyclone separator extend downward into the dense phase reaction zone, the top outlet of the cyclone separator is connected to the gas collecting chamber located at the top of the dilute phase settling zone, a reaction gas outlet is arranged at the top of the gas collecting chamber, and is connected to the reaction gas outlet pipe.

2. The fluidized bed reaction device according to claim 1, characterized in that: The air pressure drop distributor is located 100mm-300mm above the lower tangent line of the reactor, and includes a porous plate with uniform openings and a venturi distribution pipe arranged at the openings; the venturi distribution pipe consists of a monkey mouth, a distribution straight pipe, and a diffusion section, and the distribution straight pipe and the porous plate are connected by a diffusion section with a smooth curved surface structure.

3. The fluidized bed reaction device according to claim 2, characterized in that: The porosity of the porous plate is 10% to 20%, the aperture of the opening is 1.5 to 2 times the inner diameter of the distribution straight tube, the length of the distribution straight tube is 100mm to 200mm, the inner diameter is 15mm to 35mm, the diameter of the throat is 0.3 to 0.5 times the inner diameter of the distribution straight tube, and the diffusion angle of the throat and the distribution straight tube is 60 to 90°.

4. The fluidized bed reaction device according to claim 1, characterized in that: The mixed gas distributor comprises an air inlet main pipe, a gas branch pipe and a short air distribution pipe. The number of the air inlet main pipes is 1-6. The gas branch pipes are symmetrically distributed on both sides of the air inlet main pipe. A row of short air distribution pipes is arranged at the bottom of the air inlet main pipe. Two rows of short air distribution pipes are cross-symmetrically arranged on the lower side wall of the gas branch pipe. The angle between the two rows of short air distribution pipes is 40-60°.

5. The fluidized bed reaction device according to claim 1, characterized in that: The length of the short gas distribution pipe is 80mm-150mm, the diameter is 15mm-25mm, the spacing between two adjacent short gas distribution pipes in the same row on the gas branch pipe is 8-12 times the diameter of the distributed straight pipe, and the spacing follows a decreasing law, gradually decreasing from the air inlet end to the far end.

6. The fluidized bed reaction device according to claim 1, characterized in that: The cone angle of the air equalizing chamber is 60° to 120°, the air inlet is located at 1 / 3 to 1 / 2 of the cone height, a guide plate is arranged above the air inlet, the area of ​​the guide plate is 1.5 to 2 times the cross-sectional area of ​​the air inlet pipe, and the angle between the plane of the guide plate and the side of the cone is 60° to 100°; the total height of the dense phase reaction zone is 7m to 11m, of which the height of the catalyst oxidation regeneration zone is 400mm to 600mm, and the height of the main dense phase reaction zone is 6.7m to 10.5m; the diameter of the cylindrical section of the dilute phase sedimentation zone is 1.2 to 1.8 times that of the dense phase reaction zone, and the height is 0.6 to 0.9 times the height of the dense phase reaction zone, and the cone angle of the dilute phase sedimentation zone is 100° to 150°.

7. The fluidized bed reaction device according to claim 1, characterized in that: The cooling medium U-shaped tube bundle is a plurality of heat exchange tube bundles arranged vertically, the diameter of the heat exchange tube is between 50mm and 150mm, the spacing between adjacent heat exchange tubes is between 100mm and 200mm, and the length of the heat exchange tube is 0.98 to 1.0 times the height of the dense phase reaction zone.

8. The fluidized bed reaction device according to claim 1, characterized in that: The distance between the mixed gas distributor and the air pressure drop distributor is 400mm-600mm.

9. The fluidized bed reaction device according to claim 1, characterized in that: The volume of the gas collecting chamber is 0.02-0.05 times that of the dilute phase settling zone (zone III).

10. A process for producing acrylonitrile or hydrocyanic acid in a fluidized bed reactor, characterized in that: The fluidized bed reaction device according to claim 1 is used to produce acrylonitrile or hydrocyanic acid by the following steps: (1) Air enters the air equalizing chamber, is guided by the guide plate, is pressure-equalized in the air equalizing chamber, and is evenly distributed to the dense phase reaction zone through the air pressure drop distributor, contacts the catalyst bed, and fluidizes and regenerates the catalyst; (2) Ammonia and propylene (methanol) mixed gas is uniformly sprayed into the catalyst oxidation regeneration zone through a mixed gas distributor, where it contacts the hot catalyst, starts the reaction, and rapidly heats the reaction mixed gas; (3) The reaction gas stays in the catalyst oxidation regeneration zone for less than or equal to 0.3 seconds, and then enters the main dense phase reaction zone to continue the reaction, and the reaction heat is taken away by the cooling medium U-shaped tube bundle; (4) After the reaction is completed, the reaction gas carries the catalyst into the dilute phase settling zone, and the gas velocity is reduced to 0.3 to 0.5 times the linear velocity of the dense phase reaction zone, and the entrained catalyst is accelerated to settle; (5) In the dilute phase settling zone, the cyclone separator separates the entrained catalyst, and the separated catalyst returns to the dense phase reaction zone to continue to participate in the reaction. The separated gas is discharged through the gas collecting chamber to eventually form acrylonitrile or hydrocyanic acid product gas; Among them, when producing acrylonitrile, the mixed gas is ammonia and propylene, and the molar ratio of propylene:ammonia:air is 1:(1.05~1.1):(9~10); when producing hydrocyanic acid, the mixed gas is ammonia and methanol, and the molar ratio of methanol, ammonia and air is 1:(1.1~1.3):(9.8~1.3).

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