Reaction system and method for preparing o-nitrobenzaldehyde

Abstract

The reaction system comprises a bromination reaction kettle, a hydrolysis reaction kettle, an oxidation reaction kettle and a refining reaction kettle, and is characterized in that a feeding hole and an upper circulating pipe are arranged at the top end of the refining reaction kettle, and a lower circulating pipe is arranged at the bottom end of the refining reaction kettle; a product discharge port is formed in the side surface of the refining reaction kettle; and a filter plate is arranged in the refining reaction kettle. Through the synergistic effect of the rotatable filter plate and the lifting blocking frame, the fan-shaped blocking plate is in a vertical state during suction filtration, so that full-effect filtration is realized; when blockage is detected, the lifting blocking frame moves upwards to enable the fan-shaped blocking plate to horizontally close most of the filters, only a single flushing opening is reserved for high-pressure backwashing, the filters can be subjected to backwashing one by one in cooperation with a rotating structure of the filter plate, the problems that a traditional fixed filter plate is prone to blockage and not thorough in cleaning are effectively solved, and the filtering efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of o-nitrobenzaldehyde production, and in particular to a reaction system and method for preparing o-nitrobenzaldehyde. Background Art

[0002] o-Nitrobenzaldehyde is an important pharmaceutical and fine chemical intermediate, and its preparation process involves multiple steps such as bromination, hydrolysis, oxidation and refining. In the refining stage, the traditional process often uses a fixed filter plate to perform suction filtration on the crude product, but there are the following technical bottlenecks: In the prior art, the filter plate is mostly of a fixed structure. The filtrate passing through a single channel is likely to cause clogging of the filter holes. When backwashing, it is necessary to stop the machine to disassemble the filter plate or rely on manual high-pressure flushing. The cleaning efficiency is low and it is difficult to completely restore the filtering performance, seriously affecting the production continuity. Most of the existing refining reaction kettles adopt an independent stirring and circulation system, and the coordination between mechanical stirring and liquid circulation is poor, resulting in uneven pH adjustment, large crystal grains, and low product purity.

[0003] In view of the above problems, there is an urgent need to develop a reaction system integrating efficient filtration, intelligent backwashing and enhanced mixing functions to break through the bottlenecks of the prior art and improve the production efficiency and quality of o-nitrobenzaldehyde. Summary of the Invention

[0004] In order to solve the problems mentioned in the above background art, the present invention provides a reaction system and method for preparing o-nitrobenzaldehyde.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A reaction system and method for preparing o-nitrobenzaldehyde, including a bromination reaction kettle, a hydrolysis reaction kettle, an oxidation reaction kettle and a refining reaction kettle, characterized in that: a feeding port and an upper circulation pipe are provided at the top of the refining reaction kettle, a lower circulation pipe is provided at the bottom of the refining reaction kettle, a product discharge port is provided on the side of the refining reaction kettle, a filter plate is provided inside the refining reaction kettle, and the horizontal height of the product discharge port is greater than the horizontal height of the filter plate; An annular connecting pipe is provided between the upper circulation pipe and the lower circulation pipe, a first connecting port and a second connecting port are respectively provided on the annular connecting pipe, and a third connecting port is provided on the lower circulation pipe; The filter plate is rotatably installed inside the refining reaction kettle, a lifting blocking frame is provided below the filter plate, a flushing notch and a plurality of blocking notches are provided on the lifting blocking frame, a sector blocking plate is rotatably installed in the blocking notch, and a plurality of filters are installed on the filter plate.

[0006] Preferably, a first valve and a second valve are respectively arranged on both sides of the upper circulation pipe on the annular connecting pipe, a third valve and a fourth valve are respectively arranged on both sides of the lower circulation pipe on the annular connecting pipe, the third connection port is connected to the liquid inlet of the circulation pump, the second connection port is connected to the liquid outlet of the circulation pump, the first connection port is connected to the water adding pipeline, and a cooling jacket is arranged outside the refining reactor.

[0007] Preferably, one end of the upper circulation pipe extends from the top end of the refining reactor to the inside of the refining reactor and is rotatably connected with a first vertical shaft. Both sides of the bottom end of the first vertical shaft are connected with L-shaped branches, and a plurality of stirring blades are fixed on the L-shaped branches.

[0008] Preferably, the first vertical shaft, the L-shaped branches and the stirring blades are all hollow inside and communicate with the upper circulation pipe, and a plurality of liquid discharge holes are formed in the stirring blades.

[0009] Preferably, a first spur gear is fixed on the outside of the first vertical shaft, a first rotating motor is fixed on the top end of the refining reactor, the output shaft of the first rotating motor extends into the inside of the refining reactor and is fixed with a second spur gear, and the first spur gear meshes with the second spur gear.

[0010] Preferably, a second vertical shaft is rotatably installed inside the refining reactor through a bracket. The second vertical shaft penetrates through the filter plate, and the filter plate is rotatably installed on the outside of the second vertical shaft.

[0011] Preferably, a plurality of permanent magnets A are fixed on the outer side of the filter plate, a toothed ring is rotatably installed outside the refining reactor, a plurality of permanent magnets B are fixed on the toothed ring, the permanent magnets B correspond to the permanent magnets A one by one and attract each other, and a second rotating motor is fixedly installed outside the refining reactor. The output shaft of the second rotating motor is fixed with a third spur gear, and the third spur gear meshes with the toothed ring.

[0012] Preferably, a transmission box is fixed at the middle position of the lifting blocking frame. A rotating pipe is installed inside the transmission box. A first bevel gear is fixed on the outside of the rotating pipe. The installation rotating shaft of the sector blocking plate extends into the transmission box and is fixed with a second bevel gear. The second bevel gear meshes with the first bevel gear, and the plurality of second bevel gears do not contact each other. A spiral guide groove is arranged inside the rotating pipe, and the bottom end of the spiral guide groove communicates with a vertical guide groove. A limiting rod is fixed at the bottom end of the second vertical shaft, and one end of the limiting rod extends into the spiral guide groove.

[0013] Preferably, a lifting guide frame is fixed at the bottom end of the transmission box, a guide column is fixed inside the refining reactor, the guide column movably penetrates through the lifting guide frame through a guide hole, and a follow-up lifting ring is fixed on the lifting guide frame. A plurality of permanent magnets C are fixed on the follow-up lifting ring. An active lifting ring is arranged outside the refining reactor, the active lifting ring is driven to lift by a cylinder, and a plurality of permanent magnets D are fixed on the active lifting ring. The plurality of permanent magnets C and the plurality of permanent magnets D correspond one by one and attract each other.

[0014] A method for preparing o-nitrobenzaldehyde includes the following steps: S1: Bromination reaction Add water, o-nitrotoluene and carbon tetrachloride into the bromination reactor, dropwise add bromine and keep the temperature for reaction for 1 hour, then dropwise add 27.5% hydrogen peroxide solution. After stratification, separate the organic layer and the water layer; S2: Hydrolysis reaction Add the organic layer obtained from the bromination reaction into the hydrolysis reactor, add sodium carbonate solution and reflux and stir for 22 hours. After cooling to 50 °C, stratify and recover the bromine in the water layer; S3: Oxidation reaction Transfer the hydrolyzed organic layer to the oxidation reactor, dropwise add 60% nitric acid and keep the temperature and stir for 3 hours. After adding water, cool to below 20 °C, and filter by suction to obtain the crude o-nitrobenzaldehyde and the mother liquor; S4: Refining reaction Put the crude product into the refining reactor, add water and adjust the pH to 7-8, circulate and mix through the upper circulation pipe and the lower circulation pipe, turn on the cooling jacket to cool to below 20 °C, and start the circulating pump to filter by suction: During suction filtration, the lifting blocking frame moves downward, and the sector blocking plate rotates to the vertical state. The filtrate is filtered by the filter and discharged through the lower circulation pipe; If the filter is blocked, control the cylinder to drive the active lifting ring to drive the lifting blocking frame to move upward, and the sector blocking plate rotates to the horizontal state to block most of the filters, only leaving the filter corresponding to the flushing notch for backwashing. At the same time, drive the filter plate to rotate by the second rotating motor to flush each filter one by one; S5: Product collection.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Efficient filtration and anti-blocking design Through the synergistic effect of the rotatable filter plate and the lifting blocking frame, the sector blocking plate is in the vertical state during suction filtration to achieve full-effect filtration; when blockage is detected, the lifting blocking frame moves upward to make the sector blocking plate close most of the filters horizontally, only leaving a single flushing port for high-pressure backwashing. With the rotating structure of the filter plate, each filter can be backwashed one by one, effectively solving the problems of easy blockage and incomplete cleaning of the traditional fixed filter plate, and improving the filtration efficiency.

[0016] 2. Intelligent backwashing control Adopt a magnetic coupling drive mechanism (the permanent magnets A / B / C / D are linked with the toothed ring and the active lifting ring), and the lifting of the internal lifting baffle and the opening / closing angle of the sector baffle can be accurately controlled through an external cylinder. The unique spiral guide groove and limit rod design enables the sector baffle to automatically rotate 90° during the lifting process, ensuring a quick switch to the backwashing mode when blocked, and reducing manual intervention by 60%.

[0017] 3. Strengthened mixing and circulation efficiency The upper circulation pipe is integrated with hollow stirring blades, which realizes double mixing of liquid flow injection and mechanical stirring under the drive of a circulation pump. Cooperating with a cooling jacket for precise temperature control, it improves the pH adjustment in the refining stage and the reaction uniformity in the crystallization process, enhancing the product purity. The multi-valve design of the annular connecting pipe supports the quick switching of water addition, circulation, and suction filtration modes, improving the operation efficiency. Brief description of the drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 Is the overall flowchart of the present invention; Figure 2 Is the front view of the refining reactor of the present invention; Figure 3 Is the three-dimensional view of the refining reactor of the present invention; Figure 4 Is the right view of the refining reactor of the present invention; Figure 5 Is the cross-sectional view of the refining reactor of the present invention; Figure 6 Is the structural schematic diagram of the lower half of the refining reactor of the present invention; Figure 7 Is the top view of the filter plate in the refining reactor of the present invention; Figure 8 Is the bottom view of the lifting baffle in the refining reactor of the present invention; Figure 9 Is the schematic diagram of the cooperation relationship between the lifting baffle and the filter plate in the refining reactor of the present invention; Figure 10 Is the three-dimensional view of the first perspective of the lifting baffle in the refining reactor of the present invention; Figure 11It is a second perspective three-dimensional view of the lifting blocking frame in the refining reactor of the present invention; Figure 12 It is a schematic diagram showing the sector blocking plate of the lifting blocking frame in the refining reactor of the present invention rotating to the vertical state when moving downward; Figure 13 It is a cross-sectional view of the transmission box in the refining reactor of the present invention; Figure 14 It is a cross-sectional view of the rotating pipe in the refining reactor of the present invention; Figure 15 It is a schematic diagram showing the cooperation of the active lifting ring and the follower lifting ring in the refining reactor of the present invention; In the figure: 1, refining reactor; 101, feeding port; 102, lower circulation pipe; 103, annular connecting pipe; 1031, first connection port; 1032, second connection port; 1033, first valve; 1034, second valve; 1035, third valve; 1036, fourth valve; 104, cooling jacket; 105, product discharge port; 106, upper circulation pipe; 1061, first vertical shaft; 1062, L-shaped branch; 1063, stirring blade; 1064, drain hole; 1065, first spur gear; 1066, first rotating motor; 1067, second spur gear; 2, filter plate; 201, filter; 202, bracket; 203, second vertical shaft; 2031, limit rod; 204, permanent magnet A; 3, tooth ring; 301, permanent magnet B; 302, second rotating motor; 303, third spur gear; 4, lifting blocking frame; 401, transmission box; 402, sector blocking plate; 4021, second bevel gear; 403, lifting guide frame; 404, guide post; 405, follower lifting ring; 4051, permanent magnet C; 406, rotating pipe; 4061, first bevel gear; 4062, spiral guide groove; 4063, vertical guide groove; 5, cylinder; 501, active lifting ring; 502, permanent magnet D; 6, bromination reactor; 7, hydrolysis reactor; 8, oxidation reactor. Detailed implementation manners

[0020] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. Embodiment 1

[0021] Refer to Figures 1-15, A reaction system and method for preparing o-nitrobenzaldehyde, including a bromination reaction kettle 6, a hydrolysis reaction kettle 7, an oxidation reaction kettle 8 and a refining reaction kettle 1. The top of the refining reaction kettle 1 is provided with a feeding port 101 and an upper circulation pipe 106, the bottom of the refining reaction kettle 1 is provided with a lower circulation pipe 102, the side of the refining reaction kettle 1 is provided with a product discharge port 105, and a filter plate 2 is arranged inside the refining reaction kettle 1. The horizontal height of the product discharge port 105 is greater than the horizontal height of the filter plate 2; First, add water, (o-)nitrotoluene, and carbon tetrachloride to the bromination reaction kettle 6, dropwise add bromine, keep warm for 1 h, start to dropwise add 27.5% H2O2, separate the layers, the water layer enters sewage treatment, and the organic layer is directly reused, or after distilling and recovering carbon tetrachloride, it enters sewage treatment; Then add the solid bromide to the hydrolysis reaction kettle 7, add a soda ash solution, reflux and stir for 22 h, cool down to 50 °C and separate the layers. The water layer is used for bromine recovery or directly sold outside; Put the hydrolyzed organic layer into the oxidation reaction kettle 8, start to dropwise add 60% nitric acid, keep warm and stir for 3 h, then add water to the kettle, stop stirring after stirring for 5 minutes, cool down to below 20 °C, and filter by suction to obtain the crude product of o-(p-)nitrobenzaldehyde and the mother liquor; Put the crude product into the refining reaction kettle 1, add water, stir and adjust the pH value to 7-8, cool down to below 20 °C, and filter by suction to obtain the product of o-(p-)nitrobenzaldehyde. The filtrate is neutralized with the oxidation wastewater and then enters sewage treatment; An annular connecting pipe 103 is arranged between the upper circulation pipe 106 and the lower circulation pipe 102. The annular connecting pipe 103 is respectively provided with a first connection port 1031 and a second connection port 1032, and the lower circulation pipe 102 is provided with a third connection port 1021; The filter plate 2 is rotatably installed inside the refining reaction kettle 1. An elevating blocking frame 4 is arranged below the filter plate 2. The elevating blocking frame 4 is provided with a flushing notch and a plurality of blocking notches. A sector-shaped blocking plate 402 is rotatably installed in the blocking notches, and a plurality of filters 201 are installed on the filter plate 2; The crude product is put into the refining reaction kettle 1 through the feeding port 101. A first valve 1033 and a second valve 1034 are respectively arranged on both sides of the upper circulation pipe 106 on the annular connecting pipe 103. A third valve 1035 and a fourth valve 1036 are respectively arranged on both sides of the lower circulation pipe 102 on the annular connecting pipe 103. The third connection port 1021 is connected to the liquid inlet of the circulation pump, the second connection port 1032 is connected to the liquid outlet of the circulation pump, the first connection port 1031 is connected to the water adding pipeline, and a cooling jacket 104 is arranged outside the refining reaction kettle 1; When adding water to the refining reactor 1, the first valve 1033, the third valve 1035 and the fourth valve 1036 are closed, and the second valve 1034 is opened. Water enters the refining reactor 1 from the first connection port 1031 through the annular connecting pipe 103 and then through the upper circulation pipe 106. After adding water, the circulation pump can be started while starting the stirring to enter the circulation mode: At this time, the third valve 1035 is closed, the first valve 1033 is opened, the second valve 1034 and the fourth valve 1036 are closed. Driven by the circulation pump, the liquid flows through the annular connecting pipe 103 through the lower circulation pipe 102 and then enters the refining reactor 1 through the upper circulation pipe 106, and can circulate reciprocally to promote mixing, and can assist stirring to improve the refining efficiency; After the pH value is adjusted to 7-8, the circulation and stirring are stopped, and cooling water is introduced into the cooling jacket 104 to cool down to below 20°C. The first valve 1033, the second valve 1034, the third valve 1035 and the fourth valve 1036 are closed, and the waste water is pumped out through the lower circulation pipe 102 by the circulation pump. The o-(p-)nitrobenzaldehyde product passes through the filter 201 on the filter plate 2 and remains inside the refining reactor 1. During the filtering process, the lifting blocking frame 4 moves downward away from the filter plate 2, and the sector blocking plate 402 rotates to the vertical state ( Figure 12 ), at this time, the sector blocking plate 402 on the lifting blocking frame 4 will not cause any obstruction to the filter 201, and efficient suction filtration can be carried out; If the filter 201 is blocked during suction filtration, resulting in an increase in the suction filtration pressure, the backwashing mode can be started at this time. During backwashing, the sector blocking plate 402 is rotated to the horizontal mode, and the lifting blocking frame 4 is controlled to move upward ( Figures 8-10 state), at this time, the sector blocking plate 402 can block most of the filter 201, and only the filter 201 facing the flushing gap can allow the backwashing liquid to flow in, so as to improve the water pressure of the backwashing of a single filter 201 and improve the backwashing effect. Since the filter plate 2 is rotatably installed inside the refining reactor 1, the filter plate 2 can rotate relative to the lifting blocking frame 4, so as to change the position of the flushing gap relative to the filter 201, so as to backwash different filters 201 and ensure that each filter 201 can be backwashed; The product after suction filtration is taken out through the product discharge port 105. Example 2

[0022] Refer to Figures 1-15, the difference between this embodiment and embodiment 1 is that one end of the upper circulation pipe 106 extends from the top of the refining reactor 1 to the inside of the refining reactor 1 and is rotatably connected to the first vertical shaft 1061, both sides of the bottom end of the first vertical shaft 1061 are connected to L-shaped branches 1062, a plurality of stirring blades 1063 are fixed on the L-shaped branch 1062, the first vertical shaft 1061, the L-shaped branch 1062 and the stirring blade 1063 are hollow inside and communicated with the upper circulation pipe 106, a plurality of drainage holes 1064 are opened on the stirring blade 1063, a first spur gear 1065 is fixed to the outside of the first vertical shaft 1061, a first rotating motor 1066 is fixed to the top of the refining reactor 1, the output shaft of the first rotating motor 1066 extends to the inside of the refining reactor 1 and is fixed to a second spur gear 1067, and the first spur gear 1065 is meshed with the second spur gear 1067; By turning on the first rotating motor 1066, the first vertical shaft 1061 can be driven to rotate through the engagement of the first spur gear 1065 and the second spur gear 1067, and the material is then stirred by the stirring blades 1063. During the stirring, the circulating liquid is continuously and dispersedly ejected through the drainage hole 1064, which can greatly improve the mixing degree of the material and improve the refining efficiency. Example 3

[0023] Reference Figures 1-15 , the difference between this embodiment and embodiment 1 is that a second vertical shaft 203 is rotatably mounted inside the refining reactor 1 through a bracket 202, the second vertical shaft 203 penetrates the filter plate 2, and the filter plate 2 is rotatably mounted outside the second vertical shaft 203, a plurality of permanent magnets A204 are fixed to the outside of the filter plate 2, a gear ring 3 is rotatably mounted outside the refining reactor 1, a plurality of permanent magnets B301 are fixed on the gear ring 3, the permanent magnets B301 correspond to the permanent magnets A204 one by one and attract each other, and a second rotating motor 302 is fixedly mounted outside the refining reactor 1, a third spur gear 303 is fixed to the output shaft of the second rotating motor 302, and the third spur gear 303 is meshed with the gear ring 3; By having permanent magnet B301 correspond to permanent magnet A204 one by one and attracting each other, the gear ring 3 and filter plate 2 can be kept relatively prohibited through the side wall of the refining reactor 1. By turning on the second rotating motor 302, the third spur gear 303 can be driven to rotate, and then the gear ring 3 can be driven to rotate, and the filter plate 2 can be driven to rotate through magnetic transmission, so that the relative position of the filter 201 on the filter plate 2 can be adjusted in the backwash mode to ensure that each filter 201 can be flushed. Example 4

[0024] Reference Figures 1-15, the difference between this embodiment and Embodiment 3 is that a transmission box 401 is fixed at the middle position of the lifting and blocking frame 4. A rotating tube 406 is installed inside the transmission box 401. A first bevel gear 4061 is fixed to the outside of the rotating tube 406. The installation rotating shaft of the sector blocking plate 402 extends into the transmission box 401 and is fixed with a second bevel gear 4021. The second bevel gear 4021 meshes with the first bevel gear 4061, and the multiple second bevel gears 4021 do not contact each other. A spiral guide groove 4062 is provided inside the rotating tube 406, and a vertical guide groove 4063 communicates with the bottom end of the spiral guide groove 4062. A limiting rod 2031 is fixed to the bottom end of the second vertical shaft 203, and one end of the limiting rod 2031 extends into the spiral guide groove 4062; When the lifting and blocking frame 4 moves downward, the second vertical shaft 203 will move vertically relative to the rotating tube 406. When the limiting rod 2031 moves along the spiral guide groove 4062, it will drive the rotating tube 406 to rotate through a linkage method. Then, the sector blocking plate 402 is driven to rotate by the meshing of the second bevel gear 4021 and the first bevel gear 4061. When the lifting and blocking frame 4 is at the highest position, the sector blocking plate 402 is in a horizontal state. When the lifting and blocking frame 4 is at the lowest position, the sector blocking plate 402 is in a vertical state, achieving the purpose of automatic switching. Due to the existence of the vertical guide groove 4063, when the lifting and blocking frame 4 moves upward, the sector blocking plate 402 will be converted to a horizontal state in advance and continue to move upward in a horizontal state and contact the lower end of the filter 201, maintaining a tighter blockage of the filter 201. When the lifting and blocking frame 4 moves downward, it moves a certain distance first, and then the sector blocking plate 402 starts to rotate, which can prevent interference between the sector blocking plate 402 and the filter plate 2.

[0025] Among them, a lifting guide frame 403 is fixed to the bottom end of the transmission box 401. A guide post 404 is fixed inside the refined reaction kettle 1. The guide post 404 passes through the lifting guide frame 403 through a guide hole, and a follow-up lifting ring 405 is fixed on the lifting guide frame 403. A plurality of permanent magnets C4051 are fixed on the follow-up lifting ring 405. An active lifting ring 501 is provided outside the refined reaction kettle 1. The active lifting ring 501 is lifted and lowered by a cylinder 5, and a plurality of permanent magnets D502 are fixed on the active lifting ring 501. The plurality of permanent magnets C4051 and the plurality of permanent magnets D502 correspond one by one and attract each other; Through the magnetic attraction between the permanent magnet C4051 and the permanent magnet D502, it is ensured that the active lifting ring 501 and the follow-up lifting ring 405 move synchronously up and down. Furthermore, the lifting and blocking frame 4 can be driven to lift and lower from the outside of the refined reaction kettle 1 through the telescopic movement of the cylinder 5, so as to efficiently switch between the suction filtration and backwashing states.

[0026] A method for preparing o-nitrobenzaldehyde includes the following steps: S1: Bromination Reaction Add water, o-nitrotoluene, and carbon tetrachloride into the bromination reactor 6. Dropwise add bromine and keep the reaction at a constant temperature for 1 hour. Subsequently, dropwise add 27.5% hydrogen peroxide solution. After liquid separation, separate the organic layer from the aqueous layer; S2: Hydrolysis Reaction Add the organic layer obtained from the bromination reaction into the hydrolysis reactor 7. Add soda ash solution and reflux with stirring for 22 hours. After cooling to 50 °C, perform liquid separation and recover bromine in the aqueous layer; S3: Oxidation Reaction Transfer the hydrolyzed organic layer to the oxidation reactor 8. Dropwise add 60% nitric acid and keep stirring at a constant temperature for 3 hours. Add water and then cool to below 20 °C. Filter by suction to obtain crude o-nitrobenzaldehyde and mother liquor; S4: Refining Reaction Put the crude product into the refining reactor 1. Add water and adjust the pH to 7 - 8. Circulate and mix through the upper circulation pipe 106 and the lower circulation pipe 102. Open the cooling jacket 104 to cool to below 20 °C, and start the circulating pump for suction filtration: During suction filtration, the lifting and blocking frame 4 moves downward, and the fan-shaped blocking plate 402 rotates to the vertical state. The filtrate is filtered by the filter 201 and discharged through the lower circulation pipe 102; If the filter is blocked, control the air cylinder 5 to drive the active lifting ring 501 to drive the lifting and blocking frame 4 to move upward. The fan-shaped blocking plate 402 rotates to the horizontal state to block most of the filter, and only the filter corresponding to the flushing notch is reserved for backwashing. At the same time, drive the filter plate 2 to rotate by the second rotating motor 302 to flush each filter one by one; S5: Product Collection In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0027] In the present invention, unless otherwise clearly defined and limited, terms such as "arranged", "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, and it may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] The control mode of the present invention is automatically controlled by a controller. The control circuit of the controller can be realized by simple programming by those skilled in the art. The provision of power also belongs to the common knowledge in the art, and the present invention is mainly used to protect mechanical devices. Therefore, the control mode and circuit connection of the present invention will not be explained in detail.

[0029] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered by the protection scope of the present invention.

Claims

1. A reaction system for preparing o-nitrobenzaldehyde, comprising a bromination reaction kettle (6), a hydrolysis reaction kettle (7), an oxidation reaction kettle (8) and a refining reaction kettle (1), characterized in that: The top of the refining reactor (1) is provided with a feeding port (101) and an upper circulation pipe (106), the bottom of the refining reactor (1) is provided with a lower circulation pipe (102), the side of the refining reactor (1) is provided with a product discharge port (105), a filter plate (2) is arranged inside the refining reactor (1), and the horizontal height of the product discharge port (105) is greater than the horizontal height of the filter plate (2). An annular connecting pipe (103) is arranged between the upper circulation pipe (106) and the lower circulation pipe (102). A first connection port (1031) and a second connection port (1032) are respectively arranged on the annular connecting pipe (103), and a third connection port (1021) is arranged on the lower circulation pipe (102). The filter plate (2) is rotatably installed inside the refining reactor (1). An elevating blocking frame (4) is arranged below the filter plate (2). The elevating blocking frame (4) is provided with a flushing notch and a plurality of blocking notches. Sector-shaped blocking plates (402) are rotatably installed in the blocking notches, and a plurality of filters (201) are installed on the filter plate (2).

2. The reaction system for preparing o-nitrobenzaldehyde according to claim 1, characterized in that: First valves (1033) and second valves (1034) are respectively arranged on both sides of the upper circulation pipe (106) on the annular connecting pipe (103), and third valves (1035) and fourth valves (1036) are respectively arranged on both sides of the lower circulation pipe (102) on the annular connecting pipe (103). Moreover, the third connection port (1021) is connected to the liquid inlet of the circulation pump, the second connection port (1032) is connected to the liquid outlet of the circulation pump, the first connection port (1031) is connected to the water adding pipeline, and a cooling jacket (104) is arranged outside the refining reactor (1).

3. The reaction system for preparing o-nitrobenzaldehyde according to claim 1, characterized in that: One end of the upper circulation pipe (106) extends from the top of the refining reactor (1) to the inside of the refining reactor (1) and is rotatably connected to a first vertical shaft (1061). Both sides of the bottom end of the first vertical shaft (1061) are connected with L-shaped branches (1062), and a plurality of stirring blades (1063) are fixed on the L-shaped branches (1062).

4. A reaction system for preparing o-nitrobenzaldehyde according to claim 3, characterized in that: The first vertical shaft (1061), the L-shaped branches (1062) and the stirring blades (1063) are all hollow inside and are communicated with the upper circulation pipe (106). A plurality of liquid discharge holes (1064) are arranged on the stirring blades (1063).

5. The reaction system for preparing o-nitrobenzaldehyde according to claim 4, characterized in that: A first straight gear (1065) is fixed on the outside of the first vertical shaft (1061). A first rotating motor (1066) is fixed on the top of the refining reactor (1). The output shaft of the first rotating motor (1066) extends into the refining reactor (1) and is fixed with a second straight gear (1067). The first straight gear (1065) meshes with the second straight gear (1067).

6. The reaction system for preparing o-nitrobenzaldehyde according to claim 1, characterized in that: A second vertical shaft (203) is rotatably installed inside the refining reactor (1) through a bracket (202). The second vertical shaft (203) penetrates through the filter plate (2), and the filter plate (2) is rotatably installed on the outside of the second vertical shaft (203).

7. A reaction system for preparing o-nitrobenzaldehyde according to claim 6, characterized in that: A plurality of permanent magnets A (204) are fixed on the outer side of the filter plate (2). A toothed ring (3) is rotatably installed outside the refining reactor (1). A plurality of permanent magnets B (301) are fixed on the toothed ring (3). The permanent magnets B (301) correspond to the permanent magnets A (204) one by one and attract each other. A second rotating motor (302) is fixedly installed outside the refining reactor (1). A third spur gear (303) is fixed on the output shaft of the second rotating motor (302). The third spur gear (303) meshes with the toothed ring (3).

8. A reaction system for preparing o-nitrobenzaldehyde according to claim 6, characterized in that: A transmission box (401) is fixed at the middle position of the lifting blocking frame (4). A rotating pipe (406) is installed inside the transmission box (401). A first bevel gear (4061) is fixed on the outside of the rotating pipe (406). The installation rotating shaft of the fan-shaped blocking plate (402) extends into the transmission box (401) and is fixed with a second bevel gear (4021). The second bevel gear (4021) meshes with the first bevel gear (4061). And the plurality of second bevel gears (4021) do not contact each other. A spiral guide groove (4062) is provided inside the rotating pipe (406). And the bottom end of the spiral guide groove (4062) communicates with a vertical guide groove (4063). A limiting rod (2031) is fixed at the bottom end of the second vertical shaft (203). One end of the limiting rod (2031) extends into the spiral guide groove (4062).

9. The reaction system for preparing o-nitrobenzaldehyde according to claim 8, wherein: A lifting guide frame (403) is fixed at the bottom end of the transmission box (401). A guide post (404) is fixed inside the refining reactor (1). The guide post (404) movably penetrates through the lifting guide frame (403) through a guide hole. And a follower lifting ring (405) is fixed on the lifting guide frame (403). A plurality of permanent magnets C (4051) are fixed on the follower lifting ring (405). An active lifting ring (501) is provided outside the refining reactor (1). The active lifting ring (501) is driven to lift by a cylinder (5). And a plurality of permanent magnets D (502) are fixed on the active lifting ring (501). The plurality of permanent magnets C (4051) correspond to the plurality of permanent magnets D (502) one by one and attract each other.

10. A method for preparing o-nitrobenzaldehyde, which is prepared by using a reaction system for preparing o-nitrobenzaldehyde as described in claim 9, characterized in that, Comprising the following steps: S1: Bromination reaction Water, o-nitrotoluene and carbon tetrachloride are added to the bromination reactor (6). Bromine is added dropwise and the reaction is kept warm for 1 hour. Subsequently, 27.5% hydrogen peroxide solution is added dropwise. After stratification, the organic layer and the water layer are separated. S2: Hydrolysis reaction The organic layer obtained from the bromination reaction is added to the hydrolysis reactor (7). Soda ash solution is added and refluxed with stirring for 22 hours. After cooling to 50 °C, stratification is carried out, and bromine in the water layer is recovered. S3: Oxidation reaction The hydrolyzed organic layer is transferred to the oxidation reactor (8). 60% nitric acid is added dropwise and stirred while keeping warm for 3 hours. After adding water, it is cooled to below 20 °C, and crude o-nitrobenzaldehyde and mother liquor are obtained by suction filtration. S4: Refining reaction The crude product is put into the refining reactor (1). Water is added and the pH is adjusted to 7 - 8. It is circulated and mixed through the upper circulation pipe (106) and the lower circulation pipe (102). The cooling jacket (104) is opened to cool down to below 20 °C, and the circulating pump is started for suction filtration: During suction filtration, the lifting and blocking frame (4) moves downward, and the sector blocking plate (402) rotates to the vertical state. The filtrate is filtered by the filter (201) and discharged through the lower circulation pipe (102). If the filter is blocked, the control cylinder (5) drives the active lifting ring (501) to drive the lifting and blocking frame (4) to move upward. The sector blocking plate (402) rotates to the horizontal state to block most of the filters, and only the filters corresponding to the flushing gaps are reserved for backwashing. At the same time, the filter plate (2) is driven by the second rotating motor (302) to rotate, and the filters are flushed one by one. S5: Product collection.

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