A continuous pipeline oxidation device and process for preparing nitrobenzoic acid

Abstract

The present invention discloses a continuous pipeline oxidation device and process for preparing nitrobenzoic acid, and the present invention relates to the technical field of nitrobenzoic acid preparation equipment. The continuous pipeline oxidation device and process for preparing nitrobenzoic acid can, by setting a synchronous driving mechanism, after the material is fed into the inner side of the reaction kettle, while stirring, make the sealing cover tightly press and seal the feed inlet, and can ensure that the sealing cover always covers the feed inlet during the stirring process. When the stirring is over, the feed inlet can be automatically opened. The opening and closing of the sealing cover realizes automation and synchronization with the stirring component, without the need for manual separate operation. Moreover, due to the mechanical linkage with the working of the stirring component, the timeliness of the opening and closing of the sealing cover is ensured. By setting the stirring component, vertical stirring from top to bottom and from bottom to top can be realized in the reaction kettle during stirring, thus avoiding the phenomenon that a large amount of materials always deposit at the bottom of the reaction kettle, and greatly improving the efficiency and quality of stirring.

Description

Technical Field

[0001] The present invention relates to the technical field of nitrobenzoic acid preparation equipment, and specifically to a continuous pipeline oxidation equipment and process for preparing nitrobenzoic acid. Background Art

[0002] The preparation of nitrobenzoic acid substances mostly uses a single reaction kettle. There are various raw material conveying pipes for introducing reaction substances in the reaction kettle. In the early stage, due to the high solubility of various substances, the reaction is rapid. In the later stage, due to the decrease in raw material concentration, the reaction slows down or even stagnates. And a method for continuously oxidizing nitrobenzoic acid by intersection disclosed in the existing Chinese patent CN114671766A. The equipment adopted by this method includes a reaction kettle, a non-driven gas-liquid integrated part, and an intersection box; a nitro toluene raw material liquid, a nitric acid solution, and oxygen are introduced into the reaction kettle to form a product and a reaction mixture. Among them, the nitro toluene raw material liquid and the product float at the corresponding positions on the liquid surface of the reaction mixture in the reaction kettle due to the increase in the density of the overall reaction system; among them, the reaction mixture is introduced into three channels of the non-driven gas-liquid integrated part through a circulation pump connected to the bottom of the reaction kettle. The problem solved by this technical solution is: how to optimize the preparation process and improve production efficiency;

[0003] The method for continuously oxidizing nitrobenzoic acid by intersection provided by this patent uses a reaction kettle of conventional technology for production. The structure of the reaction kettle in the existing technology is mostly like an automatic feeding kettle for the production of p-nitrobenzoic acid disclosed in Chinese patent CN219051262U, which relates to the technical field of p-nitrobenzoic acid production, and specifically includes a tank body. A connecting bracket is vertically installed at the bottom edge of the tank body. A discharge pipe is coaxially installed at the bottom inside the tank body. A connecting flange is installed at the bottom of the discharge pipe. A rotating rod is coaxially arranged inside the tank body. The top of the rotating rod passes through the tank body through a rotating bearing and is coaxially installed with a driving motor. The driving motor is arranged on the top of the tank body. When the present utility model is used, through the correspondence between the arc-shaped plate and the arc-shaped groove, when feeding materials into the reaction kettle, as the rotating rod continuously rotates, the arc-shaped groove is in a continuously opening and closing switching state, and the fully mixed p-nitrotoluene and catalyst are intermittently operated to enter the reaction kettle, so as to buffer the passing process of p-nitrotoluene and catalyst at the discharge pipe, preventing p-nitrotoluene and catalyst from accumulating too much and blocking the discharge pipe; when the reaction kettle in the existing technology is used, the feeding is carried out by opening the feeding port cover. After the feeding is completed, the cover of the reaction kettle is manually closed, and then during the reaction catalysis process, the stirring structure is rotated to stir the reaction materials to improve the mixing uniformity of the materials and the catalyst and enhance the reaction efficiency. However, such an operation has problems of inconvenient operation and poor stirring and mixing efficiency because it requires manual opening and closing of the cover and can only perform radial rotation stirring. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] In view of the deficiencies of the prior art, the present invention provides a continuous pipeline oxidation device and process for preparing nitrobenzoic acid, which solves the problems of cumbersome operation and poor stirring and mixing efficiency of the reaction kettle for preparing nitrobenzoic acid in the existing conventional technology.

[0006] (2) Technical solutions

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions: A continuous pipeline oxidation device for preparing nitrobenzoic acid, comprising a reaction kettle, a junction box and a non-driven gas-liquid integration component. A gas driving component is further installed on the top of the junction box. The top of the reaction kettle is connected to the intake end of the gas driving component through a first pipeline, and a booster pump is installed on the first pipeline. The bottom of the reaction kettle is connected to the liquid inlet end of the non-driven gas-liquid integration component through a second pipeline. The gas inlet end of the non-driven gas-liquid integration component is connected to the outlet end of the gas driving component through a third pipeline. The discharge end of the non-driven gas-liquid integration component is connected to the top of the reaction kettle. The upper end of the reaction kettle is further connected to the junction box through a fourth pipeline. A circulation pump is also installed on the second pipeline. The junction box is further connected to a nitric acid solution storage tank through a fifth pipeline. The reaction kettle further includes a feed inlet provided at the top of the reaction kettle, and a sealing cover is rotatably installed on the feed inlet. A stirring assembly is installed in the middle of the reaction kettle. A synchronous driving mechanism is further fixed on the top of the reaction kettle. The synchronous driving mechanism is used to drive the stirring assembly to work and can close the sealing cover while the stirring assembly is pneumatically driven, and open the sealing cover while the stirring assembly stops.

[0008] Preferably, the reaction kettle further includes support rods fixed on the outer wall of the reaction kettle at equal angles and a support plate fixed at the bottom of the support rods.

[0009] Preferably, a ring-shaped convex edge is formed at the top of the feed inlet, and a rubber gasket is fixed on the top of the ring-shaped convex edge.

[0010] Preferably, the stirring assembly includes a transmission shaft, a reciprocating lead screw, a moving block, stirring blades, convex blocks and grooves. The middle of the reaction kettle is rotatably connected to the transmission shaft through a bearing. The lower end of the transmission shaft is fixed with a reciprocating lead screw. The lower end of the reciprocating lead screw is rotatably connected to the inner wall of the reaction kettle through a bearing. A moving block is fitted on the outer side of the reciprocating lead screw. Stirring blades are fixed on the moving block. Convex blocks are formed on the outer wall of the stirring blades. Grooves are symmetrically formed on the inner wall of the reaction kettle. The convex blocks are slidably connected to the inner walls of the grooves.

[0011] Preferably, a rotating rod is fixed to one side of the sealing cover close to the stirring assembly. The rotating rod is rotatably connected to the outer wall of the feed inlet through a bearing. A torsion spring is sleeved on the end of the rotating rod. One end of the torsion spring is fixed to the outer wall of the rotating rod, and the other end of the torsion spring is fixed to the outer wall of the feed inlet.

[0012] Preferably, the synchronous driving mechanism includes a motor, a worm, a worm gear, a gear, a connecting piece, a push rod, a sliding block, a pushing plate, a rack, a second spring and a limiting strip. A motor is fixed to the top of the reaction kettle. The output end of the motor is fixed with a worm. The worm is rotatably connected to the top of the reaction kettle through a bearing. The top of the transmission shaft is fixed with a worm gear. The worm gear is meshed with the worm. A gear is fixed to the end of the worm. Connecting pieces are symmetrically fixed to one side of the sealing cover close to the rotating rod. A push rod is rotatably connected between the two connecting pieces through a pin. The lower end of the push rod is rotatably connected with a sliding block through a pin. The sliding block is slidably connected to the outer wall of the feed inlet. The bottom of the sliding block is arc-shaped. A pushing plate is slidably connected to one side of the top of the reaction kettle close to the sliding block. The top surface of the pushing plate is inclined. The bottom of the sliding block is in pressing contact with the top surface of the pushing plate. A rack is fixed to one side of the pushing plate close to the gear. The rack is meshed with the gear. A second spring is fixed to the outer wall of the pushing plate far from the sliding block. The side of the second spring far from the pushing plate is fixed to the top of the reaction kettle. An inverted L-shaped limiting strip is fixed to one side of the top of the reaction kettle close to the second spring. The pushing plate is in pressing contact with the outer wall of the limiting strip.

[0013] Preferably, a first slide rail is fixed to the top of the reaction kettle on one side of the rack and directly below the rack. A first slide bar fixed to the outer wall of the pushing plate is slidably connected to the outer wall of the first slide rail.

[0014] Preferably, second slide rails are symmetrically fixed to the outer wall of the feed inlet on one side close to the sliding block. The sliding block is slidably connected to the outer wall of the second slide rail through a chute.

[0015] The present invention also provides a process for preparing nitrobenzoic acid by a continuous pipeline oxidation device for preparing nitrobenzoic acid. The above-mentioned continuous pipeline oxidation device for preparing nitrobenzoic acid is used for preparation. The process includes the following steps:

[0016] 1), A nitro toluene raw material liquid, a nitric acid solution and oxygen are introduced into the reaction kettle through the feed inlet together in an existing ratio to form a product and a reaction mixture. At the same time, nitric oxide gas is also generated. Nitric oxide and oxygen generate nitrogen dioxide gas. As the reaction temperature increases, the density of the product nitrobenzoic acid increases. Therefore, the nitro toluene raw material liquid and the product float on the liquid level position of the reaction mixture due to the increase in the density of the overall reaction system.

[0017] 2) The reaction mixture is introduced into the non-driven gas-liquid integrated component through a circulation pump connected to the bottom of the reaction kettle to achieve the contact between nitrogen dioxide and water to generate nitric acid solution, and then returns to the reaction kettle to form a cycle, thereby continuously improving the reaction efficiency.

[0018] 3) The gas exported from the first pipeline on the reaction kettle is pressurized to a sufficient pressure by a booster pump and enters the gas-driven component to drive the gas-driven component to rotate, and then returns to the non-driven gas-liquid integrated component, and is mixed with the liquid in the non-driven gas-liquid integrated component and enters the reaction kettle.

[0019] 4) A part of the solution with raw materials and products in the reaction kettle is introduced into the junction box, and the nitric acid solution in the nitric acid solution storage tank is introduced into the upper end of the junction box. In this way, the substances introduced from the upper end and the lower end move relatively up and down and react in the junction box. At this time, the concentration of the nitro toluene raw material solution is high at the lower end, and the concentration of the nitric acid solution in the nitric acid solution storage tank is high at the upper end; at the lower end position, the high-concentration nitro toluene raw material solution reacts with the low-concentration nitric acid solution, and at the upper end position, the low-concentration nitro toluene raw material solution reacts with the high-concentration nitric acid solution. Through such a configuration, the product is discharged after standing and stratifying.

[0020] Preferably, during the process of discharging the product in step 4), by using the characteristics that the density of the nitric acid solution is heavier than that of the nitro toluene raw material liquid and lighter than that of nitrobenzoic acid, the final product is exported from the upper end outlet of the junction box, and the unreacted raw materials are exported from the lower end outlet of the junction box.

[0021] (III) Beneficial effects

[0022] The present invention provides a continuous pipeline oxidation device and process for preparing nitrobenzoic acid. Compared with the prior art, it has the following beneficial effects:

[0023] (1) For the continuous pipeline oxidation device and process for preparing nitrobenzoic acid, by setting a synchronous drive mechanism, after the material is fed into the inner side of the reaction kettle, while stirring, the sealing cover can be tightly pressed to seal the feed port, and it can be ensured that the sealing cover always covers the feed port during the stirring process, and the feed port can be automatically opened after the stirring ends. The opening and closing of the sealing cover realizes automation and synchronization with the stirring component, without the need for manual operation, and due to the mechanical linkage with the working of the stirring component, the timeliness of the opening and closing of the sealing cover is ensured.

[0024] (2) For the continuous pipeline oxidation device and process for preparing nitrobenzoic acid, through the set stirring component, longitudinal stirring from top to bottom and from bottom to top can be realized in the reaction kettle during stirring, so as to ensure that the materials in the upper and lower layers can be evenly mixed, thus avoiding the phenomenon that a large amount of materials always deposit at the bottom of the reaction kettle, and greatly improving the efficiency and quality of stirring. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of the present invention;

[0026] Figure 2 It is a schematic structural diagram of the feed inlet of the present invention;

[0027] Figure 3 For the present invention Figure 2 An enlarged view of part A;

[0028] Figure 4 It is a schematic structural diagram of the synchronous drive mechanism of the present invention;

[0029] Figure 5 It is a schematic structural diagram of the stirring assembly of the present invention;

[0030] Figure 6 It is a schematic structural diagram of the stirring blade of the present invention;

[0031] Figure 7 It is a schematic structural diagram of the rubber gasket of the present invention;

[0032] Figure 8 It is a schematic structural diagram of the shape of the top push plate of the present invention;

[0033] Figure 9 It is a schematic structural diagram of the position of the top push plate of the present invention;

[0034] Figure 10 It is a schematic structural diagram of the shape of the sliding block of the present invention.

[0035] In the figure, 1, reaction kettle; 101, first pipeline; 101A, booster pump; 102, second pipeline; 102A, circulation pump; 103, fourth pipeline; 104, support rod; 105, support plate; 2, junction box; 201, gas drive component; 202, fifth pipeline; 3, non-driven gas-liquid integration component; 301, third pipeline; 4, nitric acid solution storage tank; 5, feed inlet; 51, annular flange; 51A, rubber gasket; 6, sealing cover; 7, stirring assembly; 71, transmission shaft; 72, reciprocating lead screw; 73, moving block; 74, stirring blade; 75, convex block; 76, groove; 8, synchronous drive mechanism; 81, motor; 82, worm; 83, worm gear; 84, gear; 85, connecting piece; 86, push rod; 87, sliding block; 88, top push plate; 89, rack; 810, second spring; 811, limiting strip; 9, rotating rod; 10, torsion spring; 11, first slide rail; 12, first slide bar; 13, second slide rail. Detailed Embodiments

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. 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.

[0037] Please refer to Figures 1-10 , the embodiments of the present invention provide a technical solution: a continuous pipeline oxidation device for preparing nitrobenzoic acid, including a reaction kettle 1, a junction box 2 and a non-driven gas-liquid integrated part 3. A gas driving part 201 is also installed on the top of the junction box 2. The top of the reaction kettle 1 is connected to the air inlet end of the gas driving part 201 through a first pipeline 101. A booster pump 101A is installed on the first pipeline 101. The bottom of the reaction kettle 1 is connected to the liquid inlet end of the non-driven gas-liquid integrated part 3 through a second pipeline 102. The air inlet end of the non-driven gas-liquid integrated part 3 is connected to the air outlet end of the gas driving part 201 through a third pipeline 301. The discharge end of the non-driven gas-liquid integrated part 3 is connected to the top of the reaction kettle 1. The upper end of the reaction kettle 1 is also connected to the junction box 2 through a fourth pipeline 103. A circulation pump 102A is also installed on the second pipeline 102. The junction box 2 is also connected to a nitric acid solution storage tank 4 through a fifth pipeline 202. The reaction kettle 1 further includes a feed inlet 5 provided at the top of the reaction kettle 1. The reaction kettle 1 further includes support rods 104 fixed on the outer wall of the reaction kettle 1 at equal angles and a support plate 105 fixed at the bottom of the support rods 104. Through the support plate 105 and the support rods 104, the reaction kettle 1 can be stably supported at the use position. A ring-shaped convex edge 51 is formed at the top of the feed inlet 5. A rubber gasket 51A is fixed at the top of the ring-shaped convex edge 51. A sealing cover 6 is rotatably installed on the feed inlet 5. After the sealing cover 6 is rotated and closed, it can press on the rubber gasket 51A, so that the sealing cover 6 can tightly seal the feed inlet 5. A stirring assembly 7 is installed in the middle of the reaction kettle 1. A rotating rod 9 is fixed on one side of the sealing cover 6 close to the stirring assembly 7. The rotating rod 9 is rotatably connected to the outer wall of the feed inlet 5 through a bearing. A torsion spring 10 is sleeved at the end of the rotating rod 9. One end of the torsion spring 10 is fixed to the outer wall of the rotating rod 9, and the other end of the torsion spring 10 is fixed to the outer wall of the feed inlet 5. The setting of the torsion spring 10 makes the sealing cover 6 always have a tendency to be opened. When the sealing cover 6 is not subjected to the force of being rotated and closed, the torsion spring 10 rebounds to drive the rotating rod 9 to rotate to open the sealing cover 6. When the sealing cover 6 is subjected to the force of being driven to rotate and close, it is a process of twisting and storing energy of the torsion spring 10. A synchronous driving mechanism 8 is also fixed on the top of the reaction kettle 1. The synchronous driving mechanism 8 is used to drive the stirring assembly 7 to work and can close the sealing cover 6 while the stirring assembly 7 is pneumatically driven, and open the sealing cover 6 while the stirring assembly 7 stops.

[0038] The usage process is as follows. In the initial state, when the stirring assembly 7 is not driven to work, the sealing cover 6 is kept in an open state under the action of the torsion spring 10. The operator can put materials and catalysts into the inner side of the reaction kettle 1 through the feed port 5. After the feeding is completed, the synchronous drive mechanism 8 is driven to work, so that the stirring assembly 7 works together for stirring. At the initial stage of the stirring assembly 7 starting to work, the sealing cover 6 can be closed under the action of the synchronous drive mechanism 8 at the same time, and finally the sealing cover 6 is always pressed tightly on the rubber gasket 51A, so that the sealing cover 6 is always tightly closed during the stirring process. When the synchronous drive mechanism 8 is stopped driving at the end of the reaction, the stirring assembly 7 loses power and stops working. Due to the loss of power, the sealing cover 6 is opened under the action of the resilience of the torsion spring 10, so that discharging and subsequent continuous feeding work can be carried out, and the preparation work of nitrobenzoic acid is carried out repeatedly like this.

[0039] The stirring assembly 7 includes a transmission shaft 71, a reciprocating lead screw 72, a moving block 73, stirring blades 74, a convex block 75 and a groove 76. The middle part of the reaction kettle 1 is rotatably connected with the transmission shaft 71 through a bearing. The lower end of the transmission shaft 71 is fixed with a reciprocating lead screw 72. The lower end of the reciprocating lead screw 72 is rotatably connected with the inner wall of the reaction kettle 1 through a bearing. A moving block 73 is fitted on the outer side of the reciprocating lead screw 72. Stirring blades 74 are fixed on the moving block 73. Convex blocks 75 are formed on the outer wall of the stirring blades 74. Grooves 76 are symmetrically formed on the inner wall of the reaction kettle 1. The convex blocks 75 are slidably connected with the inner walls of the grooves 76. During the working process of the stirring assembly 7, by driving the transmission shaft 71 to rotate to drive the reciprocating lead screw to rotate, and the cooperation between the reciprocating lead screw 72 and the moving block 73 is a prior art. By rotating the reciprocating lead screw 72, the moving block 73 can move up and down and then up and down repeatedly on its outer side, so as to drive the stirring blades 74 to move up and down reciprocally. During the movement of the stirring blades 74, the convex blocks 75 slide inside the grooves 76. The convex blocks 75 and the grooves 76 are arranged to ensure that the stirring blades 74 can slide up and down stably. By stirring the materials inside the reaction kettle 1 up and down by the stirring blades 74, the materials in the upper and lower layers inside the reaction kettle 1 can be disturbed and mixed, so as to avoid the phenomenon that a large amount of catalysts are deposited under the reaction kettle 1, and greatly improve the quality and efficiency of stirring and mixing.

[0040] The synchronous drive mechanism 8 includes a motor 81, a worm 82, a worm gear 83, a gear 84, a connecting piece 85, a push rod 86, a sliding block 87, a top push plate 88, a rack 89, a second spring 810 and a limiting strip 811. The motor 81 is fixed to the top of the reactor 1. The output end of the motor 81 is fixed with the worm 82. The worm 82 is rotatably connected to the top of the reactor 1 through a bearing. The top of the transmission shaft 71 is fixed with the worm gear 83. The worm gear 83 is meshed and connected with the worm 82. The end of the worm 82 is fixed with the gear 84. Symmetrically fixed to the side of the sealing cover 6 close to the rotating rod 9 are the connecting pieces 85. A push rod 86 is rotatably connected between the two connecting pieces 85 through a pin. The lower end of the push rod 86 is rotatably connected with a sliding block 87 through a pin. The sliding block 87 is slidably connected to the outer wall of the feed inlet 5. The bottom of the sliding block 87 is arc-shaped. A top push plate 88 is slidably connected to the side of the top of the reactor 1 close to the sliding block 87. The top surface of the top push plate 88 is inclined. The bottom of the sliding block 87 is in pressing contact with the top surface of the top push plate 88. A rack 89 is fixed to the side of the top push plate 88 close to the gear 84. The rack 89 is meshed and connected with the gear 84. A second spring 810 is fixed to the outer wall of the top push plate 88 away from the sliding block 87. The side of the second spring 810 away from the top push plate 88 is fixed to the top of the reactor 1. A limiting strip 811 arranged in an inverted L shape is fixed to the side of the top of the reactor 1 close to the second spring 810. The top push plate 88 is in pressing contact with the outer wall of the limiting strip 811. A first slide rail 11 is fixed to the side of the top of the reactor 1 close to the rack 89 and directly below the rack 89. A first slide bar 12 fixed to the outer wall of the top push plate 88 is slidably connected to the outer wall of the first slide rail 11. Symmetrically fixed to the side of the outer wall of the feed inlet 5 close to the sliding block 87 are second slide rails 13. The sliding block 87 is slidably connected to the outer walls of the second slide rails 13 through chutes.

[0041] The usage process of the synchronous drive mechanism 8 is as follows: The driving motor 81 rotates to drive the worm 82 to rotate, which can drive the worm wheel 83 to rotate, enabling the transmission shaft 71 to rotate, and enabling the stirring assembly 7 to operate. At the initial stage of the rotation of the motor 81, that is, at the initial stage of the rotation of the worm 82, the gear 84 is driven to rotate synchronously. The rotation of the gear 84 deflects the rack 89 to move away from the second spring 810, driving the push plate 88 to slide away from the limit strip 811. The movement of the push plate 88 can push the sliding block 87 to move upward, thereby pushing the push rod 86, and further enabling the sealing cover 6 to flip towards the rubber gasket 51A. Before the rack 89 moves to the point where it is about to disengage from the gear 84, the sealing cover 6 has already pressed on the top of the rubber gasket 51A, achieving the effect of sealing the feed port 5. Then, under the continuous rotation of the gear 84, the rack 89 will be deflected to a state of disengaging from the gear 84, while the sealing cover 6 is always pushed and pressed by the push rod 86 against the outside of the sealing gasket to achieve sealing. It should be emphasized that during the process of the sealing cover 6 being pressed on the rubber gasket 51A, the bottom of the sliding block 87 is always in contact with the inclined surface of the push plate 88. After the gear 84 disengages from the rack 89, under the restoring force of the second spring 810, it will be pulled towards the side close to the limit strip 811 each time it disengages, and always adheres to the gear 84 without separating from the gear 84 until the stirring work of the motor 81 ends. After the motor 81 stops rotating, under the restoring forces of the second spring 810 and the torsion spring 10, the sealing cover 6 rotates back to open. At the same time, the rack 89 slides back towards the side close to the limit strip 811, and the rack 89 engages with the gear 84 again. Driven by the rack 89, the gear 84 rotates in reverse, driving the output shaft of the motor 81 to rotate in the reverse direction by a certain distance. It should be emphasized that the elastic force of the second spring 810 is large enough to enable the rack 89 to deflect the gear 84 to rotate. Then the push plate 88 slides back to its original position. Finally, the push plate 88 presses on the limit strip 811, and the sliding block 87 descends and resets to press on the lower end of the inclined surface of the push plate 88, while the sealing cover 6 opens. Thus, it is achieved that the sealing cover 6 is sealed and closed at the start of the stirring work, and the sealing cover 6 is automatically opened at the end of the stirring work, eliminating the need for manual opening and closing of the sealing cover 6, greatly saving the operation steps. And because the opening and closing of the sealing cover 6 are mechanically linked with the stirring work, the stability and timeliness of the opening and closing of the sealing cover 6 are ensured.

[0042] The present invention also provides a process for preparing nitrobenzoic acid using a continuous pipeline oxidation device for preparing nitrobenzoic acid. The process for preparing nitrobenzoic acid is carried out using the above-mentioned continuous pipeline oxidation device for preparing nitrobenzoic acid, and the process includes the following steps:

[0043] 1), Feed the nitro-toluene raw material liquid, nitric acid solution, and oxygen into the reaction kettle 1 through the feed port 5 in the existing ratio to form a product and a reaction mixture. At the same time, nitric oxide gas is also generated. Nitric oxide reacts with oxygen to form nitrogen dioxide gas. As the reaction temperature increases, the density of the product nitrobenzoic acid increases. Therefore, the nitro-toluene raw material liquid and the product float on the liquid surface of the reaction mixture due to the increase in the density of the overall reaction system.

[0044] 2) The reaction mixture is introduced into the non-driven gas-liquid integrated part 3 through the circulation pump 102A connected to the bottom of the reaction kettle 1 to realize the contact between nitrogen dioxide and water to generate nitric acid solution, and then return to the reaction kettle 1 to form a cycle, thereby continuously improving the reaction efficiency.

[0045] 3) The gas exported from the first pipeline 101 on the reaction kettle 1 is pressurized by the booster pump 101A to a sufficient pressure and enters the gas drive part 201 to drive the gas drive part 201 to rotate and then return to the non-driven gas-liquid integrated part 3, and is mixed with the liquid in the non-driven gas-liquid integrated part 3 and enters the reaction kettle 1.

[0046] 4) A part of the solution with raw materials and products in the reaction kettle 1 is introduced into the junction box 2, and the nitric acid solution in the nitric acid solution storage tank 4 is introduced into the upper end of the junction box 2. In this way, the substances introduced from the upper end and the lower end move relatively up and down and react in the junction box 2. At this time, the concentration of the nitro-toluene raw material solution is high at the lower end, and the concentration of the nitric acid solution in the nitric acid solution storage tank 4 is high at the upper end; at the lower end position, the high-concentration nitro-toluene raw material solution reacts with the low-concentration nitric acid solution, and at the upper end position, the low-concentration nitro-toluene raw material solution reacts with the high-concentration nitric acid solution. Through such a configuration, the overall efficiency of the reaction is improved, and the problem that the existing reaction efficiency is very high in the early stage and very low in the later stage will not occur. After the reaction, the product is discharged by static settling. During the discharge process of the product, taking advantage of the characteristics that the density of the nitric acid solution is heavier than that of the nitro-toluene raw material liquid and lighter than that of the nitrobenzoic acid, the final product is exported from the upper end outlet of the junction box 2, and the unreacted raw materials are exported from the lower end outlet of the junction box 2.

[0047] At the same time, the content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

[0048] It should be noted that, in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprising", "including" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or elements inherent to such process, method, article or device.

[0049] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A continuous pipeline oxidation device for preparing nitrobenzoic acid, comprising a reaction kettle (1), a junction box (2) and a driverless gas-liquid integrated component (3). A gas driver (201) is further installed on the top of the junction box (2). The top of the reaction kettle (1) is connected to the intake end of the gas driver (201) through a first pipeline (101). A booster pump (101A) is installed on the first pipeline (101). The bottom of the reaction kettle (1) is connected to the liquid inlet end of the driverless gas-liquid integrated component (3) through a second pipeline (102). The gas inlet end of the driverless gas-liquid integrated component (3) is connected to the outlet end of the gas driver (201) through a third pipeline (301). The discharge end of the driverless gas-liquid integrated component (3) is connected to the top of the reaction kettle (1). The upper end of the reaction kettle (1) is further connected to the junction box (2) through a fourth pipeline (103). A circulation pump (102A) is also installed on the second pipeline (102). The junction box (2) is further connected to a nitric acid solution storage tank (4) through a fifth pipeline (202). It is characterized in that the reaction kettle (1) further includes a feed inlet (5) provided at the top of the reaction kettle (1). A sealing cover (6) is rotatably installed on the feed inlet (5). A stirring assembly (7) is installed in the middle of the reaction kettle (1). A synchronous drive mechanism (8) is further fixed to the top of the reaction kettle (1). The synchronous drive mechanism (8) is used to drive the stirring assembly (7) to work and can close the sealing cover (6) while the stirring assembly (7) is pneumatically actuated, and open the sealing cover (6) while the stirring assembly (7) stops; the reaction kettle (1) further includes support rods (104) fixed on the outer wall of the reaction kettle (1) at equal angles and a support plate (105) fixed to the bottom of the support rods (104). A ring-shaped convex edge (51) is formed at the top of the feed inlet (5). A rubber gasket (51A) is fixed to the top of the ring-shaped convex edge (51); the stirring assembly (7) includes a transmission shaft (71), a reciprocating lead screw (72), a moving block (73), stirring blades (74), a convex block (75) and a groove (76). The middle of the reaction kettle (1) is rotatably connected to the transmission shaft (71) through a bearing. The lower end of the transmission shaft (71) is fixed with a reciprocating lead screw (72). The lower end of the reciprocating lead screw (72) is rotatably connected to the inner wall of the reaction kettle (1) through a bearing. A moving block (73) is fitted on the outer side of the reciprocating lead screw (72). Stirring blades (74) are fixed on the moving block (73). Convex blocks (75) are formed on the outer wall of the stirring blades (74). Grooves (76) are symmetrically formed on the inner wall of the reaction kettle (1). The convex blocks (75) are slidably connected to the inner walls of the grooves (76); The synchronous drive mechanism (8) includes a motor (81), a worm (82), a worm gear (83), a gear (84), a connecting piece (85), a push rod (86), a sliding block (87), a top push plate (88), a rack (89), a second spring (810) and a limiting strip (811). A motor (81) is fixed to the top of the reaction kettle (1). The output end of the motor (81) is fixed with a worm (82). The worm (82) is rotationally connected to the top of the reaction kettle (1) through a bearing. The top of the transmission shaft (71) is fixed with a worm gear (83). The worm gear (83) is meshed and connected with the worm (82). The end of the worm (82) is fixed with a gear (84). Connecting pieces (85) are symmetrically fixed to one side of the sealing cover (6) close to the rotating rod (9). A push rod (86) is rotationally connected between the two connecting pieces (85) through a pin. The lower end of the push rod (86) is rotationally connected with a sliding block (87) through a pin. The sliding block (87) is slidably connected to the outer wall of the feed inlet (5). The bottom of the sliding block (87) is arc-shaped. A top push plate (88) is slidably connected to one side of the top of the reaction kettle (1) close to the sliding block (87). The top surface of the top push plate (88) is inclined. The bottom of the sliding block (87) is in pressing contact with the top surface of the top push plate (88). A rack (89) is fixed to one side of the top push plate (88) close to the gear (84). The rack (89) is meshed and connected with the gear (84). A second spring (810) is fixed to the outer wall of the top push plate (88) away from the sliding block (87). The side of the second spring (810) away from the top push plate (88) is fixed to the top of the reaction kettle (1). An inverted L-shaped limiting strip (811) is fixed to one side of the top of the reaction kettle (1) close to the second spring (810). The top push plate (88) is in pressing contact with the outer wall of the limiting strip (811). A first slide rail (11) is fixed to the top of the reaction kettle (1) on the side close to the rack (89) and directly below the rack (89). A first slide bar (12) fixed to the outer wall of the top push plate (88) is slidably connected to the outer wall of the first slide rail (11). Second slide rails (13) are symmetrically fixed to one side of the outer wall of the feed inlet (5) close to the sliding block (87). The sliding block (87) is slidably connected to the outer wall of the second slide rail (13) through a chute.

2. The continuous pipeline oxidation device for preparing nitrobenzoic acid according to claim 1, characterized in that: A rotating rod (9) is fixed to one side of the sealing cover (6) close to the stirring assembly (7). The rotating rod (9) is rotationally connected to the outer wall of the feed inlet (5) through a bearing. A torsion spring (10) is sleeved on the end of the rotating rod (9). One end of the torsion spring (10) is fixed to the outer wall of the rotating rod (9). The other end of the torsion spring (10) is fixed to the outer wall of the feed inlet (5).

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