Production and preparation system of N-methylaniline

Abstract

The invention discloses a production preparation system of N-methylaniline, which comprises an aniline metering tank, a methanol metering tank, a mixing kettle, a gasification kettle, a fixed bed reactor, a condenser, a crude product receiving storage tank and a refining unit, the top end of the mixing kettle is provided with a circulating pump, and the bottom end of the mixing kettle is provided with a discharge port; a circulating pipe is connected between the discharge port and a feed port of the circulating pump, and a charging port is formed in the feed port; two stirring shafts are rotationally mounted in the mixing kettle, and the top ends of the stirring shafts extend to the outside of the mixing kettle and are provided with rotary joints. The discharge port is formed in the bottom end of the mixing kettle and connected with the feed port of the circulating pump through the circulating pipe, and the feed port is provided with the charging port, so that aniline and methanol materials can enter the circulating pump. After being pressurized, the materials are sprayed into the mixing kettle through the feeding pipe, the stirring shaft, the stirring branches and the spray heads, and the primarily mixed materials can flow into the circulating pump again to be sprayed and mixed, so that the material mixing process is accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of N-methylaniline production, and particularly to a production preparation system for N-methylaniline. Background Art

[0002] As an important organic chemical raw material, N-methylaniline has wide applications in many fields such as dyes, pharmaceuticals, and pesticides. There are some deficiencies in the traditional production preparation system of N-methylaniline.

[0003] In the material mixing link, the conventional stirring method has low efficiency, and it is difficult to achieve rapid and sufficient mixing of materials, resulting in an extended reaction time and limited production efficiency. Moreover, this will cause more energy to be consumed during the production process to maintain the reaction, not only increasing the production cost, but also generating more energy consumption and pollutant emissions, which is not conducive to energy conservation and environmental protection.

[0004] In addition, the existing circulating pump structure and conveying method are often relatively single, unable to work in coordination with the stirring process, and unable to further improve the material mixing effect, which to a certain extent affects the product quality and production efficiency. At the same time, due to the independent operation of the circulating pump and the stirring system, the energy utilization efficiency in the whole production process is low, increasing unnecessary energy consumption, and it is also not conducive to achieving the energy conservation and emission reduction goals during the production process.

[0005] Therefore, developing a production preparation system for N-methylaniline that can overcome the above defects, with reasonable design and high efficiency, is of great significance for achieving energy conservation and environmental protection, reducing production costs, and improving product quality and production efficiency. Summary of the Invention

[0006] In order to solve the problems mentioned in the above background art, the present invention provides a production preparation system for N-methylaniline.

[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A production preparation system for N-methylaniline includes an aniline metering tank, a methanol metering tank, a mixing kettle, a gasification kettle, a fixed bed reactor, a condenser, a crude product receiving storage tank, and a refining unit. A circulating pump is installed at the top of the mixing kettle. There is a discharge port at the bottom of the mixing kettle, and a circulating pipe is connected between the discharge port and the feed port of the circulating pump. There is a feeding port on the feed port.

[0009] Two stirring shafts are rotatably installed inside the mixing kettle. The top ends of the stirring shafts extend to the outside of the mixing kettle and are equipped with rotary joints. The circulating pump has two discharge ports, and feed pipes are provided between the two discharge ports and the two rotary joints.

[0010] The stirring shaft is hollow inside, and a plurality of stirring branches are provided on the outside of the stirring shaft. The stirring branches are communicated with the inside of the stirring shaft, and a nozzle is provided at one end of the stirring shaft.

[0011] Preferably, a gear is fixed at a position near the top of the outside of the stirring shaft, and the two gears are meshed with each other.

[0012] Preferably, a driven pulley is fixed on the outside of one of the stirring shafts, a rotating motor is fixed at the top of the mixing kettle, a driving pulley is fixed on the output shaft of the rotating motor, and a transmission belt is provided between the driven pulley and the driving pulley.

[0013] Preferably, a first piston plate and a second piston plate are respectively provided in the circulation pump. A first driving shaft and a second driving shaft are respectively connected to the first piston plate and the second piston plate, and the second driving shaft is movably sleeved on the outside of the first driving shaft.

[0014] Preferably, a first one-way valve is installed on the feed inlet, and the first one-way valve ensures that the material can only flow into the circulation pump. A second one-way valve is installed on the feed pipe, and the second one-way valve ensures that the material can only flow out from the inside of the circulation pump.

[0015] Preferably, a linkage mechanism is provided between the stirring shaft and the circulation pump. The linkage mechanism drives the first driving shaft and the second driving shaft to move in opposite directions, and further drives the first piston plate and the second piston plate to reciprocally approach and move away from each other.

[0016] Preferably, the linkage mechanism includes two sets of link mechanisms. The link mechanism includes a power input shaft, and the two power input shafts are respectively fixed to the two stirring shafts. The link mechanism further includes a first link, a second link and a third link.

[0017] Preferably, one end of the first link is fixed to the input shaft, the other end of the first link and one end of the second link are fixed through a first pin shaft, and the end of the second link away from the first pin shaft is fixed to the third link through a second pin shaft.

[0018] Preferably, a first driving rod is fixed at one end of the first driving shaft. A fourth link is hinged on the first driving rod. The end of the fourth link away from the first driving rod is hinged to the first pin shaft. A second driving rod is fixed at one end of the second driving shaft. A fifth link is hinged on the second driving rod. The end of the fifth link away from the second driving rod is hinged to the second pin shaft.

[0019] Preferably, the stirring branches are distributed in an annular array on the outside of the stirring shaft. A cross bar is fixed inside the mixing kettle. A plugging device is fixed at the top of the cross bar. The plugging device extends into the stirring branch movably. The plugging device is of an arc-shaped structure, and a notch is provided on one side where the plugging devices are close to each other.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. By providing a discharge port at the bottom end of the mixing kettle, which is connected to the feed port of the circulation pump through a circulation pipe, and the feed port is provided with a feeding port, aniline and methanol materials can enter the circulation pump. After pressurization, they are sprayed into the mixing kettle through the feed pipe, the stirring shaft, the stirring branches and the nozzles. The initially mixed materials can flow back into the circulation pump for jet mixing again, accelerating the material mixing process. Two stirring shafts are rotatably installed in the mixing kettle, and a plurality of stirring branches are arranged outside the stirring shafts. When the stirring shafts rotate, the stirring branches stir the materials, which, in cooperation with the circulating jet mixing, further improves the mixing efficiency. This efficient mixing method can achieve full mixing of the materials in a relatively short time, reducing the reaction time and thus reducing the energy consumption, achieving energy conservation and environmental protection to a certain extent.

[0022] 2. Gears that mesh with each other are fixed at positions close to the top of the outside of the stirring shafts. One of the stirring shafts is connected to the driving pulley of the rotating motor through a driven pulley and a transmission belt. By starting the rotating motor, the two stirring shafts can be driven to rotate synchronously and in opposite directions, achieving efficient stirring, and the structure is simple and the transmission is stable. A first piston plate and a second piston plate are arranged in the circulation pump, which are respectively connected to a first driving shaft and a second driving shaft. A linkage mechanism is provided between the stirring shaft and the circulation pump. When the stirring shaft rotates, the power input shaft drives the linkage mechanism to rotate, and then pulls the fourth connecting rod and the fifth connecting rod, driving the first driving rod and the second driving rod, so that the first piston plate and the second piston plate reciprocate close to and away from each other, realizing the one-way conveying of the materials, reducing the use of additional driving devices, not only reducing the investment cost of the equipment, but also reducing the energy consumption.

[0023] 3. The stirring branches are distributed in an annular array on the outside of the stirring shafts. A cross bar and a plugging device at the top end are fixed in the mixing kettle. During the rotation of the stirring shafts, only the stirring branches at specific positions (the direction where the two stirring shafts face each other) can pass through the notch of the plugging device. At this time, the nozzles spray liquid, and the two streams of liquid impact each other, improving the mixing effect. When the nozzles rotate to other positions, they are blocked by the plugging device, so that only part of the liquid is sprayed relative to the nozzles at a certain time, increasing the pressure of the sprayed liquid and further enhancing the mixing effect. The optimized mixing effect ensures the full progress of the reaction, reduces the waste of raw materials, reduces the pollutant emissions that may be generated due to incomplete reaction, and at the same time, the efficient mixing also reduces the energy consumption required for the reaction, being more environmentally friendly. Description of the Drawings

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0026] Figure 2 It is a front view of the mixing kettle of the present invention;

[0027] Figure 3 It is a cross-sectional view of a mixing kettle of the present invention;

[0028] Figure 4 It is an exploded view of the stirring shaft and the stirring shaft matching of the present invention;

[0029] Figure 5 A first perspective stereoscopic view of the circulating pump of the present invention;

[0030] Figure 6 A cross-sectional view from a top view of a circulating pump of the present invention;

[0031] Figure 7 It is a front view of the circulating pump of the present invention;

[0032] Figure 8 A second perspective perspective view of the circulating pump of the present invention;

[0033] Figure 9 It is a three-dimensional enlarged view of the connecting rod mechanism of the present invention;

[0034] Figure 10 It is a front view of the connecting rod mechanism of the present invention;

[0035] Figure 11 It is a schematic diagram showing that the first piston plate and the second piston plate of the circulating pump of the present invention are in the closest state;

[0036] Figure 12 It is a schematic diagram showing that the first piston plate and the second piston plate of the circulating pump of the present invention are in the most distant state;

[0037] In the figure: 1, aniline metering tank; 2, methanol metering tank; 3, mixing kettle; 301, discharge port; 302, circulation pipe; 303, stirring shaft; 3031, rotary joint; 304, stirring branch; 305, spray head; 306, cross bar; 307, plugging device; 4, gasification kettle; 5, fixed bed reactor; 6, condenser; 7, crude product receiving storage tank; 8, circulation pump; 801, feed inlet; 8011, first one-way valve; 802, feeding port; 803, feed pipe; 8031, second one-way valve; 804, first drive shaft; 8041, first drive rod; 8042, fourth connecting rod; 805, first piston plate; 806, second drive shaft; 8061, second drive rod; 8062, fifth connecting rod; 807, second piston plate; 9, power input shaft; 901, gear; 902, driven pulley; 903, rotary motor; 904, driving pulley; 10, first connecting rod; 1001, second connecting rod; 1002, third connecting rod; 1003, first pin shaft; 1004, second pin shaft. Detailed implementation manners

[0038] 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.

[0039] Embodiment 1

[0040] Referring to Figures 1-12 , a production and preparation system for N-methylaniline, comprising an aniline metering tank 1, a methanol metering tank 2, a mixing kettle 3, a gasification kettle 4, a fixed bed reactor 5, a condenser 6, a crude product receiving storage tank 7 and a refining unit. A circulation pump 8 is installed at the top of the mixing kettle 3. A discharge port 301 is provided at the bottom of the mixing kettle 3. A circulation pipe 302 is connected between the discharge port 301 and the feed inlet 801 of the circulation pump 8. A feeding port 802 is provided on the feed inlet 801;

[0041] Two stirring shafts 303 are rotatably installed inside the mixing kettle 3. The top ends of the stirring shafts 303 extend to the outside of the mixing kettle 3 and are provided with rotary joints 3031. The circulation pump 8 is provided with two discharge ports, and feed pipes 803 are provided between the two discharge ports and the two rotary joints 3031;

[0042] The inside of the stirring shaft 303 is hollow, and a plurality of stirring branches 304 are provided on the outside of the stirring shaft 303. The stirring branches 304 are communicated with the inside of the stirring shaft 303, and a spray head 305 is provided at one end of the stirring shaft 303.

[0043] The aniline and methanol materials from the tank farm are pumped into the aniline metering tank 1 and methanol metering tank 2 in the workshop respectively for standby. Then, the aniline and methanol are mixed by a material pump through a proportioning mixer according to a molar ratio of 1:1.5; subsequently, they are pumped into the mixing kettle 3 for full mixing. After mixing, they are pumped into the vaporization kettle 4 (flow rate 0.4 - 0.7 m 3 / h) for vaporization. The vaporization kettle 4 uses heat-conducting oil as a heat source for heating, and the material vaporizes at a temperature of 170 - 230°C. The gas phase enters the fixed-bed reactor 5 through a pipeline. The fixed-bed reactor 5 (composite catalyst) uses heat-conducting oil as a heat source for heating to keep the temperature at 180 - 250°C for reaction to produce N-methylaniline. The crude N-methylaniline is condensed and liquefied by the condenser 6 and enters the crude N-methylaniline receiving storage tank 7, and the crude N-methylaniline is transferred to the refining unit for separation and purification.

[0044] In the refining unit, after the crude N-methylaniline is evenly mixed, it is sent to the methanol tower by the N-methylaniline feeding pump. In the methanol tower, methanol is recovered by distillation at normal pressure and the top of the tower at a temperature of 60 - 75°C; other component media enter the aniline azeotropic tower for treatment. At -0.09 MPa and a temperature of 150 - 170°C, aniline and water are azeotropically distilled out from the upper part of the tower. The gas-phase medium is condensed by the condenser and stratified under 5% brine. Among them, the organic phase enters the aniline tower. After the inorganic phase enters the wastewater tower to recover aniline, the remaining wastewater goes to environmental protection treatment. The top of the aniline tower azeotropes at a temperature of 102°C, and its gas-phase medium is condensed by the aniline recovery tower condenser and separated into two phases automatically under the action of 5% brine. The aqueous-phase medium enters the wastewater tower to recover aniline, and the organic phase returns to the aniline tower. After the aqueous phase of the wastewater tower is treated by resin and qualified, it enters the sewage treatment station for treatment. When the water content of aniline at the bottom of the aniline tower is less than 1%, it is pumped out, then cooled by a cooler to make the material temperature drop below 40°C, and then enters the aniline recovery storage tank and returns to the batching process for recycling. The material at the bottom of the azeotropic tower is pumped into the N-methylaniline rectification tower, and N-methylaniline of high quality is obtained by rectification at -0.095 MPa and a temperature of 150 - 165°C. The material at the bottom of the tower is pumped into the N,N-diethylaniline distillation tower (batch tower), and by-product N,N-dimethylaniline is recovered at -0.095 MPa and a temperature of 160 - 180°C, and the kettle residue is discharged about once every 15 days.

[0045] The materials in the aniline metering tank 1 and methanol metering tank 2 enter the circulation pump 8 through the feeding port 802 and the feeding port 801, and then after pressurization, they are sprayed into the inside of the mixing kettle 3 through the feeding pipe 803, the stirring shaft 303, the stirring shaft 303 and the nozzle 305, so as to accelerate the mixing of the materials. The initially mixed materials can flow out through the discharge port 301 and flow into the circulation pump 8 again through the circulation pipe 302 for jet mixing. At the same time, the stirring shaft 303 can rotate to drive the stirring branch 304 to stir the materials, further improving the mixing efficiency.

[0046] Example 2

[0047] Refer to Figures 1-12 , the difference between this embodiment and Embodiment 1 is that a gear 901 is fixed at a position near the top outside the stirring shaft 303, and the two gears 901 are meshed with each other. A driven pulley 902 is fixed outside one of the stirring shafts 303, a rotating motor 903 is fixed at the top of the mixing kettle 3, a driving pulley 904 is fixed on the output shaft of the rotating motor 903, and a transmission belt is provided between the driven pulley 902 and the driving pulley 904;

[0048] When the rotating motor 903 is turned on, it can drive the driving pulley 904 to rotate, and can drive the driven pulley 902 to rotate through the transmission of the transmission belt, and then drive one of the stirring shafts 303 to rotate. Then, through the meshing of the two gears 901, the other stirring shaft 303 can be driven to rotate synchronously and reversely, so as to carry out stirring and mixing.

[0049] Example 3

[0050] Refer to Figures 1-12 , the difference between this embodiment and Embodiment 2 is that a first piston plate 805 and a second piston plate 807 are respectively arranged in the circulation pump 8. A first driving shaft 804 and a second driving shaft 806 are respectively connected to the first piston plate 805 and the second piston plate 807. The second driving shaft 806 is movably sleeved outside the first driving shaft 804. A first one-way valve 8011 is installed at the feed inlet 801, and the first one-way valve 8011 ensures that the material can only flow into the circulation pump 8. A second one-way valve 8031 is installed on the feed pipe 803, and the second one-way valve 8031 ensures that the material can only flow out from the inside of the circulation pump 8. A linkage mechanism is provided between the stirring shaft 303 and the circulation pump 8. The linkage mechanism drives the first driving shaft 804 and the second driving shaft 806 to move in opposite directions, so as to drive the first piston plate 805 and the second piston plate 807 to reciprocally approach and move away from each other;

[0051] When the first piston plate 805 and the second piston plate 807 move closer to each other, the material in the circulation pump 8 can be pressed out from the two feed pipes 803, so as to add the material into the mixing kettle 3. When the first piston plate 805 and the second piston plate 807 move away from each other, the material can be extracted from the feed inlet 801 into the circulation pump 8, so as to achieve the effect of unidirectional material transportation.

[0052] Example 4

[0053] Refer to Figures 1-12, The difference between this embodiment and Embodiment 3 is that the linkage mechanism includes two sets of link mechanisms. The link mechanism includes a power input shaft 9. The two power input shafts 9 are respectively fixed to the two stirring shafts 303. The link mechanism further includes a first link 10, a second link 1001, and a third link 1002. One end of the first link 10 is fixed to the input shaft 9. The other end of the first link 10 and one end of the second link 1001 are fixed through a first pin shaft 1003. The end of the second link 1001 far from the first pin shaft 1003 is fixed to the third link 1002 through a second pin shaft 1004. One end of the first drive shaft 804 is fixed with a first drive rod 8041. A fourth link 8042 is hinged on the first drive rod 8041. The end of the fourth link 8042 far from the first drive rod 8041 is hinged to the first pin shaft 1003. One end of the second drive shaft 806 is fixed with a second drive rod 8061. A fifth link 8062 is hinged on the second drive rod 8061. The end of the fifth link 8062 far from the second drive rod 8061 is hinged to the second pin shaft 1004;

[0054] Through the design of the linkage mechanism, when the power input shaft 9 rotates following the stirring shaft 303, the two power input shafts 9 rotate synchronously and in opposite directions. When the power input shaft 9 rotates, it can drive the whole formed by the first link 10, the second link 1001, and the third link 1002 to rotate. During the rotation of the first link 10, the second link 1001, and the third link 1002, it can pull the fourth link 8042 and the fifth link 8062 to move accordingly. Furthermore, the first drive rod 8041 and the second drive rod 8061 are driven to approach and move away from each other through the fourth link 8042 and the fifth link 8062. Then, the first piston plate 805 and the second piston plate 807 are driven to approach and move away from each other, and it can operate continuously in a cycle without additional driving devices.

[0055] Among them, the stirring branches 304 are annularly and arrayedly distributed on the outer side of the stirring shaft 303. A cross bar 306 is fixed inside the mixing kettle 3. The top end of the cross bar 306 is fixed with a plugging device 307. The plugging device 307 extends into the stirring branch 304 movably, and the plugging device 307 is of an arc-shaped structure, and there is a notch on the side where the plugging devices 307 approach each other;

[0056] Since the plugging device 307 is fixed, during the rotation of the stirring shaft 303, only the stirring branch 304 facing the direction where the two stirring shafts 303 face each other can be aligned with the notch. At this time, the stirring branch 304 is in a connected state, and the nozzle 305 connected to the stirring branch 304 can spray out liquid. At this time, the nozzles 305 on the two stirring shafts 303 face each other, and the two jets of liquid impact each other, thereby improving the mixing effect. When the nozzle 305 rotates to the side where the two stirring shafts 303 are away from each other, it will be automatically blocked by the plugging device 307. During a certain period of time, only some of the opposite nozzles 305 will spray out liquid, which can increase the pressure of the sprayed liquid and further improve the mixing effect.

[0057] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship 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.

[0058] In the present invention, unless otherwise clearly specified and defined, the terms "set", "install", "connect", "couple", "fix", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. 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.

[0059] 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 mainly aims to protect mechanical devices, so the control mode and circuit connection of the present invention will not be explained in detail.

[0060] The above is only a preferred specific embodiment 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 should be covered by the protection scope of the present invention.

Claims

1. A production and preparation system for N-methylaniline, comprising an aniline metering tank (1), a methanol metering tank (2), a mixing kettle (3), a vaporization kettle (4), a fixed-bed reactor (5), a condenser (6), a crude product receiving storage tank (7) and a refining unit, characterized in that: A circulation pump (8) is installed at the top of the mixing kettle (3). The bottom of the mixing kettle (3) is provided with a discharge port (301). A circulation pipe (302) is connected between the discharge port (301) and the feed inlet (801) of the circulation pump (8). A feeding port (802) is provided on the feed inlet (801). Two stirring shafts (303) are rotatably installed inside the mixing kettle (3). The top ends of the stirring shafts (303) extend to the outside of the mixing kettle (3) and are provided with rotary joints (3031). The circulation pump (8) is provided with two discharge ports, and feed pipes (803) are provided between the two discharge ports and the two rotary joints (3031). The inside of the stirring shaft (303) is hollow, and a plurality of stirring branches (304) are provided on the outside of the stirring shaft (303). The stirring branches (304) are communicated with the inside of the stirring shaft (303), and a spray head (305) is provided at one end of the stirring shaft (303).

2. The production and preparation system of N-methylaniline according to claim 1, wherein: Gears (901) are fixed at positions near the top ends on the outside of the stirring shafts (303), and the two gears (901) are meshed with each other.

3. The production and preparation system of N-methylaniline according to claim 2, characterized in that: A driven pulley (902) is fixed on the outside of one of the stirring shafts (303). A rotary motor (903) is fixed at the top of the mixing kettle (3). A driving pulley (904) is fixed on the output shaft of the rotary motor (903). A transmission belt is provided between the driven pulley (902) and the driving pulley (904).

4. The production and preparation system of N-methylaniline according to claim 2, wherein: A first piston plate (805) and a second piston plate (807) are respectively provided inside the circulation pump (8). A first driving shaft (804) and a second driving shaft (806) are respectively connected to the first piston plate (805) and the second piston plate (807). The second driving shaft (806) is movably sleeved on the outside of the first driving shaft (804).

5. The production and preparation system of N-methylaniline according to claim 4, characterized in that: A first one-way valve (8011) is installed on the feed inlet (801), and the first one-way valve (8011) ensures that the material can only flow into the circulation pump (8). A second one-way valve (8031) is installed on the feed pipe (803), and the second one-way valve (8031) ensures that the material can only flow out of the inside of the circulation pump (8).

6. The production and preparation system of N-methylaniline according to claim 5, characterized in that: A linkage mechanism is provided between the stirring shaft (303) and the circulation pump (8). The linkage mechanism drives the first driving shaft (804) and the second driving shaft (806) to move in opposite directions, and further drives the first piston plate (805) and the second piston plate (807) to reciprocally approach and move away from each other.

7. The production and preparation system of N-methylaniline according to claim 6, characterized in that: The linkage mechanism includes two groups of link mechanisms. The link mechanism includes a power input shaft (9). The two power input shafts (9) are respectively fixed to the two stirring shafts (303). The link mechanism further includes a first link (10), a second link (1001), and a third link (1002).

8. The production and preparation system of N-methylaniline according to claim 7, characterized in that: One end of the first link (10) is fixed to the input shaft (9). The other end of the first link (10) and one end of the second link (1001) are fixed through a first pin shaft (1003). The end of the second link (1001) far from the first pin shaft (1003) is fixed to the third link (1002) through a second pin shaft (1004).

9. The production and preparation system of N-methylaniline according to claim 8, characterized in that: One end of the first drive shaft (804) is fixed with a first drive rod (8041). A fourth connecting rod (8042) is hinged on the first drive rod (8041). One end of the fourth connecting rod (8042) away from the first drive rod (8041) is hinged with a first pin shaft (1003). One end of the second drive shaft (806) is fixed with a second drive rod (8061). A fifth connecting rod (8062) is hinged on the second drive rod (8061). One end of the fifth connecting rod (8062) away from the second drive rod (8061) is hinged with a second pin shaft (1004).

10. A production and preparation system for N-methylaniline according to claim 2, characterized in that: The stirring branches (304) are distributed in an annular array on the outer side of the stirring shaft (303). A cross bar (306) is fixed inside the mixing kettle (3). The top end of the cross bar (306) is fixed with a plugging device (307). The plugging device (307) extends into the stirring branches (304) movably. And the plugging device (307) is of an arc-shaped structure. And a notch is arranged on one side where the plugging devices (307) are close to each other.

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