A multi-vessel series reactor

Abstract

The utility model relates to chemical reaction equipment field discloses a kind of multi-kettle series reactor, including first reaction kettle, second reaction kettle and third reaction kettle, the discharge outlet of first reaction kettle is connected by pipeline one second reaction kettle's feed inlet, the discharge outlet of second reaction kettle is connected by pipeline two third reaction kettle's feed inlet, first reaction kettle, second reaction kettle and third reaction kettle are all provided with stirring assembly in, and the stirring assembly includes driving motor, stirring shaft one, stirring shaft two, bevel gear one, bevel gear two, bevel gear three and stirring paddle.In the utility model, by setting stirring shaft one and stirring shaft two coaxial reverse structure, cooperate the stirring paddle of opposite rotation, can form the shear flow field of up and down convection in kettle, need not rely on static blade to realize gas-liquid-solid three-phase efficient mixing, hydrogen gas bubble is fully sheared and broken, solid catalyst is suspended uniformly, avoid deposition accumulation, improve reaction rate.

Description

Technical Field

[0001] This utility model relates to the field of chemical reaction equipment, and in particular to a multi-tank reactor in series. Background Technology

[0002] Hydrogenation is an important unit operation in the production of chemical, pharmaceutical, and fine chemicals, and is widely used in the synthesis of pharmaceutical intermediates, dye manufacturing, and fragrance preparation. Traditional hydrogenation often uses batch high-pressure reactors, while multi-reactor series reactors are widely used in continuous hydrogenation production because they allow for staged control of the reaction process.

[0003] To improve reaction controllability, existing technologies have developed reaction systems that use multiple continuous stirred tanks in series. However, conventional series systems still have some shortcomings: the stirring components are mostly single-axis stirring structures, which can only form a unidirectional flow field. In scenarios such as hydrogenation of nitrobenzene that require efficient mass transfer, the contact between the gas, liquid, and solid phases is insufficient. Hydrogen bubbles are prone to agglomerate into large bubbles and escape, and solid catalysts are prone to deposit at the bottom of the tank, resulting in low reaction rates and difficulty in ensuring product selectivity, leading to hydrogen waste and reduced product yield. Utility Model Content

[0004] To overcome the above shortcomings, this utility model provides a multi-reactor series reactor, which aims to solve the problem of "insufficient contact between gas, liquid and solid phases causing hydrogen waste and reduced product yield" in the prior art.

[0005] To achieve the above objectives, this utility model adopts the following technical solution: a multi-tank reactor in series, comprising a first reactor, a second reactor, and a third reactor. The outlet of the first reactor is connected to the inlet of the second reactor via a pipe one, and the outlet of the second reactor is connected to the inlet of the third reactor via a pipe two. Each of the first, second, and third reactors is equipped with a stirring assembly, which includes a drive motor, a stirring shaft one, a stirring shaft two, a bevel gear one, a bevel gear two, a bevel gear three, and a stirring paddle. The drive motor is fixed to the top of the first and second reactors. The first bevel gear is fixedly connected to the output shaft of the drive motor. The first stirring shaft vertically passes through the top center of the first and second reaction vessels and is rotatably connected to the first and second reaction vessels. The second bevel gear is fixedly connected to the top of the first stirring shaft and is coaxially rotatably connected to the inner cavity of the first stirring shaft. The third bevel gear is fixedly connected to the top of the second stirring shaft. The top of the first bevel gear meshes with the third bevel gear, and the bottom of the first bevel gear meshes with the second bevel gear. Stirring blades are fixedly connected to the bottom circumferential outer walls of both the first and second stirring shafts, and the stirring blades on the surfaces of the first and second stirring shafts rotate in opposite directions.

[0006] As a further description of the above technical solution: Both pipeline one and pipeline two are equipped with one-way check valves in the middle.

[0007] As a further description of the above technical solution: The top of the first, second, and third reaction vessels is equipped with a hydrogen inlet pipe, which is connected to a hydrogen source via a flow proportional valve.

[0008] As a further description of the above technical solution: The top of the first reactor is fixedly connected to a feed pipe, which is connected to the raw material storage tank via a metering pump.

[0009] As a further description of the above technical solution: The bottom of the third reactor is fixedly connected to a discharge pipe, which is connected to downstream equipment or stored in a product storage tank via a back pressure regulating valve.

[0010] As a further description of the above technical solution: The first, second, and third reaction vessels are all filled with replaceable catalyst baskets. The catalyst baskets are filled with supported metal catalysts selected from one or more of Pd / C, Pt / Al2O3, and Raney nickel. Different types or activities of catalysts can be filled in different reaction vessels.

[0011] As a further description of the above technical solution: The first, second, and third reaction vessels are equipped with pressure sensors, temperature sensors, and controllers on their surfaces, and the pressure sensors and temperature sensors are electrically connected to the controllers respectively.

[0012] As a further description of the above technical solution: Sampling valves are fixedly connected to the bottom of the first, second, and third reaction vessels.

[0013] This utility model has the following beneficial effects: 1. In this utility model, by setting a coaxial and reverse structure of stirring shaft one and stirring shaft two, and cooperating with stirring paddles rotating in opposite directions, a shear flow field of vertical convection can be formed in the reactor. Efficient mixing of gas, liquid and solid phases can be achieved without relying on stationary blades. Hydrogen bubbles are fully sheared and broken, solid catalyst is suspended uniformly, avoiding deposition and accumulation, accelerating the contact between hydrogen and substrate, and improving the reaction rate.

[0014] 2. In this utility model, by setting independent flow ratio valves in the hydrogen inlet pipes of each reactor, hydrogen can be supplied on demand. The first reactor can be set with a higher hydrogen flow rate to meet the needs of rapid reaction, while the second and third reactors gradually reduce the hydrogen flow rate to avoid excessive hydrogen causing side reactions of over-hydrogenation. Compared with the traditional unified hydrogen supply mode, the hydrogen utilization rate is improved. Attached Figure Description

[0015] Figure 1 This is a three-dimensional structural diagram of the overall device in this utility model; Figure 2 This is a three-dimensional structural schematic diagram of the overall device from another perspective in this utility model; Figure 3 This is a three-dimensional cross-sectional view of the stirring assembly in this utility model; Figure 4 This utility model Figure 3 A magnified three-dimensional structural diagram at point A in the middle.

[0016] Legend: 11. First reactor; 12. Second reactor; 13. Third reactor; 14. Pipeline 1; 15. Pipeline 2; 2. Stirring assembly; 21. Drive motor; 221. Stirring shaft 1; 222. Stirring shaft 2; 231. Bevel gear 1; 232. Bevel gear 2; 233. Bevel gear 3; 24. Stirring paddle; 3. One-way check valve; 4. Hydrogen inlet pipe; 41. Flow proportional valve; 111. Feed pipe; 112. Metering pump; 131. Discharge pipe; 132. Back pressure regulating valve; 51. Pressure sensor; 52. Temperature sensor; 53. Controller; 61. Sampling valve. Detailed Implementation

[0017] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0018] Reference Figure 1 and Figure 2 This utility model provides an embodiment of a multi-stage series reactor, comprising a first reactor 11, a second reactor 12, and a third reactor 13. The outlet of the first reactor 11 is connected to the inlet of the second reactor 12 via a pipe 14, and the outlet of the second reactor 12 is connected to the inlet of the third reactor 13 via a pipe 2 15, forming a three-stage series continuous flow reaction system. Both pipe 14 and pipe 2 15 are equipped with one-way check valves 3 in the middle to prevent high-pressure hydrogen or reactants from flowing back to the upstream reactor, ensuring unidirectional flow of materials, maintaining the reaction sequence of each stage and the stability of the system. Each of the first reactor 11, the second reactor 12, and the third reactor 13 is equipped with a stirring assembly 2.

[0019] Reference Figure 2 - Figure 4The stirring assembly 2 includes a drive motor 21, a first stirring shaft 221, a second stirring shaft 222, a first bevel gear 231, a second bevel gear 232, a third bevel gear 233, and a stirring paddle 24. The drive motor 21 is fixed to the top of the first reactor 11 and the second reactor 12. The first bevel gear 231 is fixedly connected to the output shaft of the drive motor 21. The first stirring shaft 221 vertically passes through the top center of the first reactor 11 and the second reactor 12 and is rotatably connected to the first reactor 11 and the second reactor 12, and is rotatably sealed to them through a sealed bearing. The second bevel gear 232 is fixedly connected to the top of the first stirring shaft 221. The second stirring shaft 222... The stirring shaft 221 is coaxially rotatably connected to the inner cavity of the stirring shaft 221 and rotates with it. The two can rotate relative to each other. The bevel gear 233 is fixedly connected to the top of the stirring shaft 222. The top of the bevel gear 231 meshes with the bevel gear 233, and the bottom of the bevel gear 231 meshes with the bevel gear 232. The stirring blades 24 are fixedly connected to the bottom circumferential outer walls of both the stirring shaft 221 and the stirring shaft 222. The blades of the stirring blades 24 on the surfaces of the stirring shaft 221 and the stirring shaft 222 rotate in opposite directions, which plays a coaxial reversal role, enhances the gas-liquid-solid three-phase mass transfer, and can accelerate the contact between hydrogen and substrate in the nitrobenzene hydrogenation scenario, thereby increasing the reaction rate.

[0020] Reference Figure 1 and Figure 2 The top of the first reactor 11, the second reactor 12 and the third reactor 13 are all equipped with hydrogen inlet pipes 4. The hydrogen inlet pipes 4 are connected to the hydrogen source through the flow proportional valve 41 to realize independent hydrogen supply in stages. The flow proportional valve 41 can dynamically adjust the hydrogen flow according to the reaction requirements of each stage to avoid side reactions caused by excessive hydrogen supply in the first stage or insufficient hydrogen in the last stage affecting the conversion rate.

[0021] Reference Figure 1 - Figure 3 The top of the first reactor 11 is fixedly connected to a feed pipe 111, which is connected to the raw material storage tank via a metering pump 112. The metering pump 112 is model MRA11-D48 and is used to precisely control the liquid phase feed rate to ensure stable system residence time. The bottom of the third reactor 13 is fixedly connected to a discharge pipe 131, which is connected to downstream equipment or stored in a product storage tank via a back pressure regulating valve 132. The back pressure regulating valve 132 is model RXBF-A40 / 1.0-F and is used to maintain constant pressure in the system, promote hydrogen dissolution, and prevent gas-liquid stratification.

[0022] Reference Figure 1 and Figure 2The first reactor 11, the second reactor 12, and the third reactor 13 are all filled with replaceable catalyst baskets. The catalyst baskets are porous stainless steel cylindrical structures that can be loaded or removed vertically from the top of the reactor. The catalyst baskets are filled with supported metal catalysts selected from one or more of Pd / C, Pt / Al2O3, and Raney nickel. Different types or activities of catalysts can be filled in different reactors to achieve a segmented catalytic function design. In homogeneous or heterogeneous hydrogenation reactions, this structure can avoid over-hydrogenation or by-product generation caused by excessively high catalyst concentration in a single reactor, thereby improving the selectivity of the target product.

[0023] Reference Figure 1 - Figure 3 The surfaces of the first reactor 11, the second reactor 12, and the third reactor 13 are equipped with pressure sensors 51, temperature sensors 52, and controllers 53. Pressure sensors 51 and temperature sensors 52 are electrically connected to controllers 53. Temperature sensors 52 enable independent temperature control of each reactor stage. Controllers 53 are equipped with touch screens to display the temperature, pressure, and stirring speed parameters of each reactor stage. The first two reactor stages are controlled at 100~120℃ to accelerate the nitro reduction reaction rate. The final reactor stage 13 is controlled at 70~80℃ to suppress further hydrogenation of aniline to generate byproducts such as cyclohexylamine, significantly improving the selectivity of the target product aniline.

[0024] Reference Figure 1 - Figure 3 The bottom of the first reaction vessel 11, the second reaction vessel 12 and the third reaction vessel 13 are all fixedly connected with sampling valves 61. Samples inside the reaction vessels can be extracted and tested through the sampling valves 61. The sampling valves 61 are pressure-resistant needle valves and can extract samples of the reaction liquid at each stage by manual or automatic means for offline analysis of conversion rate and selectivity, which is convenient for process optimization and process monitoring.

[0025] Working principle: Before starting the system, check the status of each valve to ensure that the back pressure regulating valve 132 and sampling valve 61 are closed and the one-way check valve 3 is installed in the correct direction. Load the required catalyst into the replaceable catalyst basket 7 of each reactor according to the process requirements and seal it into the reactor through the top quick-opening flange. Then, turn on the metering pump 112 to send the pre-prepared methanol liquid raw material of nitrobenzene from the raw material storage tank into the first reactor 11 at a constant flow rate through the feed pipe 111. At the same time, hydrogen is introduced into each reactor through the hydrogen inlet pipe 4 at the top of each reactor and the flow proportioning valve 41. The hydrogen flow rate of each stage is set independently according to the needs of the reaction stage. The first reactor has a larger hydrogen supply to meet the initial rapid reduction requirements. The hydrogen supply to subsequent reactors is gradually reduced to avoid excess hydrogen causing side reactions.

[0026] After the drive motor 21 starts, it drives the bevel gear 231 to rotate. Since the bevel gear 231 meshes with the upper bevel gear 233 and the lower bevel gear 232 at the same time, it drives the stirring shaft 222 to rotate with the stirring shaft 221 at the same speed but in opposite directions. The stirring paddles 24 installed at the bottom of the two shafts form a strong shear flow and circulating flow field in the reaction liquid because the blades rotate in opposite directions. This achieves coaxial reverse stirring, enhances the bubble dispersion effect, improves the mass transfer coefficient of hydrogen in the liquid phase, and enables hydrogen molecules to diffuse more efficiently to the catalyst surface to participate in the reaction, thereby increasing the hydrogenation rate.

[0027] After the reactants undergo preliminary hydrogenation in the first reactor 11, they enter the second reactor 12 through the one-way check valve 3 in pipeline 14. The one-way check valve 3 prevents high-pressure hydrogen from flowing back to the upstream stage, ensuring the one-way nature of the reaction process and the safety of the system. In the second reactor 12, the hydrogenation reaction continues, and the reaction temperature is maintained at 100~120℃ to accelerate the conversion of intermediates.

[0028] Subsequently, the material flows into the third reactor 13 through pipeline 2 15. The reaction temperature in this stage is controlled at a relatively low 70~80℃, which aims to inhibit the further hydrogenation of target products such as aniline to generate byproducts such as cyclohexylamine or cyclohexanol, thereby improving the selectivity of the final product. The pressure of the entire system is precisely maintained at the set value of 2.0MPa by the electronic back pressure regulating valve 132 to ensure that hydrogen is fully dissolved and to avoid gas-liquid separation.

[0029] Temperature and pressure data at each stage of the reaction process are collected in real time by pressure sensor 51 and temperature sensor 52 and transmitted to controller 53. Operators can monitor the operating status through a touch screen and adjust the stirring speed, heating power, or gas flow rate as needed. In addition, samples can be taken periodically through the bottom sampling valve 61 for GC or HPLC analysis to evaluate the conversion rate and selectivity at each stage, achieving closed-loop process optimization. Finally, the liquid product after complete reaction is continuously discharged through discharge pipe 131 and enters downstream separation units such as distillation column or crystallizer to achieve product recovery.

[0030] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A multi-tank reactor in series, comprising a first reactor (11), a second reactor (12), and a third reactor (13), characterized in that: The outlet of the first reactor (11) is connected to the inlet of the second reactor (12) through pipe one (14), and the outlet of the second reactor (12) is connected to the inlet of the third reactor (13) through pipe two (15). A stirring assembly (2) is provided in the first reactor (11), the second reactor (12) and the third reactor (13). The stirring assembly (2) includes a drive motor (21), a stirring shaft one (221), a stirring shaft two (222), a bevel gear one (231), a bevel gear two (232), a bevel gear three (233), and a stirring paddle (24). The drive motor (21) is fixed to the top of the first reactor (11) and the second reactor (12). The bevel gear one (231) is fixedly connected to the output shaft of the drive motor (21). The stirring shaft one (221) vertically passes through the top center of the first reactor (11) and the second reactor (12) and is rotatably connected to the first reactor (11) and the second reactor (12). The bevel gear one (231) is fixed to the top of the second reactor (12). The second (232) is fixedly connected to the top of the first (221) stirring shaft. The second (222) stirring shaft is coaxially rotatably connected to the inner cavity of the first (221) stirring shaft. The third (233) bevel gear is fixedly connected to the top of the second (222) stirring shaft. The top of the first (231) bevel gear meshes with the third (233) bevel gear. The bottom of the first (231) bevel gear meshes with the second (232) bevel gear. The bottom circumferential outer walls of the first (221) and the second (222) stirring shaft are both fixedly connected with stirring paddles (24), and the fan blades of the stirring paddles (24) on the surfaces of the first (221) and the second (222) stirring shaft rotate in opposite directions.

2. The multi-tank reactor according to claim 1, characterized in that: One-way check valves (3) are provided in the middle of both pipeline one (14) and pipeline two (15).

3. A multi-tank reactor according to claim 1, characterized in that: The top of the first reactor (11), the second reactor (12) and the third reactor (13) are all provided with hydrogen inlet pipes (4), and the hydrogen inlet pipes (4) are connected to the hydrogen source through a flow proportional valve (41).

4. A multi-tank reactor according to claim 1, characterized in that: The top of the first reactor (11) is fixedly connected to a feed pipe (111), which is connected to the raw material storage tank through a metering pump (112).

5. A multi-tank reactor according to claim 1, characterized in that: The bottom of the third reactor (13) is fixedly connected to a discharge pipe (131), which is connected to downstream equipment or stored in a product storage tank through a back pressure regulating valve (132).

6. A multi-tank reactor according to claim 1, characterized in that: The first reactor (11), the second reactor (12) and the third reactor (13) are all filled with replaceable catalyst baskets. The catalyst baskets are filled with supported metal catalysts selected from one or more of Pd / C, Pt / Al2O3 and Raney nickel. Different types or activities of catalysts can be filled in different reactors.

7. A multi-tank reactor according to claim 1, characterized in that: The first reactor (11), the second reactor (12) and the third reactor (13) are provided with a pressure sensor (51), a temperature sensor (52) and a controller (53) on their surfaces. The pressure sensor (51) and the temperature sensor (52) are electrically connected to the controller (53) respectively.

8. A multi-tank reactor according to claim 1, characterized in that: Sampling valves (61) are fixedly connected to the bottom of the first reactor (11), the second reactor (12) and the third reactor (13).

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