CN218654509U - Tubular reactor for the preparation of 2,4-dichloronitrobenzene - Google Patents

Abstract

The utility model provides a tubular reactor for preparing 2,4-dichloronitrobenzene belongs to chemical reaction equipment technical field, include: the reaction chamber consists of a plurality of U-shaped reaction tubes which are arranged in parallel and connected end to end, and the heat exchange shell is sleeved outside the reaction chamber; the inlet of the reaction cavity is respectively communicated with a chlorobenzene feeding pipeline and a mixed acid feeding pipeline; the outlet of the reaction cavity is communicated with a product collecting pipeline; the plurality of U-shaped reaction tubes comprise a straight tube section and a bent tube section, wherein the straight tube section is provided with a static mixing element, and the bent tube section is provided with a branch tube; the heat exchange shell comprises a plurality of heat exchange chambers which are arranged in parallel, and the arrangement direction of each heat exchange chamber is vertical to the direction of the straight pipe section. The utility model discloses a tubular reactor for solve in the current tubular reactor double-phase mix the inequality, reaction heat remove difficulty, the unable accurate control of reaction temperature, the inhomogeneous side reaction that causes of temperature distribution takes place to increase, the yield of target product and the relatively poor problem of quality.

Description

Tubular reactor for the preparation of 2,4-dichloronitrobenzene

technical field

The utility model relates to the technical field of chemical reaction equipment, in particular to a tubular reactor for preparing 2,4-dichloronitrobenzene.

Background technique

2,4-Dichloronitrobenzene, CAS number: 611-06-3, molecular formula: C ₆ H ₃ Cl ₂ NO ₂ , molecular weight: 191.9995, light yellow crystal, melting point: 31-34°C, boiling point: 258°C, Water solubility: 188mg/L (20°C), an important intermediate of organic chemical products such as pesticides, medicines, and dyes. With the continuous development of the domestic chemical industry, the market demand for 2,4-dichloronitrobenzene is also increasing. The synthesis process of 2,4-dichloronitrobenzene is to fully react m-dichlorobenzene and mixed acid (nitric acid and sulfuric acid) solution according to a certain ratio to obtain the target product. Since the nitration reaction mainly occurs at the two-phase interface, and a large amount of heat will be generated during the reaction process, the effect of two-phase mixing and the control of the reaction temperature have a direct and significant impact on the reaction conversion rate, selectivity and reaction rate. Influence.

At present, there are mainly two types of reactors used in the production of 2,4-dichloronitrobenzene: tank reactors and tubular reactors. Among them, the tank reactor belongs to batch production. The mechanical driving force of the high-speed stirring paddle is used to make the two phases mix and react. The reaction speed is slow, the cycle is long, and the conversion rate is low, resulting in low production efficiency. And the reaction conditions such as temperature Unstable control, complex and frequent side reactions, resulting in low quality of target products, large amount of mixed acid, large output of waste acid and organic waste liquid, serious environmental pollution, does not meet the requirements of "green chemistry", and the energy consumption of high-speed stirring is relatively high At the same time, due to the limitation of the production process of the reactor and the stirring paddle, the enlargement of the production scale is restricted. Therefore, the application and research of tubular reactors have gradually become a hot spot in recent years.

The tubular reactor is under a certain pressure, the two-phase liquid co-flows through the static mixing element, and reacts in the tubular reactor. The reactor has the advantages of simple structure, low energy consumption, and easy expansion. However, this kind of reactor is prone to uneven mixing during the reaction process, which leads to inconsistent reaction rates at different positions of the reactor, which affects the mass transfer rate and product yield. Moreover, the traditional heat exchange method is to set a heat exchange jacket on the outside of the tubular reactor, but this structure has a poor cooling effect, which will easily lead to difficulty in removing the reaction heat, and will cause the reaction temperature in the tubular reactor to be inaccurate. Shortcomings such as control and uneven temperature distribution will cause an increase in side reactions and affect the yield and quality of the target product.

Utility model content

The utility model provides a tubular reactor for preparing 2,4-dichloronitrobenzene, which is used to solve the problem of uneven mixing of two phases, difficulty in removing reaction heat and inaccurate reaction temperature in the existing tubular reactor. Control, increased side reactions caused by uneven temperature distribution, poor yield and quality of the target product.

The utility model provides a tubular reactor for preparing 2,4-dichloronitrobenzene, which comprises: a reaction chamber composed of a plurality of U-shaped reaction tubes arranged in parallel and connected end to end; The heat exchange shell outside the chamber.

Specifically, the inlet of the reaction chamber is communicated with the chlorobenzene feed pipeline and the mixed acid feed pipeline respectively; the outlet of the reaction chamber is communicated with the product collection pipeline; a plurality of U-shaped reaction tubes include a straight pipe section and an elbow section, and the straight pipe section is provided with Static mixing element, elbow section provided with branch pipes.

Specifically, the heat exchange housing includes a plurality of heat exchange chambers arranged in parallel, and the direction of each heat exchange chamber is perpendicular to the direction of the straight pipe section; each heat exchange chamber is symmetrically provided with medium inlets and medium outlet, and the medium inlet is arranged on the side close to the inlet of the reaction chamber.

Specifically, in each heat exchange chamber, a plurality of baffles are arranged in staggered intervals, and the baffles are perpendicular to the inner wall of the heat exchange chamber.

Specifically, the static mixing element is SMX type, SV type, SH type, SK type, SX type or SL type.

Specifically, the shape of the bent pipe section and the branch pipe is a square or D shape, and the branch pipe is a right angle pipe or an arc pipe.

Specifically, a plurality of distribution components distributed at intervals are arranged in the bent pipe section and the branch pipe, and the flow distribution components and the branch pipe are integrally formed.

Specifically, the flow distribution assembly includes circular columns and diamond-shaped columns, and the circular columns and rhombic columns are respectively arranged alternately in adjacent flow distribution assemblies.

Specifically, the circular column and the diamond-shaped column have the same height, and the contact surfaces of the circular column and the diamond-shaped column have different end surface areas, and the end surface area of the circular column is smaller than that of the diamond-shaped column.

Specifically, on the circular column and the diamond-shaped column, the end faces away from the contact surfaces between the two are respectively connected to the inner walls of the branch pipe and the curved pipe section.

Specifically, one side edge of the diamond-shaped column is vertically facing the direction of material feeding in the branch pipe and the bent pipe section.

Specifically, an arc-shaped concave structure is provided on the side of the circular column facing the feed direction of the material in the branch pipe and the bent pipe section.

The tubular reactor used for preparing 2,4-dichloronitrobenzene of the present invention realizes sufficient mixing of reaction raw materials by setting static mixing elements and branch pipes in the reaction chamber, improves the reaction rate, and can independently Controlled heat exchange chamber to achieve a good temperature control and uniform temperature effect in the reaction process, which can effectively avoid the difficulty of removing the reaction heat, the inaccurate control of the reaction temperature, uneven temperature distribution, reaction hot spots and overheating phenomenon, and reduce side effects. The reaction occurs, thereby improving the selectivity and yield of the target product, and improving the quality stability of the target product.

The nitric acid and m-dichlorobenzene in the reaction material are continuously mixed to varying degrees through the static mixing element and the branch pipe in the reaction chamber. They are mixed during the whole reaction process, which is conducive to the full contact and reaction of the reaction raw materials, and improves the utilization rate of raw materials and The conversion rate is shortened, the reaction cycle is shortened, and the material consumption is reduced. Compared with the batch reactor, the contact between nitric acid and m-dichlorobenzene in the reactor of the utility model is more sufficient, which can properly reduce the amount of mixed acid in the reactor, which is beneficial to reduce production costs, and can also reduce waste liquid Processing capacity, production is more environmentally friendly.

The tubular reactor of the utility model adopts static sealing in all, which avoids the disadvantage that the rotating parts in the traditional stirred tank reactor will weaken the sealing performance, the reactor has better sealing performance, can be produced continuously, and the reaction process is easy to control. The heat transfer efficiency is high, which can effectively avoid the increase of by-products caused by overheating of the reaction, the energy consumption and raw material consumption are low, the production process is safe and reliable, and it is also suitable for the mixing and reaction of flammable, explosive and corrosive materials.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the appended drawings in the following description The drawings show some embodiments of the utility model, and those skilled in the art can also obtain other drawings according to these drawings without creative work.

Fig. 1 is the structural representation of the tubular reactor for preparing 2,4-dichloronitrobenzene provided by an embodiment of the utility model;

Fig. 2 is a schematic structural diagram of an elbow section, a branch pipe and a shunt assembly provided by an embodiment of the present invention;

Fig. 3 is a schematic structural diagram of a shunt assembly provided by an embodiment of the present invention.

Explanation of reference signs:

1-reaction chamber, 2-heat exchange shell, 11-U-shaped reaction tube, 12-chlorobenzene feed pipe, 13-mixed acid feed pipe, 14-product collection pipe, 21-heat exchange chamber, 22-medium inlet , 23-medium outlet, 24-baffle plate, 111-straight pipe section, 112-bent pipe section, 113-branch pipe, 1111-static mixing element, 1121-splitter assembly, 1211-circular column, 1212-rhombic column, 1213 - Curved concave structure.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, and Not all examples. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts also belong to the scope of protection of the present invention.

Referring to shown in Fig. 1, a kind of tubular reactor that is used to prepare 2,4-dichloronitrobenzene provided by the utility model comprises: the reaction tube 11 that is made up of a plurality of U-shaped reaction tubes 11 that are arranged in parallel and connected end to end The cavity 1 and the heat exchange shell 2 sleeved on the outside of the reaction cavity 1 .

In one embodiment, the inlet of reaction chamber 1 communicates with chlorobenzene feed pipeline 12 and mixed acid feed pipeline 13 respectively; and the curved pipe section 112 , the straight pipe section 111 is provided with a static mixing element 1111 , and the curved pipe section 112 is provided with a branch pipe 113 .

Instability of feed (such as speed fluctuation or sudden change of feed amount) can easily lead to axial unevenness of materials in the tubular reactor, which will affect the stable operation of the reaction or lead to the occurrence of adverse side reactions. Setting the static mixing element 1111 can improve the temperature gradient, velocity gradient and mass gradient of the material, realize the sufficient mixing of the reaction raw materials, increase the reaction rate, and also avoid the energy loss of the liquid in the traditional stirred reactor colliding with the wall, and the energy utilization rate is high. The setting of the branch pipe 113 is to facilitate the improvement of the residence time difference caused by the uneven mixing of materials in the straight pipe section 111 in the curved pipe section 112, so that materials with different residence times and different concentrations can be further mixed, and the next straight pipe section 111 can be improved. The axial unevenness of the material can further avoid adverse problems such as increased side reactions and runaway reaction heat caused by the material reacting in the U-shaped reaction tube 11 for too long in an uneven state.

In one embodiment, the heat exchange housing 2 includes a plurality of heat exchange chambers 21 arranged in parallel, and the arrangement direction of each heat exchange chamber 21 is perpendicular to the direction of the straight pipe section 111; A medium inlet 22 and a medium outlet 23 are arranged symmetrically on both sides, and the medium inlet 22 is arranged on a side close to the inlet of the reaction chamber 1 .

Since the nitration reaction is an exothermic reaction, the main function of the heat exchange chamber 21 is to provide a cooling medium to remove the reaction heat, so the medium passed into the heat exchange chamber 21 is cooling water or frozen water. Since the distribution and mixing of materials in the U-shaped reaction tube 11 are different, adopting a single heat exchange medium inlet and outlet is not conducive to zone temperature control. In order to achieve more precise control of the reaction temperature, the heat exchange chamber 21 is set perpendicular to the direction of the straight pipe section 111, so that the flow direction of the medium in the heat exchange chamber 21 is perpendicular to the flow direction of the material in the straight pipe section 111 of the reaction tube 11, so that by adjusting different The flow rate and/or temperature of the medium in the heat exchange chamber 21 can independently and accurately control the reaction temperature in different regions of the reaction tube 11, increase the heat transfer efficiency of the tubular reactor, and help control the reaction rate.

The medium inlet 22 is arranged on the side close to the entrance of the reaction chamber 1, so that the flow direction of the medium adapts to the exothermic law of the continuous reaction of the material, which is more conducive to the heat exchange of the reaction, so that the reaction temperature can be better controlled. The medium inlet 22 and the medium outlet 23 of each heat exchange chamber 21 can be communicated with each other, and can be set independently, so that each heat exchange chamber 21 does not interfere with each other, and can ensure the isothermal operation of the entire reaction chamber 1 . For example, in the front section of the reaction chamber 1, because the concentration of dichlorobenzene and nitric acid in the middle of the reaction raw materials is relatively high, the reaction is violent, and a large amount of heat of reaction is generated, so the temperature of the medium in the heat exchange chamber 21 near the inlet can be lower to provide more Good temperature control and cooling effect, avoiding the occurrence of reaction hot spots and overheating phenomena.

In one embodiment, in each heat exchange chamber 21 , a plurality of baffles 24 are arranged in staggered intervals, and the baffles 24 are perpendicular to the inner wall of the heat exchange chamber 21 .

A baffle 24 is set in the heat exchange chamber 21, so that the medium flows in an "S shape" in the heat exchange chamber 21, which increases the flow path of the cooling medium and increases the contact time between the cooling medium and the reaction chamber 1, which is more beneficial Heat exchange and increased heat transfer efficiency are beneficial to ensure isothermal operation of the reactor.

In one embodiment, the static mixing element 1111 is of SMX type, SV type, SH type, SK type, SX type or SL type.

Wherein, the above-mentioned MX type, SV type, SH type, SK type, SX type or SL type can refer to the relevant description in the SMX type, SV type, SH type, SK type, SX type or SL type static mixer in the prior art , which will not be repeated here.

Using the static mixing element 1111 fixed in the straight pipe section 111 can change the flow state of the material, and can better promote the dispersion and thorough mixing of different reaction raw materials (water phase and oil phase). At the same time, the length of the static mixing element 1111 is adjusted according to the length of the straight pipe section 111, and the quantity is adjusted according to the number of the straight pipe section 111. The general principle is to control the residence time of the reaction material, control the occurrence of side reactions, and increase the product yield.

In one embodiment, the shape of the bent pipe section 112 and the branch pipe 113 is a square or a D shape, and the branch pipe 113 is a right angle pipe or an arc pipe.

Since it is inconvenient to have a built-in static mixing element 1111 in the curved pipe section 112, the material in the curved pipe section 112 is easy to separate into two phases to form a situation of uneven concentration. When the material with uneven concentration enters the next straight pipe section 111, it will first Mixing and then reacting, the reaction efficiency will be reduced and the time required for the reaction will be prolonged. The role of the branch pipe 113 is to change the flow path and residence time of the material. The flow of the elbow section 112 and the branch pipe 113 is different, which can mix and eliminate the uneven distribution of the axial direction to a certain extent, and can avoid the uneven distribution of the material. , reducing the concentration deviation of the two phases. The shape of the branch pipe 113 is S-shaped or D-shaped, and it is a right-angled pipe or an arc-shaped pipe.

As shown in FIG. 2 and FIG. 3 , in one embodiment, a plurality of distribution components 1121 are arranged in the elbow section 112 and the branch pipe 113 at intervals, and the flow distribution components 1121 and the branch pipe 113 are integrally formed.

Distributor assembly 1121 is arranged in elbow section 112 and branch pipe 113 can further improve mixing effect, and material is extruded and divided by flow divider assembly 1121 in elbow section 112 and branch pipe 113, then joins behind flow assembly 1121, and forms vortex, then It is squeezed and divided again by the next dividing component 1121, and the flow is continuously divided and mixed and recombined, thereby realizing high-intensity mixing of materials.

In one embodiment, the splitter assembly 1121 includes circular pillars 1211 and diamond-shaped pillars 1212 , and the circular pillars 1211 and rhombus-shaped pillars 1212 are arranged alternately in adjacent splitter assemblies 1121 .

In one embodiment, the circular column 1211 and the diamond-shaped column 1212 have the same height, and the contact surfaces of the circular column 1211 and the diamond-shaped column 1212 have different end surface areas.

In one embodiment, on the circular column 1211 and the diamond-shaped column 1212 , the end surfaces away from the contact surfaces between them are respectively connected to the inner walls of the branch pipe 113 and the curved pipe section 112 .

In one embodiment, one side edge of the rhombus column 1212 is vertically facing the direction of material feeding in the branch pipe 113 and the curved pipe section 112 .

In one embodiment, an arc-shaped concave structure 1213 is provided on the side of the circular column 1211 facing the feed direction of the material in the branch pipe 113 and the bent pipe section 112 .

The distribution components 1121 are arranged in a staggered manner, and the volume and surface shape of the circular column 1211 and the diamond-shaped column 1212 are different, so that when the material flows in the curved pipe section 112 and the branch pipe 113, it forms a staggered movement on the plane and the vertical surface, effectively increasing the flow rate of the material. The mass transfer between them enables the materials to fully mix and react. The arc-shaped concave treatment of the circular column 1211 can make it easier for the material to form a vortex when flowing, increase the turbulence effect and mass transfer effect, and enhance the mixing effect of the material.

It should be noted that the tubular reactor of the present utility model is also provided with a temperature sensor and a pressure sensor, and the temperature sensor and the pressure sensor are respectively used to detect the temperature and pressure in the reaction tube. In this way, through the temperature sensor and the pressure sensor, Accurately detect the temperature and pressure in the reaction process, and accurately control the temperature and pressure in the reaction according to the detected temperature and pressure values. In addition, the tubular reactor is also provided with a safety relief valve. The positions and structures of the temperature sensor, the pressure sensor and the safety relief valve are not limited and described in detail here.

Below in conjunction with specific embodiment the utility model is described in further detail.

Example 1

A tubular reactor for the preparation of 2,4-dichloronitrobenzene. During specific work, m-dichlorobenzene enters the entrance of the reaction chamber 1 through the chlorobenzene feed pipe 12, and the mixed acid solution enters the reaction chamber through the mixed acid feed pipe 13. The entrance of the chamber 1, the two raw materials enter the U-shaped reaction tube 11 from the entrance of the reaction chamber 1. The reaction raw materials first enter the straight pipe section 111 of the U-shaped reaction pipe 11 , and are mixed and reacted while passing through the static mixing element 1111 . When entering the curved pipe section 112 from the straight pipe section 111, part of the material splits into the branch pipe 113. Because the paths of the curved pipe section 112 and the branch pipe 113 are different, the material residence time and velocity gradient are different. When the materials in 112 recombine, the two streams of materials will naturally mix, thereby improving the axial unevenness of the materials in the next straight pipe section 111. The material circulates, mixes and reacts repeatedly in the straight pipe section 111, the bent pipe section 112 and the branch pipe 113, and finally enters the product collection pipe 14 from the outlet of the reaction chamber 1 to facilitate subsequent refining.

During the reaction, the cooling medium is injected into the heat exchange chamber 21 and the heat exchange shell 2 arranged in parallel through different medium inlets 22 , and after heat exchange in the heat exchange chamber 21 , the medium finally flows out through the medium outlet 23 .

Example 2

In this embodiment, on the basis of Embodiment 1, multiple baffles 24 are arranged in each heat exchange chamber 21. After the cooling medium passes through the baffles 24 to change the flow path in the heat exchange chamber 21, the medium is S-shaped. The flow increases the flow path of the cooling medium, which is more conducive to heat exchange and heat transfer efficiency, and is conducive to ensuring the isothermal operation of the reactor.

Example 3

In this embodiment, on the basis of Embodiment 1, a plurality of integrally formed and distributed distribution components 1121 are arranged in the elbow section 112 and the branch pipe 113. When the material flows in the elbow section 112 and the branch pipe 113, it passes through different When the circular column 1211 and the diamond-shaped column 1212 of the volume and surface shape form a staggered movement on the plane and the vertical surface, the mass transfer between the materials is effectively increased, the materials are continuously divided and mixed and recombined, and the reaction can be fully mixed. The arc-shaped concave structure 1213 of the circular column 1211 can make it easier for the material to form a vortex when flowing, increase the effect of turbulence and mass transfer, and enhance the mixing effect of the material.

It should be noted that, in this utility model, the detailed structure of some devices is not described in detail, but it belongs to the prior art known to those skilled in the art, so it will not be repeated here.

It should be noted that those skilled in the art can make some modifications to the above-mentioned device under the guidance of the utility model. For example, the device is also equipped with liquid level gauges, overflow/nitrogen pipelines, etc.; the conveying pipelines inside the device are equipped with pressure sensors, flow meters or temperature sensors between different units, and are also equipped with different valves, such as pressure relief Valves, pressure regulating valves, safety valves, pneumatic valves, etc. are used to adjust and stabilize the pressure of the entire device, and can also adjust the opening of the valve to adjust the flow of materials in the pipeline.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present utility model, rather than limit it; although the utility model has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand It can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements to some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the various embodiments of the present invention Scope of technical solutions.

Claims (10)

1. a tubular reactor for preparing 2,4-dichloronitrobenzene, characterized in that: comprising: A reaction chamber composed of a plurality of U-shaped reaction tubes arranged in parallel and connected end to end, and a heat exchange shell sleeved outside the reaction chamber; The inlet of the reaction chamber is communicated with the chlorobenzene feed pipeline and the mixed acid feed pipeline respectively; the outlet of the reaction chamber is communicated with the product collection pipeline; The plurality of U-shaped reaction tubes include straight pipe sections and bent pipe sections, the straight pipe sections are provided with static mixing elements, and the bent pipe sections are provided with branch pipes; The heat exchange housing includes a plurality of heat exchange chambers arranged in parallel, and the arrangement direction of each heat exchange chamber is perpendicular to the direction of the straight pipe section; each of the heat exchange chambers is on both sides of the reaction chamber A medium inlet and a medium outlet are arranged symmetrically, and the medium inlet is arranged on a side close to the inlet of the reaction chamber. 2. the tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 1, characterized in that: in each of the heat exchange chambers, a plurality of baffles are arranged alternately at intervals, And the baffle is perpendicular to the inner wall of the heat exchange chamber. 3. The tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 1, characterized in that: said static mixing element is SMX type, SV type, SH type, SK type, SX type type or SL type. 4. the tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 1, characterized in that: the shape of the elbow section and the branch pipe is a shape of a mouth or a D shape, and the The branch pipe is a right angle pipe or an arc pipe. 5. The tubular reactor for preparing 2,4-dichloronitrobenzene according to any one of claims 1-4, characterized in that: the elbow section and the branch pipe are provided with a plurality of Distributing components are distributed at intervals, and the distributing components are integrally formed with the branch pipe. 6. the tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 5, characterized in that: the split flow assembly comprises a circular column and a rhombus column, and the circular column and the The rhombus-shaped upright columns are respectively arranged in a staggered manner in adjacent flow distribution components. 7. the tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 6, characterized in that: the height of the circular column is the same as that of the rhombus column, and the circular column The end surface area of the contact surface between the column and the rhombus column is different, and the end surface area of the circular column is smaller than that of the rhombus column. 8. the tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 7, characterized in that: on the circular column and the rhombus column, the end faces away from the contact surfaces of the two respectively connected with the inner wall of the branch pipe and the bend pipe section. 9. The tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 6, characterized in that: one side edge of the rhomboid column vertically faces the branch pipe and the elbow section The direction in which the material is fed. 10. The tubular reactor for preparing 2,4-dichloronitrobenzene according to claim 6, characterized in that: the circular column faces the material feed in the branch pipe and the elbow section One side of the direction is provided with an arc-shaped concave structure.

Images