Accelerating tubular reactor and application thereof

Abstract

The invention belongs to the technical field of chemical production, provides an accelerating tubular reactor and application thereof, and solves the problems of high thermal runaway risk and local overheating in the prior art. The accelerating tubular reactor comprises an overflow cavity, a heat exchange tube, an accelerating cavity and a circulating pump. The mass transfer and heat transfer effects of the system in the reaction process are good, the local overheating phenomenon is avoided, and the process safety is remarkably improved; the reactor is of a tubular structure, the size reaches the cm level, and the reactor is suitable for large-scale industrial production; the reactor adopts a tubular structure, so that engineering amplification can be realized by increasing the number of tubes, and the amplification risk is low; the technology is a continuous technology, the production efficiency is high, the automation degree of the device is high, the safety of the reaction process is improved, and the green, safe and efficient production requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of chemical production, in particular to an accelerating tubular reactor and application thereof. Background Art

[0002] The chemical industry production process involves many liquid-liquid heterogeneous reaction systems. Because the reaction process occurs at the interface between two phases, the reaction effect usually depends on the mass transfer efficiency and mixing degree between the phases. Since most liquid-liquid heterogeneous reaction processes are complex, the mass transfer and mixing performance of the reactor used has a great influence on the reaction process.

[0003] For continuous tubular reactors, traditional mass transfer enhancement is mostly achieved by adding a mixer at the front end of the reactor. Its basic working mechanism is to use the mixing unit fixed in the tube to change the flow state of the fluid in the tube, so as to achieve good dispersion and full mixing between different fluids. Pipeline mixers are divided into jet pipeline mixers, vortex pipeline mixers and static pipeline mixers according to the mixing methods such as nozzle type, vortex type, porous plate or special-shaped plate type.

[0004] For liquid-liquid heterogeneous interface reactions with poor emulsification, such as the mononitration of aromatic hydrocarbons under dilute acid conditions, although this mixer can achieve good mixing effects in a short time, as the feed liquid flows in the reactor, the droplets in the two-phase system gradually aggregate and stratify, and it is impossible to maintain a good mixing effect and meet the mixing requirements of the reaction process. In particular, it is difficult to achieve tubular continuous production for reactions with high requirements for mixing effects and long reaction cycles. Although some reactions can increase the emulsification stability of the system by using phase transfer catalysts, the increase in catalysts will not only increase the cost of raw materials, but also increase the difficulty of product post-processing, and also affect product quality, which is not an ideal solution. For heterogeneous reactions with large apparent process heat release, high requirements for mass transfer and heat transfer in the reaction process, and long reaction cycles, in order to maintain reaction selectivity, it is difficult to accelerate the reaction speed by conventional forced methods such as heating and increasing the concentration of reactants. The risk of thermal runaway in the traditional kettle reactor process is high, and local hot spots are prone to occur, affecting product quality. However, it is impossible to achieve long-term reaction by using microchannels and ordinary tubular reactors. Strengthening process conditions to shorten reaction time will reduce reaction selectivity, affect product quality, and make industrial application impossible. Therefore, for this type of reaction, it is still necessary to develop appropriate continuous process intensification technology and equipment. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems in the prior art and provide an accelerating tubular reactor and application thereof.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides an accelerating tubular reactor, comprising an overflow chamber 1, a heat exchange tube 2, an accelerating chamber 3, and a circulating pump 4.

[0008] Preferably, the overflow chamber 1 is provided with a pressure balance port 7 and an overflow port 8 .

[0009] Preferably, thermometers 5 are provided at both ends of the heat exchange tube 2 .

[0010] Preferably, the acceleration chamber 3 is provided with a feed port 6, and a rotating shaft is provided inside the acceleration chamber 3, and the rotating speed of the rotating shaft is 1000-10000 rpm.

[0011] Preferably, the outlet of the acceleration chamber 3 is connected to the inlet of the overflow chamber 1 , and the outlet of the overflow chamber 1 is connected to the inlet of the heat exchange tube 2 ; the circulation pump 4 is arranged between different heat exchange tubes 2 ; the last stage heat exchange tube 2 is connected to the acceleration chamber 3 through the feed port 6 .

[0012] Preferably, the material circulates inside the accelerating tubular reactor, with a circulation period of 5 to 15 cycles / minute and a circulation flow rate of 0.5 to 1 m / s.

[0013] The invention also provides application of the accelerating tubular reactor in heterogeneous interface reaction.

[0014] Preferably, the number of series-connected stages of the accelerating tubular reactor is ≤6.

[0015] The present invention provides an accelerating tubular reactor, comprising an overflow chamber, a heat exchange tube, an accelerating chamber, and a circulating pump, to solve the problem that the traditional tubular reactor has poor mixing effect and is not suitable for reactions with long reaction time. According to the requirements of heterogeneous interface reaction enhancement and residence time, a single-stage or multi-stage series method is used for continuous synthesis. During continuous operation, the reaction raw materials are pre-mixed according to the process ratio, added to the accelerator and the tubular reactor through a metering pump to complete the reaction, and the product liquid enters the receiver.

[0016] The accelerated tubular reactor provided by the present invention does not use a phase transfer catalyst during the reaction process, and adopts an acceleration device to achieve heterogeneous mass transfer enhancement, thereby solving the problems of heterogeneous mass transfer and heat transfer obstacles with long reaction time, low selectivity, poor product quality, etc. The present invention adopts a multi-stage overflow and graded temperature control method to achieve heterogeneous interface reaction enhancement and continuous synthesis. Compared with the traditional kettle reactor, the tubular reactor increases the heat exchange area to improve the heat exchange efficiency, avoids local overheating caused by mass transfer and heat transfer obstacles during the reaction process, and improves production safety and process stability; the reaction raw materials are mixed and enhanced by the accelerator to achieve a molecular-level mixing degree, and the mixing effect is maintained in the reactor through appropriate speed circulation, which greatly enhances the mixing effect of the device, avoids the generation of multiple nitrate byproducts caused by uneven mixing, and ensures reaction efficiency and product quality. The product has the advantages of good selectivity, high production efficiency, high safety, and less three wastes, and meets the requirements of process safety and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the accelerating tubular reactor of the present invention;

[0018] Among them, 1 is the overflow chamber, 2 is the heat exchange tube, 3 is the acceleration chamber, 4 is the circulation pump, 5 is the thermometer, 6 is the feed port, 7 is the pressure balance port, 8 is the overflow port, and 9 is the drain port;

[0019] Figure 2 It is a structural schematic diagram of the heterogeneous interface reaction device of the present invention;

[0020] Among them, A is the raw material tank, B is the raw material tank, C is the metering pump, D is the metering pump, E is the accelerating tubular reactor, F is the heat exchanger, and G is the product tank. DETAILED DESCRIPTION

[0021] The present invention provides an accelerating tubular reactor, comprising an overflow chamber 1, a heat exchange tube 2, an accelerating chamber 3, and a circulating pump 4.

[0022] In the present invention, the overflow chamber 1 is provided with a pressure balance port 7 and an overflow port 8 .

[0023] In the present invention, thermometers 5 are provided at both ends of the heat exchange tube 2 .

[0024] In the present invention, the heat exchange tubes 2 adopt a tube-in-tube structure and are vertically arranged in the shell, and process heat exchange is achieved through the heat exchange medium in the shell.

[0025] In the present invention, the acceleration chamber 3 is provided with a feed port 6 , the number of which can be increased or decreased according to the specific reaction, and one of the feed ports is connected to the heat exchange tube 2 .

[0026] In the present invention, a rotating shaft is arranged inside the acceleration chamber 3, and the rotating speed of the rotating shaft is preferably 1000-10000rpm, more preferably 2000-8000rpm, and more preferably 4000-6000rpm; the rotating shaft is connected to the motor outside the acceleration chamber, and the material is efficiently mixed by the high-speed rotating shaft.

[0027] In the present invention, the outlet of the acceleration chamber 3 is connected to the inlet of the overflow chamber 1, and the outlet of the overflow chamber 1 is connected to the inlet of the heat exchange tube 2; the circulation pump 4 is arranged between different heat exchange tubes 2; the last stage heat exchange tube 2 is connected to the acceleration chamber 3 through the feed port 6.

[0028] In the present invention, the material circulates inside the accelerating tubular reactor, and the circulation period is preferably 5 to 15 cycles / minute, more preferably 6 to 14 cycles / minute, and more preferably 8 to 12 cycles / minute; the circulation flow rate is preferably 0.5 to 1 m / s, more preferably 0.6 to 0.9 m / s, and more preferably 0.7 to 0.8 m / s.

[0029] In the present invention, the material in the reactor is powered by a circulation pump 4 and circulates in the reactor. The raw material is added into the reactor through the feed port 6 at the upper end of the acceleration chamber 3, and flows into the overflow chamber 1 and the heat exchange tube 2 after being fully mixed with the circulating liquid, and then circulates back to the acceleration chamber 3. When the liquid level in the overflow chamber 1 rises to the overflow port 8 as the material increases, the reaction liquid flows out of the reactor from the overflow port 8 as the raw material is continuously added. The average residence time of the material can be freely controlled by changing the feeding rate. During the reaction, the material is continuously circulated in the reactor by the circulation pump 4, and is continuously mixed by the accelerator, thereby ensuring the mixing effect during the reaction; at the same time, the liquid flows between the heat exchange tubes 2 at both ends, which can achieve efficient heat transfer and ensure that the reaction heat is removed in time.

[0030] In the present invention, after the reaction is completed, the reaction system is discharged through the drain port 9.

[0031] The structural schematic diagram of the accelerating tubular reactor of the present invention is as follows Figure 1 shown.

[0032] The invention also provides application of the accelerating tubular reactor in heterogeneous interface reaction.

[0033] The present invention also provides a heterogeneous interface reaction device, which comprises a raw material tank, a product tank, a metering pump, a heat exchanger and an accelerating tubular reactor.

[0034] In the present invention, the heterogeneous interfacial reaction device simultaneously transports the raw materials in the raw material tank to the accelerating tubular reactor through a metering pump. The number of series-connected accelerating tubular reactors can be adjusted according to actual process conditions. The product output from the last accelerating tubular reactor is cooled by a heat exchanger and then collected in a product tank.

[0035] The structural schematic diagram of the heterogeneous interface reaction device in the present invention is as follows Figure 2 shown.

[0036] In the present invention, the number of series-connected stages of the accelerating tubular reactor is ≤6.

[0037] In the present invention, the single-stage residence time of the accelerating tubular reactor is preferably ≥5 min, more preferably ≥10 min, and more preferably ≥15 min.

[0038] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0039] Example 1

[0040] Accelerating tubular reactor: the outlet of the accelerating chamber is connected to the inlet of the overflow chamber, and the outlet of the overflow chamber is connected to the inlet of the heat exchange tube; the circulating pump is arranged between different heat exchange tubes; the heat exchange tube of the last stage is connected to the accelerating chamber through the feed port, and a rotating shaft is arranged inside the accelerating chamber, and the rotating shaft is connected to the motor; the heat exchange tube adopts a tube-in-tube structure and is vertically arranged in the shell, and thermometers are arranged at both ends of the heat exchange tube; the overflow chamber is provided with a pressure balance port and an overflow port.

[0041] Heterogeneous interface reaction device: a raw material tank, a product tank, a metering pump, a heat exchanger and an accelerating tubular reactor are set up, and the series number of the accelerating tubular reactor is 2.

[0042] The above equipment is used to continuously produce mononitrobenzene, including the following steps: the single-stage residence time of the accelerating tubular reactor is 10 minutes, the total residence time is 20 minutes, the reaction temperature is 65°C, the circulation flow rate is 0.8m / s, and the rotating shaft speed in the mixing chamber is 1500rpm; sulfuric acid and nitric acid are mixed to form a mixed acid, wherein the sulfuric acid concentration is 70% and the nitric acid concentration is 98.0%; the molar ratio of benzene, nitric acid and sulfuric acid is 1.2:1.0:4; benzene and nitric acid are simultaneously introduced into the first-stage accelerating tubular reactor, the material liquid is collected and statically layered, the upper organic phase is washed with water, and the obtained organic phase is the product. After the system runs stably, the nitric acid conversion rate is 98.08%, the mononitrobenzene content in the product is 85.0%, and the benzene content is 13.1%.

[0043] Example 2

[0044] The same accelerating tubular reactor and heterogeneous interface reaction device as in Example 1 were used, and the number of series stages was 4.

[0045] The continuous production of mononitrobenzene using the above equipment includes the following steps: the single-stage residence time of the accelerated tubular reactor is 5 minutes; the reaction adopts a graded temperature control method, the feed liquid temperature in the first reactor is 40-50°C, the temperature in the second and third reactors is 50-60°C; the temperature in the fourth reactor is 60-70°C, the circulation flow rate is 0.5m / s, and the rotor speed in the mixing chamber is 2500rpm; sulfuric acid and nitric acid are mixed to form a mixed acid, wherein the sulfuric acid concentration is 72% and the nitric acid concentration is 98.0%; benzene and nitric acid are simultaneously introduced into the first reactor, the feed liquid is statically layered, the upper organic phase is washed with water, and the obtained organic phase is the product. The molar ratio of benzene, nitric acid and sulfuric acid is 1.04:1.0:2; after stable operation, the nitric acid conversion rate is 98.16%, the mononitrobenzene content in the product is 93.7%, and the benzene content is 6.2%.

[0046] Comparative Example

[0047] The continuous production process of mononitrobenzene in a kettle includes the following steps: a total of 3 reactors, a single-stage residence time of 10 minutes, a total residence time of 30 minutes, and a reaction temperature of 45-55°C; sulfuric acid and nitric acid are mixed to form a mixed acid, wherein the sulfuric acid concentration is 70-75%, and the nitric acid concentration is 98.0%; the molar ratio of benzene, nitric acid and sulfuric acid is 1.5:1.0:4; benzene and nitric acid are simultaneously introduced into the first-stage reactor of the continuous kettle reactor, the liquid extracted from the third-stage reactor is statically layered, the upper organic phase is washed with water, and the obtained organic phase is the product. After the system runs stably, the nitric acid conversion rate is 97.08%, the mononitrobenzene content in the product is 77.8%, and the benzene content is 22.1%.

[0048] It can be seen from the above embodiments that the present invention provides an accelerated tubular reactor, which has good mass and heat transfer effects in the system during the reaction, does not cause local overheating, and significantly improves process safety; the reactor is a tubular structure with a size of cm level, which is suitable for large-scale industrial production; the reactor adopts a shell-and-tube structure, and engineering scale-up can be achieved by increasing the number of shells and tubes, with low scale-up risk; the process of the present invention is a continuous process technology with high production efficiency and high degree of device automation, which improves the safety of the reaction process and meets the requirements of green, safe and efficient production.

[0049] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An accelerating tubular reactor, characterized in that: It comprises an overflow chamber (1), a heat exchange tube (2), an acceleration chamber (3), and a circulation pump (4).

2. The accelerating tubular reactor according to claim 1, characterized in that: The overflow chamber (1) is provided with a pressure balance port (7) and an overflow port (8).

3. The accelerating tubular reactor according to claim 1 or 2, characterized in that: Thermometers (5) are provided at both ends of the heat exchange tube (2).

4. The accelerating tubular reactor according to claim 3, characterized in that: The acceleration chamber (3) is provided with a feed port (6), and a rotating shaft is provided inside the acceleration chamber (3), and the rotating speed of the rotating shaft is 1000-10000 rpm.

5. The accelerating tubular reactor according to claim 4, characterized in that: The outlet of the acceleration chamber (3) is connected to the inlet of the overflow chamber (1), and the outlet of the overflow chamber (1) is connected to the inlet of the heat exchange tube (2); the circulation pump (4) is arranged between different heat exchange tubes (2); and the heat exchange tube (2) at the last stage is connected to the acceleration chamber (3) through the feed port (6).

6. The accelerating tubular reactor according to claim 1 or 5, characterized in that: The material circulates inside the accelerating tubular reactor, with a circulation period of 5 to 15 cycles / minute and a circulation flow rate of 0.5 to 1 m / s.

7. Use of the accelerating tubular reactor according to any one of claims 1 to 6 in heterogeneous interfacial reactions.

8. The use according to claim 7, characterized in that The number of series-connected stages of the accelerating tubular reactor is ≤6.

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