CN113683545B - System and method for preparing cyclohexyl hydroperoxide by oxidizing cyclohexane - Google Patents

Abstract

The invention provides a system and method for preparing cyclohexyl hydroperoxide by oxidation of cyclohexane, comprising: a reactor; a partition plate is arranged in the reactor; The position is a reaction section, and the part below the partition plate is a separation section; a micro-interface generator is arranged in the reaction section, and the micro-interface generator is immersed below the liquid surface; the liquid surface in the reaction section A multi-layer sieve plate is arranged above; a cyclohexane inlet and an air inlet are arranged on the side wall of the reaction section; the cyclohexane inlet is vertically arranged above the sieve plate; the air inlet and the The micro-interface generators are connected, and the air is dispersed and broken into micron-level micro-bubbles by the micro-interface generators, and then enters the reaction section. The system of the present invention has low energy consumption, low cost, high safety, low required reaction temperature and pressure, few side reactions and high product yield, and is worthy of wide popularization and application.

Description

A system and method for preparing cyclohexyl hydroperoxide by oxidation of cyclohexane

technical field

The invention relates to the field of cyclohexane oxidation reaction preparation, in particular to a system and method for preparing cyclohexyl hydroperoxide by cyclohexane oxidation.

Background technique

The oxidation of cyclohexane to cyclohexyl hydroperoxide is an important intermediate for the preparation of cyclohexane or cyclohexanone; the cyclohexane air oxidation process is the mainstream process at home and abroad, including non-catalyzed and catalytic oxidation processes; it is generally believed that in the cyclohexane In the process of hexane oxidation, cyclohexane oxidation reaction is a free radical reaction. The cyclohexane oxidation reaction process is as follows: first, the raw material benzene is hydrogenated to generate cyclohexane, then cyclohexane is oxidized by air to generate cyclohexyl hydroperoxide, and cyclohexyl hydroperoxide flows into the next device, under alkaline conditions Hydrolysis produces cyclohexanol and cyclohexanone, after saponification and separation, cyclohexanol enters the dehydrogenation device for dehydrogenation to produce cyclohexanone.

The existing cyclohexane oxidation reaction system mainly has the following problems:

(1) The oxidation reaction adopts the form of five reactors connected in series, and the conversion rate of each tank gradually increases, but the overall single-pass conversion rate is only 3.5%. A large amount of cyclohexane at the outlet of the 5# oxidation tank enters the subsequent separation system, and after purification, it is recycled to the 1# oxidation tank. The inlet of the kettle leads to an increase in the separation energy consumption and power consumption of the whole device;

(2) Reaction temperature (165 ℃) and reaction pressure (1.2MPa) are higher, may cause by-product to increase after temperature rises, unfavorable for improving the yield of cyclohexyl hydroperoxide;

(3) The compressed air is fed by bubbling, and the problems of uneven gas-liquid distribution and low mass transfer efficiency inside the reactor lead to low reaction rate, low equipment utilization rate and uneven oxidation depth. At the same time, exhaust gas is discharged from the top of the reactor. High oxygen content reduces the effective utilization of oxygen in compressed air;

(4) A large amount of cyclohexane and cyclohexyl hydroperoxide oxidation solution enters the decomposition and alkali separation system, resulting in large investment in pipelines, instruments, valves and equipment between the oxidation reaction and the decomposition reaction section.

In view of this, the present invention is proposed.

Contents of the invention

The first purpose of the present invention is to provide a system for producing cyclohexyl hydroperoxide by oxidation of cyclohexane, the system integrates the reaction section and the separation section in a reactor by adopting the scheme of one tower and two kettles for the reactor, The floor area of the system is reduced, and the degree of system integration is improved; by setting a micro-interface generator, the air can be dispersed and broken into micron-level micro-bubbles, which increases the gas-liquid mass transfer area between cyclohexane and improves The oxidation efficiency of cyclohexane.

The second object of the present invention is to provide a preparation method, which is easy to operate, and the obtained cyclohexyl hydroperoxide product is of high quality, which is conducive to reducing energy consumption and achieves a better reaction effect than the existing process.

In order to realize the above-mentioned purpose of the present invention, special adopt following technical scheme:

The invention provides a system for preparing cyclohexyl hydroperoxide by oxidation of cyclohexane, comprising: a reactor; a partition plate is arranged in the reactor; the position above the partition plate in the reactor is In the reaction section, the part below the partition plate is a separation section; a micro-interface generator is arranged in the reaction section, and the micro-interface generator is submerged below the liquid surface;

A multi-layer sieve plate is arranged above the liquid level in the reaction section; a cyclohexane inlet and an air inlet are arranged on the side wall of the reaction section; the cyclohexane inlet is vertically arranged on the sieve plate above; the air inlet is connected to the micro-interface generator, and the air enters the reaction section after being dispersed and broken into micron-level micro-bubbles by the micro-interface generator;

The side wall of the reaction section is provided with a material outlet; the material outlet is arranged vertically below the liquid level in the reaction section; the material outlet is connected to the separation section.

In the prior art, the reaction temperature and pressure of cyclohexane oxidation reaction to prepare cyclohexyl hydroperoxide are high, the by-products are many, and the product yield is low; and in the existing process, compressed air is generally fed by bubbling, but there are still The problems of uneven gas-liquid distribution and low mass transfer efficiency inside the reactor lead to low reaction rate, low equipment utilization rate and uneven oxidation depth. At the same time, the oxygen content of the tail gas discharged from the top of the reactor is relatively high, which reduces the effective oxygen in the compressed air. utilization rate.

In order to solve the above-mentioned technical problems, the present invention provides a system for producing cyclohexyl hydroperoxide by oxidation of cyclohexane. The system integrates the reaction section and the separation section in one reactor by using a reactor with one tower and two kettles. In this way, the floor area of the system is reduced, and the degree of system integration is improved; by setting the micro-interface generator, the air can be dispersed and broken into micron-level micro-bubbles, which increases the gas-liquid mass transfer area between cyclohexane and cyclohexane , improving the oxidation efficiency of cyclohexane.

Preferably, the number of the micro-interface generators is two, the type of the micro-interface generators is a pneumatic micro-interface generator, and the outlets of the two micro-interface generators are arranged opposite to each other. Setting two micro-interface generators can disperse and crush the air at the same time, which improves the dispersion efficiency of the micro-interface; setting the outlets of the two micro-interface generators opposite is to make the two air micro-bubbles hedge against each other and prevent the occurrence of micro-bubbles. Coalesce to make the microbubbles evenly distributed.

Preferably, a gas distribution pipe is provided at the outlet of the micro-interface generator, and the gas distribution pipe communicates with the two micro-interface generators; the surface of the gas distribution pipe is provided with a plurality of air holes. The arrangement of the gas distribution pipe can make the two streams of microbubbles do turbulent movement in the gas distribution pipe, and the microbubbles flow out from the pores, so that the microbubbles are evenly distributed.

Preferably, a liquid distributor is arranged above the sieve plate.

In the present invention, the reactor is divided into an upper reaction section and a lower separation section, with a high degree of integration and a small footprint; wherein, a micro-interface generator connected to the air inlet is arranged in the reaction section, and air enters the micro-interface during reaction. The generator is dispersed and crushed into micron-level microbubbles and then mixed with cyclohexane liquid to form a gas-liquid emulsion, which increases the gas-liquid mass transfer area between cyclohexane and air and improves the reaction efficiency. At the same time, the required reaction temperature and The pressure is greatly reduced,

In the present invention, the number of micro-interface generators is two, the outlets of the two micro-interface generators are opposite, and the outlets of the two micro-interface generators are connected through the gas distribution tube. On the one hand, the microbubbles move in turbulent flow in the gas distribution pipe, and enter the reaction section along the pores on the wall of the gas distribution pipe, which promotes the uniform distribution of the microbubbles; on the other hand, the two microbubbles form a collision flow , further disperse and break through the collision, and improve the mass transfer efficiency of the micro interface.

In addition, the positions of the cyclohexane inlet and the air inlet of the present invention are not randomly arranged. The reason why the air inlet is set below the cyclohexane inlet is because air is a gas, and it is easy to overflow from the outlet. Setting the air inlet below can prolong the reaction path of the air in the reaction section. It is the oxygen in the air and cyclohexane. Alkanes are further reacted to increase the utilization rate and conversion rate of raw materials. The cyclohexane inlet is set at the top for dripping from the upper part, and the liquid distributor is also installed to promote the cyclohexane liquid to drip down evenly from the upper part, and further react with the air overflowing from the upper part of the reaction section to improve the utilization rate of raw materials. A multi-layer sieve plate is also provided above the liquid level in the reaction section, and the sieve plate can reduce the top gas flow rate, so that the falling cyclohexane can fully react with it. It can be seen that the present invention improves the conversion rate of raw materials and reduces the energy consumption required for the reaction by combining the application of the micro-interface generator and the sieve plate, and through the specific setting of its position and the like.

Those skilled in the art can understand that the micro-interface generator used in the present invention has been embodied in the inventor's previous patents, such as application numbers CN201610641119.6, CN201610641251.7, CN201710766435.0, CN106187660, CN105903425A, Patents of CN109437390A, CN205833127U and CN207581700U. The prior patent CN201610641119.6 introduced in detail the specific product structure and working principle of the micro-bubble generator (that is, the micro-interface generator). There is a cavity, the body is provided with an inlet communicating with the cavity, the opposite first end and second end of the cavity are open, and the cross-sectional area of the cavity is from the middle of the cavity to the first end and the second end of the cavity. The second end is reduced; the secondary broken piece is arranged at at least one of the first end and the second end of the cavity, a part of the secondary broken piece is set in the cavity, and the two ends of the secondary broken piece and the cavity are open An annular channel is formed between the through holes. The micron bubble generator also includes an inlet pipe and a liquid inlet pipe.” From the specific structure disclosed in the application document, it can be known that the specific working principle is: the liquid enters the micrometer tangentially through the liquid inlet pipe. In the bubble generator, the gas is rotated and cut at a super high speed, so that the gas bubbles are broken into micron-level micro-bubbles, thereby increasing the mass transfer area between the liquid phase and the gas phase, and the micro-bubble generator in this patent belongs to the pneumatic micro-interface generation device.

In addition, it is recorded in the prior patent 201610641251.7 that the primary bubble breaker has a circulating liquid inlet, a circulating gas inlet, and a gas-liquid mixture outlet, while the secondary bubble breaker connects the feed port with the gas-liquid mixture outlet, indicating that the bubble breaker is both Gas-liquid mixing is required. In addition, it can be seen from the following drawings that the primary bubble breaker mainly uses circulating fluid as power, so in fact, the primary bubble breaker belongs to the hydraulic micro-interface generator, and the secondary bubble breaker is a gas-liquid breaker. The mixture is passed into the elliptical rotating ball for rotation at the same time, so that the bubbles are broken during the rotation process, so the secondary bubble breaker is actually a gas-liquid linkage micro-interface generator. In fact, whether it is a hydraulic micro-interface generator or a gas-liquid linkage micro-interface generator, they all belong to a specific form of the micro-interface generator, but the micro-interface generator used in the present invention is not limited to the above-mentioned several forms The specific structure of the bubble breaker described in the prior patents is only one of the forms that the micro-interface generator of the present invention can adopt.

In addition, it is recorded in the previous patent 201710766435.0 that "the principle of the bubble breaker is high-speed jet flow to achieve gas collision", and it is also explained that it can be used in micro-interface strengthening reactors to verify the relationship between the bubble breaker and the micro-interface generator. and the prior patent CN106187660 also has relevant records for the specific structure of the bubble breaker, specifically see paragraphs [0031]-[0041] in the description, and the accompanying drawings, which describe the bubble breaker S-2 The specific working principle of the bubble breaker is described in detail. The top of the bubble breaker is the liquid phase inlet, and the side is the gas phase inlet. The liquid phase coming in from the top provides the entrainment power, so as to achieve the effect of crushing into ultra-fine bubbles, which can also be seen in the attached drawings. The bubble breaker has a conical structure, and the diameter of the upper part is larger than that of the lower part, which is also for the liquid phase to provide better entrainment power.

Since the micro-interface generator was just developed in the early stage of the patent application, it was named micro-bubble generator (CN201610641119.6) and bubble breaker (201710766435.0) in the early stage. With continuous technological improvement, it was later renamed as micro-interface generator Device, now the micro-interface generator in the present invention is equivalent to the previous micro-bubble generator, bubble breaker, etc., but the name is different. In summary, the micro-interface generator of the present invention belongs to the prior art.

Preferably, the air inlet is connected with an air pipeline, and a gas filter is arranged on the air pipeline, and the air flows into the reaction section after being filtered by the gas filter. The air is filtered and then sent to the reaction section, which effectively prevents impurities in the air from clogging the micro-interface generator.

Preferably, the material outlet is connected to a circulating external cooler, and the circulating external cooler is connected to the micro-interface generator; a part of the material generated in the reaction section enters the separation section, and the other part passes through the circulating After being cooled by the external cooler, it flows back into the micro-interface generator.

Preferably, the cyclohexane inlet is connected with a cyclohexane pipeline; the top of the separation section is connected with a reflux tank, and the reflux tank is connected with the cyclohexane pipeline, and the cyclohexane separated by the reflux tank Hexane returns to the reaction section to continue the reaction.

Preferably, a condenser is connected to the bottom of the separation section, and the product separated by the separation section is condensed by the condenser and then extracted.

The present invention also provides a kind of preparation method of the system that adopts above-mentioned cyclohexane oxidation to prepare cyclohexyl hydroperoxide, comprises the steps:

After the air is dispersed and broken into micron-level microbubbles through the micro-interface, it is mixed with cyclohexane for oxidation reaction, and then separated to obtain cyclohexyl hydroperoxide.

Preferably, the oxidation reaction temperature is 150-160° C., and the pressure is 0.6-1.0 MPa.

The cyclohexyl hydroperoxide product obtained by adopting the reaction method of the invention has good quality and high yield. In addition, the preparation method itself has low reaction temperature, greatly reduced pressure, and significantly reduced cost.

Compared with prior art, the beneficial effect of the present invention is:

(1) The system for preparing cyclohexyl hydroperoxide by cyclohexane oxidation of the present invention adopts the scheme of one tower and two kettles for the reactor, and integrates the reaction section and the separation section in one reactor, thereby reducing the floor area of the system , improving the degree of system integration;

(2) By setting the micro-interface generator, the air can be dispersed and broken into micron-level micro-bubbles, which increases the gas-liquid mass transfer area with cyclohexane and improves the oxidation efficiency of cyclohexane;

(3) The outlets of the two micro-interface generators are facing each other and the outlets of the two micro-interface generators are connected through the gas distribution pipe. On the one hand, the microbubbles do turbulent movement in the gas distribution pipe, The pores on the wall enter the reaction section, which promotes the uniform distribution of microbubbles; on the other hand, two streams of microbubbles form a collision flow, which is further dispersed and broken by collision, which improves the mass transfer efficiency of the microinterface.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating a preferred embodiment and are not to be considered as limiting the invention. Also throughout the drawings, the same reference numerals are used to designate the same components. In the attached picture:

Fig. 1 is the structural representation of the system of cyclohexane oxidation preparation cyclohexyl hydroperoxide that the embodiment of the present invention provides;

Fig. 2 is the structural representation of the reactor that the embodiment of the present invention provides;

Fig. 3 is a schematic structural diagram of a gas distributor provided by an embodiment of the present invention;

Fig. 4 is a structural schematic diagram of a system for producing cyclohexyl hydroperoxide by oxidation of cyclohexane in the prior art.

Description of drawings:

10-cyclohexane pipeline; 20-air pipeline;

30-gas filter; 40-reactor;

50-reaction section; 501-air inlet;

502-cyclohexane import; 503-sieve plate;

504-micro-interface generator; 505-gas distribution tube;

506-material outlet; 507-air hole;

508-liquid distributor; 60-separation section;

70-reflux tank; 80-condenser;

90-circulating external cooler; 100-dividing plate.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are some of the embodiments of the present invention, rather than all of them. It is only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, or in a specific orientation. construction and operation, therefore, should not be construed as limiting the invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and should not be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it may be mechanically connected or electrically connected; it may be directly connected or indirectly connected through an intermediary, and it may be the internal communication of two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

In order to illustrate the technical solution in the present invention more clearly, the following will be described in the form of specific examples.

Example

Referring to Figures 1-3, the present embodiment provides a system for producing cyclohexyl hydroperoxide by oxidation of cyclohexane, comprising: a reactor 40; a partition plate 100 is arranged in the reactor 40; The position above the partition plate 100 is the reaction section 50, and the part below the partition plate 100 is the separation section 60; a micro-interface generator 504 is arranged in the reaction section, and the micro-interface generator 504 is immersed below the liquid surface;

The top of the liquid surface in the reaction section 50 is provided with a multi-layer sieve plate 503; the side wall of the reaction section 50 is provided with a cyclohexane inlet 502 and an air inlet 501; Above; the air inlet 501 is connected to the micro-interface generator 504, and after the air is dispersed and broken into micron-level microbubbles by the micro-interface generator 504, it enters the reaction section 50; the side wall of the reaction section 50 is provided with a material outlet 506; the material outlet 506 It is arranged vertically below the liquid level in the reaction section 50 ; the material outlet 506 is connected with the separation section 60 .

In order to promote the even dripping of the liquid, a liquid distributor 508 is arranged above the sieve plate 503 .

In this embodiment, there are two micro-interface generators 504, and the outlets of the two micro-interface generators 504 are arranged opposite to each other. A gas distribution manifold 505 is provided at the outlet of the micro-interface generator 504, and the gas distribution manifold 505 communicates with the two micro-interface generators 504; the surface of the gas distribution manifold 505 is provided with a plurality of air holes 507. The two streams of microbubbles move in turbulent flow in the gas distribution manifold 505, and the microbubbles flow out from the pores 507, so that the microbubbles are evenly distributed.

The micro-interface generator 504 can be a pneumatic micro-interface generator, a hydraulic micro-interface generator or a gas-liquid linkage micro-interface generator. In this embodiment, the two micro-interface generators 504 are pneumatic micro-interface generators.

As shown in FIG. 1 , in this embodiment, the air inlet 501 is connected to the air pipeline 20 , and the air pipeline 20 is provided with a gas filter 30 , and the air flows into the reaction section 50 after being filtered by the gas filter 30 . The material outlet 506 is connected with a circulating external cooler 90, and the circulating external cooler 90 is connected with the micro interface generator 504; part of the material generated in the reaction section 50 enters the separation section 60, and the other part flows back to the micro interface after being cooled by the circulating external cooler 90. interface generator 504. The cyclohexane inlet 502 is connected with a cyclohexane pipeline 10; the top of the separation section 60 is connected with a reflux tank 70, and the reflux tank 70 is connected with the cyclohexane pipeline 10, and the cyclohexane separated by the reflux tank 70 returns to the reaction section 50 continue to react. A condenser 80 is connected to the bottom of the separation section 60 , and the product separated by the separation section 60 is condensed by the condenser 80 and then extracted.

In fact, the reflux tank 70 is also provided with a waste water outlet and a waste gas outlet for discharging the separated waste water and waste gas. A gas outlet is provided at the top of the reaction section 50, and tail gas generated by the reaction is discharged from the gas outlet.

During the reaction, air and cyclohexane are fed into the reaction section 50 . After the air is dispersed and broken into micron-level microbubbles through the micro-interface, it is mixed with cyclohexane for oxidation reaction, and then separated by the separation section 60 to obtain cyclohexyl hydroperoxide.

The specific reaction conditions are as follows: control the total feed flow rate of air to 21.3m ³ /h, cyclohexane feed to 5.0m ³ /h, under the conditions of 150°C, 0.6Mpa; 155°C, 0.8Mpa; 160°C, 1.0Mpa react separately. The specific experimental parameters are as follows:

Table 1

Experimental example 4

The difference between this example and Experimental Example 2 is that no micro-interface generator and gas distribution header are used. The reaction parameters are as follows: the residence time of the liquid phase is 55 min, the space-time yield is 0.0298 t/(m ³ ·h), and the single pass conversion rate of cyclohexane is 3.6%.

Experimental example 5

The difference between this example and Experimental Example 2 is that only a micro-interface generator is used and no gas distribution manifold is used. The reaction parameters are as follows: the residence time of the liquid phase is 43 min, the space-time yield is 0.0323 t/(m ³ ·h), and the single pass conversion rate of cyclohexane is 4.3%.

comparative example

As shown in FIG. 4 , it is a schematic structural diagram of an oxidation system in the prior art. Control the total feed flow rate of air to 21.3m ³ /h, feed cyclohexane to 5.0m ³ /h, and carry out the reaction at 165°C and 1.2Mpa. The specific parameters of the reaction are as follows: Among them, the residence time of the liquid phase is 54.8min , the space-time yield is 0.0293t/(m ³ ·h), and the single-pass conversion rate of cyclohexane is 3.5%.

By comparison, compared with the prior art, the required energy consumption of the system of the present invention is significantly reduced, and the conversion rate of raw materials is greatly improved.

In a word, compared with the prior art, the system of the present invention has low energy consumption, low cost, high safety, low required reaction temperature and pressure, few side reactions, and high product yield, and is worthy of wide application.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (1)

1. a device for producing cyclohexyl hydroperoxide by cyclohexane oxidation, is characterized in that, comprises: reactor; Dividing plate is arranged in described reactor; Be positioned at above described dividing plate in described reactor The position is a reaction section, and the part located below the partition plate is a separation section; a micro-interface generator is arranged in the reaction section, and the micro-interface generator is submerged below the liquid surface; A multi-layer sieve plate is arranged above the liquid level in the reaction section; a cyclohexane inlet and an air inlet are arranged on the side wall of the reaction section; the cyclohexane inlet is vertically arranged on the sieve plate above; the air inlet is connected to the micro-interface generator, and the air enters the reaction section after being dispersed and broken into micron-level micro-bubbles by the micro-interface generator; The side wall of the reaction section is provided with a material outlet; the material outlet is arranged vertically below the liquid level in the reaction section; the material outlet is connected to the separation section; The number of the micro-interface generators is two, the type of the micro-interface generators is a pneumatic micro-interface generator, and the outlets of the two micro-interface generators are arranged oppositely; The outlet of the micro-interface generator is provided with a gas distribution pipe, and the gas distribution pipe is connected to the two micro-interface generators; the surface of the gas distribution pipe is provided with a plurality of air holes; A liquid distributor is arranged above the sieve plate; The air inlet is connected with an air pipeline, and a gas filter is arranged on the air pipeline, and the air flows into the reaction section after being filtered by the gas filter; The material outlet is connected to a circulating external cooler, and the circulating external cooler is connected to the micro-interface generator; a part of the material generated in the reaction section enters the separation section, and the other part passes through the circulating external cooler Flow back into the micro-interface generator after cooling; The cyclohexane inlet is connected with a cyclohexane pipeline; the top of the separation section is connected with a reflux tank, and the reflux tank is connected with the cyclohexane pipeline, and the cyclohexane separated by the reflux tank returns to Continue to react in the reaction section; A condenser is connected to the bottom of the separation section, and the product separated by the separation section is condensed by the condenser and then extracted.

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