Preparation system and preparation method of phenol acetone

Description

A kind of preparation system and preparation method of phenol acetone Technical Field The invention belongs to the technical field of phenol acetone preparation, and in particular to a phenol acetone preparation system and a preparation method. Background Art Phenol is a widely used organic chemical raw material, and its main preparation method is the cumene method. Among them, the reaction of cumene with oxygen to form cumene hydroperoxide (CHP for short) is a key step in the production of phenol acetone. The specific reaction is as follows: Main reaction: Side effects: The existing industrial production process of cumene oxidation to produce phenol acetone is mainly divided into the following steps: cumene is oxidized to produce CHP; after CHP is concentrated, it is decomposed with acid to obtain a crude phenol and acetone solution; after the crude phenol and acetone solution is neutralized with acid, it is separated by distillation to obtain phenol acetone products. However, the reaction system for preparing phenol acetone in the prior art comprises the following problems: First, the reactor of the oxidation section adopts a bubbling reactor. The volume of bubbles in the reactor is too large to fully contact with the liquid cumene, thus reducing the reaction efficiency of the system; Second, during the oxidation process, as the concentration of cumene hydroperoxide (CHP) increases, the reaction temperature rises, while the CHP residence time is prolonged and the side reaction products increase significantly. In view of this, the present invention is proposed. Summary of the invention The first object of the present invention is to provide a phenol acetone preparation system, which combines the enhanced reaction technology into the phenol acetone preparation process, effectively improves the reaction efficiency of the raw materials and the utilization rate of oxygen, while reducing the reaction temperature and reaction time. The second object of the present invention is to provide a method for preparing phenol acetone using the above-mentioned preparation system, which is simple to operate, has milder operating conditions, and has low energy consumption, achieving a better processing effect than the existing technology process. In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: The present invention provides a system for preparing phenol acetone, comprising: An oxidation unit, the oxidation unit comprising an oxidation tower, a first built-in strengthening unit is arranged inside the oxidation tower, and the first built-in strengthening unit is arranged at the top of the oxidation tower; The first built-in enhancement unit includes a first enhancement reactor and a second enhancement reactor, the first enhancement reactor is arranged above the second enhancement reactor, a connecting pipe is arranged between the first enhancement reactor and the second enhancement reactor, and the first enhancement reactor is arranged above the liquid surface; A pre-reaction pipeline is provided in the middle of the oxidation tower, and the pre-reaction pipeline is connected to the outlet of the second enhanced reactor; The condensation unit comprises a reaction kettle, a second built-in strengthening unit is arranged inside the reaction kettle, and the second built-in strengthening unit is arranged at the top of the reaction kettle. In the prior art, the following problems mainly exist when preparing phenol acetone: 1. The reactor in the oxidation section adopts a typical bubbling reactor, and the opening size of the gas distributor is millimeter-level. The bubble size is relatively large, generally in the millimeter-centimeter range, and the bubbles tend to coalesce during their ascent in the oxidation tower, resulting in a limited gas-liquid interface area and low mass transfer and reaction efficiency; 2. During the oxidation reaction, as the concentration of cumene hydroperoxide (CHP) increases, the reaction temperature rises, the CHP residence time increases, and the side reaction products increase significantly; 3. The oxygen content in the gas phase at the top of the oxidation tower is high, the oxygen utilization rate is low, and the energy consumption is high. In order to solve the above technical problems, the present invention provides a preparation system of phenol acetone. The preparation system has a simple overall structure. By arranging a first built-in intensification unit in a reaction tower, the reaction raw materials and oxygen can be broken and dispersed into micron-level bubbles, thereby increasing the macroscopic reaction rate and improving the mass transfer area between the gas-liquid two phases. By arranging a pre-reaction pipeline in the middle part of the oxidation tower and connecting the pre-reaction pipeline with a second intensified reactor, the reaction time can be extended, and the reaction is carried out inside the pre-reaction pipeline. Isopropylbenzene and oxygen can be preliminarily mixed to avoid the polymerization of oxygen and improve the utilization rate of oxygen. Preferably, multiple layers of baffles are sequentially arranged inside the pre-reaction pipe from top to bottom, and the multiple layers of baffles are staggered; Preferably, the baffle is arranged to be inclined downward in a direction away from the inner wall of the pre-reaction pipe, and the inclination angle between the baffle and the side wall of the pre-reaction pipe is 70-90°. The baffle is arranged to extend the residence time of the reaction raw materials in the pre-reaction pipe through the baffle, break the vortex and eddy current in the pre-reaction pipe through the baffle, so that the reaction raw materials and oxygen are mixed more evenly in the pre-reaction pipe, reduce the problem of insufficient local mixing or dead corners, and thus improve the mixing efficiency; and, by setting the baffle, the temperature distribution inside the liquid is improved, and the heat transfer efficiency is improved; and the reason why the angle between the baffle and the side wall of the pre-reaction pipe is set to 70-90° is that at 70-90°, the shear force of the mixing can be reduced to a certain extent, the reaction raw materials can be stirred more gently, and the production of by-products can be avoided. Specifically, there are three baffles, which are equiangularly distributed on the side wall of the pre-reaction pipe along the circumferential direction. The baffle at the top of the three baffles has an inclination angle of 70°, the baffle at the middle has an inclination angle of 80°, and the baffle at the bottom has an inclination angle of 90°. This arrangement can increase the mixing effect in a gradient manner, further extend the flow path of the reaction raw materials, and at the bottom The baffle is perpendicular to the inner wall of the pre-reaction pipe, which can effectively break up the vortex and eddy current and improve the mitigation effect. Preferably, a third enhanced reactor is provided at the bottom of the oxidation tower, and the outlet of the third enhanced reactor is opposite to the outlet of the pre-reaction pipeline. By providing the third enhanced reactor opposite to the outlet of the pre-reaction pipeline, hedging can be achieved. Preferably, the inner wall of the oxidation tower is provided with an inner coil, the length of which matches the length of the spiral pipe. The inner coil can be provided to assist in adjusting and controlling the reaction temperature. Specifically, the cooling water inlet of the inner coil is arranged above the cooling water outlet, and such an arrangement can reduce the reaction temperature. Preferably, an external strengthening unit is arranged outside the oxidation tower, the external strengthening unit is connected to the first internal strengthening unit, the external strengthening unit comprises a fourth strengthening reactor and a fifth strengthening reactor, and a connecting pipe is arranged between the fourth strengthening reactor and the fifth strengthening reactor. By arranging the external strengthening unit, the reaction raw materials and oxygen are crushed and dispersed before entering the reaction tower, the phase boundary mass transfer area is increased, and the reaction rate is improved. In the present invention, a first built-in strengthening unit is arranged in the oxidation tower, and the built-in strengthening unit is composed of a first strengthening reactor and a second strengthening reactor. The two strengthening reactors are arranged in an upper and lower position and connected by a connecting pipe; wherein, the unreacted gas at the main tower top of the first strengthening reactor is entrained, and after being dispersed and crushed again, it is returned to the second strengthening reactor through the connecting pipe to continue the reaction, thereby improving the conversion rate of oxygen; the second strengthening reactor is arranged below the first strengthening reactor, and the second strengthening reactor is connected to the external strengthening unit, and the reaction raw materials and oxygen introduced into the oxidation tower are dispersed and crushed for a second time, and the pressure energy of the gas transported into the oxidation tower or the kinetic energy of the circulating liquid is converted into the surface energy of the bubble and transferred to the oxygen, so that the oxygen is broken to form micron-sized bubbles to react with the isopropylbenzene solution, thereby improving the mass transfer area of ​​the gas-liquid two-phase, and improving the conversion rate and utilization rate of isopropylbenzene and oxygen; the microbubbles of the first strengthening reactor can be dispersed again after entering the second strengthening reactor through the connecting pipe, thereby improving the uniformity of its distribution in the liquid raw material. In addition, the setting of the connecting pipe can also support the second strengthening reactor and improve the overall structural strength. The pre-reaction pipe in the oxidation tower is also provided with a baffle. The baffle of the present invention is multi-layered, preferably three-layered, and has a certain inclination angle. The inclination angles of the three-layer baffles increase successively, which can extend their residence time in the pre-reaction pipe. The inclined setting of the baffles breaks the vortex and eddy current in the pre-reaction pipe, so that the reaction raw materials and oxygen are mixed more evenly in the pre-reaction pipe, reducing the problem of insufficient local mixing or dead corners. A third enhanced reactor is also arranged below the pre-reaction pipeline and is connected to the oxygen inlet. This arrangement is because by-products will be produced during the oxidation reaction of isopropylbenzene, which will inhibit the oxidation reaction. Therefore, it is necessary to introduce oxygen in small amounts multiple times to avoid the production of by-products and to improve the conversion rate and utilization rate of oxygen. The reactor of the present invention is provided with a second built-in strengthening unit, which is composed of a sixth strengthening reactor and a seventh strengthening reactor. The two strengthening reactors are respectively arranged on opposite side walls in the reactor and have opposite outlets. Such an arrangement can form a collision flow between the two strengthening reactors to improve the dispersion effect. Those skilled in the art will appreciate that the enhanced reactor used in the present invention has been embodied in the inventor's prior patents, such as patents with application numbers CN201610641119.6, CN201610641251.7, CN201710766435.0, CN106187660, CN105903425A, CN109437390A, CN205833127U and CN207581700U. The specific product structure and working principle of the micron bubble generator (i.e., microinterface generator) are described in detail in the prior patent CN201610641119.6. The application document states that "the micron bubble generator includes a main body and a secondary crushing member, a cavity is provided in the main body, an inlet connected to the cavity is provided on the main body, and the first and second opposite ends of the cavity are open, wherein the cross-sectional area of ​​the cavity decreases from the middle of the cavity to the first and second ends of the cavity; the secondary crushing member is provided at at least one of the first and second ends of the cavity, a part of the secondary crushing member is provided in the cavity, and an annular channel is formed between the secondary crushing member and the through holes open at both ends of the cavity. The micron bubble generator also includes an air inlet pipe and a liquid inlet pipe." From the specific structure disclosed in the application document, it can be known that its specific working principle is: the liquid enters the micron bubble generator tangentially through the liquid inlet pipe, rotates at ultra-high speed and cuts the gas, so that The gas bubbles are broken into micro-bubbles at the micron level, thereby increasing the mass transfer area between the liquid phase and the gas phase, and the micro-bubble generator in this patent is a pneumatic micro-interface generator. In addition, the prior patent 201610641251.7 records that the primary bubble breaker has a circulating liquid inlet, a circulating gas inlet and a gas-liquid mixture outlet, and the secondary bubble breaker connects the feed port with the gas-liquid mixture outlet, indicating that the bubble breaker requires gas-liquid mixture to enter. In addition, it can be seen from the following figures that the primary bubble breaker mainly uses circulating liquid as power, so the primary bubble breaker is actually a hydraulic micro-interface generator, and the secondary bubble breaker simultaneously passes the gas-liquid mixture into an elliptical rotating ball for rotation, thereby achieving bubble breaking 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, it is a specific form of a micro-interface generator. However, the micro-interface generator adopted by the present invention is not limited to the above-mentioned forms. The specific structure of the bubble breaker recorded in the prior patent is only one of the forms that the micro-interface generator of the present invention can adopt. In addition, the prior patent 201710766435.0 states that "the principle of the bubble breaker is to use high-speed jets to achieve mutual collision of gases", and also explains that it can be used in a micro-interface enhanced reactor, verifying the correlation between the bubble breaker and the micro-interface generator; and the prior patent CN106187660 also has relevant records on the specific structure of the bubble breaker, see the specification for details.

[0031] -

[0041] , as well as the attached drawings, provide a detailed description of the specific working principle of the bubble breaker S-2. The top of the bubble breaker is a liquid inlet, and the side is a gas inlet. The liquid phase coming in from the top provides suction power, thereby achieving the effect of crushing into ultra-fine bubbles. It can also be seen in the attached drawings that the bubble breaker has a conical structure, and the diameter of the upper part is larger than that of the lower part, so that the liquid phase can better provide suction power. Since the micro-interface generator was just developed in the early stage of the prior patent application, it was named micron bubble generator (CN201610641119.6), bubble breaker (201710766435.0), etc. in the early stage. With the continuous technical improvement, it was later renamed as micro-interface generator. Now the enhanced reactor in the present invention is equivalent to the previous micron bubble generator, bubble breaker, etc., but the name is different. In summary, the enhanced reactor of the present invention belongs to the prior art. Preferably, the fourth enhanced reactor is connected to the cumene inlet, and the fifth enhanced reactor is connected to the oxygen inlet; Preferably, an air filter is provided between the oxygen inlet and the fifth enhanced reactor; Preferably, the cumene inlet and the oxygen inlet are connected with a regulating valve and a flow meter respectively. By setting the regulating valve and the flow meter, the feed amount of cumene and oxygen can be adjusted and controlled. Preferably, a reflux pipeline is arranged outside the oxidation tower, the inlet of the reflux pipeline is connected to the side wall of the oxidation tower, and the outlet of the reflux pipeline is connected to the bottom of the oxidation tower; Preferably, the reflux pipeline is connected to a circulating cooler, and the circulating cooler is respectively connected to the reflux pipeline inlet and the crude product outlet. Preferably, a stirring paddle is provided at the bottom of the reactor, and a stirring blade is connected to the stirring paddle, and the stirring blade is provided below the second built-in strengthening unit. A stirring paddle is provided in the reactor, and the stirring paddle cooperates with the second built-in strengthening unit to stir the microbubbles, thereby improving the uniformity of their dispersion in the liquid in the reactor and further improving the reaction effect. Preferably, a tail gas outlet is provided at the top of the reactor, and the tail gas outlet is connected to the first enhanced reactor and the tail gas washing tower through gas pipelines respectively. In addition, the present invention also provides a method for preparing phenol acetone, and the phenol acetone is prepared by using the above reaction system. Preferably, the preparation method comprises the following steps: cumene and oxygen are reacted to generate a crude solution of phenol and acetone after enhanced crushing and dispersion; and the phenol and acetone solutions are condensed to generate phenol acetone. Preferably, the oxidation reaction temperature is 50-70°C, and the condensation reaction temperature is 80-100°C. The preparation method of the invention is simple to operate, can effectively improve the conversion rate of reactants and the yield of products, and at the same time, reduces the reaction time, increases the reaction temperature, and significantly reduces the cost. Compared with the prior art, the present invention has the following beneficial effects: (1) The preparation system of the present invention is provided with an oxidation tower and a reaction kettle, and a first built-in strengthening unit and a second built-in strengthening unit are respectively provided therein, thereby effectively improving the reaction efficiency and the conversion rate of the raw materials; (2) The present invention changes the traditional bubbling reactor into an enhanced technology to enhance the oxygen to the isotropic The mass transfer process in the propylbenzene solution significantly increases the macroscopic reaction rate and improves the space-time yield of the oxidation tower by 20% to 30%, thereby improving the oxidation reaction efficiency, shortening the reaction time, and reducing the generation of by-products. BRIEF DESCRIPTION OF THE DRAWINGS Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings: FIG1 is a schematic structural diagram of a system for preparing phenol acetone provided in Example 1 of the present invention; FIG2 is a schematic diagram of the structure of the pre-reaction pipeline provided in Example 1 of the present invention. in: 1-Oxidation tower; 2-First built-in strengthening unit; 201-first enhanced reactor; 202-second enhanced reactor; 203-connecting pipe; 3-pre-reaction pipeline; 301- baffle; 4- third enhanced reactor; 5-inner coil; 501-cooling water inlet; 502-cooling water outlet; 6-external strengthening unit; 601-the fourth enhanced reactor; 602-the fifth enhanced reactor; 603-connecting pipeline; 7-cumene inlet; 8- oxygen inlet; 9- air filter; 10- regulating valve; 11- flow meter; 12- reflux pipeline; 121- circulation cooler; 13-reactor; 14-second built-in strengthening unit; 141-sixth enhanced reactor; 142-seventh enhanced reactor; 15-stirring paddle; 151-stirring blade; 16- tail gas outlet; 17- gas pipeline; 18- tail gas scrubber; 19- oxygen tank. DETAILED DESCRIPTION The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used, they are all conventional products that can be purchased commercially. In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In order to more clearly explain the technical solution of the present invention, it is described in the form of specific embodiments below. Example 1 1-2 shows a system for preparing phenol acetone according to an embodiment of the present invention, which includes an oxidation unit and a condensation unit connected in sequence; The oxidation unit includes an oxidation tower 1, wherein a first built-in strengthening unit 2 is arranged inside the oxidation tower 1, and the first built-in strengthening unit 2 is arranged at the top of the oxidation tower 1, and the first built-in strengthening unit 2 includes a first strengthening reactor 201 and a second strengthening reactor 202, the first strengthening reactor 201 is arranged above the second strengthening reactor 202, a connecting pipe 203 is arranged between the first strengthening reactor 201 and the second strengthening reactor 202, and the first strengthening reactor 201 is arranged above the liquid surface; an external strengthening unit 6 is arranged outside the oxidation tower 1, and the external strengthening unit 6 includes a fourth strengthening reactor 601 and a fifth strengthening reactor 602, the fourth strengthening reactor 601 is arranged above the fifth strengthening reactor 602, and a connecting pipe 603 is arranged between the fourth strengthening reactor 601 and the fifth strengthening reactor 602, specifically, the fourth strengthening reactor 601 is connected to the isopropylbenzene inlet 7, the fifth strengthening reactor 602 is connected to the oxygen inlet 8, and the second strengthening reactor 202 is connected to the external strengthening unit 6. After being dispersed and crushed into micron-sized bubbles in the external intensification unit 6, the isopropylbenzene liquid and oxygen enter the oxidation tower 1 and are crushed and dispersed for the second time through the second intensification reactor 202 to increase the mass transfer area of ​​the phase boundary between the gas and liquid phases. In order to accurately control the reaction system, the cumene inlet 7 and the oxygen inlet 8 are respectively connected to a regulating valve 10 and a flow meter 11, which can adjust and control the feed amounts of cumene liquid and oxygen. In order to ensure the purity of the produced phenol acetone, an air filter 9 is provided between the oxygen inlet 8 and the fifth enhanced reactor 602 to ensure the purity of the oxygen entering the oxidation tower 1. In this embodiment, the first enhanced reactor 201 is located at the top of the oxidation tower 1, and the first enhanced reactor 201 is located above the liquid level of the oxidation tower 1, and the gas above the liquid level in the oxidation tower 1 enters the first enhanced reactor 201 through the gas pipeline 17. During the reaction, the unreacted gas above the liquid level of the oxidation tower 1 is sucked into the first enhanced reactor 201 through the gas pipeline 17, and after being dispersed and crushed in the first enhanced reactor 201, it returns to the oxidation tower 1 to continue the reaction, thereby improving the conversion rate of oxygen. A pre-reaction pipe 3 is arranged in the middle part of the oxidation tower 1, and the pre-reaction pipe 3 is connected to the outlet of the second enhanced reactor 202. A third enhanced reactor 4 is arranged at the bottom end of the oxidation tower 1, and the third enhanced reactor 4 is connected to the oxygen inlet 8, and the outlet of the third enhanced reactor 4 is opposite to the outlet of the pre-reaction pipe 3. Such an arrangement can realize the offset of the reactants in the pre-reaction pipe 3 and the oxygen microbubbles at the outlet of the third enhanced reactor 4, thereby achieving the effect of stirring the reaction raw materials and improving the reaction rate. Continuing to refer to FIG. 2 , a plurality of baffles 301 are sequentially arranged inside the pre-reaction pipe 3 from top to bottom, and the plurality of baffles 301 are arranged in an alternating manner; specifically, the baffles 301 are arranged obliquely downward in a direction away from the inner wall of the pre-reaction pipe 3, and an inclination angle between the baffles 301 and the side wall of the pre-reaction pipe 3 is 70-90°. Specifically, in this embodiment, there are three baffles 301, which are circumferentially distributed at equal angles on the outer wall of the pre-reaction pipe 3. The baffle 301 at the top of the three baffles 301 has an inclination angle of 70°, the baffle 301 at the middle has an inclination angle of 80°, and the baffle 301 at the bottom has an inclination angle of 90°. This arrangement can increase the mixing effect in a gradient, further extend the flow path of the reaction raw materials, and the baffle 301 at the bottom is perpendicular to the inner wall of the pre-reaction pipe 3, which can effectively break the vortex and eddy current and improve the mitigation effect. In order to improve the heat dissipation effect of the oxidation tower 1, an inner coil 5 is arranged on the inner wall of the oxidation tower 1. The length of the inner coil 5 is adapted to the length of the spiral pipe. The cooling water inlet 501 of the inner coil 5 is arranged above the cooling water outlet 502. The inner coil 5 can assist in adjusting and controlling the reaction temperature. In the embodiment of the present invention, a third enhanced reactor 4 is also provided at the bottom of the oxidation tower 1, and the outlet of the third enhanced reactor 4 is opposite to the outlet of the pre-reaction pipe 3. The advantage of such a setting is that the mixed solution generated by the initial reaction in the pre-reaction pipe 3 can offset the oxygen coming out of the third enhanced reactor 4, thereby stirring the gas-liquid mixture in the oxidation tower 1. Continuing to refer to FIG. 1 , a reflux pipeline 12 is provided on the outside of the oxidation tower 1, the inlet of the reflux pipeline 12 is connected to the side wall of the oxidation tower 1, and the outlet of the reflux pipeline 12 is connected to the bottom of the oxidation tower 1; the reflux pipeline 12 is connected to a circulating cooler 121, and the circulating cooler 121 is respectively connected to the inlet of the reflux pipeline 12 and the outlet of the crude product. The condensation unit of the present invention is connected to the oxidation unit. Specifically, the reaction kettle 13 of the condensation unit is connected to the crude product outlet of the oxidation unit for condensing the phenol-acetone mixed solution. Specifically, the reactor 13 is provided with a second built-in strengthening unit 14, which is arranged at the top of the reactor 13. The second strengthening unit 14 includes a sixth strengthening reactor 141 and a seventh strengthening reactor 142. The two strengthening reactors are respectively arranged on opposite side walls in the reactor 13 and have opposite outlets. Such an arrangement can form a collision flow between the two enhanced reactors to improve the dispersion effect. Specifically, the sixth enhanced reactor 141 is connected to the crude product outlet, and the seventh enhanced reactor 142 is connected to the oxygen tank 19. In this embodiment, a stirring paddle 15 is provided at the bottom of the reactor 13, and a stirring blade 151 is connected to the stirring paddle 15, and the stirring blade 151 is provided below the second built-in strengthening unit 14. The stirring paddle 15 provided in the reactor 13 cooperates with the second built-in strengthening unit 14 to stir the microbubbles coming out of the sixth strengthening reactor 141 and the seventh strengthening reactor 142, thereby improving the uniformity of their dispersion in the liquid in the reactor 13 and further improving the reaction effect. The preparation method of the preparation system of this embodiment is as follows: isopropylbenzene and oxygen are broken into microbubbles at the micron level through enhanced dispersion and then mixed in the oxidation tower 1 to generate a crude solution of phenol and acetone. The crude solution of phenol and acetone enters the reactor 13, and oxygen reacts with the crude product through the seventh enhanced reactor 142 to obtain a phenol-acetone solution. Example 2 The only difference between this example and Example 1 is that the inclination angle of the baffles in the pre-reaction pipe is 80°. Example 3 The only difference between this example and Example 1 is that the inclination angle of the pre-reaction pipe is 45°. Example 4 The only difference between this example and Example 1 is that the third enhanced reactor is not provided. Comparative Example 1 The only difference between this example and Example 1 is that no baffle is provided in the pre-reaction pipe. Comparative Example 2 The only difference between this example and Example 1 is that no pre-reaction pipeline is provided. Comparative Example 3 The only difference between this example and Example 1 is that the first built-in strengthening unit is not provided. Comparative Example 4 This example adopts the existing technology, directly passing the isopropylbenzene liquid into the bottom of the oxidation tower, and passing the fresh air sent by the compressor after alkali washing into the bottom of the oxidation tower, reacting in the oxidation tower to generate reaction products, and the reaction products enter the company's separation tank for separation and then enter the subsequent concentration section. Experimental Example 1 Phenol acetone was prepared by using the preparation systems of Examples 1-4 and Comparative Examples 1-3, respectively. The specific experimental conditions were as follows: the mass flow rate of cumene was 3003.2 kg / h, the volume flow rate of cumene was 3.7 m 3 / h, the mass flow rate of oxygen is 573.0kg / h, and the volume flow rate of oxygen is 96.1m 3 / h. The reaction results are shown in the following table: Table 1 Experimental results When preparing phenol acetone in the prior art, the selectivity of CHP is usually about 60.56%, the tail oxygen content is 5.1%, the oxygen utilization rate is 69%, and the yield of phenol acetone is 62%. As can be seen from Table 1, compared with the existing oxidation tower, the phenol acetone output of each embodiment of the present invention is significantly increased, and the phenol acetone yield of Example 1 is increased by 36%. The tail gas oxygen content of the reaction system of each embodiment of the present invention is lower than 5%, which is 0.8-4% lower than the prior art, and the reaction time and reaction temperature of each embodiment of the present invention are lower than those of the prior art. As can be seen from Table 1, Example 1 of the present invention is the best example. The reaction temperature of the preparation system of this embodiment is significantly lower than the reaction temperature of preparing phenol acetone in the prior art, and the reaction time is significantly shortened. It still has good raw material conversion rate and product yield, and CHP selectivity is significantly improved. It shows that the baffle arrangement mode and the enhanced reactor setting mode of Example 1 can achieve the best reaction effect. It can be seen that the preparation system of this embodiment has low reaction energy consumption and good preparation effect. Among them, the phenol acetone yield of Comparative Example 3 is lower than that of Example 1. This is because Comparative Example 3 does not have the first built-in enhanced unit, which cannot fully crush and disperse isopropylbenzene and oxygen in the oxidation tower, and cannot offset the third enhanced reactor. It can be seen that this embodiment improves the yield of phenol acetone by arranging the enhanced reactor of the oxidation tower. In summary, compared with the prior art, the phenol acetone preparation system of the present invention has an easy-to-achieve reaction temperature, a short reaction time, a high raw material conversion rate, and a high product yield, and is worthy of wide promotion and application. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A system for preparing phenol acetone, characterized in that: include: An oxidation unit, the oxidation unit comprising an oxidation tower, a first built-in strengthening unit is arranged inside the oxidation tower, and the first built-in strengthening unit is arranged at the top of the oxidation tower; The first built-in enhancement unit includes a first enhancement reactor and a second enhancement reactor, the first enhancement reactor is arranged above the second enhancement reactor, a connecting pipe is arranged between the first enhancement reactor and the second enhancement reactor, and the first enhancement reactor is arranged above the liquid surface; A pre-reaction pipeline is provided in the middle of the oxidation tower, and the pre-reaction pipeline is connected to the outlet of the second enhanced reactor; The condensation unit comprises a reaction kettle, a second built-in strengthening unit is arranged inside the reaction kettle, and the second built-in strengthening unit is arranged at the top of the reaction kettle.

2. The system for preparing phenol acetone according to claim 1, characterized in that: The pre-reaction pipe is provided with multiple layers of baffles from top to bottom in sequence, and the multiple layers of baffles are arranged in a staggered manner; Preferably, the baffle is arranged to be inclined downward in a direction away from the inner wall of the pre-reaction pipe, and the inclination angle between the baffle and the side wall of the pre-reaction pipe is 70-90°.

3. The system for preparing phenol acetone according to claim 1, characterized in that: A third enhanced reactor is arranged at the bottom end of the oxidation tower, and the outlet of the third enhanced reactor is opposite to the outlet of the pre-reaction pipeline.

4. The system for preparing phenol acetone according to claim 1, characterized in that: The inner wall of the oxidation tower is provided with an inner coil, and the length of the inner coil is adapted to the length of the spiral pipeline.

5. The system for preparing phenol acetone according to claim 1, characterized in that: An external strengthening unit is arranged outside the oxidation tower, and the external strengthening unit is connected to the first internal strengthening unit. The external strengthening unit includes a fourth strengthening reactor and a fifth strengthening reactor, and a connecting pipe is arranged between the fourth strengthening reactor and the fifth strengthening reactor.

6. The system for preparing phenol acetone according to claim 5, characterized in that: The fourth enhanced reactor is connected to the cumene inlet, and the fifth enhanced reactor is connected to the oxygen inlet; Preferably, an air filter is provided between the oxygen inlet and the fifth enhanced reactor; Preferably, the cumene inlet and the oxygen inlet are respectively connected with a regulating valve and a flow meter.

7. The system for preparing phenol acetone according to claim 1, characterized in that: A reflux pipeline is arranged outside the oxidation tower, the inlet of the reflux pipeline is connected to the side wall of the oxidation tower, and the outlet of the reflux pipeline is connected to the bottom of the oxidation tower; Preferably, the reflux pipeline is connected to a circulating cooler, and the circulating cooler is respectively connected to the reflux pipeline inlet and the crude product outlet.

8. The system for preparing phenol acetone according to claim 1, characterized in that: A stirring paddle is disposed at the bottom end of the reactor, and a stirring blade is connected to the stirring paddle, and the stirring blade is disposed below the second built-in strengthening unit.

9. The system for preparing phenol acetone according to claim 1, characterized in that: The top of the reactor is provided with an exhaust gas outlet, and the exhaust gas outlet is connected to the first enhanced reactor and the exhaust gas washing tower through gas pipelines respectively.

10. A method for preparing phenol acetone, characterized in that: Phenol acetone is prepared using the preparation system described in any one of claims 1 to 9.

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