System and method for preparing 1, 3-propylene glycol

Abstract

The invention provides a system and a method for preparing 1, 3-propylene glycol. The system comprises a first feeding pipeline, a second feeding pipeline, a third feeding pipeline, a fourth feeding pipeline, a hydration reactor, a turntable extraction tower and a hydrogenation reactor, the first feeding pipeline is connected with the hydration reactor; a first enhanced mass transfer unit is arranged in the hydration reactor, and the second feeding pipeline is connected with the first enhanced mass transfer unit; an outlet of the hydration reactor is connected with the turntable extraction tower; a water phase outlet of the turntable extraction tower is connected with the bottom of the hydrogenation reactor through a conveying pipeline; a second enhanced mass transfer unit is arranged in the hydrogenation reactor, and the third feeding pipeline is connected with the second enhanced mass transfer unit; the fourth feeding pipeline is connected with the conveying pipeline; the hydrogenation reactor is a slurry bed reactor; a material outlet of the hydrogenation reactor is higher than the second enhanced mass transfer unit in the vertical direction, and the material outlet is lower than the liquid level in the hydrogenation reactor in the vertical direction. The system can be used for adding a catalyst required by hydrogenation reaction in real time.

Description

Technical Field

[0001] The present invention relates to the technical field of 1,3 - propanediol preparation, and more particularly, to a system and a method for preparing 1,3 - propanediol. Background Art

[0002] 1,3 - Propanediol is an important chemical raw material and a key raw material for synthesizing polytrimethylene terephthalate (PTT). PTT is a high - performance polyester fiber widely used in the textile and clothing industries. It is commonly used as a raw material for polyester polyols, an initiator for polyether polyols, and a chain extender for polyurethanes, for producing high - performance polyurethane materials. At the same time, 1,3 - propanediol can be used as a humectant, solvent, and emulsifier in the food industry, which can extend the shelf life of food and maintain the taste and moisture. It can be used as an organic solvent in industries such as lubricants and antifreeze agents.

[0003] In related technologies, most of the 1,3 - propanediol preparation processes are prepared by the hydration and hydrogenation of acrolein. Currently, fixed - bed reactors are mostly used in the hydrogenation reaction process. During the production process, it is necessary to stop the production regularly to replace the catalyst, which consumes a large amount of energy and brings economic losses and safety risks.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The first object of the present invention is to provide a system for preparing 1,3 - propanediol. This system uses a slurry bed for the hydrogenation reaction and can add the catalyst required for the hydrogenation reaction in real - time through the fourth feed pipeline during the production process. Thus, the problem of the fixed - bed reactor needing to stop production to replace the catalyst is solved. Moreover, by setting a first mass - transfer intensifying unit in the hydration reactor and a second mass - transfer intensifying unit in the hydrogenation reactor, the interfacial mass - transfer area between raw materials in the acrolein hydration reaction and the hydrogenation reaction can be increased, the conversion rate of raw materials can be improved, and the energy consumption required for the reaction can be reduced, which helps to increase production benefits.

[0006] The second object of the present invention is to provide a method for preparing 1,3 - propanediol. By using the above - mentioned system, the high - efficient production of 1,3 - propanediol can be achieved.

[0007] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted: The present invention provides a system for preparing 1,3 - propanediol, including: a first feed pipeline, a second feed pipeline, a third feed pipeline, a fourth feed pipeline, a hydration reactor, a rotary disk extraction column, and a hydrogenation reactor; The first feed pipeline is used to transport a mixed solution of acrolein, a homogeneous catalyst, and a polymerization inhibitor, and the first feed pipeline is connected to the hydration reactor; The second feed pipeline is used to transport deionized water. A first mass transfer intensifying unit is arranged in the hydration reactor, and the second feed pipeline is connected to the first mass transfer intensifying unit; The outlet of the hydration reactor is connected to the rotary disk extraction column, and the aqueous phase outlet of the rotary disk extraction column is connected to the bottom of the hydrogenation reactor through a transport pipeline; The third feed pipeline is used to transport hydrogen. A second mass transfer intensifying unit is arranged in the hydrogenation reactor, and the third feed pipeline is connected to the second mass transfer intensifying unit; The fourth feed pipeline is used to transport the hydrogenation reaction catalyst, and the fourth feed pipeline is connected to the transport pipeline; The hydrogenation reactor is a slurry bed reactor; the material outlet of the hydrogenation reactor is higher than the second mass transfer intensifying unit in the vertical direction and lower than the liquid level in the hydrogenation reactor in the vertical direction; A baffle is arranged in the hydrogenation reactor near the material outlet. The top of the baffle is higher than the material outlet in the vertical direction and lower than the liquid level of the hydrogenation reactor; the bottom of the baffle extends obliquely downward along the direction close to the side wall of the hydrogenation reactor to form an extension part, and there is a gap between the bottom of the extension part and the side wall of the hydrogenation reactor.

[0008] In the above solution, acrolein, a homogeneous catalyst, and an inhibitor are mixed in the first feed pipeline. Among them, the homogeneous catalyst is used to catalyze the occurrence of the hydration reaction, and the inhibitor is used to prevent the dimerization reaction of acrolein and improve the product selectivity. By premixing the homogeneous catalyst and the inhibitor into acrolein before the reaction, this solution helps the homogeneous catalyst and the inhibitor to be evenly distributed in the hydration reactor, thus helping to better play the catalytic role and the inhibition role, improving the conversion rate of the reaction raw materials, and at the same time reducing the occurrence of side reactions; by setting a first mass transfer intensifying unit in the hydration reactor, deionized water can be dispersed into micron-sized micro-droplets, thereby increasing the phase boundary mass transfer area between the deionized water and acrolein. This helps to improve the efficiency of the hydration reaction and the conversion rate of raw materials, and can reduce the requirements for temperature and pressure in the hydration reaction to a certain extent, thus helping to reduce the reaction energy consumption; the hydrogenation reactor of this solution uses a slurry bed reactor, and a hydrogenation reaction catalyst is added to the hydrogenation reactor through the fourth feed pipeline, and the hydrogenation reaction catalyst can be replaced in real time during the production process. Thus, the problem that the fixed bed needs to stop for catalyst replacement is solved; by setting a second mass transfer intensifying unit in the hydrogenation reactor, hydrogen can be dispersed and broken into micron-sized micro-bubbles, thereby increasing the phase boundary mass transfer area between hydrogen and 3-hydroxypropionaldehyde. This helps to improve the reaction efficiency of the hydrogenation reaction, the conversion rate of 3-hydroxypropionaldehyde, and the selectivity of 1,3-propanediol, and can reduce the requirements for temperature and pressure in the hydrogenation reaction to a certain extent, thus helping to reduce the reaction energy consumption; by setting a baffle near the material outlet in the hydrogenation reactor, an internal settling tank can be formed between the baffle and the side wall of the hydrogenation reactor. The reaction liquid in the hydrogenation reactor flows into the internal settling tank for sedimentation. The supernatant is output through the material outlet, and the lower turbid liquid flows back into the hydrogenation reactor through the gap between the bottom of the extension part and the side wall of the hydrogenation reactor to continue to participate in the reaction. Thus, the purity of the product output from the material outlet and the utilization rate of the catalyst can be improved, which helps to save costs.

[0009] Preferably, the first mass transfer intensifying unit includes a first mass transfer intensifier and a second mass transfer intensifier, and the second feed pipeline is respectively connected to the first mass transfer intensifier and the second mass transfer intensifier; Both the upper and lower ends of the first mass transfer intensifier and the second mass transfer intensifier are provided with outlets. The number of upper-end outlets of the first mass transfer intensifier is less than the number of lower-end outlets, and the number of upper-end outlets of the second mass transfer intensifier is greater than the number of lower-end outlets; The first mass transfer intensifier is arranged above the second mass transfer intensifier in the vertical direction, and the first mass transfer intensifier and the second mass transfer intensifier are arranged staggered in the vertical direction.

[0010] In the above solution, both of the mass transfer intensifiers adopt a flared structure with more outlets at one end and fewer outlets at the other end, which can make the distribution of the output micro-droplets more reasonable. And by arranging the first mass transfer intensifier and the second mass transfer intensifier staggered in the vertical direction, the lower outlet of the first mass transfer intensifier and the upper outlet of the second mass transfer intensifier can be staggered with each other. This arrangement can avoid the collision of two micro-droplet flows and cause liquid dead zones, and can use the micro-droplets ejected by the two mass transfer intensifiers to stir the reaction liquid in the hydration reactor. On the one hand, this can make the micro-droplets evenly distributed, further increase the mass transfer area and the contact area between reaction raw materials, and improve the reaction efficiency. On the other hand, by stirring the reaction liquid, it can ensure the uniform distribution of the homogeneous catalyst and inhibitor in the reaction liquid, and ensure the catalytic effect of the homogeneous catalyst and the inhibition effect of the inhibitor, which helps to further improve the reaction efficiency of the hydration reaction.

[0011] Preferably, the first feed pipeline has a first outlet and a second outlet. The first outlet is located above the second outlet in the vertical direction, and both the first outlet and the second outlet are located between the first mass transfer intensifier and the second mass transfer intensifier in the vertical direction; The first outlet is connected to the side wall of the hydration reactor that is farther away from the first mass transfer intensifier, and the second outlet is connected to the side wall of the hydration reactor that is farther away from the second mass transfer intensifier.

[0012] In the above solution, both outlets of the first feed pipeline are located between the two mass transfer intensifiers. It can be understood that there are more micro-droplets between the two mass transfer intensifiers. This way of directly supplementing acrolein between the two mass transfer intensifiers can ensure the stable progress of the reaction; in addition, by connecting the first outlet to the side wall of the hydration reactor that is farther away from the first mass transfer intensifier and the second outlet to the side wall of the hydration reactor that is farther away from the second mass transfer intensifier, the power of the materials output from the two outlets and the power of the micro-droplets output by the two mass transfer intensifiers can be used to stir the reaction liquid between the two mass transfer intensifiers, which can make the micro-droplets, homogeneous catalyst, and inhibitor evenly distributed, thus helping to improve the hydration reaction efficiency.

[0013] Preferably, the second mass transfer intensifier group includes a third mass transfer intensifier and a fourth mass transfer intensifier, and the third feed pipeline is respectively connected to the third mass transfer intensifier and the fourth mass transfer intensifier; Both the upper and lower ends of the third mass transfer intensifier and the fourth mass transfer intensifier are provided with outlets. The number of upper outlets of the third mass transfer intensifier is less than the number of lower outlets, and the number of upper outlets of the fourth mass transfer intensifier is greater than the number of lower outlets; The third mass transfer intensifier is arranged above the fourth mass transfer intensifier in the vertical direction, and the third mass transfer intensifier and the fourth mass transfer intensifier are arranged staggeredly in the vertical direction.

[0014] In the above solution, both mass transfer intensifiers adopt a flared structure with more outlets at one end and fewer outlets at the other end, which can make the output microbubbles more reasonably distributed in the hydrogenation reactor. And by arranging the third mass transfer intensifier and the fourth mass transfer intensifier staggeredly in the vertical direction, the lower outlet of the third mass transfer intensifier and the upper outlet of the fourth mass transfer intensifier can be staggered with each other. This arrangement can avoid the collision of two microbubble flows causing a liquid dead zone, and can use the microbubbles ejected by the two mass transfer intensifiers to stir the reaction liquid in the hydrogenation reactor. On the one hand, this can make the microbubbles evenly distributed, further increase the mass transfer area and the contact area between reaction raw materials, and improve the reaction efficiency. On the other hand, it can ensure the uniform distribution of the hydrogenation reaction catalyst in the reaction liquid by stirring the reaction liquid, ensuring the catalytic effect of the catalyst, which helps to further improve the reaction efficiency of the hydrogenation reaction.

[0015] Preferably, the system further includes a first circulation pipeline. The inlet of the first circulation pipeline is connected to the bottom of the hydrogenation reactor, and the outlet is connected to the side wall of the hydrogenation reactor on the side farther from the fourth mass transfer intensifier; the outlet of the first circulation pipeline is located between the third mass transfer intensifier and the fourth mass transfer intensifier.

[0016] In the above solution, the first circulation pipeline can circulate the reaction liquid at the bottom of the hydrogenation reactor between the two mass transfer intensifiers. This way can play a role in stirring the bottom of the hydrogenation reactor and avoid the deposition of the catalyst at the bottom.

[0017] Preferably, the system further includes a second circulation pipeline; the inlet of the second circulation pipeline is connected to the side wall of the hydrogenation reactor near the baffle and the inlet of the second circulation pipeline is lower than the bottom of the extension part in the vertical direction; the outlet of the second circulation pipeline is connected to the side wall of the hydrogenation reactor on the side farther from the third mass transfer intensifier; the outlet of the second circulation pipeline is located between the third mass transfer intensifier and the fourth mass transfer intensifier.

[0018] In the above solution, the second circulation pipeline can directly input the lower turbid liquid containing a higher concentration of catalyst settled by the built-in sedimentation tank between the two mass transfer intensifiers, and realize uniform dispersion by the stirring of the microbubble flow of the two mass transfer intensifiers, which helps to further improve the utilization rate and catalytic effect of the catalyst.

[0019] Preferably, the outlet of the first circulation pipeline is vertically below the outlet of the second circulation pipeline. This arrangement enables the two liquid flows output by the two circulation pipelines to synergistically stir the reaction liquid with the microbubble flows output by the two mass transfer intensifiers respectively, improving the stirring effect on the reaction liquid, and thus enhancing the distribution uniformity of the microbubbles and the catalyst in the reaction liquid.

[0020] Preferably, a plurality of partitions are provided in the hydrogenation reactor. The plurality of partitions are arranged staggeredly, and the plurality of partitions are all located vertically between the baffle and the second mass transfer intensifier unit. Preferably, the partitions are inclined downward along the direction away from the side wall of the hydrogenation reactor. This solution can reduce the flow velocity of the upper reaction liquid by staggeredly arranging a plurality of partitions, promote the sedimentation of the catalyst in the reaction liquid, and thus reduce the purity of the product output at the material outlet. In a further solution, by arranging the partitions inclined downward, the sedimented catalyst can flow back into the lower reaction liquid along the partitions, avoiding the accumulation of the sedimented catalyst.

[0021] Preferably, the system further includes a sedimentation tank and a filter; the material outlet is connected to the sedimentation tank, and the sedimentation tank is connected to the filter; an arc-shaped filter cloth is provided in the filter; the arc-shaped filter cloth divides the internal chamber of the filter into a filtration chamber and a filtrate chamber, the filtrate chamber is connected to the product pipeline, and the side wall of the filtration chamber is connected to the hydrogenation reactor; preferably, the number of filters is two, and the two filters are arranged in parallel; preferably, a guiding plate is provided at the inlet of the filter, and the guiding plate extends obliquely downward along the direction close to the arc-shaped filter cloth. In this solution, the filter cloth of the filter adopts a 1 / 4 circular arc design, which is more conducive to the recovery of the catalyst and can effectively prevent the catalyst from blocking on the filter cloth; in a further solution, the number of filters is set to two, and the two filters can adopt an open-and-closed application mode to avoid stopping production due to cleaning the filter, which helps to increase production efficiency; in a further solution, a guiding plate is provided in the filter, and the guiding plate can play a guiding and buffering role, avoiding the direct impact of the crude product entering the filter on the arc-shaped filter cloth and ensuring the filtering effect of the arc-shaped filter cloth.

[0022] Preferably, the oil phase outlet of the rotary disk extraction column is connected to the distillation column; the bottom outlet and the top outlet of the distillation column are both connected to the first feed pipeline, and the middle section outlet of the distillation column is connected to the rotary disk extraction column. In this solution, the aqueous phase containing 3-hydroxypropionaldehyde separated by the rotary disk extraction column flows into the hydrogenation reactor from the bottom for hydrogenation reaction, and the oil phase containing the homogeneous catalyst and unreacted acrolein flows into the distillation column from the top for distillation separation. The acrolein produced at the top of the distillation column flows into the hydration reactor for recycling, the extractant produced in the middle section flows into the extraction column for recycling, and the homogeneous catalyst produced at the bottom flows into the hydration reactor for recycling. The recycling of materials can significantly improve the product yield, and the recycled raw materials have no adverse effects on the reaction process.

[0023] Those skilled in the art can understand that the mass transfer intensifier adopted in the present invention has been embodied in the prior patents of the present inventor, such as the patents with application numbers CN201610641119.6, CN201610641251.7, CN201710766435.0, CN106187660A, CN105903425A, CN205833127U and CN207581700U. The specific product structure and working principle of the microbubble generator (i.e., bubble crusher) were introduced in detail in the prior patent CN201610641119.6. It is recorded in this application document that "the microbubble generator includes a main body and a secondary crushing member. There is a cavity inside the main body, and an inlet communicating with the cavity is provided on the main body. The opposite first end and second end of the cavity are both open. Among them, the cross-sectional area of the cavity decreases from the middle of the cavity to the first end and the second end of the cavity; the secondary crushing member is provided at at least one of the first end and the second end of the cavity. A part of the secondary crushing member is arranged inside the cavity, and an annular channel is formed between the secondary crushing member and the through holes that are open at both ends of the cavity. The microbubble generator also includes an air inlet pipe and a liquid inlet pipe." From the specific structure disclosed in this application document, its specific working principle can be known as follows: The liquid tangentially enters the microbubble generator through the liquid inlet pipe, rotates at a super high speed and cuts the gas, so that the gas bubbles are broken into microbubbles at the micron level, thereby increasing the mass transfer area between the liquid phase and the gas phase. Moreover, the microbubble generator in this patent belongs to a pneumatic bubble crusher.

[0024] 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 actually belongs to a hydraulic enhanced reactor, 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 actually belongs to a gas-liquid linkage bubble breaker. In fact, whether it is a hydraulic bubble breaker or a gas-liquid linkage bubble breaker, it is a specific form of bubble breaker. However, the enhanced mass transfer device 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 can be adopted by the present invention.

[0025] In addition, the prior patent 201710766435.0 records that "the principle of the bubble breaker is a high-speed jet to achieve mutual collision of gases"; and the prior patent CN106187660 also has relevant records on the specific structure of the bubble breaker, see paragraphs

[0031] -

[0041] in the specification, and the drawings, which explain in detail the specific working principle of the bubble breaker S-2. The top of the bubble breaker is a liquid phase inlet, and the side is a gas phase inlet. The liquid phase coming in from the top provides suction power, thereby achieving the effect of crushing into ultrafine bubbles. It can also be seen in the drawings that the bubble breaker has a conical structure, and the diameter of the upper part is larger than the diameter of the lower part, so that the liquid phase can better provide suction power.

[0026] Since the bubble breaker was just developed in the early stage of the prior patent application, it was named micron bubble generator (CN201610641119.6) in the early stage. With the continuous technical improvement, it was later renamed as bubble breaker. Now the enhanced mass transfer device in the present invention is equivalent to the previous micron bubble generator, micro interface generator, etc., but the name is different. In summary, the enhanced mass transfer device of the present invention itself belongs to the prior art.

[0027] The present invention also provides a method for preparing 1,3-propylene glycol, which uses the system of any of the above embodiments to prepare 1,3-propylene glycol.

[0028] Compared with the prior art, the present invention has the following beneficial effects: 1. Acrolein, a homogeneous catalyst, and an inhibitor of polymerization are mixed in the first feed pipeline. Among them, the homogeneous catalyst is used to catalyze the occurrence of the hydration reaction, and the inhibitor of polymerization is used to prevent the dimerization reaction of acrolein and improve the product selectivity. By premixing the homogeneous catalyst and the inhibitor of polymerization into acrolein before the reaction, this solution helps the homogeneous catalyst and the inhibitor of polymerization to be evenly distributed in the hydration reactor, thereby contributing to better exerting the catalytic effect and the inhibition effect of polymerization, improving the conversion rate of the reaction raw materials, and reducing the occurrence of side reactions at the same time; 2. By arranging a first mass transfer intensifying unit in the hydration reactor, deionized water can be dispersed into micron-sized micro-droplets, thereby increasing the phase boundary mass transfer area between deionized water and acrolein. This helps to improve the efficiency of the hydration reaction and the conversion rate of raw materials, and can reduce the requirements for temperature and pressure in the hydration reaction to a certain extent, thus contributing to reducing the reaction energy consumption; 3. The hydrogenation reactor of this solution adopts a slurry bed reactor, and a hydrogenation reaction catalyst is added to the hydrogenation reactor through a fourth feed pipeline, enabling the real-time replacement of the hydrogenation reaction catalyst during the production process. Thus, the problem of the need to stop the fixed bed to replace the catalyst is solved; 4. By arranging a second mass transfer intensifying unit in the hydrogenation reactor, hydrogen can be dispersed and broken into micron-sized micro-bubbles, thereby increasing the phase boundary mass transfer area between hydrogen and 3-hydroxypropionaldehyde. This helps to improve the reaction efficiency of the hydrogenation reaction, the conversion rate of 3-hydroxypropionaldehyde, and the selectivity of 1,3-propanediol, and can reduce the requirements for temperature and pressure in the hydrogenation reaction to a certain extent, thus contributing to reducing the reaction energy consumption; 5. By arranging a baffle near the material outlet in the hydrogenation reactor, an internal settling tank can be formed between the baffle and the side wall of the hydrogenation reactor. The reaction liquid in the hydrogenation reactor flows into this internal settling tank for sedimentation. The supernatant is output through the material outlet, and the lower turbid liquid flows back into the hydrogenation reactor through the gap between the bottom of the extension part and the side wall of the hydrogenation reactor to continue participating in the reaction. Thus, the purity of the product output from the material outlet and the utilization rate of the catalyst can be improved, which helps to save costs. Description of the Drawings

[0029] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: Figure 1 Shows a schematic structural diagram of the system for preparing 1,3-propanediol according to Embodiment 1 of the present invention; Figure 2 Shows a schematic diagram of the liquid flow direction between the first mass transfer intensifier and the second mass transfer intensifier in the hydration reactor according to Embodiment 1 of the present invention; Figure 3 Schematic structural diagram of the hydrogenation reactor according to Embodiment 1 of the present invention; Figure 4 Schematic diagram of the liquid flow direction between the third mass transfer intensifier and the fourth mass transfer intensifier in the hydrogenation reactor according to Embodiment 1 of the present invention; Figure 5 Schematic structural diagram of the filter according to Embodiment 1 of the present invention.

[0030] In the figure: 1, hydration reactor; 2, first mass transfer intensifier; 3, first feed pipeline; 4, second feed pipeline; 5, second mass transfer intensifier; 6, rotary disk extraction column; 7, rectification column; 8, hydrogenation reactor; 9, fourth feed pipeline; 10, sedimentation tank; 11, filter; 12, third feed pipeline; 13, first circulation pipeline; 14, second circulation pipeline; 15, partition board; 16, extension part; 17, baffle; 18, fourth mass transfer intensifier; 19, third mass transfer intensifier; 20, arc-shaped filter cloth; 21, guiding plate; 22, conveying pipeline. Detailed implementation manners

[0031] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific implementation manners. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are 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 those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. For those conditions not specified in the embodiments, they shall be carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is 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 should not be construed as limiting the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "installation", "connection", and "coupling" 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 directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0034] In order to more clearly illustrate the technical solutions in the present invention, the following will be described in the form of specific embodiments.

[0035] Embodiment 1 With reference to Figures 1-5 , this embodiment provides a system for preparing 1,3 - propanediol. The system includes: a first feed pipeline 3, a second feed pipeline 4, a third feed pipeline 12, a fourth feed pipeline 9, a hydration reactor 1, a rotary disk extraction column 6, and a hydrogenation reactor 8; the first feed pipeline 3 is used to transport a mixed solution of acrolein, a homogeneous catalyst, and a polymerization inhibitor, and the first feed pipeline 3 is connected to the hydration reactor 1; the second feed pipeline 4 is used to transport deionized water, and a first mass transfer intensifying unit is arranged in the hydration reactor 1, and the second feed pipeline 4 is connected to the first mass transfer intensifying unit; the outlet of the hydration reactor 1 is connected to the rotary disk extraction column 6, and the aqueous phase outlet of the rotary disk extraction column 6 is connected to the bottom of the hydrogenation reactor 8 through a transport pipeline 22; the third feed pipeline 12 is used to transport hydrogen, and a second mass transfer intensifying unit is arranged in the hydrogenation reactor 8, and the third feed pipeline 12 is connected to the second mass transfer intensifying unit; the fourth feed pipeline 9 is used to transport a hydrogenation reaction catalyst, and the fourth feed pipeline 9 is connected to the transport pipeline 22; the hydrogenation reactor 8 is a slurry bed reactor; the material outlet of the hydrogenation reactor 8 is higher than the second mass transfer intensifying unit in the vertical direction and lower than the liquid level in the hydrogenation reactor 8 in the vertical direction; a baffle 17 is arranged near the material outlet in the hydrogenation reactor 8, the top of the baffle 17 is higher than the material outlet in the vertical direction and lower than the liquid level of the hydrogenation reactor 8; the bottom of the baffle 17 extends obliquely downward along the direction close to the side wall of the hydrogenation reactor 8 to form an extension part 16, and there is a gap between the bottom of the extension part 16 and the side wall of the hydrogenation reactor 8.

[0036] The homogeneous catalyst, inhibitor, and hydrogenation reaction catalyst can be selected as needed. In this embodiment, the homogeneous catalyst can be N-alkyl amino acid, and the addition amount of the homogeneous catalyst can be 5-15% of the mass of the hydration reaction liquid. The pressure of the hydration reaction can be 0-0.5 MPa (gauge pressure), the temperature can be 30-60 °C, and the time can be 2-4 h. The addition amount of acrolein in the hydration reaction is 5-25% of the mass of the hydration reaction liquid. The pressure of the hydrogenation reaction can be 2-5 MPa (gauge pressure), the temperature can be 40-100 °C, and the space velocity can be 1-5 h -1 .

[0037] The inhibitor can be hydroquinone, and the addition amount of hydroquinone can be 0-0.1% of the mass of the hydration reaction liquid. In the hydration reaction, acrolein is prone to dimerization reaction, reducing the selectivity. At the same time, there is a certain interaction relationship between the dimer and the product, which is difficult to separate and affects the quality of the product. Adding a trace amount of inhibitor can avoid the dimerization of acrolein. During the subsequent extraction operation, a small part of the inhibitor enters the oil phase and enters the bottom N-alkyl amino acid logistics during the separation of the oil phase, and is recycled to the hydration reactor 1 together with this logistics. The remaining inhibitor enters the hydrogenation reactor 8 with the aqueous phase, but the presence of the inhibitor has no adverse effect on the hydrogenation reaction.

[0038] The hydrogenation reaction catalyst can adopt a powdered supported noble metal catalyst. The noble metal is selected from nickel, palladium, rhodium, or platinum, the carrier is alumina, titanium oxide, or silica, and the noble metal content in the supported noble metal catalyst is 5-30 wt%.

[0039] In this embodiment, acrolein, the homogeneous catalyst, and the inhibitor can be premixed and then input into the hydration reactor 1 via the first feed pipeline 3. It can be understood that in order to ensure the flow of materials in each pipeline, a water pump can be set on the pipeline, which will not be elaborated.

[0040] In this embodiment, an internal settling tank can be formed between the baffle 17 and the side wall of the hydration reactor 1. The volume of this tank can be 1 / 20-1 / 10 of the volume of the hydrogenation reactor 8, the height can be 1 / 5-3 / 5 of the height of the hydrogenation reactor 8, and the width can be 1 / 10-1 / 5 of the hydrogenation reactor 8. Among them, the height of the lower turbid liquid is 1 / 10-1 / 5 of the height of the tank. The internal settling tank can make part of the powdered catalyst settle in the tank, reducing the subsequent catalyst recovery amount and saving costs.

[0041] In this embodiment, the number of theoretical plates of the rotary extraction tower 6 is 3-6, the extraction method adopts countercurrent extraction, the extractant is selected from at least one of methyl tert-butyl ether, diethyl ether, and benzene, the oil-water mass ratio is 1.5-5:1, and the extraction temperature is 25-40 °C.

[0042] In this embodiment, as Figure 1As shown, the oil phase outlet of the rotating disk extraction column 6 is connected to the distillation column 7; the bottom outlet and the top outlet of the distillation column 7 are both connected to the first feed pipeline 3, and the middle section outlet of the distillation column 7 is connected to the rotating disk extraction column 6. The water phase containing 3-hydroxypropionaldehyde separated by the rotating disk extraction column 6 flows into the hydrogenation reactor 8 for hydrogenation reaction, and the oil phase containing N-alkyl amino acid and unreacted acrolein flows into the distillation column 7 for distillation separation. The acrolein produced at the top of the distillation column 7 flows into the hydration reactor 1 for recycling, the extraction agent produced in the middle section flows into the extraction column for recycling, and the N-alkyl amino acid produced at the bottom of the column flows into the hydration reactor 1 for recycling. The recycling of materials can significantly improve the product yield, and the recycled raw materials have no adverse effects on the reaction process.

[0043] Continue to refer to Figure 1 , in this embodiment, the first mass transfer intensifier unit includes a first mass transfer intensifier 2 and a second mass transfer intensifier 5, and the second feed pipeline 4 is respectively connected to the first mass transfer intensifier 2 and the second mass transfer intensifier 5; both the upper and lower ends of the first mass transfer intensifier 2 and the second mass transfer intensifier 5 are provided with outlets, the number of upper end outlets of the first mass transfer intensifier 2 is less than the number of lower end outlets, and the number of upper end outlets of the second mass transfer intensifier 5 is greater than the number of lower end outlets; the first mass transfer intensifier 2 is arranged above the second mass transfer intensifier 5 in the vertical direction, and the first mass transfer intensifier 2 and the second mass transfer intensifier 5 are arranged staggeredly in the vertical direction. In this embodiment, the used mass transfer intensifiers (including the first mass transfer intensifier 2, the second mass transfer intensifier 5, the third mass transfer intensifier 19, and the fourth mass transfer intensifier 18) are all in the shape of a flared mouth, and the length ratio of its two ends is 5:2.

[0044] Continue to refer to Figure 1 , in this embodiment, the first feed pipeline 3 has a first outlet and a second outlet. The first outlet is above the second outlet in the vertical direction, and both the first outlet and the second outlet are located between the first mass transfer intensifier 2 and the second mass transfer intensifier 5 in the vertical direction; the first outlet is connected to the side wall of the hydration reactor 1 on the side farther from the first mass transfer intensifier 2, and the second outlet is connected to the side wall of the hydration reactor 1 on the side farther from the second mass transfer intensifier 5. In this case, as Figure 2 shown. The reaction liquid between the two mass transfer intensifiers can be stirred in the clockwise direction under the driving force of the materials output from the two outlets and the driving force of the micro-droplets output by the two mass transfer intensifiers, thereby improving the distribution uniformity of the catalyst and micro-droplets in the reaction liquid.

[0045] Continue to refer to Figure 1, the second enhanced mass transfer unit includes a third enhanced mass transfer device 19 and a fourth enhanced mass transfer device 18. The third feed pipeline 12 is respectively connected to the third enhanced mass transfer device 19 and the fourth enhanced mass transfer device 18. Both the upper and lower ends of the third enhanced mass transfer device 19 and the fourth enhanced mass transfer device 18 are provided with outlets. The number of upper-end outlets of the third enhanced mass transfer device 19 is less than the number of lower-end outlets, and the number of upper-end outlets of the fourth enhanced mass transfer device 18 is greater than the number of lower-end outlets. The third enhanced mass transfer device 19 is arranged vertically above the fourth enhanced mass transfer device 18, and the third enhanced mass transfer device 19 and the fourth enhanced mass transfer device 18 are staggered in the vertical direction.

[0046] Refer to in combination Figure 1 、 Figure 3 , the system further includes a first circulation pipeline 13. The inlet of the first circulation pipeline 13 is connected to the bottom of the hydrogenation reactor 8, and the outlet is connected to the side wall of the hydrogenation reactor 8 on the side farther from the fourth enhanced mass transfer device 18. The outlet of the first circulation pipeline 13 is located between the third enhanced mass transfer device 19 and the fourth enhanced mass transfer device 18. The reaction liquid at the bottom of the hydrogenation reactor 8 is pumped into the space between the third enhanced mass transfer device 19 and the fourth enhanced mass transfer device 18 through the first circulation pipeline 13.

[0047] Refer to in combination Figure 1 、 Figure 3 , the system further includes a second circulation pipeline 14. The inlet of the second circulation pipeline 14 is connected to the side wall of the hydrogenation reactor 8 near the baffle 17 and the inlet of the second circulation pipeline 14 is vertically lower than the bottom of the extension part 16. The outlet of the second circulation pipeline 14 is connected to the side wall of the hydrogenation reactor 8 on the side farther from the third enhanced mass transfer device 19. The outlet of the second circulation pipeline 14 is located between the third enhanced mass transfer device 19 and the fourth enhanced mass transfer device 18. The lower turbid liquid settled in the sedimentation tank is pumped into the space between the third enhanced mass transfer device 19 and the fourth enhanced mass transfer device 18 through the second circulation pipeline 14.

[0048] In this embodiment, the outlet of the first circulation pipeline 13 is vertically below the outlet of the second circulation pipeline 14. As Figure 4 shown, in this case, the two liquid flows output by the two circulation pipelines and the microbubble flows respectively output by the two enhanced mass transfer devices can stir the reaction liquid in the counterclockwise direction.

[0049] Refer to in combination Figure 1 、 Figure 3 , a plurality of partition plates 15 are arranged in the hydrogenation reactor 8. The plurality of partition plates 15 are staggered, and the plurality of partition plates 15 are all located vertically between the baffle 17 and the second enhanced mass transfer unit. The partition plates 15 are inclined downward in the direction away from the side wall of the hydrogenation reactor 8. In this embodiment, the inlet of the second circulation pipeline 14 is vertically higher than the partition plates 15.

[0050] Refer to in combinationFigure 1 , Figure 5 , the system further includes a sedimentation tank 10 and a filter 11; the material outlet is connected to the sedimentation tank 10, and the sedimentation tank 10 is connected to the filter 11. In this embodiment, the number of filters 11 is two, and the two filters 11 are arranged in parallel. The two filters 11 can adopt an open-and-closed application mode to avoid stopping the machine due to cleaning the filter 11.

[0051] As Figure 5 shown, an arc-shaped filter cloth 20 is arranged inside the filter 11; the arc-shaped filter cloth 20 divides the inner chamber of the filter 11 into a filtration chamber and a filtrate chamber, the filtrate chamber is connected to the product pipeline, and the side wall of the filtration chamber is connected to the hydrogenation reactor 8. A guiding plate 21 is arranged at the inlet of the filter 11, and the guiding plate 21 extends obliquely downward along the direction close to the arc-shaped filter cloth 20. The reacted material flows upward from bottom to top in the hydrogenation reactor 8, flows into the sedimentation tank 10 from the material outlet for precipitation, the supernatant is product 1,3-propanediol, and the lower turbid liquid is filtered and separated by the filter 11. The filtered solid catalyst is returned to the hydrogenation reactor 8 for recycling, and the filtrate is product 1,3-propanediol.

[0052] This embodiment also provides a method for preparing 1,3-propanediol, and this method uses the above system to prepare 1,3-propanediol.

[0053] This method specifically includes the following steps: First, deionized water is introduced into the first enhanced mass transfer device 2 and the second enhanced mass transfer device 5 in the hydration reactor 1, and acrolein, N-alkyl amino acid, and hydroquinone are added to the hydration reactor 1 according to 5-25%, 5-15%, and 0-0.1% of the mass of the hydration reaction solution. A hydration reaction is carried out under the conditions of a pressure of 0-0.5 MPa (gauge pressure), a temperature of 30-60 °C, and a time of 2-4 h to generate 3-hydroxypropionaldehyde. The reacted material flows upward from bottom to top in the hydration reactor 1 and flows into the rotating disk extraction column 6 from the top of the tower for extraction and separation. The extractant is selected from at least one of methyl tert-butyl ether, ethyl ether, and benzene. The number of theoretical extraction plates is 3-6, the extraction method is countercurrent extraction, the oil-water mass ratio is 1.5-5:1, and the extraction temperature is 25-40 °C. The separated aqueous phase containing 3-hydroxypropionaldehyde flows into the hydrogenation reactor 8 from the bottom of the tower for hydrogenation reaction, and the oil phase containing N-alkyl amino acid and unreacted acrolein flows into the distillation column 7 from the top of the tower for distillation and separation. The acrolein produced at the top of the distillation column 7 flows into the hydration reactor 1 for recycling, the extractant produced in the middle section flows into the extraction column for recycling, and the N-alkyl amino acid produced at the bottom of the tower flows into the hydration reactor 1 for recycling.

[0054] Then, the powdered supported noble metal catalyst is loaded into the hydrogenation reactor 8, and hydrogen is introduced into the microinterface intensification unit of the hydrogenation reactor 8. The pressure of the hydrogenation reaction is controlled at 2 - 5 MPa (gauge pressure), the temperature is 40 - 100 °C, and the space velocity is 1 - 5 h -1 The hydrogenation reaction is carried out to produce 1,3 - propanediol. The reacted material flows upward in the hydrogenation reactor 8 and flows into the sedimentation tank 10 from the top of the tower for precipitation. The supernatant is the product 1,3 - propanediol, and the lower turbid liquid is separated by filtration. The filtered solid catalyst is returned to the hydrogenation reactor 8 for recycling, and the filtrate is the product 1,3 - propanediol.

[0055] In this example, the specific process for preparing 1,3 - propanediol is as follows: 6.8 kg of deionized water is introduced into the first mass transfer intensification unit of the hydration reactor, 1.5 kg of acrolein and 0.4 kg of N - alkyl amino acid catalyst are added, and the reaction is carried out under the conditions of a pressure of 0.2 MPa (gauge pressure) and a temperature of 55 °C for 3 h. The reacted material flows upward in the hydration reactor and flows into a rotating disk extraction column (with 5 trays, an extraction temperature of 30 °C, and the hydrated reaction liquid and the extractant methyl tert - butyl ether are extracted counter - currently at a mass ratio of 1:2) from the top of the tower for extraction and separation. The aqueous phase containing 3 - hydroxypropionaldehyde separated out flows into the hydrogenation reactor from the bottom of the tower for hydrogenation reaction. The pressure of the hydrogenation reaction is 5 MPa (gauge pressure), the temperature is 90 °C, and the space velocity is 1.5 h -1 , after 1 h of reaction, the conversion rate of 3 - hydroxypropionaldehyde is 99.4%, and the selectivity of 1,3 - propanediol is 99.5%.

[0056] In this example, the mass percentage contents of each component (except the solvent) in the hydrated reaction liquid before extraction, the oil phase and the aqueous phase after extraction are shown in Table 1.

[0057] Table 1 Mass percentage contents of each component before and after extraction

[0058] Example 2 The system used in this example is the same as that in Example 1. The specific process for preparing 1,3 - propanediol in this example is as follows: 7.8 kg of deionized water is introduced into the first mass transfer intensification unit of the hydration reactor, 0.8 kg of acrolein and 1.4 kg of N - alkyl amino acid catalyst are added, and the reaction is carried out under the conditions of a pressure of 0.1 MPa (gauge pressure) and a temperature of 35 °C for 2 h. The reacted material flows upward in the hydration reactor and flows into a rotating disk extraction column for extraction and separation from the top of the tower. The aqueous phase containing 3 - hydroxypropionaldehyde separated out flows into the hydrogenation reactor from the bottom of the tower for hydrogenation reaction. The pressure of the hydrogenation reaction is 4 MPa (gauge pressure), the temperature is 60 °C, and the space velocity is 1.5 h -1, after reacting for 1 h, the conversion rate of 3-hydroxypropionaldehyde was 97.4%, and the selectivity of 1,3-propanediol was 98.5%.

[0059] Example 3 The system used in this example was the same as that in Example 1. The specific process for preparing 1,3-propanediol in this example was as follows: 9.2 kg of deionized water was introduced into the first enhanced mass transfer unit of the hydration reactor, 2.0 kg of acrolein and 1.5 kg of N-alkyl amino acid catalyst were added, and the reaction was carried out at a pressure of 0.4 MPa (gauge pressure) and a temperature of 60 °C for 2 h. The reacted material flowed upward in the hydration reactor and flowed into the rotary disk extraction column from the top of the tower for extraction and separation. The aqueous phase containing 3-hydroxypropionaldehyde separated out flowed into the hydrogenation reactor from the bottom of the tower for hydrogenation reaction. The pressure of the hydrogenation reaction was 4 MPa (gauge pressure), the temperature was 80 °C, and the space velocity was 1.5 h -1 , after reacting for 1 h, the conversion rate of 3-hydroxypropionaldehyde was 99.8%, and the selectivity of 1,3-propanediol was 99.8%.

[0060] Example 4 The specific process for preparing 1,3-propanediol in this example was the same as that in Example 1, except that in this example, the third enhanced mass transfer unit was arranged vertically directly above the second enhanced mass transfer unit, and at this time, the lower outlet of the third enhanced mass transfer unit was opposite to the upper outlet of the fourth enhanced mass transfer unit. In this example, after reacting for 1 h, the conversion rate of 3-hydroxypropionaldehyde was 98.1%, and the selectivity of 1,3-propanediol was 98.3%.

[0061] Example 5 The specific process for preparing 1,3-propanediol in this example was the same as that in Example 1, except that the outlets of the first circulation pipeline and the second circulation pipeline were at the same height. In this example, after reacting for 1 h, the conversion rate of 3-hydroxypropionaldehyde was 99.1%, and the selectivity of 1,3-propanediol was 99.2%.

[0062] Comparative Example 1 The specific process for preparing 1,3-propanediol in this example was the same as that in Example 1, except that in this example, the first enhanced mass transfer unit was not arranged in the hydration reactor, and the second enhanced mass transfer unit was not arranged in the hydrogenation reactor. After hydrogenation reaction for 1 h, the conversion rate of 3-hydroxypropionaldehyde was 76.3%, and the selectivity of 1,3-propanediol was 87.4%.

[0063] Comparative Example 2 In this example, the first enhanced mass transfer unit is not provided in the hydration reactor, and the second enhanced mass transfer unit is not provided in the hydrogenation reactor. The specific process for preparing 1,3-propanediol in this example is as follows: 6.8 kg of deionized water is introduced into the hydration reactor, and 1.5 kg of acrolein and 0.4 kg of N-alkyl amino acid catalyst are added. The reaction is carried out at a pressure of 0.2 MPa (gauge pressure) and a temperature of 55 °C for 3 h. The reacted material flows upward in the hydration reactor and flows into the extraction tower from the top of the tower for extraction and separation. The aqueous phase containing 3-hydroxypropionaldehyde separated out flows into the hydrogenation reactor from the bottom of the tower for hydrogenation reaction. The pressure of the hydrogenation reaction is 10 MPa (gauge pressure), the temperature is 110 °C, and the space velocity is 1.5 h -1 . After reacting for 1 h, the conversion rate of 3-hydroxypropionaldehyde is 84.2%, and the selectivity of 1,3-propanediol is 89.1%.

[0064] According to Examples 1-5, it can be seen that the system of the present invention has a high raw material conversion rate and a better selectivity of 1,3-propanediol when preparing 1,3-propanediol.

[0065] Comparing Example 1 and Example 4, it can be seen that in terms of both raw material conversion rate and selectivity of 1,3-propanediol, Example 1 is superior to Example 4. This may be because the outlets of the two enhanced mass transfer units in Example 4 are opposite to each other, resulting in a dead zone of the reaction liquid. In Example 1, the reaction liquid is agitated by staggering the outlets of the two enhanced mass transfer units. Therefore, the distribution uniformity of the catalyst and microbubbles in the reaction liquid in the hydrogenation reactor in Example 1 is better, the reaction rate is fast, and both the raw material conversion rate and the selectivity of 1,3-propanediol are better.

[0066] Comparing Example 1 and Example 5, it can be seen that in terms of both raw material conversion rate and selectivity of 1,3-propanediol, Example 1 is superior to Example 5. This may be because in Example 1, by specifically adjusting the outlet positions of the two circulation pipelines, the agitation effect on the reaction liquid is strengthened, so that the distribution uniformity of the catalyst and microbubbles in the reaction liquid in the hydrogenation reactor in Example 1 is better than that in Example 5, and the reaction rate is faster. As a result, both the raw material conversion rate of the hydrogenation reaction and the selectivity of 1,3-propanediol in Example 1 are better.

[0067] Comparing Example 1, Comparative Example 1, and Comparative Example 2, it can be seen that both the raw material conversion rate and the selectivity of 1,3-propanediol in Example 1 are superior to those in Comparative Example 1 and Comparative Example 2. This shows that by setting up the enhanced mass transfer unit, the interfacial mass transfer area between raw materials is increased, the reaction rate is increased, and thus the raw material conversion rate and the selectivity of 1,3-propanediol are increased.

[0068] In summary, the system of the present invention can increase the interfacial mass transfer area between raw materials in the acrolein hydration reaction and the hydrogenation reaction, and improve the raw material conversion rate and the selectivity of 1,3-propanediol by utilizing the first enhanced mass transfer unit disposed in the hydration reactor and the second enhanced mass transfer unit disposed in the hydrogenation reactor.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit 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 they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and 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 1,3-propylene glycol, characterized in that: include: A first feed pipeline, a second feed pipeline, a third feed pipeline, a fourth feed pipeline, a hydration reactor, a rotating disc extraction tower and a hydrogenation reactor; The first feed pipeline is used to transport a mixed solution of acrolein, a homogeneous catalyst and a polymerization inhibitor, and the first feed pipeline is connected to the hydration reactor; The second feed pipeline is used to transport deionized water, a first enhanced mass transfer unit is provided in the hydration reactor, and the second feed pipeline is connected to the first enhanced mass transfer unit; The outlet of the hydration reactor is connected to the rotary disc extraction tower, and the water phase outlet of the rotary disc extraction tower is connected to the bottom of the hydrogenation reactor through a delivery pipeline; The third feed pipeline is used to transport hydrogen, a second enhanced mass transfer unit is provided in the hydrogenation reactor, and the third feed pipeline is connected to the second enhanced mass transfer unit; The fourth feed pipeline is used to transport the hydrogenation reaction catalyst, and the fourth feed pipeline is connected to the transport pipeline; The hydrogenation reactor is a slurry bed reactor; the material outlet of the hydrogenation reactor is higher than the second enhanced mass transfer unit in the vertical direction, and the material outlet is lower than the liquid level in the hydrogenation reactor in the vertical direction; A baffle is arranged near the material outlet in the hydrogenation reactor, and the top of the baffle is higher than the material outlet in the vertical direction and lower than the liquid level of the hydrogenation reactor; the bottom of the baffle extends obliquely downward along the direction close to the side wall of the hydrogenation reactor to form an extension part, and there is a gap between the bottom of the extension part and the side wall of the hydrogenation reactor.

2. The system according to claim 1, characterized in that The first enhanced mass transfer unit comprises a first enhanced mass transferor and a second enhanced mass transferor, and the second feed pipeline is connected to the first enhanced mass transferor and the second enhanced mass transferor respectively; The first enhanced mass transferor and the second enhanced mass transferor are both provided with outlets at the upper and lower ends, the number of outlets at the upper end of the first enhanced mass transferor is less than the number of outlets at the lower end, and the number of outlets at the upper end of the second enhanced mass transferor is greater than the number of outlets at the lower end; The first intensified mass transfer device is disposed above the second intensified mass transfer device in the vertical direction, and the first intensified mass transfer device and the second intensified mass transfer device are staggered in the vertical direction.

3. The system according to claim 2, characterized in that The first feed pipeline has a first outlet and a second outlet, the first outlet is located above the second outlet in the vertical direction, and the first outlet and the second outlet are both located between the first intensified mass transferor and the second intensified mass transferor in the vertical direction; The first outlet is connected to a side wall of the hydration reactor that is farther from the first enhanced mass transferor, and the second outlet is connected to a side wall of the hydration reactor that is farther from the second enhanced mass transferor.

4. The system according to claim 1, characterized in that The second enhanced mass transfer unit comprises a third enhanced mass transferor and a fourth enhanced mass transferor, and the third feed pipeline is connected to the third enhanced mass transferor and the fourth enhanced mass transferor respectively; The third and fourth enhanced mass transfer devices are provided with outlets at both upper and lower ends, the number of outlets at the upper end of the third enhanced mass transfer device is less than the number of outlets at the lower end, and the number of outlets at the upper end of the fourth enhanced mass transfer device is greater than the number of outlets at the lower end; The third intensified mass transferor is arranged above the fourth intensified mass transferor in the vertical direction, and the third intensified mass transferor and the fourth intensified mass transferor are arranged alternately in the vertical direction.

5. The system according to claim 4, characterized in that It also includes a first circulation pipeline, the inlet of which is connected to the bottom of the hydrogenation reactor, and the outlet is connected to the side wall of the hydrogenation reactor farther from the fourth enhanced mass transferor; the outlet of the first circulation pipeline is located between the third enhanced mass transferor and the fourth enhanced mass transferor.

6. The system according to claim 5, characterized in that It also includes a second circulation pipeline; the inlet of the second circulation pipeline is connected to the side wall of the hydrogenation reactor close to the baffle and the inlet of the second circulation pipeline is lower than the bottom of the extension portion in the vertical direction; the outlet of the second circulation pipeline is connected to the side wall of the hydrogenation reactor far from the third enhanced mass transferor; the outlet of the second circulation pipeline is located between the third enhanced mass transferor and the fourth enhanced mass transferor; Preferably, the outlet of the first circulation pipeline is located below the outlet of the second circulation pipeline in the vertical direction.

7. The system according to any one of claims 1 to 6, characterized in that: A plurality of partitions are arranged in the hydrogenation reactor, the plurality of partitions are arranged in a staggered manner, and the plurality of partitions are located between the baffle and the second enhanced mass transfer unit in the vertical direction; Preferably, the partition is arranged to be inclined downward in a direction away from the side wall of the hydrogenation reactor.

8. The system according to any one of claims 1 to 6, characterized in that: It also includes a sedimentation tank and a filter; the material outlet is connected to the sedimentation tank, and the sedimentation tank is connected to the filter; an arc-shaped filter cloth is arranged in the filter; the arc-shaped filter cloth divides the inner chamber of the filter into a filter chamber and a filtrate chamber, the filtrate chamber is connected to the product pipeline, and the side wall of the filter chamber is connected to the hydrogenation reactor; Preferably, the number of the filters is two, and the two filters are arranged in parallel; Preferably, a guide plate is provided at the inlet of the filter, and the guide plate is extended obliquely downward in a direction close to the arc-shaped filter cloth.

9. The system according to any one of claims 1 to 6, characterized in that: The oil phase outlet of the rotary disc extraction tower is connected to the distillation tower; the bottom outlet and the top outlet of the distillation tower are both connected to the first feed pipeline, and the middle section outlet of the distillation tower is connected to the rotary disc extraction tower.

10. A method for preparing 1,3-propylene glycol, characterized in that: 1,3-propylene glycol is prepared using the system described in any one of claims 1 to 9.

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