External circulation type tetrahydrofuran preparation device

Abstract

The utility model provides an external circulation type device for preparing tetrahydrofuran. The device comprises a gas-liquid separator, a cyclization reactor and a pump, the top of the cyclization reactor is connected with the upper part of the gas-liquid separator, so that a gas-liquid mixture extracted from the cyclization reactor enters the gas-liquid separator; the bottom of the gas-liquid separator is connected with the bottom of the cyclization reactor, and a pump is arranged on a connecting pipeline, so that a liquid-phase discharged material of the gas-liquid separator enters the cyclization reactor. Uniform passing of reaction liquid in the cyclization reactor is achieved through external circulation, the problems that materials are mixed, products are separated and a catalyst is prone to being broken under stirring are fundamentally solved, the activity of the catalyst is exerted, meanwhile, the reaction products are rapidly separated in the gas-liquid separator, circulating liquid basically does not contain tetrahydrofuran and water, and the production cost is reduced. The reaction equilibrium is pushed forward, so that the raw material conversion rate is increased.

Description

Technical Field

[0001] The utility model belongs to the field of tetrahydrofuran preparation and relates to an external circulation type device for preparing tetrahydrofuran. Background Art

[0002] Tetrahydrofuran is an important organic chemical and fine chemical raw material with a wide range of uses. At present, its production processes mainly include furfural method, maleic anhydride direct hydrogenation method, and 1,4-butanediol dehydration method. Among them, the furfural method has complex process, high raw material consumption, and serious pollution, and has been gradually eliminated. The maleic anhydride direct hydrogenation method uses maleic anhydride aqueous solution as raw material. The solution is highly corrosive and has high corrosion protection requirements for equipment materials. The hydrogenation pressure is high, and the investment and operating costs are high. The 1,4-butanediol dehydration method is the current mainstream production process. 1,4-butanediol is dehydrated under acid or cationic resin catalysis to produce tetrahydrofuran. This method is simple, mature, and has the characteristics of low reaction temperature and high yield.

[0003] The common continuous preparation process of tetrahydrofuran by 1,4-butanediol method uses a fixed reaction bed as a reactor, which is filled with a solid catalyst, and the liquid phase reactant flows under the action of the solid catalyst for catalytic reaction. However, this method is limited by chemical equilibrium, resulting in a low degree of reaction conversion (the conversion rate is usually 35 to 45%), which affects the product yield and requires the recovery of a large amount of unreacted 1,4-butanediol. In response to this problem, various parties have proposed different technical improvement measures, but while improving the product yield, there are still certain defects.

[0004] Chinese utility model patent document CN 116003350 discloses a method for preparing tetrahydrofuran, wherein BDO is vaporized and then enters a tube-type fixed bed reactor, the inner side of the tubes of the tube-type fixed bed reactor is filled with a catalyst, the temperature of vaporizing BDO is 233-245°C, and the space velocity is 20-40h -1 The bed temperature of the tube-in-tube fixed bed reactor is 233-245°C, and the outlet pressure is 5-10KPaG. This method has a high reaction temperature and consumes a lot of energy to vaporize BDO.

[0005] Chinese utility model patent document CN 110746383A, a crude distillation section containing fillers is set at the top of the reactor. After the reaction materials pass through the crude distillation section, they are condensed and separated in the separation tank in turn. The condensate obtained is refluxed to the crude distillation section, and the gaseous materials obtained are sent to the subsequent separation and refining section. This utility model patent uses the method of introducing inert gas to stir the materials in the reactor. According to the characteristics of the large difference in boiling points between raw materials and products, the boiling point of 1,4-butanediol is 228°C, the boiling point of water is 100°C, and the boiling point of tetrahydrofuran is 66°C, so that the product water and tetrahydrofuran will be quickly vaporized once they are generated, thereby realizing the separation of gaseous products and liquid raw materials. However, when the amount of inert gas introduced is small, it is not enough to mix the materials in the reactor evenly; when the amount of inert gas introduced is large, it will cause a large amount of 1,4-butanediol to be taken out, making the post-processing process complicated and increasing energy consumption. At the same time, the heat of product gasification phase change will cause a huge temperature difference between the upper and lower parts of the catalyst bed, the bed temperature is uneven, and the temperature at the top of the bed is significantly lower, making it difficult to efficiently exert catalytic activity. Utility Model Content

[0006] In view of the above problems, the utility model provides a device for preparing tetrahydrofuran, comprising: a gas-liquid separator, a cyclization reactor and a pump;

[0007] The top of the cyclization reactor is connected to the upper part of the gas-liquid separator, so that the gas-liquid mixture produced by the cyclization reactor enters the gas-liquid separator;

[0008] The bottom of the gas-liquid separator is connected to the bottom of the cyclization reactor, and the pump is arranged on the connecting pipeline so that the liquid phase discharge of the gas-liquid separator enters the cyclization reactor;

[0009] The gas-liquid mixture contains tetrahydrofuran, or further contains unreacted 1,4-butanediol;

[0010] The liquid phase output contains 1,4-butanediol.

[0011] According to an embodiment of the present utility model, the gas-liquid separator includes a heating component and a gas phase separation and removal component located above the heating component.

[0012] According to the implementation scheme of the utility model, the gas phase separation and removal component is composed of a liquid phase distribution component and a gas-liquid separation component;

[0013] The liquid phase distribution component is composed of a liquid sprayer, a liquid distributor and a liquid collecting tank;

[0014] The gas-liquid separation component is composed of a tower plate, a filler or a combination of the two.

[0015] According to an implementation scheme of the utility model, in terms of positional relationship from top to bottom, they are liquid sprayer, tower plate, liquid collecting tank, liquid distributor, and filler.

[0016] According to the embodiment of the present utility model, the number of the tower plates may be 0 to 5.

[0017] According to an embodiment of the present invention, the height of the filler can be 0 to 3 meters.

[0018] The number of plates and the height of the packing are not both equal to 0.

[0019] According to an embodiment of the present invention, the heating component includes but is not limited to an inner coil, a finned tube, a heating jacket, a heating disc, a heat exchange tube (such as a coated heat exchange tube) or a combination of any two or more thereof.

[0020] According to the implementation scheme of the utility model, the gas-liquid separator is provided with:

[0021] The first material inlet is located at the upper part of the gas phase separation and removal component, so that the gas-liquid mixture produced by the cyclization reactor enters the gas-liquid separator and is separated into gas and liquid by the gas phase separation and removal component;

[0022] The second material inlet is located in the middle of the gas-liquid separation component so that fresh 1,4-butanediol is fed into the middle of the gas-liquid separation component; or, located in the lower part of the gas-liquid separator so that fresh 1,4-butanediol is fed above the heating component.

[0023] According to the implementation scheme of the utility model, the gas-liquid separator is provided with:

[0024] a steam inlet, located above the heating component;

[0025] The steam condensate outlet is located below the heating component.

[0026] According to the implementation scheme of the utility model, the gas-liquid separator is provided with:

[0027] A gas phase outlet, located at the top of the gas-liquid separator, for extracting the gas in the gas-liquid mixture, namely, tetrahydrofuran and water;

[0028] The liquid phase outlet is located at the bottom of the gas-liquid separator; the liquid phase outlet is connected to the pump, and the liquid phase containing 1,4-butanediol enters the cyclization reactor through the pump.

[0029] According to an embodiment of the present utility model, the cyclization reactor is a fixed reaction bed reactor.

[0030] According to an embodiment of the utility model, a catalyst is arranged in the cyclization reactor, for example, the catalyst is a solid acid catalyst, including but not limited to a cation exchange resin catalyst and / or a molecular sieve catalyst.

[0031] According to an embodiment of the utility model, the cyclization reactor is provided with:

[0032] A feed inlet, located at the bottom of the cyclization reactor, connected to the pump, and the liquid phase containing 1,4-butanediol extracted from the gas-liquid separator enters the cyclization reactor through the pump;

[0033] The discharge port is located at the top of the cyclization reactor and is connected to the first material inlet.

[0034] According to a preferred embodiment of the utility model, the device for preparing tetrahydrofuran comprises: a gas-liquid separator, a cyclization reactor and a pump;

[0035] The cyclization reactor comprises: a feed inlet arranged at the bottom of the cyclization reactor and a discharge outlet arranged at the top of the cyclization reactor;

[0036] The gas-liquid separator comprises: a first material inlet, a second material inlet, a gas phase outlet, a liquid phase outlet, a heating component, and a gas phase separation and removal component located above the heating component;

[0037] The first material inlet is arranged at the upper part of the gas phase separation and removal component, and the discharge port is connected to the first material inlet;

[0038] The second material inlet is arranged in the middle or lower part of the gas-liquid separation component, so that fresh 1,4-butanediol enters the gas-liquid separator;

[0039] The gas phase outlet is arranged at the top of the gas-liquid separator for discharging tetrahydrofuran;

[0040] The liquid phase outlet is arranged at the bottom of the gas-liquid separator, the liquid phase outlet is connected to the feed port through a pipeline, and the pump is arranged on the connecting pipeline;

[0041] The gas phase separation and removal component is composed of a liquid phase distribution component and a gas-liquid separation component;

[0042] The liquid phase distribution component is composed of a liquid sprayer, a liquid distributor and a liquid collecting tank;

[0043] The gas-liquid separation component is composed of a tray, a filler or a combination of the two;

[0044] According to the position relationship from top to bottom, they are liquid sprayer, tower plate, liquid collecting tank, liquid distributor and packing.

[0045] The utility model also provides a method for preparing tetrahydrofuran, comprising: a gas-liquid mixture extracted from a cyclization reactor enters a gas-liquid separator for gas-liquid separation, the obtained gas phase containing tetrahydrofuran is extracted, the obtained liquid phase is mixed with fresh 1,4-butanediol, heated, and returned to the cyclization reactor for further reaction;

[0046] The gas-liquid mixture produced by the cyclization reactor enters the gas-liquid separator, and the liquid phase and the fresh 1,4-butanediol mixture return to the cyclization reactor, all driven by a pump;

[0047] Preferably, the preparation method is carried out in the above-mentioned device.

[0048] According to an embodiment of the present invention, the temperature of the heated mixture of the liquid phase and fresh 1,4-butanediol is 90-160°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C.

[0049] Beneficial Effects

[0050] The utility model combines a cyclization reactor with a gas-liquid separator. The reaction liquid containing 1,4-butanediol is extracted from the bottom of the gas-liquid separator and enters the cyclization reactor for reaction under the push of a pump. The gas-liquid mixed product is discharged from the top of the cyclization reactor and enters the gas-liquid separator. The gas-liquid separator sequentially completes the separation of liquid-phase unreacted 1,4-butanediol and gas-phase reaction products tetrahydrofuran and water, the mixing of the circulating reaction liquid and fresh 1,4-butanediol, and the heating of the mixed material. The utility model realizes the uniform passage of the reaction liquid in the cyclization reactor through external circulation, fundamentally solves the problems of material mixing, product separation, and easy breakage of the catalyst due to stirring, so that the activity of the catalyst can be brought into play. At the same time, the reaction product can be quickly separated in the gas-liquid separator, so that the circulating liquid basically does not contain tetrahydrofuran and water, and the reaction balance is pushed in a positive direction, which is conducive to improving the raw material conversion rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a structural schematic diagram of a tetrahydrofuran reaction device;

[0052] Figure 2 for Figure 1 Schematic diagram of the structure of the gas-liquid separator R1;

[0053] Reference numerals: R1-gas-liquid separator, R2-cyclization reactor, B-pump;

[0054] 1-liquid sprayer, 2-tower plate, 3-liquid collecting tank, 4-liquid distributor, 5-packing, 6-heating disc, 7-housing;

[0055] a-fresh 1,4-butanediol, b-liquid phase discharge, c-cyclization reactor feed, d-gas-liquid mixture, e-gas phase discharge, f-steam, g-steam condensate. DETAILED DESCRIPTION

[0056] The following will further describe the technical solution of the utility model in combination with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the utility model, and should not be interpreted as limiting the scope of protection of the utility model. All technologies implemented based on the above content of the utility model are included in the scope of protection of the utility model.

[0057] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0058] The inventors found that the common continuous preparation process of tetrahydrofuran by 1,4-butanediol method uses a fixed reaction bed as a reactor, and a solid catalyst is loaded in the reactor, so that the liquid phase reactant flows under the action of the solid catalyst for catalytic reaction. When the fixed reaction bed reactor is not set with stirring, the disturbance generated by the gasification of the product itself is not enough to mix the materials in the reactor evenly. At the same time, the heat of the product gasification phase will cause a large temperature difference between the upper and lower layers of the catalyst bed, and the uneven bed temperature makes it difficult to efficiently exert the catalytic activity. The lack of disturbance of the reaction liquid will also make it difficult to remove the gas phase product, resulting in a low degree of reaction conversion and affecting the product yield. Although the problem of mixing materials in the reactor can be solved by installing a stirrer above the solid catalyst, mechanical stirring will cause the catalyst to break and reduce the service life of the catalyst. When the material in the reactor is stirred by the method of introducing an inert gas, when the amount of the introduced inert gas is small, it is not enough to mix the materials in the reactor evenly; when the amount of the introduced inert gas is large, 1,4-butanediol will be taken out in large quantities, making the post-processing process complicated and increasing energy consumption.

[0059] Based on this, the utility model provides a tetrahydrofuran reaction device, such as Figure 1 As shown, the reaction device consists of a gas-liquid separator R1, a cyclization reactor R2 and a pump B;

[0060] The cyclization reactor R2 is a fixed-type reaction bed reactor, in which a solid acid catalyst is arranged, including but not limited to a cation exchange resin catalyst and / or a molecular sieve catalyst; a feed inlet is arranged at the bottom of the cyclization reactor R2 and a discharge port is arranged at the top of the cyclization reactor R2;

[0061] In one embodiment, the structure of the gas-liquid separator R1 is as follows Figure 2As shown, it includes: a shell 7, a first material inlet, a second material inlet, a gas phase outlet, a liquid phase outlet, a heating component, and a gas phase separation and removal component located above the heating component; the heating component and the gas phase separation and removal component are located in the shell 7;

[0062] The gas phase separation and removal component is composed of a liquid phase distribution component and a gas-liquid separation component;

[0063] The liquid phase distribution component is composed of a liquid sprayer 1, a liquid distributor 4 and a liquid collecting tank 3;

[0064] The gas-liquid separation component is composed of a tray 2 and a filler 5;

[0065] According to the position relationship from top to bottom, they are liquid sprayer 1, tray 2, liquid collecting tank 3, liquid distributor 4, and packing 5;

[0066] After the gas-liquid mixture at the top of the cyclization reactor enters the gas-liquid separator, it is first distributed on the tower plate by liquid spraying in the liquid sprayer, and then it is distributed on the packing by the liquid collecting tank and liquid distributor. That is, forced distribution, by setting multiple gas-liquid distribution components in the equipment, the material is distributed under the action of the gas-liquid distribution components, and the distribution effect of the mixture is improved.

[0067] The first material inlet is arranged at the upper part of the gas phase separation and removal component, and the discharge port of the cyclization reactor R2 is connected to the first material inlet, so that the gas-liquid mixed discharge of the cyclization reactor enters the gas-liquid separator, and the gas-liquid separation is performed in the gas phase separation and removal component;

[0068] The second material inlet is arranged in the middle of the gas-liquid separation component, so that fresh 1,4-butanediol enters the gas-liquid separator; in another embodiment, the second material inlet is arranged at the lower part of the gas-liquid separation component;

[0069] The gas phase outlet is arranged at the top of the gas-liquid separator R1 for discharging tetrahydrofuran and water;

[0070] The liquid phase outlet is arranged at the bottom of the gas-liquid separator R1, and is connected to the feed port of the cyclization reactor R2 through a pipeline, and a pump B is arranged on the connecting pipeline;

[0071] The number of trays 2 does not exceed 0 to 5, and the height of the packing 5 does not exceed 3 meters;

[0072] The heating component is a heating disc 6; in some embodiments, it can also be an inner coil, a finned tube, a heating jacket, a heat exchange tube, a coated heat exchange tube, or a combination of any two or more of the above;

[0073] The gas-liquid separator R1 is also provided with a steam inlet located above the heating disc 6 and a steam condensate outlet located below the heating disc 6. The steam f flows inside the heating disc 6, and exchanges heat with the material outside the disc on the surface of the metal disc through the heating disc 6, and heats the liquid phase separated by the gas-liquid separator and the fresh 1,4-butanediol mixture to the required temperature, and the steam condensate g after heat exchange is discharged from the bottom of the heating disc 6.

[0074] The gas-liquid mixture d from the cyclization reactor R2 enters the gas-liquid separator R1 from the top, and first passes through the liquid sprayer 1 to evenly distribute the material above the tower plate 2. The tower plate 2 will provide sufficient contact area for the removal of tetrahydrofuran and water in the gas-liquid mixture d. The material after passing through the tower plate is collected in the liquid collecting tank 3, and at the same time, fresh 1,4-butanediol a is fed from the top of the liquid collecting tank 3 into the gas-liquid separator R1. The material in the liquid collecting tank 3 enters the packing 5 below through the liquid distributor 4, and the circulating reaction liquid after the separation of tetrahydrofuran and water and the fresh 1,4-butanediol a are mixed on the packing, and tetrahydrofuran and water are further removed at the same time. The removed tetrahydrofuran and water are the gas phase output e, which is extracted from the top of the gas-liquid separator R1. The heating disc 6 in the lower part of the gas-liquid separator R1 is used to heat and supplement the heat loss of the reactor. The mixed reaction liquid is extracted from the bottom of the gas-liquid separator R1. The liquid phase discharge b becomes the feed c of the cyclization reactor under the action of pump B and enters the cyclization reactor R2 for reaction. The reaction product of the cyclization reactor R2 and the unreacted raw material, that is, the gas-liquid mixture d, are driven by the continuous feeding of pump B and circulate into the gas-liquid separator R1.

[0075] Examples 1-3

[0076] use Figure 1 In the device for preparing tetrahydrofuran shown in the figure, the number of plates of the gas-liquid separator R1 is 3, and the packing height is 1 m. The cyclization reactor R2 is a fixed reaction bed reactor, using a cation exchange resin as a catalyst, and the purity of the raw material 1,4-butanediol is ≥99.9%. The feed flow rate of fresh 1,4-butanediol a is 16.9 kg / h, the temperature is 90°C, and the pressure is 0.2 MPa (G); the flow rate of the liquid phase discharge b at the bottom of the gas-liquid separator is 253.5 kg / h, the temperatures are 130, 135, and 140°C (corresponding to the embodiment in Table 1), and the pressure is 0.2 MPa (G); the flow rate of the feed c of the cyclization reactor is 253.5 kg / h, the temperatures are 130, 135, and 140°C (corresponding to the temperatures in Table 1), and the pressure is 0.25 MPa (G); the flow rate of the gas-liquid mixture d is 253.5 kg / h, the temperatures are 122, 127, and 132°C (corresponding to the embodiment in Table 1), and the pressure is 0.21 MPa (G); the flow rate of the gas phase discharge e is 16.9 kg / h, and the pressure is 0.20 MPa (G);

[0077] The raw material 1,4-butanediol is added to the reaction system from the gas-liquid separator R1 and mixed with the circulating reaction liquid after tetrahydrofuran and water are separated from the upper part of the gas-liquid separator R1. The heating disc of the gas-liquid separator R1 is used to heat and supplement the heat loss of the reactor. Under the action of pump B, the reaction liquid enters the cyclization reactor R2 for reaction. 1,4-Butanediol reacts at the interface of the cation exchange resin in the cyclization reactor to generate tetrahydrofuran and water. The reaction product and the unreacted raw material are circulated into the gas-liquid separator R1 under the promotion of pump B. The tetrahydrofuran and water removed on the gas phase separation and removal component are taken out at the top of the gas-liquid separator R1 and enter the tetrahydrofuran product refining process. The circulating 1,4-butanediol after the product is removed is mixed with the fresh raw material a to supplement the heat and enter the next cycle. By adjusting the outlet temperature of the reaction liquid of the gas-liquid separator R1, the yield under different reaction conditions is recorded, as shown in Table 1.

[0078] Table 1

[0079]

[0080] Note: Yield = ratio of the yield of tetrahydrofuran in the gas phase output to the amount of tetrahydrofuran product corresponding to the amount of fresh 1,4-butanediol a added.

[0081] The above describes the implementation methods of the present invention. However, the present invention is not limited to the above implementation methods. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An external circulation type device for preparing tetrahydrofuran, characterized in that, The device comprises: a gas-liquid separator, a cyclization reactor and a pump; The top of the cyclization reactor is connected to the upper part of the gas-liquid separator, so that the gas-liquid mixture produced by the cyclization reactor enters the gas-liquid separator; The bottom of the gas-liquid separator is connected to the bottom of the cyclization reactor, and the pump is arranged on the connecting pipeline so that the liquid phase discharge of the gas-liquid separator enters the cyclization reactor; The gas-liquid mixture contains tetrahydrofuran, or further contains unreacted 1,4-butanediol; The liquid phase output contains 1,4-butanediol.

2. The device according to claim 1, characterized in that The gas-liquid separator comprises a heating component and a gas phase separation and removal component located above the heating component.

3. The device according to claim 2, characterized in that The gas phase separation and removal component is composed of a liquid phase distribution component and a gas-liquid separation component; The liquid phase distribution component is composed of a liquid sprayer, a liquid distributor and a liquid collecting tank; The gas-liquid separation component is composed of a tray, a filler or a combination of the two; According to the position relationship from top to bottom, they are liquid sprayer, tower plate, liquid collecting tank, liquid distributor and packing.

4. The device according to claim 3, characterized in that The number of the tower plates is 0 to 5, and the height of the filler is 0 to 3 meters; the number of the tower plates and the height of the filler are not both 0.

5. The device according to claim 3, characterized in that The gas-liquid separator is provided with: The first material inlet is located at the upper part of the gas phase separation and removal component, so that the gas-liquid mixture produced by the cyclization reactor enters the gas-liquid separator and is separated into gas and liquid by the gas phase separation and removal component; The second material inlet is located in the middle of the gas-liquid separation component so that fresh 1,4-butanediol is fed into the middle of the gas-liquid separation component; or, located in the lower part of the gas-liquid separator so that fresh 1,4-butanediol is fed above the heating component.

6. The device according to claim 2, characterized in that The gas-liquid separator is provided with: a steam inlet, located above the heating component; The steam condensate outlet is located below the heating component.

7. The device according to claim 1, characterized in that The gas-liquid separator is provided with: A gas phase outlet, located at the top of the gas-liquid separator, for extracting the gas in the gas-liquid mixture, namely, tetrahydrofuran and water; The liquid phase outlet is located at the bottom of the gas-liquid separator; the liquid phase outlet is connected to the pump, and the liquid phase containing 1,4-butanediol enters the cyclization reactor through the pump.

8. The device according to claim 1, characterized in that The cyclization reactor is a fixed reaction bed reactor; And / or, a catalyst is arranged in the cyclization reactor; And / or, the cyclization reactor is configured as follows: A feed inlet, located at the bottom of the cyclization reactor, connected to the pump, and the liquid phase containing 1,4-butanediol extracted from the gas-liquid separator enters the cyclization reactor through the pump; The discharge port is located at the top of the cyclization reactor and is connected to the first material inlet of the gas-liquid separator.

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