Production system for preparing fatty nitrile by ammoniation and dehydrogenation of fatty alcohol

Abstract

The utility model discloses a production system for preparing fatty nitrile by ammonification and dehydrogenation of fatty alcohol. The production system comprises a vaporizer, a heat exchanger, a cooler, a gas-liquid separation tank, an absorption tower, a deamination tower, a light component removal tower, a dehydration tower, a pressurization tower and a product tower which are connected in sequence, the heat exchanger is connected with the superheater and the tubular reactor; the top of the gas-liquid separation tank and the top of the deamination tower are respectively connected with a vaporizer; the bottom of the gas-liquid separation tank is connected with the deamination tower; the top of the pressurizing tower is connected with the dehydrating tower; by setting efficient heating medium supply and heat exchange measures in a tubular reactor and controlling proper reaction conditions, uniform temperature distribution of a catalyst bed layer is realized, the fatty alcohol conversion rate and the selectivity of a target product are improved, a high-purity fatty nitrile product is obtained through rectification separation, and meanwhile, the high recovery rate of ammonia is realized.

Description

TECHNICAL FIELD

[0001] The application relates to a production system for preparing fatty nitrile through fatty alcohol amination dehydrogenation, and belongs to the field of fatty nitrile production. BACKGROUND

[0002] Fatty nitrile is an important chemical raw material and fine chemical intermediate, which is widely used in the fields of medicine, pesticide, dye and synthetic resin, and is also an important raw material for synthesizing fatty amine compounds. Common fatty nitriles include acetonitrile, propionitrile and butyronitrile.

[0003] Fatty nitrile can be prepared from fatty hydrocarbon, fatty alcohol, halogenated fatty hydrocarbon and ammonia as raw materials. Production systems include oxidation nitrile process, direct nitrification process, dehydration nitrification process and amination dehydrogenation process. Among them, the fatty alcohol amination dehydrogenation process has the advantages of simple reaction process, low raw material cost, high atom utilization rate and high industrial application value.

[0004] The process of preparing fatty nitrile through fatty alcohol amination dehydrogenation is a strong endothermic process, and a tube reactor is usually used. However, the conversion rate of fatty alcohol amination dehydrogenation reaction is low, the energy consumption in the production process is high, and it is not conducive to industrial production. CONTENT OF THE UTILITY MODEL

[0005] According to one aspect of the application, a production system for preparing fatty nitrile through fatty alcohol amination dehydrogenation is provided, which comprises a vaporizer, a heat exchanger, a cooler, a gas-liquid separation tank, an absorption tower, a deamination tower, a light component removal tower, a dehydration tower, a pressurization tower and a product tower connected in sequence.

[0006] The heat exchanger is connected with a superheater and a tube reactor.

[0007] The top of the gas-liquid separation tank and the top of the deamination tower are respectively connected with the vaporizer.

[0008] The bottom of the gas-liquid separation tank is connected with the deamination tower.

[0009] The top of the pressurization tower is connected with the dehydration tower.

[0010] Raw materials such as liquid ammonia, fatty alcohol and recycled ammonia, and circulating gas enter the vaporizer together, and the mixed raw materials are vaporized in the vaporizer. After being heated to the reaction temperature through the heat exchanger and the superheater, the materials enter the tube reactor for reaction. The reaction process requires a large amount of heat, which can be provided by the external heat medium, such as molten salt or hot air, to supplement the heat required for the reaction.

[0011] After the reaction, the materials are cooled through the heat exchanger and the cooler, and then the cooled reaction materials are subjected to gas-liquid separation in the gas-liquid separation tank. After the separation, part of the gas phase is returned to the vaporizer, and the other part of the gas phase enters the absorption tower for absorption. The absorption liquid and the liquid phase after the gas-liquid separation enter the deamination tower together to recover ammonia.

[0012] The upper liquid phase inlet of the absorption tower is connected with a desalted water pipeline, and desalted water is introduced to absorb soluble components such as ammonia in the feed gas phase, and the absorption liquid is sent to the ammonia removal tower, and the gas phase outlet at the top of the absorption tower discharges non-condensable gases such as hydrogen produced in the reaction;

[0013] The ammonia removal tower removes ammonia in the feed through distillation, and the ammonia discharged at the top is returned to the vaporizer, and the kettle liquid without ammonia enters the light component removal tower, and the low-boiling-point components in the feed are collected at the top of the light component removal tower, and the kettle liquid containing acetonitrile, water and heavy components flows into the water removal tower, and most of the water in the feed is collected at the kettle of the water removal tower, and a small amount of acetonitrile, high-boiling substances and azeotropic entrained water are collected at the top and sent to the pressurized tower;

[0014] In the pressurized tower, the acetonitrile and water azeotrope are collected from the top and returned to the inlet of the water removal tower, and the acetonitrile without water is collected at the kettle and enters the subsequent product tower, and the product tower is separated through rectification to obtain acetonitrile product at the top, and the by-product high-boiling substance is collected at the kettle, the conversion rate of fatty alcohol is more than 99%, the purity of fatty nitrile is more than 99.8%, and the selectivity of fatty nitrile is more than 85%;

[0015] Fatty alcohol conversion rate = (mole number of fatty alcohol in feed - mole number of fatty alcohol in product) / mole number of fatty alcohol in feed × 100%;

[0016] Fatty nitrile selectivity = (mole number of fatty nitrile in product) / (mole number of fatty alcohol in feed - mole number of fatty alcohol in product) × 100%.

[0017] The above process description only considers the connection relationship between upstream and downstream, and the conventional equipment such as pumps, compressors and condensers and reboilers of rectification towers between devices due to different pressures are not described.

[0018] Optionally, the outlet of the vaporizer is connected with the inlet of the cold side of the heat exchanger;

[0019] The outlet of the cold side of the heat exchanger is connected with the inlet of the superheater;

[0020] The outlet of the shell-and-tube reactor is connected with the inlet of the hot side of the heat exchanger, and the outlet of the hot side of the heat exchanger is connected with the inlet of the cooler.

[0021] Optionally, the gas phase outlet of the gas-liquid separation tank is divided into two streams, one of which is connected with the inlet of the vaporizer, and the other of which is connected with the lower gas phase inlet of the absorption tower;

[0022] The mass ratio of the gas phase going to the absorption tower is 0.2-1.0;

[0023] The liquid phase outlet of the gas-liquid separation tank is connected with the inlet of the ammonia removal tower.

[0024] Optionally, the liquid phase outlet of the absorption tower is connected to the inlet of the deamination tower.

[0025] Optionally, the tube reactor is provided with at least one heat medium inlet.

[0026] Optionally, when the heat medium is molten salt, 1-3 heat medium inlets are provided.

[0027] When there is more than one heat medium inlet, the ratio of the distance between the heat medium inlets to the length of the tube is 0.1-0.6.

[0028] The difference between the temperature of the molten salt inlet and the reaction temperature is 10-80℃.

[0029] Optionally, when the heat medium is hot air, 1-5 heat medium inlets are provided.

[0030] When there is more than one heat medium inlet, the ratio of the distance between the heat medium inlets to the length of the tube is 0.05-0.5.

[0031] The difference between the temperature of the hot air inlet and the reaction temperature is 15-150℃.

[0032] Optionally, a heat transfer enhancing accessory is provided outside the heat exchange tube.

[0033] Optionally, the heat transfer enhancing accessory is selected from external threads or fins.

[0034] When the tube reactor is used for preparing acetonitrile by ammoniating and dehydrogenating ethanol, the operating temperature is 300-500℃, the operating pressure is 0-1.0 MPaG, the molar ratio of ammonia to ethanol is 2-8, the mass space velocity of fatty alcohol is 0.1-1.0 h -1 .

[0035] Optionally, the absorption tower is operated at normal pressure, the operating temperature at the top of the tower is 0-40℃, and the ratio of the mass flow rate of desalted water to the standard volume flow rate of the gas phase is 0.5-10 kg / Nm 3 .

[0036] The beneficial effects that can be produced by the present application include:

[0037] The production system for preparing fatty nitrile by ammoniating and dehydrogenating fatty alcohol provided by the present application realizes uniform temperature distribution in the catalyst bed, improves the conversion rate of fatty alcohol and the selectivity of the target product by providing efficient heat medium supply and heat exchange measures in the tube reactor and controlling appropriate reaction conditions, and high purity fatty nitrile product is obtained through rectification separation, and high ammonia recovery rate is realized.

[0038] The production system provided by the present application can achieve the effects of a fatty alcohol conversion rate of more than 99%, a fatty nitrile purity of more than 99.8%, and a fatty nitrile selectivity of more than 85%. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A schematic diagram of a production system according to an embodiment of the present application is provided.

[0040] List of components and reference numerals:

[0041] R01 - tubular reactor, E01 - vaporizer, E02 - heat exchanger, E03 - superheater, E04 - cooler, V01 - gas-liquid separation tank, T01 - absorption column, T02 - deamination column, T03 - light-removing column, T04 - dehydration column, T05 - pressurizing column, T06 - product column. DETAILED DESCRIPTION

[0042] The present application will be described in detail below with reference to examples, but the present application is not limited to these examples.

[0043] As shown in Figure 1 According to an embodiment of the present application, a production system for preparing fatty nitrile by aminating and dehydrogenating fatty alcohol is provided, which comprises, in sequence, a vaporizer E01, a heat exchanger E02, a cooler E04, a gas-liquid separation tank V01, an absorption column T01, a deamination column T02, a light-removing column T03, a dehydration column T04, a pressurizing column T05, and a product column T06.

[0044] The heat exchanger E02 is connected with a superheater E03 and a tubular reactor R01;

[0045] The outlet of the vaporizer E01 is connected with the cold side inlet of the heat exchanger E02;

[0046] The cold side outlet of the heat exchanger E02 is connected with the inlet of the superheater E03;

[0047] The outlet of the tubular reactor R01 is connected with the hot side inlet of the heat exchanger E02, and the hot side outlet of the heat exchanger E02 is connected with the inlet of the cooler E04;

[0048] The gas-liquid separation tank V01 and the top of the deamination column T02 are respectively connected with the vaporizer E01;

[0049] The gas phase outlet of the gas-liquid separation tank V01 is divided into two streams, one of which is connected with the inlet of the vaporizer E01, and the other of which is connected with the lower gas phase inlet of the absorption column T01;

[0050] The mass ratio of the gas phase going to the absorption column T01 is 0.2-1.0;

[0051] The liquid phase outlet of the gas-liquid separation tank V01 is connected with the inlet of the deamination column T02;

[0052] The bottom of the gas-liquid separation tank V01 is connected with the deamination column T02;

[0053] The liquid phase outlet of the absorption tower T01 is connected to the inlet of the ammonia removal tower T02. The absorption tower T01 operates at atmospheric pressure, with a top operating temperature of 0–40°C. The ratio of the demineralized water mass flow rate to the gaseous standard volume flow rate is 0.5–10 kg / Nm³. 3 ;

[0054] The top of the pressurization tower T05 is connected to the dehydration tower T04;

[0055] The tubular reactor R01 is provided with at least one heat medium inlet.

[0056] When the heat medium is molten salt, 1 to 3 heat medium inlets are provided;

[0057] When there is more than one heat medium inlet, the ratio of the spacing between the heat medium inlets to the length of the tube is 0.1 to 0.6;

[0058] The temperature difference between the molten salt inlet and the reaction temperature is 10–80°C.

[0059] When the heat medium is hot air, 1 to 5 heat medium inlets are provided;

[0060] When there is more than one heat medium inlet, the ratio of the spacing between the heat medium inlets to the length of the tube is 0.05 to 0.5;

[0061] The temperature difference between the hot air inlet and the reaction temperature is 15–150°C.

[0062] An enhanced heat transfer accessory is provided on the outside of the heat exchange tube, and the enhanced heat transfer accessory is selected from external threads or fins.

[0063] When the tubular reactor R01 is used for the ammoniation and dehydrogenation of ethanol to produce acetonitrile, the operating temperature is 300–500℃, the operating pressure is 0–1.0 MPaG, the ammonia-to-ethanol molar ratio is 2–8, and the mass hourly space velocity (WHSV) of the fatty alcohol is 0.1–1.0 h⁻¹. -1 .

[0064] Process:

[0065] The raw materials, liquid ammonia, fatty alcohol, recycled ammonia, and circulating gas enter the vaporizer E01 together. The mixed raw materials are vaporized together in the vaporizer E01. After being heated by the heat exchanger and superheater E03 to reach the reaction temperature, they enter the tubular reactor R01 for reaction. The reaction process has a large heat absorption, which can be provided by the external heat medium, such as molten salt or hot air to supplement the heat required for the reaction.

[0066] The reacted material is cooled by a heat exchanger and a cooler E04, and the cooled reaction material is subjected to gas-liquid separation in a gas-liquid separation tank V01. After separation, part of the gas phase is returned to the vaporizer E01, and the other part of the gas phase is introduced into an absorption tower T01 for absorption. The absorption liquid and the liquid phase after gas-liquid separation are introduced into an ammonia removal tower T02 for ammonia recovery.

[0067] The liquid phase inlet at the upper part of the absorption tower T01 is connected with a desalted water pipeline, and desalted water is introduced into the absorption tower T01 to absorb the soluble components such as ammonia in the gas phase. The absorption liquid is introduced into the ammonia removal tower T02, and the gas phase at the top of the absorption tower T01 is discharged as non-condensable gas such as hydrogen produced in the reaction.

[0068] The ammonia removal tower T02 removes ammonia in the feed by distillation. The ammonia at the top of the tower is returned to the vaporizer E01, and the kettle liquid without ammonia is introduced into a light component removal tower T03. The low-boiling-point components in the feed are removed at the top of the light component removal tower T03, and the kettle liquid containing acetonitrile, water and heavy components is introduced into a water removal tower T04. Most of the water in the feed is removed at the kettle of the water removal tower T04, and a small amount of acetonitrile, high-boiling-point substances and azeotropic entrainment water are removed at the top of the tower and introduced into a pressurized tower T05.

[0069] In the pressurized tower T05, the acetonitrile and water azeotrope is removed at the top of the tower and returned to the inlet of the water removal tower T04. The acetonitrile without water is removed at the kettle of the tower and introduced into a product tower T06. The product tower T06 is subjected to rectification and separation, and acetonitrile product is obtained at the top of the tower. The high-boiling-point by-product is removed at the kettle of the tower. The conversion rate of the fatty alcohol is more than 99%, the purity of the fatty nitrile is more than 99.8%, and the selectivity of the fatty nitrile is more than 85%.

[0070] The conversion rate of the fatty alcohol = (the number of moles of the fatty alcohol in the feed - the number of moles of the fatty alcohol in the product) / the number of moles of the fatty alcohol in the feed x 100%.

[0071] The selectivity of the fatty nitrile = the number of moles of the fatty nitrile in the product / (the number of moles of the fatty alcohol in the feed - the number of moles of the fatty alcohol in the product) x 100%.

[0072] The above process description only considers the connection relationship between the upstream and downstream. The conventional devices such as pumps, compressors, condensers and reboilers of the rectification towers between the devices due to different pressures are not described.

[0073] Example 1

[0074] The production system of the application is used for preparing acetonitrile by ethanol amination dehydrogenation. The catalyst uses a supported metal oxide catalyst developed by Dalian Institute of Chemical Physics. The heat medium of the tubular reactor R01 is hot air, and fins are arranged outside the heat exchange tubes. Three heat medium inlets are arranged, and the ratio of the distance between the heat medium inlets to the length of the tubes is 0.25. The difference between the temperature of the hot air inlet and the reaction temperature is 80°C. The reaction temperature is controlled by adjusting the temperature of the hot air inlet. The reaction temperature is 200°C, the pressure is 0.5 MPa, the space velocity is 0.5 h-1, the reaction time is 2 h, the conversion rate of the fatty alcohol is more than 99%, the purity of the fatty nitrile is more than 99.8%, and the selectivity of the fatty nitrile is more than 85%. Figure 1The gas-liquid separation tank V01 outlet vapor phase to the absorption tower T01 gas phase mass ratio is 0.7; the absorption tower T01 is operated at normal pressure, the tower top operating temperature is 20℃, and the ratio of the desalted water mass flow rate to the vapor phase standard volume flow rate is: 3kg / Nm 3 . The column reactor R01 operating temperature is 420℃, the operating pressure is 0.1MPaG, the ammonia alcohol molar ratio is 6, and the fatty alcohol mass space velocity is 0.5h -1 .

[0075] It is calculated that in the embodiment, the ethanol conversion rate is 99.8%, the acetonitrile purity is 99.95%, and the acetonitrile selectivity is 87.5%.

[0076] Comparative Example 1

[0077] The traditional production system is used for preparing acetonitrile by ethanol amination dehydrogenation, the catalyst uses the supported metal oxide catalyst developed by Dalian Institute of Chemical Physics, the heat medium of the column reactor R01 uses molten salt, one heat medium inlet is arranged, and the heat medium inlet spacing to column length ratio is 0.2. Figure 1 The other operating conditions are the same.

[0078] It is calculated that in the comparative example, the ethanol conversion rate is 97.5%, the acetonitrile purity is 99.9%, and the acetonitrile selectivity is 84.0%.

[0079] It can be seen from the comparison of the embodiment 1 and the comparative example 1 that the column reactor R01 and the production system of the application are used, and the raw material ethanol conversion rate and the product acetonitrile selectivity are obviously improved.

[0080] Example 2

[0081] The production system of the application is used for preparing acetonitrile by ethanol amination dehydrogenation, the catalyst uses the supported metal oxide catalyst developed by Dalian Institute of Chemical Physics, the heat medium of the column reactor R01 uses molten salt, and external threads are arranged outside the heat exchange tube; two heat medium inlets are arranged, the heat medium inlet spacing to column length ratio is 0.2, and the difference between the molten salt inlet temperature and the reaction temperature is 40℃; and the device connection mode shown in the figure is adopted. Figure 1 The gas-liquid separation tank V01 outlet vapor phase to the absorption tower T01 gas phase mass ratio is 0.8; the absorption tower T01 is operated at normal pressure, the tower top operating temperature is 20℃, and the ratio of the desalted water mass flow rate to the vapor phase standard volume flow rate is: 5kg / Nm 3 . The column reactor R01 operating temperature is 450℃, the operating pressure is 0.3MPaG, the ammonia alcohol molar ratio is 4, and the fatty alcohol mass space velocity is 0.3h -1 .

[0082] It is calculated that in the embodiment, the ethanol conversion rate is 99.9%, the acetonitrile purity is 99.95%, and the acetonitrile selectivity is 86.3%.

[0083] Example 3

[0084] The production system used in this application is for the ammonitrile-to-acetonitrile production via ethanol amination and dehydrogenation. The catalyst used is a supported metal oxide catalyst developed by the Dalian Institute of Chemical Physics. Molten salt is selected as the heat medium in the tubular reactor R01, and external threads are provided on the outside of the heat exchange tubes. Two heat medium inlets are provided, with the ratio of the inlet spacing to the tube length being 0.2. The temperature difference between the molten salt inlet and the reaction temperature is 40°C. Figure 1 The equipment connection shown indicates that the vapor phase mass ratio from the outlet of gas-liquid separator V01 to absorber T01 is 0.8; absorber T01 operates at atmospheric pressure with a top operating temperature of 20℃, and the ratio of demineralized water mass flow rate to standard vapor phase volume flow rate is 5 kg / Nm³. 3 The tubular reactor R01 operates at a temperature of 350℃ and a pressure of 0.1 MPaG, with an ammonia-to-methanol molar ratio of 2 and a mass hourly space velocity (WHSV) of 0.1 h⁻¹ for the fatty alcohol. -1 .

[0085] According to calculations, the ethanol conversion rate in this embodiment is 99.5%, the acetonitrile purity is 99.95%, and the acetonitrile selectivity is 85.6%.

[0086] Example 4

[0087] The production system used in this application is for the ammonitrile-to-acetonitrile production via ethanol ammoniation and dehydrogenation. The catalyst used is a supported metal oxide catalyst developed by the Dalian Institute of Chemical Physics. Hot air is selected as the heat medium for the R01 tube-type reactor, and fins are installed on the outside of the heat exchange tubes. Three heat medium inlets are provided, with the ratio of the inlet spacing to the tube length being 0.2. The temperature difference between the hot air inlet and the reaction temperature is 70°C. Figure 1 The equipment connection shown indicates that the vapor phase mass ratio from the outlet of gas-liquid separator V01 to absorber T01 is 0.75; absorber T01 operates at atmospheric pressure with a top operating temperature of 20℃, and the ratio of demineralized water mass flow rate to standard vapor phase volume flow rate is 4 kg / Nm³. 3 The tubular reactor R01 operates at a temperature of 500℃ and a pressure of 1.0 MPaG, with an ammonia-to-methanol molar ratio of 8 and a mass hourly space velocity (WHSV) of 1.0 h⁻¹ for the fatty alcohol. -1 .

[0088] According to calculations, the ethanol conversion rate in this embodiment is 99.9%, the acetonitrile purity is 99.95%, and the acetonitrile selectivity is 87.1%.

[0089] The above description is only a part of the embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols, characterized in that, It includes a vaporizer, heat exchanger, cooler, gas-liquid separator, absorption tower, ammonia removal tower, light nitrate removal tower, dehydration tower, pressurization tower and product tower connected in sequence; The heat exchanger is connected to the superheater and the tubular reactor; The tops of the gas-liquid separator and the ammonia removal tower are respectively connected to the vaporizer; The bottom of the gas-liquid separator is connected to the ammonia removal tower; The top of the pressurization tower is connected to the dehydration tower.

2. The production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols according to claim 1, characterized in that, The outlet of the vaporizer is connected to the cold side inlet of the heat exchanger; The cold-side outlet of the heat exchanger is connected to the inlet of the superheater; The outlet of the tubular reactor is connected to the hot-side inlet of the heat exchanger, and the hot-side outlet of the heat exchanger is connected to the inlet of the cooler.

3. The production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols according to claim 1, characterized in that, The gas phase outlet of the gas-liquid separator is divided into two streams: one stream is connected to the inlet of the vaporizer, and the other stream is connected to the lower gas phase inlet of the absorption tower. The mass ratio of the gas phase going to the absorption tower is 0.2~1.0; The liquid phase outlet of the gas-liquid separator is connected to the inlet of the ammonia removal tower.

4. The production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols according to claim 1, characterized in that, The liquid phase outlet of the absorption tower is connected to the inlet of the deammoniation tower.

5. The production system for preparing fatty nitrile by amination and dehydrogenation of fatty alcohols according to claim 1, characterized in that, The tubular reactor is provided with at least one heat medium inlet.

6. The production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols according to claim 5, characterized in that, When the heat medium is molten salt, 1 to 3 heat medium inlets are provided; When there is more than one heat medium inlet, the ratio of the spacing between heat medium inlets to the length of the tube is 0.1 to 0.

6. The temperature difference between the molten salt inlet and the reaction temperature is 10~80℃.

7. The production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols according to claim 6, characterized in that, When the heat medium is hot air, 1 to 5 heat medium inlets are provided; When there is more than one heat medium inlet, the ratio of the spacing between the heat medium inlets to the length of the tube is 0.05 to 0.5; The temperature difference between the hot air inlet and the reaction temperature is 15~150℃.

8. The production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols according to claim 1, characterized in that, Enhanced heat transfer accessories are installed on the outside of the heat exchange tubes.

9. A production system for preparing fatty nitrile by amination and dehydrogenation of fatty alcohols according to claim 8, characterized in that, The enhanced heat transfer accessory is made of external thread or fins.

10. A production system for preparing fatty nitriles by amination and dehydrogenation of fatty alcohols according to claim 1, characterized in that, The absorption tower operates at atmospheric pressure, with a top operating temperature of 0~40℃, and the ratio of demineralized water mass flow rate to gas phase standard volume flow rate is 0.5~10 kg / Nm³.

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