A method and device for separating fractions of easily coking substances

Abstract

The present invention discloses a method for fractionating easily coked materials. After the easily coked materials are heated in a distillation tower or a still of a distillation apparatus, the light components contained therein are collected after flowing out through the distillation column of the distillation tower or the distillation tube of the distillation apparatus. The method heats the easily coked materials in the still as follows: a portion of the relatively light components is collected at the distillation column or the distillation tube, and after heating, the components are mixed with the extracted bottom material of the still through a venturi ejector and sprayed back into the still, whereby the materials in the still are heated by the sprayed reflux components. The linear velocity of the fluid at the nozzle of the venturi ejector is controlled to be 50 m / s to 80 m / s. By heating the relatively light components that are evaporated and then returning them to the still, the temperature difference between the light components and the temperature in the still is relatively low, thereby reducing high-temperature coking. At the same time, the light components are sprayed into the still to play an impact stirring role, thereby accelerating the heat transfer rate and further reducing coking.

Description

Technical Field

[0001] The present invention relates to a fraction separation technology for easily coking substances. Background Art

[0002] The substances that are easy to coke in the present invention include but are not limited to industrial heavy aromatics, oxygen-containing oils and fats, aniline tar hydrogenation products, etc. Industrial heavy aromatics are a kind of brown oil with a certain aromatic smell. After separation and purification, a high-boiling point aromatic solvent with a lighter color can be obtained. Because of its wide distillation range (170°C-400°C), some substances have a high boiling point. In order to obtain a high-boiling point aromatic solvent with a lighter color using a traditional distillation tower, it is often necessary to increase the reflux ratio and reduce the feed amount, which causes some high-boiling point substances to coke and carbonize, the yield of light components is low, and the proportion of residual oil increases. Oxygen-containing oils and fats mainly refer to the products of biodiesel prepared from animal and plant oils. Their composition is complex, and the boiling point of glycerides that have not been completely methylated is high. During the distillation process, oxygen-containing groups are also very easy to coke and gradually form carbon deposits to block pipelines. The product of aniline tar hydrogenation is mainly cyclohexylamine, which contains a large amount of amine-containing products that are difficult to lighten, and is very easy to coke and carbonize during the heating process.

[0003] In the traditional process of intermittent distillation or distillation of easily coked materials, the temperature of the external heat source of the kettle is continuously increased to allow the light component materials to continue to evaporate until no material flows out. During this process, the temperature of the heat source outside the kettle is high (generally 30 to 70°C higher than the temperature of the material in the kettle), and the mass and heat transfer of the material in the kettle is limited, the material is heated unevenly, the temperature of the heat source is large compared to the temperature of the material in the kettle, and a relatively stable high-temperature boundary layer exists at the kettle wall. The heating time is long, and it is very easy to coke and form carbon deposits on the inner wall of the kettle, further resulting in a low yield of light components. When using traditional continuous distillation or distillation operations, mass and heat transfer are limited by the area of ​​the heat exchanger and the material flow rate. During this process, the temperature difference between the heat source temperature of the heat exchanger and the temperature of the material in the kettle is large, and a relatively stable high-temperature boundary layer also exists. Some materials need to be reheated in the reboiler to increase the yield of the light component. This also leads to serious coking of easily coked materials in the reboiler and on the inner wall of the heat exchanger, which blocks the pipeline and further affects production capacity. Summary of the Invention

[0004] The purpose of the present invention is to solve the defects in the prior art and provide a method that can effectively solve the problem that traditional distillation towers or distillation devices are easily coked when heated, resulting in low yield of light components.

[0005] In order to achieve the above-mentioned object, the present invention provides a method for fraction separation of easily coking substances, which adopts a distillation tower or a distillation device, and the light components in the easily coking substances are heated in a kettle (i.e., the kettle of the distillation tower or the distillation kettle of the distillation device, hereinafter referred to as the kettle), and then flow out through the end of the distillation column or the distillation tube and are collected (the collected product is referred to as the light product); the fraction separation method of the present invention heats the easily coking substances in the kettle by the following manner: a portion of the components distilled from the kettle that are lighter than the substances in the kettle is collected at the distillation column or the distillation tube, and after heating, the components are mixed with the materials extracted from the bottom of the kettle through a venturi ejector and sprayed back into the kettle, and the materials in the kettle are heated by the sprayed reflux components; the fraction separation method controls the fluid linear velocity at the nozzle of the venturi ejector to be 50m / s to 80m / s.

[0006] The present invention uses the local negative pressure formed by the injection of material in the venturi ejector to extract a portion of the relatively light components evaporated from the kettle, and then heats the components through a heat exchanger and injects them into the kettle to mix. The heat exchanger provides the external heat required for the fraction separation process, and the kettle body is only insulated without heating, or only provides partial heat. This reduces the possibility of the existence of a high-temperature boundary layer in the kettle, or reduces the thickness and temperature gradient of the high-temperature boundary layer, thereby avoiding coking on the surface of the kettle wall and the surface of the heating tube. The material in the kettle forms a local circulation. After the lighter components are heated, they flow back into the tower kettle, and the material undergoes internal heat exchange, thereby achieving overall stirring and heating of the material. In this process, the temperature difference between the heated material and the material in the kettle is small, achieving rapid mass transfer and heat transfer, and effectively avoiding the coking problem.

[0007] The present invention simultaneously utilizes the venturi ejector to perform reflux injection of the material in the kettle and controls the fluid flow rate at the nozzle, thereby effectively improving the heat transfer effect, being beneficial to the separation and purification of light components, and further improving the yield of light components.

[0008] Furthermore, when a distillation column is used, the reflux ratio of the components distilled to the end of the distillation column is controlled to be 10:1 to 1:10.

[0009] In some embodiments, it is preferred to collect the components distilled from the kettle at the end of the distillation column or distillation tube near the kettle to reduce energy consumption. For example, the light components are collected at the first distillation plate of the distillation column and then heated for reflux injection.

[0010] Among them, the temperature difference between the heat exchanger outlet and the material temperature in the kettle is 5℃~10℃.

[0011] Furthermore, the components evaporated from the kettle collected by the above-mentioned distillation column or distillation tube are passed through a heat exchanger and then introduced into the air inlet of the venturi ejector; the bottom of the kettle is connected to the inlet section of the venturi ejector through a circulation pump; the nozzle of the venturi ejector extends into the kettle and is located below the liquid level of the material; the specifications of the venturi ejector are inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = (30~40): (2~6): (3~8): (40~200): (400~1800), and the opening angle of the diffusion section is 5~40°.

[0012] Furthermore, the above-mentioned easily coking substances are aniline tar hydrogenation products, biodiesel products or heavy aromatic hydrocarbons.

[0013] The present invention also provides a method for vacuum distillation of easily coking substances, which uses a distillation tower and controls the vacuum degree in the tower to -0.095±0.002MPa.

[0014] The present invention also provides a method for continuously distilling a coking-prone substance, wherein the coking-prone substance to be distilled is preheated and continuously introduced into the kettle of a distillation tower, and the vacuum degree in the tower is controlled at -0.095±0.002MPa.

[0015] The present invention also provides a device for separating the above-mentioned easily coking material fractions, comprising a distillation tower or a distillation device, a condenser, a venturi ejector, a heat exchanger, and a circulation pump; when a distillation tower is used, the distillation tower comprises a tower kettle and a distillation column, the top of the distillation column is connected to the condenser, and the condenser divides the condensed components into two paths through a regulating valve, one path is extracted as a light product, and the other path is refluxed into the distillation column, and the reflux extraction ratio is controlled by the regulating valve; when a distillation device is used, the distillation device comprises a distillation kettle and a distillation tube, the end of the distillation tube is connected to the condenser. The venturi ejector comprises an inlet section, a nozzle, a mixing section and a diffusion section which are connected in sequence; the inlet section and the nozzle are in a tapered tubular shape; a tapered annular air chamber is provided on the periphery of the inlet section and the nozzle, and the air chamber is connected to the mixing section; and the annular air chamber is provided with an air inlet; the diffusion section is in a gradually expanding tubular type; an interface is provided on the distillation column or the distillation tube and is connected to the air inlet of the venturi ejector through a heat exchanger; the bottom of the kettle is connected to the inlet section of the venturi ejector through a circulating pump; the nozzle of the venturi ejector extends into the kettle and is located below the liquid level of the material.

[0016] In some embodiments, as a preference, the specifications of the Venturi ejector are: inlet section opening inner diameter: nozzle inner diameter: chamber closing inner diameter: mixing section length: diffusion section length = (32~38): (2~6): (5~8): (80~200): (800~1800), and the opening angle of the diffusion section is 5~40°.

[0017] In some embodiments, as a preference, when the easily coking substance is the hydrogenation product of aniline tar, the specifications and dimensions of the Venturi injector are the inner diameter of the opening of the inlet section: the inner diameter of the nozzle: the inner diameter of the closing of the air chamber: the length of the mixing section: the length of the diffusion section = (35-38): (2-5): (5-8): (100-200): (900-1800), and the opening angle of the diffusion section is 10-40°; more preferably, the specifications and dimensions of the Venturi injector are the inner diameter of the opening of the inlet section: the inner diameter of the nozzle: the inner diameter of the closing of the air chamber: the length of the mixing section: the length of the diffusion section = 38:5:8:150:1200, and the opening angle of the diffusion section is 36°.

[0018] When the easily coking substance is a biodiesel product, the specifications and dimensions of the Venturi injector are the inner diameter of the inlet section opening: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = 35: (2-5): (5-8): (100-180): (800-1600), and the opening angle of the diffusion section is 5-30°; more preferably, the specifications and dimensions of the Venturi injector are the inner diameter of the inlet section opening: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = 35:3:6:150:800, and the opening angle of the diffusion section is 8°.

[0019] When the easily coking substance is heavy aromatic hydrocarbon, the specifications and dimensions of the Venturi ejector are the inner diameter of the opening of the inlet section: the inner diameter of the nozzle: the inner diameter of the closing of the air chamber: the length of the mixing section: the length of the diffusion section = 32: (2 to 6): (5 to 8): (80 to 180): (1000 to 1800), and the opening angle of the diffusion section is 12 to 35°; more preferably, the specifications and dimensions of the Venturi ejector are the inner diameter of the opening of the inlet section: the inner diameter of the nozzle: the inner diameter of the closing of the air chamber: the length of the mixing section: the length of the diffusion section = 32: 5: 8: 100: 1700, and the opening angle of the diffusion section is 25°.

[0020] In some embodiments, preferably, the place where the air inlet of the venturi ejector is connected to the lower end of the distillation column is located at the first distillation plate.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] This invention replaces traditional external kettle heating by heating the relatively lighter components distilled from the kettle through a heat exchanger and returning them to the kettle. The temperature of the lighter components heated by the heat exchanger is 5-10°C higher than the set temperature inside the kettle. Compared with traditional external kettle heating, this reduces the temperature difference and reduces high-temperature coking. Furthermore, the heated lighter components are injected into the kettle through impact stirring, which accelerates heat transfer compared to traditional external kettle heating, further reducing coking of easily coked materials at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of the distillation device of aniline tar hydrogenation product of the present invention;

[0024] Figure 2 for Figure 1 Schematic diagram of the structure of the Chinese Qiuli ejector;

[0025] Figure 1 In the figure, 1-tower bottom, 2-distillation column, 3-condenser, 4-regulating valve, 5-heat exchanger, 6-Venturi ejector, 7-circulation pump, 8-storage tank;

[0026] Figure 2 In the figure, D1 is the inner diameter of the inlet section opening, D2 is the inner diameter of the nozzle, D3 is the inner diameter of the air chamber closing, L1 is the length of the mixing section, L2 is the length of the diffusion section, α is the opening angle of the diffusion section; 601 is the inlet section, 602 is the mixing section, 603 is the diffusion section, 604 is the nozzle, 605 is the air chamber, and 606 is the air inlet. DETAILED DESCRIPTION

[0027] The distillation operation method in the following embodiments is as follows:

[0028] 1. Batch distillation operation

[0029] like Figure 1 As shown in FIG, the distillation device used for separating coking-prone substances of the present invention comprises a distillation tower kettle 1, a distillation column 2, a condenser 3, a regulating valve 4, a heat exchanger 5, a venturi ejector 6, a circulating pump 7, and a storage tank 8. Figure 2 The venturi ejector comprises an inlet section 601, a nozzle 604, a mixing section 602, and a diffuser section 603, which are interconnected in sequence. The inlet section and nozzle are in the form of a tapered tube. A tapered annular air chamber 605 is provided on the periphery of the inlet section and nozzle, communicating with the mixing section. The annular air chamber is provided with an air inlet 606. The diffuser section 603 is in the form of a gradually expanding tube. The top of the distillation column 2 is connected to the condenser 3. The condenser divides the condensed components into two paths via a regulating valve 4: one path is extracted to a storage tank 8, and the other path refluxes into the distillation column 2. The regulating valve 4 controls the reflux-to-extraction ratio. The lower end of the distillation column is connected to the air inlet 606 of the venturi ejector 6 via a heat exchanger 5. The bottom of the tower reactor 1 is connected to the inlet section 601 of the venturi ejector 6 via a circulating pump 7. The nozzle of the venturi ejector extends into the tower reactor and is located below the liquid level of the material.

[0030] When in use, the material to be separated is pumped into the feed port of the tower, the circulation pump 7 is turned on and the flow rate of the material at the nozzle of the venturi ejector 6 is adjusted to a certain value, the reflux ratio is set (the reflux ratio has no significant effect on the distillation effect, and is adjusted according to the material distillation situation and the flow rate of the venturi ejector nozzle, and can be within the range of 10:1-1:10), the condenser 3 is turned on, the temperature of the heat exchanger 5 is adjusted, and the material is continuously extracted until no material flows out of the top of the tower, and the light component material at the top and the residue in the tower are collected and weighed separately. When the device is turned on, the tower bottom material is slowly heated by external heating. When a fraction is extracted, the heat exchanger 5 is turned on to heat and provide the heat required for the distillation process. The tower bottom is only necessary for insulation without additional heating.

[0031] 2. Continuous distillation operation

[0032] like Figure 1 As shown, during continuous operation, the side feed pump is turned on and the flow rate of the material (which has been preheated to the corresponding temperature) is adjusted to a certain value (feeding from the feed port set in the distillation tower body), the vacuum degree in the tower and the reflux extraction ratio are adjusted, and when the heavy component drops to a certain liquid level in the tower bottom due to its high boiling point, the venturi ejector circulation pump 7 is turned on, and the heat exchanger 5 is adjusted. Through the negative pressure formed by the venturi ejector, part of the material in the distillation tower is extracted and heated and circulated to the tower bottom, so that the material that is not completely separated in the tower bottom is heated again. In this process, due to the strong mass transfer and heat transfer effect of the venturi ejector flow, the heat exchange efficiency is improved, and the temperature difference between the heat exchanger and the tower bottom material is small, thereby allowing the light component that is not completely separated in the tower bottom to obtain a heat source again and be effectively separated. Compared with the traditional continuous distillation tower using a reboiler for heating, the heat exchange efficiency is effectively improved, which can further increase the feed amount and increase production capacity. At the same time, due to the stirring effect of the venturi ejector, the heating is uniform, further reducing the possibility of coking and producing residual oil, and improving the yield of the light component.

[0033] Example 1 (Batch Distillation of Aniline Tar Hydrogenation Product)

[0034] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation tower kettle. The detailed design dimensions of the distillation venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the gas chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 35:4:6:150:1100, and the diffusion section opening angle α was 20°. Under normal pressure, the circulation pump was turned on and the timing was started so that the liquid linear velocity at the venturi ejector nozzle reached 50 m / s. The top condenser was turned on and the reflux ratio was adjusted to a full reflux state. The tower kettle material was initially heated slowly using external heating. When it was observed that the material at the top of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to provide the heat required for the distillation process. The tower kettle was only insulated as necessary without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 3.5 hours. During this process, the temperature difference between the material at the heat exchanger outlet and the material in the tower kettle was measured to be 10°C. The light component material at the top and the tower kettle residue were collected and weighed separately. The top material was 20.03 kg, accounting for 89%, and the tower kettle residue was 0.53 kg, accounting for 2.4%, with a loss of 8.6%.

[0035] Example 2 (Batch Distillation of Aniline Tar Hydrogenation Product)

[0036] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:4:6:150:1100, and the diffuser opening angle α was 20°. Under normal pressure, the circulating pump was started and the timer was started until the liquid linear velocity at the Venturi ejector nozzle reached 65 m / s. The top condenser was opened and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux steadily, heat exchanger 5 was activated to provide the required heat for the distillation process. The bottom was only insulated for necessary heat without additional heating. The reflux-to-receipt ratio was quickly adjusted to 1:2 and the receivable was withdrawn. When no material flowed out of the receivable end, heating was stopped and the entire process was recorded for 3.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 7°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 20.81kg, accounting for 92.5%, and the tower bottom residue was 0.45kg, accounting for 2%, with a loss of 5.5%.

[0037] Example 3 (Batch Distillation of Aniline Tar Hydrogenation Product)

[0038] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:4:6:150:1100, and the diffuser opening angle α was 20°. Under normal pressure, the circulation pump was turned on and the timer was started until the liquid linear velocity at the Venturi ejector nozzle reached 80 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux steadily, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:2 and the extraction process was continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 3.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 6°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 19.9kg, accounting for 88.4%, and the tower bottom residue was 0.63kg, accounting for 2.8%, with a loss of 8.8%.

[0039] Comparative Example 1 (Effect of Material Linear Velocity at Venturi Ejector Nozzle on Distillation)

[0040] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:4:6:150:1100, and the diffuser opening angle α was 20°. Under normal pressure, the circulation pump was turned on and the timer was started until the liquid linear velocity at the Venturi ejector nozzle reached 30 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux steadily, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat without additional heating. The reflux-to-receipt ratio was quickly adjusted to 1:2 and the receivable was withdrawn. When no material flowed out of the receivable end, heating was stopped and the entire process was recorded for 4.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 25°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 18.6kg, accounting for 82.7%, and the tower bottom residue was 2.18kg, accounting for 9.7%, with a loss of 7.6%.

[0041] It can be seen from Examples 1, 2, 3 and the comparative example that when the liquid linear velocity at the nozzle of the Venturi ejector is too low, the distillation time is long, and the proportion of tower bottom residue and loss is high.

[0042] Comparative Example 2 (Effect of Material Linear Velocity at Venturi Ejector Nozzle on Distillation)

[0043] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:4:6:150:1100, and the diffuser opening angle α was 20°. Under normal pressure, the circulating pump was turned on and the timer was started until the liquid linear velocity at the Venturi ejector nozzle reached 100 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The kettle material was initially heated slowly using external heating. Afterwards, heat exchanger 5 was turned on to provide the heat required for the distillation process. The kettle was only insulated as necessary without additional heating. At this point, as the temperature increased, the high injection linear velocity created a large negative pressure, resulting in significant pressure fluctuations in the system. The gas and liquid in the tower could not reach a stable equilibrium due to the disturbance caused by the Venturi ejector, and the experiment was terminated.

[0044] Comparative Example 3 (Batch distillation of aniline tar hydrogenation product in conventional distillation tower)

[0045] Into the 30L conventional distillation tower kettle, 22.5kg of aniline tar hydrogenation product was injected, the reflux ratio was adjusted to full reflux, the condenser was turned on, and the temperature of the distillation tower kettle was continuously increased by external electric heating under normal pressure until the top material of the distillation tower was observed to be in full reflux. The reflux ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the top of the tower. The heating was stopped and the whole process was recorded for 6 hours. During this process, the temperature difference between the electric heating temperature outside the kettle and the material in the tower kettle was 42°C. The light component material at the top and the tower kettle residue were collected and weighed separately. The top material was 18.03kg, accounting for 80.1%, and the tower kettle residue was 2.26kg, accounting for 10.1%, with a loss of 9.8%.

[0046] It can be seen from the above Examples 1-3 and Comparative Examples 1-3 that the linear velocity of the Venturi greatly affects the distillation effect. When the linear velocity is too low, it is almost indistinguishable from the traditional distillation kettle. When the linear velocity is too high, the gas-liquid equilibrium will be destroyed, resulting in the inability to produce. Therefore, the preferred linear velocity of the material at the nozzle is 50-80 m / s.

[0047] The present invention adopts a venturi ejector to accelerate the mass and heat transfer effect, so that the temperature difference between the tower bottom material temperature and the heat exchange outlet material is smaller, the distillation process time is shorter, and the light component yield is higher.

[0048] Example 4.1 (Vacuum Distillation of First-Generation Biodiesel Product)

[0049] 21 kg of first-generation biodiesel product was injected into the 30-L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:3:6:150:800, and the diffuser opening angle α was 8°. The vacuum pump was turned on to maintain the vacuum in the tower at -0.095 ± 0.002 MPa. The circulating pump was started and timing was started until the liquid linear velocity at the Venturi ejector nozzle reached 65 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:1 and the extraction process was continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 2.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 8°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 18.57kg, accounting for 88.4%, and the tower bottom residue was 0.48kg, accounting for 2.3%, with a loss of 9.3%.

[0050] Example 4.2

[0051] 21 kg of first-generation biodiesel product was injected into the 30-L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:4:5.5:150:1000, and the diffuser opening angle α was 15°. The vacuum pump was turned on to maintain the vacuum in the tower at -0.095 ± 0.002 MPa. The circulating pump was started and timing was started until the liquid linear velocity at the Venturi ejector nozzle reached 55 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:1 and the extraction process was continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 2.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 10°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 18.23kg, accounting for 86.8%, and the tower bottom residue was 0.59kg, accounting for 2.8%, with a loss of 10.4%.

[0052] Example 4.3

[0053] 21 kg of first-generation biodiesel product was injected into the 30-L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:2.5:6:100:900, with the diffuser opening angle α set at 20°. The vacuum pump was turned on to maintain the vacuum in the tower at -0.095 ± 0.002 MPa. The circulating pump was started and timing was started until the liquid linear velocity at the Venturi ejector nozzle reached 60 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:1 and the extraction process continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 2.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 9.5°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 18.4kg, accounting for 87.6%, and the tower bottom residue was 0.41kg, accounting for 2%, with a loss of 10.4%.

[0054] Example 4.4

[0055] 21 kg of first-generation biodiesel product was injected into the 30-L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:3:5.5:120:1300, and the diffuser opening angle α was 18°. The vacuum pump was turned on to maintain the vacuum in the column at -0.095 ± 0.002 MPa. The circulating pump was started and timing was started until the liquid linear velocity at the Venturi ejector nozzle reached 70 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:1 and the extraction process continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 2.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 8.5°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 18.29kg, accounting for 87.1%, and the tower bottom residue was 0.46kg, accounting for 2.9%, with a loss of 10%.

[0056] Example 4.5

[0057] 21 kg of first-generation biodiesel product was injected into the 30-L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:5:7.5:180:1600, and the diffuser opening angle α was 30°. The vacuum pump was turned on to maintain the vacuum in the tower at -0.095 ± 0.002 MPa. The circulating pump was started and timing was started until the liquid linear velocity at the Venturi ejector nozzle reached 75 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:1 and the extraction process was continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 2.5 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 7.5°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 18.1kg, accounting for 86.2%, and the tower bottom residue was 0.65kg, accounting for 3.1%, with a loss of 10.7%.

[0058] Comparative Example 4 (Vacuum Distillation of First-Generation Biodiesel Product in a Conventional Distillation Tower)

[0059] 21kg of first-generation biodiesel product was injected into the 30L distillation tower kettle, and the vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002MPa. The top condenser was turned on, and the reflux ratio was adjusted to the full reflux state. The kettle temperature was slowly increased by external electric heating. When it was observed that the material at the top of the distillation tower had begun to reflux and stabilize, the reflux withdrawal ratio was quickly adjusted to 1:1 for withdrawal. When no material flowed out of the withdrawal end, the heating was stopped and the whole process was recorded for 3h. During this process, the temperature difference between the electric heating temperature outside the kettle and the material in the tower kettle was measured to be 35°C. The light component material at the top and the tower kettle residue were collected and weighed separately. The top material was 16.96kg, accounting for 80.8%, and the tower kettle residue was 1.94kg, accounting for 9.2%, with a loss of 10%.

[0060] Example 5.1 (Vacuum Distillation of Heavy Aromatics)

[0061] 22.5 kg of heavy aromatics were injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 32:5:8:100:1700, with the diffuser opening angle α set at 25°. The vacuum pump was turned on to maintain the vacuum in the tower at -0.095 ± 0.002 MPa. The circulating pump was started and timing was started until the liquid linear velocity at the Venturi ejector nozzle reached 65 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:2 and the extraction process was continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 3 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 7°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 21.53 kg, accounting for 95.7%, and the tower bottom residue was 0.83 kg, accounting for 3.7%, with a loss of 0.6%.

[0062] Example 5.2

[0063] 22.5 kg of heavy aromatics were injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 32:5.5:8:80:1500, and the diffuser opening angle α was 12°. The vacuum pump was turned on to control the vacuum in the tower to -0.095 ± 0.002 MPa. The circulating pump was started and the timer was started until the liquid linear velocity at the Venturi ejector nozzle reached 55 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated as needed without additional heating. The reflux-to-take ratio was quickly adjusted to 1:2 and the extraction process continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 3 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 8.5°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 21.15kg, accounting for 94%, and the tower bottom residue was 0.9kg, accounting for 4%, with a loss of 2%.

[0064] Example 5.3

[0065] 22.5 kg of heavy aromatics were injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 32:4:5:110:1200, and the diffuser opening angle α was 15°. The vacuum pump was turned on to control the vacuum in the tower to -0.095 ± 0.002 MPa. The circulating pump was turned on and the timer was started until the liquid linear velocity at the Venturi ejector nozzle reached 60 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated as needed without additional heating. The reflux-to-take ratio was quickly adjusted to 1:2 and the extraction process was continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 3 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 8°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The tower top material was 21.33kg, accounting for 94.8%, and the tower bottom residue was 0.92kg, accounting for 4.1%, with a loss of 1.1%.

[0066] Example 5.4

[0067] 22.5 kg of heavy aromatics were injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 32:3.5:7:150:1000, with the diffuser opening angle α set at 30°. The vacuum pump was turned on to maintain the vacuum in the tower at -0.095 ± 0.002 MPa. The circulating pump was started and timing was started until the liquid linear velocity at the Venturi ejector nozzle reached 70 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux steadily, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated as needed without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:2 and the extraction process continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 3 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 7.5°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 21.03kg, accounting for 93.5%, and the tower bottom residue was 0.8kg, accounting for 3.6%, with a loss of 3%.

[0068] Example 5.5

[0069] 22.5 kg of heavy aromatics were injected into the 30 L distillation column kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 32:2.5:8:180:1750, and the diffuser opening angle α was 35°. The vacuum pump was turned on to control the vacuum in the tower to -0.095 ± 0.002 MPa. The circulating pump was started and the timer was started until the liquid linear velocity at the Venturi ejector nozzle reached 75 m / s. The top condenser was turned on and the reflux ratio was adjusted to full reflux. The bottom material was initially heated slowly using external heating. When the top material of the distillation column began to reflux and stabilize, heat exchanger 5 was turned on to provide the required heat for the distillation process. The bottom was only insulated as needed without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:2 and the extraction process continued until no material flowed out of the extraction end. Heating was then stopped and the entire process was recorded for 3 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 7°C. The light component material at the top and the tower bottom residue were collected and weighed separately. The top material was 21.26 kg, accounting for 94.5%, and the tower bottom residue was 0.98 kg, accounting for 4.4%, with a loss of 1.2%.

[0070] Comparative Example 5 (Vacuum Distillation of Heavy Aromatics in Traditional Distillation Tower)

[0071] 22.5kg of heavy aromatics were injected into the 30L distillation tower kettle, the vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002MPa, the top condenser was turned on, the reflux ratio was adjusted to the full reflux state, and the kettle temperature was slowly increased by external electric heating. When it was observed that the material at the top of the distillation tower had begun to reflux and stabilize, the reflux production ratio was quickly adjusted to 1:2 for production. When no material flowed out of the production end, the heating was stopped and the whole process was recorded for 4h. During this process, the temperature difference between the electric heating temperature outside the kettle and the material in the tower kettle was measured to be 40°C. The light component materials at the top and the residue in the tower kettle were collected and weighed respectively. The top material was 20.25kg, accounting for 90%, and the residue in the tower kettle was 1.98kg, accounting for 8.8%, with a loss of 1.2%.

[0072] Example 6.1 (Vacuum distillation of aniline tar hydrogenation product)

[0073] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation tower kettle. The detailed design dimensions of the distillation venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the gas chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 32:5:8:150:1200, and the diffusion section opening angle α was 36°. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the venturi ejector nozzle reached 65 m / s. The top condenser was turned on and the reflux ratio was adjusted to a full reflux state. The tower kettle material was initially heated slowly using external heating. When it was observed that the material at the top of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to provide the heat required for the distillation process. The tower kettle was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:3 and the extraction process continued until no material flowed out of the extraction port. Heating was then stopped and the entire process was recorded for 2 hours. During this process, the temperature difference between the heat exchanger outlet and the bottom of the tower was measured to be 9°C. The top light component material and the bottom residue were collected and weighed separately. The top material was 20.33 kg, accounting for 90.4%, and the bottom residue was 0.75 kg, accounting for 3.3%, resulting in a loss of 6.3%.

[0074] Example 6.2

[0075] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation tower kettle. The detailed design dimensions of the distillation venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the gas chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 38:3.5:6:100:950, and the diffusion section opening angle α was 15°. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the venturi ejector nozzle reached 55 m / s. The top condenser was turned on and the reflux ratio was adjusted to a full reflux state. The tower kettle material was initially heated slowly using external heating. When it was observed that the material at the top of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to provide the heat required for the distillation process. The tower kettle was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:3 and the extraction process continued until no material flowed out of the extraction port. Heating was then stopped and the entire process was recorded for 2 hours. During this process, the temperature difference between the heat exchanger outlet and the bottom of the tower was measured to be 9.5°C. The top light component material and the bottom residue were collected and weighed separately. The top material was 20.15 kg, accounting for 89.6%, and the bottom residue was 0.81 kg, accounting for 3.6%, resulting in a loss of 6.8%.

[0076] Example 6.3

[0077] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation tower kettle. The detailed design dimensions of the distillation venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the gas chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 38:4.5:5:120:1100, and the diffusion section opening angle α was 20°. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the venturi ejector nozzle reached 60 m / s. The top condenser was turned on and the reflux ratio was adjusted to a full reflux state. The tower kettle material was initially heated slowly using external heating. When it was observed that the material at the top of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to provide the heat required for the distillation process. The tower kettle was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:3 and the extraction process continued until no material flowed out of the extraction port. Heating was then stopped and the entire process was recorded for 2 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 8.5°C. The top light component material and the tower bottom residue were collected and weighed separately. The top material was 19.95 kg, accounting for 88.7%, and the tower bottom residue was 0.9 kg, accounting for 4%, for a loss of 7.3%.

[0078] Example 6.4

[0079] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation tower kettle. The detailed design dimensions of the distillation venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the gas chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 38:5:6.5:180:1500, and the diffusion section opening angle α was 25°. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the venturi ejector nozzle reached 70 m / s. The top condenser was turned on and the reflux ratio was adjusted to a full reflux state. The tower kettle material was initially heated slowly using external heating. When it was observed that the material at the top of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to provide the heat required for the distillation process. The tower kettle was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:3 and the extraction process continued until no material flowed out of the extraction port. Heating was then stopped and the entire process was recorded for 2 hours. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 8°C. The top light component material and the tower bottom residue were collected and weighed separately. The top material was 20.08 kg, accounting for 89.2%, and the tower bottom residue was 0.85 kg, accounting for 3.8%, a loss of 7%.

[0080] Example 6.5

[0081] 22.5 kg of aniline tar hydrogenation product was injected into the 30 L distillation tower kettle. The detailed design dimensions of the distillation venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: the nozzle inner diameter D2: the gas chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 38:2.5:7:190:1750, and the diffusion section opening angle α was 10°. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the venturi ejector nozzle reached 75 m / s. The top condenser was turned on and the reflux ratio was adjusted to a full reflux state. The tower kettle material was initially heated slowly using external heating. When it was observed that the material at the top of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to provide the heat required for the distillation process. The tower kettle was only insulated for necessary heat preservation without additional heating. The reflux-to-reduction ratio was quickly adjusted to 1:3 and the extraction process continued until no material flowed out of the extraction port. Heating was then stopped and the entire process was recorded for 2 hours. During this process, the temperature difference between the heat exchanger outlet and the bottom of the tower was measured to be 7.5°C. The top light component material and the bottom residue were collected and weighed separately. The top material was 19.89 kg, accounting for 88.4%, and the bottom residue was 0.96 kg, accounting for 4.3%, resulting in a loss of 7.3%.

[0082] Comparative Example 6 (Vacuum distillation of aniline tar hydrogenation product in conventional distillation tower)

[0083] Inject 22.5kg of aniline tar hydrogenation product into the 30L distillation tower kettle, turn on the vacuum pump to control the vacuum degree in the tower to -0.095±0.002MPa, turn on the top condenser, adjust the reflux ratio to full reflux state, slowly increase the kettle temperature by external electric heating, and when it is observed that the material at the top of the distillation tower has begun to reflux and stabilize, quickly adjust the reflux production ratio to 1:3 for production until no material flows out of the production end, stop heating and record the whole process for 3h. During this process, the temperature difference between the electric heating temperature outside the kettle and the material in the tower kettle was measured to be 40°C. Collect the light component material at the top and the tower kettle residue and weigh them separately. The top material is 18.52kg, accounting for 82.3%, and the tower kettle residue is 2.03kg, accounting for 8.7%, with a loss of 9%.

[0084] From the above Examples 4.1 to 4.5, 5.1 to 5.5, 6.1 to 6.5 and the corresponding Comparative Examples 4, 5 and 6, it can be seen that by using different easily coking materials, designing the corresponding Venturi specifications and dimensions, operating at a linear speed within a limited range, and adjusting the corresponding reflux ratio, the distillation tower takes less time than the traditional distillation tower, and has a higher light component yield and less heavy component residue.

[0085] Example 7 (Continuous Distillation of Heavy Aromatics)

[0086] Using the Venturi design of Example 5.1 above, heavy aromatics preheated to 170°C were continuously pumped into the distillation tower through the side line, and the feed rate of heavy aromatics was controlled to 12 kg / min. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa, the top condenser was turned on, and the reflux ratio was adjusted to 1:3 for extraction. When the material with a higher boiling point dropped to a liquid level in the tower bottom that exceeded the diffuser of the Venturi ejector, the circulation pump was turned on so that the linear velocity of the material out of the Venturi ejector nozzle reached 65 m / s. At the same time, the heat exchanger was turned on to continuously heat the material in the tower bottom. At this time, the temperature difference between the material in the tower bottom and the material at the outlet of the heat exchanger was measured to be 10°C. The top extraction flow rate and the tower bottom extraction flow rate were adjusted to reach a balance. At this time, the top extraction flow rate reached 11.55 kg / min, and the tower bottom extraction flow rate reached 0.38 kg / min. It was calculated that the light component accounted for 96.3%, the residual oil accounted for 3.1%, and the loss accounted for 0.6%.

[0087] Comparative Example 7 (continuous distillation of heavy aromatics in a conventional distillation tower)

[0088] As in Example 7 above, a conventional distillation tower was used to pump heavy aromatics preheated to 170°C into the distillation tower at an initial flow rate of 12 kg / min through the side line. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The top condenser was turned on and the reflux ratio was adjusted to 1:3 for extraction. When the material with a higher boiling point dropped into the tower kettle, the material in the tower kettle was further heated by electric heating outside the kettle, so that the light component was further separated. At this time, the temperature difference between the external electric heating temperature and the material in the tower kettle was measured to be 60°C. The top extraction flow rate and the tower kettle extraction flow rate were adjusted to reach a balance. At this time, the top extraction flow rate reached 10.35 kg / min, and the tower kettle extraction flow rate reached 1.36 kg / min. It was calculated that the light component accounted for 86.3%, the residual oil accounted for 11.3%, the loss accounted for 2.4%, and the separation effect was poor.

[0089] When the feed rate is reduced to 10kg / min, the temperature difference between the material in the tower bottom and the material at the heat exchanger outlet is measured to be 40°C. The flow rates of the top and bottom of the tower are adjusted to achieve balance. At this time, the top extraction is 8.99kg / min, and the bottom extraction is 0.82kg / min. It is calculated that the light component accounts for 89.9%, the residual oil accounts for 8.2%, and the loss is 1.9%.

[0090] Example 8 (Continuous Distillation of Biodiesel)

[0091] Using the Venturi design of Example 4.1 above, biodiesel preheated to 190°C was continuously pumped into the distillation tower through the side line, and the biodiesel feed rate was controlled to 10.8 kg / min. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The top condenser was turned on and the reflux ratio was adjusted to 1:1 for extraction. When the material with a higher boiling point dropped to a liquid level in the tower bottom that exceeded the diffuser of the Venturi ejector, the circulation pump was turned on so that the linear velocity of the material discharged from the Venturi ejector nozzle reached 65 m / s. At the same time, the heat exchanger was turned on to continuously heat the material in the tower bottom. At this time, the temperature difference between the material in the tower bottom and the material at the heat exchanger outlet was measured to be 9°C. The top extraction flow rate and the bottom extraction flow rate were adjusted to achieve a balance. At this time, the top extraction flow rate reached 9.56 kg / min and the bottom extraction flow rate reached 0.75 kg / min. It was calculated that the light component accounted for 88.5%, the residual oil accounted for 6.9%, and the loss accounted for 4.5%.

[0092] Comparative Example 8 (continuous distillation of biodiesel using a conventional distillation tower)

[0093] As in Example 8 above, a conventional distillation tower was used, and biodiesel preheated to 190° C. was pumped into the distillation tower through the side line at an initial flow rate of 10.8 kg / min. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa, the top condenser was turned on, and the reflux ratio was adjusted to 1:1 for extraction. When the material with a higher boiling point dropped into the tower kettle, the material in the tower kettle was further heated by electric heating outside the kettle, so that the light component was further separated. At this time, the temperature difference between the external electric heating temperature and the material in the tower kettle was measured to be 55° C. The top extraction flow rate and the tower kettle extraction flow rate were adjusted to reach a balance. At this time, the top extraction flow rate reached 8.7 kg / min, and the tower kettle extraction flow rate reached 1.52 kg / min. It was calculated that the light component accounted for 80.6%, the residual oil accounted for 14.1%, the loss accounted for 5.4%, and the separation effect was poor.

[0094] When the feed rate was reduced to 9 kg / min, the temperature difference between the material in the tower bottom and the material at the heat exchanger outlet was measured to be 39°C. The top and bottom extraction flow rates were adjusted to achieve balance. At this time, the top extraction rate was 7.5 kg / min and the bottom extraction rate was 1.05 kg / min. It was calculated that the light component accounted for 83.3%, the residual oil accounted for 11.7%, and the loss was 5%.

[0095] Example 9 (Continuous Distillation of Aniline Tar Hydrogenation Product)

[0096] Using the Venturi design of Example 6.1 above, the aniline tar hydrogenation product preheated to 120°C was continuously pumped into the distillation tower through the side line, and the feed rate was controlled to 12 kg / min. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The top condenser was turned on and the reflux ratio was adjusted to 1:3 for extraction. When the material with a higher boiling point dropped to a level in the tower bottom that exceeded the diffuser of the Venturi ejector, the circulation pump was turned on so that the linear velocity of the material discharged from the Venturi ejector nozzle reached 65 m / s. At the same time, the heat exchanger was turned on to continuously heat the material in the tower bottom. At this time, the temperature difference between the material in the tower bottom and the material at the heat exchanger outlet was measured to be 10°C. The top extraction flow rate was adjusted to achieve a balance with the bottom extraction flow rate. At this time, the top extraction flow rate reached 10.92 kg / min and the bottom extraction flow rate reached 0.49 kg / min. It was calculated that the light component accounted for 91%, the residual oil accounted for 4.1%, and the loss accounted for 4.9%.

[0097] Comparative Example 9 (Continuous distillation of aniline tar hydrogenation product in a conventional distillation tower)

[0098] As in Example 9 above, a conventional distillation tower was used to pump the aniline tar hydrogenation product preheated to 120° C. into the distillation tower through the side line at an initial flow rate of 12 kg / min. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002 MPa. The top condenser was turned on and the reflux ratio was adjusted to 1:3 for extraction. When the material with a higher boiling point dropped into the tower kettle, the material in the tower kettle was further heated by electric heating outside the kettle, so that the light component was further separated. At this time, the temperature difference between the external electric heating temperature and the material in the tower kettle was measured to be 68° C. The top extraction flow rate and the tower kettle extraction flow rate were adjusted to reach a balance. At this time, the top extraction flow rate reached 9.71 kg / min, and the tower kettle extraction flow rate reached 1.46 kg / min. It was calculated that the light component accounted for 80.9%, the residual oil accounted for 12.2%, the loss accounted for 6.9%, and the separation effect was poor.

[0099] When the feed rate was reduced to 10kg / min, the temperature difference between the material in the tower bottom and the material at the heat exchanger outlet was measured to be 42°C. The top and bottom extraction flow rates were adjusted to achieve balance. At this time, the top extraction was 8.35kg / min and the bottom extraction was 0.91kg / min. It was calculated that the light component accounted for 83.5%, the residual oil accounted for 9.1%, and the loss was 7.4%.

[0100] From the above examples of continuous distillation of materials prone to coking, it can be seen that the distillation method using a Venturi ejector combined with a traditional distillation tower can effectively improve the yield of light components and reduce the yield of residual oil. The powerful mass transfer and heat conversion effect of the Venturi ejector greatly improves the heat exchange efficiency, making the temperature difference between the bottom material and the heat exchanger outlet material temperature smaller, making it less likely to coke, thereby further improving the distillation capacity of materials prone to coking, and effectively solving a series of problems such as the easy coking of existing industrial equipment and the reduced production capacity caused by low heat exchange efficiency.

[0101] Example 10 (Batch distillation of aniline tar hydrogenation product using a distillation tower)

[0102] The device connection method is the same as that in Example 3, with the only difference being that the distillation tower is replaced by a distillation device, and the distillation components are collected on the side of the distillation tube near the kettle end and connected through a heat exchanger, and then introduced into the air inlet of the venturi ejector. The bottom of the kettle is connected to the inlet section of the venturi ejector through a circulating pump; the end of the distillation tube is connected to the condenser, and all the products flowing out of the condenser are collected without reflux.

[0103] 22.5 kg of aniline tar hydrogenation product was injected into a conventional 30-liter distillation kettle. The detailed design dimensions of the distillation Venturi ejector were as follows: the ratio of the inlet section opening inner diameter D1: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffuser length L2 was 35:4:6:150:1100, with a diffuser opening angle α of 20°. Under normal pressure, the circulation pump was started and timing was commenced until the liquid linear velocity at the Venturi ejector nozzle reached 80 m / s. The kettle contents were initially heated slowly to 270°C using external heating. Material was gradually withdrawn, and heat exchanger 5 was activated to provide the required heat for the distillation process. The kettle was only insulated until no material was discharged from the withdrawal end. Heating was then stopped, and the entire process was recorded for 1.7 hours. During this process, the temperature difference between the heat exchanger outlet and the kettle contents was measured to be 6°C. The light component materials flowing out of the condenser and the residue in the kettle were collected and weighed separately. The light component materials were 21.2 kg, accounting for 94%, and the residue in the kettle was 0.63 kg, accounting for 1.3%, with a loss of 4.7%.

[0104] As can be seen from the above embodiments, conventional distillation using the fraction separation device of the present invention can also accelerate the mass and heat transfer effects and reduce the temperature difference between the material temperature in the kettle and the material at the heat exchanger outlet. At the same time, compared with distillation, distillation technology does not require reflux, so the extraction speed is much faster, so the whole process time is shorter and the yield of light components is higher.

Claims

1. A method for fractionating a coking substance, comprising: heating the coking substance in a reactor of the distillation tower or distillation apparatus, and collecting the light components contained therein after flowing out through the distillation column of the distillation tower or the distillation tube of the distillation apparatus; characterized in that: The fraction separation method heats the easily coked material in the kettle in the following manner: a portion of the components distilled from the kettle is collected at a distillation column or a distillation tube, mixed with the material extracted from the bottom of the kettle through a venturi ejector after heating, and sprayed back into the kettle, where the material in the kettle is heated by the sprayed backflow components; the fraction separation method controls the fluid linear velocity at the nozzle of the venturi ejector to be 50m / s to 80m / s.

2. The fraction separation method according to claim 1, wherein The components collected from the distillation column or the distillation tube are passed through a heat exchanger and then introduced into the air inlet of the venturi ejector; the bottom of the kettle is connected to the inlet section of the venturi ejector through a circulation pump; the nozzle of the venturi ejector extends into the kettle and is located below the liquid level of the material; the specifications of the venturi ejector are as follows: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = (30-40): (2-6): (3-8): (40-200): (400-1800), and the opening angle of the diffusion section is 5-40°.

3. The fraction separation method according to claim 1, wherein The easily coking substance is a hydrogenation product of aniline tar, a biodiesel product or heavy aromatic hydrocarbons.

4. The fraction separation method according to claim 1, characterized in that When a distillation tower is used, the coking-prone substances are subjected to reduced-pressure distillation in the distillation tower, and the vacuum degree in the tower is controlled to be -0.095±0.002MPa.

5. The fraction separation method according to claim 4, characterized in that The fraction separation method is used for continuous distillation of easily coking substances; the easily coking substances are preheated and continuously introduced into the kettle of a distillation tower, and the vacuum degree in the tower is controlled at -0.095±0.002MPa.

6. The fraction separation method according to claim 3, characterized in that When the easily coking substance is a hydrogenation product of aniline tar, the specifications and dimensions of the Venturi injector are as follows: the inner diameter of the opening of the inlet section: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = (35-38): (2-5): (5-8): (100-200): (900-1800), and the opening angle of the diffusion section is 10-40°; when the easily coking substance is a biodiesel product ... Section length: diffusion section length = 35: (2-5): (5-8): (100-180): (800-1600), the opening angle of the diffusion section is 5-30°; when the easily coking substance is heavy aromatic hydrocarbons, the specifications of the venturi ejector are the inner diameter of the inlet section opening: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = 32: (2-6): (5-8): (80-180): (1000-1800), the opening angle of the diffusion section is 12-35°.

7. The fraction separation method according to claim 6, characterized in that When the easily coking substance is the hydrogenation product of aniline tar, the specifications and dimensions of the Venturi injector are the inner diameter of the inlet section opening: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = 38:5:8:150:1200, and the opening angle of the diffusion section is 36°; when the easily coking substance is a biodiesel product, the specifications and dimensions of the Venturi injector are the inner diameter of the inlet section opening: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = 35:3:6:150:800, and the opening angle of the diffusion section is 8°; when the easily coking substance is heavy aromatic hydrocarbons, the specifications and dimensions of the Venturi injector are the inner diameter of the inlet section opening: the inner diameter of the nozzle: the inner diameter of the air chamber closing: the length of the mixing section: the length of the diffusion section = 32:5:8:100:1700, and the opening angle of the diffusion section is 25°.

8. A fraction separation device for easily coking substances, characterized in that: The device includes a distillation tower or a distillation device, a condenser, a venturi ejector, a heat exchanger, and a circulation pump; the distillation tower includes a tower kettle and a distillation column; the distillation device includes a distillation kettle and a distillation pipe; the venturi ejector includes an inlet section, a nozzle, a mixing section, and a diffusion section that are sequentially connected; the inlet section and the nozzle are in a tapered tubular shape; the outer periphery of the inlet section and the nozzle is provided with a tapered annular air chamber, which is connected to the mixing section; the annular air chamber is provided with an air inlet; the diffusion section is a gradually expanding tubular type; when a distillation tower is used, the distillation The top of the column is connected to the condenser, and the condenser divides the condensed components into two paths through a regulating valve, one path is extracted as a light product, and the other path refluxes into the distillation column, and the reflux-extraction ratio is controlled by the regulating valve; when a distillation device is used, the end of the distillation tube is connected to the condenser; an interface is provided on the distillation column or the distillation tube, which is connected to the air inlet of the venturi ejector through a heat exchanger; the bottom of the kettle is connected to the inlet section of the venturi ejector through a circulating pump; the nozzle of the venturi ejector extends into the kettle and is located below the liquid level of the material.

9. The fraction separation device according to claim 8, characterized in that The specifications of the Venturi ejector are: inlet section opening inner diameter: nozzle inner diameter: air chamber closing inner diameter: mixing section length: diffusion section length = (32~38): (2~6): (5~8): (80~200): (800~1800), and the opening angle of the diffusion section is 5~40°.

10. The fraction separation device according to claim 9, characterized in that When a distillation column is used, the connection point between the air inlet of the venturi ejector and the lower end of the distillation column is located at the first distillation plate.

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