Method and device for separating fractions of easily-coked substances

Abstract

The invention discloses a fraction separation method of an easy-to-coke substance, which comprises the following steps: heating the easy-to-coke substance in a kettle of a rectifying tower or a distillation device, and extracting and collecting light components contained in the easy-to-coke substance after the light components flow out of a rectifying column of the rectifying tower or a distillation tube of the distillation device; according to the method, a heating mode for easily-coked substances in a kettle comprises the following steps: collecting part of relatively light components at a rectifying column or a distillation guide pipe, heating, mixing the components with extracted materials at the bottom of the kettle through a Venturi ejector, ejecting and refluxing into the kettle, and heating the materials in the kettle through the ejected and refluxed components; and the linear velocity of the fluid at the nozzle of the venturi ejector is controlled to be 50-80 m / s. According to the invention, the distilled light components are heated and then returned to the tower kettle, and the difference between the temperature of the light components and the temperature in the kettle is relatively low, so that high-temperature coking is reduced; meanwhile, light components are injected into the kettle to play an impact stirring role, so that the heat transfer rate is accelerated, and the coking phenomenon is further reduced.

Description

Technical Field

[0001] The 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, oxygenated oils and fats, and aniline tar hydrogenation products. Industrial heavy aromatics are a brown oil product with a certain aromatic smell. After separation and purification, a high-boiling 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. Using a traditional distillation tower to obtain a high-boiling aromatic solvent with a lighter color often requires increasing the reflux ratio and reducing the feed amount, which leads to the coking of some high-boiling substances, a low yield of light components, and an increase in the proportion of residual oil. Oxygenated oils and fats mainly refer to the products of biodiesel prepared using animal and plant oils and fats. They have complex components, 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 the pipeline. The hydrogenation product of aniline tar is mainly cyclohexylamine, which contains a large amount of amine-containing products that are difficult to lighten, and is very easy to coke during the heating process.

[0003] In the process of intermittent distillation or distillation of easily coked materials by traditional technology, the temperature of the external heat source of the kettle is continuously increased to make the light component material continue to evaporate until no material flows out. In 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 there is a relatively stable high-temperature boundary layer 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, which further leads to 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. In 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 there is also a relatively stable high-temperature boundary layer. Some materials need to be reheated in the reboiler to increase the yield of light components, which also leads to serious coking of easily coked materials in the reboiler and the inner wall of the heat exchanger, and the pipeline is blocked, further affecting 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 prone to coking when heated, resulting in low light component yield.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a fraction separation method for 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 partially collected products are used as light products); the fraction separation method of the present invention heats the easily coking substances in the kettle in the following manner: a part of the components distilled from the kettle that are lighter than the substances in the kettle are collected at the distillation column or the distillation tube, and after heating, they are mixed with the materials extracted from the bottom of the kettle and sprayed back into the kettle through a venturi ejector, and the materials in the kettle are heated by the sprayed reflux components; the fraction separation method controls the linear velocity of the fluid 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 material injection in the venturi injector to extract part of the relatively light components evaporated from the kettle, and then injects and mixes with the materials in the kettle after being heated by the heat exchanger. 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 part of the heat, which 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 materials in the kettle form a local circulation. After the lighter components are heated, they flow back into the tower kettle, and the materials are internally heat exchanged to achieve overall stirring and heating of the materials. In this process, the temperature difference between the heated materials and the materials in the kettle is small, which achieves rapid mass transfer and heat transfer, and effectively avoids 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 the light component and further improving the yield of the light component.

[0008] Furthermore, when a distillation tower 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 temperature 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 introduced into the air inlet of the venturi ejector after passing 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 surface of the material; the specifications 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 = (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 aromatics.

[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 substance, wherein the coking substance to be distilled is preheated and then continuously introduced into the kettle of a distillation tower, and the vacuum degree in the tower is controlled to be -0.095±0.002MPa.

[0015] The present invention also provides a device for separating the above-mentioned coking-prone material fractions, comprising a rectifying tower or a distillation device, a condenser, a venturi ejector, a heat exchanger, and a circulating pump; when a rectifying tower is used, the rectifying tower comprises a tower kettle and a rectifying column, the top of the rectifying column is connected to the condenser, 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, and the reflux extraction ratio is controlled by the regulating valve. 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 arranged on the periphery of the inlet section and the nozzle, and the air chamber is connected with 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 arranged on the rectification column or the distillation tube, and is connected with the air inlet of the venturi ejector through a heat exchanger; the bottom of the kettle is connected with 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 surface of the material.

[0016] In some embodiments, as a preference, the specifications of the Venturi injector 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°.

[0017] In some embodiments, as a preferred embodiment, when the easily coking material is the hydrogenation product of aniline tar, the specifications and dimensions of the Venturi injector are the opening inner diameter of the inlet section: the nozzle inner diameter: the closing inner diameter 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 opening inner diameter of the inlet section: the nozzle inner diameter: the closing inner diameter 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 opening inner diameter of the inlet section: the nozzle inner diameter: the closing inner diameter of the air chamber: 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 opening inner diameter of the inlet section: the nozzle inner diameter: the closing inner diameter of the air chamber: 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 coking material is heavy aromatic hydrocarbons, the specifications and dimensions of the Venturi injector are the opening inner diameter of the inlet section: the nozzle inner diameter: the closing inner diameter of the air chamber: the length of the mixing section: the length of the diffusion section = 32: (2-6): (5-8): (80-180): (1000-1800), and the opening angle of the diffusion section is 12-35°; more preferably, the specifications and dimensions of the Venturi injector are the opening inner diameter of the inlet section: the nozzle inner diameter: the closing inner diameter 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 position of the first distillation plate.

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

[0022] The present invention heats the relatively lighter components evaporated from the kettle through a heat exchanger and returns them to the kettle, replacing the traditional kettle external heating method. The temperature of the lighter components heated by the heat exchanger is 5-10°C higher than the set temperature in the kettle. Compared with the traditional kettle external heating method, the temperature difference is reduced, reducing high-temperature coking; at the same time, the heated lighter components are sprayed into the kettle to play an impact stirring role. Compared with the traditional kettle external heating method, the heat transfer rate is accelerated, further reducing the coking phenomenon caused by the heating of easily coked materials at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of the distillation device of the aniline tar hydrogenation product of the present invention;

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

[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, the distillation device used for separating the 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 includes an inlet section 601, a nozzle 604, a mixing section 602, and a diffusion section 603 which are connected in sequence; 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 605 which is connected with the mixing section; and the annular air chamber is provided with an air inlet 606; the diffusion section 603 is in a tapered tubular type. The top of the distillation column 2 is connected with the condenser 3; the condenser divides the condensed components into two paths through the regulating valve 4, one path is produced to the storage tank 8, and the other path is refluxed into the distillation column 2, and the reflux production ratio is controlled by the regulating valve 4; the lower end of the distillation column is connected with the air inlet 606 of the venturi ejector 6 through the heat exchanger 5; the bottom of the tower kettle 1 is connected with the inlet section 602 of the venturi ejector 6 through the circulating pump 7; the nozzle of the venturi ejector extends into the tower kettle and is located below the liquid surface of the material.

[0030] When in use, the material to be separated is pumped in through 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 in 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 and calculated respectively. When the device is turned on, the tower bottom material is slowly heated by external heating. When there is a fraction 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, so that the light component that is not completely separated in the tower bottom is obtained again by the heat source and effectively separated. Compared with the traditional continuous distillation tower using a reboiler for heating, the heat exchange efficiency is effectively improved, and the feed amount can be further increased to increase the production capacity. At the same time, due to the stirring effect of the Venturi ejector, the heating is uniform, which further reduces the possibility of coking and producing residual oil, and improves 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 air 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 nozzle of the venturi ejector 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 by 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 for heating to provide the heat required for the distillation process. The tower kettle was only required to be insulated without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole 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 materials at the top and the tower kettle residue were collected and weighed separately, of which 20.03kg of the tower top material accounted for 89%, and 0.53kg of the tower kettle residue accounted 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 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: 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 nozzle of the venturi ejector reached 65 m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 3.5 h. 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 materials at the top and the tower bottom residue were collected and weighed respectively, of which 20.81kg of the tower top material accounted for 92.5%, and 0.45kg of the tower bottom residue accounted 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 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: 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 nozzle of the venturi ejector reached 80 m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 3.5 h. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 6°C. The top light component material and the tower bottom residue were collected and weighed, of which 19.9kg of the tower top material accounted for 88.4%, and 0.63kg of the tower bottom residue accounted 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 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: 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 nozzle of the venturi ejector reached 30 m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 4.5 h. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 25°C. The top light component material and the tower bottom residue were collected and weighed, of which the tower 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 the tower bottom residue and loss is high.

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

[0043] 22.5kg of aniline tar hydrogenation product was injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: 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 nozzle of the venturi ejector reached 100m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating, and then the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. At this time, as the temperature increased, due to the high injection linear velocity, a large negative pressure was formed, and the system pressure fluctuated greatly. The gas and liquid in the tower could not reach a stable equilibrium under the disturbance of the venturi ejector injection, and the test was terminated.

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

[0045] Inject 22.5kg of aniline tar hydrogenation product into the 30L conventional distillation tower kettle, adjust the reflux ratio to full reflux, turn on the condenser, and use external electric heating to continuously increase the temperature of the distillation tower kettle under normal pressure until the full reflux state of the top material of the distillation tower is observed. Rapidly adjust the reflux ratio to 1:2 for extraction until no material flows out of the top of the tower, stop heating and record the whole process for 6 hours. During this process, the temperature difference between the electric heating temperature outside the kettle and the material temperature in the tower kettle is 42°C. Collect the light component materials at the top and the residue in the tower kettle and weigh them separately, of which the top material is 18.03kg, accounting for 80.1%, and the residue in the tower kettle is 2.26kg, accounting for 10.1%, and the loss is 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 failure 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 transfer 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 takes less time, and the light component yield is higher.

[0048] Example 4.1 (Vacuum distillation of first-generation biodiesel product)

[0049] 21kg of first-generation biodiesel product was injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 35:3:6:150:800, and the diffusion section opening angle α was 8°. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 65m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:1 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 2.5h. 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, of which the tower 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] 21kg of first-generation biodiesel product was injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 35:4:5.5:150:1000, 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±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 55m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:1 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 2.5h. 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 materials at the top and the tower bottom residue were collected and weighed, of which 18.23kg of the tower top material accounted for 86.8%, and 0.59kg of the tower bottom residue accounted for 2.8%, with a loss of 10.4%.

[0052] Example 4.3

[0053] 21kg of first-generation biodiesel product was injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 35:2.5:6:100:900, 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±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 60m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:1 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 2.5h. 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 top light component material and the tower bottom residue were collected and weighed, of which 18.4kg was the top material, accounting for 87.6%, and 0.41kg was the tower bottom residue, accounting for 2%, with a loss of 10.4%.

[0054] Example 4.4

[0055] 21kg of first-generation biodiesel product was injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 35:3:5.5:120:1300, and the diffusion section opening angle α was 18°. The vacuum pump was turned on to control the vacuum degree in the tower -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 70m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:1 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 2.5h. 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, of which 18.29kg of the tower top material accounted for 87.1%, and 0.46kg of the tower bottom residue accounted for 2.9%, with a loss of 10%.

[0056] Example 4.5

[0057] 21kg of first-generation biodiesel product was injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 35:5:7.5:180:1600, and the diffusion section opening angle α was 30°. The vacuum pump was turned on to control the vacuum degree in the tower to -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 75m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:1 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 2.5h. 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 top light component material and the tower bottom residue were collected and weighed, of which 18.1kg of the tower top material accounted for 86.2%, and 0.65kg of the tower bottom residue accounted for 3.1%, with a loss of 10.7%.

[0058] Comparative Example 4 (Vacuum distillation of biodiesel product in conventional distillation tower)

[0059] Inject 21kg of first-generation biodiesel 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, and use external electric heating to slowly increase the kettle temperature. 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 1:1 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 35℃. Collect the light component materials at the top and the tower kettle residue and weigh them separately. The top material is 16.96kg, accounting for 80.8%, and the tower kettle residue is 1.94kg, accounting for 9.2%, with a loss of 10%.

[0060] Example 5.1 (Vacuum distillation of heavy aromatics)

[0061] 22.5kg of heavy aromatics were injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 32:5:8:100:1700, and the diffusion section opening angle α was 25°. The vacuum pump was turned on to control the vacuum degree in the tower -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 65m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 3h. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 7°C. The top light component material and the tower bottom residue were collected and weighed, of which the tower top material was 21.53kg, accounting for 95.7%, and the tower bottom residue was 0.83kg, accounting for 3.7%, with a loss of 0.6%.

[0062] Example 5.2

[0063] 22.5kg of heavy aromatics were injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 32:5.5:8:80:1500, and the diffusion section opening angle α was 12°. The vacuum pump was turned on to control the vacuum degree in the tower -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 55m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 3h. 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, of which the tower top material was 21.15kg, accounting for 94%, and the tower bottom residue was 0.9kg, accounting for 4%, and the loss was 2%.

[0064] Example 5.3

[0065] 22.5kg of heavy aromatics were injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 32:4:5:110:1200, and the diffusion section opening angle α was 15°. The vacuum pump was turned on to control the vacuum degree in the tower -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 60m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 3h. 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, of which 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] 22.5kg of heavy aromatics were injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 32:3.5:7:150:1000, and the diffusion section opening angle α was 30°. The vacuum pump was turned on to control the vacuum degree in the tower -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 70m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 3h. 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 top light component material and the tower bottom residue were collected and weighed, of which the tower 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] 22.5kg of heavy aromatics were injected into the 30L 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: nozzle inner diameter D2: chamber closing inner diameter D3: mixing section length L1: diffusion section length L2 was 32:2.5:8:180:1750, and the diffusion section opening angle α was 35°. The vacuum pump was turned on to control the vacuum degree in the tower -0.095±0.002MPa. The circulation pump was turned on and the timing was started so that the liquid linear velocity at the nozzle of the venturi ejector reached 75m / s. The top condenser was turned on and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by external heating. When it was observed that the top material of the distillation tower had begun to reflux stably, the heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The tower kettle only did the necessary insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:2 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded as 3h. During this process, the temperature difference between the heat exchanger outlet material and the tower bottom material was measured to be 7°C. The top light component material and the tower bottom residue were collected and weighed, of which the tower top material was 21.26kg, accounting for 94.5%, and the tower bottom residue was 0.98kg, accounting for 4.4%, with a loss of 1.2%.

[0070] Comparative Example 5 (Conventional distillation tower heavy aromatics vacuum distillation)

[0071] Inject 22.5kg of heavy aromatics 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, and slowly increase the kettle temperature through external electric heating. 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 1:2 for production until no material flows out of the production end, stop heating and record the whole process 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℃. Collect the light component materials at the top and the residue in the tower kettle and weigh them separately. The top material is 20.25kg, accounting for 90%, and the residue in the tower kettle is 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 air 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 nozzle of the venturi ejector 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 by 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 heat and provide the heat required for the distillation process. The tower kettle was only required to be insulated without additional heating. The reflux extraction ratio was quickly adjusted to 1:3 for extraction. When no material flowed out from the extraction end, the heating was stopped and the whole process was recorded for 2 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 9°C. The light component material at the top and the tower kettle residue were collected and weighed respectively. The top material was 20.33kg, accounting for 90.4%, and the tower kettle residue was 0.75kg, accounting for 3.3%, with 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 air 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 nozzle of the venturi ejector 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 by 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 heat and provide the heat required for the distillation process. The tower kettle was only required to be insulated without additional heating. The reflux extraction ratio was quickly adjusted to 1:3 for extraction. When no material flowed out from the extraction end, the heating was stopped and the whole process was recorded for 2 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 9.5°C. The light component material at the top and the tower kettle residue were collected and weighed respectively. The top material was 20.15kg, accounting for 89.6%, and the tower kettle residue was 0.81kg, accounting for 3.6%, with 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 air 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 nozzle of the venturi ejector 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 by 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 heat and provide the heat required for the distillation process. The tower kettle was only required to be insulated without additional heating. The reflux extraction ratio was quickly adjusted to 1:3 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded for 2 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 8.5°C. The light component material at the top and the tower kettle residue were collected and weighed separately, of which 19.95kg of the tower top material accounted for 88.7%, and the tower kettle residue accounted for 0.9kg, accounting for 4%, and the loss was 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 air 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 nozzle of the venturi ejector 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 by 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 heat and provide the heat required for the distillation process. The tower kettle was only required to be insulated without additional heating. The reflux extraction ratio was quickly adjusted to 1:3 for extraction. When no material flowed out from the extraction end, the heating was stopped and the whole process was recorded for 2 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 8°C. The light component material at the top and the tower kettle residue were collected and weighed separately. The top material was 20.08kg, accounting for 89.2%, and the tower kettle residue was 0.85kg, accounting for 3.8%, with 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 air chamber closing inner diameter D3: the mixing section length L1: the diffusion section length L2 was 38:2.5:7:190:1750, 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 nozzle of the venturi ejector reached 75 m / s, the top condenser was turned on, and the reflux ratio was adjusted to the full reflux state. The tower kettle material was initially heated slowly by 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 heat and provide the heat required for the distillation process. The tower kettle was only necessary for insulation without additional heating. The reflux extraction ratio was quickly adjusted to 1:3 for extraction until no material flowed out of the extraction end, and the heating was stopped and the whole process was recorded for 2 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 7.5°C. The light component material at the top and the tower kettle residue were collected and weighed separately. The top material was 19.89kg, accounting for 88.4%, and the tower kettle residue was 0.96kg, accounting for 4.3%, with 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 -0.095±0.002MPa, turn on the top condenser, adjust the reflux ratio to full reflux state, and slowly increase the kettle temperature through external electric heating. 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 duration 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 materials at the top and the tower kettle residue and weigh them separately, of which 18.52kg of the top material accounts for 82.3%, and the tower kettle residue accounts for 2.03kg, accounting for 8.7%, and the loss is 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 time required is shorter than that of a traditional distillation tower, and a higher light component yield is achieved, with less heavy component residue.

[0085] Example 7 (Continuous distillation of heavy aromatics)

[0086] Using the Venturi design of Example 5.1 above, the heavy aromatics preheated to 170°C are continuously pumped into the distillation tower through the side line, and the feed amount of heavy aromatics is controlled to 12kg / min. The vacuum pump is turned on to control the vacuum degree in the tower to -0.095±0.002MPa, the top condenser is turned on, and the reflux ratio is adjusted to 1:3 for extraction. When the material with a higher boiling point drops to a liquid level in the tower bottom that exceeds the diffusion port of the Venturi ejector, the circulating pump is turned on so that the linear velocity of the material out of the Venturi ejector nozzle reaches 65m / s. At the same time, the heat exchanger is 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 is measured to be 10°C. The top extraction flow rate is adjusted to balance the bottom extraction flow rate. At this time, the top extraction flow rate reaches 11.55kg / min, and the bottom extraction flow rate reaches 0.38kg / min. It is calculated that the light component accounts for 96.3%, the residual oil accounts for 3.1%, and the loss accounts 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 continued to be heated by electric heating outside the kettle to further separate the light components. 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 was adjusted to a balance with the tower kettle extraction flow rate. 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 components 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 bottom of the tower and the material at the outlet of the heat exchanger 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 of the tower produces 8.99kg / min, and the bottom of the tower produces 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 the above embodiment 4.1, the biodiesel preheated to 190°C is continuously pumped into the distillation tower through the side line, and the amount of biodiesel entering is controlled to 10.8kg / min. The vacuum pump is turned on to control the vacuum degree in the tower to -0.095±0.002MPa, the top condenser is turned on, and the reflux ratio is adjusted to 1:1 for extraction. When the material with a higher boiling point drops to a level in the tower bottom that exceeds the diffusion port of the Venturi ejector, the circulating pump is turned on to make the linear velocity of the material out of the Venturi ejector nozzle reach 65m / s. At the same time, the heat exchanger is 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 is measured to be 9°C. The top extraction flow rate is adjusted to balance the bottom extraction flow rate. At this time, the top extraction flow rate reaches 9.56kg / min, and the bottom extraction flow rate reaches 0.75kg / min. It is calculated that the light component accounts for 88.5%, the residual oil accounts for 6.9%, and the loss accounts for 4.5%.

[0092] Comparative Example 8 (continuous distillation of biodiesel in 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 10.8kg / min. 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 1:1 for extraction. When the material with a higher boiling point dropped into the tower kettle, the material in the tower kettle was continued to be 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 8.7kg / min, and the tower kettle extraction flow rate reached 1.52kg / 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 9kg / min, the temperature difference between the material in the bottom of the tower and the material at the outlet of the heat exchanger was measured to be 39°C. The flow rates of the top and bottom of the tower were adjusted to achieve balance. At this time, the top production was 7.5kg / min, and the bottom production was 1.05kg / 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 amount was controlled to 12kg / min. 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 1:3 for extraction. When the material with a higher boiling point dropped to the liquid level in the tower bottom and exceeded the diffusion port of the Venturi ejector, the circulating pump was turned on to make the material linear velocity of the Venturi ejector nozzle reach 65m / 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 was adjusted to balance the bottom extraction flow rate. At this time, the top extraction flow rate reached 10.92kg / min, and the bottom extraction flow rate reached 0.49kg / 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 (conventional distillation tower continuous distillation of aniline tar hydrogenation product)

[0098] As in Example 9 above, a conventional distillation tower was used, and the aniline tar hydrogenation product preheated to 120°C was pumped 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 continued to be 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 tower top extraction flow rate was adjusted to balance the tower kettle extraction flow rate. At this time, the tower 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 bottom of the tower and the material at the outlet of the heat exchanger was measured to be 42°C. The flow rates of the top and bottom of the tower were adjusted to achieve balance. At this time, the top production was 8.35kg / min, and the bottom production 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] It can be seen from the above-mentioned continuous distillation embodiments of materials prone to coking 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 tower 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 capacity caused by low heat exchange efficiency.

[0101] Example 10 (Batch distillation of aniline tar hydrogenation product in 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, and 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] 22.5kg of aniline tar hydrogenation product was injected into a 30L conventional 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: 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 nozzle of the venturi ejector reached 80m / s. The material in the kettle was initially heated slowly to 270°C by external heating. The material was gradually produced. The heat exchanger 5 was turned on to heat and provide the heat required for the distillation process. The kettle body only did the necessary insulation without additional heating until no material flowed out of the production end. The heating was stopped and the whole process was recorded as 1.7h. During this process, the temperature difference between the material at the heat exchanger outlet and the material in the kettle 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 respectively, of which the light component materials were 21.2kg, accounting for 94%, and the residue in the kettle was 0.63kg, accounting for 1.3%, with a loss of 4.7%.

[0104] It can be seen from the above embodiments that conventional distillation using the fraction separation device of the present invention can also accelerate the mass transfer and heat transfer effects and reduce the temperature difference between the material temperature in the kettle and the material at the outlet of the heat exchanger. At the same time, compared with distillation, the distillation technology does not require reflux, and 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 fraction separation of coking substances, using a distillation tower or a distillation device, wherein the coking substances are heated in a reactor of the distillation tower or the distillation device, and the light components contained therein flow out through the distillation column of the distillation tower or the distillation tube of the distillation device and are then collected; characterized in that: The fraction separation method heats the coking-prone material in the kettle in the following manner: a portion of the components distilled from the kettle are 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, and the material in the kettle is heated by the sprayed refluxed 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, characterized in that 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 circulating pump; the nozzle of the venturi ejector extends into the kettle and is located below the liquid surface of the material; the specifications of the venturi ejector are as follows: 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 = (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, characterized in that: The coking-prone substance is a hydrogenation product of aniline tar, a biodiesel product or heavy aromatics.

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 coking-prone substances; the coking-prone substances are continuously introduced into the kettle of a distillation tower after being preheated, and the vacuum degree in the tower is controlled to be -0.095±0.002MPa.

6. The fraction separation method according to claim 3, characterized in that: When the coking substance is a hydrogenation product of aniline tar, the specifications and dimensions of the Venturi injector are as follows: the opening inner diameter of the inlet section: the inner diameter of the nozzle: the closing inner diameter 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°; when the coking substance is a biodiesel product ... mixing section 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 material 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: (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 opening inner diameter of the inlet section: the inner diameter of the nozzle: the closing inner diameter 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°; when the easily coking substance is a biodiesel product, the specifications and dimensions of the Venturi injector are the opening inner diameter of the inlet section: the inner diameter of the nozzle: the closing inner diameter of the air chamber: 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 aromatics, the specifications and dimensions of the Venturi injector are the opening inner diameter of the inlet section: the inner diameter of the nozzle: the closing inner diameter 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°.

8. A fraction separation device for easily coking substances, characterized in that: The device comprises a rectification tower or a distillation device, a condenser, a venturi ejector, a heat exchanger, and a circulation pump; the rectification tower comprises a tower kettle and a rectification column; the distillation device comprises a distillation kettle and a distillation tube; 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; the outer periphery of the inlet section and the nozzle is provided with a tapered annular air chamber which is connected with the mixing section; the annular air chamber is provided with an air inlet; the diffusion section is a gradually expanding tubular type; when a rectification tower is used, the rectification 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 is refluxed 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 arranged 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 and dimensions 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 tower is used, the place where the air inlet of the venturi ejector is connected to the lower end of the distillation column is located at the position of the first distillation plate.

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