WO2025067193A1 - Venturi separator and use thereof - Google Patents

Abstract

The invention relates to a Venturi separator, characterized in that the Venturi separator comprises a Venturi tube and a liquid phase collecting tube surrounding at least a part of the structure of the Venturi tube. The Venturi tube comprises the following sections which are sequentially communicated: an optional equal-diameter section, a diameter-reducing section, a throat part and a diameter-expanding section. The Venturi separator is provided with a gas phase inlet, a liquid phase inlet, a liquid phase outlet and a gas phase outlet. An opening is formed in the side wall of the diameter-expanding section or the tail end of the diameter-expanding section of the Venturi tube. The opening leads to the liquid phase collecting tube, so that the liquid phase leaves the Venturi tube under the action of centrifugal force and enters the liquid phase collecting tube. The invention also relates to a use of the Venturi separator in a chemical process.

Description

A Venturi separator and its use Technical Field

The invention relates to the field of chemical separation, in particular to the field of petrochemical aromatic separation, and specifically to a venturi separator and use thereof.

Background Art

Chemical separation technology is an important technology in chemical engineering. Whether it is petroleum refining, plastic chemical fiber, hydrometallurgy, isotope separation, or the refining of biological products, the preparation of nanomaterials, flue gas desulfurization, and the production of fertilizers and pesticides, chemical separation technology is indispensable. Most of the raw materials and products in chemical production are mixtures. It is necessary to use the differences in the physical properties of the components in the system or use separation agents to separate and purify the mixture. The commonly used separation methods in chemical production can be divided into two categories: mechanical separation and mass transfer separation. The purpose of the mechanical separation method is simply to separate the phases. As long as a simple mechanical method is used, the two phases can be separated, and there is no material transfer between the two phases; for example, filtration, sedimentation, centrifugal separation, cyclone separation and electrostatic dust removal. The mass transfer separation method is used to separate various homogeneous mixtures, and its characteristic is that mass transfer occurs.

In the prior art, separation devices using the Venturi tube principle have been disclosed, such as wet Venturi dust collectors. Wet dust collectors use the negative pressure of the gas phase to form a uniform water film in the liquid phase. The airflow carrying smoke and dust enters the Venturi separator tangentially, passes through the Venturi throat with a scrubbing liquid spray, and the airflow is rapidly accelerated in the Venturi throat, so that the relative motion of the airflow and the liquid is fully mixed, and the smoke or pollutants and droplets are gathered.

CN104226074A discloses an acid-containing tail gas washing device, which includes a condenser, a venturi tube and a phase separator, wherein the upper end of the venturi is an air inlet, the lower end of the venturi is a discharge port, the air inlet of the venturi is connected to the air outlet of the condenser; and the water inlet pipe is tangentially connected to the upper part of the venturi so that the washing water tangentially enters the upper part of the venturi. However, the acid-containing tail gas washing device has a complex structure, is composed of multiple devices, and occupies a large area.

CN108525443A discloses a venturi decontamination device for gas-liquid treatment, which includes an air inlet pipe, a liquid inlet, a venturi contraction tube, and a venturi expansion tube. The two ends of the venturi contraction tube are respectively connected to the air inlet pipe and the venturi expansion tube. The liquid inlet is arranged at the connection between the venturi contraction tube and the venturi expansion tube.

CN206577612U discloses a venturi mixer with a spiral guide plate at the throat. The spiral guide plate arranged at the throat can be used to force the mainstream fluid entering the throat to rotate, so that the introduced fluid can be introduced more evenly and better mixed with the mainstream fluid after being introduced.

However, the separation system using the venturi tube in the prior art usually requires one or more other devices such as phase separators to be used in series, and the device integration is low, so that the system occupies a large area and has a high investment cost.

To this end, the purpose of the present invention is to provide a Venturi separator suitable for use in chemical production processes, which overcomes the shortcomings of such equipment in the prior art and has the advantages of high structural integration, small footprint, low investment cost, and high separation efficiency.

Summary of the invention

After in-depth research, the inventor surprisingly found that in the multiphase separation method in the chemical process, by combining the venturi tube with the spiral flow of the fluid, the mass transfer separation and mechanical separation between the fluids can be realized simultaneously, that is, the mixing and separation of the multiphase fluids can be realized quickly and efficiently, and by creatively arranging the venturi tube in the liquid phase collection tube and arranging the position where the fluid enters the venturi tube, the spiral flow characteristics of the fluid in the venturi tube can be fully utilized to realize continuous enhanced mixing and enhanced separation between the multiphase fluids, thereby efficiently realizing the mass transfer and separation between the multiphase fluids; in addition, the ingenious combination of the venturi tube and the liquid phase collection tube makes the structure of the venturi separator simple and compact, omits subsequent equipment (such as a phase separator), saves space, and occupies a small area, so that it is suitable for use in combination with various other chemical equipment such as a distillation tower, and reduces the investment cost. In addition, the inventor found that the use of a vortex core tube in the venturi separator of the present invention can quickly obtain a high-speed spiral flow of gas in the venturi tube.

In order to achieve the above-mentioned purpose, according to a first aspect of the present invention, a venturi separator is provided, characterized in that the venturi separator comprises a venturi tube and a liquid phase collecting tube surrounding at least a part of the structure of the venturi tube, the venturi tube comprises the following sections connected in sequence: an optional equal diameter section, a reduced diameter section, a throat and an expanded diameter section, the venturi separator has a gas phase inlet, a liquid phase inlet, a liquid phase outlet and a gas phase outlet, wherein an opening leading to the liquid phase collecting tube is provided on the side wall of the expanded diameter section of the venturi tube or at the end of the expanded diameter section, so that the liquid phase leaves the venturi tube and enters the liquid phase collecting tube under the action of centrifugal force.

According to a second aspect of the present invention, the present invention also relates to the use of the Venturi separator of the first aspect, which is used for multiphase separation in chemical processes, especially for integration into organic compounds. Gas-liquid separation.

The venturi separator according to the present invention has the following advantages: its structural design is ingenious, the arrangement of its components is reasonable and compact, it can be operated continuously, has high separation efficiency, occupies a small area, saves space, has low investment cost, and can be used in combination with other devices such as distillation towers in chemical production.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings in the specification are used to illustrate the technical solutions of the present invention and constitute a part of the specification, but do not constitute a limitation of the present invention. Among them:

FIG. 1 shows a schematic diagram of an aromatics extraction system involved in Example 1 of the present invention.

FIG. 2 shows a schematic structural diagram of a Venturi separator according to an embodiment of the present invention used in Example 1. FIG.

Description of Reference Numerals

In Figure 1, 101: aromatics extraction distillation tower; 102: venturi separator; 103: reflux drum; 104: condenser; 1: aromatics feed inlet; 2: extraction solvent inlet; 3: tower top gas phase outlet; 4: washed gas outlet; 5: reflux drum inlet; 6: washing liquid inlet; 7: raffinate oil product outlet; 8: washing liquid outlet; 9: tower bottom liquid phase outlet; 10: side line inlet; 11: tower top gas phase inlet; 12: water phase outlet.

In FIG2 , 13: vortex core tube; 14: venturi tube; 15: washing liquid input tube; 16: liquid phase collecting tube; 17: top opening of the expanded diameter section; 18: open tube.

DETAILED DESCRIPTION

The specific embodiments of the present application are described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the technical solutions of the present invention, and are not intended to limit the present invention.

Any specific numerical value (including the endpoint of the numerical range) disclosed in this specification is not limited to the exact value of the numerical value, but should be understood to also cover values close to the exact value, such as all possible values within the range of ±5% of the exact value. In addition, for the disclosed numerical range, the endpoint values of the range, the endpoint values and the specific point values in the range, and the specific point values can be arbitrarily combined to obtain one or more new numerical ranges, and these new numerical ranges should also be regarded as specifically disclosed in this specification.

Unless otherwise specified, the terms used in this specification have the same meaning as those used by persons skilled in the art. If a term is defined in this specification and its definition is different from the general understanding in the art, the definition in this specification shall prevail.

In this application, except for the contents explicitly stated, any matters or items not mentioned are directly applicable to those known in the art without any changes. Moreover, any embodiment described herein can be freely combined with one or more other embodiments described herein, and the technical solutions or technical ideas formed thereby are regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new contents not disclosed or anticipated herein, unless a person skilled in the art considers that the combination is obviously unreasonable.

Unless explicitly stated otherwise, throughout the specification and claims, the term “comprise” or its synonyms such as “comprising” or “containing”, etc., will be understood to include stated elements or components but not to exclude other elements or components.

In the description of the present invention, it is necessary to understand that the orientation terms such as "length", "angle", "above", "below", "vertical", "upright", "horizontal", "top", "bottom", "inside", "outside", "tangential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

In the specification of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

According to a first aspect of the present invention, the present invention provides a venturi separator, characterized in that the venturi separator comprises a venturi tube and a liquid phase collecting tube surrounding at least a portion of the structure of the venturi tube, the venturi tube comprises the following sections connected in sequence: an expanded diameter section, a throat, a reduced diameter section and an optional equal diameter section, the venturi separator has a gas phase inlet, a liquid phase inlet, a liquid phase outlet and a gas phase outlet, wherein an opening is provided on the side wall of the expanded diameter section of the venturi tube or at the end of the expanded diameter section and leads to the liquid phase collecting tube, so that the liquid phase leaves the venturi tube and enters the liquid phase collecting tube under the action of centrifugal force.

According to an implementation of the first aspect above, the Venturi separator is placed vertically. The gas phase inlet and liquid phase inlet thereof are optionally connected to other devices so as to continuously process the gas and liquid from other devices, and the liquid phase outlet and gas phase outlet are also optionally connected to other devices for subsequent processing or storage.

According to an embodiment of the first aspect above, the venturi tube optionally includes a constant diameter section, which is connected to the reduced diameter section (if any), and can be used to connect to other equipment or install auxiliary equipment therein, such as a vortex core tube; the throat is the connecting part of the reduced diameter section and the expanded diameter section, and has the smallest diameter in the venturi tube, and it can also be a section of constant diameter pipe connecting the reduced diameter section and the expanded diameter section, and an opening for gas and liquid to leave the venturi tube is provided in the expanded diameter section or at the top of the expanded diameter section, and the optional constant diameter section, reduced diameter section, throat and expanded diameter section are connected and arranged from bottom to top.

According to an implementation of the first aspect, a liquid phase injection port is provided on the tube wall in the reduced diameter section of the venturi tube, that is, the liquid phase input from the liquid phase inlet of the venturi separator is injected into the venturi tube in the reduced diameter section of the venturi tube so as to contact and mix with the spirally flowing gas in the venturi tube. Since the gas flows in the reduced diameter section in a spiral manner at high speed in the venturi tube, as the diameter in the reduced diameter section becomes smaller and smaller, the angular velocity of the spiral flow of the gas becomes larger and larger. Therefore, when the liquid phase is injected into the venturi tube in the reduced diameter section, it flows and mixes with the spirally flowing gas, the degree of disturbance of the liquid becomes stronger and stronger, and the gas-liquid mixing becomes more and more sufficient. Therefore, the more sufficient the mass transfer between the gas and the liquid, the better the separation effect. The liquid phase injection port on the tube wall of the venturi tube can be at any position of the reduced diameter section. Preferably, the distance between the position of the liquid phase injection port and the throat is 1/10-2/3 of the length of the reduced diameter section, and more preferably, the distance between the position of the liquid phase injection port and the throat is 1/8-1/2 of the length of the reduced diameter section.

According to an embodiment of the first aspect above, a nozzle may be provided at the liquid phase injection port on the tube wall of the venturi tube to spray the liquid phase into the gas in the venturi tube in the form of small droplets to accelerate the mixing of gas and liquid. The injection flow rate and speed of the liquid phase can be adjusted by those skilled in the art according to actual needs and the gas flow rate and flow rate. The injection direction of the nozzle can be in any direction, preferably at an angle of less than 90° to the gas flow direction at the location of the liquid phase injection port, more preferably at an angle of less than 60°, more preferably at an angle of less than 30°, for example, less than 15°, and more preferably in the same direction as the gas flow direction.

According to an implementation of the first aspect, the liquid phase collecting pipe surrounds at least a portion of the structure of the venturi pipe at the periphery of the venturi pipe, for example, at least surrounds the side wall of the expanded diameter section of the venturi pipe or the opening provided at the end of the expanded diameter section. The liquid phase collecting pipe extends downward and can surround the expanded diameter section of the venturi pipe, and can even surround the throat and the reduced diameter section, and can even Surrounding the entire venturi tube. Preferably, the venturi separator of the present invention comprises a liquid phase collecting tube and a venturi tube arranged in the liquid phase collecting tube. If the liquid phase collecting tube surrounds the entire venturi tube, then the infusion pipeline for conveying the liquid phase connected to the liquid phase injection port on the tube wall of the venturi tube needs to pass through the liquid phase collecting tube wall. At this time, the liquid phase inlet of the venturi separator is connected to the liquid phase injection port on the tube wall of the venturi tube via the infusion pipeline passing through the liquid phase collecting tube wall, wherein the angle between the infusion pipeline and the conical generatrix of the reduced diameter section of the venturi tube located below the infusion pipeline can be 10-90°, preferably 30-80°, for example 40°, 50°, 60° or 70°.

According to an embodiment of the first aspect above, the top of the liquid phase collecting tube is closed, but an open tube for discharging the gas phase of the venturi separator is provided, the upper end outlet of the open tube forms the gas phase outlet of the venturi separator, and the open tube passes downward through the top of the liquid phase collecting tube and extends to the end of the expanded diameter section of the venturi tube. If an opening for the liquid phase to leave the venturi tube is provided on the side wall of the expanded diameter section of the venturi tube, then the open tube is connected to the end of the expanded diameter section of the venturi tube, and optionally a liquid phase outlet is also provided between the lower end of the open tube and the end of the expanded diameter section of the venturi tube for the liquid that is not discharged at the outlet of the expanded diameter section to be discharged here, if the opening for the liquid phase to be discharged from the venturi tube is provided at the end of the expanded diameter section of the venturi tube, then the lower end of the open tube and the end of the expanded diameter section of the venturi tube are completely or partially spaced apart to form an opening for the liquid phase to be discharged from the venturi tube, so that the opening is a continuous or discontinuous annular opening, and the height of the opening can be adjusted by raising and lowering the open tube. The height of the opening can be changed within a certain range according to the liquid phase flow rate, as long as it can satisfy the requirement that almost all the liquid phase leaves the venturi tube under the action of centrifugal force and enters the liquid phase collecting tube, and can prevent a significant amount of gas from entering the liquid phase collecting tube, for example, the height of the opening is less than 10 cm, for example, less than 5 cm.

According to an embodiment of the first aspect above, the diameter of the open tube may be slightly larger than the diameter of the end opening of the expanded section, for example, the diameter of the open tube is less than 5% larger than the diameter of the end opening of the expanded section, and preferably, the diameter of the open tube is the same as the diameter of the end opening of the expanded section.

According to an embodiment of the first aspect, the venturi separator further comprises a device for causing the gas to enter the venturi tube in a spiral flow manner or a device for causing the gas to enter the venturi tube tangentially, so that the gas flows upward in a spiral form in the venturi tube. The device is arranged at the entrance of the reduced diameter section of the venturi tube, or at the equal diameter section of the venturi tube. The device for causing the gas to generate spiral flow in the venturi tube may be a commonly used device in the art, such as a vortex core tube.

According to an embodiment of the first aspect above, the device for making the gas flow in a spiral manner in the Venturi tube is a vortex core tube, and a spiral guide vane is arranged inside the vortex core tube. The vortex core tube is arranged at the entrance of the reduced diameter section of the Venturi tube or in the equal diameter section of the Venturi tube, and the bottom inlet of the vortex core tube is formed as the gas phase inlet of the Venturi separator.

According to an implementation of the first aspect, the number of the vortex core tubes can be selected according to actual needs (such as gas flow rate, etc.), and can be one or more. If multiple vortex core tubes are used, the multiple vortex core tubes can be arranged in parallel.

According to an implementation of the first aspect, the diameter of the liquid phase collecting pipe is larger than the maximum diameter of the venturi tube disposed therein, and those skilled in the art may select it according to actual needs and site conditions. Preferably, the diameter of the liquid phase collecting pipe is 30% larger than the maximum diameter of the venturi tube disposed therein, preferably 20% larger, for example 10% or 5% larger.

According to an implementation of the first aspect above, a structure for guiding the spiral flow of gas is provided on the inner wall of the optional equal diameter section, reduced diameter section, throat and expanded diameter section of the venturi tube, so that the gas flow or gas-liquid flow can flow spirally upward or downward along the inner wall of the venturi tube. The structure can be selected from swirl blades or spiral guide vanes, which can increase the tangential velocity of the fluid, avoid the wall-adhering effect of the fluid, strengthen the contact between the gas and the liquid, and further improve the separation efficiency of the venturi separator. The spiral angle φ of the swirl blade or spiral guide vane can be selected by a person skilled in the art according to actual conditions, and adjusted according to the change in the diameter of the venturi tube.

According to a preferred embodiment, the swirl blade or spiral guide vane can be a single- or multi-start swirl blade or a single- or multi-start spiral guide vane with a thread head number n (n is a positive integer greater than or equal to 1). If the swirl blade or spiral guide vane is multi-start, and the pitch of the multi-start swirl blade or multi-start spiral guide vane (n>1) is the same as the pitch of the single-start swirl blade or single-start spiral guide vane (n=1), since the helix lead angle φ of the multi-start spiral guide vane is approximately n times the helix lead angle φ of the single-start spiral guide vane, the multi-start spiral guide vane can better guide the fluid on the inner wall of the Venturi tube, and can significantly reduce the pressure loss of the Venturi separator.

According to an implementation of the first aspect above, in the Venturi separator, the volume flow ratio of the gas phase to the liquid phase can vary within a wide range, for example, 70-2500:1. Preferably it is 200-1100:1; the inlet gas velocity of the Venturi separator is 1m/s~40m/s, preferably 5m/s~35m/s; the pressure loss of the Venturi separator is below 20kPa, for example 0.1kPa~10kPa, preferably 0.2kPa~5kPa; the absolute pressure of the liquid phase at the liquid phase injection port is above 170kPa, preferably 180kPa~1500kPa, preferably 200~1000kPa, more preferably 250~700kPa.

According to an embodiment of the first aspect above, in the Venturi separator, the bottom of the liquid phase collecting tube is connected to the liquid phase outlet of the Venturi separator through a liquid discharge pipe, wherein a liquid seal is provided at the bottom of the liquid phase collecting tube to prevent gas from entering the liquid discharge pipe.

According to a second aspect of the present invention, the present invention also relates to the use of the Venturi separator for liquid-gas separation or liquid-gas purification.

According to one embodiment of the second aspect above, the venturi separator is used for stripping separation of liquid components in the liquid phase or for washing separation or extractive separation of gas components in the gas phase, for example, using a washing liquid to elute the solvent contained in the gas from the top of a distillation tower.

The liquid phase removal rate obtained by using the venturi separator according to the present invention can reach more than 82%, preferably 90% to 99.9%, and the liquid phase separation accuracy is 1μm to 10μm, wherein the above-mentioned liquid phase removal rate = the weight of the liquid phase entering the liquid phase collection pipe/the total weight of the liquid phase injected into the venturi tube.

The beneficial effects of the technical solution of the present invention are further illustrated by the following examples, but are by no means intended to limit the scope of the present invention.

In these examples, the venturi separator of the present invention is integrated into an aromatic extraction system to separate the extraction solvent entrained in the overhead gas of the aromatic extraction distillation column.

The aromatics raw material used in the aromatics extraction system involved in the embodiments and comparative examples is the C6-C7 fraction of reformed oil, and the mass fraction of aromatics in the aromatics raw material is 65%.

The sulfolane used was a chemical reagent purchased from Inokai Technology Co., Ltd. Unless otherwise specified, the other reagents were obtained through commercial channels.

Example 1

In this embodiment, an aromatic extraction system as shown in FIG. 1 and a venturi separator as shown in FIG. 2 are used. The system includes an aromatic extraction distillation tower 101 , a venturi separator 102 , a reflux drum 103 and a condenser 104 .

The aromatics extraction distillation tower 101 includes an aromatics feed inlet 1, an extraction solvent inlet 2, a side line inlet 10, a bottom liquid phase outlet 9 and a top gas phase outlet 3; the venturi separator 102 includes Gas phase inlet 11, liquid phase (washing water in this embodiment) inlet 6, washing liquid (washing water in this embodiment) outlet 8 and gas phase (washed gas in this embodiment) outlet 4; the reflux tank 103 includes a reflux tank inlet 5, a water phase outlet 12 and an oil phase outlet 7.

The top gas phase outlet 3 of the aromatics extractive distillation tower 101 is connected to the gas phase inlet 11 of the venturi separator 102; the washing liquid (washing water in this embodiment) outlet 8 of the venturi separator 102 is connected to the side line inlet 10 of the aromatics extractive distillation tower 101, and the gas phase (washed gas) outlet 4 of the venturi separator 102 is connected to the inlet 5 of the reflux tank 103; the water phase outlet 12 of the reflux tank 103 is connected to the liquid phase (washing water in this embodiment) inlet 6 of the venturi separator 102; the oil phase outlet 7 of the reflux tank 103 is formed as the raffinate oil product outlet of the system; the condenser 104 is arranged between the gas phase (washed gas) outlet 4 of the venturi separator 102 and the inlet 5 of the reflux tank;

The venturi separator 102 includes a liquid phase collecting pipe 16 arranged vertically and a venturi tube 14 arranged vertically in the liquid phase collecting pipe 16, and a liquid phase injection port (also referred to as a washing liquid injection port in this embodiment) is provided at the upper 1/3 of the reduced diameter section length near the throat of the venturi tube 14; the venturi separator includes the venturi tube 14, the vortex core tube 13, the washing liquid input pipe 15 and the liquid phase collecting pipe 16; the washed gas outlet 4 of the venturi separator 102 is arranged at the top of the liquid phase collecting pipe 16; the liquid phase inlet 6 of the venturi separator 102 is connected to the washing liquid injection port below the throat of the venturi tube 14 through the washing liquid input pipe 15; the bottom inlet of the venturi tube is formed as the gas phase inlet of the venturi separator or is connected to the gas phase inlet of the venturi separator, and the washed gas outlet of the venturi separator is connected to the top outlet of the venturi tube through the opening pipe 18; the venturi tube 14 includes from bottom to top according to The washing liquid inlet pipe 15 passes through the wall of the liquid phase collecting pipe 16 and is connected to the washing liquid injection port on the reduced diameter section of the venturi tube 14, and is close to the throat of the venturi tube; the top of the liquid phase collecting pipe 16 is provided with an open pipe 18, the top opening of the open pipe 18 can also be used as the washed gas outlet 4 of the venturi separator 102, and the bottom opening of the open pipe 18 passes downward through the top of the liquid phase collecting pipe and extends to The liquid phase collecting tube 16 is spaced apart from the top of the expanded diameter section of the venturi tube 14 to form an opening 17; the diameter of the opening tube 18 is the same as the diameter of the top opening of the expanded diameter section; the angle between the washing liquid input tube 15 and the axis of the venturi tube 14 is 90°; the vortex core tube 13 is arranged in the equal diameter section of the venturi tube, and the bottom inlet of the vortex core tube 13 can also be used as the gas phase inlet 11 of the venturi separator 102; the number of the vortex core tubes is one.

The raw material containing aromatic hydrocarbons enters the aromatic hydrocarbon extraction distillation tower 101 through the aromatic hydrocarbon raw material inlet 1, and the solvent Sulfolane enters the aromatic extraction distillation tower 101 through the extraction solvent inlet 2, and the raw material containing aromatics contacts with sulfolane in the aromatic extraction distillation tower 101 to extract aromatics; the top gas of the aromatic extraction distillation tower 101 is discharged from the top gas phase outlet 3, passes through the vortex core tube 13 of the venturi separator 102 to form an upward vortex flow gas, and enters the venturi tube 14; the water phase from the reflux tank 103 is sprayed into the venturi tube 14 through the washing liquid input pipe 15; the vortex flow gas contacts with the washing liquid, and is subjected to water washing and removal treatment, and the gas and the washing liquid continue to flow upward along the wall of the venturi tube to obtain a washing liquid. The post-washing gas and the washing liquid containing solvent gradually gather the washing liquid containing solvent outside the vortex under the action of centrifugal force in the expansion section. The washing liquid containing solvent is discharged from the opening between the bottom end of the open pipe 18 and the top of the expansion section under the action of centrifugal force, enters the liquid phase collection pipe 16, and reaches the washing liquid outlet 8 at the bottom of the venturi separator under the action of gravity and is discharged. The washed gas is discharged from the washed gas outlet 4, passes through the condenser 104, enters the reflux tank 103 for treatment, and the residual oil is discharged from the oil phase outlet 7 of the reflux tank 103; the liquid phase discharged from the washing liquid outlet 8 returns to the aromatic extraction distillation tower 101 for recycling. The liquid phase removal rate at the gas phase outlet of the top of the venturi separator 102 is 99.8%, and the specific operating conditions of the aromatic extraction system are shown in Table 1.

Example 2

The method is the same as that in Example 1, except that the venturi tube in this embodiment does not include a vortex core tube, but adopts tangential inlet relative to the inner wall of the venturi tube inlet, wherein the inlet gas velocity is 40 m/s. The liquid phase removal rate at the top gas phase outlet of the venturi separator 102 is 83%, and the specific operating conditions of the aromatics extraction system are shown in Table 1.

Example 3

The method is the same as that in Example 1, except that the volume flow ratio of the gas phase to the washing liquid in this embodiment is 1200:1; the liquid phase removal rate at the top gas phase outlet of the venturi separator 102 is 99.8%, and the specific operating conditions of the aromatics extraction system are shown in Table 1.

Example 4

The method is the same as that in Example 1, except that the inlet gas velocity at the inlet of the venturi tube in this embodiment is 40m/s, and the absolute pressure at the liquid phase injection port is 180kPa; the liquid phase removal rate at the top gas phase outlet of the venturi separator 102 is 95%, and the specific operating conditions of the aromatics extraction system are shown in Table 1.

Example 5

The method is the same as that in Example 1, except that in this embodiment, the distance between the liquid phase injection port and the throat of the venturi tube is 2/3 of the length of the reduced diameter section, and the absolute pressure of the washing liquid at the liquid phase injection port is 500 kPa; the liquid phase removal rate at the top gas phase outlet of the venturi separator 102 is 99.8%, and the specific operating conditions of the aromatics extraction system are shown in Table 1.

Example 6

The method is the same as that in Example 1, except that in this embodiment, the liquid phase injection port is set at the throat of the venturi tube, the volume flow ratio of the gas phase to the washing liquid is 1200, and the absolute pressure of the washing liquid at the liquid phase injection port is 250 kPa; the liquid phase removal rate at the top gas phase outlet of the venturi separator 102 is 95%, and the specific operating conditions of the aromatics extraction system are shown in Table 1.

Table 1

Comparative Example 1

The conventional process shown in Figure 1 is used, but a non-aromatic distillation column (NA column) is used instead of A venturi separator, i.e., an extractive distillation tower (ED tower) and a non-aromatic distillation tower (NA tower) are connected in series to recover trace solvents in the ED tower top gas. The raw materials, solvents and solvent ratios used are the same as those in Example 1. The operating conditions of this comparative example 1 are shown in Table 2.

Table 2

Comparative Example 2

The process shown in Figure 1 is adopted, but a non-aromatic distillation section is used instead of a Venturi separator, that is, a non-aromatic distillation section is set in the upper section of the extractive distillation tower (ED tower) to recover trace solvents in the raffinate oil. The raw materials, solvents and solvent ratios are the same as those in Example 1. The operating conditions are shown in Table 3.

Table 3

Test Example 1

The components of the raffinate oil products obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were analyzed. The composition of the raffinate oil was analyzed by ASTM D-6536 and GGBM-04-2005 standard methods for aromatic content and solvent content. The product composition is shown in Table 4.

Table 4

According to the data in Table 4, the aromatic extraction system including the venturi separator according to the present invention significantly increases the content of non-aromatic hydrocarbons in the raffinate oil, significantly reduces the content of aromatic hydrocarbons in the raffinate oil, and further improves the quality and yield of aromatic hydrocarbon products in the extract; it illustrates that the venturi separator according to the present invention can be combined with an aromatic extraction distillation tower, so that the aromatic extraction distillation tower can efficiently separate organic compounds such as aromatic hydrocarbons in the gas phase; and the venturi separator according to the present invention occupies a small area and does not require additional heating, further reducing energy consumption.

By comparing Example 1 with Comparative Example 1, it can be seen that the solvent (cyclopentane) content in the raffinate oil product obtained by the aromatic extraction system using the venturi separator of the present invention can reach a level equivalent to that of Comparative Example 1, but the addition of the water phase from the venturi separator in the aromatic extraction distillation tower of the present invention improves the solvent selectivity, so that the aromatic content in the raffinate oil is lower, and there is no need for a reboiler at the bottom of the NA tower and a reflux at the top of the tower, thereby saving energy consumption.

By comparing Example 1 with Comparative Example 2, it can be seen that the system of the present invention avoids the reflux of non-aromatic raffinate oil into the aromatic extraction distillation tower, increases the content of non-aromatic hydrocarbons in the raffinate oil, reduces the content of aromatic hydrocarbons in the raffinate oil, and further increases the yield of aromatic hydrocarbons in the extract; at the same time, the effect of removing the solvent in the raffinate oil is improved.

By comparing Example 1 with Example 2, it can be seen that when the Venturi separator of the present invention uses a vortex core tube, compared with using a tangential air intake method, the liquid phase removal rate is higher and the residual solvent content in the raffinate oil product is significantly lower.

By comparing Example 1 with Example 3, it can be seen that under the volume flow ratio range of the top gas phase/washing liquid within the preferred range of the present invention, the solvent content in the raffinate oil product is lower.

By comparing Example 1 with Example 4, it can be seen that, under the range of the gas velocity at the venturi tube inlet and the absolute pressure at the liquid phase injection port of the present invention, the liquid phase removal rate is significantly higher and the residual solvent content in the raffinate oil product is lower.

By comparing Example 1 with Example 5, it can be seen that at the inlet of the venturi tube of the present invention Under the range of gas velocity and absolute pressure of the liquid phase injection port, when the distance between the liquid phase injection port and the throat is 2/3 of the length of the reduction section, the pressure drop caused by the injection of the liquid phase is significantly higher than the pressure drop caused by the liquid phase when the distance between the liquid phase injection port and the throat is 1/3 of the length of the reduction section. A higher pressure is required at the top of the extractive distillation tower to maintain the same gas velocity, but the separation effects of the two are equivalent, indicating that by injecting the washing liquid at a position within the preferred range of the present invention, the extractive distillation tower can maintain optimal operating conditions.

By comparing Example 1 with Example 6, it can be seen that, within the range of the gas velocity at the inlet of the venturi tube of the present invention and the absolute pressure of the liquid phase injection port, the separation effect produced by the liquid phase being injected at the reduced diameter section is much higher than the separation effect produced by the liquid phase being injected at the throat. This is because when the liquid phase is injected at the throat, it does not experience the reduced diameter section, resulting in insufficient gas-liquid mixing, and the ratio of the volume flow rates of the gas phase to the washing liquid is large, resulting in less solvent in the gas being washed by the liquid phase, and therefore the residual solvent content in the raffinate oil product is higher.

By comparing Example 1 with Example 6, it can be seen that, within the range of the gas velocity at the inlet of the venturi tube of the present invention and the absolute pressure of the liquid phase injection port, since the liquid phase is injected at a lower position in the reduced diameter section, less liquid phase can be injected when treating the gas at the same speed, resulting in a lower gas treatment efficiency and a higher solvent residual content in the raffinate oil product.

The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims (16)

A venturi separator, characterized in that the venturi separator comprises a venturi tube and a liquid phase collecting tube surrounding at least a part of the structure of the venturi tube, the venturi tube comprises the following sections connected in sequence: an optional equal diameter section, a reduced diameter section, a throat and an expanded diameter section, the venturi separator has a gas phase inlet, a liquid phase inlet, a liquid phase outlet and a gas phase outlet, wherein an opening is provided on the side wall of the expanded diameter section of the venturi tube or at the end of the expanded diameter section, and the opening leads to the liquid phase collecting tube. The venturi separator according to claim 1 is characterized in that the liquid phase injection port on the tube wall of the venturi tube is arranged in the reduced diameter section of the venturi tube, preferably, the distance between the position of the liquid phase injection port and the throat is 1/10-2/3 of the length of the reduced diameter section, and more preferably, the distance between the position of the liquid phase injection port and the throat is 1/6-1/2 of the length of the reduced diameter section. The venturi separator according to any one of claims 1-2 is characterized in that a nozzle can be provided at the liquid phase injection port on the tube wall of the venturi tube. The venturi separator according to any one of claims 1 to 3 is characterized in that the liquid phase inlet of the venturi separator is connected to the liquid phase injection port on the wall of the venturi tube via a liquid infusion pipeline that optionally passes through the liquid phase collection tube wall, wherein the angle between the liquid infusion pipeline and the conical generatrix of the reduced diameter section of the venturi tube located below the liquid infusion pipeline is 10-90°, preferably 30-80°, and preferably, the liquid phase enters the venturi tube through the liquid phase injection port in a tangential direction relative to the horizontal circumference of the venturi tube. The venturi separator according to any one of claims 1 to 4 is characterized in that the top of the liquid phase collecting tube is closed and is provided with an open tube for discharging the gas phase of the venturi separator, the upper end outlet of the open tube forming the gas phase outlet of the venturi separator, the open tube passes through the top of the liquid phase collecting tube and extends downward to the end of the expanded diameter section of the venturi tube, and optionally a gap is provided between the lower end of the open tube and the end of the expanded diameter section of the venturi tube to form a liquid phase outlet. The Venturi separator according to any one of claims 1 to 5 is characterized in that the diameter of the open tube is greater than or equal to the diameter of the end opening of the expanded section, and preferably the diameter of the open tube is equal to the diameter of the end opening of the expanded section. The Venturi separator according to any one of claims 1 to 6 is characterized in that the diameter of the liquid phase collecting pipe is larger than the maximum diameter of the Venturi tube arranged therein, preferably, the diameter of the liquid phase collecting pipe is 30% larger than the maximum diameter of the Venturi tube arranged therein, such as 10% or 5%. The Venturi separator according to any one of claims 1 to 7, characterized in that the Venturi separator further comprises a device for causing the gas to enter the Venturi tube in a spiral flow manner or a device for causing the gas to enter the Venturi tube tangentially. The Venturi separator according to any one of claims 1 to 8 is characterized in that the device for making the gas flow in a spiral manner in the Venturi tube is a vortex core tube, a spiral guide vane is arranged inside the vortex core tube, the vortex core tube is arranged at the entrance of the reduced diameter section of the Venturi tube or in the equal diameter section of the Venturi tube, and the bottom inlet of the vortex core tube is formed as the gas phase inlet of the Venturi separator or is connected to the gas phase inlet of the Venturi separator. The Venturi separator according to any one of claims 1 to 9 is characterized in that the number of the vortex core tubes is one or more, preferably multiple, and the multiple vortex core tubes are arranged in parallel. The Venturi separator according to any one of claims 1 to 10 is characterized in that a structure for guiding the spiral flow of gas is provided on the inner wall of any of the equal-diameter section, reduced-diameter section, throat and expanded-diameter section of the Venturi tube; preferably, the structure is selected from swirl blades or spiral guide vanes. The Venturi separator according to claim 11 is characterized in that the swirl blade or spiral guide vane is selected from a single-start swirl blade or a single-start spiral guide vane or a multi-start swirl blade or a multi-start spiral guide vane having a number of thread heads n, wherein n is a positive integer greater than 1. The venturi separator according to claims 1-11 is characterized in that the bottom of the liquid phase collecting pipe is connected to the liquid discharge pipe, wherein a liquid seal is provided at the bottom of the liquid phase collecting pipe. Use of the Venturi separator according to any one of claims 1 to 13, which is used for multiphase separation in chemical processes, preferably for gas stripping separation of liquid components and washing separation or extraction separation of gas components. According to the use according to claim 14, the venturi separator is used to elute the liquid component in the gas phase by means of a washing liquid, the volume flow ratio of the gas phase to the washing liquid is 70-2500:1, preferably 200-1100:1, and the obtained liquid phase removal rate can be 82% to 99.9%, preferably 90 to 99.9%. According to the use according to claim 14, the inlet gas velocity of the Venturi separator is 1m/s to 40m/s, preferably 5m/s to 35m/s; the pressure loss of the Venturi separator is 0.1kPa to 10kPa, preferably 0.2kPa to 5kPa; and/or the absolute pressure of the liquid phase at the liquid phase injection port is 180kPa to 1500kPa.