A vertical flow single-kettle extractor and a regulating method, a multi-stage countercurrent extraction system and a control regulating method thereof

Abstract

The application discloses a vertical flow single-kettle extractor and a regulating method, a multi-stage countercurrent extraction system and a control and regulating method connected in series. The extractor is a vertical single-kettle structure, and a combination of a mixing cylinder, a flow guide cylinder and a container outer shell is formed in the inside, and further comprises a variable-speed stirrer, phase clarification functional fillers, two-phase liquid inlet ports and two-phase liquid outlet ports. The variable-speed stirrer drives two-phase materials to fully blend in the mixing chamber in the push flow mode and forms stable booster delivery, the blended materials enter the annular clarification chamber in the horizontal radial flow mode after turning back to realize efficient layering, and the booster pressure head is reserved for discharging. A plurality of single-kettle extractors are connected in series in the countercurrent mass transfer mode, and components such as inter-stage connection and regulation are configured, and a countercurrent extraction system supporting pressure extraction is formed. The system can be operated according to a specific method, and can have the advantages of efficient and lossless whole-line start-stop, online large-scale adjustment of processing capacity, whole-line adjustment of two-phase flow ratio, convenient start-up and material distribution, convenient shutdown and separate quality discharge and the like.

Description

Technical Field

[0001] This invention belongs to the field of liquid-liquid extraction and separation technology, specifically relating to a vertical flow single-pot extractor and its adjustment method, and a multi-stage countercurrent extraction system connected in series therewith and its control and adjustment method. Background Technology

[0002] Liquid-liquid extraction is an indispensable process in chemical, hydrometallurgical, pharmaceutical, and environmental protection fields. It is widely implemented using box-type or tank-type mixing and clarifying devices. A single-stage device consists of two chambers: a mixing chamber and a clarifying chamber. The oil and water phases are lifted upwards in the mixing chamber by an agitator and overflow into the clarifying chamber. Subsequently, they undergo gravity overflow along a relatively long horizontal path to achieve phase stratification. To overcome the flow deviation and short-circuiting phenomena associated with gravity overflow, damping components are often installed to buffer and distribute the flow. However, the existing lift-overflow flow field significantly restricts the functionality of extraction equipment, resulting in the following inherent defects:

[0003] Firstly, the clarification chamber's effect is weak, thus reducing efficiency and forcing a longer extraction stage. The mixing chamber loses its pressure head after upward overflow, forcing the clarification chamber to rely on gravity overflow for discharge. To limit the power consumption corresponding to the lifting height, the height of the mixing chamber must be controlled. To ensure continuous and stable flow of both phases during countercurrent extraction, the height of the clarification chamber must be less than that of the mixing chamber. Therefore, the clarification chamber can only employ shallow gravity overflow, making secondary stratification after two-phase discharge more likely.

[0004] Secondly, the two-phase flow ratio is difficult to adjust in countercurrent extraction. Liquid-liquid extraction involves significant mass transfer between the two phases, resulting in a substantial increase or decrease in the volume of one phase compared to the other. This necessitates adaptive adjustment of the two-phase flow ratio, especially when the feed concentration fluctuates. However, in a lift-overflow flow field, the lighter phase discharge has no head, making it impossible to obtain fluid dynamics signals for automated control. Furthermore, any adjustment of the flow rate of one phase inevitably causes fluctuations in the other phase. Consequently, fluctuations in the two-phase volume ratio in countercurrent extraction can easily extend into multi-stage cascading oscillations, making it difficult to stabilize after startup. Especially during shutdown, due to material stratification in the mixing chamber, phase impacts after restarting are unavoidable.

[0005] Third, it is difficult to further optimize the extraction efficiency, operating power consumption, and online volume. Most of them can only adopt a rectangular box tank structure, which makes it difficult to overcome the disadvantages such as poor pressure resistance, poor sealing, difficulty in corrosion prevention and temperature control, and large footprint, thus restricting the application and expansion of liquid-liquid extraction process.

[0006] The aforementioned shortcomings of traditional mixer-clarifiers limit their effectiveness in multi-stage, pressurized, solvent-volatile, and flexible control scenarios. While numerous technical efforts have been made to overcome these drawbacks, fundamental improvements have not been achieved. For example, CN 202006039 U employs a dual-mixing-chamber gradient stirring design with dual reflux pipes, improving extraction efficiency and objectively providing potential for adjusting the single-unit throughput. CN 218774342 U achieves equipment compactness and improves sealing performance through a concentric nested structure (inner cylinder mixing + outer cylinder clarification). CN 223263453 U, to enhance phase separation and reduce clarification chamber volume, incorporates a two-phase mixing and lifting process followed by overflow into the two-phase interface zone of the clarification chamber, enhancing the two-phase clarification effect by adding spatial components. CN 220071639 U, based on traditional CMS-type mixer-clarifiers, adopts an external heavy phase weir and regulating tank structure, improving the function of online adjustment of heavy phase flow rate. Although the aforementioned technologies have improved separation efficiency, sealing performance, and online adjustment to varying degrees, they have not changed the "lift-overflow" flow field configuration. They are unable to improve the problems of flexible adjustment of the two-phase flow rate and volume ratio, large online volume, and insufficient single-stage mass transfer efficiency in multi-stage countercurrent extraction processes, and cannot solve the phase ratio impact after shutdown and restart. Summary of the Invention

[0007] Objective of the Invention: This invention achieves an integrated innovation of a single-reactor extraction device. The vertical single-reactor structure ensures the reliability of the equipment in terms of pressure resistance, sealing, corrosion resistance, and temperature control, resulting in higher extraction efficiency and lower energy consumption. It also allows for large-scale online adjustment of the throughput by pressurizing both phases in the stratified system. Based on this single-reactor system, a novel multi-stage countercurrent extraction system is constructed to achieve superior countercurrent extraction performance, including but not limited to improving single-stage efficiency, enabling independent adjustment of the flow rates of the two phases after stratification, allowing for significant online adjustment of the throughput, and enabling quick recovery to steady-state operation after shutdown and restart in a simple and efficient manner. Furthermore, the solutions to the above problems are integrated into a systematic operating method.

[0008] The technical essence of this invention is to construct a flow field of downflow mixing and vertical direct current clarification within a single extraction device, including: a central mixing chamber employing multi-paddle coordinated downflow mixing and providing a stable pressurization head; a clarification chamber outside the central mixing chamber employing horizontal radial flow distribution and gravity vertical flow stratification, operating in a fully filled mode, which improves the clarification efficiency of the two phases while ensuring that both phases are pressurized before discharge after stratification; coupled with a phase interface monitoring instrument, allowing direct online adjustment of the volume and flow rate of both phases; realizing direct switching between internal circulation and continuous discharge of a single unit; and further enabling new functions in the countercurrent extraction system such as rapid material feeding and start-up, rapid balance adjustment, non-destructive shutdown, and shock-free quick restart.

[0009] Based on the above technical essence, the present invention provides a vertical flow single-pot extraction machine for liquid-liquid extraction of oil and water phases, the main structure of which includes:

[0010] The outer shell of the vertical vessel is assembled and welded from the lower head, the cylindrical body, the upper head, and the top flange;

[0011] The mixing cylinder is coaxially disposed on the upper part of the outer casing;

[0012] The guide tube is a coaxial outer sleeve at the bottom of the mixing cylinder, installed on the lower end cap of the outer shell, and guides the fluid to the outer space between the mixing cylinder and the guide tube;

[0013] The components of the mixing cylinder include: a top end cap with a vertical cylinder section and a flange, a sealing ring, an inner cylinder section, a propulsion chamber and a diversion cone section, and a balance gas interface is provided on the top end cap;

[0014] The flange of the top end cap is paired with the top flange of the outer shell and together clamps the sealing ring, thereby forming a pressure isolation seal for the internal space of the extractor and enabling the extractor to be designed and manufactured according to pressure vessel specifications.

[0015] After the top end cap, mixing cylinder, and guide cylinder are assembled and connected with the outer shell, the internal space of the outer shell is divided into a mixing chamber formed by the interior of the mixing cylinder and the guide cylinder, and an annular clarification chamber formed by the mixing cylinder, the guide cylinder, and the outer shell.

[0016] A variable speed mixer is installed on the top of the mixing cylinder. Its drive shaft is a multi-paddle mixing shaft that extends into the mixing chamber. The multi-paddle mixing shaft is provided with at least one mixing paddle and at least one propulsion paddle located at the tail end of the multi-paddle mixing shaft. The mixing paddle is used to drive the two-phase materials to mix uniformly, and the propulsion paddle is used to generate an axial downward thrust flow to transport the blended materials.

[0017] The light phase inlet and the heavy phase inlet are located on the same horizontal plane of the vertical cylinder section of the top head;

[0018] The light phase outlet and the heavy phase outlet are respectively located at the upper and lower parts of the outer shell, and are respectively provided with internal drainage pipes for drawing out the stratified light phase and heavy phase from the top and bottom of the clarification chamber, respectively. The light phase drives the gas phase out at the top of the clarification chamber to form a fully filled clarification chamber during operation.

[0019] A phase interface sensor is installed on the upper end cap of the outer shell and extends into the clarification chamber to monitor the level of the two-phase working interface in the clarification chamber. The upper and lower parts of the interface level are the light phase and heavy phase clarification spaces, respectively, and light phase packing and heavy phase packing with clarification functions are installed thereon.

[0020] Based on the spatial combination of the mixing cylinder, the guide cylinder and the outer shell, and the combined action of the variable speed agitator, the two-phase media form a downward flow mixing-vertical direct flow clarification flow field in a single container space. This drives the material to be mixed by the downward flow in the mixing chamber, then guided back by the guide cylinder and enter the clarification chamber in a horizontal radial flow. Subsequently, stratification is achieved in the vertical direction, and both the light and heavy phases after stratification are pressurized and discharged.

[0021] Furthermore, the vertical flow single-pot extractor has a circulation outlet near the height of the two-phase working interface of the outer shell and a circulation return outlet at the feed height of the mixing cylinder. The two are connected by an internal circulation valve assembly consisting of pipelines and switching valves. This allows for stopping the two-phase feed in single-stage operation and simultaneously connecting the mixing chamber and the clarification chamber to maintain the distribution and mass transfer balance of the two phases within the equipment.

[0022] Furthermore, the nominal diameter D and height H of the shell of the vertical flow single-pot extractor are determined according to the single-machine residence time required for mass transfer separation, and the diameter-to-height ratio D / H is 0.7~1; based on the decreasing interfacial tension value and density difference between the two phases, the single-machine residence time is determined in the range of 6~30 min, thereby determining the volume of the shell, calculating the nominal diameter D, and then back-calculating to determine H.

[0023] Furthermore, in the components of the mixing cylinder of this vertical flow single-pot extractor, the sealing ring is welded to the inner cylinder section, and the inner cylinder section is connected to the propulsion chamber and the guide cone section in sequence through an inverted conical variable diameter section; the dimensions of the above components include: the diameter d and depth h of the propulsion chamber are determined by the extraction working flow rate, and the length-to-diameter ratio h / d is 0.45~1.5; specifically, according to the extraction two-phase interfacial tension value and density difference value from small to large, the downward flow velocity of the mixed liquid in the propulsion chamber is selected in the range of 0.05~0.4 m / s, and the rounded value of d is calculated. The inner cylinder diameter d1 and the propeller penetration length H2 of the mixing cylinder are determined based on the mixing residence time of the two-phase media in the mixing chamber, which is within the range of 1.5 to 7.5 min. The following conditions must be met: the mixing chamber volume is calculated based on the mixing residence time; then, the rounded value of d1 is selected within the range of 2.2d ≤ d1 ≤ (0.4 to 0.7) D, according to the ratio of the interfacial tension and density difference between the extracted two phases from smallest to largest; and H2 is determined within the range of 0.24 to 0.72 times the height H of the outer shell. The bottom angle α of the inverted conical variable diameter section is selected within the range of 20° to 50°, according to the ratio of the interfacial tension and density difference between the extracted two phases from largest to smallest, and the penetration depth h1 of the propeller upper edge from the propulsion chamber inlet is 0.12 to 0.5 times d. The cone angle β of the drainage cone section is determined within the range of 5° to 55°, according to the overflow pipe length and the ratio of the two-phase density difference from smallest to largest.

[0024] Furthermore, the inner diameter d2 of the guide tube of the vertical flow single-pot extractor is determined to be within the range of 0.4 to 1.1 times the inner cylinder section diameter d1 of the mixing cylinder; and several horizontally distributed clarification chamber material outlets are provided at the top of the guide tube, wherein the line height H3 is designed according to the height of the two-phase interface under working conditions and is the same as the median detection depth of the phase interface sensor.

[0025] Furthermore, the fluid delivery direction of the propeller at the lower end of the variable speed agitator of this vertical flow single-pot extractor is vertically downward.

[0026] Furthermore, the vertical distance H1 between the opening height of the light phase inlet and the heavy phase inlet of the vertical flow single-pot extractor and the flange sealing surface of the top head is 0.15 to 0.4 times the inner cylinder section diameter d1 of the mixing cylinder.

[0027] Furthermore, the opening of the circulation reflux port of this vertical flow single-pot extractor is at the same horizontal height as the light phase inlet and the heavy phase inlet.

[0028] Furthermore, the range of the phase interface sensor of this vertical flow single-pot extractor corresponds to the range in which the height of the light and heavy phase interface can be effectively adjusted under working conditions, and the adjustment range is 0.1 to 0.3 times the height H of the outer shell.

[0029] Furthermore, the light phase packing and heavy phase packing installed in the light phase and heavy phase clarification spaces of this vertical flow single-pot extractor have the same surface polarity as the heterogeneous emulsion droplets in their respective spaces and similar surface energies.

[0030] Furthermore, the vertical flow single-pot extractor is also equipped with a liquid level sensor on the top cap for monitoring the working liquid level inside the mixing cylinder.

[0031] Furthermore, the extractor distinguishes between two working pressure modes—low pressure and pressurized mode—based on the influence of working pressure on the mass transfer dynamics of the system. The low-pressure extraction mode is suitable for extraction applications where the working pressure does not exceed 0.3 MPa; the pressurized extraction mode is suitable for extraction applications where pressurization can promote interphase mass transfer, and the working pressure is not lower than 0.3 MPa and not higher than 3.2 MPa.

[0032] In the low-pressure extraction mode, the rotational speed n of the variable speed stirrer is 150~400 r / min, and the matching relationship between the diameter d of the propulsion chamber and the working flow rate Q of the extractor is as follows:

[0033] When the diameter d of the propulsion chamber is 70~190 mm, the working flow rate Q is 1.2~6 m³ / h;

[0034] When the diameter d of the propulsion chamber is 190~250 mm, the working flow rate Q is 6~15 m³ / h;

[0035] When the diameter d of the propulsion chamber is 250~325 mm, the working flow rate Q is 15~36 m³ / h;

[0036] When the diameter d of the propulsion chamber is 340~400 mm, the working flow rate Q is 36~75 m³ / h;

[0037] When the diameter d of the propulsion chamber is 400~475 mm, the working flow rate Q is 75~150 m³ / h;

[0038] When the diameter d of the propulsion chamber is 475~550 mm, the working flow rate Q is 150~220 m³ / h.

[0039] Furthermore, in the pressurized extraction mode, the rotational speed n of the variable speed stirrer is 150~600 r / min, and when n is 400~600 r / min, the downward flow rate of the mixture in the propulsion chamber is 1.5~3.5 times that in the low-pressure extraction mode.

[0040] The adjustment method of the above-mentioned vertical flow single-pot extractor of the present invention for realizing material feeding and start-up includes the following steps:

[0041] a) Open the valve on the internal circulation valve assembly to connect the mixing chamber and the clarification chamber;

[0042] b) Close the outlet pipes of the light phase and the heavy phase to prevent the discharge of both phases, and inject the heavy phase into the mixing chamber first and then the light phase according to the preset two-phase ratio, and then stop the two-phase feeding.

[0043] c) Start the variable speed mixer and adjust it to the preset speed;

[0044] d) Close the valves on the internal circulation pipe valve assembly to isolate the mixing chamber and the clarification chamber, and at the same time start the continuous feeding of the two phases according to the preset flow rate, and simultaneously open the light phase outlet and the heavy phase outlet to achieve continuous feeding and discharging of the light and heavy phases.

[0045] The adjustment method of the above-mentioned vertical flow single-pot extractor of the present invention, so as to achieve shock-free temporary start-up and shutdown, includes the following steps:

[0046] During a temporary shutdown, while stopping the two-phase feed and discharge, the internal circulation valve assembly is opened to create a material circulation between the mixing chamber and the clarification chamber inside the extractor, thereby maintaining the internal two-phase distribution and concentration balance.

[0047] During restart, the two-phase inlet and outlet are restored, and the internal circulation valve assembly is closed simultaneously to achieve a shock-free restart of the extractor.

[0048] The adjustment method of the vertical flow single-tank extractor of the present invention adjusts the processing capacity by actively increasing or decreasing the rotation speed of the variable speed stirrer to continuously increase or decrease the downflow flow generated by the propeller.

[0049] The adjustment method of the vertical flow single-pot extractor of the present invention adjusts the speed of the variable speed agitator in the opposite direction based on the deviation direction of the working liquid level signal of the mixing chamber detected by the liquid level sensor, thereby changing the discharge flow rate of the propeller. The variable speed agitator is then restored to the set speed after the working liquid level signal of the liquid level sensor returns to the set value, thereby achieving the adjustment to suppress the error of the inlet and outlet flow rates.

[0050] The adjustment method of the vertical flow single-pot extractor of the present invention, after fluctuations in the flow rate of the raw liquid or the concentration of the mass transfer component, resets the control height of the phase interface sensor to meet the two-phase balance required for the process to meet the standard. The outlet flow rates of the light phase outlet and the heavy phase outlet are adjusted slightly in opposite directions according to the increase or decrease of the two phase volumes, so that the two-phase interface in the equipment is stabilized at the newly set target height, thereby realizing the reverse adjustment of reconstructing the two-phase balance.

[0051] The adjustment method of the vertical flow single-pot extractor of the present invention achieves online adjustment of the two-phase flow ratio through the following steps, specifically including:

[0052] a) Adjust the inlet flow rate of one or two phases that need to be changed, and simultaneously change the corresponding outlet flow rate;

[0053] b) Based on the signals from the phase interface sensor, monitor the movement of the two-phase interface;

[0054] c) When the interface moves to the height of the adjustment target, continue to fine-tune the outlet flow rate and stabilize the monitoring signal of the phase interface sensor at the target height.

[0055] d) Maintain the operating parameters at the current state to lock in the new two-phase flow ratio.

[0056] The multi-stage countercurrent extraction system of the present invention consists of two or more stages of vertical flow single-pot extractors as described above, used for liquid-liquid countercurrent mass transfer. The system selects models of the same size, or combines 2 to 4 models of different specifications according to the volume change of the two phases during the extraction process and the mass transfer stages. The countercurrent extraction system also includes the following system-level functional components:

[0057] The main pressure balance pipe for the entire line is connected to the top of each extraction machine and is equipped with a switch valve; this is used to inject inert gas at a preset pressure into each extraction machine and achieve pressure balance of each machine.

[0058] The interstage connection and control pipeline assembly connects the light phase outlet of the previous stage extractor to the light phase inlet of the next stage extractor, and connects the heavy phase outlet of the next stage extractor to the heavy phase inlet of the previous stage extractor. Each connecting pipeline is equipped with a pressure gauge and a flow regulating valve for comparative adjustment of the flow rates of the two phases or one phase between stages.

[0059] The whole line connection and interstage isolation components include a heavy phase discharge main pipe connecting the bottom of the clarification chamber of each stage of the extractor and a light phase overflow main pipe connecting the feed height of the mixing chamber of each stage, as well as control valves installed between each main pipe and the extractor; to enable the mixing chamber and clarification chamber of each stage of the extractor to become a multi-chamber communication state, or to switch to an interstage isolation state where each stage of the extractor becomes a separate concentration unit;

[0060] The bypass reflux pipeline assembly connects the final stage raffinate outlet to the primary feed liquid inlet; it is used to return the raffinate phase to the feed liquid inlet for bypass circulation of the entire line when the system is started up or scheduled to be shut down, while the extractor maintains countercurrent mass transfer until the raffinate concentration reaches the standard.

[0061] By configuring the above system components and coordinating with the individual control of each extraction stage, the system can perform specific line-wide control operations.

[0062] The control and adjustment method of the multi-stage countercurrent extraction system of the present invention, based on the above-mentioned extraction system, and through manipulation and adjustment of the system-level functional components and each stage of the extraction machine, enables the system to possess the following unique functional operating modes, including:

[0063] The system comprises the following functions: Line standby and material spreading actions, based on the line pressure balance main pipe and coordinated with individual machine adjustments at each stage, for rapid material spreading of two-phase materials at preset pressures; Stage isolation and internal circulation actions, based on the line pressure balance main pipe and line connection and interstage isolation components and coordinated with individual machine adjustments at each stage, for quickly establishing two-phase distribution within the system after line standby and material spreading actions, and achieving two-phase material spreading for the entire line; Rare phase line bypass circulation action, based on bypass reflux pipeline components and line connection and interstage isolation components and coordinated with individual machine adjustments at each stage, for achieving the required rare phase concentration and preparing for shutdown after stage isolation and internal circulation actions; Continuous countercurrent extraction action, based on interstage connection and control pipeline components and coordinated with individual machine adjustments at each stage, for normal operation after the rare phase line bypass circulation action; and Line synchronous discharge action, based on internal circulation valve components and interstage connection and control pipeline components and coordinated with individual machine adjustments at each stage, for line shutdown and non-rinsing graded discharge after temporary line shutdown actions.

[0064] Alternatively, the control and adjustment method of the above-mentioned countercurrent extraction system of the present invention, based on the above-mentioned extraction system and the adjustment method of each stage of single extraction machine to realize shock-free temporary start-up and shutdown, so that the system has the following unique temporary stop and shock-free restart operation modes:

[0065] The temporary shutdown of the entire production line, based on the internal circulation valve assembly and the overall line connection and interstage isolation assembly, and in coordination with the adjustment of individual machines at each stage, is used for temporary interruption of production after continuous countercurrent extraction. The shockless restart of the entire production line, based on the internal circulation valve assembly and the interstage connection and control pipeline assembly, and in coordination with the adjustment of individual machines at each stage, is used to directly restore the production operation to continuous countercurrent extraction after the temporary shutdown of the entire production line.

[0066] Furthermore, the control and regulation method of the countercurrent extraction system described in this invention is based on the above-mentioned extraction system and single extractor to achieve adjustment of processing capacity, suppression of inlet and outlet flow errors, and adaptation to fluctuations in the two-phase working interface, or a combination of such methods, so that the system can achieve a unique online balance regulation function, including three online adjustments: adjustment to adapt to short-term fluctuations, adjustment of the two-phase flow ratio, and elimination of cumulative errors.

[0067] The short-term fluctuation adjustment function is that when the feed flow rate or target component concentration changes in the short term, based on the control of the interstage connection and control pipeline components, and in coordination with the adjustment of each stage of the single machine to adapt to fluctuations, the stability of the two-phase interface level inside each stage of the extractor is maintained under the reconstructed two-phase equilibrium, so as to realize the fluctuation compensation adjustment of the whole system line.

[0068] The two-phase flow ratio adjustment function is that, when it is necessary to change the light and heavy two-phase flow ratio in the system, it is based on the control of the inter-stage connection and control pipeline components, and coordinates the online adjustment of the two-phase flow ratio of each stage unit to achieve the adjustment and stabilization of the two-phase flow ratio of the whole line.

[0069] The cumulative error elimination function is that when it is necessary to restore the working liquid level of a certain stage or several stages of the extractor, it is based on the adjustment of the inlet and outlet flow rate of each stage to suppress the error, and coordinates the control of the inter-stage connection and control pipeline components to achieve the suppression of cumulative error of the entire line.

[0070] Beneficial effects: Compared with traditional equipment, it has the following significant advantages directly brought about by structural innovation:

[0071] 1. Higher single-unit efficiency: This extractor replaces the traditional "lift-overflow" mode with a "downward flow mixing-vertical direct current clarification" flow field. The multi-paddle downward flow reduces backmixing and makes mass transfer more uniform and sufficient. The vertical direct current stratification in the annular clarification chamber with two-phase pressure head and higher elevation results in higher clarification efficiency. The combination of these two advantages not only improves the extraction efficiency of each stage of extraction, but also significantly reduces operating energy consumption.

[0072] 2. Wider range of applications: The extraction machine adopts a vertical container configuration, which is compact and reliable with good sealing performance. It can be designed and manufactured according to pressure vessel specifications, making it easy to achieve corrosion prevention and temperature control. It is also easy to scale up, greatly expanding the application range of liquid-liquid extraction.

[0073] 3. More flexible single-unit adjustment: Both light and heavy phases of the extractor can be pressurized for discharge, and independent flow rate adjustment is supported on the discharge pipeline. Combined with the structure of the extractor, a unique adjustment method is adopted to achieve independent, precise and quick material spreading and start-up, impact-free temporary start-up and shutdown control, processing capacity adjustment, change of two-phase flow ratio, suppression of cumulative error, and online adjustment to adapt to the concentration fluctuation of mass transfer components.

[0074] 4. Superior overall line control performance: Based on the countercurrent extraction system built by the vertical flow single-pot extractor, the system components are set up and coordinated with the individual machine control of each extraction stage to perform specific overall line control operations. This includes overall line standby and material feeding actions, isolation and internal circulation actions of each stage, overall line bypass circulation actions of the raffinate phase, continuous countercurrent extraction actions, overall line temporary shutdown actions, overall line shock-free restart actions, overall line synchronous discharge actions, as well as online adjustment to adapt to short-term fluctuations, two-phase flow ratio adjustment and cumulative error elimination. Attached Figure Description

[0075] Figure 1 Schematic diagram of the overall structure and components of a vertical flow single-pot extractor Figure 1 ;

[0076] Figure 2 This is a schematic diagram of the overall structure and components of the mixing cylinder of a vertical flow single-pot extractor;

[0077] Figure 3 Schematic diagram of the overall structure and components of a vertical flow single-pot extractor Figure 2 ;

[0078] Figure 4 This is an exploded view of the structural dimensions of a vertical flow single-pot extractor.

[0079] Figure 5 This is a schematic diagram of the installation of the internal circulation pipe valve assembly of a vertical flow single-pot extractor.

[0080] Figure 6 This is a schematic diagram of a countercurrent extraction system using the light phase as the extractant.

[0081] The components include: 1. Mixing cylinder; 2. Guide cylinder; 3. Outer shell; 4. Variable speed agitator; 5. Light phase inlet; 6. Heavy phase inlet; 7. Light phase outlet; 8. Heavy phase outlet; 9. Phase interface sensor; 10. Top end cap; 11. Sealing ring; 12. Inner cylinder section; 13. Propulsion chamber; 14. Drainage cone section; 15. Multi-paddle stirring shaft; 16. Mixing paddle; 17. Propulsion paddle; 18. Light phase packing; 19. Heavy phase packing; 20. Clarification chamber distribution port; 21. Circulation outlet; 22. Circulation return port; 23. Internal circulation pipe valve assembly; 24. Liquid level sensor; 25. Pressure gauge; 26. Flow regulating valve; 27. Heavy phase discharge main; 28. Light phase overflow main. Detailed Implementation

[0082] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0083] I. Vertical Flow Single-Stage Extractor and Adjustment Method

[0084] The overall structure and components of the extraction machine of this invention are as follows: Figure 1 and Figure 3 As shown. The overall structure of the mixing cylinder and its components of the vertical flow single-pot extractor is as follows. Figure 2 As shown in the diagram. A diagram illustrating the important dimensions of the extraction machine is shown below. Figure 4 As shown. The installation of the internal circulation pipe valve assembly connecting the mixing chamber and the clarifier chamber is as follows. Figure 5 As shown.

[0085] The vertical flow single-pot extractor of the present invention is used for mass transfer separation operations such as extraction, washing, or component displacement between oil and water phases, and is implemented using the following technical means:

[0086] The extractor is a single vertical container. After the two phase materials are fully mixed in the mixing cylinder 1 by the downward push flow, they are guided back by the guide cylinder 2 and enter the annular clarification chamber formed by the extractor and the outer shell 3 in a horizontal radial flow, and finally achieve efficient stratification in the vertical direction.

[0087] The overall structure of the vertical flow single-pot extractor designed to achieve the above-mentioned technical effects is as follows: Figure 1As shown. The main structural component is a vertical container shell 3 with a nominal diameter D, which is welded together from a lower end cap, a cylinder, an upper end cap, and a top flange. The height of the top flange and the bottom end of the lower end cap is H, which is the height of the shell 3. The mixing cylinder 1 is coaxially arranged on the upper part of the shell 3. The guide cylinder 2 is a coaxial outer sleeve at the lower part of the mixing cylinder 1, installed on the lower end cap of the shell 3, and guides the fluid to the outer space between the mixing cylinder 1 and the guide cylinder 2. The extractor also includes a variable speed stirrer 4 and light phase inlet pipes 5 and 6 installed on the mixing cylinder 1, a light phase outlet pipe 7 and a heavy phase outlet pipe 8 installed on the shell 3, and a phase interface sensor 9 for monitoring the level of the oil-water two-phase working interface.

[0088] The components of the mixing cylinder 1 include a top head 10 with a vertical cylinder section and a flange, a sealing ring 11, an inner cylinder section 12, a propulsion chamber 13, and a drainage cone section 14. Crucially, a balancing gas inlet is provided on the top head 10.

[0089] The flange of the top end cap 10 mates with the top flange of the outer shell 3, and together they clamp the sealing ring 11, forming a pressure-isolated seal for the internal space of the equipment, while ensuring that the extraction machine can be designed and manufactured according to pressure vessel specifications. After the top end cap 10, mixing cylinder 1, and guide cylinder 2 are assembled and connected to the outer shell 3, the internal space of the outer shell 3 is divided into a mixing chamber inside the mixing cylinder 1 and the guide cylinder 2, and an annular clarification chamber formed between the mixing cylinder 1, the guide cylinder 2, and the outer shell 3. The mixing chamber is the space where the two-phase materials undergo blending, mass transfer, and momentum transfer, while the clarification chamber is the space where the mixed liquid achieves two-phase stratification and discharge.

[0090] A variable-speed stirrer 4 is installed at the top of the mixing cylinder 1, and its drive shaft is a multi-paddle stirring shaft 15 that extends into the mixing chamber. The multi-paddle stirring shaft 15 is equipped with at least one mixing paddle 16 located in the upper middle part and at least one propeller paddle 17 located at the lower end. The main function of the mixing paddle 16 is to drive the two-phase materials to mix uniformly. The propeller paddle 17 is used to generate a stable axial downward thrust flow, continuously transporting the mixture and providing a pressure head, laying the foundation for stable and adjustable two-phase flow rates during countercurrent extraction.

[0091] Light phase inlet 5 and light phase inlet 6 are located on the same horizontal plane of the top end cap 10 cylinder section, and are used to introduce the light phase and heavy phase to be transferred, respectively.

[0092] In operation, the two-phase interface divides the clarification chamber into upper and lower parts: the upper part is the light phase clarification space, and the lower part is the heavy phase clarification space. To enhance the clarification effect, light phase packing 18 and heavy phase packing 19 with coalescing function are installed in the light and heavy phase clarification spaces, respectively. The light phase outlet 7 and heavy phase outlet 8 are respectively located at the upper and lower parts of the outer shell 3, and are equipped with internal drainage pipes to draw out the extracted two-phase media from the top and bottom layers, respectively, and to ensure that the clarification chamber operates under pressure when full of liquid.

[0093] The interface sensor 9 is installed on the upper end cap of the housing 3 for real-time monitoring of the interface level.

[0094] Multiple clarification chamber distribution ports 20 are provided at the top of the guide tube 2, which are horizontally distributed along the circumference. Their function is to allow the blended emulsion from the mixing chamber to enter the annular clarification chamber in a uniform horizontal radial flow at the oil-water interface, so as to provide uniform distribution for subsequent vertical direct current stratification.

[0095] In the technical solution of the vertical flow single-pot extractor of the present invention, the overall structure and the dimensional design of key components follow the inherent technical logic of the equipment to ensure that its "downward flow mixing - vertical direct flow clarification" flow field can achieve optimized operation for different processing objects and process requirements. The specific dimensional design of the key components is as follows:

[0096] The nominal diameter D and height H of the outer casing 3 are parameters that determine the single-unit processing flow rate Q. Their dimensions are determined based on the residence time required for mass transfer separation within the equipment. Specifically, the diameter-to-height ratio D / H is designed to be within the range of 0.7 to 1.0. First, based on the physical properties of the two phases to be processed, primarily interfacial tension and density difference, the single-unit residence time is selected within the range of 6 to 30 minutes, according to these two indicators from largest to smallest. Based on this, the required working volume of the outer casing 3 is calculated. This working volume is the product of the sum of the feed two-phase flow rates Q (within the same unit) and the residence time t. Then, based on the D / H value, a preliminary value for the diameter D can be calculated from the effective volume and rounded to the nominal diameter. Finally, the height H of the equipment is calculated.

[0097] The components of mixing cylinder 1 are as follows Figure 2As shown, the sealing ring 11 is welded to the inner cylinder section 12. The inner cylinder section 12 is connected to the propulsion chamber 13 and the guide cone section 14 in sequence through an inverted conical diameter-changing section. The reasonable structural dimensions are the basis for its efficient mixing and stable conveying functions. The diameter d and depth h of the propulsion chamber 13 are determined by the extraction working flow rate. Based on the increasing interfacial tension and density difference between the two phases, the downward flow velocity v of the mixture in the propulsion chamber is reasonably selected within the range of 0.05~0.4 m / s. This avoids strong emulsification and reduces the retention of the light phase. The required cross-sectional area of ​​the propulsion chamber is calculated using the ratio Q / v of the sum of the two phase flow rates Q to the flow velocity v. Then, the diameter d is calculated and rounded based on the cross-sectional area. Its length-to-diameter ratio h / d is controlled within the range of 0.45~1.5.

[0098] The inner cylinder diameter d1 of mixing cylinder 1 and the insertion length H2 of propeller 17 are determined based on a mixing residence time of 1.5~7.5 min for the two-phase medium in mixing cylinder 1. The calculation method is consistent with the calculation of the working volume of outer shell 3, specifically satisfying the following: Based on the increasing interfacial tension and density difference between the two phases, a rounded value of d1 is selected within the range of 2.2d ≤ d1 ≤ (0.4~0.7)D. Simultaneously, the insertion length H2 of the propeller is determined within the range of 0.24~0.72 times the total height H of outer shell 3. Once the inner cylinder diameter d1 of mixing cylinder 1 and the insertion length H2 of propeller 17 are determined, the volume of the mixing chamber is essentially determined.

[0099] The inverted conical variable-diameter section connecting the inner cylinder section 12 and the propulsion chamber 13 has a base angle α selected within the range of 20° to 50° based on the decreasing interfacial tension and density difference between the two phases. It must also ensure that the penetration depth h1 of the upper edge of the propeller 17 from the inlet of the propulsion chamber 13 is 0.12 to 0.5 times the diameter d. The cone angle β of the drainage cone section 14 below it is determined within the range of 5° to 55° based on the overflow pipe length and the increasing density difference between the two phases.

[0100] In addition to the above, the extraction machine of the present invention also includes the following configuration:

[0101] The balance gas interface opened on the top end cap 10 is used to connect to the external balance gas. It is a key interface for realizing pressurized operation and pressure balance of the equipment, and provides the basic conditions for the extraction machine to operate under pressure conditions.

[0102] The guide tube 2, serving as the coaxial outer sleeve at the bottom of the mixing tube 1, requires careful consideration of its inner diameter d2 for both fluid guidance and distribution. Ideally, it should be a rounded value within the range of 0.4 to 1.1 times the diameter d1 of the inner section of the mixing tube. The centerline height H3 of the top clarifier outlet 20 coincides with the height of the two-phase interface under operating conditions and is also the same as the midpoint of the range of the phase interface sensor 9.

[0103] The variable speed agitator 4 operates at a speed n of 150~600 r / min. The fluid delivery direction of the propeller 17 at its lower end is vertically downwards. At the selected speed, the flow rate of the propeller 17 is ensured to match the volume of the mixing zone, meeting the required residence time for the two-phase fluids in the mixing chamber. The purpose of these two requirements is to allow sufficient time for mass transfer in the blend, while also providing a stable output flow rate and pressurization. Simultaneously, the speed of the variable speed agitator 4 and the working liquid level in the clarification chamber are positively correlated with the delivery flow rate.

[0104] The opening height H1 of the light phase inlet pipe 5, the light phase inlet pipe 6, and the circulation return port 22 is the vertical distance from its axis to the flange sealing surface of the top head 10. In order to ensure that the mixing chamber is mixed immediately upon feeding within a limited space, H1 is 0.15 to 0.4 times the diameter d1 of the inner section of the mixing cylinder.

[0105] In general, the core structural dimensions of the vertical flow single-pot extractor, including volume parameters such as the diameter d of the propulsion chamber, the diameter d1 of the inner section of the mixing cylinder, the insertion length H2 of the propeller, and the diameter D of the outer shell, are optimized in coupling with the flow parameters of the mixing slurry 16 and the propeller 17, specifically conforming to the physical properties of the two phases to be processed. The overall technical logic is as follows: For two-phase systems with large density differences and interfacial tension, on the one hand, the difficulty of mass transfer in two-phase blending increases, so d1 should be increased accordingly, and the insertion length H2 of the propeller should be increased, i.e., increasing the residence time of the two phases in the mixing chamber, while simultaneously increasing the diameter of the mixing slurry 16; alternatively, a larger d1 / d can be added, i.e., appropriately reducing d and increasing the rotational speed n, to prevent the heavy phase from escaping before sufficient mixing, while simultaneously reducing the diameter of the propeller 17. On the other hand, since the two phases are easily separated and clarified, the diameter D of the outer shell 3 can be reduced, i.e., reducing the volume of the clarification chamber and the residence time of the material through the single machine. For two-phase systems with small density differences and interfacial tension, the opposite technical selection is adopted. The aforementioned adjustment of key dimensions of the equipment allows the core structural parameters of the vertical flow single-pot extractor to be flexibly and efficiently matched with the media properties of the extraction system. This is the core technical relationship that enables the present invention to achieve good versatility and high efficiency.

[0106] Furthermore, the range of the interface sensor 9 is not a fixed value, but is set according to the actual production control requirements. The adjustment range is 0.1 to 0.3 times H to ensure sufficient monitoring and adjustment capabilities for the interface position.

[0107] The light-phase packing 18 and heavy-phase packing 19, installed in the light and heavy-phase clarification chambers, are crucial components for improving separation efficiency. On one hand, their surface polarity is the same as that of the heterogeneous emulsion droplets in the clarification chamber, and their surface energies are similar. This characteristic allows the heterogeneous emulsion droplets to more easily wet, remain, aggregate, and eventually coalesce and grow before being removed, thus enhancing the clarification effect. On the other hand, the uniform resistance provided by the packing promotes the formation of a uniform radial flow in the horizontal direction after the two-phase fluids enter the clarification chamber.

[0108] In addition, a liquid level sensor 24 is installed on the top end cap 10 to directly monitor the working liquid level in the mixing chamber. When the working liquid level in the mixing chamber deviates from the preset safety range, the control system can adjust the speed n of the variable speed agitator 4 to change the output pressure head of the propeller 17 in real time and actively eliminate the cumulative error of the feed flow rate.

[0109] To further enhance operational flexibility, a circulation outlet 21 is located near the two-phase interface height of the outer casing 3, and a circulation return outlet 22 is located at the feed height of the mixing chamber. The opening of the circulation return outlet 22 is at the same horizontal height as the light phase inlet pipe 5 and the light phase inlet pipe 6. The circulation outlet 21 and the circulation return outlet 22 are connected by pipelines and switching valves to form an internal circulation valve assembly 23, which is used to stop the two-phase feed in single-stage operation and simultaneously connect the mixing chamber and the clarification chamber to maintain the distribution and mass transfer balance of the two phases within the equipment.

[0110] In the field of liquid-liquid extraction, the application of pressure-enhanced mass transfer is still insufficient due to limitations in the pressure-bearing capacity of extraction equipment. Appropriately increasing the working pressure of the two phases can enhance interfacial turbulence, stabilize and optimize the interfacial state, improve the mass transfer coefficient, increase the mass transfer driving force, and significantly enhance the performance coupling between the light phase packing 18 and the heavy phase packing 19. Many two-phase systems show a significant increase in mass transfer coefficient under pressure, thereby improving extraction efficiency or reducing the amount of extractant used. This invention ensures the safe and efficient use of volatile, high-efficiency solvents through the aforementioned mechanism, or allows for pressurized extraction at higher temperatures, significantly expanding the application boundaries of liquid-liquid extraction technology.

[0111] Based on the significant influence of pressure on the mass transfer dynamics of the extraction process, this invention defines two operating pressure modes and optimizes the corresponding operating parameters. The low-pressure extraction mode is suitable for extraction applications where the operating pressure has little impact on interphase mass transfer, or where the operating pressure does not exceed 0.3 MPa. The pressurized extraction mode is suitable for extraction applications where increasing pressure can promote interphase mass transfer, and the operating pressure is not lower than 0.3 MPa and does not exceed 3.2 MPa. Based on the expansion of the above pressure conditions, the advancement of this invention lies in the ability to select more suitable types of stirring and propellers within the structural space to adapt to a wider range of background pressure and media parameter requirements. Therefore, the technical logic for implementing the extraction machine is as follows: First, determine whether to use the "low-pressure extraction mode" or the "pressurized extraction mode" based on the preferred operating pressure available for the specific two-phase extraction. Then, with the determined processing flow rate Q and the selected pressure mode, the matching relationship between the diameter d of the propulsion chamber 13 and the operating flow rate Q can be clarified by comparing Table 1, providing a basis for the selection of the mixing impeller 16 and the propeller 17, as well as the overall control and adjustment of the equipment. It is well known in the art that a mixing impeller 16 is reasonably selected within the space of the mixing cylinder 1. The propeller 17 has a specific speed of 4,000 to 40,000 or more under the operating conditions. Depending on the different submerged pressure and operating speed, it can be selected, but is not limited to, solid helical blade conveying impeller, propeller type, blade-optimized axial flow pump impeller, etc.

[0112] Table 1. Quantitative relationship between propulsion chamber diameter d, variable speed agitator rotation speed n, and working flow rate under different pressure modes

[0113]

[0114] In the mixing chamber, the interfacial tension between the two phases increases under pressure extraction conditions, resulting in larger average droplets for both phases. Therefore, enhanced stirring is necessary, with a higher rotational speed preferred, and the propeller 17 can also output a larger flow rate. In the clarification chamber, the efficiency of phase separation and clarification is significantly improved under pressure. In summary, within the device structure of this invention, under pressure extraction mode (0.3~3.2 MPa), a larger processing flow rate is preferred for the same model. The diameter d of the propeller chamber and the rotational speed n can have a wider matching relationship. Specifically, when n is 400~600 r / min, the downward flow velocity of the mixture in the propeller chamber 13 is preferably 1.5~3.5 times that under low-pressure extraction mode.

[0115] In summary, the core innovation of the vertical flow single-pot extractor designed in this invention lies in the following: through the reasonable spatial combination of the mixing cylinder 1, the guide cylinder 2, and the outer shell 3, combined with the drive generated by the variable speed stirrer 4, a highly efficient flow field of "downward push mixing - vertical direct flow clarification" is formed in a single container space. The two-phase media are driven to mix in the mixing chamber by downward push, and then guided back by the guide cylinder 2 to enter the clarification chamber as a horizontal radial flow. Then, uniform stratification is achieved in the vertical direction, and both the light and heavy phases after stratification are pressurized and discharged, laying the foundation for subsequent process control and multi-stage countercurrent connection.

[0116] Furthermore, with the optimized combination of the above-mentioned technical features, the vertical flow single-pot extractor can achieve the following new performance in terms of internal flow field and mass transfer separation of light and heavy phases.

[0117] After the uniformly blended two-phase fluid enters the clarification chamber, the vertical floating and sinking of the two-phase emulsion near the interface layer objectively continues the large-area contact mass transfer between the two phases, which can significantly prolong the extraction process and ensure that the two phases reach the mass transfer balance within the stage. Compared with the lift-overflow flow field of the mixing chamber of traditional equipment, the extraction efficiency of a single machine is higher.

[0118] The vertical flow single-tank extractor has phase clarification packing in the two-phase clarification space, and the clarification chamber is much taller in the vertical direction than the traditional horizontal flow clarification chamber. At the same time, the two phases that are no longer in contact are always under pressure, which gives the clarification chamber of this configuration the following properties: First, it achieves uniform distribution of the two phases on the annular cross section of the clarification chamber after stratification; second, it is more conducive to making full use of the packing performance and accelerating clarification; and third, it can make full use of and pressurize to enhance the "Oswald ripening" effect and obtain better clarification results.

[0119] More importantly, there must be a vertical concentration gradient of heterogeneous substances in the two-phase fluid. The concentration of heterogeneous substances decreases with distance from the stratification interface, and the concentration values ​​follow a logarithmic function distribution. This technical mechanism has been reliably demonstrated. Therefore, discharging the two phases from the top and bottom of the vertical flow clarification field in the clarification chamber, respectively, is more in line with technical principles.

[0120] The hydrostatic pressure of the liquid level in the mixing chamber of the extractor and the output pressure boost of the propeller 17 can be maintained and utilized throughout the mass transfer and stratification process, avoiding the head dissipation in the lift-overflow process of traditional equipment, thereby significantly reducing the power consumption of a single unit. Thanks to the clarification efficiency of a single unit, the number of countercurrent stages required for the same separation requirements is reduced, thus achieving energy savings for the entire production line.

[0121] After installing resistance regulating valves on the discharge pipelines of the light phase outlet 7 and the heavy phase outlet 8, the increase in the working liquid level in the clarification chamber can increase the discharge head of the variable speed agitator 4, increase the pressure before the regulating valve on the two-phase discharge pipeline, and thus increase the discharge flow through the valve; conversely, the decrease in the working liquid level will reduce the two-phase discharge flow. This fluid dynamics mechanism can spontaneously suppress the accumulation of flow error during continuous operation.

[0122] The vertical flow single-pot extractor of the present invention not only achieves new functions, but also has a new single-machine control and adjustment method, including: (1) quick material feeding start-up, (2) impact-free temporary start-up and stop control, (3) change processing capacity adjustment, (4) suppress inlet and outlet flow error, (5) adapt to mass transfer component concentration fluctuations and (6) change the two-phase volume ratio, etc., online adjustment.

[0123] (1) Methods for starting the material spreading machine include:

[0124] a) Open the valve on the internal circulation valve assembly 23 to connect the mixing chamber and the clarification chamber;

[0125] b) Close the light phase outlet 7 and the heavy phase outlet 8 to prevent the discharge of both light and heavy phases, and inject the heavy phase first and then the light phase into the mixing chamber according to the preset two-phase ratio, and then stop the two-phase feeding.

[0126] c) Start the variable speed mixer 4 and adjust it to the preset speed;

[0127] d) Close the valve on the internal circulation pipe valve assembly 23 to isolate the mixing chamber and the clarification chamber, and at the same time start the continuous feeding of the two phases according to the preset flow rate, and simultaneously open the light phase liquid outlet 7 and the heavy phase liquid outlet 8 to realize the continuous feeding and discharging of the light and heavy phases.

[0128] (2) Methods for achieving shock-free temporary start-stop include:

[0129] During a temporary shutdown, while stopping the two-phase feed and discharge, the internal circulation valve assembly 23 is opened to create a material circulation between the mixing chamber and the clarification chamber inside the extractor, thereby maintaining the internal two-phase distribution and concentration balance.

[0130] During restart, the two-phase inlet and outlet are restored, and the internal circulation valve assembly 23 is closed simultaneously to achieve a shock-free restart of the extractor.

[0131] (3) The method of changing the processing capacity adjustment includes: by actively increasing or decreasing the speed of the variable speed stirrer 4, the flow rate of the downward thrust generated by the propeller 17 is continuously increased or decreased, thereby realizing the online adjustment of the single-machine processing capacity of the extractor.

[0132] (4) The method for suppressing the error of inlet and outlet flow includes: adjusting the speed of the variable speed agitator 4 in the opposite direction of the deviation direction of the working liquid level signal of the mixing chamber detected by the liquid level sensor 24, changing the discharge flow of the propeller 17, and restoring the variable speed agitator 4 to the set speed after the working liquid level signal of the liquid level sensor 24 returns to the set value, thereby realizing the adjustment of suppressing the error of inlet and outlet flow.

[0133] (5) Adjustment methods to adapt to fluctuations include: after fluctuations in the flow rate of raw liquid or the concentration of mass transfer components, the control height of the phase interface sensor 9 is reset to meet the two-phase balance required for the process to meet the standard (the concentration of the load liquid meets the standard or the residual amount of the raffinate meets the standard). The outlet flow rates of the light phase outlet 7 and the heavy phase outlet 8 are adjusted slightly in opposite directions according to the increase or decrease of the two phase volumes, so that the two-phase interface in the equipment is stabilized at the newly set target height, thereby realizing the reverse adjustment of reconstructing the two-phase balance.

[0134] (6) A method for adjusting the two-phase flow ratio online, including the following steps:

[0135] a) Adjust the inlet flow rate of one or two phases that need to be changed, and simultaneously change the corresponding outlet flow rate;

[0136] b) Based on the signal from the phase interface sensor 9, monitor the movement of the two phase interfaces.

[0137] c) When the interface moves to the target height, continue to fine-tune the opening of the flow regulation mechanism on the outlet pipeline to stabilize the monitoring signal of the phase interface sensor 9 at the target height.

[0138] d) Maintain the operating parameters at the current state to lock in the new two-phase flow ratio.

[0139] Each of the above control and adjustment methods can be completed automatically online, and the adjustment process can avoid oscillations or shocks in the extraction concentration balance and the two-phase volume ratio. Based on the above-mentioned new adjustment methods, the multi-stage countercurrent extraction system constructed by the vertical flow single-pot extractor has superior performance, including higher overall line efficiency, shorter countercurrent stages, more flexible production adjustment, etc., and significantly expands the application fields of liquid-liquid extraction.

[0140] II. Countercurrent Extraction System and Control Methods

[0141] Based on the above-mentioned single-unit extractor, this invention can also construct a countercurrent extraction system consisting of vertical flow single-tank extractors connected in series. Specifically, it refers to connecting the vertical flow single-tank extractors in two or more stages using a countercurrent mass transfer method. Besides the necessary two-phase feeding and regulating facilities, the system allows for flexible machine configuration; that is, it can use extractors of the same size connected in series, or it can select a combination of 2 to 4 different sizes of extractors depending on the magnitude of the two-phase volume changes during the process. A flow chart of a countercurrent extraction system using the light phase as the extractant is shown below. Figure 6 As shown.

[0142] The countercurrent extraction system comprises four systemic functional components, including:

[0143] (1) Main pressure balance pipe for the whole line: connected to the top of each extraction machine and equipped with switch valves; used to inject inert gas at a preset pressure into each extraction machine and achieve pressure balance of each machine.

[0144] (2) Interstage connection and control pipeline assembly: Connect the light phase outlet 7 of the previous stage extractor to the light phase inlet of the next stage extractor, and connect the heavy phase outlet 8 of the next stage extractor to the heavy phase inlet of the previous stage extractor. Each connecting pipeline is equipped with a pressure gauge 25 and a flow regulating valve 26 for comparative adjustment of the flow rates of the two phases or one phase between stages.

[0145] (3) Line connection and interstage isolation components: including heavy phase discharge main pipe 27 connecting the bottom of the clarification chamber of each stage of the extractor and light phase overflow main pipe 28 connecting the feed height of each stage of the mixing chamber, and control valves set between each main pipe and the extractor; to enable the mixing chamber and clarification chamber of each stage of the extractor to become a multi-chamber communication state, or to switch to the interstage isolation state where each stage of the extractor becomes a separate concentration unit.

[0146] (4) Bypass reflux pipeline assembly: connects the outlet of the final stage raffinate to the inlet of the primary feed liquid; used to return the raffinate phase to the feed liquid inlet for bypass circulation of the whole line when the system is started or scheduled to be shut down, while the extractor maintains countercurrent mass transfer until the concentration of the raffinate reaches the standard.

[0147] By configuring the above system components and coordinating the individual control of each extraction stage, the system can perform specific line-wide control operations.

[0148] This invention also provides a control method for the countercurrent extraction system. Based on the coordinated operation of the system's component configuration and individual machine state control, the system can perform the following unique functional operation modes and switch between them, including:

[0149] The system includes the following actions: Line standby and material spreading, used for rapid material spreading of two-phase materials at preset pressures; Stage isolation and internal circulation, used to quickly establish two-phase distribution within the system after the line standby and material spreading actions, and to achieve two-phase material spreading throughout the line; Rare phase bypass circulation, used for two-phase volume distribution and shutdown preparation within the system after the stage isolation and internal circulation actions; Continuous countercurrent extraction, used for normal production operation after the rare phase bypass circulation; Temporary line shutdown, used for temporary production interruption after the continuous countercurrent extraction; Shock-free restart, used for direct resumption of continuous countercurrent extraction after the temporary line shutdown; and Synchronous discharge, used for non-rinsing, graded discharge after shutdown following the temporary line shutdown. Each of these actions is implemented by specific operations of this invention, ensuring efficient and comprehensive system control.

[0150] Specifically, the standby and material spreading actions of the entire line are achieved as follows: based on the overall line pressure balancing manifold and coordinated with the adjustment of each stage of individual machines, the control valves of the overall line connection and interstage isolation components are opened to put the system in an interstage connection state; then, balancing gas is injected into the system through the overall line pressure balancing manifold to maintain the set back pressure; and two-phase materials are injected using the static pressure balance principle to achieve the synchronous attainment of the two-phase interface height and working liquid level in all extractors to the preset value, thereby completing the rapid material spreading of the entire line.

[0151] Isolation and internal circulation actions at each stage: Based on the overall pressure balance main pipe and the overall connection and interstage isolation components, and in coordination with the adjustment of each stage's individual units, the following method is used: close the control valve of the overall connection and interstage isolation components to switch the system to the interstage isolation state; then start the variable speed stirrer 4 of each stage's extractor and open its internal circulation pipe valve assembly 23, so that each stage's extractor can run in internal circulation under isolation state, thereby quickly establishing a stable two-phase flow field and concentration distribution within the system.

[0152] The bypass circulation operation of the raffinate phase is achieved by: based on the bypass reflux pipeline assembly and the overall line connection and interstage isolation assembly, and in coordination with the individual machine adjustment of each stage; in the following manner: the bypass reflux pipeline assembly is opened, and the final stage raffinate phase is introduced into the system inlet for overall line circulation, while fresh extractant is continuously introduced for countercurrent mass transfer; and the operating parameters of each stage are finely adjusted based on the pressure gauge 25 and flow regulating valve 26 in the interstage connection and control pipeline assembly to ensure that the component concentration in the raffinate phase meets the standard, in preparation for switching to continuous countercurrent operation or stopping the machine after meeting the standard.

[0153] Continuous countercurrent extraction operation: Based on interstage connection and control pipeline components and coordinated adjustment of each stage of individual machine; it is achieved in the following way: by closing the bypass reflux pipeline components and switching to continuous feeding and discharging, the system is switched from the cyclic concentration state to stable and continuous production, and the loaded liquid and raffinate are continuously discharged from the two-phase outlet of the system respectively.

[0154] Temporary shutdown of the entire line: Based on the internal circulation valve assembly 23 and the line connection and inter-stage isolation assembly, and in coordination with the adjustment of each stage of individual machine; it is achieved in the following way: while stopping the two-phase feed, the internal circulation valve assembly of each stage is opened, so that each extraction stage enters the internal circulation state, maintaining the internal two-phase distribution and concentration balance at the time of shutdown.

[0155] The shock-free restart of the entire production line is achieved through the internal circulation valve assembly 23 and the interstage connection and control pipeline assembly, in coordination with the individual machine adjustments at each stage. This is accomplished as follows: first, it is confirmed that the agitators at each stage are operating in internal circulation mode; then, two-phase feeding is simultaneously restored, and the internal circulation valves of each extraction stage are closed synchronously. This achieves a shock-free switch from a shutdown state to a continuous countercurrent extraction state for the entire line. This feature gives the production line outstanding operational flexibility, allowing it to "stop and restart at any time."

[0156] The synchronous discharge action of the entire line is achieved in the following manner, based on the internal circulation valve assembly 23 and the interstage connection and control pipeline assembly, and in coordination with the adjustment of each stage of the single machine: the system first executes the whole line circulation action of the raffinate phase to make the concentration of the raffinate liquid reach the standard; then it switches to the interstage connection state defined by the whole line standby and material spreading action and allows it to stand still and separate into layers, finally achieving graded discharge without rinsing.

[0157] Furthermore, the present invention also designs a specific adjustment method for the countercurrent extraction system, including but not limited to online balance adjustment.

[0158] Online balance adjustment of the countercurrent extraction system is the core performance for maintaining stable system operation. The online balance adjustment is based on the adjustment performance of a single unit and is achieved in coordination with the control of system components. It mainly includes three interrelated online adjustments: adjustment to adapt to short-term fluctuations, two-phase flow ratio adjustment, and elimination of cumulative errors.

[0159] The characteristic of the short-term fluctuation adjustment function is that when the feed flow rate or target component concentration changes in the short term, it will cause changes in the volume of one or two phases and the equilibrium concentration of the two phases in each stage of the system. Based on the reverse adjustment method of reconstructing the two-phase equilibrium of a single machine, the aforementioned adaptive fluctuation adjustment can be performed on each stage of the system, in conjunction with the fine adjustment of the opening of the flow control valve 26 on each stage's outlet pipeline. This maintains the stability of the two-phase interface level at the newly set height within each stage of the extractor, thereby achieving adaptive fluctuation adjustment for the entire system line.

[0160] The two-phase flow ratio adjustment function is characterized by maintaining the raffinate concentration or the loaded extractant concentration at the target level when the two-phase flow ratio needs to be adjusted for the entire line. Based on the changes in the two-phase interface height signal monitored by the phase interface sensors 9 of each stage of the extractor, the opening of the flow regulating valve 26 on the pipeline after the light phase outlet 7 and the heavy phase outlet 8 is adjusted to stabilize the two-phase interface at the new target height, thereby precisely controlling the two-phase flow ratio of the entire line. Since both phase fluids are pressurized before the valves, this adjustment can be completed by adjusting a single phase.

[0161] The cumulative error elimination function is characterized by the fact that during continuous operation, the inter-stage cumulative error caused by flow imbalance is reflected in the working liquid level signal of the mixing chamber monitored by the liquid level sensor 24. When the working liquid level in one or more stages of the extractor deviates from the preset range, the feed and discharge flow rates of that stage's extractor are automatically restored to balance by adjusting the speed of the variable speed agitator 4, changing the discharge head of the propeller 17, or simultaneously reducing the two-phase discharge. The above adjustments can continue to be made stage by stage until the working liquid level of the entire line is within the set range, thereby achieving cumulative error suppression for the entire line.

[0162] The aforementioned technical adjustments, based on the unique pressurized discharge performance of the extractor and the configuration of system components, form a complete feedback control loop. This allows for deep collaboration between the individual machine and system components, effectively suppressing common drawbacks of traditional extraction equipment and providing more comprehensive control and adjustment capabilities. Performance upgrades are achieved in areas such as two-phase flow ratio adjustment, operational flexibility, online adjustment accuracy, and energy saving. Compared to traditional centrifugal countercurrent extraction and tank-type countercurrent extraction systems, the extractor and countercurrent system of this invention offer significant advantages in both economy and practicality, providing a newer and better solution for expanding the application of liquid-liquid extraction processes.

[0163] Application Cases

[0164] The following specific application examples will be used to verify the effectiveness of the single extraction machine configuration and adjustment method, countercurrent extraction system and control adjustment method of the present invention.

[0165] First, the basic parameters of the extraction process need to be determined, including the two-phase working flow rate, physical properties (density, concentration, interfacial tension, etc.), mass transfer characteristics, and separation requirements. Based on the required residence time for a single stage (typically 6-30 minutes), the volume of the outer shell 3 is calculated, and then its nominal diameter D (with the diameter-to-height ratio D / H controlled within the range of 0.7-1.0) and height H are determined.

[0166] The downward flow velocity of the mixture in the propulsion chamber 13 is selected based on the interfacial tension and density difference (0.05~0.4 m / s), and the rounded value of the diameter d and the depth h of the propulsion chamber (h / d is 0.45~1.5) are determined accordingly. The volume of the mixing cylinder 1 is such that the average residence time of the two-phase mixture in the mixing chamber is 1.5~7.5 min, specifically as follows: the inner cylinder section diameter d1 must satisfy 2.2d ≤ d1 ≤ (0.4~0.7)D, and the insertion length H2 of the propeller 17 is taken as 0.24~0.72 times H. In addition, the inner diameter d2 of the guide cylinder 2 is determined as 0.4~1.1 times d1.

[0167] The rotational speed n of the variable speed agitator 4 can be adjusted in the range of 150~600 r / min. The agitator assembly should include at least one mixing paddle 16 and a tail propeller paddle 17, with the fluid delivery direction of the propeller paddle 17 being vertically downward.

[0168] The pressure sealing rating, material, and wall thickness should be selected according to the working pressure mode (low pressure ≤ 0.3 MPa or pressurized 0.3~3.2 MPa). All parts in contact with materials must be made of corrosion-resistant materials based on the corrosiveness of the medium. The circulation outlet 21 near the two-phase working interface height of the outer shell 3 is connected to the circulation return port 22 of the mixing cylinder 1 via the internal circulation pipe valve assembly 23. The range of the phase interface sensor 9 is selected according to the interface adjustment range of 0.2~0.7 m, and the liquid level sensor 24 must be able to monitor changes in the liquid level in the mixing chamber.

[0169] Application Case 1-1: Vertical Flow Single-Stage Extractor with Light Phase Extractant

[0170] The volumetric flow rate of the extractant phase is 36–48 m³. 3 / h, density is 830~950 kg / m³ 3 The volumetric flow rate of the working solution to be extracted is 34~46 m³. 3 / h; density difference between working solution and extractant phase 350~500 kg / m 3， The interfacial tension between the two phases is 20~35 mN / m. In actual production, such as the separation of boric acid from salt lake brine, these physical properties meet the above parameters. The residence time of the two-phase media in each stage of the extraction process is determined to be 13~16 min, as required for the primary extraction. The vertical flow single-pot extractor is implemented using the following technical solution:

[0171] The working pressure is atmospheric pressure, and the working temperature is 5 °C ~ 45 °C;

[0172] The outer shell 3 has a diameter D = 2800 mm and a height H = 3300 mm.

[0173] The diameter of the propulsion chamber 13 is d=380 mm and the depth is h=350 mm; the downward flow velocity of the mixture is 0.177 m / s.

[0174] The inner cylinder section diameter of mixing cylinder 1 is d1=1380 mm; the guide cylinder 2 is a combined cylinder with two diameters, the inner diameters of the two sections are 600 mm and 1350 mm respectively.

[0175] The rotational speed n of the variable speed mixer 4 is adjustable within the range of 240~380 r / min, and the propeller is a helical propeller.

[0176] The average residence time of the two-phase mixture in the mixing chamber was 2.6–3.6 min;

[0177] There are 3 hybrid propellers 16; the insertion length H2 of the propeller 17 is 2250 mm;

[0178] The bottom angle α of the inverted conical transition tube is 30°; the penetration depth h1 of the upper edge of the propeller from the inlet of the propulsion chamber is 70 mm; the cone angle β of the drainage cone section 14 is 10°.

[0179] The perpendicular distance H1 between the axis of the light phase inlet pipe 5 and the light phase inlet pipe 6 and the flange sealing surface is 360 mm.

[0180] The elevation H3 of the centerline of the clarifier feed port 20 from the container flange is also the elevation of the two-phase interface, and it is also the target detection depth of the phase interface sensor 9. H3 is determined to be 1450 mm, and the range of the phase interface sensor 9 is 1450~1950 mm.

[0181] The light phase packing 18 uses surface-modified mesh silicon carbide structured packing; the heavy phase packing 19 uses dispersed polytetrafluoroethylene extraction packing. The specific surface area of ​​both phase packings is 250~350 m². 2 / m 3 Filler factor 450-700 m -1 .

[0182] The output flow rate and booster head at the light phase outlet are as follows: Flow rate 32~50 m³ / h 3 / h, booster head 7~4 kPa.

[0183] The output flow rate and booster head at the recurrent phase outlet are respectively: Flow rate 32~50 m³ / h 3 / h, booster head 9~6 kPa.

[0184] Application Case 1-2: The countercurrent extraction system connected in series with the extraction machine in Application Case 1-1 is used for extracting boric acid from old brine in salt lakes.

[0185] Before lithium extraction from salt lake brine, boric acid is typically extracted from the old brine of the salt lake using an extraction method. The old brine is the mother liquor after sodium and potassium separation and removal of suspended solids from the salt lake brine. Preferably, the pH is 2, and the boric acid content is 16.8 g / L. A1416 is used as the extractant, and it is uniformly mixed with an equal volume of sulfonated kerosene as the extraction organic phase. The working flow rate of the old brine is 40 m³ / L. 3 / h, the ratio of blank organic phase to working fluid flow (O / A) is controlled at 1.1:1.

[0186] The countercurrent extraction system employs a five-stage vertical flow single-pot extractor connected in series in a countercurrent mass transfer manner. The outlets of the two countercurrent phases between stages are each connected to the inlet pipeline of the next stage. Pressure gauges 25 and flow control valves 26 are installed on the pipelines before and after the media flow direction. A balance gas main is installed and connected to the top end cap 10 of each stage extractor. A heavy phase discharge main 27 is installed at the bottom of the extractor, connecting to the drain ports of each stage extractor. A light phase overflow main 28 is installed at the feed height of the extractor, connecting to the mixing chamber of each stage extractor. The system flow chart is attached. Figure 6 As shown.

[0187] The dimensions of the five-stage vertical flow single-pot extractor are based on the data in Example 1. The pressure of the balance gas in the balance gas main pipe is atmospheric pressure, the pressure displayed on the pressure gauge 25 is 1.5~25 kPa, and the system operating temperature is room temperature.

[0188] The above systems perform specific standby and material feeding actions, isolation and internal circulation actions at each stage, and raffinate phase circulation actions according to operational needs, for the two-phase volume distribution and shutdown preparation of the system; continuous countercurrent extraction actions for normal production operation; and synchronous material discharge actions for non-rinsing and graded material discharge after shutdown, as well as online adjustment operations to process flow rate and eliminate accumulated errors when necessary.

[0189] After the above five-stage continuous countercurrent extraction, the loaded organic phase contained 5.3%wt boric acid, the raffinate contained 23~26mg / L boric acid, and the total extraction rate was greater than 99.95%.

[0190] Application Case 2-1: Vertical Flow Single-Stage Extractor with Heavy Phase Extractant

[0191] The volumetric flow rate for extracting the organic phase is 16–30 m³. 3 / h density is 1200~1500 kg / m³ 3 The volumetric flow rate of the working solution to be extracted is 18~24 m³. 3 / h; the density difference between the loaded oil phase and the feed water phase is 240~320 kg / m³. 3 The density difference between the two blank phases is 380~400 kg / m³. 3The interfacial tension between the loaded oil phase and the feed aqueous phase is 15~20 mN / m, and the interfacial tension between the blank two phases is 35~45 mN / m. In actual production, such as after polyphenylene sulfide polymerization, the extraction and recovery of the solvent N-methylpyrrolidone meets the above physical property parameters. The residence time of the two-phase media in each extraction stage is determined according to the 16 min required for primary extraction. The implementation of the vertical flow single-pot extractor adopts the following technical solution:

[0192] The working pressure is atmospheric pressure, and the working temperature is 5 °C ~ 45 °C;

[0193] The outer shell has a diameter D = 2400 mm and a height H = 2700 mm.

[0194] The diameter of the propulsion chamber is d=310 mm and the depth is h=300 mm; the downward flow velocity of the mixture is 0.148 m / s.

[0195] The inner cylinder section diameter of the mixing cylinder is d1=1300 mm; the guide cylinder is a variable diameter combined cylinder with inner diameters d2 of 600 mm and 1250 mm for the two sections.

[0196] The speed n of the variable speed mixer is adjustable in the range of 240~380 r / min, and the propeller is a propulsion propeller.

[0197] There are 3 hybrid propellers in total; the penetration length of the propeller is H2 = 1500 mm;

[0198] The average residence time of the two-phase mixture in the mixing chamber was 3.5–4.5 min;

[0199] The bottom angle α of the inverted conical transition tube is 35°; the penetration depth h1 of the upper edge of the propeller from the inlet of the propulsion chamber is 55 mm; the cone angle β of the drainage cone section 14 is 15°.

[0200] The vertical distance H1 between the axis of the two-phase inlet pipe and the flange sealing surface is 300 mm.

[0201] The elevation H3 of the centerline of the clarifier feed port from the container flange is also the elevation of the two-phase interface, and it is also the target detection depth of the phase interface sensor. H3 is determined to be 1100 mm, and the range of the phase interface sensor is 1100~1600 mm.

[0202] The light phase packing 18 uses dispersed polytetrafluoroethylene extraction packing; the heavy phase packing 19 uses surface-modified mesh silicon carbide structured packing. The specific surface area of ​​both phase packings is 250~350 m². 2 / m 3 Filler factor 450-700 m -1 .

[0203] The output flow rate and boost head at the outlet of the loaded oil phase are as follows: the flow rate is 15 - 30 m 3 / h, and the boost head is 12 - 7 kPa.

[0204] The output flow rate and boost head at the outlet of the raffinate aqueous phase are as follows: the flow rate is 15 - 30 m 3 / h, and the boost head is 10 - 5 kPa.

[0205] Application Case 2 - 2: The countercurrent extraction system corresponding to Application Case 2 - 1 is used for the extraction of N - methylpyrrolidone in the production of polyphenylene sulfide by using a series - connected extraction machine.

[0206] The mixed waste liquid composed of the mother liquor and the washing liquid after the reaction of polyphenylene sulfide. In the filtrate obtained by pretreating the waste liquid to remove residual oligomers, the NMP content fluctuates within the range of 22 - 30%wt, the pH value varies within the range of 9 - 11, the feed flow rate is 19 m 3 / h, and the raffinate with an NMP content lower than 1000 mg / L is qualified.

[0207] The countercurrent extraction system uses four - stage vertical - flow single - kettle extraction machines connected in series in the counter - current mass transfer mode. The outlet of the counter - current two - phase between stages is respectively connected to the feed port pipeline of the next stage, and pressure gauges and flow regulating valves are arranged in front and behind according to the flow direction of the medium on the pipeline; a balance gas main pipe is set and connected to the top heads of each stage of extraction machines; a heavy - phase discharge main pipe connecting the drain ports of each stage of extraction machines is set at the bottom of the extraction machines; a light - phase overflow main pipe connecting the mixing chambers of each stage of extraction machines is set at the feed height of the extraction machines. The system flow is as shown in the appendix Figure 6 shown. The extraction machine at the light - phase feed end is the primary extraction, and the extraction machine at the heavy - phase feed end is the final stage.

[0208] The sizes of the four - stage vertical - flow single - kettle extraction machines are all based on the data of Example 3. The pressure of the balance gas in the balance gas main pipe is 0.4 MPa, the indicated pressure of the pressure gauge is the boost head of 1.5 - 15 kPa, and the system operating temperature is 42 - 45 °C.

[0209] Chloroform is used as the extractant to recover N - methylpyrrolidone (NMP) therein. The flow ratio O / A of blank chloroform to the filtrate is at most 1:1, normally 18:19, and at least 12.5:19. The average extraction factor E for each extraction stage is 5.25, and at most 11.5:19.

[0210] The above - mentioned system respectively performs specific whole - line standby and feeding operations, stage - by - stage isolation and internal circulation operations, and raffinate - phase whole - line circulation operations according to the operation requirements, for the two - phase volume distribution of the system and preparation for shutdown; continuous counter - current extraction operations for normal production operation; whole - line synchronous discharging operations for discharging different media without flushing after shutdown, and online adjustment operations for processing flow rate and eliminating cumulative errors when necessary.

[0211] The extractor can employ unique control and regulation methods, including: online adjustment of single-unit processing capacity, reverse regulation to reconstruct two-phase equilibrium, suppression of short-term fluctuations in the working liquid level, and online regulation of two-phase equilibrium within the stage for impact-free temporary start-up and shutdown. This enables the single unit and its connected countercurrent extraction system to possess comprehensive line-wide control performance. Furthermore, it can perform online adjustment of processing capacity, suppression of short-term fluctuations in the working liquid level, and impact-free temporary start-up and shutdown as needed.

[0212] Since the NMP concentration in the raffinate phase is less than 1000 mg / L and has a relatively large margin, the process target is to achieve the required concentration of the loaded extractant phase when the feed conditions of the above system fluctuate. For example, when the NMP concentration decreases, the interface between the two phases will shift towards the heavier phase due to the decrease in the total mass transfer of the raffinate (the volume of the loaded phase decreases, and the volume of the raffinate phase increases). In this case, the interface height of each stage in the system should be re-controlled according to the current concentration, while the feed flow rate of the heavier chloroform phase should be reduced. The specific adjustments are as follows:

[0213] When the NMP concentration in the working fluid was reduced to 22% wt, the interface control height of the final stage extractor was set at a ratio of 14.5:12.5. At this flow ratio, the concentration of the heavy phase at the outlet remained unchanged, while the raffinate light phase still met the requirements. This height was used as the target value for all extractors, while the chloroform inlet flow rate was reduced to 12.5 m³ / s. 3 / h. While reducing the opening of the flow regulating valve on the light phase outlet line, slightly increase the opening of the heavy phase outlet regulating valve to stabilize the signal from the phase interface sensor at the new set value. Then, adjust the height of the phase interface at each stage of the extractor in the same manner to complete the reverse process adjustment.

[0214] When the NMP concentration in the feed working solution increases, the interface between the two phases will shift towards the lighter phase due to the increase in the total mass transfer of the raffinate (the volume of the loaded phase increases, and the volume of the raffinate phase decreases). In this case, the compensation adjustment is performed in the opposite direction.

[0215] The NMP content in the working solution is 30% wt, and the chloroform heavy phase flow rate is controlled at 18 m³ / min. 3 / h; When the NMP in the feed working solution decreases to 22% wt, adjust the heavy phase chloroform flow rate to 12.5 m³ / h. 3 / h.

[0216] Before and after adjusting for feed fluctuations, the concentration of NMP in the heavy phase after extraction can be maintained at 39.1% wt; the concentration of NMP in the light phase after raffinate is 450~880 mg / L, and the total extraction rate is always greater than 99.94%.

Claims

1. A vertical flow single-pot extractor for liquid-liquid extraction of oil and water phases, characterized in that, The structure of the extraction machine includes: The outer shell (3) of the vertical container is welded together from the lower head, the cylinder, the upper head and the top flange; The mixing cylinder (1) is coaxially disposed on the upper part of the outer shell (3); The guide tube (2) is the lower coaxial outer sleeve of the mixing tube (1), which is installed on the lower end cap of the outer shell (3) and guides the fluid to the outer space between the mixing tube (1) and the guide tube (2); The components of the mixing cylinder (1) include: a top end cap (10) with a vertical cylinder section and a flange, a sealing ring (11), an inner cylinder section (12), a propulsion chamber (13) and a diversion cone section (14), and a balance gas interface is provided on the top end cap (10); The flange of the top sealing head (10) is paired with the top flange of the outer shell (3) and together they clamp the sealing ring (11), thereby forming a pressure-isolated seal for the internal space of the extractor and enabling the extractor to be designed and manufactured in accordance with pressure vessel specifications. After the top end cap (10), mixing cylinder (1) and guide cylinder (2) are assembled and connected with the outer shell (3), the internal space of the outer shell (3) is divided into a mixing chamber formed by the inside of the mixing cylinder (1) and the guide cylinder (2), and an annular clarification chamber formed between the mixing cylinder (1), the guide cylinder (2) and the outer shell (3); A variable speed agitator (4) is installed on the top of the mixing cylinder (1), and its drive shaft is a multi-paddle stirring shaft (15) that extends into the mixing chamber. The multi-paddle stirring shaft (15) is provided with at least one mixing paddle (16) and at least one propeller paddle (17) located at the tail end of the multi-paddle stirring shaft (15). The mixing paddle (16) is used to drive the two-phase materials to mix uniformly, and the propeller paddle (17) is used to generate an axial downward thrust flow to transport the blended materials. The light phase inlet (5) and the heavy phase inlet (6) are located on the same horizontal plane of the vertical cylinder section of the top head (10); The light phase outlet (7) and the heavy phase outlet (8) are respectively located at the upper and lower parts of the outer shell (3), and are respectively provided with internal drainage pipes for drawing out the stratified light phase and heavy phase from the top and bottom of the clarification chamber, respectively. The light phase drives the gas phase to exit at the top of the clarification chamber to form the clarification chamber to be fully filled during operation. A phase interface sensor (9) is installed on the upper end cap of the outer shell (3) and extends into the clarification chamber to monitor the level of the two-phase working interface in the clarification chamber. The upper and lower parts of the interface level are the light phase and heavy phase clarification spaces, respectively, and light phase packing (18) and heavy phase packing (19) with clarification functions are installed respectively. Based on the spatial combination of the mixing cylinder (1), the guide cylinder (2) and the outer shell (3) and the combined action of the variable speed stirrer (4), the two-phase media form a downward flow mixing-vertical direct current clarification flow field in a single container space, which drives the material to be mixed by downward flow in the mixing chamber, and then guided back by the guide cylinder (2) to enter the clarification chamber in a horizontal radial flow, and then achieves stratification in the vertical direction, so that both light and heavy phases after stratification can be pressurized and discharged.

2. The vertical flow single-pot extractor according to claim 1, characterized in that, A circulation outlet (21) is provided near the height of the two-phase working interface of the outer shell (3), and a circulation return outlet (22) is provided at the feed height of the mixing cylinder (1). The two are connected by an internal circulation pipe valve assembly (23) consisting of pipelines and switching valves, so as to stop the two-phase feeding in the single-stage working state and simultaneously connect the mixing chamber and the clarification chamber to maintain the distribution and mass transfer balance of the two phases in the equipment.

3. The vertical flow single-pot extractor according to claim 1, characterized in that, The nominal diameter D and height H of the outer shell (3) are determined according to the single-machine residence time required for mass transfer separation, and the diameter-to-height ratio D / H is 0.7~1; the single-machine residence time is determined in the range of 6~30 min according to the large to small values ​​of interfacial tension and density difference between the two phases, and then the volume of the outer shell (3) is determined. After calculating the nominal diameter D, H is then calculated in reverse.

4. The vertical flow single-pot extractor according to claim 1, characterized in that, In the components of the mixing cylinder (1), the sealing ring (11) is welded to the inner cylinder section (12), and the inner cylinder section (12) is connected to the propulsion chamber (13) and the drainage cone section (14) in sequence through an inverted conical diameter-changing section; the dimensions of the above components include: The diameter d and depth h of the propulsion chamber (13) are determined by the extraction working flow rate, and the length-to-diameter ratio h / d is 0.45~1.5; specifically, the downward flow velocity of the mixture in the propulsion chamber (13) is selected in the range of 0.05~0.4 m / s according to the increasing value of the interfacial tension value and density difference between the two phases of extraction, and the rounded value of d is calculated. The inner cylinder section diameter d1 of the mixing cylinder (1) and the insertion length H2 of the propeller (17) are determined according to the mixing residence time of the two-phase medium in the mixing chamber, which is 1.5 to 7.5 min. The following conditions must be met: the mixing chamber volume is calculated based on the mixing residence time, and the rounded value of d1 is selected in the range of 2.2d ≤ d1 ≤ (0.4~0.7) D according to the extraction of the interfacial tension value and density difference of the two phases from small to large. At the same time, H2 is determined in the range of 0.24 to 0.72 times the height H of the outer shell (3). The bottom angle α of the inverted conical variable diameter section is selected in the range of 20°~50° according to the extraction interfacial tension value and density difference value from large to small, and satisfies that the penetration depth h1 of the upper edge of the propeller (17) from the inlet of the propulsion chamber (13) is 0.12~0.5 times d; The cone angle β of the drainage cone section (14) is determined in the range of 5°~55° according to the overflow pipe length and the density difference between the two phases from small to large.

5. The vertical flow single-pot extractor according to claim 1, characterized in that, The inner diameter d2 of the guide tube (2) is determined to be 0.4 to 1.1 times the inner cylinder section diameter d1 of the mixing tube (1); and several horizontally distributed clarification chamber feed ports (20) are provided on the top of the guide tube (2), wherein the line height H3 is designed according to the height of the two-phase interface under working conditions and is the same as the median detection depth of the phase interface sensor (9).

6. The vertical flow single-pot extractor according to claim 1, characterized in that, The vertical distance H1 between the opening height of the light phase inlet (5) and the heavy phase inlet (6) and the flange sealing surface of the top end cap (10) is 0.15 to 0.4 times the inner cylinder section diameter d1 of the mixing cylinder (1).

7. The vertical flow single-pot extractor according to claim 1, characterized in that, The range of the phase interface sensor (9) corresponds to the range in which the height of the light and heavy phase interface can be effectively adjusted under working conditions. The adjustment range is 0.1 to 0.3 times the height H of the outer shell (3).

8. The vertical flow single-pot extractor according to claim 1, characterized in that, The light phase packing (18) and heavy phase packing (19) installed in the light phase and heavy phase clarification space have the same surface polarity as the heterogeneous emulsion droplets in their respective spaces and similar surface energies.

9. The vertical flow single-pot extractor according to claim 1 or 2, characterized in that, A level sensor (24) for monitoring the working liquid level inside the mixing cylinder (1) is also installed on the top end cap (10).

10. The vertical flow single-pot extractor according to claim 1 or 2, characterized in that, Based on the influence of working pressure on the mass transfer dynamics of the system, this extractor distinguishes between two working pressure modes: low-pressure and pressurized. The low-pressure extraction mode is suitable for extraction applications where the working pressure does not exceed 0.3 MPa; the pressurized extraction mode is suitable for extraction applications where pressurization can promote interphase mass transfer and the working pressure is not lower than 0.3 MPa and not higher than 3.2 MPa. In the low-pressure extraction mode, the rotational speed n of the variable speed stirrer (4) is 150~400 r / min, and the matching relationship between the diameter d of the propulsion chamber (13) and the working flow rate Q of the extractor is as follows: When the diameter d of the propulsion chamber (13) is 70~190 mm, the working flow rate Q is 1.2~6 m³ / h; When the diameter d of the propulsion chamber (13) is 190~250 mm, the working flow rate Q is 6~15 m³ / h; When the diameter d of the propulsion chamber (13) is 250~325 mm, the working flow rate Q is 15~36 m³ / h; When the diameter d of the propulsion chamber (13) is 340~400 mm, the working flow rate Q is 36~75 m³ / h; When the diameter d of the propulsion chamber (13) is 400~475 mm, the working flow rate Q is 75~150 m³ / h; When the diameter d of the propulsion chamber (13) is 475~550 mm, the working flow rate Q is 150~220 m³ / h.

11. The vertical flow single-pot extractor according to claim 10, characterized in that, In the pressurized extraction mode, the rotational speed n of the variable speed stirrer (4) is 150~600 r / min, and when n is 400~600 r / min, the downward flow rate of the mixture in the propulsion chamber (13) is 1.5~3.5 times that of the downward flow rate in the low-pressure extraction mode.

12. The adjustment method of the vertical flow single-pot extractor according to claim 2, characterized in that, To start the material feeding process, follow these steps: a) Open the valve on the internal circulation valve assembly (23) to connect the mixing chamber and the clarification chamber; b) Close the light phase outlet (7) and the heavy phase outlet (8) to prevent the discharge of both light and heavy phases, and inject the heavy phase first and then the light phase from the mixing chamber according to the preset two-phase ratio, and then stop the two-phase feeding; c) Start the variable speed mixer (4) and adjust it to the preset speed; d) Close the valve on the internal circulation pipe valve assembly (23) to isolate the mixing chamber and the clarification chamber, and at the same time start the continuous feeding of the two phases according to the preset flow rate, and simultaneously open the light phase outlet (7) and the heavy phase outlet (8) to realize the continuous feeding and discharging of the light and heavy phases.

13. The adjustment method of the vertical flow single-pot extractor according to claim 2, characterized in that, To achieve shock-free temporary start-stop, follow these steps: When temporarily shutting down, while stopping the two-phase feed and discharge, the internal circulation valve assembly (23) is opened to form a material circulation between the mixing chamber and the clarification chamber inside the extractor, thereby maintaining the internal two-phase distribution and concentration balance; During restart, the two-phase feed and discharge are restored, and the internal circulation valve assembly (23) is closed simultaneously to achieve a shock-free restart of the extractor.

14. The adjustment method of the vertical flow single-pot extractor according to claim 1, characterized in that, By actively increasing or decreasing the rotation speed of the variable speed mixer (4), the flow rate of the downward thrust generated by the propeller (17) can be continuously increased or decreased, thereby adjusting the processing capacity.

15. The adjustment method of the vertical flow single-pot extractor according to claim 1 or 2, characterized in that, The rotational speed of the variable speed agitator (4) is adjusted in the opposite direction based on the deviation direction of the working liquid level signal of the mixing chamber detected by the liquid level sensor (24), thereby changing the discharge flow rate of the propeller (17). The variable speed agitator (4) is restored to the set speed after the working liquid level signal of the liquid level sensor (24) returns to the set value, thereby achieving the adjustment to suppress the error of the inlet and outlet flow rates.

16. The adjustment method of the vertical flow single-pot extractor according to claim 1, characterized in that, After fluctuations in the flow rate of the raw liquid or the concentration of the mass transfer component, the control height of the phase interface sensor (9) is reset to meet the two-phase balance required for the process to be up to standard. The outlet flow rates of the light phase outlet (7) and the heavy phase outlet (8) are adjusted slightly in opposite directions according to the increase or decrease of the two phase volumes, so that the two-phase interface in the equipment is stabilized at the newly set target height, thereby realizing the reverse adjustment of reconstructing the two-phase balance.

17. The adjustment method of the vertical flow single-pot extractor according to claim 1, characterized in that, The online adjustment of the two-phase flow ratio is achieved through the following steps: a) Adjust the inlet flow rate of one or two phases that need to be changed, and simultaneously change the corresponding outlet flow rate; b) Based on the signal from the phase interface sensor (9), monitor the movement of the two phase interfaces; c) When the interface moves to the height of the adjustment target, continue to fine-tune the outlet flow rate and stabilize the monitoring signal of the phase interface sensor (9) at the target height. d) Maintain the operating parameters at the current state to lock in the new two-phase flow ratio.

18. A multi-stage countercurrent extraction system, comprising two or more vertical flow single-pot extractors as described in claim 1 or 2 connected in series, for liquid-liquid countercurrent mass transfer, characterized in that, The system selects models of the same size, or combines 2 to 4 models of different specifications according to the mass transfer stages based on the volume change of the two phases during extraction. The multi-stage countercurrent extraction system also includes the following system-level functional components: The main pressure balance pipe for the entire line is connected to the top of each extraction machine and is equipped with a switch valve; this is used to inject inert gas at a preset pressure into each extraction machine and achieve pressure balance of each machine. The interstage connection and control pipeline assembly connects the light phase outlet (7) of the previous stage extractor to the light phase inlet of the next stage extractor, and connects the heavy phase outlet (8) of the next stage extractor to the heavy phase inlet of the previous stage extractor. Each connecting pipeline is equipped with a pressure gauge (25) and a flow control valve (26) for comparative adjustment of the flow rates of the two phases or one phase between stages. The whole line connection and interstage isolation components include a heavy phase discharge main pipe (27) connecting the bottom of the clarification chamber of each stage of the extractor and a light phase overflow main pipe (28) connecting the feed height of each stage of the mixing chamber, as well as control valves installed between each main pipe and the extractor; to enable the mixing chamber and clarification chamber of each stage of the extractor to become a multi-chamber communication state, or to switch to the interstage isolation state where each stage of the extractor becomes a separate concentration unit; The bypass reflux pipeline assembly connects the final stage raffinate outlet to the primary feed liquid inlet; it is used to return the raffinate phase to the feed liquid inlet for bypass circulation of the entire line when the system is started up or scheduled to be shut down, while the extractor maintains countercurrent mass transfer until the raffinate concentration reaches the standard. By setting up the above system and functional components, and coordinating with the individual control of each extraction machine, this system can perform specific whole-line control operations.

19. The control and adjustment method for the multi-stage countercurrent extraction system according to claim 18, characterized in that, By manipulating and adjusting system-level functional components and extraction machines at each stage, the system can possess the following unique functional operating modes: The entire line standby and material spreading actions are based on the entire line pressure balance main pipe and coordinated with the adjustment of each level of individual machine. It is used for the entire line to standby at preset pressure and for the rapid spreading of two-phase materials. The isolation and internal circulation actions at each level are based on the overall line pressure balance main pipe and the overall line connection and inter-stage isolation components, and are coordinated with the adjustment of each level of individual machine. This is used to quickly establish the two-phase distribution within the system after the overall line standby and material spreading actions, and to realize the two-phase material spreading of the entire line. The residual phase bypass circulation operation is based on the bypass return pipeline assembly and the line connection and inter-stage isolation assembly, and coordinates with the adjustment of each stage of individual units. It is used to ensure that the residual phase concentration in the system reaches the standard and prepares for shutdown after each stage of isolation and internal circulation operation. The continuous countercurrent extraction operation, based on interstage connection and control pipeline components and coordinated adjustment of each stage of individual machine, is used for normal operation after the bypass circulation operation of the raffinate phase rectification line; The temporary shutdown of the entire production line is based on the internal circulation valve assembly (23) and the entire line connection and interstage isolation assembly, and is coordinated with the adjustment of each stage of individual machines. It is used for the temporary interruption of production after the continuous countercurrent extraction operation. The shockless restart of the entire production line is based on the internal circulation valve assembly (23) and the interstage connection and control pipeline assembly, and is coordinated with the adjustment of each stage of individual machines. It is used for the direct restoration of production operation to continuous countercurrent extraction after the temporary shutdown of the entire production line. The synchronous material discharge action of the whole line is based on the internal circulation valve assembly (23) and the interstage connection and control pipeline assembly and coordinates the adjustment of each level of single machine. It is used for the whole line shutdown and non-rinsing graded material discharge after the temporary shutdown action of the whole line.

20. The control and adjustment method for the multi-stage countercurrent extraction system according to claim 18, characterized in that, By manipulating and regulating system-level functional components and extraction machines at each stage, the system achieves unique online balance regulation functions, including three online regulation functions: adaptation to short-term fluctuations, two-phase flow ratio regulation, and elimination of cumulative errors. The short-term fluctuation adjustment function is that when the feed flow rate or target component concentration changes in the short term, it is based on the control of the interstage connection and control pipeline components, and coordinates the adjustment of each stage of the single machine to adapt to the fluctuation. Under the reconstructed two-phase balance, it maintains the stability of the two-phase interface level inside each stage of the extractor, and realizes the fluctuation compensation adjustment of the whole system line. The two-phase flow ratio adjustment function is that when it is necessary to change the light and heavy two-phase flow ratio in the system, it is based on the control of the inter-stage connection and control pipeline components, and coordinates the online adjustment of the two-phase flow ratio of each stage unit to achieve the adjustment and stabilization of the two-phase flow ratio of the whole line. The cumulative error elimination function is that when it is necessary to restore the working liquid level of a certain stage or several stages of the extractor, it is based on the adjustment of the inlet and outlet flow rate of each stage to suppress the error, and coordinates the control of the inter-stage connection and control pipeline components to achieve the suppression of cumulative error of the entire line.

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