A centrifugal liquid-liquid phase separation system and method

Abstract

The invention discloses a centrifugal liquid-liquid phase separation system and method, the phase separation system comprises a raw material tank, a booster pump, a cooler, a spiral phase separation pipeline, a heavy phase extraction valve, a heavy phase extraction sensor, a light phase extraction valve, a light phase extraction sensor and a reflux valve, the liquid outlet of the raw material tank is connected to the cooler through the booster pump, the cooler is used to cool the solution discharged from the raw material tank; the liquid outlet of the cooler is connected to the liquid inlet of the spiral phase separation pipeline, the spiral phase separation pipeline is provided with a heavy phase extraction port at a corresponding position of the outer wall of different layers of pipelines, the heavy phase extraction port is provided with a heavy phase extraction sensor and a heavy phase extraction valve, the liquid outlet of the spiral phase separation pipeline is connected with a light phase extraction pipe and a reflux pipe in parallel, and the reflux pipe is connected to the liquid inlet of the raw material tank. The centrifugal liquid-liquid phase separation system of the invention realizes the separation of heavy phase solution and light phase solution by using the centrifugal force generated by the spiral phase separation pipeline, and the system structure is more compact and occupies a small area.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid-liquid separation, and in particular to a centrifugal liquid-liquid phase separation system and method. Background Art

[0002] Liquid-liquid separation technology is widely used in various fields such as petroleum, chemical industry, food, medicine, and environmental protection. The traditional liquid-liquid separation technology is gravity separation, which uses the density difference between different liquids. Under the action of gravity, the high-density liquid sinks and the low-density liquid floats, thereby achieving separation. Gravity separation is suitable for liquid mixtures with large density differences and immiscible liquids, such as the separation of water and oil, and the separation speed is slow. When achieving continuous separation, it often requires a large and complex separation system, which requires large equipment investment and floor space. In addition, because gravity separation uses density differences to achieve separation, when the feed flow rate or feed composition fluctuates, there is often a serious phase interface fluctuation problem, resulting in low separation purity or even inability to separate phases normally. Summary of the invention

[0003] In view of the above-mentioned defects of the prior art, the present invention provides a centrifugal liquid-liquid phase separation system. When the two-phase solution enters the centrifugal liquid-liquid phase separation system, the centrifugal force generated by the spiral phase separation pipe causes the heavy phase solution to be enriched on the outer wall of the pipe and discharged through the heavy phase extraction pipe. The light phase solution is subjected to relatively small centrifugal force, so it flows close to the inner wall of the spiral phase separation pipe and is discharged through the light phase extraction pipe, thereby achieving the separation of the heavy phase solution and the light phase solution. The centrifugal liquid-liquid phase separation system of the present invention achieves the separation of the heavy phase solution and the light phase solution by virtue of the difference in the magnitude of the centrifugal force exerted on the heavy phase solution and the light phase solution, thereby improving the separation speed and separation purity compared to the traditional gravity separation method. To this end, the present invention also provides a centrifugal liquid-liquid phase separation method.

[0004] A first aspect of the present invention provides a centrifugal liquid-liquid phase separation system, comprising a raw material tank, a booster pump, a cooler, a spiral phase separation pipeline, a heavy phase production valve, a heavy phase production sensor, a light phase production valve, a light phase production sensor and a reflux valve.

[0005] The liquid outlet of the raw material tank is connected to the liquid inlet of the cooler through a booster pump, and the cooler is used to cool the solution discharged from the raw material tank;

[0006] The liquid outlet of the cooler is connected to the liquid inlet of the spiral phase-separation pipeline, the spiral phase-separation pipeline is a spiral multi-layer pipeline, and the spiral phase-separation pipeline is provided with heavy phase production outlets at corresponding positions on the outer wall of different layers of the pipeline, the heavy phase production outlet is connected to the heavy phase production pipe, and the heavy phase production outlet is provided with a heavy phase production sensor and a heavy phase production valve.

[0007] The liquid outlet of the spiral phase-separation pipeline is connected in parallel with a light phase production pipe and a reflux pipe, and the light phase production pipe and the reflux pipe are respectively provided with a light phase production valve and a reflux valve. A light phase production sensor is provided at the liquid outlet of the spiral phase-separation pipeline, and the light phase production sensor is connected to the light phase production valve and the reflux valve. The reflux pipe is connected to the liquid inlet of the raw material tank.

[0008] The two-phase solution discharged from the raw material tank enters the cooler through the booster pump to cool down and increase the density difference of the two-phase solution; the cooled two-phase solution enters the spiral phase separation pipeline. Because the heavy phase solution has a larger density and is subjected to a larger centrifugal force, it flows away from the central axis of rotation and along the outer edge wall of the curved flow channel in the spiral phase separation pipeline; the light phase solution has a smaller density and is subjected to a relatively lower centrifugal force, and flows close to the inner edge wall of the curved flow channel. Thus, the separation of the heavy phase solution and the light phase solution is achieved.

[0009] As a preferred embodiment, each layer of the spiral phase-separated pipeline is at a different height, and the projected diameter of each layer of the spiral phase-separated pipeline decreases successively from the liquid inlet to the liquid outlet.

[0010] As a more preferred embodiment, the projected diameter of the pipe at the layer where the liquid inlet of the spiral phase-separation pipe is located is more than 3 times that of the pipe at the layer where the liquid outlet is located.

[0011] The projected diameter of the pipe at the layer where the liquid outlet is located is set to be lower than the projected diameter of the pipe at the layer where the liquid inlet is located, which overcomes the problem of reduced flow rate, reduced flow velocity and reduced centrifugal force at the liquid outlet, and helps to improve the separation efficiency and separation purity under low flow rate conditions at the liquid outlet.

[0012] As another preferred embodiment, each layer of the spiral phase-separation pipeline is located in the same plane, the liquid inlet of the spiral phase-separation pipeline is located in the outermost circle, and the liquid outlet of the spiral phase-separation pipeline is located in the innermost circle.

[0013] As another preferred embodiment, each layer of the spiral phase-separated pipeline is at a different height, and each layer of the spiral phase-separated pipeline has the same projected diameter.

[0014] As a more preferred embodiment, the cross-section of the spiral phase-separated pipe is elliptical, and the major axis of the ellipse is in the horizontal direction.

[0015] The cross-section of the spiral phase separation pipe is set to an ellipse, and the long axis direction of the ellipse structure is consistent with the direction of the centrifugal force, which is beneficial to reducing the secondary flow and Dean vortex generated by the vortex of the solution in the pipe, and improving the separation purity and separation efficiency of the solution.

[0016] As another preferred embodiment, the spiral phase-separation pipe is arranged in a phase separator, and the spiral phase-separation pipe and the inner wall of the phase separator are surrounded to form a pipe for solution circulation.

[0017] As a more preferred embodiment, the area of ​​the spiral phase-separated pipeline decreases proportionally with the increase of the height of the layer where the pipeline is located.

[0018] The spiral phase separation pipeline is set to a flow channel design with a tapered cross-section, which can ensure that the flow channel at the liquid outlet still has a high flow velocity and centrifugal force, and can be used for the separation of two-phase solutions with a large feed volume.

[0019] As a preferred embodiment, the side wall of the spiral phase-separated pipe is provided with an anti-vortex baffle.

[0020] The setting of the anti-vortex baffle effectively avoids pulsation and backmixing between stratified solutions caused by secondary flow and Dean vortex when the solution flows in a curved manner.

[0021] As a more preferred embodiment, the anti-vortex baffle is horizontally arranged on the inner wall of the spiral phase-separated pipe, and the anti-vortex baffle runs through the entire spiral phase-separated pipe.

[0022] The anti-vortex baffle can be set as one or two. When set as one, the anti-vortex baffle can be connected to the inner wall of one side of the spiral phase-separated pipe, or it can be connected to the inner wall of both sides of the spiral phase-separated pipe.

[0023] As a preferred embodiment, the cross-sectional shape of the spiral phase-separated pipe is circular, elliptical, triangular, rectangular or irregular.

[0024] The cross-sectional shape of the spiral phase-separated pipe can be a common shape, such as a circle, an ellipse, a triangle, a rectangle, or an irregular shape, such as a special shape.

[0025] A second aspect of the present invention provides a centrifugal liquid-liquid phase separation method, which uses the above-mentioned centrifugal liquid-liquid phase separation system to perform phase separation, comprising the following steps:

[0026] S1, discharge the two-phase solution in the raw material tank into the cooler through the booster pump for cooling treatment;

[0027] S2. The cooled solution enters the spiral phase separation pipe. Under the action of centrifugal force, the two-phase solution is separated into a heavy phase solution and a light phase solution. The heavy phase solution is discharged from the heavy phase extraction pipe, and the light phase solution is discharged from the light phase extraction pipe. The two-phase solution that cannot be separated flows back to the raw material tank from the reflux pipe.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The centrifugal liquid-liquid phase separation system of the present invention achieves separation of heavy phase solution and light phase solution by using the centrifugal force generated by the spiral phase separation pipeline. The system structure is more compact and occupies a small area.

[0030] (2) The centrifugal liquid-liquid phase separation system of the present invention is first subjected to a cooling treatment before the two-phase solution enters the spiral phase separation pipeline to increase the density difference between the two-phase solution, so that the flow channel cross section can obtain a larger density gradient during the centrifugal cyclone, thereby improving the separation purity of the heavy phase solution and the light phase solution.

[0031] (3) The centrifugal liquid-liquid phase separation system of the present invention is provided with a plurality of heavy phase extraction ports on the outer wall of the spiral phase separation pipe to realize the gradual extraction of the heavy phase solution and avoid excessive extraction at one time that affects the purity of the heavy phase solution.

[0032] (4) The centrifugal liquid-liquid phase separation system of the present invention utilizes the influence of the density difference of the two-phase solution on the centrifugal force to achieve liquid-liquid separation. The separation process is continuous and is not affected by factors such as solution ratio, inlet flow state, inlet flow rate, liquid level height, etc., and has a wider range of applications.

[0033] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of a centrifugal liquid-liquid phase separation system in Example 1 of the present invention;

[0035] Figure 2 It is a schematic structural diagram of an anti-vortex baffle in a centrifugal liquid-liquid phase separation system of the present invention;

[0036] Figure 3 It is a structural schematic diagram of the cross-sectional shape of the spiral phase separation pipeline in the centrifugal liquid-liquid phase separation system of the present invention;

[0037] Figure 4 is a schematic diagram of a centrifugal liquid-liquid phase separation system in Example 2 of the present invention;

[0038] Figure 5 is a schematic diagram of a centrifugal liquid-liquid phase separation system in Example 3 of the present invention;

[0039] Figure 6 Schematic diagram of the centrifugal liquid-liquid phase separation system in Example 4 of the present invention.

[0040] Among them: 1-raw material tank, 2-boosting pump, 3-cooler, 4-spiral phase separation pipeline, 5-heavy phase production valve, 6-heavy phase production sensor, 7-light phase production sensor, 8-light phase production valve, 9-reflux valve, 41-anti-vortex baffle. DETAILED DESCRIPTION

[0041] In order to make the technical means, creative features, objectives and effects of the invention easier to understand, the invention is further described below with reference to specific illustrations. However, the invention is not limited to the following implementation cases.

[0042] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0043] Gravity separation is a conventional method for liquid-liquid separation, which uses gravity to achieve the separation of solutions with different densities. However, due to the simple use of gravity, the separation speed is slow, and gravity separation is only applicable to two-phase solutions with large density differences.

[0044] The present invention changes the existing ideas and uses centrifugal force to achieve separation. By improving the phase-separation pipeline, centrifugal force is generated when the two-phase solution flows through the phase-separation pipeline. The centrifugal force on the heavy phase solution is larger, and it is enriched on the outer edge of the pipeline; the centrifugal force on the light phase solution is smaller, and it is enriched on the inner edge of the pipeline. Through the ingenious design of the phase-separation pipeline structure, the separation of the heavy phase solution and the light phase solution is achieved. Compared with the gravity separation method, the separation speed is significantly improved.

[0045] For most small molecule liquids, their density changes with temperature. The inventors of this application have found through repeated experiments that the lower the solution temperature, the greater the density difference between solutions. Taking refrigerant R22 (chlorodifluoromethane) and mineral refrigeration oil 3GS as an example, when the temperature range is 25℃-85℃, the density of refrigerant R22 changes from 1200kg / m 3 (25℃) reduced to 850kg / m 3 (85℃), and the density of refrigeration oil is 890kg / m 3 (25℃) reduced to 850kg / m 3 (85°C). Therefore, the liquid-liquid two-phase solution needs to be cooled before centrifugal separation to increase the density gradient of the liquid during cyclone flow and facilitate the separation of the two-phase solution.

[0046] The present application provides a centrifugal liquid-liquid phase separation system, including a raw material tank 1, a booster pump 2, a cooler 3, a spiral phase separation pipeline 4, a heavy phase extraction valve 5, a heavy phase extraction sensor 6, a light phase extraction valve 8, a light phase extraction sensor 7 and a reflux valve 9. The liquid outlet of the raw material tank 1 is connected to the liquid inlet of the cooler 3 through the booster pump 2. The cooler 3 is used to cool the solution discharged from the raw material tank 1; the liquid outlet of the cooler 3 is connected to the liquid inlet of the spiral phase separation pipeline 4. The spiral phase separation pipeline 4 is a spiral multi-layer pipeline. The spiral phase separation pipeline 4 is Heavy phase production outlets are arranged at corresponding positions on the outer walls of different layers of pipelines, and the heavy phase production outlets are connected to the heavy phase production pipe. A heavy phase production sensor 6 and a heavy phase production valve 5 are arranged at the heavy phase production outlet. The liquid outlet of the spiral phase-separating pipeline 4 is connected in parallel with the light phase production pipe and the reflux pipe. The light phase production pipe and the reflux pipe are respectively provided with a light phase production valve 8 and a reflux valve 9. A light phase production sensor 7 is arranged at the liquid outlet of the spiral phase-separating pipeline 4. The light phase production sensor 7 is connected to the light phase production valve 8 and the reflux valve 9. The reflux pipe is connected to the liquid inlet of the raw material tank 1.

[0047] The two-phase solution discharged from the raw material tank 1 enters the cooler 3 through the booster pump 2 to cool down and increase the density difference of the two-phase solution; the cooled two-phase solution enters the spiral phase separation pipeline 4. Since the heavy phase solution has a larger density and is subjected to a larger centrifugal force, it flows away from the central axis of rotation and along the outer edge wall of the curved flow channel in the spiral phase separation pipeline 4; the light phase solution has a smaller density and is subjected to a relatively smaller centrifugal force, and flows close to the inner edge wall of the curved flow channel. Thus, the separation of the heavy phase solution and the light phase solution is achieved.

[0048] Different from the flow in a straight pipe, when the solution moves in a curved pipe or curved flow channel, under the action of various forces such as centrifugal force and Coriolis force, the flow velocity and centrifugal force of the fluid near the center of the pipe are large, so that the pressure increment along the centerline area is greater than the pressure increment near the pipe wall area, causing the central fluid to flow near the pipe wall, and the fluid near the pipe wall continues to flow toward the central area under the action of centrifugal force, thereby forming two secondary flow vortices with opposite rotation directions in the flow channel section, namely Dean vortices. Dean vortices will intensify the mixing between the fluids in the pipe. From the perspective of enhancing heat transfer and enhancing mass transfer, the existence of Dean vortices is beneficial; however, from the perspective of separation, the existence of Dean vortices is disadvantageous, which will cause secondary back mixing between the separated fluids in the rotating flow channel, which is not conducive to the improvement of the separation efficiency and separation purity of the liquid-liquid phase separator. Therefore, the present application sets an anti-vortex baffle 41 in the pipe of the spiral phase separation pipe 4. The anti-vortex baffle 41 is horizontally arranged on the inner wall of the spiral phase separation pipe 4 and runs through the entire spiral phase separation pipe 4. The anti-vortex baffle 41 here can be set as one or two. When set as one, the anti-vortex baffle 41 can be connected to the inner wall on either side of the spiral phase-separated pipe 4, or can be connected to the inner wall on both sides of the spiral phase-separated pipe 4.

[0049] The density difference on the solution flow channel caused by centrifugal vortex is the basic condition for achieving liquid-liquid two-phase separation. In order to achieve the final separation of the solution, the separated solution in the pipeline needs to be extracted in time. The extraction time and extraction amount of heavy phase and light phase solution can be determined based on the solution density, thermal conductivity, viscosity, conductivity, refractive index, pH and other physical properties. Taking refrigerant R22 and mineral refrigeration oil 3GS as examples, their physical properties at 25°C are shown in Table 1.

[0050] Table 1

[0051]

[0052] As can be seen from Table 1, for refrigerant R22 and mineral refrigeration oil 3GS, it is more advantageous to use viscosity as the extraction index. Of course, for other two-phase systems, other physical properties such as density and conductivity may also be used as extraction indicators. Example 1

[0053] like Figure 1 A centrifugal liquid-liquid phase separation system includes a raw material tank 1, a booster pump 2, a cooler 3, a spiral phase separation pipeline 4, a heavy phase production valve 5, a heavy phase production sensor 6, a light phase production valve 8, a light phase production sensor 7 and a reflux valve 9.

[0054] The raw material tank 1 stores a two-phase mixed solution of refrigerant R22 and mineral refrigeration oil 3GS. The refrigerant R22 and the mineral refrigeration oil 3GS are immiscible. The temperature of the two-phase mixed solution is 80° C., and the volume ratio of the refrigerant R22 to the mineral refrigeration oil 3GS is approximately 1:1.

[0055] The raw material tank 1 is provided with a feed port, a discharge port and a reflux port. The liquid outlet of the raw material tank 1 is connected to the liquid inlet of the cooler 3 through a booster pump 2, and the volume flow rate is 20m 3 / h, the cooler 3 is used to cool the solution discharged from the raw material tank 1. The cooler 3 here adopts a plate heat exchanger. After cooling by the cooler 3, the temperature of the two-phase mixed solution is close to 30°C.

[0056] The liquid outlet of the cooler 3 is connected to the liquid inlet of the spiral phase-separating pipeline 4. The spiral phase-separating pipeline 4 is a spiral multi-layer pipeline. The spiral phase-separating pipeline 4 is provided with a heavy phase extraction port at the corresponding position of the outer wall of different layers of pipelines. The heavy phase extraction port is usually located in the middle position of the outer wall of each layer of pipelines. The heavy phase extraction port is connected to the heavy phase extraction pipe. The heavy phase extraction port is provided with a heavy phase extraction sensor 6 and a heavy phase extraction valve 5. In this embodiment, the spiral phase-separating pipeline 4 is a vortex spiral multi-layer structure. The vortex spiral multi-layer structure is a combination of a spiral tube and a vortex tube. The pipeline adopts a DN50 equal-diameter circular tube. Each layer of the spiral phase-separating pipeline 4 is at a different height. From the liquid inlet to the liquid outlet, the height increases successively, and the projected diameter decreases successively. The projected diameter of the pipeline where the liquid inlet of the spiral phase-separating pipeline 4 is located is 1000mm, and the projected diameter of the pipeline where the liquid outlet is located is 300mm. The heavy phase extraction port is intermittently arranged at the middle position of the outer wall of each layer of pipelines, or at the corresponding position of the outer wall of each layer of pipelines. A heavy phase production sensor 6 is provided at the heavy phase production outlet. Since each layer is provided with a heavy phase production outlet, a heavy phase production sensor 6 and a heavy phase production valve 5 are provided at the heavy phase production outlet. Then, each heavy phase production branch pipeline is merged into a heavy phase production pipe.

[0057] The liquid outlet of the spiral phase-separation pipeline 4 is connected in parallel with a light phase production pipe and a reflux pipe, on which a light phase production valve 8 and a reflux valve 9 are respectively provided. A light phase production sensor 7 is provided at the liquid outlet of the spiral phase-separation pipeline 4, and the light phase production sensor 7 is connected to the light phase production valve 8 and the reflux valve 9. The reflux pipe is connected to the liquid inlet of the raw material tank 1.

[0058] The above-mentioned heavy phase extraction sensor 6 and light phase extraction sensor 7 are both density sensors. The above-mentioned heavy phase extraction valve 5, light phase extraction valve 8 and reflux valve 9 are all proportional regulating valves.

[0059] like Figure 2 As shown, an anti-vortex baffle 41 is arranged in the spiral phase-splitting pipeline 4. The anti-vortex baffle 41 is arranged horizontally on the inner side wall of the spiral phase-splitting pipeline 4 and runs through the entire spiral phase-splitting pipeline 4. There are many ways to arrange the anti-vortex baffle 41. Only one anti-vortex baffle 41 can be arranged, and the entire anti-vortex baffle 41 runs through the entire spiral phase-splitting pipeline 4. It can also be arranged as two anti-vortex baffles 41, and the two anti-vortex baffles 41 are arranged in parallel on the same side of the spiral phase-splitting pipeline 4; of course, the anti-vortex baffle 41 can be connected to only one end side wall of the spiral phase-splitting pipeline 4, or it can be connected to the two end side walls of the spiral phase-splitting pipeline 4 respectively.

[0060] The cross-sectional shape of the spiral phase-splitting pipeline 4 is not limited. Figure 3 As shown, it can be circular, oval, triangular, square or irregular.

[0061] The working method of this embodiment is as follows:

[0062] The mixed solution in the raw material tank 1 is pressurized by the booster pump 2 and then enters the cooler 3. The rated flow rate of the booster pump 2 is 25m 3 / h, the 80℃ solution is cooled to 30℃ by circulating water, and then enters the spiral phase separation pipe 4. The inlet flow rate of the spiral phase separation pipe 4 is about 3m / s. The mixed solution of R22 and mineral refrigeration oil 3GS enters the vortex spiral tube and swirls. At 30℃, the density of R22 is greater than the density of refrigeration oil, and its swirl centrifugal force is greater than the centrifugal force of refrigeration oil. R22 is enriched on the outer wall of the swirl pipe. The density of the solution at each heavy phase extraction port is monitored by a density sensor. When the detected density is not lower than the required density of R22 purity (for example, when the purity requirement of R22 is 90%, the extraction density ≥ density (R22) × 90% + density (refrigeration oil) × 10%) , open the heavy phase production valve 5 corresponding to the production pipe; and determine the opening ratio of the five heavy phase production valves 5 from the inlet to the outlet of the spiral phase-separation pipeline 4, such as 100%, 80%, 60%, 40%, and 20% respectively; the opening ratio here can be adjusted according to experience, or it can be controlled in real time with the help of PID algorithm. The light phase production sensor 7 at the outlet of the spiral phase-separation pipeline 4 monitors the density of the outlet solution and operates in a partial reflux mode. When the density of the outlet solution meets the requirements, the refrigeration oil is produced. According to experience, the opening ratio of the light phase production valve 8 is 80%, and the opening ratio of the reflux valve 9 is 10%. The reflux liquid returns to the raw material tank 1, and this cycle repeats.

[0063] The projected diameter of the pipe at the layer where the liquid outlet is located is set to be lower than the projected diameter of the pipe at the layer where the liquid inlet is located, which overcomes the problem of reduced flow rate, reduced flow velocity and reduced centrifugal force at the liquid outlet, and helps to improve the separation efficiency and separation purity under low flow rate conditions at the liquid outlet. Example 2

[0064] like Figure 4 A centrifugal liquid-liquid phase separation system includes a raw material tank 1, a booster pump 2, a cooler 3, a spiral phase separation pipeline 4, a heavy phase production valve 5, a heavy phase production sensor 6, a light phase production valve 8, a light phase production sensor 7 and a reflux valve 9.

[0065] The raw material tank 1 stores a partially miscible methanol-n-hexane mixed solution with fluctuating raw material component ratios, wherein the mass content of methanol is 10%-90%.

[0066] The raw material tank 1 is provided with a feed port, a discharge port and a reflux port. The liquid outlet of the raw material tank 1 is connected to the liquid inlet of the cooler 3 through the booster pump 2. The cooler 3 is used to cool the solution discharged from the raw material tank 1. The cooler 3 here adopts a shell-and-tube heat exchanger. After cooling by the cooler 3, the temperature of the two-phase mixed solution is close to 25°C. At this time, the density of pure methanol is 789kg / m 3, the density of pure n-hexane is 656 kg / m 3 ; Since methanol and n-hexane are partially miscible, the methanol content in the conjugate solution at 25°C is 60% by mass and the density is 735 kg / m 3 , viscosity is 0.54cP; the other phase of the conjugate solution, that is, the methanol content in the n-hexane-rich solution is 5% and the density is 662kg / m 3 , viscosity is 0.29cP.

[0067] The liquid outlet of the cooler 3 is connected to the liquid inlet of the spiral phase-separating pipe 4. The spiral phase-separating pipe 4 is a spiral multi-layer pipe. The spiral phase-separating pipe 4 is provided with heavy phase extraction outlets at corresponding positions on the outer walls of different layers of pipes. The heavy phase extraction outlets are connected to the heavy phase extraction pipe. The heavy phase extraction outlets are provided with heavy phase extraction sensors 6 and heavy phase extraction valves 5. The spiral phase-separating pipe 4 is a vortex tubular multi-layer structure. Each layer of the spiral phase-separating pipe 4 is located in the same plane. The liquid inlet of the spiral phase-separating pipe 4 is located in the outermost circle, and the liquid outlet of the spiral phase-separating pipe 4 is located in the innermost circle. The spiral phase-separating pipe 4 adopts an equal-diameter circular pipe. Two anti-vortex baffles 41 are arranged in the pipe along the material flow direction. The anti-vortex baffles 41 are horizontally placed on the inner wall of the pipe.

[0068] The pipeline adopts DN50 equal diameter round pipe. The heavy phase production outlet is intermittently arranged at the middle position of the outer wall of each layer of the pipeline, or at the corresponding position of the outer wall of each layer of the pipeline. A heavy phase production sensor 6 is arranged at the heavy phase production outlet. Since each layer is provided with a heavy phase production outlet, a heavy phase production sensor 6 and a heavy phase production valve 5 are arranged at the heavy phase production outlet, and then each heavy phase production branch pipeline is merged into a heavy phase production pipe.

[0069] The liquid outlet of the spiral phase-separation pipeline 4 is connected in parallel with a light phase production pipe and a reflux pipe, on which a light phase production valve 8 and a reflux valve 9 are respectively provided. A light phase production sensor 7 is provided at the liquid outlet of the spiral phase-separation pipeline 4, and the light phase production sensor 7 is connected to the light phase production valve 8 and the reflux valve 9. The reflux pipe is connected to the liquid inlet of the raw material tank 1.

[0070] The above-mentioned heavy phase production sensor 6 and light phase production sensor 7 are both viscosity sensors. The above-mentioned heavy phase production valve 5, light phase production valve 8 and reflux valve 9 are all proportional regulating valves.

[0071] The working method of this embodiment is as follows:

[0072] The mixed solution in the raw material tank 1 is pressurized by the booster pump 2 and then enters the cooler 3. The feed is cooled to 25°C by low-temperature water. The mixed solution enters the spiral phase-separation pipe 4 and swirls. The methanol-rich solution with a higher density is enriched on the outer wall of the vortex tube, while the n-hexane-rich solution is enriched on the inner wall of the flow channel section of the vortex tube. The viscosity of the heavy phase solution outside the vortex tube is collected by a viscometer. When the measured viscosity is greater than 0.54cP, the corresponding heavy phase extraction valve 5 is opened. When the light phase viscosity sensor at the outlet of the spiral phase-separation pipe 4 measures a viscosity lower than 0.29cP, the light phase extraction valve 8 is opened. When the viscosity of the light phase solution at the outlet of the spiral phase-separation pipe 4 is greater than 0.29cP, the reflux valve 9 is opened. The on-off and opening of the heavy phase extraction valve 5, the light phase extraction valve 8 and the reflux valve 9 can be intelligently controlled according to the changes in the viscometer signal through the PID algorithm. Here, the on-off control of the heavy phase production valve 5, the light phase production valve 8 and the reflux valve 9 by the PID algorithm is a conventional application of the prior art; of course, manual control can also be performed according to the values ​​displayed by the sensors.

[0073] The spiral phase separation pipeline 4 of this embodiment adopts a vortex tubular structure and uses a viscosity index with significant difference as a characterization parameter for judging the purity of light and heavy phase solutions. It can be applied to applications where the feed composition is unstable, the feed flow is prone to fluctuations, and the density difference of the solutions to be separated is not large. Example 3

[0074] like Figure 5 A centrifugal liquid-liquid phase separation system includes a raw material tank 1, a booster pump 2, a cooler 3, a spiral phase separation pipeline 4, a heavy phase production valve 5, a heavy phase production sensor 6, a light phase production valve 8, a light phase production sensor 7 and a reflux valve 9.

[0075] The raw material tank 1 stores ethyl acetate-water solution, which is an azeotropic partially miscible solution. Under normal temperature conditions, the density of ethyl acetate is 900 kg / m 3 , the density of water is 1000kg / m 3 In the conjugate solution formed under the phase equilibrium conditions, the mass content of ethyl acetate in the ethyl acetate-rich phase is 92%, and the mass content of ethyl acetate in the water-rich phase is 4%.

[0076] The raw material tank 1 is provided with a feed port, a discharge port and a reflux port. The liquid outlet of the raw material tank 1 is connected to the liquid inlet of the cooler 3 through the booster pump 2. The cooler 3 is used to cool the solution discharged from the raw material tank 1. The cooler 3 here adopts a shell and tube heat exchanger. After cooling by the cooler 3, the temperature of the two-phase mixed solution is close to 25°C.

[0077] The liquid outlet of the cooler 3 is connected to the liquid inlet of the spiral phase-separating pipeline 4. The spiral phase-separating pipeline 4 is a spiral multi-layer pipeline. The spiral phase-separating pipeline 4 is provided with heavy phase production outlets at corresponding positions on the outer walls of different layers of pipelines. The heavy phase production outlets are connected to the heavy phase production pipe. The heavy phase production outlets are provided with heavy phase production sensors 6 and heavy phase production valves 5. The spiral phase-separating pipeline 4 is a spiral tube-shaped multi-layer structure. Each layer of the spiral phase-separating pipeline 4 is at a different height, and the projected diameter of each layer of the spiral phase-separating pipeline 4 is the same. The spiral phase-separating pipeline 4 adopts an elliptical tube, the long axis of the ellipse is in the horizontal direction, and an anti-vortex baffle 41 is provided in the pipeline, and the anti-vortex baffle 41 is horizontally placed on the inner wall of the pipeline.

[0078] The heavy phase production outlet is intermittently arranged at the middle position of the outer wall of each layer of the pipeline, or at the corresponding position of the outer wall of each layer of the pipeline. A heavy phase production sensor 6 is arranged at the heavy phase production outlet. Since each layer is provided with a heavy phase production outlet, a heavy phase production sensor 6 and a heavy phase production valve 5 are arranged at the heavy phase production outlet, and then each heavy phase production branch pipeline is merged into a heavy phase production pipe.

[0079] The liquid outlet of the spiral phase-separation pipeline 4 is connected in parallel with a light phase production pipe and a reflux pipe, on which a light phase production valve 8 and a reflux valve 9 are respectively provided. A light phase production sensor 7 is provided at the liquid outlet of the spiral phase-separation pipeline 4, and the light phase production sensor 7 is connected to the light phase production valve 8 and the reflux valve 9. The reflux pipe is connected to the liquid inlet of the raw material tank 1.

[0080] The above-mentioned heavy phase extraction sensor 6 and light phase extraction sensor 7 are both density sensors. The above-mentioned heavy phase extraction valve 5, light phase extraction valve 8 and reflux valve 9 are all proportional regulating valves.

[0081] The working method of this embodiment is as follows:

[0082] The ethyl acetate mixed solution in the raw material tank 1 is pressurized by the booster pump 2 and then enters the cooler 3. The feed is cooled to room temperature by circulating water. Then the mixed solution enters the spiral pipe of the spiral phase separation pipe 4 for vortex centrifugation. The water with higher density is enriched on the outer side of the oval pipe, and the ethyl acetate with relatively lower density is enriched on the inner side of the oval pipe. The density of the heavy phase outlet solution is detected by the heavy phase sensor, and the density of the light phase outlet solution is detected by the light phase sensor, so as to realize the extraction of the heavy phase solution and the light phase solution.

[0083] The spiral phase separation pipe 4 of this embodiment adopts an elliptical spiral tube. The long axis direction of the elliptical tube is consistent with the direction of centrifugal force. The elliptical structure is beneficial to reducing the secondary flow and Dean vortex generated by the vortex of the solution in the tube, thereby improving the separation efficiency and separation purity. Example 4

[0084] like Figure 6, which is different from Example 1, the spiral phase separation pipeline 4 needs to be jointly enclosed with the inner wall of the phase separator to form a centrifugal flow channel. The lower part of the phase separator is the feed port, the upper part is the light phase discharge port, and the heavy phase production port is intermittently arranged outside the phase separator, that is, the outer wall of the swirl channel. The cross-section of the spiral flow channel is rectangular, and a tapered flow channel is adopted, that is, as the spiral flow channel is increased, the flow channel area is proportionally reduced. The rectangular flow channel is provided with a plurality of anti-vortex baffles 41 along the material flow direction, and the anti-vortex baffles 41 are horizontally placed on the inner wall of each layer of the flow channel. The heavy phase production sensor 6 and the light phase production sensor 7 both adopt conductivity sensors.

[0085] This embodiment uses a spiral phase separation pipe 4 and a phase separator to jointly construct a centrifugal flow channel, and adopts a flow channel design with a tapered cross-section. The variable flow channel cross-section can ensure that the tail section flow channel still has a high flow rate and centrifugal force. This embodiment is particularly suitable for applications with large feed volumes.

[0086] The preferred specific embodiments of the present invention are described in detail above. It should be understood that ordinary technicians in the field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in the technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A centrifugal liquid-liquid phase separation system, characterized in that: It includes a raw material tank, a booster pump, a cooler, a spiral phase separation pipeline, a heavy phase production valve, a heavy phase production sensor, a light phase production valve, a light phase production sensor and a reflux valve. The liquid outlet of the raw material tank is connected to the liquid inlet of the cooler through a booster pump, and the cooler is used to cool the solution discharged from the raw material tank; The liquid outlet of the cooler is connected to the liquid inlet of the spiral phase-separation pipeline. The side wall of the spiral phase-separation pipeline is provided with an anti-vortex baffle to avoid pulsation and back-mixing between stratified solutions caused by secondary flow and Dean vortex when the solution flows in a curved manner. The spiral phase-separation pipeline is a spiral multi-layer pipeline. The spiral phase-separation pipeline is provided with heavy phase production outlets at corresponding positions on the outer side walls of different layers of pipelines. The heavy phase production outlet is connected to the heavy phase production pipe. The heavy phase production outlet is provided with a heavy phase production sensor and a heavy phase production valve. The liquid outlet of the spiral phase-separation pipeline is connected in parallel with a light phase production pipe and a reflux pipe, and the light phase production pipe and the reflux pipe are respectively provided with a light phase production valve and a reflux valve. A light phase production sensor is provided at the liquid outlet of the spiral phase-separation pipeline, and the light phase production sensor is connected to the light phase production valve and the reflux valve. The reflux pipe is connected to the liquid inlet of the raw material tank.

2. The centrifugal liquid-liquid phase separation system according to claim 1, characterized in that: Each layer of the spiral phase-separated pipeline is at a different height, and the projected diameter of each layer of the spiral phase-separated pipeline decreases from the liquid inlet to the liquid outlet.

3. The centrifugal liquid-liquid phase separation system according to claim 2, characterized in that: The projected diameter of the pipe at the layer where the liquid inlet of the spiral phase-separated pipe is located is more than 3 times that of the pipe at the layer where the liquid outlet is located.

4. The centrifugal liquid-liquid phase separation system according to claim 1, characterized in that: Each layer of the spiral phase-separation pipeline is located in the same plane, the liquid inlet of the spiral phase-separation pipeline is located in the outermost circle, and the liquid outlet of the spiral phase-separation pipeline is located in the innermost circle.

5. The centrifugal liquid-liquid phase separation system according to claim 1, characterized in that: Each layer of the spiral phase-separated pipeline is at a different height, and each layer of the spiral phase-separated pipeline has the same projected diameter.

6. The centrifugal liquid-liquid phase separation system according to claim 1, characterized in that: The spiral phase-separation pipeline is arranged in the phase separator, and the spiral phase-separation pipeline and the inner wall of the phase separator are surrounded to form a pipeline for solution circulation.

7. The centrifugal liquid-liquid phase separation system according to claim 6, characterized in that: As the height of the layer where the spiral phase-separated pipeline is located increases, the corresponding pipeline area decreases in proportion.

8. The centrifugal liquid-liquid phase separation system according to claim 1, characterized in that: The anti-vortex baffle is horizontally arranged on the inner side wall of the spiral phase-separated pipeline, and the anti-vortex baffle runs through the entire spiral phase-separated pipeline.

9. A centrifugal liquid-liquid phase separation method, characterized in that: The centrifugal liquid-liquid phase separation system according to any one of claims 1 to 8 is used for phase separation, comprising the following steps: S1, discharge the two-phase solution in the raw material tank into the cooler through the booster pump for cooling treatment; S2. The cooled solution enters the spiral phase separation pipe. Under the action of centrifugal force, the two-phase solution is separated into a heavy phase solution and a light phase solution. The heavy phase solution is discharged from the heavy phase extraction pipe, and the light phase solution is discharged from the light phase extraction pipe. The two-phase solution that cannot be separated flows back to the raw material tank from the reflux pipe.

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