Partial mutual solution liquid phase equilibrium test system and test method thereof

Abstract

The invention discloses a partial mutual solution liquid phase balance test system and a test method thereof, the test system comprises a solution supply module, a temperature regulation and control module, a phase splitting module and a test sampling module, the solution supply module comprises a heavy phase solution storage tank, a light phase solution storage tank and a metering pump; the phase splitting module comprises a phase splitter and a circulating pump, and an outlet of the metering pump is connected with an inlet of the circulating pump; the temperature regulation and control module is used for regulating the temperature of a solution entering the phase splitter, an outlet of the circulating pump is connected with an inlet of the temperature regulation and control module, and an outlet of the temperature regulation and control module is connected with a solution inlet of the phase splitter; the test sampling module comprises a light-phase flowmeter, a light-phase densimeter, a light-phase flow regulating valve, a light-phase sampling pipe, a heavy-phase flowmeter, a heavy-phase densimeter, a heavy-phase flow regulating valve and a heavy-phase sampling pipe; and the light-phase solution outlet and the heavy-phase solution outlet of the phase splitter are respectively connected with the inlet of the circulating pump. According to the test system, the split-phase process parameters can be collected in real time, and the test efficiency and precision are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid-liquid separation, and particularly to a partially miscible liquid-liquid phase equilibrium test system and a test method thereof. BACKGROUND

[0002] In the chemical, petroleum, pharmaceutical and other industries, liquid-liquid separation is an important unit operation, and its purpose is to separate two immiscible or partially miscible liquid mixtures. In chemical production, the safe operation temperature zone is determined according to the liquid-liquid phase equilibrium data to avoid the local enrichment of flammable, explosive and toxic components caused by the delamination of partially miscible raw materials. In the field of industrial water treatment, the use of liquid-liquid phase equilibrium data helps to select appropriate treatment methods, improve pollutant removal efficiency, and reduce treatment costs. In the field of biological therapy, the solubility of drugs in oil and water phases is determined through the liquid-liquid phase diagram to optimize the dosage form and improve the bioavailability. In the field of daily chemicals, the product formula and storage temperature are determined through the liquid-liquid phase diagram to ensure the quality stability of cosmetics. The accurate testing of liquid-liquid phase equilibrium data is of great significance to the safety production and new product development in the fields of chemistry, materials, medicine, and chemical industry.

[0003] In the conventional testing process of liquid-liquid phase equilibrium or liquid-liquid phase diagram, the turbidity point observation method is used to determine the phase change process (from completely miscible state to phase separation state or from phase separation state to completely miscible state), which has the problems of low testing accuracy, low efficiency, and strong subjectivity. In addition, the turbidity point observation method is no longer applicable to solution systems with deep color or turbidity critical point not obvious. SUMMARY

[0004] To solve the problems existing in the prior art described above, the present application provides a partially miscible liquid-liquid phase equilibrium test system, which can collect the phase separation process parameters in real time, determine the phase change process through the density changes of the light phase solution outlet and the heavy phase solution outlet of the phase separator, overcome the disadvantages of manual turbidity point determination, and improve the testing efficiency and accuracy. Therefore, the present application also provides a test method for the above test system.

[0005] In a first aspect, the present application provides a partially miscible liquid-liquid phase equilibrium test system, which comprises a solution supply module, a temperature control module, a phase separation module, and a test sampling module, The solution supply module comprises a heavy phase solution storage tank, a light phase solution storage tank, and a metering pump, and the outlets of the heavy phase solution storage tank and the light phase solution storage tank are connected to the inlet of the metering pump; The phase separation module comprises a phase separator and a circulating pump, and the outlet of the metering pump is connected to the inlet of the circulating pump; The temperature control module is used to adjust the temperature of the solution entering the phase separator, the outlet of the circulating pump is connected to the inlet of the temperature control module, and the outlet of the temperature control module is connected to the solution inlet of the phase separator. The test sampling module comprises a light phase flow meter, a light phase density meter, a light phase flow regulating valve and a light phase sampling pipe arranged at the light phase solution outlet of the phase separator, and a heavy phase flow meter, a heavy phase density meter, a heavy phase flow regulating valve and a heavy phase sampling pipe arranged at the heavy phase solution outlet of the phase separator, and the light phase solution outlet and the heavy phase solution outlet of the phase separator are respectively connected with the inlet of the circulating pump.

[0006] As a preferred embodiment, the heavy phase solution tank and the light phase solution tank are respectively provided with a vacuum port connected with a vacuum pump.

[0007] As a preferred embodiment, the temperature control module comprises a heat exchanger, a temperature control pump and a high-low temperature thermostat unit connected in sequence, and the heat exchanger, the temperature control pump and the high-low temperature thermostat unit form a circulation system, the outlet of the circulating pump is connected with the inlet of the heat exchanger, and the outlet of the heat exchanger is connected with the solution inlet of the phase separator.

[0008] As a preferred embodiment, the heavy phase solution tank is provided with a heavy phase solution reflux port, and the light phase solution tank is provided with a light phase solution reflux port; the heavy phase solution outlet of the phase separator is connected with the heavy phase solution reflux port, and a stop valve is arranged on the connecting pipeline; the light phase solution outlet of the phase separator is connected with the light phase solution reflux port, and a stop valve is arranged on the connecting pipeline.

[0009] As a preferred embodiment, the phase separator is a gravity type phase separator or a cyclone type phase separator.

[0010] As a preferred embodiment, the heat exchanger is selected from a plate type, a tube type, a jacket type and a spiral plate type heat exchanger.

[0011] As a preferred embodiment, the heavy phase flow meter and the light phase flow meter are selected from a float type flow meter, an electromagnetic type flow meter, a vortex type flow meter or an ultrasonic wave type flow meter.

[0012] As a preferred embodiment, the heavy phase density meter and the light phase density meter are selected from a tuning fork type density meter.

[0013] As a preferred embodiment, the high-low temperature thermostat unit comprises a plurality of constant temperature water baths connected in sequence, and the temperature control range of the high-low temperature thermostat unit is-80℃-150℃.

[0014] In the second aspect, the application provides a test method for the test method of the partial mutual solution liquid phase equilibrium test system, which comprises the following steps: S1, the heavy phase components in the heavy phase solution tank and the light phase components in the light phase solution tank are respectively discharged into the phase separator through the metering pump, and the mass concentration of the heavy phase components in the phase separator is 40%-60%; S2, the circulating pump and the temperature control module are started; S3. Adjust the temperature of the test solution in the phase separator using the temperature control module to bring the test solution into a phase-separated state. Gradually reduce the opening of the heavy phase flow regulating valve and observe the reading of the heavy phase flow meter. Q 重 and the readings of the phase density meter p 重 ,when p 重 along with Q 重 When the flow rate remains unchanged, stop the adjustment of the heavy phase flow control valve, collect the heavy phase conjugate solution through the heavy phase sampling tube, and test the concentration of the heavy phase component in the heavy phase conjugate solution; restore the heavy phase flow control valve to its initial opening, gradually reduce the opening of the light phase flow control valve, and observe the reading of the light phase flow meter. Q 轻 and light phase density meter readings p 轻 ,when p 轻 along with Q 轻 When the flow rate remains unchanged, stop the adjustment action of the light phase flow regulating valve, collect the light phase conjugate solution by the light phase sampling tube, and test the concentration of the heavy phase component in the light phase conjugate solution; S4. Increase or decrease the temperature of the test solution, repeat step S3, and test the concentration of the heavy phase component in the heavy phase conjugate solution and the light phase conjugate solution at different temperatures; at a specific temperature, ( p 重 - p 轻 ) / p 重 <0.5% and when p 重 along with Q 重、 p 轻 along with Q 轻 When all remain constant, the concentration of the heavy phase component at the highest or lowest melting point is obtained.

[0015] As a preferred embodiment, before step S1, step S0 is also included: a step of evacuating the test system.

[0016] In a preferred embodiment, after step S2, the steps of determining the solution phase region and determining the liquid-liquid phase diagram morphology are further included: Solution phase region determination steps: Adjust the temperature of the test solution in the phase separator to temperature T, and compare the readings with those of the light phase density meter. p 轻 and the readings of the phase density meter p 重 The relationship, if ( p 重 -p 轻 ) / p 重 If <0.5%, then the mixed solution at temperature T is completely miscible; if ( p 重 - p 轻 ) / p 重 When the concentration is ≥0.5%, the mixed solution at temperature T is in a phase-separated state. Liquid-liquid phase diagram morphology determination steps: When the mixed solution at temperature T is in a completely miscible state, raise or lower the temperature of the test solution in the phase separator and compare... p 重 , p 轻 The relationship between the difference and temperature change, if p 重 , p 轻 If the difference between the two values ​​increases with increasing temperature or decreases with decreasing temperature, the mixed solution is determined to be a partially miscible solution with the lowest melting point. When the mixed solution at temperature T is in a phase-separated state, the solution temperature in the phase separator is increased or decreased, and the values ​​are compared. p 重 , p 轻 The relationship between the difference and temperature change, if p 重 , p 轻 The difference between them decreases as the temperature increases or increases as the temperature decreases, and at a specific temperature... p 重 = p 轻 If the test solution is found to be partially miscible with the lowest melting point, then the test solution is determined to be such that it is a partially miscible solution.

[0017] As a preferred embodiment, after step S4, a step of drawing a liquid-liquid phase diagram with the highest melting point temperature or the lowest melting point is also included.

[0018] Beneficial effects: (1) The partial interphase liquid equilibrium test system of the present invention can collect phase separation process parameters in real time and judge the phase change process by the density change of the light phase solution outlet and the heavy phase solution outlet of the phase separator. This overcomes the drawback of manual judgment by turbidity point and improves test efficiency and test accuracy.

[0019] (2) The part of the mutual solution liquid-liquid equilibrium test system in the application runs in a closed state, realizes high-pressure test, and avoids the problem that low-boiling components (such as n-pentane) cannot be liquefied under high-temperature conditions in the conventional method, leading to the difficulty in testing the liquid-liquid phase separation performance.

[0020] (3) The part of the mutual solution liquid-liquid equilibrium test system in the application is in a constant temperature state through the temperature regulation module, and the conjugate solution is collected at the light phase solution outlet and the heavy phase solution outlet of the phase separator to obtain the left curve and the right curve of the liquid-liquid phase diagram and the concentration point of the highest solubility point / lowest solubility point at different temperatures, and the test process is simple and convenient.

[0021] (4) The part of the mutual solution liquid-liquid equilibrium test system in the application can simultaneously collect multiple parameters such as temperature, flow, density and phase separation time, and can obtain multiple performance indicators such as phase separation rate and phase separation efficiency through theoretical calculation, provides test data support for the optimization of liquid-liquid separation process and the design of the phase separator, and can be applied to multiple fields such as chemical industry, petroleum and pharmaceutical industry.

[0022] (5) The part of the mutual solution liquid-liquid equilibrium test system in the application can realize pressure-bearing closed test, avoids the problem of toxic material liquid, and has a wider application range.

[0023] (6) The test method in the application gradually reduces the opening degree of the flow regulating valve on the sampling side during testing, judges the concentration change of the solution on the sampling side through the density change of the sampling side, and obtains the concentration value of the sampling side in the stable state, effectively avoiding the influence of the moving of the stratification interface on the test result.

[0024] (7) The left curve and the right curve of the part of the mutual solution liquid-liquid equilibrium diagram obtained by the test method in the application are only related to the temperature of the solution, and are independent of the initial concentration of the solution, and the mass concentration of 40%-60% of the heavy phase component can cover the concentration requirement of the phase diagram of most phase separation solutions.

[0025] The concept, specific structure and technical effects of the application will be further described below with reference to the accompanying drawings, so as to fully understand the purpose, features and effects of the application. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 The flow chart of the part of the mutual solution liquid-liquid equilibrium test system in the application 1; Figure 2 Partial miscibility liquid phase diagram with the highest consolute point in Example 1; Figure 3 Flow chart of the partial miscibility liquid phase equilibrium test system in Example 2 of the present application; Figure 4 Partial miscibility liquid phase diagram with the lowest consolute point in Example 2.

[0028] Explanation of reference numerals: 1 - heavy phase solution storage tank, 2 - light phase solution storage tank, 3 - vacuum pump, 4 - metering pump, 5 - circulating pump, 6 - heat exchanger, 7 - temperature control pump, 8 - high and low temperature thermostat unit, 9 - phase separator, 10 - light phase flow meter, 11 - light phase densimeter, 12 - light phase flow regulating valve, 13 - heavy phase flow meter, 14 - heavy phase densimeter, 15 - heavy phase flow regulating valve, 16 - light phase sampling pipe, 17 - heavy phase sampling pipe. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0030] The terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, if the term "multiple" appears, the meaning of "multiple" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0031] In the present application, unless otherwise explicitly specified and limited, if the terms "mounting", "connection", "connecting", "fixing" and the like appear, these terms should be understood in a broad sense. For example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] If an element is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element, or intervening elements can be present. If an element is referred to as being "connected" to another element, it can be directly connected to the other element, or intervening elements can be present. As used herein, the terms "vertical", "horizontal", "upper", "lower", "left", "right", and similar terms are used for explanation only and are not intended to be limiting.

[0033] For partially miscible solutions, accurate testing of liquid-liquid phase diagrams or liquid-liquid phase equilibrium data is of great significance to the safety production and new product development in the fields of chemistry, materials, medicine, chemical industry, etc. The traditional method determines whether the test solution is in a phase separation state or a completely miscible state by observing the cloud point, which is highly subjective and has low testing accuracy.

[0034] The present application provides a partially miscible solution liquid phase equilibrium testing system, comprising a solution supply module, a phase separation module, a temperature control module and a testing and sampling module.

[0035] The solution supply module is used for delivering two test solutions to the phase separation module, and comprises a heavy phase solution storage tank, a light phase solution storage tank and a metering pump.

[0036] The phase separation module is used for fully mixing and separating the two test solutions, and comprises a phase separator and a circulating pump.

[0037] The temperature control module is used for controlling the temperature of the test solution in the phase separator, and comprises a heat exchanger, a temperature control pump and a high-low temperature thermostat unit connected in sequence.

[0038] The heat exchanger is selected from a plate type, a tube type, a jacket type and a spiral plate type heat exchanger.

[0039] The test sampling module is used for collecting flow, density and phase diagram data in real time during the phase separation test process, and comprises a light phase flow meter, a light phase density meter, a light phase flow regulating valve and a light phase sampling pipe arranged at the light phase solution outlet of the phase separator, and a heavy phase flow meter, a heavy phase density meter, a heavy phase flow regulating valve and a heavy phase sampling pipe arranged at the heavy phase solution outlet of the phase separator, wherein the light phase flow meter and the heavy phase flow meter are selected from a float type flow meter, an electromagnetic flow meter, a vortex flow meter or an ultrasonic flow meter, and the heavy phase density meter and the light phase density meter are selected from a tuning fork type density meter.

[0040] During the test process, the circulating pump is in an open state, and the test solution is circulated in the phase separator and the temperature control module.

[0041] The heavy phase solution tank and the light phase solution tank are respectively provided with vacuum ports connected with a vacuum pump.

[0042] The vacuum pump is arranged to perform vacuumizing on the whole test system before filling.

[0043] The heavy phase solution tank is provided with a heavy phase solution backflow port, and the light phase solution tank is provided with a light phase solution backflow port; the heavy phase solution outlet of the phase separator is connected with the heavy phase solution backflow port, and a stop valve is arranged on the connecting pipeline; the light phase solution outlet of the phase separator is connected with the light phase solution backflow port, and a stop valve is arranged on the connecting pipeline.

[0044] The heavy phase solution backflow port and the light phase solution backflow port are arranged to adjust the content of the heavy phase component or the light phase component in the test solution, so that the phase diagram of the test solution under different compositions is obtained, and the stability of the test system and the accuracy of the test result are evaluated.

[0045] The application further provides a test method of the test system. In the first step, the vacuum pump is connected with the vacuum ports in the heavy phase solution tank and the light phase solution tank to perform vacuumizing on the system.

[0046] In the second step, the heavy phase component in the heavy phase solution tank and the light phase component in the light phase solution tank are respectively discharged into the phase separator through the metering pump, and the mass concentration of the heavy phase component in the phase separator is 40%-60%.

[0047] Under the initial concentration, most of the liquid-liquid phase diagram tests of the partially miscible solution can meet the requirements.

[0048] The light phase component refers to a relatively low boiling point component, and the heavy phase component refers to a relatively high boiling point component. Taking n-pentane-DMF as an example, the light phase component is n-pentane, and the heavy phase component is DMF. In the isopropylamine-water system, the light phase component is isopropylamine, and the heavy phase component is water.

[0049] Third step, start the circulating pump and temperature control module.

[0050] Fourth step, test the solution phase area judgment, the specific judgment criteria are: adjust the temperature of the test solution in the phase separator to temperature T, compare the difference between the light phase density meter reading p 轻 and the heavy phase density meter reading p 重 , if ( p 重 - p 轻 ) / ( p 重 <0.5%, p 重 - p 轻 ) / ( p 重 ≥0.5%,

[0051] then the mixed solution at temperature T is in a completely miscible state; if ( p 重 , p 轻 ) / ( p 重 , p 轻 ) is greater or less as the temperature increases or decreases, then the mixed solution is a partially miscible solution with the lowest consolute point; when the mixed solution at temperature T is in a phase separation state, increase or decrease the temperature of the solution in the phase separator, compare the difference between p 重 , p 轻 and the change in temperature, if ( p 重 , p 轻 ) decreases as the temperature increases or increases as the temperature decreases, and at a certain temperature p 重 = p 轻 , then the mixed solution is a partially miscible solution with the highest consolute point.

[0052] By following the steps above, it can be directly determined whether the test solution is a partially miscible solution with the lowest melting point or a partially miscible solution with the highest melting point. Of course, even without determining the solution phase region and liquid-liquid phase diagram morphology, subsequent testing steps alone can distinguish between partially miscible solutions with the lowest melting point and partially miscible solutions with the highest melting point.

[0053] Step 6: Adjust the temperature of the test solution inside the phase separator using the temperature control module to bring the test solution into a phase-separated state. Gradually reduce the opening of the heavy phase flow regulating valve and observe the reading of the heavy phase flow meter. Q 重 and the readings of the phase density meter p 重 ,when p 重 along with Q 重 When the flow rate remains unchanged, stop the adjustment of the heavy phase flow control valve, collect the heavy phase conjugate solution through the heavy phase sampling tube, and test the concentration of the heavy phase component in the heavy phase conjugate solution; restore the heavy phase flow control valve to its initial opening, gradually reduce the opening of the light phase flow control valve, and observe the reading of the light phase flow meter. Q 轻 and light phase density meter readings p 轻 ,when p 轻 along with Q 轻 When the flow rate remains unchanged, stop the adjustment action of the light phase flow regulating valve, collect the light phase conjugate solution by the light phase sampling tube, and test the concentration of the heavy phase component in the light phase conjugate solution.

[0054] The temperature of the test solution inside the phase separator is adjusted by the temperature control module, such as T', to bring the test solution into a phase-separated state. The opening of the heavy phase flow regulating valve is gradually reduced, while the opening of the light phase flow regulating valve is maintained at its initial state. Because the test solution inside the phase separator is constantly circulating, the phase separation interface will gradually shift towards the light phase component. The flow rates are read by the heavy phase flow meter and the heavy phase density meter, respectively. Q 重 and density value p 重 ,when p 重 along with Q 重 When the flow rate remains constant, the adjustment of the heavy phase flow control valve is stopped, and the heavy phase conjugate solution is collected by the heavy phase sampling tube to test the concentration of the heavy phase component in the heavy phase conjugate solution. When testing the content of each component in the heavy phase conjugate solution, the opening of the heavy phase flow control valve is reduced to effectively avoid the influence of liquid level fluctuations on sampling and ensure the accuracy of the test.

[0055] Conversely, when the concentration of the heavy phase component in the light phase conjugate solution needs to be tested, the opening of the light phase flow regulating valve is gradually reduced in the same way, and the opening of the heavy phase flow regulating valve is maintained at the initial state.

[0056] Step 7, the temperature of the test solution is increased or decreased, and step 6 is repeated to test the concentration of the heavy phase component in the heavy phase conjugate solution and the light phase conjugate solution at different temperatures; when the temperature is a certain temperature, p 重 - p 轻 ) / p 重 <0.5% and when p 重 With Q 重、 p 轻 With Q 轻 The concentration of the heavy phase component at the highest or lowest solubility point is obtained when the heavy phase component concentration is not changed.

[0057] Thus, taking the temperature T' of the test solution as an example, the concentration values of the light phase conjugate solution and the heavy phase conjugate solution at T', T'+△T', T'-△T' can be obtained, and a phase diagram curve of temperature vs. heavy phase component concentration can be drawn.

[0058] Example 1 This example takes the liquid-liquid phase equilibrium test of n-heptane-DMF as an example to introduce the liquid-liquid phase equilibrium test system and the test method of the liquid-liquid phase diagram with the highest solubility point.

[0059] As p , the liquid-liquid phase equilibrium test system of the partially miscible solution includes a solution supply module, a temperature control module, a phase separation module, and a test sampling module.

[0060] The solution supply module is used to deliver two test solutions to the phase separation module, and includes a heavy phase solution tank 1, a light phase solution tank 2, a vacuum pump 3, and a metering pump 4. The heavy phase solution tank 1 and the light phase solution tank 2 are each provided with a discharge port, a reflux port, a vacuum port, and a charging port; the discharge port of the heavy phase solution tank 1 is connected to the inlet of the metering pump 4, and a stop valve is arranged on the connecting pipeline; the discharge port of the light phase solution tank 2 is connected to the inlet of the metering pump 4, and a stop valve is arranged on the connecting pipeline; the vacuum port of the heavy phase solution tank 1 and the vacuum port of the light phase solution tank 2 are both connected to the vacuum pump 3; and the outlet of the metering pump 4 is connected to the inlet of a circulating pump 5, and a stop valve is arranged on the connecting pipeline.

[0061] The temperature control module is used for controlling the solution temperature of the liquid-liquid phase separation test, and comprises a high-low temperature thermostat unit 8, a temperature control pump 7 and a heat exchanger 6. The high-low temperature thermostat unit 8, the heat exchanger 6 and the temperature control pump 7 are sequentially connected in a head-to-tail mode to form a closed circulation loop. The high-low temperature thermostat unit 8 is composed of multiple constant temperature water baths which are sequentially connected in series. The series loop is filled with a heat carrier, and the heat carrier is water. The test solution is sequentially introduced into each constant temperature water bath under the action of the temperature control pump 7 to perform heating or cooling operation on the test solution. The outlet of the circulation pump 5 is connected with the liquid inlet of the heat exchanger 6. Of course, the high-low temperature thermostat unit 8 can also be only one constant temperature water bath when the power reaches the expectation.

[0062] The phase separation module is used for sufficiently mixing and separating two test solutions, and comprises a phase separator 9 and a circulation pump 5.

[0063] The test sampling module is used for collecting the flow and density parameters of the phase separation test in real time, determining the phase diagram data of the layered conjugate phase solution through sampling test, and comprises a light phase flow meter 10, a light phase densimeter 11, a light phase flow regulating valve 12, a heavy phase flow meter 13, a heavy phase densimeter 14, a heavy phase flow regulating valve 15, a light phase sampling pipe 16 and a heavy phase sampling pipe 17.

[0064] The phase separator 9 adopts a gravity type phase separator, the side wall of which is provided with a solution inlet, the top portion of which is provided with a light phase solution outlet, and the bottom portion of which is provided with a heavy phase solution outlet. The liquid outlet of the heat exchanger 6 is connected with the solution inlet of the phase separator 9. The light phase outlet pipe of the phase separator 9 is provided with the light phase flow meter 10, the light phase densimeter 11 and the light phase flow regulating valve 12, and the light phase sampling pipe 16 is arranged. The heavy phase outlet pipe of the phase separator 9 is provided with the heavy phase flow meter 13, the heavy phase densimeter 14 and the heavy phase flow regulating valve 15, and the heavy phase sampling pipe 17 is arranged.

[0065] The light phase outlet pipe and the heavy phase outlet pipe of the phase separator 9 are connected with the inlet of the circulation pump 5 after being merged. The light phase outlet pipe of the phase separator 9 is connected with the backflow port of the light phase solution storage tank 2, and a stop valve is arranged on the connecting pipeline. The heavy phase outlet pipe of the phase separator 9 is connected with the backflow port of the heavy phase solution storage tank 1, and a stop valve is arranged on the connecting pipeline.

[0066] The heat exchanger 6 of the embodiment adopts a plate type heat exchanger. The phase separator 9 can adopt a gravity type phase separator. The light phase flow meter 10 and the heavy phase flow meter 13 adopt float type flow meters, and the test accuracy is ±0.5%. The light phase densimeter 11 and the heavy phase densimeter 14 can adopt tuning fork type densimeters, and the test accuracy is ±0.00001 g / cm 3The high and low temperature thermostat unit 8 adopts a constant temperature water bath unit, the temperature control range is -30°C~100°C, and the temperature control precision is ±0.1°C; the vacuum pump 3 adopts a dry screw vacuum pump.

[0067] The test method and specific steps of the embodiment are as follows: The volume of the phase separator 9 is calibrated with pure water, and then the water is discharged. The vacuum pump 3 is started to vacuumize the light phase solution storage tank 2, the heavy phase solution storage tank 1, the phase separation module and the connecting pipeline, and when the absolute pressure is 0.5 kPa, the vacuum pump is closed. The light phase solution storage tank 2 is filled with n-pentane, and the heavy phase solution storage tank 1 is filled with DMF.

[0068] The valve of the heavy phase solution storage tank 1 is opened, the metering pump 4 is started, and DMF is injected into the phase separation module. Then the valve of the heavy phase solution storage tank 1 is closed, and the valve of the light phase solution storage tank 2 is opened. The metering pump 4 is used to supplement n-pentane into the phase separation module, and the mass concentration of DMF in the phase separation module is adjusted. n 0 ≈50%.

[0069] The circulating pump 5 is started to make the test solution in the phase separation module circulate, the high and low temperature thermostat unit 8 and the temperature control pump 7 are started, the inlet solution temperature of the phase separator 9 is set to 30°C, the opening degrees of the light phase flow regulating valve 12 and the heavy phase flow regulating valve 15 are jointly adjusted, the light phase solution flow and the heavy phase solution flow are changed, and it is found that during the flow adjustment process, the lower limit value of the light phase solution density is 634 kg / m 3 , the upper limit value of the heavy phase solution density is 887 kg / m 3 , and the difference between the extreme values of the light and heavy phase densities is 253 kg / m 3 ; when the test solution is heated to 50°C, the lower limit value of the light phase solution density under the flow regulation of the phase separator 9 is 626 kg / m 3 , the upper limit value of the heavy phase solution density is 833 kg / m 3 , and the difference between the extreme values of the light and heavy phase densities is 207 kg / m 3 ; that is, as the test solution is heated, the difference between the light and heavy phase densities gradually decreases, and it is preliminarily determined that n-pentane-DMF is a partially miscible solution with the highest consolute temperature. When the test solution is continuously heated to 77.5°C, it is found that the light phase solution density and the heavy phase solution density of the phase separator are consistent, both are 698 kg / m 3 , and the density value is independent of the flow, which indicates that the test solution enters a completely miscible state. Thus, it is determined that the n-pentane-DMF solution is a partially miscible solution with the highest consolute temperature, and the liquid-liquid phase diagram opens downward.

[0070] The temperature of the test solution is restored to 30°C by the temperature regulation module, the opening degree of the heavy phase flow regulating valve 15 is slowly reduced, and the heavy phase solution density begins to gradually increase and then stabilizes at 887 kg / m3 When the opening of the heavy phase flow regulating valve 15 is continuously reduced, the density of the heavy phase solution no longer changes, at this time the phase separation interface of the phase separator 9 has shifted to the heavy phase outlet side of the phase separator 9 (as the system is always in a circulating operation, when the heavy phase solution is taken, the opening of the heavy phase flow regulating valve 15 is reduced, so that the phase separation interface is close to the light phase solution, and the heavy phase solution is taken at the bottom end of the heavy phase solution, to ensure the accuracy of the test results), that is, the heavy phase solution outlet is the heavy phase solution under the conjugate composition at 30°C, after stable operation for 15 min, sampling is performed through the heavy phase sampling pipe, and concentration testing is performed on the sampled solution through gas chromatography, and the mass content of DMF in the heavy phase solution is 87.8%, thereby determining the right side critical solution temperature of the liquid-liquid phase diagram at 30°C T = 30°C, n 2 = 87.8%).

[0071] The heavy phase flow regulating valve 15 is restored to the initial opening, and the opening of the light phase flow regulating valve 12 is slowly reduced, and after the density of the light phase solution starts to gradually decrease and then stabilizes at 634 kg / m 3 When the opening of the light phase flow regulating valve 12 is continuously reduced, the density of the light phase solution no longer changes, at this time the phase separation interface of the phase separator 9 has shifted to the heavy phase outlet side of the phase separator 9, that is, the light phase solution outlet is the light phase solution under the conjugate composition at 30°C, after stable operation for 15 min, sampling is performed through the light phase sampling pipe 16, and concentration testing is performed on the sampled solution through gas chromatography, and the mass content of DMF in the light phase solution is 7.2%, thereby determining the left side critical solution temperature of the liquid-liquid phase diagram at 30°C T = 30°C, n 1 = 7.2%).

[0072] The test solution is subjected to temperature rise and fall at intervals of 5°C, and the concentrations at each temperature are tested according to the above method n 1 , n 2 When the density limit difference between the light phase solution and the heavy phase solution is less than 10 kg / m 3 in the high temperature zone, the increment interval is adjusted to 0.5°C, to search for the highest critical solution temperature of the test, when the test solution is heated to 77.5°C, the density of the light phase solution and the heavy phase solution of the phase separator is consistent, and the density is independent of the flow, the mass content of DMF in the sampled solution is 48.6%, that is, the highest critical solution temperature of n-pentane-DMF T s = 77.5°C, n s = 48.6%) As Figure 1The liquid-liquid phase diagram of n-pentane-DMF can be obtained by connecting the solubility points of each test in sequence.

[0073] The embodiment provides a test method and steps of liquid-liquid phase equilibrium with the highest consolute point. The stability of the solution concentration is determined by the sampling side solution density change trend, and the small flow control of the sampling side is used to ensure the small fluctuation of the sampling solution, so that the influence of the layered interface movement on the test result is effectively avoided. Meanwhile, the embodiment is operated in a closed state, high-pressure test is realized, and the problem that n-pentane cannot be liquefied at high temperature in normal-pressure test, resulting in the difficulty in testing the liquid-liquid phase performance of n-pentane is avoided.

[0074] Embodiment 2 The embodiment takes the test process of the liquid-liquid phase equilibrium of isopropylamine-water as an example, and introduces a liquid-liquid phase equilibrium test system and a test method of a liquid-liquid phase diagram with the lowest consolute point temperature.

[0075] As shown in Figure 2 , the system composition and equipment connection mode of the embodiment are the same as those of embodiment 1, and details are not described herein again. Different from embodiment 1, the phase separator 9 of the embodiment is a cyclone type phase separator, which separates the light phase and heavy phase solutions by centrifugal force difference.

[0076] The test method and specific steps of the embodiment are as follows: The volume of the phase separator 9 is calibrated by using pure water, and then the water is discharged. The vacuum pump 3 is started to vacuumize the light phase solution tank 2, the heavy phase solution tank 1, the phase separation module and the connecting pipeline, and when the absolute pressure is 0.5 kPa, the vacuum pump is closed. Isopropylamine is filled into the light phase solution tank 2, and pure water is filled into the heavy phase solution tank 1.

[0077] The valve of the heavy phase solution tank 1 is opened, the metering pump 4 is started, water is injected into the phase separation module, then the valve at the bottom of the heavy phase solution tank 1 is closed, the valve of the light phase solution tank 2 is opened, isopropylamine is supplemented into the phase separation module through the metering pump 4, and the mass concentration of water in the phase separation module is adjusted n 0 ≈50%.

[0078] The circulating pump 5 is started to make the test solution in the phase separation module circulate, the high-low temperature thermostat 8 and the temperature control pump 7 are started, the inlet solution temperature of the phase separator 9 is set to 40 DEG C, the opening degrees of the light phase flow regulating valve 12 and the heavy phase flow regulating valve 15 are jointly adjusted, the light phase solution flow and the heavy phase solution flow are changed, and it is found that the lower limit value of the light phase solution density is 737 kg / m 3 , the upper limit value of the heavy phase density is 949 kg / m 3 , and the difference between the extreme values of the light phase density and the heavy phase density is 212 kg / m 3; when the test solution is heated to 60℃, the lower limit of the light phase solution density is 678 kg / m 3 , the upper limit of the heavy phase density is 938 kg / m 3 , and the difference between the extreme values of the light and heavy phase densities is 260 kg / m 3 ; that is, as the test solution is heated, the difference between the light and heavy phase densities gradually increases, and it is preliminarily determined that isopropylamine-water is a partially miscible solution with the lowest consolute temperature. When the test solution is cooled to 21.5 ℃, it is found that the light phase solution density at the light phase solution outlet of the phase separator 9 and the heavy phase solution density at the heavy phase solution outlet are consistent, both being 870 kg / m 3 , and the density values are independent of the flow rate, indicating that the solution has entered a completely miscible state, and thus it is determined that isopropylamine-water is a partially miscible solution with the lowest consolute temperature, and the liquid-liquid phase diagram opens upward.

[0079] The solution temperature is increased to 70℃ by the temperature control module, the heavy phase flow regulating valve 15 is slowly reduced, and the heavy phase solution density begins to gradually increase and then stabilizes at 937 kg / m 3 When the opening of the heavy phase flow regulating valve is further reduced, the heavy phase solution density no longer changes, at this time the phase separation interface of the phase separator 9 has shifted to the light phase outlet side of the phase separator 9, that is, the heavy phase solution outlet is the heavy phase solution under the conjugate composition at 70℃, after stable operation for 15 min, sampling is performed through the heavy phase sampling pipe, and concentration testing is performed on the sampled solution by gas chromatography, and the mass content of water in the heavy phase solution is 96.4%, thus it is determined that the right side consolute point of the liquid-liquid phase diagram at 70℃ T = 70℃, n 2 = 96.4%).

[0080] The heavy phase flow regulating valve 15 is restored to the initial opening, and the light phase flow regulating valve 12 is slowly reduced, and the light phase solution density begins to gradually decrease and then stabilizes at 648 kg / m 3 When the opening of the light phase flow regulating valve 12 is further reduced, the light phase solution density no longer changes, at this time the phase separation interface of the phase separator 9 has shifted to the heavy phase outlet side of the phase separator 9, that is, the light phase solution outlet is the light phase solution under the conjugate composition at 70℃, after stable operation for 15 min, sampling is performed through the light phase sampling pipe, and concentration testing is performed on the sampled solution by gas chromatography, and the mass content of water in the light phase solution is 4.1%, thus it is determined that the left side consolute point of the liquid-liquid phase diagram at 70℃ T = 70℃, n 1 = 4.1%).

[0081] The solution is cooled at intervals of 5℃, and the n 1, n 2 Point concentration; when the solution is cooled to 25℃, when the difference between the density limit of the light and heavy phase solution is less than 10 kg / m 3 , the increase interval is adjusted to 0.5℃ to search for the accurate minimum solubility point temperature, when the solution is cooled to 21.5℃, the light phase solution and the heavy phase solution of the phase separator 9 have the same density, and the density is independent of the flow rate, the mass concentration of water in the solution at this temperature is 44.3% according to the sampling test, that is, the minimum solubility point of isopropylamine-water is T s =21.5℃, n s = 44.3%).

[0082] As Figure 3 Figure 4 shown, the liquid-liquid phase diagram of isopropylamine-water can be obtained by connecting the solubility points obtained in each test in sequence.

[0083] Any combination of the technical features of the above examples can be made, in order to make the description simple, all possible combinations of the technical features in the above examples are not described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the description.

[0084] The above examples only express several embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of variations and improvements can be made, which belong to the protection scope of the present application.

Claims

1. A partially miscible liquid-liquid equilibrium test system, characterized in that, The system comprises a solution supply module, a temperature regulation module, a phase separation module and a test sampling module. The solution supply module comprises a heavy phase solution tank, a light phase solution tank and a metering pump, the outlets of the heavy phase solution tank and the light phase solution tank are connected to the inlets of the metering pump respectively. The phase separation module comprises a phase separator and a circulating pump, the outlet of the metering pump is connected to the inlet of the circulating pump. The temperature regulation module is used to regulate the temperature of the solution entering the phase separator, the outlet of the circulating pump is connected to the inlet of the temperature regulation module, and the outlet of the temperature regulation module is connected to the solution inlet of the phase separator. The test sampling module comprises a light phase flow meter, a light phase density meter, a light phase flow regulating valve and a light phase sampling pipe arranged at the light phase solution outlet of the phase separator, and a heavy phase flow meter, a heavy phase density meter, a heavy phase flow regulating valve and a heavy phase sampling pipe arranged at the heavy phase solution outlet of the phase separator, the light phase solution outlet and the heavy phase solution outlet of the phase separator are connected to the inlets of the circulating pump respectively. The heavy phase solution tank and the light phase solution tank are respectively provided with a vacuum port, and the vacuum port is connected to a vacuum pump.

2. The partially miscible liquid phase equilibrium test system of claim 1, wherein, The temperature regulation module comprises a heat exchanger, a temperature control pump and a high-low temperature thermostat unit connected in sequence, the heat exchanger, the temperature control pump and the high-low temperature thermostat unit form a circulation system, the outlet of the circulating pump is connected to the inlet of the heat exchanger, and the outlet of the heat exchanger is connected to the solution inlet of the phase separator.

3. The partially miscible liquid phase equilibrium test system of claim 1, wherein, The heavy phase solution tank is provided with a heavy phase solution reflux port, the light phase solution tank is provided with a light phase solution reflux port, the heavy phase solution outlet of the phase separator is connected to the heavy phase solution reflux port, and a stop valve is arranged on the connecting pipeline, the light phase solution outlet of the phase separator is connected to the light phase solution reflux port, and a stop valve is arranged on the connecting pipeline.

4. The partially miscible liquid phase equilibrium test system of claim 1, wherein, The phase separator is a gravity type phase separator or a cyclone type phase separator, and the heavy phase flow meter and the light phase flow meter are selected from a float type flow meter, an electromagnetic flow meter, a vortex flow meter or an ultrasonic flow meter.

5. The partially miscible liquid phase equilibrium test system of claim 1, wherein, The high-low temperature thermostat unit comprises a plurality of constant temperature water baths connected in sequence, and the temperature control range of the high-low temperature thermostat unit is -80℃-150℃.

6. The partially miscible liquid phase equilibrium test system of claim 1, wherein, A test method for the partial mutual solution liquid phase equilibrium test system according to any one of claims 1-6, comprising the following steps:

7. A test method characterized by, S1, the heavy phase components in the heavy phase solution tank and the light phase components in the light phase solution tank are respectively discharged into the phase separator through the metering pump, and the mass concentration of the heavy phase components in the phase separator is 40%-60%; S2, the circulating pump and the temperature regulation module are started; S3, the test sampling module is used to collect the heavy phase and the light phase in the phase separator, and the collected heavy phase and light phase are respectively placed in a heavy phase sample tank and a light phase sample tank; S3, adjusting the temperature of the test solution in the phase separator by the temperature control module, so that the test solution is in the phase state, gradually reducing the opening of the heavy phase flow regulating valve, observing the heavy phase flow meter reading Q 重 and the heavy phase densimeter reading S4, the heavy phase sample tank and the light phase sample tank are respectively provided with a density meter, and the densities of the heavy phase and the light phase are measured; 重 , when S5, the heavy phase sample tank and the light phase sample tank are respectively provided with a refractive index meter, and the refractive indexes of the heavy phase and the light phase are measured; 重 with Q 重 unchanged, stop the regulating action of the heavy phase flow regulating valve, collect the heavy phase conjugate solution by the heavy phase sampling pipe, test the concentration of the heavy phase component in the heavy phase conjugate solution; restore the heavy phase flow regulating valve to the initial opening, gradually reduce the opening of the light phase flow regulating valve, observe the light phase flow meter reading Q 轻 and the light phase densimeter reading S6, the heavy phase sample tank and the light phase sample tank are respectively provided with a viscosity meter, and the viscosities of the heavy phase and the light phase are measured; 轻 , when S7, the heavy phase sample tank and the light phase sample tank are respectively provided with a flash point tester, and the flash points of the heavy phase and the light phase are measured; 轻 with Q 轻 unchanged, stop the regulating action of the light phase flow regulating valve, collect the light phase conjugate solution by the light phase sampling pipe, test the concentration of the heavy phase component in the light phase conjugate solution; S4, raising or lowering the temperature of the test solution, repeating the step S3, testing the concentration of the heavy phase component in the heavy phase conjugate solution, light phase conjugate solution at different temperatures; when a certain temperature, S8, the heavy phase sample tank and the light phase sample tank are respectively provided with a pour point tester, and the pour points of the heavy phase and the light phase are measured; 重 - S9, the heavy phase sample tank and the light phase sample tank are respectively provided with a freezing point tester, and the freezing points of the heavy phase and the light phase are measured; 轻 ) / S10, the heavy phase sample tank and the light phase sample tank are respectively provided with a boiling point tester, and the boiling points of the heavy phase and the light phase are measured; 重 <0.5% and when S11, the heavy phase sample tank and the light phase sample tank are respectively provided with a gas chromatography tester, and the gas chromatography of the heavy phase and the light phase is tested; 重 with Q 重、 S12, the heavy phase sample tank and the light phase sample tank are respectively provided with a liquid chromatography tester, and the liquid chromatography of the heavy phase and the light phase is tested; 轻 with Q 轻 The concentration of the heavy phase component at the highest or lowest solubility point is obtained when the concentration of the heavy phase component in the heavy phase conjugate solution, light phase conjugate solution at different temperatures; when a certain temperature, 8. The test method of claim 7, wherein, S13, the heavy phase sample tank and the light phase sample tank are respectively provided with a mass spectrometry tester, and the mass spectrometry of the heavy phase and the light phase is tested; 9. The test method of claim 7, wherein, S14, the heavy phase sample tank and the light phase sample tank are respectively provided with a nuclear magnetic resonance tester, and the nuclear magnetic resonance of the heavy phase and the light phase is tested; Solution phase zone determination step: adjust the temperature of the test solution in the phase separator to temperature T, compare the light phase densitometer reading S15, the heavy phase sample tank and the light phase sample tank are respectively provided with a polarimetry tester, and the polarimetry of the heavy phase and the light phase is tested; 轻 to the heavy phase densitometer reading S16, the heavy phase sample tank and the light phase sample tank are respectively provided with a spectrophotometry tester, and the spectrophotometry of the heavy phase and the light phase is tested; 重 , if (light phase densitometer reading S17, the heavy phase sample tank and the light phase sample tank are respectively provided with a titration tester, and the titration of the heavy phase and the light phase is tested; 重 - S18, the heavy phase sample tank and the light phase sample tank are respectively provided with a pH value tester, and the pH values of the heavy phase and the light phase are tested; 轻 ) / (heavy phase densitometer reading S19, the heavy phase sample tank and the light phase sample tank are respectively provided with a conductivity tester, and the conductivities of the heavy phase and the light phase are tested; 重 < 0.5%, then the test solution at temperature T is in a completely miscible state; if (light phase densitometer reading S20, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 重 - S21, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 轻 ) / (heavy phase densitometer reading S22, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 重 ≥ 0.5%, then the test solution at temperature T is in a phase separated state; Liquid-liquid phase diagram form determination step: when the test solution at temperature T is in a completely miscible state, the temperature of the test solution in the phase separator is increased or decreased, the relationship between the difference between S23, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 重 , S24, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 轻 and the temperature change is compared, and if the difference between S25, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 重 , S26, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 轻 becomes larger as the temperature increases or becomes smaller as the temperature decreases, it is determined that the test solution is a partially miscible solution with the lowest consolute point; when the test solution at temperature T is in a phase-separated state, the temperature of the solution in the phase separator is increased or decreased, the relationship between the difference between S27, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 重 , S28, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 轻 and the temperature change is compared, and if the difference between S29, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 重 , S30, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 轻 becomes smaller as the temperature increases or becomes larger as the temperature decreases, and at a certain temperature S31, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 重 = S32, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; 轻 , it is determined that the test solution is a partially miscible solution with the lowest consolute point.

10. The test method of claim 7, wherein, S33, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; S34, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; S35, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; S36, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; S37, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; S38, the heavy phase sample tank and the light phase sample tank are respectively provided with a surface tension tester, and the surface tensions of the heavy phase and the light phase are tested; S39

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