Continuous measurement system and method for the solubility of organic matter in supercritical carbon dioxide

Abstract

This invention provides a continuous measurement system and method for the solubility of organic matter in supercritical carbon dioxide. The system includes a sampling system and an analysis system. The sampling system comprises a high-pressure equilibrium vessel, a sampling bottle, and a first pipeline. The sampling bottle is connected to or disconnected from the high-pressure equilibrium vessel via the first pipeline. The high-pressure equilibrium vessel provides the temperature, pressure, and environment required for the dissolution of organic matter in supercritical carbon dioxide fluid. The supercritical carbon dioxide fluid saturated with dissolved organic matter in the high-pressure equilibrium vessel enters the sampling bottle through the first pipeline at a specified temperature and pressure. A first regulating valve is provided on the first pipeline, which closes and seals the inlet of the sampling bottle after sampling is completed. The analysis system includes the sampling bottle separated from the high-pressure equilibrium vessel after sampling and an absorption bottle. This invention enables continuous measurement of the solubility of organic matter in supercritical carbon dioxide at a specified pressure and temperature, with high measurement efficiency and a short measurement process.

Description

Technical Field

[0001] This invention relates to the field of supercritical fluid extraction technology, specifically to a continuous measurement system and method for the solubility of organic matter in supercritical carbon dioxide. Background Technology

[0002] Supercritical fluids are fluids whose temperature and pressure are both above their critical points. Supercritical fluids exist in a state where there is no clear gas-liquid interface, exhibiting properties of both gases and liquids. Their density is similar to that of liquids, their viscosity is similar to that of gases, and their diffusion coefficient lies between that of liquids and gases. This gives supercritical fluids excellent flow, heat transfer, mass transfer, and dissolution properties.

[0003] Carbon dioxide is widely used in various industries due to its stability, non-toxicity, flame retardancy, low cost, and low critical temperature and pressure, such as carbon dioxide flooding and carbon dioxide extraction. Supercritical carbon dioxide fluid extraction technology is a green, environmentally friendly, efficient, and clean separation technology. Its principle is based on the influence of pressure and temperature on the solubility of fluids. Under supercritical conditions, carbon dioxide selectively dissolves different components. Then, through a series of methods such as depressurization and heating, the supercritical fluid is converted into a common gas, allowing the extracted substances to separate sequentially, thereby achieving the purpose of separation and purification. Therefore, measuring the solubility of substances in supercritical carbon dioxide is of great significance for practical production.

[0004] Existing methods for determining the solubility of supercritical carbon dioxide involve placing a known mass of solute into a high-pressure equilibrium vessel with a transparent viewing window, and then introducing supercritical carbon dioxide fluid to dissolve it. During the measurement, the temperature and pressure within the vessel are varied to induce a cloud point in the system, which corresponds to the solubility at that temperature and pressure. However, this method cannot determine the solubility of organic compounds in supercritical carbon dioxide at specified pressures and temperatures. Furthermore, the dissolution equilibrium time is long, making it difficult to capture the instantaneous cloud point. During air purging, some solute flows out through the vent valve with the airflow, leading to an overestimation of the calculated supercritical carbon dioxide solubility and distorting the measurement results. In existing technologies, sampling typically involves opening the high-pressure equilibrium vessel. Each opening introduces air, requiring subsequent purging of the pipeline to reduce air-induced errors. This reduces measurement efficiency and prolongs the measurement process. Summary of the Invention

[0005] To address the above problems, this invention provides a continuous measurement system for the solubility of organic matter in supercritical carbon dioxide. The system allows for detachable connection between a sampling bottle and a high-pressure equilibrium vessel, enabling sampling at any time without being limited by the temperature and pressure within the vessel. After sampling, the high-pressure equilibrium vessel and sampling bottle are separated, and the separated sampling bottle is connected to an absorption bottle. Based on the mass of carbon dioxide or organic matter sample absorbed by the absorption bottle, the solubility of the organic matter can be conveniently and quickly calculated. This solves the technical problems of existing measurement systems being unable to determine the solubility of organic matter in supercritical carbon dioxide at specified pressures and temperatures, as well as their low measurement efficiency and numerous measurement steps.

[0006] This invention provides a continuous measurement system for the solubility of organic matter in supercritical carbon dioxide, comprising a sampling system and an analysis system. The sampling system includes a high-pressure equilibrium vessel, a sampling bottle, and a first pipeline connecting the outlet of the high-pressure equilibrium vessel and the inlet of the sampling bottle. The sampling bottle is connected to or disconnected from the high-pressure equilibrium vessel via the first pipeline. The high-pressure equilibrium vessel provides the temperature, pressure, and environment required for the dissolution of organic matter in supercritical carbon dioxide fluid. The supercritical carbon dioxide fluid saturated with dissolved organic matter in the high-pressure equilibrium vessel enters the sampling bottle through the first pipeline at a specified temperature and pressure. A first regulating valve is provided on the first pipeline, which closes and seals the inlet of the sampling bottle after sampling is completed. The analysis system includes the sampling bottle, which is separated from the high-pressure equilibrium vessel after sampling, and an absorption bottle connected to the outlet of the sampling bottle. The absorption bottle can be an organic matter absorption bottle or a CO2 absorption bottle.

[0007] According to this technical solution, by adding an excess of organic sample to the high-pressure equilibrium vessel, the organic sample in the supercritical carbon dioxide can be kept in a saturated state, avoiding errors caused by the instantaneous capture of the turbidity point. Since the organic sample in the high-pressure equilibrium vessel is in an excess state, sampling at another specified pressure and temperature can be achieved simply by adjusting the pressure and temperature in the high-pressure equilibrium vessel, avoiding the problem of impurity gas in the system pipeline caused by repeated injection of organic matter.

[0008] The sampling bottle can be detachably connected to the high-pressure equilibrium vessel, enabling continuous sampling and measurement at any time. During sampling, the high-pressure equilibrium vessel does not need to be opened, preventing air from entering, reducing pipeline purging, shortening the sampling process, and improving sampling efficiency. Furthermore, it avoids the leakage of some solute with the gas flow during pipeline purging, improving the accuracy of solubility calculations. After sampling, the high-pressure equilibrium vessel and sampling bottle are separated, and the separated sampling bottle is connected to the absorption bottle. Based on the mass of carbon dioxide or organic sample absorbed by the absorption bottle, the solubility of the organic matter can be conveniently and quickly calculated.

[0009] The first regulating valve of this invention can control the flow rate of supercritical carbon dioxide fluid containing dissolved saturated organic matter into the sampling bottle, and after sampling is completed, it can seal the inlet end of the sampling bottle to prevent impurities from entering the sampling bottle and causing measurement errors, thereby further improving the accuracy of the measurement results.

[0010] In an optional technical solution of the present invention, the first pipeline includes a first pipe section and a second pipe section. The inlet of the first pipe section is connected to the outlet of the high-pressure balance vessel. The outlet of the first pipe section is detachably connected to the inlet of the second pipe section. The outlet of the second pipe section is connected to a sampling bottle. After the sampling bottle is used for sampling, the second pipe section is disconnected from the first pipe section, and the outlet of the first pipe section is connected to another sampling bottle.

[0011] According to this technical solution, the high-pressure equilibrium vessel and the sampling bottle can be detachably connected via a first and second pipe section. The structure is simple, easy to manufacture, and inexpensive. It also allows for convenient and flexible connection and separation of the high-pressure equilibrium vessel and the sampling bottle. After one sampling is completed, another sampling bottle can be directly connected to the outlet of the first pipe section, and the temperature and pressure inside the high-pressure equilibrium vessel can be adjusted to achieve sampling at another temperature and pressure parameter. This facilitates and quickly enables continuous measurement of the solubility of organic matter in supercritical carbon dioxide, and prevents impurities from entering the sampling bottle through the first pipe section, thus improving the accuracy of the measurement results.

[0012] In an optional technical solution of the present invention, a second pipeline is provided between the outlet of the sampling bottle and the inlet of the absorption bottle, and a second regulating valve for adjusting the outlet flow of the sampling bottle and a pressure reducing valve for reducing the inlet pressure of the absorption bottle are sequentially provided on the second pipeline.

[0013] According to this technical solution, by adjusting the outlet flow rate of the sampling bottle through the fifth regulating valve and reducing the inlet pressure through the pressure reducing valve, it is possible to avoid incomplete absorption caused by the rapid passage of supercritical carbon dioxide fluid containing dissolved organic matter through the absorption bottle, which would affect the accuracy of the solubility calculation results.

[0014] In an optional technical solution of the present invention, in the analysis system, the inlet of the second pipe section is connected to a protective gas supply device, and the first regulating valve is opened when the protective gas supply device supplies protective gas.

[0015] According to the technical solution, the protective gas supply device is used to provide a gas source to the analysis system, ensuring that the organic sample or carbon dioxide in the sampling bottle completely enters the absorption bottle.

[0016] In an optional technical solution of the present invention, the sampling system further includes a carbon dioxide supply device, a third regulating valve, a cooling device, a high-pressure pump, a preheating device, and a fourth regulating valve connected sequentially via a third pipeline. The carbon dioxide supply device provides the carbon dioxide gas required for measurement, the cooling device is used to cool the carbon dioxide gas at the outlet of the carbon dioxide supply device into liquid carbon dioxide, the high-pressure pump is used to transport the liquid carbon dioxide to the preheating device, the preheating device heats the liquid carbon dioxide to a specified temperature, the third regulating valve is used to control the outlet flow rate of the carbon dioxide gas, and the fourth regulating valve is used to control the outlet flow rate of the carbon dioxide preheated to the specified temperature.

[0017] According to this technical solution, the carbon dioxide gas supplied by the carbon dioxide supply device is cooled to below the saturation temperature by a cooling device to form liquid carbon dioxide. After being transported by a high-pressure pump and preheated by a preheating device, the pressure and temperature of the liquid carbon dioxide rise above the critical pressure and critical temperature, reaching a supercritical state. By pretreating the gaseous carbon dioxide to a supercritical state before entering the high-pressure balance vessel, the handling of carbon dioxide in the high-pressure balance vessel is simplified, which is beneficial to improving measurement efficiency and enhancing the flexibility of the system.

[0018] In an optional technical solution of the present invention, a first pressure sensor and a first temperature sensor are installed on the high-pressure balance vessel, and a second pressure sensor and a second temperature sensor are installed on the sampling bottle. During the sampling process, the readings of the first pressure sensor and the second pressure sensor are the same and are at the experimentally specified pressure, and the readings of the first temperature sensor and the second temperature sensor are the same and are at the experimentally specified temperature.

[0019] According to this technical solution, the temperature and pressure of the equilibrium vessel and the sampling bottle can be easily obtained. During sampling, the temperature and pressure inside the equilibrium vessel and the sampling bottle are kept the same, which helps to reduce experimental errors and improve the accuracy of measurement.

[0020] In an optional technical solution of the present invention, the sampling system further includes a vacuum pump, the outlet of which is connected to a third pipeline and located between the high-pressure pump and the preheating device, and the outlet of the vacuum pump is provided with a fifth regulating valve.

[0021] The vacuum pump in this technical solution can remove impurities from the system pipeline, thereby improving the accuracy of measurements.

[0022] The present invention further provides a method for continuous measurement of the solubility of organic matter in supercritical carbon dioxide, comprising the following steps:

[0023] Supercritical carbon dioxide fluid and an excess of organic sample are injected into a high-pressure equilibrium vessel, wherein the organic sample is at least partially dissolved in the supercritical carbon dioxide fluid;

[0024] Adjust the temperature and pressure inside the high-pressure balance vessel to the specified temperature and pressure respectively. After the organic sample has dissolved for the specified time, open the first regulating valve to allow the supercritical carbon dioxide fluid containing saturated organic matter dissolved in the high-pressure balance vessel to enter the sampling bottle. The temperature and pressure inside the sampling bottle are the same as those inside the high-pressure balance vessel. Complete the sampling and close the first regulating valve.

[0025] Separate the sampling bottle from the high-pressure equilibrium vessel, and connect the outlet of the separated sampling bottle to the inlet of the absorption bottle, so that the organic sample and CO2 in the sampling bottle enter the absorption bottle.

[0026] When the absorption bottle is a carbon dioxide absorption bottle, it absorbs carbon dioxide from the sampling bottle. The total mass m of carbon dioxide and organic sample is obtained by weighing the sampling bottle before and after sampling. Combined with the measurement of the pH value change of the absorption bottle before and after absorbing carbon dioxide gas, the mass m′ of carbon dioxide is calculated according to formula (4). And the solubility S of organic sample at specified temperature and specified pressure is calculated according to formula (1) and formula (2).

[0027] When the absorption bottle is an organic absorption bottle, weigh the sampling bottle before and after sampling to obtain the total mass m of carbon dioxide and organic sample, and weigh the absorption bottle before and after absorbing organic sample to obtain the mass m″ of organic matter. Calculate the solubility S of organic sample at specified temperature and specified pressure according to formula (1) and formula (3).

[0028] m = m0 - m1 (1)

[0029]

[0030]

[0031]

[0032] In the formula, m0 is the mass of the sampling bottle after sampling, and m1 is the mass of the sampling bottle before sampling; C0 is the mass of OH in the absorption bottle before absorbing carbon dioxide. - The concentration of ions, C1 being the concentration of OH- ions in the absorption bottle before and after carbon dioxide absorption. - The concentration of ions, where V is the volume of the solution in the absorption bottle.

[0033] According to this technical solution, the sampling bottle and the high-pressure balance vessel can be detachably connected, enabling sampling at any time, achieving continuous sampling and measurement. The high-pressure balance vessel does not need to be opened during sampling, preventing air from entering, reducing pipeline purging, shortening the sampling process, and improving sampling efficiency. The absorption method is used to calculate the mass of carbon dioxide or organic matter samples, and the solubility of organic matter is calculated by combining the mixed mass before and after sampling. This avoids problems such as measurement errors of flow meters at low flow rates, thus achieving rapid, continuous, and reliable measurement of the solubility of organic matter in supercritical carbon dioxide.

[0034] In the optional technical solution of the present invention, the carbon dioxide absorption bottle contains an alkaline solution, and the cations of the alkaline solution react with carbon dioxide to form a carbonate precipitate. The mass of the carbon dioxide in the sampling bottle is calculated by weighing the mass of the precipitate generated in the absorption bottle according to formula (5).

[0035]

[0036] In equation (5), m″′ is the mass of the precipitate generated in the absorption bottle, M is the molar molecular mass of the precipitate, and X is the mass of the precipitate molecule. The quantity.

[0037] According to this technical solution, the solubility of organic matter is calculated by weighing and measuring pH, which avoids problems such as measurement error of gas flow rate when the flow meter is measuring at low flow rates, thereby realizing rapid, continuous and reliable measurement of the solubility of organic matter in supercritical carbon dioxide.

[0038] In an optional technical solution of the present invention, after the sampling bottle is separated from the high-pressure balance vessel, another sampling bottle is connected to the outlet of the high-pressure balance vessel, and the temperature and pressure inside the high-pressure balance vessel are adjusted to achieve sampling under another temperature and pressure parameter. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the sampling system in the continuous measurement system for the solubility of organic matter in supercritical carbon dioxide according to the first embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the analytical system in the continuous measurement system for the solubility of organic matter in supercritical carbon dioxide according to the first embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the sampling system in the continuous measurement system for the solubility of organic matter in supercritical carbon dioxide according to the second embodiment of the present invention.

[0042] Figure 4This is a schematic diagram of the sampling system in the continuous measurement system for the solubility of organic matter in supercritical carbon dioxide according to the third embodiment of the present invention.

[0043] Figure 5 This is a schematic diagram of the analytical system in the continuous measurement system for the solubility of organic matter in supercritical carbon dioxide according to the fourth embodiment of the present invention.

[0044] Figure label:

[0045] Sampling system 1; constant temperature container 10; high pressure balance vessel 11; first pressure sensor 111; first temperature sensor 112; piston 113; sampling bottle 12; second pressure sensor 121; second temperature sensor 122; carbon dioxide supply device 13; cooling device 14; high pressure pump 15; preheating device 16; buffer device 17; syringe 18; vacuum pump 19; analysis system 2; absorption bottle 21; protective gas supply device 22; first pipeline 31; first pipeline section 311; second pipeline section 312; compression fitting 313; second pipeline 32; third pipeline 33; branch pipe 331; safety valve 332; first regulating valve 41; second regulating valve 42; third regulating valve 42; fourth regulating valve 44; fifth regulating valve 45; pressure reducing valve 5; exhaust valve 51; third pressure sensor 131; third temperature sensor 132; pressure resistant bottle 23. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] [First Implementation Method]

[0048] Please see Figure 1 , Figure 2As shown, the present invention provides a continuous measurement system for the solubility of organic matter in supercritical carbon dioxide, including a sampling system 1 and an analysis system 2. The sampling system 1 includes a high-pressure equilibrium vessel 11, a sampling bottle 12, and a first pipeline 31 connecting the outlet of the high-pressure equilibrium vessel 11 and the inlet of the sampling bottle 12. The sampling bottle 12 is connected to or separated from the high-pressure equilibrium vessel 11 through the first pipeline 31. The high-pressure equilibrium vessel 11 provides the temperature, pressure, and environment required for the dissolution of organic matter in supercritical carbon dioxide fluid. The supercritical carbon dioxide fluid saturated with dissolved organic matter in the high-pressure equilibrium vessel 11 enters the sampling bottle 12 through the first pipeline 31 at a specified temperature and pressure. A first regulating valve 41 is provided on the first pipeline 31, which closes and seals the inlet end of the sampling bottle 12 after sampling is completed. The analysis system 2 includes the sampling bottle 12 separated from the high-pressure equilibrium vessel 11 after sampling and an absorption bottle 21 connected to the outlet of the sampling bottle 12. The absorption bottle 21 is an organic matter absorption bottle or a CO2 absorption bottle.

[0049] In this embodiment of the invention, by adding an excess of organic sample to the high-pressure balancing vessel 11, the organic sample in the supercritical carbon dioxide can be kept in a saturated state, avoiding errors caused by the instantaneous capture of the turbidity point. Since the organic sample in the high-pressure balancing vessel 11 is in an excess state, sampling at another specified pressure and temperature can be achieved simply by adjusting the pressure and temperature in the high-pressure balancing vessel 11, avoiding the problem of impurity gas in the system pipeline caused by repeated injection of organic matter.

[0050] The sampling bottle 12 can be detachably connected to the high-pressure equilibrium vessel 11, enabling continuous sampling and measurement at any time. During sampling, the high-pressure equilibrium vessel 11 does not need to be opened, preventing air from entering and reducing pipeline purging, thus shortening the sampling process and improving efficiency. Furthermore, it avoids the leakage of some solute with the airflow during pipeline purging, improving the accuracy of organic sample solubility calculations. After sampling, the high-pressure equilibrium vessel 11 and sampling bottle 12 are separated, and the separated sampling bottle 12 is connected to the absorption bottle 21. Based on the mass of carbon dioxide or organic sample absorbed by the absorption bottle 21, the solubility of the organic matter can be conveniently and quickly calculated.

[0051] The first regulating valve 41 of the present invention can control the flow rate of supercritical carbon dioxide fluid containing dissolved saturated organic matter into the sampling bottle 12, and after sampling is completed, it can seal the inlet end of the sampling bottle 12 to prevent impurities from entering the sampling bottle 12 and causing measurement errors, thereby further improving the accuracy of the measurement results.

[0052] In a preferred embodiment of the present invention, the first pipeline 31 includes a first pipe section 311 and a second pipe section 312. The inlet of the first pipe section 311 is connected to the outlet of the high-pressure balance vessel 11. The outlet of the first pipe section 311 is detachably connected to the inlet of the second pipe section 312. The outlet of the second pipe section 312 is connected to the sampling bottle 12. After sampling is completed in the sampling bottle 12, the second pipe section 312 is disconnected from the first pipe section 311, and the outlet of the first pipe section 311 is connected to another sampling bottle 12.

[0053] Through the above method, the high-pressure equilibrium vessel 11 and the sampling bottle 12 can be detachably connected via a first pipe section 311 and a second pipe section 312. This design is simple, easy to manufacture, and inexpensive. It allows for convenient and flexible connection and separation of the high-pressure equilibrium vessel 11 and the sampling bottle 12. After one sampling is completed, another sampling bottle 12 can be directly connected to the outlet of the first pipe section 311, and sampling at a different temperature and pressure parameter can be achieved by adjusting the temperature and pressure inside the high-pressure equilibrium vessel 11. This facilitates and quickly enables continuous measurement of the solubility of organic matter in supercritical carbon dioxide, and prevents impurities from entering the sampling bottle 12 through the first pipe section 311, thus improving the accuracy of the measurement results. In a specific embodiment of the invention, the first pipe section 311 and the second pipe section 312 are detachably connected via a compression fitting 313. This not only facilitates the connection and separation of the first pipe section 311 and the second pipe section 312 but also ensures the sealing of the connection node, preventing impurities from entering the pipeline.

[0054] In a preferred embodiment of the present invention, a first pressure sensor 111 and a first temperature sensor 112 are installed on the high-pressure balance vessel 11, and a second pressure sensor 121 and a second temperature sensor 122 are installed on the sampling bottle 12. The first pressure sensor 111 and the first temperature sensor 112 are used to measure the pressure and temperature inside the high-pressure balance vessel 11, respectively, and the second pressure sensor 121 and the second temperature sensor 122 are used to measure the pressure and temperature inside the sampling bottle 12, respectively. During continuous measurement, the readings of the first pressure sensor 111 and the second pressure sensor 121 are kept to be the same and at the experimentally specified pressure, and the readings of the first temperature sensor 112 and the second temperature sensor 122 are kept to be the same and at the experimentally specified temperature.

[0055] In a preferred embodiment of the present invention, a second pipeline 32 is provided between the outlet of the sampling bottle 12 and the inlet of the absorption bottle 21. The second pipeline 32 is sequentially provided with a second regulating valve 42 for adjusting the outlet flow of the sampling bottle 12 and a pressure reducing valve 5 for reducing the inlet pressure of the absorption bottle 21.

[0056] In this embodiment of the invention, the outlet flow rate of the sampling bottle 12 is adjusted by the second regulating valve 42, and the inlet pressure is reduced by the pressure reducing valve 5. The high-pressure carbon dioxide and organic sample in the sampling bottle 12 slowly enter the absorption bottle 21 and are absorbed. This can avoid the rapid passage of supercritical carbon dioxide fluid containing dissolved organic matter through the absorption bottle 21, which would lead to incomplete absorption of organic matter or carbon dioxide by the absorption bottle 21 and affect the accuracy of the solubility calculation results.

[0057] In a preferred embodiment of the present invention, in the analysis system 2, the inlet of the second pipe section 312 is connected to a protective gas supply device 22, and the first regulating valve 31 is opened when the protective gas supply device 22 supplies protective gas. The protective gas supply device 22 is used to provide a gas source to the analysis system 2, ensuring that the organic sample or carbon dioxide in the sampling bottle 12 completely enters the absorption bottle 21. The first regulating valve 41 is also used to regulate the flow rate of the protective gas entering the analysis system 2. The protective gas supply device 22 is preferably a protective gas storage tank, and the protective gas is usually an inert gas that will not react with carbon dioxide or organic samples and will not affect the measurement results.

[0058] In a preferred embodiment of the present invention, the sampling system 1 further includes a carbon dioxide supply device 13, a third regulating valve 43, a cooling device 14, a high-pressure pump 15, a preheating device 16, and a fourth regulating valve 44, which are sequentially connected via a third pipeline 33. The carbon dioxide supply device 14 provides the carbon dioxide gas required for measurement. The cooling device 14 is used to cool the carbon dioxide gas into liquid carbon dioxide. The high-pressure pump 15 is used to transport the liquid carbon dioxide to the preheating device 16. The preheating device 16 preheats the received liquid carbon dioxide to a specified temperature. The third regulating valve 43 is used to control the outlet flow rate of the carbon dioxide gas, and the fourth regulating valve 44 controls the outlet flow rate of the carbon dioxide preheated to the specified temperature. In a specific embodiment of the present invention, the carbon dioxide supply device 13 is a carbon dioxide storage tank. The carbon dioxide gas provided by the carbon dioxide supply device 13 is cooled below the saturation temperature by the cooling device 14 to form liquid carbon dioxide. After being transported by the high-pressure pump 15 and preheated by the preheating device 16, the pressure and temperature of the liquid carbon dioxide rise above the critical pressure and critical temperature, reaching a supercritical state. By pretreating the carbon dioxide gas before it enters the high-pressure balance vessel 11 to achieve a supercritical state, the handling of carbon dioxide in the high-pressure balance vessel 11 is simplified, which is beneficial to improving measurement efficiency and increasing the flexibility of the system.

[0059] In a preferred embodiment of the present invention, in order to reduce the heat dissipation of carbon dioxide in the pipeline from the external environment and to ensure that the temperature of carbon dioxide entering the high-pressure balance vessel 11 is the same as the temperature of carbon dioxide at the outlet of the preheating device 16, the third pipeline 33 between the preheating device 16 and the high-pressure balance vessel 11 is covered with heat-insulating cotton (not shown in the figure).

[0060] In a preferred embodiment of the present invention, in order to alleviate the fluctuations in pressure and flow in the pipeline caused by the reciprocating motion of the high-pressure pump 15 and to make the data acquisition during system operation more stable, a buffer device 17 is provided on the third pipeline 33 between the high-pressure pump 15 and the preheating device 16. Specifically, the buffer device 17 is a pulsation damper.

[0061] In a preferred embodiment of the present invention, a syringe 18 is also included, through which the organic sample is injected into the high-pressure equilibrium vessel 11.

[0062] In a preferred embodiment of the present invention, the sampling system further includes a vacuum pump 19, which is disposed on the third pipeline 33 and located between the pulsation damper and the preheating device 16. The outlet of the vacuum pump 19 is provided with a fifth regulating valve 45. The vacuum pump 19 is used to remove air introduced into the system pipeline and reduce measurement errors.

[0063] Furthermore, the third pipeline 33 is also equipped with a branch pipe 331 and a safety valve 332 installed on the branch pipe 331. The safety valve 332 plays a safety protection role in the system. When the system pressure exceeds the specified value, the safety valve 332 opens to discharge a part of the fluid in the system into the atmosphere, so that the system pressure does not exceed the allowable value.

[0064] In a preferred embodiment of the present invention, the sampling system 1 further includes a constant temperature container 10, a high pressure balancing vessel 11, and a sampling bottle 12 placed inside the constant temperature container 10.

[0065] The above describes in detail the continuous measurement system for the solubility of organic matter in supercritical carbon dioxide according to the first embodiment of the present invention. The following describes its measurement method, including the following steps:

[0066] S1: Inject supercritical carbon dioxide fluid and excess organic sample into the high-pressure balance vessel 11, wherein the organic sample is at least partially dissolved in the supercritical carbon dioxide fluid;

[0067] S2: Adjust the temperature and pressure inside the high-pressure balance vessel 11 to reach the specified temperature and pressure respectively. After the organic sample has dissolved for the specified time, open the first regulating valve 41 to allow the supercritical carbon dioxide fluid containing saturated organic matter dissolved in the high-pressure balance vessel 11 to enter the sampling bottle 12. The temperature and pressure inside the sampling bottle 12 are the same as those inside the high-pressure balance vessel 11. Complete the sampling and close the first regulating valve 41.

[0068] S3: Separate the sampling bottle 12 from the high-pressure equilibrium vessel 11, and connect the outlet of the separated sampling bottle 12 to the inlet of the absorption bottle 21, so that the organic sample and CO2 in the sampling bottle 12 enter the absorption bottle 21; specifically, the separated sampling bottle 12, together with the second pipe section 312 and the first regulating valve 41, is connected to the analysis system 2.

[0069] S4: When the absorption bottle is a carbon dioxide absorption bottle, it absorbs carbon dioxide from the sampling bottle. The total mass m of carbon dioxide and organic sample is obtained by weighing the sampling bottle before and after sampling. Combined with the measurement of the pH value change of the absorption bottle before and after absorbing carbon dioxide gas, the mass m′ of carbon dioxide is calculated according to formula (4); and the solubility S of organic sample at specified temperature and specified pressure is calculated according to formula (1) and formula (2).

[0070] When the absorption bottle is an organic absorption bottle, weigh the sampling bottle before and after sampling to obtain the total mass m of carbon dioxide and organic sample, and weigh the absorption bottle before and after absorbing organic sample to obtain the mass m″ of organic matter. Calculate the solubility S of organic sample at specified temperature and specified pressure according to formula (1) and formula (3).

[0071] m = m0 - m1 (1)

[0072]

[0073]

[0074]

[0075] In the formula, m0 is the mass of the sampling bottle after sampling, and m1 is the mass of the sampling bottle before sampling; C0 is the mass of OH in the absorption bottle before absorbing carbon dioxide. - The concentration of ions, C1 being the concentration of OH- ions in the absorption bottle before and after carbon dioxide absorption. - The concentration of ions is given by V, where V is the volume of the solution in the absorption bottle. The carbon dioxide absorption bottle contains an alkaline solution.

[0076] Through the above method, the sampling bottle 12 and the high-pressure balance vessel 11 can be detachably connected, enabling sampling at any time, achieving continuous sampling and continuous measurement. During the sampling process, there is no need to open the high-pressure balance vessel 11, avoiding air entering the high-pressure balance vessel 11, reducing pipeline purging, shortening the sampling process, and improving sampling efficiency. The mass of carbon dioxide or organic matter samples is calculated using the absorption method, and the solubility of organic matter is calculated by combining the mixed mass before and after sampling. This avoids problems such as measurement errors of flow meters at low flow rates, thereby achieving rapid, continuous, and reliable measurement of the solubility of organic matter in supercritical carbon dioxide.

[0077] Specifically, before step S1, there is also a step S0 to purge the system piping;

[0078] S01: Adjust the fourth regulating valve 44, the first regulating valve 41, and the second regulating valve 42 to the open state, open the third regulating valve 43 and start the high-pressure pump 15 to purge the carbon dioxide system pipeline;

[0079] S02: Close the above regulating valves (41, 42, 43, 44) and open the fifth regulating valve 45, start the vacuum pump 19 to discharge the gas in the system pipeline and evacuate the system.

[0080] S03: Close the fifth regulating valve 45 and vacuum pump 19; repeat steps S01 and S02 two to three times to ensure that the system pipeline does not contain air or other impurities.

[0081] In step S1, the step of injecting excess organic sample into the high-pressure equilibrium vessel 11 includes: after purging the system pipeline, injecting excess organic sample into the high-pressure equilibrium vessel 11 through a syringe 18. Preferably, a magnetic stirrer (not shown in the figure) is provided inside the high-pressure equilibrium vessel 11 to accelerate the dissolution process of the organic matter.

[0082] The steps for injecting carbon dioxide into the high-pressure balance vessel 11 include:

[0083] Adjust the fourth regulating valve 44 to the open state, and the cooling device 14 and the preheating device 16 to the working state. The preheating device 16 heats the carbon dioxide to the experimental set temperature; open the third regulating valve 43 and start the high pressure pump 15 to inject carbon dioxide into the high pressure balance vessel 11.

[0084] In step S2, after the readings of the first pressure sensor 11 and the first temperature sensor 12 stabilize and reach the experimental set pressure value, the third regulating valve 43 and the fourth regulating valve 44 are closed. After the dissolution time reaches the experimental set time, the first regulating valve 41 is opened to allow the supercritical carbon dioxide containing saturated organic matter dissolved in the high-pressure equilibrium vessel 7 to flow into the sampling bottle 12. After the readings of the second pressure sensor 13 and the first pressure sensor 11 are the same, and the readings of the second temperature sensor 14 and the first temperature sensor 12 are the same, the first regulating valve 41 is closed to complete the sampling.

[0085] In a preferred embodiment of the present invention, the volume of the sampling bottle 12 should be much smaller than the volume of the high-pressure balance vessel 11, so that when the first regulating valve 41 is opened for sampling, the readings of the first pressure sensor 11 and the first temperature sensor 12 do not change. Furthermore, to prevent a sharp drop in fluid temperature due to adiabatic expansion at the moment the first regulating valve 41 is opened, which could cause some organic matter or carbon dioxide to condense at the outlet of the first regulating valve 41, the outside of the first pipeline 31 is covered with a constant-temperature electric heating belt.

[0086] In a preferred embodiment of the present invention, the absorption bottle 21 is a carbon dioxide absorption bottle, and the contents of the absorption bottle 21 contain an alkaline solution. The contents of the carbon dioxide absorption bottle contain an alkaline solution, and the cations of the alkaline solution react with carbon dioxide to form a carbonate precipitate. The mass of the carbon dioxide in the sampling bottle is calculated by weighing the mass of the precipitate generated in the absorption bottle according to formula (5).

[0087]

[0088] In equation (5), m″′ is the mass of the precipitate generated in the absorption bottle, M is the molar molecular mass of the precipitate, and X is the mass of the precipitate molecule. The quantity.

[0089] By employing weighing and pH measurement to calculate the solubility of organic compounds, problems such as measurement errors in gas flow rate measurements at low flow rates are avoided, thus enabling rapid, continuous, and reliable measurement of the solubility of organic compounds in supercritical carbon dioxide. In some embodiments, the absorption bottle 21 can also be an organic absorption bottle, containing organic matter to absorb the organic sample. Utilizing the principle that the organic absorption bottle only absorbs the organic sample and not carbon dioxide, the weight of the organic sample can be obtained by measuring the change in weight of the absorption bottle 21 before and after absorption. Combining this with the total mass of carbon dioxide and the organic sample obtained before and after sampling, the solubility of the organic compound in supercritical carbon dioxide fluid can be calculated.

[0090] In a preferred embodiment of the present invention, after the sampling bottle 12 is separated from the high-pressure balance vessel 11, another sampling bottle 12 (including a new second pipe section 312 and a first regulating valve 41) is connected to the outlet of the high-pressure balance vessel 11, and sampling at a different temperature and pressure parameter is achieved by adjusting the temperature and pressure inside the high-pressure balance vessel 11. Specifically, the connection between the high-pressure balance vessel 11 and the sampling bottle 12 is disconnected by a compression fitting 313, and the sampling bottle 12 can be connected to the analysis system 2. The new sampling bottle 12 (including a new second pipe section 312 and a first regulating valve 41) can be resealed to the high-pressure balance vessel 11 by the compression fitting 313. Repeating the above step S2 can complete sampling at a specified pressure and temperature.

[0091] [Second Implementation Method]

[0092] Please see Figure 3 As shown, the second embodiment of the present invention provides a continuous measurement system for the solubility of organic matter in supercritical carbon dioxide. Its structure is basically the same as the continuous measurement system in the first embodiment, except that a piston 113 is installed above the high-pressure balance vessel 11. The piston 113 can move up and down inside the high-pressure balance vessel 11, increasing or decreasing the pressure inside the high-pressure balance vessel 11 by moving the piston 113. By flexibly controlling the pressure inside the high-pressure balance vessel 11 by moving the piston 113, the start and stop of the high-pressure pump 15 can be reduced. When the experimental set pressure is high, the high-pressure balance vessel 11 can reach a higher pressure by moving the piston 113.

[0093] [Third Implementation Method]

[0094] Please see Figure 4 As shown, the third embodiment of the present invention provides a continuous measurement system for the solubility of organic matter in supercritical carbon dioxide. Its structure is basically the same as that of the continuous measurement system in the first embodiment. The difference is that the carbon dioxide storage tank supplies liquid carbon dioxide. The carbon dioxide storage tank is placed at an angle so that the liquid carbon dioxide in the carbon dioxide storage tank can flow out through the bottle mouth and be transported to the preheating device 16 by the high-pressure pump 15. This eliminates the need for the cooling device 14, simplifies the system structure, reduces system energy consumption, shortens the measurement time, and improves measurement efficiency.

[0095] [Fourth Implementation Method]

[0096] Please see Figure 5 As shown, the fourth embodiment of the present invention provides a continuous measurement system for the solubility of organic matter in supercritical carbon dioxide. Its structure is basically the same as the continuous measurement system in the first embodiment, except that in this system, carbon dioxide and organic matter samples from sampling bottle 12 are introduced into a pressure-resistant bottle 23 of known volume. The carbon dioxide and organic matter samples from sampling bottle 12 enter the pressure-resistant bottle 23 through a second regulating valve 42. Carbon dioxide exists in the pressure-resistant bottle 23 in gaseous form, while the organic matter sample is in liquid form, and its volume is negligible. A pressure sensor 131 and a temperature sensor 132 are installed on the pressure-resistant bottle 23. By querying the density of carbon dioxide at the corresponding pressure and temperature, and combining this with the volume of the pressure-resistant bottle 23, the mass m′ of carbon dioxide can be obtained.

[0097] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A continuous measurement system for the solubility of organic matter in supercritical carbon dioxide, characterized in that, The sampling system and the analysis system, wherein, the sampling system comprises a high-pressure balance tank, a sampling bottle and a first pipeline connecting the outlet of the high-pressure balance tank and the inlet of the sampling bottle, the sampling bottle is connected to or separated from the high-pressure balance tank through the first pipeline, the high-pressure balance tank provides the temperature, pressure and place required for the dissolution of organic matter in supercritical carbon dioxide fluid, the supercritical carbon dioxide fluid dissolved with saturated organic matter in the high-pressure balance tank enters the sampling bottle through the first pipeline at a specified temperature and pressure; a first regulating valve is arranged on the first pipeline, and the first regulating valve is closed to seal the inlet end of the sampling bottle after sampling of the sampling bottle is completed; the analysis system comprises the sampling bottle separated from the high-pressure balance tank after sampling and an absorption bottle connected to the outlet of the sampling bottle, the absorption bottle is an organic matter absorption bottle or a CO2 absorption bottle; the first pipeline comprises a first pipe section and a second pipe section, the inlet of the first pipe section is connected to the outlet of the high-pressure balance tank, the outlet of the first pipe section is detachably connected to the inlet of the second pipe section, the outlet of the second pipe section is connected to the sampling bottle, the second pipe section is disconnected from the first pipe section after sampling of the sampling bottle is completed, the outlet of the first pipe section is connected to another sampling bottle, and the temperature and pressure in the high-pressure balance tank are adjusted to realize sampling under another temperature and pressure parameter; a second pipeline is arranged between the outlet of the sampling bottle and the inlet of the absorption bottle, and a second regulating valve for regulating the outlet flow of the sampling bottle and a pressure reducing valve for reducing the inlet pressure of the absorption bottle are arranged on the second pipeline in sequence; a first pressure sensor and a first temperature sensor are arranged on the high-pressure balance tank, and a second pressure sensor and a second temperature sensor are arranged on the sampling bottle; during sampling, the readings of the first pressure sensor and the second pressure sensor are the same and are a specified pressure, and the readings of the first temperature sensor and the second temperature sensor are the same and are a specified temperature; When the absorption bottle is a carbon dioxide absorption bottle, carbon dioxide from the sampling bottle is absorbed, and the total mass of the carbon dioxide and the organic sample is obtained by weighing the sampling bottle before and after sampling m , in combination with measuring the change in pH value of the absorption bottle before and after absorbing carbon dioxide gas, the mass of carbon dioxide is calculated according to formula (4) ; and the solubility of the organic sample at a specified temperature and a specified pressure is calculated according to formula (1) and formula (2) S ; or the absorption bottle is an organic matter absorption bottle, the total mass of the carbon dioxide and the organic matter sample is obtained by weighing the mass of the sampling bottle before and after sampling m , and the mass of the organic matter is obtained by weighing the mass of the absorption bottle before and after absorbing the organic matter sample , and the solubility of the organic matter sample at a specified temperature and a specified pressure is calculated according to formula (1) and formula (3) S ; （1） （2） （3） （4） wherein m 0 is the mass of the sampling bottle after sampling, m 1 is the mass of the sampling bottle before sampling; C 0 is the concentration of OH ions in the absorption bottle before absorption of carbon dioxide, - C 1 is the concentration of OH ions in the absorption bottle after absorption of carbon dioxide, - V V is the volume of the solution in the absorption bottle.​​ 2. The system for continuous measurement of organic solubility in supercritical carbon dioxide according to claim 1, wherein, in the analysis system, the inlet of the second pipe section is connected to a protective gas supply device, and the first regulating valve is opened when the protective gas supply device supplies protective gas.

3. The system for continuous measurement of organic solubility in supercritical carbon dioxide of any one of claims 1 to 2, wherein, the sampling system further comprises a carbon dioxide supply device, a third regulating valve, a cooling device, a high-pressure pump, a preheating device and a fourth regulating valve connected in sequence through a third pipeline, the carbon dioxide supply device provides carbon dioxide gas required for measurement, the cooling device is used for cooling the carbon dioxide gas at the outlet of the carbon dioxide supply device into liquid carbon dioxide, the high-pressure pump is used for delivering the liquid carbon dioxide to the preheating device, the preheating device heats the liquid carbon dioxide to a specified temperature, the third regulating valve is used for controlling the outlet flow of the carbon dioxide gas, and the fourth regulating valve is used for controlling the outlet flow of the carbon dioxide preheated to the specified temperature.

4. The system for continuous measurement of organic solubility in supercritical carbon dioxide according to claim 3, wherein, the sampling system further comprises a vacuum pump, the outlet of the vacuum pump is connected to the third pipeline and located between the high-pressure pump and the preheating device, and the outlet of the vacuum pump is provided with a fifth regulating valve.

5. A continuous measurement method of a system for continuous measurement of solubility of an organic substance in supercritical carbon dioxide as claimed in any one of claims 1 to 4, characterized by, The method comprises the following steps: injecting supercritical carbon dioxide fluid and excess organic sample into the high-pressure equilibrium kettle, the organic sample being at least partially dissolved in the supercritical carbon dioxide fluid; adjusting the temperature and pressure in the high-pressure equilibrium kettle to reach a specified temperature and pressure, respectively, and after the dissolution time of the organic sample reaches a specified time, opening the first regulating valve to allow the supercritical carbon dioxide fluid saturated with the dissolved organic sample in the high-pressure equilibrium kettle to enter the sampling bottle, the temperature and pressure in the sampling bottle being the same as those in the high-pressure equilibrium kettle, completing sampling and closing the first regulating valve; separating the sampling bottle from the high-pressure equilibrium kettle and connecting the outlet of the separated sampling bottle with the inlet of the absorption bottle to allow the organic sample and CO2 in the sampling bottle to enter the absorption bottle; When the absorption bottle is a carbon dioxide absorption bottle, carbon dioxide from the sampling bottle is absorbed, and the total mass of the carbon dioxide and the organic sample is obtained by weighing the sampling bottle before and after sampling m , in combination with measuring the change in pH value of the absorption bottle before and after absorbing carbon dioxide gas, the mass of carbon dioxide is calculated according to formula (4) ; and the solubility of the organic sample at a specified temperature and a specified pressure is calculated according to formula (1) and formula (2) S ; or the absorption bottle is an organic matter absorption bottle, the total mass of the carbon dioxide and the organic matter sample is obtained by weighing the mass of the sampling bottle before and after sampling m , and the mass of the organic matter is obtained by weighing the mass of the absorption bottle before and after absorbing the organic matter sample , and the solubility of the organic matter sample at a specified temperature and a specified pressure is calculated according to formula (1) and formula (3) S ; （1） （2） （3） （4） wherein m 0 is the mass of the sampling bottle after sampling, m 1 is the mass of the sampling bottle before sampling; C 0 is the concentration of OH ions in the absorption bottle before absorption of carbon dioxide, - C 1 is the concentration of OH ions in the absorption bottle after absorption of carbon dioxide, - V V is the volume of the solution in the absorption bottle.​​ 6. The method of claim 5, wherein the method further comprises: The carbon dioxide absorption bottle contains an alkali solution, cations of the alkali solution form carbonate precipitate with carbon dioxide, by weighing the mass of the precipitate generated in the absorption bottle, the mass of carbon dioxide in the sampling bottle is calculated according to formula (5) ; （5） In formula (5), is the mass of the precipitate generated in the absorption bottle, M is the molar molecular mass of the precipitate, X is the number of the contained in one precipitate molecule.

7. The method of claim 6, wherein the method further comprises: determining the solubility of the organic compound in supercritical carbon dioxide based on the measured pressure and the measured temperature. comprising, after the sampling bottle is separated from the high-pressure equilibrium kettle, connecting another sampling bottle to the outlet of the high-pressure equilibrium kettle and adjusting the temperature and pressure in the high-pressure equilibrium kettle to achieve another temperature and pressure parameter for sampling.

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