CN108508057B - Low-voltage phase balance experimental device and online sampling and measuring method - Google Patents
Low-voltage phase balance experimental device and online sampling and measuring method Download PDFInfo
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- CN108508057B CN108508057B CN201810669934.2A CN201810669934A CN108508057B CN 108508057 B CN108508057 B CN 108508057B CN 201810669934 A CN201810669934 A CN 201810669934A CN 108508057 B CN108508057 B CN 108508057B
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
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Abstract
The invention provides a low-pressure phase balance experimental device and an online sampling measurement method, which can realize phase balance data measurement and online sampling in a low-pressure environment, ensure that an experiment or industrial process runs continuously without interference, can be suitable for the experimental industrial processes of petroleum, chemistry, metallurgy and the like, provide accurate fluid phase balance experimental data for the experimental industrial processes, and provide basic physical property data for the design, operation, control and optimization of the process industry.
Description
Technical Field
The invention relates to the field of experimental data testing in the fields of petroleum, chemistry and metallurgical industry, in particular to a low-pressure phase balance experimental device and an online sampling and measuring method.
Background
The fluid phase balance property is an essential basic physical property of the industrial process, which determines the accuracy and precision of the simulation calculation of the process, such as the theoretical plate number, the operation reflux ratio and other important parameters of the rectifying tower are closely related to the phase balance property in the calculation of the separating tower, and the rectification, extraction, absorption and leaching are all basic unit operations of the industrial process, and any research on the fluid phase balance property is based on the phase balance physical property of a corresponding system.
Fluid phase equilibrium properties can be obtained by theoretical thermodynamic methods such as empirical correlation, activity coefficients, state equations, and the like. With advances in computational chemistry, predictive models of phase equilibrium properties have also been developed, such as COSMO-RS, COSMO-SAC, and the like. However, although the model method can obtain the fluid phase balance property, the model method must be based on experimental data, otherwise, whether the model method is correct or not cannot be known, and characteristic parameters in many model methods are obtained through regression experimental data, so that it is important to measure the real phase balance data under different conditions through the experimental method.
The measurement of fluid phase equilibrium properties can be classified as static, cyclic, isothermal, or isobaric, depending on the experimental method or type of data obtained. To date, fluid phase balance development has disclosed a vast amount of experimental data, including low pressure, normal pressure and high pressure data, especially with normal pressure data, because measurement of normal pressure fluid phase balance does not involve the problems of pressure balance and control, collection of low pressure samples, etc., and experiments are directly performed in an atmospheric environment. For low pressure systems (i.e. the internal pressure of the experimental system is lower than the atmospheric pressure), it is necessary to consider how the pressure is constant, how the sample is collected, how external disturbances are reduced as much as possible, etc., and these technical problems directly affect the accuracy of the measurement of the fluid phase equilibrium properties.
In experimental work, it is often necessary to perform the experimental operation at low pressure due to the specificity of the system. However, whether in actual industrial production or laboratory research, the samples must be analyzed at regular time or under certain conditions, but how to obtain effective samples for analysis is a continuing challenge in the case of continuous operation of the device. Currently, in both industry and laboratory, samples at pressures above atmospheric are typically sampled directly by a sampling bottle, but when the pressure is too high, the sample flashes off during sampling, so that the obtained sample cannot represent the original constituent. For the sample under low pressure, the pressure of the sample to be taken is low, so that the sample cannot directly enter the sampling bottle, the pressure in the sampling bottle must be kept not higher than the system pressure before sampling, the sampling of the sample under low pressure is complicated, and the sample has high tightness.
In order to facilitate on-line sampling in a low-pressure environment in a low-pressure phase balance experiment, enable an experiment or an industrial process to run continuously without interference, and obtain accurate fluid phase balance data, particularly vapor-liquid phase balance data, it is necessary to design a low-pressure phase balance experiment device and an on-line sampling method.
Disclosure of Invention
The invention aims to solve the technical problems that: in order to overcome the defects of the prior art, the invention provides a low-pressure phase balance experimental device and an online sampling measurement method for realizing phase balance measurement and online sampling in a low-pressure environment, so that an experiment or industrial process runs continuously without interference, the device can be applied to the experimental industrial processes of petroleum, chemistry, metallurgy and the like, provides accurate fluid phase balance experimental data for the experimental industrial processes, and provides basic physical property data for the design, operation, control and optimization of the process industry.
The technical scheme adopted for solving the technical problems is as follows: the low-pressure phase balance experimental device comprises a distillation balance system, a cooling circulation system and a pressure stabilizing automatic control system, wherein the distillation balance system is communicated with the upper part of the cooling circulation system through a circulating cooler pipeline, the distillation balance system is communicated with the bottom of the cooling circulation system through a liquid return pipeline, a pressure balance guide pipe is arranged in the cooling circulation system, the top of the pressure balance guide pipe extends out of the upper top of the cooling circulation system and is respectively provided with a pressure measuring port and a pressure stabilizing system interface, and the pressure stabilizing system interface is communicated with the pressure stabilizing automatic control system; the bottom of the cooling circulation system is provided with a sampling port, the end part of the liquid return pipe is connected with the sampling port, the other side of the sampling port corresponding to the liquid return pipe is provided with an online sampling interface, the side wall of the lower part of the distillation balance system is also provided with an online sampling interface, and a sampling device is fixedly connected to the online sampling interface; the sampling device comprises a sample receiving assembly, a pressurizing assembly and a vacuum assembly, wherein an online sampling pressure pipeline is communicated at an online sampling interface, the sample receiving assembly comprises a liquid receiving pipe fastening nut which is fixedly communicated below the online sampling interface and an online liquid receiving pipe which is connected below the liquid receiving pipe fastening nut, the pressurizing assembly comprises an emptying port and a pressurizing valve which are communicated with the online sampling pressure pipeline, the vacuum assembly comprises a vacuum system and a sampler pressure control valve which is communicated with the online sampling pressure pipeline, and the vacuum system is connected to the lower end of the sampler pressure control valve through a vacuum system interface.
The distillation balance system comprises a cylindrical distillation body, temperature measuring sleeves are respectively fixed in the top and the side walls of the distillation body, sample adding ports are formed in the circumferential side walls of the distillation body, which correspond to the bottom positions of the side wall temperature measuring sleeves, liquid blocking pipes are fixed below the temperature measuring sleeves in the top of the distillation body, liquid spraying coils are fixed at the bottoms of the temperature measuring sleeves in the side walls of the distillation body, a fluid cover is fixed below the liquid spraying coils, a balancer boiling chamber is arranged between the fluid cover and the bottom of the distillation body, a stirring device is arranged in the balancer boiling chamber, distillation sampling ports are formed in the top of the balancer boiling chamber, which correspond to the side walls of the distillation body, air entraining pipes communicated with the outside are fixed in the balancer boiling chamber, and air entraining valves are arranged in the air entraining pipes.
The stirring device may be a mechanical stirrer or a magnetic stirrer. A heating system is designed at the bottom of the boiling chamber of the balancer, and can adopt electric heating, water/oil bath jacket heating and coil heating modes, wherein the temperature operation range is room temperature to 120 ℃, and the preferable temperature range is room temperature to 90 ℃. The height of the spray coil ranges from 40mm to 80mm. The liquid level at which the sample is added must be 10mm to 50mm above the apex of the fluid enclosure. The outlet of the spray liquid coil pipe is opposite to the bottom of the temperature measuring sleeve in the side wall of the distillation body. The flow rate of the cooling medium is such that the rate of droplets falling through the droplet tube is not greater than 120 droplets per minute.
The pressure-stabilizing automatic control system comprises a controller and a pressure-stabilizing buffer tank connected with the distillation balance system through a pressure-stabilizing system interface, wherein a second regulating valve and an electromagnetic valve are sequentially connected to a pipeline between the pressure-stabilizing buffer tank and the pressure-stabilizing system interface, a pressure gauge and a vent are arranged at the top of the pressure-stabilizing buffer tank, and two ends of the pressure-stabilizing buffer tank are respectively communicated with a pressure supplementing component and a pressure reducing component; the pressure supplementing assembly comprises a pressure source, a pressure reducing valve, an electromagnetic valve and a third regulating valve which are sequentially connected, the third regulating valve is communicated with a pressure stabilizing buffer tank pipeline, the pressure reducing assembly comprises a first regulating valve, an electromagnetic valve and a vacuum pump which are sequentially connected, and the pressure reducing assembly further comprises a ball valve which is connected with the first regulating valve in parallel; and the pressure measuring port and the pressure stabilizing buffer tank are respectively connected with a pressure sensor.
The cooling circulation system is a coil condenser, and the circulation cooler is a jacket condenser. The cooling medium of the coil condenser and the jacket condenser is circulating water, hot water or heat conducting oil.
After a certain amount of experimental samples are added into the distillation balance system through the sample adding port and the system pressure reaches a target value, the samples are heated through electric heating, wherein the heating mode can be external heating or internal heating, and stirring is performed while heating. After the liquid boils, the boiling fluid is ejected from the liquid spraying coil pipe under the forced action of the liquid flow cover, the vapor phase and the liquid phase are separated in the liquid blocking pipe, the liquid phase returns to the balancer boiling chamber to be mixed with the main body, and the gas phase flows into the cooling circulation system.
Through two online sampling interfaces and the sampling device connected with the online sampling interfaces, online sampling can be realized, gas and liquid are respectively sampled online, continuous operation of vapor-liquid phase balance experiments with different horizontal pressures is realized, and the experiment or industrial process is continuously operated without interference.
An online sampling measurement method of a low-voltage phase balance experimental device comprises the following measurement steps:
A. checking the states of each regulating valve and each electromagnetic valve, confirming that the positions of each regulating valve and each electromagnetic valve are correct, adding about 300ml of experimental sample through the sample adding port, and closing the vacuum valve of the sample adding port;
B. closing all the regulating valves and the electromagnetic valves of the pressure stabilizing buffer tank, and starting the controller at the same time;
C. opening a vacuum pump, and slowly opening a ball valve after the vacuum pump stably operates;
D. observing a pressure gauge at the top of the pressure stabilizing buffer tank, and gradually closing the ball valve and opening the first regulating valve and the third regulating valve when the pressure gauge approaches to the experimental target value;
E. after the pressure of the pressure stabilizing buffer tank reaches and is stabilized at a target value, slowly opening a second regulating valve to enable the pressure of the experimental system to reach the target value;
F. after the whole system is stable, the boiling chamber of the balancer is slowly heated, so that the temperature of the system is gradually increased;
G. heating and simultaneously opening the stirring device and the air-entraining valve on the air-entraining pipe;
H. after the liquid in the boiling chamber of the balancer boils, adjusting the heating load, keeping the temperature of the system constant, and observing the reflux quantity of the cooling circulation system, wherein the reflux speed is not more than 120 drops/min;
I. after the system is stable for 30 minutes, reading the temperature and pressure experimental values every 5 minutes, reading 10 groups in total, and taking an average value;
J. and adjusting the target value of the control pressure, and measuring the next experimental point.
The low-pressure phase balance experimental device and the online sampling method provided by the invention have the beneficial effects that online sampling can be realized in a low-pressure environment, so that an experiment or an industrial process can run continuously without interference, the device and the method can be applied to experimental industrial processes such as petroleum, chemistry and metallurgy, accurate fluid phase balance experimental data can be provided for the experimental industrial processes, and basic physical property data can be provided for design, operation, control and optimization of the process industry.
Drawings
The invention will be further described with reference to the drawings and examples.
FIG. 1 is a schematic diagram of the distillation balance system and cooling circulation system of the present invention.
FIG. 2 is a flow chart of the pressure control system of the present invention.
FIG. 3 is a schematic diagram of a sampling device according to the present invention.
Fig. 4 is a cross-sectional view of B-B in fig. 3.
FIG. 5 is a graph comparing the saturated vapor pressure of the pure substances tested in the present invention with the literature values.
FIG. 6 is a T-x (y) plot of the vapor-liquid equilibrium data for a binary mixture of tetrachloroethylene and 1-butanol measured in accordance with the present invention at an absolute pressure of 6kPa versus a comparison of the literature.
FIG. 7 is an x-y plot of the vapor-liquid equilibrium data for a binary mixture of tetrachloroethylene and 1-butanol at an absolute pressure of 6kPa versus a literature comparison.
In the figure, 1, a liquid return pipe 2, a pressure balance guide pipe 3, a cooling circulation system 4, a circulation cooler 5, a pressure measuring port 6, a pressure stabilizing system interface 7, a sampling port 8, an online sampling interface 9, a liquid receiving pipe compact nut 10, an online liquid receiving pipe 11, an online sampling pressure pipeline 12, a vent port 13, a pressure increasing valve 14, a sampler pressure control valve 15, a distillation body 16, a temperature measuring sleeve 17, a sample adding port 18, a liquid blocking pipe 19, a liquid spraying coil 20, a fluid cover 21, a balancer boiling chamber 22, a stirring device 23, a distillation sampling port 24, a pressure stabilizing buffer tank 25, a second regulating valve 26, an electromagnetic valve 27, a pressure gauge 28, a vent port 29, a pressure source 30, a pressure reducing valve 31, a third regulating valve 32, a first regulating valve 33, a vacuum pump 34, a ball valve 35, a pressure sensor 36 and a gas guiding pipe are shown.
Detailed Description
The invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic representations which merely illustrate the basic structure of the invention and therefore show only the structures which are relevant to the invention.
The low-pressure phase balance experimental device shown in fig. 1 to 4 is a preferred embodiment of the present invention, and comprises a distillation balance system, a cooling circulation system 3 and a pressure stabilizing automatic control system.
The distillation balance system is communicated with the upper part of the cooling circulation system 3 through a pipeline of a circulating cooler 4, the distillation balance system is communicated with the bottom of the cooling circulation system 3 through a pipeline of a liquid return pipe 1, a pressure balance conduit 2 is arranged in the cooling circulation system 3, the top of the pressure balance conduit 2 extends out of the upper top of the cooling circulation system 3 and is respectively provided with a pressure measuring port 5 and a pressure stabilizing system interface 6, and the pressure stabilizing system interface 6 is communicated with a pressure stabilizing automatic control system; the bottom of the cooling circulation system 3 is provided with a sampling port 7, the end part of the liquid return pipe 1 is connected with the sampling port 7, the other side of the sampling port 7 corresponding to the liquid return pipe 1 is provided with an on-line sampling port 8, the side wall of the lower part of the distillation balance system is also provided with an on-line sampling port 8, and a sampling device is fixedly connected to the on-line sampling port 8; the sampling device comprises a sample receiving assembly, a pressurizing assembly and a vacuum assembly, wherein an online sampling pressure pipeline 11 is communicated at an online sampling interface 8, the sample receiving assembly comprises a liquid receiving pipe fastening nut fixedly communicated below the online sampling interface 8 and an online liquid receiving pipe 10 connected below the liquid receiving pipe fastening nut 9, the pressurizing assembly comprises a vent 2812 and a pressurizing valve 13 which are communicated with the online sampling pressure pipeline 11, the vacuum assembly comprises a vacuum system and a sampler pressure control valve 14 communicated with the online sampling pressure pipeline 11, and the vacuum system is connected to the lower end of the sampler pressure control valve 14 through a vacuum system interface.
The cooling circulation system 3 is a coil condenser, and the circulation cooler 4 is a jacket condenser. The cooling medium of the coil condenser and the jacket condenser is circulating water, hot water or heat conducting oil. The cooling medium can be cold water, warm water or other low-temperature medium according to the nature of the practical experiment system, so that the vapor phase from the distillation balance system is cooled into liquid under the pressure condition of the system and flows back to the boiling chamber in a natural flow mode. In the cooling circulation system 3, a liquid collector is provided to facilitate collection and analysis of the sample.
The distillation balance system comprises a cylindrical distillation body 15, wherein temperature measuring sleeves 16 are respectively fixed on the top and the side walls of the distillation body 15, sample adding ports 17 are formed in the circumferential side walls of the distillation body 15 corresponding to the bottom positions of the side wall temperature measuring sleeves 16, liquid blocking pipes 18 are fixed below the temperature measuring sleeves 16 in the top of the distillation body 15, liquid spraying coils 19 are fixed below the liquid spraying coils 19, a fluid cover 20 is fixed below the liquid spraying coils 19, a balancer boiling chamber 21 is arranged between the fluid cover 20 and the bottom of the distillation body 15, a stirring device 22 is arranged in the balancer boiling chamber 21, distillation sampling ports 23 are formed in the top of the balancer boiling chamber 21 corresponding to the side walls of the distillation body 15, air entraining pipes 36 communicated with the outside are fixed in the balancer boiling chamber 21, and air entraining valves are arranged in the air entraining pipes 36. The stirring device 22 and the bleed air pipe 36 eliminate the experimental impact of bumping.
The automatic pressure stabilizing control system comprises a controller and a pressure stabilizing buffer tank 24 connected with a distillation balance system through a pressure stabilizing system interface 6, wherein a second regulating valve 25 and an electromagnetic valve 26 are sequentially connected to a pipeline between the pressure stabilizing buffer tank 24 and the pressure stabilizing system interface 6, a pressure gauge 27 and a vent 2812 are arranged at the top of the pressure stabilizing buffer tank 24, and two ends of the pressure stabilizing buffer tank 24 are respectively communicated with a pressure supplementing component and a pressure reducing component; the pressure supplementing assembly comprises a pressure source 29, a pressure reducing valve 30, an electromagnetic valve 26 and a third regulating valve 31 which are sequentially connected, the third regulating valve 31 is in pipeline communication with the pressure stabilizing buffer tank 24, the pressure reducing assembly comprises a first regulating valve 32, the electromagnetic valve 26 and a vacuum pump 33 which are sequentially connected, and the pressure reducing assembly further comprises a ball valve 34 which is connected with the first regulating valve 32 in parallel; the pressure measuring port 5 and the pressure stabilizing buffer tank 24 are respectively connected with a pressure sensor 35.
In a particular experimental or industrial process, the stirring device 22 may be a mechanical stirrer or a magnetic stirrer. A heating system is designed at the bottom of the balancer boiling chamber 21, and the heating system can adopt electric heating, water/oil bath jacket heating and coil heating modes, and the temperature operation range is room temperature to 180 ℃, and the preferable temperature range is room temperature to 150 ℃. The spray coil 19 has a height in the range of 40mm to 80mm. The liquid level of the added sample must be 10mm to 50mm above the apex of the fluid enclosure 20. The outlet of the spray coil 19 is opposite to the bottom of the temperature measuring sleeve 16 in the side wall of the distillation body 15. The flow rate of the cooling medium is such that the rate of droplets falling through the droplet tube is not greater than 120 droplets per minute.
After a certain amount of experimental samples are added into the distillation balance system through the sample adding port 17 and the system pressure reaches a target value, the samples are heated through electric heating, wherein the heating mode can be external heating or internal heating, and stirring is performed while heating. After the liquid is boiled, the boiling fluid is sprayed out of the liquid spraying coil 19 under the forced action of the liquid flow cover, the vapor phase and the liquid phase are separated in the liquid blocking pipe 18, the liquid phase returns to the balancer boiling chamber 21 to be mixed with the main body, and the gas phase flows into the cooling circulation system 3.
The sampling can be performed by an on-line sampling device without interrupting the experimental or industrial process. The on-line sampling structure is a spherical interface, is connected with a container to be sampled (a sampling port 7 at the bottom of the cooling circulation system 3 or the side wall at the lower part of the distillation balance system), closes a sampler pressure control valve 14, an emptying valve and the sampling port 7 before connection, and connects a vacuum system interface with a vacuum system; then slowly opening the sampler pressure control valve 14 to make the pressure in the sampling device equal to or slightly lower than the pressure of the container to be sampled (the bottom sampling port 7 of the cooling circulation system 3 or the lower side wall of the distillation balance system) and keeping the pressure unchanged; slowly opening the sampling port 7, enabling a sample in a container to be sampled (the sampling port 7 at the bottom of the cooling circulation system 3 or the side wall at the lower part of the distillation balance system) to slowly flow into the online liquid receiving pipe 10 through a spherical interface, putting a solvent into the online liquid receiving pipe 10 in advance to fix the sample, and closing the sampling port 7 after the sample in the online liquid receiving pipe 10 reaches a certain amount; after the sampler pressure control valve 14 is closed again, the pressure increasing valve 13 is slowly opened, so that the pressure in the sampling device is restored to the atmospheric pressure, and the air-sensitive sample can be introduced with protective nitrogen through the vent 2812; finally, the sample is sampled and analyzed through a sampling port 7, or the online liquid receiving pipe 10 is taken out through a liquid receiving pipe fastening nut, and then the sample is further processed and analyzed.
Preferably, the sampling device pressure is operated in the range of 0.1kPa absolute to 1 atm and the sampling device temperature is operated in the range of room temperature to 280 ℃.
Through two on-line sampling interfaces 8 and the sampling device who is connected with on-line sampling interface 8, can realize on-line sampling, carry out on-line sampling to gas and liquid respectively, realize the continuous operation of different horizontal pressure vapour-liquid phase balance experiments, make experiment or industrial process continuous operation and not disturbed.
An online sampling and measuring method of a low-voltage phase balance experimental device can adopt the sampling and measuring device to sample and use the following measuring steps to carry out experiments.
A. Checking the states of the regulating valves and the electromagnetic valves 26, confirming that the positions of the regulating valves and the electromagnetic valves 26 are correct, adding about 300ml of experimental sample through the sample adding port 17, and closing the vacuum valve of the sample adding port 17;
B. closing all the regulating valves and solenoid valves 26 of the surge tank 24 while starting the controller;
C. opening the vacuum pump 33, and slowly opening the ball valve 34 after the vacuum pump 33 stably operates;
D. observing the pressure gauge 27 at the top of the surge tank 24, gradually closing the ball valve 34 and opening the first regulating valve 32 and the third regulating valve 31 when the value approaches the experimental target value;
E. after the pressure of the pressure stabilizing buffer tank 24 reaches and stabilizes at the target value, slowly opening the second regulating valve 25 to enable the pressure of the experimental system to reach the target value;
F. after the whole system is stable, the balancer boiling chamber 21 is slowly heated to gradually increase the temperature of the system;
G. heating while opening the mixing device 22 and the bleed valves on the bleed air pipe 36;
H. after the liquid in the balancer boiling chamber 21 boils, the heating load is adjusted to keep the system temperature constant, and the reflux amount of the cooling circulation system 3 is observed, wherein the reflux speed is not more than 120 drops/min;
I. after the system is stable for 30 minutes, reading the temperature and pressure experimental values every 5 minutes, reading 10 groups in total, and taking an average value;
J. and adjusting the target value of the control pressure, and measuring the next experimental point.
By adopting the measuring steps, the saturated vapor pressure of the ethanol and the water pure components can be measured, and the measured experimental data and the comparison result of the literature values are drawn in the figure 5, so that the two are consistent, and the sampling measuring device and the measuring method provided by the invention can be used for measuring the saturated vapor pressure of the pure fluid.
By adopting the measurement steps, the vapor-liquid balance of the binary mixture of tetrachloroethylene and 1-butanol at the absolute pressure of 6kPa can be measured, and the results are plotted in the figures 6 and 7, wherein the T-x (y) diagram and the x-y diagram of the phase balance are respectively compared in the figures 6 and 7, and the experimental data and the literature value are compared to find that the two diagrams are consistent, so that the sampling measurement device and the measurement method provided by the invention can be used for measuring the vapor-liquid balance of the mixture.
With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.
Claims (3)
1. The utility model provides a low pressure phase balance experimental apparatus which characterized in that: the device comprises a distillation balance system, a cooling circulation system (3) and a pressure stabilizing automatic control system, wherein the distillation balance system is communicated with the upper part of the cooling circulation system (3) through a pipeline of a circulating cooler (4), the distillation balance system is communicated with the bottom of the cooling circulation system through a pipeline of a liquid return pipe (1), a pressure balance conduit (2) is arranged in the cooling circulation system, the top of the pressure balance conduit (2) extends out of the upper part of the cooling circulation system (3) and is respectively provided with a pressure measuring port (5) and a pressure stabilizing system interface (6), and the pressure stabilizing system interface (6) is communicated with the pressure stabilizing automatic control system; the bottom of the cooling circulation system (3) is provided with a sampling port (7), the end part of the liquid return pipe (1) is connected with the sampling port (7), the other side of the sampling port (7) corresponding to the liquid return pipe (1) is provided with an online sampling interface (8), the side wall of the lower part of the distillation balance system is also provided with an online sampling interface (8), and a sampling device is fixedly connected to the online sampling interface (8); the sampling device comprises a sampling component, a pressurizing component and a vacuum component, wherein an online sampling pressure pipeline (11) is communicated at the online sampling interface (8), the sampling component comprises a liquid receiving pipe fastening nut (9) fixedly communicated below the online sampling interface (8) in a sealing way and an online liquid receiving pipe (10) connected below the liquid receiving pipe fastening nut (9), the pressurizing component comprises a vent (12) and a pressurizing valve (13) which are communicated with the online sampling pressure pipeline (11), the vacuum component comprises a vacuum system and a sampler pressure control valve (14) communicated with the online sampling pressure pipeline (11), and the vacuum system is connected to the lower end of the sampler pressure control valve (14) through a vacuum system interface (15);
the distillation balance system comprises a cylindrical distillation body (15), wherein temperature measuring sleeves (16) are respectively fixed in the top and the side walls of the distillation body (15), sample adding ports (17) are formed in the circumferential side walls of the distillation body (15) corresponding to the bottom positions of the side wall temperature measuring sleeves (16), liquid blocking pipes (18) are fixed below the temperature measuring sleeves (16) in the top of the distillation body (15), liquid spraying coils (19) are fixed at the bottoms of the temperature measuring sleeves (16) in the side walls of the distillation body (15), fluid covers (20) are fixed below the liquid spraying coils, a balancer boiling chamber (21) is arranged between the fluid covers (20) and the bottoms of the distillation body (15), stirring devices (22) are arranged in the balancer boiling chamber (21), distillation sampling ports (23) are formed in the side walls of the balancer boiling chamber (21) corresponding to the distillation body (15), air entraining pipes (26) communicated with the outside are fixed in the balancer boiling chamber (21), and air entraining valves are arranged in the air entraining pipes (36);
the automatic pressure stabilizing control system comprises a controller and a pressure stabilizing buffer tank (24) connected with a distillation balance system through a pressure stabilizing system interface (6), wherein a second regulating valve (25) and an electromagnetic valve (26) are sequentially connected to a pipeline between the pressure stabilizing buffer tank (24) and the pressure stabilizing system interface (6), a pressure gauge (27) and an emptying port (28) are arranged at the top of the pressure stabilizing buffer tank (24), and two ends of the pressure stabilizing buffer tank (24) are respectively communicated with a pressure supplementing component and a pressure reducing component; the pressure supplementing assembly comprises a pressure source (29), a pressure reducing valve (30), an electromagnetic valve (26) and a third regulating valve (31) which are sequentially connected, the third regulating valve (31) is in pipeline communication with the pressure stabilizing buffer tank (24), the pressure reducing assembly comprises a first regulating valve (32), the electromagnetic valve (26) and a vacuum pump (33) which are sequentially connected, and the pressure reducing assembly further comprises a ball valve (34) which is connected with the first regulating valve (32) in parallel; pressure sensors (35) are respectively connected to the pressure measuring port (5) and the pressure stabilizing buffer tank (24).
2. A low pressure phase equilibrium experiment apparatus as claimed in claim 1, wherein: the cooling circulation system (3) is a coil condenser, and the circulation cooler (4) is a jacket condenser.
3. An online sampling and measuring method of a low-voltage phase balance experimental device is characterized by comprising the following steps of: the low-pressure phase balance experiment device adopting the device as claimed in claim 1 comprises the following measuring steps:
A. checking the states of the regulating valves and the electromagnetic valves (26), confirming that the positions of the regulating valves and the electromagnetic valves (26) are correct, adding about 300ml of experimental sample through the sample adding port (17), and closing the vacuum valve of the sample adding port (17);
B. closing all regulating valves and electromagnetic valves of the pressure stabilizing buffer tank (24) and simultaneously starting a controller;
C. opening a vacuum pump (33), and slowly opening a ball valve (34) after the vacuum pump (33) runs stably;
D. observing a pressure gauge (27) at the top of the surge tank (24), and gradually closing the ball valve (34) and opening the first regulating valve (32) and the third regulating valve (31) when the value approaches the experimental target value;
E. after the pressure of the pressure stabilizing buffer tank (24) reaches and stabilizes at a target value, slowly opening a second regulating valve (25) to enable the pressure of the experimental system to reach the target value;
F. after the whole system is stable, the boiling chamber (21) of the balancer is slowly heated, so that the temperature of the system is gradually increased;
G. heating and simultaneously opening the stirring device (22) and the air-entraining valve on the air-entraining pipe;
H. after the liquid in the balancer boiling chamber (21) boils, the heating load is regulated, the system temperature is kept constant, and the reflux quantity of the cooling circulation system (3) is observed, wherein the reflux speed is not more than 120 drops/min;
I. after the system is stable for 30 minutes, reading the temperature and pressure experimental values every 5 minutes, reading 10 groups in total, and taking an average value;
J. and adjusting the target value of the control pressure, and measuring the next experimental point.
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| CN113624570B (en) * | 2021-08-06 | 2023-04-28 | 清华大学 | Vapor-liquid phase balance device and method for analyzing HF in fluorocarbon |
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