CN212410482U

CN212410482U - High-purity organic matter purity measuring device based on freezing point depression method

Info

Publication number: CN212410482U
Application number: CN202020243354.XU
Authority: CN
Inventors: 刘运传; 王雪蓉; 周燕萍; 王倩倩; 姚凯; 马衍东; 郑会保; 冀克俭
Original assignee: Shandong Non Metallic Material Research Institute
Current assignee: Shandong Non Metallic Material Research Institute
Priority date: 2020-03-03
Filing date: 2020-03-03
Publication date: 2021-01-26
Anticipated expiration: 2030-03-03

Abstract

The utility model discloses a high-purity organic matter purity measuring device based on a freezing point descending method. It includes a Dewar flask, a sample thermal insulation environment providing unit, and a sample pool. The lower part of the upper cover of the Dewar flask has an insulating vacuum chamber in the shape of a bulb, and the upper cover is provided with a line pipe, a liquid nitrogen level gauge, and a liquid nitrogen delivery pipe. , Evacuation tube, nitrogen pressure relief tube, a heater trap with a built-in heater in the sample cell, a platinum resistance temperature sensor on the outside of the sample cell, two capillaries on the sample cell, and the sample thermal insulation environment includes a multi-layer thermal insulation screen and In the vacuum chamber, manganese copper wire is wound outside each layer of insulation screen as a heater, the sample cell is suspended in the innermost layer of insulation screen, and the inner layer of insulation screen in the adjacent two layers of insulation screen is suspended from the outer layer of insulation screen. The inner and outermost thermal insulation screens are suspended in the vacuum chamber, and the vacuum chamber is set in the Dewar flask. There are several pairs of anti-series thermocouples respectively.

Description

High-purity organic matter purity measuring device based on freezing point depression method

Technical Field

The utility model relates to a high-purity organic matter purity measuring device, in particular to high-purity organic matter purity measuring device based on freezing point depression method.

Background

At present, the purity of organic matters is generally measured by gas chromatography in China, and the uncertainty of the purity measurement of the organic matters with the purity of more than 95 percent is 0.3 percent, so that the requirement of measuring the purity of ultra-clean high-purity organic matters cannot be met. The freezing point depression method is based on the principle of solvent colligative property, and when the dilute solution is cooled to the freezing point and only pure solvent is separated out, the value of freezing point depression is in direct proportion to the quantity of solute contained in the dilute solution, and is independent of the type of solute. The freezing point depression method is suitable for measuring the purity of organic matters with the purity of more than 98 percent, the expansion uncertainty can reach 0.004 percent, and the accuracy of the organic matter sample with higher purity is better. Therefore, the method for measuring the purity of the organic matter by the freezing point depression method is an accurate and reliable classical measurement method.

There is no reliable high-purity organic matter purity measuring device based on freezing point depression method in the prior art.

Disclosure of Invention

To the above-mentioned defect that exists among the prior art, the utility model provides a high-purity organic matter purity measuring device suitable for freezing point depression method measures organic matter purity.

The utility model discloses a realize through following technical scheme: the utility model provides a high-purity organic matter purity measuring device based on freezing point depression method which characterized by: the device comprises a Dewar flask, a sample heat insulation environment providing unit and a sample cell, wherein the Dewar flask comprises a flask body and an upper cover detachably connected with the flask body, the lower part of the upper cover is provided with a heat insulation vacuum chamber in a spherical segment shape, the spherical crown surface of the heat insulation vacuum chamber is positioned in the Dewar flask, the upper cover is provided with a line pipe, a liquid nitrogen level meter, a liquid nitrogen delivery pipe, a vacuum pumping pipe and a nitrogen pressure relief pipe, a heater trap is arranged in the sample cell, a heater is arranged in the heater trap, the outer side of the sample cell is provided with a platinum resistance temperature sensor, the sample cell is provided with two capillary tubes communicated with the interior of the sample cell, the sample heat insulation environment comprises a plurality of layers of heat insulation screens and vacuum chambers arranged at the periphery of the sample cell, a manganese copper wire is wound outside each layer of heat insulation screen to serve as the heater, the sample cell is suspended in the heat insulation screen at the innermost layer, and the inner layer of the two, the outermost heat insulation screen is suspended in the vacuum chamber, the vacuum chamber is arranged in the Dewar flask, the upper part of the vacuum chamber is provided with a flange for sealing connection, the vacuum chamber is communicated with the heat insulation vacuum chamber through a vacuum chamber connecting pipe, a plurality of pairs of thermocouples which are reversely connected are respectively arranged between the sample cell and the inner heat insulation screen and between the adjacent heat insulation screens, and leads of the heater in the sample cell, each thermocouple, the platinum resistance temperature sensor and the heater of each heat insulation screen are all led out to the outside of the Dewar flask through the vacuum chamber connecting pipe and the line pipe.

The utility model discloses in, the heater that sets up in the heater trap of sample cell is used for heating the sample in the sample cell, the temperature that the platinum resistance sensor who sets up at the sample cell lateral surface is used for detecting the sample cell, it is used for providing adiabatic environment for the sample to set up at the adiabatic screen of sample cell outlying multilayer and real empty room, the setting is between sample cell and adiabatic screen, the thermocouple between adiabatic screen and the adiabatic screen is used for measuring the difference in temperature, so that the difference in temperature between control sample cell and the adiabatic screen is 0.001 ℃. The utility model discloses during the use, the liquid nitrogen conveyer pipe is connected with liquid nitrogen feeding device, the evacuation pipe is connected with evacuation equipment, heater in the sample cell, each thermocouple, platinum resistance temperature sensor, the heater of each adiabatic screen is connected the sample and is melted the electric work respectively and supply to with measuring unit and sample melting temperature measuring unit, let in the liquid nitrogen in to the dewar bottle through liquid nitrogen feeding device, utilize the liquid nitrogen to reduce the temperature in the dewar bottle, provide the low temperature measurement environment for the sample, give real empty room and thermal-insulated real room evacuation through evacuation equipment, supply with the heating of measuring unit and sample melting temperature measuring unit control sample cell and carry out data acquisition through sample melting electric work. The utility model provides a thermal-insulated real empty room is after the evacuation, and the vacuum is formed in its spherical segment, can effectively reduce the inside heat exchange with the laboratory environment of dewar bottle. The utility model provides a two capillaries that set up on the sample cell are used for cleaning the sample cell, during the use, connect high-purity gas to one of them capillary, discharge from another capillary through high velocity air flow liquid in the sample cell, through the multiple operation cleaning sample cell.

Furthermore, in order to facilitate connection and ensure the safety of the measuring process, the bottle body and the upper cover of the Dewar bottle are connected by a flange.

Furthermore, in order to ensure the sealing performance of the vacuum chamber, a polytetrafluoroethylene sealing gasket is arranged between flanges at the upper part of the vacuum chamber, two sealing rings with triangular sections are respectively arranged on the sealing surfaces of the two flanges, and the two flanges are connected through spring bolts. The two sealing rings with triangular sections arranged on the flange sealing surface are matched with the polytetrafluoroethylene sealing gasket, so that the sealing effect of the flange can be greatly improved, the sealing effect of the vacuum chamber is improved, and the vacuum chamber and the Dewar flask are isolated. The two flanges are connected through the spring bolt, the spring bolt is utilized to compress the flanges, the spring is always in a compression state, in the whole test process, the spring bolt automatically exerts pressure, the sealing rings of the two flanges are kept to compress the polytetrafluoroethylene sealing gasket all the time, failure caused by factors such as temperature reduction and vacuumizing of the vacuum chamber is avoided, and the sealing performance of the vacuum chamber is guaranteed.

Furthermore, one end of the vacuum chamber connecting pipe is fixedly connected with the bottom of the heat insulation vacuum chamber, and the other end of the vacuum chamber connecting pipe is fixedly connected with a flange on the upper part of the vacuum chamber.

Further, the vacuum chamber and the heat-insulating screen are both cylindrical structures.

Further, the liquid nitrogen delivery pipe is communicated with the bottom of the Dewar flask.

Further, the platinum resistance temperature sensor is fixed at the center of the outer wall of the sample cell through glue bonding.

The utility model has the advantages that: the utility model provides a low temperature heat insulation environment of the sample by adopting the Dewar flask and the liquid nitrogen and the vacuum device in the Dewar flask, and can reduce the heat exchange of the sample near the freezing point caused by heat radiation and air convection so as to ensure the accuracy and reliability of the experimental process; the design of the multi-layer radiation-proof heat-insulating screen in the vacuum environment can further improve the heat-insulating property of the sample environment of the sample pool. The utility model discloses can provide strict adiabatic environment for being surveyed the sample, have high measurement accuracy and reliability, can regard as the standard device of certain material purity measurement and standard substance's research and development device for realize that the quantity value of purity measurement traces to the source.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of the present invention;

FIG. 2 is a schematic diagram of the construction of the sample cell portion of FIG. 1;

FIG. 3 is a schematic view of the vacuum chamber of the present invention;

FIG. 4 is a schematic view of a flange sealing structure of the vacuum chamber of the present invention;

FIG. 5 is a schematic view of the upper flange of FIG. 4;

FIG. 6 is a schematic view of the lower flange of FIG. 4;

FIG. 7 is a schematic view of a meter connection according to an embodiment of the present invention;

FIG. 8 is a time-temperature curve for a blank sample cell with no sample added in accordance with an embodiment;

FIG. 9 is a time-temperature curve for a sample cell with benzene added in accordance with an embodiment;

FIG. 10 is a graph of electrical function versus temperature for a blank cell with no sample added in accordance with an embodiment;

FIG. 11 is a graph of electrical function versus temperature for a sample cell with benzene added in an embodiment;

FIG. 12 is a graph of electrical function versus temperature for a sample under test with the heat absorbed by the blank sample cell subtracted by interpolation in one embodiment;

in the figure, 1, a line pipe, 2, a liquid nitrogen level meter, 3 and a liquid nitrogen delivery pipe; 4. vacuumizing a tube; 5. a nitrogen pressure relief pipe; 6. an upper cover of the dewar flask; 7. a bolt; 8. a thermally insulated vacuum chamber; 9. a spherical crown surface of the vacuum chamber; 10. a vacuum chamber connecting pipe; 11. a flange of the vacuum chamber; 111. a lower flange of the vacuum chamber 112, an upper flange of the vacuum chamber 12, a spring bolt; 13. a seal ring; 14. a polytetrafluoroethylene seal gasket; 15. a vacuum chamber; 16. an insulating screen; 17. a heat-insulating screen suspension wire; 18. a support bar; 19. an insulating screen; 20. a capillary tube; 21. a sample cell; 22. heater trap, 23, dewar, 24, platinum resistance temperature sensor, 25, hook, 26, heater, 27, thermocouple.

Detailed Description

The invention will now be further described by way of non-limiting examples with reference to the accompanying drawings:

as shown in fig. 1 to 6, the high purity organic matter purity measuring apparatus based on the freezing point depression method comprises a dewar 23, a sample adiabatic environment providing unit, and a sample cell 21. The Dewar flask 23 is made of stainless steel plates, the Dewar flask 23 comprises a flask body and an upper cover 6, a flange connection structure is adopted between the flask body and the upper cover 6, the lower part of the upper cover 6 is provided with a heat insulation vacuum chamber 8 in a spherical segment shape, and a spherical crown surface 9 of the heat insulation vacuum chamber 8 is positioned inside the Dewar flask 23. The upper cover 6 is provided with a line pipe 1, a liquid nitrogen level meter 2, a liquid nitrogen delivery pipe 3, a vacuum-pumping pipe 4 and a nitrogen pressure relief pipe 5. Preferably, the liquid nitrogen delivery pipe 3 opens into the bottom of the dewar 23. The sample cell 21 is processed by a copper tube, a heater trap 22 is arranged in the sample cell 21, and a heater is arranged in the heater trap 22 and used for heating a sample. A platinum resistance temperature sensor 24 is arranged on the outer side of the sample cell 21, preferably, the length of the platinum resistance temperature sensor 24 is one fourth of the length of the sample cell, and the platinum resistance temperature sensor is fixed at the center of the outer wall of the sample cell 21 through adhesive bonding. The sample cell 21 is provided with two capillaries 20 communicating with the interior thereof. The two capillaries 20 function as: injecting a sample to be detected into the sample cell by using an injector, connecting high-purity gas to one capillary, discharging liquid in the sample cell from the other capillary by using high-speed gas flow, and cleaning the sample cell through multiple operations. The sample heat insulation environment comprises a plurality of layers of heat insulation screens and a vacuum chamber 15, wherein the heat insulation screens are arranged on the periphery of the sample cell 21, the heat insulation screens are processed by copper plates and are plated with nickel to increase smoothness, and the heat insulation screens are preferably of cylindrical structures. The vacuum chamber 15 is of a cylindrical structure, a flange 11 is arranged at the upper part of the vacuum chamber 15 and comprises an upper flange 112 and a lower flange 111, a polytetrafluoroethylene sealing gasket 14 is arranged between the upper flange 112 and the lower flange 111, two sealing rings 13 with triangular sections are respectively arranged on sealing surfaces of the upper flange 112 and the lower flange 111, the upper flange 112 and the lower flange 111 are connected through spring bolts 12, and the springs are always in a compression state. The vacuum chamber 15 is disposed within the dewar 23. And a layer of low-temperature-resistant heat-conducting insulating paint is coated on the side surface and the upper and lower bottom surfaces of each heat-insulating screen, and a manganese copper wire is wound outside each heat-insulating screen to serve as a heater. The sample cell 21 is suspended in the innermost heat-insulating screen by a hook 25 on the upper part of the sample cell, the inner heat-insulating screen in the two adjacent heat-insulating screens is suspended on a support rod 18 arranged on the upper part of the outer heat-insulating screen by a heat-insulating screen suspension wire 17, and the outermost heat-insulating screen is suspended in the vacuum chamber 15 and is suspended on a lower flange of the vacuum chamber 15. A vacuum chamber connecting pipe 10 is arranged between the vacuum chamber 15 and the heat insulation vacuum chamber 8, one end of the vacuum chamber connecting pipe 10 is fixedly connected with the bottom of the heat insulation vacuum chamber 8, the other end of the vacuum chamber connecting pipe is fixedly connected with an upper flange 112 of the vacuum chamber 15, and the vacuum chamber 15 is communicated with the heat insulation vacuum chamber 8 through the vacuum chamber connecting pipe 10. And a plurality of pairs of anti-series thermocouples are respectively arranged between the sample cell 21 and the inner-layer heat-insulating screen and between the adjacent heat-insulating screens. The heater 26 in the sample cell 21, the thermocouples, the platinum resistance temperature sensors, and the lead wires of the heaters of the heat-insulating shields are led out of the dewar 23 through the vacuum chamber connecting pipe 10 and the line pipe 1.

As shown in the attached figure 7, the utility model discloses during the use, be equipped with temperature controller, programmable constant current source, standard resistance, data acquisition instrument and each heater, thermocouple, sensor are connected. The heater of the heat-insulating screen, the sample pool and the thermocouple of the heat-insulating screen are all connected with the temperature controller, and the temperature difference between the sample pool and the heat-insulating screen is controlled by the temperature controller; the standard resistor is connected in series with a heater in the sample cell and a current channel of the data acquisition instrument, is connected in parallel with a voltage channel of the data acquisition instrument, and is then connected with a voltage output terminal of the programmable constant current source, and the programmable constant current source is connected with the industrial personal computer. And calculating the heating electric work of the sample by measuring the voltage at two ends of the standard resistor, the heating time and the standard value of the resistor. The platinum resistance temperature sensor of the sample cell is connected with a temperature measuring instrument, and the temperature measuring instrument is connected with an industrial personal computer.

In this embodiment, the heater 26 of the sample cell 21 is connected in series with a 0.01-ohm standard resistor, the voltage of the standard resistor is collected by an 34970 a-type data collection instrument of the science and technology, and the current passing through the heater 26 of the sample cell is calculated according to the standard value of the standard resistor. The temperature of the sample cell 21 was collected using a model 34420a seven-bit half nanovolt/micro-ohm meter of the science and technology. A programmable constant current source, model E3641A, from the science and technology adopted, provides electrical power to the heater 26 of the sample cell. A350-type temperature controller (with 3060 thermocouple card) of lake shore company is adopted to collect the temperature difference between the sample pool and the heat insulation screen, the temperature difference between the heat insulation screen and output electric energy to the heat insulation screen. When the temperature of the inner layer is higher than that of the outer layer, the temperature difference is negative. An 34420A type seven-bit half-nanovolt/micro-ohm meter and an E3641A type programmable constant current source are connected with a 610H type industrial control machine of the Hua science and technology through an R232 interface, and a 34970A type data acquisition instrument and a 350 type temperature controller are connected with the 610H type industrial control machine of the Hua science and technology through a GPIB interface. The nEXT400 molecular pump set of Edward company is connected with the vacuum chamber connecting pipe. The liquid nitrogen delivery pipe 3 is connected with an YDZ-200 liquid nitrogen tank of the west Asia company. The VBnet language is adopted to write control and analysis software, and the working process is as followsThe following: and starting software, respectively detecting the communication connection of software registration information, NI-VISA installation information, an 34420A type instrument, a 34970A type instrument, an E3641A type instrument and a 350 type instrument, and the like, entering a test interface after the detection is passed, and giving information after the detection fails. On the test interface, firstly, each basic parameter and control parameter are set, and the database information is updated. The basic parameters mainly comprise sample mass, sample molar mass, a temperature difference acquisition channel, an electric power output channel, a temperature point, PID parameters and the like; the control parameters mainly comprise temperature, temperature difference range, stabilization time, heater resistance value, output voltage, output current, heating time, data acquisition number, data filtering range and the like. Introducing liquid nitrogen into the Dewar flask, cooling to set temperature, opening vacuum valve, starting vacuum pump, and pumping vacuum chamber 15 to vacuum degree lower than 10^-5Bar. The program is operated, the software starts to judge the temperature of the sample pool, the temperature difference between the sample pool and the heat insulation screen and the temperature difference between the heat insulation screens, when the temperature difference between the sample pool and the heat insulation screens and the temperature difference between the heat insulation screens are larger than the set temperature difference, the 350-type temperature controller starts the electric power output, the electric power output is adjusted according to the set PID parameters until the temperature of the sample pool is stabilized in the set time and the set temperature change range, and the temperature difference between the sample pool and the heat insulation screens and the temperature difference between the heat insulation screens are stabilized in the set time and the set temperature change range. Stopping the temperature and temperature difference judging clock, starting the E3641A type programmable constant current source electric power output clock, controlling the temperature difference of the heat insulation screen to track the temperature of the sample pool by the 350 type temperature controller, keeping the temperature difference between the sample pool and the inner heat insulation screen at 0.001 ℃, closing the electric power output clock when the sample pool is heated to the set heating time, and starting the temperature and temperature difference judging clock. The electric power output process collects the initial electric power, the intermediate electric power and the electric power at the end, the average electric power is taken for calculation, and the heating time is calculated by taking the running time of the heating process system. And the temperature data filtering of the sample cell combines the periodic integration time of a power supply and amplitude limiting filtering for an adjusting instrument. Calibrating the resistance values of the sample cell heater resistors at different temperature points to obtain a curve of the resistance and the temperature, and calculating the heat emitted by the heater by adopting the calibrated resistance values. The heating power of the sample is the blank deducted from the heating power of the sample loading at the corresponding temperatureThe method comprises the steps that heating power of a sample pool is measured by measurement software, wherein a blank sample pool without a sample is measured, power required by the blank sample pool at different temperatures is obtained, then the sample is added into the sample pool, the power of the sample pool with the sample is obtained, and the heating power of the blank sample pool is deducted by the software through an interpolation method. Fig. 8 is a time-temperature curve of a blank sample cell to which no sample is added, fig. 9 is a time-temperature curve of a sample cell to which benzene is added, in the process curves of fig. 8 and 9, each collected segment is the temperature of the sample in the heat balance process after the heating process is finished, the sample temperature stabilization time and the temperature range, such as 300 seconds and 0.01 ℃, are set, the current temperature is collected as the balance temperature after the conditions are met, and then the next heating process is performed. Fig. 10 is a graph showing the electric power-temperature curve of a blank sample cell to which no sample is added, fig. 11 is a graph showing the electric power-temperature curve of a sample cell to which benzene is added, and in the process curves of fig. 10 and 11, the heating electric power of the blank sample cell is linearly related to the sample temperature, the heating electric power of the sample cell to which benzene is added is linearly related to the solid phase and the liquid phase of the sample temperature, and the solid-liquid phase temperature changes little. The solid phase data and the solid-liquid phase data are subjected to tangent intersection as an initial temperature, and the solid-liquid phase data and the liquid phase data are subjected to tangent intersection as a termination temperature. And calculating the total heat absorbed by the sample in the melting process according to the initial temperature and the termination temperature, and then dividing the heat corresponding to each temperature by the total heat to obtain the melting parts at different temperatures. And (3) drawing the reciprocal of the melting part and the temperature, extrapolating to obtain the melting point of the pure sample, and calculating the content of impurities in the sample according to a freezing point depression formula.

Other parts in this embodiment are the prior art, and are not described herein again.

Claims

1. a high-purity organic matter purity measuring device based on freezing point descent method, is characterized in that: comprise Dewar flask (23), sample thermal insulation environment providing unit, sample pool (21), and described Dewar flask (23) comprises bottle body and an upper cover (6) detachably connected to the bottle body, the lower part of the upper cover (6) has an insulating vacuum chamber (8) in the shape of a spherical cutout, and the spherical cap surface of the insulating vacuum chamber (8) (9) is located inside the Dewar flask (23), and the upper cover (6) is provided with a line pipe (1), a liquid nitrogen level gauge (2), a liquid nitrogen delivery pipe (3), and an evacuation pipe ( 4), a nitrogen pressure relief pipe (5), a heater trap (22) is provided in the sample cell (21), a heater is provided in the heater trap (22), and the sample cell (21) is provided with a heater. A platinum resistance temperature sensor is provided on the outside, two capillaries (20) communicating with the inside of the sample cell (21) are provided, and the sample thermal insulation environment includes a multi-layer thermal insulation screen arranged on the periphery of the sample cell (21). and the vacuum chamber (15), each layer of thermal insulation screen is wound with manganese copper wire as a heater, the sample cell (21) is suspended in the innermost thermal insulation screen, and the two adjacent layers of the thermal insulation screen are The layer insulation screen is suspended in the outer layer insulation screen, the outermost insulation screen is suspended in the vacuum chamber (15), the vacuum chamber (15) is arranged in the Dewar flask (23), the The upper part of the vacuum chamber (15) is provided with a flange sealing connection, the vacuum chamber (15) is communicated with the insulating vacuum chamber (8) through a vacuum chamber connecting pipe (10), and the sample cell (21) A plurality of pairs of anti-series thermocouples are respectively arranged between the thermal insulation screens of the inner layer and between the adjacent thermal insulation screens. The wires of the device are all led out to the outside of the Dewar flask (23) through the vacuum chamber connecting pipe (10) and the line pipe (1).

2. The device for measuring the purity of high-purity organic matter based on freezing point descent method according to claim 1, characterized in that: flange connection is adopted between the bottle body and the upper cover of the Dewar flask (23).

3. The high-purity organic matter purity measuring device based on freezing point descent method according to claim 1, wherein a polytetrafluoroethylene gasket (14) is arranged between the upper flanges of the vacuum chamber (15), The sealing surfaces of the two flanges are respectively provided with two sealing rings (13) with a triangular section, and the two flanges are connected by spring bolts (12).

4. The high-purity organic matter purity measuring device based on freezing point descent method according to claim 3, characterized in that: one end of the vacuum chamber connecting pipe (10) is fixedly connected to the bottom of the heat insulating vacuum chamber (8), The other end is fixedly connected with the flange on the upper part of the vacuum chamber (15).

5. The device for measuring the purity of high-purity organic matter based on freezing point descent method according to claim 1 or 2 or 3 or 4, wherein the vacuum chamber (15) and the heat insulating screen are both cylindrical structures.

6. The high-purity organic matter purity measuring device based on freezing point descent method according to claim 1 or 2 or 3 or 4, characterized in that: the liquid nitrogen delivery pipe (3) is connected to the Dewar flask (23) bottom of.

7. The high-purity organic matter purity measuring device based on freezing point descent method according to claim 1, wherein the platinum resistance temperature sensor is fixed at the center position of the outer wall of the sample cell (21) by gluing.