Karl Fischer moisture content measuring device

Abstract

The utility model discloses a Karl Fischer moisture content measuring device, which relates to the technical field of moisture content detection, and comprises a carrier gas device, a sample bottle, a heating device, a gas separation bottle and a Karl Fischer tester, the gas inlet of the sample bottle is connected with the carrier gas equipment through a first pipeline and is used for hermetically heating a sample to be detected to volatilize moisture, the heating device is used for heating the sample to be detected in the sample bottle to volatilize moisture, and the gas separation bottle is communicated with the gas outlet of the sample bottle; the gas separation bottle is communicated with the sample bottle and is used for separating water vapor and other gases generated by a to-be-detected sample in the sample bottle, the Karl Fischer tester is communicated with the gas separation bottle and is used for detecting the water vapor separated from the gas separation bottle, the content of trace moisture is accurately tested, interference of other factors is avoided, the operation is simple, the cost is low, the accuracy is high, and the repeatability is good.

Description

Technical Field

[0001] The utility model relates to the technical field of water content detection, and more specifically to a Karl Fischer water content determination device. Background Art

[0002] Currently, the commonly used methods for determining moisture content include drying, chromatography, spectroscopy, and the Karl Fischer method. The Karl Fischer method is the most accurate of the various chemical methods for determining moisture content in a substance. After years of refinement, its accuracy has been enhanced, and it is widely used in the pharmaceutical, petroleum, chemical, pesticide, dye, and grain industries, becoming a global industry standard analytical method.

[0003] The Karl Fischer method uses I2, SO2, pyridine, and anhydrous CH3OH (water content below 0.05%) to prepare a reagent, using methanol as the medium and Karl Fischer solution as the titrant to measure the sample moisture content. After the reagent reacts with the water in the sample, the water content in the sample is calculated by calculating the reagent consumption.

[0004] The Karl Fischer method can rapidly determine the moisture content of liquids, solids, and gases. Currently, Karl Fischer methods for moisture content testing are primarily divided into direct injection and furnace heating. Liquid samples and alcohol-soluble solid samples are typically tested using the direct injection method, while solid samples that are poorly soluble in alcohol or release moisture only at high temperatures are typically tested using the furnace heating method.

[0005] However, the iodine and sulfur dioxide in the Karl Fischer reagent are highly reactive substances that react easily with other substances, making the Karl Fischer method for measuring moisture content susceptible to side reactions. Currently, there are no suitable devices or methods for measuring moisture content in substances that are poorly soluble in alcohol solutions and volatilize or decompose easily upon heating.

[0006] In summary, how to solve the problem of inaccurate results caused by side reactions with other gases in Karl Fischer method testing is an urgent problem to be solved by those skilled in the art. Utility Model Content

[0007] In view of this, the purpose of the present invention is to provide a Karl Fischer moisture content measuring device, which can improve the accuracy of Karl Fischer method for detecting moisture.

[0008] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0009] A Karl Fischer moisture content measuring device, comprising:

[0010] Carrier gas equipment to provide inert gas;

[0011] A sample bottle, wherein the air inlet of the sample bottle is connected to the gas carrier device via a first pipeline, and is used for sealing and heating the sample to be tested to volatilize water;

[0012] A heating device, used for heating the sample to be tested in the sample bottle to volatilize water;

[0013] The gas separation bottle is connected to the gas outlet of the sample bottle and is used to separate the water vapor and other gases generated by the sample to be tested in the sample bottle;

[0014] The Karl Fischer analyzer is connected to the gas separation bottle and is used to detect the water vapor separated from the gas separation bottle.

[0015] The utility model further provides a first gas outlet and a second gas outlet on the gas separation bottle, the first gas outlet is connected to the Karl Fischer analyzer, and the second gas outlet is provided with a second pipe connected to the outside for discharging other gases except water vapor.

[0016] The present invention further includes:

[0017] Filler, filled in the gas separation bottle, used to absorb water vapor generated by the sample to be tested;

[0018] The heating device can heat the gas separation bottle to volatilize the water vapor absorbed by the filling material.

[0019] Furthermore, the filler of the present invention is spherical anhydrous CaCl2.

[0020] The present invention further includes:

[0021] a first manual valve, installed at the first gas outlet, for controlling the connection between the gas separation bottle and the Karl Fischer analyzer;

[0022] A second manual valve is installed at the second gas outlet and is used to control the connection between the gas separation bottle and the outside;

[0023] When the heating device heats the sample bottle, the first manual valve is in a closed state, and the second manual valve is in an open state;

[0024] When the heating device heats the gas separation bottle, the first manual valve is in an open state and the second manual valve is in a closed state.

[0025] Furthermore, the utility model provides a visual operating screen on the heating device for controlling the heating temperature and heating time of the sample bottle and the gas separation bottle respectively.

[0026] The present invention further includes:

[0027] a third pipe, for connecting the gas outlet of the Karl Fischer analyzer to the outside;

[0028] The drying mechanisms are respectively arranged on the first pipeline, the second pipeline and the third pipeline.

[0029] Furthermore, the present invention adopts color-changing silica gel as a desiccant inside the drying mechanism.

[0030] The Karl Fischer moisture content determination device provided by the utility model has the following steps: when a sample to be tested is placed in a sample bottle, the sample to be tested in the sample bottle is heated by a heating device to volatilize moisture, a carrier gas device is used to provide an inert gas, and the introduced inert gas can drive water vapor and other gases generated by the sample to be tested to be sent into a gas separation bottle, and the water vapor is separated separately in the gas separation bottle, so that only the water vapor can be sent separately into the interior of the Karl Fischer determination instrument, thereby realizing the detection of water vapor and achieving accurate testing of trace moisture content, avoiding the influence of substances that are difficult to dissolve in alcohol solution and will volatilize when heated or are easily decomposed when heated on the test result during the detection process, and at the same time, the utility model has the advantages of simple operation, low cost, high accuracy and good repeatability. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0032] Figure 1 This is a schematic structural diagram of a specific embodiment provided by the present utility model.

[0033] 1 is a carrier gas device, 2 is a first pipeline, 3 is a sample bottle, 4 is a heating device, 5 is a gas separation bottle, 6 is a second pipeline, 7 is a third pipeline, 8 is a drying mechanism, and 9 is a Karl Fischer analyzer. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] The core of the utility model is to provide a Karl Fischer moisture content determination device, which can improve the accuracy of Karl Fischer method for detecting moisture.

[0036] Please refer to Figure 1 A Karl Fischer moisture content determination device includes a carrier gas device 1, a sample bottle 3, a heating device 4, a gas separation bottle 5 and a Karl Fischer analyzer 9. The carrier gas device 1 is used to provide inert gas. The air inlet of the sample bottle 3 is connected to the carrier gas device 1 through a first pipe 2, which is used for sealing and heating the sample to be tested to volatilize moisture. The heating device 4 is used to heat the sample to be tested in the sample bottle 3 to volatilize moisture. The gas separation bottle 5 is connected to the air outlet of the sample bottle 3 and is used to separate water vapor and other gases generated by the sample to be tested in the sample bottle 3. The Karl Fischer analyzer 9 is connected to the gas separation bottle 5 and is used to detect the water vapor separated in the gas separation bottle 5.

[0037] During use, the sample to be tested is placed in the sample bottle 3, and the sample to be tested in the sample bottle 3 is heated by the heating device 4 to volatilize the moisture. The carrier gas device 1 is used to provide inert gas. The inert gas introduced can drive the water vapor and other gases generated by the sample to be tested to be sent into the gas separation bottle 5, and the water vapor and other gases are separated in the gas separation bottle 5. Therefore, only the water vapor can be sent into the Karl Fischer analyzer 9 alone, so as to realize the detection of water vapor and accurately test the trace moisture content, avoiding the influence of substances that are difficult to dissolve in alcohol solution and will volatilize when heated or are easily decomposed when heated on the test results during the detection process. At the same time, the operation is simple, the cost is low, the accuracy is high, and the repeatability is good.

[0038] It should be noted that the embodiment of the present invention does not limit the specific method for separating water vapor in the gas separation bottle 5. In some embodiments, it is sufficient as long as it can achieve effective separation of water vapor, for example, a condensation method or an adsorption method can be used.

[0039] Furthermore, the present invention does not specifically limit the inert gas. The inert gas within the carrier gas device 1 can be nitrogen, argon, or the like. Nitrogen and argon do not react with the sample during heating, nor with substances within the sealed measurement device, thereby ensuring the accuracy of the measurement mechanism.

[0040] Please refer to Figure 1 In order to further improve the gas separation effect, in some embodiments, the gas separation bottle 5 is provided with a first gas outlet and a second gas outlet, the first gas outlet is connected to the Karl Fischer analyzer 9, and the second gas outlet is provided with a second pipe 6 connected to the outside for discharging other gases except water vapor. That is to say, through the first gas outlet and the second gas outlet provided on the gas separation bottle 5, the second gas outlet is provided with a second pipe 6 connected to the outside, and the other separated gases are discharged through the second pipe 6, thereby avoiding the gases entering the Karl Fischer analyzer 9 through the first pipe 2 and affecting the detection results.

[0041] Please continue to refer to Figure 1 In some embodiments, a filler 12 is used to fill the gas separation bottle 5 and absorb the water vapor generated by the sample to be tested. That is, by placing the filler 12 inside the gas separation bottle 5, the water vapor generated by the sample to be tested is absorbed by the filler 12, and the filler 12 can only absorb water vapor and will not absorb other gases. Therefore, other gases will be separated and discharged at this time. The heating device 4 can heat the gas separation bottle 5 to re-volatilize the water vapor absorbed by the filler 12. That is, when the heating device 4 heats the gas separation bottle 5, the water vapor absorbed by the filler 12 will be re-volatilized, and the re-volatilized water vapor will enter the Karl Fischer analyzer 9, thereby realizing the detection of the moisture content of the sample, and the filler 12 can be reused after the water vapor is volatilized, which is beneficial to reducing the cost of detection.

[0042] It should be noted that the embodiment of the present invention does not limit the specific material of the filler 12. It only needs to be able to safely absorb and completely volatilize water vapor.

[0043] Please continue to refer to Figure 1 In some embodiments, the filler 12 uses spherical anhydrous CaCl2. That is, by using spherical anhydrous CaCl2 as the filler 12 for adsorbing water vapor, anhydrous CaCl2 itself has a strong moisture adsorption effect and can completely absorb the water vapor evaporated from the sample. At the same time, spherical particles are used to increase their surface area, which is conducive to further improving the absorption efficiency of water vapor.

[0044] It should be noted that the present invention is not limited to using CaCl2 as the filler 12. In some embodiments, other materials capable of absorbing and re-volatilizing water, such as anhydrous magnesium sulfate, can also be used as the filler 12.

[0045] In addition, the embodiment of the present invention is not limited to the spherical shape of the filler 12. In some embodiments, in order to improve its adsorption effect on water vapor, other shapes such as hollow spheres, honeycombs or irregular shapes can also be used.

[0046] Please continue to refer to Figure 1In some embodiments, a first manual valve 10 is installed at the first gas outlet to control the connection between the gas separation bottle 5 and the Karl Fischer analyzer 9; a second manual valve 11 is installed at the second gas outlet to control the connection between the gas separation bottle 5 and the outside. That is to say, the first manual valve 10 and the second manual valve 11 can respectively control the gas outlet of the first gas outlet and the second gas outlet on the gas separation bottle 5. When the heating device 4 heats the sample bottle 3, the first manual valve 10 is in a closed state and the second manual valve 11 is in an open state. When the heating device 4 heats the gas separation bottle 5, the first manual valve 10 is in an open state and the second manual valve 11 is in a closed state. That is to say, when the heating device 4 heats the sample bottle 3, since the first manual valve 10 is in the closed state and the second manual valve 11 is in the open state, the other gases generated will be discharged through the second pipe 6. After the water in the sample is completely evaporated, the heating device 4 heats the gas separation bottle 5. Since the first manual valve 10 is in the open state and the second manual valve 11 is in the closed state at this time, the external gas will not enter the gas separation bottle 5 through the second gas outlet. Only water vapor will enter the Karl Fischer analyzer 9 through the first gas outlet, which is beneficial to further avoid the influence of other gases on the test results and improve the accuracy of the moisture test results.

[0047] It should be noted that the description of the first manual valve 10 and the second manual valve 11 in the embodiment of the present invention is not specifically limited. In some embodiments, they can be replaced by other valves, such as solenoid valves, electric valves or hydraulic valves.

[0048] Please refer to Figure 1 In order to further improve the accuracy of the test results, a third pipe 7 is provided for connecting the gas outlet of the Karl Fischer analyzer 9 with the outside, and a drying mechanism 8 is provided on the first pipe 2, the second pipe 6 and the third pipe 7 respectively. That is to say, the third pipe 7 is provided for connecting the Karl Fischer analyzer 9 with the outside so as to discharge the gas generated during the detection process, which is beneficial to the influence of the gas on the detection results. At the same time, a drying structure is provided on the first pipe 2, the second pipe 6 and the third pipe 7. The drying structure on the first pipe 2 is used to dry the carrier gas, and the drying structure on the second pipe 6 and the third pipe 7 is used to prevent moisture and carbon dioxide in the air from entering the device, so as to reduce the interference of external gas on the detection results.

[0049] It should be noted that the embodiments of the present invention do not limit the specific method and structure of the drying structure, as long as it can complete the drying and reduce external gas interference.

[0050] Please continue to refer to Figure 1In some embodiments, color-changing silica gel is used as a desiccant inside the drying mechanism 8, that is, color-changing silica gel is used as a drying structure to dry the passing gas.

[0051] In addition, a one-way valve may be installed on the second pipe 6 to reduce the risk of external gas entering the gas separation bottle 5 .

[0052] That is to say, the focus of the embodiment of the present invention is: the sample to be tested is placed in the sample bottle 3, the sample to be tested in the sample bottle 3 is heated by the heating device 4 to volatilize the water, the carrier gas equipment 1 is used to provide inert gas, and the inert gas introduced can drive the water vapor and other gases generated by the sample to be tested to be sent into the gas separation bottle 5, and the water vapor is separated separately in the gas separation bottle 5, so that only the water vapor can be sent into the Karl Fischer analyzer 9 alone, thereby realizing the detection of water vapor and realizing accurate testing of trace moisture content, avoiding the influence of substances that are difficult to dissolve in alcohol solution and will volatilize when heated or are easily decomposed when heated on the test results during the detection process, and at the same time, the operation is simple, the cost is low, the accuracy is high, and the repeatability is good.

[0053] The following are the specific experimental methods and approaches of this device:

[0054] Experiment 1

[0055] 1. In a dry room with a dew point temperature ≤ -50°C, weigh a certain mass of the powder to be tested into sample bottle 3 and record the mass m;

[0056] 2. Close the cap of sample bottle 3 tightly and press Figure 1 Assemble the device and make sure it is well sealed;

[0057] 3. Close the first manual valve 10 and open the second manual valve 11;

[0058] 4. Open the gas source of the carrier gas device 1;

[0059] 5. Turn on the heating component to heat the sample bottle 3, set the heating temperature T1, heating time t1;

[0060] 6. The gases generated by heating include water vapor and impurity gases generated by sample decomposition;

[0061] 6. The carrier gas carries the gas generated after heating in the sample bottle 3 into the gas separation bottle 5. After the filler 12 in the gas separation bottle 5 absorbs water vapor, the carrier gas and impurity gas are discharged to the outside through the second gas outlet;

[0062] CaCl2 reacts with water vapor to form CaCl2·2H2O. The reaction formula is as follows:

[0063] CaCl2+2H2O=CaCl2·2H2O

[0064] 7. After the sample cools to room temperature, open the first manual valve 10 and close the second manual valve 11;

[0065] 8. Turn on the heating mechanism to heat the gas separation bottle 5 and set the heating temperature to T2. The CaCl2·2H2O in the gas separation bottle 5 undergoes a decomposition reaction to generate water vapor and anhydrous CaCl2. The reaction formula is as follows:

[0066] CaCl2·2H2O=CaCl2+2H2O↑

[0067] 8. The carrier gas carries the water vapor generated in the gas separation bottle 5 into the Karl Fischer moisture analyzer;

[0068] 9. Use a Karl Fischer titrator to test the moisture content. Enter the sample mass m, set the offset value to <10 to start the test, stir at a speed of 5-6, and use Safeline C19 as the Karl Fischer reagent.

[0069] 10. The test results are as follows:

[0070] Sample composition Mass / g Heating temperature T1 / ℃ Heating time t1 / min Heating temperature T2 / ℃ Moisture content / ppm LATP 0.2011 150 5 260 42.3 LATP 0.2006 180 5 260 51.3 LATP 0.2013 230 5 260 52.5

[0071] Conclusion: From the results of implementation 1, it can be seen that the moisture content in LATP powder remains unchanged as the heating temperature increases.

[0072] Comparative Experiment 1

[0073] 1. In a dry room with a dew point temperature ≤ -50°C, weigh a certain mass of the powder to be tested into sample bottle 3 and record the mass m;

[0074] 2. Use a combination of a cassette furnace and a Karl Fischer moisture analyzer to test the sample;

[0075] 3. Place the sample bottle 3 on the cassette furnace and set the heating temperature T1 and heating time t1;

[0076] 4. Enter the mass of the sample to be tested m on the Karl Fischer titrator, set the offset value to <10 to start the test, the stirring speed to 5-6, and the Karl Fischer reagent to be Safeline C19;

[0077] 5. The test results are as follows:

[0078] Sample composition Mass / g Heating temperature T1 / ℃ Heating time t1 / min Moisture content / ppm LATP 0.2008 150 5 197.0 LATP 0.2014 180 5 215.7 LATP 0.2003 230 5 378.2

[0079] Conclusion: From the comparative example results, it can be seen that the moisture content in LATP powder increases with the increase of heating temperature.

[0080] Experimental results: Compared with Experiment 1, the moisture content is significantly higher. This is because there are impurities in the LATP powder that are easily decomposed by heating. The components produced after the decomposition of the impurities directly enter the Karl Fischer moisture meter and react with the Karl Fischer reagent to release water or consume iodine, resulting in erroneous results.

[0081] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0082] The above describes in detail the Karl Fischer moisture content determination device provided by the present invention. This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are intended only to facilitate understanding of the method and core concepts of the present invention. It should be noted that those skilled in the art may, without departing from the principles of the present invention, make various improvements and modifications to the present invention, and such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A Karl Fischer water content measuring device, characterized in that: include: A carrier gas device (1) for providing an inert gas; A sample bottle (3), the air inlet of the sample bottle (3) is connected to the gas carrier device (1) via a first pipe (2), and is used for sealing and containing the test sample; A heating device (4) is used to heat the sample bottle (3) so as to heat the sample to be tested therein to volatilize water; A gas separation bottle (5) is connected to the gas outlet of the sample bottle (3) and is used to separate the water vapor generated by the sample to be tested in the sample bottle (3); A Karl Fischer analyzer (9) is connected to the gas separation bottle (5) and is used to detect the water vapor separated from the gas separation bottle (5).

2. A Karl Fischer water content measuring device according to claim 1, characterized in that: The gas separation bottle (5) is provided with a first gas outlet and a second gas outlet, the first gas outlet is connected to the Karl Fischer analyzer (9), and the second gas outlet is provided with a second pipe (6) connected to the outside for discharging gases other than water vapor.

3. A Karl Fischer water content measuring device according to claim 2, characterized in that: Also includes: A filler (12) is filled in the gas separation bottle (5) and is used to completely absorb the water vapor generated by the sample to be tested; The heating device (4) can heat the gas separation bottle (5) to completely volatilize the water vapor absorbed by the filler (12).

4. A Karl Fischer water content measuring device according to claim 3, characterized in that: The filler (12) is spherical anhydrous CaCl2.

5. A Karl Fischer water content measuring device according to claim 2, characterized in that: Also includes: a first manual valve (10), installed at the first gas outlet, for controlling the communication between the gas separation bottle (5) and the Karl Fischer analyzer (9); a second manual valve (11), installed at the second gas outlet, for controlling the communication between the gas separation bottle (5) and the outside; When the heating device (4) heats the sample bottle (3), the first manual valve (10) is in a closed state, and the second manual valve (11) is in an open state; When the heating device (4) heats the gas separation bottle (5), the first manual valve (10) is in an open state, and the second manual valve (11) is in a closed state.

6. A Karl Fischer water content measuring device according to claim 3, characterized in that: The heating device (4) is provided with a visual operating screen for controlling the heating temperature and heating time of the sample bottle (3) and the gas separation bottle (5) respectively.

7. A Karl Fischer moisture content measuring device according to any one of claims 2 to 6, characterized in that: Also includes: a third pipe (7) for connecting the gas outlet of the Karl Fischer analyzer (9) to the outside; The drying mechanism (8) is respectively arranged on the first pipe (2), the second pipe (6) and the third pipe (7).

8. A Karl Fischer water content measuring device according to claim 7, characterized in that: The drying mechanism (8) uses color-changing silica gel as a desiccant.

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