Evaluation device and method for protection performance of cyclohexane adsorbent

Abstract

The invention relates to the technical field of chemical defense, in particular to a device and a method for evaluating the protection performance of a cyclohexane adsorbent. The system comprises an air generator, an air mass flow meter, a humidity regulator and a cyclohexane detector which are sequentially connected together through a pipeline, wherein the cyclohexane detector is electrically connected with a computer; the air mass flow meter is further connected with a flow controller, the two ends of the humidity regulator are connected with a cyclohexane steam generating device and a micrometering valve in parallel through pipelines, and the micrometering valve is used for regulating and controlling the air flow of cyclohexane. The evaluation device further comprises a measuring pipe, and when the evaluation device is used, the measuring pipe is connected in series between a pipeline formed by converging the humidity regulator and the cyclohexane steam generating device and the cyclohexane detector through a pipeline; the method is simple, efficient, safe and easy to operate, fills up the blank of the method for evaluating the cyclohexane dynamics by the adsorbent, lays a foundation for evaluating the protection performance of the adsorbent cyclohexane in the future, and also provides a solution for replacing benzene which is a high-harmfulness protection object.

Description

Technical Field

[0001] The invention relates to the field of chemical defense technology, and in particular to a device and method for evaluating the protective performance of a cyclohexane adsorbent. Background Art

[0002] Cyclohexane is a colorless organic liquid with a pungent odor. It is used as a standard substance for chromatographic analysis, a solvent, and in organic synthesis. It has low toxicity and is often used to replace benzene for degreasing and paint stripping. The performance evaluation of cyclohexane adsorbents (activated carbon) for removing cyclohexane from the air includes the benzene adsorption value. In the latest 2022 revised version of GB 2890-2022 "Respiratory Protection Self-priming Filter-type Gas Mask", the protection object benzene in the filter protection time is changed to cyclohexane. Benzene is highly toxic and environmentally dangerous. Cyclohexane has similar physical and chemical properties to benzene and is stable. It is used as a substitute for benzene for adsorbent performance testing in the world. However, there is currently no unified cyclohexane adsorbent protection performance evaluation method in China. Summary of the invention

[0003] The present invention solves the technical problem that there is no unified kinetic evaluation method for cyclohexane adsorbents at present, and provides a device and method for evaluating the protective performance of cyclohexane adsorbents. It provides strong support for the design modification and process improvement of cyclohexane adsorbents, and also lays a technical foundation for replacing more harmful benzene with cyclohexane in the future.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a device for evaluating the protective performance of a cyclohexane adsorbent, comprising an air generator, an air mass flow meter, a humidity regulator, and a cyclohexane detector connected in sequence through pipelines, wherein the cyclohexane detector is electrically connected to a computer; the air mass flow meter is also connected to a flow controller, and both ends of the humidity regulator are connected to a cyclohexane vapor generator and a fine-tuning valve through pipelines, wherein the fine-tuning valve is used to regulate the gas flow rate of cyclohexane; the evaluation device also comprises a measuring tube, and when the evaluation device is in use, the measuring tube is connected in series between the pipeline after the humidity regulator and the cyclohexane vapor generator are combined and the cyclohexane detector through a pipeline.

[0005] A method for evaluating the protective performance of a cyclohexane adsorbent, using the above-mentioned evaluation device, comprises the following steps:

[0006] S1. Turn on the cyclohexane detector and preheat for 30 minutes;

[0007] S2. Use polytetrafluoroethylene tubes and quick connectors to connect the components of the device in sequence;

[0008] S3. Fill the measuring tube and test the air tightness of the measuring tube;

[0009] S4. Turn on the air generator and adjust the air flow to the required value; turn on the fine-tuning valve and adjust the cyclohexane gas flow according to the test value of the cyclohexane detector to keep the cyclohexane concentration within the required range;

[0010] S5. According to the test requirements, set the test temperature and adjust the relative humidity of the airflow. During the test, keep the temperature, humidity and flow rate specified in the test conditions within the required range;

[0011] S6. After adjusting the cyclohexane concentration value, connect the measuring tube installed in step S3 to the pipeline, and start the timer to start the test;

[0012] S7, recording the cyclohexane penetration concentration change value measured by the cyclohexane detector, stopping the test when the cyclohexane concentration value reaches 10ppm, turning off the mass flow meter, and recording the time t at this time, i.e., the protection time of the cyclohexane adsorbent for cyclohexane; and obtaining the dynamic saturated adsorption capacity of the adsorbent for cyclohexane according to the cyclohexane concentration data measured in the test;

[0013] S8. After the test, remove the measuring tube, purge the cyclohexane detector with clean air or nitrogen until the displayed value is zero, turn off the air generator and end the test.

[0014] As a further limitation of the technical solution of the present invention, the airtightness test in step S3 is to observe the pressure change under a pressure of 13.3 kPa. If the pressure drop value within 1 minute does not exceed 0.26 kPa, the airtightness test is passed.

[0015] As a further limitation of the technical solution of the present invention, the air flow requirement of step S4 is 0.5 L / min·cm 2 .

[0016] As a further limitation of the technical solution of the present invention, step S5 sets the test temperature to 20±3° C. and adjusts the relative humidity of the air flow to 50±2%.

[0017] As a further limitation of the technical solution of the present invention, in step S7, according to the cyclohexane concentration data measured by the experiment, the dynamic saturated adsorption capacity of the adsorbent for cyclohexane is obtained according to formula (1):

[0018]

[0019] Where:

[0020] M——dynamic saturated adsorption capacity of cyclohexane by adsorbent, mg;

[0021] t 0 ——The time for the cyclohexane penetration concentration to increase from zero, min;

[0022] t 1——Test duration, which should be the time when the cyclohexane penetration concentration is consistent with the original concentration, min;

[0023] C——Original concentration of cyclohexane, mg / m 3 ;

[0024] C t ——t 1 Cyclohexane penetration concentration corresponding to the time period, mg / m 3 ;

[0025] q v ——Test air flow rate, L / min;

[0026] m——sample mass, g.

[0027] As a further limitation of the technical solution of the present invention, the original concentration of cyclohexane is directly measured by an instrument or calculated by a weight method. The specific steps of calculating by the weight method are as follows:

[0028] Put cyclohexane in the generating bottle. Before the test, weigh the mass m of the generating bottle containing cyclohexane. 1 , accurate to 0.01g. When weighing, the outer wall of the bottle should be carefully wiped clean. After weighing, the instrument can be connected for testing. To ensure the uniform volatilization of cyclohexane vapor, place the generating bottle in a constant temperature water bath at 30℃. The temperature change should be within ±0.5℃. After the test, re-weigh the mass of the generating bottle m 2 The cyclohexane vapor concentration is calculated according to formula (2):

[0029]

[0030] Where:

[0031] C—cyclohexane vapor concentration in the mixed gas flow, in milligrams per liter (mg / L);

[0032] m 1 —Before the test, weigh the mass of the generating bottle and cyclohexane in grams (g);

[0033] m 2 —After the test, weigh the mass of the generating bottle and cyclohexane in grams (g);

[0034] q v —Total air flow rate, in liters per minute (L / min);

[0035] t—The total time from opening to closing of the bottle, in minutes (min).

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The invention is simple, efficient, safe and easy to operate, filling the blank of the kinetic evaluation method of adsorbents for cyclohexane, laying a foundation for the evaluation of the cyclohexane protection performance of adsorbents (activated carbon and other toxic filtering materials) in the future, and also providing a solution for replacing benzene, a highly hazardous protection object. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the structure of the device for evaluating the protective performance of cyclohexane adsorbent.

[0039] The following are marked in the figure:

[0040] 1-air generator, 2-air mass flow meter, 3-flow controller, 4-humidity regulator, 5-cyclohexane vapor generator, 6-measuring tube, 7-cyclohexane detector, 8-computer. DETAILED DESCRIPTION

[0041] The present invention is further described below in conjunction with specific embodiments.

[0042] The invention is a kinetic evaluation device and method for removing cyclohexane adsorbent from the air, which are established according to the protection performance testing principle and relevant standards such as GB 2890-2022 "Respiratory Protection Self-priming Filter Gas Mask", GJB 6239.16-2008 "Military Impregnated Activated Carbon Performance Test Method Part 16 General Method for Determining Protection Time", GJB 1468A-2017 "General Specification for Military Activated Carbon and Impregnated Activated Carbon", WJ 20453-2016 "Impregnated Activated Carbon Protection Time Determination Method", and WJ 20642-2018 "Impregnated Activated Carbon Performance Test Method".

[0043] Example

[0044] like Figure 1 As shown, a device for evaluating the protective performance of a cyclohexane adsorbent comprises an air generator 1, an air mass flow meter 2, a humidity regulator 4, and a cyclohexane detector 7 which are sequentially connected together through pipelines, wherein the cyclohexane detector 7 is electrically connected to a computer 8; the air mass flow meter 2 is also connected to a flow controller 3, and both ends of the humidity regulator 4 are connected to a cyclohexane vapor generator 6 and a fine-tuning valve through pipelines, wherein the fine-tuning valve is used to regulate the gas flow rate of cyclohexane; the evaluation device further comprises a measuring tube 6, and when the evaluation device is in use, the measuring tube 6 is serially connected through a pipeline between the pipeline after the humidity regulator 4 and the cyclohexane vapor generator 5 are combined and the cyclohexane detector 7.

[0045] Since cyclohexane is liquid at room temperature, the present invention uses air flow to carry cyclohexane gas from cyclohexane liquid and then mixes it with a certain amount of air to generate a cyclohexane gas flow with a specific concentration.

[0046] A method for evaluating the protective performance of a cyclohexane adsorbent, using the above-mentioned evaluation device, comprises the following steps:

[0047] S1, turn on the cyclohexane detector 7, preheat for 30 minutes;

[0048] S2. According to Figure 1 Use polytetrafluoroethylene tubes and quick connectors to connect the components of the device in sequence;

[0049] S3. Fill the measuring tube 6 and test its air tightness. Observe the pressure change under 13.3 kPa. If the pressure drop does not exceed 0.26 kPa within 1 minute, it is airtight.

[0050] S4, turn on the air generator 1, adjust the air flow to the required value (the flow rate is based on the air flow rate of 0.5L / (min·cm 2 )); Open the fine-tuning valve and adjust the cyclohexane gas flow rate according to the test value of the cyclohexane detector 7 to keep the cyclohexane concentration within the required range (the concentration requirements refer to the requirements of 5.2.7 in GB 2890-2022);

[0051] S5. According to the test requirements, set the test temperature to (20±3)℃ or other required temperature, and adjust the relative humidity of the airflow to (50±2)%. During the test, keep the temperature, humidity and flow rate specified in the test conditions within the required range;

[0052] S6, after adjusting the cyclohexane concentration value, connect the measuring tube 6 installed in step S3 to the pipeline, and start the timer to start the test;

[0053] S7, recording the cyclohexane penetration concentration change value measured by the cyclohexane detector, stopping the test when the cyclohexane concentration value reaches 10ppm, turning off the mass flow meter, and recording the time t at this time, i.e., the protection time of the cyclohexane adsorbent for cyclohexane; and obtaining the dynamic saturated adsorption capacity of the adsorbent for cyclohexane according to the cyclohexane concentration data measured in the test;

[0054] According to the experimental cyclohexane concentration data, the dynamic saturated adsorption capacity of the adsorbent for cyclohexane is obtained according to formula (1):

[0055]

[0056] Where:

[0057] M——dynamic saturated adsorption capacity of cyclohexane by adsorbent, mg;

[0058] t 0 ——The time for the cyclohexane penetration concentration to increase from zero, min;

[0059] t 1——Test duration, which should be the time when the cyclohexane penetration concentration is consistent with the original concentration, min;

[0060] C——Original concentration of cyclohexane, mg / m 3 ;

[0061] C t ——t 1 Cyclohexane penetration concentration corresponding to the time period, mg / m 3 ;

[0062] q v ——Test air flow rate, L / min;

[0063] m——sample mass, g.

[0064] The original concentration of cyclohexane is directly measured by instrument or calculated by weight method. The specific steps of weight method are as follows:

[0065] Put cyclohexane in the generating bottle. Before the test, weigh the mass m of the generating bottle containing cyclohexane. 1 , accurate to 0.01g. When weighing, the outer wall of the bottle should be carefully wiped clean. After weighing, the instrument can be connected for testing. To ensure the uniform volatilization of cyclohexane vapor, place the generating bottle in a constant temperature water bath at 30℃. The temperature change should be within ±0.5℃. After the test, re-weigh the mass of the generating bottle m 2 The cyclohexane vapor concentration is calculated according to formula (2):

[0066]

[0067] Where:

[0068] C—cyclohexane vapor concentration in the mixed gas flow, in milligrams per liter (mg / L);

[0069] m 1 —Before the test, weigh the mass of the generating bottle and cyclohexane in grams (g);

[0070] m 2 —After the test, weigh the mass of the generating bottle and cyclohexane in grams (g);

[0071] q v —Total air flow rate, in liters per minute (L / min);

[0072] t—The total time from opening to closing of the bottle, in minutes (min).

[0073] S8. After the test is completed, remove the measuring tube 6, purge the cyclohexane detector with clean air or nitrogen until the displayed value is zero, turn off the air generator, and end the test.

[0074] The test results of the cyclohexane adsorbent for cyclohexane measured in this embodiment are:

[0075] Sample No. Test temperature / ℃ Air flow humidity / % Cyclohexane test concentration (mg / L) Protection time / min Dynamic saturated adsorption capacity (mg / g) 1# 17.3 50.0 2510 141 242 2# 17.3 50.1 2546 134 285 3# 17.6 50.3 1011 40 / 4# 17.1 49.9 1023 68 / 5# 17.4 50.0 954 97 /

[0076] The above-mentioned test tube testing method refers to the provisions of "JJG (Military Industry) 51-2014 Test Tube for Activated Carbon and Impregnated Carbon Test". In actual testing, the pressure value can be visually observed to be unchanged within 10 seconds under a pressure of 20kPa;

[0077] The test conditions can be selected according to the actual test requirements;

[0078] The original concentration of cyclohexane can also be determined by weight method, and the penetration concentration can also be detected by chromatography.

[0079] Requirements for reagents and equipment used in the method of the present invention:

[0080] a) Cyclohexane, in accordance with GB / T 14305-2015, with a purity of not less than 99.5%.

[0081] b) Metal measuring tubes shall comply with the requirements of 4.2 and Chapter 5 of JJG (Military Industry) 51-2014.

[0082] c) Vibrator, dental vibrator.

[0083] d) Timer, with a graduation value of 1s.

[0084] e) Air generator, 5L, or selected according to test conditions.

[0085] f) Water bath, temperature adjustment range (10~80)℃.

[0086] g) Portable temperature and humidity measuring instrument.

[0087] h) Cyclohexane analyzer, with a measuring range of (0-5000) ppm and a graduation value not greater than 1 ppm.

[0088] i) Quick connector, Φ6mm, 8mm.

[0089] The key point of the present invention is the precise control of the test conditions and the calculation of the dynamic saturated adsorption of cyclohexane by the adsorbent. Since the test results will be affected by the cyclohexane concentration, airflow temperature and humidity, the target concentration must be stable and uniform during the test, and the airflow temperature and humidity must remain constant. The target flow meter used is required to have high control accuracy and no flow drift; the calculation of the dynamic saturated adsorption of cyclohexane by the adsorbent is obtained by integrating the permeation concentration curve. Compared with the static method, the method of the present invention is fast and simple.

Claims

1. A device for evaluating the protective performance of a cyclohexane adsorbent, characterized in that: The evaluation device comprises an air generator (1), an air mass flow meter (2), a humidity regulator (4), and a cyclohexane detector (7) which are sequentially connected together through a pipeline, wherein the cyclohexane detector (7) is electrically connected to a computer (8); the air mass flow meter (2) is also connected to a flow controller (3); both ends of the humidity regulator (4) are connected to a cyclohexane vapor generator (6) and a fine-tuning valve through a pipeline, wherein the fine-tuning valve is used to adjust the air flow rate of cyclohexane; the evaluation device also comprises a measuring tube (6); when the evaluation device is in use, the measuring tube (6) is serially connected through a pipeline between the pipeline after the humidity regulator (4) and the cyclohexane vapor generator (5) are combined and the cyclohexane detector (7).

2. A method for evaluating the protective performance of a cyclohexane adsorbent, using the evaluation device as claimed in claim 1, characterized in that: The following steps are involved: S1. Turn on the cyclohexane detector (7) and preheat for 30 minutes; S2. Use polytetrafluoroethylene tubes and quick connectors to connect the components of the device in sequence; S3, filling the measuring tube (6) and testing the air tightness of the measuring tube (6); S4, turning on the air generator (1) and adjusting the air flow rate to the required value; turning on the fine-tuning valve and adjusting the cyclohexane gas flow rate according to the test value of the cyclohexane detector (7) to keep the cyclohexane concentration within the required range; S5. According to the test requirements, set the test temperature and adjust the relative humidity of the airflow. During the test, keep the temperature, humidity and flow rate specified in the test conditions within the required range; S6. After adjusting the cyclohexane concentration value, connect the measuring tube (6) installed in step S3 to the pipeline, and start the timer to start the test; S7, recording the cyclohexane penetration concentration change value measured by the cyclohexane detector, stopping the test when the cyclohexane concentration value reaches 10ppm, turning off the mass flow meter, and recording the time t at this time, i.e., the protection time of the cyclohexane adsorbent for cyclohexane; and obtaining the dynamic saturated adsorption capacity of the adsorbent for cyclohexane according to the cyclohexane concentration data measured in the test; S8. After the test is completed, remove the measuring tube (6), purge the cyclohexane detector with clean air or nitrogen until the displayed value is zero, turn off the air generator, and end the test.

3. The method for evaluating the protective performance of a cyclohexane adsorbent according to claim 1, characterized in that: The airtightness test in step S3 is to observe the pressure change under a pressure of 13.3 kPa. If the pressure drop value does not exceed 0.26 kPa within 1 minute, the airtightness test is passed.

4. The method for evaluating the protective performance of a cyclohexane adsorbent according to claim 1, characterized in that: Step S4 requires the air flow rate to be 0.5 L / min·cm 2 .

5. The method for evaluating the protective performance of a cyclohexane adsorbent according to claim 1, characterized in that: Step S5 sets the test temperature to 20±3°C and adjusts the relative humidity of the air flow to 50±2%.

6. The method for evaluating the protective performance of a cyclohexane adsorbent according to claim 1, characterized in that: In step S7, according to the cyclohexane concentration data measured in the experiment, the dynamic saturated adsorption capacity of the adsorbent for cyclohexane is obtained according to formula (1): Where: M——dynamic saturated adsorption capacity of cyclohexane by adsorbent, mg; t0——the time when the cyclohexane penetration concentration starts to increase from zero, min; t1——test duration, which should be the time when the cyclohexane penetration concentration is consistent with the original concentration, min; C——Original concentration of cyclohexane, mg / m 3 ; C t ——Cyclohexane penetration concentration corresponding to time period t1, mg / m 3 ; q v ——Test air flow rate, L / min; m——sample mass, g.

7. The method for evaluating the protective performance of a cyclohexane adsorbent according to claim 6, characterized in that: The original concentration of cyclohexane is directly measured by instrument or calculated by weight method. The specific steps of weight method are as follows: Cyclohexane is placed in a generator bottle. Before the test, the mass m1 of the generator bottle containing cyclohexane is weighed to an accuracy of 0.01g. The outer wall of the bottle should be carefully wiped clean during weighing. After weighing, the instrument can be connected for testing. To ensure that the cyclohexane vapor volatilization is uniform, the generator bottle is placed in a constant temperature water bath at 30°C. The temperature change should be within ±0.5°C. After the test, the mass m2 of the generator bottle is weighed again. The cyclohexane vapor concentration is calculated according to formula (2): Where: C—cyclohexane vapor concentration in the mixed gas flow, in milligrams per liter (mg / L); m1—the mass of the generating bottle and cyclohexane weighed before the test, in grams (g); m2—the mass of the generating bottle and cyclohexane weighed after the test, in grams (g); q v —Total air flow rate, in liters per minute (L / min); t—The total time from opening to closing of the bottle, in minutes (min).

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