Method for rapidly detecting sulfur content based on dynamic viscosity

Abstract

The invention relates to a method for rapidly detecting sulfur content based on dynamic viscosity, and belongs to the field of fine chemical engineering. The method for detecting the sulfur content is carried out based on the dynamic viscosity, the sulfur content is rapidly obtained through the dynamic viscosity and is basically consistent with the content of a sulfur sample determined through a sulfur content detection (also called sulfur mass fraction) method in the national standard GB / T 2449, and rapid detection on whether the sulfur content meets the requirement or not is achieved by testing the sulfur viscosity. The whole testing process takes about 40 minutes, and the testing time is reduced by 83% compared with the testing time of 4 hours of a sulfur content testing method in the national standard, so that the rapid detection of the sulfur content is realized. Through online detection of the viscosity device, real-time control of the production process can be realized.

Description

Technical Field

[0001] This invention relates to a method for rapid detection of sulfur content based on dynamic viscosity, belonging to the field of fine chemicals. Background Technology

[0002] Sulfur is an extremely important chemical product and industrial raw material, widely used in chemical, light industry, pharmaceutical, pesticide, rubber, dye, papermaking, and fertilizer industries. my country's annual apparent sulfur demand reaches 17 million tons, more than half of which is imported. Unlike the abundant sulfur deposits abroad, my country has scarce sulfur mines, and its sulfur is mainly derived from crude oil and high-sulfur natural gas. Hydrogen sulfide produced during the refining of crude oil and high-sulfur natural gas is recovered through a modified Claus process to obtain industrial sulfur. Due to differences in sulfur origin and production processes, the types and amounts of impurities vary. Common impurities include water vapor and organic hydrocarbon compounds; sulfur derived from volcanic or pyrite deposits may also contain impurities such as arsenic and selenium. These impurities significantly affect sulfur quality. With the continuous expansion of sulfur applications and sustained growth in demand, the market is placing higher demands on sulfur quality, and high-purity sulfur with low impurity content is gradually becoming the mainstream product in the sulfur market.

[0003] Currently, sulfur content is mainly determined according to the national standard GB / T 2449.1-2014, and the methods for detecting sulfur purity rely on the difference method and the gravimetric method. The difference method calculates the sulfur content by subtracting the sum of the mass fractions of the four impurities after detecting four indicators: ash content, acidity, organic matter, and arsenic. Detecting ash content requires high-temperature ignition, which is time-consuming; detecting acidity requires extracting acidic substances from the sulfur with a water-isopropanol mixture followed by titration, which has a significant impact on experimental operation; the detection of sulfur and organic matter content involves titration and gravimetric methods. The former involves burning the sample with an oxygen stream followed by titration, requiring more than ten reagents including sulfuric acid, chromium trioxide, chromic acid, and barium hydroxide, making the operation complex; the latter involves weighing the sample twice after ignition to obtain the organic matter content, resulting in large experimental errors; detecting arsenic content requires complex equipment such as spectrophotometers and arsenic analyzers, leading to high detection costs. The gravimetric method for determining sulfur purity involves washing and filtering the sulfur with carbon disulfide, drying the remaining material, weighing it, and then calculating the sulfur purity. However, the reagents used are highly toxic, posing significant safety risks, and this method also results in a large margin of error.

[0004] In summary, all existing methods require a significant amount of operator time, involve complex procedures, and demand a high level of operator skill. Therefore, none of them are suitable for online detection and control of sulfur content in production processes.

[0005] Therefore, there is an urgent need for a method that can quickly test, has high sensitivity, and can detect and control sulfur content online to solve the current predicament of sulfur detection. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for rapid detection of sulfur content based on dynamic viscosity.

[0007] The detection method of this invention avoids a lot of cumbersome operations compared with the current national standard for sulfur content testing, reduces detection time by more than 90%, and significantly improves the sensitivity of the detection results. It is particularly suitable for rapid detection and online production monitoring in fields with high requirements for sulfur purity.

[0008] This invention is achieved through the following technical solution: A method for rapid determination of sulfur content based on dynamic viscosity includes the following steps: (1) Provide the sulfur to be tested, add the sulfur to be tested into the sample cup, the sample cup is equipped with a high temperature viscometer with heating function and can test dynamic viscosity, turn on the high temperature viscometer to heat, after the temperature is raised to a temperature greater than the melting point, turn on the stirring rotor of the high temperature viscometer to stir, and continue to heat to 160~400℃. (2) After the sulfur to be tested melts, it is kept at a constant temperature for 20-40 minutes, and the viscosity at that temperature is obtained by a high-temperature viscometer; (3) The sulfur content can be quickly determined based on the tested sulfur viscosity; The detection correspondence is as follows: The sulfur viscosity is less than 40,000 cP, and the sulfur content to be tested is ≤99.95%. The sulfur viscosity is 40,000-45,000 cP, and the sulfur content to be tested is 99.95%–99.97%. The sulfur viscosity is 45,000-60,000 cP, and the sulfur content to be tested is 99.97%-99.98%. The sulfur viscosity is greater than 60,000 cP, and the sulfur content to be tested is ≥99.98%.

[0009] According to a preferred embodiment of the present invention, in step (1), the amount of sulfur to be tested in the sample cup is melted and then used to cover the rotor of the high-temperature viscometer.

[0010] According to a preferred embodiment of the present invention, in step (1), the amount of sulfur to be tested in the sample cup is 25~35g.

[0011] According to a preferred embodiment of the present invention, in step (1), the high-temperature viscometer is a high-temperature Brinell viscometer from Shanghai Fangrui Instrument Co., Ltd.

[0012] According to a preferred embodiment of the present invention, in step (1), the temperature control accuracy of the high-temperature viscometer is 0.1℃.

[0013] According to a preferred embodiment of the present invention, in step (1), the viscometer sample cup is made of stainless steel, aluminum or ceramic.

[0014] According to a preferred embodiment of the present invention, in step (1), the stirring speed is 2~8 rpm. According to a preferred embodiment of the present invention, in step (1), the heating rate is 10℃ / min to 30℃ / min.

[0015] According to a preferred embodiment of the present invention, in step (2), the viscosity at that temperature is obtained after being kept at a constant temperature for 20-50 minutes.

[0016] According to a preferred embodiment of the present invention, in step (2), the sulfur viscosity test temperature is 160℃~400℃. According to a preferred embodiment of the present invention, in step (2), the test temperature is greater than 240°C, and nitrogen is introduced into the sample cup to replace the air, so that the test process is carried out under nitrogen protection.

[0017] According to a preferred embodiment of the present invention, in step (2), the operations of steps (1) and (2) are repeated, and the average value of the two test results is taken to obtain the viscosity of the sulfur standard sample.

[0018] The method for detecting sulfur content in this invention is based on dynamic viscosity. The sulfur content can be obtained quickly through dynamic viscosity, which is basically consistent with the method for determining sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449. By testing the sulfur viscosity, the method can quickly detect whether the sulfur content meets the requirements.

[0019] The principle upon which this invention is based is as follows: When a sulfur sample is heated and melted, it polymerizes into insoluble sulfur. However, the presence of trace impurities or organic matter can inhibit the polymerization of sulfur free radicals. The more impurities present, the more they affect sulfur polymerization, and the viscosity of polymerized sulfur is related to the degree of polymerization. At a given temperature, the lower the content of impurities or organic matter, the higher the degree of polymerization of insoluble sulfur, and the higher the corresponding viscosity value. A rotor immersed in the test melt is driven by a spring of a calibrated high-temperature viscometer. The resistance generated by the continuous rotation of the rotor is transmitted to a torque sensor through a rotating connecting rod. Since torque is proportional to viscosity, the viscosity value is calculated.

[0020] This invention is applicable to the rapid characterization of sulfur content, and is particularly suitable for the rapid characterization and online detection of high-purity sulfur content.

[0021] Technical features and advantages of the present invention: 1. The method for detecting sulfur content in this invention is based on dynamic viscosity. The sulfur content can be obtained quickly through dynamic viscosity, which is basically consistent with the method for determining sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449. By testing the sulfur viscosity, the rapid detection of whether the sulfur content meets the requirements can be achieved.

[0022] 2. The entire testing process of this invention takes approximately 40 minutes, which is 83% shorter than the 4-hour test time required by the national standard for sulfur content testing, thus achieving rapid detection of sulfur content. Real-time control of the production process can be achieved through online viscosity monitoring.

[0023] 3. Traditional testing methods are time-consuming and prone to human error. The method of this invention is simple and easy to use, and even trace amounts of organic matter have a significant impact on viscosity, allowing for a direct assessment of sulfur quality. Detailed Implementation

[0024] To make the objectives and technical solutions of this invention clearer, the invention will now be described in further detail with reference to the embodiments.

[0025] Example 1: A method for rapid determination of sulfur content based on dynamic viscosity includes the following steps: (1) Provide 30g of sulfur to be tested, add the sulfur to be tested into a sample cup, the sample cup is equipped with a high temperature viscometer with heating function and can test dynamic viscosity, turn on the high temperature viscometer to heat, raise the temperature to a temperature greater than the melting point of sulfur, turn on the stirring rotor of the high temperature viscometer to stir, and continue to raise the temperature. (2) Heat to 230℃ and keep at that temperature for 30 minutes. The viscosity of sulfur at 230℃ is 70000 cP. The sulfur content of the raw material is ≥99.98%.

[0026] The sulfur to be tested was tested according to the method for testing sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449, and the sulfur content of the raw material was found to be 99.99%.

[0027] The results of the detection method of the present invention are basically consistent with those of the method for detecting sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449. The method of the present invention is simpler, faster and less time-consuming.

[0028] Example 2: A method for rapid determination of sulfur content based on dynamic viscosity includes the following steps: (1) Provide 28g of sulfur to be tested, add the sulfur to be tested into a sample cup, the sample cup is equipped with a high temperature viscometer with heating function and can test dynamic viscosity, turn on the high temperature viscometer to heat, and after the temperature is raised to a temperature greater than the melting point of sulfur, turn on the stirring rotor of the high temperature viscometer to stir, and continue to heat. (2) Heat to 280℃ and keep at that temperature for 45 minutes. The viscosity of sulfur at 280℃ is 20000 cP. The sulfur content of the raw material is ≤99.95%.

[0029] The sulfur to be tested was tested according to the method for testing sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449, and the sulfur content of the raw material was found to be 99.94%.

[0030] The results of the detection method of the present invention are basically consistent with those of the method for detecting sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449. The method of the present invention is simpler, faster and less time-consuming.

[0031] Example 3: A method for rapid determination of sulfur content based on dynamic viscosity includes the following steps: (1) Provide 32g of sulfur to be tested, add the sulfur to be tested into a sample cup, the sample cup is equipped with a high temperature viscometer with heating function and can test dynamic viscosity, turn on the high temperature viscometer to heat, and after the temperature is raised to a temperature greater than the melting point of sulfur, turn on the stirring rotor of the high temperature viscometer to stir, and continue to heat. (2) Heat to 250°C and keep at that temperature for 25 minutes. The viscosity of sulfur at 250°C is 55000 cP. The sulfur content of the raw material is 99.97% to 99.98%.

[0032] The sulfur to be tested was tested according to the method for testing sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449, and the sulfur content of the raw material was found to be 99.98%.

[0033] The results of the detection method of the present invention are basically consistent with those of the method for detecting sulfur content (also known as sulfur mass fraction) in the national standard GB / T 2449. The method of the present invention is simpler, faster and less time-consuming.

Claims

1. A method for rapid detection of sulfur content based on dynamic viscosity, comprising the following steps: (1) Provide the sulfur to be tested, add the sulfur to be tested into the sample cup, the sample cup is equipped with a high temperature viscometer with heating function and can test dynamic viscosity, turn on the high temperature viscometer to heat, after the temperature is raised to a temperature greater than the melting point, turn on the stirring rotor of the high temperature viscometer to stir, and continue to heat to 160~400℃. (2) After the sulfur to be tested melts, it is kept at a constant temperature for 20-40 minutes, and the viscosity at that temperature is obtained by a high-temperature viscometer; (3) The sulfur content can be quickly determined based on the tested sulfur viscosity; The detection correspondence is as follows: The sulfur viscosity is less than 40,000 cP, and the sulfur content to be tested is ≤99.95%. The sulfur viscosity is 40,000-45,000 cP, and the sulfur content to be tested is 99.95%–99.97%. The sulfur viscosity is 45,000-60,000 cP, and the sulfur content to be tested is 99.97%-99.98%. The sulfur viscosity is greater than 60,000 cP, and the sulfur content to be tested is ≥99.98%.

2. The method according to claim 1, characterized in that, In step (1), the amount of sulfur to be tested in the sample cup is melted and then used to cover the rotor of the high-temperature viscometer.

3. The method according to claim 1, characterized in that, In step (1), the amount of sulfur to be tested in the sample cup is 25~35g.

4. The method according to claim 1, characterized in that, In step (1), the high-temperature viscometer is a high-temperature Brinell viscometer from Shanghai Fangrui Instrument Co., Ltd.

5. The method according to claim 1, characterized in that, In step (1), the temperature control accuracy of the high-temperature viscometer is 0.1℃.

6. The method according to claim 1, characterized in that, In step (1), the viscometer sample cup is made of stainless steel, aluminum or ceramic, the stirring speed is 2~8 rpm, and the heating rate is 10℃ / min~30℃ / min.

7. The method according to claim 1, characterized in that, In step (2), the viscosity at that temperature is obtained after being kept at a constant temperature for 20-50 minutes.

8. The method according to claim 1, characterized in that, In step (2), the sulfur viscosity test temperature is 160℃~400℃.

9. The method according to claim 1, characterized in that, In step (2), the test temperature is greater than 240°C. Nitrogen gas is introduced into the sample cup to replace the air, so that the test process is carried out under nitrogen protection.

10. The method according to claim 1, characterized in that, In step (2), repeat steps (1) and (2) and take the average of the two test results to obtain the viscosity of the sulfur standard sample.