Ultraviolet Fluorescence Method for Determining Sulfur Content in Liquefied Petroleum Gas

Ultraviolet Fluorescence Method for Determining Sulfur Content in Liquefied Petroleum Gas

Liquefied Petroleum Gas (LPG) is a colorless gas or a yellowish-brown oily volatile liquid with a distinctive odor. It is derived from petroleum or natural gas through pressurization and cooling for liquefaction, and is composed of hydrocarbons, mainly propane and butane, with minor admixtures of ethylene, propylene, ethane, and butylene. LPG is flammable, explosive, highly fluid and slightly toxic. Its liquid density is 580 kg/m³, gaseous density is 2.35 kg/m³, and relative gaseous density is 1.686.

Given its characteristics, LPG is commonly used in non-ferrous metal smelting, metal cutting, agricultural product roasting, industrial furnace firing and other applications.

Purpose of the Experiment

In the field of chemical research, the determination of sulfur content is of great significance for LPG. Sulfides are corrosive in nature; excessive sulfur content will accelerate the corrosion of instruments and equipment, shorten the replacement cycle of such devices, and increase the risk of explosion or fire. Meanwhile, its corrosion products can cause pipeline blockage and affect gas stability. In addition, due to its inherent toxicity, excessive sulfur content is harmful to the health of exposed personnel.

The determination of sulfur content helps production personnel control product quality, ensure the combustibility and stability of the fuel, prevent engine efficiency reduction or equipment failure caused by sulfur exceeding the standard, and reduce the risk of illness among exposed employees.

Experimental Instruments

· SH0689 Ultraviolet Fluorescence Sulfur Analyzer

· Auxiliary equipment and materials, including an analytical balance with a sensitivity of 0.01 mg, 100 ml volumetric flasks, sulfur standard solution, and analytical-grade reagents.

Experimental Procedures

· Inspect the instruments to ensure they are clean, dry and free from contamination, then connect the power supply.

· Calibrate the instruments in accordance with the experimental requirements.

· Select the calibration curve, dilute the sulfur standard solution with the chosen solvent, and prepare the calibration standard solution.

· Extract the test sample. If the sulfur concentration of the sample is not within the sulfur concentration range of the standard solution used for calibration, perform mass dilution or volume dilution on the sample.

· Select the appropriate sample injection method to introduce the sample, determine the response value of the sample solution, inspect the combustion tube and other components in the flow path, and confirm whether the sample is completely combusted.

· Remove components with carbon deposits or soot, and recalibrate the instruments.

· Measure each sample three times and calculate the average response value.

Result Analysis

Through experiment and analysis, the sulfur content of the tested LPG is approximately 157 mg/m³, which complies with the requirements of the GB 11174 standard.