Simulation and Evaluation of Effective Solutions in Reducing Mercaptan and Sulfur in Liquid Gas Exit in Sulforex Unit

Liquefied petroleum gas (LPG) refers to the hydrocarbon gases propane, butane or their combination. Liquid gas is often used for heating purposes and vehicle fuel. In refineries, the hydrocarbon flow of propane, butane and pentane contains impurities such as methyl mercaptan, ethyl mercaptan and other mercaptans. In this research, the simulation of mercaptanization unit of Abadan refinery has been done. First, the unit was simulated in the ProMax software and after the validation of the simulation, the effect of process variables such as the caustic flow rate, caustic concentration, sour feed flow rate and washing column pressure on the concentration of mercaptan in product has been investigated. The concentration of mercaptans in the output product has been discussed. The results of the simulation show that the total calculation error is less than 10%, which indicates the accuracy of the simulation in steady state. Based on the simulation results, with the increase of caustic flow rate, concentration of caustic solvent and washing column pressure, the amount of produced product (ethyl mercaptan and methyl mercaptan) decreases. Only by increasing the flow rate of sour feed, the amount of produced product will increase.