Design and optimization of hydrodesulfurization process for liquefied petroleum gases

Abstract

This study, for the first time, carries out the development and optimization of hydrodesulfurization as a promising alternative, for cleaner production of liquefied petroleum gases. Through this process, all the sulfur impurities are hydrogenated into hydrogen sulfide, which is a manageable compound in gas plants as it can subsequently be converted to elemental sulfur. The investigated feedstock with total throughput of 8 × 104 kg h−1 and total sulfur of 3850 ppmw, is from third refinery of South Pars Gas Complex in Iran. For the process optimization, the costs of energy and hydrogen are minimized for sulfur reduction to less than 1 ppmw. The optimal inlet temperature to the reactor is found to be 280 °C and the stripper column for the final removal of hydrogen sulfide requires 50 theoretical trays. The costs of energy are 1.5% of treated product price and the hydrogen demand is 75 kg h−1. For compensation, there would be new incomes from selling ultra-clean product as well as 3.5% over-production of elemental sulfur. Consequently, the results demonstrate the merits of hydrodesulfurization, not only for attaining a cleaner product with ultra-low sulfur content but also for stopping all the ecological drawbacks, including sulfur dioxide emission and water contaminations, associated with the current processes.