Process simulation, optimization, and cost analysis of a proposed sulfur recovery unit by applying modified Claus technology

Abstract

Removing sour gas from any suitable gas sweetening technology in a cost-effective and environmentally responsible manner is a major challenge. This paper discusses how to safely and economically dispose of small amounts of acid gases resulting from the amine sweetening process. A two-stage Claus desulfurization unit was studied and simulated to treat acid gases resulting from natural gas sweetening operations in Ras Gharib oil fields (Egypt). These acid gases are used as feedstock for the proposed plant to produce a valuable product, such as elemental sulfur, which is used as a raw material in many industries. Although many sulfur recovery techniques are available for various conditions and applications, the Claus process is a critical and widely used method for recovering elemental sulfur from gaseous hydrogen sulfide. This work represents the potential benefits of treating acid gases with high hydrogen sulfide content. In addition, operational variables that could affect sulfur production and sulfur recovery efficiency of the studied Claus unit were studied and optimized. Aspen HYSYS simulation software (version 9) was used to evaluate the economic aspects and optimize the operational parameters of the unit for producing sulfur from acid background gases. The results showed that the maximum sulfur production was achieved at a catalytic converter reactor temperature of 270 °C and 210 °C for the first and second catalytic reactor, respectively, with an air flow rate of 933.3 kg mol/h. The economic study of the proposed desulfurization unit showed that the Claus unit would be economically acceptable with an expected return on investment of approximately 10% and an average payback period of 10 years. Moreover, the introduced plant has a positive impact on the environment by reducing the concentration of hydrogen sulfide in the gas from 69.58 to 0.16%.