A reaction scheme was developed to comply with the experimental data provided by the laboratory setup and industrial plants for the Claus reaction furnace. The proposed reaction scheme was applied in analyzing an industrial Claus reaction from environmental and economic points of view. By applying the modified Claus process, the total emissions from the processed acid gas was reduced about 52.34% compared to acid gas without treatment. The case studies showed that hydrogen sulfide and oxygen mole percentages in the furnace inlet have considerable impacts on the relative, normalized and total environmental impacts of the system. In addition, sulfur efficiency was also influenced by their variations. The 80.41% and 58.98% declines in total environmental impacts and the 71% and 48.41% enhancements for sulfur efficiency were acquired by hydrogen sulfide and oxygen variations, respectively. Therefore, any variation which led to raising hydrogen sulfide conversion to sulfur results in sulfur efficiency improvement and, consequently, has several economic benefits. The optimal operating conditions of an industrial Claus reaction furnace were also investigated. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.