The Simulation And Optimization Of Sulfur Recovery Process

Sulfur recovery of petroleum, petrochemical industry, natural gas and coal industries is the main source of sulfur production in our country. After Crude oil’s hydrotreating, the removed sulfur is in the form of H2S. H2S is also the major impurity in natural gas. Synthetic ammonia plant, coking plant, coal gas plant, etc, which use coal as raw material involve the problem of H2S recycling. The H2S has an adverse effect on the downstream operating unit, equipment corrosion, environmental protection and product quality, so the removal of H2S must be conducted. The method of gas desulfurization is commonly alkanolamine method, which uses alkanolamine solution as the absorbent through chemical absorption to remove H2S in the feed gas. The acid gas with a high concentration of H2S is extracted from solvent regeneration. If directly discharged into the atmosphere, it not only pollutes the environment, but also is a waste of sulfur resource. The Claus process of sulfur recovery from H2S is often used in industry, and the quality of the sulfur producted by Claus process is higher than in other ways. The simulation of alkanolamine desulfurization and sulfur recovery processes has important significance to the development of the process, the design, the control of production, the energy conservation optimization and technical transformation.AMSIM module was used in the process simulation software PRO/Ⅱ to simulate the desulfurization process using MDEA as the absorbent, and the effect of the major operating parameters was examined on separation process. The process parameters were also optimized with the goal of minimum energy consumption under the condition of the guarantee of H2S recovery.There are complex combustion reactions and elemental sulfur forms of transformation in Claus process. And the process simulation using Aspen Plus exits the problems that the composition of flue gas deviates from the actual value and the sulfur recovery rate can’t be calculated. So, Fortran language was used to develop Claus furnace and sulfur condenser unit models. For Claus furnace model, the minimum free energy method was used to calculate the equilibrium composition of the reaction products in the furnace, with the correction of the mole fraction of COS, CS2, CO and H2components. For sulfur condenser, sulfur vapor composition diagram was used to calculate sulfur composition in the process gas at the outlet of the condenser. The developed combustion furnace and sulfur condenser unit models were used as the user models of Aspen Plus, and were compiled and linked to Aspen Plus for use. Aspen Plus user model and Aspen Plus built-in model were used to simulate the unconventional spilt-flow Claus process respectively.The results show that the calculated temperature in user model is closer to the real temperature by the correction of byproduct in the Claus combustion furnace and sulfur recovery yield can also be calculated in the Aspen Plus. This method belongs to the secondary development of software, which makes full use of the advantages of Aspen Plus software such as the widespread application, friendly interface, suppling of substantial physical properties, detecting the material conservation of the establishing model automatically, integration with other section easily, etc. And this method extends the application of Aspen Plus.