عنوان مقاله [English]
Gasoline hydrotreating is a valuable and economical process for increasing gasoline quality, comparing with other refining processes. Observing harmful effects of some components in gasoline, like benzene, aromatics, olefins and sulfur compounds, which are detrimental to human health and environment and necessity of their removal, hydro treating process of gasoline is a matter of importance in the refining industry. The basis of this process is selective hydro treating of gasoline in sulfur removal reactor after removal of the cuts with boiling point less than 650°C in a fractionation tower to preserve Octane No. of final product. The sulfur removal of lighter cuts to the limit of 50 ppm needs a treating process which will result in octane loss. Therefore for the sulfur removal of this cut, a hydrogenation reactor is used before fractionation tower which its role is mainly hydrogenation of diolefines and olefines. Also it converts mercaptans to thiophenes. With this process, sulfur in lighter cut is transferred to heavier cut. And consequently the sulfur content of lighter cut is reduced to less than 50 ppm. This process is known as C.G.H (cracking gasoline hydrotreating) and its goal is producing gasoline with Euro.4 standard. In this study review and complete simulation of Imam Khomeimy Oil Refining Co. of Shazand has been done with the aid of Aspen Hysys software. Meanwhile in order to increase the quality and quantity of the gasoline of this unit, a new plan for process modification is presented which will improve the gasoline specification of this unit from Euro.4 to Euro.5 standard. However, the accuracy of the new plan is checked based on the calculations in the presented model. Finally design calculations related to new equipment changes of the plan implementation based on new process model and modified condition is done.