bài giảng quá trình chưng cất

1 Nguyễn Văn Toàn 2 Chapter Nguyễn Văn Toàn 3 Nguyễn Văn Toàn 4 Introduction  Hydrotreating processes aim at the removal of impurities such as sulfur and nitrogen from distillate fuels—naphtha, kerosene, and diesel—by treating the feed with hydrogen at elevated temperature and pressure in the presence of a catalyst.  Hydrotreating has been extended in recent years to atmospheric resids to reduce the sulfur and metal content of resids for producing low-sulfur fuel oils.  The operating conditions of treatment are a function of type of feed and the desulfur- ization levels desired in the treated product. Nguyễn Văn Toàn 5 Introduction  The feed types considered here are: Naphtha, Kerosene, Gas oils, Atmospheric resids or reduced crudes.  The principal impurities to be removed are: Sulfur, Nitrogen, Oxygen, Olefins, Metals. Nguyễn Văn Toàn 6 Basic Reactions in Hydrotreating HC - CH CH 3 - HC CH S + 4H 2 C 5 H 12 + H 2 S Methyl thiophene n-pentane  Desulfurization C 5 H 12 + H 2 S Amyl mercaptan n-pentane CH 3 - CH 2 - CH 2 - CH 2 - CH 2 - SH + H 2 CH 3 - CH 2 - CH 2 -S - S - CH 2 - CH 2 - CH 3 + 3H 2 2C 3 H 8 + 2H 2 S Dipropyl disulfide Nguyễn Văn Toàn 7 Basic Reactions in Hydrotreating  Denitrification HC - CH CH 3 - HC CH NH + 4H 2 C 5 H 12 + NH 3 N + 5H 2 + C 3 H 8 + NH 3 Methyl pyrrol Quinoline Nguyễn Văn Toàn 8 Basic Reactions in Hydrotreating  HYDROCARBON SATURATION R - CH = CH 2 + H 2 RCH 2 CH 3 + H 2 + H 2 O R - OH + H 2 OH RH + H 2 O  OXYGEN REMOVAL Nguyễn Văn Toàn 9 Basic Reactions in Hydrotreating  Metals  The metals contained in the naphtha feed are arsenic, lead, and to a lesser degree copper and nickel, which damage the reforming catalyst permanently.  Vacuum gas oils and resid feeds can contain a significant amount of vanadium and nickel.  During the hydrotreating process, the compounds that contain these metals are destroyed and the metals get deposited on the hydrotreating catalyst. Nguyễn Văn Toàn 10 Catalysts  Cobalt (molybdenum on alumina support). This is the general catalyst for HDS service.  Nickel (molybdenum on alumina support). This is used especially for denitrification.  Cobalt (molybdenum and other metals on neutral support). The neutral support prevents the polymerization of the olefins. This catalyst is employed in conjunction with other catalysts for olefinic feeds.