Abstract
In the process of oil refining, hydro cracking is a process through which a heavy hydrocarbon cut is converted into lighter and more valuable products in presence of hydrogen. The current study is concerned with a multi objective optimization of several hydro cracking unit’s reactors of the Shazand refinery. In this regard, a tube reactor in a fixed bed has been modeled and the results validated with industrial data collected from the aforementioned refinery. Then the reactor optimized with the aim of increasing production with respect to the least reduction in the catalytic activity and efficiency in terms of hydrogen and fuel gas consumption. The results indicated that, optimization plus changes in operating conditions led to increased or maintained conversions at accepted industrial levels.
Furthermore, the procedure to reduce the hydrogen consumption complied with led to an estimated annual reduction of 83,373.84 hNm3 hydrogen consumptions plus annual saving of about 87,120 Nm3 in heater’s fuel gas consumption. These were economically valuable and in particular, important interms of environmental issues. Operating parameters varied within ±0.1, ± 0.3, ±0.6, ± 1 and ± 1.2 °C for the reactor inlet temperature for 5, 10 and 20 % by volume of hydrogen injection into the feed and inlet. Optimal variations ranged for the reactor inlet temperature from - 0.7 to + 0.3 °C as well as; for inlet hydrogen injection determined to be + 9 to – 9 % by volume and for the feed inputs were found +4 to 8 % by volume.
