Abstract

Steady-state  and dynamic simulation play important roles in investigation of refinery units. Therefore, simulation can help this investigation and behavior assessment. In this paper, simulation was done by commercial software. In fact, because of solving many state equations simultaneously and using control theory, dynamic simulation has more significant impact than steady-state simulation. Flow, pressure, temperature and level (FPTL) were controlled by Proportional-Integral-Derivative (PID) controllers in the unit. The case study is Kermanshah Refinery. The behavior of the FPTL controllers in dynamic regime were observed after the changing of the crude oil feed flow rate by 3% for 5 h. ASTM D86 boiling points (compositions) of two simulations were compared with experimental data. Finally, system sensitivity to inputs variables was investigated in the MATLAB®/Simulink^TM by transferring the dynamic results. Transient responses to changes such as feed temperature, feed flow rates, steam flow rates and the duties of the reboilers of columns in Gasoline unit were plotted. Among of all disturbances, the system is more sensitive to changes in the feed temperature, the duties of the reboilers of columns in gasoline unit and simultaneous combination of above changes.

Key words: Steady-state, dynamic, PID controller, ASTM D86, Sensitivity, MATLAB simulink, transition responses.