A coupling model of fluid catalytic cracking and diesel hydrotreating processes to study the effects of reaction temperature on the composition of diesel

Abstract

The coupling optimization between different plants was the most difficult and key problem in refineries. To accurately describe the effective transfer of material flow information between Fluid Catalytic Cracking (FCC) and Diesel Hydrotreating (DH) processes and realize the coupling simulation for these processing units in refineries, a coupling model of FCC and DH processes using a fractionation tower simulation system was established to calculate the hydrocarbon compositions of diesel based on the Structure Oriented Lumping (SOL) method. The fractionation tower simulation system developed by MATLAB software was used to divide the molecular composition matrix of FCC product into the molecular composition matrices of dry gas, liquefied petroleum gas, gasoline, diesel, and oil slurry. The molecular composition matrix of diesel contained 73, 69, 183, 121 and 743 structural vectors representing paraffins, olefins, naphthenes, aromatics and non-hydrocarbon molecules, respectively. The fractionation ratios of the hydrocarbon group compositions with carbon numbers between 5 and 12 in the molecular composition matrix of gasoline and diesel were calculated. The effective transmission of material flow in the FCC and DH processes was accurately expressed by the transmission of the molecular composition matrix of diesel obtained by the fractionation tower simulation system. The effects of FCC and DH reaction conditions on the hydrocarbon compositions of diesel were calculated at the molecular level by the FCC-DH process coupling model. Through the FCC-DH process coupling model using a fractionation tower simulation system, the transformation laws of hydrocarbon and non-hydrocarbon molecules in different devices could be revealed to provide guidance for reducing the content of polycyclic aromatic hydrocarbons and sulfur in diesel, optimizing operating conditions and controlling product quality indicators.