Determination of Process Simulation and Performance Models for Improved Products Yield in Enhanced Modular Refinery Operation in Nigeria

This chapter focused on the need to curb continual scarcity and importation of petroleum finished products in Nigeria through the rehabilitation of existing refineries, construction of new refineries and improved operations of modular refinery processes. Thus, operations and modification of modular refinery process by considering twenty (20) different types of Nigerian crude oil for crude oil assay analysis and classification using Aspen Hysys. The crude oil assay analysis categorized the twenty Nigerian crude oil types as sweet crude (sulphur content below 0.5wt%), light crude oil (API value above 38) and medium crude oil type (API value between 22 and 28). Also, the Nigerian crude oil types were grouped based on their recovery volume at true boiling point of 3700C as group A (crude oil with recovery volume above 80%), which is suitable for modular refinery operations in Nigeria, while group B (crude oil with recovery volume between 70% and 79%) and group C (crude oil with recovery volume below 70%) are more suitable for enhanced modular refinery process due to high residue (above 20%) from conventional modular refinery. Besides, light and medium sweet oil types were simulated in a modular refinery (topping plant) at different numbers of column tray (25, 29, 35, 40 and 48) and based on products yield and equipment cost, modular refinery with twenty-nine (29) column trays was applied in this study. Therefore, twenty Nigerian crude oil types were simulated in a topping plant and enhanced topping plant of 30,000bpd capacity and twenty-nine (29) column trays respectively using Aspen Hysys to evaluate their products yield and tray compositions. Furthermore, the enhanced moduular refinery with hydrocracker reactor yielded more significant products (liquefied petroleum gas, naphtha, diesel and bottom) from the residue of conventional topping plant with Nigerian Brass 2012 of API 40.62, recovery volume 88.78%, yielded residue of 11.22% and 1.29% for modular and enhanced modular refineries respectively while Okoro 2012 of least API 23.54, recovery volume 57.84%, yielded residue of 42.16% and 4.92% for modular and modified modular refineries respectively. In addition, the principle of conservation of mass was applied in developing the hydrocracker reactor models based on the determined nature of reaction taking place in the hydrocracker reactor, kinetic parameters (pre-exponential factors and activation energies) estimated using single point regression analysis with MatLab software and results compared with kinetic experimental data of similar study with minimum absolute errors or deviations. The developed models were solved using MatLab software and the models predicted feedstock conversion (residue) and products yield along the hydrocracker dimensionless length, thus the hydrocracking process was simulated to evaluate the effects of catalyst effectiveness factor on feedstock conversion and products yield along the reactor dimensionless length.