PTQ Q1 2024 Issue

Simulating VGO, WLO, and WCO co-hydroprocessing: Part 2 Economic analysis performed when co-hydroprocessing VGO, WLO, and WCO shows that WLO studied percentages increase hydrocracking unit net profits

Mohamed S El-Sawy, Fatma H Ashour and Ahmed Refaat Cairo University Tarek M Aboul-Fotouh Al-Azhar University S A Hanafi Egyptian Petroleum Research Institute

P art 1 of this study ( PTQ, Q4 2023) presents simulation and analytical studies made on vacuum gasoil (VGO), waste lubricating oil (WLO), and waste cooking oil (WCO) co-hydroprocessing over commercial hydrocrack- ing catalyst. This study follows our previous work which studied the co-hydroprocessing of VGO, WLO, and WCO experimentally on a lab-scale reactor, utilising the commer- cial hydrocracking catalyst. Most fuel producers prefer to utilise existing units to co-hydroprocess WLO, WCO, and VGO rather than install new separate hydroprocessing units because there is a high degree of similarity between units used to hydroprocess petroleum cuts and units to hydropro- cess waste oils mixture with VGO. In this discussion, market analysis and economic studies were conducted to illustrate the flexibility and prevalence of using these unconventional feed mixtures (blends of VGO with WLO and WCO) as industrial feedstock during the COVID-19 pandemic, which caused transportation limita- tions and market upsets. The analysis focused on the fluctu - ations in crude oil, petroleum fuels, and bio-diesel prices last year. By mixing WLO and WCO with VGO as hydrocracking feed, good opportunities for expense optimisation and net profit maximisation can be found, especially when crude oil prices increase. Resource optimisation Many countries were highly affected by the COVID-19 pan- demic and its consequences on global markets and eco- nomics. Hard times usually lead to a concentrated effort to use all available resources. One of these resources is waste oils and their application to convert to fuels with traditional esterification for WCO, distillation followed by extraction for WLO or hydroprocessing of both. Waste recycling has several benefits, including using waste as an energy source, which will suppress toxic and hazardous emissions into the environment and reduce greenhouse gas (GHG) emissions. In addition, waste recycling is stimulating development in the region as well as aiding social structure, especially in developing countries. Furthermore, the refining industry faces numerous challenges in producing high-quality fuels at reasonable costs. Cold flow properties are often a concern when dealing with products derived from hydroprocessing waste oils or VGOs. 1 , ²

Generally, the hydroprocessing unit consists of a reaction section and a fractionation section to separate the reaction products into desired product streams. Hydroprocessing units’ reactors commonly use a trickle bed reactor (TBR) con- figuration due to its simplicity, reliability, and good operabil - ity. A TBR is a fixed bed reactor with a trickle flow regime of hydrocarbon and hydrogen mixture moving from the top to the bottom of the reactor, passing through catalyst bed(s). Usually, heavy hydrocarbons and middle distillates hydropro- cessing reactors consist of more than one catalyst bed with intermediate hydrogen quenching streams to control reaction temperature, as all hydroprocessing reactions are exothermic. Co-hydroprocessing of VGO, WCO, and WLO is a mixed- phase reaction where liquid moves downwards and forms a laminar stream around the catalyst pellets and hydrogen is distributed through available voids in the catalyst bed. Reactions start by diffusing a dissolved hydrocarbon feed mixture and hydrogen in the catalyst pores, reaching the active sites. On the active sites, cracking and hydrogenation reactions occur. These are enhanced by increasing the reac- tion temperature and hydrogen partial pressure.³ Modelling and simulation are important tools for optimis- ing plant profit and operating conditions. Modelling and sim - ulation of an existing industrial hydroprocessing unit need operating conditions and product yield identification. The simulation model case of the hydroprocessing unit consists mainly of a reaction section and a fractionation section. The most complicated aspect of building the simulation model is the calibration of the kinetic model, which forms the core of the simulation. The reaction kinetics depend on many factors, such as reaction temperature, hydrogen partial pressure, liquid hourly space velocity (LHSV), feed composition, and catalyst configuration. From these data, in addition to product yields and specifications, simulation software can predict calibra - tion factors that will be the core of the simulation model. To overcome the complexity of building hydroprocessing reactions kinetic models, many studies and technical papers recommend using commercial software to execute the mod- elling and simulation of hydroprocessing units.⁴ An extensive literature review has been conducted to study the technologies and equipment used industrially in the hydroprocessing of WCO and WLO individually, and

PTQ Q1 2024