Published: November 14, 2011 r2011 American Chemical Society 629 dx.doi.org/10.1021/ef201406r | Energy Fuels 2012, 26, 629–641 ARTICLE pubs.acs.org/EF Whole Crude Oil Hydrotreating from Small-Scale Laboratory Pilot Plant to Large-Scale trickle-Bed Reactor: Analysis of Operational Issues through Modeling Aysar T. Jarullah, † Iqbal M. Mujtaba, †, * and Alastair S. Wood † † School of Engineering, Design and Technology, University of Bradford, Bradford BD7 1DP, U.K. ABSTRACT: Catalytic hydrotreating (HDT) is a mature process technology practiced in the petroleum refining industries and used to treat the oil fractions from a crude oil distillation (CDU) unit for the removal of contaminants such as sulfur, nitrogen, etc. Hydrotreating of the whole crude oil before it goes to a CDU unit is a new technology and is regarded as one of the more difficult tasks that have not been reported widely in the public domain. Our recent study using a laboratory small-scale pilot plant shows significant improvement in middle distillate yields and quality of crude oil in terms of contaminants present. Recently, we also determined best kinetic parameters for several hydrotreating reactions using experimental data from the small-scale trickle-bed reactor (TBR), using parameter estimation techniques. With these parameters, we were able to develop a process model of TBR that was validated using the experimental data from the pilot plant. In this study, we scale up the pilot-scale TBR where the throughput of crude oil changes from 45  10 6 m 3 /h to 66.243 m 3 /h (10 000 bpd), the reactor height increases from 65 cm to 1061 cm, and the diameter changes from 2 cm to 399 cm. While isothermal conditions could be easily maintained in the small-scale TBR (an isothermal steady state model mentioned above was sufficient for the reactor), it is not the case for a large-scale reactor. Hence, a detailed model with energy balance was considered for the analysis of the large-scale reactor, and the temperature control issues are discussed. The ratio of reactor length to reactor diameter (L R /D R ) is chosen in such a way so that radial variation could be neglected and it was obtained using an optimization technique. All the main simultaneously occurring hydrotreating reactions are considered. These reactions are hydrodesulfurization (HDS), hydrodenitrogentaion (HDN), hydrodeasphaltenization (HDAs), and hydro- demetallization (HDM), which includes hydrodevanadization (HDV), hydrodenickelation (HDNi). In addition, the chemical reactions responsible for converting part of the crude oil to middle distillate are also considered. The gPROMS modeling software is used for modeling and simulation of the scaled-up TBR process. 1. INTRODUCTION Hydrotreating of whole crude oil is a new challenge and new technology that has not been reported in the literature. Conventionally, all hydrotreatment operations are conducted on each oil fraction (such as gasoline, kerosene, and light and heavy gas oils) followed by CDU separately and not on the whole crude oil. 1 In the petroleum refining industry, HDT reactions (such as hydrodesulfurization (HDS), hydrodenitrogenation (HDN), hydrodeasphaltenization (HDAs), and hyhdrodemetallization (HDM)) are carried out in three phase (solidliquidgas) trickle-bed reactors (TBRs). 26 Jarullah et al. 1,47 considered, for the first time, hydrotreating of the whole crude oil. Jarullah et al. 4 studied a kinetic parameters estimation and simulation of trickle-bed reactor for HDS of crude oil. Jarullah et al. 5 presented a kinetic model development and simulation of simultaneous HDN and HDM (includes HDV and HDNi) of crude oil in a TBR. HDAs of crude oil with kinetic model development and process simulation was investigated by Jarullah. 6 As a result of full crude oil hydrotreating, signifi- cant improvement in middle distillate yields and fuel quality is observed by Jarullah et al. 1 The kinetic models for converting a portion of crude oil to middle distillate yields have also been reported by Jarullah et al. 7 For all the above-mentioned HDT reactions, detailed pilot- plant experiments were carried out in a small-scale labora- tory TBR at di fferent operating conditions. The pilot-plant trickle-bed reactor was operated isothermally by an independent temperature control of five zone electric furnaces. 1 It is clear from the literature review that there is no study on the whole crude oil hydrotreating using large-scale TBR in the public domain. Therefore, the focus of this paper is to look at the- scale up issues of an industrial TBR, on the basis of our previous works and through the use of mathematical modeling. In this study, we attempted to develop a model for an industrial trickle- bed reactor used for whole crude oil hydrotreating (including chemical reactions for HDS, HDN, HDV, HDNi, HDAs, and crude oil conversion to middle distillate yields). The mass balance and reaction rate equations are taken from earlier works, 47 and in addition, we now add energy balance equations. The optimal operation of an industrial hydrotreating unit is investigated to evaluate the viability of a large-scale process of the crude oil hydrotreating process. The dimensions of the industrial trickle-bed reactor are taken into consideration (in terms of the ratio of optimal length to diameter of the reactor). As a result of the exothermic behavior of industrial trickle-bed reactor, the control of the reaction temperature (which is regarded as an important factor in hydrotreating units, having a big impact on the conversion of process reactions) is the main issue in such Received: September 16, 2011 Revised: November 11, 2011