Inhibitory study and trickle bed reactor modeling for joint reactions of hydrodesulfurization, hydrodenitrogenation and hydrodearomatization during the hydrotreating of vacuum gas oils
Advancing the chemical engineering fundamentals
Chemical Reaction Engineering (T2-2P)
Keywords: modeling,simulation,trickle,inhibition,hydrotreatment
The purpose of this research is confronting some of the present challenges about hydrotreatment of heavy petroleum fractions: Modeling and simulation; clarification of inhibitory or promoter effects among molecules of aromatic, sulfur, basic nitrogen, non-basic, and water; and application of available analytical techniques.
Based on technical considerations, mainly properly analytical techniques, was selected a vacuum gas oil (VGO) from a crude oil of intermediate character (Naphtenic/Paraffinic, 27API, 0.8% Sulfur) representing the heavy fractions during the hydrotreatment process. Similarly, were selected and purchased six pure compounds: dibenzotiophene (sulfur), decahydro-naphthalene (mono-aromatic), naphthalene (di-aromatic), anthracene (tri-aromatic), carbazole (non-basic nitrogen), and acridine (basic nitrogen). Also, was included like a reactive the use of water, emulsified to the vacuum gas oil in concentration between 5-10% vol., and cuts of aromatic compounds obtained from liquid-liquid extraction of six sub-fractions of selected vacuum gas oil.
All the test were realized at pilot plant (ECOPETROL-ICP), where was used a commercial catalyst in its original size (Ni-Mo/Al2O3, trilobe shape, equivalent size of 1,8 mm, length 4,1mm). The reactor has an inside diameter of 1,9cm and a length of 73,5 cm. The operating temperature, pressure, liquid hourly space velocity (LHSV) and gas/oil ratio were 330-390C, 5-10 MPa, 1-3 h-1, 4.0-6.5 respectively.
The analytical techniques selected for this research were Nuclear Magnetic Resonance-NMR (for aromatic content and other analysis), Gas chromatography coupled with high performance mass spectrometry-GC/MS (for aromatic families distribution-including sulfur families), Ultra violet-visible spectrometry-UV/VIS (for aromatic families), Simulated distillation (SimDis), analysis of Saturates-Aromatic-Resin (SAR), and Standard Tests (ASTM) to determinate basic nitrogen, total nitrogen, total sulfur, and other physic-chemical properties in vacuum gas oils (VGO).
For modeling and simulation of Trickle Bed Reactor (TBR), a set of several reactor models were evaluated, and finally, two three-phase reactor models reported in the literature were combined and used in the present investigation: Korsten and Hoffman-1996 for gas and liquid phase, and Froment et al.-1994, for solid phase. The model includes correlations for the determination of the necessaries physic-chemical parameters, determined at the process conditions using information reported in the literature. Also, a sequential design of experiments was used for model discrimination and parameter estimation during kinetic investigation for HDS, HDN and HDA reactions.
To detect inhibition or promotion effects, the selected reactive were mixed (in comparables concentrations with real feedstock) with the selected and severely hydrotreated vacuum gas oil, under an elaborated 25 factorial design of experiments.
The results include the modeling of Trickle Bed Reactor based on experiments carried out under typical industrial conditions at pilot plant, and the inhibition and promoter effects among different selected compounds.
Presented Tuesday 18, 13:30 to 15:00, in session Chemical Reaction Engineering (T2-2P).
