4-Lump kinetic model for vacuum gas oil hydrocracker involving hydrogen consumption

Abstract

A 4-lump kinetic model including hydrogen consumption for hydrocracking of vacuum gas oil in a pilot scale reactor is proposed. The advantage of this work over the previous ones is consideration of hydrogen consumption, imposed by converting vacuum gas oil to light products, which is implemented in the kinetic model by a quadratic expression as similar as response surface modeling. This approach considers vacuum gas oil (VGO) and unconverted oil as one lump whilst others are distillate, naphtha and gas. The pilot reactor bed is divided into hydrotreating and hydrocracking sections which are loaded with different types of catalysts. The aim of this paper is modeling the hydrocracking section, but the effect of hydrotreating is considered on the boundary condition of the hydrocracking part. The hydrocracking bed is considered as a plug flow reactor and it is modeled by the cellular network approach. Initially, a kinetic network with twelve coefficients and six paths is considered. But following evaluation using measured data and order of magnitude analysis, the three route passes and one activation energy coefficient are omitted; thus the number of coefficients is reduced to five. This approach improves the average absolute deviation of prediction from 7.2% to 5.92%. Furthermore, the model can predict the hydrogen consumption for hydrocracking with average absolute deviation about 8.59% in comparison to those calculated from experimental data.

5-Lumps kinetic modeling, simulation and optimization for hydrotreating of atmospheric crude oil residue

“…Moreover, higher liquid flow rate gives greater liquid holdup, which evidently decreases the contact of liquid and gas reactants at the catalyst active site, by increasing film thickness. Figure 5 also illustrates that the yield of naphtha and kerosene was decreased by increasing the LHSV which was in agreement with the role of the residence time-the smaller the LHSV, the better the hydrotreating [3]. The small difference in conversion between LHSV = 0.3 and LHSV = 1 is attributed to the effect on hydrogen consumption.…”

“…4. At low temperature, the conversion of RCR was very low, then increased gradually with increasing reaction temperature from 653 to 693 K. The yield of naphtha and kerosene was decreased by increasing the LHSV which agreed with the role of the smaller the LHSV, the better the hydrotreating [34]. The role of temperature was routine, for naphtha and kerosene the temperature stimulates the hydrogenolysis reactions, so that the yield of both was improved.…”

“…It is generally used to process heavy oil cuts. The process is tailored to various needs of refineries to maximize middle distillates, gasoline, LPG and similar products [3]. Kinetic model has a significant effect on process optimization, unit design and catalyst selection.…”

“…Increasing the number of lumps, however, will complicate the model by increasing the number of model parameters [16]. Although numerous researchers published about lumping model for some oils and residues [3,[17][18][19][20][21], there is a lack of models for predicting kinetic parameters of atmospheric crude oil residue with a flexibility of operating pressure along with the absence of experimental data. The proposed model will estimate the optimal conditions of the five lumps, naphtha, kerosene, light gasoil, heavy gasoil and lowest residue with low content of impurities.…”

A two-dimensional discrete lumped model for a trickle-bed vacuum gas oil hydrocracking reactor

“…The device, catalyst, feed and operating conditions were described completely in the previous work [25]. The reactor consisted of a cylindrical vessel with an internal diameter of 0.016 m and height of 1.22 m (see Fig.…”