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Hydrocracking is a significant process in a refinery which is commonly used for converting heavy fractions such as vacuum gas oil (VGO) to the valuable products such as naphtha and diesel. In this research, VGO hydrocracking process was studied in a pilot scale plant in the presence of a zeolite and two amorphous based commercial catalysts called RK-NiY, RK-MNi and KF-101, respectively. In order to study the effect of support on the yield of the process, a discrete 4-lump kinetic model, including feed (vacuum gas oil and unconverted materials), distillate (diesel and kerosene), naphtha and gas was proposed for each catalyst. At first, each network had six reaction paths and twelve kinetic coefficients, and then by using the model reduction methodology, only four main routes for RK-MNi and RK-NiY, and three ones for KF-101 were designated. Results showed that the absolute average deviation (AAD%) of reduced models decreased from 5.11 %, 10.1 % and 21.8 % to 4.54 %, 8.9 % and 19.67 % for RK-MNi, KF-101 and RK-NiY, respectively. Moreover, it was confirmed that amorphous and zeolite catalysts could be selected for producing middle distillate and naphtha products, respectively.

A four-lump computational fluid dynamic (CFD) model was proposed for the investigation of vacuum gas oil hydrocracking in a trickle-bed reactor. The experiment was conducted at 360–390 °C and 146 bar in the reactor at three different flow rates. It was found that the modeling predictions of vacuum gas oil cracking agreed well with the experimental measurements. Furthermore, the developed model analyzed the effects of the feed flow rate in the reactors on the concentration distribution and product yield. The maximum yields of the products including distillate (31%), naphtha (14%), and gas (3%) were obtained at the lowest feed flow rate. However, the feed flow rate enhancement from 0.1568 to 0.2059 kg·h –1 led to the increasing feed concentration and reducing the product concentration at the outlet of the reactor. The latter phenomenon was happened due to the decreasing feed residence time with the increasing mass flow rate.

The constant pressure heat capacity and forced convection heat transfer coefficient of water/oxygen mixtures were measured in a horizontal, smooth, electrically-heated tube. For the supercritical pressure (25 MPa) considered, flow rates (0.76–2.04 kg/min), heat fluxes (21–290 kW/m2) and temperatures (330–430°C), the flow in the 6.2 mm ID tube was fully turbulent. The fluid was distilled water and up to 9 wt % oxygen. The water/oxygen mixture and the above experimental conditions are relevant to supercritical water oxidation systems (SCWO). At subcritical temperatures the oxygen/water mixture is almost immiscible and the flow is two-phase. Just below the critical temperature, the fluid becomes single-phase. By measuring bulk and surface temperatures, for a given flow rate, heat flux and oxygen content, both the heat capacity and heat transfer coefficient for the mixture were measured. The water-oxygen system is a highly non-ideal mixture, and small amounts of oxygen significantly reduce the temperature at which maximum heat transfer occurs. Despite the multi-phase nature of the flow at temperatures well below the critical temperature (i.e., <360°C), the presence of small quantity of oxygen has little effect on the heat transfer. At supercritical temperatures where the flow is single-phase and gas-like, the presence of oxygen has little effect on the heat transfer coefficient. However, at near-critical temperatures, the addition of small amounts of oxygen results in a dramatic change in the heat transfer. Firstly, the magnitude and temperature for the peak heat transfer decrease, consistent with changes in heat capacity. Secondly, heat transfer is deteriorated at moderate heat flux, mostly but not exclusively on the top surface of the tube.

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