“…The effectiveness factor for spherical catalyst in trickle bed regime and the bed void fraction is 0.7 [44] and 0.35, respectively. The only unknown variable in the above equations is density of feed and product stream inside the reactor which can be calculated as follows: (14) In Eq.…”
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.
“…The effectiveness factor for spherical catalyst in trickle bed regime and the bed void fraction is 0.7 [44] and 0.35, respectively. The only unknown variable in the above equations is density of feed and product stream inside the reactor which can be calculated as follows: (14) In Eq.…”
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.
“…Finally, it should also be noted that despite decreased financial support for reaction engineering in certain geographical locations, significant efforts are still devoted to multiphase reaction engineering as witnessed by continued success of the ISCRE conferences and 122 worldwide contributions to the Festschrift in I&EC Research [129,130]. An interesting indication of recent trends in multiphase reaction engineering in terms of research activity location is provided by the data shown in Figure 3.…”
“…This ensemble of multiport valves provides a means for online sampling of the product gas from each of the six reactors, the feed gas, and the calibration gas. Detailed explanations of the stream flow paths and other key aspects are provided in a related publication devoted to the online GC method, so only a brief overview of the sampling system is given here. 4 Heated valve enclosure that shows the installation details of the various multiport valves used for directing gas flows and collecting gas samples for GC analysis.…”
Section: Methodsmentioning
confidence: 99%
“…The prototype online technique, which used four integrated GC columns connected to multiport gas switching valves in a single GC oven, was fully automated and provided a full quantitative account of all hydrocarbons, organic oxygenates, and inorganic combustion products generated from the MARS-1 catalyst evaluation experiments, including H 2 O. An enhanced version of this method was later demonstrated that employed dual-column ovens with independent temperature programs for improved peak resolution and faster overall analysis time . The method also included the capability of positive identification of all reaction species by online injection to a Hewlett-Packard 6890 GC system with a Hewlett-Packard 5973 mass selective detector.…”
Section: Historical Perspective and Literature Reviewmentioning
An automated reactor system for a detailed performance evaluation of gas-phase heterogeneous
oxidation catalysts that utilizes a parallel array of six fixed microreactors called the Multiple
Automated Reactor System, or MARS, is described. The key MARS components include a gas
manifold that safely generates a light hydrocarbon oxidation feed composition, an array of six
fixed-bed microreactors with dedicated components for control of individual reactor feed gas
flow rates and temperatures, an integrated gas sampling and gas chromatography system for
online analysis of feed and product gas compositions, and a process automation control package
based on process logic controller technology. The addition of one or more liquid feed components,
such as steam or organometallic catalyst surface modification agents, is also possible through
a dedicated liquid feed vaporizer subsystem. The automation package contains all of the elements
needed for logging of process sensors, monitoring of all process alarms, control of all process
variables, interlock sequencing, and communication between the operator and automation
hardware through a human−machine interface. These features allow a user-defined catalyst
testing protocol to be downloaded from the automation so that the system can safely operate
24/7 in an unattended mode. Two versions of the MARS are described that mainly differ in the
fixed-bed microreactor configuration and the length of the heated zones used for transport of
product gases from the catalytic zone to the online gas sampling system. One version employs
a classical U-tube fixed-bed microreactor, whereas the second version uses a straight-through
fixed bed. An overview of key operating characteristics is provided. It is shown in part 2 of this
series of papers that the contribution of metal-wall-catalyzed and homogeneous gas-phase
reactions on the observed hydrocarbon and oxygen conversions can achieve significant yet
different levels in each reactor configuration for 1,3-butadiene oxidation. The need to first assess
the role of undesired reactions and then to either eliminate or minimize their contribution to
the desired solid-catalyzed reaction in parallel microreactors is emphasized.
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