In-situ Combustion Simulation from Laboratory to Field Scale

In-situ combustion simulation from laboratory to field scale has always been challenging, due to difficulties in deciding the reaction model and Arrhenius kinetics parameters, together with erroneous results observed in simulations when using large-sized grid blocks. We present a workflow of successful simulation of heavy oil in-situ combustion process from laboratory to field scale. We choose the ongoing PetroChina Liaohe D block in-situ combustion project as a case of study. First, we conduct kinetic cell (ramped temperature oxidation) experiments, establish a suitable kinetic reaction model, and perform corresponding history match to obtain Arrhenius kinetics parameters. Second, combustion tube experiments are conducted and history matched to further determine other simulation parameters and to determine the fuel amount per unit reservoir volume. Third, we upscale the Arrhenius kinetics to the upscaled reaction model for field-scale simulations. The upscaled reaction model shows consistent results with different grid sizes. Finally, field-scale simulation forecast is conducted for the D block in-situ combustion process using computationally affordable grid sizes. In conclusion, this work demonstrates the practical workflow for predictive simulation of in-situ combustion from laboratory to field scale for a major project in China.

ASSESSMENT OF BIOLOGY ACTIVITY OF THE PEELING SUBSTANCES BY THE PHYSICOCHEMICAL APPROACHES ON THE SPIROSTOMUM AMBIGUUM CELL MODEL

Objective: To evaluate the biological activity of chemical peeling substances based on enzymatic and Arrhenius kinetics using Spirostomum ambiguum as an alternative approach to animal experiments. Methods: The Spirotox method was used to analyze the mechanism of «xenobiotic-cell» interaction, similar to the Michaelis-Menten enzymatic kinetics. The Hill-Langmuir equation was used to determine the degree of cooperativity in the binding of xenobiotics to cellular receptors. Using the Arrhenius kinetics, the observed activation energy obsEa of cell death in the model solutions of glycolic and carbolic acids was determed, which will allow predicting the toxicity parameters of any peeling substances. Results: The relationship Spirostomum ambiguum lifetime tL-lgC concentration of peeling compound solution made it possible to characterize the moment of cellular transition from the intermediate state C•Ln to the dead state DC, characterized by irreversible structural and functional changes in the cell/death. The values were 5.3 mmol•l-1 for glycolic acid solutions and 2.8 mmol•l-1 for carbolic acid solutions. Equilibrium constants Keq of complexation, the rate of infusoria death fm, and the degree of ligand cooperativity n were calculated. The activation energy °bsEa of cell death was determined in Arrhenius coordinates, which were 210±0.39 kJ·mol-1 and 108±0.09 kJ·mol-1 for glycolic and carbolic acids respectively. The correlation between the values ​​of activation energy and DL50 of mammals (rats) was discovered. Conclusion: The obtained kinetic parameters made it possible, without animals and humans testing, to characterize the mechanisms of interaction of peeling substances with the living cell.

Dynamics and control of loop reactors - a review

In loop reactors the system is composed of several reactor units that are organized in a loop and the feeding takes place at one of several ports with switching of the feed port. In its simplest operation a pulse is formed and rotates around it, producing high temperatures which enable combustion of dilute streams. A limiting model with infinite number of units was derived. Rotating pulses, steady in a moving coordinate, emerge in both models when the switching to front propagation velocities ~1. But this behavior exists over a narrow domain. Simulations were conducted with generic first order Arrhenius kinetics. Experimental observations are reviewed. Outside the narrow frozen rotating pattern domain the system may exhibit multi- or quasi-periodic operation separated by domains of inactive reaction. The bifurcation set incorporates many 'finger'-like domains of complex frequency-locked solutions that allow to extend the operation domain with higher feed temperatures. Control is necessary to attain stable simple rotating frozen pattern within the narrow domains of active operation. Various tested control approaches are reviewed. Actual implementation of combustion in LR will involve several reactants of different ignition temperatures. Design and control should be aimed at producing locked fronts and avoid extinction of slower reactions.

The Profound Unravelling of Equilibrium Thermodynamics and Arrhenius First-Order Kinetics in Relation to Metal Hydride Desorption Reactions

<div> <p>Approaching the entanglement problem of kinetics with thermodynamics in reversible metal hydride desorption reactions by means of a hyperbola template such as the Michaelis-Menten curve renders a closed solution for their unravelling possible, revealing profound insight of general significance into both, the structure of the rate-limiting thermodynamic factor and the nature of experiment-specific first-order Arrhenius kinetics. As by-product an alternate method of extreme simplicity for modelling transient behaviour of reversible metal hydride tanks is obtained. This paper concludes a series of works concerned with objectively approaching metal hydride soprtion reaction kinetics.</p></div>

The Profound Unravelling of Equilibrium Thermodynamics and Arrhenius First-Order Kinetics in Relation to Metal Hydride Desorption Reactions

<div> <p>Approaching the entanglement problem of kinetics with thermodynamics in reversible metal hydride desorption reactions by means of a hyperbola template such as the Michaelis-Menten curve renders a closed solution for their unravelling possible, revealing profound insight of general significance into both, the structure of the rate-limiting thermodynamic factor and the nature of experiment-specific first-order Arrhenius kinetics. As by-product an alternate method of extreme simplicity for modelling transient behaviour of reversible metal hydride tanks is obtained. This paper concludes a series of works concerned with objectively approaching metal hydride soprtion reaction kinetics.</p></div>

Kinetics Study of the Hydrodeoxygenation of Xylitol over a ReOx-Pd/CeO2 Catalyst

In this study, we elucidate the reaction kinetics for the simultaneous hydrodeoxygenation of xylitol to 1,2-dideoxypentitol and 1,2,5-pentanetriol over a ReOx-Pd/CeO2 (2.0 weight% Re, 0.30 weight% Pd) catalyst. The reaction was determined to be a zero-order reaction with respect to xylitol. The activation energy was elucidated through an Arrhenius relationship as well as non-Arrhenius kinetics. The Arrhenius relationship was investigated at 150–170 °C and a constant H2 pressure of 10 bar resulting in an activation energy of 48.7 ± 10.5 kJ/mol. The investigation of non-Arrhenius kinetics was conducted at 120–170 °C and a sub-Arrhenius relation was elucidated with activation energy being dependent on temperature, and ranging from 10.2–51.8 kJ/mol in the temperature range investigated. Internal and external mass transfer were investigated through evaluating the Weisz–Prater criterion and the effect of varying stirring rate on the reaction rate, respectively. There were no internal or external mass transfer limitations present in the reaction.