Vol 51, No 1 (2017)

Mathematical modeling of ultrasonic or mechanical separation of oil sand in an aqueous alkaline medium was performed. Kinetic dependences were obtained that adequately describe bitumen recovery based on the limiting role of chemical transformations or mass transfer. It was shown that the second model describes the process kinetics better. A comparison of the theoretical and experimental data allowed us to obtain empirical equations that relate the kinetic coefficients of the model to the characteristics of the heterogeneous mixture being separated and the main process parameters. Recommendations on the technological conditions of separation were given.

The results of our studies of the model of synthesis of barium titanate and nickel–zinc ferrite powders including the mutual influence of the micro and macro scales characteristic for the synthesis of submicron- and nanosized complex oxides were reported. The relationship between the structure of oxides and the synthesis conditions was studied. The characteristics of the gas-dynamic structure in the synthesis reactor, temperature fields, reagent concentrations, and synthesis products were obtained by kinetic calculations of the synthesis of barium titanate and nickel–zinc ferrite in a wide range of similarity parameters.

The possible ionic equilibria in Fe₂(SO₄)₃ water solutions were considered and the most probable of them were determined. Mathematical model of complexation in Fe₂(SO₄)₃ solutions was developed. In this model, the ions that cause a change in the solution pH were taken into account and the generally accepted assumptions on the negligible concentrations of particles, stability constants of which are low, are not included in the model. Based on the model, the calculations of iron distribution by the ionic forms in Fe₂(SO₄)₃ solutions with different concentrations were done with the accuracy of a few hundredths. The reliability of the proposed mathematical description of iron(III) ion equilibria was confirmed experimentally. The process of iron(III) transformation to the required complex form by mathematically predicted change of solution composition was shown. The targeted recharge of complex particles was used as a basis for separating iron(III) and heavy nonferrous metals based on the available ion-exchange resins.

Gas assisted gravity drainage (GAGD) is a novel subdivision of gas injection method. In this method the injection wells are located in the upper bed of the oil zone, and the production wells are drilled at the bottom bed of the oil zone. Reservoir simulation is among the decision tools for investigating production rate and selecting the best scenarios for developing the oil and gas fields. Selecting the location of the injection wells for reaching the optimized pressure and production rate is one of the most significant challenges during the injection process. Recent experiences have shown that artificial intelligence (AI) is a reliable solution for taking the mentioned decision appropriately and in a least possible time. This study is attributed to the investigation of applying the artificial neural network (ANN) as an artificial intelligence method and a potent predictor for choosing the most proper location for injection in a GAGD process in a fractured carbonate reservoir. The results of this investigation clearly show the efficiency of the ANN as a powerful tool for optimizing the location of the injection wells in a GAGD process. The comparison between the results of ANN and black oil simulator indicated that the predictions obtained from the ANN is highly reliable. In fact the production flow rate and pressure can be obtained in every possible location of the injection well.

In this study, a computational model is developed for the estimation of the equilibrium composition of WGSR (water gas shift reaction) based on the stoichiometric and nonstoichiometric thermodynamic approaches. The model employs the Peng–Robinson equation of state (PR-EoS) formulation and the Gibbs free energy minimization. A Matlab computer program is developed for the numerical solution of a highly nonlinear equation of systems satisfying thermodynamic constraints. Molar fractions of each species are determined for different physical conditions using the proposed computational model and the computer code. Comparisons of model predictions with previous results show that molar fractions can be computed accurately using the present computational algorithm. On the basis of the numerical tests, a novel empirical expression is proposed to determine the hydrogen yield for energy considerations.

It has been shown that studies are aimed at improving existing apparatuses and their elements in the agitating zone of liquids. A great deal of attention is devoted to investigating heat exchange upon stirring, the problem of the intensification of which has not been solved completely. For this reason, apparatuses with vertical heat-exchange units are considered to be promising. A model that allows for the assumption of the effect of the features of the design of agitator and heat-exchange units designed as vertical tubes on the heat-exchange efficiency in the stirring apparatus has been suggested. Results of experimental investigations of hydrodynamics and heat exchange in the apparatuses under study have been given and their high heat effectiveness has been demonstrated. The effectiveness of heat transfer has been compared in the blocks with parallel and series-connected tubes at identical flow rates of the heat carrier in the pipes of each block. No difference in the effectiveness of heat transfer is observed in the entire range of the rotation frequency of a stirrer. At higher water consumption, a block with parallel-connected pipes provides a higher amount of heat flow due to the larger driving force of heat transfer. Experimental data are generalized based on the theoretical dependence for calculating the coefficient of heat withdrawal from the agitated medium. The possibility of increasing coefficients of heat withdrawal from the agitated medium is only restricted by the supplied mechanical energy. An example of the calculation of apparatuses has been given.

A significant part of the low-grade waste heat steam and hot water produced in the power-generation turbines of thermal power plants and internal combustion engines forcedly dispersed into the environment, as well as of the thermal energy of water heated in solar boilers could be used to produce hydrogen (and simultaneously oxygen). A facility for the cost-effective implementation of the process has been developed. Conditions have been determined under which the electric power generated when using produced hydrogen is much higher than the expended energy.