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 Theoretical Foundations of Chemical EngineeringJournal Prestige (SJR): 0.284 Citation Impact (citeScore): 1Number of Followers: 3      Hybrid journal (It can contain Open Access articles) ISSN (Print) 1608-3431 - ISSN (Online) 0040-5795 Published by Springer-Verlag  [2469 journals]
• Dissolution Kinetics of Nickel(II) Hydroxide in a Mixed
Ammonia–Carbonate Solution

Abstract: The reaction of nickel(II) hydroxide and a mixed ammonia–carbonate solution to form nickel(II) aqua–ammonia complexes is studied in the temperature range of 20–40°C. Experiments show that the dissolution proceeds via the formation of an intermediate in the form of hydrated nickel hydroxide [Ni(H2O)x](OH)2, which has a particle size of less than 5–8 μm. Two reaction mechanisms are considered: consecutive and parallel consecutive. Theoretical modeling of the kinetic data allows the rate constants of individual reaction steps, along with the apparent activation energy, to be determined for different temperatures (20, 30, and 40°С).
PubDate: 2022-06-01

• Application Regularities of Heat Pumps in Extractive Distillation

Abstract: — The work considers the application of heat pumps in the extractive distillation of isobutyl alcohol–isobutyl acetate and allyl alcohol–allyl acetate mixtures in complexes consisting of both two-outlet columns and complexes with partially thermally coupled distillation systems. It is shown that the application of heat pumps in some cases provides a reduction in energy costs by more than 30% in the complexes of two-outlet columns and up to 50% in the complexes with partially thermally coupled distillation systems compared to the conventional scheme. Also, the application of internal heat pumps with disposition of the compressor between sections of the extractive column is considered. Such solution is shown to provide a reduction in energy costs by more than 40%; however, its efficiency strongly depends on the physicochemical properties of the mixture. The economic efficiency of the considered schemes is estimated by the criterion of total annual costs. Conditions governing the application efficiency of heat pumps in extractive distillation are formulated based on the obtained data.
PubDate: 2022-06-01

• Comparison of Hydrogenation and Oxidation Methods for Improving the
Performance of Marine Gasoil

Abstract: Fuel desulfurization methods based on hydrogenation and oxidation processes were compared in order to find an optimum method for desulfurization of marine gasoil (MGO) obtained by a process involving heavy distillates. Marine gasoil subjected to these two desulfurization processes had different physicochemical and performance characteristics due to the formation of different hydrocarbon compositions in these chemical processes. Hydrotreatment of marine gasoil led to a decrease in its lubricating ability, flash point, and fuel susceptibility with respect to a depressor–dispersant additive compared to these characteristics for fuel after oxidation with a hydrogen peroxide–acetic acid system. This is explained by the formation of low-boiling fractions and the removal of polysulfides and high-boiling alkanes from the sample under hydrotreatment conditions. Unlike hydrotreatment, oxidative desulfurization does not lead to isomerization and cracking of aliphatic and polyaromatic hydrocarbons, and organosulfur compounds are removed in oxidized forms (sulfoxides, sulfones, and sulfonate esters), as confirmed by chromato-mass spectroscopy and IR spectrometry. The change in the molecular mass characteristics of fuel components in these desulfurization processes was studied by gel permeation chromatography. Under the conditions of hydrotreatment, destructive hydrogenation of aromatics and cracking of heavy aliphatics occur, while during oxidation, the degradation processes of hydrocarbons occur to a lesser extent. After oxidative desulfurization, the characteristics of marine gasoil are more suitable for operational requirements than those for fuel after hydrotreatment. Due to milder process conditions and simple and accessible apparatuses and raw materials for oxidation compared to hydrotreatment, oxidative desulfurization is preferable as a method for improving the fuel performance.
PubDate: 2022-06-01

• Optimization of Steam Reforming of Methane in a Hydrogen-Filtering
Membrane Module with a Nickel Catalyst and a Palladium-Alloy Foil

Abstract: — A model is proposed for steam reforming of methane in a catalytic reactor, the working section of which includes two cylindrical chambers separated by a palladium foil membrane of the Pd, Pd–23% Ag, Pd–6% Ru, Pd–10% Ru, Pd–6% In–0.5% Ru, and Pd–6% In compositions. The upper chamber is evacuated and the atmospheric pressure is maintained in the lower chamber. Upon uniform feed of raw materials to the lower chamber, the problems are reduced to determination of the CH4, H2O, CO2, CO, and H2 flows from the solution of a system of first-order nonlinear ordinary differential equations. The 100% conversion of methane is achieved only when the ratio of water steam and methane input flows is more than two. Calculations are performed in the temperature range 700 $$< T <$$ 1000 K at the ratio of steam/methane input flows belonging to this range [2, 10]. The optimum values of input flows of raw materials, at which the yield of hydrogen and the conversion of methane reach 100%, are determined. At optimum flows and specified temperature, the maximum hydrogen flow through the membrane is observed at the minimum permissible ratios of steam and methane input flows.
PubDate: 2022-06-01

• A New Class of Exact Solutions of the Oberbeck–Boussinesq Equations
Describing an Incompressible Fluid

Abstract: — A new class of exact solutions of the Oberbeck–Boussinesq equations for incompressible media is constructed taking into account body forces, heat sources (sinks), and Joule dissipation. The expressions for the velocities are quadratic forms with respect to two coordinates, generalizing the class of Lin–Sidorov–Aristov solutions. Temperature, pressure, and the field of body forces are described by forms of the fourth degree. The possibility of using this class for convective flows in the Stokes and Oseen approximation is considered, and the possibilities of a new class for describing rotating liquid masses are demonstrated. A simple example illustrates the complex structure of the velocity field for a creeping convective Couette-type fluid flow in a layer with a permeable boundary moving inhomogeneously.
PubDate: 2022-06-01

• Analytical Review of the Papers Presented at the International Scientific
and Technical Symposium “Improving the Energy and Recourse Efficiency
and Environmental Safety of Processes and Apparatuses in Chemical Industry
and Allied Branches” Dedicated to the 110th Anniversary of A.N.
Planovskii

Abstract: The papers analyzed here were presented in the reposts of leading scientists in the processes and apparatuses of chemical technology and published in the Proceedings of the International Scientific and Technical Symposium “Improving the Energy and Recourse Efficiency and Environmental Safety of Processes and Apparatuses in the Chemical Industry and Allied Branches,” which was dedicated to the 110th anniversary of A.N. Planovskii and held at Kosygin Russian State University. The scientific areas considered included the development of processes and apparatuses in chemical technology as a science and an educational discipline; the main trends in the theory of engineering of energy- and resource-efficient chemical engineering systems under the conditions of the digital economy; the possibilities of improving the efficiency of mass-transfer processes through the use of contemporary methods for the mathematical modeling and kinetic calculation of apparatuses, intensification, and energy and resource saving; the development of systems of computational fluid dynamics as applied to the spatial calculations of processes and apparatuses; innovative methods for the production of fibrous and nano materials; the fundamentals of methods for the intensification of basic processes in different industrial technologies; the scientific foundations for the creation of energy- and resource-efficient chemical engineering and other processes; considerations of environmental safety for technological processes and equipment; and efficient systems for the improvement of technospheric safety.
PubDate: 2022-06-01

• Obtaining Tungsten, Titanium, and Molybdenum Powders during their
Dispersion in Pulsed Discharges in Aqueous Solutions

Abstract: The study continues research into the dispersion of metals in pulsed discharges in nitric and sulfuric acid solutions. It was revealed that metal powders are the main product that forms in the dispersion of tungsten, titanium, molybdenum. It was found that the current pulse frequency fed to the electrodes significantly effects the productivity of the process. Thermodynamic calculations show that the atomic oxygen produced in the process oxidizes dispersed metal particles, and a film containing stable forms of metal oxides forms on their surfaces. Our results confirm the earlier stated assumptions: atomic oxygen is formed as the working solution undergoes thermal decomposition in the spark discharge zone, and it participates in oxidation of dispersed metal particles, forming a protective oxide film on the surface, which protects the metal from interacting with the environment.
PubDate: 2022-06-01

• Volumetric Studies on Aqueous Lithium Pentaborate Solution from 288.15 to
323.15 K

Abstract: Densities for aqueous lithium pentaborate solutions at the molalities of (0.011–0.976) mol kg−1 were measured with an Anton Paar Digital vibrating-tube densimeter at temperature intervals of 5 K from 288.15 to 323.15 K. The coefficient of thermal expansion (α), apparent molar volume ( $${{\varphi }_{V}}$$ ), apparent molar expansibility ( $${{\varphi }_{E}}$$ ) and limiting apparent molar expansibility ( $$\varphi _{{\text{E}}}^{0}$$ ) were obtained based on the experimental density data. On the basis of the Vogel–Tamman–Fulcher equation, the coefficients of the correlation equation for densities of LiB5O8(aq) against temperature and molality were parameterized. The results suggest a strong solute-solvent interaction in the solution, and lithium pentaborate is classified as a “structure breaking” solute. As temperatures rise, the hydrophilic character becomes unapparent.
PubDate: 2022-06-01

• Application of a First Principles Mathematical Model of a Mass-Transfer
Technological Process to Improve the Accuracy of the Estimation of the End
Product Quality

Abstract: This study addresses the problem of improvement of the accuracy of the estimation of the quality of the end product when the used set of training data segments is small. It is extended with a physically grounded model (first principles model) of a mass-transfer technological process involved in the production of methyl tert-butyl ether (MTBE). It is shown that the proposed approach is superior to other methods for the construction of statistical models (soft sensors) to estimate the quality of the end products, since it makes it possible to take into account physically grounded relationships and characteristics of the technological process, which ultimately leads to an increase in the level of adequacy of the developed model. The feasibility of the use of a first principles model of the mass-transfer process in the algorithm for the development of statistical models to estimate the quality index of the end product are determined under conditions of parametric uncertainty in the Murphree efficiency of mass transfer and the parameters of the binary interaction between isobutylene dimers and components from the MTBE production system. The use of the area of the region of the intersection of output variable distributions between the values in the extended training and test samples is proposed as a criterion for the effectiveness of extension of the training sample.
PubDate: 2022-06-01

• Influence of Saturation Temperature on Pressure Drop during Condensation
of R-134a inside a Dimpled Tube: A Numerical Study

Abstract: In this study, the numerical simulations for multiphase fluid flow inside a smooth and dimpled tube were investigated at low mass velocities during the condensation of R-134a to determine the pressure drop. The numerical analysis was conducted at a dryness fraction of 0.5, temperature of saturation of 30–50°C, and mass fluxes range between 50 and 200 kg m−2 s−1. The impact of mass flux on the pressure drops had been studied along the smooth and dimpled tube. The smooth and dimpled tubes were designed with an inside and outside diameter of 8.38 and 9.54 mm, respectively. The specifications of the dimpled tube were o = 1 mm, p = 5.08 mm, z = 4.99 mm, and e = 0.5 mm. The Volume of Fluid (VOF) flow model was utilized in this study and the flow field was assumed to be three-dimensional, transient and turbulent. With an increase in mass flux for both smooth and dimple tubes, total pressure drop and frictional pressure drop increases. The numerically simulated two-phase friction factor was compared with the well-known correlations of the dimple tube. Also, the numerically simulated pressure drop for the dimple tube was more compared with the plain tube and the pressure drop decreases with an increase in temperature of saturation.
PubDate: 2022-06-01

• Application of Mathematical Modeling in Technology for the Recovery of
Rubber from Latex in a Magnetic Field

Abstract: The paper presents a study of the process of the isolation of styrene-butadiene rubber from latex with the method of mathematical planning for a full factorial experiment (23). Regression equations that describe the effect of coagulant consumption, as well as the intensity and duration of magnetic field exposure on the process of obtaining rubber from latex, have been obtained. The physical and mechanical properties of the vulcanizates comply with the regulatory requirements.
PubDate: 2022-06-01

• Analysis of Extraction Separation in a Cascade of Mixing-Settling
Extractors in a Recirculation Liquid-Liquid Chromatography Mode

Abstract: Previously, a method for increasing the efficiency of extraction separation of liquid mixtures has been proposed, in which a solution of a mixture of components is introduced as a series of pulse injections in a cascade of mixing-settling extractors operating in the eluent chromatography mode. The present study is further development of this method as applied to separation in a cascade of mixing-settling extractors operating in a recirculation chromatography mode. A mathematical model was developed, and periodic and continuous processes of extraction separation were analyzed for conditions with a mixture of components loaded into a cascade of mixing-settling extractors in the form of a series of successive pulse injections separated by short time intervals. Experiments were performed on a cascade of mixing-settling extractors, which confirmed that the model is reliable. It was shown on some examples that the serial method of loading the solution into a closed circuit of extractors significantly increases the efficiency of separation.
PubDate: 2022-06-01

• Intensification of the Process of Separation of Oil Emulsions by Exposure

Abstract: — To intensify the process of membrane separation of oil emulsions, the membrane element is subjected to constant exposure to ultrasonic vibrations with a frequency of 35 kHz. In the separation of oil emulsions, a decrease in the productivity of the membranes from 22 to 40 times is found, due to the accumulation of oil particles in the near-membrane layer. As a result of the action of ultrasound on the membranes, an increase in specific productivity of up to 30% for microfiltration membranes and up to 45% for ultrafiltration membranes is observed. The impact of ultrasound prevents the aggregation of oil particles and the formation of a gel layer. After separation of the oil emulsion by polymeric membranes, the concentration of oil products decreases. The retention capacity of microfiltration membranes for oil products ranges from 79 to 88% and the retention capacity of ultrafiltration membranes from 91 to 99%. Under the influence of ultrasound, friction forces arise between the particles of oil and the dispersion medium, which leads to a decrease in the particle size, which increases the likelihood of particles slipping through the pores of the membrane. The decrease in the retention capacity for microfiltration membranes averages 3% and for ultrafiltration membranes by 0.6%.
PubDate: 2022-06-01

• Calculation of the Interphase Heat and Mass Transfer in a Nozzle Spray
Cone Taking into Account the Drag Crisis and the Heat- and Mass-Transfer
Crisis

Abstract: Details of a numerical model and the results of calculation are presented for the interphase heat and mass transfer in the two-phase flow produced by nozzle spraying of a liquid into a gas. The proposed mathematical model is based on the unsteady-state differential equations of flow of a compressible medium, supplemented with the equations of heat and mass transfer from the drops to the gas. Difference analogs of the equations of continuity and motion of the phases are created using the known Lax–Wendroff explicit scheme. The axial and radial profiles of the velocities and temperatures of the drops and the gas in the free nozzle spray cone, and also in the two-phase flow through the cylindrical apparatus, are calculated taking into account the early drag crisis of the drops and the crisis of the heat-and-mass transfer inter the phases, and also the specific features of the turbulent friction in the gas, which were detected in previous experiments. In the calculations, in particular, the dependences of the temperatures of the drops and the gas, averaged over the outlet section of the apparatus, on the gas flow rate through the apparatus are characterized.
PubDate: 2022-06-01

• Description of the Operation of a Biochemical Reactor by a Diffusion Model

Abstract: The operation of an unsteady-state well-stirred flow-through biochemical reactor is studied. Nonlinear boundary-value problems describing the operation of such reactors are considered. Nontrivial solutions under homogeneous boundary conditions are sought. The analysis is based on the equations of the diffusion model. The switch of the operating modes of the reactors in the case of several solutions of the equations of the process is analyzed.
PubDate: 2022-06-01

• Combination of Variational and Empirical Methods to Determine the Porosity
during the Deposition of Spherical Particles

Abstract: A combination of variational and empirical methods to determine the porosity is used to give a theoretical explanation of the power-law dependence of the dimensionless velocity of the constrained motion of particles during sedimentation.
PubDate: 2022-04-01

• Low-Temperature Catalytic Decomposition of N2O

Abstract: A series of oxide catalysts modified with potassium cations, 1–5% K2О/CoFe2O4, with a spinel structure were obtained via mechanochemical synthesis. The obtained samples were studied via X-ray powder diffraction, nitrogen adsorption–desorption, temperature-programmed reduction with hydrogen, and temperature-programmed desorption of oxygen. It was shown that an increase in the potassium content leads to a significant decrease in the crystallinity of the oxide, an increase in the specific surface area, and the formation of weakly bound oxygen species; this favors an increase in the catalytic activity of the samples in the decomposition of nitrous oxide at 150–400°C. The most active catalyst was 5% K2О/CoFe2O4, which had the maximum content of weakly bound oxygen species. It was determined that the presence of oxygen or water in the rection mixture decreases the activity in the low-temperature catalytic decomposition of N2O.
PubDate: 2022-04-01

• Heat and Mass Transfer in a Dense Layer during Dehydration of Colloidal
and Sorption Capillary-Porous Materials under Conditions of Unsteady

Abstract: The results of numerical simulation and experimental study of heat and mass transfer in a stationary blown layer of colloidal capillary-porous materials of plant origin with cyclic radiation convective energy supply were presented. The mathematical model consists of the equations of gas phase mass conservation, filtration, and heat and mass transfer in phases, which allow for the internal resistance to heat and moisture transfer in particles when determining the heat and mass transfer coefficients. It includes the dependence of the specific heat of phase transition on particle moisture, particle shrinkage, and layer height during dehydration and the dependence of the effective coefficients of thermal conductivity of gas and vapor diffusion on the filtration rate. The results of modeling of dehydration of potato particles in a dense layer with cyclic radiation-convective energy supply were presented. It was shown that dehydration can be intensified and its duration can be reduced in comparison with the convective method. The calculated data were compared with the experimental data, confirming the adequacy of the model. The experimental kinetic dependences of desorption of activated carbon and zeolite with convective and radiation-convective energy supply were presented. The results of comparison indicate that the duration of desorption is markedly reduced when additional infrared irradiation is provided; for activated carbon, the process time is halved.
PubDate: 2022-04-01

• Theoretical and Practical Foundations of the Selective Separation of
Phosphate Ions from Phosphate Ores with a High Content of Iron Impurities
with the Recirculation Method

Abstract: Calculations and experimental analysis of phosphate ores contaminated with Fe(III) compounds showed that advanced processing of these ores in a scheme with recycling of Fe(III) compounds is possible. The selective precipitation of $${\text{PO}}_{4}^{{3 - }}$$ ions from a nitric acid extract with Fe(III) ions in the form of a FePO4 precipitate, the subsequent alkaline extraction of $${\text{PO}}_{4}^{{3 - }}$$ ions from FePO4, and the dissolution of the formed Fe(OH)3 precipitate in HNO3 make it possible to obtain soluble phosphates and to recycle Fe(III) ions for the precipitation of $${\text{PO}}_{4}^{{3 - }}$$ from the nitric acid extract. The residual P(V) content in the Fe(OH)3 precipitate under the conditions of the recycling of Fe(III) ions is 0.80 wt %, which corresponds to a degree of $${\text{PO}}_{4}^{{3 - }}$$ extraction from FePO4 of 97.1%. The results of the theoretical calculations agree with the obtained experimental data. The proposed original solutions make it possible to process more phosphate ore contaminated with Fe(III) compounds with smaller amounts of Fe(III) compounds, including those contained in the ore.
PubDate: 2022-04-01

• Mathematical Model of Contact Cooling and Purification of the Dispersed
Phase of Gases in Packed Scrubbers

Abstract: The work contains a numerical solution of the scientific and technical problem of the determination of the efficiency of packed scrubbers during condensation cooling and purification of the dispersed phase of gases in the process of a stationary film liquid flow through regular and chaotic contact devices. A system of differential equations with partial derivatives of the conjugate transfer of heat, the mass of water vapor, and the dispersed phase in the packing layer is written. The heat and mass transfer and the transfer of dispersed particles between the gas and liquid phases are taken into account with volume source terms of the interfacial transfer, averaged over the local volume of the layer. Expressions are given to determine the source parameters. The results of the numerical solution of the system of equations in terms of the temperature and moisture content fields and comparison with known experimental data are presented. The dependence of the efficiency of gas purification from a finely dispersed phase on the gas velocity is shown. Comparative characteristics of packings, as well as scientific and technical solutions for the modernization of scrubbers introduced in the industry, are given.
PubDate: 2022-04-01

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