Open Access Open Access  Restricted Access Access granted  Restricted Access Subscription Access

Vol 57, No 1 (2023)

Cover Page

Full Issue

Open Access Open Access
Restricted Access Access granted
Restricted Access Subscription Access

Articles

Mathematical Modeling of Processes of Separation by Liquid–Liquid Chromatography Methods

Kostanyan A.E., Voshkin A.A.

Abstract

The practical implementation of new highly efficient methods of liquid–liquid chromatography requires preliminary mathematical modeling for the conditions of the separation process being developed, including its equipment design. In this work, two approaches to the mathematical description of the processes of liquid–liquid chromatography are theoretically analyzed, one of which is based on solving the material-balance equations of a model of a cascade of equilibrium steps, and the other of which uses the Gaussian distribution to describe the outlet concentration profiles of the components of the mixture being separated. It is shown that, if the number of equilibrium steps (characterizing the efficiency of the chromatographic system) is N ≥ 50, then the separation processes can be mathematically modeled using the simpler dependences obtained from the Gaussian distribution. For the conditions when the efficiency of the chromatographic system is N < 50, dependences are obtained using the model of equilibrium steps for mathematical modeling of the processes of separation by various methods of liquid–liquid chromatography.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):3-15
pages 3-15 views

Algorithm for Processing Data on the Thermophysical Properties of Phosphorites by Solving the Inverse-Coefficient Heat-Conduction Problem

Meshalkin V.P., Bobkov V.I., Dli M.I., Orekhov V.A., Chistyakova T.B.

Abstract

An algorithm is proposed to process experimental data to determine the thermophysical properties (specific heat capacity and thermal conductivity) of phosphorites by solving the inverse-coefficient heat-conduction problem, which reduces to programmable heating complicated by thermally activated endothermic reactions of dissociation of carbonates and control of the internal thermal state of a system with distributed parameters. Consideration is made of the problem of mathematical and computer modeling of a system for processing experimental data and generalizing the main dependences of the thermophysical properties in the operating temperature range of thermal-engineering equipment for the heat treatment of ore raw materials and the actual chemical-composition range of phosphorites. This problem is solved by solving the inverse-coefficient heat-conduction problem. The control parameters are thermal conductivity and specific heat capacity, which are the coefficients in the heat equation for a plate. The optimality criterion is the smallest deviation of the temperature distribution in the plate thickness obtained in a computational experiment from a given distribution. The optimization problem is solved by the sliding-tolerance method with optimization by the deformable-polyhedron method. The article presents the results obtained in computational experiments modeling phosphate raw materials. The obtained numerical results agree well with the results of physical experiments, which confirms the adequacy of our developed mathematical and computer models and the proposed algorithm for solving the inverse-coefficient heat-conduction problem.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):16-21
pages 16-21 views

Heat-Pump Efficiency in Acetone-Methanol Extractive Distillation Depending on Feed Composition

Burachuk A.S., Anokhina E.A., Timoshenko A.V.

Abstract

The application of heat pumps in extractive distillation is studied on the example of the acetone–methanol mixture. The dependence of the efficiency on the feed mixture composition is investigated. It is found that the most effective in the whole range of feed compositions is the scheme with a heat pump in which the compressed overhead vapor of the regeneration column heats its own reboiler. A criterion for estimating the energy savings is suggested, based on which a number of efficiency conditions of heat-pump application both in extractive distillation and in distillation in general are formulated. Proceeding from the obtained results, a preliminary discrimination algorithm for versions of the distillation schemes with heat pumps is offered.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):22-37
pages 22-37 views

Development of Flowsheet of Separation of a Phenol Production Mixture Based on the Analysis of Phase Equilibrium Diagrams

Gaganov I.S., Belim S.S., Frolkova A.V., Frolkova A.K.

Abstract

In the large-scale production of phenol by the cumene method, an important constituent is the separation of multicomponent mixtures containing the target products and various impurities. The potential of distillation processes of a specific composition is determined by the structure of the vapor–liquid equilibrium diagram structure. The paper analyzes the phase diagram of a six-component system and its constituents of a smaller dimension. Thermodynamic restrictions on the distillation process associated with the presence of separatric manifolds are established, and ways to overcome them through the use of special techniques are shown. The structures of mixture separation flowsheets are proposed and the columns operation parameters are determined. The use of the re-extractive distillation process is a viable alternative for phenol purification, since it allows the second product of the cumene method, acetone, to be involved in the technological cycle.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):38-47
pages 38-47 views

Universality of Supercritical Carbon Dioxide in the Process of Tertiary Oil Production

Gumerov F.M., Zaripov Z.I., Khairutdinov V.F., Sagdeev D.I.

Abstract

The results of comparative analysis for the key factors of the mechanism of oil-recovery enhancement with the use of gases in a supercritical fluid state as applied to carbon dioxide and propane (propane/butane mixtures) are presented. The above-mentioned factors as a subject of consideration incorporate the dissolving ability of compressed gases with respect to oil and its components, the phase behavior of binary systems containing the mentioned displacing agents and oil hydrocarbons, the critical parameters for the binary systems of fluid-phase behavior types I–II, the compressibility of carbon dioxide and propane under oil-displacement process conditions in tertiary oil production, the viscosity of the media participating in the discussed process and, finally, the swelling of oil as a result of its saturation with a gas. The results of experimental implementation under supercritical fluid conditions are given for an extraction oil-recovery process with carbon dioxide as an extragent in one case and propane in the other case. It is established that propane and propane/butane mixtures are three or more times superior to CO2 in dissolving ability with respect to oil components under displacement-process conditions; that they more often form systems of fluid-phase behavior types I–II with the oil components, which is preferable for the process of its recovery; that the compressor power spent on the compression of carbon dioxide and methane is threefold or more higher than for propane; and, finally, that propane has a much lower viscosity under oil-displacement conditions. In sum, propane and propane/butane mixtures are preferable for use in the oil-displacement process within the framework of tertiary oil production.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):48-59
pages 48-59 views

Theoretical Substantiation of the Mechanism of Ultrasonic Dehydration of Materials Without a Phase Transition of Liquid Into Vapor

Khmelev V.N., Shalunov A.V., Golyx R.N., Terentiev S.A., Nesterov V.A.

Abstract

The article theoretically substantiates the ability of ultrasonic vibrations to dehydrate capillary-porous materials due to the dispersion of moisture from the capillaries and pores of the material under the action of shock waves formed by cavitation bubbles. A phenomenological model is presented based on the analysis of the slow growth of a distorted cylindrical cavitation bubble, taking into account the influence of the cylindrical capillary walls limiting its oscillations. The optimal range (150–170 dB) of ultrasonic pressure levels is revealed, at which the mechanism of cavitation moisture dispersion is realized. It is established that the optimal conditions for the action of ultrasonic vibrations on a dried material are realized when the dimensions or thicknesses of the layer of the dried material correspond to the length of ultrasonic vibrations in air.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):60-70
pages 60-70 views

Unsteady-State Mass Transfer in Gels with Microorganisms

Khramtsov D.P., Khramtsov O.A., Pokusaev B.G., Vyazmin A.V., Nekrasov D.A.

Abstract

Hydrogels are promising for use in tissue engineering as matrices for cell incubation and with subsequent use of such biomaterial systems as bioinks suitable for 3D bioprinting. The heat and mass transfer in hydrogel materials based on agarose and gelatin with model microorganisms incubated in the bulk of the gel are studied by the optical methods of spectroscopy and microscopy. The propagation of the fronts of the nutrient medium in pure gelatin hydrogels and mixed hydrogels based on agarose with the addition of gelatin are compared to determine the diffusion properties of the mixed hydrogels that can ensure the delivery of nutrient components to microorganisms. New data are obtained on the degree of heterogeneity in the growth of microorganisms during their bulk incubation under various temperature conditions of incubation, which is necessary to control the properties of bioink in bioprinting. An analytical description of the curve of cell growth in the gel is proposed, and on its basis an expression for determining the cell growth rate is obtained. A numerical model is developed to describe the absorption of nutrients by cells during their growth.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):71-80
pages 71-80 views

On Some Criterial Models of Convective Heat Transfer

Konoplev A.A., Rytov B.L., Berlin A.A., Romanov S.V.

Abstract

It is known that the results of calculations for various criterial models of convective heat transfer may differ from each other, which, according to existing ideas, is usually associated with different operating conditions of the heat exchangers under study. In the work, thermal engineering experiments are carried out with a laboratory water-to-water tubular heat exchanger of the “pipe-in-pipe” type with smooth tubes at normal pressure and moderate temperatures at various inlet temperatures of the heat carriers and their flow rates. The results of the experiment are compared with the results of calculations based on the models of B.S. Petukhova, S.S. Kutateladze, Nusselt, and M.A. Mikheev. The comparison shows that the discrepancies between the experiment and the models, as well as between the models themselves, stem not only from experimental inaccuracies, but also from inaccuracies in the models themselves.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):81-90
pages 81-90 views

Dual-Cascade System with Two Additional Feed Flows and a Product Flow for the Purification of Regenerated Uranium Hexafluoride from 232, 234, 236U

Palkin V.A., Maslyukov E.V.

Abstract

A dual-cascade system for the purification of regenerated uranium hexafluoride from 232, 234, 236U is proposed. In the first cascade, regenerated uranium is enriched to a 235U concentration of no less than 20% with a decrease in the mass 236U/235U ratio. Its additional feed flow is waste uranium hexafluoride, whose contaminated flow is removed as an additional product. The second additional feed flow is natural uranium hexafluoride. The main product flow from the first cascade is sent as a feed flow to the second cascade. Its waste purified from 232, 234U is diluted with low-enriched or natural uranium hexafluoride to the 235U concentration less than 5%. A numerical experiment is also performed. It is shown that the product formed after diluting the waste of the second cascade satisfies the ASTM C996-20 specification requirements for enriched commercial uranium hexafluoride in terms of  232, 234, 236U.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):91-97
pages 91-97 views

Analysis of Variants of Reforming of a Part of the Fuel (on the Example of Propane) in a Mixture with Internal Combustion Engine Exhaust Gas to Add the Reformate to the Combustion Chamber

Shigarov A.B.

Abstract

Thermochemical recovery of the heat of automotive internal combustion engine (ICE) exhaust gas saves fuel and reduces harmful emissions. Two designs of thermochemical heat recovery in propane-fueled ICEs are numerically analyzed. In both designs, a mixture of 10–20% of the initial propane with part of the ICE exhaust gas is subjected to catalytic reforming, and then the hydrogen-containing reforming products together with propane are added to the combustion chamber. In the first design, the reforming is carried out in an adiabatic reactor; and in the second, in a tubular one. In the analysis, the fraction of the exhaust gas recycle is varied within the range 0.1–0.5 and the temperature in the range 470–690°С. The second design is shown to be more efficient; it ensures an increase in the chemical enthalpy of the fuel mixture by 1.9–3.6% at a hydrogen mass fraction of 0.3–0.9%. For the operating conditions of an ICE with an effective power of 30 kW, the characteristics of an adiabatic reformer and a tubular reformer with a Ni/Cr2O3/Al2O3 catalyst are calculated.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):98-108
pages 98-108 views

Ultrasound Assistant Deep-Eutectic-Solvent-Based Liquid–Liquid Microextraction for the Determination of Transesterification Catalyst in Biodiesel Samples

Shishov A.Y., Markova U.O., Nizov E.R., Melesova M.A., Meshcheva D.A., Krekhova F.M., Bulatov A.V.

Abstract

Hydroxides of alkali and alkaline earth metals are most widely used as catalysts for transesterification of triglycerides of fatty acids in biodiesel production. After biodiesel purification, the determination of catalyst residue is performed to prevent their excess accumulation. Catalysts can promote the degradation of biodiesel. In this research, a simple, fast, and environmentally friendly strategy for the sensitive determination of transesterification catalysts (sodium, potassium, calcium, and magnesium) in biodiesel samples by flame atomization atomic absorption spectrometry is developed. The developed procedure is based on ultrasound assistant dispersive liquid–liquid microextraction of the catalysts in a hydrophilic deep eutectic solvent prepared by mixing quaternary ammonium salt and carboxylic acid. The effect of the nature of the deep eutectic solvent on the mass transfer of catalysts is investigated; in addition, the microextraction procedure conditions are optimized to obtain high sensitivity. The limits of detection established for the proposed procedure are 0.03 mg kg–1 for all analytes. No hazardous and volatile organic solvents are required for sample pretreatment. Sample preparation time is less 15 min.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):109-116
pages 109-116 views

Cold-Pressing Processing of a Fluoropolymer-Based Composite Material

Stolin A.M., Stelmakh L.S., Stelmakh E.V.

Abstract

External friction–assisted single-action cold pressing is theoretically analyzed as applied to powder polymer composite materials based on a fluoropolymer with small contents of additives (<5%), such as silicon dioxide SiO2, kaolinite Al4[Si4O10](OH)8, carbon nanotubes, and carbon fiber. Analytical solutions are obtained in the form of formulas that make it possible to analyze how the compaction of the materials is affected by the applied pressure, the coefficient of external friction, the geometric sizes of the compacts, and the properties of the material, including its porosity. A simplified system of the initial equations in Lagrangian variables after averaging over the radius is used to numerically calculate the development of the density inhomogeneity over the volume of the material as a function of time, which is brought about by the difference between the compaction rates of the lower and upper layers. New clear concepts of the kinetics of compaction of fluoropolymer-based powder materials are determined, and the qualitative features of various stages of development of the density inhomogeneity are identified. Answers are found to the practically important questions related to the experimental determination of the time of the pressing process to obtain a high-quality blank.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):117-124
pages 117-124 views

Extractive Distillation of the Tetrahydrofuran–Acetonitrile–Chloroform Mixture

Zhuchkov V.I., Ryzhkin D.A., Raeva V.M.

Abstract

The vapor–liquid equilibrium of the tetrahydrofuran–acetonitrile system, the equimolar tetrahydrofuran–acetonitrile–chloroform mixture is experimentally studied. The effect of various amounts of dimethyl sulfoxide on the relative volatilities of the components at 101.32 kPa is investigated. The extractive distillation flowsheets of the tetrahydrofuran–acetonitrile–chloroform mixture with dimethyl sulfoxide are calculated.

Teoretičeskie osnovy himičeskoj tehnologii. 2023;57(1):125-135
pages 125-135 views
pages 136-138 views

This website uses cookies

You consent to our cookies if you continue to use our website.

About Cookies