Theoretical Foundations of Chemical Engineering最新文献

{"title":"Difference Scheme of Higher Order of Approximation for the Hallaire’s Equation with Variable Coefficients","authors":"M. Kh. Beshtokov","doi":"10.1134/S0040579524601560","DOIUrl":"10.1134/S0040579524601560","url":null,"abstract":"<p>The initial boundary value problem for the one-dimensional Hallaire’s equation with variable coefficients and boundary conditions of the first kind is studied. The problem under study describes the processes of heat transfer in a heterogeneous environment, moisture transfer in soils, and fluid filtration in fractured porous media. To numerically solve the problem posed, a difference scheme of high order of accuracy is constructed: the fourth order of accuracy in h and the second order of accuracy in τ. Using the method of energy inequalities, an a priori estimate of the solution in a difference treatment is obtained. From this estimate it follows that the solution is unique and stable with respect to the right-hand side and initial data. Under the assumption of the existence of an exact solution to the original differential problem in the class of sufficiently smooth functions, and also due to the linearity of the problem under consideration, the obtained a priori estimate implies that the solution of the constructed difference problem converges to the solution of the original differential problem at a rate equal to the order of approximation of the difference scheme. The goal and scientific novelty of the work is to obtain a new numerical scheme of a higher order of approximation when solving the Dirichlet problem for the Hallaire’s equation with variable coefficients.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"734 - 737"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Polymodality of Secondary Kaolinite Distribution in Open Sandy Reservoir Systems","authors":"I. A. Melnik","doi":"10.1134/S0040579524601456","DOIUrl":"10.1134/S0040579524601456","url":null,"abstract":"<p>Numerous studies by various authors on the results of transformation of open systems have shown that the intensities and contents of the transformed elements have a polymodal form of statistical distribution in the case of external influence on the system. Apparently, the essence of the phenomenon of statistical polymodality of transformation of systems is universal. Therefore, the universal theory of polymodal distribution formation can be used to analyze samples of secondary mineral contents in permeable sand reservoirs, which are open systems. Obviously, each mode of the polymodal statistical distribution of the transformed elements will be the result of the manifestation of some attractor. The purpose of this paper is to present a universal kinematic theory of the formation of a polymodal statistical distribution of the number of transformed elements of an open system, where secondary clay minerals, kaolinites subjected to the process of superimposed epigenesis in a sandy reservoir, are considered as the formed elements. The objects of the study are samples of secondary kaolinitization intensity values in sand intervals of oil and gas fields of the Yamal Peninsula and the contents of secondary kaolinite (determined from the core) in the Upper Jurassic sand strata of the Stolbovoye oil-and-gas field. The process of secondary kaolinitization is due to the influence of deep fluids. The research method was determined on the basis of the obtained equation of unified modes of a polymodal distribution of the number of transforming elements (in the process of transformation of systems). The number (intensity) of transformed elements is proportional to the ratio of the system transformation time to the flow time of the external influence on the elements of this system. Seven basic constants (attractors) related to the “golden” proportion are theoretically calculated, bringing them into conformity with the universal principles of system transformation process states. Having compared the constants obtained theoretically with the calculated unified values of the modes of the empirical data, the states of the system-transformation processes with respect to each mode are determined. Analysis of the modes calculated in the polymodal distribution of the secondary kaolinite intensities and kaolinite content, as well as comparison of the mode values (with the corresponding transformation principle) with the empirical data on the transformation processes, give evidence for the validity of the universal kinematic theory. Thus, using universal principles of transformation, on the basis of the determined contents of secondary kaolinite in the studied intervals of the permeable strata, it is possible to identify zones with desired chemical and hydrodynamic properties and characteristics.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"787 - 797"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Algorithm for Finding the Optimal Composition of the Reacting Mixture on the Basis of the Reaction Kinetic Model","authors":"E. V. Antipina,&nbsp;S. A. Mustafina,&nbsp;A. F. Antipin","doi":"10.1134/S0040579524601559","DOIUrl":"10.1134/S0040579524601559","url":null,"abstract":"<p>The results of development of an algorithm for searching for optimal initial concentrations of substances in a chemical reaction are presented. The algorithm combines optimization methods with the theoretical foundations of modeling chemical reactions in terms of constructing their kinetic models. A mathematical description of the dynamics of the concentrations of reactants over time is presented in the form of a system of ordinary differential equations, the initial conditions of which are specified by the values of the initial concentrations of the reactants. The problem of determining the optimal composition of the reacting mixture is formulated in general terms. The problem involves restrictions imposed on the values of the initial concentrations of substances and on their initial total concentration. To solve the problem, the penalty method and the Hooke–Jeeves method are used. A penalty function is described that allows one to reduce the original problem to a problem without restrictions. A step-by-step algorithm for searching for optimal initial concentrations of a chemical reaction is formulated. A computational experiment is carried out for the catalytic reaction of aminomethylation of thiols using tetramethylmethanediamine. A kinetic model of the reaction is presented, on the basis of which an optimization problem is formulated to find the values of the initial concentrations of the reagents to obtain the highest yield of the target product at the end of the reaction. The optimal initial concentrations of the starting substances are calculated for different reaction durations and at different temperatures. The developed numerical algorithm for determining the optimal initial concentrations of the reagents takes into account the physicochemical features of the problem and can be used in the study of complex chemical reactions containing a large number of initial and intermediate substances. Its use makes it possible to determine the patterns of a chemical reaction at the stage of a computer experiment, without resorting to laboratory experiments, thus providing significant savings in time and material costs.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"728 - 733"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of the Effect of Low-Frequency Vibroacoustic Fields on Carbon Dioxide Absorption at the Liquid–Gas Interface","authors":"V. S. Boldyrev,&nbsp;N. A. Bogatov,&nbsp;A. S. Savina,&nbsp;A. P. Zotkin,&nbsp;E. I. Pentukhin","doi":"10.1134/S0040579524601572","DOIUrl":"10.1134/S0040579524601572","url":null,"abstract":"<p>This work is a continuation of the study of the effect of low-frequency acoustic axial low-energy oscillations of the infrasonic and early audible frequency ranges on the speed of surface treatment of various structural materials, primarily materials used in radio electronics. Low-frequency vibration treatment of surfaces of various alloys and semiconductors is one of the most promising modern tasks facing the domestic radio-electronics industry. The use of low-frequency acoustic fields makes it possible to increase the speed of metal surface treatment processes two- to five-fold. The so-called “bubble” etching method, involving the passage of air bubbles through the etching solution during surface treatment, is widely applied at present. This method makes it possible to intensify the process of surface etching and to significantly increase its speed, up to threefold. Etching with an external acoustic field shows similar results. In the work, studies are carried out comparing the process of gas dissolution in the field of low-frequency influences at the liquid–gas interface with the process of bubbling gas passed through distilled water. The results of the experimental study are presented to explain the reason for the acceleration of the etching processes in a low-frequency acoustic field due to the absorption of gases located at the phase boundary. Comparisons of the acoustic effect with bubbling and diffusion flowing through the liquid–gas interface are given.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"738 - 742"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the Effect of the Combustion Process on the Convective Heat Transfer in a Cylinder of a Marine High-Speed Diesel Engine","authors":"B. I. Rudnev,&nbsp;O. V. Povalikhina","doi":"10.1134/S0040579524601419","DOIUrl":"10.1134/S0040579524601419","url":null,"abstract":"<p><b>Abstract</b>—Until recently, when improving the existing mathematical models of local heat transfer in the combustion chamber of marine high-speed diesel engines, it was believed that the fuel combustion process has a strong effect on the parameters of convective heat transfer. However, modern experimental studies have shown that this effect is insignificant. The experimental convective heat fluxes obtained during the operation of a marine high-speed diesel engine on fuel and under pure compression differ by an average of 6–10%. The purpose of this article is to present and discuss the results of an analysis of the effect of the combustion process on the convective heat transfer in a cylinder of a marine high-speed diesel engine. The experimental data presented in the article show that the formation of the thermal load of the cylinder–piston group during the period of active heat generation is determined mainly by radiative heat exchange. This gives designers and researchers the opportunity to create mathematical models describing the processes of local heat exchange in the combustion chamber of marine high-speed diesel engines with greater accuracy and to reduce the time of experimental debugging of new samples.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"807 - 810"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling of the Process of Thermochemical Decomposition of Plant Waste in the Activated Carbon Production Line","authors":"R. G. Safin,&nbsp;A. S. Rodionov,&nbsp;D. F. Ziatdinova","doi":"10.1134/S0040579524601602","DOIUrl":"10.1134/S0040579524601602","url":null,"abstract":"<p>Today, there is a tendency toward an increase in the release of plant waste, which, with classical methods of disposal, leads to adverse environmental effects. The paper presents the results of mathematical modeling of the process of thermochemical decomposition of plant waste for a technological line for the production of activated carbon, designed to partially solve the problem of waste disposal. At the Department of Processing of Wood Materials of the Kazan National Research Technological University (KNRTU), a plant for the pyrogenetic processing of plant materials into activated carbon has been developed. Thermochemical decomposition of plant materials is a complex thermodynamic process in which a large number of chemical reactions occur with the absorption and release of heat. The process of pyrolysis of plant raw materials can be divided into three zones: pre-drying, thermochemical decomposition, and coal calcination. Each of these zones has its own differential equations. To optimize the modes of the activated carbon production process, there is a need for numerical modeling of the process of thermochemical decomposition of plant raw materials, since the quality of the obtained coal directly affects the adsorption capacity of the produced adsorbent and the percentage of impurities in the finished product. Numerical modeling produces as output the numerical values of the density; the heat of the chemical reaction in the process of splitting and polymerization of the constituent components of the plant raw materials and the temperature of the material in the process; the thermochemical decomposition; and the dependence of the duration of the thermochemical decomposition process on the thickness of the bulk layer and the size of the processed particles. Mathematical modeling is carried out by jointly solving the system of differential equations of thermochemical kinetics, expressed for an infinite plate. Pine chips 7 mm thick are taken as the object of the research.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"811 - 817"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of Thiophene Derivatives and Destruction Kinetic Regularities during the Cracking Process of High-Sulfur Vacuum Gasoil Oxidation Products","authors":"E. B. Krivtsov,&nbsp;A. V. Goncharov,&nbsp;Yu. A. Sviridenko,&nbsp;M. I. Merzhigot","doi":"10.1134/S0040579524601638","DOIUrl":"10.1134/S0040579524601638","url":null,"abstract":"<p>The results of a study of the composition of cracking products of high-sulfur vacuum gasoil from the Novokuibyshevsk Refinery under various conditions are presented. The quantitative content of sulfur in the liquid cracking products of vacuum gasoil, as well as in the liquid cracking products of oxidized gasoil and its non-polar and polar parts after separation by liquid-adsorption chromatography, is established. It is shown that in the process of thermal cracking of high-sulfur vacuum gasoil, sulfur is practically not removed from the composition of the liquid products. Derivatives of thiophene and benzo- and dibenzothiophene are intensively formed and accumulated, which worsens the quality of the obtained distillate fractions. Pre-oxidation reduces the thermal stability of the high-molecular-weight sulfur-containing components that are stable during conventional heat treatment. Pre-oxidation significantly slows down the accumulation of low-molecular-weight aromatic sulfur compounds in the liquid cracking products. As a result, sulfur-containing components both undergo condensation reactions into coke and destruct with the formation of gaseous sulfur compounds (hydrogen sulfide and lower mercaptans), which contributes to an increase in the degree of sulfur removal. Chromatographic analysis of the liquid cracking products of oxidized vacuum gasoil shows that under such conditions, no degradation processes of newly formed thiophene derivatives are observed. Separate heat treatment of non-polar and polar products of vacuum gasoil oxidation allows minimizing the occurrence of gas formation reactions by eliminating side interactions between the components. It is shown that the formation and accumulation of aromatic sulfur compounds (thiophene derivatives) in the obtained distillates occurs during the cracking of non-polar products, while the sulfur content in the composition of the liquid products practically does not decrease. Cracking of polar products leads to intense gas and coke formation, the sulfur content in the composition of liquid products decreases threefold, and thiophene and benzothiophene homologues predominate in the products.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"759 - 767"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improving the Efficiency of the Decomposition of the Aluminate Liquor by Preparing and Introducing an Active Seed into the Decomposition Process","authors":"K. D. Alekseev,&nbsp;I. V. Loginova,&nbsp;I. E. Chetyrkin,&nbsp;I. S. Gostinskaya","doi":"10.1134/S0040579524601626","DOIUrl":"10.1134/S0040579524601626","url":null,"abstract":"<div><p>The objective of the study was to determine the optimal parameters for preparing and dosing an active seed (finely divided aluminum hydroxide) to stabilize the decomposition process of the aluminate liquor during decomposition in the Bayer process. Laboratory tests were carried out on an Intronics temperature-controlled rotating water bath (Australia). Granulometric analysis of the obtained aluminum hydroxide was performed using the VideoTest automatic image analysis system with an Axioskop-40 microscope (Carl Zeiss, Germany) equipped with the Image Analysis program. Laboratory studies were conducted to obtain finely divided aluminum hydroxide (active seed) by mixing the alkali aluminate liquor and the process water in various ratios. It was determined that the process water should be the first to be fed and then the cooled alkali aluminate liquor should be introduced. The following optimal conditions for obtaining an active seed were found: the solution should be held for 48–72 h at a temperature of 50°C at a ratio of the aluminate liquor to the process water of 60 to 40%. Laboratory studies were conducted on dosing the obtained active seed into the head decomposers of the decomposition process. It was shown that the use of the active seed in the continuous process of decomposition stabilizes the granulometric composition of the product aluminum hydroxide. It was observed that the presence of the active seed allows reducing the initial temperature of the decomposition process from 62 to 58°C without changing the granulometric composition of aluminum hydroxide. In addition, the positive effect of introducing the active seed on increasing the degree of decomposition of the aluminate liquor to 1.5% was confirmed. Thus, based on the results of the studies, it was established that the use of a new method for preparing and dosing an active seed into the head decomposers allows intensifying the decomposition process in the production of alumina.</p></div>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"721 - 727"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361704","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluation of the Efficiency of Vortex Contact Devices in a Diabatic Distillation Column","authors":"I. N. Madyshev,&nbsp;I. V. Sannikov,&nbsp;O. S. Dmitrieva","doi":"10.1134/S0040579524601584","DOIUrl":"10.1134/S0040579524601584","url":null,"abstract":"<p>One of the most important criteria in the development of column mass transfer apparatuses is a high separating ability. This goal can be achieved by improving contact devices, as well as directly influencing the process itself. A vortex contact device has been developed, which consists of two coaxial pipes. There are slots on the surface of the inner tube; as vapor passes through the slots it begins to twist, forming a vortex dispersed–annular vapor–liquid flow in the annulus. The liquid flowing down from the upper contact stage is broken up into separate drops under the action of centrifugal forces and thrown to the wall of the vortex device, where a film flow is created. To implement the process of diabatic distillation, the vortex contact stage is equipped with a cooling jacket, where the coolant is supplied. On the example of this vortex contact device for diabatic distillation, the possibility of increasing the separating power of contact devices is considered. By tray calculation, the compositions and flow rates of the liquid and vapor phases at each stage of the column are determined. The process of diabatic distillation is carried out by removing heat from the stages of the rectifying part of the column. Calculations are made both with heat removal only from the upper stage of the column, and with different amounts of heat removed from the upper four stages of the column. The influence of thermal effects on the Murphree efficiency index is determined for various design parameters of the vortex contact device and various operating modes of the distillation column. The results obtained are compared with similar indicators of calculations of adiabatic distillation. The greatest increase in efficiency according to Murphree is achieved with an increase in the Reynolds criterion, as well as with an increase in the ratio of the height of the swirling vapor–liquid layer to the height of the slot of the vortex contact stage for the passage of vapor. It is established that additional heat removal makes it possible to increase the efficiency of the Murphree vortex contact device by 11% compared to adiabatic distillation.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"782 - 786"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of the Influence of Technological Parameters on the Properties of Transparent Conductive Oxides","authors":"E. A. Pecherskaya,&nbsp;T. O. Zinchenko,&nbsp;P. E. Golubkov,&nbsp;O. V. Karpanin,&nbsp;S. A. Gurin,&nbsp;M. D. Novichkov","doi":"10.1134/S0040579524601444","DOIUrl":"10.1134/S0040579524601444","url":null,"abstract":"<p>A model in the form of an oriented graph is developed, displaying the interrelations of technological modes and quality parameters of transparent conductive coatings. The model makes it possible to systematize the factors affecting the process and propose an analytical description of the effect parameters, the reactions to them, and the properties of the synthesized coatings in the form of a system of differential equations. Based on the specified mathematical model of the relationship between technological modes and coating properties, a method for selecting optimal technological parameters is developed in order to obtain transparent conductive coatings with specified properties. The achieved results can be used in technological processes for synthesizing transparent conductive coatings with specified properties.</p>","PeriodicalId":798,"journal":{"name":"Theoretical Foundations of Chemical Engineering","volume":"58 3","pages":"798 - 806"},"PeriodicalIF":0.7,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143361773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}