Fine Chemical Technologies (E-Journal) / Тонкие химические технологии
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ДВУХСТАДИЙНАЯ ПЕРЕКРИСТАЛЛИЗАЦИЯ С РЕГЕНЕРАЦИЕЙ РАСТВОРИТЕЛЯ
Get PDFIn this paper we propose an option of an energy-saving scheme for the two-stage recrystallization of substances from aqueous solutions with regeneration of the solvent from the final solutions by evaporation using a closed-type heat pump and recuperative heat exchange between the mass flows. Theoretical equations describing this process were derived. On the basis of these dependences we carried out analysis of the impact of some parameters on potassium nitrate recrystallization from aqueous solutions. It was found that the regeneration of the solvent from the final solutions allows reducing significantly the consumption of fresh solvent for the purification process. It was shown that the use of heat pumps at the stage of the solvent extraction from the final solutions combined with recuperative heat exchange between the mass flows is energetically most advantageous in most technological regimes. This is confirmed by high values of the energy conversion coefficient and low values (<1) of relative consumption of reference fuel. It was found that an additional stage of the product crystallization of from the evaporated solution allows increasing the output of refined products almost by a factor of 1.3. This has a positive effect on the technical and economic indicators of the purification process
ТЕОРЕТИЧЕСКОЕ ОБОСНОВАНИЕ ВЫБОРА ОПТИМАЛЬНОЙ СХЕМЫ РАЗДЕЛЕНИЯ ТРЕХКОМПОНЕНТНОЙ СМЕСИ
Get PDFIt is theoretically justified that for the scheme of separation of three-component mixtures with the release of the high-boiling component in the first column there is a region of initial compositions for which the heat costs are the least. An expression describing the boundary of the optimality regions of different separation schemes is given. The calculation of the heat costs for both rectification schemes of the three-component mixtures performed using the Aspen Plus software package confirmed the theoretical justification for the existence of optimality regions for each of them. With the help of the concept of internal energy saving, the advantage of one or another scheme of separation of a three-component mixture is explained.Теоретически обосновано, что для схемы разделения трехкомпонентных смесей с выделением высококипящего компонента в первой колонне существует область исходных составов, для которой тепловые затраты оказываются наименьшими. Приведено выражение, описывающее границу областей оптимальности различных схем разделения. Выполненный с использованием программного пакета Aspen Plus расчет затрат теплоты для обеих схем ректификации трехкомпонентных смесей подтвердил теоретическое обоснование наличия областей оптимальности для каждой из них. С помощью понятия внутреннего энергосбережения объяснено преимущество той или иной схемы разделения трехкомпонентной смеси
ПРЕВРАЩЕНИЕ КОРОТКОЦЕПНЫХ н-АЛКАНОВ ПОД ДЕЙСТВИЕМ ГИДРОДИНАМИЧЕСКОЙ КАВИТАЦИИ
Get PDFThe structure and properties of oil disperse systems (ODS) are mainly determined by the presence of paraffin hydrocarbons (n-alkanes) in the crude oil and natural gas liquid. Short-chain n-alkanes (С8-С17) are part of ODS dispersion medium. Under oil refining treatment, they concentrate in the distillate fractions and influence the operation characteristics of product liquid fuels and natural gas liquid.We studied the influence of hydrodynamic cavitation on the short-chain n-alkanes. Cavitation was produced by a high pressure disintegrator DA-1. A plunger pump produced compression pressure 50 MPa. Cavitation treatment was applied three times in a row. The research object was liquid oil paraffin containing 96.5% wt. n-alkanes С9-С21 (including 95% wt. С9-С17) and 2.5% wt. isoalkanes С10-С20; the balance was a mixture of other hydrocarbons. The results of GLC demonstrated that the total conversion of initial n-alkanes С14-С17 was not high, but it grew growing constantly: after the 1st cavitation cycle - 1.4%, after the 2nd cavitation cycle - 2.7%, after the 3rd one - 3.6%. At the highest conversion, the concentration of n-alkanes C8-C13 in liquid oil paraffin increased by 28% rel., and the concentration of n-alkanes C18-C22 - by 36% rel. The information obtained allows predicting the influence of the short-chain n-alkanes present in the oil feed on alterations of its hydrocarbon and fraction composition after cavitation
ОЦЕНКА ПЕРЕМЕННОЙ ИНТЕНСИВНОСТИ ОТВОДА ТЕПЛОТЫ ОТ ПОВЕРХНОСТИ ПАДАЮЩИХ И КРИСТАЛЛИЗУЮЩИХСЯ КАПЕЛЬ РАСПЛАВОВ В ПРОЦЕССЕ ИХ ПРИЛЛИРОВАНИЯ
Get PDFThe method of calculation of the intensity of heat removal from the surface of the crystallizing melt droplets is presented. A comparison with the experimental fixed values representing the intensity of the heat transfer between the surface of the resulting pellet and cooling agent is carried out. The influence of heat transfer coefficient on the surface of the pellet changes on complete crystallization time, and therefore on the size of the granulation tower, is analyzed. Conditions defining the heat transfer between the granule surface and surrounding coolant, while full crystallization in conjunction with the dependence of the rate of nucleation and growth of the granules determine mechanical properties of ammonia fertilizer granules.Представлен метод расчета интенсивности отвода теплоты от поверхности кристаллизующихся капель расплава. Проведено сравнение полученных значений с помощью предложенного метода с экспериментально зафиксированными значениями, характеризующими интенсивность теплообмена между поверхностью образующейся гранулы и охлаждающей средой. Проанализировано влияние изменения коэффициента теплоотдачи по поверхности гранулы на время полной кристаллизации, а, следовательно, на габариты грануляционной башни. Условие, определяющее теплообмен между поверхностью гранулы и окружающим хладоагентом, время полной кристаллизации в совокупности с зависимостями скорости зарождения и роста гранул определяют прочностные свойства гранул аммиачных удобрений
ЭНЕРГЕТИЧЕСКАЯ ЭФФЕКТИВНОСТЬ СЛОЖНОЙ КОЛОННЫ ПРИ РАЗДЕЛЕНИИ ПРОДУКТОВ ПИРОЛИЗА В ЗАВИСИМОСТИ ОТ СОСТАВА ПИТАНИЯ
Get PDFThe dependence of the energy consumption decrease on the different feed composition for the separation of C4+ vapor cracking fraction by means of complex columns implementation is investigated. Distillation sequences consisting of simple columns and partially thermally coupled distillation columns are compared. Cases of direct and indirect separation for all the schemes are considered. In order to reduce capital cost and industrial areas the implementation of dividing wall columns was proposed. These dividing wall columns are the thermodynamic analogs of partially thermally coupled distillation flowsheets. Analysis of temperature, liquid and vapor profiles in the partially thermally coupled distillation sequence revealed that only one column in the original flowsheets requires a structural change when converting it to the partially thermally coupled configuration. It is shown that the complex columns provide energy consumption reduction in the reboilers by 3-60% as compared to conventional distillation schemes
РАЗДЕЛЕНИЕ СМЕСИ АЦЕТОН-ХЛОРОФОРМ-н-БУТАНОЛ С ПРИМЕНЕНИЕМ ЭКСТРАКТИВНОЙ РЕКТИФИКАЦИИ В СХЕМАХ ИЗ ДВУХОТБОРНЫХ КОЛОНН
Get PDFИНТЕГРАЛЬНОЕ ПРЕОБРАЗОВАНИЕ ДЛЯ ТРЕТЬЕЙ КРАЕВОЙ ЗАДАЧИ НЕСТАЦИОНАРНОЙ ТЕПЛОПРОВОДНОСТИ С НЕПРЕРЫВНЫМ СПЕКТРОМ СОБСТВЕННЫХ ЗНАЧЕНИЙ
Get PDFThe mathematical theory of constructing an integral transformation and the inversion formula for it for the third boundary value problem in a domain with a continuous spectrum of eigenvalues are developed. The method is based on the operational solution of the initial problem with an initial function of general form satisfying the Dirichlet condition and a homogeneous boundary condition of the third kind. On the basis of the obtained relations, a series of analytical solutions of the third boundary value problem for a parabolic equation in various equivalent functional forms is proposed. An integral representation of the analytic solutions of the third boundary-value problem is proposed for the general form of the representation of boundary-value functions in the initial formulation of the problem. The corresponding Green's function is written out.Развита математическая теория построения интегрального преобразования и формулы обращения для него для третьей краевой задачи в области с непрерывным спектром собственных значений. Метод основан на операционном решении исходной задачи с начальной функцией общего вида, удовлетворяющей условию Дирихле, и однородному граничному условию третьего рода. На основе полученных соотношений предложена серия аналитических решений третьей краевой задачи для уравнения параболического типа в различных эквивалентных функциональных формах. Предложено интегральное представление аналитических решений третьей краевой задачи при общей форме записи краевых функций в исходной постановке задачи. Выведена соответствующая функция Грина
ОПРЕДЕЛЕНИЕ ФЕНОЛЬНЫХ СОЕДИНЕНИЙ В ДЕЗИНФЕКЦИОННЫХ СРЕДСТВАХ
Get PDFThe aspects of analytical determination of disinfectants derivatives of the phenol series аrе considered. The possibility of codetermination of five derivatives of this series in different disinfectants using the RP-HPLC method in the isocratic mode (UV detection) is shown. Alternatively, the possibilities of the determination with the use of spectrophotometry and GC methods are considered. This study and previous ones showed that the extraction of phenol derivatives by organic solvents from а wide range of disinfectants is feasible only in some cases, preferably with the use of hexane as an extractant. Further spectrophotometry of hexane extracts does not always enable to correctly compensate for the effect of background impurities and requires an additional separation of the components. The literature data and experimental results suggest that it is more efficient to analyze the whole series of disinfectants in isopropanol (sometimes in water) by chromatographic methods, preferably by HPLC. Sample preparation reduces to the solubilization of batches of ready-made disinfectants in isopropanol/water. It is optimal to carry out the chromatographic study using elution with acetonitrile-based systems (for example, СН3СN:Н2O, 60:40) providing the correct determination (λ = 280 nт) of phenol derivatives. The completeness of extraction (if the extraction method is used), as well as the metrology aspects of all the analytical determination is set directly in а laboratory during the realization of procedures of introduction/validation according to the internal documents of the system quality management for the relevant structural unit
