N. N. Kulov

The State of the Art in Chemical Engineering Science and Education

Chemical engineering education, research, and production are considered as intimately interrelated activities. The current status of the Russian chemical industry is characterized in brief. The tendencies of the development of chemical technology and problems of chemical engineering education are discussed.

Hybrid separation processes combining vacuum distillation with fractional crystallization, partial melting, and granulation

The physicochemical fundamentals of the combined processes of distillative crystallization (also called distillation crystallization or distillative freezing) and distillative sweating (also called distillation sweating or distillation melting) are considered. Results of the experimental study of the kinetics of separation of binary and ternary organic mixtures of various forms (liquids, powders, continuous layers, and granules) are presented. The high efficiency of the combined processes that make it possible to rapidly decrease the impurity content by one to two orders of magnitude after a single stage is shown. It is found that these processes can be used for effective separation of the mixtures of a eutectic composition when conventional crystallization is not applicable. Dependences of the important kinetic characteristic—an effective diffusion coefficient—on pressure are determined for a number of mixtures. An empirical formula for estimating its values is proposed. It is found that the kinetic features of the combined processes conducted under nonequilibrium conditions can cause both a decrease and an increase in the efficiency of separation of the mixtures of different types in comparison with calculated values for the equilibrium process. A method is developed that makes it possible to combine distillative crystallization with the granulation of a melt in a semicontinuous or continuous process on a cooled movable belt. The method ensures the additional purification of solidifying granules from volatile impurities. Results of calculating the main characteristics of the combined process for purifying naphthalene granules in the batch and continuous modes are given.

Some problems of separation of mixtures

The paths of the development of research and the change of priorities in the area of separation of mixtures are tracked by the example of analysis of the works of the laboratory founded by N.M. Zhavoronkov in 1945. The studies performed encompass a wide range of basic problems of heat and mass transfer in gas absorption, distillation (including vacuum, molecular, etc.), fractional crystallization, and melting. The subjects of the works under consideration include separation of isotopes of light elements, design of mass-transfer apparatuses with high unit power, investigation of the mechanism and kinetics of separation processes, studies of separation enhancement methods, and development of hybrid energy-and resource-saving processes and equipment.

Kinetics of chemisorption of ethylene by a chlorine solution

The rate of ethylene chemisorption by a chlorine solution is experimentally determined. It is shown that, in the first seconds of contact, the chemisorption is accompanied by surface convection, which enhances mass transfer. During long-term contact, the reaction mirror recedes from the interface and the convective mass transfer is replaced by diffusion mass transfer.

Countercurrent column crystallization of ternary mixtures with different mutual solubilities of components in the solid state

Characteristic features of the mass transfer in separation of ternary organic mixtures of two types and different compositions in a countercurrent crystallization column are studied. In a mixture of the first type, all the components form continuous series of solid solutions of each other, and in mixtures of the second type, only one pair of components does. The temperature and concentration distributions along the height of a modernized column in the startup period and steady-state operation are experimentally investigated. It is found that the concentration profile of the component with an intermediate melting point in the separation of a mixture of the first type has an extremum. Mixtures of the second type behave as pseudobinary mixtures if the crystallization occurs in the field of the component that forms simple eutectics with the two other components. The results of separation of ternary and binary mixtures of the same components are compared. It is shown that it is possible to increase the efficiency of separation of binary mixtures with solid solutions by controlled introduction of a third component.

Removing Volatile Impurities from Granules by Distillation Sweating

The physicochemical foundations of distillation sweating and the kinetics of the removal of volatile impurities from granules are considered. Expressions are suggested for estimating the separation efficiency in this combined process. Diphenyl, naphthalene and caprolactam granules have been purified. The influence of the nature of the separated components, the process conditions, and scale factors on the rate and efficiency are examined. The advantages of distillation sweating over ordinary distillation, sublimation, and fractional melting are demonstrated.

Kinetics of Unsteady Evaporation during Liquid-Phase Transesterification

The kinetics of unsteady evaporation during liquid-phase transesterification is studied theoretically and experimentally. A mathematical model of the process is proposed, and a satisfactory agreement between the calculated and observed data is demonstrated.

Ultrasonic activation of reagent purification of surface wastewaters from oil products

Reagent purification of water from oil contaminants can be intensified by preliminary ultrasonic short treatment of concentrated solutions. The major mechanism of the ultrasonic treatment of reagents is dispersion of coagulant and flocculant particles by cavitation. Based on the results of our studies, we chose the most suitable reagent and the optimum conditions of purification. The new acoustic reagent flotation technology is recommended for use in constructing waste disposal plants for surface water contaminated with oil products.

New design of reactive distillation processes

A technological design of reactive distillation processes (catalytic distillation) is discussed that applies liquid-flooded catalytic zones with a cocurrent-cross flow of the liquid, into each of which only a portion of the vapor stream is passed from the zone located below. This allows the cross section of the catalytic zones to be multiply reduced and the local excessive heating in them to be completely eliminated.

Dynamics of Unsteady-State Distillation Combined with Transesterification in the Liquid Phase

The kinetics of unsteady-state distillation combined with the catalytic transesterification of butyl acetate with ethanol is studied experimentally and theoretically. Experiments were carried out in the film column at total reflux. A mathematical study of the reactive distillation process is carried out using a cell model. The calculated and observed data are in satisfactory agreement.