Vol 50, No 2 (2016)

Unsteady-state Bénard–Marangoni convection in large-scale liquid flows with a linear temperature distribution at the layer boundaries has been investigated by the boundary element method. Two variants of boundary conditions are considered. In the case of temperature gradient components distributed at both boundaries, the boundary problem cannot be reduced to a one-dimensional one. The structure of layered convective flows has been studied. It has been demonstrated that the initial and boundary value problems considered here describe convective liquid counterflows and the formation of extremum (local and global) values of temperature fields. The existence of stagnant points (in which the liquid velocity is zero) inside the layer of the moving nonisothermal liquid has been discovered.

The inverse problem of identifying the parameters of sets of ordinary differential equations using experimental measurements of three functions that correspond to some components in the vector solution of a set is considered. A private case that is important for applications of chemical and biochemical kinetics when reduced equations linearly depend on the combinations of initial unknown parameters has been studied. An analysis and the numerical results are presented for two types of sets of chemical kinetics equations, such as the Lotka–Volterra model that describes the coexistence of a predator and a prey and the chemical kinetics equations that model enzyme catalysts reactions, including the Michaelis–Menten equations. The search for unknown parameters is confined to the problem of minimizing a quadratic function. In this case, the reduced differential equations of systems are used instead of their vector solutions, which are unknown in most cases. The cases of both stable and unstable search for unknown parameters are analyzed.

The modernization of reactor equipment for the industrial process of the sulfuric acid alkylation of iso-butane with olefins has been considered. Classic alkyl gasoline production technology has been improved by applying small reactors with a divergent-convergent configuration that optimizes the hydrodynamic regime in the reaction space. This emulsion process is subjected to theoretical analysis with the substantiation of the proposed contactor design. Industrial tests that confirm the high efficiency of the applied design compared to the functioning industrial sulfuric acid alkylation processes with regard to the reduction of energy consumption and the optimization of the consumption parameters of feedstock components and a catalyst have been described for this technology.

The approach to the problem of designing optimal heat-exchange networks for the reconstruction and synthesis of distillation columns is discussed. It has been proposed to reduce the original discrete-continuous nonlinear programming problem to the modified linear programming assignment problem that takes into account a number of features of separation systems.

The absorption of methanol from a contact gas in the production of technical formalin has been considered. The model of a conventional process flow sheet for absorbing methanol from a contact gas has been constructed using computer-aided modeling. The empirical coefficients used in the NRTL and Lee–Kesler models were determined. The amount of methanol in the absorption gases utilized by combustion in a conventional process flow sheet has been determined. The amounts of emissions in the case of an additional condensation stage and experimental and calculated data on the process have been compared. A method for minimizing toxic emissions that enables one tom eliminate the environmental load and increase energy and resource conservation has been proposed. The operational conditions of an absorber at a 22% increase in capacity have been considered.

Numeric studies of flow structures in a hydrodynamic filter have been presented. An analogy of flows that appear in a filter and the basic structure of flows in a hydrocyclone was drawn. The velocity and current line profiles in the operating domain of a filter were defined. Optimal correlations of regime parameters that provide a steady flow in the operating domain of a hydrodynamic filter have been found.

The paper discusses the possibility of using heat-flow calorimetry and differential scanning calorimetry to study the kinetics and modeling of industrial multistage reactions. The informativity of the obtained experimental data was studied and the methodology of applying them to solve inverse kinetic problems has been demonstrated. The results of using calorimetry to develop mathematical models of complicated chemical processes and applying them to optimize the operating conditions of industrial processes have been considered.