Vol 54, No 9-10 (2019)

A shortcoming of a drum loose materials size classifier is its low classification efficiency due to formation of a segregation core around the circulation center. A screen design that allows breaking of the segregation core is described. Model representations are expounded to describe the classification process. Based on the results of numerical experiments using a mathematical model of the classification process, a variant of segregation core breaking in a precalculated section across the screen length is proposed. The results of full-scale experiments showed negligible discrepancy (within 15%) between calculated and experimental values.

The paper describes the process of coupled numerical simulation of two-phase flow using the Dense Discrete Phase Model (DDPM), the Eulerian Wall Film model, and the k –ω turbulence model in static mixers filled with coalescing “Inzhekhim” packing elements. Device efficiency is mainly determined by the packed bed column height and the Reynolds number.

A mathematical description of the electrobaromembrane process using an approach based on the Nernst–Planck and Poisson–Boltzmann equations is presented. The hydrodynamic conditions in the intermembrane channel is taken into account by a dimensionless equation based on the Reynolds criterion and a technique is presented for determining electrobaromembrane separation of solutions, taking into account the kinetics of mass transfer and the hydrodynamics of the flow of a solution in an intermembrane channel. Through the use of the technique the local mass-transfer coefficients along the length of the channel of the membrane module may be determined. The technique may also be used to predict and develop laboratory, pilot and industrial electromembrane instruments and plants.

Investigations of the influence of the geometrical parameters of the flow path on the integral power characteristics of a free-vortex pump are conducted by means of numerical CFD methods. Recommendations for selecting the width of the profile of the impeller blade and the number of blades are given. The cavitation features of the designed vane systems are investigated.

To intensify the process of geothermal water concentration, a crystallizing evaporator design is proposed with a hydrocyclone installed in front of the entrance to the heating chamber. The main design parameters and dimensions of the evaporator and hydrocyclone are determined for specified performance.

The hydrodynamic regime used in apparatuses with suspended transportable bed of granular material (ASTB) occupies an intermediate place between fluidization and pneumatic transport. To select the basic method of calculation of ASTB, it is essential to determine which apparatuses they are close to in flow structure. In this context, studies of the flow structure in the ASTB and determination of the basic design and technological parameters affecting this characteristic are urgent. The results of determination of the modified Peclet number and the longitudinal mixing coefficient in a wide range of variation of ASTB operation conditions are presented. The obtained results confirm the closeness of the flow structure in ASTBs and pneumatic tubular driers.

Inert gases are valuable products that are widely used in industry. Their processing scheme includes several enrichment, purification, and separation stages of a Ne–He mixture (NHM). Primary enrichment of the NHM occurs in air-separation plants. Secondary enrichment uses a reflux condenser at liquid N₂ temperature (~78 K). The impurity concentration at the reflux condenser outlet can be decreased by reducing the operating temperature. However, the specific energy consumption increases whereas the extraction coefficient is practically not affected if a vacuum pump is applied. A promising trend for reducing the cooling temperature is to use non-machine cold sources. The Ne extraction coefficient during rectification depends on the impurity (He) content in the waste gases. The main method for increasing the efficiency of Ne production installations is to use additional non-machine cooling of the rectification input stream. The adsorption installation for recycling Ne from He concentrate can be chilled using two coolants, i.e., Ne and liquid N₂. The research showed that the specific energy consumption of the separation is 5–7 times greater to reach Ne temperature (28 K) than liquid N₂ temperature (78 K).

The article presents a description of a new method of calculation by means of which the distribution of the temperature of a mixture of coolants along the working circuit of a low-temperature refrigerating machine may be calculated to a first approximation and the quantitative composition of a charge mixture of coolants determined for a given composition of the circulating mixture of coolants.

Recycling to recover Xe from its mixtures is proposed because of its shortage and high price. The simplest recycling scheme involves several consumers connected to a common centralized Xe enrichment and purification complex. However, such a scheme has limited applicability because it can cover only small regions. A versatile recycling scheme is based on deployment of a network of cryogenic separators operating in unison with rare-gas consumers. Such a solution can be implemented using fully automated units and remote control of their operation, possibly over the internet. Introduction into the rectification column of an intermediate gas, the boiling point of which is between those of the mixture components to be separated, is proposed to prevent Xe from freezing on contact with the low-temperature component. Control methods that ensure stable rectification of Ar–Xe mixtures in the presence of Kr as an intermediate are developed and tested.

The experimental dependencies of the quantity of liquid in the discharge line of the compressor section on the discharge pressures of the compressor and pump sections of a piston hybrid energy-generating machine having stepped slot seal are presented and analyzed. The dependencies of the characteristics of the studied machine on the slot seal gap sizes obtained in the numerical study are presented and analyzed.

Pulsed acoustic analyzers of chlorine in N₂, air, and O₂ are considered. The possibility of using these devices for technological process control in the chemical and related industries is demonstrated by mathematical modeling.

The basic techniques of computer-aided 3D variant design of an ultrasonic device based on a proposed technique of structuro-parametric simulation of a dosing cavitation device with rectangular radiative plate are described. The proposed approach assures effective determination of the required rational dimensions of the radiative plates and ultrasonic vibrators to optimize their features when employed in specific technological processes, in particular, ultrasonic cavitation dosing in the technology employed in the manufacture of composite fibrous materials.

Comparative studies of precipitation-hardening corrosion-resistant nickel-base alloys used in the oil and gas industry are conducted. Corrosion-electrochemical properties of ÉP718 and Inconel 718 alloys are studied, and composition and microstructure are analyzed. It is observed that the passivity of these alloys may be affected significantly by the amount and composition of nonmetallic inclusions. It is demonstrated that these alloys may be used as analogs.