Vol 54, No 11-12 (2019)

The results of experimental studies of emulsification processes in rotor-disk mixers having various designs of the working units that allow control of size-wise disperse particle distribution are reported. It is shown that the size of disperse particles decreases with increase of the area of perforations in the working units of rotor-disk mixers and with installation of additional components (teeth). Thereupon, the power consumption increases because, with the experimental parameters (rotation frequency, flow rate, ratio of mixer components, etc.) remaining identical, the average size of disperse particles decreases and, consequently, the interface area increases.

Xenon is a cryogenic product that is currently in short supply. Requirements for its purity are increasing. Its consumption in microelectronics, medicine, and space technology and for high-energy particle physics research is rising. The permissible impurity contents in Xe for various applications were analyzed. A universal research cryogenic unit for Xe production of throughput up to 10 Nm³/h of feedstock mixture was designed. A scheme with separation by rectification and preliminary catalytic and adsorptive purification of the feedstock was chosen. The unit was built in blocks so that processing schemes for Xe production from various mixtures, e.g., Kr–Xe, Xe–N₂, Xe–O₂, could be studied. Trace impurities in Xe were analyzed by gas chromatographs with thermal conductivity (TCD), He-ionization (HID), and flame-ionization detectors (FID). Water vapor in the analyzed gases was measured using laseroptical and coulometric hygrometers. The first runs showed that the unit could produce Xe of purity up to 99.9999 %. Experimental data for rectification of Xe to a purity of 99.999 % are presented. Xe could be purified experimentally from traces of CF₄, C₂F₆, SF₆, hydrocarbons, CO₂, and H₂ to 0.05; O₂ and N₂, 0.1; Kr, 0.01; and water vapor, 0.2 ppm.

A modern air separation plant control system must solve a host of problems, including variation in conditions of plant operation with full guarantee of its automatic flow. The procedure of gearing the plant from one operation mode to another is based on gradual change of control action and collection of desired products without impairment of their quality below the allowable level. To accomplish this task, it is essential to determine the values of the key process parameters for various air separation plant operation conditions and the maximally allowable control action variation rate. Based on the investigation results and comparative analysis of the values of the key process parameters of optimized static-state regimes in UniSim Design environment and actual indicators with a real plant, we found insignificant deviation of the calculated parameters from the actual values during the plant operation. It was concluded that the results of air separation process modeling in UniSim Design environment or the magnitudes of control actions derived by equations of material and heat balances of the plant can be used, in a first approximation, in plant operation mode change algorithm.

The causes of gaseous nitrogen (N₂ ) losses from the atmosphere of an inhabited space station and the methods for restoring the atmospheric composition are reviewed. The desirability of delivering compressed gaseous and solid N₂ to the station is shown. Expressions for calculating the amount of N₂ required for delivery to the space station are given. The refrigeration capacity of compressed and gaseous N₂ for thermostatting electronic devices is estimated.

A classification of removable vortex generators (turbulators) in pressurized tubular channels with round cross-section is proposed. The most characteristic designs of vortex generators offered by domestic and foreign designers and inventors are considered.

Apparatuses with a suspended transportable bed (ASTB), despite a number of important advantages over the known constructions of convective dryers, have not yet found wide application due to the limited understanding of some of the features of their operation. In this article, the results of laboratory studies of some hydrodynamic features of ASTB operation are applied to the process of drying potassium chloride. In particular, an experimental study of the flow structure of potassium chloride particles is presented; the mean residence time of the particles in the apparatus is given along with the calculated residence time distribution depending on the available cross-sectional area of the gas distribution device and the main process parameters of device operation. The obtained results confirm the prospects of using ASTB for drying potassium chloride.

An original method for calculating the equilibrium pressure for the formation or dissociation of multicomponent gas hydrates as a function of temperature and composition has been developed. It is applicable to gas and water systems that are in the following phase states: gas–water vapor–ice; gas–water vapor–liquid water. The developed method is suitable for determining the equilibrium conditions for the formation (dissociation) of hydrates of multicomponent gases depending on their composition with an accuracy of about 1%. The novelty of the developed method is protected by a patent of the Russian Federation.

Experimental data on high-temperature vaporization of heterogeneous water drops, obtained by high-speed video recording, and Ansys Fluent software package were used to develop a predictive mathematical model of heat and mass transfer. An assessment was made of the influence of the key process parameter, namely, the temperature of a gaseous medium ( T_g = 500 – 850 K), on the integral characteristics of vaporization of homogeneous drops of water and drops of aqueous suspension containing graphite inclusions. The dependencies of complete vaporization and disintegration (due to ebullition) time on the temperature of the gases are established. The numerical modeling and experimental data are compared.

Experimental results for absorption drying of natural gas by a developed granulated material based on chemical water-treatment sludge of Kazan TAC-1 are presented. A batch adsorber with a fixed bed of this material is calculated. A technological scheme for a recuperative adsorption plant for drying natural gas is proposed.

Results of research on the processing of spent acid etching solution (SAES) produced during manufacturing of titanium products by their etching in hydrochloric acid are presented in this paper. The processing technology consists of neutralizing SAES with alkali, filtering, drying and calcining of titanium hydroxide precipitate, and also processing of filtrate by electrodialysis in a cell with ion-exchange membranes. Anion-, cation- and bipolar ion exchange membranes were used. It is shown that the processing of SAES formed during etching of titanium products makes it possible to purify effluents to remove NaCl in an electrodialysis cell with monopolar and bipolar membranes. Transfer of Na⁺ and Cl^– ions through the bipolar membrane MB-1 was observed. Thus, solutions generated in acid and alkali concentration chambers contain significant amounts of NaCl. It is obvious that the introduction of buffer chambers is necessary to obtain acid and alkali solutions free from NaCl when using bipolar membranes.

Results of experimental studies of the operation of burners for various technological types of oil refinery furnaces are summarized in the form of mathematical models for the yield of carbon and nitrogen oxides. Effects of temperature in the burning zone, excess air coefficient, and the temperature of air supplied for combustion on the emissions of harmful substances into the atmosphere were determined. The following burners were selected for the study: a GP-1 diffusion burner, a GIK-2 kinetic burner, and an FP-2 diffusion-kinetic burner. Recommendations for selecting the least toxic gas burners are given. Technical solutions are outlined by the author for modernizing the structure of GP-type burners to increase ecological compatibility of their operation.

The present study is devoted to evaluating the influence of the number of technical inspection cycles on the remaining life of gas cylinders with different methods of cleaning of the inner surface of the equipment and with different compositions of the corrosive media. The thickness of the wall of the cylindrical part, floor, and neck of a gas cylinder is calculated as a function of the number of cycles of technical inspection, employing different methods of cleaning the internal surface of the cylinder, including mechanical treatment with chains, shot blasting, and a pulsating flow of shot in a fluidized bed. The reduction in the thickness of the wall of the vessel is analyzed in the course of corrosive and erosive action of different working media and it is found that the cylindrical part of the cylinder is the zone that is the most susceptible to damage. Treatment with a pulsating flow of shot in a fluidized bed during technical diagnostics makes it possible to realize more uniform removal of the surface layer of metal throughout the internal volume of the gas cylinder as compared to conventional shot blasting and, ultimately, to reduce internal stresses in the material and increase the life of the vessel. Where condensate is present, the greatest damage is found in the bottom and lower cylindrical part of cylinders used to store nitrogen and carbon dioxide.

An analysis of the process of filling cavities in articles with a control gas in leakage testing is presented. Based on the results of the analysis an algorithm that describes the process of filling cavities with a gas that produces a reduction in filling time is proposed. The proposed algorithm provides a foundation for automation of leakage testing of articles by gas methods.

An approximate approach for determining the load of plastic failure (burst load) in pressure vessels with nozzles through calculation of the maximum of the characteristic loading curve of the structure (where the load is the maximum intensity of plastic strain) constructed with the use of restrained nonlinear finite element analysis and the theory of approximation of curves is proposed. Two methods of approximation of the characteristic curve are considered: elliptic approximation and approximation with the use of a quadratic polynomial. Analytical formulas for determining the value of the burst load are obtained for both methods. Estimation of the burst pressure for an experimental model of a vessel with a radial nozzle is presented as an example. A comparative analysis of a calculation of the burst pressure using formulas obtained for different choices of base points for the approximation and different values of the burst pressure obtained from the full nonlinear finite-element analysis for the experimental model is performed. It is shown that an approximation of the burst pressure can be achieved with a sufficient degree of accuracy on the basis of a limited volume of computed results with moderate computational costs.

The methodology and results of a calculation of economic and energy-saving effects in cyclones through the use of vane-type whirling devices are presented. Data on the reduction in hydraulic resistance and energy consumption achieved with gas cleaning by means of such devices in СN-11 and СN-15 cyclones, the types of cyclones that are the most common, are given. It is shown that the use of energysaving devices is economically profitable, with a recoupment period of less than a year on average.