Vol 54, No 1-2 (2018)

A theoretical study is made of the solid dispersed materials dissolution process in shear flow of a viscous liquid. A sphere-in-cell model that takes account of the effect of the solid disperse phase concentration on the conditions of mass transfer on the surface of a random particle is analyzed. Analytical equations for calculating the shear stress and Sherwood number averaged over the surface of the particles in a shear flow are derived. The basic mechanisms of shear flow of a viscous liquid around spherical particles are disclosed.

The possibility of application of various types of ejectors in utilization modules for ammonium nitrate granulation is explored. The peculiarities of the working process of the utilization module which uses ejectors of various designs are described. The advantages of application of each type of ejectors are shown and the basic postulates of the mathematical model of the working process of vortex and jet ejectors are listed.

The influence of the passive method of heat transfer enhancement by increasing of the surface area of solid inclusions in water drops, on the conditions and characteristics of their boiling and breakup in conditions of intensive vaporization, was experimentally studied. Moreover, the main characteristics of these processes were defined: heating time of a drop till breakup, number and total surface area of formed droplets in comparison with the initial one (before breakup), limiting (critical) temperatures of sustainable (controlled) breakup of water drops. The substantial influence of artificial surface irregularities, porous surface geometry before and after water vaporization and inclusion shape (using the example of an irregular shape polyhedron and a cube) on the enhancement of heat-exchange processes in the water drop – solid inclusion system and the initiation of the explosive breakup of the liquid film of a heterogeneous drop was also demonstrated. Horizons of the explosive breakup application were distinguished for systems of thermal and flame purification of water from impurities, manufacturing a syngas from water solutions, emulsions and suspensions.

Based on the analysis of a model tube-type membrane reformer for the production of high-purity hydrogen from natural gas, a satisfactory quantitative correlation of the values of the main technological parameters at an operating temperature of 600°С was established, especially for the mode with purging by steam.

Questions connected with the determination of the dynamic loads arising in the mobile components of a planetary mill with a gear drive are considered. The influence of the structural and technological parameters on the magnitude of the loads is analyzed. A horizontal planetary mill with external (respectively, internal) spinning of the grinding drums was selected to conduct the study. Inertial forces that exert a significant influence on the motion were determined in the course of a power calculation of the planetary mill drive. Kinetostatics equations based on the d’Alembert principle were compiled. The angular velocity of the pinion carrier, the relationship between the geometrical parameters and the degree of loading of the drums were varied in the calculations. It was found that the support reaction and the circumferential force both vary according to the law of cosines over a narrow range. A method of calculating the dynamic loads on the support nodes of a planetary mill that takes into account the effect of the maximum number of parameters is developed.

A design of a fuel-spray injection burner for replenishing the fuel of users of the equipment of oil and gas companies is proposed. A schematic diagram of the newly developed burner design is presented and engineering designs by means of which lesser specific metal content is achieved than in existing constructions described, the operational reliability improved, and the overhaul life increased. Effective mixing of the fuel and air is realized in the new burner, overheating of the burner stabilizer prevented, and failures in firing are eliminated. The burner supports efficient combustion of gas fuel, including as well the liquid phase components.

The process of deposition of the solid phase of a suspension in the rotor of a continuous sedimentation centrifuge with a rigid wall and periodic discharge of the sediment was investigated based on the provisions of the hydrodynamics of slow movements. Results of quantitative analysis of the process of centrifugal separation of the suspension show that the calculation method of the efficiency of this process should be improved taking into account the layered structure of the flow based on the first model.

Optimization of the design of reinforcements of holes is achieved through an analysis of conditions for reinforcing holes in pressure vessels adopted in contemporary regulatory documents. A calculation of their stress-strain state performed by the Nastran program is used as an example. For entries into elliptical floors, a decrease in the estimated length of the reinforcing metal is recommended. It is shown that effective reinforcement of the lateral entries into a cylinder is possible only by increasing the total wall thickness of the body at the site of the entry.

The principle of operation of a piston hybrid power machine with gas suction capacity is described. Results of a numerical investigation and analysis of the influence of the ratio of discharge pressure to suction pressure on the characteristics of the studied machine are given.

Use of a standard technique for calculating the shear force of highly coercive KS-25DTs and Ch36R thin permanent magnets in magnetic systems and magnetic couplings is considered. Based on the results of the study, correction factors may be introduced into the standard technique used to determine the shear force in magnetic systems and magnetic couplings with thin magnets.

A classification of the ring packing contact components of heat and mass transfer devices, the chief example of which is the Raschig ring, is proposed. Examples of designs of domestically produced and foreign unordered and ordered ring packing contact components along with their advantages and drawbacks are considered.

Promising solutions have been identified that allow to significantly reduce hazardous emissions from combustion by substituting coal with coal-water slurries (CWS) and coal-water slurries containing petrochemicals (CWSP) as combustion fuels. Experiments show that satisfactory environmental indicators can be achieved even using coal and oil processing wastes as main components of CWSP.