Vol 53, No 1-2 (2017)

The results of experimental investigations of ignition of single droplets (radius of 0.5–1.5 mm) of coal-water slurry containing petrochemicals (CWSP) in a stream of air (oxidizer) with a temperature of 600–1200 K and velocity of 0.5–5 m/sec are presented. Carbon residue (particle sizes of 80–100 μm) from pyrolysis of used automobile tires, water, and exhausted engine, turbine and transformer oils were used as the main fuel components. The times of ignition delay and complete combustion of CWSP droplets were determined atvarying concentrations of the components in the ranges corresponding to modern combustion and burner devices. The conditions at which stable combustion of CWSP is initiated were determined.

Separation of suspensions in a batch-action centrifuge was investigated as an aggregate of phenomena of sedimentation of the solid phase, formation of sediment and filtration of the clarified liquid. Analysis was performed to determine the time-dependence of the results of centrifugal separation of a liquid system on the concentration of the solid, dispersion of the processed product, filter base, geometrical and physicomechanical parameters of the process. Using a particular example, separation efficiency of suspensions was estimated numerically from the processing times of the centrifugal equipment.

Results from hydrodynamics tests of mini-ring truncated-cone packing are presented. A relationship for calculating the hydraulic resistance of the new packing design is proposed. It is shown that the hydraulic resistance of the new packing at gas flow rate ω₀ = 0.8 m/sec is 40% less than for Raschig rings (50 × 50 mm).

A probabilistic mathematical model describing the deposition process in the layers of a precoat filter is proposed. The method for calculating the filtration process of superfine particles with an auxiliary precoat layer according to the proposed model allows the optimal modes of filtration devices and their design and operating parameters to be chosen.

The cryogenic helium plant KGU-5000/4.5 was designed for production of cold at the temperature level of 4.5 K. A feature of the refrigeration cycle of this installation is low pressure of downstream helium flow equal to 0.8 MPa. Heat exchangers in helium plants should provide small temperature differences for the large temperature gradient over the length of the device and small permissible hydraulic losses, which results in large dimensions and weight of these units. Compact and efficient heat exchange surface is one of the main tasks in the development of heat exchangers for low-pressure helium cryo plants.

Mathematical models are proposed for stationary and dynamic processes of technological furnaces as objects with distributed parameters based on the laws of conservation of energy, mass and momentum. Computational investigation of the stationary modes of tubular furnaces was conducted. The boundary-value problem was formulated for the calculations of the concentration of combustible substance, density, velocity, temperatures of the flue gas and the heated raw materials headed for separation in the rectification column. Results of calculations of the technological parameters are presented. The proposed method can be used for automating rectification units in petroleum-refining and petrochemical industry.

A design for a new desublimator with a warm wall allowing desublimation of up to 98% of uranium hexafluoride from a gas–vapor mixture with up to 90% of the theoretical desublimator filling was proposed. The desublimator was calculated, produced, and tested on a real industrial product.

Synthesis of a mathematical model of cooling of supercharging gas in the vapor space of cryogenic tanks containing liquefied gas is studied. Based on the model of a unidimensional dynamic thermal boundary layer, it is shown that the heat flux through the free liquid hydrogen surface in the cryogenic tank having a vapor space supercharged with gaseous hydrogen is much less than the heat flux through a wetted surface. The operational process of supercharging vapor space with gaseous hydrogen is studied by the example of a commercial liquid hydrogen tank. An example of calculation that shows the procedure of calculation of specific heat fluxes is given. The calculation results show that in the working range of fractions of the vapor space the heat flux through the liquid surface is much less than the heat flux through a wetted surface and that the heat of the supercharging gas exerts practically no influence on the change in temperature of the cryogenic liquid during its storage in the tank.

Use of high-coercivity permanent magnets from rare-earth alloys having active lengths (length of magnet along its rotation axis) smaller than the magnet width in cylindrical magnetic couplings is examined. Based on the research results, correction factors are introduced into the procedure of calculations of transferring torques of magnetic couplings. The fabricated couplings can be used to repair magnetic couplings having thin permanent magnets for foreign-made leak-proof pumps.

Application of polymeric composites in friction assemblies of oil-well pumps is studied. A scheme is proposed for testing specimens from a variety of composites in a steel roller pair, for which the area of the wear spot is taken as the wear resistance criterion. The best results are obtained for specimens from polyamide reinforced 50% with high-molecular-weight synthetic fibres laid perpendicularly to the friction surface.

Here, the design and principle of operation of a jet-bubbling contact device are presented along with the results of experimental studies of its hydraulic resistance and mass transfer efficiency.

Results are provided for statistical analysis of corrosion damage of fuel oil pipelines and storage tanks. It is shown that the fastest tank corrosion rate is observed in the lower and upper bands. Metal corrosion rate for these bands reaches 0.09 mm/yr and 0.025 mm/yr for central bands. Fuel oil pipeline corrosion rate is in the range from 0.002 to 0.079 mm/yr, and the average corrosion rate is 0.032 mm/yr.