|HEAT-AND-POWER ENGINEERING FUNDAMENTALS|
I.А. Davletshin, A.A. Valeev, N.I. Mikheev, A.A. Paereliy
flow patterns of two-component liquid water-exxsol mixture in a horizontal channel (Transactions of Academenergo. 2019. N 3. pp. 7-15). doi:10.34129/2070-4755-2019-56-3-7-15.
e-mail: Davlet60@mail.ru, firstname.lastname@example.org, email@example.com
Federal Research Center “Kazan Scientific Center of RAS”
Keywords: multicomponent mixture, flow pattern, hydraulic loss, mixing, separation.
Experimental setup for the study of hydrodynamics in multicomponent mixture flows was developed. Flow structure and resistance in a wide range of mixture compositions were investigated. The components were mixed hydrodynamically by turbulent mixing in the channel (tube). The mixture composition was estimated from measurements of flow rates of the components. Based on the accumulated experimental data on the structure of water-Exxsol mixture flows, a classification of patterns into seven groups was suggested. The hydraulic loss in the channel flows of water-Exxsol mixture with a mixture ratio of approximately 1:1 was estimated. For the considered patterns, the data agree with simulation employing a homogenous model.
V.G. Krioukov, F.K. Khaliullin
MATHEMATICAL MODELING OF HYDRODYNAMIC AND MASS-TRANSFER PROCESSES IN THE EXTRACTOR “CROWN-MODEL” (Transactions of Academenergo. 2019. N 3. pp. 16-38). doi:10.34129/2070-4755-2019-56-3-16-38.
E-mail: firstname.lastname@example.org, email@example.com
Kazan National Research Technical University by A.N. Tupolev
Keywords: mathematical model, counter-current crossed flows, oil extraction, porous medium, mass transfer, diffusion, slugging flow regime.
The previously created mathematical model of processes in the industrial extractor “Crown Model” is developed. This model applied the one-phase pattern of the miscella flow through a porous medium. But further experimental studies fulfilled on the specially created laboratory unit showed that the miscella flows through the porous medium in the slugging flow regime. Therefore, the integrated model of hydrodynamic and mass-transfer processes in the extractor has been modified. In addition to the previously incorporated processes (counter-current crossed flows of the porous medium and the miscella; mass transfer between the pellets and the miscella; diffusion in the entire extraction field; miscella transport between the percolation sections; influence of loading and drainage zones) the new model simulates the slug regime of flow. In addition, the new model considers the power impact of the miscella pumps on the rate of oil extraction from raw material, and more detailed reflects the hydraulic scheme of extractor. A comparison between numerical and experimental data showed that they are matched. Numerical studies were carried out and the results were analyzed, in particular, an explanation was given to the “non-single” value of the miscella drag factor in the horizontal direction. Are showed three dimensional graphs of the distribution in extraction field of oil concentrations for “bulk”, “pore” and “solid” phases.
|INDUSTRIAL HEAT-AND-POWER ENGINEERING|
R.F. Kamalov, V.O. Zdor
THE EFFECT OF MAZUT EXPENSE ON HEAT EXCHANGE AND HYDRODYNAMICS IN THE STORAGE TANK (Transactions of Academenergo. 2019. N 3. pp. 39-51). doi:10.34129/2070-4755-2019-56-3-39-51.
e-mail: firstname.lastname@example.org, email@example.com
Institute of Power Engineering and Advanced Technologies, FRC Kazan Scientific Center, Russian Academy of Sciences
Keywords: mathematical model, mazut facilities, numerical studies, circulation heating, storage tank.
In this work, are simulated thermal and hydrodynamic processes during the circulation heating of fuel oil in the storage tank. The results of numerical studies in the form of the distribution of thermal and hydrodynamic characteristics in the reservoir are presented. The dependences of the fuel oil temperature at the outlet of the tank and the average volume temperature of the fuel oil in the tank on the heating time and the mode of operation of the fuel oil heater are obtained. The time of heating the fuel oil in the tank from the «cold» reserve mode to the «hot» reserve mode has been determined.
V.I. Ryazhskikh*, A.M. Kokarev**, M.I. Slyusarev**
Operation stabilization of the low productivity air separation unit in nitrogen mode (Transactions of Academenergo. 2019. N 3. pp. 52-70). doi:10.34129/2070-4755-2019-56-3-52-70.
e-mail: firstname.lastname@example.org, Kokarev36@bk.ru, email@example.com
*Voronezh State Technical University
**Air Force Academy MESC AF «AFA»
Keywords: power-intensive plants, air rectification, thermal disturbances, dynamics, stability, performance characteristics
Quasi-continuous power-intensive plants, including periodic action equipment, generate thermal disturbances in process flows and cause transients that worsen equipment performance indicators. Using the example of an low productivity air separation plant, the task of hardware-parametric optimization of the liquid nitrogen production process is considered when thermal disturbance is introduced into the feed flow at the moment of switching the adsorbers of the cleaning and drying air unit to improve the air separation unit performance. Production tests of the ТКДС-100В gas station have established a determining effect of the bottom liquid level on the distillation column operation stability. The developed rectification process dynamic model, implemented in the MatLab/Simulink environment, made it possible to establish that the increase in column pressure to supercritical values under thermal disturbance of the feed stream is connected with the bottom liquid thermal inertia. The fluid limiting mass is determined, the excess of which providing the system stability to thermal disturbances in the feed flow of the ТКДС-100В station.
|POWER GENERATION STATIONS|
Conceptual basis for improvement of existing combined heat and power plants with steam turbines (Transactions of Academenergo. 2019. N 3. pp. 71-92). doi:10.34129/2070-4755-2019-56-3-71-92.
Ulyanovsk State Technical University
Keywords: combined heat and power plants, increase of energy efficiency, energy saving technologies, use of low-potential heat carriers, reduction of standard fuel costs
The main problems of combined heat and power plants (CHPs) are analyzed and the prospects for their further development are considered. The technologies of CHPs with high energy efficiency are developed, which allows to reduce the cost of fuel and energy resources during operation. In particular, the technologies of CHP operation with parallel inclusion of base and peak heat sources at the lowered temperature chart in a district heating system and by using quantitative methods of load regulation are offered. The expediency of using excess steam from the industrial outlets of turbine to provide peak thermal power proved by graph-analytical method of analysis of thermal load graphs CHP. Energy saving technologies of using the heat of the main condensate of turbines to heat various streams of heat carriers, and the potential of the natural gas jet to cool the flow of make-up water of the heat supply systems are developed. The possibility of reducing operating costs for reserve fuel storages of CHP is substantiated.
|POWER AND MECHANICAL ENGINEERING|
N.V. Boychenko, A.V. Tumanov
JOINT FRACTURE PROBABILITY IN TERMS OF ELASTIC STRESS INTENSITY FACTOR (Transactions of Academenergo. 2019. N 3. pp. 93-106). doi:10.34129/2070-4755-2019-56-3-93-106.
FRS Kazan Scientific Centre of the Russian Academy of Sciences
Keywords: joint probability, Weibull distributions, fracture toughness, stress intensity factor
Experimental programs of fracture mechanics usually include separate groups of specimens with different geometric characteristics (shape and size). Such a variety of specimens affects the reliability of the statistical assessment of failure. In this paper, a methodology based on a generalized local model described by a three-parameter Weibull distribution is presented. This method allows the probability of failure, based on a joint assessment of experimental programs, including specimens of various shapes and sizes.
The subjects for a study were compact and bending specimens made of steel: 34XH3MA, P2 and S55C, titanium (Ti6Al4V) and aluminum (7050) alloys. The relative crack length and sample thickness were varied for each specimen geometry. An additional factor for statistical evaluation was the direction of the specimen cutting relative to the axis of the main technological strains (for specimens of titanium and aluminum alloys).
The joint probability of failure obtained in terms of elastic stress intensity factors for all materials considered in this work. The obtained curves allow determining the elastic stress intensity factor range within which fracture will occur and estimate its probability.
A.P. Zakharov, D.A. Kosov, D.I. Fedorenkov, D.V. Fedotova
surface cracks propagation in power steam turbine baldes material (Transactions of Academenergo. 2019. N 3. pp. 107-121). doi:10.34129/2070-4755-2019-56-3-107-121.
e-mail: firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com
Institute of Power Engineering and Advanced Technologies, FRC Kazan Scientific Center, Russian Academy of Sciences
Keywords: surface flow, power steam turbine blade, finite element method, plastic stress intensity factor, crack growth rate, fatigue fracture diagram.
The current paper is concerned with numerical and experimental study of surface crack growth in 2Cr13 steel. Subjects for studies were cylindrical specimens with semi-elliptical surface crack. The specimens were cut from the working blades of the low-pressure cylinder of the condensation power steam turbine K-200-130. Surface crack growth features in cylindrical specimens with different initial notches were founded in the range of applied nominal stresses. The generalization of relationships of surface crack opening displacements and aspect ratio in cylindrical specimens were given by approximation functions. For the experimental surface crack paths in tested specimens the elastic and plastic parameters for the 3D-fields of the stresses and strains at the crack tip were calculated by finite element. The crack growth rate diagrams in terms of elastic and plastic stress intensity factors were presented for two crack growth directions.
Influence of loading conditions and initial notch geometry on the fracture resistance parameters of power steam turbine blade material was analyzed.
|ECONOMICS, ECOLOGY, INNOVATIVE TECHNOLOGIES AND PROCESSES IN POWER ENGINEERING|
D.V. Ermolaev, S.S.Timofeeva
INFLUENCE OF THE STRUCTURE MODELS OF ASPHALTENES OF HIGH-VISCOUS HYDROCARBON FEEDSTOCKS ON THE THERMAL PROPERTIES OF PRODUCED SYNGAS (Transactions of Academenergo. 2019. N 3. pp. 122-134). doi:10.34129/2070-4755-2019-56-3-122-134.
e-mail: firstname.lastname@example.org, email@example.com
Federal Research Center «Kazan Scientific Center of Russian Academy of Sciences»
Keywords: oil, bitumen, tar sands, asphaltenes, structure
The article presents a study of the influence of various structure models of asphaltenes on the thermal properties of the syngas obtained during the gasification process. The results showed that during the simulation a steam gasification of asphaltenes, the content of the main components of the syngas in the considered structure models is equal to 12.1-13.1% for H2; 29.6-33.2% for CO; 39.1-39.4% for CO2 and 4.8-5.7% for CH4. The sulfur compounds formed during gasification have the following concentrations: 12–12.6% for H2S; 60.8-62.4% for COS and 25.5-26.6% for CS2. The amount of coke residue is equal to 16.4-20.5%, depending on the structure model of asphaltenes. The calorific value of produced syngas ranges from 13731 to 14272 kJ/kg. The highest value corresponds to the model of asphaltene with porphyrin complexes.