14 research outputs found
MINIMIZATION OF TOXIC EMISSIONS DURING BURNING LOW-GRADE FUEL AT KAZAKHSTAN THERMAL POWER PLANT
No full textThis paper presents new results of computational experiments on the implementation of Overfire Air (OFA) technologies using an example of a combustion chamber of the BKZ-75 boiler of the Shakhtinskaya power plant (Shakhtinsk, Kazakhstan) burning high-ash Karaganda coal. The effect of mass air flow through special nozzles located above the burner level on the flow aerodynamics, temperature fields, concentration fields of carbon monoxide CO and nitrogen NO over the entire volume of the combustion chamber was studied. The studied characteristics were compared for various percentages of supplying additional air through OFA injectors: OFA is 0% (basic version), 10% and 18 %. It was shown that the installation of OFA injectors leads to a change in the field of the total velocity vector, temperature, and concentrations of carbon oxides and nitrogen. An increase in the percentage of air supplied through OFA injectors to 18% leads to a decrease in the concentrations of carbon monoxide CO by about 36% and nitrogen oxide NO by 25% compared with the base case. The obtained results will optimize the process of burning pulverized fuel in the combustion chamber of the BKZ-75 boiler, increase the efficiency of fuel burnout, reduce harmful emissions and introduce OFAtechnology at other coal-burning thermal power plants
3-D MODELING OF HEAT AND MASS TRANSFER PROCESS DURING THE COMBUSTION OF SOLID FUEL IN A SWIRL FURNACE
No full textIn this work, a comprehensive study of thermal processes and aerodynamic and concentration characteristics of the combustion chamber of the boiler BKZ-75 of the Shakhtinskaya thermal power plant (Kazakhstan) are presented. A comparison of the characteristics of the combustion processes for two cases is given for the direct-flow method of supplying the mixture - the burners are located on opposite-side walls and the swirl-air mixture supplying method - burners with a swirl angle of the air mixture flow and their inclination to the centre of symmetry of the boiler by 30 degrees. The research results allow us to determine the optimal technological parameters of the studied object, to improve the methodology for the numerical study of heat and mass transfer processes in high-temperature and chemically reacting flows in the presence of turbulence, and also develop appropriate technological solutions for installing burner devices (direct-flow or swirl) in the studied combustion chamber
3-D MODELING OF HEAT AND MASS TRANSFER PROCESS DURING THE COMBUSTION OF SOLID FUEL IN A SWIRL FURNACE
No full textIn this work, a comprehensive study of thermal processes and aerodynamic and concentration characteristics of the combustion chamber of the boiler BKZ-75 of the Shakhtinskaya thermal power plant (Kazakhstan) are presented. A comparison of the characteristics of the combustion processes for two cases is given for the direct-flow method of supplying the mixture - the burners are located on opposite-side walls and the swirl-air mixture supplying method - burners with a swirl angle of the air mixture flow and their inclination to the centre of symmetry of the boiler by 30 degrees. The research results allow us to determine the optimal technological parameters of the studied object, to improve the methodology for the numerical study of heat and mass transfer processes in high-temperature and chemically reacting flows in the presence of turbulence, and also develop appropriate technological solutions for installing burner devices (direct-flow or swirl) in the studied combustion chamber
Numerical investigation of heat and mass transfer processes in the combustion chamber of industrial power plant boiler. Part 1, Flow field, temperature distribution, chemical energy distribution
No full textIn the present paper, the furnace chamber of the BKZ-160 boiler ofAlmaty TPP-3 (Kazakhstan) has been calculated.
The thermal characteristics of the process were studied in the form of the distribution of temperature fields and
chemical energy, and the aerodynamics of the combustion chamber was also calculated. The type of fuel, its
elementary and fractional composition, exerts the greatest influence on the course of heat-mass exchange processes
and aerodynamics. The computational experiment was carried out with two models of particle size distribution: a
polydisperse fuel flame (the particle diameter varies from 10 to 120 μm) and monodisperse fuel flame (particle size
identical and equal to dp = 60 μm). Based on the results of the computational experiments, the main regularities in
the distribution of heat fluxes in the combustion chamber volume and flow aerodynamicswere obtained. It is shown
that the greatest thermal load falls on the central region of the walls of the combustion chamber and the location of
the burner devices, which is typical for both mono- and polydisperse fuel flames. The temperature data obtained
as a result of the computational experiment showed better convergence with the empirical data obtained directly
at TPP-3. Aerodynamics of the flow for the two selected models of particle size distribution has insignificant
differences, but how they affect other characteristics of the process is one of the following tasks in view of the
authors. It should be noted that the calculation of the polydisperse fuel flame takes much more calculation time
Визначення оптимальної температури окислення неізотермічних впорскувань рідких палив з використанням моделювання на основі статистичного розподілу крапель за розмірами
No full textSingle-hole injections of liquid hydrocarbon fuels (isooctane and dodecane) under high turbulence have been investigated using direct numerical simulation based on the statistical model considering the droplets’ atomization, distribution, and combustion. The study objects are the heat and mass transfer processes during atomization and combustion of liquid fuels injections within the combustion chambers of thermal engines. The temperature and carbon dioxide concentration distributions of the fuel-air mixture, the distributions of the droplets, their velocities, and the Sauter mean radius within the isooctane and dodecane oxidation in the engine’s combustion space were obtained. An investigation of the oxidizer’s initial temperature influence on the droplets’ atomization and combustion processes showed that the optimal temperature for both fuels is 900 K. The obtained modeling results were confirmed in good agreement with theoretical and experimental data.
Thanks to the integrated use of approaches from statistical theory, numerical algorithms and 3D computer modeling techniques, the results obtained are distinguished by high accuracy, efficiency in reducing computational resources, scientific novelty in the type of droplet atomization and suitability for practical application for technological solutions not only for single-hole, but also for multi-hole injections of liquid fuels and studying the jet-to-jet interaction phenomena.
The obtained research results can be applied in miscellaneous internal combustion engines development with different atomization types, which will allow us to contemporaneously settle the concerns of streamlining the combustion process, improving the completeness of fuel combustion and reducing emissions of harmful substancesЗа допомогою прямого чисельного моделювання на основі статистичної моделі, що враховує процеси розпилення, розподілу та згоряння крапель, були досліджені одноструменеві впорскування рідких вуглеводневих палив (ізооктану і додекану) в умовах високої турбулентності. Об’єктами дослідження є процеси тепломасообміну при розпиленні та згорянні впорскувань рідких палив у камерах згоряння теплових двигунів. Отримано дані про розподіл температури та концентрації вуглекислого газу в паливоповітряній суміші, розподіл крапель, їх швидкості та середній радіус Заутера в межах окислення ізооктану і додекану в камері згоряння двигуна. Дослідження впливу початкової температури окислювача на процеси розпилення та згоряння крапель показало, що оптимальна температура для обох видів палива становить 900 К. Підтверджено гарну відповідність отриманих результатів моделювання теоретичним та експериментальним даним.
Завдяки комплексному використанню підходів статистичної теорії, чисельних алгоритмів і методів комп’ютерного 3D-моделювання, отримані результати відрізняються високою точністю, ефективністю скорочення обчислювальних ресурсів, науковою новизною в типі розпилення крапель та практичною застосовністю в технологічних рішеннях не тільки для одноструменевих, але й багатоструменевих впорскувань рідких палив та вивчення явищ взаємодії струменів.
Отримані результати досліджень можуть бути використані при розробці різних двигунів внутрішнього згоряння з різними типами розпилення, що дозволить одночасно вирішувати завдання оптимізації процесу згоряння, підвищення повноти згоряння палива і зниження викидів шкідливих речови
Computer Technologies of 3D Modeling by Combustion Processes to Create Effective Methods of Burning Solid Fuel and Reduce Harmful Dust and Gas Emissions into the Atmosphere
No full textUsing numerical methods, studies have been carried out to determine the effect of the introduction of the technology of two-stage combustion of high-ash Karaganda coal on the main characteristics of heat and mass transfer processes in the furnace of the BKZ-75 boiler at Shakhtinskaya TPP (Kazakhstan). Various regimes of supplying additional air into the combustion space, the volume of which varied from 0% (traditional basic version) to 30% of the total volume of air required for fuel combustion, have been investigated using 3D computer modeling methods. The performed computational experiments made it possible to obtain the distributions of the total velocity vector, temperature fields, concentration fields of carbon monoxide CO and nitrogen dioxide NO2 over the entire volume of the furnace and at the outlet from it. The introduction of the two-stage combustion technology made it possible to optimize the combustion of high-ash coal, since in this case there is an increase in the temperature in the torch core and a decrease in it at the outlet from the furnace, which has a significant effect on the chemical processes of the formation of combustion products. Based on the results obtained, it can be concluded that an increase in the percentage of air supplied through additional injectors to 18% leads to a decrease in the concentrations of carbon monoxide CO by about 36%, and nitrogen dioxide NO2 by 25% compared to the base case. A further increase in the volume of additional air leads to a deterioration in these indicators. The results obtained will make it possible to optimize the combustion of low-grade fuel in the furnace of the BKZ-75 boiler, increase the efficiency of fuel burnout, reduce harmful emissions into the atmosphere, and introduce a two-stage combustion technology at other coal-fired TPPs
Computational modeling of heat and mass transfer processes in combustion chamber at power plant of Kazakhstan
No full textIn this paper the results obtained by the method of numerical modelling of Ekibastuz coal burning in furnace of Kazakhstan Power Plant. Numerical experiment was carried out on the basis of three-dimensional equations of convective heat and mass transfer, taking into account the heat propagation, heat radiation, chemical reactions and multiphase structure of the medium to predict the influence of different water content in coal on overall furnace operation and formation of combustion products
SIMULATION OF LOW-GRADE COAL COMBUSTION IN REAL CHAMBERS OF ENERGY OBJECTS
No full textThe aim of the work is to create new computer technologies for 3D modelling of heat and mass transfer processes in high-temperature physicochemically reacting environments that will allow to determine the aerodynamics of the flow and heat and mass transfer characteristics of technological processes occurring in the combustion chambers in existing coal-fired thermal power plants of the Republic of Kazakhstan. The novelty of the research lies in the use of the latest information technologies of 3D modelling, which will enable project participants to obtain new data on complex heat and mass transfer processes when burning pulverized coal in real combustion chambers operating in Kazakhstan’s Thermal Power Plants (TPP). A numerical simulation, including thermodynamic, kinetic and threedimensional computer simulation of heat and mass transfer processes when burning low-grade fuel, will allow finding optimal conditions for setting adequate physical, mathematical and chemical models of the technological process of combustion of burning high ash coals. The computer modelling methods proposed for the development are new and technically feasible, since coal-fired power plants all over the world use all types of coal. The developed technologies will allow replacing or eliminating the conduct of expensive and labour-consuming natural experiments on coal-fired power plants
