Browsing by Author "Petkov V."

Now showing 1 - 8 of 8
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    Decision making for control of combustion process of pulverized coal
    (2015-01-01) Boshnakov K.; Petkov V.; Nikolov M.
    A method and system for decision making and control (DMC) of combustion process of pulverizing fuel-air mixture in large multiburner furnace is proposed. Due to the lack of necessary information inference measurements are created on the basis on the first principle CFD model of the combustion process and a sequential image processing. Decision making procedure is based on Case Based Reasoning and Rule Based Reasoning which contains some elements of knowledge, acquired via a long time operator experience and off-line simulations on the CFD - model. Combination of off-line and on-line procedures is accepted in to two stage algorithm of DMC which improves the efficiency and safety of combustion process.
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    Diagnosis of metallurgical ladle refractory lining based on non-stationary on-line data processing
    (2013-08-29) Petkov V.; Hadjiski M.; Boshnakov K.; Mihailov E.
    A new method for diagnosis of the remaining thickness of metallurgical ladle refractory lining working in a batch mode is proposed, where directly measured by a thermovision camera data about the amplitude and phase delay of the maximum surface temperature is used. Regression equations are obtained to determine the remaining thickness of the ladle refractory lining depending on the parameters of steady auto oscillations of the maximum surface temperature. It is shown that the data from nonstationary auto oscillations could be used for adaptation of the regression equations, predicting the remaining thickness of the ladle refractory lining in case of a local damage.
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    Image processing for technological diagnostics of metallurgical facilities
    (2012-01-01) Doukovska L.; Petkov V.; Mihailov E.; Vassileva S.
    The paper presents an overview of the image-processing techniques. The set of basic theoretical instruments includes methods of mathematical analysis, linear algebra, probability theory and mathematical statistics, theory of digital processing of one-dimensional and multidimensional signals, wavelet-transforms and theory of information. This paper describes a methodology that aims to detect and diagnose faults, using thermographs approaches for the digital image processing technique.
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    INVESTIGATION OF THE INFLUENCE OF MODIFICATION WITH B, Zr AND Ti ON THE STRUCTURE AND HARDNESS OF CUAL9FE3 ALLOY BRONZE IN THE CAST STATE
    (2025-11-02) Krasteva M.; Petkov V.; Raykov P.
    In view of the changes occurring in the global production plan and the imposition by the business on the market for metal products and parts, there is a tendency to replace basic parts and castings made of cast iron and steel with those made of non-ferrous metals and alloys. Some of the most used metals are copper and aluminium, and their alloys. These alloys are alloyed or modified to produce alloys with better casting, performance and corrosion properties. Aluminium bronzes are of scientific interest because they are of industrial importance at a content of 6-12 % Al with or without the addition of other elements, crystallizing in a narrow temperature range, which determines a good thinness and a high tendency to form concentrated suctions, and alloys with a content of 9-15 % Al, where the mechanical strength and hardness increase with increasing aluminium content, but their ductility and impact toughness decrease. The development aims to increase the hardness, preserve or finesse the structure and change the grain shape of aluminium bronzes by adding a small amount of B, Zr and Ti as modifiers so that the resulting castings and parts of CuAl9Fe3B, CuAl9Fe3Zr and CuAl9Fe3Ti alloys in the cast state possess high technological, corrosion and service properties.
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    INVESTIGATION OF THE INFLUENCE OF Mо, W AND V MODIFICATION ON THE STRUCTURE AND HARDNESS OF IRON-DOPED CuAl9 BRONZE IN THE CAST STATE
    (2025-11-02) Krasteva M.; Petkov V.
    Of the group of tin-free bronzes, the most widespread in foundry production is the use of so-called “aluminium” bronze, or bronze type CuAl9. Double bronzes of this type tend to “self-anneal”, resulting in a coarse-grained cast structure. To suppress this tendency, aluminium bronzes are most alloyed with iron, manganese and nickel, but are also further modified with various modifiers. The aim of this development is to investigate the influence of Mo, W and V modification on the structure and hardness of iron alloyed CuAl9 type in the cast state.
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    Modeling of biomass gasification
    (2014-02-25) Petkov V.; Mihailov E.; Kazakova N.
    Optimal conversion of chemical energy of the biomass or other solid fuel into the desired gas depends on proper configuration, sizing, and choice of gasifier operating conditions. Optimum operating conditions are often derived through trials on the unit or by experiments on pilot plants. Simulation, or mathematical modeling, allows the designer or plant engineer to reasonably optimize the operation or design of the plant. The good mathematical model can: find optimum operating conditions or a design for the gasifier, provide information on extreme operating conditions (high temperature, high pressure) where experiments are difficult to perform, provide information over a much wider range of conditions than those obtained experimentally, better interpret experimental results and analyze abnormal behavior of a gasifier, if that occurs. The equilibrium model is independent of the gasifier design which can make them more suitable for a system study of the most important process parameters. The use of an equilibrium model assumes that the residence time of the reactants in the gasifier is high enough to reach chemical equilibrium. For established biomass ultimate analysis, temperature of gasification air and temperature of produced gas, combining the mass balance equations with the equations for the equilibrium constants and equation of energy balance, the equivalence ratio (ER) and composition of produced gas can be obtained. A mathematical model for investigation of the influence of temperature of the produced gas and temperature of gasification air on the process parameters was developed. It can be used for estimation and design of gasification equipment.
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    Modelling of biomass pyrolysis
    (2015-01-01) Kazakova N.; Petkov V.; Mihailov E.
    Pyrolysis is an essential preliminary step in a gasifier. The first step in modelling the pyrolysis process of biomass is creating a model for the chemical processes taking place. This model should describe the used fuel, the reactions taking place and the products created in the process. The numerous different polymers present in the organic fraction of the fuel are generally divided in three main groups. So, the multistep kinetic model of biomass pyrolysis is based on conventional multistep devolatilization models of the three main biomass components - cellulose, hemicelluloses, and lignin. Numerical simulations have been conducted in order to estimate the influence of the heating rate and the temperature of pyrolysis on the content of the virgin biomass, active biomass, liquid, solid and gaseous phases at any moment.
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    Possibilities for saving energy in ferrous metallurgy: Integration of technological processes
    (2016-01-01) Mihailov E.; Petkov V.; Ivanova M.; Stoyanova B.
    One of the main factors having a significant effect on fuel and energy saving in the production of rolled ferrous metals is matching the operation of the continuous casting machines with that of the re-heating furnaces so called continuous technologies in the form of direct rolling or hot charging. In order to investigate the heat exchange processes, the opportunities for enhancing the energy efficiency and determining the optimal parameters of the flat product production process in ferrous metallurgy, some mathematical models of metal solidification and cooling in a continuous steel casting machine were determined as well as a mathematical model of metal heating in the re-heating furnaces. For efficient implementation of such technologies one common algorithm was built on the basis of the individual mathematical models, representing the continuous casting - rolling mill complex control technology, dynamically matching the operation of the individual units to the actual production conditions in on-line mode. The developed algorithm can be used as part of a system for analyzing the thermal condition of the blocks at any single moment for the purpose of optimization of the units' operation within the whole technological process. As a conclusion, considering the original developed algorithm, a 21-51% energy saving was noticed.