Faculty of Mechanical Engineering

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VERIFICATION OF METHOD FOR ESTIMATING COMBUSTION EFFICIENCY IN A BUBBLING FB COMBUSTOR
(Vinča Institute of Nuclear Sciences, Belgrade, 2000-11)
Risto V. Filkoski
;
Longin Przybylski
;
Ilija J. Petrovski
The article refers to a mathematical method for estimating the efficiency of the combustion process in bubbling fluidised bed conditions. The calculation procedure used in this work is given elsewhere [1, 2] and, here, it is only briefly described. The objective of the present investigation is to validate the mentioned method when using brown coal as a fuel in a laboratory fluidised bed combustor. Particular attention is devoted to the subject of elutriation of fuel particles out of the combustor, considering the fact that it is one of the most important factors limiting the combustion efficiency and the furnace design as well. The work presented here contains the conditions and some results of experimental research in heat losses resulting from the phenomenon of elutriation of combustible particles [3]. Experiments were carried out in a combustor with an inner diameter of 200 mm and a height of 1200 mm. A numerical testing of the method for estimating the combustion efficiency was accomplished within a bed temperature range from 780 °C to 900 °C and a fluidising velocity from 1.20 to 1.32 m/s. The results achieved were compared with the experimentally obtained data. Besides the appearance of some deviations, it may be stated that the results are reasonable and in line with the expectations.
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Combining Different Fossil Fuel Types Used in Cement Industry with RDF as Alternative Fuel and Analyzing the Environmental and Economic Impact
(City Health Journal, Chj, 2023-03)
Monika Uler-Zefikj
;
Dame Dimitrovski
;
Risto V. Filkoski
In Macedonia, the recycling rate is extremely low, representing only 1% of the total generated waste, leading to large amounts of waste being landfilled. A solution in line with the waste management hierarchy regarding waste disposal is waste recovery represented through energy valorization by utilizing the remaining valuable components of waste. In order to avoid throwing waste into landfills, there is a possibility to use it as an energy source for clinker production. In the paper, the energy potential of different fossil fuels is analyzed and the environmental aspect from pairing fossil fuels with refuse-derived fuel (RDF) in the cement production process. According to the national legal framework, the cement industry is permitted to use different waste types as alternative fuels, including RDF. The considered cement industry can implement alternative fuels in the production process with amounts up to 30,000 - 35,000 tons per year. The calculations regarding CO2 emissions were performed for 5 different scenarios with various shares of alternative fuels in the fuel mix composition, starting with 0%, continuing with 25%, 50%, 75%, and 100%. Also, an economic effect achieved due to the replaced thermal energy source was calculated, expressed as mass saving of fossil fuel and financial saving derived. The performed calculations showed when RDF is used in the fuel mix with 75% the CO2 emission reduction is 2.9% when used with coal, 7.3% when combined with lignite, and around 2% when combusted with petrol coke. Economic benefits are generated from the mass reduction of fossil fuels by their substitution with RDF. The maximal, theoretical substitution rate was 100% RDF where the financial savings from the reduced coal consumption were calculated to be above 12 million euro, from heavy fuel oil (HFO) saved were below 23,5 million euro, from reduced lignite usage were above 37 million, and from petrol coke saved were 15,4 million euro.
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Modelling of a PV system - A case study Kosovo
(IAES, 2023-03)
Blerina Bylykbashi,
;
Risto V. Filkoski
The modeling of a photovoltaic (PV) system used for the needs of the industrial sector is presented in this paper. Its analysis was done analytically using real one-year measurements during the system monitoring period and software-wise using premium PV*SOL software. System generated energy, maximum power point (MPP) voltage, final yield and average generated power are included in the analysis. The highest summer energy produced for real conditions is in July with 2811.86 kWh, the highest MPP voltage also presented in July with a value of 400 V. The final yield with a value of 103.07 kWh/kWp and the highest average power 16.6 kW as well. during the month of July. Where it to let just It can be seen that due to the Mediterranean atmospheric conditions in the place of application of the PV system, during the summer months the parameters are higher than during the winter months.
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Exploring the Potential of Biomass Pyrolysis for Renewable and Sustainable Energy Production: A Comparative Study of Corn Cob, Vine Rod, and Sunflower
(Sustainability, MDPI, 2023-09-11)
Domazetovska Simona
;
Vladimir Strezov
;
Risto V. Filkoski
;
Tao Kan
The paper investigates the potential of biomass pyrolysis as a sustainable and renewable energy solution. The study focuses on three biomass types: corn cob, vine rod, and sunflower, which are abundant agricultural residues with potential for biofuel production. The pyrolytic gas, oil, and char produced during pyrolysis at a heating rate of 10 C/min were analyzed. At the pyrolysis temperature of 500 C, the corn cob showed the smallest final residual mass of 24%, while the vine rod exhibited the largest mass loss of 40%. Gas analysis revealed the concentrations of CO2, CO, H2, and CH4 in the pyrolytic gas, indicating its energy potential. Sunflower presented the largest calorific value of the produced biogas, while corn cob was the lowest. The chemical composition of the bio-oils was determined, with aliphatic acids identified as the dominant compounds, suggestin their potential for biodiesel production. Fourier Transform–Infrared Spectroscopy (FT-IR) analysis of raw biomass and char products demonstrated varying extents of decomposition among the biomass samples. A multicriteria assessment approach was employed to evaluate the differences between the selected three biomass feedstock and determined that sunflower biomass ranked the highest among the three, although the overall difference was small, confirming the suitability of all three biomass samples for pyrolysis conversion to higher-value-added fuels.
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Assessment of thermal processing behaviour of corn cob, vine rod and sunflower
(University of Nis, 2017-10)
Domazetovska Simona
;
Vladimir Strezov
;
Risto V. Filkoski
;
Tao Kan
The efforts to achieve reduction in carbon emission, soaring prices of petroleum and concerns over secured energy supply are the major drivers in the search for alternative renewable energy sources. Typical and abundant biomass residues, such as corn cob, vine rod and sunflower, have potential to produce energy in carbon neutral way when subjected to pyrolysis conversion through biogas, bio-oils and bio-char products. The objective of this work was to assess the thermal behaviour of these three agricultural biomass materials under slow pyrolysis conditions, in order to quantify their energy potential. In that direction, a variety of technological tools were employed in the research. The thermo-gravimetric analyser was used on the raw samples to monitor the mass change and to determine the proximate analysis of the considered biomass samples, which is the basis for estimation of their calorific value. The raw samples and the char products of pyrolysis at 500˚C were analysed using Fourier transform-infrared (FT-IR) spectroscopy. The results indicate change in functional groups between raw and solid char products, which refers to the loss of organics after pyrolysis at 500˚C. The organic compounds contained in the pyrolysis oils at 500˚C were investigated using gas chromatography - mass spectrometry (GC-MS). The obtained data provide important reference information on the opportunities for energy and fuel generation from pyrolysis of the analysed biomass.
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Thermal behaviour of different biomass materials under slow pyrolysis conditions
(Wojciech Budzianowski Consulting Services, 2017-06-19)
Simona Domazetovska
;
Vladimir Strezov
;
Tao Kan
;
Risto V. Filkoski
The use of carbon neutral renewable sources to achieve reduction in carbon emission, soaring prices of petroleum and concerns over secured supply of energy sources are the major drivers in the search for alternative renewable energy sources. Typical and abundant biomass residues, such as corn cob, vine rod and sunflower have potential to produce energy when subjected to pyrolysis conversion through biogas, bio-oils and bio-char products of pyrolysis. The subject of investigation of this work was to determine the thermal behaviour of these three biomass agricultural materials under slow pyrolysis conditions to quantify their energy content. In this work, a variety of technological tools were employed to characterise the pyrolysis of the three samples. The thermo-gravimetric analyser and proximate analyses were used on the raw samples to monitor the mass change and characterise the samples. The organic compounds contained in the pyrolysis oils at 500˚C were investigated using gas chromatography- mass spectrometry (GC-MS). The solid char products of pyrolysis at 500˚C and the raw samples were analysed using Fourier transform-infrared (FT-IR) spectroscopy. The results indicate change in functional groups between raw and solid char products, which refers to the loss of organics after pyrolysis at 500˚C. Тhe composition in the bio-oil was compared of the selected biomass materials. Through proximate analysis, the calorific value was determined. The obtained data will provide important reference information for energy and fuel generation from pyrolysis of the analysed biomass.

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