Aleksandar Eric

Development of a Boiler for Small Straw Bales Combustion

In terms of sustainable energy development in Serbia, as well as in the whole world, there is a growing need for using the alternative energy sources. Alternative energy sources are, in most cases, renewable: biomass, wind power, solar energy, hydro-power and geothermal energy. A need for the utilization of this kind of energy sources is dictated by the market, on one side, as well as by environmental protection, on the other. Prices of fossil fuels grow proportionally to the decreasing of fossil fuel reserves. Since available reserves of fossil fuels in Serbia, especially those of high quality, are relatively limited, this problem becomes even more emphasized. On the other hand, it is necessary to harmonize the energy production legislation and practice in Serbia with the directives of the European Union, in the sense of intensifying the utilization of renewable energy sources and thus reducing pollution and greenhouse effect formation. Biomass is one of key renewable energy sources (van Dam et al., 2007). This is the reason for the development of cheap thermal devices (boilers and furnaces) burning biomass from agricultural production, as quite available and cheap energy source. These devices could be used primarily in villages, small towns and small businesses processing agricultural goods (greenhouses, dairy farms, slaughterhouses, etc.). The devices could also find use heating schools, hospitals and other institutions. Boilers and furnaces should utilize baled biomass which has not been adequately used and should have complete combustion control. The most favorable combustion organization for this type of devices is based on the principles of burning of a cigarette. The development of these devices should be simultaneous with the solving of the problem of low ash melting temperature and damaging of boiler metal parts and walls. At the same time, environmental aspect of combustion should be kept in mind.

Development of the Technology for Combustion of Large Bales Using Local Biomass

In terms of sustainable energy development in Serbia, as well as in the whole world, there is a growing need for using the alternative energy sources. Alternative energy sources are, in most cases, renewable: biomass, wind power, solar energy, hydro-power and geothermal energy. A need for the utilization of this kind of energy sources is dictated by the market, on one side, as well as by environmental protection, on the other. Prices of fossil fuels grow proportionally to the decreasing of fossil fuel reserves. Since available reserves of fossil fuels in Serbia, especially those of high quality, are relatively limited, this problem becomes even more emphasized [1-3]. On the other hand, it is necessary to harmonize the energy produc‐ tion legislation and practice in Serbia with the directives of the European Union, in the sense of intensifying the utilization of renewable energy sources and thus reducing pollution and greenhouse effect formation.

Fluidized combustion chamber CFD simulation based on Euler-Euler granular flow model

U radu je predložen dvodimenzijski model numeričke simulacije sagorevanja tečnih goriva u fluidizovanom sloju, koji se zasniva na dvo fluidnom Euler – Euler pristupom modeliranja fluidizovanog sloja uz određivanje polja brzina gasa i čestica u dvofaznim, granularnim tokovima zasnovane na analogiji sa kinetičkom teorijom gasova (KTGF). Sveobuhvatan model kompleksnih procesa u fluidizacionoj komori sagorevanja podrazumeva, pored određivanja polja brzina gasne i čestične faze, inkorporiranje energetskih jednačina gasne i čestične faze, kao i transportnih jednačina hemijskih komponenti sa izvornim članovima usled konverzije komponenata. Brojni numerički eksperimenti pokazuju da je izbor koeficijenata u izrazima za sile trenja prilikom interakcije faza ima izuzetan značaj i mora se sprovesti za svaki, značajno različit režim fluidizacije, posebno. Urađene su serije numeričkih eksperimenata sa simulacijom procesa sagorevanja u FS sa i bez značajnog sadržaja vode u gorivu. Proračuni su nestacionarni, a modelirani vremenski period odgovara vremenu za koje gas prođe kroz celu visinu reaktora. Numerički eksperimenti, na osnovu predloženog matematičkog modela, su takođe korišćeni za potrebe analize uticaja različitih snaga pri kojima radi reaktor, kao i različitih stepena fluidizacije, na efikasnost sagorevanja kao i na profile temperatura u zoni sagorevanja. Ključne reči: CFD modeliranje; sagorevanje; fluidizovani sloj, granularni tok, tečna goriva, A comprehensive 2D numerical model of the bubbled fluidized bed with combustion of liquid fuels is proposed in the paper. The proposed numerical model is based on the Eulerian–Eulerian granular flow modeling with the kinetic theory of granular flow. The model includes the following basic governing equations: the continuity equations of the solid and gas phase, the momentum conservation equations of the gas and solid phase, the energy equations of gas, and the solid phase and conservation equations for chemical components. The choice of the semi empirical constants of the inter-phase interaction drag force model is significant and these constants must be adjusted for each particular regime of fluidization. Presented numerical experiments primarily were applied to verification of the assumptions about the impact of water content in a liquid fuel on FB combustion intensity. The numerical experiments, based on the proposed mathematical model, also have been used for the purposes of analyzing the impacts of various reactor powers as well as fluidization numbers, on the combustion efficiency and on combustion zone temperature fields.

Results of combustion of different waste fuel in fluidized bad

The sustainable development of the national energy sector implies the rational use of energy resources, use of RES, and waste management with satisfying environmental regulations. A way to simultaneously fulfill the above objectives is the utilization of low-calorific and waste materials, applying the technology of fluidized bed combustion (FBC). This paper presents experimental results of combustion of number of solid and liquid wastes, conducted on two installations: industrial demonstration (capacity up to 100 kW) and experimental FB boiler (capacity up to 500 kW). The furnace temperature distribution, the composition of flue gas at the exit of furnace, and the other combustion parameters of the fuels are given. On the basis of these results, an evaluation of the waste fuels FB combustion and possibility of utilization of their energy potential is given.