Eksperimentalno određivanje permeabilnosti baliranog sojinog ostatka

Abstract

Biomasa kao najznačajniji obnovljivi izvor energije kod nas, ima značajne prednosti sa aspekta očuvanja životne sredine, jer se njenim korišćenjem ne povećava koncentracija ugljendioksida u atmosferi, što se u potpunosti uklapa u tendencije zemalja potpisnica Kjoto sporazuma, među kojima je i Republika Srbija. U skladu s tim, grupa saradnika Laboratorije za termotehniku i energetiku Instituta za nuklearne nauke 'Vinča', niz godina unazad značajno radi na promovisanju korišćenja otpadne poljoprivredne biomase, što je finalizovano razvojem kotla snage 1,5 MW za sagorevanje baliranog sojinog ostatka za potrebe grejanja 1 hektara plastenika u okviru Poljoprivrednog kombinata Beograd. Za potrebe definisanja termofizičkih karakteristika goriva (bali- ranog sojinog ostatka) koje su od posebnog značaja za sveobuhvatnije sagledavanje i predviđanje procesa sagorevanja, u ovom radu je prikazano eksperimentalno određivanje koeficijenata permeabilnosti. Koeficijenti su određivani tako da odgovaraju viskoznim i inercionim članovima uopštene Forhajmerove jednačine. Eksperimentalnim istraživanjima je obuhvaćen uticaj poroznosti na permeabilnost, a kao rezultat analize eksperimentalnih podataka, definisane su i funkcionalne zavisnosti pomenutih koeficijenata od poroznosti. Pored toga, u radu je razmatran i uticaj vlažnosti biomase na permeabilnost, kao i funkcionalna zavisnost vlažnosti i poroznosti. Određivanje parametara permeabilnosti, kao i njihove zavisnosti od uticajnih faktora (poroznost i vlažnost), polazne su osnove u daljem istraživanju kinetike procesa sagorevanja u realnim uslovima, što je veoma značajno pri definisanju geometrijskih karakteristika ložišta.

Biomass as the most important renewable energy source in our country has also significant advantages from the aspect of environment protection. The later is because its use does not increase the concentration of carbon dioxide in the atmosphere, what is completely in accordance with the tendencies of the signatory countries of the Kyoto Agreement, including the Republic of Serbia. Accordingly, a group of associates of the Laboratory for Thermal Engineering and Energy of the Vinča Institute of Nuclear Sciences, Belgrade, a large number of years has invested huge efforts into promoting the use of agricultural waste biomass. These efforts finished with the development of 1.5 MW power boiler combustion balled soybean residue for 1 ha heating greenhouses in the Agricultural complex Belgrade. For purposes of defining the thermophysical properties of fuel (balled soybean residue), which are of great importance for the comprehensive understanding and prediction of the combustion process, this work has been shown experimental determination of the permeability coefficients in Forchheimer's equation which presents the pressure drop through porous media. Coefficients were determined to match the viscous and inertia terms of the general Forchheimer's equation. Experimental research include influence of porosity on permeability analysis, and accordingly, the semi-empirical dependence of these coefficients of porosity has been given. In addition, the paper also has discussed the influence of humidity on the permeability of biomass, and the dependence on moisture and porosity, as well. The determination of permeability parameters, and their dependence of the relevant factors (porosity and humidity), is the starting base for the further study of the combustion process kinetics under real conditions, what is very important for the defining combustion chamber construction features.