Caracterização físico-química das cinzas residuais do processo de gaseificação de cama de aviário em leito fluidizado

Abstract

The European Union established that all its countries acquire a national energy action plan aiming at that 20% of the total energy consumed from renewable sources, such as biomass, until 2020. The Republic of Ireland where this study was realized has a vast production of poultry that produce as waste called poultry litter. Gasification is a thermochemical process, which involves a breakdown of the fuel molecules consumed, producing fuel gas, volatiles, coal and ash. In this report, the mineral composition of waste ash from poultry litter gasification fluidized bed process was characterized using chemical fractionation analysis to provide parameters that allow the understanding of formation, deposition and agglomeration mechanisms in the gasification process. Firstly, moisture and ash analyses were performed for the poultry litter sample and for the cyclone ashes and bed ash samples, all of which subsequently underwent chemical fractionation. The physic-chemical characterization of the aviary bed showed a moisture content of approximately 19% and ash of 26%, which is a high ash content when compared to other biomasses. In the chemical fractionation of the poultry litter, the major elements identified by atomic absorption with flame atomization were Na, K and Mg, which originated mainly from the birds diet, as well as heavy metals such as Cd, Cr, Cu, Ni and Zn identified in small quantities. For the fractionation of the cyclone ashes collected on different days, there was similarity in the composition of the ashes for most of the elements. The first phase of the fractionation was solubilized in the active phase, the elements K and P being considered more reactive under gasification conditions and consequently, having more relevance for the formation of deposits and / or agglomerations. For the chemical fractionation of the differentiated bed ashes by process temperature, it was observed that for all the major elements, K, P, Mg and Ca, there was a decrease of the concentration with the temperature increase, and the elements extracted in the active phase followed the same pattern as for cyclone ashes.