Evaluation of dried compost for energy use via co-combustion with wood

Abstract

There is still a question of utilization of compost of unsatisfactory quality. This article deals with energy utilization of untreated compost. The energy utilization of raw compost as a fuel is not directly possible without further processing. Separation might be necessary due to large amount of mineral content (soils and other inert substances). This article is focused on the analysis of the basic fuel characteristics of compost. Proximate and elemental analyses were performed and stoichiometric combusti on was calculated. Finally, the sample was co - burned with wood biomass in a fixed grate combustion device and the gaseous emissions were determined in dependence on the amount of combustion air supplied. The emissions were expressed in graphs against exces s air coefficient and flue gas temperature. Elemental analysis of the compost sample shows high percentage of ash up to 61.70% wt. on dry basis causing low average calorific value of 8.51 MJ kg - 1 on dry basis. For combustion tests, the heating value was in creased by addition of wood chips to reach an average calorific value of the mixture to 13.4 MJ kg - 1 . The determined stoichiometric parameters can help in optimization of diffusion controlled combustion of composts or similar materials. In combustion of th e mixture of compost and wood biomass an optimum of emission parameters was found not exceeding the emission limits. Measured emission concentrations show the possibility of optimizing the combustion processes and temperatures while lowering CO emissions v ia the regulation of combustion air.