Evaluation of the hazardous emissions from different types of RDF combustion in low power boilers

Abstract

Content evaluation of the hazardous substance emission from different types of waste combustion in two solid-fuel water heating boilers was carried out. For 100 kW pyrolysis boiler the content in exhaust gases of the following compounds was determined: NO2, NO, CO, CH4, phenol, benzol, SO2, formaldehyde, HCl. For 200 kW stoker grate boiler the content in the exhaust gases of the following compounds was determined: CO, NO2, NH3, mercaptans, H2S, phenol. For the targeted factors, the calculated hazardous substance ground-level concentrations don't exceed the maximum allowable concentration limit. The hazardous substance emissions in low power boilers are comparable with high power analogs but have lower combustible efficiency. Waste combustion in the pyrolysis boilers creates 2-10 times less hazardous substances than in grate firing. It was established that combustion mode influences only the carbon monoxide content. The content of other hazardous compounds in the exhaust gases doesn't depend on the combustion parameters. The additive criterion of total emissions was suggested, which presents the sum of the ratio of the calculated ground-level hazardous substance concentrations to maximum allowable concentrations. Unlike the existing dimensionless concentration, the criterion considers hazard class and compound fraction in gases. The highest criterion value of the total emissions was noted during wood waste combustion (windows, doors, furniture) and RDF fuel, which contains a large amount of plastics.