Life cycle assessment of clinker production using refuse-derived fuel: A case study using refuse-derived fuel from Tehran municipal solid waste: Reducing emissions and conserving fossil fuel in cement making and making beneficial use of solid waste

摘要

One of the techniques used to dispose of 4,000 tons per day (TPD) of non-recyclable waste from Tehran is to burn it as an alternative fuel in cement kilns. This practice reduces emissions from landfills, prevents the loss of waste energy, and conserves fossil fuel resources. The aim of our study was to conduct a life cycle assessment (LCA) of clinker production in cement kilns using a combination of natural gas, mazut, a form of heavy, low-quality fuel oil, and refuse-derived fuel (RDF) from Tehran. We used SimaPro 7.1 software to perform an LCA of 1 kilogram (kg) of clinker produced using the following fuel combinations: the first scenario involved natural gas consumption alone, the second scenario involved a combination of natural gas and mazut, with the mazut providing 5% to 30% of the heating value needed to produce cement clinker in the kiln, and the third scenario involved a combination of natural gas and RDF (providing 5% to 30% of the heating needed in the kiln). The impact categories in the LCA of global warming, eutrophication, and acidification were assessed by the Center of Environmental Science of Leiden University (Centrum voor Milieukunde Leiden-CML) CML 2000 method. The results indicated that the third scenario, involving natural gas and RDF, reduced acidification by 2.14-11.5% and global warming by 0-1.3% relative to the first scenario involving the use of only natural gas. In addition, we observed a 0.65-3.81% reduction in acidification and a 0.9-3.8% reduction in global warming under the third scenario compared with the second scenario (co-firing of natural gas and mazut). The amount of nitrogen oxides (NO_X) emitted from the combustion of the Tehran RDF was greater than that was emitted when burning mazut. Therefore, reduction of nitrogen from the RDF composition is necessary. This study indicates that the use of Tehran RDF (with reduced nitrogen) in Tehran cement kilns does not increase cement kiln NO_X, sulfur dioxide (SO_2), and carbon dioxide (CO_2) emissions; however, we need to conduct additional investigation into the chemical composition of the Tehran waste before using solid waste in place of fossil fuels.