Environmental aspects of converting municipal solid waste into energy as part of composite fuels

The paper outlines the results of the experimental research into the ignition and combustion of composite liquid fuel with fine-grained particles of municipal solid wastes (MSW) added as a solid fuel component: wood, rubber, plastic, and cardboard. A relatively low concentration (about 10 wt%) of these components in the fuel intensifies the ignition process, given that all other conditions are the same. The experimental research has been performed using two experimental setups. The first setup allows for researching the conditions of radiant heating of motionless fuel droplets (about 1 mm in size) in a muffle furnace when the temperature is in the range of 400-1000 degrees C. The second setup allows for implementing the conditions of convective heating of motionless fuel droplets (about 1 mm in size) in the flow of pre-heated air (at the rate of 3 m/s and the temperature in the range of 400-700 degrees C). The research findings include minimum temperatures required for the stable ignition of composite liquid fuel with added MSW. They also include the dependencies of ignition delay times on the temperature under different heating conditions. It has also been determined that fuels with MSW are notable for lower nitrogen oxide and sulfur oxide concentrations in gaseous combustion products as compared to fuels without municipal wastes. Maximum difference in the concentrations of NOx and SOx for such fuels reaches 70% and 45% (in absolute units, 125 ppm and 50 ppm, respectively). The results of analytical calculations of relative fuel performance coefficients provide good reasons for the prospective use of such compositions in thermal power engineering. These relative coefficients took values in the range of 1-3. The results obtained provide ground for developing a disposal technology for MSW that cannot be processed or recycled. The technology must be power-efficient as well as economically efficient and environmentally friendly. (C) 2018 Elsevier Ltd. All rights reserved.