Intensity of the Process Gas Emission from the Thermal Treatment of the 60–340 mm MSW Fraction under Steam

Abstract

Gasification under steam excess of the residual from mechanical treatment of municipal solid waste (RMT-MSW, refuse derived fuel (RDF)-type) was investigated in a laboratory batch reactor, equipped with a section for high-temperature gas equilibration. Experiments were performed with recirculation of the condensate and residual tars/oils, for closing of the process loop. Gas emissions were registered at 300–500 °C (pyrolysis; maximum at 390 °C) and 650–800 °C (gasification; maximum at 740 °C). Peak areas, equivalent to the gas volume, were in a general proportion of 55:45. Mass of tars and oils collected together with condensing steam was only equal to 0.15% of the average weight loss of the RMT-MSW. Ninety-seven percent of organic compounds, mainly naphthalene, phenanthrene and derivatives, was separable by a simple filtration. Concentration of metals in aqueous condensate was equal to 135 mg/dm3, 98.5% by mass was potassium and sodium ions. Concentration of NH4+ was equal to 2.49 g/dm3 (mostly carbonate). According to the thermodynamic evaluation, volume of the process gas was equal to 2.11 m3 (dry, 25 °C, 1 bar) per 1 kg of the dry waste. Standard enthalpy of the gas combustion was 24.6 MJ/kg of the dry waste; approximately 16% of this energy was due to endothermicity of the process.