Pilot-Scale Demonstration of Coal Waste and Torrefied Municipal Solid Mixtures with an Entrained Flow Gasifier

Conversion of waste coals and torrefied municipal solid waste (MSW) mixtures to syngas was demonstrated with a pilot-scale entrained flow gasifier (EFG). Coal waste and coal plus opportunistic fuel mixtures present an alternative feedstock for energy production. Semi-sorted MSW was torrefied at 350 °C using a large-scale torrefaction reactor to generate a coal-like feedstock for blending and feeding with coal waste. Bituminous waste coal mixed with torrefied MSW at weight ratios of 100:0, 75:25, 50:50, 25:75, and 0:100 were gasified in the EFG while H₂, CO, CH₄, CO₂, and H₂S concentrations were continuously measured in the syngas. Emissions defined by the EPA OSWI regulations (CO, NO_x, PM, SO₂, dioxins/furans, HCl, Cd, Pb, and Hg) were also determined. The optimal steam-to-O₂ ratio was determined for each waste coal and MSW blend tested and product yields were quantified, including the ash and slag. Analyses of slag, filter ash, and quench water for the Resource Conservation and Recovery Act trace metals were completed for each feedstock blend along with a toxicity characteristic leaching procedure (TCLP) on the slag and filter ash to verify that trace metals were vitrified in the melted ash stream. Steady-state pilot-scale EFG operation along with syngas and byproduct yield measurements experimentally validated the use of coal waste and MSW in an EFG. Based on the pilot-scale optimization data, a demonstrator-scale (100 kg/h) system was modeled and designed to estimate capital and operating costs, as well as the levelized cost of energy (LCOE) for small, modular gasifier systems.