Production of Synthesis Gas by Plasma–Steam Gasification of Solid Fuels with Different Ash and Volatile Matter Contents: An Experiment and Thermodynamic Calculations

An experiment was conducted to produce synthesis gas (main components CO and H2) via plasma–steam gasification of brown coal with an ash content of 9% and a volatile matter yield of 48%. Satisfactory agreement between the calculation results and experiments for various types of solid fuel allowed the TERRA thermodynamic calculation program to be verified. A thermodynamic analysis of plasma–steam gasification of shale, brown, and hard coals was performed over a wide range of their characteristics (ash content 3–88%, volatile yield 5–50%) at temperatures from 600 to 3000 K. The composition of the gas and condensed phases of the gasification products, the degree of carbon gasification, and the specific energy consumption for the process were calculated. Although solid fuels differ significantly in ash content and volatile matter yield, synthesis gas is the primary gaseous product of their gasification, with a higher hydrogen concentration than carbon monoxide, thereby improving the environmental performance of solid fuels. In all types of fuels, the maximum synthesis gas concentration occurs between 1200 and 1600 K, with low ballast impurities (H2O, CO2, N2) and zero harmful emissions (NOX, SOX). Synthesis gas combustion heat ranges from 10,475 to 11,570 kJ/m3. A 100% gasification rate occurs at temperatures between 1250 and 1300 K. Energy consumption varies between 0.7 and 2.7 kWh/kg. In solid fuel plasma–steam gasification, the volatile yield reduces specific energy consumption, but the ash content has a negligible effect. Plasma–steam gasification of solid fuels containing 9 and 88% ash and 48% and 50% volatile yield shows a 12% reduction in specific energy consumption. Plasma–steam gasification of solid fuels with volatile yields of 48 and 5% and ash contents of 9% and 3%, respectively, results in a 60% reduction in specific energy consumption.