Hydrogen rich gas production through co-gasification of low rank coal, flotation concentrates and municipal refuse derived fuel

Highlights: • Reactivity R₅₀ and R_max as parameters determining the usability of fuels in gasification. • Hydrogen-rich gas production in co-gasification of low-rank coals with refuse-derived fuel. • Advanced mathematical models to investigate the properties of studied fuels. • Experimental campaign on co-gasification of various fuels to hydrogen-rich gas. In the paper a novel approach to thermochemical utilization of low rank coal, flotation concentrates and municipal refuse derived fuels was presented. The economic attractiveness of low rank coals and flotation concentrates is limited and that is why they are commonly stored at excavation heaps causing additional costs and the risk of endogenous fires occurrence. One of the crucial parameters determining the attractiveness and usability of a fuel in the gasification process is its reactivity. In the study several low rank coals, flotation concentrates and municipal refuse derived fuels were tested in terms of their reactivity in the process of steam gasification. The reactivity of low rank coal and flotation concentrates at 50% of carbon conversion, R₅₀, varied between 1.46·10⁻⁴ and 2.39·10⁻⁴ s⁻¹, whereas the maximum reactivity, R_max, from 3.28·10⁻⁴ to 4.62·10⁻⁴ s⁻¹. Advanced mathematical models were developed to investigate the similarities and dissimilarities between the studied fuels as well as the relationships between the physical and chemical parameters and the reactivities of fuel chars in steam gasification. On this basis, a low rank coal was selected and blended with 20%_w/w of municipal refuse derived fuel in co-gasification experiments. The aim of the research was to utilize the low rank coal characterized by the lowest reactivities (R₅₀ and R_max of 1.46·10⁻⁴ and 3.28·10⁻⁴ s⁻¹, respectively) in steam co-gasification to hydrogen-rich gas with an alternative fuel in a fixed bed reactor at the temperature of 800 °C. The selected low rank coal was blended with 20%_w/w of municipal refuse derived and the resulting fuel yielded the average concentration of hydrogen in the produced gas of 58.99%_vol.