Reactivity of Biomass, Coal, and Semicoke in Different Heating Conditions

The reactivity and conditions of nonisothermal heating are investigated for biomass, coal, and semicoke (obtained by partial gasification of coal at 700–800°C) are investigated; specifically, the mean reactive index of the fuels is determined. In addition, their reactivity in convective heating by hot air is studied; the delay time in ignition is determined. Nonisothermal heating is accompanied by synchronous thermal analysis in an air flux (heating rate 20°C/min). In convective heating by an air flux (500–800°C, flow rate ~5 m/s), the experimental system includes a muffle furnace with a built in horizontal quartz tube; fuel ignition is recorded by means of a high-speed video camera. In both types of heating, biomass is the most reactive. In convective heating by hot air, the ignition delay is less for semicoke than for coal, on account of the greater surface area of the particles. In nonisothermal heating, the mean reactive index of the semicoke (1.6 min °C^–1) is lower than for the biomass (7.0 min °C^–1) and the coal (4.1 min °C^–1). That indicates lower reactivity in the given heating conditions.