A pressurized drop-tube furnace for coal reactivity studies

The design and characterization of a pressurized drop-tube furnace for investigation of coal devolatilization, gasification, and combustion are presented. The furnace is designed for high-temperature, isothermal operation in a developing laminar flow regime. It can be operated at pressures up to 1600 kPa, and temperatures up to 1673 K, with variable reaction time, particle feeding rate, and with inert and various oxidizing atmospheres. Particle residence times can be varied between ∼0.02 and ∼10 s depending upon operating conditions and positions of injection and sampling probes. Observations ports are available for sample collections and for optical investigation of the reactions or temperature measurements. Characterization of gas temperature in the furnace shows that, although the gas temperature profile in the furnace is affected by the water-cooled injection probe, the furnace is able to achieve isothermal operation in a developing laminar flow regime. Results from a series of brown coal devolatilization tests demonstrated the suitability of the furnace for experiments in coal research.