Design and performance of a laboratory scale pressurized oxy-coal reactor

Abstract

A pressurized oxy-coal (POC) reactor has been designed, built and tested to investigate key technologies related to oxy-coal combustion including a dry coal feed system, an oxy-coal burner, and a slagging ash management system. The coal feed system utilized a fluidized bed to convey pulverized coal with CO2 from a coal bed into the reactor. The reactor has diagnostic capabilities including optical access, embedded thermocouples, fuel and gas flow rates, exhaust gas analysis (CO2, CO, NO, O2) and heat flux. At 13.6 atm and a firing rate of 89 kWth a mean feed rate of 12.5 kg/h was established with large fluctuations of approximately ±2 kg/h. After polishing the fluid bed walls and removing accumulated large particles on the fluid bed screen, a coal feed rate of 7 kg/h ± 0.5 kg/h was demonstrated. The measured wall temperature profiles, heat flux, and exhaust gas concentrations enabled evaluation of the burner characteristics. The burner produced a long flame as designed but increased mixing is required to improve burnout. Flowing slag was obtained as designed when the reactor remained at the required firing rate and stoichiometric ratio to keep the walls above the slagging temperature.