Steam gasification of powder river basin coal: surface reaction kinetics and intraparticle mass transfer restrictions

Abstract

Steam gasification kinetics studies were conducted in a modified drop tube fixed bed reactor to approximate the injection of ambient temperature coal into a fluidized bed gasifier. Product gases were measured using a customized rapid response gas analysis system with a quadrupole mass spectrometer. Experiments were done within Regime I temperature range (no mass transfer restrictions), and effects of temperature and pressure on surface chemical reaction were analyzed using three different particle size ranges. The random pore model closely fits the experimental results and the fitting parameters are listed. Char characterizations are presented, including surface area measurements and scanning electron microscope images. Mass transfer resistances were analyzed by comparing experimental and theoretically predicted effectiveness factors using the Thiele modulus, based on particle sizes, temperature, total pressure, and steam partial pressure.