Ingeniería e Investigación (May 2009)
Thermogravimetric characteristics of char obtained at high heat rate
Abstract
Coal reactivity during combustion is determined by the thermogravimetric characteristics of char. The thermogravimetric charac- teristics of chars obtained in a drop-tube furnace were studied in this work. Chars from the devolatilisation of three bituminous coals were obtained at three times (100, 150 and 300 ms), three temperatures (900, 1,000 and 1,100°C) and at high heat rate (104 K/s). The chars were burned using non-isothermal thermogravimetry (heated to 900°C) and isothermal thermogravimetry at700°C, 800°C and 900°C to obtain their combustion profiles. Characteristic temperatures (ignition, peak and final tempe- ratures) were determined by non-isothermal thermogravimetry; it was found that chars from La Yolanda coal gave the highest figures for the characteristic temperatures. Isothermal thermogravimetry revealed that the combustion rate for the three coals decreased with increased devolatilisation time and combustion temperature.
