A novel technique for characterizing sintering propensity of low rank fuels for CFBC boilers

Abstract

In CFBC boilers ash sintering may contribute to deposit formation in the cyclone, return leg and post cyclone flue gas channel. In some cases, rapid sintering can lead to heavy agglomerate formation, which may finally inhibit circulation in dense phase areas (such as seal pot). Hence understanding the sintering behavior before the fuel is used, would be desirable for avoiding problems.Particle-to-particle sinter bonding, usually results in shrinkage. The present technique is based on measuring the area shrinkage continuously during heating of ash pellets over a temperature range of interest. The area shrinkage measurement showed clear differences in the sintering profiles among the coal ashes tested.Present work describes the sintering profiles of ashes for the temperature range of 800–1100°C. The finger print of sintering behavior, over the temperature range is made easy using the area shrinkage measurement. The probable mechanism behind the sintering behavior observed in some low rank coals in the temperature range 800–1000°C is proposed. The advantages over the other conventional techniques used for prediction of sintering such as compression strength measurement, electrical conductance are brought out.