Smoldering characteristics of high bulk density peat

Abstract Low-density peats from many countries have long been studied by many authors. They are mostly forest and moss peats. Different peat types, from different locations in the world, may present degradation behavior that differs significantly. Bulk density, which is one the most important physical parameters governing the smoldering dynamics of solid fuels, varies among countries’ peatlands. This work compares experimental data for low (200 kg m−3) and high (450 kg m−3) bulk density peat smoldering in a test bench. Peat samples with different densities, organic matter contents, and particle sizes were considered in this work. The physicochemical characterization included ultimate analysis, ash composition, the density of the solid, and thermogravimetric and differential thermogravimetric analysis. The influences of the organic matter content, as well as the bulk surface area to volume ratio on peat burning, are also discussed. It is showed that, for the same organic matter and bulk surface area to volume ratio, the high bulk density peat burning rate is as low as one-third of the low bulk density peat burning rate. Once the High Heating Value of both peats is found similar, this lower burning rate is related to chemical kinetics, which shows higher oxidation temperature, around 500 °C for the high bulk density peat, and 300 °C for the low bulk density peat. For the high bulk density peat, the higher the bulk surface area to volume ratio the higher both horizontal and vertical smoldering spread rates.