“…In this respect, reaction modelling is a challenging task, because of the difficulty of identifying and quantifying heavier products, and the lack of thermophysical properties for a variety of feedstocks, chars, and tars. In addition, the quantity and the nature of tars vary according to several factors such as reactor temperature and pressure (Shafizadeh, 1982;Evans and Milne, 1987), the nature and ratio of oxidising gases (Kinoshita et al, 1994), the nature of biomass feedstocks (Fagbemi et al, 2001) especially the catalytic effect of their inorganic content (Shafizadeh, 1982), and even the types of gasifiers (Buekens and Schoeters;1985). These issues have an impact on choices between design alternatives that affect the overall efficiency of process design.…”