4. Conclusions
One and the same reactor can be utilized for a variety of fuels in pellet form, but at varying air–fuel ratios, temperature levels, gas compositions and lower heating values. Themassconsumptionrateinagasifierwithacertaingeometry seems to be a function of pellet geometry and not of the chem- ical composition, with similar rate for all pellets of same size, but smaller rate for one size larger pellet of same material. Similarly, the equivalenceratioseems to be in the sameorder of magnitude for the same size pellets in the same reactor geom- etry, but higher for the one size larger pellets. This result may rather an effect of the bed characteristics and flow conditions. The water gas shift reaction seems to relatively well approxi- mate gas composition modelling but needs to be accompanied with a proper prediction of the temperature evolution for a cer- tain fuel during gasification, which in turn depends on the fuel reactivity. Forgasificationofpelletsinthestudiedloadintervalthereseem to be an almost linear relation between air–fuel ratio and cold- gas efficiency: The higher the air–fuel ratio, the higher is the efficiency. All pellet sorts show similar shrinking characteristics on indi- vidual pellets, however, different bed dynamics. Higher reactive pellets create denser char beds. The char bed porosity is the dominating factor in pressure drop estimation. The amount of dust collected in respective char bed did not affect negatively on the pressure drop.