At the beginning of the experiment, the empty bed was preheated to 600 C using a propane torch. Later the torch was turned off and biomass samples were gradually added to the gasifier when the fuel bed height reached 22 cm above the grate. Afterward, the fuel port was closed and air was sent into this system at the desire rate. As fuel gasified in the reactor chamber, negative pressure was maintained inside the chamber by using a vacuum fan to exhaust the gases from the gasifier. The gas was first passed over water-gas heat exchanger which is installed on the top of the gasifier in order to lower the gas temperature and then exhausted to the ambient. It took approximately 60 min for experiments to reach steady state,
this being when Tpeak varied less than 10 C over the 15 min period
and the location of the Tpeak remained in the same place.