Particle size affected the degree to which air was drawn around the particles in the gasification process. The pressure in the gasifier was kept slightly negative compared to atmosphere and a smaller amount of air was exhausted without reacting with char from the gasifier. Generally, more air as sucked out from the larger particles due to large spacing between them. Fig. 6 gives the steady state gasification temperature profile for three different size juniper samples. The gasification temperature increased with the increase of particle size in the combustion zone. This conclusion was confirmed with the theoretical and experimental studies of wood chips in a fixed-bed reactor [21].