Preliminary fixed-bed downdraft gasification of birch woodchips

Abstract

This paper investigated the possibilities of using birch wood chips for fixed-bed downdraft gasification. The preliminary air gasification resulted producer gas with an average composition of 11.5 % CO, 5.4 % CO2, 5.9 % H2, 0.38 % CH4 corresponding to a mean lower heating value of about 2 MJ/kg. The approximate size of woodchips used for gasification was around 11.5 mm for a maximum solid throughput of 0.65 kg/h. The obtained equivalence ratio (ratio between actual air fuel ratio and stoichometric air fuel ratio) as a result of air and biomass feed was close to 0.45 which was stable throughout the test. Producer gas left the gasifier at ca. 150 °C and was diverted for flaring owing to the level of low energy content. Despite availability, the option for gas to generate heat and electricity via integrated gas engine has not been utilized in the present case and remained for further ongoing research.