• Hla, San

Abstract

Woody waste streams (e.g. timber mill residue, urban green waste) represent a largely-untapped renewable energy resource; those that are utilised are usually combusted for power generation at a range of scales and efficiencies. Gasification-based systems offer flexibility in scale, feedstock, and application, and can be used to broaden the base of waste utilisation in Australia. Sub-tropical and tropical municipalities in Australia face considerable challenges with the volume of green waste requiring management, with much of it not being reused as compost due to the disparity between supply and demand. Energy contents of green wastes are as high as wood wastes (on a dry basis) as they primarily consist of garden waste mainly prunings, palm fronds, grass clippings and branches. Their use as an energy feedstock, however, remains limited.CSIRO operates a research scale biomass gasifier, designed to convert solid biomass fuels into useful synthesis gas, which can be further integrated in our research gas processing and power generation facilities.This paper presents the results of recent investigations using this gasifier, whereby it was used to gasify woody biomass to investigate the effects of air ratios and staging on gasifier performance. Effects of moisture content on the performance of gasification process were also explored. The results showed that an optimum equivalence ratio was found to be about 0.34 yielding the cold gas efficiencies of biomass gasifier approximately 70%. Under this optimum operating condition, the lower heating value (LHV) of syngas produced was found to be 4.3 MJ/Nm³ and, the peak temperature of combustion zone was observed as high as 1050°C high enough to crack the tars inside gasifier. These data are important to the assessment of feasibility and economics of different waste-to-energy concepts.

Topics

• crack
• combustion
• wood
• gasification