8.5 MWTH CHP PLANT IN OBERWART, AUSTRIA – BASED ON DFB STEAM GASIFICATION OF SOLID BIOMASS – ACHIEVES CONTINUOUS FULL LOAD OPERATION THROUGH STRINGENT OPTIMIZATION

摘要

In times of heavily fluctuating biomass prices for energy conversion/production, it is of utmostimportance to secure and stabilize a continuously high load operation of decentralised CHP plants based on solidbiomass such as wood chips from forestry. The 8.5 MWth CHP plant in Oberwart, based on the DFB steamgasification technology as developed at VUT, struggled to get into continuous full load operation with 2.7 MWel and1.5 MWth output for the past two years. This was partly attributed to the poor downstream equipment installedpreviously and partly due to the enduring very high biomass water content (> 35 wt-%) entering the gasifier. Duringan intense optimization phase lasting over one and a half years, gas velocities in the product gas cooling section havebeen reduced significantly; an additional heat exchanger in the flue gas cooling section was installed to ensure asufficiently low entry-temperature into the flue gas bag filter and to increase heat output efficiency. Furthermore, anewly designed vertical chute dryer, based on a cross-flow belt-dryer concept, was developed and replaced the old,inefficient drying apparatus. Mass- and energy balances have been calculated for the revised plant design includingthe new biomass dryer using IPSEpro. Efficiencies of nearly 32 % (brut) electrical and 66 % (brut) overall are beingachieved. Due to the now continuously high syngas production, ongoing R&D projects concerning further synthesisof the producer gas for hydrogen and BioSNG generation at the plant site in Oberwart, Austria are able to capture thevery latest research and development trends in the bioenergy sector.