24 Bioenergy International PS1 2015 "NBUUFSPGFGGJDJFOU QBSUJDVMBUFSFNPWBM With increasingly tougher restrictions on industrial air emissions, pellet manufacturers are looking to “future-proof” particulate matter (PM) compliance, cost effectively. One Portuguese producer, Glowood Indústria S.A., has recently installed a brand new type of mechanical cyclone. The most recent results show a remarkable reduction of its PM emissions, from 700mg/Nm3 to under 15mg/Nm3. PELLETS LOCATED IN CERCAL Do Alentejo near the Port of Sines in southern Portugal, Glowood Indústria S.A. is a 100 000 tonne-per-annum pellet plant. Commissioned in 2012, the 10 million Euro facility uses pine sawdust from sawmills as well as eucalyptus and pine roundwood. Production is 100 percent geared towards export. Like many pellet producers Glowood uses a biomass boiler with the exhaust stream heating a rotary dryer to dry the incoming feedstock. The material is dried and carried over via dryer cyclones to the next stage in the pelleting process. In addition to separating wet wood particles from the dryer, a much smaller amount of fly ash from the biomass combustion is captured in these cyclones. Conventional limitations The total concentration of wood dust and ash entering dryer cyclones from a rotary dryer is typically in the 200- 300g/Nm3 range. Whilst dryer cyclones are capable of capturing the larger particles to a high degree (>99%), particulate matter (PM) emissions exiting dryer cyclones are still around 200-350mg/ Nm3 exceeding existing regulatory limits in many countries. As Pedro Ribas Araújo, CEO, Advanced Cyclone Systems has transformed an understanding of particle agglomeration into a business and environmental benefit. restr par tuguese Glowood mo Nm LOCATED IN from and 100 Lik uses stre d clon ting wet muc t Co The and ro 3 Ped stan a result additional end-stage dust removal systems need to be installed if PM emissions are to be brought under 50mg/Nm3, a threshold under discussion for the upcoming EU Medium Combustion Plant (MCP) directive. However conventional end-stage dust removal systems have limitations. Flue-gas tars essentially rule out the use of bag filters, and Dry Electrostatic Precipitators (ESPs) cannot be used because of dust explosion hazards. Energy consumption, corrosion and secondary pollutant issues limit the use of Venturi scrubbers. While able to handle tars and very efficient at PM 10 and 2.5 removal, Wet Electrostatic Precipitators (WESPs) come with high investment costs along with water consumption and wastewater treatment issues. Finally conventional multi-cyclones have a removal efficiency of less than 50 percent. An advanced cyclone system The Glowood plant has a triple-pass
Bioenergy nr 1 - 2015
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