engleski

Emission and characterization of particulate matter from a 30 MW biomass-fired power plant in China

The utilization of biomass in grate boilers is one source of stationary particulate matter emissions. The emissions and characteristics of particulate matters from a 30 MW biomass-fired power plant equipped with fabric filter were investigated. The boiler is stoker-fired with a water cooled vibration grate with a duration of 210 s vibrations every 13 min. The fine particles were sampled by a Dekati low-pressure impactor and analyzed by a scanning electron microscopy equipped with energy dispersive X- ray spectrometry. PM2.5 and PM10 were collected on the quartz filters to determine the water- soluble ions by ion chromatography, and to determine the organic-carbon (OC) and element- carbon (EC) contents by a thermal-optical method with a carbon analyzer system. Results show that the particle size distribution of PM10 at the inlet of fabric filter from the combustion of blended feedstocks (50% bark, 30% capsicum stalks and 20% straw stalks) is bimodal, while that of dry bark feedstocks (80% bark and 20% straw stalks) is essentially unimodal with negligible PM1.0~10. The combustion of blended fuels generates higher PM1.0 yields than that of dry bark feedstocks. Elemental analysis shows that PM1.0 in all cases mainly consist of potassium, chlorine, and sulfur, while the higher chlorine but lower sulfur contents are observed in PM1.0 from blended fuels compared with that from bark feedstocks. The vibrating operation of grate furnace reduces PM1.0 emission as well as the sulfur content in particulate matter emissions. Ion chromatography results show that SO42- and Cl- are the two most abundant water-soluble anions in particulate matters, while the water- soluble cations are richest in K+ with considerable content of Ca2+, Mg2+, Na+ and NH4+. The contribution of particulate OC/EC in PM2.5/PM10 is in the range of 1~3%, indicating the high combustion efficiencies and the low OC/EC emissions of biomass-fired grate furnaces. The measuring result at the outlet of bag filter shows that the bag filter is efficient to remove the particulate matters from biomass combustion, resulting in an ultra- low PM10 emission of about 2.0 mg/Nm3.

Biomass combustion ; fine particle ; sulfur ; high temperature ; potassium

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