Fine Particle Emission from an Industrial Coal-Fired Circulating Fluidized-Bed Boiler Equipped with a Fabric Filter in China

摘要

In this work, the PM_(2.5) emission characteristics, the comparison of the morphological characteristics, and the size-classified elemental composition of PM_(2.5) are determined experimentally before and after the fabric filter at an industrial circulating fluidized-bed boiler. Measurement in situ was taken with an electrical low-pressure impactor equipped with a two-stage dilution sampling system. The morphological characteristics and size-classified elemental composition were performed by scanning electron microscopy and energy-dispersive X-ray analysis. The size distribution was measured in the range from 0.029 to 2.38 μm. Before and after the fabric filter, the number size distribution displays a bimodal distribution. The fabric filter total removal efficiency of PM_(2.5) without pulse back blowing cleaning is 99.449%, and that with pulse back blowing cleaning can reach 99.029%. The minimum size-classified removal efficiencies appear in the particle size range from 0.1 to 1 μm. In this size range, the fabric filter size-classified removal efficiencies are 99.15-99.59%, and the pulse back blowing cleaning can result in the lowest value of 98.46%. The morphological characteristics before and after the fabric filter are nearly the same, except channels 3-5. Sodium, potassium, and zinc show enrichment with decreasing particle size; calcium and titanium show clear enrichment with increasing particle size; however, silicon, aluminum, magnesium, iron, and manganese show no enrichment with particle size variation.