In this work, the PM 2.5 emission characteristics, the comparison of the morphological characteristics, and the sizeclassified 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.

In this research, the emission characteristics, morphological characteristics and size-classified elemental compositions of PM 2.5 are determined experimentally before and after a fabric filter (FF) at an industrial pulverized coal boiler. Sampling and measurement of PM 2.5 in situ were taken with an ELPI with a two-stage dilution sampling system. The morphological characteristics were analyzed by scanning electron microscopy. The size-classified elemental compositions were analyzed by energy-dispersive X-ray analysis and inductively coupled plasma−atomic emission spectrometry. The number size distribution of PM 2.5 before the FF displays a unimodal distribution. The mass distribution of PM 2.5 before the FF displays a unimodal distribution with the peak near 0.1 μm, but the mass distribution of PM 2.5 after the FF shows no peak. The pulse back blowing of the FF exerts significant influence on PM 2.5 number and mass concentrations after the FF, especially on the number and mass concentrations of PM 0.007−0.029 . There appears a penetration window in nearly 0.1−1 μm; however, the removal efficiency of PM 0.007−0.029 is lowest. The pulse back blowing of the FF can reduce the removal efficiency of PM 0.007−0.029 from 99.37% to 97.80%. The microstructures of super-micrometer and sub-micrometer particles are different before and after the FF; however, the ultrafine particles in 0.007−0.029 μm are nearly the same before and after the FF. The fractional mass distributions of silicon, aluminum, iron, calcium, and magnesium vary little with variation of the particle size. Cadmium, arsenic, and selenium are enriched with the particle size decreasing.

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