Impact of water washing precipitator dust on the particulate composition and dioxins in sintering flue gas
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摘要: 為研究除塵灰配入燒結對煙氣顆粒物組成和二噁英的影響,利用水洗方式對燒結除塵灰進行除雜改性,然后采用燒結杯測定改性前后配入對燒結礦性能的影響,并通過撞擊式顆粒物采樣器和二噁英采樣器對煙氣污染物進行采樣分析,研究改性前后配入燒結對顆粒物組成堿金屬和重金屬含量以及煙氣二噁英和前驅體物質排放量的影響.結果表明:燒結除塵灰中的K和Cl在水洗除雜改性過程中被有效去除,除雜后的除塵灰配加燒結有助于改善燒結礦粒度組成、減少煙氣顆粒物和二噁英排放濃度;K組成在燒結顆粒物排放中占有較高比例,遠高于金屬Na、Pb和Zn的含量,且在粒度較細的細顆粒物中占比更高,水洗除雜后配入燒結可顯著降低燒結配料中的K組成,使得煙氣排放的K組成顯著降低,進一步降低顆粒物的排放濃度,其中又以1.10~2.10 μm粒度范圍的顆粒物和K組成的減排比例最高;燒結原料Cl組成和燒結過程中的有機前驅體氯苯、多氯聯苯是煙氣二噁英生成的重要誘因,除塵灰水洗在降低Cl組成的同時也顯著降低煙氣前驅體多氯聯苯排放量達40%,有利于降低煙氣中二噁英的排放濃度.Abstract: Sintering is an important process for the smelting of iron and steel for ironmaking in a blast furnace. However, the sintering process emits air pollutants in the sintering flue gas, especially fine particles and dioxins. In order to study the effects of sintering with precipitator dust on the composition of particulate matter and dioxins in the sintering flue gas, the precipitator dust was purified by a water washing method. The influence of sintering with the precipitator dust before and after the purifying modification was determined by a sintering cup experiment. The flue gas pollutants were then collected by the impact particle sampler and dioxin sampler and the alkali content, heavy metal content and dioxin precursor emissions were determined. The experimental results indicate that potassium (K) and chlorine (Cl) in the precipitator dust are effectively removed by the water washing method. The sintering with the purifying modification and precipitator dust improve the particle size distribution of the sinter and reduce the concentration of particulates and dioxins that are emitted in the flue gas. The K content is higher in the sintered particles, especially the smaller ones, compared to sodium (Na), lead (Pb), and zinc (Zn). Sintering with the precipitator dust after washing significantly reduces the K content of the sinter burden proportion and causes the notable reduction of K in the flue gas particles, particularly in the particle size range of 1.10-2.10 μm. The Cl in the sintering raw material, along with the chlorobenzene and polychlorinated biphenyls that are generated in the sintering process, cause the generation of the dioxins. The sintering with the precipitator dust after washing effectively reduces the content of Cl. The emission of polychlorinated biphenyls is also reduced to 40%, which is beneficial in reducing the concentration of dioxins.
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Key words:
- particulate matter /
- dioxins /
- precipitator dust /
- sintering flue gas /
- alkali metal /
- mechanism
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參考文獻
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