循环流化床超细石灰石炉内脱硫研究
The In-situ Desulfurization With Ultra-fine Limestone for Circulating Fluidized Bed Boilers
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摘要: 分析了石灰石粒径对循环流化床（circulating fluidized bed,CFB）锅炉炉内脱硫效率的影响,并且在中试规模和工业规模的CFB锅炉上,研究了超细石灰石的炉内脱硫效果。在3MW（th）中试CFB试验台上分别进行了d50=10μm的超细石灰石与d50=310μm的粗石灰石的脱硫实验,结果表明,当细石灰石的钙硫比分别为3.05、3.19和3.30时,脱硫效率可以达到91.5%,95.1%和98.2%;而粗石灰石在钙硫比为3.41时可实现98.3%的脱硫效率;当SO2排放浓度降到约为80mg/m3时,采用粗石灰石脱硫的氮氧化物排放浓度约为细石灰石的两倍。在220t/h CFB锅炉上,采用d50=10μm超细石灰石粉,在钙硫比为1.82条件下,SO2排放浓度可控制在22.6mg/m3,脱硫效率为99.53%。实验结果表明,超细石灰石具有较好的脱硫性能,并且在减少催化NOx生成方面具有一定的优势。Abstract: This paper analyzed the influence of particle size on the in-situ desulfurization in circulating fluidized bed（CFB） boilers, and investigated the effectiveness of the desulfurization technology with ultra-fine limestone particles in a pilot-scale and a commercial-scale CFB boilers. In a 3 MW（th） pilot-scale CFB boiler, desulfurization using the ultra-fine limestone with a 10μm cut size and the coarse limestone with a 310μm cut size was compared. The results showed that the ultra-fine limestone realized 91.5%, 95.1% and 98.2% sulfur removal efficiency with Ca/S molar ratio of 3.05, 3.19 and 3.30, respectively, while the coarse limestone realized 98.3% sulfur removal efficiency with Ca/S molar ratio of 3.41. When SO2 emission concentration was reduced to around 80 mg/m~3, the NOx emission under coarse limestone injection condition was nearly twice higher than that under ultra-fine limestone condition. In the 220 t/h CFB boiler, at Ca/S molar ratio of 1.82, the desulfurization technology with ultra-fine limestone reduced SO2 emission concentration to 22.6 mg/m~3, and realized up to 99.53% sulfur removal efficiency. The ultra-fine limestone shows good sulfur removal performance, and has less catalytic effect on NOx formation.
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