SCR脱硝副产物硫酸氢铵与空预器中飞灰反应特性

Reaction characteristic of by-product ammonium bisulfate from SCR denitrification and fly ash in air preheater

开展SCR脱硝副产物硫酸氢铵与飞灰反应特性研究,利用MS2000激光粒度仪对不同飞灰样品的粒度特征进行了分析。结果表明,当ABS飞灰质量配比为1∶50时,1~10和10~100μm的粒度范围内飞灰所占体积比都有明显增大。利用SEM对不同飞灰样品的形貌进行了观察与分析,结果表明掺杂ABS后飞灰形貌有明显改变。利用XRD鉴定掺杂ABS前后飞灰的物相,掺杂ABS后,除了原飞灰样中原有的矿物相外,还检测出了Fe2（SO4）3和Na2SO4,由此可见,ABS与飞灰发生了反应。由EDS元素分析结果可知,当掺杂ABS后,O、Al和Si元素仍然是主体元素且含量差别不大,相比原灰样唯一不同的是后两种样品中出现了S元素,且S元素的含量随着掺杂ABS的量的增加而增大。飞灰比电阻测试结果显示,掺杂一定量的ABS会降低飞灰的比电阻,增强了电除尘器捕捉飞灰的能力。XPS分析结果显示,掺杂ABS后,ABS会与飞灰中的Na_2O反应形成Na_2SO_4。

In this paper,we performed characteristics research on the reaction between fly ash and ammonium bisulfate（ ABS）,the SCR denitrification by-product. The granularity characteristics of different fly ash samples were analyzed using the MS2000 laser granulometer. Results show that when the quality ratio of ABS to fly ash is 1 ∶ 50,the fly ash volumetric ratios of particles of size in the range 1—10 and 10—100 microns increase. SEM morphology studies were used to observe and analyze the characteristics of different fly ash samples,the results of which show that the morphology characteristics of fly ash change after they are ABS-doped. XRD diffraction was applied to identify the mineral phases of ABS-doped fly ash samples. In ABS-doped samples,Fe_2（ SO_4）_3and Na_2SO_4 were detected in addition to the mineral phases in the original fly ash samples; thus,it confirms that ABS had reacted with fly ash. EDS analysis shows that O,Al,and Si remain the main elements in ABS-doped samples and there is little difference between the species contents. The only difference compared to the original fly ash samples is that S appears in the other two samples,and the S content increases with increasing amount of ABS-doping. Specific resistance studies reveal that ABS-doping reduces the resistivity of fly ash and enhances the ability of an electrical precipitator to capture fly ash. XPS analysis shows that Na_2O in the fly ash reacts with ABS to form Na_2SO_4 in the ABS-doped samples.