掺烧固废燃料的循环流化床锅炉引风机叶片腐蚀原因分析

Analysis on Corrosion Causes of Induced Draft Fan Blade in Circulating Fluidized Bed Boiler With Mixed Burning Solid Waste Fuel

为研究某掺烧固废燃料的2×300 MW循环流化床机组引风机叶片腐蚀严重的原因,对腐蚀区域叶片和不同位置的灰进行了取样分析。X光衍射光谱(X-Ray diffractomer,XRD)、扫描电镜(scanning electron microscope,SEM)、X射线荧光光谱(X-ray fluorescence,XRF)等分析结果表明:在叶片锈样中和叶片表面均发现有Cl元素,未发现S元素,由此确定叶片腐蚀的原因是Cl腐蚀;通过对锅炉不同位置灰样的化验,发现空预器板结灰和半干法脱硫塔后布袋除尘器捕集的脱硫灰出现了Cl元素富集的情况,这是引起设备Cl腐蚀的关键。掺烧的固废燃料和污泥是Cl的主要来源,板结灰中的Cl富集与选择性非催化还原逃逸的NH3有关,而脱硫灰中Cl富集的原因有待进一步研究确定。

In order to study the reasons for serious corrosion problem of induced draft fan blades of a 2×300 MW circulating fluidized bed unit which were blended burning solid waste fuel,the samples of the corroded blade and ash from different positions were taken.The analysis results of X-Ray diffractomer(XRD),scanning electron microscope(SEM)and X-ray fluorescence(XRF)show that Cl element is found in the rust samples and on the surface of the blades,and no trace of S element is found.Therefore,it is determined that the cause of the corrosion of the blades is Cl corrosion.Through the test of ash samples at different positions of the boiler,it is found that the ash hardened on the air preheater and the ash collected by bag filter behind the semi-dry flue gas desulfurization are enriched in Cl,which is the key to cause the Cl corrosion of the equipment.The blended burning solid waste fuel and sludge are the main sources of Cl.The enrichment of Cl in the ash hardened on the air preheater is found related to NH3 escaped from selective non-catalytic reduction,the reason of Cl enrichment in desulfurized ash needs further study.