循环流化床锅炉燃用准东煤结渣、沾污分析

Analysis and Study of the Slagging and Contamination of a CFB Boiler Burning Zhundong-originated Coal

在一台因燃用准东煤而严重结渣的循环流化床锅炉内提取结渣灰样,利用XRF和XRD方法分析了灰样的形态和成份。研究表明:分离器出口烟道壁面灰渣内层的Na元素以Na2SO4形式存在,同时又有大量Ca SO4存在,形成Na2SO4-Ca SO4低熔点复合盐体系。Na2SO4-Ca SO4低熔点复合盐被壁面捕捉形成粘性底层,同时由于Fe、Ca协同作用,捕捉的灰中矿物质迅速形成低熔点共熔体,并且固化形成致密的渣层。对于高温再热器管子,由于Na2SO4、Na K3(SO4)2或Na O·Al2O3·2(Si O2)等低熔点化合物以气溶胶形式存在于烟气中,同时吸附烟气中的飞灰颗粒,然后沾结在管子表面形成结渣沾污。

Ash samples were taken from the slagging and contamination locations in a circulating fluidized bed seriously slagged by burning Zhundong-originated coal and the morphology and composition of the ash samples were analyzed by using the XRF and XRD method. It has been found that the Na element in the inner layer of the ash and slag on the wall surface of flue gas ducts at the outlet of the separator exists in the form of Na2SO4 and in the meantime,a great deal of Ca SO4 is present,forming a Na2SO4-Ca SO4 low melting point compound salt system. The low melting point compound salts are captured by wall surfaces to form a viscous base course and at the same time,under a synergistic action of Fe and Ca,the mineral substances captured from ash rapidly turn to be a low melting point eutectoid and are solidified to form a compact slag layer. For tubes in the high temperature reheater,the low melting point compounds such as Na2SO4,Na K3( SO4)2or Na O. Al2O3. 2( SiO 2) exist in the form of aerosol in the flue gases and in the meantime,adsorb particles in the flying ash and then,adhere to tube surfaces to form slags and contaminants.