摘要
研究了取自某燃用渣油锅炉不同部位换热面的多个沉积样品,分析了不同区域和沉积生长不同阶段的组分与控制机理。XRF、SEM-EDAX和XRD分别用来鉴定样品的元素组成、形貌以及晶相,并对其中2个沿沉积生长方向有明显分层的典型样品,用环氧树脂固化,对断面做分区能谱扫描。结果表明,渣层生长初期相对成熟阶段,出现Fe、V、Ca和S的富集,而Si和Al则表现出相反的趋势。这主要是由于成长初期气相SO_3和V_2O_5等以及被熔融相Fe_2O_3包裹的SiO_2小颗粒在热涌力和凝结等作用下输送到沉积表面发生粘附作用。初期的矿物组成相对成熟阶段含有较多长石类矿物,如钙长石和钠长石。对于成熟渣样,炉膛内沉积主要矿物组成为莫来石,2级(高温)过热器部位沉积主要为莫来石,方石英与微斜长石(钾铝硅酸盐),而1级(低温)过热器与省煤器部位则出现一些钒酸钠,钒酸铁与硫酸钙沉积。
Ash deposits samples at different locations in a oil-fired boiler, which has suffered severe ash deposition problem, were studied to investigate the mechanism controlling the deposition in different deposition stages and at different zones. The XRF, SEM- EDAX and XRD techniques were used to identify the elemental composition, morphorlogy and mineralogy characteristics respectively. Two typical mature samples which were kept undisturbed were embeded in epoxy resin and then polished, subjected to SEM-EDAX analysis to quantify the elemental composition in the different layers in the direction of deposits growth. The results indicated that in the initial particulate layer, the major elemental content, viz. V, S,Na,Ca,Fe are much higher than the outer layer, while Si and Al show the adverse tendency. This may be due to the vaporized SO3 and V205 and the molten Fe2O3 or SiO2 particles covered by melten Fe2O3,which are transferred and then adhered to the deposit surface mainly by the following two machenisms,viz, thermophoresis and condensation. The major minerals in deposits at the water-wall zone is mullite, while for samples from the secondary superheater tube bank（at the furnace exit）, besids mullite there are considerable cristobalite and microcline （potassium aluminosili-cates）. Some vanadium oxide or salt（i.e. NiV3O8, NaV6O15 and Fe0.125V2O5） are detected for samples from primary superheater tube bank and the econo-mizer zones.
出处
《中国电机工程学报》
EI
CSCD
北大核心
2007年第5期49-54,共6页
Proceedings of the CSEE
关键词
燃油锅炉
灰沉积
初始小颗粒层
烧结
oil-fired boiler
ash deposition
initial particulate layer
sintering
