生物质锅炉积灰特性与露点腐蚀

以ND钢为研究对象，选取316 L不锈钢为对比材料，主要研究了65 t·h^-1生物质循环流化床锅炉烟气深度冷却条件下的积灰与露点腐蚀耦合特性。对积灰和腐蚀层进行了XRF、XRD、SEM和EDS分析。实验结果表明：实验管件表面沉积物可分为腐蚀层、耦合层和灰沉积层（NH₄Cl、SiO₂和（NH₄）₂SO₄）。耦合层包含了灰沉积物和金属腐蚀产物，且与灰沉积层黏结紧密易剥落；腐蚀层多为金属的氯化物和氧化物，其厚度随实验进口水温降低而降低，当管壁温低于烟气水露点时，ND钢被腐蚀的程度急剧加重。在实验条件下，ND钢的抗露点腐蚀能力弱于316L不锈钢。

Characteristics of ash deposit and dew point corrosion in biofuel boiler

The coupling characteristics between ash deposit and dew point corrosion of deep-cooling flue gas on ND steel and 316 L stainless steel(control) was investigated in a 65 t·h^-1 circulating fluidized bed biofuel boiler. The ash deposit and corrosion layer were studied by X-ray fluorescence spectroscopy(XRF), X-ray diffraction(XRD), scanning electron microscope(SEM) and energy dispersive spectrometer(EDS). Results indicated that the deposits on tube surface could be classified as layers of corrosion, coupling and ash deposit(NH₄Cl、SiO₂ and(NH₄)₂SO₄). The coupling layer contained ash deposit and metal corrosion by-product, which was prone to spall off because of strong adhesion to the ash deposit layer. The corrosion layer, mainly composed of metal compounds of chlorides and oxides, reduced dramatically in thickness with the decrease of inlet water temperature. The degree of corrosion of ND steel increased sharply when wall temperature was below water dew point of flue gas. ND steel showed corrosion resistance inferior to 316 L stainless steel at experimental conditions.