燃煤可吸入颗粒的物理化学特性及形成机理

应用低压撞击器分别对某100 MW和50 MW燃煤机组锅炉的除尘器前后飞灰颗粒进行采样，研究了除尘器前后PM₁₀的物理化学特性，探讨了颗粒物可能的形成机理.结果表明，两台锅炉产生PM₁₀的质量粒径均呈双峰分布，峰值分别在0.1 μm和4 μm左右.粒径小于0.377 μm的颗粒可能为气化-凝结机理形成，超微米颗粒则可能是通过亚微米颗粒凝聚、聚结和矿物质熔融、破碎、聚结形成.亚微米颗粒中碱金属和碱土金属的氧化物或硫化物为其主要成分，而超微米颗粒中主要成分为难熔性氧化物.

Physiochemical characteristics and formation mechanism of inhalable particulate matter in coal combustion process

By using low pressure impactor, fly ash was sampled at the inlet and outlet of ESP in 50 MW and 100 MW utility boilers separately.The composition, mass size distribution and microstructure of fly ash were measured by using X-ray fluorescence,0.001 mg precision microbalance and scanning electron microscope (SEM).A similar bimodal distribution of PM₁₀ was obtained in both boilers studied, the small and large modes were formed at 0.1 μm and 4 μm, respectively.The chemical composition of the size-segregated ash showed that the ash particles smaller than 0.377 μm were formed via nucleation of vaporized ash components, and the primary chemical components were the oxides and sulfates of alkali metal and alkali earth metal in submicron-size ash.The microstructure measurements showed that the supermicron-size ash was formed by coagulation and coalescence of the submicron-size ash,and fragmentation and coalescence of mineral matter.Refractory oxides were the major composition of supermicron-size ash.