Behavior of alkali minerals in oxyfuel co-combustion of biomass and coal at elevated pressure  

作　　者：Oris CHANSA Zhong-yang LUO Wen-nan ZHANG Chun-jiang YU 

机构地区：[1]The State Key Laboratory of Clean Energy Utilization,Zhejiang University,Hangzhou 310027,China [2]Department of Chemical Engineering,Mid Sweden University,85170 Sundsvall,Sweden

出　　处：《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》2021年第2期116-129,共14页浙江大学学报（英文版）A辑（应用物理与工程）

基　　金：Project supported by the National Science Foundation Cooperation of China and USA(NSFC-NSF)(No.51661125012);Project of the State Key Laboratory of Clean Energy Utilization,Zhejiang University,China。

摘　　要：Combustion of biomass or coal is known to yield aerosols and condensed alkali minerals that affect boiler heat transfer performance.In this work,alkali behavior in the pressurized oxyfuel co-combustion of coal and biomass is predicted by thermodynamic and chemical kinetic calculations.Existence of solid minerals is evaluated by X-ray diffraction(XRD)analysis of ashes from pressure thermogravimetric combustion.Results indicate that a rise in pressure affects solid alkali minerals negligibly,but increases their contents in the liquid phase and decreases them in the gas phase,especially below 900℃.Thus,less KCl will condense on the boiler heat transfer surfaces leading to reduced corrosion.Increasing the blend ratio of biomass to coal will raise the content of potassium-based minerals but reduce the sodium-based ones.The alkali-associated slagging in the boiler can be minimized by the synergistic effect of co-combustion of sulphur-rich coal and potassium-rich biomass,forming stable solid K2SO4 at typical fluidized bed combustion temperatures.Kinetics modelling based on reaction mechanisms shows that oxidation of SO2 to SO3 plays a major role in K2SO4 formation but that the contribution of this oxidation decreases with increase in pressure.

关 键 词：Oxyfuel co-combustion Equilibrium calculations Chemical kinetic reactions Mineral’s identifications Thermogravimetric combustion 

分 类 号：TK6[动力工程及工程热物理—生物能]