为了研究秸秆燃烧中钾（K）类无机物的逸出特性,计算其逸出速率,利用X射线荧光能谱仪（XRF）和X射线衍射仪（XRD）分析玉米秸及其低温灰中K的化学形态,利用同步热分析仪（STA）研究秸秆及其灰中主要K类无机物在高温过程的逸出特性,建立KCl在多孔介质中逸出和在熔融相中分压的蒸发模型,并应用模型计算秸秆灰中KCl的蒸发速率。结果表明：秸秆低温灰中的K主要以KCl、K2SO4形态存在,两者约占灰总量的13%;常用燃烧温度下,KCl主要以蒸发形式逸出;KCl与K2SO4的共熔,可降低KCl在熔融相中的蒸气压;秸秆灰中KCl蒸发速率的计算值与实验值吻合良好。
Abstract
The objective of this study is to investigate the release characteristics of potassium（K）and calculate its release rate during biomass combustion.Chemical forms of potassium in corn stover and its ashes were analyzed using X-ray fluorescence （XRF）,X-Ray diffraction （XRD）. Release characteristics of potassium chloride （KCl） at normal combustion temperatures was measured using simultaneous thermogravimetric analyzer （STA）. A model considering transport resistance from porous medium and partial pressure of KCl was developed to calculate the evaporation rate of KCl in corn-stover-ash. Results show that KCl and K2SO4 are the main species of potassium, accounts for about 13% of corn-stover-ash. Evaporation is the main way of the KCl release at normal combustion temperatures. Vapor pressure of KCl in molten phase is decreased via eutectic melting of KCl and K2SO4; The calculation agrees well with the experimental results.
关键词
生物质能 /
燃烧 /
KCl /
蒸发模型 /
分压 /
多孔介质
Key words
biomass energy /
combustion /
potassium chloride /
evaporation model /
partial pressure /
porous media
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