反应压力对玉米秆灰中碱金属热转化特性的影响

Effect of reaction pressure on thermal conversion characteristics of alkali metal in corn stalk ash

选用玉米秸秆为原料,探究反应压力对生物质灰中碱金属热转化特性的影响。在500℃制备玉米秆灰,在加压管式炉中设定不同反应压力和反应温度烧制灰样,采用XRF(X射线荧光)和XRD(X射线衍射)对制备的灰样进行分析。结果表明:反应压力抑制灰中无机矿物的释放。900℃时灰分损失率从0.1 MPa时的6.75%减少到1.0 MPa时的5.93%,减少约12%。1000℃时灰颗粒之间发生严重熔融,可挥发性物质释放到气相中的空隙受阻;0.1 MPa和2.0 MPa下的灰中K_(2)O的质量分数分别为13.2%和13.6%;而Cl的质量分数从0.1 MPa时的0.61%增加到2.0 MPa时的1.0%。说明提高反应压力能够有效地减轻高温下灰的熔融团聚程度,抑制灰分中低熔点物质的分解或气化,将更多的K元素和Cl元素保留在灰中。结合XRD分析可知,压力升高时灰中KCl和SiO_(2)等无机矿物的质量分数增加,证明压力增大能够有效抑制KCl的释放,并将其转化为硅酸盐保留在灰分中。

Corn straw was used as raw material to explore the effect of reaction pressure on the thermal conversion characteristics of alkali metals in biomass ash.Corn stalk ash was prepared at 500℃,and then the ash samples were placed in a pressurized tube furnace with different reaction pressures and reaction temperatures,and the prepared ash samples were analyzed by XRF and XRD.The results show that the release of inorganic minerals from ash is inhibited by reaction pressure.At 900℃the ash loss rate decreases from 6.75%at 0.1 MPa to 5.93%at 1.0 MPa,which is about 12%.At 1000℃severe melting occurs between the ash particles,and the voids of volatile substances released into the gas phase are blocked.The mass fraction of K_(2)O in ash at 0.1 MPa and 2.0 MPa is 13.2%and 13.6%,while the mass fraction of Cl increases from 0.61%at 0.1 MPa to 1.0%at 2.0 MPa.The results show that increasing the reaction pressure can effectively reduce the melting and agglomeration of ash at high temperature,and inhibit the decomposition or gasification of low-melting point substances in ash,and retain more K and Cl elements in ash.Combined with XRD analysis,the content of inorganic minerals such as KCl and SiO_(2)in the ash increases with the increase of pressure,which proves that the increase of pressure can effectively inhibit the release of KCl and convert it into silicate and retain it in the ash.