有氧烘焙对生物质气化及碱金属迁移转化特性的影响

Effects of oxidative torrefaction on biomass gasification and alkali metal release and transformation characteristics

本工作研究了有氧烘焙对玉米秸秆组成成分、烘焙产率、化学结构及微观结构等理化特性及气化特性的影响,同时考察了玉米秸秆烘焙及气化过程中碱金属的迁移转化规律。结果表明,烘焙可有效提高玉米秸秆中固定碳含量,降低H/C、O/C。相较于惰性烘焙,有氧烘焙具有更好的提质效果,结合H/C、O/C、质量产率和能量产率发现,氧气体积分数为6%时较合适。烘焙玉米秸秆气化气中CO含量、气体产率及热值随烘焙气氛中氧气含量的增加呈先上升后下降的趋势,在氧气体积分数为6%时气化品质相对较好,此时气体组分中CO体积分数为14.73%、气体产率达到1.09 L/g、气体热值达到4.93 MJ/m3。烘焙过程中碱金属在玉米秸秆中富集,并促进部分水溶态钾向醋酸铵溶态钾转化,有助于气化过程中生成更多不溶态钾,且有氧烘焙促进作用更明显。研究结果可为生物质有氧烘焙提质及气化产气的技术推广提供基础数据及技术支持。

The effects of oxidative torrefaction on the basic physicochemical,such as composition,torrefaction yield,chemical structure,and microstructure,and gasification properties of corn straw,were studied.The release and transformation of alkali metals during torrefaction and gasification of corn straw were also investigated.The results show that torrefaction can increase the fixed carbon content in corn straw effectively and decrease the values of H/C and O/C.Compared with inert atmosphere torrefaction,oxidative torrefaction has better quality improvement effects,and the best roasting atmosphere is 6% oxygen concentration.Combining H/C,O/C,mass yield and energy yield,it is found that the oxygen concentration of 6% during torrefaction is suitable.The concentration of CO,gas production rate,and gas calorific value of torrefied corn straw increased first and then decreased with the increase of oxygen concentration in the torrefaction atmosphere during gasification.The gasification characteristics were optimal at 6% oxygen concentration,with CO content of 14.73%,gas production rate of 1.09 L/g,and gas calorific value of 4.93 MJ/m^(3).The alkali metals were enriched in the corn straw during the torrefaction process.The conversion from water-soluble K to ion-exchanged K was also promoted,which helped produce more insoluble K in the gasification process.The oxidative torrefaction promoted the effect more pronounced.The results of the study can provide essential data and technical support for the technological promotion of oxidative torrefaction and gasification of biomass.