Comparison of gasification performances between raw and torrefied biomasses in an air-blown fluidized-bed gasifier
Comparison of gasification performances between raw and torrefied biomasses in an air-blown fluidized-bed gasifier
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鼓风流化床气化炉中生物质与烘焙生物质的气化性能比较
DOI：
10.1016/j.ces.2017.04.050
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发表时间：
2017
影响因子：
4.7
通讯作者：
Lin Jianzhong
中科院分区：
文献类型：
--
作者：
Ku Xiaoke;Jin Hanhui;Lin Jianzhong
作者已经开发的CFD-DEM模型已被扩展到直接比较原料和焙烧的草生物质在空气吹流化床气化炉的气化性能。床料是作为固体热载体的非煅烧橄榄石。此外，四个关键操作参数（即，气化温度Tr、过量空气系数λ、水蒸气添加量和生物质进料位置）也被系统地检查。结果进行了定性和定量分析的各种指标：流化行为，床层压降，产品气体浓度分布，总气体产率，和碳转化率（CC）。对于生物质原料和生物质焙烧产物，增加Tr可以提高总气体产率和CC;增加λ可以降低H2产率，但增加CO2产率和CC;添加水蒸汽对总气体产率和CC有积极影响，并可用于调节产物气体中的H2/CO比;总气体产率和CC均随生物质进料位置高度的增加而降低。对于所有的情况下，焙烧生物质获得较低的H2产率和CC，但较高的CO产率比其原始对应物在相同的操作条件下，这表明焙烧生物质需要一个较长的转化过程相比，原料燃料。此外，焙烧生物质的气化行为更依赖于燃料进料位置比原料燃料和这样的知识是重要的流化床气化炉的焙烧原料的优化设计。
A CFD-DEM model already developed by the authors has been extended to directly compare the gasification performances between raw and torrefied grassy biomasses in an air-blown fluidized-bed gasifier. The bed material is non-calcined olivine which acts as the solid heat carrier. Furthermore, effects of four key operating parameters (i.e., gasification temperatureTr, excess air ratioλ, steam addition, and biomass feed location) are also systematically examined. The results are analyzed both qualitatively and quantitatively by various indices: the fluidization behavior, bed pressure drop, product gas concentration profiles, total gas yield, and carbon conversion (CC). For both raw and torrefied biomasses, increasingTrcan enhance both the total gas yield and CC; risingλdecreases the H2yield but increases the CO2yield and CC; the steam addition has a positive influence on the total gas yield and CC and it can also be used to adjust the H2/CO ratio in the product gas; both the total gas yield and CC decrease with raising the height of the biomass feed location. For all cases, the torrefied biomass obtains a lower H2yield and CC but a higher CO yield than its raw counterpart under the same operating conditions, suggesting that torrefied biomass requires a longer conversion process compared with raw fuel. Moreover, the gasification behavior of torrefied biomass is more dependent on the fuel feed location than raw fuel and such knowledge is important for the optimal design of fluidized-bed gasifier for torrefied feedstock.