蒸汽爆破过程中生物质固相得率的试验测定方法

An Experiment Detection Method For the Biomass Solid Phase Yield in Steam Explosion Process

生物质在蒸汽爆破过程中各类成分会发生多种物理化学变化,造成固相质量的理论减少;固液混合物可能被气流带出或飞溅出回收仓,造成固相质量的非理论减少。这两种因素使生物质爆破前后的物料衡算难以实现。通过对青贮玉米秸秆、小麦秸秆、玉米秸秆、玉米芯、花生壳五种生物质进行多种处理方式的对比试验,我们发现青贮玉米秸秆经2.0MPa\10min、2.4MPa\5min、2.8MPa\3min三种饱和蒸汽蒸煮工艺处理后,再以550℃\4h灼烧后的总灰分相对原料平均变化率分别为0.68%、0.38%和0.34%,其它四种生物质在蒸煮过程中灰分含量也保持了相对稳定,表明在2.8MPa压力以下的不同蒸煮工艺对不同生物质总灰分的绝对质量影响基本没有,所发生的物理化学变化基本不改变总灰分的质量。由于同温度下的蒸煮过程与汽爆过程所发生的物理化学变化类型基本相同,因此对灰分含量影响可以在很大程度上相互参照。只要保证灰分在固相中是均匀分布的,就可以通过汽爆前后总灰分或酸不溶性灰分在固相中的相对含量f0与f1确定出爆后总的固相得率v=f0/f1,并计算出固相中每种成分的爆后得率。从而为汽爆工艺优化与过程分析提供一种更为准确可靠的物料衡算分析方法。

In biomass steam explosion（SE） process, the different components in biomass will occur physical and chemical changes which generate soluble products and volatile products because of high temperature and pressure steam and other materials. These cause theoretical decrease in biomass solid phase mass. In addition, it is inevitable that solid- liquid mixture is brought out by airflow or splashed out of recycle cavity in violent explosion shock wave of practical SE process, although the recycle cavity equips solid gas separation device. This causes non- theoretical decrease in biomass solid phase mass. Because the mass decrease by the two factors is difficult to detection, it is difficult to achieve quality balance between SE process before and after. And then, the abstract quality change of different components in biomass would be a barrier in SE technology optimization and process analysis. In order to solve this problem, we conducted contrast experiments with silage corn straw, wheat straw, corn straw, corncob and peanut shell, found that silage corn straw total ash quality rates of change are 0.68%, 0.38% and 0.34% after a boiling process in 2.0MPa／10min, 2.4MPa／5min and 2.8MPa／3min and a heating process in550℃／4h. The other four kinds of biomass also remain relative stability in boiling processes. These indicate that different boiling conditions have little impact on different biomass total ash quality below 2.8MPa boiling process. Although boiling process and SE process have different degrade degrees, they have about same physical and chemical changes, include volatilization, sublimation and thermolysis. And then, the impact on ash quality between two processes would be cross references. Then if ash is equally distributed in solid phase, we can determine total solid phase yield（v） by the relative amount of total ash or nonacid- soluble ash before（f0） and after（f1） SE process： v= f0/ f1,and then we can determine different components solid phase yield（cn） by their relative amount before（m0） and after（m1） SE process： cn =m1v/ m0. This method not only reflects solid phase quality theoretical decrease caused by soluble products（liquid phase） and volatile products（gas phase） generated in SE process, but also avoids experiment process errors caused by solid particle dissolved in liquid phase and splashed in explosion, provides a more accurate and reliable material balance calculate way for SE technology optimization and process analysis.