煤和生物质共热解过程中,填料方式会显著影响挥发分之间相互作用及产物分布。分析分隔放置(Case1)、机械混合(Case2)、煤在棉秆上层(Case3)和煤在棉秆下层(Case4)4种填料方式下淖毛湖煤(NMH)和棉秆(CS)共热解产物的分布、组成及性质,并结合分形理论研究共热解半焦的孔隙特征,探究共热解协同效应。结果表明,NMH和CS协同作用因填料方式不同而变化,填料方式对共热解产物分布及性质影响大。用Case4方式时,共热解焦油产率最高,为15.94%,较理论计算值增加3.89%,正协同效应最显著。此时,CS热解产生的富氢组分及时与NMH热解挥发物发生交互作用,导致H2、CH4和C2~C4产量较理论值降低,共热解焦油产率增加。不同填料方式对共热解焦油中轻油馏分均产生负协同作用。含氧化合物相对含量减少可能是因为共热解过程促进脱氧反应(如脱羧和脱羰基化等),进一步生成脂肪烃,减少含氧官能团发生交联反应;在共热解中,·H自由基与活性含氧基团产生正协同作用,促使焦油中O、N、S原子向固体或气体产物转移。由半焦分形结果可知半焦分形维数D1和D2均在2~3间,说明半焦粗糙度和孔结构均满足分形结构基本特征。对于Case3和Case4方式,位于下层样品半焦的表面更粗糙。用Case3方式所得CS-C孔隙更小;而Case4方式所得NMH-C孔隙更不均匀,孔结构更复杂。

In the co-pyrolysis process of coal and biomass, the mixing mode significantly affects the interaction between volatile components, which in turn affects the distribution of products. In this study, the co-pyrolysis products distribution, composition, and propertiesof Naomaohu coal (NMH) and cotton stalks (CS) under four mixing modes, which is separated placement (Case 1), mechanical mixing(Case 2), coal in the upper layer of cotton stalks (Case 3), and coal in the lower layer of cotton stalks (Case 4). Combined with thefractal theory, the pore characteristics of co-pyrolysis char were studied, and the synergistic effect of co-pyrolysis was explored. The results show that the synergistic effect of NMH and CS varies with different mixing modes, and the mixing mode has a significant impact onthe distribution and properties of co-pyrolysis products. In Case 4 method, the co-pyrolysis tar yield is the highest, 15.94%, which is3.89% higher than the theoretical calculation value, and the positive synergistic effect is the most significant. At this point, the hydrogenrich components generated by CS pyrolysis interact with the volatiles of NMH pyrolysis in a timely manner, which result in a decrease inthe yields of H2, CH4, and C2 -C4 compared to the theoretical values, and an increase in the co-pyrolysis tar yield. Different mixing modes have a negative synergistic effect on the light oil in co-pyrolysis tar. The decrease in the oxygen-containing compounds may bedue to the co-pyrolysis process promoting deoxygenation reactions (such as decarboxylation and decarboxylation), further generating fattyhydrocarbons, and reducing the occurrence of cross-linking reactions of oxygen-containing functional groups. During the co-pyrolysisprocess, ·H radicals and active oxygen-containing groups have a positive synergistic effect, promoting the transfer of O, N, and S atomsin tar to solid or gas products. From the fractal dimension of char, the fractal dimensions D1 and D2 of the char are between 2-3, indicating that the roughness and pore structure of the char meet the basic characteristics of the fractal structure. For Case 3 and Case 4 methods, the surface of the sample char located in the lower layer is rougher. The CS-C obtained by Case 3 method has smaller pores; whilethe pores of NMH-C obtained by Case 4 method are more uneven and the pore structure is more complex.

0 引言

1 试验

   1.1 原料与试剂

   1.2 热解试验

   1.3 产率计算

   1.4 产物分析

2 结果与讨论

   2.1 TG/DTG分析

   2.2 产物分布和气体组成

   2.3 焦油分析

   2.4 半焦分析

3 结论