High temperature swelling of coal/tetralin mixtures in a high pressure microdilatometer

High pressure microdilatometer experiments were performed on a subbituminous (Wyodak) and a bituminous (Illinois no. 6) coal in helium and hydrogen atmospheres with and without added tetralin. Wyodak coal samples showed no swelling but contractions ranging between 24 and 40 vol% upon heating at 20 and 100 °C min^{− 1} under helium or hydrogen pressures between 150 and 1000 psig (˜1.0–6.9 MPa). Under the same conditions, Illinois no. 6 coals displayed contractions (25–60 vol%) prior to swelling up to 117 vol%. Upon tetralin addition (at 35–190 wt% of the coal), Wyodak coal samples did not swell but showed an increasing contraction with increasing helium or hydrogen pressure due to a slight softening and fusion of the coal particles. In contrast, addition of tetralin at much lower concentrations (5–35 wt%) had a marked effect on the contraction and swelling behaviour of Illinois no. 6. A maximum swelling of 200 vol% was obtained at a tetralin addition of 30 wt%. The increased swelling results from more extensive softening and fusion of coal particles in the presence of tetralin. Both coals showed a decreasing char yield with increasing tetralin concentration. The substantially lower extent of interaction observed between Wyodak coal samples and tetralin compared to Illinois no. 6 coal can be attributed to the differences in pore structure and/or chemical constitution of the two coal samples. Examination of the resultant solids by optical microscopy revealed the microstructural changes produced by thermal treatment in dilatometer experiments.     

Coal liquefaction in nitrogen compounds

Model compound studies have shown that 1,2,3,4-tetrahydroquinoline is an exceptionally good coal solvent. In the pure compound, subbituminous coal conversion to THF-soluble products approaches 100% under relatively mild reaction conditions. The effectiveness of tetrahydroquinoline for coal conversion appears to be related to its concentration relative to coal. The unique behaviour of tetrahydroquinoline is ascribed to its being a highly active H-donor; the fact that it is regenerable under reaction conditions by the reaction of hydrogen and quinoline; and that its polarity allows penetration of the coal structure and aids in dispersion of the dissolved coal. It has been found that, during reaction with coal, tetrahydroquinoline and other nitrogen compounds undergo extensive condensation reactions which result in an increase in the nitrogen content of the high boiling and non-distillable liquefaction products.     

Relative reactivity of hydrogen donor solvent in coal liquefaction

Hydrogen transfer from donor solvent to coal must involve reactions such as hydrogen donation to free radicals and hydrogenation of aromatic structures. The relative reactivities of five typical hydrogen donor solvents, more reactive than tetralin, were determined using a competing elimination reaction in the liquefaction of a bituminous coal at 400 °C and a brown coal at 350 °C. 9,10-Dihydroanthracene, 9,10-dihydrophenanthrene and 1,2,3,4-tetrahydroquinoline exhibited outstanding hydrogen donating ability. Further, the relative reactivities of five mild hydrogen donor solvents such as acenaphthene and indan were determined by a similar elimination reaction using a bituminous coal at 450 °C.     

广义KDV-MKDV方程的精确解

利用直接积分方法将广义KDV-MKDV方程化为一阶变系数非线性常微分方程组,然后用待定系数法确定相应的常数获得了广义KDV-MKDV方程新的精确解;利用先作假设变换后选取试探函数的方法来直接构造广义KDV-MKDV方程新的精确解.     

利用Liapanov直接方法判定差分方程稳定性

研究差分方程稳定性的强有力的方法是Liapanov直接方法,这一方法的核心思想是针对所研究的方程,构造出其相应的Liapanov函数,利用它来判定方程的稳定性．     

Dependence of coal liquefaction behaviour on coal characteristics. 6. Product distributions from coals treated in a continuous-flow reactor

Further experimentation with coals in a continuous-flow reactor system at 440 and 455°C confirms the significance of the previous classification of a set of coals by cluster analysis. The greatest yields of distillable products tend to be given by coals of high sulphur content in the middle of the range of the high-volatile bituminous rank classes. Yet the lowest yields of preasphaltene (toluene-insoluble material) tend to be given by coals of high rank and medium sulphur content. The group of low sulphur, low-rank coals (mostly Rocky Mountain province), in a solvent different from that used for the other groups, showed poor conversion and poor distillate yield at the higher temperature. It is concluded that this coal/solvent combination is particularly prone to retrogressive reactions, including coking.     

窄带滤光片光学极值法直接监控的光学设计

窄带滤光片是应用于光谱学、激光、天文物理学、通信等各个领域的光学组件,精确控制每一层膜厚是制备滤光片的困难所在.采用光学极值法直接监控工件,可以同时制备多件滤光片.设计了监控光路和信号获得电路,通过探测到的测试信号,监控薄膜膜厚,实现了直接监控.     

直埋玻璃钢聚氨酯保温管及其保温层厚度设计

介绍了直埋玻璃钢聚氨酯保温管的结构形式及优良性能．为了降低玻璃钢聚氨酯保温管的初期投资,探讨了直埋玻璃钢聚氨酯热力管保温层的2种设计方法,并采用工程实例进行计算．结果表明,按双层保温计算法设计保温层更为经济合理．以上结论为直埋玻璃铜聚氨酯保温管保温层设计提供了理论依据．