聚氨酯包膜缓释肥的制备及性能的研究

采用无溶剂喷涂成型法制备了聚氨酯包膜缓释肥,讨论了喷涂比例对包膜量和耐磨性的影响以及不同包膜量对缓释性能的影响。结果表明,聚氨酯预聚体与扩链剂的喷涂比例为7.50∶1、实际包覆量为7.23%时,包膜缓释肥的初溶率范围在10.00%~12.50%、微溶率范围在1.80%~2.40%,包膜效果最好;包覆肥颗粒的表面光滑度、均匀度和耐磨性能好,优于日本产包膜肥。     

Transport and reaction in evolving,disordered composites-I. Gasification of porous solids

The problem of modelling the gasification of porous solids is complicated by the interactions between the transport-reaction mechanisms and the dynamics of the complex, evolving morphology of the solid. These mechanisms can be decoupled by assuming that the morphology is perfectly disordered and remains as such throughout the gasification process. Whereas this assumption is undoubtedly simplistic it allows the study of the problem in the range between diffusion control and kinetic control. Throughout this work, the role of the morphology is highlighted whereas other aspects, such as chemistry, have been considerably simplified. The main goals are to study the interactions between the transport, reaction and morphological evolution processes and to emphasize the role of the erosion process in the acceleration of the gasification rate.     

Estimation of dynamic change in gasification rate of chars—II. Overlapped grain model

Structure model of solids which considers the change in degree of overlapping of grains with progress of the solid consumption reaction on the surface of the grain was presented. The proposed model can describe the dynamic change in surface area which first increases to the maximum and then decreases during char gasification using only the initial porosity and the initial surface area. The proposed model together with the previous models was compared with the experimentally observed dynamic change in surface area during gasification. This model can explain the experimental result (Adschiri and Furusawa, 1987) that the maximum surface area was obtained at the porosity of around 0.5.     

Molecular structure of a brown coal

A model for the structural unit of a typical Rheinische Braunkohle has been developed from the results of elemental analyses, pyrolysis experiments and titration studies and from extrapolation of literature data for similar coals. The model presented here has been successfully applied to explain the pyrolysis and hydropyrolysis behaviour of Rheinische Braunkohle.     

Ф168 mm高强度矫直机的设计开发

针对国内现有矫直机在生产过程中产生的诸多问题,新设计出Ф168 mm高强度矫直机,在矫直机的防水、防尘及设备稳定性方面进行了专门设计.经过数台该型号矫直机的制造和现场使用证明,新设计的Ф168 mm矫直机所采用的基本设计方案是可行的,管材矫直质量明显提高.     

切顶卸压无煤柱开采矿压显现特征分析

针对某矿切顶卸压无煤柱开采技术条件,采用理论分析、现场监测与数值模拟相结合的方法对其矿压显现特征进行了分析。结果表明:沿空留巷段可分为初次来压、矿压显现强烈及一般3个危险区,巷道变形发展主要分为掘进变形、采前变形、掘巷渐次变形与变形稳定4个阶段,其中掘巷渐次变形阶段对巷道影响最为严重。切顶卸压可以有效切断顶板的应力传播路径,使应力集中向支架远端的实体煤层中传导,提高支架的支撑效果。工作面滞后40～100 m范围内,煤壁侧应力与顶板累计沉降值显著增加,此阶段顶板岩梁运动剧烈,需要加强支护。研究成果可为矿山沿空留巷巷道施工与支护设计提供指导。     

Microstructure and properties of epitaxial layers by laser glazing

Various processes of laser surface melting are employed to modify the features of epitaxially grown microstructures in the melt. Three kinds of microstructures are demonstrated in this investigation. The one with complex microstructures possesses the best resistivity against hot stress corrosion.     

灵活性切缸供热空冷系统抽真空管道改造设计

为缓解火电厂发电利用小时少的问题,部分供热机组进行了灵活性切缸供热节能改造.为确保抽出更多高压蒸汽和低压乏汽用于扩大供热需求和提高灵活性调峰能力,机组需要在冬季更低设计背压3 kPa运行,已有机组的空冷系统抽真空管道不能满足要求,通过对抽真空系统在不同管段处的管径进行调整和方案组合,经阻力计算比较后,得出一组满足抽真空...