超重力强化甲醇柴油乳化行为研究

The interest of using alternative alcohol fuel in diesel engines has been accelerated recently due to the rapid decrease of world petroleum reserves and restrictions on exhaust emissions from internal combustion (IC) engines triggered by environmental concerns. Combined with China's situation, coal is abundance and coal-to-methanol technology is practicable because of its low cost. Among these fuels, methanol-diesel emulsified fuel, which can be used as alternative fuels in the existing engines, have received increasing attention. .The traditional emulsified device have the mechanical stirring, homogenizer and colloid mill etc, have some shortcomings such as bigger equipment, higher energy consumption, worse dispersity characteristics and batch operation etc, which influence the development of the methanol-diesel emulsified fuel..Aimed at above problems, Impinging Stream-Rotating Packed Bed (IS-RPB) as emulsified device is firstly proposed according to the intensifying liquid/liquid interaction of mix characteristics. The velocity fields distribution of fluid particle and coupling parameter are built between impinging and rotating packed regions. The emulsified processes are analysised logically, which are divided into initial emulsification, intensified emulsification and perfect emulsification. Effect of the high gravity factor, methanol content, emulsifier amount, HLB value and liquid flow rate on the stability, rheological property, dispersity, physical and chemical characteristics of methanol-diesel emulsified fuel with novel compound surfactants were studied systematically. .This technology have academic research significance and potential industrial application prospect for developing novel alternative fuels, alleviating engery crisis and decreasing environmental pollution.

石油资源日趋短缺和环境污染日益严重，发展低排放代用燃料已引起了世界各国的重视。结合我国煤资源丰富的国情，以煤制甲醇的技术比较成熟，生产成本低。甲醇柴油乳化燃料作为一种新型替代燃料，由于其燃烧效率高、污染少等特点，得到越来越多科技工作者的青睐，成为乳化燃料领域研究的热点。传统乳化柴油制备技术主要是间歇操作，存在物料混合不均、稳定性差、乳化剂用量大等缺点，制约乳化柴油技术的发展。本项目创建强化液-液混合与接触过程的新型超重力机制（IS-RPB）作为乳化装置，建立流体质点在撞击区和旋转填料区的流体速度场分布；阐明超重力制备甲醇柴油的乳化行为，揭示旋转填料床内腔尺寸与撞击雾面的"耦合"效应；通过研究乳化剂的配伍机理和助乳化剂的增溶效能，探索甲醇柴油乳化协同机制；考察物性参数、结构参数和操作参数等对乳化柴油流变性能、稳定性、表面张力、分散性能和腐蚀性等的影响，开辟连续制备乳化柴油新工艺。

石油资源日趋短缺和环境污染日益严重，发展低排放代用燃料已引起了世界各国的重视，特别是醇类燃料的研究一直是广大科技工作者十分关注的课题之一。影响制备甲醇柴油乳液性能的两个关键因素是乳化剂和乳化装置。针对传统乳化柴油制备技术主要是间歇操作，存在物料混合不均、稳定性差、乳化剂用量大等缺点，开发新型乳化剂和连续操作的高效乳化装置势在必行。.围绕以上思路，开发了适合于甲醇乳化的撞击流-旋转填料床（IS-RPB）乳化装置，建立了流体质点在撞击区和旋转填料区的流体速度场分布，构建了制备甲醇柴油乳液的旋转填料床内径与撞击面的“耦合”结构参数，分析了超重力环境下甲醇柴油的乳化过程，将乳化过程分为初始乳化、强化乳化和完善乳化三个阶段，并对其进行了流场模拟和各个乳化阶段的贡献规律。.根据 Prince 的混合膜理论，研究复配乳化剂和助乳化剂的协同机制，优选了复配乳化剂，绘制了拟三相图，探索了乳液增溶甲醇量的影响规律。在此基础上研究了操作参数、结构参数对甲醇柴油乳液稳定性的影响规律。超重力因子和柴油流量的增加，提高了甲醇和柴油两股液体微元的相互作用，有利于甲醇和柴油的乳化；提高甲醇柴油乳液的循环次数，有利于提高其稳定性，稳定时间可达30天以上。.流变性能研究结果表明：在牛顿型复合乳化剂条件下，甲醇柴油乳液在各种组分配比下均近似牛顿流体，甲醇柴油乳液的粘度随着乳化剂含量及粘度的增加而增大，随着柴油含量的减少而增大，满足国家燃油标准（GB/T 265）。.采用光学显微镜摄像技术来可视化地研究甲醇柴油乳液分散相的粒径大小和分布。研究表明：通过改变超重力因子、柴油流量、甲醇含量和乳化剂用量等操作参数可以控制甲醇柴油乳液甲醇的分散度，其平均粒径为12-40μm。.以石油产品性能测试的国家标准为依据，对不同比例的甲醇乳化燃料的密度、表面张力、腐蚀性等理化性质进行了测试和研究。研究表明：当甲醇含量低于15%时，甲醇柴油乳液的密度、腐蚀性、十六烷值等理化性质满足柴油机的燃烧要求，满足国家燃油标准。.本研究探索了超重力强化甲醇柴油的乳化行为，甲醇柴油乳液各项性能满足柴油燃烧指标，更重要的是实现了甲醇柴油乳液的连续性制备，可以“现做现用”，达到少用乳化剂目的，开拓了乳化柴油制备新工艺。本文的完成，对于缓解能源短缺，发展新型代用燃料、降低环境污染具有重要的理论研究意义和工业应用前景。