煤制天然气工厂建设若干问题的探讨

近年来国内兴起了煤制天然气建设热潮,但可供参考经验不多。本文结合煤制天然气工厂建设经验,介绍了面向工业用户、面向城镇用户和面向综合用户三类工厂,简述了“从煤矿到煤制天然气工厂再到城镇用户”供应链存在的“煤化工生产装置要求安、稳、长、满、优运行与用户用气量不均衡之间的矛盾”和“煤化工生产装置阶段性停产必然性与用户要求供气不间断之间的矛盾”,指出了保证连续稳定供气是工厂建设的首要任务,解决或缓解供应链上的主要矛盾是建设的关键问题;分析了影响供应链上系统运行的因素,表明工厂首先要有明确的定位,煤源是工厂设计和运行的基础,采用可靠技术、本地化装备、多系列装置有利于工厂的优化运行和快速消除故障;提出应从总体设计开始设计全厂信息化并系统集成,安全环保设施和剩余物质管理要考虑规范升级对策,并高度重视由于量的变化所带来的问题;与利益相关者的关系非常重要。综合考虑资源、市场、环境和政策来制定建设原则。     

Method for preparing polyaluminocarbosilane

Polyaluminocarbosilane (PACS) was synthesized directly by the one‐pot reaction of polydimethylsilane (PDMS) with aluminum acetylacetonate [Al(acac)₃] in an autoclave. In this closed system, all the aluminum in Al(acac)₃ was converted into PACS. Therefore, the content of aluminum could be readily controlled quantitatively. On the basis of Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR, ²⁹Si‐NMR, and ²⁷Al magic‐angle spinning NMR analysis, the reaction mechanism was proposed as follows: PDMS dissociated during pyrolysis to generate silicon free radicals, and then they reacted with Al(acac)₃ to yield PACS containing (Si? O)_nAl groups (n = 4, 5, or 6). Meanwhile, these reactions resulted in the cleavage of O? C and/or O?C bonds in Al(acac)₃. Some of the free‐radical fragments generated by this cleavage continued to react with the silicon free radicals and were incorporated into the structural units of PACS; the rest of them may have been converted into small oxygen‐containing compounds, which were removed in the subsequent processing after the reactions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

基于GT-Power的LPG燃气组分对发动机排放影响的研究

通过建立单缸点火式LPG发动机在GT-Power中仿真,来研究LPG组分及其比例对发动机排放的影响.仿真实验表明,LPG组分对污染物的排放有重要的影响.随着丁烷比例的增加,CO和HC的排放增加,而NO_x减少;其中,CO、HC排放最少的是Fuel 1#,NO_x的排放最低的是Fuel 3#;考虑到综合排放性能和动力性的同时,丙烷与丁烷比例为7:3时最佳.     

氧化镧的加入对PREP制备钨粉末性能的影响

采用等离子旋转电极雾化技术(plasma rotating electrode processing,PREP)制备出纯W和W-La合金球形粉末,对比分析了2种类型粉末的化学成分、形貌、物理性能、缺陷和粒度分布。结果表明:PREP法制备的球形纯W粉末表面光滑、球形度高,小于106μm粉末的收得率为70%。在棒料中加入La₂O₃后,大部分La₂O₃在PREP过程中挥发,残余的La₂O₃优先附着于液滴表面,降低了的液态金属钨的表面张力,将小于106μm粉末的收得率提升至90%;但是,表面张力的降低同时也导致W-La合金粉末表面出现少量缺陷。La₂O₃提高粉末收得率的现象为研究提高PREP技术粉末收得率提供了新思路。     

SiCp/Al复合材料薄壁件车削力的仿真研究

应用有限元分析软件ABAQUS对Si Cp/Al复合材料薄壁件车削力进行了仿真研究,得到了切削用量对切削力的影响规律,并结合文献的实验成果对相应规律进行了分析。仿真结果表明:在Si Cp/Al复合材料薄壁件车削过程中,随切削速度的增大,三向切削分力(轴向力Fx、径向力Fy、切向力Fz)均增大,但径向力Fy增幅很小;随进给量的增大,三向切削分力都有增大的趋势;随背吃刀量的增大,三向切削分力均显著增大;背吃刀量是影响切削力的主要因素。     

宏观过程的方向与限度——可逆性判据(Ⅱ)

本文从平衡判据的普遍规律--克劳修斯不等式出发,按照不同的过程条件,分别讨论了熵判据、亥氏函数和吉氏函数判据以及相变化和化学变化的可逆性判据.同时指出了这些平衡判据所包含的物理意义及它们间的一些内在联系.     

堆石坝面板声发射源组合定位方法

堆石坝上游侧的混凝土面板是关乎大坝安全的重要防渗结构.针对现有声发射源定位方法在大尺度、时变性结构中定位效率与精度的不足,提出了一种兼顾大尺度与波速扰动影响的声发射源组合定位方法.首先,为减少声发射源定位计算中的无关搜索域,发展了一种分布式声发射传感器阵列,并基于各声发射传感器到时权重,建立了关于子监测阵列快速识别与声...     

Covalent Adaptable Microstructures via Combining Two-Photon Laser Printing and Alkoxyamine Chemistry: Toward Living 3D Microstructures

Manufacturing programmable materials, whose mechanical properties can be adapted on demand, is highly desired for their application in areas ranging from robotics, to biomedicine, or microfluidics. Herein, the inclusion of dynamic and living bonds, such as alkoxyamines, in a printable formulation suitable for two-photon 3D laser printing is exploited. On one hand, taking advantage of the dynamic covalent character of alkoxyamines, the nitroxide exchange reaction is investigated. As a consequence, a reduction of the Young´s Modulus by 50%, is measured by nanoindentation. On the other hand, due to its “living” characteristic, the chain extension becomes possible via nitroxide mediated polymerization. In particular, living nitroxide mediated polymerization of styrene results not only in a dramatic increase of the volume (≈8 times) of the 3D printed microstructure but also an increase of the Young's Modulus by two orders of magnitude (from 14 MPa to 2.7 GPa), while maintaining the shape including fine structural details. Thus, the approach introduces a new dimension by enabling to create microstructures with dynamically tunable size and mechanical properties.     

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随着对清洁能源需求量的日益增长，天然气国际贸易量正在不断加大。远隔重洋地区的天然气贸易是依靠将天然气液化后通过船运来完成的，因而LNG船就成为了完成天然气远洋贸易的关键设备。文章回顾了LNG船的发展史，介绍了LNG船的技术特点和一些配套设施，同时还阐述了我国需要建立自己的LNG船队，从而保证我国LNG进口的重要意义。     

Earliest Deadline First Scheduling with Active Buffer Management for Real-Time Traffic in the Internet

We studied the problem of QoS guarantee for differentiated services. A two-level hierarchical scheduling framework was deployed to separate QoS metrics. Due to its desirable property of minimizing the maximum packet lateness, the Earliest Deadline First (EDF) scheduling was adopted to provide the in-class scheduling for the time-sensitive traffic. We employed an EDF scheduler combined with an active buffer management scheme (CHOKe) to improve the fairness of resource allocation and to maintain a good delay performance for real-time applications. Simulation results showed that the proposed scheme can achieve a better delay performance and make a more fair bandwidth allocation between the real-time TCP and UDP connections than the First Come First Served (FCFS) scheduling with the drop-tail buffer management which is commonly deployed in traditional IP routers.