Comparative Testing of Powder Caking

In a collaborative research project called “Consumer Oriented Solids Transport Technology” (COSTT), a uniaxial caking tester was developed to measure the caking propensity of bulk solids under controlled environmental conditions. To validate the results gained from this tester, a series of round robin tests were run, using an organic acid of known humidity dependence as test material. These tests showed that even seemingly minor deviations in the test procedure can cause significant deviations in the measured uniaxial strength. This paper gives an indication of the level of details required to run a reliable caking test and the obtainable reproducibility.     

Using Nanoscaled Powder as an Additive in Coarse-Grained Powder

Nanoscaled Al₂O₃ powder is used as additive in coarse-grained Al₂O₃ green bodies. Its influence on the green density is investigated. The potential effect of powder mixing on the green density is described by a model for multimodal powder mixtures that predicts the powder composition for maximum green body density. The model is applied to bimodal and trimodal mixtures with one of the components being nano-powder. The calculated relative densities are compared with experimental results. Furthermore, sintering experiments are conducted to investigate the influence of the amount of nanoscaled powder on the sintered densities of bimodal bodies.     

沼气低温净化工艺的模拟研究

依据气液相平衡理论,运用Aspen Plus软件,选用合适的单元操作模块,采用PENG-ROB物性计算方法,通过对沼气泡点、露点图的分析选择合适的模拟条件;在Aspen Plus软件上对沼气低温净化工艺进行模拟,并根据模拟数据分析压力、温度对低温净化工艺的效果的影响。     

LNG接收站低温潜液泵应用

液化天然气(LNG)作为清洁能源,在世界应用越来越广泛。基于低温潜液泵作为LNG接收站的关键设备之一,对于整个工程建设的工期、费用和质量,以及后期的运营起到决定性作用。主要围绕低温潜液泵的结构特点、检验试验及国产化情况进行简述。     

热水溶液中钛酸锶晶粒的结晶过程

研究了以TiCl4水解得到的H4TiO4胶体作为钛源,在热水溶液中制备SrTiO3晶粒的结晶过程,TEM和XRD结果表明,其结晶过程主要包括3个阶段,第1阶段主要是SrTiO3晶核的形成过程;第2阶段主要是SrTiO3晶粒的配向聚集生长过程;第3阶段主要是SrTiO3晶粒的溶解结晶过程,其中第1阶段的控制步骤为H4TiO4胶体的溶解,第2阶段中晶粒的配向聚集生长在短时间内即可完成,很快进入第3阶段小晶粒的溶解和大晶粒的重结晶过程,该阶段反应速度慢,需要较长时间才能得到结晶完好的晶粒,在热水溶液中以H4TiO4胶体作为钛源制备SrTiO3晶粒关键在于控制结晶过程的第1阶段和第2阶段。     

16MnDR低温换热器的制造

本文介绍了低温氯甲烷换热器的技术特性、材料特性、工艺成型、焊接以及检验等方面内容。     

氮气雾化微细球形铝粉的生产工艺

介绍了氮气雾化微细球形铝粉的生产工艺,铝锭熔化,雾化制粉、铝粉分级和包装都是在氮气保护中进行,气体雾化器和铝液喷嘴紧密耦合并用高温高压氮气雾化,生产的铝粉颗粒为球形,流动性好,氧含量低,细粉收率高.     

聚丙烯装置细粉产生的原因分析

从催化剂和工艺操作2方面分析了聚丙烯装置生产中细粉产生的原因,以及细粉过多时对生产的危害。结果表明,催化剂细粉含量高、运输、制备、破碎,汽蒸系统、干燥系统操作不当,反应器出口没加或少加失活剂是细粉产生的主要原因;细粉产生的过多,干燥效果差、风送系统运转困难、引起工艺系统的堵塞、影响设备的使用寿命。提出了相应解决办法及注意事项。     

直接法制备细小颗粒RDX工艺条件研究

在乌洛托品硝解制备ＲＤＸ的工艺基础上,采用先氧化后结晶工艺,研究如何控制结晶过程的各种因素来制备符合美军标〔ＭＩＬ－ｇ８Ｃ〕的细小粒度的ＲＤＸ产品。     

Production of Fine, High-Purity Beta Silicon Carbide Powders

Submicrometer SiC ( β -form) powders were synthesized by reacting silica and carbon black at temperatures between 1450° and 1800°C. Simultaneous application of vacuum and mixing provides the condition for full conversion of silica to SiC. It was shown that two different reaction mechanisms are possible, depending on the reaction temperature and the partial pressure of CO. At lower temperatures (below approximately 1400°C), the dominant mechanism for silicon carbide formation involves the solid-state reaction of silica and carbon. At higher temperatures (above approximately 1400°C), the dominant mechanism is the reaction between gaseous SiO and C. Above 1400°C, the rate of SiC formation is controlled by the rate of SiO formation. In as-synthesized form, the SiC powders typically contain < 0.2 wt% of unreacted silica and free carbon in the range between 6 and 15 wt%. Precise control of partial pressure of CO in the reaction chamber and continuous mixing of the reactants provide the conditions under which the rate of silicon carbide formation may be increased by one order of magnitude. The process is suitable for large-scale commercial production of SiC, requiring no postfabrication acid leaching or major milling.     

煤制合成气低温甲醇洗工序管道布置总结

根据煤制合成气低温甲醇洗涤净化工艺装置系统特点,对其管道布置在工程设计时的一些特殊要求进行总结,供工程设计人员参考。     

超低温下甲烷爆炸极限分析及实验测试装置设计

国内大量学者对含氧煤层气液化流程中各阶段的爆炸危险性进行了分析评价,而评价过程中采用的超低温下甲烷的爆炸极限数据都是基于现有的经验公式计算得到的。通过低温下甲烷爆炸极限实验数据与该等经验公式的计算结果进行对比发现,该等经验公式在计算超低温下甲烷的爆炸极限时已不再适用,因此前人对煤层气液化流程爆炸危险性的评价结果不完全正确。针对现有低温下甲烷爆炸极限数据的局限性,构建了一套测试超低温工况下甲烷爆炸极限的实验装置,并对实验过程中爆炸容器的热应力进行了建模分析。研究结果表明:爆炸过程中,容器会产生很大的热应力,超过了材料的许用应力;在容器体积不变的情况下可通过增加长径比来减小热应力。     

ASME低温用钢国内应用探讨

低温容器用途日益广泛。由于国内低温用钢可选择性差等一些因素,ASME低温用钢在国内项目中被大量使用。随着新容规（TSG R0004—2009）及其实施意见的颁发,对低温容器设计有了更高更具体的要求。对选用ASME低温用钢而按国内标准设计的情况进行了探讨,分析了ASME与国内标准体系的不同处,指出设计时对材料本体需注意的一些问题并提出解决方案,同时也对设计ASME低温用钢容器会遇到的一些问题作了提醒和解释。     

Product Loss Minimization of an Integrated Cryogenic Separation System

The integrated cold box and demethanizer system as one of the most critical production sections in an ethylene plant couples multistage refrigeration and cryogenic separation to extract hydrogen and methane from the cracked gas feed. Ethylene and the heavier components are liquefied for recovery in the downstream process. During separation, ethylene contained in the methane and hydrogen streams is accounted as the product loss which in reality is significant. To reduce the ethylene loss with energy consumption consideration, a systematic methodology has been developed to optimize the process operation of the integrated cold box and demethanizer system. It covers rigorous simulation model development and validation, sensitivity analysis, operational optimization, and result analysis. The optimization results demonstrate the significant economic benefits of the proposed methodology.     

机械力化学法制备钛酸钡粉体

采用等摩尔比的BaCO_3和TiO_2粉体作为前驱物,利用高能球磨法球磨10h,XRD结果表明在球磨过程中,粉体颗粒大大细化,将球磨后的混合物在较低的温度下(<900℃)煅烧即可合成纯相的立方BaTiO_3粉体,当温度提高到1100℃,合成了四方相BaTiO_3粉体,在>1100℃煅烧时,晶粒尺寸急剧增大。     

Energy Minimization in Cryogenic Packed Beds during Purification of Natural Gas with High CO2 Content

Minimization of energy consumption was explored for countercurrent switched cryogenic packed beds in which separation of CO₂ and other components of natural gas can be achieved based on differences in freezing or desublimation points. Highly pure CO₂ and methane were obtained after separation. An experimental setup for CO₂ removal from natural gas was constructed and a detailed experimental study was conducted by changing different operating parameters. Compared to other cocurrent or jacket‐cooled constant‐temperature configurations, countercurrent switched beds provided optimal separation and energy efficiencies. The effects of important process parameters like initial temperature profiles of the cryogenic bed, feed composition, and feed flow rate on energy requirement, bed saturation, bed pressure, and cycling times were investigated. The energy requirement for cryogenic packed beds was compared with the conventional cryogenic distillation process.     

The Effects of Operating Conditions on the Milling of Microcrystalline Cellulose

There is little detailed work relating the physical process that occurs during milling to the mechanical properties and mechanism of particle breakage. Very often, the selection of an appropriate mill and subsequently the determination of its optimum operating conditions are by trial and error. This paper look into optimizing the operating conditions of a ball mill through statistical analysis and the effect of temperature on the milling behavior of a common pharmaceutical excipient, microcrystalline cellulose (MCC). In addition, the bulk milling behavior of MCC is compared to its single particle breakage behavior. In this work, milling is conducted in a Retsch single ball mill where a bed of powder is subjected to impact by a steel ball in a horizontal cylindrical container. The container is vibrated horizontally at a set frequency, causing the ball to impact on the bed of particles. It is found that the finest MCC product can be achieved by milling a 2 g batch of material using a 12 mm ball size and at a frequency of 18 Hz. Temperature is found to have insignificant effect on the extent of breakage of MCC in both bulk milling and single particle impact testing. Milling and single particle impact experiments have both shown that MCC is more susceptible to breakage with increasing strain rate. In conclusion, the single impact tests could be used successfully for predicting the bulk milling behavior of the material, as shown in the case of MCC.     

低温阀门闸板应力场的数值计算及分析

在对低温闸板结构进行简化后,采用有限元法开发了应力分析软件,对应力、位移场进行了数值模拟,并绘制了应力等值线图、位移图和应力变化曲线图,探讨了应力与变形的规律,为进一步完善低温闸板的设计提供了理论依据。     

C．F．布朗深冷净化系统模拟分析

通过模拟计算对深冷净化系统做了深入的分析，研究了深冷净化系统脱除甲烷化气中过量氮、甲烷、惰气和回收弛放气中氢的能力，甲烷化气组成和压力对净化效果和操作稳定性的影响。