Modeling of unsteady filtration gas combustion

Unsteady filtration gas combustion with various gas flow parameters is studied by mathematical modeling. Transition processes due to a sudden change in the calorific value of the gas mixture, gas flow velocity, and flow direction are considered. Trends and mechanisms of change in the structure of the filtration gas combustion wave and its propagation velocity are analyzed for various types of transition processes. It is found that with a sudden change in gas flow parameters, the flame can abruptly move large distances in the porous medium. Subsequently, at the new flame localization, a wave of filtration gas combustion forms which corresponds to the changed parameters of the gas flow. If in the porous medium, the amount of heat is insufficient, the transition process ends with quenching. As the gas flow direction changes, the combustion wave continues to propagate in the former direction for some time, which can lead to the spread of the high-temperature zone in devices based on the reverse process with a homogeneous gas-phase reaction.     

Anisotropic membrane materials for gas separations

To date the design of membranes for gas separations has relied on isotropic materials that control the magnitude of mass flux. However, mass flux is a vector quantity and controlling its direction is essential for complete manipulation of diffusion processes. In this article, we show how anisotropic materials enable control of mass flux direction in membranes and allow for novel mechanisms for gas separation. We present a detailed study of the design parameters that control membrane selectivities and permeances and demonstrate that this new class of membranes can provide a new avenue to obtain significant improvements with respect to isotropic materials. We also discuss how the proposed anisotropic membranes can be constructed using isotropic materials. Mass diffusion principles for gas separations in anisotropic membranes are different from those in isotropic materials and this novel strategy for the design of membranes can open new opportunities in membrane separation processes.     

己内酰胺生产技术及应用

介绍了己内酰胺生产工艺和市场情况，并对各种生产工艺进行了比较，并指出立足于技术进步，进行扩容改造是我国己内酰胺的发展方向。     

Orientation of amorphous poly(ethylene terephthalate) by tensile drawing,roll-drawing,and die-drawing

Orientation of initially amorphous poly(ethylene terephthalate) films and sheets was carried out by means of tensile drawing in a tensile tester, roll-drawing using a series of four rolling stations, and by die-drawing. The drawing temperature was 80 and 90°C and drawing rate ranged from 2 to 20 cm/min in the different processes. Crystallinity was observed to increase with draw ratio for all these processes. The onset of crystallinity development depends on the drawing rate. The glass transition temperature was essentially constant and crystallization temperature decreased with increasing draw ratio. The trans conformers content was observed to increase with draw ratio at the expense of the gauche conformers for the three processes. The orientation of the trans conformers increases readily from the beginning of draw and saturates rapidly. The orientation of the gauche conformers was negligible. Some differences are observed for the behavior of the 1020 and 730 cm^?1 benzene ring bands, which may be due to differences in the benzene ring configuration at the surface as a result of different deformation mechanisms for the die and roll-drawing. However, further investigations to elucidate this hypothesis are needed. The mechanical properties obtained in the longitudinal direction increased for all the processes. In the transverse direction, the roll and die-drawing processes induced a decrease in modulus and strength with increasing draw ratio, similar to that observed for uniaxial orientation. This indicates that these processes are mainly uniaxial, despite the plane strain nature of the deformation.     

硝基苯废水治理技术的研究进展

硝基苯具有高毒性、难降解性及在环境中的积累性,使得硝基苯污染问题越来越受到科学研究者的关注。硝基苯废水的主要处理方法有物理法、化学法和生物降解法,论述了近年来国内外对这3种处理方法的研究进展,并阐述了今后研究的重点和发展方向。     

贫燃NO_X选择性催化还原技术及其研究进展

简单介绍了脱除ＮＯＸ的催化技术和最新的贫燃ＮＯＸ选择性催化还原技术。着重分析国外在开发贫燃ＮＯＸ选择性催化还原技术过程中所进行的研究工作和目前存在的问题，并指出今后的研究方向     

HDI合成工艺研究进展

论述了六亚甲基-1,6-二异氰酸酯(HDI)合成工艺的现状及主要研究方向,并对各种生产工艺的优缺点进行了分析。着重介绍先由碳酸二甲酯(DMC)胺解法合成六亚甲基二氨基二甲酸甲酯(HDU-1),再催化分解HDU-1制备HDI的绿色非光气合成工艺,并展望了HDI清洁生产工艺的前景。     

国外乙丙橡胶合成新技术进展

综述了国外溶液聚合、悬浮聚合、气相聚合等乙丙橡胶合成技术路线以及合成催化剂、第三单体、生产工艺改进及新型EPDM的开发研究进展，并对几种乙丙橡胶合成路线进行了技术经济分析。     

亲和膜手性拆分技术及手性拆分固膜

阐述了亲和膜拆分技术,包括亲和超滤、纳滤、电渗析、渗析及渗透汽化等在手性拆分领域的应用,对基于对映体间亲和性差异的手性选择膜及基于"形状记忆"的分子印迹拆分膜的最新进展进行了综述,并就今后的发展方向提出建议。     

镀锡板无铬钝化的现状与发展前景

综述国内外镀锡板无铬钝化研究工作,主要涉及锆酸盐、钼酸盐、钨酸盐、硅酸盐、磷酸盐、钛酸盐、稀土金属盐及有机类钝化(如植酸)等,其中研究有较大进展的为锆酸盐钝化和有机类钝化,并提出了镀锡板无铬钝化的发展方向以及前景.     

催化裂化汽提过程的研究方法进展

介绍了近年来催化裂化汽提过程研究方法的现状,主要包括冷态模拟、热态模拟和计算机模拟(流体动力学)。阐述了3种研究方法的相关实例,指明了各类研究方法的优缺点,并详细阐述了冷态模拟和计算机模拟的改进历程,根据现有研究方法的优缺点提出了新的发展方向。     

Effects of loading rate and temperature on domain switching and evolutions of reference remnant state variables during polarization reversal in a PZT wafer

A PZT wafer poled in thickness direction is subject to through-thickness electric field cyclic loads at four different loading rates and four different temperatures. Electric displacement in thickness direction and in-plane extensional strain are measured and plotted during a complete cycle of polarization reversal. Reference remnant polarization and reference remnant in-plane extensional strain are calculated from the measured data. Effects of electric field loading rate and temperature on domain switching process and evolutions of reference remnant state variables are discussed and explained using consecutive two step slow 90° domain switching processes and reduced coercive field at high temperatures.     

Single-site catalysts in the industrial production of polyethylene

This review generalizes the data on the application of single-site catalysts (SSCs) in the industrial production of polyethylene. The history of their industrial application, the basic types of SSCs, the main processes of the production of polyethylene (PE) on the mentioned systems, the largest PE production plants using SSCs, and the application fields of polymers synthesized at these plants are described. The prospects for further development in this direction are discussed.     

数据驱动方法在化工过程故障诊断中的研究进展

数据驱动方法是一种黑箱模型,具有自主挖掘和构建数据内在关系的优点。随着感知设备的发展和计算能力的提升,数据驱动方法在化工过程故障诊断的研究领域体现出了更大的优势。本文介绍了各类数据驱动方法的原理和作用,并分析了其各自的优缺点与实际应用方向,总结得出深度学习和集成学习是数据驱动方法未来研究重点。同时,本文回顾了近五年来国内外数据驱动方法在化工过程故障诊断中的研究与应用,综合分析了现阶段该领域的研究情况,表明将多种数据驱动方法进行组合来解决化工过程问题的思路具有一定的有效性。并进一步给出了关于数据异常、时间滞后等问题的研究方向。最后,本文建议更多地从方法的机理出发对方法进行研究和优化,在未来的研究思考中应更着重于实用性和时效性。     

Analysis of non-spherical polydisperse particle growth in a two-dimensional tubular reactor

Polydisperse aggregate particle growth considering coalescence, coagulation, generation and spatial transport processes is studied in a two-dimensional reactor for the first time. Effects of two-dimensional spatial transport processes, such as convection, diffusion, deposition and thermophoresis as well as nucleation, coagulation and coalescence are of primary interests. An efficient particle dynamics model based on two sets of coupled sectional equations (J. Aerosol Sci. 32 (2001) 565) is used to facilitate the severe computation loads for analyzing the growth of non-spherical polydisperse particles in an axi-symmetric two-dimensional geometry. Fluid dynamics calculations indicate the existence of non-uniform distributions of temperature and flow fields in the radial direction as well as in the axial direction inside the reactor. Particle dynamics simulations also demonstrate the significant inhomogeneous spatial distributions of the characteristics of aggregate particles. The present two dimensional calculations for reactor temperatures and particle size distributions are in agreement with the previous experimental data. The validity of simplified one-dimensional analysis is also evaluated against the present two-dimensional analysis. While the one-dimensional analysis agreed well with the spatially two-dimensional one for the cases of low flow rates, it resulted in significant errors for high flow rates.     

不锈钢表面抛光技术的研究进展

介绍了化学抛光、电化学抛光及复合抛光的特性、优缺点以及如何应用这些工艺技术对不锈钢进行着色前处理,指出了不锈钢表面抛光技术的发展方向。     

国内外石墨换热器的发展与应用研究

叙述了国外石墨换热器的发展概况、性能、生产工艺路线和应用研究。着重分析了国内外制造石墨换热器所采用的新型材料、制造工艺，以及国内外石墨换热器的技术经济参数，指出了我国石墨换热器的发展方向。     

Recent Progress in Regenerated Cellulose Fibers by Wet Spinning

Cellulose is the most abundant and “green” biomass resource on earth and gains tremendous attention. It is expected to become an alternative for traditional chemical and petroleum resources. This review describes the traditional solvents used for industrial processes, the non-derivative organic solvents, and the aqueous solution systems, along with their dissolution mechanisms and development of fiber-spinning processes. The problems associated with the industrial production of viscose fibers and cuprammonium fibers are also discussed. This paper focuses on the research status of regenerated cellulose fibers (RCFs) prepared with green and no-pollution aqueous solutions and provides some effective strategies and methods for improving the mechanical strength of RCFs and promoting the implementation of industrial production. Lastly, the current developments of RCFs are summarized and prospected and it would serve as a guide for the developmental trend and research direction of RCFs in the future.     

纳米级二氧化钛粉体的制备方法和发展趋势

介绍了纳米级TiO2 的制备方法和研究现状 ,讨论了气相法和液相法合成纳米级TiO2 的优缺点 ,指出当前纳米级TiO2 的主要研究方向。我国应加快开发适合国情的纳米级TiO2 生产新工艺     

Characterization of particle size evolution of the deposited layer during electrostatic powder coating processes

This experimental study investigated particle size evolution in deposited layers during typical electrostatic powder coating processes, using two powder (coarse and ultrafine) systems. Results disclosed that powder coating is a size-selective process in which the motions of in-flight particles are size-dependent. As a result, particles deposited on different regions of the substrate present some size discrepancy which accounts for a size-decreasing tendency along radial direction for both powders. In comparison with coarse powder, however, ultrafine powder can greatly alleviate the size discrepancy. Furthermore, it was also revealed that, due to the size-selective effect, locally deposited particles are with narrower size distributions than the original particles. The study still demonstrated that small particles are more prone to adhere on the substrate in coarse powder coating processes while large particles take the priority to deposit in ultrafine powder coating processes, due to different dominant factors. However, because of the intensifying back corona, the deposited particles show a size-decreasing tendency with extended spraying duration, which is commonly exhibited in both coarse and ultrafine powder coating processes. Nevertheless, in this study it was also found that charging voltage plays a limited influence on the size evolution.