氟烃抛射剂HFC-152a在低VOCs型气雾剂中的应用

1前言 二十世纪七十年代．人们发现氯氟烃是破坏大气臭氧层的元凶．并预期会对全球生态环境产生严重影响．从而引发了淘汰氯氟烃和相关化学物质的全球行动。中国也严格按照《蒙特利尔议定书》和《中国消耗臭氧层物质逐步淘汰的国家方案》的要求,对CFCs的生产消费进行了削减和淘汰,同时大力支持国内企业开发和生产ODS替代物。     

微乳型厨房除油污气雾剂的研制

本文阐述了厨房油垢的成因以及常用的洗涤方法、将溶剂的渗透、溶解性能和表面活性剂的渗透、润湿、乳化性能结合,研制一种微乳型的弱碱性厨房清洗剂,在弱碱性条件下达到较好的去油污效果,对环境友好,而且具有光亮功能。选用合适的抛射剂和防锈剂制成气雾剂,解决了洗涤剂对马口铁罐的腐蚀问题。     

Creeping film model for condensed centrifugal separation processes

In a new process of separating high concentrations of gaseous contaminants like water vapor, CO₂ and H₂S from well gas streams, the contaminants are condensed and subsequently removed in a centrifugal separator. This paper presents an analytical model for the formation of a thin liquid film inside the small channels of a vertically oriented rotating phase separator. Film behavior is investigated under the combined influence of centrifugal and gravitational forces. At high gas throughput the shear forces at the interface between the gas flow and the liquid film, and the resulting pressure drop over the channel, are considered as well. The gas velocity through the channels is corrected for the displacement effect of the liquid film. Solutions are presented for several channel heights at various operating conditions, and for gas flow in upward and downward direction.     

Deactivation of V2O5-WO3-TiO2 SCR catalyst at biomass fired power plants: Elucidation of mechanisms by lab- and pilot-scale experiments

In this work, deactivation of a commercial type V₂O₅-WO₃-TiO₂ catalyst by aerosols of potassium compounds was investigated in two ways: (1) by exposing the catalyst in a lab-scale reactor to a layer of KCl particles or fly ash from biomass combustion; (2) by exposing full-length monolith catalysts to pure KCl or K₂SO₄ aerosols in a bench-scale reactor. Exposed samples were characterized by activity measurements, SEM-EDX, BET/Hg-porosimetry, and NH₃ chemisorption. The work was carried out to support the interpretation of observations of a previous study in which catalysts were exposed on a full-scale biomass fired power plant and to reveal the mechanisms of catalyst deactivation.Slight deactivation (about 10%) was observed for catalyst plates exposed to a layer of KCl particles at 350 °C for 2397 h. No deactivation was found for catalyst plates exposed for 2970 h to fly ash (consisting mainly of KCl and K₂SO₄) collected from an SCR pilot plant installed on a straw-fired power plant. A fast deactivation was observed for catalysts exposed to pure KCl or K₂SO₄ aerosols at 350 °C in the bench-scale reactor. The deactivation rates for KCl aerosol and K₂SO₄ aerosol exposed catalysts were about 1% per day and 0.4% per day, respectively.SEM analysis of potassium-containing aerosol exposed catalysts revealed that the potassium salt partly deposited on the catalyst outer wall which may decrease the diffusion rate of NO and NH₃ into the catalyst. However, potassium also penetrated into the catalyst wall and the average K/V ratios (0.5–0.75) in the catalyst structure are high enough to explain the level of deactivation observed. The catalyst capacity for NH₃ chemisorption decreased as a function of exposure time, which reveals that Brønsted acid sites had reacted with potassium compounds and thereby rendered inactive in the catalytic cycle. The conclusion is that chemical poisoning of active sites is the dominating deactivation mechanism, but physical blocking of the surface area may also contribute to the loss of activity in a practical application. The results support the observation and mechanisms of deactivation of SCR catalysts in biomass fired systems proposed in a previous study [Y. Zheng, A.D. Jensen, J.E. Johnsson, Appl. Catal. B 60 (2005) 253].     

Canonical form and mathematical interpretation of electrolyte solution systems

We describe a canonical form of electrolyte solution systems for the mathematical interpretation of solidliquid equilibrium. The canonical form is obtained from the analysis of the algebraic structure of electrolyte solution systems and the Karush-Kuhn-Tucker (KKT) conditions for the minimization of the total Gibbs free energy. As a result, the mathematical role of solid species in the solid-liquid equilibrium problem is explained as a Lagrange multiplier of a sort of the linearly constrained optimization problem. This finding will add to the development of an efficient numerical algorithm for the simulation of electrolyte solution systems. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Seasonal variation of columnar aerosol optical properties over Athens, Greece, based on MODIS data

A long-term (2000–2005) data set of aerosol optical properties obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) is analyzed focusing on the Greater Athens Area in the Eastern Mediterranean region. The MODIS aerosol optical depth standard product (AOD at 550 nm) and its respective ratio attributed to fine-mode particles (FM) are employed to evaluate the inter-annual and seasonal variability of the aerosol properties over Athens. Based on AOD₅₅₀ and FM values three specific aerosol types are discriminated corresponding to different aerosol load and optical properties. The aerosol types considered correspond to urban/industrial aerosols, coarse-mode particles and clean maritime conditions. This study focuses on the seasonal and year-to-year fluctuation of the number of occurrences as well as the AOD₅₅₀ and FM values of each aerosol type. The coarse-mode particles are observed mainly in the summer, while spring is the most favorable season for the occurrence of urban/industrial aerosols. On the other hand, clean maritime conditions occur mainly in the winter. The AOD₅₅₀ values for the coarse-mode particles are higher in spring, while the urban/industrial and clean maritime aerosols exhibit slightly higher values in the summer. The seasonal distribution of the aerosol properties is related to anthropogenic and dust emissions in the spring/summer period, but is modified by atmospheric dispersion and precipitation in late autumn/winter. The main conclusion of the study is that the coarse-mode particles exhibit much stronger inter-annual and seasonal variability compared to the urban/industrial aerosols. Finally, three cases corresponding to each aerosol type are analyzed with the aid of synoptic weather maps, air mass trajectories and MODIS data.     

用β吸收法测定空气中粉尘质量的实验研究

研究了大气中的普通粉尘质量与β射线的吸收关系。对两组共20个样品的测量结果进行分析表明,收集在滤纸上的粉尘质量与β射线吸收实验之间存在着一定的比例关系,其相关系数为0．96。本工作为利用β吸收法自动测定空气中的粉尘质量浓度提供了数据。另外,对于空气湿度以及滤纸均匀性对测量的影响也进行了实验和讨论。     

快中子脉冲反应堆厅内空气中裂变产物污染的研究

本文研究了快中子脉冲反应堆大厅内空气中裂变产物的污染问题。通过对ＣＦＢＲ－Ⅱ快中子脉冲反应堆爆发额定产额脉冲（１．５３×１０１６裂变）后，厅内气溶胶的取样和γ谱分析，确定了裂变产物从黄铜壳内空气中释放到厅内空气中形成气溶胶的释放份额为５×１０－３。利用此释放份额计算了厅内空气中不同放射性核素的气溶胶浓度；还计算了该堆爆发额定产额脉冲后不同冷却时间ｔ厅内空气中无分凝混合裂变产物的导出空气浓度ＤＡＣ（ｔ）值，为该堆辐射安全分析和现场辐射防护提供了依据。     

Aerosol characterisation in Italian towns by IBA techniques

The composition of particulate matter in the atmosphere of four major Italian towns (Florence, Genoa, Milan and Naples) has been studied with the extensive application of IBA techniques. The aerosol has been collected simultaneously in the four towns during the first weeks of year 2001, by two-stage continuous streaker samplers, which provide the separation of the particulate matter in two fractions. The concentrations in air of about 20 elements, and the total particulate mass, have been extracted in the PM2.5 and PM10 fractions with hourly resolution by PIXE, PIGE and optical analyses of about 2700 samples. IBA analyses have been performed at the 3 MeV external proton beam of the INFN accelerator facility at the University of Florence.     

用于放射性气溶胶在线富集进样的狭缝虚拟撞击器的研制

为满足环境气溶胶在线进样的要求,改善电感耦合等离子体质谱计(Inductively Coupled Plasma Mass Spectrometry,ICP蛳MS)对粒子中待测核素的探测限,研制出一套具有低流量、低压降特点的狭缝虚拟撞击器,可作为气溶胶在线富集进样系统的关键部件与ICPˉMS联用。本文介绍了该狭缝虚拟撞击器的研制情况:首先由ICP蛳MS的进样条件,根据经验公式完成了理论设计,确定进样流量为11L/min,强流与弱流的流量比为10,喷射狭缝宽度为1mm,长宽比为10;然后用计算流体动力学软件Fluent R对上述结构内部的流场和粒子运动径迹进行了数值模拟,考察了喷射狭缝与收集狭缝的间距G、收集狭缝的宽度Wc及其进口曲率半径的加工偏差对收集效率的影响,得到了较优化的取值范围:G取1.0～1.2mm,Wc取1.4～1.6mm,此时的切割粒径D50约2.5μm;加工出狭缝虚拟撞击器的原型装置,对其分别用室内空气气溶胶和荧光素钠标记的单分散油酸粒子进行富集性能测量。实测结果表明:空气动力学等效直径在2.5～5μm范围内的粒子浓度得到了明显富集,5μm的粒子的富集因子达到极大值7。