Marketing issues related to waste-grown aquatic foods

Environmental Management - Are societal wastes all bad? Some of them, including heat from power plants and certain organic wastes, have been demonstrated to be potentially valuable for growing...     

关于建立资源与环境快速反应系统的探讨

本文阐述了国家快速反应系统的概念及其作用。以建立资源与环境快速反应系统为例,说明建立系统的必要性、系统的内容、组成及技术指示。     

Modeling thermal analysis for predicting thermal hazards relevant to transportation safety and runaway reaction for 2,2′-azobis(isobutyronitrile)

The pure decomposition behavior of 2,2′-azobis (isobutyronitrile) (AIBN) and its physical phase transformation were examined and discussed. The thermal decomposition of this self-reactive azo compound was explored using differential scanning calorimetry (DSC) to elucidate the stages in the progress of this chemical reaction. DSC was used to predict the kinetic and process safety parameters, such as self-accelerating decomposition temperature (SADT), time to maximum reaction rate under adiabatic conditions (TMR_ad), and apparent activation energy (E_a), under isothermal and adiabatic conditions with thermal analysis models. Moreover, vent sizing package 2 (VSP2) was applied to examine the runaway reaction combined with simulation and experiments for thermal hazard assessment of AIBN. A thorough understanding of this reaction process can identify AIBN as a hazardous and vulnerable chemical during upset situations. The sublimation and melting of AIBN near its apparent onset decomposition temperature contributed to the initial steps of the reaction and explained the exothermic attributes of the peaks observed in the calorimetric investigation.     

The influence of ClO− and acidity in the reaction between H2O2 and CuCl2

The potentially explosive reaction of hydrogen peroxide (H₂O₂) and copper chloride (CuCl₂) was investigated. Pressure tests revealed that the reaction was strongly temperature - dependent and can easily undergo runaway reaction. Nevertheless, there was only a slight pressure increase at the low temperatures studied or when using low concentrations of CuCl₂. Under the conditions generating the slight pressure increase, hypochlorite anions (ClO⁻) are generated and the acidity increases. As the reaction reaches completion, ClO⁻ disappears, and the acidity decreases. Interestingly, the addition of phosphate buffer to maintain the weakly acid conditions led to a runaway reaction, and the use of basic ClO⁻ promoted the exothermic reaction. Based on the results, acidity has a strong impact on the reaction behaviour.     

Thermal hazard accident investigation of hydrogen peroxide mixing with propanone employing calorimetric approaches

Hydrogen peroxide (H₂O₂), historically, due to its broad applications in the chemical industries, has caused many serious fires and explosions around the world. Its thermal hazards may also be incurred by an incompatible reaction with other chemicals, and a runaway reaction may be induced in the last stage. This study applied thermal analytical methods to explore the H₂O₂ leading to these accidents by incompatibility and to discuss what might be formed by the upset situations. Thermal hazard analysis contained a solvent, propanone (CH₃COCH₃, so-called acetone), which was deliberately selected to mix with H₂O₂ for investigating the degree of thermal hazard. Differential scanning calorimetry (DSC) and vent sizing package 2 (VSP2) were employed to evaluate the thermal hazard of H₂O₂. The results indicated that H₂O₂ is highly hazardous while mixed with propanone, as a potential contaminant. The time to maximum rate (TMR) was used as emergency response time in the chemical industries. Therefore, TMR of H₂O₂ was calculated to be 70 min for runaway reaction (after T₀) and TMR of H₂O₂/propanone was discovered to be 27 min only. Fire and explosion hazards could be successfully lessened if the safety-related data are properly imbedded into manufacturing processes.     

Alternative method to prevent thermal runaway in case of error on operating conditions continuous reactor

Thermal runaway was studied in a continuous tubular pilot reactor under steady-state regime. Different accident scenarii were conducted by making some errors on reactant concentrations and/or temperature feed. To prevent thermal runaway, control by direct contact by solvent injection was used at different reactor locations. This injection allowed controlling the maximum reaction temperature. A simplified analytical method to estimate the maximum reaction temperature along the reactor was used.Benefit of this control method was the diminution of computational time. Furthermore, by injecting solvent to control maximum reaction temperature, there is no need to shut down the unit. The control method was validated experimentally.     

煤矿照度对人反应时间和可靠度的影响研究

煤矿综采工作面狭窄,工作环境昏暗,照明环境普遍不好,是近年来井下事故多发的重要因素之一。针对目前煤矿综采工作面存在的照度问题,通过控制光照时间和操作难度,利用舒尔特表测算反应时间和操作可靠度,使用SPSS20. 0和Excel进行数据处理,设计试验组和对照组来进行对比试验。结果表明,1)从反应时间来看,0～25 min,试验组平均反应时间的变化趋势与对照组相反,被试者的注意力先下降后上升; 25～55 min,被试者逐渐适应低照度环境,反应时间也在逐渐缩短;被试者在低照度条件下操作55 min后,反应时间随光照时间增加而大幅度增加,超过劳动时间临界值后,视觉疲劳度迅速增加,反应急速减慢,从而可能导致安全事故的发生,影响生产效率,此时应合理安排工人休息。2)从操作难度来看,在简单及正常操作难度时,试验组和对照组操作可靠度变化比较接近,表明低照度条件对一般操作的可靠度影响不明显;在极难操作难度时,低照度条件对可靠度影响明显,在井下生产过程中,低照度环境下应尽量避免安排复杂的机械化操作。3)反应时间与光照时间呈二次函数关系,通过建立回归方程量化了两者的关系,为以后合理安排煤矿工人劳动休息时间提供了理论依据。     

二氧化硫与环己烷的光化学反应

本文研究了ＳＯ２与环己烷在无氧及有氧体系中的光化学反应，观察到了白色烟雾有生成并凝聚，利用ＧＣ和ＧＣ／ＭＳ法确定了部分反应产物－环烯烃、醇、酮、二元酸酯、呋喃衍生物以及硫酸二甲酯等有机化合物，探讨了影响光化学反应的几种因素及反应机理。     

聚合氯化铝铁絮凝剂的性能研究

煤矸石是采煤过程之废料。本文利用煤矸石制备出了聚合氯化铝铁（ＰＡＦＣ）：一种新型无机高分子絮凝剂，探讨了Ｆｅ＾３＋的稳定性与溶液离子强度之间的关系，发现溶液的离子强度越大，则产生Ｆｅ（ＯＨ）３沉淀时的ＰＨ越高。研究了ＰＡＦＣ水解产物的ζ电位及絮凝效果随ＰＨ的变化情况，比较了ＰＡＦＣ、ＰＡＣ和ＰＦＳ的除浊性能，ＰＡＦＣ在ＰＨ为７．０－８．２范围内除浊效果最佳，ＰＡＦＣ的除浊效果优于ＰＡＣ。