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461.
本文采用顶空-固相微萃取-毛细管气相色谱联用技术测定了洗涤制品中二噁烷量,使用50μmPEG/树脂萃取头。顶空平衡温度为80℃,萃取时间为40min。使用石英毛细管柱:30m×0.32mm×0.4μmi.d.内壁涂有5%二苯基(95%)二甲基硅氧烷固定液。外标法定量,二噁烷测定结果的相对标准偏差(RSD)为9.33%;在0.35μg/g~120μg/g范围,色谱峰面积与质量浓度之间呈良好线性关系,线性相关系数(R)为0.9998;回收率为98.7%~102%。 相似文献
462.
采用活性炭采样管吸附环境空气中的糠醛,以CS2解析,用Rtx-WAX毛细管柱分离,氢火焰离子化检测器检测,气相色谱仪测定。方法最低检出质量浓度糠醛0.006mg/m3,加标回收率在90%以上,方法安全,简单灵敏,分离度好,检出限低。 相似文献
463.
Having a risk analysis of harmful releases over mountainous terrains through wind tunnel experiment is a frontier problem in China. In this paper, a straight-flow wind tunnel is applied to simulate the atmospheric boundary layer and research the motion of high-sulfur gas released to atmosphere when accidental releases occur in a gathering station over the mountainous terrain. After an analysis of hourly concentration in the field accident for eight wind directions, experimental results reveal that nearby concentration fields are dominated by wind and far-field concentration distribution is dominated by topography, which leads to complete levels of consequence impact for the personnel risk inside and around the gathering station. Based on CFD techniques, a three-dimensional modelling was established in comparison with the wind tunnel experiment, which suggests that CFD prediction had underestimated the near-field gas concentration and the performance could not precisely match actual risks the gathering station causes to the mountainous terrain, which leads to a modified equation for numerical prediction. Instead of proposing a lower personnel risk evaluation obtained through the use of CFD techniques, the wind tunnel experiment offers a new choice for the consequence impact analysis for the petrochemical industry in China. 相似文献
464.
A physical and mathematical model of the reduced kinetics is presented describing heterogeneous detonation in suspensions non-uniform in particle concentration. The model is based on the heterogeneous media approaches, semi-empirical laws of ignition and combustion, and data on the dependence of the detonation velocity on particle concentration. Formation of suboxides and incomplete combustion of aluminum are taken into account integrally. The dependence of the heat release of chemical reactions and the fraction of unburnt particles on the initial composition is determined from the solution of the stationary problem of the structure of the detonation wave. In the calculations of unsteady detonation flows, it is supposed to solve an additional equation for the spatial distribution of initial concentrations. The problems of initiation and development of cellular detonation in flat channels in suspensions of micron-sized aluminum particles are studied. Dependences of the cell size on particle concentration in uniform suspensions are determined. The flow patterns of cellular structures, the forms of the leading front, and the propagation velocities in channels with longitudinal or transversal gradients of particle concentration are analyzed. 相似文献
465.
Hazardous extent predictions that ensure process safety while avoiding overestimation have been a challenge for hazardous area classification. Specific leak scenarios can be addressed to build rapid empirical models to accurately determine hazardous extent considering several factors that are not included in general approaches. In view of that, this work aims to propose a novel CFD-based empirical model for gas emissions in open and unobstructed areas. It considers a wide range of variables such as storage temperature and pressure, orifice diameter, molecular weight, gas concentration, and wind velocity. A sensitivity analysis was performed to evaluate each variable's contribution to the gas cloud extent. The linear regression model resulting from the combination of all variables contribution was coupled with Ewan and Moddie's model to minimize the prediction errors due to the non-monotonic wind effects. The suggested algorithm accurately calculates the hazardous extent with a coefficient of determination equals to 0.9842 and a RMSE of 0.0151 for a dataset of 600 cases of generic gases release. The proposed model was also validated for 60 cases of hydrogen releases under different storage conditions, giving a coefficient of determination equal to 0.9829 and a RMSE of 0.0680, indicating a good agreement with the data. 相似文献
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In this paper, heavy gas diffusion in a confined space has been investigated. The effects of barrier and source intensity on CO2 diffusion are explored by the small-scale experiments and computational fluid dynamics (CFD) methods. Six different turbulence models are selected to predict the gas concentrations. By comparing these experimental values with the simulated ones, it is found that all models can effectively predict the concentration variation with time, and SST k-ω model is most close to the ideal model compared with others. Three source-barrier distances and three CO2 flow rates have been set up for the study. In this confined space, the main flow is concentrated in the region near the ground. The existence of barriers in the space will have a dilution effect on the high-concentration plume near the ground of the near-source area and a barrier effect on the low-concentration plume in the far-source area. The changes in source intensity have notable impact on the gas concentrations. This study can provide an experimental basis for the risk assessment in the confined spaces, as well as an experimental and data reference for large-scale CFD simulations. 相似文献
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470.
The article focuses on analyzing risks associated with the gas transfer operation in a liquified petroleum gas (LPG) bottling plant in India. The transfer operations involve transferring liquified gas from the transport tanker to the underground storage tank. Due to the rapid expansion of the cities, many LPG bottling plants in India got surrounded by residential areas and business centers. Moreover, to maintain the supply chain, the frequency of the transfer operations at the bottling plant also increased. In this scenario, an accidental release of LPG during the transfer operation may lead to various consequences such as a pool fire, a fireball, and even a catastrophic rupture of the tank with a successive explosion of its contents. In the study, the operations involved in bottling plants are classified into different hazard zones and analyzed. The probability of occurrence of events leading to an accident is modeled using modeling tools such as ALOHA and PHAST. The consequences of an accident following various events, such as jet fire, fireball, etc., are modeled, and the simulation results are compared. The thermal radiation has been estimated as 4–40 kW/m2, which could adversely affect the nearby population and could result in damaging plant machinery and equipment. 相似文献