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181.
Maintaining an adequate air flow with a desired air quality that is free from hazardous gases is among the most important actions taken toward the improvement of safety in any process plant. Due to the increased focus on the consequences of existing hazardous material on safety, health, and the environment, air quality and sufficient ventilation within a plant has been increasingly considered in the design stage. This paper investigates and analyzes methane and hydrogen sulfite dispersion and the effect of air ventilation within a CAD model of an offshore platform using computation fluids dynamics (CFD). In addition, this method and its principals could be utilized in any other hazardous environment. Simulations of possible hazardous events along with solutions for preventing or reducing their probability are presented to better assess the data. These investigations are performed by considering hypothetical hazardous scenarios which consist of gas leakages from pipes and process equipment under different conditions. After drafting a precise and highly detailed CAD model of the plant and performing CFD simulations on this model, the results of gas behaviors, dispersion, distribution, accumulation, and its possible hazards are investigated and analyzed. The larger amount of details of the actual plant model in CFD simulation are obtained by using a combination of different methods and software. These include PDMS for 3-D drawing of the plan, Rinoceros for geometrical integration of the process equipment and facilities, and Sharc Harpoon which meshes the model. Moreover, the probability of inducing ignitable or toxic concentration of gases within the atmosphere and air ventilation of the unit is considered by these investigations. 相似文献
182.
Chunmei Gong Jiajia Wang Congxia Hu Junhui Wang Pengbo Ning Juan Bai 《环境科学学报(英文版)》2015,27(8):184-196
C4 plants possess better drought tolerance than C3 plants. However, Hedysarum scoparium, a C3 species, is dominant and widely distributed in the desert areas of northwestern China due to its strong drought tolerance. This study compared it with Haloxylon ammodendron, a C4 species, regarding the interactive effects of drought stress and different leaf–air vapor pressure deficits. Variables of interest included gas exchange, the activity levels of key C4 photosynthetic enzymes, and cellular anatomy. In both species, gas exchange parameters were more sensitive to high vapor pressure deficit than to strong water stress, and the net CO2 assimilation rate (An) was enhanced as vapor pressure deficits increased. A close relationship between An and stomatal conductance (gs) suggested that the species shared a similar response mechanism. In H. ammodendron, the activity levels of key C4 enzymes were higher, including those of phosphoenolpyruvate carboxylase (PEPC) and nicotinamide adenine dinucleotide phosphate-malate enzyme (NADP-ME), whereas in H. scoparium, the activity level of nicotinamide adenine dinucleotide-malate enzyme (NAD-ME) was higher. Meanwhile, H. scoparium utilized adaptive structural features, including a larger relative vessel area and a shorter distance from vein to stomata, which facilitated the movement of water. These findings implied that some C4 biochemical pathways were present in H. scoparium to respond to environmental challenges. 相似文献
183.
含硫气田在天然气开采、管道批处理、气田污水处理过程中,由于高压气流携带井底岩屑、单质硫析出、工艺添加的化学药剂反应产生沉淀物等因素,会产生一些成分复杂、有恶臭气味的固态物质,统称为采气污泥,影响生产安全和工艺参数调配,需要及时清理并无害化处置。结合固废减量化、无害化、资源化的处置原则,立足于企业自行处置的目的,本文就含硫气田采气污泥特性以及无害化处理的方法进行研究,对处理效果进行了分析,对废物综合利用进行了有益的尝试,为今后含硫气田污泥处理提供了一条可借鉴的思路。 相似文献
184.
建立了简便、快速、有效的分散液液微萃取(DLLME)-气相色谱/质谱技术萃取水样中痕量阿特拉津的新方法。通过试验确定最佳萃取条件。 相似文献
185.
This paper discusses a procedure for case studies of accidental gas explosions. The procedure for each case study can be subdivided into four steps, i.e., collection of proofs, analyses, confirmation, and inference about the processes of the accident, and the issues in each step are pointed out. Making a guess on the sequence of the accident to be investigated should be avoided during collection of proofs. Misunderstanding of the phenomena in analyses and confirmation is likely caused by inappropriate knowledge on the phenomena and/or use of unsuitable models. The sequence of the accidental gas explosion should be inferred on the basis of confirmed processes. If there are other possibilities, those should be described in the report. The reasonableness of the results of a case study depends on the rationality of the procedure and the quality or plausibility of knowledge to infer the probable sequence. 相似文献
186.
The numerical simulation of gas dispersion is of great importance in various areas of engineering such as optimisation, synthesis of chemical process, petroleum industry and process safety. The OpenFOAM (Open Field Operation and Manipulation) code is a free and open source computational fluid dynamics (CFD) program. The current research is focused on the development and customisation of a computational tool for handling gas dispersion of heavy gases, such a LNG and CO2. The novel CFD tool relies on OpenFOAM framework. The core of the work is based on the OpenFOAM solver rhoReactingBuoyantFoam to handle gas dispersion. A series of CFD simulations has been performed for methane and CO2. The source term of the former is modelled by HSM (Hybrid Switch Model). The model comprises contribution from HEM (Homogeneous Equilibrium Model) approach, frozen model and non-equilibrium model for CO2 leak. The novel approach switches between equilibrium and non-equilibrium conditions based on the meta-stable parameter on the grounds of thermodynamics and experimental observations. Good agreement with experimental data is observed. Numerical findings for methane leakage from the proposed CFD tool are compared with experimental data and FLACS. Good agreement is observed. 相似文献
187.
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189.
运用模糊系统理论,按照瓦斯危险状态存在的模糊客观性,提出了瓦斯危险状态评价语言因于描述方法;结合提出的矿井瓦斯危险状态程度及其存在程度的可能性度量方法,构成了瓦斯危险状态评价的多值化描述方法,而且包含了更多的状态描述信息,对指标间相互关联制约作用进行了进一步的研究,挖掘了指标间相互关联制约对评价结论的本质影响. 相似文献
190.
使用寿命长的微孔薄膜复合滤料过滤石灰窑气,把温度控制在78~200℃之间。过滤风速小于2.50m/min以内,就可以确保净化后的窑气含尘浓度达标。 相似文献