压裂返排液生物处理实验研究

从油田压裂返排液中筛选出EB系列菌种,可高效降解压裂返排液中的高分子和有机污染物。考察了振荡时间、温度、接种量、菌种混合比例等对压裂返排液COD去除率的影响。结果表明:48h振荡、25℃、10%接种量、菌种EB1和EB2按1∶1比例混合是较佳应用条件。EB复合菌种的应用范围较广,其pH值适用范围为6～9,矿化度适用范围为3 000～20 000mg/L。该研究提高了压裂返排液生物处理技术规模化应用的可行性。     

CFD simulations of dust dispersion in the 20 L vessel: Effect of nominal dust concentration

Measurements of flammability and explosion parameters for dust/air mixtures require uniform dispersion of the dust cloud inside the test vessel. In a previous work, we showed that, in the standard 20 L sphere, the dust injection system does not allow generation of a uniform cloud, but rather high gradients of dust concentration are established. In this work, we used a previously validated three-dimensional CFD model to simulate the dust dispersion inside the 20 L sphere at different dust nominal concentrations (and fixed dust diameter). Results of numerical simulations have shown that, as the dust nominal concentration is increased, sedimentation prevails and, thus, when ignition is provided, the dust is mainly concentrated at the vessel walls.     

Analysis of gas dispersion and ventilation within a comprehensive CAD model of an offshore platform via computational fluid dynamics

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.     

Experimental data and CFD performance for cloud dispersion analysis: The USP-UPC project

Forecasting the behaviour of a flammable or toxic cloud is a critical challenge in quantitative risk analysis. Recent literature shows that empirical and integral models are unable to model complex dispersion scenarios, like those occurring in semi-confined spaces or with the presence of physical barriers. Although CFD simulators are promising tools in this regard, they still need to be fully validated with comprehensive datasets coming from experimental campaigns designed ad-hoc. In this paper, we present an experimental campaign carried out by a joint venture between University of São Paulo and Universitat Politècnica de Catalunya to investigate CFD tools performance when used to analyse clouds dispersion. The experiments consisted on propane cloud dispersion field tests (unobstructed and with the presence of a fence obstructing the flow) of releases up to 0.5 kg s⁻¹ of 40 s of duration in a discharge area of 700 m². We provide a full 1-s averaged propane concentration evolution dataset of two experiments, extracted from 29 points located at different positions within the cloud, with which we have tested FLACS^® CFD-software performance. FLACS reproduces successfully the presence of complex geometry, showing realistic concentration decreases due to cloud dispersion obstruction by the existence of a fence. However, simulated clouds have not represented the whole complex accumulation dynamics due to wind variation.     

Numerical modeling of water spray suppression of conveyor belt fires in a large-scale tunnel

Conveyor belt fires in an underground mine pose a serious life threat to miners. Water sprinkler systems are usually used to extinguish underground conveyor belt fires, but because of the complex interaction between conveyor belt fires and mine ventilation airflow, more effective engineering designs are needed for the installation of water sprinkler systems. A computational fluid dynamics (CFD) model was developed to simulate the interaction between the ventilation airflow, the belt flame spread, and the water spray system in a mine entry. The CFD model was calibrated using test results from a large-scale conveyor belt fire suppression experiment. Simulations were conducted using the calibrated CFD model to investigate the effects of sprinkler location, water flow rate, and sprinkler activation temperature on the suppression of conveyor belt fires. The sprinkler location and the activation temperature were found to have a major effect on the suppression of the belt fire, while the water flow rate had a minor effect.     

超临界流体技术及其在环境保护中的应用

从超临界流体萃取、超临界水氧化、催化超临界水氧化和超临界流体色谱等四个方面介绍超临界流体技术在环境分析、环境污染治理中的应用和发展方向。     

Prenatal diagnosis of galactosialidosis

The second prenatal diagnosis of galactosialidosis is reported. Neuraminidase and β-galactosidase activities in cultured amniotic cells were deficient, this being confirmed by skin fibroblast enzyme assay on the affected fetus after interruption of the pregnancy. Cultured placental cells demonstrated the same enzyme deficiencies. Analysis of deproteinized amniotic fluid showed the presence of abnormal oligosaccharides specific for a-neuraminidase deficiency.     

Microvillar enzyme assays in amniotic fluid and fetal tissues at different stages of development

A systematic study of microvillar enzyme activities in the amniotic fluid in correlation with their values in different fetal tissues during development has been undertaken. Microvillar enzymes appeared in the amniotic fluid at the time of disappearance of the anal membrane, 12–13 weeks, and declined from the 18th week until the 24th week. The study of fetal tissues and fluids has shown that gamma-glutamyltranspeptidase is mainly of liver origin. The significant decrease of the activities of these amniotic fluid enzymes has been the basis of prenatal diagnosis of cystic fibrosis. These assays may be useful for the diagnosis of certain digestive tract abnormalities at later stages of pregnancy.     

Amniotic fluid-AFP in Down syndrome and other chromosome abnormalities

80·2 Per cent of 111 Down syndrome pregnancies had amniotic fluid (AF) alpha fetoprotein (AFP) levels on or below the median and 10·8 per cent at or below 0·5 MoM compared with 41·9 and 1·4 per cent of controls. These differences were even more striking when the gestational age was < 18 weeks compared with ⩾ 18 weeks. No such association was seen for other chromosome abnormalities including trisomy 18,45,X and mosaics, 47,XXY, 47,XXX, and other structural abnormalities and triploidy, even when high levels due to defects such as omphalocele and cystic hygroma were excluded. All cases of trisomy 13 and 80 per cent with 47,XYY had AF-AFP levels above the median. Selection of cases for karyotyping by a low level of AF-AFP would clearly fail to detect aneuploidies other than Down syndrome and is not recommended. A possible weak association between low maternal serum (MS) and AF-AFPs in Down syndrome was most evident at < 18 weeks, suggesting that MS screening between 16 and 18 weeks may be the most informative time.