基于Fluent的地下管廊液氮灭火数值模拟方法*

为更好地研究液氮的灭火特性,提出基于Fluent软件的地下管廊液氮灭火数值模仿方法,并研究其适用性。首先,搭建缩尺寸地下管廊液氮灭火试验平台,通过改变注氮方向和注氮距离,开展地下管廊液氮灭火试验,以便得到数值模拟所需的输入参数和验证数据;然后,确定基于Fluent软件的数值模拟方法,用该方法开展与试验同工况的数值模拟,并对比二者结果。研究表明:该数值模拟结果与试验数据有较好的一致性;管廊顶棚不同位置处温度的变化趋势与试验一致,误差最低约为4.7%;管廊底部 O₂ 体积分数的模拟效果与注氮距离有关,注氮距离越近,模拟效果越好,误差最低为0.3%,最高为15.3%。     

平朔安太堡矿区复垦地土壤微生物与土壤性质关系的研究

调查安太堡大型露天矿区西排土场植被恢复与土壤微生物的关系.结果表明,土壤中微生物量与土壤中的水分、速效磷、土壤有机质、有效性氮和海拔高度有明显的关系.麦地、林地、草地的土壤中呈现出:细菌》放线菌》固氮菌》霉菌;撂荒地呈现为:细菌》放线菌》霉菌》固氮菌;裸地呈现出:细菌》放线菌》霉菌.细菌、放线菌和霉菌呈现麦地最高,裸地最低,固氮菌为林地高于其他样地.在撂荒地和裸地中,细菌占微生物总量的一半以上.麦地、林地、草地、撂荒地中的各种菌、速效磷、土壤有机质、有效性氮含量明显高于裸地中的含量.微生物总量和样地的海拔、样地土壤的含水率有明显的关系,土壤中的含水量直接影响微生物总量.微生物总量与速效磷含量和有机质含量成正比,有机质含量与有效性氮含量成正比.细菌与海拔呈极显著负相关,与其他几种养分指标呈极显著正相关,放线菌与海拔和速效磷呈极显著相关,与其他指标相关性不显著,固氮菌与几种养分指标相关性均不显著.按全国土壤养分划分标准,安太堡大型露天矿区复垦地等级不高,还需要用科学的方法加快复垦区土壤的恢复.     

活性污泥法的动力学方程讨论及数学模型研究

活性污泥法水处理过程是一个复杂的生化反应过程,伴随有物理化学反应、生化反应、相变过程及物质与能量的转化和传递过程.通过对微生物动力学方程的讨论,进而建立动力学模型,比较了Monod方程和Contois方程分别来模拟有机碳在曝气条件下的生化去除过程.模型主要预测底物浓度、溶解氧、微生物增长等引起的系统响应,为污水处理厂的运行提供指导.     

连续退火机组氮气窒息事故分析及预防对策

介绍了某冷轧厂连续退火机组发生的一起氮气窒息事故,分析了水淬槽氮气产生的机理、事故发生的原因,提出了预防氮气窒息事故的对策措施.     

人工湿地对二级出水中TN、TP去除效果的季节性研究

研究了垂直流和表面流两种人工湿地系统在水力停留时间为2 d条件下,在不同季节对二级出水中TN、TP的去除效果。结果显示,垂直流湿地系统对TN、TP的去除效果优于表面流湿地系统。两种类型的人工湿地对TN的去除效果随季节的变化而波动,夏秋季节去除率最高,春季次之,冬季去除效果最差;垂直流人工湿地系统对TP的去除效果随季节的变化趋势与TN去除率的变化相同,而表面流湿地系统对TP的去除效果在春夏秋季变化不大,冬季的平均去除率仅有16.5%。分析认为,人工湿地应用于二级出水的深度处理,对于满足观赏性景观环境用水(尤其是观赏性河道和湖泊类)的水质指标是可行的。     

水解酸化法预处理生物制药废水的试验研究

对生物制药废水水解酸化反应器采用接种污泥的方式进行启动,在不断增加进水污染负荷的条件下,40 d 内完成水解酸化反应器的启动。试验研究表明：当水解酸化反应器的水力停留时间为8h 时, COD 去除率可达到34．2％。而且,水中有机氮在水解酸化过程中转化为氨氮,为后续二级生物处理提供了高效去除氨氮的基础。     

晋牛矿1303综放面采空区注氮方案研究及数值模拟

为了合理设计采空区注氮防灭火方案,以晋牛煤矿1303综放工作面为研究对象,通过在采空区进、回风侧布置束管监测系统,连续测定采空区气体浓度变化,划分采空区自燃“三带”分布区域,并基于采空区自燃“三带”划分标准和数值模拟的方法,利用流体力学COMSOL计算软件,研究不同注氮量、注氮位置下采空区氧化自燃带的分布规律。研究结果表明:注氮量和注氮位置参数的变化,对氧化自燃带上界限的影响并不显著,而对氧化自燃带的下界限影响比较显著;最合适的注氮位置应该在距离切顶线30 m左右,运用Origin软件得出注氮量与氧化自燃带宽度呈指数关系,由拟合式计算出最优注氮量为386 m3/h,此时氧化自燃带的宽度为31.5 m。     

提高炼油废水处理场的氨氮去除率

对炼油废水处理场现有工艺进行流程优化,将MBR装置调整在接触氧化池之后运行.优化流程后氨氮平均去除率可从近于0提高至71.70％;COD平均去除率可从50.00％提高至72.00％.通过对工艺流程的对比,分析了现有工艺氨氮质量浓度难以降低的原因,指出废水中存在的某些污染物对硝化细菌起到抑制作用,减少了反应器中硝化细菌的...     

The GANE Roof Project: The impact of reduced N & S deposition and experimental warming in an acid grassland

A field-based system used to quantify the response of acid grassland to reduced atmospheric nitrogen and sulphur deposition, and to investigate the effects of elevated soil temperature on acid grassland development is described. The system is based on 12 retractable roofs, covering undisturbed experimental plots of acid grassland and three controls. Nine roofs are used to exclude natural precipitation and three roofs used to retain emitted IR radiation at night. An irrigation system has been developed to simulate natural precipitation, allowing for the application of specific treatment regimes of ambient, reduced nitrogen and reduced nitrogen/sulphur deposition beneath the nine rain exclusion plots. Plant, soil parameters, leachate chemistry and gaseous fluxes are being monitored and initial results on soil water chemistry are described. Warming appeared to enhance nitrate concentrations in soil water but this was not sustained beyond the first year of treatment. In contrast, the deposition reduction treatments decreased soil water nitrate concentrations within a few weeks of reducing deposition. This was not observed for other solutes such as sulphate or ammonium suggesting a more direct link between deposition of nitrate and leaching losses.     

Impact of Land Use on Soluble Organic Nitrogen in Soil

Although it has been hypothesized that soluble organic nitrogen (SON) plays a central role in regulating productivity in some terrestrial ecosystems, the factors controlling the size of the SON pool in soil remain poorly understood. Therefore our principal aim in this work was to assess the impact of seven different land use systems (rough and managed grassland, deciduous and coniferous woodland, heathland, wetland and tilled land) on the size of the SON and inorganic N (NO ₃ ^– , NH ₄ ⁺ ) pools in the surface soil layer (0–15 cm). After extraction with deionised water, we found that in most cases the size of the water extractable organic N (WEON) pool was similar in size to the inorganic N pool. In contrast, the KCl extractable organic N (KClEON) pool constituted the dominant form of soluble N in soils under all land uses, perhaps indicating that significant amounts were held on the soil exchange phase. In contrast to inorganic N, which varied significantly with land use, the size of the KClEON and WEON pool was similar for all land uses with the exception of KClEON in tilled land, where significantly lower amounts were observed. We conclude that SON constitutes an important soil N pool in a broad range of land uses, and that its role in microbial N assimilation, plant nutrition and ecosystem responses to atmospheric N deposition warrants further attention. SAFRD, University of Newcastle, Newcastle-upon-Tyne, NE1 7RU, U.K.