复合介质人工浮岛对含铜废水净化效果试验研究

铜污染废水具有危害范围广、作用强等特点,随着我国工业化程度的提高,水体的铜污染有进一步扩大的趋势,因此研究铜污染水体的修复方法对于治理含铜废水具有重要意义.针对这一问题,提出了采用复合介质人工浮岛技术对铜污染水体的处理效果进行研究.试验采用沸石和火山灰两组复合介质人工浮岛,浮岛植物均为菖蒲.试验研究了4个控制参数,即不...     

一起特大冒顶事故被困人员成功抢救经验探析

本文详细介绍了四老沟矿14-3号层303盘区2309巷道冒顶事故抢救所采取的措施,并对冒顶原因进行了分析。事故发生后,采用生命探测仪探测到了被困区域还有生命迹象,对抢救工作提出了更好要求;合理调整了通风系统,避免了被困人员窒息或中毒死亡;向被困区域打钻孔,给被困人员送进了牛奶等食物,避免了被困人因饥渴而死亡;快速掘进救人通道,救出被困人员。由于决策科学、果断,措施得力,才使得8名被困人员全部脱险。详细分析了事故的原因,一是采用锚杆、无腿工字钢梁联合支护设计不合理;二是施工中存在锚杆预紧力低、托钩外露长度超长、工字钢棚数量不足等问题;三是上覆14-2号煤层采空区岩层活动及8309回采面开采动压对巷道造成了很大的影响。最后,对预防类似事故发生所采取的措施和建议做出了结论。     

绿色、蓝色和蓝-绿屋顶径流水质特征

屋顶占据大量城市不透水面,实施生态屋顶建设,有利于缓解城市化造成的生态和环境问题.在北京市区搭建不同类型生态屋顶(绿色屋顶、蓝色屋顶和蓝-绿屋顶),基于对2019年雨季降雨特征、各类生态屋顶径流量以及径流中营养盐和重金属浓度的监测,计算不同生态屋顶径流污染负荷和径流水质指数(RQI),定量对比分析不同类型生态屋顶径流的综合水质差异.结果表明,在2019年雨季,各生态屋顶均表现出良好的雨水滞留能力,平均径流削减率在75.7%～78.9%之间,且不同生态屋顶的径流削减率无显著差异(P>0.05);相较雨水,各生态屋顶均为NH⁺₄-N、 DZn和DCd的汇,累积负荷削减率分别在63.8%～96.4%、68.6%～90.7%和39.8%～54.5%之间,但均为NO^-₃-N、 DCr、 DFe和DNi的释放源;蓝色屋顶是DCu的汇(累积负荷削减率为21.9%),但对雨水径流中PO^3-₄-P的累积负荷无明显影响,而绿色和蓝-绿屋顶均为PO^3-     

Performance analysis of on-farm irrigation tanks on agricultural drainage water reuse and treatment

Water reuse and pollutant removal efficiency analysis of the on-farm irrigation tanks (OFTs) was carried out in rice paddy field region of Zhanghe Irrigation District, Southern China through field experiments during the rice growing season of 2009–2011. Water flow measurements indicate that 20.6–68.9% of drainage water captured by OFTs was reused for supplemental irrigation. Rainfall was the most important factor that determines the water reuse efficiency (WRR) of OFTs, since higher rainfall resulted in higher surplus irrigation water draining out of OFTs without reuse, and thus decreased WRR. Fully using the storage capacity for storing return flow, and releasing totally for supplemental irrigation also enhanced WRR of OFTs. Water quality analysis shows that OFTs removed 47.2% of total phosphorous (TP) and 60.8% of total nitrogen (TN) of inflow and have a great effect on increasing sedimentation for return flow as the mean of removal efficiency of pollutant load (REL) for suspended solids (SS) amounted to 68.4%. For water treatment effectiveness of OFTs, high hydraulic retention time (HRT) is most beneficial to increase REL of TN whereas REL of TP is not sensitive to HRT. These results confirm that OFTs can effectively increase agricultural return flow reuse and remove pollutants. As the cascade OFTs irrigation system recycle return flow for several times, the irrigation water demand from outside of region was reduced significantly for rice production. Coupling with the effect of cyclic irrigation on the nutrients recycling by paddy fields, OFTs irrigation system also considerably mitigate the N and P off-site emission. Therefore, it is advisable to integrate the role of OFTs on water reuse and treatment for water saving irrigation and ecological management of paddy fields landscape.     

GC／MS外标法测定水中22种挥发性有机物的探究

以外标法定量,通过吹扫捕集-气相色谱质谱对22种挥发性有机物进行检测,建立了相应的分析方法。方法将单次分析时间控制样品在50min,连续进样分析时间在38min。并对样品的检测数据进行分析,样品回收率在84．9％～124．9％之间,相对标准偏差均小于10％,且加标回收率在半年内能稳定在81．5％～129．7％之间。结果表明,在采用自动进样器进样条件下,外标法在精准度上满足实验需求,且分析时间较短,节省了加入内标物所带来的成本负担。     

A CFD based explosion risk analysis methodology using time varying release rates in dispersion simulations

A full probabilistic Explosion Risk Analysis (ERA) is commonly used to establish overpressure exceedance curves for offshore facilities. This involves modelling a large number of gas dispersion and explosion scenarios. Capturing the time dependant build up and decay of a flammable gas cloud size along with its shape and location are important parameters that can govern the results of an ERA. Dispersion simulations using Computational Fluid Dynamics (CFD) are generally carried out in detailed ERA studies to obtain these pieces of information. However, these dispersion simulations are typically modelled with constant release rates leading to steady state results. The basic assumption used here is that the flammable gas cloud build up rate from these constant release rate dispersion simulations would mimic the actual transient cloud build up rate from a time varying release rate. This assumption does not correctly capture the physical phenomena of transient gas releases and their subsequent dispersion and may lead to very conservative results. This in turn results in potential over design of facilities with implications on time, materials and cost of a project.In the current work, an ERA methodology is proposed that uses time varying release rates as an input in the CFD dispersion simulations to obtain the fully transient flammable gas cloud build-up and decay, while ensuring the total time required to perform the ERA study is also reduced. It was found that the proposed ERA methodology leads to improved accuracy in dispersion results, steeper overpressure exceedance curves and a significant reduction in the Design Accidental Load (DAL) values whilst still maintaining some conservatism and also reducing the total time required to perform an ERA study.     

基于氢气充放试验及数值模拟的储氢气瓶安全评价

储氢气瓶是新能源汽车的重要储能设备,其可靠性直接关系到汽车的安全性。研究了不同环境温度下,35 MPa铝合金内胆车用储氢III型气瓶在充放气时的最终温度和应力分布情况,并对其安全性进行了评价。借助试验测试平台,在不同温度下进行了实际充放试验。试验过程中无漏气现象,且最终温度符合要求,表明储氢气瓶在试验条件下是安全的。由此,在获得了储氢气瓶充放时热响应规律的基础上,对不同温度下的氢气充放过程进行了数值模拟,得到其应力分布情况。结果表明,储氢气瓶复合层的应力远小于其材料抗拉强度,即内胆和复合层的强度均可视为满足要求。研究结果可为储氢气瓶的试验开展、安全评价、寿命预测提供依据。     

Dynamic probability assessment of urban natural gas pipeline accidents considering integrated external activities

Urban gas pipelines usually have high structural vulnerability due to long service time. The locations across urban areas with high population density make the gas pipelines easily exposed to external activities. Recently, urban pipelines may also have been the target of terrorist attacks. Nevertheless, the intentional damage, i.e. terrorist attack, was seldom considered in previous risk analysis of urban gas pipelines. This work presents a dynamic risk analysis of external activities to urban gas pipelines, which integrates unintentional and intentional damage to pipelines in a unified framework. A Bayesian network mapping from the Bow-tie model is used to represent the evolution process of pipeline accidents initiating from intentional and unintentional hazards. The probabilities of basic events and safety barriers are estimated by adopting the Fuzzy set theory and hierarchical Bayesian analysis (HBA). The developed model enables assessment of the dynamic probabilities of consequences and identifies the most credible contributing factors to the risk, given observed evidence. It also captures both data and model uncertainties. Eventually, an industrial case is presented to illustrate the applicability and effectiveness of the developed methodology. It is observed that the proposed methodology helps to more accurately conduct risk assessment and management of urban natural gas pipelines.     

河口区养殖塘水-气界面N2O扩散通量比较

以闽江河口区水产养虾塘为研究对象,于2017年6~11月,采用漂浮箱法和扩散模型法同步原位观测了养殖塘N₂O排放通量.结果表明,研究期间悬浮箱法和扩散模型法获得的养殖塘水－气界面N₂O通量变化范围分别为（0.38±0.05）~（20.63±5.63）μg/（m²·h）和（2.77±0.52）~（17.23±2.27）μg/（m²·h）,随时间推移均呈现“增加-降低-增加-降低”的双峰变化特征.两种方法观测的N₂O通量均与水温、水体硝酸盐氮（NO₃^--N）和氨氮（NH₄⁺-N）浓度呈现显著正相关关系（P<0.05）,与水体溶解氧（DO）呈现出显著负相关关系（P<0.05）.悬浮箱法与不同扩散模型法测定的N₂O排放通量大小排序表现为：模型DM_RC01>悬浮箱法>模型DM_CL98>模型DM_W92a>模型DM_MY95>模型DM_CW03>模型DM_LM86.相比其他几种模型方法,模型RC01与悬浮箱法测得的养殖塘水－气界面N₂O通量相关性系数最高.本研究结果初步表明,今后进行东南沿海河口区养殖塘N₂O通量的大尺度观测研究时,可考虑选择RC01模型法来代替悬浮箱法进行测定,进而减小人力及物力的投入.     

低温下表面流人工湿地中氨氮型富营养化水体净化研究

以氨氮为主要氮组分的富营养化水体为研究对象,采用批量培养方式对比研究了6.8～7.2℃水温下浮水植物系统(2种水葫芦Eichhornia crassipes、浮萍Lemna minor)、泡沫板系统(无生命覆盖物系统)及空白系统(无覆盖物系统)的脱氮效果,并探讨了6.4～11.2℃水温下不同起始COD浓度(27～105 mg/L)对各污染物去除的影响.结果表明,溶解氧(DO)是影响NH₄⁺-N去除的关键因子之一,好氧时期各系统NH₄⁺-N去除率占整个时期NH₄⁺-N去除率的61%～88%.3种植物系统中NH₄⁺-N的去除率(45%～56%)普遍高于泡沫板系统(38%)与空白系统(38%),而TN和COD去除效果差异则与植物类型有关;随着水体中起始COD浓度的升高,系统中DO逐渐由好氧状态降至0,该结果对NO₃^--N去除率影响最大(去除率由67%上升至95%),而对其它水质指标(COD,TN,NH₄⁺-N)的影响相对较小.