烟气扩散的CFD数值模拟

运用商业CFD软件Fluent模拟计算小尺寸下的简单烟气扩散规律.将结果用正态分布假设下的高斯烟羽模型验证.证明该软件模拟烟气扩散问题的可行性.     

城市污水厂污泥浓缩新技术的应用

分析了新型污泥浓缩设备的技术经济优点,现行污泥浓缩池的缺点、城市污水处理新工艺对浓缩的要求,介绍了2类污泥浓缩机在城市污水厂的选用和运行实例.     

Influence of organic loading on an anaerobic sequencing biofilm batch reactor (ASBBR) as a function of cycle period and wastewater concentration

The effect of organic loading on the performance of a mechanically stirred anaerobic sequencing biofilm batch reactor (ASBBR) has been investigated, by varying influent concentration and cycle period. For microbial immobilization 1-cm polyurethane foam cubes were used. An agitation rate of 500 rpm and temperature of 30+/-2 degrees C were employed. Organic loading rates (OLR) of 1.5-6.0gCODl(-1)d(-1) were applied to the 6.3-l reactor treating 2.0 l synthetic wastewater in 8 and 12-h batches and at concentrations of 500-2000mgCODl(-1), making it possible to analyze the effect of these two operation variables for the same organic loading range. Microbial immobilization on inert support maintained approximately 60 gTVS in the reactor. Filtered sample organic COD removal efficiencies ranged from 73 to 88% for organic loading up to 5.4gCODl(-1)d(-1). For higher organic loading (influent concentration of 2000mgCODl(-1) and 8-h cycle) the system presented total volatile acids accumulation, which reduced organics removal efficiency down to 55%. In this way, ASBBR with immobilized biomass was shown to be efficient for organic removal at organic loading rates of up to 5.4gCODl(-1)d(-1) and to be more stable to organic loading variations for 12-h cycles. This reactor might be an alternative to intermittent systems as it possesses greater operational flexibility. It might also be an alternative to batch systems suspended with microorganisms since it eliminates both the uncertainties regarding granulation and the time necessary for biomass sedimentation, hence reducing the total cycle period.     

用烧结法从沸腾炉渣中提取铝和铁的研究

把沸腾炉渣和石灰及精煤混合制成小球,然后在大约1 000 ℃下烧结.取不同烧结时间的样品用硫酸浸取,得到含有铝离子和铁离子的溶液.试验表明,采用浓度为4 mol/l的硫酸,在80 ℃下浸取烧结球样品(50%沸腾炉渣∶40%精煤∶10%石灰)24 h,可以得到铝和铁的最大提取率,分别为86.50%和94.60%.滤渣可以作为固化材料用于高速公路的路基建设或水泥生产中的添加剂.     

化学事故救援方舱舱室环境安全性模拟研究

运用计算流体动力学(CFD)方法,对具有超压防护功能的某化学事故应急救援手术方舱室内气体污染物运动扩散的规律以及对人员安全的影响进行了数值模拟,其研究结果表明:当大气环境中氢氰酸(HCN)浓度为5mg/L时,前10s从常规进风口进入舱室的HCN在滤毒通风装置开启后,随气流运动逐渐向整个舱室扩散,经净化空气的混合稀释作用,绝大部分通过舱体缝隙排出舱室,30min内舱室HCN浓度的总量下降了95.1%,说明超压防护很好地保证了舱室环境的安全性。     

ESTIMATING THE SUSPENDED SEDIMENT LOAD IN RESERVOIRS1

ABSTRACT: The total suspended sediment loads of four north Mississippi reservoirs were determined from measurements of concentrations of suspended sediment in a vertical profile at several locations on each reservoir made during the year. These data were combined with the stage-height and known stage-volume relationships for each reservoir in a numerical integration to determine the total suspended sediment in the water body. Total suspended sediments were estimated using the product of the suspended sediment concentration in the surface water by the appropriate reservoir volume. The averaged ratios of the estimated to measured suspended sediment loads for each reservoir exceeded 0.90. Since the concentration of suspended sediments in surface waters of north Mississippi reservoirs has been shown as highly correlated with spectral reflectance, estimating the total suspended sediment of these reservoirs using remotely sensed spectral reflectance data is possible.     

The Role of Prices in Conserving Critical Natural Capital

Abstract: Until recent decades, economic decision makers have largely ignored the nonmarket benefits provided by nature, resulting in unprecedented threats to ecological life‐support functions. The economic challenge today is to decide how much ecosystem structure can be converted to economic production and how much must be conserved to provide essential ecosystem services. Many economists and a growing number of life scientists hope to address this challenge by estimating the marginal value of environmental benefits and then using this information to make economic decisions. I assessed this approach first by examining the role and effectiveness of the price mechanism in a well‐functioning market economy, second by identifying the issues that prevent markets from pricing many ecological benefits, and third by focusing on problems inherent to valuing services generated by complex and poorly understood ecosystems subject to irreversible change. I then focus on critical natural capital (CNC), which generates benefits that are essential to human welfare and have few if any substitutes. When imminent ecological thresholds threaten CNC, conservation is essential and marginal valuation becomes inappropriate. Once conservation needs have been met, remaining ecosystem structure is potentially available for economic production. Demand for this available supply will determine prices. In other words, conservation needs should be price determining, not price determined. Conservation science must help identify CNC and the quantity and quality of ecosystem structure required to ensure its sustained provision.     

有效磷含量对硝酸铵溶液热安全性的影响

为了了解硝酸磷肥生产过程中,硝酸铵溶液中加入磷酸一铵的安全性,通过自制实验装置,研究了有效磷含量对质量分数为85%的硝酸铵溶液热分解的影响。结果表明,质量分数为85%的硝酸铵和磷酸一铵混合溶液的临界爆炸温度高于纯质量分数为85%的硝酸铵溶液,稳定性更好;磷酸一铵抑制硝酸铵的热分解,随着有效磷含量的增加,硝酸铵混合溶液临界爆炸温度升高;升温速率对硝酸铵混合溶液的临界爆炸温度影响很大,随着升温速率由2℃/min升高到3℃/min,质量分数为85%的硝酸铵混合溶液的临界爆炸温度升高,不易发生爆炸,安全性更好。研究结果对硝酸磷肥的生产安全有一定的指导意义。     

环境烟草烟气粒径分布及其对光散射的影响

为了测量典型办公室内环境中环境烟草烟气悬浮颗粒物的数浓度和粒径分布变化,以及其对颗粒光散射的影响,在6.8 m×3.2mx2.8 m的试验间进行试验,采用测量范围为5～1 000 nm的DMS500扫描电迁移率粒径谱仪进行粒径测量.结果表明,不同卷烟样品的烟气粒径分布曲线近似,都可以用对数正态分布函数来描述.4种卷烟样品粒径分布及参数变化速率相似,在4 800 s内数中值粒径CMD平均值从105 nm增大至155 nm,几何标准差GSD平均值从1,58减小至1.45,CMD和GSD的变化趋势近似符合指数函数.利用基于Mueller光散射理论的程序计算烟颗粒对散射光的影响.粒径分布的变化显著改变了颗粒散射光强度,CMD最大使散射光强度增大7倍,GSD引起的强度变化较小.综合考虑烟气颗粒数浓度降低和粒径分布的变化,散射光强度最大增大3倍.     

采空区瓦斯涌出源位置对瓦斯分布影响的数值模拟

根据多孔介质渗流理论,利用Fluent软件,分别对采空区瓦斯在整个采空区均匀涌出、上邻近层及底板遗煤涌出2种情况下采空区瓦斯分布规律进行了数值模拟.结果表明:采空区瓦斯为上邻近层及底板遗煤处涌出时,沿走向方向,靠近上邻近层及底板处高体积分数瓦斯距离工作面较近;沿竖直方向,瓦斯体积分数分布呈钩状,靠近瓦斯涌出源处瓦斯体积分数最高;整个采空区均匀涌出时采空区瓦斯体积分数分布与上邻近层及底板遗煤涌出时有很大差别.因此,为了得到更符合实际情况的瓦斯分布规律,数值模拟时应按照现场实际的瓦斯涌出源位置建立模型.