增压风机并联运行中脱硫系统入口压力控制

分析了石灰石-石膏湿法脱硫系统(WFGD)中2台增压风机并联运行的入口压力控制问题,讨论并提出了一种基于前馈--反馈加偏置的脱硫系统入口压力自动控制方案,并以某600MW超临界机组双增压风机脱硫系统的入口压力控制为例加以分析说明.     

浓缩型入口下排气旋风分离器流场和性能的数值计算

运用CFD方法,对浓缩型入口下排气旋风分离器内的气固两相流动进行了研究。计算中气相采用RNGk-ε湍流模型,颗粒相采用拉格朗日坐标系下的离散相模型。重点计算了分离器流场、分离效率及其阻力特性,结果表明,采用浓缩入口后分离器内流场发生明显改变,分离器上部切向速度明显提高,有利于大颗粒的分离。同时通过对不同浓缩结构旋风分离器的分离效率和阻力特性进行分析比较,为工程设计提供了依据。     

江苏王港地区现代潮滩地貌发育特征

淤泥质潮滩是人类活动的强烈地带，江苏王港地区淤泥质潮滩宽广，由于人工引种大米草，滩涂围垦，大丰港的修筑，影响了王港地区原有潮滩发育的动力机制。王港地区生物分布和地貌特征具有明显的分带性。由于植被的促淤作用，王港地区潮滩南部垂向淤积速率较北部大；研究区内潮水沟的发育有两种类型。即泥滩带上的块体崩塌溯源侵蚀和零星分布的米草滩上的洞穴塌陷溯源侵蚀形成潮水沟；潮间带下部实测平均涨潮流流速小于平均落潮流流速，而涨潮平均含沙量大于落潮平均含沙量，潮间带下部潮水往复流及旋转流的作用在滩面上形成了双向波痕，陆地向海推进速度随着泥沙供给的减少以及滩面高程的降低而减慢。     

上海南汇潮滩表层中多环芳烃分布特征及环境意义

利用ＧＣ／ＭＳ分析了上海南汇淤泥质潮滩６，８两月表层沉积物中有机污染物多环芳烃，结果表明，该区在６月和８月８潮滩中ＰＡＨ组化芘，苯并芘及黄蒽具有较高的含量，并且在ＰＡＨ总量中所占比重也产大，在潮滩沉积物中已呈明显富集的趋势。     

崇明东滩沉积物再悬浮对沉积物-水界面氮、磷交换行为的影响

2002年7月采集崇明东滩低潮滩沉积物样和水样,运用模拟实验研究沉积物再悬浮作用对沉积物-水界面三态氮和可溶磷交换行为的影响实验发现,在沉积物不断发生再悬浮的过程中,水体中三态氮的含量明显增加,其中NO₃^--N变化最为显著,升高浓度值达11.869μmol·L^-1,NH₄⁺-N增长2.1713μmol·L^-1,NO₂^--N的释放约为0.2μmol·L^-1,可溶磷的含量也有少量的增加.同时,再悬浮作用对沉积物-水界面三态氮和可溶磷的环境地球化学行为也有一定的影响,与静置状态相比,NH₄⁺-N和NO₃^--N表现出与静置状态截然相反的变化规律,NO₂^--N受多种因素的影响,变化比较复杂,初期与静置状态相反而后表现一致.再悬浮颗粒物浓度也是制约沉积物-水界面三态氮和可溶磷变化的主要因子之一.实验结果显示,NH₄⁺-N在前7h以内的变化和悬浮颗粒物浓度表现出较好的相关关系,后5h呈负相关关系;NO₂^--N和可溶磷在整个过程中与悬浮颗粒物浓度的变化都有着很好的相关性,只有NO₃^--N的变化与其关系比较薄弱.     

海南小海潟湖环境的破坏与治理

从口门稳定性的角度,分析了三大人为工程(太阳河改道、在通道口修筑北堤和封堵南汊道及约5 km2的潮滩被围垦)所起的作用以及波浪动力对小海口门演变的影响,认为小海潟湖潮汐通道在其演变进程中,由于潮汐弱而波能相对较强,目前仍属波浪作用为主型,依据自己多年的研究工作,首次提出以口门复式断面和通道分汊的方法对小海及该类型潟湖进行治理.     

水力空化的最佳条件研究

采用了不同几何尺寸的孔板作为水力空化发生器,研究了流量、进口压力、孔内流速、孔板的孔径与厚度之比及孔板过流总面积与管道横截面积的比值对空化数的影响,得出进口压力控制在20mH2O,孔内流速控制在14.5m/s,δ/d为1.8s,为0.06,空化效果较好.     

闸控感潮河网水环境容量计算研究

受潮汐影响的闸控河网的水环境容量计算是水环境控制的重要内容。针对闸控感潮河网的水流特点,介绍了基于动态水质模型的水环境容量的数值计算方法。其方法综合考虑了感潮河网地区水流运动复杂、易受水利工程设施运行影响的特点,并成功地应用到动态水环境容量计算。     

Just Add Water and the Colorado River Still Reaches the Sea

A recent article in Environmental Management by All argued that flood flows in North America’s Colorado River do not reach the Gulf of California because they are captured and evaporated in Laguna Salada, a below sea-level lakebed near the mouth of the river. We refute this hypothesis by showing that (1) due to its limited area, the Laguna Salada could have evaporated less than 10% of the flood flows that have occurred since 1989; (2) low flow volumes preferentially flow to the Gulf rather than Laguna Salada; (3) All’s method for detecting water surface area in the Laguna Salada appears to be flawed because Landsat Thematic Mapper images of the lakebed show it to be dry when All’s analyses said it was flooded; (4) direct measurements of salinity at the mouth of the river and in the Upper Gulf of California during flood flows in 1993 and 1998 confirm that flood waters reach the sea; and (5) stable oxygen isotope signatures in clam shells and fish otoliths recorded the dilution of seawater with fresh water during the 1993 and 1998 flows. Furthermore, All’s conclusion that freshwater flows do not benefit the ecology of the marine zone is incorrect because the peer-reviewed literature shows that postlarval larval shrimp populations increase during floods, and the subsequent year’s shrimp harvest increases. Furthermore, freshwater flows increase the nursery area for Gulf corvina (Cynoscion othonopterus), an important commercial fish that requires estuarine habitats with salinities in the range of 26–38‰ during its natal stages. Although flood flows are now much diminished compared to the pre-dam era, they are still important to the remnant wetland and riparian habitats of the Colorado River delta and to organisms in the intertidal and marine zone. Only a small fraction of the flood flows are evaporated in Laguna Salada.     

Ecological Feasibility Studies in Restoration Decision Making

The restoration of degraded systems is essential for maintaining the provision of valuable ecosystem services, including the maintenance of aesthetic values. However, restoration projects often fail to reach desired goals for a variety of ecologic, financial, and social reasons. Feasibility studies that evaluate whether a restoration effort should even be attempted can enhance restoration success by highlighting potential pitfalls and gaps in knowledge before the design phase of a restoration. Feasibility studies also can bring stakeholders together before a restoration project is designed to discuss potential disagreements. For these reasons, a feasibility study was conducted to evaluate the efficacy of restoring a tidal freshwater marsh in the Potomac River near Alexandria, Virginia. The study focused on science rather than engineering questions, and thus differed in approach from other feasibility studies that are mostly engineering driven. The authors report the framework they used to conduct a feasibility study to inform other potential restoration projects with similar goals. The seven steps of the framework encompass (1) initiation of a feasibility study, (2) compilation of existing data, (3) collection of current site information, (4) examination of case studies, (5) synthesis of information in a handbook, (6) meeting with selected stakeholders, and (7) evaluation of meeting outcomes. By conducting a feasibility study using the seven-step framework, the authors set the stage for conducting future compliance studies and enhancing the chance of a successful restoration.