石灰石—石膏湿法脱硫和循环流化床干法脱硫技术应用比较

对目前火电厂所用的石灰石—石膏湿法和循环流化床干法脱硫技术的原理和工艺进行了简单介绍,对石灰石—石膏湿法和循环流化床干法2种脱硫技术从运行技术参数、投资运行费用、脱硫效率、各自优缺点等几个方面做了简单比较,并对循环流化床法在新疆的应用前景进行了分析。     

Canopy slope effect on the performance of the solar chimney power plant

Solar chimney power plants constitute an impressive construction by its size and its output seems low for its dimensions. Although many works have been carried out on the subject, there is still much scientific and technical improvement to be done. In the present work, we consider the modeling of turbulent flow under the effect of natural convection within a solar chimney power plant (SCPP) by performing numerical simulation using the Saturne Code coupled with Syrthes code. The objective of the study is the analysis of the collector cover slope influence on the performance of the SCPP in two cases. In the first case, the storage system considered is composed solely of the ground under the collector. For the second case, the storage system is made, in addition to the ground, of a 10 cm thick tub filled with water, covering the entire surface of the collector. The concept of minimizing the entropy production is also studied with the objective of optimizing the geometric configuration as well as the effect of the collector cover slope on the efficiency of SCPP. The boundary conditions are defined according to the meteorological data for a typical day available on the site of Adrar, Algeria. The results allow us to focus on the storage system influence on the SCPP performance and the duration of its operation after sunset. This leads to the improvement of the global efficiency of the SCPP. Results show the positive impact of the extra storage media use and the configuration which improves the velocity at the chimney entrance.     

Changing governance structures and the environment: economy–environment relations at the local and regional scales

Two substantive bodies of research have developed in recent years, both of which have a focus upon local and regional scales. First, there has been the development of work on changing forms of local and regional governance. This has drawn on a range of theoretical perspectives, including notions of institutional capacity, urban regime theory and neo-regulationalist accounts. Second, a body of research has developed into environmental policy and sustainable development, but this has largely been normative and undertheorized. While these two bodies of literature have developed separately, we believe there is merit in bringing the insights from each together. A focus on local environmental policy helps to broaden our understanding of local governance and problems of after-Fordist regulation. Such a project also helps to illuminate problems in implementing policy on the environment and sustainability. The examination of changing local and regional forms of governance allows us to identify new state spaces, which may provide opportunities for the strategic insertion of environmental objectives into economic development policies. This paper seeks to theorize such environment–economy relations and emerging multi-scalar forms of environmental governance, drawing upon case study research work in six UK local authority areas. Copyright © 2002 John Wiley & Sons, Ltd.     

Spatial and Temporal Variation of Water Temperature Regimes on the Snoqualmie River Network

Although mean temperatures change annually and are highly correlated with elevation, the entire thermal regime on the Snoqualmie River, Washington, USA does not simply shift with elevation or season. Particular facets of the thermal regime have unique spatial patterns on the river network and at particular times of the year. We used a spatially and temporally dense temperature dataset to generate 13 temperature metrics representing popular summary measures (e.g., minimum, mean, or maximum temperature) and wavelet variances over each of seven time windows. Spatial stream‐network models which account for within‐network dependence were fit using three commonly used predictors of riverine thermal regime (elevation, mean annual discharge, and percent commercial area) to each temperature metric in each time window. Predictors were strongly related (r² > 0.6) to common summaries of the thermal regime but were less effective at describing other facets of the thermal regime. Relationships shifted with season and across facets. Summer mean temperatures decreased strongly with increasing elevation but this relationship was weaker for winter mean temperatures and winter minimum temperatures; it was reversed for mean daily range and there was no relationship between elevation and wavelet variances. We provide examples of how enriched information about the spatial and temporal complexities of natural thermal regimes can improve management and monitoring of aquatic resources.     

Removing perfluorooctane sulfonate and perfluorooctanoic acid from solid matrices, paper, fabrics, and sand by mineral acid suppression and supercritical carbon dioxide extraction

The removal of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) from solid matrices has received considerable attention because of the environmental persistence, bioaccumulation, and potential toxicity of these compounds. This study presents a simple method using concentrated HNO₃ as a suppression agent, and methanol-modified supercritical carbon dioxide (Sc-CO₂) extraction for removing PFOS and PFOA from solid matrices. The optimal conditions were 16 M HNO₃ and 20% (v/v) methanol containing Sc-CO₂, under a pressure of 20.3 MPa and a temperature of 50 °C. Extraction time was set at 70 min (40 min for static and 30 min for dynamic extraction). PFOA and PFOS were identified and quantitated by liquid chromatography/mass spectrometry. The extraction efficiencies (with double extractions) were close to 100% for PFOA and 80% for PFOS for both paper and fabric matrices. The extraction efficiencies for sand were approximately 77% for PFOA and 59% for PFOS. The results show that this method is accurate, and effective, and that it provides a promising and convenient approach to remediate the environment of hazardous PFOA and PFOS contamination.     

含油污水处理用旋流气浮一体化设备的CFD数值模拟

借助商业计算流体动力学(CFD)软件Fluent,对国内自主研发的含油污水处理用BIPTCFU-1型旋流气浮一体化设备进行内部流场的数值模拟研究,讨论了射流器挡板和缓流板等主要结构参数对设备分离性能的影响,并对污水处理量和回流比等运行参数对设备除油率的影响进行了评估。为下一步通过CFD数值模拟手段进行优化设计,进而成功研发含油污水旋流气浮一体化处理设备奠定了较为坚实的基础。     

袋式除尘器内部流场的数值模拟

袋式除尘器内部气流分布不均会加剧滤袋磨损,降低除尘效率。采用计算流体动力学(CFD)数值模拟方法对除尘器内部流场进行研究,分析了气流的轨迹及其在各气室中的速度分布。发现原设计中气流分布不均匀的现象比较明显,提出了在进气通道内添加气流均布板的改进措施。结果表明:改进后,除尘器箱体内部气流分布较均匀,各滤袋气流分配系数的波动幅度减小,各气室综合流量不均幅值降低。研究结果为袋式除尘器的结构优化设计提供了理论依据。     

臭氧接触池与清水池合建的三维数值模拟

利用计算流体力学软件Fluent,结合标准κ-ε模型和组分输运模型,建立了臭氧接触池和清水池的三维紊流模型;通过计算流体的停留时间分布曲线(RTD),对臭氧接触池的水力效率进行了模拟研究。在此基础上,提出了在清水池前段第一廊道设置臭氧接触池的合建方案。结果表明:单一的臭氧接触池水力效率较低,T10/HRT值仅为0.42;而臭氧接触池与清水池经过合建后,T10/HRT值达到0.65,其臭氧消毒水力效率提高了55%。     

页岩气压裂返排液高效破胶剂的研究

针对页岩气开采过程中产生的非常规压裂返排液具有高粘度、高COD及高稳定性的特点,以Fe(NO3)3和Ca(Cl O)2为原料,采用化学湿法中的两步法合成了一种绿色氧化剂K2Fe O4,并对合成出的K2Fe O4进行了定量分析,得到合成的高铁酸钾产率为67.63%,纯度为93.41%。采用X衍射、红外光谱、扫描电镜及X衍射能谱,对合成的K2Fe O4进行了表征。将K2Fe O4作为某气田页岩气压裂返排液的高效破胶剂,并对影响破胶效果的因素进行了分析。确定了K2Fe O4的加量为3 000 mg/L,体系p H为11.0及反应时间为40 min的最优条件,在最优条件下,得到出水的粘度为1.4 m Pa·s,其COD、SS和色度的去除率分别为59.1%、93.3%和88.9%。通过红外光谱和扫描电镜进行了微观观察,对K2Fe O4氧化非常规压裂返排液中主要成分胍胶的过程进行了机理分析。研究还发现,K2Fe O4在还原分解后,具有比单一铁离子更强的混凝效果。因此,K2Fe O4的应用对页岩气压裂返排液的处理有深远的影响。     

废柴油再生工艺废弃物的固化实验

废弃油基钻井液中废柴油再生工艺产生的废渣废液具有高COD和高色度等特点,直接外排对环境危害严重。通过单因素实验和正交实验确定了该废弃物的最佳固化配方为:水泥∶粉煤灰为3∶2,水泥和粉煤灰加量30%,石膏加量1.5%,硫酸铝加量1.5%,石灰加量1%。在最佳固化配方下,废弃物浸出液的COD由10 062 mg/L降至62 mg/L,色度由500倍降至8倍,各主要污染指标都符合《污水综合排放标准》(GB 8978-1996)一级标准,固化成本约120元/m3。通过固化体的宏观照片和微观SEM照片对固化机理进行了分析,结果表明,废弃物被稳固地包裹在固化体之中。