System for the pulsed pneumatic transport of ash from ash-collector bins

Results of investigations of the dependence of the percentage of voids on the shear force of a layer of ash, on the basis of which the design principle of the subassembly for the feed of ash to a transport pipeline is developed, are examined for optimization of ash flows in a pulsed regime. The schematic of a system of pulsed pneumatic transport of ash from the bins of ash collectors, and results of measurements during experimental operation of the system, as well as relationships for the calculation of its dynamic parameters are presented. Conclusions concerning the high reliability of the removal and pneumatic transport of ash over a distance of more than 80 m with minimal air consumption are drawn on the basis of results of the experimental operation. __________ Translated from élektricheskie Stantsii, No. 6, June 2007, pp. 17–20.     

Automated System for Controlling the Operation of the Shaking Elements of Electrodes in Combination with Dry Removal of Ash from Electric Filter Hopper

An automated system for controlling the operation of shaking elements of electrodes (aeroridges) is suggested, which cleans the electrodes of the electric filter synchronously with the system of pneumatic removal of ash. Relationships for calculating the design parameters of the system depending on the modes of pneumatic transportation and dependences of the parameters of the fluidized layer of the removed ash on the structural variants of aeroridges are presented.     

气力输灰及粉煤灰综合利用方案探讨

研究了国内外电厂干式除灰技术和粉煤灰综合利用的现状,结合华电能源牡丹江第二发电厂的实际,对#7炉电除尘器气力输灰方案进行了探讨,对粉煤灰综合利用及经济效益进行了分析,指出了气力输灰系统应注意的一些问题。     

EDTA-粉煤灰/H2O2体系处理模拟制革废水的试验研究

通过实验以及动力学分析表明用配体的引入对体系进行改进,提高了基于粉煤灰的多相类Fenton体系对模拟制革废水的去除效果,同时得到EDTA-粉煤灰/H2O2体系降解模拟制革废水的最佳反应条件:在室温下,反应pH值为10,初始COD值为110.8 mg/L,过氧化氢浓度为200.4 mg/L,EDTA的浓度为250 mmol/L,粉煤灰投加量为10 g/L的情况下,COD和色度的去除率都在95%以上,粉煤灰在多次使用后,COD去除率均达到97%以上。     

基于稳定输送流场的正压浓相气力输灰系统研究及应用

分析了大型火电机组气力输灰系统高能耗、输灰管道磨损严重的原因,根据气一固两相流的流动特性与其稳定输送流场的关系,设计了新型多泵制正压浓相型气力输灰系统。对该系统在600MW机组上进行了试验研究,试验结果表明,该系统可节能降耗并减少管道的磨损。     

锅炉气力输灰系统堵管原因及预防措施

以周口隆达发电公司浓相气力输灰系统为例，针对出现输灰系统的耗气量降低的问题提出了气力输灰系统的改进和优化方法，分析了在运行过程中发生堵管的原因并提出预防措施及处理方法；     

Removal of organic sediments from reservoirs and lakes and their processing

The experimental-industrial cleaning of Latvian lakes and the removal of sapropel at its in situ moisture content by a suction-tube dredge with a chambered pneumatic pump made by the Italian firm Pneuma, and also a new procedure for production of commercial sapropel are described.     

A simple low-cost approach for transport parameter determination in mountain rivers

A simplified low-cost approach to experimentally determine transport parameters in mountain rivers is described, with an emphasis on the longitudinal dispersion coefficient (D_L). The approach is based on a slug injection of table salt (NaCl) as a tracer and specific conductance readings at different locations downstream of the injection spot. Observed specific conductance readings are fit using the advection-dispersion equation with OTIS-P, yielding estimates of cross-sectional area and longitudinal dispersion coefficient for various stream reaches. Estimates of the D_L are used to assess the accuracy of several empirical equations reported in the literature. This allowed the determination of complementary transport parameters related to transient storage zones. The empirical equations yielded rather high D_L values, with some reaching up an order of magnitude higher to those obtained from tracer additions and OTIS-P. Overall, the proposed approach seems reliable and pertinent for river reaches of ca. 150 m in length.     

Separators for removal of solid particles from the hot intermediate superheating steam ducts of high-power generator units

The operation of three types of separators for the removal from the hot intermediate superheater steam duct of slag particles which reach the medium pressure part of the turbine from the steam generator. Results on the industrial operation of one of these systems are examined. Possible modifications of the separators are formulated.     

炉渣粉煤灰回填地基的强夯设计参数研究

针对人工回填料——高炉渣粉煤灰,研究其各主要施工参数对强夯效果的影响,为强夯施工参数设计提供了更加科学的参考标准,实现方案的合理性和成本的经济性。以高炉渣粉煤灰回填地基为研究对象,对强夯法加固地基的设计参数进行了数值模拟。依托包头钢铁集团新体系高炉矿渣地基处理项目,在FLAC~(3D)软件的基础上,选定夯击能、夯击次数,夯锤直径、夯点间距作为强夯施工研究参数,通过控制单一变量对不同施工参数下的强夯法加固地基的位移和应力变化进行探究。分析得出了夯击参数对强夯加固的影响规律,并对加固效果进行了详细的评价。结果表明:选取的夯击能越大,夯锤中心的土体产生的竖向位移越大;随着夯击次数的增加,土体的影响深度逐渐增大,当超过最佳夯击次数后,就显得毫无意义;夯锤直径越大,作用面积越大,土体变形范围越大。因此,合理的选取强夯间距可以增强地基的整体强夯效果。     

Removal of target odorous molecules on to activated carbon cloths.

Activated carbon materials are adsorbents whose physico-chemical properties are interesting for the treatment of odorous compounds like hydrogen sulfide. Indeed, their structural parameters (pore structure) and surface chemistry (presence of heteroatoms such as oxygen, hydrogen, nitrogen, sulfur, phosphorus) play an important role in H2S removal. The cloth texture of these adsorbents (activated carbon cloths) is particularly adapted for dealing with high flows, often found in the treatment of odor emissions. Thus, this paper first presents the influence of these parameters through adsorption isothermal curves performed on several materials. Secondly, tests in a dynamic system are described. They highlight the low critical thickness of the fabric compared to granular activated carbon.     

低热水泥胶凝体系水化热计算研究

为了评价几种传统水化热计算方法对低热水泥的适用性,进而提出低热水泥胶凝体系水化热的计算公式,采用直接法测定了不同掺量粉煤灰、矿渣条件下的低热水泥胶凝体系7 d水化热,对比应用矿物成分法、折算公式法、数值拟合法算得相应结果,调整各模型参数并对其计算精度进行评价分析。研究结果表明:矿物成分法仅能计算特征龄期下水泥水化热,算得结果与试验数值差距较大;折算公式法用于计算单一掺合料下胶凝材料7 d水化热时所得结果准确度较高;数值拟合法适用于单掺、复掺不同掺量矿物掺合料的低热水泥胶凝体系,该体系下粉煤灰、矿渣的最终水化热分别为126.6 J/g和172.4 J/g。研究成果可为大体积混凝土的绝热温升计算提供基础数据参考。     

Formation of mineral deposits in hydraulic ash removal systems

Selection of design schemes for the water supply (straight through, or circulating) of hydraulic ash-removal (HAR) systems for thermal electric power plants (TPP) is examined as a function of the character of mineralization of the water in a specific system. Causes are outlined for the formation of mineral deposits on equipment of the HAR system, which transports ash slurries of different types of solid fuels. The cause of the high rate of seasonal growth formation in the circulating HAR systems of TPP burning fuel with highly alkaline ash slurries is established experimentally in an example of a shale electric power plant. Measures are developed for rapid slow-down of the rate of growth formation in these systems. Measures are proposed for prevention of growth formation for other types of ash slurries. __________ Translated from élektricheskie Stantsii, No. 5, pp. 41–47, May, 2006.     

Study of rotating biological contactor performance in wastewater treatment using multi-culture biofilm model.

The rotating biological contactor (RBC) process offers the specific advantages of a biofilm system in treatment of wastewater for removal of soluble organic substances and stabilisation of nitrogen compounds. Being a unique adaptation of the moving-medium biofilm system, it facilitates easy and effective oxygen transfer. However, process optimisation and adaptability under different conditions remain challenging tasks for the efficient use of this technology. Although modelling helps to study system performance under various external conditions, satisfactory mathematical representation is lacking due to the dynamic nature of the RBC system. In this work, it has been attempted to frame a mathematical model for a three-stage RBC process in simple and realistic ways. The model is based on the well-known principles of one-dimensional mass transfer and transport of substances. The biochemical conversion process is adopted from the Activated Sludge Model No. 3 which represents a mixed-culture biomass environment. Owing to the dynamic nature of oxygen transfer, which is the typical limiting substrate in municipal wastewaters, the boundary layer is assumed to be completely mixed and concentrations averaged over the entire volume. A part of the boundary layer is assumed to be exposed to air and the rest submerged in bulk liquid at all times. The model results are compared with laboratory-scale experimental data available at 25 'C. Sensitivity analysis is performed with the model to study the significance of variation of different system parameters or the surrounding environment. In essence, the model helps to explore the flexibilities within a RBC system and optimise the process design accordingly.     

Sedimentology of New Fluvial Deposits on the Elwha River,Washington, USA,Formed During Large‐Scale Dam Removal

Removal of two dams 32 m and 64 m high on the Elwha River, Washington, USA, provided the first opportunity to examine river response to a dam removal and controlled sediment influx on such a large scale. Although many recent river‐restoration efforts have included dam removal, large dam removals have been rare enough that their physical and ecological effects remain poorly understood. New sedimentary deposits that formed during this multi‐stage dam removal result from a unique, artificially created imbalance between fluvial sediment supply and transport capacity. River flows during dam removal were essentially natural and included no large floods in the first two years, while draining of the two reservoirs greatly increased the sediment supply available for fluvial transport. The resulting sedimentary deposits exhibited substantial spatial heterogeneity in thickness, stratal‐formation patterns, grain size and organic content. Initial mud deposition in the first year of dam removal filled pore spaces in the pre‐dam‐removal cobble bed, potentially causing ecological disturbance but not aggrading the bed substantially at first. During the second winter of dam removal, thicker and in some cases coarser deposits replaced the early mud deposits. By 18 months into dam removal, channel‐margin and floodplain deposits were commonly >0.5 m thick and, contrary to pre‐dam‐removal predictions that silt and clay would bypass the river system, included average mud content around 20%. Large wood and lenses of smaller organic particles were common in the new deposits, presumably contributing additional carbon and nutrients to the ecosystem downstream of the dam sites. Understanding initial sedimentary response to the Elwha River dam removals will inform subsequent analyses of longer‐term sedimentary, geomorphic and ecosystem changes in this fluvial and coastal system, and will provide important lessons for other river‐restoration efforts where large dam removal is planned or proposed. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.     

Depth distribution and mobility of a harpacticoid copepod within the bed sediment of an alpine brook

The harpacticoid copepod Limnocamptus echinatus (Mrazek) shows a very distinct large-scale vertical distribution within the bed sediments of Oberer Seebach, a second-order gravel stream. The population peak appears in a sediment layer between 15 and 35 cm over long periods on average. Abundances are significantly lower in the topmost sediments and sediment layers below 50 cm depth. The large-scale vertical distribution is mainly influenced by the changes and pattern of temperature and discharge, which influences the current velocity of the surface and interstitial water. Effects appear quite different, when permanent flooded areas and areas that periodically fall dry on the surface are compared. Limnocamptus echinatus is forced deeper into the sediments of the gravel bar during low water temperatures and/or high discharge situations. On permanent flooded areas the vertical distribution is more stable over long periods, but higher fluctuations occur during short periods. The Limnocamptus echinatus population shows higher mobility in deeper sediment layers (40 to 60 cm sediment depth). Comparing longer periods, water flow and the transport of fine material differ in deeper sediment layers. The water current is much slower, producing a tendency for fine material sedimentation. This might be the main reason for the higher mobility in deeper sediment layers and the restriction of 90 per cent of the Limnocamptus echinatus population to a sediment depth of 50 cm. High mobility in vertical and horizontal directions within the bed sediments is interpreted as normal reactions and adaptations to the dynamic behaviour of the system, mainly forced by physical parameters. Biological parameters appear as subdominant for large-scale vertical distributions.     

Prioritizing removal of dams for passage of diadromous fishes on a major river system

Native diadromous fishes have been extirpated from much of the Susquehanna River system for nearly a century. Recent restoration efforts have focused on removal of dams, but there are hundreds of dams and presently there is no biologically based system to assist in prioritizing their removal. We present a new method that uses existing habitat suitability index models (HSI) for American shad Alosa sapidissima, alewife A. pseudoharengus, blueback herring A. aestivalis, and American eel Anguilla rostrata to prioritize the removal of non‐hydropower dams within the Susquehanna River system. We ranked HSI scores for each of the four species, association between a landscape‐scale factor and HSIs, length of river opened by removing a dam, and distance from the mouth at Chesapeake Bay for each dam and then calculated a mean rank prioritization for dam removal by averaging the ranks for the seven criteria. This prioritization method is resistant to outliers, is not strongly affected by somewhat arbitrary decisions on metrics included in the analysis, and provides a biologically based prioritization for dam removal that can be easily amended to include other metrics or adapted to other river systems and that complements other social and economic considerations that must be included in decisions to remove dams. Published in 2008 by John Wiley & Sons, Ltd.     

颗粒级配对管涌发展的影响试验研究

自行设计模型槽进行垂直渗流下砂土管涌试验,通过精细化量测手段获取管涌发展中土体几何、水力学参数及颗粒运动特点,研究颗粒级配对管涌发生发展的影响,揭示管涌细观机理。管涌型砂土可动颗粒本身级配影响流失颗粒最大粒径及颗粒流失量在渗流方向上的分布情况,但对最终颗粒流失量影响不大;可动颗粒含量对砂土是否发生渗透破坏及潜蚀发展过程影响密切,临界细颗粒含量及存在的自滤过程是要考虑的。通过体视显微镜,从细观尺度揭示临界细颗粒含量的砂土在管涌过程中,可能产生自滤反滤现象而使系统自稳定,进一步揭示该机制是由于砂土在复杂的水土相互作用过程中形成层间系数D15/d85值符合自稳定的级配特点所致。研究表明,对级配分布较广,缺失中间粒径的管涌型砂土,要判别砂土是否会发生渗透破坏及其临界水力梯度大小,在采用经典公式或经验曲线判断的基础上,有必要针对实际工程土体的级配特性与实际水力学条件,开展复杂水土作用过程的试验论证。     

Parameter optimization and design aspect for electrocoagulation of silica nano-particles in wafer polishing wastewater.

A systematic procedure has been proposed for the design of a multi-channel, continuous-flow electrocoagulation reactor of mono-polar configuration for the removal of sub-micron particles from wastewater. Using the chemical-mechanical-planarization (CMP) process as the target source of wastewater, a series of laboratory-scale studies were conducted to determine the required operating conditions for the efficient removal of the ultrafine particles. These operating criteria included charge loading (> or = 8 F m(-3)), current density (> or = 5.7 A m(-2)), hydraulic retention time (> or = 60 min), as well as the initially operational pH (7 to approximately 10). Furthermore, a steady-state transport equation with second-order reaction kinetics was employed to describe the rate of coagulation as the rate-limiting factor. The actual kinetic constant determined from the laboratory-scale experiments was approximately 1.2 x 10(-21) m3 s(-1), which was three orders of magnitude smaller than that calculated based on Brownian diffusion during the coagulation. The model was subsequently validated with a series of experiments using a pilot-scale electro-coagulation reactor geometrically similar to the laboratory-scale reactor with nearly twenty times volumetric scale-up.     

断层破碎带隧洞管棚支护参数设计方法

为确保断层破碎带内隧洞的安全施工和掌子面岩体稳定,提出了一种管棚支护参数的设计方法。首先,对管棚分段且取其中一部分作为有效计算长度,采用太沙基理论计算松散破碎岩体对管棚的荷载,根据约束条件将洞内管棚简化为两端固支梁,得到管棚弯矩、挠度和端部反力。然后,根据岩体和管棚的各类破坏条件,推导了管棚支护参数的计算公式。最后,介绍该方法在某断层破碎带隧洞的应用情况。该隧洞前期超前支护仅采用小导管,已发生数次掌子面坍塌。基于此方法分析小导管支护偏弱并进行了管棚支护设计,在之后开挖过程中收敛变形减小,管棚支护取得了较好的加固效果。研究成果可为断层破碎带隧洞管棚支护参数设计提供参考。