七流中间包结构优化的物理模拟

采用物理模拟的方法对某厂七流中间包进行了结构优化。研究结果表明,无控流装置中间包各流流动特性一致性很差,原型控流装置起到了一定的导流作用,但1流、2流与3流、4流差异较大,死区比例为22.68%;优化后的控流装置可减小各流之间的差异,延长平均停留时间到520.2s,减小死区比例至16.75%,有利于生产顺行和铸坯质量的提高。     

高炉合理煤气流分布探讨

提出了合理煤气流分布的概念，在分析国内外高炉煤气流分布基本型式及特征的基础上，探讨了南钢目前高炉煤气流的分布现状及对技术经济指标的影响，分析了影响煤气流分布的因素，提出了煤气流分布由合理向最佳的发展方向及需要的条件。     

焦化能量流、能量流网络解析及重构

回顾了焦化能量流、能量流网络的发展历程,分析了以蒸汽为传热介质的能量流、能量流网络与以导热油为传热介质的能量流、能量流网络在热量利用效率方面存在的巨大差距及原因,指明了利用导热油做为传热介质重构焦化能量流网络的效率优势,重点介绍了利用导热油回收上升管焦炉荒煤气余热,形成"卡诺循环"高效传热网络并与粗苯、蒸氨等工艺用能耦...     

钢铁制造流程物质流与能量流协同优化研究进展

 钢铁企业具有流程长、能耗高、排放量大等特点,钢铁制造流程物质流与能量流的协同优化是实现高层次系统节能的关键。为此,对钢铁制造流程物质流和能量流优化的研究进展与应用进行了综述,在此基础上阐述了钢铁制造流程物质流与能量流协同优化的主要研究方向,即物质流与能量流的相互影响和协同规律研究、考虑能源约束的生产计划编制和物流与能流耦合调度。提出了解决协同优化模型构建和求解的关键在于科学的物质流与能量流协同表征方法、生产计划与能源计划时间粒度的统一和智能算法的优化。     

高炉无钟炉顶布料料流宽度数学模型及试验研究

针对高炉实际操作过程中炉料的料流宽度与档位划分不一致,无钟炉顶布料后煤气流分布波动变化大,高炉顺行困难的问题,对布料操作中料流宽度计算的不足,重点考虑了炉料的受力变化对料流宽度的影响,分析了科氏力对料流宽度的影响,提出了分段考虑科氏力来计算料流宽度,修正计算了溜槽出口水平宽度的误差,建立了无钟炉顶布料的料流宽度数学模型。通过工业现场1∶10的模型试验,验证了该数学模型计算料流宽度的正确性和合理性,将料流宽度和溜槽倾角调整相一致的原则应用于2 500 m3高炉,达到了布料分布合理,气流稳定,高炉顺行的目的。     

八流方坯连铸中间包控流装置优化的水模研究

通过八流方坯连铸中间包水模实验,研究了不同控流装置对其流动特性的影响。研究表明:对比原挡墙,中间包的控流装置改为新挡渣墙后,表征中间包流动特性的流动特性因素有了明显的改善。在新挡墙的基础上,对稳流器和挡坝等控流装置关于控流效果的影响进行了实验研究,发现每个方案中的一个或者多个控流参数有利于进一步改善中间包的控流效果。通过对比和分析这几种控流方案对改善中间包内流体流动特性的效果,确定了最优方案。     

移动床固体颗粒绕流顺排圆管的过程

工业中常用带埋管的移动床来加热或冷却固体颗粒物料,其过程涉及颗粒流与管壁间的复杂传热,而颗粒绕流圆管的流动过程对其传热效果起着决定性作用.为简化描述颗粒的流动过程,通过分析颗粒绕流圆管的特性,建立了拟漏斗流模型,并给出了模型所需颗粒绕流圆管描述参数的取值范围,模型可用以求取颗粒绕流圆管的速度场和时长等参数.建立了埋管移动床实验系统,考察了颗粒绕流顺排管束的过程;同时利用离散单元法(DEM)对该过程进行数值模拟,获得了颗粒绕流圆管的流动过程,并利用移动床实验结果对比验证了离散单元法数值模拟结果;最后,对比了基于拟漏斗流模型的计算结果和离散单元法数值模拟结果,并根据此结果对拟漏斗流模型的描述参数进行了确定.      

喷枪口煤粉流控制

从喷枪口煤粉流的流量、长度、流向三个方面论述了煤粉流的控制意义，提出了煤粉流的控制方法。     

一种连续型螺旋折流板换热器的设计

在总结目前国内外螺旋折流板换热器研究现状的基础上,选定了较合适的螺旋折流板换热器螺旋角。将一种已有的弓形折流板的间距用Aspen软件进行模拟计算,找出换热性能比最好的弓形折流板换热器的折流板间距。并在参考文献研究的基础上,用计算出的最优间距设计出了一种连续型螺旋折流板换热器。     

三流Τ型中间包内控流装置优化的物理模拟

通过三流T型连铸中间包物理模拟实验,研究了直挡墙、V型挡墙及其与抑湍器组合控流装置对中间包流动特性的影响。结果表明,直挡墙控流装置的控流效果优于无控流装置的中间包,但不如设计合理的V型挡墙控流装置;V型挡墙与挡坝组合控流装置（方案Ⅴ）的控流效果较好,在其基础上加入抑湍器后控流效果并不理想。因此,提出了针对三流T型中间包控流装置的优化设计方案。     

River Training and Ecological Enhancement Potential Using In-Stream Structures

The use of in-stream flow training structures for channel stabilization has become increasingly popular due to its potential cost effectiveness and ecological benefits. When properly designed and maintained, these structures help to protect the channel from erosion and lateral migration and may also provide grade control. Additionally, in-stream structures may improve fish and macroinvertebrate habitat and increase hyporheic exchange. However, a large number of these projects fail due to inadequate design guidelines. In this study, various types of in-stream sill and deflector structures are described. A literature review including case studies, journal articles, and standards developed by various agencies suggests design guidelines which are currently available but do not meet the rigorous engineering-based hydraulic design criteria necessary for success. A practitioner opinion survey of personnel from state agencies, federal agencies, and private firms indicates that these structures are being used extensively in at least 76% of the USGS physiographic provinces. In general, respondents indicated that in the areas of cost, performance, maintenance, and environmental enhancement in-stream structures are preferable to the most common alternative: riprap revetment. Information from 39 case studies suggests that successful projects involve multiple structures and are located in rivers with relatively high aspect ratios.     

Assessing the Impacts of Nutrient Load Uncertainties on Predicted Truckee River Water Quality

This study examined the effects of uncertain model boundary conditions on dissolved oxygen (DO) predictions for the lower Truckee River, Nevada using an augmented version of the EPA’s Water Quality Analysis Simulation Program Version 5 (WASP5) that included periphyton, or attached algae, in eutrophication kinetics. Uncertainty analyses were performed on selected organic nitrogen (ON) and carbonaceous biochemical oxygen demand boundary conditions using Monte Carlo techniques. The stochastic model was run using boundary concentrations assigned from observed probability distributions. Ranges of simulated values were used to construct confidence intervals, the magnitudes of which indicated the uncertainty associated with model predictions. Uncertainty in agricultural ditch return concentrations had minimal effects on in-stream model predictions, as predicted values of daily minimum and maximum DOs, daily average ON, and periphyton biomass all failed to show significant variability as a result of ditch concentration uncertainty. This result indicates that while ditch return nutrient loads are not trivial, their exact concentrations are not needed to make relatively accurate predictions of in-stream DO. However, uncertainty in the upstream ON boundary did result in significant uncertainty during summer months with regard to in-stream model predictions of ON, periphyton biomass, and DO. The model is clearly more sensitive to changes in this boundary than to changes in agricultural ditch concentrations.     

Pool Quality Index: New Method to Define Minimum Flow Requirements of High-Gradient, Low-Order Streams

High-gradient (>1%), low-order streams, characterized by hydraulically nonuniform and heterogeneous channels, represent a problem for the most widely employed habitat-based in-stream flow methods (IFIM-PHABSIM). In a nonuniform high gradient and turbulent channel, as low-order streams usually are, the classical 1D hydraulic modeling, ordinarily employed by in-stream flow models to simulate the changes in fish habitat with the flow, could be questionable, if not completely inapplicable. Channel morphology in fact plays a major role in association with hydraulics in determining the abiotic environments (biotopes) in which aquatic communities live. Particularly, in low-order river systems, different channel form features shape the biological community that can be hosted in a certain biotope. For this reason, the link between morphology and discharge is important when evaluating possible impacts of flow reduction on aquatic organisms. To represent the relationship between hydraulics and channel morphology quantitatively, a hydraulic diversity concept has been adopted. Studies from the literature have revealed that, in a regulated river, a decrease of the environmental variability including hydraulic diversity quite often resulted in a downstream decrease of the macro-invertebrate diversity, which can consequently affect fish biomass. These considerations create the ground for a hydraulic diversity-discharge–based in-stream flow method with the aim to promote high community diversity in a low-order regulated stream. A statistic ordination technique (correspondence analysis) applied to 370 hydraulic sections helped to identify four main morphological units (pools, deep pools, and slow and fast riffles) in terms of hydraulic diversity. In each morphological unit, the hydraulic diversity-discharge relationship was investigated and modeled by means of best-fit regression curves. Combining the hydraulic diversity-discharge curves from different morphological units (pools and riffles), a simplified model of the stream [pool quality index (PQI)] was obtained. This model has been applied to make recommendations for the minimum flow requirements in six low-order river sites. PQI recommendations were consistent with hydrology and other hydrology-based in-stream flow methodologies. Finally, a multiple regression model indicated that in 12 low-order stream sites a good deal of the variability of macro-invertebrate diversity is explained by the availability of hydraulic environments modeled by means of PQI curves. In conclusion, given the encouraging cues about the ecological meaning of PQI and the possibility to overcome difficulties typically encountered by other methods in the low-order river modeling, PQI can be considered a valid alternative for assessing the in-stream flow needs of low-order streams.     

Formation of Breakup Ice Jams at Bridges

Bridges can impede the passage of river ice during the breakup event and promote formation of ice jams, with adverse socioeconomic and ecological impacts. Design for ice passage at bridges has largely been empirical and qualitative so that avoidance of ice-jam instigation is often uncertain. It is thus important to develop rational design criteria, based on a thorough understanding of the factors governing the interaction between bridges and ice. This concern is quantified by utilizing recent advances on breakup initiation and comparing driving and resisting forces when the sheet ice cover is about to be set in motion. Retention of ice sheets by in-stream piers can lead to jamming via accumulation of ice rubble that may be arriving from upriver. The resulting methodology is applied to two case studies and yields results that are in full accord with local experience. Though the present findings pertain to the obstruction created by in-stream piers, similar reasoning can be applied to constrictions that may be caused by protruding bridge abutments.     

Optimal Wasteload Allocation Procedure for Achieving Dissolved Oxygen Water Quality Objectives. I: Sensitivity Analysis

A method is presented to compute sensitivities of in-stream dissolved oxygen (DO) with respect to perturbations in the load vector and the reaction coefficients that make up the eutrophication cycle. It is shown that the direct sensitivity method, i.e., the repetitive solution of the direct problem, produces the desired information, however at a large computational cost. The utilization of the adjoint sensitivity method proves to be a much more efficient way to compute these sensitivities as large subsets of the sensitivity information domain can be easily extracted with just a few runs. It is found that for the given problem setup, in-stream DO is most sensitive to ammonia, effluent DO, algae, and carbonaceous biochemical oxygen demand (CBOD) loads. Additionally, the computed sensitivities vary considerably in their general trend over the simulation time. Sensitivities also are computed with respect to the reaction coefficients (26 total) that govern the interdependency of all constituents. Sediment oxygen demand proves to be the coefficient with the highest influence that is three orders of magnitude higher than the next set of coefficients comprised of reaeration, CBOD degradation, nitrification, and denitrification. All other coefficients have a negligible influence on DO concentrations. Computations are carried out using a two-dimensional model formulation applied to a long rectangular channel with varying width and slope and periodic but unsteady flow conditions.     

Hydraulic Complexity Metrics for Evaluating In-Stream Brook Trout Habitat

A two-dimensional hydraulic model (River2D) was used to investigate the significance of flow complexity on habitat preferences of brook trout (Salvelinus fontinalis) in the high-gradient Staunton River in Shenandoah National Park, Virginia. Two 100-m reaches were modeled where detailed brook trout surveys (10–30-m resolution) have been conducted annually since 1997. Spatial hydraulic complexity metrics including area-weighted circulation and kinetic energy gradients (KEG) were calculated based on modeled velocity distributions. These metrics were compared to fish density in individual habitat complexes (10–30-m subreaches) to evaluate relationships between fish location and average flow complexity. In addition, the fish density was compared to additional habitat variables including percent cascade (CS), pool (PL) and riffle, and in-stream (ISCN) and riparian cover. There were negative correlations between modeled mean velocity (VEL) and maximum depth (MAXD) and fish density; however, there were no statistically significant correlations between KEGs or area-weighted circulation and fish density. Fish density was negatively correlated to ISCN and positively correlated to the percent of the channel dominated by protruding boulders (BD) and CS. The structural complexity of cascade habitat and areas with protruding boulders creates complex flow patterns indicating that flow complexity plays an important role in brook trout habitat preferences at the local scale. Linear discriminate analysis was used to further investigate the relationships between habitat variables and fish density. Using backward stepwise variable selection, the final explanatory model contained the BD, ISCN, MAXD, PL, and VEL variables. These observations indicate that at a coarse spatial scale hydraulic complexity may be an important component in fish habitat preferences; however, other habitat variables cannot be ignored and the hydraulic complexity metrics calculated using 2D modeling results were not explanatory. While spatial hydraulic complexity metrics provide quantifiable measures for evaluating stream restoration project impacts on in-stream habitat quality, the relationships between fish density and hydraulic complexity were not straightforward. This is likely due in part to modeling limitations in this high-gradient complex stream. Further research is needed at a range of spatial scales, stream types, and fish species to fully investigate the use of hydraulic complexity metrics to quantify in-stream habitat.     

Benefits of Flexible Irrigation Water Supply

This paper develops a general introduction into the concepts of a flexible irrigation water supply in rate, frequency, and duration together with the benefits to the farmer for doing so. A flexible water supply allows the farmer the opportunity to choose an on-farm irrigation practice that best meets the needs of the desired crop, the cost and availability of labor, and other local economic or social situations. As water quality issues are more closely tied to the issues of water quantity, water use efficiency must improve. A flexible irrigation water supply can lead to improved efficiencies. Non-point-source pollution and in-stream flows also become factors in other social issues such as the care of threatened and endangered species. Flexible supplies can again help. This paper also shows, through a case study, the application of a limited rate arranged system to an irrigation district in Washington State where significant flexibility has led to efficient water use and economic and environmental benefits.     

Two-Dimensional Depth-Averaged Flow Modeling with an Unstructured Hybrid Mesh

An unstructured hybrid mesh numerical method is developed to simulate open channel flows. The method is applicable to arbitrarily shaped mesh cells and offers a framework to unify many mesh topologies into a single formulation. A finite-volume discretization is applied to the two-dimensional depth-averaged equations such that mass conservation is satisfied both locally and globally. An automatic wetting-drying procedure is incorporated in conjunction with a segregated solution procedure that chooses the water surface elevation as the main variable. The method is applicable to both steady and unsteady flows and covers the entire flow range: subcritical, transcritical, and supercritical. The proposed numerical method is well suited to natural river flows with a combination of main channels, side channels, bars, floodplains, and in-stream structures. Technical details of the method are presented, verification studies are performed using a number of simple flows, and a practical natural river is modeled to illustrate issues of calibration and validation.     

Diffusive Behavior of Bedform-Induced Hyporheic Exchange in Rivers

Solute transport in natural streams is a complex phenomenon that involves both in-stream dispersion and mass exchange with the porous zones surrounding the water body. Due to the complex nature of the riverine systems several models may be used to simulate and analyze the transport of solutes with different degrees of complexity. The bedform-induced hyporheic transport is a stream-subsurface exchange mechanism that can be reproduced in controlled systems, such as laboratory flumes. Application of a simple Fickian diffusion model to laboratory data obtained with passive solutes and stationary bedforms proves successful within a range of durations of the contamination process. A dimensionless form of the diffusion coefficient, scaled with dynamic, physical, and geometric properties of the system is derived by comparison with another physically based model. A prediction of the dimensionless diffusion coefficient is obtained as a function of the timescale of the exchange process and is validated with a few sets of results from laboratory tests.     

Temporal Development of Scour Holes around Submerged Stream Deflectors

Deflector structures used in many fish habitat rehabilitation schemes are frequently overtopped, yet few studies have examined the scour patterns created around submerged models. Furthermore, laboratory studies typically test smooth-surfaced structures, whereas those installed in natural rivers are generally made of logs or boulders. This study uses rough-surfaced paired deflectors to investigate the temporal evolution of scour for three overtopping ratios in identical approach flow conditions in a flume. Results show that maintaining identical discharge and raising the deflector height, which reduces the overtopping ratio (i.e., flow depth divided by structure height), generates increased depth and volume of scour next to the structures. The location of maximum depth and the rate of scouring with time is similar for the two highest deflectors (overtopping ratios of 1.22 and 1.83), but different for the lowest deflector model (overtopping ratio of 3.67). To improve the success rate of river restoration projects using in-stream structures, the overtopping ratio should be considered in equations that predict the scour depth evolution with time.