Application of Dynamic Programming Method in Optimization of Water Distribution Pipe Network

With a water-supply network by dynamic programming. The minimal as an example, the network was optimized annual discounted costs were taken as an objective function and node pressure etc. as constraint conditions. The alternative pipe diameters were optimized as per enumeration method and the group allowing objective function with the least values would be the optimized one. It is proved the optimized pipe network reduced by 11.49% in terms of cost and the optimized ben- efits proved much significant.

Optimal operation of water distribution networks under local pipe failures

The optimal operation of water distribution networks under local pipe failures, such as water main breaks, was proposed. Based on a hydraulic analysis and a simulation of water distribution networks, a macroscopic model for a network under a local pipe failure was established by the statistical regression. After the operation objectives under a local pipe failure were determined, the optimal operation model was developed and solved by the genetic algorithm. The program was developed and examined by a city distribution network. The optimal operation alternative shows that the electricity cost is saved approximately 11%, the income of the water corporation is increased approximately 5%, and the pressure in the water distribution network is distributed evenly to ensure the network safe operation. Therefore, the proposed method for optimal operation under local pipe failure is feasible and cost-effective.

Small Water Distribution System Operations and Disinfection By Product Fate

The Stage-2 Disinfectant and Disinfection By-Product (D/DBP) regulations force water utilities to be more concerned with their finished and distributed water quality. Compliance requires changes to their current operational strategy, which affect the formation of DBPs over time. This study quantifies changes in DBP formation and chlorine decay kinetics under different operational conditions and pipe materials found at many small-scale water utilities. A physical model (Pipe Loop) of a distribution system was used to evaluate the change in water quality from conditions such as having a high chlorine dosage entering the distribution system, using a chlorine booster system in the distribution system, and operation of clearwells/storage tanks. The High Chlorine Run (HC) is least favorable option with approximately 64% and 30% higher TTHMs than Normal Run (NR) and Chlorine Booster Run (CB), respectively. High Chlorine conditions also minimize the wall effects. The location of Boosters should always be after the storage systems to avoid extra contact time that can produce approximately 23% - 78% higher TTHMs. The following trends are discovered from the data analysis: Chlorine residual HC > CB > NR and TTHM NR > CB > HC.

Application of Ice Pigging in a Drinking Water Distribution System:Impacts on Pipes and Bulk Water Quality

Ice pigging is an emerging technique for pipe cleaning in drinking water distribution systems.However,substantial confusion and controversy exist on the potential impacts of ice pigging on bulk water quality.This study monitored the microstructural features and composition of sediments and microbial community structures in bulk water in eight multimaterial Chinese networks.Chloride concentration analysis demonstrated that separate cleaning of pipes with different materials in complex networks could mitigate the risk of losing ice pigs and degrading water quality.The microstructural and trace element characterization results showed that ice pigs would scarcely disturb the inner surfaces of long-used pipes.The bacterial richness and diversity of bulk water decreased significantly after ice pigging.Furthermore,correlations were established between pipe service age,temperature,and chloride and total iron concentrations,and the 15 most abundant taxa in bulk water,which could be used to guide practical ice pigging operations.

Effectiveness of urban distributed runoff model for discharge and water depth calculation in urban drainage pipe networks

Effective urban land-use re-planning and the strategic arrangement of drainage pipe networks can significantly enhance urban flood defense capacity.Aimed at reducing the potential risks of urban flooding,this paper presents a straightforward and efficient approach to an urban distributed runoff model(UDRM).The model is developed to quantify the discharge and water depth within urban drainage pipe networks under varying rainfall intensities and land-use scenarios.The Nash efficiency coefficient of UDRM exceeds 0.9,which indicates its high computational efficiency and potential benefit in predicting urban flooding.The prediction of drainage conditions under both current and re-planned land-use types is achieved by adopting different flood recurrence intervals.The findings reveal that the re-planned land-use strategies could effectively diminish flood risk upstream of the drainage pipe network across 20-year and 50-year flood recurrence intervals.However,in the case of extreme rainfall events(a 100-year flood recurrence),the re-planned land-use approach fell short of fulfilling the requirements necessary for flood disaster mitigation.In these instances,the adoption of larger-diameter drainage pipes becomes an essential requisite to satisfy drainage needs.Accordingly,the proposed UDRM effectively combines land-use information with pipeline data to give practical suggestions for pipeline modification and land-use optimization to combat urban floods.Therefore,this methodology warrants further promotion in the field of urban re-planning.

Water System Condition and Asset Replacement Prioritization

The goal of asset management is to identify and track the maintenance and replacement of assets that have reached their useful life. For that reason, gathering data and collecting information is a critical step when developing an asset management plan. Such data gathering includes physical and operational properties of the assets as well as collecting and tracking important events during the lifespan of the asset (i.e., pipe breaks, replacement year, maintenance performed, etc.). Critical factors in the asset management plan may be overlooked when there is no data or poor quality data. However, many utilities lack the resources for examining buried infrastructure and lack good quality work order data, so other methods of data collection are needed. The concept for this paper was to develop a means to acquire data on the assets for a condition assessment to identify pipes that were most likely to break and those with the highest consequences for same. Three utilities were used as examples. It was found that for buried infrastructure, much more information was known than anticipated but the actual predictions relied on only a few factors related to pipe type. However, there is a need to track the consequences, in this case breaks, which would indicate a failure. The latter would be useful for predicting future maintenance needs and the most at-risk assets, but is often missing in utility systems as many utilities do not adequately track breaks sufficiently. In this case two utilities were analyzed and predication on a third was developed.

螺杆泵转速对油水旋流分离管流场特性的影响

旋流分离器在井下采油螺杆泵作用下会发生复杂的振动现象,对旋流分离器内部流场造成一定影响。为研究螺杆泵不同转速下旋流分离器内部流场的变化规律,以同井注采工艺中螺杆泵作用下的旋流分离管柱为研究对象,针对振动壁面旋流分离管柱结构及工作特点,基于计算流体动力学方法、计算固体力学方法以及流固耦合理论,建立流固耦合力学模型;利用流固耦合分析方法,对双螺杆泵转动条件下井下旋流分离管柱内速度场、油相分布、涡量及湍动能等流场特性进行分析。分析结果表明:随着螺杆泵转速升高,分离器内切向速度和轴向速度强度逐渐减弱,径向速度的不对称性逐渐加剧,转速的周期性变化还会造成径向速度场分布的偏移;螺杆泵不同转速下旋流分离器内部涡量分布不同,随着转速升高,溢流管以及锥段部分附近相关流场的涡旋明显增强;旋流器溢流口附近油相体积分数会随着螺杆泵转速的升高而减小;不同螺杆泵转动状态下,大颗粒油滴的分布不同。所得结果可为螺杆泵井下旋流分离同井注采系统的设计及螺杆泵的转速设定提供参考。

管道特性曲线法在注射水储存分配系统的应用

应用管道特性曲线法对制药企业注射水储存分配系统的流量与压力关系进行了分析探讨,提出了简化计算的方法,并结合具体工程案例进行了分析比较。针对系统实际运行调试过程中出现的常见问题,提出了相应的理论依据及措施。

基于好房子建设的建筑水系统技术提升与创新

好房子建设是住房和城乡建设部重点工作之一,建筑水系统(给水、热水、排水)与房屋使用者关系最为密切,是好房子的重要组成部分。建筑给水系统应提供优质的饮用水,建立优质饮用水的水质安全保障体系。建筑热水系统采取洗浴废水废热利用的节能低碳技术,降低生活热水的使用成本。建筑排水系统应安全排出污废水并不对室内环境产生负面影响,采用高安全性的排水系统。好房子中的建筑水系统还要符合国家战略发展需求,在设计理念、技术、产品上开展创新性的工作。

AFT Fathom在某大型化工厂循环水系统水力学计算中的应用

应用AFT Fathom软件对某大型化工厂循环水系统管网进行水力学分析计算,得出循环水系统管网的流量、压力分配情况。与传统手算方法相比,该方法能够优化设计,提高设计准确性,减少工程运行成本,对于同类型给水排水系统的设计优化具有指导意义。

基于粒度识别的烧结智能配水技术研究与应用

针对烧结混合料水分难以精准测量的问题,本文将粒度识别技术与智能配水相结合,开发了烧结智能配水系统。该系统直接将水分的调整与混合料粒级组成建立关系,通过建立基于混合料粒度的有监督自学习优化控制算法对加水量进行实时调整,以达到烧结混合料加水的自动闭环控制。经工业实践跟踪发现:应用该智能配水系统后,烧结利用系数由1.36 t/(m^(2)·h)增加到1.41 t/(m^(2)·h),烧结矿转鼓指数由78.10%增加到78.64%,烧结负压由12.71 kPa下降到12.14 kPa,烧结主抽频率由39.4 Hz下降到38 Hz。

锅炉水冷壁管爆管原因研究

一台蒸汽锅炉的水冷壁管在同一部位连续发生爆管,严重威胁生产安全。文章通过研究爆口管材的材质、力学性能、金相组织以及锅炉结构和水冷壁中的流量分配等,分析爆管原因,并提出循环回路的优化措施,以期为后续类似问题的处理提供参考。

母管制热电联产机组闭式循环冷却水系统节能改造

针对某母管制热电联产机组闭式循环冷却水系统运行中存在的泵选型偏大、能耗高等问题,对闭式循环冷却水泵叶轮优化改造,保持额定流量不变,减小了扬程。将单元制的闭式循环冷却水系统改造为“大母管制”。经过长时间运行测试,在非夏季工况闭式循环冷却水系统可减少1台水泵运行,电功率减少约166kW,每年可节约52万元,获得了较大的经济效益。

西藏扎拉水电站引水发电建筑物设计

为解决扎拉水电站引水发电建筑物设计过程中存在引水隧洞穿越活动断裂,引水隧洞Ⅳ类、Ⅴ类围岩洞段占比较大,调压室顶部层间密集剪切带,巨型冲击式机组配水环管充水保压浇筑混凝土等重大技术难点,充分论证引水隧洞过活动断裂洞段增加衬砌混凝土厚度、短分节、上部设置排水洞(兼勘探洞、灌浆洞、监测洞)等措施的有效性。通过优化布置和计算线弹性有限元结构,提出了引水隧洞Ⅲ类、Ⅳ类、Ⅴ类围岩分别选取40,60,80 cm厚度衬砌结构设计,调压室选取1.5,1.0 m厚度衬砌结构设计,配水环管选取5.5 MPa的充水保压埋设方式,配水环管分区配置钢筋来优化结构设计。相关设计成果可供同类工程参考。

烧结混合料粒度在线识别研究与应用

烧结过程中混合料配水的稳定控制对生产的稳定优质有至关重要的影响。本文基于烧结加水混料制粒的第一性原理,采用平均灰度处理、频率域法增强等技术进行了图像增强,利用Canny算子实现图像的边缘检测分割以及Halcon集合运算与区域变换算子进行处理,从而得到接近真实颗粒形态的轮廓特征,解决了混合料粒度识别的难题。通过试验对比发现试验物理筛分与图像识别结果两者偏差均在5%以内,基本可以表征混合料的整体特征;同时,验证了实时监测结果对加减水过程混合料粒度数据变化较为敏感,且对混合料加减水过程有很好的跟随性,为下一步基于混合料粒度识别的自动配水奠定了坚实基础。

输水工程大直径钢管外包混凝土垫层结构研究

为研究输水工程中垫层弹模和厚度对钢管外包混凝土结构应力分布的影响,确定垫层参数的最优取值,以引汉济渭二期输水工程为背景,运用有限元软件,对大直径钢管外包混凝土垫层结构进行分析研究。确定钢管及外包混凝土在垫层不同弹性模量、不同厚度下的应力状态。结果标明:设置垫层后,外包混凝土主应力明显降低,有效改善钢管及外包混凝土的应力分布;随着垫层弹性模量的减小,钢管的等效应力逐渐增加,外包混凝土的主应力逐渐减小;垫层厚度小于20 mm时,外包混凝土最大主应力随垫层厚度增大而减小,厚度大于20 mm时,外包混凝土最大主应力减小情况不显著,垫层最优厚度10~20 mm;垫层弹性模量和厚度同比例时,钢管等效应力和外包混凝土主应力基本不变。研究成果对输水工程中大直径钢管外包混凝土垫层结构选择具有参考意义。

Review on corrosion and corrosion scale formation upon unlined cast iron pipes in drinking water distribution systems

The qualified finished water from water treatment plants(WTPs) may become discolored and deteriorated during transportation in drinking water distribution systems(DWDSs), which affected tap water quality seriously. This water stability problem often occurs due to pipe corrosion and the destabilization of corrosion scales. This paper provides a comprehensive review of pipe corrosion in DWDSs, including corrosion process, corrosion scale formation, influencing factors and monitoring technologies utilized in DWDSs. In terms of corrosion process, corrosion occurrence, development mechanisms, currently applied assays, and indices used to determine the corrosion possibility are summarized, as well as the chemical and bacterial influences. In terms of scale formation, explanations for the nature of corrosion and scale formation mechanisms are discussed and its typical multilayered structure is illustrated. Furthermore, the influences of water quality and microbial activity on scale transformation are comprehensively discussed. Corrosion-related bacteria at the genus level and their associated corrosion mechanism are also summarized. This review helps deepen the current understanding of pipe corrosion and scale formation in DWDSs, providing guidance for water supply utilities to ensure effective measures to maintain water quality stability and guarantee drinking water safety.

Two-dimensional pipe leakage through a line crack in water distribution systems

In water distribution systems,water leakage from cracked water pipes is a major concern for water providers.Generally,the relationship between the leakage rate and the water pressure can be modeled by a power function developed from the orifice equation.This paper presents an approximate solution for the computation of the steady-state leakage rate through a longitudinal line crack of a water distribution pipe considering the surrounding soil properties.The derived solution agrees well with results of numerical simulations.Compared with the traditional models,the new solution allows assessment of all the parameters that related with leakage including the pressure head inside the pipe,hydraulic conductivity,crack size and its position,and pipe size and its depth.

Bacteriological challenges to asbestos cement water distribution pipelines

Asbestos cement （AC） pipes were commonly installed in the drinking water distribution systems from the mid 1920s to the late 1980s. In recent years, an increase in the number of water main breaks has occurred in the AC portions of some pipe networks, which can be partially attributed to the corrosion of the aged pipes. This study evaluated the potential role that microorganisms may have played in the degeneration and failure of AC pipes. In this study, a fresh AC pipe section was collected from the distribution network of the City of Regina, Canada and examined for microbiological activities and growth on inside surfaces of pipe sample. Black slime bacterial growths were found to be attached to inner pipe surfaces and a distinctively fibrous internal coating （patina） with iron oxides was formed over the time. The microbial populations inside the patina and the black slime were tested with BART^TM testers. Heterotrophic aerobic bacteria （HAB） and slime forming bacteria （SLYM） dominated in both the black growths and inside the patina. Iron related bacteria, denitrification bacteria and sulfate reducing bacteria were also commonly present. Microbial challenge assays were conducted by submerging the cut segments of the AC pipe into selected bacterial cultures for a period of 10 days under both aerobic and anaerobic environments. Weight changes were determined and the surface morphology was examined for each of the assayed pipe segments. Results indicated that acid producing bacteria, SLYM and HAB could facilitate the pipe weight loss under anaerobic environments.

Water Leakages in Public Water Supply System and How to Prevent Them

The article addresses the results of effective water losses prevention in public water supply systems, focusing on procedures for monitoring hidden leaks as the main part of losses and as the first step to control and prevent them. The described methodology has been applied based on a cross-border cooperation between twin capital cities Vienna and Bratislava in the Central Europe Region within the project deWaloP （Developing Water Loss Prevention） and adopted in Bratislava Water Company （BVS） in the Slovak Republic. The paper provides a complex of simple and easily available practices for analyses of water distribution measurements bringing essential information as to the necessity to use advanced procedures to actively reduce leakage. These practices involve minimum night flows analyses, hydrodynamic pressures analyses, pinpointing of water leakages by working with valves in the water network, the methodology of setting alarm limits for measured data, as well as use of advanced practices to obtain missing topologic data. As the water infrastructure in former socialistic countries are in bad technical condition and the lack of pertinent operational data is a significant obstacle to the application of a more sophisticated methodology based on GIS and other information systems, the procedures focus on using the most simple way to evaluate and control water losses. Finally, the introduction of described methodology in Bratislava Water Company after many years of unsuccessful effort even with expensive sophisticated leakage equipment brought positive outputs and the graph line of water losses level is finally going down. The use of expensive multi-correlating equipment together with human resources on the basis of implementing the above described leakage monitoring will subsequently become more effective, as it shall pinpoint major leakages, disclosure and removal of that shall significantly contribute to the effective reduction of water losses.