污水处理厂粗格栅深基坑支护方案确定及质量控制

污水处理厂粗格栅属于深基坑工程,基坑支护方案的确定与质量控制是污水处理厂施工的重点。以天津市空港物流加工区污水处理厂为例,对粗格栅深基坑支护方案及质量控制措施进行了系统阐述,以期为同行业深基坑支护方案的制定提供参考。     

冀州市污水处理厂的工艺设计和设计特点

冀州市污水处理厂深度处理污水后,出水排放至稀释能力较小的城市景观明渠。介绍了该厂的设计规模,对粗格栅间、进水提升泵房、旋流沉砂池、初沉池、浮动填料生化反应池、二级提升泵站、湿地、鼓风机房和污泥浓缩脱水间等构筑物设计及设备配置情况和污水处理工艺作了介绍。对四连体构筑物、浮动填料生化池、曝气器、湿地及后置投加化学除磷等生态设计的特点进行了经验总结。该厂运行出水水质达到国家一级标准的A标准,运行稳定。     

沙特第九污水处理厂第五期工程的设计与运行

以沙特阿拉伯第九污水处理厂第五期工程为例,介绍了该水厂的曝气除砂工艺,对格栅间、曝气沉砂池、初沉池、A/O池、二沉池等主要构筑物以及设计参数进行了研究,总结了该项目的设计难点以及设计运行中存在的一些问题,为以后中东地区的污水处理厂设计积累了宝贵经验。     

大面积不等高不排水沉井施工技术例析

粗格栅及进水泵房是南京江心洲污水处理厂扩建工程的一个重要项目，主要为河西奥林中心收集到的污水提供动力。污水经粗格栅后由污水泵输送至江心洲污水厂进行处理。粗格栅及进水泵房为钢筋混凝土结构，采用不排水下沉法施工。     

采用A/O工艺的污水处理厂提标改造工程设计

辽宁省某污水处理厂设计规模为10×104m3/d,采用A/O处理工艺。升级改造工程要求设计出水水质从《城镇污水处理厂污染物排放标准》(GB 18918—2002)一级B标准提升至一级A标准。针对出水总氮超标问题,增设一组A/O生化池,以降低脱氮负荷,同时增设碳源投加系统,从而保证了脱氮效率;针对进水含砂量大,导致粗、细格栅和提升水泵等机械设备磨损严重的问题,提标改造中增设了粗格栅及平流沉砂池,使进水中的砂在平流沉砂池内预沉,同时去除大颗粒漂浮物,从而保证了粗、细格栅及提升泵的正常运行。实际运行表明,提标改造工程出水水质完全达到一级A标准。     

“T”形沉井的下沉施工技术

1 工程概况 浙江省温州市某污水处理厂工程位于温州市燕化镇桃花岛以南,蒲州河以东,团江西岸,该污水处理厂工程的粗格栅间及进水泵房采用沉井结构,该沉井平面形状为“T”形(见下图),其中“T”形的“-”部分为进水泵房,“I’部分为粗格栅间。 该沉井外包尺寸为30100×1933mm,“T”形肋宽为10900mm,面积约为400m~2;沉井进水泵房高度为     

城市污水处理厂预处理系统的改造设计

污水预处理对污水处理厂的正常运行起着非常重要的作用,结合无锡市锡山区污水处理厂的工程改造实例,针对实际工程运行过程中细格栅、厌氧水解池等预处理系统中出现的问题,介绍了细格栅池以及升流式膜法水解池的设备选型、改造技术参数以及工艺特点.     

试谈土钉墙技术在深基坑支护中的应用

驻马店污水处理厂位于驻马店市橡林乡刘楼村．设计日处理污水能力为10万m^3／d。粗格栅和提升泵房是污水厂预处理单位工程．位于厂区内东北角。该构筑物是污水处理厂中埋置最深的单位工程，也是施工难度较大的工程项目。     

粉碎型格栅用于污水泵站存在的问题和使用建议

粉碎型格栅具有环境友好、可实现无人值守及泵站地埋化等优点,但也存在投资费用高、维修周期长、维修费用贵、运行能耗高、对污水处理厂影响大等问题,基于杭州市污水泵站应用粉碎型格栅的经验,提出了设计和运行管理方面的相关建议。     

新型格栅除污机在污水处理厂的应用

随着我国城镇污水处理厂污染物排放标准的进一步提高和污水处理事业的快速发展,各种污水处理新工艺、新流程应运而生,对污水处理厂预处理工艺单元的设置也提出了更加严格的技术要求。作为一种重要的预处理工艺单元设备,格栅的选用成为污水处理厂的关注热点。文章分析了传统格栅的不足,重点介绍了转鼓式细格栅及网板式阶梯格栅的原理、作用、结构性能及工程应用。通过应用新型细格栅,能够有效去除污水中的纤维和毛发等物质,为后续单元的正常、稳定运行提供基本保障。     

On artificial dilution of point source mercury emissions in a regional atmospheric model

Previously, we developed and applied a regional atmospheric mercury model to a domain covering most of North America at a horizontal grid resolution of 100 km. The implication of using this coarse resolution is that point sources of mercury emissions are instantaneously spread over a grid volume of horizontal dimensions 100 x 100 km2 and a vertical dimension equal to the depth of the grid cell where the point source emissions are released. Since point sources comprise a significant majority of a regional mercury emissions inventory, it is important to understand what effect this artificial dilution may have on calculated mercury concentrations and deposition fluxes. To understand this effect, we conducted model simulations using a finer grid, embedded within the original coarse grid, over a sub-domain that includes over 50% of the largest mercury point sources in the north-eastern United States. The horizontal resolution of the fine grid is 20 km, i.e. it is five times smaller than that of the coarse grid. We compared short-term (daily) and long-term (annual) averaged mercury concentrations, and deposition (wet and dry) fluxes on the coarse and fine grids. As expected, the effect of grid resolution is more clearly seen in close proximity to point sources than at remote locations. For short-term averages near major point sources, the peak concentrations and dry deposition fluxes of mercury from the fine grid are almost a factor of two greater than the corresponding estimates from the coarse grid. At remote locations, however, the concentrations and dry deposition peaks estimated by the two model grid resolutions are more comparable. For total wet deposition of mercury, the distinction between the fine and the coarse grid model results is less significant, regardless of the location. This could be due to the redistribution of precipitation fields or the effect of mercury aqueous chemistry. The effect of grid resolution is more important when model estimates are averaged over short time periods, e.g. daily, as opposed to over long periods, e.g. seasonally and annually.     

Development of adaptive coarse grid generation methods for fast fluid dynamics in simulating indoor airflow

The control of indoor air quality and thermal comfort requires faster-than-real-time simulations of air distribution. One approach to achieve such simulations is to use coarse grid. This study developed two adaptive coarse grid generation methods by analysing the grid-related truncation errors in the solution of the Navier–Stokes equations by fast fluid dynamics (FFD). Method 1 generates a grid that is coarser than that for a grid-independent solution but can still provide accurate FFD predictions. Method 2 generates a very coarse grid that provides acceptable FFD predictions. This study assessed the performance of the developed methods by using them to simulate three typical indoor airflows. The assessment showed that the coarse grid generated by Method 1 accelerated the FFD simulation by at least two to five times, with similar computational accuracy. The coarse grid generated by Method 2 provided faster-than-real-time FFD simulations for the cases tested in this study.     

Feasibility of utilizing numerical viscosity from coarse grid CFD for fast turbulence modeling of indoor environments

Computational fluid dynamics (CFD) is a useful tool in building indoor environment study. However, the notorious computational effort of CFD is a significant drawback that restricts its applications in many areas and stages. Factors such as grid resolution and turbulence modeling are the main reasons that lead to large computing cost of this method. This study investigates the feasibility of utilizing inherent numerical viscosity induced by coarse CFD grid, coupled with simplest turbulence model, to greatly reduce the computational cost while maintaining reasonable modeling accuracy of CFD. Numerical viscosity introduced from space discretization in a carefully specified coarse grid resolution may have similar magnitude as turbulence viscosity for typical indoor airflows. This presents potentials of substituting sophisticated turbulence models with inherent numerical viscosity models from coarse grid CFD that are often used in fast CFD analysis. Case studies were conducted to validate the analytical findings, by comparing the coarse grid CFD predictions with the grid-independent CFD solutions as well as experimental data obtained from literature. The study shows that a uniform coarse grid can be applied, along with a constant turbulence viscosity model, to reasonably predict general airflow patterns in typical indoor environments. Although such predictions may not be as precise as fine-grid CFDs with well validated complex turbulence models, the accuracy is acceptable for indoor environment study, especially at an early stage of a project. The computing speed is about 100 times faster than a fine-grid CFD, which makes it possible to simulate a complicated 3-dimensional building in real-time (or near real-time) with personal computer.     

纤维格栅对新/旧水泥混凝土黏结性能的影响

为了研究纤维格栅类型、旧水泥混凝土与纤维格栅表面处理状况、粗集料最大粒径对新/旧水泥混凝土黏结劈拉强度的影响,对10组150mm×150mm×150mm的新/旧水泥混凝土黏结立方体试块进行劈拉试验.分析了试件的劈拉破坏过程,探讨了纤维格栅与新/旧水泥混凝土的黏结机理.结果表明:采用网格尺寸为5mm的玄武岩纤维格栅时新/旧水泥混凝土的黏结劈拉强度最大,旧水泥混凝土与纤维格栅表面处理状况对新/旧水泥混凝土黏结劈拉强度有较大的影响,而粗集料最大粒径对新/旧水泥混凝土黏结劈拉强度影响较小.     

浅析电网规划设计的关键问题与技术

电网规划设计决定电力基础设施的建设水平,也影响经济的发展,因此,本文对电网规划设计的几个关键问题--负荷预测、电网的网架分析与运行、电网的规划评价等方面进行了分析和研究,提出相应的解决方式。     

Automated design of prefabricated building

The paper describes a knowledge-based system for the detailed design of prefabricated building. The system employs a comprehensive approach which integrates different design aspects, architectural, structural and technological. The system receives, as an input, a preliminary architectural design of the building to be erected, adjusts it to a modular grid, indicates the location of structured supports, breaks down the floors and walls into elements to be prefabricated and finally produces detailed drawings of the elements and their cost estimate. The premise of the system, its operation and the structure of its knowledge are described.     

大跨度复合预应力焊接球网架结构施工技术

在天津市第一中学学生活动中心工程中,采用大跨度预应力焊接球网架,施工中抓住各关键点：网架定位、冬期施工温度对材料的影响、可靠的操作平台、网架结构的变形控制、网架拼装焊接技术、预应力张拉、网架结构与主体结构连接等制定质量控制措施。施工后,对网架变形进行观测及分析,测量结果满足设计要求。     

一种计算变电站接地网电阻的简化方法

提出了一种简单而精确的接地电阻的计算方法。这种方法是以数值分析和镜像法的理论为基础。利用导体的电阻与其电容的对偶性,通过计算导体间的电容来得到接地网的接地电阻,该方法中的计算参数与变电站接地网的设计有关,如接地网埋设深度,接地网规模,网格数量,接地体直径等。为了检验该方法,将通过该方法所得的结果与文献中的六种不同的公式和方法所得的结果进行了比较。发现由该公式的计算得到的结果与通过计算机得到的结果最接近,从而证明该方法的可靠性。     

柱面网壳结构体系性能分析

本以马家军室内田径训练馆屋面网壳设计为例,分析了柱面网壳的受力规律及其与下部支承结构刚度的关系,结果表明柱面网壳结构对边界条件非常敏感,提出网壳包络设计思想,得出了一些有益的结论和建议 。     

A bi-level design and operation optimization process applied to an energy centre

This paper presents the methods and results of a bi-level optimization process used to select and size the components of an energy centre as well as to determine their optimal operation. The optimization process used a single-objective optimization of operational control nested within a two-objective optimization of design parameters that minimized capital costs and carbon emissions. Different cases were examined in which the ‘credit’ assigned for the export of excess electricity to the grid was varied. Results are presented including the overall trade-off front, trends amongst design variables, operational schedules for a particular solution, and aggregated parameters like total energy supplied by each device. Constraints on roof area were critical at the design-level, and complex interactions between demand and supply were identified at the operational level. Comparison of the two cases highlights the impact of the export of excess power to the grid.