Sizes for Self-Cleaning Pipes in Municipal Water Supply Systems
Sizes for Self-Cleaning Pipes in Municipal Water Supply Systems
复制标题
市政供水系统自洁管道尺寸
DOI：
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
J. Vreeburg
中科院分区：
文献类型：
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作者：
S. Buchberger;M. Blokker;J. Vreeburg
历史上，市政配水系统中管道的最小直径由消防流量要求决定。在北美的大多数情况下，允许的最小管道尺寸是6英寸（150毫米），即使是在为100个或更少的家庭供水的分支存根上。管网的这些外围区域经常流速低、停留时间长、水质差，并有沉淀物积聚。因此，许多自来水公司定期冲洗这些管道以清洁它们。近年来，一些自来水公司（最值得注意的是在荷兰）已经引入了“自清洁”网络的概念，每天几分钟，临界管道速度发生并重新悬浮在低流量期间沉降的颗粒。自清洁网络与典型的环状配电系统截然不同。自清洁网络有一个分支式的安排，下游下降的直径和单向的速度，达到至少0.4米/秒，每天几分钟。使用经验“qN“方法估计自清洁网络中的峰值流量，其中q是通常取为每秒每单位0.083升的分接单位需求，N是附近分接单位的数量。估计峰值流量的问题，因此，所需的管道直径也可以使用泊松矩形脉冲（PRP）模型的基本原则，为居民用水需求进行研究。本文的目的是应用PRP模型的理论结果，以产生可靠性为基础的估计的峰值流量和相应的管道尺寸，以确保临界自清洁速度作为邻域大小的函数。PRP模型的结果进行了比较，对传统的，但保守的qN方法。
Historically, the minimum diameter of a pipe in a municipal water distribution system has been governed by fire flow requirements. In most cases across North America, the minimum allowable pipe size is six inches (150 mm), even on branching stubs that feed 100 or fewer homes. These peripheral regions of the pipe network often experience low velocities, long residence times, poor water quality and accumulation of settled deposits. As a consequence, many water utilities routinely flush these lines in an effort to cleanse them. In recent years, several water utilities (most notably in the Netherlands) have introduced the concept of a “self-cleaning” network where, for several minutes each day, a critical pipe velocity occurs and resuspends particles that settled during the low flow periods. Self-cleaning networks are a radical departure from the typical looped distribution system. Self-cleaning networks have a branch-type arrangement with downstream declining diameters and unidirectional velocities that reach at least 0.4 m/s for several minutes each day. Peak flows in the self-cleaning network are estimated using an empirical “ qN ” method, where q is the tapping unit demand usually taken as 0.083 litre per second per unit and N is the number of tapping units in the neighborhood. The problem of estimating the peak flow and, hence, the required pipe diameter can also be investigated using basic principles from the Poisson Rectangular Pulse (PRP) model for residential water demands. The objective of this paper is to apply theoretical results from the PRP model to generate reliability based estimates of the peak flow and the corresponding pipe size needed to assure a critical self-cleaning velocity as a function of neighborhood size. Results from the PRP model are compared against the conventional but conservative qN method.