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INTRODUCTION TO URBAN WATER DISTRIBUTION - CHAPTER 6

MẠNG LƯỚI HOẠT ĐỘNG yêu cầu của người tiêu dùng sẽ không được hài lòng trong một mạng lưới hoạt động kém, ngay cả khi nó đã được thiết kế và xây dựng. Sai sót trong giai đoạn này khuếch đại vấn đề phổ biến và những tác động của họ đã được đề cập trong chương trước: - áp suất hoạt động thấp gây ra cung cấp không đầy đủ, áp lực điều hành cao gây rò rỉ cao trong hệ thống, vận tốc thấp gây giữ nước trong đường ống và hồ chứa nước, thường xuyên thay đổi. | CHAPTER 6 Operation and Maintenance 6.1 NETWORK OPERATION The consumer s requirements will not be satisfied in a poorly operated network even if it has been well designed and constructed. Making errors in this phase amplifies the common problems and their implications that were already mentioned in previous chapters - low operating pressures causing inadequate supply - high operating pressures causing high leakage in the system - low velocities causing long retention of water in pipes and reservoirs - frequent changes of flow direction causing water turbidity. These problems can have a serious impact on public health and coping with them also influences maintenance requirements and the overall exploitation costs. The operation of gravity systems is rather simple and deals with the balance between supply and consumption which can be controlled by operating valves. Pressure limitations in the gravity systems that result from topographic conditions become even bigger in the case of a bad design. A wrongly elevated tank incorrect volume or badly sized pipe diameter will not guarantee optimal supply and errors will have to be corrected by what would otherwise be unnecessary pumping. In pumped systems a more sophisticated operation has to be introduced to meet the demand variations and keep the pressures within an acceptable range. Computer simulations are an essential support in solving problems such as these. As well as pressures and flows network models can process additional results relevant to the optimisation of the operation such as power consumption in pumping stations demand deficit in the system or decay growth of constituents in the network. These models are also able to describe the patterns developed during irregular supply situations. Finally the models can be linked with monitoring devices in the system which enables the whole operation to be conducted from one central place. An example in Figure 6.1 shows a comparison between computer model output and .