Water Distribution Network

Abstract

In a water distribution network having at least one pump for distributing water over the network, the pump is driven by an electric motor and a variable speed device, and there is a device for operating the pump in phases. On starting the pump in a first starting phase the pump speed rises rapidly from zero to a threshold speed between zero and a maximum pump speed, in a second starting phase the threshold speed is maintained, in a third starting phase the pump speed is increased more slowly to a maximum speed, and in a fourth operating phase the maximum speed is maintained. On stopping the pump, in a first stopping phase the pump speed decreases gradually from a maximum speed to an intermediate speed, and in a second stopping phase the pump speed decreases rapidly from the intermediate speed to zero.

Description

FIELD OF THE INVENTION[0001]This invention relates to control of pressure in a water distribution network.BACKGROUND OF THE INVENTION[0002]Water distribution networks supply water from a treatment works to the eventual consumers, domestic or commercial, through pipes of decreasing diameter. The flow of water across the network is controlled by pumps and valves. Pumps are typically provided at pumping stations and operate at varying pressures and flow rates to move water through the different diameter pipes. There are generally two types of pump; transfer pumps which move large volumes of water, and level of service pumps, which operate to keep a given pressure in a part of the network. Each pump delivers water through a non-return valve which opens at a given pressure differential across it and closes at a given flow through it. It is well known that a rapid change in velocity of water in such a network produces a transient surge or pressure spike, which travels as a wave along the ...

AI Technical Summary

Benefits of technology

The patent describes a system for starting a pump without causing damage or excessive pressure spikes. The system uses a programmable logic circuit to control the electric motor and allow for a gradual increase in pump speed. This gradual increase prevents pressure spikes and damage to the pump, while still allowing it to operate at its maximum speed. The system can also be combined with an expansion vessel to further reduce surges and pressure spikes, and can be easily adjusted for different pumps or requirements. Overall, the system ensures the safe and efficient operation of pumps.

Problems solved by technology

For example, when a pump starts, static water from a supply pipe is drawn quickly into the suction side, causing an initial drop in pressure.

This causes an initial pressure increase, causing a pressure wave which dissipates over a period of time as the flow system equilibrium is achieved.

The pressure waves are transient, but travel through the network, causing vibration and leading to damage to pipes and pumps.

It is known to use pressure reduction vessels in the network to dissipate these pressure spikes, but these may not be adequate, as they do not react sufficiently quickly to dissipate the surge or spike fully.

They also are extra components, requiring installation and maintenance.

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