Rotork’s innovative CVA electric control valve actuators are enabling the Sydney Water Corporation in Australia to control the pressure in the city’s water supply network with greatly increased response and accuracy.

Water authorities need to control the supply pressure in their potable water pipeline networks throughout the day in response to user demand. Pipeline pressure also needs to be controlled to reduce network water leaks and to mitigate pipe bursts and consequential expensive repairs. To perform this vital function on the Sydney water supply network, Rotork Australia has supplied more than 150 Rotork CVL500 linear control valve actuators with adaptation for fitting to pilot valves.

Typically, spring pressure in a pilot valve is modulated over a short 1 – 4mm stroke; this controls the output of the pilot valve, which in turn controls the pipeline pressure. Network pressure can range from 15 metres to over 90 metres head. The characteristic of the Rotork CVL500 actuator enables very accurate control of the network in increments of 0.4 metres of head pressure. For the Sydney Water network this is an improvement on the previous coarse control resolution of up to 7 metres head, just by changing to the Rotork CVL500 actuator. Using a PID* control loop, the Rotork CVL500 provides repeatable and reliable ongoing pressure control.

The Rotork CVL500 actuator can operate in a flooded pit, as the enclosure is IP68 rated, whilst only low power 24V DC or 240V mains is needed. The CVL500 uses Bluetooth® to enable remote configuration and monitoring from outside the pit or confined space. With the integral manual override control the CVL500 allows operation with or without power by electrical and mechanical engineers as well as site operators.

The Rotork actuators were supplied to NetWorks Alliance, a collaboration formed by Sydney Water to deliver a programme aimed at reducing leaks and main breaks from the city’s 21,000 km water supply network. The Alliance provides integrated design-construction of renewals and other water and sewer works across Sydney Water’s area of operations.

Case Study by Honeywell: Ultrasonic gas leak detection (UGLD) is capable of offering an  enhanced mechanism for detecting pressurised gas leaks in applications where more traditional technologies fail to perform effectively due to high natural ventilation rates or excessive vibration. Detection methods such as point and open path IR absorption, catalytic beads and EC cells are dependent on large localised gas clouds forming in order to detect a gas leak. Such gas clouds form well in enclosed areas however, in exposed or elevated areas subject to strong winds leaking gas dilutes quickly with the leak potentially going undetected for long periods of time.

Ultrasonic noise can be generated in a number of ways that may lead to inappropriate positioning or alarm condition such as; mechanical noise, process generated ultrasound, electrical equipment. The main reason for undertaking a survey is to measure the ultrasound in the operational plant, quite simply because we cannot hear what the detector hears. Where new build installations are considering the use of UGLD’s, assumptions of background sound levels are made based on a wealth of experience from live plant studies.

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White Paper by Magnetrol: Over the years, well defined standards have been established to address the requirements for process sealing between electrical system and process fluids, where a failure could allow migration of fluid into the electrical system. The primary audience for this are the users of the process operators and facilities and installers of electrical system and instrumentation.

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To optimize plant performance and prevent expensive turbine damage, rapid control is critical for industrial power markets covering multiple energy sources. Maintaining turbine efficiency is an even higher priority today because of lower emission requirements and varying fuel sources due to the increase in unconventional natural gas sources, such as shale. Plant gas sources are primarily composed of methane, but typically there are extensive variations in higher hydrocarbons (C2+) as well. In fact, in some cases, over 18 percent variation has been recorded with fluctuations from 10 percent to 16 percent within one minute. Turbines have to be more flexible and need to present the above criteria over a wide range of loads because gas turbine power plants are often used only for peak loads.

Application:

Methane and higher hydrocarbons like ethane and propane behave differently during combustion. The variability of fuel sources can sometimes pose challenges for control and optimization, especially for combined cycle turbines with lower emissions. While a gas chromatograph can provide all the required measurements, the speed of response it provides is sometimes not sufficient for effective control.

The solution can often be a process gas analyzer (PGA) with a specific configuration of optical benches and filters that provide continuous measurement and the rapid response that’s required. In addition, an approximate calorific value (BTU) can be provided as long as the higher hydrocarbons are low in content. If this is not the case, the BTU value will be underestimated but never overestimated. Such values cannot be used for custody transfer but they may be adequate to prevent turbine damage and optimize performance. If the operator knows the variation of C2+ in the fuel sources, then that will substantially minimize the error.

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