Vaalkop water treatment plant set the trend for technology monitoring and control amongst its peers in the Magalies Water stable when it implemented an Adroit supervisory control and data acquisition system in 2000. Since then, Magalies Water deployed a further two additional Adroit systems at the Temba WTW and Roodeplaat WTW and plans to deploy Adroit systems at Bospoort WTW, Boitekong STW and Rustenburg STW as well.
Mias van der Walt, area manager for the Magalies Water western region says, "The biggest advantage of the scada system is the ability to control the water quality and quantity. This information enables us to improve service levels."
The Asset Improvement Plan (AIP) is a living document that outlines continuous process improvements for the waterworks. Vaalkop use the scada as an enabler to achieve the service level goals set out in AIP. Affordability, value for money, user friendliness, and the fact that it is not too complicated, are the reasons that Mias cites for selecting Adroit over its competitors. "The Adroit system is modular and you do not get unnecessary and expensive bells and whistles," he says.
The Vaalkop scada monitors the production facility where water is treated. It also monitors the expansive water distribution system that runs north-south from Rustenburg to Thabazimbi and east-west between Bethanie and Sun City. The distribution network is also monitored by Adroit software. Flow into, and from, reservoirs is monitored to ensure that there is sufficient water supply delivered to the main consumers.
Adroit is involved from the point where the water is extracted from the dam, monitoring pumps and the dosing of chemicals through the flocculation, sedimentation, flotation and filtration processes to remove all suspended matter.
Chlorine is added at the end to disinfect the water of microbes and similar organisms.
Raw water quality determines how the dosage rates or processes in the plant should be adjusted in order to improve poor water quality. Muddy water for example, would require different chemical treatment to water containing a high percentage of algae. The Adroit scada guards the chemical dosage rates of chemicals and water quality parameters as set out by the plant operator.
All energy requirements, pump temperatures and kW consumed, are monitored by the scada, as are vibration, flow rates and pressure that are relayed to the system from the array of field equipment such as pressure gauges and flowmeters. Water quality is determined by online turbidity, pH and residual chlorine meters.
Audible and onscreen alarming has been implemented to alert plant personnel to maintenance and operation conditions, while an SMS is sent by the Adroit to the production manager in the event of a serious situation.
The scada's trend functionality is used predominantly for faultfinding, particularly equipment malfunction. Changes can be traced back to the cause for process improvement and the correct people can be notified in the event of an alarm. Gradual changes over time can also be tracked using the trend function to alert management to potential problems before they occur.
To further Vaalkop's quest for better service levels, the waterworks has implemented an Opus reporting and analysis program to automatically deliver regular daily, weekly and monthly reports, as well as preconfigured reports on production and non-conformance critical to AIP.
The Adroit system is loaded onto a server with approximately three workstations located on the plant at strategic intervals for monitoring purposes. An Ethernet network connects the units. Vaalkop uses the scada in conjunction with approximately 10 Modicon Programmable Logic Controllers (PLCs) that run the various process units across remote stations of the plant, such as the pumps and filtration systems. These run on Modbus plus protocol with a Modbus plus interface at the server that connects the PLCs to the scada.
For more information contact Megan Davidson, Adroit Technologies, 011 658 8100, [email protected], www.adroit.co.za
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