At a seawater reverse osmosis (SWRO) desalination plant in Thalaiyadi, Jaffna (Sri Lanka), with a capacity of 24 million litres per day, we developed the control system with Siemens SIMATIC PCS 7 V9.1, with redundant controllers and supervision servers.
- 24 MLDmillion litres of desalinated water per day
- ~3,000signals distributed across the plant
- PCS 7 V9.1redundant controllers and servers
- Remotesystem maintenance from our offices
The challenge
To integrate PCS 7 with a demilitarised zone (DMZ) and with the energy metering equipment, motor control and the rest of the plant systems, with a volume of around 3,000 signals distributed throughout the facility.
What we did
Control programming
- Siemens APL standard blocks
- Custom functions in SCL
- Coordination of pumps, filtration, reverse osmosis, chemical dosing and clean-in-place (CIP)
Integration and operation
- Field signals and plant equipment over PROFINET and Modbus TCP
- Operator screens, alarms, trends and diagnostics
- Integration with the DMZ
Data and reports
- Process Historian for historical storage
- Information Server for automatic report generation (later extension)
Commissioning and remote maintenance
Our work included functional testing and commissioning support. Since then we have maintained the system remotely: we support the plant’s control software and data systems from our offices.