Sinclair Knight Merz has designed an innovative, dynamic, water and salt balance model for the Tarong Power Station in south-east Queensland. The model enables the power station’s water systems to be optimised without compromising on the water quality.
The 1400 MW power station consumes 800 L/s of water to make-up for evaporation losses from the cooling towers and includes boilers that convert 285 L/s of water into steam. The main water supply is from Boondooma Dam; other sources include on-site storage dams and Wivenhoe Dam.
The model, constructed using CADSIM Plus 2000, provides a graphical interface and enables the simulation to be reliable, robust, user-friendly and dynamic. It can perform predictive analyses based on 100 years of weather data via an Excel link.
The model allows specifications to be manipulated while retaining relationships, constraints and conditions. Annual water charges and other operating parameters can be calculated. Further, a range of operating scenarios can be implemented by simple ‘on-off’ switches.
Using the model, an initial assessment of site water, found that by simulating tightly controlled blowdown Total Dissolved Salt (TDS) limits, potential water savings of nearly 5% were possible. Actions were recommended to achieve this control, including the use of additional metering. Other assessment results included finding a water deficit in the Ash Dam and that on-site water harvesting opportunities were limited to small, but valuable, amounts for recycle or reuse. Zero discharge using existing plant and piping was found to be unlikely due to limited sinks for the dissolved solids and the dependency on uncontrollable parameters.
Tarong Energy now has a powerful process design and operations support tool. Tarong have used the model to further investigate water use on-site; to optimise design criteria; to determine the impact and reliability of alternate supplies; and, to highlight environmental risk. They have also found it has resulted in better decisions being made, as the model is especially useful for presenting data to managers. Further, the model’s costing of recovered water has been used in determining the value of new projects. Future work will target achieving zero discharge.
Authors
Lee Foster
Charl Jeannot
Sinclair Knight Merz Pty Ltd.
D.J. Knights
Tarong Energy, Nanango, Qld 4615, AUSTRALIA
V.M. Ashley
Chemical and Process Engineering, School of Engineering, University of Surrey, ENGLAND