ABSTRACT
Scale control is vital for cooling water operations, and evaluation of best-fit scale inhibitors for the application is essential, for the scale treatment. One of the traditional test methods for industrial water scale inhibitor screening is static bottle testing. Recently, in other industries, Kinetic Turbidity Test (KTT) has gained more acceptance for scale inhibitor evaluation. KTT uses an Ultraviolet-Visible (UV-Vis) spectrophotometer to monitor scale formation at various dosages of tested products, as function of reaction time. The technology can provide minimum dosage recommendations for the treatment with selected inhibitors, and give the insight on scale formation kinetics and mechanism, under the effects of different types of scale inhibitors.
Polymer dispersancy in waters with particulates such as iron oxide and clay, is also an important characteristic to evaluate, in systems with high levels of suspended solids or fine particles. Previously(currently), this testing was conducted in bottles where the turbidity of solutions were measured by pipette transfer to a cuvette and turbidity meter, providing one data point at a certain time. Kinetic turbidity testing can continuously and simultaneously monitor and record turbidity changes with time, under the effects of various polymer dispersants and dosages. This capability provides more thorough and objective data, for scale control product evaluation.
This paper presents the approach to evaluate scale control chemistries for industrial applications by KTT, and compares the KTT test data, with bottle test results. The laboratory testing results show that KTT provides a fast and data-driven approach for evaluating performance of scale inhibitors and dispersants.
Scale formation in cooling water systems has many problematic operational effects. For example, scale deposits that build up on heat exchanger tubes, reduce heat transfer and flow velocities inside the condenser tubes of desalination plants. Equipment may be damaged by overheating, which can cause expensive downtime for cleaning or repair, resulting in lost revenue. In addition, scale deposits can accelerate corrosion and lead to equipment failure. Major scales include calcium carbonate, calcium sulfate, calcium phosphate, magnesium silicate, silica and other mineral compounds, etc. Scale control can be achieved by using operational control and chemicals. Chemical usage is one of the most common scale treatments methods.1–10 Different types of scales require different types of scale inhibitor chemistry, at varying dosages. Therefore, laboratory scale inhibitor testing is a powerful approach for screening products and determining effective dosages for the treatment.
