Abstract
Mineral scale formation is a problem across many industries and diverse applications. Each application may have specific characteristics that must be considered if a modelling system is to be reasonably accurate. The modelling of cooling water and oil field production chemistry have been studied extensively since the 1970’s and state-of-the-art physical chemistry models developed to simulate them, even under extreme conditions. Membrane systems did not begin to receive the same rigorous treatment as oil and gas production, cooling water, and geothermal power production, until the 1990’s. Much of the software used for membrane systems relies upon simple index calculations on the level of the Langelier Saturation Index, and saturation indices based upon total analytical values.
This paper discusses the practical application of advanced physical chemistry techniques commonly employed in cooling water and oil field chemistry, to application specific modelling of mineral scale formation and control in membrane systems.
The techniques are discussed and applied to:
Predicting scale formation;
Identifying the upper driving force limit for inhibitors and blends;
Developing inhibitor models for minimum effective dosage;
Developing models for preventing failure due to inhibitor solubility; and
Modeling inhibitor synergy and competitive inhibition.
The methods discussed have been validated in field applications.
