Calcium carbonate and barium sulphate scale formation kinetics : a surface scale deposition kinetic model

Scale formation is one of the major flow assurance problems in the water treatment and in the oil and gas sectors. Calcium carbonate (CaCO3) is the most common scale encountered in industry. Barium sulphate (BaSO4) scale is the most difficult to deal with as it is highly insoluble and requires chemical and/or physical treatments. Scale build up results in reduced water flow through pipes and could lead to an entire shutdown of installations leading to important financial losses. Nowadays, the main ways to treat and prevent scale formation are periodic squeeze treatments and/or the continuous injection of scale inhibitors. The use of nitrogen and phosphorous compounds, such as polyphosphino carboxylic acid (PPCA), has already been shown to significantly decrease calcium carbonate scale formation. However, the discharge of such inorganic chemicals into the environment represents a real threat and green inhibitors (such as Polymaleic acid (PMA), Poly-Aspartate (PA) and Carboxymethyl-inulin (CMI) are an altemative. A simultaneous comparison of their inhibition effects on scale precipitation and deposition has been carried out in this study. Several different scale preCipitation prediction models have been developed. However, these models are based on thermodynamics and give, at most, a scale tendency to form. Scale Deposition rate equations or prediction of scale deposition have been largely ignored. Moreover, no attempts have been made to associate precipitation data in the bulk solution with deposition data on a solid surface. If a comparison is made with corrosion prediction where a time-based rate is given (in millimetres per year), then it can be seen that a scale kinetic deposition model would be more useful for the flow assurance and the integrity management. This study present a first attempt for a calcium carbonate and barium sulphate scale deposition kinetic model giving an amount of scale (quantity as a mass or thickness) on a stainless steel surface in function of the saturation index, the temperature, the pressure and flow regimeEThOS - Electronic Theses Online ServiceGBUnited Kingdo