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Keywords:

  • CaCO3 precipitation kinetics;
  • multicomponent ionic diffusion;
  • scale deposition;
  • simplified models;
  • rigorous analysis

Abstract

The complexity of CaCO3 deposit formation on a flow surface arises from the need to take into account the multicomponent transport of all ionic species involved in the carbonic system. Several semitheoretical and empirical models are available. This article presents a rigorous kinetic model that takes into account the diffusional transport of all species involved in CaCO3 wall deposition under turbulent flow as well as the kinetics of the CaCO3 crystallization reaction. Conditions under which high- and low-pH simplified expressions may be used are evaluated. It is shown that the simplified precipitation rate equations provide results within 10% of the rigorous solution when the high-pH expression is applied for solutions at pH levels above 9.5, and the low-pH expression is applied for solutions at pH levels below 7.6. © 2011 American Institute of Chemical Engineers AIChE J, 2012