Deposition and Removal Mechanisms During Calcium Sulphate Fouling in Heat Exchangers

摘要

A systematic analysis of calcium sulphate fouling in a heat exchanger is presented in this article. Different deposition and removal mechanisms are studied. The fouling process is reaction controlled and affected by the presence of calcium sulphate particles in the process solution and the increasing mass of deposits forming on the heat transfer surface, as they provide additional nucleation sites for the crystallisation. The concentration of the particles is quite low (10-14 ppm) to have any significant particulate fouling. The deposits are found to be strong and they exhibit little removal. Three different stages and hence three separate rates are considered to define and then model the fouling process right from the start. Satisfactory agreement is found between the experimental results and the results predicted from the fouling model. It is endeavoured to update this model by representing the rate of crystallisation as a function of the nucleation sites. This improved model is capable of including the above-mentioned enhancements in crystallisation fouling.