Abstract
We studied the scale formation and its prevention in brine preheaters at the vacuum pan system salt manufacturing factory, using brine concentrated in flow-down salt field. The principal components of scale were found to be calcium carbonate and calcium sulfate, and the mechanism of scale formation, as follows:
The calcium carbonate scale was formed by break-up of the bicarbonate ion in heating and boiling the brine, and the calcium sulfate scale by decrease in solubility with increasing brine temperature. We found that addition of 5-50ppm of sodium hexametaphosphate was effective for scale prevention, which was verified in a plant test.
