Mitigation of scaling in heat exchangers by physical water treatment using zinc and tourmaline

This paper presents a study on the mitigation of calcium carbonate scaling in a double-pipe heat exchanger by physical water treatment (PWT) using zinc and tourmaline as catalytic materials. Artificially-hardened water at 300 mgL ^-1 was utilized as the fluid medium to form fouling deposits. The cooling water (i.e., hard water) velocity was varied from 0.3 to 0.8 ms ^-1. The inlet temperatures were maintained at 86 ± 1° C and 22 ± 1° C for hot- and cold-water sides, respectively. The results show that in PWT-treatment case, the fouling resistances are 13-50% lower than those in no-treatment case. The SEM image of the deposit shows a blunt shape crystal structure in case of PWT-treatment, while a pointed crystal structure in case of no-treatment. The calcium content of deposits formed in the cases of PWT-treatment is lower by 17-22% than those of the no-treatment, which corresponds to a thinner fouling in case of PWT-treatment.