Water treatment to de-foul heat exchanger - involves using additives to remove deposits, suspend particles, inhibit corrosion and/or improve filterability

摘要

Treatment of water used as a heat-transfer medium in heat-exchange equipment is effected by adding additives to the water, successively or simultaneously, during the normal operation of the equipment, and opt. filtering the water to remove suspended solids. The additives must each have one or more of the following properties: (a) removal of deposits; (b) suspension of particles resulting from (a); (c) protection of surfaces uncovered by (a) against corrosion; (d) improving the filterability of the water on washable porous media. Additives of type (a) are NaOH, Na3PO4, Na borate and Na benzoate. Additives of type (b) are Na tannates, Na lignosulphonates and polymethacrylates. Additives of type (c) are (i) reducing agents, e.g. Na tannates or hydrazine hydrate, (ii) pH regulators, e.g. NaOH, Na2CO3, Na3PO4, Na benzoate, Na borate, cyclohexylamine and ethanolamines, and/or (iii) film formers, e.g. Na tannates, Na3PO4, Na silicate, NaNO2 and carbazole derivs. Additives of type (d) are Na tannates, Na lignosulphonates, alginates and synthetic polymers.