Diagnosis of Heat Exchanger Scales in Cooling Water Systems

An experimental database is compiled in order to fingerprint the scales formed over the hot surfaces of heat exchangers, in cooling water systems or other systems with similar chemistry. To collect these data, a dynamic simulating pilot plant was designed with considerable application flexibility among which simultaneous flow of water with different velocity and heat fluxes to three simulating heat exchangers can be mentioned. Changing the water chemistry and using various inhibitors composition known in the art, the nature of scale deposits formed on the heating elements was studied by scanning electron microscopy (SEM) coupled with Energy Dispersive X-ray instrument. The heat flux of the elements ranges from 9.46 × 104 to 1.45 × 105 J/m2.sec, which depending on the velocity of fluid passing through the orifice of pipe, give rise to skin temperatures of 80 °C to 230 °C. The flow velocities used in this study were 0.21 and 0.46 m/sec.  Phosphonates and most popular polymers were studied as scale inhibitors.