Study On New Acidition Technique In Circulating Cooling Water System

Corrosion and scale inhibition by phosphonate based inhibitors for medium hardness water is studied through rotary coupon, static and dynamic scale inhibition tests. The effect of several factors such as calcium ion, pH, alkalinity, etc. on corrosion and scale inhibition are investigated. The developing process action mechanism and classification in circulating cooling water are summarized. The mechanism of corrosion inhibitor is discussed in terms of electrochemical inhibition, film formation, adsorption film and scale inhibitor in terms of chelation function, dispersion function and crystal distortion function.For medium hardness water, low calcium rigidity and some limitation such as thermal load and low water quantity of circulating water can lead low cycles of concentration. It shows that increasing pH to restrain corrosion in acidition technique may increase scale trend of inorganic phosphorus and zinc. This paper not only study a new acidition technique raising alkalinity properly to decrease the corrosion rate of steel equipment via optimization, but also evaluate a new prescription in acidition technique by studying the ratio of calcium ion and alkalinity. It is proved that the co-inhibitors show better corrosion and scale inhibition in circulating cooling water of medium calcium rigidity and alkalinity of 200~600mg/L. The dynamic simulation experiment also proves that the standard of GB9050 (the corrosion rate and conglutination rate) can be reached.