An exptl. statistical plan is utilized to solve corrosion problems of a section of an industrial plant for the prodn. of caprolactam, consisting of a multistage flash evaporator entirely constructed in AISI 316L (X2CrNiMo 17 12 2). Preliminary tests show that the nitrates or acidity due to the H2SO4 do not influence the corrosive phenomena and confirmed the pos., though costly, effect of adding hydroxylamine sulfate (SI) in the evaporator feed. An exptl. plan was prepd. to diminish the cost and dosage of SI in the system: the exptl. statistical approach has allowed the authors to minimize the no. of tests required to define the system rapidly and adequately, and to optimize the required amt. of SI. The data processed were obtained in a 2-step exptl. plan that allowed the authors to establish a relationship between the logarithm of crit. corrosion current and the concns. of some evaporator feeding components. In addn., it was possible to clarify certain corrosion effects and to reduce the SI addn. up to 1.4 g/L, thereby optimizing the chem. system and considerably reducing maintenance costs. A plausible explanation of the related effects of some of the feeding components is also proposed.
CORROSION INHIBITION IN AN INDUSTRIAL CRYSTALLIZATION PLANT - OPTIMIZING THE PROCESS WITH A STATISTICAL-METHOD
MORETTI, Giuseppe;TONIOLO, Luigi
1994-01-01
Abstract
An exptl. statistical plan is utilized to solve corrosion problems of a section of an industrial plant for the prodn. of caprolactam, consisting of a multistage flash evaporator entirely constructed in AISI 316L (X2CrNiMo 17 12 2). Preliminary tests show that the nitrates or acidity due to the H2SO4 do not influence the corrosive phenomena and confirmed the pos., though costly, effect of adding hydroxylamine sulfate (SI) in the evaporator feed. An exptl. plan was prepd. to diminish the cost and dosage of SI in the system: the exptl. statistical approach has allowed the authors to minimize the no. of tests required to define the system rapidly and adequately, and to optimize the required amt. of SI. The data processed were obtained in a 2-step exptl. plan that allowed the authors to establish a relationship between the logarithm of crit. corrosion current and the concns. of some evaporator feeding components. In addn., it was possible to clarify certain corrosion effects and to reduce the SI addn. up to 1.4 g/L, thereby optimizing the chem. system and considerably reducing maintenance costs. A plausible explanation of the related effects of some of the feeding components is also proposed.
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