ABSTRACT

Boiler treatment chemistry has been shown to be critical in maintaining clean heat transfer surfaces and minimizing corrosion in higher pressure industrial boilers. Monitoring boiler feedwater contamination, especially iron and copper, from condensate leakage and upsets is a critical parameter required to maintain control parameters which promote passivation and clean heat transfer surfaces. Hydrogen analysis has also been shown to detect FAC (Flow Assisted Corrosion) and UDC (Under Deposit Corrosion) subsequently monitor corrective procedures. Hydrogen analysis remains the only dynamic continuous monitoring technique available for corrosion monitoring in feedwater and boiler systems.

INTRODUCTION

Hydrogen analysis has been a useful monitoring technique for the identification and, in many cases, the quantification of in service boiler corrosion. It can be a useful tool for detecting waterside corrosion processes before damage to failure occurs in boiler system components. Since availability and reliability of boiler plants are key components for increasing operational life expectancy, periodic hydrogen analysis can be used for evaluating the water chemistry and the potential impact of the chemical treatment program. This technique, when coupled with oxygen and sodium studies and iron and copper feedwater and boiler blowdown analysis, provides evaluation tools for feedwater, boiler and steam cycle determinations. Also, the copper and iron testing can be used to evaluate corrosion in the condensate system.

Boiler tube damage to failure can occur as a result of internal boiler corrosion. It is frequently caused by the breakdown or inability to form a stable protective magnetite film at the boiler tube metal surface. The protective magnetite film is often referred to as the passive film which grows and forms naturally under normal operating conditions in the boiler, producing magnetite and hydrogen. As a result, the boiler has often been described as a thin passive magnetite film surrounded by a steel frame. The objective of a boiler corrosion protection program is to maintain the passive film intact, thereby protecting the steel frame. If the magnetite film is destroyed or if its formation is interrupted, corrosion of the base metal occurs rapidly.1,2,3,4

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