Abstract
One of the major causes of fouling in boilers is corrosion in the condensate system caused by the presence of oxygen and/or carbon dioxide, and other changes in water chemistry. These problems are usually solved by treating with chemicals, such as neutralizing amines, filming amines, oxygen scavengers and other corrosion inhibitors. Conventional condensate corrosion monitoring techniques include the measurements of oxygen, iron and copper concentrations, conductivity and pH. These are only indications of the corrosivity of the environment. They do not directly determine the corrosion rate of metals used in the condensate system. Coupon weight loss measurement is widely used to monitor corrosion; however, it is time-consuming and problems can not be corrected in a timely manner.
Corrosion products from the condensate system, such as iron oxides, that are returned to the boiler may form deposits on boiler tubes. These deposits can reduce heat transfer efficiency and increase the risk of tube failure due to overheating. This can also result in reduced boiler efficiency, more frequent boiler cleaning, production losses, and plant shutdowns.
Accurate, reliable and low maintenance instruments for continuous on-line monitoring of corrosion rate and corrosion product transport have long been needed. This work describes the use of an electrochemical linear polarization probe and an optical particle monitor for on-line corrosion rate and corrosion product transport monitoring.
