A possible use of volatile amines on air-cooled fossil-fired boiler/turbine units

Volatile amines have been used to condition boilers in the power industry for over 70 years. More recently they have been successfully used in minimising two-phase FAC (flow-accelerated corrosion) in nuclear power plants. For a variety of reasons, operators of high temperature and pressure fossil-fired boilers have been reluctant to adopt the use of amines. This is possibly because they have found that oxygenated treatment (OT) provides a simple but effective way of conditioning their steam/water circuits and do not see the need to use additional treatment chemicals. For its successful use, OT demands that steam conductivities be maintained at a low level. There is possibly also a concern that use of organic additives could cause these conductivities to rise above the levels advised for OT and the limits set by turbine manufacturers. A growing number of new power stations are now being equipped with air-cooled condensers. One of the most commonly used designs employs a large area of finned carbon steel tubes that has been shown to be prone to corrosive attack. It is known, however, that this attack can be minimised by increasing ammonia levels in the bulk condensate to a pH of about 9.8-10. This paper considers the possibility of using a volatile amine with ammonia to ensure that the pH in the early condensate droplets formed in air-cooled condensers is high enough to suppress any corrosion. (orig.)