The process of removing the dissolved gases from the feed water of the boiler is a very essential process in a steam system. Rapid localized corrosion in boiler tubes is caused by the presence of dissolved oxygen in the feedwater. Low pH levels will be caused by the dissolved carbon dioxide in water and the production of corrosive carbonic acid. Severe acid attack throughout the boiler system is caused by low pH levels in the feedwater. Well dissolved gases and low pH levels in the feedwater can be controlled or removed by adding chemicals, it is a more economical and thermally efficient process of removing these gases mechanically. Deaeration is the name of this mechanical process and this will increase the life of a steam system dramatically.
Several problems related to corrosion are caused by dissolved gases. For example, pitting is produced by oxygen in the water which is particularly severe due to its localized nature. Frequently, carbon dioxide corrosion is encountered in condensate systems and less commonly in water distribution systems. In the presence of oxygen, water containing ammonia readily attacks copper and copper-bearing alloys. This results in corrosion which leads to deposition on boiler heat transfer surfaces and reduces efficiency and reliability. For meeting industrial standards of both oxygen content and the allowed metal oxide levels in feedwater, almost complete oxygen removal is needed. For accomplishing this, an efficient mechanical deaeration supplemented by an effective and properly controlled chemical oxygen scavenger is required. Two scientific principles are used for deaeration. The first principle is based on Henry's law. The law states that gas solubility in a solution decreases as the gas partial pressure above the solution decreases. The second part proves that deaeration is the relationship between gas solubility and temperature. In simpler terms, it can be said that gas solubility rises and approaches saturation temperature. Both of these natural processes are used by a deaerator for removing dissolved carbon dioxide, oxygen, and other non-condensable gases from the boiler feedwater. The feedwater is later sprayed in thin films into a steam atmosphere which allows it to become quickly heated to saturation. Spraying of feedwater in thin films gets the surface area of the liquid in contact with the steam increased that results in the more rapid removal of oxygen and lower gas concentrations. The solubility of all dissolved gases gets reduced by this process and it removes them from the feedwater. The liberated gases are then vented from the deaerator. By keeping these principles in mind, Dutco Tennant LLC supplies a comprehensive range of deaerators.