Why can surface condensers be classified as deaerators?

Surface condensers can be classified as deaerators primarily because they are equipped with air ejectors or vacuum systems that serve to remove dissolved gases from the condensate. In the operation of a surface condenser, as steam passes through the condenser, it is cooled and condensed back into water. The presence of air or other non-condensable gases can negatively impact the efficiency of the system and may lead to corrosion in the boiler feedwater.

By utilizing air ejectors, these condensers create a low-pressure environment that helps to remove air and other gases that might be present in the condensate. This is particularly important because non-condensable gases can form corrosive conditions in the system and reduce the effectiveness of heat transfer.

In summary, the classification of surface condensers as deaerators is valid due to their specific design features that enable them to effectively remove air and other dissolved gases, thereby improving the quality of the water being returned to the boiler system.