industrial boiler illustration; photo by process-heating
Industrial boilers have an inherent problem. As feed water or input water is heated, oxygen and carbon dioxide are released. Both gases have an adverse effect on boiler integrity. Oxygen attaches to the metal components and causes rust through the oxidation process. When dissolved carbon dioxide and water are combined, carbonic acid is created. This acid acts as a corrosive agent when coming in contact with metal. Both gases combined together can severely reduce the life span of a boiler system.
Deaeration is used to minimize the harmful effects of carbon dioxide and oxygen. Through the process, the gases are removed in several ways. In one method, heated water sprayed through a stack of metal trays and allowing the dissolved gases to attach to the trays. They are then scrubbed with steam, allowing the gases to vent through the top of the tank. In another system, steam is sprayed on the top of the feed water, releasing oxygen and carbon dioxide. The steam condenses and becomes deaerated water and falls to the bottom of the tank. The dissolved gases are vented through valves in the top of the deaeration tank.
The process is dependent on movement of water through the deaerator tanks and into the boiler. To transport water, a series of deaerator pumps are used. A pump for moving feed water into the tank is usually required. For infusing the spray nozzles, another pump may be used. In other systems, a pump may be used to draw water from the deaeration tank to the boiler.
Pumps must be constructed of quality materials with anticorrosive properties and have a reasonable rate of flow. For continuously flowing systems, a rate of 330 gallons per minute is considered a good rate of flow. In other systems, the deaeration process might not be needed on a continuous basis. In these systems, a control panel with start and stop control buttons are used to operate the pumps. To ensure efficient use of feed water, pumps can be constructed with recirculation pipes to reuse boiler water.