ABSTRACT
Large watertube boilers provide the evaporative capacity to raise the quantities of superheated steam needed to drive steam turbines generating electricity for general distribution. Fossil fuel boilers can be fired by gas, oil or pulverized coal. They are complex systems designed to maximize thermal efficiency and differ considerably according to the nature of the fuel, power output, steam temperature and local experience. This chapter considers the two aspects of corrosion control: waterside corrosion, including the treatment of boiler water; and fireside corrosion. The treatment and control of boiler water has the following objectives: control of pH, removal of dissolved oxygen, elimination of the precursors of calcareous scale, monitoring for contaminants and use of inhibitors. The fireside of a boiler comprises the combustion chamber, external surfaces of evaporation tubes, and superheating tubes and downstream ancillary equipment including heat exchangers and facilities for dust removal from flue gases.
