the chloride content down. The boiler operations also include bottom blows in order to get rid of solids. Scale is precipitated impurities out of the water and then forms on heat transfer surfaces. This is a problem because scale does not transfer heat very well and causes the tubes to fail by getting too hot. Corrosion is caused by oxygen in the water. The oxygen causes the metal to oxidize which lowers the melting point of the metal. Foaming and priming is caused when the boiler water does not have the correct amount of chemicals and there are suspended solids in the water which carry over in the dry pipe. The dry pipe is where the steam and water mixture are separated. Boiler feedwater treatment Boiler water treatment is used to control alkalinity, prevent scaling, correct pH, and to control conductivity. The boiler water needs to be alkaline and not acidic, so that it does not ruin the tubes. There can be too much conductivity in the feed water when there are too many dissolved solids. These correct treatments can be controlled by efficient operator and use of treatment chemicals. The main objectives to treat and condition boiler water is to exchange heat without scaling, protect against scaling, and produce high quality steam. The treatment of boiler water can be put into two parts. These are internal treatment and external treatment. (Sendelbach, p. 131) The internal treatment is for boiler feed water and external treatment is for make-up feed water and the condensate part of the system. Internal treatment protects against feed water hardness by preventing precipitating of scale on the boiler tubes. This treatment also protects against concentrations of dissolved and suspended solids in the feed water without priming or foaming. These treatment chemicals also help with the alkalinity of the feed water making it more of a base to help protect against boiler corrosion. The correct alkalinity is protected by adding phosphates. These phosphates precipitate the solids to the bottom of the boiler drum. At the bottom of the boiler drum there is a bottom blow to remove these solids. These chemicals also include anti-scaling agents, oxygen scavengers, and anti-foaming agents. Sludge can also be treated by two approaches. These are by coagulation and dispersion. When there is a high amount of sludge content it is better to coagulate the sludge to form large particles in order to