MARINE ENGINEERING :MEO Exams

The purpose of boiler water treatment is fourfold: 1.To react with any remaining feed water hardness and prevent its precipitation as scale on boiler metal; 2.To condition any suspended matter such as hardness sludge or iron oxide in the boiler and make it non adherent to boiler metal; 3.To provide anti-foam protection to permit a reasonable concentrations of dissolved solids in boiler water without introducing carry-over; 4.To eliminate dissolved gases from water and to provide sufficient alkalinity to prevent boiler corrosion.          i.   Scale Formation and Prevention Typical constituents of scales and deposits in boiler are: Calcium carbonate, Calcium sulphate, Complex silicates of Mg, Fe, Ca and Al, Calcium phosphate, Magnesium hydroxide, Magnesium phosphate, Iron and copper oxides. A build-up of scale leads to reduced boiler efficiency and in water tube boilers can eventually lead to tube failures as o...