For boiler operators, it is their aim to maintain a high water quality. Why is this important? In the operation of boilers, the quality of boiler water has been a very important factor to consider. When the power plant operating pressures surges up, the corresponding water quality requirements will become stricter. The requirements will get tough as the current units will be operating at supercritical pressures. Continuous changes and improvements in the methods used in maintaining the quality of the water, understanding the mechanisms of corrosion as well as the development of new chemicals have all resulted in an efficient and more economical water regime management.
Why boiler water treatment is is very important? There are typically four major reasons why the water quality is very important. Impurities in the water form different scales.
- Water contains salts which upon evaporation of water will form scales on the surface where heat transfer occurs. Scales have lower heat transfer capacity compared to steel: the coefficient of heat transfer of scales is 1kcal/m against the 15 kcal/m for the steel. The will lead to the overheating and eventually to failure of the boiler tubes. Scale will also reduce the flow area which will correspondingly increase the pressure drop in piping and boiler tubes.
- Dissolved oxygen or low PH in the water will attack steel components. This will eventually cause lowering or pitting the thickness of steel tubes and will lead to the rupture of boiler tubes. Contaminants such as chlorides which are a problem in seawater cooled power facilities also behave in the same manner.
- Flow assisted corrosion will occur in the carbon steel pipes because of a continuous removal of the protective oxide layer during high flows.
- Impurities which are carried in the stream will cause deposits on the turbine blades and will lead to reduced efficiency of the turbine, blade failure as well as high vibrations. The contaminants will also cause erosion of the turbine blades. Silica subjected to higher operating pressure will carry and volatilize over the turbine blades.
Simon from Capital Sheffield will service boilers for you in case of repairs and maintenance.