Water softener is one of water treatment efforts to make feedwater is suitable for requirement of steam boiler. Water can be called hard if it is tested with soap will be difficult to make foam and water can be called soft if it can porduce foam easily. There are some types of water softener process, can be operated manual or automatic and can be multiple tank or single tank. The most popular type is the zeolite softening process. In this process, magnesium and calcium ion contain in water will be removed and elminate it until there is not hardness.
Water softener process use ion exchange to make hardness is removed and change it into soluble sodium ions easily. This matter should be performed because hardness (magnesium and calcium ions) will be scale while sodium is soluble. So when water is supplied into steam boiler pressure part, scale will not occur and do not disturb heat transfer process. Furthermore, zero hardness will reduce amount of chemical injection needed.
Sodium ions can be taken from salt or sodium chloride (NaCl). Clhorine anion (Cl-) and sodium cation (Na+) will be formed when salt is mixed with water because salt will be dissolved in water, very cheap effort.