Water used in boilers is water which the content of mineral had been released and filtered (demin water) because the mineral content in water can damage the parts of boiler. To eliminate the mineral content in water, can use the flocculation and clarification steps. Flocculation is the process of removal of particles suspended in water either large or colloidal compounds are suspended in water. Content levels of these particles are expressed as turbidity. The flocculation steps are:
- Filtration process
Filtration is the process of filtering large-sized dirt. The filtered impurities are organic compounds, fine particles, color compounds and microorganisms.
Coagulation is done to remove dirt impurities form compounds that are ionic.
Water generated from the process above is called with demineralized water (demin water). But in demin water still contained dissolved gases such as carbon dioxide and oxygen can cause corrosion of pipes and tubes. To eliminate the solution of these gases is performing deaeration process. Deaeration process is performed in the deaerator process on the two stages, namely:
Deaeration process mechanically is done by stripping process with low steam (LS). This can eliminate the solution of oxygen and carbon dioxide by up to 0.007 ppm.
Deaeration processes chemically are carried out by injecting solution of hydrazine (N2H4). The end result of deaeration process is called Boiler Feed Water (BFW) which is then used as feed water to the steam boiler.