How does scale adhesion reduce thermal efficiency? [Basic Knowledge]

Does a 1mm scale attachment reduce heat transfer efficiency by about 3%? What is the impact on annual costs?

■What happens to thermal efficiency when scale accumulates? It is said that when 1mm of scale accumulates, the heat transfer efficiency decreases by about 3%. Hardness components such as calcium and magnesium contained in the feed water precipitate due to temperature rise and concentration, adhering to the boiler as scale. Issues with water softeners or the concentration of silica can also be contributing factors. Scale is less conductive to heat compared to metal, thus hindering heat transfer like insulation. ■How much does it affect costs? Assuming the energy cost for boiler operation is 10 million yen per year, operating with 1mm of scale accumulation would result in a simple calculation of +3%, bringing the total to 10.3 million yen, which could lead to over 300,000 yen in waste annually. ■What other risks are there besides thermal efficiency? Areas where scale has accumulated are prone to localized overheating, which could lead to a decrease in the strength of the can body, cracking, or unexpected operational shutdowns. ■How can these risks be prevented? Common measures to prevent scale accumulation include the removal of hardness components using water softeners, water quality management with chemicals, and sludge discharge through blowdown. Please feel free to consult us first.

BoilerWater Treatment Chemicalsboiler