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How to manage boilers
Water quality management
Water component
  1. Components dissolved in water include canions of calcium, magnesium, sodium, and potassium, and anions of bicarbonate, sulfur and chloride. Apart from these, there are also silica and iron.
  2. To use as boiler water, it is ideal to use water with less dissolved matters above. In particular, for use as boiler supply water, it is more ideal if there are less hardness components such as calcium and magnesium and lower silica density.
  3. To remove the dissolved components above, insert a certain amount of antiscale.
Harmful influences to boilers from untreated waters
  1. Generates scales in tubes shortening lifetime and deteriorating efficiency
  2. Note:What is scale disorder?

    This phenomenon is when inorganic substances (calcium, magnesium, silica, etc.) mixed with water adheres and hardens on the heater part. Adhering of the scale may result in deteriorated boiler efficiency and overheating damage of the heater part. The hardness of structural steel weakens around 350℃; in particular, as the heater load is high in the water tube structure, a slight scale can cause great disorder due to insulation from the scale.
  3. Scales deteriorate heat conductivity of tubes causing negligent accidents such as tube rupture.
  4. Results in shorter lifetime of boiler and negligence accidents from tube corrosion.
  5. Causes corrosion of the steam tube due to carry over and aging of the machine.
  6. Note: What is carry over disorder?

    Carry over disorder is when foreign substances and moisture dissolved or mixed in the boiler water transits into the steam system with steam, deteriorating steam purity which may increase corrosion of the superheater or other steam annex equipment and deteriorate the product quality.
Measures for water treatment management
  1. Install a water softening apparatus (softener) to completely remove calcium and magnesium.
  2. Silica that cannot be removed from water softening equipment can be discharged by changing into fusible silicate of soda that cannot be scaled using a proper chemical (antiscale).
  3. As floating substances such as soil and dust entering from industrial water or underground water cannot be processed by softener or chemicals, use only water purified by installing a micro filter to discharge water management and raw water.
Water quality and corrosion management
Types of corrosions
  1. Corrosion from pH
  2. Corrosion from dissolved oxygen
  3. Corrosion from chlorides
Cause of corrosion
  1. Corrosion from pH Water can be acidic, neutral or alkaline. This is determined by the pH of water. The acidity of water is expressed as acidic (pH 1-5) << neutral (pH 6-8)<<alkaline (pH 9-14), however most of the time, water is neutral. Corrosion in the boiler can be best avoided if the acidity of water is maintained at pH 11 – 11.8.
  2. Corrosion from dissolved oxygen Oxygen in air is dissolved in water used in boilers, and boiler water that has not removed the dissolved oxygen can generate corrosion by contacting with iron.
  3. Corrosion from chlorides In water, chlorides are dissolved before we notice, which may cause corrosion of boiler tubes.
Measures against corrosion
  1. Corrosion prevention by pH As water is generally neutral, control the injection amount of the complex antiscaler so that the pH becomes 11 – 11.8 into the boiler.
  2. Corrosion prevention by dissolved oxygen Dissolved oxygen can be removed by inserting a complex antiscaler in the water. This is possible as the deoxidant in the complex antiscaler removes dissolved oxygen.
  3. Corrosion prevention by chlorides In order to prevent corrosion from chlorides, perform lower blowing after or during operation of the boiler so that chlorides are not condensed (Once every day based on 8 hours of operation). When an automatic blowing system is applied, boiler operation in the optimized state is possible.