Internal Feedwater Treatment for Boilers
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Questions and Answers

What is the main purpose of an internal water treatment program in boilers?

  • Control the pH and alkalinity levels in the boiler water (correct)
  • Increase the concentration of dissolved and suspended solids in the boiler water
  • Promote foaming within the boiler
  • Eliminate oxygen from the boiler water
  • What pH range is ideal to prevent boiler corrosion?

  • 1-3
  • 9.5-10.5 (correct)
  • 7-8
  • 4-6
  • What is the most effective way of preventing caustic embrittlement in boilers?

  • Using lignins and tannins to prevent embrittlement
  • Limiting the boiler water NaOH concentration (correct)
  • Maintaining high concentrations of sodium hydroxide in the boiler water
  • Adding sodium hydroxide to increase pH levels
  • How can foaming be effectively controlled in a boiler?

    <p>Using anti-foaming agents and continuous surface blowdown</p> Signup and view all the answers

    What is used to combat the corrosion caused by dissolved oxygen in boilers?

    <p>Hydrazine and sodium sulfite</p> Signup and view all the answers

    Why is hydrazine's use decreasing in combating oxygen corrosion in boilers?

    <p>It has been designated as a toxic substance</p> Signup and view all the answers

    What is the disadvantage of using sodium sulfite as an oxygen scavenger in boilers?

    <p>It increases the dissolved solids concentration in the boiler</p> Signup and view all the answers

    What causes caustic gouging in boilers?

    <p>$NaOH$ concentrating under a deposit on high heat transfer areas</p> Signup and view all the answers

    What is the purpose of internal treatment of water in low-capacity, low-pressure heating boilers?

    <p>To prevent the formation of scale, corrosion, and sludge</p> Signup and view all the answers

    What is the primary focus of internal water treatment for low-pressure hot water boilers?

    <p>pH control and corrosion prevention</p> Signup and view all the answers

    Why is internal treatment of water essential even after external treatment in high-pressure boilers?

    <p>To meet the stringent water treatment requirements</p> Signup and view all the answers

    What is the main reason for returning most of the steam condensate to the boiler in low-pressure steam heating boilers?

    <p>To minimize the need for additional water after initial filling</p> Signup and view all the answers

    What happens to the internal water treatment requirements as the make-up water needed for boilers increases?

    <p>They become more extensive</p> Signup and view all the answers

    What is the main reason for using internal treatment as the only method to prevent scale, corrosion, and sludge in low-capacity, low-pressure heating boilers?

    <p>External treatment is not effective for these impurities</p> Signup and view all the answers

    What is the primary purpose of external treatment of water for boiler feedwater?

    <p>To remove most impurities from the water</p> Signup and view all the answers

    In what type of boilers are make-up water requirements usually very low?

    <p>Low-pressure hot water boilers</p> Signup and view all the answers

    What chemical can be used in high-pressure boilers to avoid the formation of sodium sulfate and the subsequent increase in corrosion?

    <p>Hydrazine</p> Signup and view all the answers

    Which chemical is suggested to be handled carefully according to its Safety Data Sheet due to its cancer-causing properties?

    <p>Hydrazine</p> Signup and view all the answers

    What is the purpose of using chelants in a boiler water treatment program?

    <p>To trap metallic ions and make scales more soluble</p> Signup and view all the answers

    What is the purpose of using sodium phosphate in a boiler for scale prevention?

    <p>To precipitate impurities in a different form</p> Signup and view all the answers

    What advantage does diethylhydroxylamine (DEHA) offer over hydrazine?

    <p>Low volatility and low toxicity</p> Signup and view all the answers

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