21 Questions
What is the main purpose of an internal water treatment program in boilers?
Control the pH and alkalinity levels in the boiler water
What pH range is ideal to prevent boiler corrosion?
9.5-10.5
What is the most effective way of preventing caustic embrittlement in boilers?
Limiting the boiler water NaOH concentration
How can foaming be effectively controlled in a boiler?
Using anti-foaming agents and continuous surface blowdown
What is used to combat the corrosion caused by dissolved oxygen in boilers?
Hydrazine and sodium sulfite
Why is hydrazine's use decreasing in combating oxygen corrosion in boilers?
It has been designated as a toxic substance
What is the disadvantage of using sodium sulfite as an oxygen scavenger in boilers?
It increases the dissolved solids concentration in the boiler
What causes caustic gouging in boilers?
$NaOH$ concentrating under a deposit on high heat transfer areas
What is the purpose of internal treatment of water in low-capacity, low-pressure heating boilers?
To prevent the formation of scale, corrosion, and sludge
What is the primary focus of internal water treatment for low-pressure hot water boilers?
pH control and corrosion prevention
Why is internal treatment of water essential even after external treatment in high-pressure boilers?
To meet the stringent water treatment requirements
What is the main reason for returning most of the steam condensate to the boiler in low-pressure steam heating boilers?
To minimize the need for additional water after initial filling
What happens to the internal water treatment requirements as the make-up water needed for boilers increases?
They become more extensive
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?
External treatment is not effective for these impurities
What is the primary purpose of external treatment of water for boiler feedwater?
To remove most impurities from the water
In what type of boilers are make-up water requirements usually very low?
Low-pressure hot water boilers
What chemical can be used in high-pressure boilers to avoid the formation of sodium sulfate and the subsequent increase in corrosion?
Hydrazine
Which chemical is suggested to be handled carefully according to its Safety Data Sheet due to its cancer-causing properties?
Hydrazine
What is the purpose of using chelants in a boiler water treatment program?
To trap metallic ions and make scales more soluble
What is the purpose of using sodium phosphate in a boiler for scale prevention?
To precipitate impurities in a different form
What advantage does diethylhydroxylamine (DEHA) offer over hydrazine?
Low volatility and low toxicity
This quiz covers the essential process of internal treatment of boiler feedwater, which involves adding chemicals to further soften, deaerate, and condition the water after it has entered the boiler. It discusses the importance of internal treatment in removing impurities that external treatment may have missed, and its role in preventing boiler failure.
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