Internal Feedwater Treatment for Boilers

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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?

Using anti-foaming agents and continuous surface blowdown (A) Signup and view all the answers

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

Hydrazine and sodium sulfite (A) Signup and view all the answers

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

It has been designated as a toxic substance (B) Signup and view all the answers

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

It increases the dissolved solids concentration in the boiler (A) Signup and view all the answers

What causes caustic gouging in boilers?

$NaOH$ concentrating under a deposit on high heat transfer areas (B) Signup and view all the answers

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 (B) Signup and view all the answers

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

pH control and corrosion prevention (B) Signup and view all the answers

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

To meet the stringent water treatment requirements (D) 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?

To minimize the need for additional water after initial filling (C) Signup and view all the answers

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

They become more extensive (D) 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?

External treatment is not effective for these impurities (D) Signup and view all the answers

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

To remove most impurities from the water (B) Signup and view all the answers

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

Low-pressure hot water boilers (D) 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?

Hydrazine (C) 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?

Hydrazine (A) Signup and view all the answers

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

To trap metallic ions and make scales more soluble (A) Signup and view all the answers

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

To precipitate impurities in a different form (D) Signup and view all the answers

What advantage does diethylhydroxylamine (DEHA) offer over hydrazine?

Low volatility and low toxicity (D) Signup and view all the answers