23 Questions
What is the primary concern for Power Engineers regarding dissolved gases in water?
Pitting and corrosion of the boiler metal
What is the purpose of using deaerators in controlling dissolved oxygen?
To lower the dissolved oxygen level
What effect does dissolved carbon dioxide have on the pH level in a boiler?
It lowers the pH level
What is the relationship between pH value and acidity?
Lower pH indicates higher acidity
How does high pH boiler water affect ferrous boiler metal?
It dissolves any existing protective oxide layer
What is the purpose of adding sodium hydroxide (caustic soda) to boiler water?
To increase the pH level
Why is oxygen a concern in boiler water?
It causes pitting and localized corrosion in the boiler metal
What are the impurities or conditions most often identified as important water quality measures in a boiler system?
Suspended Solids, Dissolved Solids, Dissolved Gases, pH
What can result from impurities in a boiler system?
Reduction in efficiency and potential catastrophic failure
What is the typical problem that can result from carryover of impurities downstream from the boiler?
Negatively affecting the purity of the steam
What will scale formation from salts do inside a boiler?
Cause blockages and reduce heat transfer efficiency
Where are the typical areas of corrosion in a boiler due to impurities?
Hottest areas of the boiler such as the water wall
What will suspended solids do if left untreated in a boiler system?
Deposit on the boiler heat transfer surfaces
What is the general relationship between operating pressure and feedwater purity in a boiler system?
Higher operating pressure requires purer feedwater
Where can sludge from flowing water deposit within a boiler system?
On the boiler heat transfer surfaces
What are the two main categories of methods for treating boiler water?
External and internal treatment
What are examples of suspended solids in the boiler water?
Clay, sand, and silica
Which method is commonly used to reduce the levels of suspended solids in boiler water?
Gravity settling (clarifiers) and pressure filtration
What is the most common dissolved solids of interest in boiler water?
Calcium salts of bicarbonate, sulfate, carbonate, and chloride
What is the main problem caused by hardness in boiler water?
Boiler tube scaling
How can colloidal silica be reduced in boiler water?
Agglomeration techniques such as used in a clarifier
How can sludge be controlled in a boiler?
By blowing down the boiler mud drum
What can sludge and scale buildup lead to in a boiler?
Boiler overheating
Test your knowledge on the impurities that may enter a boiler system and their potential effects, including suspended solids, dissolved solids, dissolved gases, and pH levels.
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