Boiler Water Impurities Quiz

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Questions and Answers

What is the primary concern for Power Engineers regarding dissolved gases in water?

  • Acidic corrosion of the condensate return lines
  • Pitting and corrosion of the boiler metal (correct)
  • Formation of carbonic acid in the condensate lines
  • Rusting of the boiler metal

What is the purpose of using deaerators in controlling dissolved oxygen?

  • To lower the dissolved oxygen level (correct)
  • To inhibit the formation of carbonic acid
  • To reduce the pH level of the water
  • To increase the solubility of oxygen in water

What effect does dissolved carbon dioxide have on the pH level in a boiler?

  • It has no effect on the pH level
  • It causes neutralization of the pH level
  • It raises the pH level
  • It lowers the pH level (correct)

What is the relationship between pH value and acidity?

<p>Lower pH indicates higher acidity (C)</p> Signup and view all the answers

How does high pH boiler water affect ferrous boiler metal?

<p>It dissolves any existing protective oxide layer (D)</p> Signup and view all the answers

What is the purpose of adding sodium hydroxide (caustic soda) to boiler water?

<p>To increase the pH level (D)</p> Signup and view all the answers

Why is oxygen a concern in boiler water?

<p>It causes pitting and localized corrosion in the boiler metal (A)</p> Signup and view all the answers

What are the impurities or conditions most often identified as important water quality measures in a boiler system?

<p>Suspended Solids, Dissolved Solids, Dissolved Gases, pH (A)</p> Signup and view all the answers

What can result from impurities in a boiler system?

<p>Reduction in efficiency and potential catastrophic failure (D)</p> Signup and view all the answers

What is the typical problem that can result from carryover of impurities downstream from the boiler?

<p>Negatively affecting the purity of the steam (D)</p> Signup and view all the answers

What will scale formation from salts do inside a boiler?

<p>Cause blockages and reduce heat transfer efficiency (C)</p> Signup and view all the answers

Where are the typical areas of corrosion in a boiler due to impurities?

<p>Hottest areas of the boiler such as the water wall (D)</p> Signup and view all the answers

What will suspended solids do if left untreated in a boiler system?

<p>Deposit on the boiler heat transfer surfaces (B)</p> Signup and view all the answers

What is the general relationship between operating pressure and feedwater purity in a boiler system?

<p>Higher operating pressure requires purer feedwater (B)</p> Signup and view all the answers

Where can sludge from flowing water deposit within a boiler system?

<p>On the boiler heat transfer surfaces (C)</p> Signup and view all the answers

What are the two main categories of methods for treating boiler water?

<p>External and internal treatment (D)</p> Signup and view all the answers

What are examples of suspended solids in the boiler water?

<p>Clay, sand, and silica (B)</p> Signup and view all the answers

Which method is commonly used to reduce the levels of suspended solids in boiler water?

<p>Gravity settling (clarifiers) and pressure filtration (D)</p> Signup and view all the answers

What is the most common dissolved solids of interest in boiler water?

<p>Calcium salts of bicarbonate, sulfate, carbonate, and chloride (C)</p> Signup and view all the answers

What is the main problem caused by hardness in boiler water?

<p>Boiler tube scaling (C)</p> Signup and view all the answers

How can colloidal silica be reduced in boiler water?

<p>Agglomeration techniques such as used in a clarifier (B)</p> Signup and view all the answers

How can sludge be controlled in a boiler?

<p>By blowing down the boiler mud drum (D)</p> Signup and view all the answers

What can sludge and scale buildup lead to in a boiler?

<p>Boiler overheating (B)</p> Signup and view all the answers

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