Boiler Water Treatment Quiz
24 Questions
1 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary role of sodium hexametaphosphate (Calgon) when added to boiler feed water?

  • To produce gaseous byproducts
  • To form insoluble complexes with dissolved minerals
  • To increase the boiling point of water
  • To form soluble complexes that prevent scaling (correct)

Radioactive salts prevent scale formation by emitting energy radiations.

True (A)

What is the gelatinous substance formed by the hydrolysis of sodium aluminate in boiler treatment?

Aluminum hydroxide (Al(OH)3)

The disintegration or decay of boiler material due to chemical or electrochemical reactions is known as __________.

<p>boiler corrosion</p> Signup and view all the answers

Which of the following is NOT a method for preventing boiler corrosion?

<p>Spraying oil into the boiler (A)</p> Signup and view all the answers

Match the following methods with their corresponding description:

<p>Preheating = Removes dissolved gases by increasing temperature Chemical Treatment = Uses additives to eliminate oxygen in water Mechanical Deaeration = Involves vacuum to remove gases from water Electrical Conditioning = Prevents scale formation using electrical discharges</p> Signup and view all the answers

What is one disadvantage of sludge formation in boilers?

<p>Fuel wastage (A)</p> Signup and view all the answers

Dissolved Oxygen (D.O.) in boiler water can contribute to corrosion of the boiler materials.

<p>True (A)</p> Signup and view all the answers

What chemical compound is formed when magnesium chloride reacts with sodium hydroxide?

<p>Magnesium hydroxide (Mg(OH)2)</p> Signup and view all the answers

Scales can be easily removed using simple tools such as a wire brush.

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

What substances are commonly responsible for sludge formation?

<p>MgCO3, MgCl2, CaCl2, MgSO4</p> Signup and view all the answers

_______ formation decreases the efficiency of boilers due to reduced heat transfer.

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

Match the following problems with their characteristics:

<p>Scale = Hard deposits that adhere firmly Sludge = Soft, loose, and slimy precipitate Caustic embrittlement = Weakening of metal due to caustic substances Priming and foaming = Formation of bubbles that disrupt steam production</p> Signup and view all the answers

Which of the following is a prevention method for sludge formation?

<p>Blow-down operations (A)</p> Signup and view all the answers

Increasing the temperature of hard water always increases its solubility.

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

What happens to calcium bicarbonate when heated in low-pressure boilers?

<p>It decomposes to form calcium carbonate, water, and carbon dioxide.</p> Signup and view all the answers

What is the main chemical reaction involved in treating water with calcium carbonate (CaCO3)?

<p>Ca2+ + Na2CO3 → CaCO3 + 2Na+ (D)</p> Signup and view all the answers

Aluminum and iron salts can be considered as contributors to permanent hardness in water.

<p>True (A)</p> Signup and view all the answers

What is the equivalent weight of NaAlO2 based on its molar mass?

<p>The equivalent weight of NaAlO2 is equal to its molar mass.</p> Signup and view all the answers

The lime requirement can be calculated using the formula: 74/100 [____] all in terms of CaCO3 equivalent.

<p>Tem.(Ca+2 + 2xTem.Mg+2 + Per.(Mg+2 + Fe+2 + Al+3) + H+ + CO₂ + HCO3 - NaAlO2)</p> Signup and view all the answers

Match the following components with their description:

<p>Natural Zeolite = Derived from green sand and is non-porous Synthetic Zeolite = More efficient and has a gel structure Zeolite = Hydrates of sodium aluminum orthosilicate Aluminum salts = Contributors to permanent hardness in water</p> Signup and view all the answers

Which of the following statements is true about the soda requirement calculation?

<p>Soda requirement equals 106/100 times the sum of various ion concentrations. (D)</p> Signup and view all the answers

The molecular weight of Ca(OH)2 is considered when calculating lime requirements.

<p>True (A)</p> Signup and view all the answers

When treating water, if OH- and CO3-2 ions are present, it indicates an excess of [Ca(OH)2 + Na2CO3] and ______.

<p>Na2CO3</p> Signup and view all the answers

Flashcards

Lime requirement

The amount of calcium hydroxide (Ca(OH)2) needed to treat water and remove hardness.

Soda requirement

The amount of sodium carbonate (Na2CO3) needed to treat water and remove hardness.

Zeolite process

A water treatment method that uses zeolites to soften hard water by exchanging sodium ions for calcium and magnesium ions.

Natural zeolite

A less efficient type of zeolite that is less widely used due to porous structure.

Signup and view all the flashcards

Synthetic zeolite

A more efficient type of zeolite with a gel structure, commonly used.

Signup and view all the flashcards

Hardness in water

Hardness of water is the water's ability to precipitate soap.

Signup and view all the flashcards

Permanent hardness

Hardness of water caused by dissolved minerals that cannot be removed by boiling, caused by sulfates and chlorides.

Signup and view all the flashcards

Temporary hardness

Hardness of water caused by dissolved bicarbonates, that precipitates upon heating or treatment.

Signup and view all the flashcards

Boiler Corrosion

The breakdown or deterioration of boiler materials due to chemical or electrochemical reactions with its environment.

Signup and view all the flashcards

Corrosion Cause: Dissolved Gases

Dissolved gases like O2, CO2, and H2S in water can cause boiler corrosion.

Signup and view all the flashcards

Oxygen Corrosion

Dissolved oxygen directly reacts with boiler materials at high temperatures creating rust and scale formation

Signup and view all the flashcards

Oxygen Removal (Preheating)

Increasing water temperature lowers oxygen solubility, removing oxygen in water at around 65°C

Signup and view all the flashcards

Chemical Oxygen Removal

Adding chemicals like Na₂SO₃ to remove oxygen, converting it into a salt.

Signup and view all the flashcards

Mechanical Deaeration

Using a system to remove oxygen from water by using spraying water in a heated tower.

Signup and view all the flashcards

Calgon Conditioning

Adding sodium hexametaphosphate to boiler water to form soluble complexes with CaSO₄ , preventing scale formation.

Signup and view all the flashcards

Sodium Aluminate Treatment

Hydrolyzing sodium aluminate to form a gelatinous precipitate that traps impurities for easier removal.

Signup and view all the flashcards

Boiler sludge

A soft, loose, slimy precipitate in a boiler, formed by substances more soluble in hot water than cold.

Signup and view all the flashcards

Sludge formation causes

Occurs when salts like MgCO3, MgCl2, CaCl2, MgSO4 are in the water, especially in colder boiler areas and slower flow zones.

Signup and view all the flashcards

Boiler scale

Hard deposits on boiler surfaces, difficult to remove.

Signup and view all the flashcards

Scale formation causes

Decomposition of calcium bicarbonate, reduced solubility of salts (like CaSO4) at high temps, and hydrolysis of magnesium salts. Also, silicates present in water.

Signup and view all the flashcards

Sludge disadvantages

Poor heat conduction, reduced boiler efficiency, pipes get blocked.

Signup and view all the flashcards

Scale disadvantages

Reduced heat transfer, increased fuel waste, and overheating.

Signup and view all the flashcards

Preventing sludge

Use soft water and regular blow-down operations.

Signup and view all the flashcards

Scale prevention - not mentioned

Not explicitly mentioned; likely involves methods to prevent scale-forming substances from entering the boiler.

Signup and view all the flashcards

Study Notes

Water Softening

  • Objectives: Introduction, Lime Soda Process, Zeolite or Permutit Process, Ion-Exchange or De-Ionization or De-Mineralization Process, Boiler Troubles, Sludge, Scales, Boiler Corrosion, Caustic Embrittlement, Priming and Foaming, Numerical based on Lime Soda Process

Introduction

  • Removing hardness causing salts (Ca²⁺, Mg²⁺, and other heavy metal ions) from water is called water softening.
  • Hard water is unsuitable for domestic and industrial use.
  • Hardness causing salts can be removed through external and internal treatment.

External Treatment

  • Water treatment before entering the boiler.
  • Prevents boiler problems.
  • Methods include lime-soda process and zeolite process.

Internal Treatment

  • Conditioning of water within the boiler.
  • Removes salts not completely removed by external treatment.
  • Methods include carbonate conditioning, phosphate conditioning, calgon conditioning.

Lime Soda Process

  • Adds lime [Ca(OH)₂] and soda [Na₂CO₃] to raw water.
  • Forms insoluble precipitates of calcium carbonate and magnesium hydroxide.
  • Chemical reactions involved in the process.

Zeolite or Permutit Process

  • Zeolite is used in a suitable column.
  • Hard water percolates through the zeolite bed.
  • Exchange process replaces sodium(Na+) ions with calcium (Ca²⁺) and magnesium (Mg²⁺) ions
  • Water is softened.
  • Total dissolved solids increase.

Ion-Exchange or De-Ionization or De-Mineralization Process

  • Exchanging ions in solution held on a porous, insoluble solid.
  • Removes cations and anions, leading to complete deionization.
  • Using ion-exchange resins, which are organic cross-linked insoluble polymers.

Boiler Troubles

  • Sludge: Soft, loose, slimy precipitate. Formed in colder boiler portions. Easily removed.
  • Scales: Hard deposits on boiler surfaces. Difficult to remove. Formed by reactions like decomposition of calcium bicarbonate, decreased solubility of salts, hydrolysis of magnesium salts, and formation of magnesium and calcium silicates.
  • Boiler Corrosion: Disintegration of boiler material by chemical/electrochemical reactions. Caused by dissolved gases (O₂, CO₂, H₂S) and acidic salts.
  • Caustic Embrittlement: Boiler material becoming brittle due to high alkalinity (NaOH).
  • Priming and Foaming: Droplets of water carried along with steam, reducing efficiency. Caused by dissolved/suspended matter, sudden boiling, high velocities of steam generation, improper boiler design, and high water level. Foaming is the formation of bubbles in the boiler from presence of oil/alkalies

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Water Softening Processes PDF

Description

Test your knowledge on boiler water treatment processes and chemical interactions. This quiz covers various aspects of scale formation, corrosion prevention, and the chemicals involved in boiler maintenance. Answer questions about specific substances and their effects on boiler efficiency.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser