4BE3 U6 C4 Obj 1 EMH
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EASY What is a primary reason for the deposition of solids in cooling towers?

  • The increased concentration of dissolved solids due to evaporation (correct)
  • The breakdown of calcium bicarbonate at high temperatures
  • The reaction of calcium bicarbonate with oxygen
  • The corrosion of condenser surfaces

    • What is the byproduct of the breakdown of calcium bicarbonate in cooling towers?

  • Calcium carbonate (correct)
  • Carbon dioxide
  • Calcium bicarbonate
  • Calcium oxide

    • What is a consequence of scaling in cooling towers?

  • Reduced corrosion risk
  • Increased operating costs and risk of under-deposit corrosion (correct)
  • Increased heat transfer efficiency
  • Improved structural integrity of concrete walls

    • What is a common source of impurities in cooling water?

    <p>Raw make-up water</p> Signup and view all the answers

    Corrosion in cooling systems can lead to what?

    <p>Equipment failure and loss of heat transfer efficiency</p> Signup and view all the answers

    What is biological fouling?

    <p>Growth of microorganisms on surfaces</p> Signup and view all the answers

    What increases the rate of calcium bicarbonate breakdown and scaling?

    <p>Rise in pH and temperature</p> Signup and view all the answers

    What is a consequence of under-deposit corrosion?

    <p>Increased risk of equipment failure</p> Signup and view all the answers

    What is the result of biological attack on cooling tower wood?

    <p>The cellulose deteriorates.</p> Signup and view all the answers

    What is the recommended pH range for cooling tower water?

    <p>6 to 8</p> Signup and view all the answers

    What is the maximum recommended limit of Total Dissolved Solids in cooling tower water?

    <p>&lt; 2500 mg/L</p> Signup and view all the answers

    Why is it important to control the growth of microorganisms in cooling towers?

    <p>To protect the environment and human health</p> Signup and view all the answers

    What is the purpose of the guidelines published by the Canadian Council of Ministers of Environment?

    <p>To provide water quality guidelines for cooling towers</p> Signup and view all the answers

    What is the visible result of the cooling tower operation?

    <p>A large white 'cloud' of water vapour</p> Signup and view all the answers

    What is the primary cause of steel corrosion in cooling towers?

    <p>Dissolved oxygen in the cooling water</p> Signup and view all the answers

    What happens to the rate of corrosion when the concentration of dissolved oxygen in the water increases?

    <p>It increases</p> Signup and view all the answers

    What is the approximate concentration of dissolved oxygen in water at 20°C?

    <p>9.1 ppm</p> Signup and view all the answers

    What is the effect of acidity on corrosion?

    <p>It promotes corrosion</p> Signup and view all the answers

    What is the effect of temperature on corrosion rates?

    <p>Corrosion rates increase with increasing temperature up to 70°C</p> Signup and view all the answers

    What is a common problem in cooling towers due to airborne dust and debris?

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

    What is biological fouling caused by in cooling towers?

    <p>Algae, fungi, and bacteria growth</p> Signup and view all the answers

    What can biofilms do in cooling towers?

    <p>Reduce flow rates in tubes and channels</p> Signup and view all the answers

    What is a critical biological growth that can appear in cooling towers?

    <p>Legionella bacteria</p> Signup and view all the answers

    What causes wood deterioration in cooling towers?

    <p>Biological and chemical attack</p> Signup and view all the answers

    MEDIUM What is the primary source of carbon for microorganism growth in cooling towers?

    <p>Cellulose deterioration</p> Signup and view all the answers

    What is the recommended limit for manganese in cooling tower water?

    <p>&lt; 0.5 mg/L</p> Signup and view all the answers

    What is the purpose of keeping the pH of cooling tower water between 6 and 8?

    <p>To minimize corrosion</p> Signup and view all the answers

    What is the consequence of not controlling microorganism growth in cooling towers?

    <p>Increased corrosion rates</p> Signup and view all the answers

    What is the maximum recommended limit for total iron in cooling tower water?

    <p>&lt; 0.5 mg/L</p> Signup and view all the answers

    What is the visible result of the cooling tower operation?

    <p>A large cloud of water vapor</p> Signup and view all the answers

    What is the primary reaction that occurs between steel and oxygen in cooling towers?

    <p>Rust formation through electrochemical reaction</p> Signup and view all the answers

    At what temperature does the concentration of dissolved oxygen in water decrease significantly?

    <p>30°C</p> Signup and view all the answers

    What is the effect of a neutral pH of 7.1 on steel corrosion?

    <p>It increases the corrosion rate</p> Signup and view all the answers

    What is the primary source of plugging in cooling towers?

    <p>Airborne dust and debris</p> Signup and view all the answers

    What is the effect of biofilms on heat exchanger efficiency?

    <p>It decreases the efficiency</p> Signup and view all the answers

    What is the primary mode of transmission of Legionella?

    <p>Inhalation of contaminated water droplets</p> Signup and view all the answers

    What is the primary component of wood that gives it strength?

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

    What is the primary agent of delignification in wood?

    <p>All of the above</p> Signup and view all the answers

    What is the effect of temperature on corrosion rates above 70°C?

    <p>It has relatively little effect on the corrosion rate</p> Signup and view all the answers

    What is the primary reason why Legionella is a significant concern in cooling towers?

    <p>There is no vaccine for it</p> Signup and view all the answers

    Why is scaling less severe in cooling towers compared to boilers?

    <p>Because the operating temperatures are much lower in cooling towers</p> Signup and view all the answers

    What is the primary source of the impurities in cooling water that leads to deposition of solids?

    <p>Raw make-up water</p> Signup and view all the answers

    What is the consequence of under-deposit corrosion in cooling towers?

    <p>Increased operating costs and plant downtime</p> Signup and view all the answers

    What is the chemical reaction that leads to the deposition of solids in cooling towers?

    <p>Ca(HCO3)2 ⇌ CaCO3 + CO2 + H2O</p> Signup and view all the answers

    What is the effect of an increase in pH and water temperature on the deposition of solids in cooling towers?

    <p>It increases the rate of scaling</p> Signup and view all the answers

    What is the consequence of corrosion in cooling systems?

    <p>Loss of heat transfer efficiency and equipment failure</p> Signup and view all the answers

    What is the primary source of impurities in cooling water that leads to biological fouling?

    <p>Microorganisms in the water</p> Signup and view all the answers

    What is the consequence of plugging or erosion of equipment in cooling towers?

    <p>Increased operating costs and plant downtime</p> Signup and view all the answers

    HARD What is the approximate concentration of dissolved oxygen in water at 30°C?

    <p>7.6 ppm</p> Signup and view all the answers

    Which of the following is NOT a factor that enhances biological fouling in cooling towers?

    <p>Oxygen-poor environment</p> Signup and view all the answers

    What is the primary component of wood that gives it strength?

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

    What is the effect of acidity on corrosion rates in cooling towers?

    <p>Increases corrosion rates</p> Signup and view all the answers

    Which of the following is a consequence of corrosion in cooling systems?

    <p>Equipment failure</p> Signup and view all the answers

    What is the primary mode of transmission of Legionella?

    <p>Inhalation of contaminated mist</p> Signup and view all the answers

    What is the primary agent of delignification in wood?

    <p>Oxidizing agents</p> Signup and view all the answers

    What is the effect of biofilms on heat exchanger efficiency?

    <p>Reduces efficiency</p> Signup and view all the answers

    What is the primary reason why Legionella is a significant concern in cooling towers?

    <p>It can cause serious lung infections</p> Signup and view all the answers

    What is the consequence of plugging or erosion of equipment in cooling towers?

    <p>System failure</p> Signup and view all the answers

    What is the primary reason why the Canadian Council of Ministers of Environment developed water quality guidelines for cooling towers?

    <p>To regulate the environmental impact of cooling towers on human health</p> Signup and view all the answers

    What is the significance of the recommended pH range of 6 to 8 for cooling tower water?

    <p>It reduces the risk of corrosion</p> Signup and view all the answers

    What is the primary consequence of not controlling the growth of microorganisms in cooling towers?

    <p>Biological fouling</p> Signup and view all the answers

    What is the primary role of non-oxidizing biocides in controlling microorganism growth in cooling towers?

    <p>To prevent the growth of microorganisms</p> Signup and view all the answers

    What is the primary source of carbon for the growth of microorganisms in cooling towers?

    <p>Cellulose from wood</p> Signup and view all the answers

    What is the primary reason why the total dissolved solids limit is set at 2500 mg/L in cooling tower water?

    <p>To reduce the deposition of solids</p> Signup and view all the answers

    What is the primary reason why the concentration of dissolved solids increases in cooling towers?

    <p>Water evaporates in the towers, leaving behind dissolved solids</p> Signup and view all the answers

    What is the effect of an increase in both pH and water temperature on the rate of calcium bicarbonate breakdown?

    <p>It increases the rate of calcium bicarbonate breakdown</p> Signup and view all the answers

    What is the primary consequence of corrosion in cooling systems?

    <p>It increases the operating costs and results in more plant downtime</p> Signup and view all the answers

    What is the primary source of impurities in cooling water that leads to plugging or erosion of equipment?

    <p>All of the above</p> Signup and view all the answers

    What is the primary consequence of biological fouling in cooling towers?

    <p>It leads to wood deterioration</p> Signup and view all the answers

    What is the chemical reaction that leads to the deposition of solids in cooling towers?

    <p>Ca(HCO3)2 ⇌ CaCO3(scale deposit) + CO2(gas) release) + H2O</p> Signup and view all the answers

    What is the primary reason why scaling is less severe in cooling towers compared to boilers?

    <p>The operating temperatures are much lower in cooling towers</p> Signup and view all the answers

    What is the primary consequence of under-deposit corrosion in cooling towers?

    <p>It increases the operating costs and results in more plant downtime</p> Signup and view all the answers

    Study Notes

    Cooling Tower Impurities and Their Effects

    • Impurities in cooling tower water can lead to increased operating costs and equipment failure.
    • Sources of impurities include:
      • Avian waste
      • Contact with the atmosphere
      • Raw make-up water

    Deposition of Solids (Scaling)

    • Water evaporation in cooling towers increases the concentration of dissolved solids, leading to deposition of solids (scaling) on condensers and evaporative surfaces.
    • Scaling primarily results from dissolved calcium bicarbonate, which breaks down when heated.
    • Factors influencing scaling include:
      • Concentration of calcium and bicarbonate ions
      • pH of the cooling water
      • Water temperature

    Corrosion

    • Corrosion can cause:
      • Equipment failure
      • Loss of heat transfer efficiency
      • Loss of structural integrity of concrete walls and basins
    • Principal cause of steel corrosion is dissolved oxygen in the cooling water.
    • Factors influencing corrosion include:
      • Concentration of dissolved oxygen
      • Acidity
      • Temperature

    Plugging or Erosion of Equipment

    • Airborne dust and debris, dirt, sand, corrosion products, natural organics, and aluminum phosphates can enter the water and plug up the system.
    • Plugging can lead to increased operating costs and equipment failure.

    Biological Fouling

    • Biological fouling occurs due to growth of algae, fungi, avian waste, and bacteria in recirculating cooling towers.
    • Factors enhancing biological fouling include:
      • Warm water
      • Abundant sunlight
      • Oxygen-rich environment
    • Biological fouling can lead to:
      • Reduced flow rates
      • Corrosion of metals
      • Destruction of wooden portions of the tower

    Legionella and Waterborne Diseases

    • Legionella bacteria can cause serious lung infections and flu-like infections.
    • Legionella growth is enhanced in cooling towers and other human-made systems.
    • Prevention is the only option, as there is no vaccine.

    Wood Deterioration

    • Wooden components in cooling towers are susceptible to biological and chemical attack, leading to deterioration.
    • Chemical attack occurs mainly through delignification.
    • Biological attack occurs through cellulose deterioration.

    Water Quality Guidelines

    • Guidelines for cooling tower water quality include:
      • pH range of 6 to 8
      • Total dissolved solids less than 2500 mg/L
      • Limits for calcium, iron, manganese, copper, aluminum, sulfide, silica, and suspended solids.

    Cooling Tower Impurities and Their Effects

    • Impurities in cooling tower water can lead to increased operating costs and equipment failure.
    • Sources of impurities include:
      • Avian waste
      • Contact with the atmosphere
      • Raw make-up water

    Deposition of Solids (Scaling)

    • Water evaporation in cooling towers increases the concentration of dissolved solids, leading to deposition of solids (scaling) on condensers and evaporative surfaces.
    • Scaling primarily results from dissolved calcium bicarbonate, which breaks down when heated.
    • Factors influencing scaling include:
      • Concentration of calcium and bicarbonate ions
      • pH of the cooling water
      • Water temperature

    Corrosion

    • Corrosion can cause:
      • Equipment failure
      • Loss of heat transfer efficiency
      • Loss of structural integrity of concrete walls and basins
    • Principal cause of steel corrosion is dissolved oxygen in the cooling water.
    • Factors influencing corrosion include:
      • Concentration of dissolved oxygen
      • Acidity
      • Temperature

    Plugging or Erosion of Equipment

    • Airborne dust and debris, dirt, sand, corrosion products, natural organics, and aluminum phosphates can enter the water and plug up the system.
    • Plugging can lead to increased operating costs and equipment failure.

    Biological Fouling

    • Biological fouling occurs due to growth of algae, fungi, avian waste, and bacteria in recirculating cooling towers.
    • Factors enhancing biological fouling include:
      • Warm water
      • Abundant sunlight
      • Oxygen-rich environment
    • Biological fouling can lead to:
      • Reduced flow rates
      • Corrosion of metals
      • Destruction of wooden portions of the tower

    Legionella and Waterborne Diseases

    • Legionella bacteria can cause serious lung infections and flu-like infections.
    • Legionella growth is enhanced in cooling towers and other human-made systems.
    • Prevention is the only option, as there is no vaccine.

    Wood Deterioration

    • Wooden components in cooling towers are susceptible to biological and chemical attack, leading to deterioration.
    • Chemical attack occurs mainly through delignification.
    • Biological attack occurs through cellulose deterioration.

    Water Quality Guidelines

    • Guidelines for cooling tower water quality include:
      • pH range of 6 to 8
      • Total dissolved solids less than 2500 mg/L
      • Limits for calcium, iron, manganese, copper, aluminum, sulfide, silica, and suspended solids.

    Cooling Tower Impurities and Their Effects

    • Impurities in cooling tower water can lead to increased operating costs and equipment failure.
    • Sources of impurities include:
      • Avian waste
      • Contact with the atmosphere
      • Raw make-up water

    Deposition of Solids (Scaling)

    • Water evaporation in cooling towers increases the concentration of dissolved solids, leading to deposition of solids (scaling) on condensers and evaporative surfaces.
    • Scaling primarily results from dissolved calcium bicarbonate, which breaks down when heated.
    • Factors influencing scaling include:
      • Concentration of calcium and bicarbonate ions
      • pH of the cooling water
      • Water temperature

    Corrosion

    • Corrosion can cause:
      • Equipment failure
      • Loss of heat transfer efficiency
      • Loss of structural integrity of concrete walls and basins
    • Principal cause of steel corrosion is dissolved oxygen in the cooling water.
    • Factors influencing corrosion include:
      • Concentration of dissolved oxygen
      • Acidity
      • Temperature

    Plugging or Erosion of Equipment

    • Airborne dust and debris, dirt, sand, corrosion products, natural organics, and aluminum phosphates can enter the water and plug up the system.
    • Plugging can lead to increased operating costs and equipment failure.

    Biological Fouling

    • Biological fouling occurs due to growth of algae, fungi, avian waste, and bacteria in recirculating cooling towers.
    • Factors enhancing biological fouling include:
      • Warm water
      • Abundant sunlight
      • Oxygen-rich environment
    • Biological fouling can lead to:
      • Reduced flow rates
      • Corrosion of metals
      • Destruction of wooden portions of the tower

    Legionella and Waterborne Diseases

    • Legionella bacteria can cause serious lung infections and flu-like infections.
    • Legionella growth is enhanced in cooling towers and other human-made systems.
    • Prevention is the only option, as there is no vaccine.

    Wood Deterioration

    • Wooden components in cooling towers are susceptible to biological and chemical attack, leading to deterioration.
    • Chemical attack occurs mainly through delignification.
    • Biological attack occurs through cellulose deterioration.

    Water Quality Guidelines

    • Guidelines for cooling tower water quality include:
      • pH range of 6 to 8
      • Total dissolved solids less than 2500 mg/L
      • Limits for calcium, iron, manganese, copper, aluminum, sulfide, silica, and suspended solids.

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    Description

    This quiz covers the sources of impurities in cooling tower water, including avian waste, atmospheric contact, and raw make-up water, and the resulting problems of scaling, corrosion, and plugging.

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