4BE3 U6 C4 Obj 2 EMH

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Questions and Answers

EASY What is the main method of reducing deposition of solids?

Using sequestering agents and chelates (correct)

Maintaining pH levels above 7

Using chlorine to control biological growth

Adding sulfuric acid to increase pH levels

Why is it important to maintain pH levels between 6.5 and 7?

To increase the effectiveness of chlorine

To promote the deposition of solids

To control biological growth

To keep solids in suspension (correct)

What is the purpose of adding sulfuric acid to water treatment?

To reduce pH levels (correct)

To increase pH levels

To add nutrients to the water

To control biological growth

What are polymeric organics and organic phosphorus compounds used for?

To keep scale-forming salts in solution at high concentration levels Signup and view all the answers

What can happen if chemicals are not maintained in the cooling water?

Severe scaling can occur rapidly Signup and view all the answers

Why is continuous and uniform feed necessary in cooling water systems?

To prevent heavy scale formation Signup and view all the answers

What is another method of preventing calcium scale formation in cooling water systems?

Removing calcium hardness from the water with a softening process Signup and view all the answers

Why is balancing cooling towers with complementary corrosion and biological controls important?

To prevent corrosion and biological growth Signup and view all the answers

What is the purpose of using an ion exchange softener in cooling tower water treatment?

To soften the water by removing calcium and magnesium ions Signup and view all the answers

What is the function of crystal modification chemicals in cooling tower water treatment?

To promote the formation of soft sludge Signup and view all the answers

What is cycling control in cooling tower operation?

The maintenance of the appropriate ratio of dissolved solids in the circulating water Signup and view all the answers

What is the purpose of blowdown in cooling tower operation?

To control the concentration of dissolved solids in the circulating water Signup and view all the answers

What is the purpose of using sacrificial anodes in cooling tower corrosion control?

To direct corrosion to sites where it can be tolerated or accepted Signup and view all the answers

What is the benefit of using corrosion resistant materials in cooling tower construction?

To reduce the risk of corrosion Signup and view all the answers

What is the result of operating a cooling tower at higher cycles of concentration?

The risk of deposition in the water system increases Signup and view all the answers

What is the purpose of conductivity-based blowdown in cooling tower operation?

To control the conductivity of the circulating water Signup and view all the answers

What is the benefit of using cold-lime softening in cooling tower water treatment?

To remove calcium carbonate from the water Signup and view all the answers

What is the typical range of cycles of concentration in cooling tower operation?

3-6 Signup and view all the answers

What is the primary purpose of using chemical inhibitors in cooling water?

To form protective layers on metal surfaces Signup and view all the answers

Which type of inhibitor coats the anodic surfaces of a system?

Anodic inhibitors Signup and view all the answers

What is a consequence of incomplete coating of anodic surfaces with anodic inhibitors?

Corrosion effects are worsened Signup and view all the answers

Which of the following is an example of a general inhibitor?

Soluble oils Signup and view all the answers

Why are chromates no longer used in systems from which water can escape?

They cause unacceptable environmental damage Signup and view all the answers

What is the purpose of screens and filters in cooling water systems?

To prevent plugging and erosion Signup and view all the answers

What is the consequence of having too slow a flow rate in a cooling water system?

Deposition occurs Signup and view all the answers

How do heavy metals operate in chemical methods to prevent biological fouling?

They penetrate the cell wall and destroy protein groups Signup and view all the answers

What is a precaution that operators should take when working with biocides?

Wearing protective clothing Signup and view all the answers

Why do some biocides tend to increase the corrosive nature of the cooling water?

They produce by-products that are corrosive Signup and view all the answers

What is the recommended volume of biocide for standard cooling tower systems?

60 litres/tonne Signup and view all the answers

Why is shock feeding of biocides used in cooling systems?

To create a temporary high concentration of biocide Signup and view all the answers

What is the purpose of adding dispersants during biocide slug feedings?

To prevent fouling of the cooling system Signup and view all the answers

Which of the following woods has a natural resistance to biological attack?

Redwood Signup and view all the answers

What is used to treat water and prevent wood deterioration?

Biocides Signup and view all the answers

MEDIUM What is the purpose of limiting the use of nails, screws, or iron hardware in wood systems?

To prevent deterioration of the wood in their vicinity Signup and view all the answers

What is the recommended volume of biocide for evaporative condenser systems?

8 litres/tonne Signup and view all the answers

What is the purpose of adding dispersants during biocide slug feedings?

To hold dead microbiological growth in suspension Signup and view all the answers

Why is shock feeding of biocides used in cooling systems?

To create a temporary high concentration of biocide Signup and view all the answers

What is the purpose of adding lime in the cold-lime softening method?

To precipitate calcium carbonate out of the solution Signup and view all the answers

What is used to treat wood and prevent deterioration?

Wood preservatives Signup and view all the answers

Why is it important to alternate biocides once a month?

To prevent organisms from developing immunity to the biocide Signup and view all the answers

What is the function of crystal modification chemicals in cooling tower water treatment?

To promote the formation of soft sludge Signup and view all the answers

Which type of wood has a natural resistance to biological attack?

Redwood Signup and view all the answers

What is the benefit of operating a cooling tower at higher cycles of concentration?

It minimizes make-up water consumption, sewage disposal, and the related water and sewer charges Signup and view all the answers

What is the purpose of blowdown in cooling tower operation?

To remove excess dissolved solids from the cooling system Signup and view all the answers

What is the typical range of cycles of concentration in cooling tower operation?

Between 3 and 6 Signup and view all the answers

What is the purpose of make-up proportional blowdown?

To maintain a proportional ratio of dissolved solids in the make-up water and cooling water Signup and view all the answers

What happens to the conductivity of the water when calcium carbonate forms?

It decreases Signup and view all the answers

What is the purpose of using corrosion resistant materials in cooling tower construction?

To reduce corrosion in the cooling system Signup and view all the answers

What is the benefit of using sacrificial anodes in cooling tower corrosion control?

It directs corrosion to sites where it can be tolerated or accepted Signup and view all the answers

What is the purpose of conductivity-based blowdown?

To trigger blowdown when a predetermined conductivity value is reached Signup and view all the answers

What is the primary function of sequestering agents and chelates in water treatment?

To reduce the deposition of solids and keep them in suspension Signup and view all the answers

Why is it important to maintain a low pH level in cooling water systems?

To prevent the formation of calcium scale Signup and view all the answers

What is the purpose of adding specialty chemicals to cooling water systems?

To keep scale-forming salts in solution at high concentration levels Signup and view all the answers

Why is it important to balance cooling towers with complementary corrosion and biological controls?

To prevent severe scaling and biological growth Signup and view all the answers

What is the consequence of not maintaining specialty chemicals in cooling water systems?

Severe scaling can occur rapidly Signup and view all the answers

What is the purpose of blowdown in cooling water systems?

To remove solids that have deposited from the water Signup and view all the answers

What is the benefit of using polymeric organics and organic phosphorus compounds in cooling water systems?

They can keep scale-forming salts in solution at high concentration levels Signup and view all the answers

Why is it necessary to follow site-specific water treatment procedures and guidelines?

Because each plant has custom-tailored water treatment needs Signup and view all the answers

What is the primary purpose of using chemical inhibitors in cooling water systems?

To form a protective film on the metal surfaces Signup and view all the answers

Which type of inhibitor is zinc?

Cathodic inhibitor Signup and view all the answers

What is a consequence of using chromates in cooling water systems?

It causes unacceptable environmental damage when released Signup and view all the answers

What is the purpose of screens and filters in cooling water systems?

To prevent plugging and erosion of equipment Signup and view all the answers

What is the effect of having too slow a flow rate in a cooling water system?

It increases deposition of solids Signup and view all the answers

What is the purpose of chemical methods in preventing biological fouling?

To kill microorganisms Signup and view all the answers

What is the recommended approach when working with biocides?

Use extreme caution and wear protective clothing Signup and view all the answers

Why are polysilicates and molybdates used as alternative inhibitors?

They are more environmentally friendly than traditional inhibitors Signup and view all the answers

What is the consequence of incomplete coating of metal surfaces with cathodic inhibitors?

It increases the corrosion potential, leading to severe pitting Signup and view all the answers

What is the purpose of using triazoles in cooling water systems?

To prevent corrosion of copper Signup and view all the answers

What is a potential consequence of using a single type of biocide continuously in a cooling system?

Development of immunity in microbiological organisms Signup and view all the answers

What is the purpose of treating water with biocides in cooling systems?

To control microbiological growth and prevent biological fouling Signup and view all the answers

Why is it important to alternate biocides once a month in a cooling system?

To prevent the development of immunity in microbiological organisms Signup and view all the answers

HARD What is the recommended volume of biocide for evaporative condenser systems?

8 litres/tonne Signup and view all the answers

What is the purpose of adding dispersants during biocide slug feedings in cooling systems?

To hold dead microbiological growth in suspension until blowdown Signup and view all the answers

Which type of wood has a natural resistance to biological attack?

Redwood Signup and view all the answers

What is the primary purpose of using general inhibitors in cooling water systems?

To cover all regions of a system regardless of whether they are anodic or cathodic Signup and view all the answers

What is a consequence of not achieving sufficient concentration of anodic inhibitors?

The corrosion effects can worsen, concentrating corrosion on a smaller anodic surface Signup and view all the answers

Why are chromates no longer used in systems from which water can escape?

They cause unacceptable environmental damage Signup and view all the answers

What is the function of polysilicates and molybdates in cooling water systems?

To form a thin film on the metal and prevent corrosion Signup and view all the answers

What is the purpose of Y-strainers or equivalent in cooling water systems?

To prevent plugging and erosion of equipment Signup and view all the answers

How do heavy metals operate in chemical methods to prevent biological fouling?

They kill microorganisms by penetrating the cell wall and destroying protein groups Signup and view all the answers

What is a consequence of incomplete coating of metal surfaces with inhibitors?

Severe corrosion can occur at unprotected sites Signup and view all the answers

Why is it important to maintain a sufficient concentration of biocides in cooling water systems?

To kill microorganisms and prevent biological fouling Signup and view all the answers

What is the purpose of screens and filters in cooling water systems?

To prevent plugging and erosion of equipment Signup and view all the answers

What is a precaution that operators should take when working with biocides?

Wear protective clothing, gloves, and eye protection Signup and view all the answers

What is the primary mechanism by which sequestering agents and chelates reduce the deposition of solids?

By keeping the solids in suspension, allowing them to be blown down Signup and view all the answers

What is the effect of high pH levels on the deposition of solids?

It promotes the deposition of solids Signup and view all the answers

What is the purpose of adding sulfuric acid to the water treatment process?

To keep the pH in the lower range (6.5 to 7) Signup and view all the answers

What is the consequence of not maintaining the correct concentration of specialty chemicals in the cooling water?

It will result in severe scaling Signup and view all the answers

What is the purpose of using polymeric organics and organic phosphorus compounds in the water treatment process?

To keep scale-forming salts in solution at high concentration levels Signup and view all the answers

Why is it necessary to balance cooling towers with complementary corrosion and biological controls?

To prevent corrosion of steel and copper Signup and view all the answers

What is another method of preventing the formation of calcium scale in cooling water systems?

By removing calcium hardness from the water with a softening process prior to use Signup and view all the answers

What is the consequence of rapid scaling in cooling water systems?

It will clog the system and reduce its efficiency Signup and view all the answers

What is the primary advantage of using crystal modification chemicals in cooling tower water treatment?

To prevent the formation of hard scale Signup and view all the answers

What is the purpose of cycling control in cooling tower operation?

To maintain the appropriate ratio of dissolved solids in the circulating water Signup and view all the answers

What is the consequence of operating a cooling tower at higher cycles of concentration?

Reduced make-up water consumption Signup and view all the answers

What is the purpose of using cold-lime softening in cooling tower water treatment?

To precipitate calcium carbonate out of the water Signup and view all the answers

What is the consequence of calcium carbonate forming in the cooling water system?

Decreased conductivity of the water Signup and view all the answers

What is the purpose of using make-up proportional blowdown in cooling tower operation?

To allow a proportional blowdown discharge based on the amount of make-up water added Signup and view all the answers

What is the benefit of using corrosion resistant materials in cooling tower construction?

Reduced corrosion rate Signup and view all the answers

What is the purpose of using sacrificial anodes in cooling tower corrosion control?

To direct corrosion to sites where it can be tolerated or accepted Signup and view all the answers

What is the typical range of cycles of concentration in cooling tower operation?

3-6 Signup and view all the answers

What is the purpose of conductivity-based blowdown in cooling tower operation?

To open the blowdown valve when a predetermined conductivity value is reached Signup and view all the answers

Study Notes

Deposition of Solids (Scaling)

Sequestering agents and chelates are used to reduce deposition of solids, keeping them in suspension to be blown down.
Maintaining pH levels is important, with higher pH promoting deposition of solids and lower pH (6.5 to 7) helping keep solids in suspension.
Specialty chemicals, such as polymeric organics (polyaculates) and organic phosphorus compounds, are added to keep scale-forming salts in solution.

Methods to Prevent Calcium Scale Formation

Remove calcium hardness from water with softening process prior to use.
Keep scale-forming salts in solution using crystal modification chemicals.
Precipitate calcium as a removable (soft) sludge rather than as a hard scale.

Cooling Tower Maintenance

Maintain appropriate cycles of concentration to minimize deposition and corrosion.
Use cycle control methods, such as make-up proportional blowdown and conductivity-based blowdown, to keep costs at a minimum.
Balance the need to minimize water consumption and sewage disposal with the risk of deposition and corrosion.

Corrosion Control

Use corrosion-resistant metals and materials, protective coatings, sacrificial anodes, and induced electric currents to direct corrosion to tolerable sites.
Apply protective films using chemical inhibitors, classified into cathodic, anodic, and general inhibitors.

Plugging or Erosion of Equipment

Use screens and filters to prevent plugging and erosion.
Install a Y-strainer upstream of the blowdown valve to prevent plugging.

Biological Fouling

Use mechanical methods, such as trash bars and strainers, and chemical methods, such as biocides, to protect against biological fouling.
Biocides work in concentrations greater than a minimum dosage and maintained for a set amount of time.
Use precautions when working with biocides, such as rubber gloves, protective clothing, and eye protection.

Wood Deterioration

Choose woods that have a natural resistance to biological attack.
Treat with wood preservatives, such as creosote or chromated copper arsenate.
Limit the use of nails, screws, or iron hardware, which accelerate deterioration of wood in their vicinity.

Deposition of Solids (Scaling)

Sequestering agents and chelates are used to reduce deposition of solids, keeping them in suspension to be blown down.
Maintaining pH levels is important, with higher pH promoting deposition of solids and lower pH (6.5 to 7) helping keep solids in suspension.
Specialty chemicals, such as polymeric organics (polyaculates) and organic phosphorus compounds, are added to keep scale-forming salts in solution.

Methods to Prevent Calcium Scale Formation

Remove calcium hardness from water with softening process prior to use.
Keep scale-forming salts in solution using crystal modification chemicals.
Precipitate calcium as a removable (soft) sludge rather than as a hard scale.

Cooling Tower Maintenance

Maintain appropriate cycles of concentration to minimize deposition and corrosion.
Use cycle control methods, such as make-up proportional blowdown and conductivity-based blowdown, to keep costs at a minimum.
Balance the need to minimize water consumption and sewage disposal with the risk of deposition and corrosion.

Corrosion Control

Use corrosion-resistant metals and materials, protective coatings, sacrificial anodes, and induced electric currents to direct corrosion to tolerable sites.
Apply protective films using chemical inhibitors, classified into cathodic, anodic, and general inhibitors.

Plugging or Erosion of Equipment

Use screens and filters to prevent plugging and erosion.
Install a Y-strainer upstream of the blowdown valve to prevent plugging.

Biological Fouling

Use mechanical methods, such as trash bars and strainers, and chemical methods, such as biocides, to protect against biological fouling.
Biocides work in concentrations greater than a minimum dosage and maintained for a set amount of time.
Use precautions when working with biocides, such as rubber gloves, protective clothing, and eye protection.

Wood Deterioration

Choose woods that have a natural resistance to biological attack.
Treat with wood preservatives, such as creosote or chromated copper arsenate.
Limit the use of nails, screws, or iron hardware, which accelerate deterioration of wood in their vicinity.

Deposition of Solids (Scaling)

Sequestering agents and chelates are used to reduce deposition of solids, keeping them in suspension to be blown down.
Maintaining pH levels is important, with higher pH promoting deposition of solids and lower pH (6.5 to 7) helping keep solids in suspension.
Specialty chemicals, such as polymeric organics (polyaculates) and organic phosphorus compounds, are added to keep scale-forming salts in solution.

Methods to Prevent Calcium Scale Formation

Remove calcium hardness from water with softening process prior to use.
Keep scale-forming salts in solution using crystal modification chemicals.
Precipitate calcium as a removable (soft) sludge rather than as a hard scale.

Cooling Tower Maintenance

Maintain appropriate cycles of concentration to minimize deposition and corrosion.
Use cycle control methods, such as make-up proportional blowdown and conductivity-based blowdown, to keep costs at a minimum.
Balance the need to minimize water consumption and sewage disposal with the risk of deposition and corrosion.

Corrosion Control

Use corrosion-resistant metals and materials, protective coatings, sacrificial anodes, and induced electric currents to direct corrosion to tolerable sites.
Apply protective films using chemical inhibitors, classified into cathodic, anodic, and general inhibitors.

Plugging or Erosion of Equipment

Use screens and filters to prevent plugging and erosion.
Install a Y-strainer upstream of the blowdown valve to prevent plugging.

Biological Fouling

Use mechanical methods, such as trash bars and strainers, and chemical methods, such as biocides, to protect against biological fouling.
Biocides work in concentrations greater than a minimum dosage and maintained for a set amount of time.
Use precautions when working with biocides, such as rubber gloves, protective clothing, and eye protection.

Wood Deterioration

Choose woods that have a natural resistance to biological attack.
Treat with wood preservatives, such as creosote or chromated copper arsenate.
Limit the use of nails, screws, or iron hardware, which accelerate deterioration of wood in their vicinity.

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Description

Learn about common water treatment methods and ways to prevent deposition of solids, also known as scaling. Understand the importance of site-specific treatment procedures and guidelines.