108 Questions
EASY What is the main advantage of reusing condensate in a steam system?
Reducing the amount of make-up water required
What is the primary source of impurities in condensate?
Hydraulic oils and lubricants
Why is it necessary to treat condensate?
To prevent impurities from plugging or corroding the condensate return and feedwater systems
What is the primary concern of carbon dioxide in boilers and steam systems?
It can form carbonic acid
What is the main reason why strict environmental licenses may prohibit systems that use a significant percentage of make-up water?
To minimize the environmental impact
What is the primary effect of impurities in condensate on boilers?
They can scale up or corrode the boilers
What is the primary source of oxygen in boilers and steam systems?
Air intrusions from condensate return tanks
What is the primary advantage of treating condensate?
Preventing impurities from plugging or corroding the condensate return and feedwater systems
What is the pH of a carbonic acid solution at atmospheric pressure?
5.8
What is the primary cause of localized grooving in condensate return systems?
Carbonic acid
How can oxygen enter the condensate return system?
All of the above
What is the effect of hardness on boilers?
Decreases the rate of heat transfer
What is the purpose of dealkalization equipment in the external treatment systems?
To reduce the hardness of the feedwater
What is the effect of carbon dioxide corrosion and oxygen corrosion occurring together in a system?
The total combined corrosion rate is significantly higher
What is the purpose of filming amines in condensate return systems?
To create a protective film on metal surfaces
What is the result of improperly functioning deaerators in the feedwater system?
More oxygen in the feedwater
What is the purpose of ensuring that turbine glands are fed with gland steam or water?
To prevent air from entering the condensate system
What is the result of sending condensate with high corrosion by-products to drain?
Reduced corrosion in the system
What type of layer does filming amine form on metal surfaces?
Thin, sticky, oily type
What is the purpose of filming amines in a boiler system?
To protect metal surfaces from corrosion
What does a sodium zeolite softener reduce to zero?
Hardness
Why is it necessary to introduce filming amines gradually into a system?
To prevent rapid deposition of particles
What is the purpose of installing a dealkalizer or demineralizer system?
To reduce the cost and complexity of condensate corrosion control
What is the reaction between neutralizing amines and carbonic acid?
R-NH2 + H2CO3 → R-NH3 + HCO3
What is the purpose of condensate polishers?
To purify condensate
What type of contaminants can foul ion-exchange beads in condensate polishers?
Oil and other process fluids
What is the optimal pH range for condensate maintained by neutralizing amines?
Between 8.8 and 9.2
Why is regular backwashing and regeneration necessary for condensate polishers?
Because their ion exchange and filtration abilities become exhausted
What is the purpose of a P-alkalinity check?
To confirm the condensate pH is greater than 8.3
Why should ammonia not be used as a neutralizing amine in some systems?
Because it attacks copper, zinc, or nickel components
What is the primary function of pre-filters in condensate systems?
To remove oil and other process fluids
What is the purpose of filming amines?
To create protective films on metal surfaces
Why are condensate polishers essential for high-pressure boilers?
Because feedwater purity is critical
How should filming amines be fed into the system?
Directly to the steam lines
What is the effect of overfeeding neutralizing amines?
It increases the system's corrosiveness
What is the purpose of metering pumps in neutralizing amine systems?
To inject amine directly into the steam lines
What is the purpose of a dealkalizer or demineralizer system in a steam system?
To reduce alkalinity in the make-up water
What is the reaction between neutralizing amines and carbonic acid?
R-NH2 + H2CO3 → R-NH3 + HCO3
What is the optimal pH range maintained by neutralizing amines in the condensate?
8.8 to 9.2
What is the purpose of filming amines in a boiler system?
To create a protective film on metal surfaces
Why should ammonia not be used as a neutralizing amine in some systems?
Because it can aggressively attack copper, zinc, or nickel components
What is the effect of overfeeding neutralizing amines?
It increases corrosion rates
What is the purpose of P-alkalinity checks in a condensate return system?
To measure the alkalinity of the condensate
MEDIUM Why are metering pumps used in neutralizing amine systems?
To reduce chemical waste through blowdown or blowoff
What is the purpose of filming amines in condensate return systems?
To create a protective film on metal surfaces
What is the effect of neutralizing amines on carbon dioxide corrosion rates?
They reduce corrosion rates
What is the result of carbon dioxide entering the condensate system?
Localized grooving of metal surfaces
What is the primary benefit of reusing condensate in a steam system?
Reducing the overall cost of plant operations
What is the primary source of oxygen in condensate return systems?
Contact with air
Which of the following is NOT a source of impurities in condensate?
Pure water from the source supply
What is the effect of hardness on boilers?
Increased risk of boiler pressure component failure
What is the primary concern with carbon dioxide in boilers and steam systems?
It reacts with condensate to form carbonic acid
What is the purpose of mechanical inspection and maintenance in combating condensate corrosion?
To minimize the amount of make-up feedwater required
What is the result of combining carbon dioxide corrosion and oxygen corrosion in a system?
A significant increase in corrosion rate
Why is treating condensate necessary?
To prevent impurities from plugging or corroding the system
What is the primary effect of oxygen in boilers and steam systems?
It corrodes the condensate return system
What is the purpose of filming amines in condensate systems?
To form a protective layer on metal surfaces
Why is it necessary to ensure that turbine glands are fed with gland steam or water?
To prevent air from infiltrating the condensate system
What is the primary source of carbon dioxide in boilers and steam systems?
All of the above
What is the effect of improperly functioning deaerators on the feedwater system?
Increased oxygen levels in the condensate
What is the primary concern with hardness in boilers and steam systems?
It causes scaling in boilers
What is the primary benefit of treating condensate for carbon dioxide?
Preventing corrosion and scaling in boilers and steam systems
What is the primary method of preventing condensate line corrosion?
Mechanical inspection and maintenance
What is the result of sending condensate with high corrosion by-products to drain?
Prevention of corrosion by-products from entering the system
What is the primary function of filming amines in condensate return systems?
To form a protective layer on metal surfaces
What is the purpose of introducing filming amines gradually into a system?
To prevent rapid deposition of impurities
What is the purpose of condensate polishers?
To purify the condensate
What is the result of not backwashing and regenerating condensate polishers regularly?
The polishers will become exhausted
What type of contaminants can foul ion-exchange beads in condensate polishers?
Oil or other process fluids
What is the purpose of pre-filters in condensate systems?
To remove oil or other process fluids
Why are condensate polishers essential for high-pressure boilers?
Because feedwater purity is critical
What happens when filming amines are introduced into the system?
They form a protective layer on metal surfaces
What is the primary cause of the increased corrosion rate when both carbon dioxide and oxygen are present in a condensate return system?
The synergistic effect of the two corrosive species.
What is the primary mechanism by which air enters the condensate return system through heat exchangers?
Through vacuum breakers during the off-cycle.
What is the primary effect of hardness on boilers?
Reduced heat transfer efficiency and potential pressure component failure.
What is the primary purpose of ensuring that turbine glands are fed with gland steam or water?
To prevent air from infiltrating the condensate system.
What is the primary benefit of minimizing the amount of make-up feedwater required in a steam system?
Reduced flow of impurities into the system.
What is the primary effect of improperly functioning deaerators in the feedwater system?
Failure to remove dissolved oxygen and carbon dioxide.
What is the primary purpose of neutralizing amines in condensate return systems?
To react with and neutralize carbonic acid.
What is the primary effect of sending condensate with high corrosion by-products to drain?
Prevention of corrosion in the condensate return system.
What is the primary mechanism by which carbon dioxide enters the condensate return system?
Through contact with air in open systems.
What is the primary benefit of using filming amines in condensate return systems?
Formation of a protective layer on metal surfaces.
What is the primary reason why condensate must be treated?
To prevent plugging or corroding the condensate return and feedwater systems
What is the primary source of carbon dioxide in boilers and steam systems?
All of the above
What is the primary effect of carbon dioxide on condensate?
It forms carbonic acid, which reacts with the condensate
What is the primary consequence of not reusing condensate in a steam system?
All of the above
What is the primary reason why air intrusions can enter condensate return tanks?
Because of hydraulic oils and lubricants from mechanical equipment
HARD What is the primary effect of impurities on boilers?
They can scale up or corrode the boilers
What is the primary benefit of treating condensate?
Reducing the overall cost of plant operations
What is the primary reason why strict environmental licenses may prohibit systems that use a significant percentage of make-up water?
Because of the increased environmental impact
What is the primary mechanism by which filming amines protect metal surfaces from corrosion?
By adsorbing onto metal surfaces and forming a thin, sticky layer that prevents corrosion
Why is it necessary to use blends of filming and neutralizing amines in some systems?
To provide a broader range of corrosion protection mechanisms
What is the primary function of condensate polishers in high-pressure boilers?
To remove particulate and suspended matter from the condensate
Why are pre-filters used in some condensate systems?
To remove oil and other process fluids from the condensate
What is the primary advantage of using filming amines in condensate systems?
They form a thin, sticky layer that protects metal surfaces from corrosion
Why is regular backwashing and regeneration necessary for condensate polishers?
To prevent fouling of the ion-exchange resin
What is the primary consequence of introducing filming amines too rapidly into a system?
The rapid deposition of impurities will occur, leading to fouling of the system
What is the primary benefit of using condensate polishers in high-pressure boilers?
They are essential for maintaining the purity of the feedwater
What is the primary purpose of dealkalization equipment in a steam system?
To reduce the alkalinity of the make-up water
What is the effect of neutralizing amines on the corrosion rates of a steam system?
They have no effect on the corrosion rates due to dissolved oxygen
Why is it necessary to test and monitor boiler alkalinity?
To maintain the mass of CO2 in the steam within control limits
What is the primary advantage of using filming amines in a steam system?
They create a protective film on metal surfaces
What is the optimal pH range for condensate maintained by neutralizing amines?
Between 8.8 and 9.2
What is the result of overfeeding neutralizing amines in a steam system?
The system becomes more corrosive due to excessively high pH
What is the purpose of metering pumps in neutralizing amine systems?
To reduce the amount of chemical wasted through continuous blowdown
What is the primary benefit of using sodium zeolite softeners in a steam system?
They reduce the hardness of the make-up water to zero
What is the purpose of a P-alkalinity check in a condensate return system?
To ensure that the condensate pH is above 8.3
Why is it necessary to introduce filming amines gradually into a steam system?
To prevent the system from becoming too corrosive
Study Notes
Steam Systems and Condensate
- A steam system that does not reuse condensate relies on 100% make-up water, which requires more external feedwater treatment, chemical input, heat input, and water input, resulting in greater associated costs and environmental impact.
Treating Condensate
- Condensate should be pure, but it can be contaminated with impurities from various sources, including mechanical equipment, malfunctioning water softeners, air intrusions, and process fluids.
Reasons for Treating Condensate
- Impurities in condensate can plug or corrode the condensate return and feedwater systems.
- Impurities can scale up or corrode boilers.
Impurities in Condensate
- Carbon dioxide (CO2): enters boilers and steam systems through various sources, including alkalinity species in raw water, poorly functioning deaerators, and sodium carbonate introduction.
- Oxygen (O2): enters boilers and steam systems through air intrusions, improperly functioning deaerators, and leaks in heat exchangers.
- Hardness: enters condensate systems through leaking potable water heat exchangers, steam turbine condensers, and open cross-connections with potable water systems.
- Corrosion products: enter condensate systems through corrosion of condensate handling system components.
Corrosion in Condensate Systems
- Carbon dioxide corrosion: causes a general thinning of metal parts in the condensate return system and localized grooving.
- Oxygen corrosion: causes pitting of metal surfaces.
Preventing Condensate Line Corrosion
- Mechanical inspection and maintenance: minimizes the amount of make-up feedwater required, reducing the flow of impurities into the system.
- Dealkalization equipment: reduces hardness to zero, preventing carbonate and bicarbonate formation in the boiler.
- Neutralizing amines: increase condensate pH by neutralizing acid in the condensate system, reducing corrosion.
- Filming amines: create protective films on metal surfaces, protecting against corrosion from dissolved CO2 and O2.
Neutralizing Amines
- Neutralizing amines are effective against carbon dioxide corrosion, but not oxygen corrosion.
- Amines react with carbonic acid to form bicarbonate, which returns to the boiler and decomposes to CO2.
- Typical neutralizing amines used are diethylaminoethanol (DEAE), methoxypropylamine (MOPA), diethanolamine (DEA), monoethanolamine (MEA), morpholine, and cyclohexylamine.
Filming Amines
- Filming amines create protective films on metal surfaces, protecting against corrosion from dissolved CO2 and O2.
- Filming amines should be fed directly to steam lines to reduce chemical loss due to blowdown and blowoff.
Condensate Polishing
- Condensate polishers are mixed bed ion exchangers designed to purify condensate.
- They filter out particulate and suspended matter, and perform ion exchange to remove hardness and chlorides.
- Condensate polishing is essential for high-pressure boilers, where feedwater purity is critical.
Steam Systems and Condensate
- A steam system that does not reuse condensate relies on 100% make-up water, which requires more external feedwater treatment, chemical input, heat input, and water input, resulting in greater associated costs and environmental impact.
Treating Condensate
- Condensate should be pure, but it can be contaminated with impurities from various sources, including mechanical equipment, malfunctioning water softeners, air intrusions, and process fluids.
Reasons for Treating Condensate
- Impurities in condensate can plug or corrode the condensate return and feedwater systems.
- Impurities can scale up or corrode boilers.
Impurities in Condensate
- Carbon dioxide (CO2): enters boilers and steam systems through various sources, including alkalinity species in raw water, poorly functioning deaerators, and sodium carbonate introduction.
- Oxygen (O2): enters boilers and steam systems through air intrusions, improperly functioning deaerators, and leaks in heat exchangers.
- Hardness: enters condensate systems through leaking potable water heat exchangers, steam turbine condensers, and open cross-connections with potable water systems.
- Corrosion products: enter condensate systems through corrosion of condensate handling system components.
Corrosion in Condensate Systems
- Carbon dioxide corrosion: causes a general thinning of metal parts in the condensate return system and localized grooving.
- Oxygen corrosion: causes pitting of metal surfaces.
Preventing Condensate Line Corrosion
- Mechanical inspection and maintenance: minimizes the amount of make-up feedwater required, reducing the flow of impurities into the system.
- Dealkalization equipment: reduces hardness to zero, preventing carbonate and bicarbonate formation in the boiler.
- Neutralizing amines: increase condensate pH by neutralizing acid in the condensate system, reducing corrosion.
- Filming amines: create protective films on metal surfaces, protecting against corrosion from dissolved CO2 and O2.
Neutralizing Amines
- Neutralizing amines are effective against carbon dioxide corrosion, but not oxygen corrosion.
- Amines react with carbonic acid to form bicarbonate, which returns to the boiler and decomposes to CO2.
- Typical neutralizing amines used are diethylaminoethanol (DEAE), methoxypropylamine (MOPA), diethanolamine (DEA), monoethanolamine (MEA), morpholine, and cyclohexylamine.
Filming Amines
- Filming amines create protective films on metal surfaces, protecting against corrosion from dissolved CO2 and O2.
- Filming amines should be fed directly to steam lines to reduce chemical loss due to blowdown and blowoff.
Condensate Polishing
- Condensate polishers are mixed bed ion exchangers designed to purify condensate.
- They filter out particulate and suspended matter, and perform ion exchange to remove hardness and chlorides.
- Condensate polishing is essential for high-pressure boilers, where feedwater purity is critical.
Steam Systems and Condensate
- A steam system that does not reuse condensate relies on 100% make-up water, which requires more external feedwater treatment, chemical input, heat input, and water input, resulting in greater associated costs and environmental impact.
Treating Condensate
- Condensate should be pure, but it can be contaminated with impurities from various sources, including mechanical equipment, malfunctioning water softeners, air intrusions, and process fluids.
Reasons for Treating Condensate
- Impurities in condensate can plug or corrode the condensate return and feedwater systems.
- Impurities can scale up or corrode boilers.
Impurities in Condensate
- Carbon dioxide (CO2): enters boilers and steam systems through various sources, including alkalinity species in raw water, poorly functioning deaerators, and sodium carbonate introduction.
- Oxygen (O2): enters boilers and steam systems through air intrusions, improperly functioning deaerators, and leaks in heat exchangers.
- Hardness: enters condensate systems through leaking potable water heat exchangers, steam turbine condensers, and open cross-connections with potable water systems.
- Corrosion products: enter condensate systems through corrosion of condensate handling system components.
Corrosion in Condensate Systems
- Carbon dioxide corrosion: causes a general thinning of metal parts in the condensate return system and localized grooving.
- Oxygen corrosion: causes pitting of metal surfaces.
Preventing Condensate Line Corrosion
- Mechanical inspection and maintenance: minimizes the amount of make-up feedwater required, reducing the flow of impurities into the system.
- Dealkalization equipment: reduces hardness to zero, preventing carbonate and bicarbonate formation in the boiler.
- Neutralizing amines: increase condensate pH by neutralizing acid in the condensate system, reducing corrosion.
- Filming amines: create protective films on metal surfaces, protecting against corrosion from dissolved CO2 and O2.
Neutralizing Amines
- Neutralizing amines are effective against carbon dioxide corrosion, but not oxygen corrosion.
- Amines react with carbonic acid to form bicarbonate, which returns to the boiler and decomposes to CO2.
- Typical neutralizing amines used are diethylaminoethanol (DEAE), methoxypropylamine (MOPA), diethanolamine (DEA), monoethanolamine (MEA), morpholine, and cyclohexylamine.
Filming Amines
- Filming amines create protective films on metal surfaces, protecting against corrosion from dissolved CO2 and O2.
- Filming amines should be fed directly to steam lines to reduce chemical loss due to blowdown and blowoff.
Condensate Polishing
- Condensate polishers are mixed bed ion exchangers designed to purify condensate.
- They filter out particulate and suspended matter, and perform ion exchange to remove hardness and chlorides.
- Condensate polishing is essential for high-pressure boilers, where feedwater purity is critical.
Learn about the importance of reusing condensate in steam systems and how to treat condensate to maintain purity and efficiency.
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