54 Questions
EASY What is the current trend in cleaning large boilers?
Chemical cleaning
What is the purpose of an alkaline boil out?
To remove oily substances from boiler water
What chemicals are commonly used in an alkaline boil out?
Caustic soda, soda ash, and sodium phosphate
What is the purpose of an inhibitor in acid cleaning?
To prevent or minimize metal attack
What is a precaution when using strong alkaline cleaning solvents?
Avoid using them with non-drainable superheaters
What is a consideration when using an acid cleaning method?
Follow proper technique and safety procedures
What is a step in the process of acid cleaning?
Analyze the deposit to determine the right type of acid to use
Why is chemical cleaning not always suitable for smaller boilers?
It requires complex piping and pumping systems
What is the purpose of isolating the boiler from the steam header during acid cleaning?
To prevent acid from entering the steam header
Why is it necessary to vent the boiler during acid cleaning?
To prevent the explosion of hydrogen gas
What is the primary purpose of using a 5% solution of inhibited hydrochloric acid for boiler cleaning?
To effectively remove scale from the boiler
What is the advantage of using sulfamic acid over hydrochloric acid?
It is easier to handle and less corrosive
What is the benefit of using chelating agents for boiler cleaning?
They are less dangerous to use and remove scale slowly
Why is it necessary to remove brass and bronze parts during acid cleaning?
To prevent corrosion of these parts
What is the purpose of boiling out the boiler with an alkaline solution after acid cleaning?
To remove any remaining acid
What is the benefit of using chelating agents for online cleaning of boilers?
It can remove existing scale without removing the boiler from service
Why is it necessary to use demineralized water for flushing the boiler after acid cleaning?
To remove any remaining acid from the boiler
What is the consequence of overfeeding chelant in boiler cleaning?
It can lead to corrosion of the boiler metal
MEDIUM What is the primary purpose of using an alkaline boil out in boiler cleaning?
To dissolve oil and grease from the waterside of new boilers
What precaution should be taken when using strong alkaline cleaning solvents?
Avoid using them if the boiler has non-drainable superheaters made of austenitic stainless steel
What is the purpose of adding an inhibitor to the acid in acid cleaning?
To prevent or minimize the attack of the acid on the metal
Why is chemical cleaning not always suitable for smaller boilers?
Because it requires complex piping and pumping systems
What is the first step in using an acid cleaning method?
Analyze the deposit to determine the type of acid to use
What is the purpose of following proper technique when using an acid cleaning method?
To ensure safe work procedures are in place
Why is it advisable to perform acid cleaning under the direction of experienced personnel?
To ensure safe work procedures are in place
What is the purpose of using a combination of caustic soda, soda ash, and sodium phosphate in alkaline boil out?
To dissolve oil and grease from the waterside of new boilers
What is the primary purpose of isolating the boiler from the rest of the system during acid cleaning?
To prevent the acid from entering other parts of the system
What is the advantage of using chelating agents for boiler cleaning?
They can be used to clean boilers online
Why is it necessary to vent the boiler during acid cleaning?
To reduce the risk of explosion
What is the purpose of using an inhibitor in acid cleaning?
To reduce the corrosiveness of the acid
What is the benefit of using sulfamic acid over hydrochloric acid?
It is less corrosive and easier to handle
What is the purpose of boiling out the boiler with an alkaline solution after acid cleaning?
To neutralize any remaining acid in the boiler
Why is it necessary to remove brass and bronze parts during acid cleaning?
Because they are affected by the acid
What is the consequence of overfeeding chelant in boiler cleaning?
It can cause the boiler metal to corrode
What is the benefit of using demineralized water for flushing the boiler after acid cleaning?
It does not contain minerals that can deposit on the boiler
Why is chemical cleaning not always suitable for smaller boilers?
Because they have a smaller capacity for acid
HARD What is the primary reason for not using strong alkaline cleaning solvents in boilers with non-drainable superheaters made of austenitic stainless steel?
Because they attack austenitic stainless steels
What is the primary benefit of using an inhibitor in acid cleaning?
It reduces the risk of acid attacking the metal
What is the primary purpose of analyzing the deposit before using an acid cleaning method?
To determine the best type of acid to use
What is the primary reason for using complex piping and pumping systems in chemical cleaning of large boilers?
To ensure that the chemicals are properly distributed
What is the primary advantage of using alkaline boil out in cleaning boilers?
It is gentler on the metal surfaces
What is the primary reason for performing acid cleaning under the direction of experienced personnel?
To ensure that the cleaning process is safe and effective
What is the primary purpose of using a combination of caustic soda, soda ash, and sodium phosphate in alkaline boil out?
To ensure that the chemicals are effective at removing contaminants
What is the primary reason for not using chemical cleaning for smaller boilers?
Because the cost of the equipment is not justified by the size of the boiler
What is the primary purpose of isolating the boiler from the steam header during acid cleaning?
To prevent the acid from flowing back into the steam header
What is the primary advantage of using chelating agents over acid cleaning methods?
They can be used to remove existing scale from a boiler without removing the boiler from service
What is the primary purpose of using an alkaline boil out after acid cleaning?
To neutralize any remaining acid in the boiler
What is the primary consideration when using an acid cleaning method?
The potential corrosive effects of the acid on the boiler materials
What is the primary purpose of using sulfamic acid over hydrochloric acid?
It is less corrosive and does not produce noxious fumes
What is the primary consequence of overfeeding chelant in boiler cleaning?
The boiler metal becomes more susceptible to corrosion
What is the primary purpose of using demineralized water for flushing the boiler after acid cleaning?
To prevent corrosion of the boiler materials
What is the primary reason why chemical cleaning is not always suitable for smaller boilers?
The process of acid cleaning is too complex for smaller boilers
What is the primary purpose of venting the boiler during acid cleaning?
To prevent the buildup of hydrogen gas
What is the primary advantage of using a combination of caustic soda, soda ash, and sodium phosphate in alkaline boil out?
It provides a more thorough cleaning of the boiler than using a single alkaline solution
Study Notes
Chemical Cleaning Methods for Boilers
- Chemical cleaning is the trend for large boilers, requiring the services of a chemical company or consultant and involving complex piping and pumping systems.
- Chemical cleaning is not economically viable for smaller boilers.
Alkaline Boil Out Method
- Alkaline boil out is a method of chemical cleaning that removes oil, grease, and other contaminants from the waterside of new boilers or boilers contaminated during operation.
- The method uses a combination of caustic soda, soda ash, sodium phosphate, and sometimes sodium nitrite and sodium sulfite.
- The chemicals are added to the boiler water, and steam pressure is raised and maintained for approximately 48 hours to dissolve deposits on drum and tube surfaces.
- Strong alkaline solutions should not be used on boilers with non-drainable superheaters made of austenitic stainless steel.
Inhibited Acid Cleaning Method
- Inhibited acid cleaning uses an acid to dissolve scale and an inhibitor to prevent metal corrosion.
- The acid and inhibitor are added to the boiler, and the boiler is isolated from the steam header and other parts.
- The acid solution is circulated through the boiler at a temperature of about 65°C until cleaning is complete.
- The boiler is then drained, flushed, and boiled out with an alkaline solution to neutralize any remaining acid.
Safety Precautions for Acid Cleaning
- The right type of acid must be used, and the deposit must be analyzed first.
- Adequate piping systems, temperature control, and circulation must be installed.
- The boiler must be isolated, and all parts not being cleaned must be isolated or protected.
- Brass and bronze parts must be removed or replaced with steel parts.
- All valves exposed to the acid must be made of steel, and all gauges and meters must be isolated.
Safety and Environmental Considerations
- The boiler room must be adequately ventilated, and personnel handling acids must wear proper safety clothing.
- Spent solvent must be disposed of safely and in accordance with environmental regulations.
- Hydrogen production and fire/explosion risks must be mitigated.
Chelating Agents for Chemical Cleaning
- Chelating agents can be used for chemical cleaning while the boiler remains in operation.
- Chelating agents are less dangerous to use but more expensive than acids.
- Chelating agents can remove existing scale from a boiler without taking it out of service.
- However, chelant overfeeding can lead to corrosion and scale removal too quickly, causing sludge accumulation.
- Complete oxygen removal is mandatory, and chelant feed systems must be designed with non-corrosive materials.
Chemical Cleaning Methods for Boilers
- Chemical cleaning is the trend for large boilers, requiring the services of a chemical company or consultant and involving complex piping and pumping systems.
- Chemical cleaning is not economically viable for smaller boilers.
Alkaline Boil Out Method
- Alkaline boil out is a method of chemical cleaning that removes oil, grease, and other contaminants from the waterside of new boilers or boilers contaminated during operation.
- The method uses a combination of caustic soda, soda ash, sodium phosphate, and sometimes sodium nitrite and sodium sulfite.
- The chemicals are added to the boiler water, and steam pressure is raised and maintained for approximately 48 hours to dissolve deposits on drum and tube surfaces.
- Strong alkaline solutions should not be used on boilers with non-drainable superheaters made of austenitic stainless steel.
Inhibited Acid Cleaning Method
- Inhibited acid cleaning uses an acid to dissolve scale and an inhibitor to prevent metal corrosion.
- The acid and inhibitor are added to the boiler, and the boiler is isolated from the steam header and other parts.
- The acid solution is circulated through the boiler at a temperature of about 65°C until cleaning is complete.
- The boiler is then drained, flushed, and boiled out with an alkaline solution to neutralize any remaining acid.
Safety Precautions for Acid Cleaning
- The right type of acid must be used, and the deposit must be analyzed first.
- Adequate piping systems, temperature control, and circulation must be installed.
- The boiler must be isolated, and all parts not being cleaned must be isolated or protected.
- Brass and bronze parts must be removed or replaced with steel parts.
- All valves exposed to the acid must be made of steel, and all gauges and meters must be isolated.
Safety and Environmental Considerations
- The boiler room must be adequately ventilated, and personnel handling acids must wear proper safety clothing.
- Spent solvent must be disposed of safely and in accordance with environmental regulations.
- Hydrogen production and fire/explosion risks must be mitigated.
Chelating Agents for Chemical Cleaning
- Chelating agents can be used for chemical cleaning while the boiler remains in operation.
- Chelating agents are less dangerous to use but more expensive than acids.
- Chelating agents can remove existing scale from a boiler without taking it out of service.
- However, chelant overfeeding can lead to corrosion and scale removal too quickly, causing sludge accumulation.
- Complete oxygen removal is mandatory, and chelant feed systems must be designed with non-corrosive materials.
Chemical Cleaning Methods for Boilers
- Chemical cleaning is the trend for large boilers, requiring the services of a chemical company or consultant and involving complex piping and pumping systems.
- Chemical cleaning is not economically viable for smaller boilers.
Alkaline Boil Out Method
- Alkaline boil out is a method of chemical cleaning that removes oil, grease, and other contaminants from the waterside of new boilers or boilers contaminated during operation.
- The method uses a combination of caustic soda, soda ash, sodium phosphate, and sometimes sodium nitrite and sodium sulfite.
- The chemicals are added to the boiler water, and steam pressure is raised and maintained for approximately 48 hours to dissolve deposits on drum and tube surfaces.
- Strong alkaline solutions should not be used on boilers with non-drainable superheaters made of austenitic stainless steel.
Inhibited Acid Cleaning Method
- Inhibited acid cleaning uses an acid to dissolve scale and an inhibitor to prevent metal corrosion.
- The acid and inhibitor are added to the boiler, and the boiler is isolated from the steam header and other parts.
- The acid solution is circulated through the boiler at a temperature of about 65°C until cleaning is complete.
- The boiler is then drained, flushed, and boiled out with an alkaline solution to neutralize any remaining acid.
Safety Precautions for Acid Cleaning
- The right type of acid must be used, and the deposit must be analyzed first.
- Adequate piping systems, temperature control, and circulation must be installed.
- The boiler must be isolated, and all parts not being cleaned must be isolated or protected.
- Brass and bronze parts must be removed or replaced with steel parts.
- All valves exposed to the acid must be made of steel, and all gauges and meters must be isolated.
Safety and Environmental Considerations
- The boiler room must be adequately ventilated, and personnel handling acids must wear proper safety clothing.
- Spent solvent must be disposed of safely and in accordance with environmental regulations.
- Hydrogen production and fire/explosion risks must be mitigated.
Chelating Agents for Chemical Cleaning
- Chelating agents can be used for chemical cleaning while the boiler remains in operation.
- Chelating agents are less dangerous to use but more expensive than acids.
- Chelating agents can remove existing scale from a boiler without taking it out of service.
- However, chelant overfeeding can lead to corrosion and scale removal too quickly, causing sludge accumulation.
- Complete oxygen removal is mandatory, and chelant feed systems must be designed with non-corrosive materials.
This quiz covers the methods and techniques used for chemical cleaning of boilers, including the alkaline boil out method and its applications.
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