At the end of this module, you will be able to:
- Identify and describe the safety guidelines associated with boiler feedwater chemical additives
- Describe why boiler water treatment is needed
- Identify the two major approaches to treating boiler feedwater
- Identify the reasons that internal chemical additives are used in boilers
- Describe the purpose of each of the following types of boiler water chemical additives: Phosphates, Chelants, Polymers, Oxygen scavengers, Antifoaming agents, Neutralizing amines, and Filming amines
The following key questions are answered in this module:
What is the purpose of chemical additives used in boiler feedwater?
To improve feedwater quality and steam purity, as well as correct other problems caused by impurities. They can increase boiler efficiency; reduce fuel, operating, and maintenance costs; minimize maintenance and downtime; and prevent corrosion and extend equipment lifetime.
What types of impurities might need to be removed from boiler feedwater?
Alkalinity, silica, iron, dissolved oxygen, calcium, and magnesium.
What are the major types of external treatments?
Softening, evaporation, and membrane contractors.
What are the major types of internal treatments?
Phosphates, chelates, and polymers.
Why may chemicals be added internally or externally to boiler feedwater?
External treatment is used when the amount of one or more of the feedwater impurities is too high to be tolerated by the boiler system. The purpose of internal treatment is to properly react with feedwater hardness, condition sludge, scavenge oxygen, and prevent boiler water foaming.
Below is a transcript of the video sample provided for this module:
The primary function of a boiler is to capture the heat from combusted fuel to heat water and generate steam. The conditions within a modern boiler place some stringent requirements on the water which circulates through it. First, at the high temperatures and pressures within the boiler, low concentrations of some chemical compounds in the boiler feed water, which are not a problem at room temperature, will either become corrosive or create damaging deposits on the hot walls of the boiler tubes.
Second, as water boils and creates steam, solids in the water tend to remain in the water. This creates a situation where even small concentrations of impurities in the feed water tend to increase with time. Increased concentrations magnify the negative effects of the impurities.
Use the additional resources and links below to learn more about this topic: