Boiler Feed Water Treatment: What It Is and How It Works
For industrial companies using a boiler for its facility, some type of boiler feed water treatment system is usually necessary to ensure an efficient process and quality steam generation. The most appropriate boiler feed water treatment system will help the facility avoid costly plant downtime, expensive maintenance fees, and boiler failure as a result of scaling, corrosion, and fouling of the boiler and downstream equipment.
But what is a boiler feed water treatment system and how does it work?
The complex answer to this question (which largely depends on the quality and quantity of makeup water needed for the boiler on an individual basis) is simplified and broken down for you below:
What Is a Boiler Feed Water Treatment System?
A boiler feed water treatment system is a system made up of several individual technologies that address your specific boiler feed water treatment needs.
Treating boiler feed water is essential for both high- and low-pressure boilers. Ensuring the correct treatment is implemented before problems such as fouling, scaling, and corrosion occur, will go a long way in avoiding costly replacements/upgrades down the line.
An efficient and well-designed boiler feed water treatment system should be able to:
- Efficiently treat boiler feed water and remove harmful impurities prior to entering the boiler
- Promote internal boiler chemistry control
- Maximize use of steam condensate
- Control return-line corrosion
- Avoid plant downtime and boiler failure
- Prolong equipment service life
What Does a Boiler Feed Water Treatment System Include?
As mentioned above, the exact components of a boiler feed water treatment system depend on the quality of water being drawn from in relation to the quality of water makeup needed for the specific boiler (according to the manufacturer’s recommendations), but in general, a basic boiler feed water treatment system typically includes some type of:
- Filtration and ultrafiltration
- Ion exchange/softening
- Membrane processes such as reverse osmosis and nanofiltration
- Deaeration/degasification
- Coagulation/chemical precipitation
Depending on the impurities present in your water, any combination of these treatments might best suit your facility and make up your treatment system, and depending on the needs of your plant and process, these standard components are usually adequate. However, if your plant requires a system that provides a bit more customization, there might be some features or technologies you will need to add on.
What Contaminants Does Boiler Feed Water Treatment Remove?
A boiler feed water treatment system might be made up of the technologies necessary to remove problematic dissolved solids, suspended solids, and organic material, including any number of the following:
- Iron: either soluble or insoluble, iron can deposit on boiler parts and tubes, damage downstream equipment, and affect the quality of certain manufacturing processes
- Copper: can cause deposits to settle in high-pressure turbines, decreasing their efficiency and requiring costly cleaning or equipment change-outs
- Silica: if not removed to low levels, especially in high-pressure boilers, silica can cause extremely hard scaling
- Calcium: can cause scaling in several forms depending on the chemistry of the boiler feed water (e.g. calcium silicate, calcium phosphate, etc.)
- Magnesium: if combined with phosphate, magnesium can stick to the interior of the boiler and coat tubes, attracting more solids and contributing to scale
- Aluminum: deposits as scale on the boiler interior and can react with silica to increase the likelihood of scaling
- Hardness: also causes deposits and scale on boiler parts and piping
- Dissolved gasses: chemical reactions due to the presence of dissolved gases such as oxygen and carbon dioxide can cause severe corrosion on boiler pipes and parts
[Download our free boiler feed water treatment e-book.]
How Does a Boiler Feed Water Treatment System Work?
Specific treatment processes vary depending on the requirements of the boiler and quality/chemistry of the feed and makeup water, but a typical boiler feed water treatment system will usually include the following steps:
1. Makeup Water Intake
Makeup water, or the water replacing evaporated or leaked water from the boiler, is first drawn from its source, whether raw water, city water, city-treated effluent, in-plant wastewater recycle (cooling tower blowdown recycle), well water, or any other surface water source.
2. Coagulation and Chemical Precipitation
After all the large objects are removed from the original water source, various chemicals are added to a reaction tank to remove the bulk suspended solids and other various contaminants…
3. Filtration and Ultrafiltration
The next step is generally running through some type of filtration to remove any suspended particles such as sediment, turbidity, and certain types of organic matter…
4. Ion Exchange Softening
When pretreating boiler feed water, if there’s high hardness complexed with bicarbonates, sulphates, chlorides, or nitrates, a softening resin can be used…
5. Dealkalization
After the softening process, some boiler feed water treatment systems will utilize dealkalization to reduce alkalinity/pH…
6. Reverse Osmosis (RO) and Nanofiltration (NF)
Reverse osmosis (RO) and nanofiltration (NF) are often used down the line in the boiler feed water treatment system process…
7. Deaeration or Degasification
At this point in the boiler feed water treatment process, any condensate being returned to the system will mix with the treated makeup water and enter the deaeration or degasification process…
8. Distribution
After the boiler feed water has been sufficiently purified according to the boiler manufacturer’s recommendation and other industry-wide regulations, the water is fed to the boiler where it is heated and used to generate steam…
Conclusion
SAMCO Technologies has over 40 years of experience helping our customers design and custom-engineer boiler feed water treatment systems. If you have any questions, be sure to visit our website for more information about boiler feed water treatment here. We also have an article you might be interested in how much a boiler feed water treatment system might cost you and who we recommend as qualified boiler feed water treatment companies for you to consider as you search for all the options available for your plant.
Related Resources
Other SAMCO Technologies articles that relate to boiler feed water include:
- Common Boiler Feed Water Treatment Issues and How to Avoid Them
- How to Choose the Best Boiler Feed Water Treatment Technologies for Your Plant
- Do You Need a Boiler Feed Water Treatment System for Your Plant?
- Scaling vs. Corrosion: Why It Matters for Your Boiler Feed Water System
- 10 of the Best Boiler Feed Water Treatment Equipment Supply and Technology Companies
- How Much Should a Boiler Feed Water Treatment System for a Thermal Power Plant Cost?
- How Much Does a Boiler Feed Water Treatment System Cost? (Pricing, Factors, Etc.)