Film-forming amines (FFAs) have been successfully used in boiler applications to help facilities reduce corrosion, deposition, and iron transport throughout their steam systems.
This innovative technology can be particularly beneficial for refineries, where maintaining utility system conditions is important for production efficiency.
Film-Forming Amine Treatment vs. Traditional Boiler Treatment
Traditional boiler treatment programs do not generally include a corrosion inhibitor. Pretreatment is used to reduce scale and corrosive ions, and oxygen levels are reduced via mechanical and chemical means. pH is raised to passivate metal surfaces, and temperature is increased to deoxygenate the water through a deaerator, helping build the passive layer.
In complicated systems such as those seen at refineries, these standard processes may not achieve the desired level of corrosion inhibition. Film-forming amines can be a beneficial supplement to the treatment program, as they bind directly to the metal surfaces, where corrosion is typically more difficult to treat.
Benefits of Film-Forming Amine Treatment for Refinery Operations
FFA programs have primarily been used in power industry applications in the past. However, they can offer significant benefits to applications specific to the refining industry.
Soft Water Systems
In combination with an existing corrosion inhibition program, FFA can help:
- Reduce amine usage
- Treat complicated and extensive condensate systems and reboilers, as well as mixed-metallurgy systems containing copper and iron
- Inhibit corrosion during layup periods
Higher Purity Systems
FFA can help reduce corrosion in the following higher purity systems:
- Low-pressure waste heat boilers such as SRU condensers
- Mixed metallurgy systems balancing pH and oxygen scavengers
- Condensate and feedwater systems, where reducing iron and copper transport via corrosion inhibition may help reduce the risk of underdeposit corrosion.
These products also help reduce flow-accelerated corrosion and issues related to layup.
What are Film-Forming Amines and How Do They Work?
Film-forming amines contain a long chain hydrocarbon as part of the molecule. The amine portion of the molecule allows it to form an attachment to the copper or iron within the oxide layer on the metal surface. The hydrocarbon portion of the molecule repels water, inhibiting water transport to the surface where the film is formed.
In traditional treatment, mild steel develops a passive oxide layer by building layers of magnetite particles that get progressively less organized and irregular in shape as they move away from the surface. The stacking of these particles decreases the corrosion rate so smaller, more organized particles result in decreased layer depth. Particle size is strongly influenced by the solubility and mobility of the magnetite particle as well as the oxidation rate of the corroding ferrous iron from the metal surface.
A low concentration of oxygen increases the oxidation rate of ferrous iron dissolving from the surface, which both increases magnetite formation and allows for the formation of low concentrations of hematite.
Hematite forms an iron oxide polymer that interacts with the magnetite, decreasing its mobility. This reduces the particle size and cements the particle in place, allowing for a more compact, passive, and stable iron oxide layer.
With FFA treatment, the epitaxial layer is depleted, and a film is formed to create a hydrophobic surface. If the FFA residual is decreased below a film maintenance level, the epitaxial layer will regrow to its original depth.
FFA treatment will remove the less organized top portion of the iron oxide layer because it is not bonded with the other particles as effectively. Once the looser iron oxide layer is removed, the film starts to build and increase in density as more treatment is added.
Measuring Hydrophobicity
A successfully applied FFA program will create a hydrophobic layer on boiler surfaces.
Image of a steam drum with a hydrophobic layer of FFA. Water droplets stay on the surface of the drum without being absorbed into the surface and causing corrosion.
Preparing for FFA Application: What You Need to Know
Prior to feeding FFA treatment in your boiler systems, several factors may need to be considered. These include, but are not limited to:
- Water analysis data: is water chemistry on target based on industry guidelines?
- Where does the water go?
- What percent of condensate is returned?
- Does condensate get polished?
- Are there any blowdown restrictions?
- Historical data
- pH trends for drums, steam system, and hotwell
- Iron residual trends for drums and hotwell
- Cation conductivity trends in the hotwell
- Deposit weight density
- Boiler inspection reports
- Pictures of drum internals
- Economizer and evaporator tube wall thickness measured by ultrasonic testing
How is FFA Treatment Performance Measured?
To monitor the effectiveness of FFA treatment, tracking the following parameters is recommended:
- Iron residual reduction (benchmarked against historic iron residual levels)
- Reduction in corroding areas (benchmarked against past inspections)
- Hydrophobicity
- Integrity of the piping based on surface analysis
Frequently Asked Questions
Does ChemTreat feed FFA as a stand-alone program for deposit, scale, and corrosion control?
ChemTreat does not feed FFAs as a standalone program. We feed film-forming amines as a supplement to traditional treatment programs for systems that need an enhanced level of corrosion inhibition.
Does this technology “gunk up” like previous generations utilizing octadecylamine (ODA) chemistry?
ChemTreat’s FFA technology is more volatile than products such as ODA and does not have the same solubility issues. Filming amines can also be tested to verify that product is not being overfed. FFA application has not caused issues such as gunking, probe fouling, strain clogging, etc.
Are filming amines sensitive to pH?
Unlike previous generations of this technology, ChemTreat’s filming amine is not pH-sensitive, so the hydrophobic layer stays intact if pH increases.
Do filming amines bind catalyst sites?
ChemTreat’s FFA technology has been fed in systems where steam directly contacts with catalyst sites, and we have not observed the product binding with catalysts. Catalysts are very active sites that operate at a temperature above the stability of FFAs, so we would not expect filming amines to bind with them.
Is FFA the Right Treatment Solution for my Refinery?
As with all other technologies, due diligence is necessary to determine the feasibility for utilizing the methods discussed in this post.
It is always important to consult your equipment manuals and guides and seek guidance from your local water treatment representative to address your specific needs.
Contact ChemTreat today to see if FFA treatment is right for your facility.
