Common Problems and Solutions in Boiler Feed Water Treatment

Introduction

Boiler feed water treatment is a critical process that ensures the efficiency and longevity of boilers. However, several issues can arise due to the combination of boiler makeup and condensate return water. In this article, we will explore the most common problems and their solutions in boiler feed water treatment, including sludge prevention, scale removal, corrosion control, and the prevention of foaming and priming.

An Increase of Sludge

What it means: Sludge in boilers refers to sediments, solids, or oils that are typically softer than scale. If these sediments "bake" onto heat exchangers, it can cause significant issues. This can be a result of inadequate filtration, poor water treatment, or the presence of poorly filtered precipitants. Over time, these sediments can harden and form a layer that insulation layer, causing excessive heating and potentially leading to heat-tube blowouts.

How to avoid it: Effective measures include eliminating sludge-causing contaminants before they become problematic. Periodically blowing out sludge accumulations can also help prevent them from hardening. Sludge conditioners may be used internally in boilers, but high-pressure boilers should avoid liquid conditioners as they can disperse sludge-causing solids, which can be removed during blowdown. Careful monitoring and the use of certain polymers and advanced filtration methods can also be beneficial. High-pressure boilers may require filtering feed water for suspended solids using microfiltration or ultrafiltration technologies.

Scale Buildup

What it means: Scaling occurs when impurities like silica, iron, calcium, magnesium, aluminum, and other contaminants precipitate or settle out when heated, leaving behind hard deposits. These impurities can also lead to scaling.

How to avoid it: The level of scaling is determined by the amount of these impurities in relation to the boiler's pressure. Higher-pressure boilers require higher-quality water. For example, boilers that generate steam to power turbines need complex feed water treatment systems to remove impurities. General guidelines for feed water purity will come from the boiler manufacturer, and organizations like the American Society of Mechanical Engineers (ASME) may have contamination limit recommendations. For low-pressure boilers, simple sodium cycle water softeners are sufficient, while high-pressure boilers may require advanced technologies like reverse osmosis, electrodeionization, or deionization. Water treatment specialists can provide the best solutions for your specific boiler and process.

System Corrosion

What it means: Corrosion in boilers occurs due to the presence of dissolved oxygen, carbon dioxide, and chloride ions, which can break down and weaken metal elements over time. High boiler pressures exacerbate the problem. Chloride stress cracking can also occur when chlorides are present at unacceptable levels.

How to avoid it: To prevent corrosion, high-quality oxygen scavengers can be used to remove dissolved gases from the feed water, in addition to deaerators. Managing the internal chemistry within proper pH levels and implementing an overall internal chemistry program is crucial. Other measures include maintaining appropriate alkalinity levels and using membrane filtration, ion exchange, and softening technologies. Ensuring pH remains between 8.5 and 9.5 can also help.

Prevention of Foaming and Priming

What it means: Foaming and priming in boilers occur when high amounts of dissolved solids are present at the water surface. These impurities bubble up as steam is generated, reducing the efficiency of superheaters and turbines. Foaming is the formation of persistent bubbles in boilers, which is due to substances like oils that reduce water's surface tension.

How to avoid it: The best way to prevent foaming and priming is to maintain a low level of dissolved solids and control alkalinity. This can be achieved using membrane filtration, ion exchange, and softening technologies, and ensuring that the pH remains between 8.5 and 9.5. Proper pretreatment and chemistry control are also essential in maintaining boiler efficiency.

How SAMCO Can Help

SAMCO offers a comprehensive approach to boiler feed water treatment. Our strategies include proper pretreatment to remove harmful impurities, effective internal chemistry control, and advanced treatment to manage steam condensate. We have years of experience assisting our customers in understanding the complex chemistry involved and providing top-tier boiler feed water treatment technologies, including filtration and resin services.

Conclusion

Boiler feed water treatment is a crucial aspect of ensuring the longevity and efficiency of your boiler system. By addressing common issues such as sludge, scale buildup, corrosion, and foaming and priming, you can ensure optimal performance and reduce downtime. If you need expert advice and solutions, contact SAMCO for a comprehensive treatment program tailored to your specific needs.