Internal Treatment Chemicals

Benefits of internal boiler water treatment 

Application of Veolia's boiler water internal treatment chemicals is a significant contributor in the fight to control deposit forming contaminants, maintain clean heat transfer surfaces, ensure optimum efficiency, and prevent downtime. In addition, the benefits of internal boiler water treatment include:

• Reduces deposition and potentially removes pre-existing scale
• Reduces the probability of deposit-associated corrosion
• Improves contaminant transport and reduces boiler sludge accumulation
• Promotes clean heat transfer surfaces and enhances boiler efficiency
• Control total cost of ownership by optimizing fuel and water consumption
• Improves reliability and availability by minimizing tube failure and downtime

Your Veolia representative uses proprietary boiler modeling software to demonstrate the operational and financial benefits of applying our boiler treatment recommendations. Our business model relies on creating value for our customers by documenting optimizations based on their highest expectations.

What is boiler water internal treatment?

Boiler water internal treatment is the regrouping of all chemical programs that aim at conditioning dissolved or suspended contaminants and preventing it from causing harm to the boiler’s internals through deposition or corrosion mechanisms. In today’s internal treatment programs, synthetic polymers typically form the backbone of the treatment strategy. Other treatment components may be added, such as phosphate or chelants, but polymers play the main role as the latest molecule’s present significant performance and safety benefits by comparison to other treatment programs.

Why does scale form in a boiler?

The scale is formed by salts that have limited solubility but are not totally insoluble in the boiler water. These salts reach the deposit site in a soluble form and precipitate when concentrated by evaporation. Common feedwater contaminants that can form boiler deposits include calcium, magnesium, iron, copper, silica, and others.

What does scale do to a boiler tube?

Scale prevents adequate heat transfer from the fuel to the water. When scale is present on the waterside, heat from the fuel is accumulated in the tube metallurgy and the temperature of the metal increases due to lack of cooling effect by the water. If the tube temperature exceeds its design temperature, the pressure inside the tube may cause deformation and rupture.

Waterside deposition may also serve as concentration cells for dissolved solids contained in the boiler water. Water found in the porous deposit will evaporate, leaving behind high concentrations of dissolved solids, but the presence of the deposit will keep more water from diluting those. The environment found between the deposit and the tube surface can reach extreme pH due to the presence of free caustic, especially in low purity feedwater systems such as those using softened water. These conditions will cause a caustic attack (i.e., attack) on carbon steel tubes and may reduce the metal thickness to the point where the tube cannot contain the internal pressure. We will then observe tube deformation and rupture.

 

How do boiler water polymers work?

Boiler polymers work through three mechanisms:

1. Dispersion: suspended solids that enter through the feedwater or form by concentration and crystallization of dissolved solids can be kept dispersed by applying electrical charges to them and boiler surfaces. When small particles repulse each other like the magnets of the same pole, they cannot attach to each other or to surfaces to form scale. Instead, they form a fluid sludge that can be blown down easily.

2. Crystal modification: when dissolved solids reach their solubility limit, they form crystals designed to attach to each other and grow into large jagged-edged stars. Their shape also facilitates attachment to boiler surfaces, establishing nucleus sites for scale formation. Polymers can interfere in the crystal formation by filling gaps and rounding edges, making them into balls that easily roll and do not tend to bind with each other or stick to boiler surfaces. The fluid sludge that is formed can more easily be removed through controlled blowdown.

3. Complexation: polymer react directly with dissolved ions to prevent them from interacting together and forming crystals. Instead, they force the contaminants to remain in solution. This mechanism is not as strong as for other treatment programs, namely chelants. Current polymer technologies are designed to act effectively on influent contaminants without harming the structural metallurgy of the boiler.