Proper Water Treatment Fuels Dependable Power Generation

A demineralized water treatment system removes impurities from feedwater entering a power station’s boiler, heading off scaling, corrosion, and other issues that can harm equipment and interrupt power delivery. Guest contributor GAI Engineering Manager David A. Weakley II, PE, offers his perspective on water treatment’s role in reliable power generation.

A power station’s primary objective is to generate power reliably and profitably. This makes it essential for power providers to invest in a robust, modern, and well-maintained demineralized water system to help make sure that the facility’s boiler, turbine, and condenser are operating well.

The proactive outlay of $3-6M to install a redundant and well-specified demineralized water system can serve to protect not only tens of millions of dollars of capital equipment, but will also help safeguard the power station’s capability to reliably generate electricity.

Raw feedwater coming in to a power station contains suspended and dissolved impurities that, if left untreated, begin to concentrate and collect in the power station’s boiler equipment to the point of causing scaling, corrosion, or other issues. A well-designed demineralized water system mitigates these outcomes by removing impurities before the feedwater reaches the boiler. Some of the issues associated with inadequately treated boiler feedwater are reflected in the table below:

Problematic Constituent in
Boiler Feedwater
Effects on Boiler Tubes, Turbine Blades, and Condensers

Suspended Solids
Solids buildup can cause scaling, plugging, abrasion, corrosion, and leaks.

Calcium and Magnesium
Elevated concentrations will result in scaling/plating in the system that will ultimately reduce flowrates, excessive headloss, and reduced heat transfer efficiency.

Creation of gypsum that will deposit and scale causing reduced flowrates, excessive headloss, and reduced heat transfer efficiency.

Iron and Manganese
Deposits, scaling, bacterial growth, and rust corrosion; can lead to plugging of tubes or imbalances on rotating equipment.

Carbon Dioxide
Can suppress pH levels, which promotes corrosion. Neutralizes amines that are used as a corrosion-prevention additive in condensers.

Dissolved Oxygen
Oxidizes and corrodes metal, can lead to weakened and pitted boiler tubes.

Hard, brittle deposits that can damage turbine blades and reduce heat transfer efficiency. Silica scale can be impervious to cleaning with hydrochloric acid.

Chloride corrosion can rust, weaken, and pit boiler tubes. Chloride corrosion is exacerbated at higher temperatures and lower pH levels. Leaks in tube walls can occur.

Carbonate / Bicarbonate
Scaling of calcium carbonate and acidic corrosion of carbon dioxide can occur if present.

A demineralized water system consists of several unit-treatment processes to filter suspended solids and remove dissolved salts from feedwater prior to steam generation. Traditionally, ion exchange (IX) vessels are used to systematically remove cations (calcium, magnesium, sodium, etc.), then anions (chloride, sulfates, bicarbonate, and even silica). Depending on specific site conditions, some other facilities may opt to utilize reverse osmosis (RO) systems to pressurize the filtered water and force the water across a semi-permeable membrane sized to let only water molecules pass through while rejecting suspended salts. Power providers require high pressure, high temperature steam for boiler operations, so a higher quality water is required. Further polishing of demineralized water from traditional IX vessels and RO systems can be achieved with a polishing mixed bed (ion exchange) or electro-deionization technology.

A properly demineralized water system heads off scaling, corrosion, and other effects of inadequately treated feedwater before these issues become severe enough to significantly reduce performance and allows for more efficient boiler operations by reducing the frequency of system blowdowns and dosing of chemical additives. All of these attributes contribute to maintaining reliable, cost-effective power delivery for consumers and greatly enhancing equipment life and operation for power providers.

Demineralized water system

Contact David A. Weakley II, PE to learn more about power station boiler feedwater and how water treatment can help manage troublesome constituents in your steam cycle.

David WeakleyDavid Weakley II, PE specializes in the design and optimization of water and wastewater treatment processes and facilities. With a strong focus on environmental compliance and improved plant efficiency, David identifies opportunities for reusing water from existing facility processes, as well as reducing overall facility water, power and chemical consumption, sludge production, and labor demands. His professional experience includes water treatment for municipalities (wastewater and drinking water), power generation, mining, oil and gas (production and refining), fertilizer production, petrochemicals, and seawater desalination.

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