HOW TO RECONSTRUCT A COOLING TOWER

THE THERMAL PERFORMANCE AND STRUCTURAL INTEGRITY OF AGING COOLING TOWERS CAN BE RESTORED

By Ed Shupert

Cooling towers play an important role in modern power plants. But there comes a time when aging cooling towers require more than routine maintenance and repairs or replacement of components, such as heat transfer media. Thermal performance can fall and structural integrity can become a major issue. It is time for a reconstruction project.

A Job Safety Analysis (JSA) is a recommended first-step before accessing the cooling tower. The JSA should address inherent dangers such as high voltage, fall hazards and trip hazards, and define appropriate mitigation efforts, such as lockout and tagout, personal protective equipment and fall protection.

Another smart early step is a performance test. This gives the plant operator a starting point to establish goals for capacity improvement, as well as a reference point for evaluating the final results.

The Cooling Technology Institute (CTI) has a published thermal test code, ATC-105, by which the performance accuracy can be determined. Specialized instrumentation is required to determine precise water flow rates, air rates and temperatures. Some vendors may offer this and outside agencies can also assist.

The scope of work should be developed based on a thorough inspection to identify:

• Deterioration of cooling tower structural elements

• Fill media clogging or damage

• Condition of drift eliminators and louvers

• Water distribution system — missing nozzles or leaking pipes

• Wear and corrosion of mechanical components

• Ladders and guardrail deterioration.

If a cooling tower’s fill is clogged or damaged beyond repair, there may be an opportunity to replace it with higher performing fill. A common reconstruction project where additional cooling capacity is sought involves replacing the original splash fill with PVC film fill (where water quality allows). In other cases, where the integrity of fill is sufficient and additional thermal performance is not sought, simply cleaning the fill may meet project goals.

Replacing wood with fiberglass reinforced plastic (FRP) is a way to increase tower lifespan. A coal-powered baseload plant, for example, replaced wooden elements, such as the hot water deck, deck supports, walkways, crossflow pipe saddle supports and structural splice plates with FRP. It also changed a carbon steel riser support beam to stainless steel.

After reconstruction is complete, a maintenance plan should be created for the cooling tower. At a minimum, every cell of the tower should receive an annual inspection of gearboxes, gearbox oil and seals, driveshafts, distribution water basins, fan cylinders, fans, fan tip clearance and pitch, fill, distribution piping and nozzles, ladders and other safety components.

Ed Shupert is Manager of Reconstruction Project Management at SPX Cooling Technologies. SPX Cooling Technologies is a global manufacturer of cooling towers, providing full-service cooling solutions, components and technical support for power generation, petrochemical and industrial applications for nearly a century.

For more information, please visit

www.spxcooling.com.