Baking soda-based technology cleans gas turbines quickly, effectively
A major steel company in Japan recently switched to a baking soda-based abrasive cleaning technology that has enabled workers to safely and effectively clean its gas turbines in 20 percent of the time and at a fraction of the cost it previously took to handclean them.
The company uses four gas turbines and two steam turbines to generate electricity for one of its manufacturing facilities. Manufactured by Mitsui Zosen, a division of the engineering and ship building company, the 20 MW gas turbines are four feet in diameter and eight feet long. They are made of highly finished, hardened stainless steel and designed to withstand high temperatures and speeds. Over time, however, gas contaminants and products of combustion, including iron oxide, carbon, silica and calcium, build up on the turbine blades and other intricate areas. This build-up eventually impacts the efficiency of the turbine. To keep them running smoothly, the turbines are cleaned every 12 to 24 months, depending on their usage.
Previously, workers dismantled the turbines and manually cleaned them using grinders, brushes and buffers. This process was slow, taking approximately 192 man hours per turbine to complete and posing damage potential to the turbines. The cleaning time is especially critical, as the plant cannot generate electricity without them and must buy electricity in the interim. The company also tried cleaning with aluminum oxide and glass beads, but the processes damaged the turbines by removing small metal fragments. This roughened the surface and created an imbalance potential during high-speed use.
Recently, the company switched to the Armex Cleaning and Coating Removal Systems, developed by Church & Dwight Company Inc. The Accustrip System delivery device is designed to work with compressed air and precisely deliver Armex blast media, a patented media formulation based on baking soda (sodium bicarbonate). It is a natural, water soluble, inorganic salt with a soft crystalline structure for a mild abrasive. The soft crystals actually break down on contact with the substrate. For this application, the media was applied wet for cleaning the open blades and dry for cleaning the turbines` intricate areas.
The results have included significant savings in several areas:
Y Labor Savings: Labor was dramatically reduced from 192 to 36 man hours?a savings of 156 man hours per turbine.
Y Electricity Costs Reduced: By reducing the cleaning time and keeping the turbine cleaning in-house, the facility minimized the amount of purchased electricity used.
Y Cleaning Cycle Time Extended: The baking soda-based technology produces an exceptionally clean and smooth finish. This enables the turbine to run longer and accumulate dirt more slowly. Therefore, the cycle time between cleanings is longer.
Y Rebalancing Eliminated: The gentle cleaning process did not cause any metal removal damage, eliminating the need to rebalance the turbine.
Y Outsourcing Risks Eliminated: As an in-house method, this technology eliminated the need to outsource cleaning and, thus, prevented the potential for costly weather and transporting damage.
Y Worker/Environmental Risks Reduced: The benign nature of the baking soda-based media makes it a safe product for both workers and the environment.