| Cooling system maintenance
Advantages and disadvantages The table below summarises the advantages and disadvantages of the cleaning methods discussed. Although proven and successfully applied for over 40 years, foam cleaning is largely unknown in Europe (as mentioned in the previous article in Modern Power Systems). Originally invented for removal of iron and copper oxides from steam turbine blades, foam cleaning mixtures can be adapted to remove any type of deposits including silica and other hard sticking scale from turbines, compressors or heat exchangers. Surfaces can be given additional protection from corrosion with a passivation step.
By injection of suitable additives, foam cleaning can also be used for disinfection of condensers before visual inspection. The foam cleaning process requires only short outage periods and produces only small amounts of waste needing to be disposed of. Because the foam composition can be
Figure 9. Inlet tube sheet before (top) and after foam cleaning (bottom)
Before
Figure 11. Gas turbine intercooler system, employing spiral wound, densely packed stainless steel tubes. The white deposits mainly consist of phosphates and other mineral compounds
adapted to the scale and debris to be removed, the method is very effective.
Finally, foam cleaning can be applied to complicated configurations that are not accessible to other cleaning methods because the foam can reach very narrow clearances and gaps.
After
Before
Figure 12. Intercooler before and after foam cleaning Summary
Figure 10. Inner tube surfaces before (top) and after foam cleaning (bottom)
The stainless steel coils inside the heat exchangers (shell material carbon steel) have a very densely packed inner surface. This arrangement does not allow application of typical hydrodynamic cleaning methods, like high pressure water jet blasting or water jet washing. The heat exchanger’s tube support structures do not allow filling with a chemical solution for cleaning or flushing when fully loaded. This would only be possible if a temporary supporting structure was built. The power plant operator allowed only two weeks for carrying out the cleaning. Use of foam cleaning allowed all scale and deposits to be removed from the intercoolers (Figure 12), and within the required schedule.
www.modernpowersystems.com | March 2026 | 25
of the advantages and disadvantages of the cleaning methods discussed.
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