Steam Turbine Deposits – How They Occur, Their Effects and How They Can Be Eliminated

ABSTRACT

During operation, impurities can enter the water-steam cycle (WSC) with the make-up water, through leaks or with the process condensate return and cause corrosion and deposits. Deposits can form at any point in the WSC, depending on the composition and local conditions (pressure, temperature, flow conditions). Deposits are formed from dissolved and suspended substances that are transported from the point of formation to the point of deposition in the WSC with the water or steam flow. The deposits formed on the turbine blades not only disrupt the flow around the blades, they also increase the pressure loss between the turbine inlet and outlet and thus reduce the efficiency of the overall process.

Three methods for removing turbine deposits have proven to be particularly effective, whereby each of the methods mentioned has specific advantages and disadvantages which will be discussed in this article.

REFERENCES

• Failure Analysis – Fundamentals and Performance of Failure Analysis, 2011. Verein Deutscher Ingenieure e.V., Beuth Verlag GmbH, Berlin, Germany, VDI 3822.
• Leidich, F. U., "Some Basics of Power Plant Chemistry – Corrosion and Deposition", PPCHEM 2023, 25(01), 38.
• Technical Guidance Document: Procedures for the Measurement of Carryover of Boiler Water into Steam, 2008. International Association for the Properties of Water and Steam, IAPWS TGD1-08. Available from https://www.iapws.org.
• State-of-Knowledge on Deposition, Part 2: Assessment of Deposition Activity in Fossil Plant Units, 2003. Electric Power Research Institute, Palo Alto, CA, USA, EPRI 1004930.
• Leidich, F. U., "Power Plant Water Chemistry", presented at Alstom User Symposium, 2005 (Washington, DC, USA). ALSTOM Power Generation AG, Germany.
• Leidich, F. U., Rziha, M., "The Economic Benefits and Goals of Power Plant Chemistry", PPCHEM 2021, 23(06), 254.
• Svoboda, R., Palmer, D. A., "Behaviour of Copper in Generator Stator Cooling Water Systems", presented at the 15th International Conference on the Properties of Water and Steam, 2008 (Berlin, Germany). International Association for the Properties of Water and Steam.
  Also published in: PowerPlant Chemistry 2009, 11(2), 70.
• Leidich, F. U., "The Economic Impact of Power Plant Chemistry in Regard to Maintenance and Lifetime", presented at the Steam Turbine and Generator User Group Meeting, 2016 (Manchester, UK). Institution of Mechanical Engineers, London, UK.
• Leidich, F. U., "Avoidance of Common Mistakes during Failure Analyses and Misinterpretation of Lab Results – Part 1: Sampling", PPCHEM 2021, 23(03), 108.
• Leidich, F. U., "Avoidance of Common Mistakes during Failure Analyses and Misinterpretation of Lab Results – Part 2: Lab Analyses / Sample Handling, Preparation, and Analytical Procedures", PPCHEM 2022, 24(02), 70.
• Maika, W., Foster, C. D., "Chemical Removal of Deposits from Turbine Rotors – Experiences after First Application in European Power Plant", presented at the Chemie im Kraftwerk, 2013 (Leipzig, Germany). vgbe energy service GmbH, Essen, Germany.
• Ecol Sp. z o.o., Rybnik, Poland: https://ecol.eu.