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Turbine Preservation in power plant

 

Frequently Faced Problems

In Power Plants, Fertilizer units & Refineries, expensive equipment like Turbines, Chillers, Power Generators, Boilers, Condensers, Panels etc. begin to rust and corrode when in storage or during shutdown or even when in operation due to excess moisture presence in the air.

Moisture accelerates the rate of corrosion leading to : 

  • Deterioration & decrease in the life of parts and components.
  • Equipment malfunction & failure.

Rate of corrosion accelerates when Relative Humidity crosses the critical level of 40%. Above this level, industrial pollutants like sulphur-di-oxide also enhance the rate of corrosion. The rate of  corrosion is more when surface is exposed to polluted air in combination with high relative humidity. Hence, if the relative humidity(RH) of the area where expensive equipment is stored can be restricted to below 40%,  then all equipment like generator, turbines and related  components can be maintained in a well-preserved condition for immediate activation,whenever required.

Plant Shutdown

Reasons why some equipment in Power Plants/Refineries or the whole unit has to be idled or shutdown temporarily for extended period are

  • For maintenance or repair
  • Due to excess capacity
  • As standby in case of breakdown
  • Partial shut down due to excess capacity
  • ‘Extended cold standby' (ECS)

All equipment, when not in operation, must be preserved in the ‘As Left’ condition till there is a need to activate them. When needed, they should be capable of going ‘On-Line’ immediately.

General Recommendation

During shutdown, Relative Humidity should be maintained at 15%-30% RH at 24ºC (75ºF) and, during operation, at less than 35% RH at ambient temperature to minimise the loss due to corrosion.

Our Solution

Controlling Corrosion through Dehumidification:

Dehumidification involves drying the air by removing excess moisture. Removal of moisture from the storage area lowers the relative humidity of the area, hence, effectively arresting corrosion and microbial growth. During equipment storage, proper dehumidification ensures minimum deterioration of all the internal systems.

Power plants idled for maintenance or repair can be effectively protected from corrosion, by blowing dryair through the steam side as well the generator winding.

Dehumidified air keeps components such as boilers, condensers, turbines, rust free when the plant is shut down. In certain cases, shutdown can go on for a complete year.

In case of fossil fuel power station, layup can be due to furnace, boiler repair or less expensive power availability from an alternate source. During such periods , dryair circulation in the facility prevents rusting and other harmful moisture related problems.

TDS application finds great usage in hydel power plants. Dehumidification services are used for equipment storage even when the plant is under construction and also during annual shutdown.

TDS provides desiccant based dehumidifiers,which provide ideal solution for moisture/ humidity control during storage.This helps in preventing costly repairs and emergency outage. Along with dehumidifiers TDS also provides condensing units, blowers, ducts and technical manpower for dehumidification services.

Benefits
  • Rental services are ideal to fulfill any short term,immediate and seasonal requirement.
  • Postpone capital outlay.
  • Try and Test the suitability of the equipment before purchase.
  • Prevention of dust and moisture ingress into sensitive Generator Windings.
References
  • ALSTOM 
  • NHPC

 

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