Oil in Condensate

The red dots show measurement locations for colour-, oil- or TOC in condensate.

Condensate is typically clean water. Condensate return is used as boiler feedwater whenever possible, since it is clean and hot. It takes significantly less energy to reboil condensate return than to use fresh make-up water.
Condensate goes through turbines, pumps, heat exchangers and other equipment. Oil or other contaminants may leak unrecognized into the condensate.  These contaminants involve coating, foaming, corrosion and other problems if they reach the boiler. Even if there are no oil leaks, the condensate can become contaminated with iron resulting from an improperly treated piping system or corrosion. This iron will cause high erosion at the turbine blades.  Sometimes condensate is cleaned by passing it through polishing filters to remove filterable contaminants, but this is expensive and the measurement system is required for filtration control.

Optical or Acoustic:
Two different principles of measurement are typically used for oil and particle monitoring in condensate or feedwater, the classic optical 12°forward scatter turbidity measurement as well as the ultrasonic reflection. Both methods detect even low contaminations immediately.

Optical: Forward scatter turbidity (Model MoniTurb-F / Messenger)
The optical measurement allows very high process temperatures. The sapphire windows of the sensor typically become opaque after some weeks or month of operation, due to mineral coatings. This requires a consistent manual cleaning of the windows in diluted HCL.

Acoustic: Ultrasonic reflection (Model AS3 / AT3)
The ultrasonic pulses of the measurement probe are not affected by any coatings. The accruing of mineral coatings is prevented by the ultrasonic cleaning effect additionally.  The probe does not have any wearing parts, shows extreme high long term stability and is usually free of maintenance.  The design of the probe allows an easy and cost-effective installation. These advantages make the ultrasonic reflection to a perfect technology for this application.

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