Condenser Helium Leak Testing

Power generation turbines, regardless of the type of fuel used, are driven by steam generated in a boiler. The boiler heats water and converts it to steam, spinning the turbine and in turn, driving the generator that produces electrical power. After exiting the turbine, the steam is routed through a condenser, cooling the steam back to water, which is then returned to the boiler to start the cycle again

The efficiency of this process is dictated by the pressure gradient across the turbine and condensing system. Leaks in the system degrade the pressure differential and can easily result in power loss in excess of one megawatt per turbine

Condenser Leak Testing Using Helium

A helium leak detector is comprised of a high vacuum pump and backing pump, which provides the correct vacuum conditions for a small mass spectrometer. In a mass spectrometer, gasses are ionized and accelerated through a magnetic field which isolates gas molecules by mass. This separation allows extremely small concentrations of helium to be detected, thus making it ideal for condenser leak testing. Helium is sprayed around the vacuum portions of the condenser (Figure 1), while a mass spectrometer detects low concentrations of the gas at the outlet of the extractor or at other sites within the vacuum region of the condenser

In general, helium tracer gas testing works very well because leaks can be sealed as soon as identified, and subsequent testing can be performed immediately to confirm that the leaks are sealed. The use of helium is advantageous as the gas is non-toxic, non-flammable non-reactive with other chemicals and very quickly diffuses though small leaks. The helium method allows a maintenance engineer the flexibility to perform leak tests while the plant is operating, without the need to isolate the section under test.