Fouling Effects of Turbine Exhaust Gases on Heat Exchanger Tubes for Heat Recovery Systems

This paper discusses test results of inserting a cylindrical fouling probe unit in a shipboard LM2500 and a land-based Solar Saturn gas turbine exhausts. These probes are total heat flux measurement devices for film chemistry and heat transfer experiments under simulated heat exchanger conditions.

The average film build-up rate and heat transfer rate are inversely proportional to the test time. The total thermal resistance of the fouled probe increased linearly with time. After a five-hour test, the measured fouling thermal resistance factor was 1.5 times the recommended TEMA design factor. As the average surface temperature for the tests increased, the average fouling film build-up rate and the film sulfur content decreased. Lower wall temperatures produce thicker fouling films. The thermal conductivity of the test films ranged from 0.0204 to 0.0272 BTU/HR-F-ft²/ft (0.0353 to 0.0470 J/sec-K-m²/m).

Up to 30% by weight of the film samples consists of metals and sulfur present in the fuel as impurities or additives. Fouling deposits from shipboard waste heat boiler operations, unlike those from land-based operation, will be affected by more alkali metals in salty air.