Erosion-oxidation of carbon steel and deposition of particles on a tube during combustion of coal-based fuels in an industrial boiler
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering
- Energy and Environmental Research Corp., Livermore, CA (United States)
An in situ test was used to assess the erosivity of particles in the convection section of an industrial boiler during combustion of micronized coal and while cofiring coal-water fuel with natural gas. Erosion was accelerated using a small jet of clean gas to increase the velocities of ash and unburned char particles at the surface of a carbon steel coupon. Because the jet alters the velocity distribution of the particles, a simulation of the system including particle behavior in the jet, erosion of both tube metal and oxide scale, and scale formation was needed to estimate erosion rates at lower velocities. Although the particles formed from coal-water fuel were more erosive than the particles from micronized coal in the accelerated test, calculations showed that the opposite would be the case on an isolated 51 mm diameter tube at typical convection section velocities. The change in relative erosion rates was due to differences in the size distributions and impaction efficiencies of the particles (effects of gas velocity and size of target). An accurate model is therefore essential to meaningful application of the results of the accelerated test. The calculations indicated that erosion of tube material at 550 K would be slower than 0.05 {micro}m/hour at convection section velocities less than 8 m/s while firing coal-water fuel with natural gas and at velocities less than 10 m/s during combustion of micronized coal. At these velocities, under the conditions of gas and particle composition investigated, erosion is expected to be most rapid on the upstream stagnation line of an isolated tube and to remove material only from the oxide layer, not from the underlying carbon steel.
- Research Organization:
- Engineering Foundation, New York, NY (United States)
- Sponsoring Organization:
- USDOE Pittsburgh Energy Technology Center, PA (United States)
- DOE Contract Number:
- FC22-92PC92162
- OSTI ID:
- 305662
- Report Number(s):
- CONF-9507274--PROC.; ISBN 0-306-45376-2
- Country of Publication:
- United States
- Language:
- English
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