Analysis of Graphite Dust Deposition in Hot Gas Duct of HTGR

The behavior of the graphite dust is important to the safety of high-temperature gas-cooled reactor (HTGR). The temperature field in hot gas duct was obtained using computational fluid dynamics (CFD) method. Further analysis to the thermo-phoretic deposition and turbulent deposition shows that as the dust particle diameter increases, the thermo-phoretic deposition efficiency decreases, and the turbulent deposition efficiency initially decreases and then increases. The comparisons of calculation results for two reactor powers, namely 30%FP (full power) and 100%FP, indicate that the thermo-phoretic deposition efficiency is higher at 30%FP than that at 100%FP, while the turbulent deposition efficiency grows more rapidly at 100%FP. Besides, the results also demonstrate that the thermophoretic deposition and the turbulent deposition are nearly equivalent when particle sizes are small, while the turbulent deposition becomes dominant when particle sizes are fairly large. The calculation results by using the most probable distribution of particle size show that the total deposition of graphite dusts in hot gas duct is limited.