Wear of graphite pebbles modeled using a macroscopic particle model in a pneumatic transport lifting pipe

摘要

Modern high temperature gas-cooled reactors (HTGR) uses charging and discharging devices to complete the graphite pebble fuel cycle using pneumatic transport. However, the wear of the graphite pebbles and the radioactive products in the lifting pipe have a negative impact on the reactor. This study quantified the wear rate by modeling the movement and impacts of the graphite pebbles in the vertical lifting pipe using macroscopic particle model and the finite volume method with comparisons to visual monitoring for measuring the lift velocity and graphite pebble impacts on the wall. The results show that the impact frequency varies and depends mainly on the pebble lifting speed and uncertain radial velocity. The impact, contact characteristics and radial velocity of the lifting process were combined into a pebble wear model. The results show that this wear model is relatively robust and in good agreement with the experimental data and can provide guidance for engineering estimates for HTGR designs. (C) 2019 Elsevier B.V. All rights reserved.