The advantages of circulating fluidized bed (CFB) boilers over other boiler types include the possibility to fire fuels of low calorific value and rich in mineral matter like oil shale. However, particle-surface interactions may cause wear of surfaces submerged in ITREX, of the walls. inside the furnace, of chrome-plated panels in separators, and of heat surfaces in boiler convection passes. This takes place directly in the boiler, but particle-surface interactions begin in the fuel supply system already and end in the ash removal system. The present article deals with wear in the fuel supply system on the basis of practical experience.