Wear on tubes by jet impingement in a fluidized bed

This study investigated wear on heat-transfer tubes resulting from impingement of particles entrained by a jet in a fluidized bed. The particular application is the fluidized-bed boiler for the Liquid Metal Fast Breeder Reactor in which a steam-tube failure might cause a high-velocity jet, accelerate particles, and erode adjacent tubes.Croloy and 304 SS tubes immersed in a fluidized bed were subjected to impingement wear from a sonic-jet issuing through a 1.17 mm diam. hole. Wear on target tubes was severe (when spaced near the leak source (1.6 cm)). With spacings of 20 cm, wear was scarcely measurable, being less than 0.002 cm/min.Impingement wear was measured in beds of rounded nickel, angular magnesia and angular iron. Results clearly show that increasing the hardness or angularity of particles increases impingement wear rate.An analysis of impingement wear was performed to project results of room-temperature tests to actual conditions. At 800 K and 1400 kPa, wear is projected to occur at 3 – 5 times the rate measured in tests.