Testing of a Power Feeding Apparatus with High Pressure Oxygen

Abstract

We studied the design and testing of a high-pressure powder feeding apparatus used in some process to feed powder material, such as burnt lime, or metallic compounds in oxygen atmospheres in expected accuracy, and also to examine the repeatability of powder feeding and to study the safety against ignition or explosion based on impurities contained in the powder, such as a small amount of metallic iron powder due to use of a high-pressure oxygen as carrier gas for the powder.
It was understood that the accuracy of the powder feed rate was within a range of ±3 wt%, and gas flow rate did not affect the powder feed rate accuracy.
Further, by mixing an iron powder ranging up to 200 mesh as impurity in the burnt lime, it was found that the temperature at the surface of the transfer tube was raised by friction of the mixed powder against the wall, and we calculated the energy required to cause ignition of the iron powder as impurity.
As a result, the condition under which the mixture of powder and impurities (iron powder) was safely transferred by high-pressure oxygen gas was found to be a mixing ratio of less than 0.1 wt% and a carrier gas speed of less than 15 m/s.