Dr. Tateo Usui

Abstract:

Gas carburizing of solid steel is carried out by using a large amount of hydrocarbon in order to keep the furnace atmosphere as long as constant, because carbon from hydrocarbon is consumed for carburization of the steel surface and hydrogen remains in the furnace. In the present study, selective removal methods of H₂ were surveyed and fundamental experiment was done by using Proton Conductor SrZr_1-xY_xO_3-a , which was prepared by spark plasma sintering method; hydrogen gas was separated from wet simulated coke oven gas atmosphere at high temperature successfully.

Therefore, injection of hydrogen through the tuyers of the blast furnace is expected to reduce coke rate; this is a kind of bridge technology for conventional blast furnace system to hydrogen reduction furnace system.

 At the same time, reported method to selectively remove H₂ was also applied to bench scale furnace for gas carburizing of solid steel by using gas filter module made of poli-imido fiber tube. The control of the furnace atmosphere was very important to keep it constant, which was also studied numerically as well as experimentally. Finally, selective removal of H₂ from the furnace was verified experimentally and the flow rate of so-called “carrier gas” (hydrocarbons) could be reduced more than 75 % under the condition of the same quality of steel surface by the carburization treatment. As a result, exhaust gas volume could also be reduced and the burnt exhaust gas, namely, CO₂ emission was minimized.