Hydrogen, in terms of reducibility, is the best alternative for use as a reducing agent for the reduction of iron oxides. In fact, hydrogen plasma smelting reduction (HPSR) is a new “CO2“-free steelmaking process in which iron oxides are reduced by hydrogen in the plasma state. In HPSR, plasma is generated by creating an electric arc between a hollow graphite electrode as the cathode and molten iron oxide bath as the anode, with continual input of a mixed gas containing argon and hydrogen. Figure 1 shows the basic flow sheet of the plasma experimental equipment which was installed at the Chair of Ferrous Metallurgy.
In the process, argon or nitrogen is used to conduct the current in the plasma arc; argon is preferred due to its low ionization energy and high conductivity. Hydrogen operates as the reducing agent; hence, a mixture of hydrogen and argon is injected into the arc zone in the reactor through the hollow graphite electrode. Collision of electrons with hydrogen molecules
at high temperatures leads to the activation of the hydrogen molecules. The injection of gases through the electrode directly to the arc zone guarantees optimal conditions for atomization and ionization. Excited hydrogen molecules provide a potentially very useful way for the reduction of stable metal oxides.
The stabilization of the arc is one of the main influencing parameters on the productivity of the process. There are several methods to be employed to improve the stabilization of the plasma arc. In fact, argon is used not only to decrease hydrogen concentration in the H2-Ar mixture to increase the hydrogen utilization but also to stabilize the arc. Despite of using argon as a stabilizer, the stabilization of the HPSR plasma arc should be increased by the other methods as well. This study is to design and construct a system to increase the plasma arc stability of the plasma arc from laboratory-scale plasma facility.
- Characterization of the plasma arc stabilizer (PAS)
- Designation of the PAS
- Construction of the PAS
- Installation of PAS on the Laboratory scale
- Commissioning and testing