The Midrex Direct Reduction process is based upon a low pressure, moving bed shaft furnace where the reducing gas or syngas moves counter-current to the lumpiron oxide ore or iron oxide pellet solids in the bed. The reducing gas is producedfrom reforming of natural gas using two nickel based catalyst types and one inert ceramic support. Regarding to the very sever operational conditions in Midrexreformers due to reformer high temperatures, low pressures, low steam to carbon ratio and high CO2 content in the reformer feedstock, two varieties of catalysts along with an inert bed layer should be loaded to avoid catalyst deterioration, one with higher nickel oxide content and activity based on alumina and the other with lower nickel oxide and activity on rugged magnesium oxide carrier. Unlike steam reformers, in Midrex reformers, feedstock moves upward inside thetubes and accordingly the catalysts loading pattern should be adjusted so that thefeed gas stream firstly pre-heated over sufficient volume of ceramic support layer, then partially reformed and heated over semi-active magnesium oxide based catalyst to facilitate the process conditions of application of an alumina based high active catalyst. Hence, the ultimate reforming will be done over high active catalyst.
Several significant features of the robust DRI reforming catalysts are as follows:
- High catalytic activity for converting feedstock
- High resistance against coke formation
- High heat transfer coefficient
- Low pressure drop and high geometric surface area
- Excellent stability of catalyst performance.
C11-09-05RWH : is a high active DRI reforming catalyst based on alumina carrier. This 6-hole ribbed ring shaped catalyst containing highnickel oxide content is loaded inside Midrex reformer tubes as the major layer, is considered for the complementary reforming of natural gas purposes along with semi-active catalyst.
C11-7-02RR : A superior semi-active DRI reforming catalyst with lower nickel oxide content is based on magnesium oxide (MgO) carrier.
CS 305 : Is aAlumina based high strength inert ceramic support used for loading the bottom section of Midrex reformer tubes.