The Study On The Mathematic Model Of Cylinder-type Reduction Process

China is rich in coal resource, which provides a good condition for the developmentof coal based process. Direct-reduction ironmaking has many potential advantages whichbelongs to non blast furnace ironmaking, and attracted more and more attention in recentyears. The Tunnel kiln retort method was used in powder metallurgy process for the highadded value products, direct reduction iron (sponge iron) used as an important raw materialfor smelting special steel has a high additional value. However, the reaction temperature islow and the dynamic condition is poor in the direct reduction process, which affects thesponge iron production seriously. The reactive cylinder direct reduction process containsmany chemical reactions, these reactions occurs simultaneously, couples and influences byeach other which makes the reaction system become very complicated.In this paper, a non-isothermal mathematical model was established, the equationswere discrete using the control volume integration (display format) and were compiled bythe C language. The model was used to the numerical simulation of the cylinder typereactive process. To the whole process of reaction, the mass transfer, heat transfer, reactionrate change of gases in the mineral layer and the change of quality in iron ore layer couldbe described.Through Numerical simulation, we can draw the following conclusions:(1) Simulated the reactive cylinder direct reduction experiment by a non-isothermalmathematical model, the temperature field and the reduction degree of iron ore obtained bythe model were in good agreement with the experimental values, the model can describethe process of the reactive cylinder direct reduction experiment.(2) The numerical calculation on experiment process of cylinder-type reduction showsthat：the ratio of chemical reaction heat and heat conduction closing to the inner/outerside of the iron ore layer is0.6-0.9during the reaction. The reaction heat (carbon gasification and water gas reaction) released by reaction of carbon and heat conductionquantity is considerable, which effects the heat transfer of reactive cylinder and leads to thetemperature difference between the reactive cylinder at the center and the outer side is205oC.Heat transfer and mass transfer of gases effect commonly on the cylinder typereduction reaction.(3)The numerical calculation can be drawn that:In the process of cylinder-typereduction, The degree of iron ore reduction of closing to the coke layer is relatively higherand the degree of closing to the center of iron ore layer is relatively lower which showsU word distribution.