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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 46330 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Afshin, Hossein; Farhanieh, Bijan
- Abstract:
- Direct reduction of iron is a process to reduce iron in solid phase. The output of this procedure is direct reduced iron (DRI) that can be used in electric arc furnacewithout further changes. Midrex technology, which is the most important one among direct reduction of iron processes, provides 60% of DRI.
Required synthesis gas for reduction process is gained from reforming of the natural gas,with the major proportion of methane, with water steam and carbon dioxide in a piece of equipment called “reformer”. As a matter of fact, reformer is a type of plug chemical reactors. Input materials (natural gas, water steam and carbon dioxide) enter from the bottom section to the prepared pipes in the exterior layer and as they flow on the catalytic bed they absorb heat and reach the appropriate temperature for reduction process. Dominant physical phenomena in reformers can be categorized in three subdivides: mass transfer and particle diffusion, heat transfer between catalytic bed and fluid, and momentum transfer of the gas phase.
Synthesis gas production is known as the capacity determinative in a direct reduction factory and 20 % of the total costs of the factory are related to providence of reformer pipes. Scorching spots due to clogging caused from carbon formation is one of the damages to these pipes. Understand of the design of reformers and their optimum state of operation which is the focus of this study is momentous in order to significant importance of direct reduction process in the steel industry of Iran. The attempt of this study is to define the condition of the input gas to the reformers that results in perfect production.
First of all it has been tried to define the descriptive equations of the reformers and coefficients adjusted to the practical observations to achieve the goal of this study and then the results investigated by means of numerical solution and total verification. A method for identification of proper outputs in specific entrance of pressure and mass flux is suggested at last. Reduction of carbon formation probability by means of some verification is also investigated - Keywords:
- Numerical Solution ; Finite Volume Method ; Direct Reduction Process ; Midrex Method ; Direct Iron Reduction ; Midrex Reformer
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