Study of Iron Carburization in CO-based gas mixtures

Open Access
- Author:
- Wang, Zhe
- Graduate Program:
- Mechanical Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 30, 2007
- Committee Members:
- Richard A Yetter, Committee Chair/Co-Chair
Vigor Yang, Committee Member
Thomas Litzinger, Committee Member
Long Qing Chen, Committee Member - Keywords:
- numerical model
Iron carburization - Abstract:
- Experiments were conducted using resistance a relaxation method to study iron carburization for different temperatures and gas-phase mixtures compositions. Under most conditions, the overall reaction rate was found to increase with CO and H2 partial pressures. At extremely high ratios of , further increasing the H2 partial pressure inhibits the overall reaction rate. For the same CO-He gas mixture, the reaction rate increases with the temperature and then decreases, with the peak rate around 960oC. For CO-H2 gas mixtures, the reaction rate is independent of the temperature below 960oC and then decreases with further increases in temperature. An analytic model was established based on previous analytic models. The new analytic model assumes partial equilibrium of the CO dissociation reactions and Langmiur single layer adsorption. Results of the analytic model were found to predict the time history of the carburization process after least squares fitting the model predictions to the experimental data. However, a single set of parameter was insufficient to predict all of the experimental results. Based on the experimental results, the analytic model, and quantum mechanical calculations in the literature, an iron carburization reaction mechanism was established and applied to a numerical model that describe iron foil experiments. The numerical model was found to generally predict iron carburization in all the CO-H2-H2O-He-CO2 gas mixtures studied at 925oC. Also, it shows the correct temperature dependence for carburization in both CO-He and CO-H2 gas mixtures for temperatures below 960oC.