Effects of Measurement Materials and Oxygen Partial Pressure on Synthetic Coal Slag Viscosity Values
The viscosity of the molten ash (slag) resulting from the mineral constituents in slagging gasifiers is critical for controlling the operation of the process. The viscosity of two synthetic slags with compositions resembling the mineral impurity constitution of coal feedstocks were examined at temperatures from 1300~1500 °C using a rotating-bob viscometer. A few combinations of atmospheres and experimental materials were investigated with respect to one another to determine slag viscosity. A CO/CO2 atmosphere (CO:CO2=1.8, corresponding to PO2=10-8 atm) is required to sustain ferrous ions in FeO-containing slags, however it is oxidizing to most metals. Iron oxide in the slag prevents usage of Fe parts. In un-purified Ar, the Fe metal surface oxidizes. Utilizing purified argon prevents iron measurement components from oxidation, however, the metallic surfaces act as nucleation sites for the reduction of the Fe-oxide in the slag into metallic Fe. Dissolution of ceramic materials, including Al2O3 and ZrO2, occurs in both atmospheres. Therefore, evaluating slag properties in the laboratory is challenging. The measured viscosities diverged depending on the material selection. This difference is likely attributable to the container/spindle-slag interaction. The measurements with ceramic parts agreed best with FactSage prediction, with an average activation energy of 271.2 kJ for eastern coal slag. The dissolution of container/spindles materials was substantial during measurement of western coal slag, and precipitation of crystalline phase was inevitable. Nevertheless, the viscosity data agreed best with Kalmanovitch prediction above 1350oC. The activation energy changed dramatically for both datasets, likely indicating the Newtonian-to-non-Newtonian transition.
coal gasifier viscosity measurement components crystallization
Jingxi ZHU Tetsuya Kenneth KANEKO Haoyuan MU James P. BENNETT Seetharaman SRIDHAR
US Department of Energy, National Energy Technology Laboratory, Pittsburgh, PA 15236, USA Department Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, PA 15213, U US Department of Energy, National Energy Technology Laboratory, Albany, OR 97321 USA
国际会议
Ninth International Conference on Molten Slags,Fluxes and Salts(第九届国际熔渣、溶剂与熔盐学术会议 MOLTEN12)
北京
英文
1-16
2012-05-27（万方平台首次上网日期，不代表论文的发表时间）