A shock tube and modeling study on the auto-ignition properties of pyrrole in O_2 /CO_2 atmosphere at elevated pressures

摘要

Understanding the details of pyrrole combustion chemistry in the O_2 /CO_2 atmosphere contributes to developingthe strategies for nitrogen oxides (NOx) control during the pressurized oxy-coal combustion(POCC). However, the existing kinetic models for pyrrole oxidation lack multi-dimensional validation, andthe ignition delay times (IDTs) of pyrrole in the O_2 /CO_2 atmosphere are still scarce. This study measuredthe IDTs of pyrrole in O_2 /CO_2 atmospheres at an elevated pressure of 5.2 bar, temperatures from 1271to 1645 K, and equivalence ratios Φ = 0.5, 1.0, and 2.0 in a shock tube. The results demonstrate thatthe pyrrole IDTs decrease with decreasing equivalence ratio and the pyrrole mixtures in O_2 /CO_2 atmosphereshave longer IDTs than those in O_2 /Ar atmospheres. A pyrrole oxidation kinetic model (HUST pyrrolemodel) has been developed by updating 19 reactions in our previous model (HUST pyridine model).HUST pyrrole model gives a satisfactory prediction of the IDTs of pyrrole in the O_2 /Ar atmosphere (measuredby MacNamara et al.) and O_2 /CO_2 atmosphere (measured in this study) and the profiles of pyrrole,HCN, and NO (measured by Yamamoto et al.). The comparison of the HUST pyrrole model with the Lumbrerasmodel (2001) was conducted by the pyrrole IDTs and profiles of HCN using the sensitivity andflux analysis. The addition of HNCPROP and modification of R665 (C_3H_3 + O_2 = CH_2CO + HCO), R1273(AC_3H_4 CN + H_2 = > ALLYLCN + H), R1251 (PYRLNE = ALLYLCN), R1238 (PYRROLE + H = PYRLYL + H 2 ),and R1240 (PYRROLE + OH = PYRLYL + H_2O) in HUST pyrrole model significantly improve the predictionperformance for the pyrrole oxidation. The effects of the equivalence ratio and CO_2 on the IDTs forpyrrole oxidation have been analyzed.