Understanding the effect of the atmosphere on the release of alkali and alkaline-earth metals (AAEM) during oxy-fuel combustion is important for the development of oxy-fuel combustion technologies with reduced problems with particulate formation and corrosion. To this end, we examined the release behavior of AAEM during oxy-fuel combustion in different gas environments. A drop-tube reactor and ion chromatography were used to investigate the release rates of AAEM. Our results show that the release rates of Na and K were higher than those of Ca and Mg in all types of gas environments. Experimental conditions that favor combustion, namely, higher temperature, higher oxygen content, and longer residence time, markedly increased the release rates of Na and K, whereas changes in the release rates of Ca and Mg were much smaller. The presence of SO 2 in the atmosphere suppressed the release of AAEM via formation of sulfates, whereas the presence of H 2 O promoted it. A synergistic effect of H 2 O and SO 2 on the release of AAEM during oxy-fuel combustion was observed.
Few studies on the low-temperature combustion behavior of MIPK, being a promising fuel additive , have been conducted. In this work, ignition delay times (IDTs) of MIPK were measured in the temperatures ranging between 780–910 K and pressures of 20 and 25 bar using a rapid compression machine (RCM). Oxy-fuel combustion combined with biofuel could remove CO 2 from the atmosphere. The IDTs of MIPK were measured in the temperatures ranging between 1125–1600 K under the O 2 /CO 2 atmosphere at the pressures of 1 and 10 bar using a shock tube . A low to high-temperature MIPK kinetic model (HUST-MIPK model) was proposed, in which the low-temperature sub-model consists of 19 low-temperature reaction classes and was constructed by analogy-based method, the high-temperature sub-model was adapted from the works of Cheng et al.. The predictions of HUST-MIPK model are in good agreement with the present low-temperature IDTs, high-temperature O 2 /CO 2 atmosphere IDTs, and the literature experimental data. The negative temperature coefficient (NTC) behavior was not observed in the temperature range from 790 to 910 K in the present RCM experiments, but was observed for methyl propyl ketone (MPK) and diethyl ketone (DEK) under similar conditions. The low-temperature chemistry of three pentanone isomers (MIPK, MPK, and DEK) was compared using the flux and sensitivity analysis. The comparison of the experimental high-temperature IDTs between O 2 /CO 2 and O 2 /Ar atmospheres indicates the IDTs of MIPK under O 2 /CO 2 atmosphere are longer than those under O 2 /Ar atmosphere at 1 bar, and the effects of CO 2 are almost independent of the pressure. The physical and chemical effects of CO 2 on the ignition were studied in detail.