HCN oxidation in an O2/CO2 atmosphere: An experimental and kinetic modeling study

NOx formation and reduction mechanisms in staged O2/CO2 combustion

Coal combustion with O 2 /CO 2 is promising because of its easy CO 2 recovery, extremely low NO x emission, and high desulfurization efficiency However, there exist many unknowns concerning in-furnace desulfurization in O 2 /CO 2 pulverized coal combustion, which is much different from that in conventional coal combustion Research on CaSO 4 decomposition aimed at desulfurization in O 2 /CO 2 pulverized coal combustion is also necessary to investigate the desulfurization behaviors The kinetics of desulfurization and CaSO 4 decomposition were examined in atmospheres of high CO 2 and SO 2 concentrations The characteristics and mechanisms of desulfurization in an O 2 /CO 2 pulverized coal combustion system were clarified by combining experimental results and modeling with the kinetics obtained by us The effects of sorbent type, residence time, and so on were investigated It has been identified that the system desulfurization efficiency in O 2 /CO 2 pulverized coal combustion is increased to about four to six times as high as that of conventional pulverized coal combustion mainly attributed to the following: (1) practical residence time of SO 2 is extended and SO 2 is enriched inside furnace owing to flue gas recirculation; (2) CaSO 4 decomposition is inhibited because of a high SO 2 concentration Their contributions were quantitatively clarified as follows: below 1450 K, the former contributes above two-thirds, whereas above 1500 K, the latter contributes above two-thirds to the overall increase in desulfurization efficiency The system desulfurization efficiency in O 2 /CO 2 pulverized coal combustion maintains a high value in a wide range of temperature and particle residence time These results of a high system desulfurization efficiency, in addition to an extremely low conversion ratio from fuel-N to exhausted NO and an easy CO 2 recovery without CO 2 separation process, make simultaneous control of CO 2 /NO x /SO x possible in O 2 /CO 2 pulverized coal combustion It can be concluded that O 2 /CO 2 pulverized coal combustion is a promising advanced coal combustion technology for the protection of global environment

Drastic SOx Removal and Influences of Various Factors in O2/CO2 Pulverized Coal Combustion System

An experimental parametric study of gas reburning under conditions of interest for oxy-fuel combustion

A study of formation and destruction of NO in adiabatic laminar premixed flames of CH4 + O2 mixtures diluted with N2 or Ar (with various dilution ratios) in a range of equivalence ratios at atmospheric pressure is presented. Nitric oxide was seeded into the flames using mixtures of diluent gas + 100 ppm of NO. The heat flux method was employed to measure adiabatic burning velocities of these flames. Nitric oxide concentrations in the post-flame zone at 10, 15 and 20 mm above the burner surface were measured using probe sampling. Burning velocities and NO concentrations simulated using a previously developed chemical kinetic mechanism were compared with the experimental results. The conversion ratio of NO seeded into the flames was determined. The kinetic mechanism accurately predicts burning velocities over the range of equivalence ratios and NO conversion in the rich flames. Significant discrepancies between measured and calculated NO conversion in the lean and near-stoichiometric flames were observed and discussed.

Formation and destruction of nitric oxide in methane flames doped with NO at atmospheric pressure

The effect of initial CO 2 concentration on NO destruction and regeneration was investigated as part of our ongoing research on NO emission from CO 2 recycled coal combustion, which could realize easy CO 2 recovery and drastic N() reduction simultaneously. Experiments were carried out in a flat flame burner for CH 4 /O 2 /Ar/NO/CO 2 flame at various excess oxygen ratios (from 0.6 to 1.2) and CO 2 concentrations (from 0% to 48%). It was found that CO 2 has a pronounced negative effect on the destruction of NO under fuel-rich condition. In contrast, under fuel- lean condition, the effect of CO 2 becomes smaller even at high CO 2 concentrations. Kinetic modeling showed that a large part of NO is regenerated through the reaction N+CO 2 = NO+CO at high CO 2 concentrations. The effect of CO 2 is not so significant under fuel-lean condition because this reaction is no longer competitive with other NO formation reactions in this case.

Bo Feng

Papers

NO Destruction and Regeneration in CO2 Enriched CH4 Flame. (A Fundamental Study on CO2 Recycled Coal Combustion)