Syngas combustion radiation profiling through spectrometry and DFCD processing techniques

Abstract

Experimental investigations of H2 and H2-enriched syngas flame radiation properties have been conducted through spectroscopic and DFCD (Digital Flame Colour Discrimination) techniques. A spectrograph was employed to quantify the emission profile of H2-based flames in the UV–visible spectral domain. The OH* emission was found to be the strongest in reactants with highest amount of H2. Further addition of CO and/or CO2 resulted in the reduction of OH* intensity with the addition of CO2 causing greater radical intensity-loss than that of CO. The decrease in OH* intensity is accompanied by a corresponding increase in the CO–O* broadband continuum in the short-wavelength domain of the visible spectrum. Such reduction of OH* along with increase in CO–O* intensity can be related to the endothermic reaction mechanism of CO + OH => CO2 + H, which describes the role of CO/CO2 addition in H2-enriched syngas flames. Comparison with direct imaging results provided additional credence to the effect of temperature reduction as flames with CO and/or CO2 additions resembled colourations closer to typical bluish premixed hydrocarbon flame. The employment of DFCD processing effectively characterised different syngas combustion conditions by combining aspects of digital flame colour intensities with spatial combustion distributions. This colour signal quantification method was shown to yield useful characterisation of H2-based flames, similar to the use of OH* chemiluminescence intensity variation from spectrometry. Also, DCFD analysis was able to depict the variances between the burning of different syngas gaseous constituents. Thus, useful image-based parameters related to the H2-based combustion can be derived and potentially applied as a practical monitoring and characterisation mean for syngas combustion.