Abstract
This work aims at supplying some fundamental insights of producer gas combustion and it is developed in the framework of the Green Deal project FRONTSH1P. To this aim, an in-house designed combustion chamber is directly coupled with a fluidized bed gasifier operated with wood packaging waste (e.g., disused pallets). Stable combustion process of producer gas mixtures, also at very-lean equivalence ratio (ER), is achieved and presented as an interesting insight against rising clean energy demand of industrial users with net-zero emissions. Thermal imaging based IR thermography technique is employed and time resolved flame images were viewed for flame temperature field and topology analysis at ER, φ ~ 0.20 - 0.85. The producer gas flame was quite stable and evenly distributed in the combustion chamber volume at ER = 0.85. Conversely, at lower ER, φ = 0.20, 0.43, the producer gas flame was strongly unstable due to several competing factors related to fluid dynamics and chemical kinetics. Finally, the re-stabilization opportunity of producer gas flame was revealed with the addition of a small share of methane gas ( ~ 5% CH4) at ER, φ ~ 0.20 0.25, which could represent a possible solution to achieve flame stability at ultra-lean combustion. Moreover, CO concentrations of 53 ppm and NOx emissions of 33 ppm were produced mainly due to fuel-prompt mechanism during ultra-lean combustion of producer gas mixture (G1) 3.70 % CH4, 18.16 % H2, 8.69 % CO2, 21.79 % CO, 7.26 % H2O, and 40.40 % N2.