Liquid-fueled high-performance burner utilizing a coarse porous matrix

Abstract

In this study, a kerosene-fueled premixed burner system with a thick and large pore-sized (“coarse”) porous matrix was developed to achieve less-soot stable premixed combustion with variable combustion loads, i.e., turn-down ratio, TDR, defined as the ratio between the maximum and minimum loads. The present burner system mainly consists of the thick and coarse porous matrix made by packed ceramic balls of 8 mm-diameter, which acts as a vaporizer, mixer, and flame holder. The liquid fuel is fed into the porous matrix along with air. As the air and vaporized fuel are supplied toward the top-end (surface) of the porous matrix, a premixed flame is formed at this surface. Benefits of the adopted porous matrix include reduced wettability of the liquid fuel to pores of the porous matrix, which prevents its direct supply to the flame, promotes vaporization and mixing, and functions as a flame holder, allowing the flame to be sustained within the porous matrix. Combustion experiments were then carried out under various equivalence ratios (φ) between 0.47 and 1.34, and temperature measurement was conducted to evaluate the vaporization capability within the porous matrix. The experimental results confirmed that the quasi-steady and stable premixed combustion across the entire surface of the porous matrix throughout the burning event was successfully achieved under all φ values considered in this study. A simplified (one-dimensional) analytical model was developed to examine achievable range of TDR. It was found that the expected achievable TDR was higher than the value for the conventional spray combustion technology (∼ 6). Thus, the present burner system with a thick and coarse porous matrix was effective for attaining stable premixed combustion and a high TDR.