Experimental investigation of submerged flame in packed bed porous media burner fueled by low heating value producer gas

• Producer gas (PG) was derived from biomass using gasification process.
• PG fueled two layer porous medium burner for hot air production was developed.
• Submerged combustion was achieved for wide range of equivalence ratio 0.33 < Φ < 0.71.
• Low CO emission below 10 ppm was achieved.
• Hot air power output of 7 kWth was achieved with overall system efficiency of 54%.

Combustion inefficiencies and high pollutants emissions keep motivating researchers to enhance combustion technology. Producer gas fuel from biomass gasification with its low heating value and high CO content requires a special combustor design for efficient burning. Porous media burner (PMB) has been widely investigated and proven to be well suited for low heating value fuels lean combustion. This study aims at performance investigation of PMB fueled by producer gas from biomass gasification. A downdraft gasifier system along with a PMB burner and heat recovery unit has been developed. The PMB comprises two layers of 10 mm and 20 mm diameter upper and lower alumina spheres packed, respectively. With PG heating value of about 5 MJ/m3, lean to ultra lean stable combustion was achieved with equivalence ratios (Φ) in the range of 0.33 < Φ < 0.71. Combustion layer temperature was in the range of 1300–1550 K. The lowest recorded emissions from the PMB were 6 ppm and 230 ppm for CO and NOx respectively. The heat recovered from the burner was utilized in hot air production of 7 kWth that can be used for drying process in small industries. Maximum heat recovery heat exchanger effectiveness was about 93% with overall system efficiency of 54%.