High Efficient gasification in a Low-tar biomass (LTB) gasifier by Coupling with Inclined Nozzle and Combustor for Tar Reduction

Abstract A novel design of low-tar biomass (LTB) gasifier with an inclined nozzle in the pyrolysis zone and a separate combustor installed inside the partial oxidation zone has been designed, developed and tested, while maintaining an extremely low tar in the producer gas. The design process was focused on a swirling flow created by an inclined nozzle which allows a good mixing between gasifying air and pyrolysis gases in the pyrolysis zone. A separate combustor which has large annular and reverse flow zones with the help of swirl flow. The resulted mixing gases has sucked inside in to the combustor and burning the mixture with the help of induced thermal cracking in the partial oxidation zone. At an equivalence ratio of 0.35, the gasifier had a thermal capacity at 23.8 kW and a maximum cold gas efficiency of 93.1%. Using wood chips with a moisture content of 9–34%, the LTB gasifier had generated a producer gas at 7.4-27.14 mg/Nm3 with a lower heating value of 4.57–5.11 MJ/Nm3. The resulted producer gas can be piped directly to the internal combustion engine or a gas turbine at small to medium scale power plant in remote rural off-grid areas.