Experimental Investigation on a Newly Designed Combustor for LCV Gas

Abstract

Air blown gasification of biomass is one of the most promising and efficient ways to use alternative energy sources like organic matters from waste and biomass for producing LCV (Low Calorific Value) gas. This fuel is best used in highly efficient gas turbines (or combined cycles). The section Thermal Power Engineering of Delft University of Technology operates a 1.5 MW pressurized fluidized bed gasification rig, including a hot gas cleaning unit with the ability to test pressurized combustors designed and optimized for LCV gas combustion. In this paper, the results of six combustion experiments with the 1 MW non-swirling TUD (Technical University Delft) combustor are presented and compared with the results of experiments performed with a 1.0 MW swirling combustor designed by ALSTOM Power UK. The primary and cooling airflow of the TUD combustor can be altered independently for optimization purposes. The experiments were performed at 3.5 and 5.0 bara and stable combustion was accomplished with gas of heating values (HHV) ranging from 2.7 to 3.8 MJ/m3n. Combustion efficiencies of the TUD combustor were well above 99.9% and emissions of CO were within the EU standards, except for one experiment where Minphyl as catalyst was added to the gasifier fuel. A high percentage of primary air was used in this experiment. Emissions of NO were outside the EU standards (100 ppm) for four of the six experiments because of the high fuel bound nitrogen (FBN) concentrations in the fuel gas. The FBN conversion rate ranged from 98% to 39% for FBN concentrations ranging from 238 to 2238 ppm.