Performance of a pilot scale biomass gasification and producer gas combustion system using feedstock with controlled nitrogen content

This study is focused on the effects of nitrogen content in biomass feedstock on the producer gas composition and the flue gas NOx emissions from a pilot-scale gasification and combustion system. Biomass gasification has the potential to produce carbon negative energy by using renewable resources. The greenhouse gases emitted by burning fossil fuels have to be reduced, and biomass gasification is one of the means to achieving this. When the biomass-derived gas is burned, NOx emissions are a critical factor that can limit the use of the system. The government regulations limit the amount of NOx that can be emitted into the atmosphere. These emission regulations are becoming more stringent every year. Hence it is imperative to design combustion systems that can produce low NOx emissions without compromising the intended purpose for heat and power generation. This work is aimed at helping with the design of a low NOx burner by conducting experimental investigations on an existing burner. In this study, tests were conducted in a pilot-scale fluidized bed gasifier using biomass feedstock with different nitrogen contents. The producer gas from the gasifier undergoes a gas cleaning phase before its combustion in a burner. Fuel NOx and thermal NOx contributed to the total NOx formation in the burner. The main precursor to fuel NOx is ammonia in the producer gas. Ammonia and tars were collected from the producer gas using IEA (International Energy Agency) tar protocol and analyzed using spectrophotometer and GC-FID (Gas chromatograph-flame ionization detector), respectively. The producer gas and the exhaust flue gas were analyzed using a micro gas chromatograph (Micro-GC). The