Biomass gasification : combustion of gas mixtures

Abstract

The work presented in this study is primarily experimental and covers the following two main areas; gasification of biomass and combustion of gas mixtures.

The work on biomass gasification includes the design of a laboratory scale gasification unit and integration with a gas engine with the necessary equipment for gas cooling and filtration. The performance of both the gasifier and the integrated system is documented in three enclosed papers.

The work on gas combustion covers mainly experimental studies of jet diffusion flames with respect to NOx formation and emission, flame geometry and thermal radiation, flame stability and laminar burning velocities. The gas mixtures investigated are low calorific value (LCV) gases, typically from biomass gasification, and mixtures of natural gas and LCV gas. From the experimental data found in this study new correlations for prediction of NOx emission, flame geometry, thermal radiation and laminar burning velocity are suggested.

The novelty of this work is mainly related to the investigation of combustion characteristics of gas mixtures. Few data has previously been published on combustion characteristics of gas mixtures similar as found from biomass gasification. For mixtures of LCV gases and natural gas no previous publications have been found which covers the topics presented in this study. The mixed-fuel operation of a gas engine presented in this thesis also represents a novelty compared to documented operation of engines with product gas from biomass gasification.