Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.
In rich combustion, the natural gas is partially oxidized to produce syngas, a mixture which consists mainly of hydrogen and carbon monoxide. The goal of the work is to develop a computational model to predict the syngas composition, temperature and soot content. The method of reaction progress variables is applied to turbulent rich combustion modeling. The model handles both the gaseous and the solid phase transport. The gas phase model predicts the gaseous chemical species and temperature. The soot model quantifies the soot formation in the turbulent rich flame. The link between the two parts is the concentration of acetylene, which is considered to be the dominant soot precursor. The model is implemented in the CFX flow solver. The model predictions are compared with data from experiments on ultra rich combustion of natural gas by means of air enriched to 40% oxygen concentration at up to 3 bar and 300 kW. Good comparison was found between measurements and model predictions on carbon monoxide, hydrogen and the soot precursor acetylene. It can be concluded that the model provides reliable information on product gas concentrations as a result of ultra rich combustion of natural gas. The predicted soot concentrations were found to compare well to measurements in a rich flame as reported in the literature.