Boil-off gas handling for LNG-carriers with a low-swirl burner

Abstract

Wärtsilä is looking into a new technology for boil-off gas handling. The technology chosen for further research is a low-swirl burner. This burner has shown promising NOx emission results which is a problem inside the shipping industry. The system is a combined high/low-swirl burner that could handle both premixed- and none-premixed mixture. The objective for the project is to find a correlation between swirl-number and flame shape. This has been done using algebraic equations and images of the flame. Burner design was unchangeable during this thesis thus the selection of swirl-numbers was limited. Experiment was conducted at Wärtsilä Moss in large scale. A high-speed camera analyzation was intended but due to uncontrollable factors a thermal camera had to be used. This thesis has discovered the optimal swirl-numbers for the given design to achieve the characteristic low-swirl flame shape. The correlation between swirl-number and flame shape is discovered for the combined high/low-swirl burner.