Numerical and experimental investigations on turbulent combustion fields generated by large-scale submerged combustion vaporizer burners with water spray equipment

In order to meet the increasing demand of natural gas worldwide, the development of large-scale and environmentally friendly submerged combustion vaporizer (SCV) burners, which can vaporize massive liquefied natural gas (LNG), is strongly desired. One of good solutions to reduce nitrogen oxides emissions is the installation of water spray system into the burner. In this study, a large-scale SCV burner equipped with a water spray system is developed by numerical simulations of cold flows and experiments of small-scale SCV burners, and the characteristics of the nitric oxide (NO) and carbon monoxide (CO) emissions are investigated. In addition, Large Eddy Simulations (LESs) of turbulent combustion fields generated by the large-scale SCV burner are performed, and the validity is assessed by comparing with the experiments. As a combustion model, the five-dimensional non-adiabatic flamelet progress variable (5D-NA-FPV) approach, which can take into account the effects of various heat losses including latent heats by the evaporation of sprayed water, conduction, and radiation of hot burned gases, is newly introduced. The experimental results show that NO emissions for a large-scale SCV burner decrease to less than 50 ppm corrected at O2 = 5% as the water spray amount increases, but that CO emissions increase due to the heat loss by water evaporation. Also, the LES/5D-NA-FPV adequately captures the effects of the water spray amount on the NO and CO reactions, which suggests that it could be a powerful tool for an optimal design of large-scale SCV burners.