Numerical simulation on liquefied natural gas submerged combustion vaporizer

To predict the natural gas outlet temperature of a liquefied natural gas (LNG) submerged combustion vaporizer(SCV), this paper establishes a complete model for the numerical computation of the fluid flow and heat transfer in the whole SCV system, including the combustion chamber, down comer and LNG heat exchanger. For the combustion chamber, weighted-sum gray gas model (WSGGM) is used to calculate the gas absorption coefficient and DO model is used to solve RTE. The flow and heat transfer behavior is then obtained considering radiation and convection. For the LNG heat exchanger, a segmentation treatment is used for the coiled tube because of the drastically changing fluid properties. The two-phase fluid model is used to deal with the gas-liquid two-phase flow and heat transfer process for the shell-side and the total heat transfer coefficient is then calculated. The tube-side and shell-side heat transfer coefficients are well consistent with the results of previous studies. When the shell-side inlet gas temperature varies within the range of 500-700 ℃, the outlet gas temperature and the average water bath temperature slightly increase and the turbulent kinetic energy and heat transfer coefficient slightly decrease. Under the practical operation conditions, the LNG outlet temperature maintains at 15 ℃ or so, which can meet the production requirement.