Numerical Simulation Of LNG Submerged-Combustion Vaporizer

In recent years,the value of liquefied natural gas has been widespread concerned by the society.Special storage and gasification equipments,which are LNG-related equipments, have also become a hot academic.LNG submerged-combustion vaporizer,mainly being used for peak load system,is a kind of heat exchanger with high thermal efficiency.Although the shell and tube heat exchanger has been further discussed,the sturcture and simulation of LNG submerged-combustion vaporizer is rarely reported.LNG submerged-combustion vaporizer differs from ordinary heat transfer in many aspects.For example,the process of heat transfer and mixing between the gas-jet and water,the disturbance of gas-jet to water,the structure and arrangement of heat exchange tubes,the flow and gasification of LNG in pipes,and the low rate of gas at exit,etc.In order to provide a reference to achieve practical application in engineering and design better,the flow and heat transfer process must be known and more reasonable structures and parameters must be discussed.In this paper,LNG vaporizer's combustion chamber,shell-side flow field,and fluid flow and heat transfer process of tube were simulated.The parameters of structure and operating were discussed to improve water turbulence effects and the rate of gas in tube.Then an integrated simulation was done using the optimizing parameters.The prime task and the conclusion are as following:The physical and numerical models of a LNG vaporizer's combustion chamber, shell-side flow field,as well as the fluid flow and heat transfer process of tube-side were established.Turbulent flow was described with standard k-εmodel,the combustion of combustion chamber components was simulated with finite-rate model,the couple calculation between the gas phase and the water phase was calculated with discrete phase model, multiphase flow was handled with mixture model,and the UDF function was added to source term to express the process of vaporization.Through numerical simulation of combustion chamber,flow field,temperature field,and the analysis of the gas component,which could provide a reference for the operation and design of next process,were got.The results of numerical simulation of shell-side showed that the Reynolds number of gas-jet had a great impact on the flow of shell-side water;and the shell-side water's average velocity and turbulence kinetic energy increased along with the Reynolds number increasing; tubes and nozzles with the same location was more conducive to the water's turbulence around tubes;tubes and wall influenced the shell-side flow field significantly.By the numerical simulation of tube-side,the distribution of flow field,temperature field and pressure field in the tube were got,and they could explain the flow and heat transfer process in the tube.And the factors which affected the rate of gas were got.Through the integrated numerical simulation of vaporizer,the results showed that the optimization of shell and tube's parameters had a great impact on the thermal efficiency and the rate of gas.