Numerical Simulation Study Of Radiation Chamber In Methane-steam Reforming Furnace

Methane-steam reforming furnace plays a core role in the production of hydrogen,the radiation chamber providing the space where heat exchanging between furnace and tubes and reforming reaction taking place,is an indispensable part of the hydrogen production process.As the tubes are vulnerable under the serious operation condition of high temperature,it is urgent to attract more attention to the research on the radiation chamber.There are many limitations on the traditional investigation methods,but by adopting Computational Fluid Dynamics method,this paper simulates the reaction processes happened in the furnace to reach the goal of providing necessary information on the design and optimization of radiation chamber in the context of inadequate parameters.This paper describes the mass transportation,heat transportation and momentum transportation processes in the tubes and furnace by creating appropriate mathematics models,the results offer detailed data on further understanding of temperature,velocity distribution of flue gas and heat exchange between tube skin.At last,temperature distribution of flue gas in the furnace and heat flux of the tube skin are improved to be more uniform with a little structure modification of the radiation chamber.In the two burners simplified geometric furnace model,the turbulent model is standard k-? model,and radiation model is P1 model which is applicable to big geometric model with the advantage of small amount of calculation.Computing the furnace model with finite rate/eddy dissipation model,ED model,EDC model and species transport model,PDF transport model,and the numerical simulation results of five combustion models show that the ideal model is EDC,which is more realistic though its disadvantage of large amount of calculation.The reaction tube model is approximated to plug flow reactor model and the calculation results of the plug flow reactor model meet the design requirements.Finally the tube model and the furnace model couple with each other by iterating until obtaining constant temperature profile of outer tube skin,and the temperature distribution is regarded as the boundary condition of the whole domain furnace model.Furnace simulation results show that high temperature flue gas mainly gathers in the upper part of the radiation chamber center,the temperature of flue gas in the rest of the radiation chamber is mostly uniform.The heat flux of reaction tube and its surrounding flue gas temperature are in positive correlation,the higher flue gas temperature,the higher heat flux.The heat flux of the upper part of the central two rows reaction tubes keeps at a higher level,and then declines along the tube length.The heat flux of the first and fourth row reaction tubes is on the decline on the whole along the tube length.Furnace structure optimization results reveal that the special structure of furnace plays a decisive role in the distribution of flue gas.The new structure scheme can improve the uniformity of the temperature distribution of the flue gas and largely reduce the highest temperature of flue gas,at the same time,the distribution of heat flux of the first row reaction tubes also become more uniform.