The Optimization Study Of An In-line Burning Heater Of Shell Claus Off-gas Treating Process

The in-line burning heater of a natural gas purification SCOT process features an outflow with temperature higher than the optimum temperature of hydrogenation catalysts downstream.A better outflow temperature can be achieved by reducing the consumption of fuel gas.First,a simplified model based on chemical reaction kinetics is established by using CHEMKIN-PRO.Inlets of fuel flow,mixing flow of air and steam,claus tail gas flow are studied to achieve optimal ranges of flow rates.Second,three optimized inlet flow rates are achieved using response surface methodology,which satisfy the requirement of outflow in temperature and hydrogen concentration.At last,a numerical combustion model is established by using ANSYS FLUENT-16.0 to study the changes of flow field due to various fuel inlet and air/steam inlet flow rates.A comparison of flow fields before and after optimization is studied.The study shows that the combustion of fuel and air/steam are incomplete,the chemical equilibrium determines the temperature and hydrogen concentration of outflow.Air flow rate has the greatest effect of the temperature,so does fuel flow rate with the hydrogen concentration.A more intensive incomplete combustion will lead to an upstream shifting of the higher temperature area,and an extension of flame.The optimized condition features a reduction of out flow temperature from 555.15 K to498.72 K,and hydrogen mole fraction from 1.96% to 1.95%,while 34.73% flow rates of fuel is reduced.The condition of outflow satisfies the target temperature of catalysts downstream.Energy conservation is achieved with less consumption of fuel gas.