Effects Of Hydrogen Sulfide On Burning Characteristics Of Ammonia/Methane Blended Fuel

With the depletion of traditional fossil energy reserves and the deepening of social attention to environmental protection,people begin to look for new clean alternative energy.Ammonia gradually enters people’s field of vision because of its special advantages.As a carbon-free fuel,ammonia gas is completely burned and has no carbon dioxide emissions;and it is more convenient for liquefaction storage and transportation.Therefore,it is very important to use ammonia efficiently and cleanly,and to understand its combustion characteristics,such as laminar burning velocity,component concentration distribution,turbulent flame structure and velocity,etc.At present,an important aspect of the use of ammonia as a fuel is to mix and burn with other fuels.On the one hand,it can be used cleanly,and on the other hand,it can improve the efficiency of ammonia combustion.In the choice of blending fuel,introduce sour natural gas（methane+hydrogen sulfide）to explore the influence of hydrogen sulfide on combustion,so as to guide the direct utilization of natural gas fields and reduce the cost of desulfurization.In this paper,the burning velocity and turbulent flame structure of premixed laminar adiabatic combustion are used as the starting points to study the mixed combustion characteristics of ammonia and sour natural gas.In this paper,a laminar combustion test platform is built based on the heat flow method to obtain a one-dimensional non-tensile adiabatic flame.Under normal temperature and pressure,the laminar burning velocity of sour natural gas,ammonia/methane/hydrogen sulfide premixed gas was measured,and the effects of equivalent ratio,hydrogen sulfide mixing ratio,and ammonia mixing ratio on combustion speed were systematically studied.influences.Using the optimized combustion mechanism of hydrogen sulfide and ammonia,the PREMIX module of Chemkin PRO is used to simulate the flame speed,the sensitivity factors of 10 key elementary reactions,the flame temperature and the distribution of main free radicals.The results show that the combined mechanism can predict the laminar burning velocity of gas more accurately,increasing the ratio of hydrogen sulfide or ammonia will reduce the laminar burning velocity,and the velocity peak appears at the equivalent ratio?=1.05.The addition of hydrogen sulfide will reduce the generation rate of H and OH radical concentration,and increase the SH and CH₃ radical concentration in the flame.The reaction that affects the combustion changes under different equivalence ratios,but H+O₂<=>O+OH It has the largest positive sensitivity factor under any working conditions,and it increases with the increase of the equivalence ratio,which is the main elementary reaction that promotes flame combustion.Aiming at the turbulent combustion characteristics of mixed gas,this paper uses planar laser induced fluorescence PLIF technology to study,including OH radicals in turbulent flames,flame front and turbulent burning velocity.The averaging process of the captured flame transient images shows that the OH fluorescence signal intensity is the strongest and the turbulent combustion is the strongest near the equivalence ratio?=1.0.Increasing the ratio of hydrogen sulfide to ammonia in the fuel gas,the OH fluorescence signal decreased significantly,and the width of the central unburned area also increased.At the same time,the equivalent ratio and blending ratio also affect the turbulence velocity.Increasing the proportion of hydrogen sulfide or ammonia gas increases the surface area of the flame front,reduces the intensity of turbulent combustion,and reduces the speed;and compared with laminar combustion,the turbulent velocity decreases more significantly.In the rich combustion area,increasing the equivalence ratio will also lead to a decrease in the intensity of turbulent combustion,and thus a decrease in turbulent velocity.