| Building a clean,low-carbon,safe and efficient energy system is the overall requirement of energy system.Nitrogen oxides from fossil fuel combustion need to be treated effectively.Selective non-catalytic reduction denitration technology in thermal power industry.Selective non-catalytic reduction(SNCR)in the thermal power industry has low cost and strong adaptability to complex working conditions and is widely used.Study the reaction process of SNCR denitration technology,carry out numerical simulation,and explore methods to improve the denitrification efficiency of SNCR technology.It has important practical and engineering significance for energy saving,emission reduction and operation optimization.Among the many influencing factors such as reaction temperature,residence time,ammonia nitrogen molar ratio,and the mixing degree of reducing agent and flue gas,the mixing degree of reducing agent and flue gas has become the key to restricting the efficiency of SNCR denitration technology.With the help of computational fluid dynamics simulation software,the flue gas flow,heat and mass transfer and denitrification reaction in the furnace are numerically simulated,and the optimization scheme of pulsating jet reducing agent is proposed and UDF programming simulation is verified..In view of the importance of the influence of particle size distribution and velocity of reducing agent atomized droplets on the SNCR reaction process,the atomization characteristics of nozzles in the external space are numerically simulated,and the influence of the nozzle atomization characteristics on the injection characteristics of reducing agent droplets is obtained.The flow weighting of the reducing agent droplet information of pulsating injection in one cycle was obtained,and the particle size range was 10～100 μm and the average particle size was 32.17 μm,which provided a data basis for the numerical simulation study of pulsating jet denitration later..The numerical simulation of SNCR denitration scenario of furnace direct injection compares the distribution uniformity and denitration efficiency of fixed-speed injection and pulsating injection reducing agent,and it is found that the uniformity of reducing agent distribution can be increased from 0.272 to 0.359 compared with fixed-speed injection by pulsating injection,which is helpful to enhance the mixing of reducing agent and flue gas and improve the denitrification efficiency from 30.29%to 39.93%,when the reducing agent injection method adopts horizontal downward 45° The best ammonia distribution uniformity of 0.549 and the highest denitration efficiency of 58.13%can be obtained during pulsating injection,and the ammonia escape amount can be reduced accordingly,and the amount of reducing agent can be saved by 48%in terms of economy,which achieves the same denitration efficiency as fixed-speed injection.The SNCR denitration scenario of cyclone separator is numerically simulated,the factors affecting SNCR denitration efficiency inside the cyclone separator are analyzed,the flue gas residence time,pressure,velocity distribution,evaporation of reducing agent,ammonia distribution,ammonia nitrogen molar ratio,etc.are analyzed,and the optimization and improvement are carried out,and it is confirmed that the mixing degree of reducing agent and flue gas is enhanced due to its own strong swirl characteristics,which is similar to the pulsating injection enhancement characteristics,so pulsating injection is not suitable for cyclone separator scenarios,and an optimized spray gun layout site scheme is proposed.It was found that adding a spray gun at the top could increase the denitration efficiency from 59.03%to 70.03%.. |
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