Experimental Research On Combustion Characteristics Of Low NO_x Burner For Oil Steam Injection Boiler

The heavy oil resource in china is abundant.With the maturity of heavy oil thermal exploitation technology,the number of fuel injection steam boilers has increased rapidly.In recent years,China has paid more and more attention to environmental protection,and the boiler emission standard has become stricter.For another,domestic oil-fired steam injection boiler burners are mainly imported,so the development of domestic low-NOx injection boiler burners is significant.A low NOx swirl burner suitable for fuel injection steam boiler was designed,and the combustion performance and nitrogen oxide emissions of low NOx burners were studied through the numerical calculation of the cold state,combustion experiment and industrial application experiment.It was found by numerical calculation that the influence of the swirling intensity of the primary wind blade on the aerodynamic field is small,but as the angle of the primary wind blade increases,the maximum return velocity increases.To extend the residence time of the oil mist in the recirculation zone,the angle of the primary wind blade was selected 35°.The secondary wind swirling intensity has a great influence on the aerodynamic field.As the secondary wind swirling intensity increased,the length and diameter of the recirculation zone both increased,but with the secondary wind blade angle was larger,the high speed region near the wall surface appeared,which was easy to cause the flame burned the tube,and the angle of the secondary wind blade was considered to be 35°.The influence of different wind ratios on the aerodynamic field was mainly reflected in the decrease of the proportion of the recirculation zone as the proportion of the OFA increases,and the maximum reflow velocity decreased from-8 m/s to-6 m/s.meanwhile when the proportion of the burnout wind increased,the wind speed of the near wall surface is reduced to a certain extent.The intermediate wind had a great influence on the recirculation zone.When the speed of the wind was above 60m/s,the recirculation zone is destroyed.This paper also verifieed the correctness of numerical calculations through cold state test.It was found that when the excess air ratio?reduced from 1.15 to 1.05,it achieved a reduction in NOx emissions,but with?decreased continuely,combustion instability and black smoke occurred.The intermediate jet wind delayed the mixing of the primary and secondary air,thereby reducing the oxygen content and temperature in the initial stage of combustion,and reducing the NOx content in the flue gas.However,the jet wind speed excessively destoried the flow field structure in the furnace,and caused combustion instability.With a 50m/s intermediate jet wind,it reduced the NOx content of flue gas by 10%.In addition,the water spray in the combustion zone had a certain effect on reducing the combustion temperature,and the effect of flue gas recirculation to reduce NOx emissions was obvious.The low NOx burner achieved to reduce the NOx in the flue gas from the initial 891mg/m³?converted to??O₂?=3.5%?to 508mg/m³?converted to??O₂?=3.5%?.Denitration efficiency reached 42.9%.According to the combustion test,the industrial burner was modified,and reduced the NOx emission by 29.4%.