Numerical Simulation And Research On Combustion And NO_x Formation In Precalciner

The precalciner is an important thermal equipment in the new dry process cement production process.It is also a process node in the pre-decomposition kiln technology.The raw material in the preheater,the carried flue gas in the rotary kiln,the third wind,the pulverized coal and the coal feed gas are all required to enter the precalciner.This aspect directly reflects the complexity of the operation of the precalciner,besides that,Whether it works well with them.The NO generated in the precalciner is relatively large in the NOx emissions of cement production pollutants,so it is very important significantly to reduce the NO production in the precalciner.The precalciner has third wind,kiln gas and coal and the second wind,and their imports are mostly concentrated in the lower part of the precalciner,which resulted in the decomposition of the local flow field complex.In addition,the combustion of fuel in the precalciner and the release of carbon dioxide from the decomposition of the raw material will also enhance the complexity of the flow field in the precalciner.This also implies that there are more variables in the process of generating NO in the precalciner.In this paper,it summarize the research on combustion and NO generation in the previous research on precalciner.The results show that with the increase of the third wind speed,the generation of NO in the precalciner is getting higher and higher.With the increase of the third wind temperature,the amount of NO produced in the precalciner And the amount of NO produced in the precalciner is the highest at the third wind,and the NO content in the precalciner of the third wind of third-order oxygen-oxygen content at the exit of the precalciner is not much different.In this paper,the different installation orientation of the burner of the precalciner is studied.It is found that the larger the angle between the centerline of the burner and the YZ face,the larger the confluence area is formed in the pyramid of the precalciner.When the angle is 51°and 68°,the coal feed airflow will form a circulation zone in the crushing section in the precalciner,and the circulation area formed at 68°is larger.The installation angle of the burner has a higher fuel burning intensity and a higher NO concentration when the angle of YZ is 17°.The angle of 51°is not conducive to fuel combustion,the angle of about 34°,with good fuel combustion strength and lower NO concentration.In this paper,the graded burning of the precalciner is studied.It is found that the lower the oxygen content of the kiln gas in the main combustion zone is higher when the coal ratio is 1:9,When the ratio of coal to coal is 2:8,the oxygen content in the main combustion zone is higher when the oxygen content of the kiln is 0.3%.The NO content in the main combustion zone of the precalciner is the highest when the oxygen content of the kiln is 0.6% When the ratio of coal to coal in coal briquette is 3:7,the oxygen content in the precalciner is higher when the oxygen content of kiln is 0.6%,and the amount of NO content in the precalciner In the combustion main combustion area is higher,when the oxygen content of the kiln is 0.6%,in the proportion of three kinds of the burner in different kiln oxygen,the precalciner NO content in the exit of precalciner are similar.The addition of raw material to the precalciner will affect the fuel combustion strength to affect the decomposition of NO production.In this paper,the main process parameters of the third wind of the precalciner,the installation orientation of the burner of the precalciner and the graded burning of the precalciner are carried out.The research on the NO generation of the precalciner provides more experimental samples for the technical field of the pre-decomposition kiln technology,Simultaneously,Which provides a practical reference value for the design and reconstruction of the precalciner type of energy-saving and emission reduction of the precalciner design.