The Research On Adjustable Burner Of Stepped Firing In Recirculation Zones

Although China is abundant in coal, the supply of coal is still in short. This requires theindustrial boilers not only keep the stability of ignition and combustion, but also enhancethe fuel adaptability. This paper is a study of a burner which can meet the conditions above,we also hope this burner can solve a lot of industrial problems in the practice.The mechanism of stepped firing in recirculation zones is a kind of effective way toregulate the stability of the combustion. But, for different kinds of fuel, the boiler canproduce different contour diagrams of temperature and flow, so we need to turn the burnerand make it in best state. In order to reach the purpose of stable combustion, we change theslitting bluff-body burner’angle to match different kinds of fuel.First of all, this paper introduces the stable ignition technology from domestic to foreign,and analyzes the advantages and disadvantages of the technology. Secondly, the steppedfiring in recirculation zones of slitting bluff-body burner has been introduced, and also tellthe advantages and disadvantages, which has lay the foundation for the discussing of theignition skills below.And then, we use the lumped-parameter method to analyze the mechanism of steppedfiring in recirculation zones, obtain the mathematical expressions of the related factors,which have a influence on stable ignition. Through these expressions, we can know thesefactors how to take the influence on combustion. Finally, combustion performances of theslitting bluff-body burner’ angle with different angles are simulated in Fluent under thesame initial conditions, from which we obtain the contour diagrams of temperature andflow, the velocity vector.From the simulation results, we can analyze that the flame stabilization is the worst ofall when the angle of slitting bluff-body burner is40°.The recirculation zone’ length andflow is very small, which can’t guarantee the mainstream of pulverized coal and therecirculation zone have full of energy and momentum exchange, the temperature of furnaceis not stable, even can not guarantee the stable combustion of chamber. But when the angleof slitting bluff-body burner is80°,the obstruction of slitting bluff-body burner becomes around0.6. Through the contour diagrams of velocity, we can clearly see the tworecirculation zones and the wake recovery zone. The small amount of first-fired fuel-airflow is igniting in the two recirculation zones, and releasing the full heat, to form a stableflame igniting the main flow. It can be concluded that the obstruction of slitting bluff-bodyburner best in0.55to0.65.