Research On Influence Aerodynamic And Temperature Field In Tangentially Fired Boiler With Burners Of Different Height-width Ratio

Tangent circle diameter is an important parameter of aerodynamic characteristics in the furnace of tangentially fired boiler, it has important influence on stable-combustion, furnace slagging, flue gas velocity and flue gas temperature deviation. actual tangent circle diameter is depended on some other parameters including imaginary tangent circle diameter, burners of height-width Ratio, ratios of total burner area and furnace sectional area, clearance rate of burners, momentum ratio of primary air and second air, tilting angle of burners and so on.In this thesis, with a 2008t/h and a 670t/h Tangentially Fired Boiler as prototype, mainly from burner combined jet and height-width ratio of burners cold modeling tests, numerical simulation are carried out to investigate the flow field in the burner zone.The flow velocity field in the burner zone of the 2008t/h tangentially fired boiler has been measured by hot-ball probe in 10 cases, the testing data are processed to obtain the relation of tangential circle diameter and layer number of jets. CFD commercial software is used to simulate the cases. The results show that with rising of height-width ratio of burners, the diameter of tangent circle get bigger and bigger. Tangent circle diameter will decrease accompany the increasing of clearance rate of burners with the same height-width ratio of burners. It can be artificially grouped for large height-width ratio of burners boiler, simulation shows that tangent circle diameter and dimensionless tangent circle diameter descend obviously in almost all the burner layer and average tangent circle diameter and dimensionless tangent circle diameter descend nearly 30%.The flow field,heat transfer and combustion process of a 670t/h tangentially fired boiler was simulated in 6 different cases to investigate the flow field in the burner zone. Simulation shows that with rising of height-width ratio of burners, jet trajectory and high-temperature region is gradually close to the wall, Static pressure difference on both sides of jet will non-linear increase accompany the increasing of height-width ratio of burners. Maximum diameter of airflow tangential circle and high temperature area close to the wall lead to slagging and high temperature corrosion easily when height-width ratio of burners exceeds 9; The size of tangential circle is moderate and the organization of combustion is reasonable when height-width ratio of burners fall into the range of 4 to 9; bad fullness degree of airflow in the boiler and flame concentration in the center of furnace as less than 4 in height-width ratio of burners, the advantage on organization of tangentially fired can not be played.Simulation results show that it can optimize aerodynamic field of burner region and decrease tangent circle diameter through the shutting down part of burners to minimize height-width ratio of burners for 2008t/h and 670t/h boiler. This research for design and operation of the boiler, and has important guiding significance. The results has instructional significance to the design of boiler and the operation of power plants.