Study On Gas-solid Flow Characteristics In A300MW Circulating Fluidized Bed Boiler

As a high efficient and clean combustion technology, circulating fluidized bed boiler gets a lot of attention and has developed rapidly in recent years with developing towards large-scale. The design of pant-leg structure for circulating fluidized bed (CFB) boiler is a huge advance in the large-scale process, which can send the second wind into the middle of boiler successfully. However, it also brings the "bed overturn" problem leads by the difference of material flow in each leg.A unit of visible cold experimental apparatus of CFB boiler is set up using the300MW pant-leg structure CFB boiler as the original model. Get a characteristic curve after experiment on air distribution plate and preesure drop of bed material. Then the cold state experiment of "overturn beds" is carried out. According to the experiment data, it could be found that the underlying cause of "overturn beds" is the different pressure drop characteristics of the bed materials on each other sides of furnace in the pent-leg CFB. The difference of pressure drop between each leg must be bigger when the velocity is lower. Effective control on pressure drop can prevent overturn of CFB boiler.The computational fluid dynamics fluent software is employed to investigate numerically the flow with Eulerian multiphase flow model. In comparison with a variety of operation condition by changing the velocity of wind and thickness of bed material, figure out that the flow in the boiler can be more steady if the first wind velocity and bed material are less, and the time for overturning bed is longer.