裤衩腿型循环流化床炉膛的翻床实验

Experimental study of the bed Inventory overturn in pant-legs furnace of CFB boiler

大型循环流化床(CFB)锅炉设计中广泛采用裤衩腿型的炉膛结构,炉膛内的翻床往往会造成停机事故.根据Glicksman的Scaling-Low模化准则,以具有裤衩腿结构的300MW CFB锅炉炉膛为原型,设计并建立了CFB冷态实验台.采用带通孔的中隔墙控制横向物料流动的高度和流通面积,设计了裤衩腿型炉膛内的翻床实验.动态的压力和风量测量结果表明,两侧炉膛内物料流动不对称导致了上部存在的物料横向流动,是发生翻床的根本原因;发生翻床的必要条件是固体物料产生的床压降足以控制单侧炉膛总压降的变化趋势;当炉膛上部横向通流截面平均高度降低或横向通流截面积减小时,两侧炉膛存料量的变化速率都会减缓.

The pant-legs structure is widely used in furnace design of large scale CFB boiler.The bed inventory overturn in furnace usually causes shutdown accident.Based on the Scaling-Low proposed by Glicksman,the geometric size of a 300MW CFB boiler was scaled down,and a bench-scale CFB rig was built up to study the lateral solid flow in the pant-legs CFB riser.The across area and average height of the lateral solid flow were adjusted by a partition wall with a number of slots.The changes of bed pressures and air flow rates were recorded.The experimental results show that the hydrodynamic asymmetry between both sides of the furnace is the essential cause of bed inventory overturn.The prerequisite of bed inventory overturn is a dominate portion of the pressure drop caused by the bed inventory in the total pressure drop in furnace.The process of bed inventory overturn slows down when the across area and average height of lateral solid flow decreases.