【作者】 王磊；

【导师】 潘家祯；

【作者基本信息】 华东理工大学 ， 化工过程机械， 2014， 硕士

【摘要】 下排气旋风分离器利用气固两相流的高速旋转,在离心力的作用下将固体微粒从气流中分离出来,其在循环流化床锅炉的气固分离技术中已经得到广泛的应用,具有结构简单,维护方便、压力损失低,易于布置和支捧等优点。由于旋风分离器中的含尘气流属于三维强旋转湍流,伴随着两相分离运动,而且涉及到气固两相相互作用以及凝聚、吸附和静电等许多复杂物理现象,使得理论研究遇到很大困难,理论进展缓慢。传统的设计是依据己知的操作条件和所需的性能指标,凭借经验先选定旋风分离器的结构形式及尺寸,设计过程具有很大的盲目性。本文针对某煤矿自备电厂一台型号为UG-35/3.82-M35的循环流化床煤泥锅炉,其使用的下排气旋风分离器实际运行时分离效率偏低,飞灰可燃物较多,造成较大的锅炉热效率损失,对锅炉的下排气旋风分离器设计了改造方案,并针对改造方案选择了合适的模拟方案,运用计算流体力学软件FLUENT模拟研究了改造前后下排气旋风分离器的气相流场速度分布、压力分布、固体颗粒的运动轨迹及下排气旋风分离器的分级效率和总分离效率等参数。数值模拟的结果验证了设计改造方案的可行性,本文还根据数值模拟情况对改造方案进行了优化。按照模拟验证的改造方案,对该锅炉的下排气旋风分离器进行了工程改造,并通过对具体的实际运行情况进行实验测定,发现模拟结果与改造结果吻合良好,很好的验证了CFD数值模拟计算在下排气旋风分离器改造中的优越性,同时改造后的下排气旋风分离器实际运行中分离效率大幅度提高,捕集的固体微粒粒度变细,提高了循环流化床的物料循环倍率,降低了飞灰含炭量,提高了燃料的利用率,也提高了锅炉运行效率,改造后效果显著。更多还原

【Abstract】 In the cyclone separator with downward exhaust gas, depending on the centrifugal force generated by rotation movement of gas-solid phase fluid, the solid particles are separated from the air phase. With the advantages of simple structure, easy maintenance, low pressure loss, easy to decorate and branch, it is widely applied in the flue gas desulfurization technology with circulating fluidized bed boiler and circulating fluidized bed. Because of the strong three-dimensional rotating turbulence of gas-solid phase in the cyclone separator, accompanied by two separate movement, and many complicated physical phenomena such as condensation, adsorption, and electrostatic interaction, it makes the theoretical research great difficult. The traditional design relies on the experience to select the structure of cyclone separator and size,and the design process has a great deal of blindness.In this paper, a UG-35/3.82-M35circulating fluidized bed coal boiler in operation is studied, which has a low separation efficiency, heavy fly ash and larger thermal loss. The cyclone separator is reconstructed. The Computational Fluid Dynamics commercial software FLUENT is used to study the cyclone separator with downward exhaust pipe with and without modification. Based on the modification, the appropriate numerical simulation method is chosen. The data of gas phase velocity field, pressure field, particle trajectory and particle sizing efficiency, total separation efficiency of the cyclone separator can be obtained by the numerical simulation. According to the simulation results, the appropriate retrofit scheme is presented. Through the practical application in engineering, it is found that the simulation results agree well with those obtained in the experiment. It is also verified that the CFD numerical simulation is available in the modification of exhaust cyclone separator.更多还原