FCC沉降器内部空间压力分布的数值模拟

采用Fluent流体计算软件对1.40 Mt/a催化裂化装置沉降器内部空间的油气流动状况进行了数值模拟，湍流模型是Reynolds应力输运模型，重点考察内部压力场的分布规律。沉降器计算几何模型是沉降器原型尺寸，包括内部的两级旋风分离器、内置提升管等。计算结果表明沉降器空间的压力按数值大小划分为三个区，一级旋风分离器（粗旋）和提升管反应器内的高压区，沉降器空间的中压区和二级旋风分离器（顶旋）内的低压区。其中提升管出口的压力最高，而顶旋料腿内部压力是整个沉降器压力的最低部分。沉降器内部的压力分布决定了各部分油气和蒸汽的流动路线、速度，以及料腿的料封问题。

NUMERICAL SIMULATION OF PRESSURE DISTRIBUTION PATTERN IN FCC DISENGAGER

The pressure distribution inside disengager determines the flow path of the gas and steam, feed speed and the height of material seal leg. To well understand the distribution pattern inside the FCC disengager, a numerical simulation of oil gas flow in a full-size disengager of fluid catalytic cracking unit (FCCU) was conducted by Fluent 6.2 software. The Reynolds stress transport turbulence model (RSM) was used. The commercial disengager of 1.40 Mt/a FCCU was used as the computational geometry model, including the two stage separators and the built-in riser. The simulation results indicate that the space in the disengager can be divided into three regions according to the pressure: high-pressure region inside the primary cyclone separator and riser; medium-pressure region inside the disengager and low-pressure zone inside the secondary cyclone separators. The pressure inside the diplegs of the secondary cyclone separator is the lowest in the disengager, so it is necessary to establish an effective material seal of catalyst particles to balance the negative pressure and lock the air for nesting, or will cause the phenomenon of air leakage.