高低并列式重油催化裂化汽提器挡板的结构优化

催化裂化汽提器的汽提效果对装置产品收率、能耗和长周期平稳高效运行有重要影响。高效的汽提器不仅可以提高轻质油品的收率、改善产品分布，更能降低再生器的烧焦负荷、减少催化剂的水热失活。当前常用的汽提器主要呈现两种结构形式，其一为填料结构汽提器，该汽提器空间利用率和汽提效率很高，但填料容易被焦块堵塞，不易清理，因而不适宜于重油催化裂化装置；另一种汽提器为挡板结构汽提器，该汽提器结构简单、汽提效率高、运行周期长，应用非常广泛。开孔挡板结构汽提器作为挡板结构汽提器中应用最广一种，其挡板区内气固流动特征及流场分布特点目前还研究较少，同时受实验条件和测量方法的限制，工业尺度开孔挡板结构汽提器更是鲜有研究报道。本研究将运用双流体模型结合分段曳力模型对一套工业规模催化裂化装置的锥环形挡板汽提器进行模拟，考察其流场特点和气固流体力学行为。发现模拟所得床层密度与工业实测值能较好吻合。模拟结果表明：挡板区内蒸汽并不严格呈“S”形穿过各块挡板向上流动，相邻环形挡板0.85

The baffle structure optimization for high and low side-by-side type RFCC stripper

A stripper is an important part of a fluid catalytic cracking (FCC) plant, affecting products yields, energy consumption and long-term run of the entire unit greatly. A high-efficiency stripper increases the light oil yield and improves the product distribution, moreover, it also reduces the coke-burning load of regenerator and decreases the hydrothermal deactivation of catalyst. Strippers widely used in fluid catalytic cracking units can be categorized into the packing stripper and the baffle stripper. The former owns the advantages of high stripping efficiency and better space utilization, but is not suitable for residue fluid catalytic cracking (RFCC) units, because the grid is easily blocked up with coke and difficultly cleaned. Therefore, the latter is widely used in RFCC units, benefited from simple structure, high stripping efficiency and long-term operation. Hydrodynamic characteristics of gas phase and solid phase in a commercial stripper with perforated baffle is rarely studied, subject to severe experiment condition and poor measurement methods. In this work, hydrodynamic behavior of the steam and particles in a commercial-scale fluid catalytic cracking stripper is investigated numerically, by using two-fluid model with a drag model which divides the flow region into four parts: dese, sub-dense, dilute and ultra-dilute. The mean bed density from the simulation is in good agreement with the value registered in a commercial unit. Calculation results demonstrate that strict S-shape flow of steam does not exist in stripper. Steam short circuit between the neighboring annular baffles or conical baffles occurs in the region of 0.85