(131f) CFD Simulation of Tower Internals for Application in Large Scale Tower Design

Modern distillation technology insists to achieve scale effect through large-scale of key equipment. To solve problems existing in large scale tower, such as high liquid-level gradient and uneven liquid-vapor distribution, CFD technology was used to study the fluid flowing packings or plate internals. Study results could be used to optimize internal structure and operating conditions for improving the status of fluid flow in tower. In this paper, the vapor and liquid flow of distributors, Structured packings and trays were simulated using CFD technology to solve the following engineering technical problems. (1) Liquid distribution: With the increase of the ratio of tower diameter and packing diameter and the decrease of radial dispersion coefficient of packing layer, it would be more difficult for packings to translate poor initial distribution into natural flow distribution. Therefore, the initial distribution of fluid was very important. CFD was used to calculate distributor structure, geometric dimension and hole-opening density and size, in order to achieve homogeneous distribution of liquid. (2) Gas distribution: With the development of new low pressure drop packing, gas was hardly distributed naturally in packing bed. Gas distributor in large scale tower needed to meet greater demands, such as good homogeneous distribution capacity, little hydraulic resistance, small volume, the ability to effectively prevent the liquid entrainment, difficulty to hold liquid and coke, etc. The application of CFD to simulate gas flow and distribution in gas distributor optimized the design of gas distributor. (3) Gradient of liquid level: Gradient of liquid level was much higher on large scale tray than on the small one, which affected gas-liquid contact and reduced the tray efficiency. CFD simulation study optimized the structure of tray and valves to improve gas-liquid flow.