(144c) Experimental Investigation of the Effects of Tower Motion on Random Packing Efficiency

Efforts to monetize offshore gas resources have led to increased interest in floating processing facilities such as Floating LNG.  These facilities face technical challenges, including the proper design of process equipment to achieve desired performance under moving conditions.  In particular, tilt and motions imposed on a fractionation column can have a significant impact on product specifications due to reduced packing efficiency.  An improved understanding of motion impacts will assist the analysis of tower performance and enable fit-for-purpose designs to deliver reliable performance and minimize overall cost of floating production facilities. 

The current understanding of towers in motion allows only very basic design rules and the safety factor for packing height in literature varies widely.  Therefore, an experimental test program was conducted with a 1-m diameter test column to quantify packing hydraulics and mass transfer performance with simulated wave motion.  The test column contained random packing as it is typically preferred in amine gas treating and high pressure distillation towers for gas processing plants.  The mass transfer efficiency was measured with carbon dioxide absorption into caustic solution to obtain the effective wetted packing area for mass transfer. 

This paper will present experimental results for the impact of design and operating parameters (such as packed bed height, tilt angle, etc.) on the mass transfer performance of a modern random packing.  These results are also analyzed in terms of dry/under-wetted packing volume and vapor channeling in order to obtain a model that may be used for packed tower design.

The design of floating processing facilities requires a good understanding of the impact of motion on fractionation tower performance.  Unlike previous studies, which have largely been limited to hydraulic measurements of liquid maldistribution, theoretical predictions of performance, and/or small scale experiments, this paper will present mass transfer measurements with a modern, industrial scale random packing.  The improved understanding of packing performance under motion will facilitate tower designs that meet process functional requirements and minimize overall cost of floating production facilities.