Influence of sloshing on the performance of a trough plate redistributor

A packed tower is one of the components of offshore floating liquefied natural gas (FLNG) storage and unloading device. In order to ensure the good redistribution performance of a gas–liquid redistributor in the packed tower, we developed a set of experimental devices which can realize different sloshing conditions and different bias current incoming forms and a corresponding numerical calculation model by combining hydraulic experiments with hydromechanic numerical simulation. Then, the simulation results were verified by using the experimental results, and simulation results and experimental results were analyzed. Finally, the performance of the traditional trough plate redistributor was investigated under the working conditions of quiescence, sloshing and different bias current incoming. And the following research results were obtained. First, under the working condition of quiescence, the liquid flow rate of different sprinkling points on the traditional trough plate redistributor is basically the same and the uniform distribution is presented with the non-uniformity in the order of 10–2. Second, the reason for the uniform redistribution deterioration of the redistributor is mainly the liquid level difference caused by the liquid migration. Third, under the working conditions of quiescence, rolling and pitching, the uniform distribution of trough plate redistributor is rarely affected by the change of bias current degree of the incoming liquid. Under the working condition of sloshing 5°, the non-uniformity difference of the overall orifice flow rate between the liquid incoming in the whole area and that in 2/3 area is less than 5%. Fourth, the non-uniformity of the overall orifice flow rate in the trough plate redistributor is more affected by rolling and pitching. The non-uniformity of the overall orifice flow rate rises to over 0.5 under the working condition of rolling 5° and over 0.3 in pitching 5°. It is indicated that under the working condition of sloshing 5°, the uniform distribution of trough plate redistributor is poor not only in the case of whole area liquid incoming but also in the case of bias current incoming, and it is affected more by sea conditions. In conclusion, the traditional trough plate redistributor is poorly adaptive to the sloshing at sea. Keywords: FLNG, Packed tower, Trough plate redistributor, Rolling, Pitching, Bias current condition, Numerical simulation, Non-uniformity