Experimental investigation of reaction behavior between carbon dioxide and liquid sodium

Reaction behavior of carbon dioxide (CO2) with a liquid sodium pool was experimentally investigated to understand the consequences of boundary tube failure in a sodium-CO2 heat exchanger. In this study, two kinds of experiments were carried out to investigate the reaction behavior. In one experiment, about 1-5g of liquid sodium pool were poured into flowing CO2 to obtain the information mainly about the thermo-chemical conditions to initiate the reaction and the chemical constituents of reaction products. During the experiment, visual observation was made using video-camera and the temperature change of the sodium pool and near the surface was measured by thermocouples. The experimental parameters were the sodium pool diameter, the initial temperature of sodium and CO2, the CO2 flow direction against pool surface, and the initial moisture concentration in CO2. The solid products of sodium-CO2 reaction were sampled and analyzed by X-ray diffraction (XRD), energy dispersion X-ray analysis (EDX), total organic carbon analysis (TOC), and chemical analysis. The reaction gas products were also sampled and analyzed by gas chromatography. In the other experiment. CO2 was injected into about 200 g of liquid sodium pool to simulate the boundary failure in the sodium-CO2 heat exchanger. The CO2 was fed through a helical coil-type tube dipped into the pool to adjust the temperature to the sodium pool temperature, and injected upward into the pool from a pool bottom using a nozzle attached at the end-side of the tube. The experimental parameters were the initial temperature of sodium, the diameter of the nozzle, the flow rate and the injection time of CO2. The temperature change of sodium pool and the cover gas was measured by thermocouples during the experiment, and the reaction products were sampled and analyzed by the same manner as in the former experiments after the experiment. From these experiments, it became clear that the exothermic reaction occurred above a threshold temperature, and useful and indispensable information such as the resulting temperature and pressure rise and the behavior of solid reaction products in the pool was obtained to evaluate the consequences of boundary tube failure incident in a sodium-CO2 heat exchanger. (C) 2010 Elsevier B.V. All rights reserved.