Reaction Kinetics for a Novel Flue Gas Cleaning Technology

This paper studies the kinetics of the reaction between NaClO3, FeSO4, and NaHSO3, which can potentially be used as an alternative to the conventional lime-limestone process for flue gas desulfurization. The key for the establishment of a kinetic model of the reaction is to find a way to determine concentrations of reactants or products during the reaction. The generation rate of Cl- during the reaction was monitored using a Dionex Series 4000i ion chromatograph. Based on the changes of Cl- concentrations at the designed initial reaction conditions, reaction orders for each reactant were derived. The reaction orders were determined to be 1.1 for NaClO3, 1.1 for FeSO4, and 1.4 for NaHSO3. The global rate coefficients of the reaction at temperatures ranging from 40 to 80 °C were determined. Furthermore, the preexponential factor and the activation energy in the empirical Arrhenius form of the reaction were derived from the relationship between temperature and its corresponding observed global rate coefficient

Effect of Applied Voltage on the Current Density of CO2 Electrolysis in High Temperature

Reductions in CO2 emission can be achieved directly through CO2 capture and storage (CCS), a method that is particularly effective when used with large CO2 emitters such as electrical power plants and iron and steel mills. Solid-oxide electrolysis presents an alternative means of reducing CO2 that can use some of the CO2 captured by CCS as a source of electrolysis. In addition, unused heat generated by steelmaking and through renewable sources (e.g., solar and wind) can be utilized for high-temperature electrolysis. This study investigated the effect of applying a high voltage of between 2.5 and 4.0 V to common electrolytic materials (YSZ and Pt), and found that although the initial current density of a new cell is very low, it increases drastically upon application of a high voltage. The results of FE-SEM observation revealed that the interface between the YSZ and Pt electrode moves into the YSZ by about 70 μm, and consists of a nano- and micro-porous structure that reduces the resistivity and gas diffusivity

Improvement on Heat Release Performance of Direct-contact Heat Exchanger Using Phase Change Material for Recovery of Low Temperature Exhaust Heat

Latent heat storage using a phase change material (PCM) is a promising method for utilizing the exhaust heat from steelworks. The purpose of this study was to improve the heat release performance of a direct-contact heat exchanger using a PCM and heat transfer oil (HTO). Erythritol (with a melting point of 391 K), which is a kind of sugar alcohol, was selected as a PCM. A vertical stainless steel cylinder with an inner diameter of 200 mm and height of 1400 mm was used as the heat storage unit (HSU). A ring-shaped injector with 18 holes positioned vertically downward was placed at the bottom of the HSU. Each hole in this injector had a diameter of 2.5 mm. We investigated the effects of the height of the PCM in the HSU, the HTO flow rate, and an increase in the number of injection-nozzle holes on the temperature effectiveness and heat exchange rate as indices of the heat release performances. As results, we found that an increase in the number of nozzle holes accelerated the uniform distribution of the HTO in the liquid PCM, prevented the HTO drift flow and adverse solidification of the PCM, and improved the heat release performance under the condition of a high HTO flow rate