Chemical-looping combustion (CLC) is a novel and promising option for several applications including carbon capture (CC), fuel reforming, H 2 generation, etc. Previous studies demonstrated the feasibility of performing CLC in a novel rotary design with micro-channel structures. In the reactor, a solid wheel rotates between the fuel and air streams at the reactor inlet, and depleted air and product streams at exit. The rotary wheel consists of a large number of micro-channels with oxygen carriers (OC) coated on the inner surface of the channel walls. In the CC application, the OC oxidizes the fuel while the channel is in the fuel zone to generate undiluted CO 2 , and is regenerated while the channel is in the air zone. In this two-part series, the effect of the reactor design parameters is evaluated and its performance with different oxygen carriers (OC) is compared. In Part 1, the design objectives and criteria are specified and the key parameters controlling the reactor performance are identified. The fundamental effect of the OC  Corresponding author. Tel.: +1 617 253 2295. E-mail address: ghoniem@mit.edu (A.F. Ghoniem) 2 characteristics, the design parameters, and the operating conditions are studied. The design procedures are presented on the basis of the relative importance of each parameter, enabling a systematic methodology of selecting the design parameters and the operating conditions with different OCs. Part 2 presents the application of the methodology to the designs with the three commonly used OCs, i.e., nickel, copper, and iron, and compares the simulated performances of the designs.

Reactive absorber columns Sulfuric acid and nitric acid production Sensitivity analysis and parametric studies NO, NO 2 and SO 2 removal a b s t r a c t Oxy-coal combustion has great potential as one of the major CO 2 capture technologies for power generation from coal. In oxy-coal combustion, the oxygen source is a high concentration oxygen stream and the product flue gas consists primarily of CO 2 and H 2 O with contaminants like nitrogen oxides (NO X ), sulfur oxides (SO X ) and non-condensable gases like argon, oxygen and nitrogen. NO X and SO X removal can be achieved via traditional selective catalytic reduction (SCR) and flue gas desulfurization (FGD). These traditional methods however result in relatively high capital cost and energy requirement and face complex material handling challenges. White et al. proposed a different approach to NO X /SO X removal based on the nitric acid and lead-chamber chemistry process (White et al., 2010). This two-column design utilizes an intermediate and a high-pressure reactive absorption column connected in series to respectively remove SO X and NO X from the high CO 2 -concentration flue gas. In this study, we propose a modification to this two-column process that achieves the complete removal of SO X and NO X from the CO 2 stream in a single column. We demonstrate by means of pressure sensitivity studies that this new design can meet the same separation targets as the two-column process in fewer column stages and half the feed water requirement by exploiting the pressure dependence of the rate determining NO oxidation reaction. Furthermore, we make use of parametric studies to analyze the dependence of NO X /SO X removal on key design and operating parameters for the proposed system: pressure, vapor hold-upper stage and water flow rate. Results show that the process is strongly pressure dependent, with a 3-order of magnitude decrease in required residence time when the operating pressure is varied from 4 bars to 30 bars. Vapor holdup volume and feed water flow rate have a significant impact on NO X /SO X removal up to a point -about 20 m 3 and 2 kg/s respectively for the case analyzed. Beyond these values, column performance shows substantially less sensitivity to increasing holdup volume or water flow rate. The analysis presented in this paper also shows that recycling bottoms liquid can reduce the feed water requirement by up to 40% without significantly affecting the exit gas purity.

Abstract

The emergence of technologies in which rare-earth elements provide critical functionality has increased the demand for these materials, with important implications for supply security. Recycling provides an option for mitigating supply risk and for creating economic value from the resale of recovered materials. While solvent extraction is a proven technology for rare-earth recovery and separation, its application often requires extensive trial-and-error experimentation to estimate parameter values and determine experimental design configurations. We describe a modeling strategy based on Gibbs energy minimization that incorporates parameter estimation for required thermodynamic properties as well as process design for solvent extraction and illustrate its applicability to rare earths separation. Visualization analysis during parameter estimation revealed a linear relationship between the standard enthalpies of the extractant and respective organo-metal complexes, analogous to the additivity principle for predicting molar volumes of organic compounds. Establishing this relationship reduced the size of the parameter estimation problem and yielded good agreement between model predictions and reported equilibrium extraction data, validating the property estimates for the organic phase species. Design exploration and optimization results map the space of feasible solvent extraction column configurations and identify the set of optimal design parameter values that meet recovery and purity targets.

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