Experimental Measurements and Mass Transfer/Reaction Modeling for an Industrial NO_x Absorption Process

Abstract

An industrial reactive separation process for NO x absorption into water and nitric acid in a world-scale mononitrobenzene (MNB) plant in Redcar, U.K., was investigated. Gas- and liquid-phase concentrations were measured in situ, while operating conditions such as temperature, pressure, and absorbent flow were varied. Furthermore, a comprehensive mass transfer/reaction model was developed in the process simulator Aspen Plus to simulate the absorption process, with the field process data used for validation. The model accurately predicted NO x removal from the gas (i.e., typically within 3.5% of the plant data). Other key findings are that the model successfully predicted changes in performance when key parameters such as temperature and pressure were varied. Furthermore, addition of a bleaching section was investigated, resulting in a significant improvement in NO x removal. Currently, the completed model is used to simulate existing and proposed NO x absorption systems and to develop new and innovative designs for NO x capture.

Incorporation of Oxidation Enhancement through Hydrogen Peroxide Addition into a Tested Mass Transfer/Reaction Model for an Industrial NOx Absorption Process

“…Model results were compared with plant data and the model was found to accurately predict NOx removal. Details on the collection and analysis of plant data, development of the model, including but not limited to reaction kinetics, vapor-liquid equilibria, and selection of mass transfer correlations can be found in the previous study (1). A schematic of the NOx absorption process is shown in Figure 1.…”

“…In the previous study (1), data from an operating NOx absorption system were collected and analyzed. A rate-based model was developed in Aspen Plus (utilizing the RateSep add-on) in an attempt to simulate plant conditions.…”

“…a model that accounts for reaction and mass transfer kinetics) was developed in the process simulator Aspen Plus and tested using data gathered at the world-scale Wilton mononitrobenzene plant in England (1). This model focused on the pressurized, counter-current absorption of NOx into water, resulting in the production of dilute (<20 wt%) nitric acid as a liquid product.…”

Pilot-scale Validation of the Modeling of NOx Reactive Absorption Process Using Aqueous Solutions Containing Nitric Acid and Hydrogen Peroxide

“…A rate-based unit operation model, in which rate-based mass and heat transfer calculations are possible, was selected in Aspen Plus ® . It was used by Loutet et al (2011) [19] for the modeling of the NO x absorption into water and nitric acid solutions using a packed column. The built model was validated by comparison of predicted values with experimental data from industrial-scale plant in Redcar, United Kingdom.…”

Dynamic Absorption Model for Off-Gas Separation

“…Stoichiometry is used to determine the rates for the other components in the reaction. The rate expression used for R9 is given by Loutet, et al 8 Dynamic Absorption Model for Off-Gas Separation 6…”