Practical residue curve map analysis applied to solvent recovery in non-ideal binary mixtures by batch distillation processes

Batch distillation inherent advantages has initiated recent search for process feasibility rules enabling the separation of azeotropic or difficult zeotropic binary mixtures thanks to the addition of an entrainer. A systematic procedure enabling to find suitable process and eventually suitable entrainer for the separation of zeotropic or azeotropic binary mixture is described. It brings together into practical use batch distillation process feasibility rules, chemical affinity insight and thermodynamic data analysis available in the literature. The procedure has been implemented in a wizard computer tool and is illustrated on the separation of the water – acetonitrile binary homoazeotrope. Through this tool, all possible 224 feasibility rules and 326 batch distillation sequence processes are checked systematically for each entrainer

Preliminary Design of Reactive Distillation Columns

A procedure that combines feasibility analysis, synthesis and design of reactive distillation columns is introduced. The main interest of this methodology lies on a progressive introduction of the process complexity. From minimal information concerning the physicochemical properties of the system, three steps lead to the design of the unit and the specification of its operating conditions. Most of the methodology exploits and enriches approaches found in the literature. Each step is described and our contribution is underlined. Its application is currently limited to equilibrium reactive systems where degree of freedom is equal to 2 or less than 2. This methodology which provides a reliable initialization point for the optimization of the process has been applied with success to different synthesis. The production of methyl-tert-butyl-ether (MTBE) and methyl acetate are presented as examples

Results from a pilot plant using un-promoted potassium carbonate for carbon capture

A pilot plant facility has been designed and built to trial potassium carbonate solvent technology for carbon capture under a range of conditions. The rig is capable of capturing 4 - 10 kg/hr of CO2 from 30 - 55 kg/hr of an air-CO2 mixture, with different packings. A series of trials have been completed with a range of solvent concentrations from 20 wt% to 30 wt% potassium carbonate. The experimental holdup, solvent loading and absorber temperatures have been matched with rate-based simulations in Aspen Plus® software

Flow Regime Transition in Countercurrent Packed Column Monitored by ECT

Vertical packed columns are widely used in absorption, stripping and distillation processes. Flooding will occur in the vertical packed columns as a result of excessive liquid accumulation, which reduces mass transfer efficiency and causes a large pressure drop. Pressure drop measurements are typically used as the hydrodynamic parameter for predicting flooding. They are, however, only indicative of the occurrence of transition of the flow regime across the packed column. They offer limited spatial information to mass transfer packed column operators and designers. In this work, a new method using Electrical Capacitance Tomography (ECT) is implemented for the first time so that real-time flow regime monitoring at different vertical positions is achieved in a countercurrent packed bed column using ECT. Two normalisation methods are implemented to monitor the transition from pre-loading to flooding in a column of 200 mm diameter, 1200 mm height filled with plastic structured packing. Liquid distribution in the column can be qualitatively visualised via reconstructed ECT images. A flooding index is implemented to quantitatively indicate the progression of local flooding. In experiments, the degree of local flooding is quantified at various gas flow rates and locations of ECT sensor. ECT images were compared with pressure drop and visual observation. The experimental results demonstrate that ECT is capable of monitoring liquid distribution, identifying flow regime transitions and predicting local flooding.Comment: This is a draft paper of an article submitted to CEJ - Chemical Engineering Journa

Evaluation of Dynamic Models of Distillation Columns with Emphasis on the Initial Response

The flow dynamics (tray hydraulics) are of key importance for the initial dynamic response of distillation columns. The most important parameters are the liquid holdup, the liquid hydraulic time constant and the vapor constant representing the initial effect of a change in vapor flow on liquid flow. In the paper we present methods for determining these parameters experimentally, and compare the results with estimates from available correlations such as the Francis Weir formula

Process simulation and analysis of carbon capture with an aqueous mixture of ionic liquid and monoethanolamine solvent

This study investigated the prospect of using aqueous mixture of 1-butylpyridinium tetrafluoroborate ([Bpy][BF4]) ionic liquid (IL) and monoethanolamine (MEA) as solvent in post-combustion CO2 capture (PCC) process. This is done by analysis of the process through modelling and simulation. In literature, reported PCC models with a mixture of IL and MEA solvent were developed using equilibrium-based mass transfer approach. In contrast, the model in this study is developed using rate-based mass transfer approach in Aspen Plus®. From the results, the mixed aqueous solvent with 5–30 wt% IL and 30 wt% MEA showed 7%–9% and 12%–27% less specific regeneration energy and solvent circulation rate respectively compared to commonly used 30 wt% MEA solvent. It is concluded that the IL concentration (wt%) in the solvent blend have significant impact on specific regeneration energy and solvent circulation rate. This study is a starting point for further research on technical and economic analysis of PCC process with aqueous blend of IL and MEA as solvent