Alien Registration- Sorensen, Eva (Rumford, Oxford County)

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Optimal design of hybrid distillation-membrane processes based on a superstructure approach

Considerable effort is currently being put towards process intensification to design more sustainable and energy-efficient processes. Hybrid distillation-membrane processes are prime examples of such intensified processes. In this work, different strategies are presented for how to handle the complexity of the membrane network of the hybrid process in terms of initialisation and convergence for simulation and optimisation. A superstructure approach for optimisation of membrane networks within hybrid processes is presented and verified. The energy consumption and economic performance of a hybrid distillation-pervaporation process, as well as that of the corresponding extractive distillation process, to separate a minimum-boiling azeotropic mixture are compared for different feed compositions. The impact of membrane properties and cost is also briefly considered. The results show that the total heat duty for the hybrid process is always lower than that of the extractive process for the system considered, confirming that the hybrid process is more energy efficient. In terms of total annualised cost, however, the hybrid process is found to be more economically attractive at lower feed compositions, while the extractive process is preferred for higher compositions

Recent advances and future perspectives on more sustainable and energy efficient distillation processes

Distillation has held a very strong position in the chemical process industries for well over a century, and has, as a separation method, been around for millennia. The process can be designed directly without the need for experimentation unlike other novel separation processes, and distillation is a standard part of any undergraduate curriculum. So why the ongoing interest in this separation dinosaur? Due to distillation’s significant importance in industry, and its associated high energy requirements and thereby contribution to global warming, considerable effort is still needed to make the process more energy efficient, as well as to consider other heating sources beyond traditional fossil fuels. In this work, we will outline the most significant methods currently considered for energy efficiency of distillation, and provide an overview of where we may be heading as a discipline in our quest for a more sustainable chemical engineering future. We will argue that significant improvements have already been made, but more is still required by both industry and legislators. We need to consider a future without the use of fossil fuel-based feedstock or energy sources and switch towards renewable sources, and our future graduates need to be adequately prepared for such a future

Single- and multi-objective optimisation of hybrid distillation-pervaporation and dividing wall column structures

The separation of azeotropic mixtures is often energy intensive, thus process intensification (PI) becomes an attractive route to enhance energy efficiency. Two of the most commonly used separation intensifications are dividing wall columns and hybrid distillation-membrane processes. In this work, three typical hybrid distillation structures, distillation followed by pervaporation (D-P), pervaporation followed by distillation (P-D), and distillation followed by pervaporation then by distillation (D-P-D), are considered and compared with a hybrid dividing wall column (H-DWC) structure, which is a highly integrated process combining a dividing wall column and a pervaporation membrane network. The four structures are compared by both single-objective and multi-objective optimisation. It is shown that the D-P-D and H-DWC structures require significantly lower total annualized costs than the other two designs due to requiring smaller membrane area, as these two structures use the membrane only to help the mixture composition cross the azeotropic point

Editorial

This special issue of Chemical Engineering Research and Design features selected papers from the international conference on Distillation & Absorption held in Friedrichshafenon 14–17 September 2014. The conference was organised byDECHEMA and ProcessNet’s Subject Division on Fluid Separations on behalf of the European Federation of Chemical Engineering (EFCE) and its Working Party on Fluid Separations.The first conference in this series took place in Brighton in the UK in 1960. The conferences are now held every 4 years, last in Eindhoven in 2010, and showcase the newest findings and research in distillation and absorption technology

On the apparent dispersion coefficient of the equilibrium dispersion model: An asymptotic analysis

To model chromatography, researchers have developed several approaches. These cover a broad range of applications and, depending on the assumptions adopted, have different levels of accuracy. In general, the most suitable modelling approach is the simplest that can describe a process with the desired accuracy. A model that often meets this criterion is the equilibrium dispersion model (EDM). This features one mass balance equation per analyte, including an axial dispersion term, and assumes the analyte concentrations in the mobile and stationary phases to be in local equilibrium. To account for the finite mass transfer rate between the phases, the model employs an apparent dispersion coefficient. Two expressions are available for this coefficient, one being used much more frequently than the other. In this paper, we aimed to clarify which one should be favoured. A desirable feature of simple models is that they can be derived from more general ones with appropriate physical assumptions and rigorous mathematical methods. Thus, to answer our research question, we derived the EDM from the more general pore diffusion model (POR), using an asymptotic method. The expression obtained for the apparent dispersion coefficient does agree with one of the two reported in the literature – the less frequently used. To test the validity of this expression, we simulated elution profiles using the two versions of the EDM and compared the results against those from the POR model. The simulations were conducted in the range where the POR and EDM models should be essentially equivalent, their results confirming the outcome of the asymptotic analysis. This work offers a solid theoretical grounding for the EDM, clarifies which formulation of the model is correct, and provides usable applicability conditions for the model

Hydrodynamic Characterization of Phase Separation in Devices with Microfabricated Capillaries

Capillary microseparators have been gaining interest in downstream unit operations, especially for pharmaceutical, space, and nuclear applications, offering efficient separation of two-phase flows. In this work, a detailed analysis of the dynamics of gas–liquid separation at the single meniscus level helped to formulate a model to map the operability region of microseparation devices. A water–nitrogen segmented flow was separated in a microfabricated silicon-glass device, with a main channel (width, W = 600 μm; height, H = 120 μm) leading into an array of 276 capillaries (100 μm long; width = 5 μm facing the main channel and 25 μm facing the liquid outlet), on both sides of the channel. At optimal pressure differences, the wetting phase (water) flowed through the capillaries into the liquid outlet, whereas the nonwetting phase (nitrogen) flowed past the capillaries into the gas outlet. A high-speed imaging methodology aided by computational analysis was used to quantify the length of the liquid slugs and their positions in the separation zone. It was observed that during stable separation, the position of the leading edge of the liquid slugs (advancing meniscus), which became stationary in the separation zone, was dependent only on the outlet pressure difference. The trailing edge of the liquid slugs (receding meniscus) approached the advancing meniscus at a constant speed, thus leading to a linear decrease of the liquid slug length. Close to the liquid-to-gas breakthrough point, that is, when water exited through the gas outlet, the advancing meniscus was no longer stationary, and the slug lengths decreased exponentially. The rates of decrease of the liquid slug length during separation were accurately estimated by the model, and the calculated liquid-to-gas breakthrough pressures agreed with experimental measurements

Towards a digital twin for analytical HPLC

Digital twins for industrial process development are quickly gaining popularity in the pharmaceutical industry as an effective alternative to expensive and time-consuming physical experiments. This work describes the digital model element of a digital twin of High-Performance Liquid Chromatography (HPLC). The model is based on a mechanistic model implemented in gPROMS ModelBuilder and integrated into the MATLAB environment. Unlike other models reported in the literature, our model comprises a more accurate prediction of the injection profile and can predict the elution behaviour for a wide range of HPLC conditions given a reduced number of experiments. The model is compared against experimental data performed to separate a mixture of eight small drug molecules on a C18 column, in gradient elution mode, and under nine different operative conditions (i.e. 3 temperatures × 3 solvent gradient). We will show that by considering only two isotherm parameters for each molecule, the digital model can accurately predict the retention behaviour of the eight analytes. Furthermore, it facilitates HPLC in-silico method development, showcased here via method time minimization through a dynamic solvent strength gradient. The proposed model is intended to be integrated into a digital twin architecture for offline decision support and real-time optimization

Hard facts, soft measures: Gender, quality and inequality debates in Danish film and television in the 2010s

This article investigates discussions about gender, quality and equality in Danish film and television in the 2010s. Contrary to Sweden, where gender diversity has been part of public debate and formal screen policy since the 2000s, there was little discussion of gender in the Danish screen industry until the Danish Film Institute (DFI) began focusing on diversity as a priority area before the Film Strategy for 015–18. The article analyses how both DFI and industry players have continuously argued against gender quotas, instead opting for soft measures such as ‘gender declarations’ and initiatives to raise awareness