Innate lymphoid cells (ILC) expressing the transcription factor RORγt induce the postnatal formation of intestinal lymphoid follicles and regulate intestinal homeostasis. RORγt⁺ ILC express the aryl ...hydrocarbon receptor (AhR), a highly conserved, ligand-inducible transcription factor believed to control adaptation of multicellular organisms to environmental challenges. We show that AhR is required for the postnatal expansion of intestinal RORγt⁺ ILC and the formation of intestinal lymphoid follicles. AhR activity within RORγt⁺ ILC could be induced by dietary ligands such as those contained in vegetables of the family Brasskaceae. AhR-deficient mice were highly susceptible to infection with Citrobacter rodentium, a mouse model for attaching and effacing infections. Our results establish a molecular link between nutrients and the formation of immune system components required to maintain intestinal homeostasis and resistance to infections.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Internally heat-integrated distillation column (HIDiC) is the most radical approach of a heat pump design, making efficient use of internal heat-integration: the rectifying section of a distillation ...column operating at a higher pressure becomes the heat source, while the stripping part of the column acts as a heat sink. Remarkably, a HIDIC can bring up to 70% energy savings compared to conventional distillation columns. This is highly appealing regarding the fact that distillation is one of the most energy intensive operations in the chemical process industry accounting for over 40% of the energy usage. This review paper describes the latest developments concerning this promising but difficult to implement process intensification technology, covering all the major aspects related to the working principle, thermodynamic analysis, potential energy savings, various design configurations and construction options (ranging from inter-coupled or concentric columns, shell and tube and plate–fin heat exchanger columns to SuperHIDiC), design optimization, process control and operation issues, as well as pilot-scale and potential industrial applications. Further advancement, i.e., development of HIDiC technology for multi-component mixture separations is an extremely challenging research topic, especially when HIDiC becomes associated with other technologies such as dividing-wall column (DWC) or reactive distillation (RD).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The advantages of biodiesel as an alternative fuel and the problems involved in its manufacturing are outlined. The pros and cons of making biodiesel via fatty acid esterification using solid acid ...catalysts are examined. The main problem is finding a suitable catalyst that is active, selective, and stable under the process conditions. Various solid acids (zeolites, ion‐exchange resins, and mixed metal oxides) are screened as catalysts in the esterification of dodecanoic acid with 2‐ethylhexanol, 1‐propanol, and methanol at 130–180 °C. The most promising candidate is found to be sulphated zirconia. The catalyst's stability towards thermal decomposition and leaching is tested and the effects of the surface composition and structure on the catalytic activity are discussed.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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► A review on current industrial dividing wall column applications. ► A review on current research activities in the area of dividing wall column technology. ► An analysis of current ...dividing wall columns for azeotropic, extractive and reactive distillation. ► A review on control strategies for dividing wall columns.
In spite of being an energy intensive process, distillation remains the most important separation method in the chemical process industry. Especially for the separation of mixtures with three or more components, the total energy requirement and the capital cost are very high. In this respect, dividing wall columns (DWCs) represent a very promising technology allowing a significant energy requirement reduction. This article reviews current industrial applications of DWCs and related research activities, including column configuration, design, modelling and control issues. Furthermore, the application of DWCs for azeotropic, extractive and reactive distillation is highlighted.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
► Bioethanol dehydration by advanced distillation technologies. ► Extractive and azeotropic distillation in dividing-wall column. ► Optimal designs by sequential quadratic programming (SQP). ► Energy ...savings of 10–20% with less equipment units.
The industrial production of anhydrous bioethanol requires energy demanding distillation steps to overcome the azeotropic behavior of the ethanol–water mixture. In spite of the recent developments in pervaporation and adsorption with molecular sieves, the large scale production is still dominated by extractive and azeotropic distillation as the separation technology of choice.
This study proposes novel distillation technologies for enhanced bioethanol dehydration, by extending the use of dividing-wall columns (DWC) to energy efficient extractive distillation (ED) and azeotropic distillation (AD). Notably, DWC is one of the best examples of proven process intensification technology in distillation, as it allows significantly lower investment and operating costs while also reducing the equipment and carbon footprint.
For both ED and AD cases a classic sequence of two distillation columns and the alternative based on DWC are optimized using the state of the art sequential quadratic programming (SQP) method. A mixture of 85mol.% ethanol is dehydrated using ethylene glycol and n-pentane as mass separating agents in an extractive and azeotropic distillation setup, respectively. The results of the rigorous simulations performed in Aspen Plus show that energy savings of 10–20% are possible for the novel process intensification alternatives based on DWC, while using less equipment units as compared to the conventional ED and AD configurations.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Low-energy sustainable process (<1MJ/kg) for manufacturing green acetic acid.•Full valorization of reaction heat by steam generation and electricity made by ORC.•Heat pumping by vapor compression ...for energy efficient acetic acid purification.
Acetic acid is an essential chemical product. The need for ‘green’ acetic acid has spurred new research in developing more sustainable processes. This paper presents an original conceptual design of a low-energy and low-emissions sustainable process for acetic acid manufacturing by methanol carbonylation. The emphasis is set on energy efficiency, as the exothermic reaction releases a large amount of energy that may be more effectively used.
Two processes are investigated by rigorous simulation, based on homo- and heterogeneous catalysis. The latter reveals as innovative feature the full valorization of the energy released in the reaction section, along with reducing the separation sequence to only two distillation columns. The first dewatering column is driven by low-pressure steam generated by the reactor cooling. The second purification column uses heat pumping, in which the energy rejected in condenser is upgraded for reboiler heating by vapor compression (VC), using water as working fluid. The electricity for the vapor compression is ensured by applying an Organic Rankine Cycle (ORC) for waste heat recovery by the reactor cooling. In this way, the new green process needs very little energy (below 1MJ/kg product). This eco-efficient process shows also superior sustainability metrics (e.g. low emissions of 40gCO2e/kg) as compared to the homogeneous catalyst process.
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GEOZS, IJS, IMTLJ, IZUM, KILJ, KISLJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
► Ternary separation of benzene–toluene–xylene in a dividing-wall column. ► Rigorous simulations carried out in AspenTech Aspen Plus and Aspen Dynamics. ► Energy efficient control strategies based on ...most used PID control loops. ► Liquid split manipulation for implicit minimization of energy requirements. ►
DB/
LSV and
LB/
DSV exhibit relatively short settling times and low overshooting.
Dividing-wall column (DWC) is considered nowadays the new champion in distillation, as it can bring substantial reduction in the capital invested as well as savings in the operating costs. This work presents the simulation results of energy efficient control and dynamics of a dividing-wall column (DWC). In order to allow a fair comparison of the results with previously published references, the case-study considered here is the industrially relevant ternary separation of the mixture benzene–toluene–xylene (BTX) in a DWC. Rigorous simulations were carried out in Aspen Plus and Aspen Dynamics. Several conventional control structures based on PID control loops (
DB/
LSV,
DV/
LSB,
LB/
DSV,
LV/
DSB) were used as a control basis. These control structures were enhanced by adding an extra loop controlling the heavy component composition in the top of the prefractionator, by using the liquid split as an additional manipulated variable, thus implicitly achieving minimization of energy requirements. The results of the dynamic simulations show relatively short settling times and low overshooting especially for the
DB/
LSV and
LB/
DSV control structures. Moreover, the energy efficient control proposed in this work allows the operation of DWC with minimum energy requirements or maximum purity of products.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
