No description available.

No description available.

No description available.

No description available.

This work addresses the challenges in design of heat integrated low-temperature separation processes. A novel, systematic and robust methodology is developed, which contributes to the design practice of heat-integrated separation sequence and the refrigeration system in the context of low-temperature separation processes. Moreover, the methodology exploits the interactions between the separation and refrigeration systems systematically in an integrated design context. The synthesis and optimisation of heat-integrated separation processes is complex due to the large number of design options. In this thesis, task representation is applied to the separation system to accommodate both simple and complex distillation columns. The stream conditioning processes are simulated and their associated costs are included in the overall cost of the process. Important design variables in separation systems, such as the separation sequence, type and operating conditions of the separation units (e.g. the operating pressure, feed quality and condenser type) are optimised. Various refrigeration provision strategies, such as expansion of a process stream, pure and mixed multistage refrigeration systems and cascades of multistage refrigeration cycles, are considered in the present work. A novel approach based on refrigeration system database is proposed, which overcomes the complexities and challenges of synthesis and optimisation of refrigeration systems in the context of low-temperature separation processes. The methodology optimises the key design variables in the refrigeration system, including the refrigerant composition, the number of compression stages, the refrigeration and rejection temperature levels, cascading strategy and the partition temperature in multistage cascaded refrigeration systems. The present approach has selected a matrix based approach for assessing the heat integration potentials of separation and refrigeration systems in the screening procedure. Non-isothermal streams are not considered isothermal and stream splitting and heat exchangers in series are taken into account. Moreover, heat integration of reboiler and condenser of a distillation column through an open loop heat pump system can be considered in this work. This work combines an enhanced simulated annealing algorithm with MILP optimisation method and develops a framework for simultaneously optimising different degrees of freedom in the heat integrated separation and refrigeration processes. Case studies extend the approach to the design of heat integrated separation sequences in above ambient temperature processes. The robustness of the developed framework is further demonstrated when it is utilised to design the LNG and ethylene plant fractionation trains.

La distillation dite « charentaise » est une méthode de distillation discontinue permettant la production d’eaux-de-vie de cognac à partir de vin. La distillation est effectuée dans des alambics en cuivre avec un chauffage à feu nu qui peut être favorable à la génération de composés volatils. Or, les précurseurs et les mécanismes de réactions formant ces composés, pendant la distillation, restent mal connus. La première partie de l’étude consiste à identifier les composés volatils formés au cours de la distillation charentaise. Le bilan matière effectué sur de nombreux composés lors du procédé de distillation a révélé que 2 esters, 3 aldéhydes, 3 terpènes et 12 norisoprénoïdes étaient générés. Par la suite, deux distillations utilisant un mode de chauffe différent (feu nu et vapeur) ont été menées sur un alambic pilote. Le but était d’évaluer l’impact du mode de chauffe sur la génération en composés volatils. L’étude a montré que le mode de chauffe a peu d’effet sur la génération en composés volatils. De plus, les composés formés sont similaires à ceux formés lors de la distillation en alambic traditionnel. Enfin, le troisième axe de l’étude porte sur la caractérisation de l’hydrolyse acide de l’α- terpenyl-O-β-glucopyranoside, précurseur impliqué dans la formation de l’α-terpineol, identifié comme étant généré lors de la distillation charentaise ainsi qu’en alambic pilote. Le suivi de la dégradation dans un réacteur hermétiquement fermé de l’α-terpenyl-O-β-glucopyranoside et dans des conditions représentatives du vin durant la distillation montre l’hydrolyse pour former l’α- terpineol, le trans-terpin et son isomère. Cette étude a révélé que l’hydrolyse du précurseur est favorisée en milieu aqueux et suit une cinétique d’ordre 1 / The « charentaise » distillation is a batch distillation method that allows the production of cognac spirits from wine. The distillation is performed in copper alembics through a direct open flame heating that could favor the formation of volatile compounds. The first part of this study consists in identifying the volatile compounds formed during the distillation of cognac spirits. The mass balance performed on volatile compounds revealed that 2 esters, 3 aldehydes, 3 terpenes and 12 norisoprenoids were generated. Thereafter, two distillations using a different heating mode (direct open flame and steam) were conducted on a small-scale alembic. The goal was to assess the impact of the heating mode on the formation of volatile compounds. The study showed that the mode of heating has little effect on volatile compounds’ generation. Moreover, the compounds formed are similar to the ones during the traditional distillation of cognac spirit. Finally, the third part of the study focuses on the characterization of the acid hydrolysis of α-terpenyl-O-β-glucopyranoside which is the suspected precursor to be involved in the formation of α-terpineol, identified as generated during the charentaise distillation and in small-scale distillations. α-terpenyl-O-β- glucopyranoside was placed in two representative model solutions corresponding to the initial wine and the stillage. Both solutions were exposed to 100 °C in a closed reactor system. Results showed that the hydrolysis of the precurseur formed α- terpineol, trans-terpin and its isomere that seems to be 4-(2-hydroxypropan-2-yl)-1- methylcyclohexan-2-ol). Data also revealed that the hydrolysis of the precursor follows a first order reaction model ant that an aqueous media promotes the formation of trans-terpin.

With ever-growing environmental concerns, petrochemical and fine chemical industries face an omnipresent issue in recovering acetic acid from its aqueous solutions. The recovery of acetic acid through the esterification process is a very viable option. However, esterification reactions are typically restricted by equilibrium limitations, and face challenges with product purification. Reactive distillation is an emerging technology that has an extremely attractive potential as a process alternative for carrying out equilibrium limited chemical reactions. Although the reactive distillation process has been successfully commercialised for the manufacture of hIgh commodity chemicals e.g. methyl tertiary butyl ether (MTBE) and methyl acetate, its potential as a separation tool for the recovery of acetic acid using iso-amyl alcohol has not been exploited.