1,721,143 research outputs found
Synthesis of new separation processes for bioethanol production by extractive distillation
No full textBiofuels and bioethanol are catalyzing the attention of researchers due to the big potential in reducing the dependence on crude oil together with the possible reduction in the pollution associated with the combustion processes. The bioethanol separation process is significant in terms of its production cost. In this paper, the availability of new distillation sequences for the separation of pure ethanol from the fermentation broth is considered. The new sequences are generated following a step-by-step procedure. Extending the concept of thermally coupled structures and column sections recombination, already successfully applied to ideal mixtures, it was possible to generate new distillation sequences for azeotropic mixtures. The new arrangements are proved to have a lower energy consumption together with a reduced capital cost compared to the classical sequence proposed in the literature
New distillation sequences for bioethanol production by extractive distillation
No full textIn a bioethanol production plant the separation unit performs the recovery of the ethanol from the raw fermentation beer to produce high purity ethanol. Although different separation techniques are available, distillation or distillation combined with other unit operations, remains the main technology considered for the ethanol purification. The formation of a homogeneous minimum-boiling azeotrope limits the purity allowable employing a simple distillation unit. The classical configuration for the separation of an ethanol-water mixture by extractive distillation employs three columns: the pre-concentrator, the extractive column and a stripping section. Starting from this configuration, new separation sequences are obtained applying the thermal coupling principle. Then, the column sections were rearranged taking into account the limits imposed by the recycle streams. The new arrangements were simulated considering a typical broth composition and ethylene glycol as a solvent. The new sequences report capital and energy cost reductions compared to the classical separation sequence proposed in the literature
Synthesis of intensified simple column configurations for multicomponent distillations
No full textThe synthesis of intensified simple column configurations (ISC) for multicomponent distillations is presented. The ISC configurations use less columns and less heat exchangers than the traditional distillation configurations (TDC), while they keep the similar structural simplicity as the TDC configurations that each column produces an overhead product with a condenser and a bottoms product with a reboiler. For an N-component zeotropic mixture, an easy-to-use procedure is first formulated to generate the ISC configurations from the simple column configurations (SC) with only sharp splits. Then, the procedure is generalized to produce the ISC configurations from any traditional distillation configurations (TDC) with both sharp and sloppy splits. It is demonstrated that the procedure can explicitly modify the TDC configurations step-by-step to systematically generate all the possible ISC configurations. The ISC configurations have the potential to reduce both energy consumption and capital costs than the TDC configurations, at the same time, they have the similar structural simplicity in terms of systems design, control and operation as the traditional distillation configurations. Therefore, they constitute an advantageous alternatives subspace when looking for an optimal system for a specific application in both new design and retrofit of distillation plants
A systematic procedure for synthesis of intensified simple column configurations for multicomponent distillations
No full textCO2 uptake capacity of coal fly ash: Influence of pressure and temperature on direct gas-solid caronation
No full textCoal ashes are normally considered as a waste obtained by the coal combustion in thermal power plants. Their utilization inside the site where are produced represents an important example of sustainable process integration. The present study was performed to evaluate the application of a gas-solid carbonation treatment on coal fly ash in order to assess the potential of the process in terms of sequestration of CO2 as well as its influence on the leaching behavior of metals and soluble salts. Laboratory tests, performed under different pressure and temperature conditions, showed that in the pressure range 1 ÷ 7.5 bar the CO2 uptake increased with temperature, shortening the time required to capture higher percentage of CO2. Conversely, in the pressure range 10 ÷ 15 bar, the carbonation kinetics slowed down and the effect of temperature was less evident. The best CO2 uptake was found to be 18.2 wt% corresponding to a maximum carbonation efficiency of 74%, estimated on the basis of the initial CaO content. The high degree of ash carbonation achieved in the present research, which was conducted under mild conditions, without add of water and without stirring, showed the potential use of coal fly ash in CO2 sequestration by means of direct gas-solid mineral carbonation
Process analysis for the carbon dioxide chemical absorptionâregeneration system
Full text linkThe process analysis for the post-combustion CO2capture using amine-based solvents is nowadays a fundamental step in its industrial scale design. In this work, the absorption-solvent regeneration system is deeply analyzed for different values of the loading in the solvent entering the absorber. The importance of the temperature and composition column profiles is highlighted for both the columns. In particular, the tight connection between the profiles and the L/G ratio is found to influence the choice of solvent flow rate for what concerns the absorber. On the other hand, an alternative configuration for the stripper is proposed together with a new criterion for the evaluation of the packing height. Finally, it is found that, in order to minimize the energy consumption in the stripper, the rich solvent must be sent at the highest possible temperature, taking into account the limitations imposed by the minimum temperature approach in the cross heat-exchanger and the solvent degradation
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