112,431 research outputs found
Biofuels production by biomass gasification: A review
No full textThe production of biofuels from renewable sources is a major challenge in research. Methanol, ethanol, dimethyl ether (DME), synthetic natural gas (SNG), and hydrogen can be produced from syngas which is the result of the gasification of biomasses. Syngas composition varies according to the gasification technology used (such as fixed bed reactors, fluidized bed reactors, entrained flow reactors), the feedstock characteristics, and the operating parameters. This paper presents a review of the predominant biomass gasification technologies and biofuels obtained from syngas by biomass gasification. © 2018 by the authors
Process Innovation Via Supercritical Water Gasification to Improve the Conventional Plants Performance in Treating Highly Humid Biomass
No full textThe aim of the paper is a comparison among three innovative process layouts for biomethane and power production from humid biomasses: anaerobic digestion (AD), supercritical water gasification integrated in a supercritical steam turbine stages (SCWG + SuST) and a technology that combines these two, AD plus SCWG and SuST. All the solutions were implemented in an ad hoc simulative tool of Aspen Hysis® v.7.0.1. Livestock sludge (LS) with an energy content up to 10 wt% (ashes free) was used as reference biomass to establish and compare the performance of any proposed process scheme. LS feedstocks introduced in the SCWG + SuST increased both biomethane production and power production of about 50 % compared to AD process that produces 25 Nm3/(day t) of pure biomethane. Combining both technologies, the digestate from AD outflow is feeding the SCWG + SuST process, there is an increase of 50 % of power generation with a production of biomethane of about 36 Nm3/(day t). Another advantage of the SCWG + SuST is that, set the fed, it is possible to reduce drastically the volume of the plant because the fermentation step, which usually corresponds to 15–30 days, is not required. Considering that although AD process is a simple and consolidated technology, it does not allow the total recovery of the organic compounds and requires long period for the biomass, the proposed innovative processes could offer new solutions for biomethane and power production. © 2016, Springer Science+Business Media Dordrecht
Teoriia prozy v 20-e gg. L.V. Pumpjanskij i "formalisty"
No full textThe article examines the most important concepts within the theory of prose by Lev Pumpjanskij, Viktor Sklovskij, Jurij Tynjanov, Boris Ejchenbaum and Boris Tomasevskij. The paper aims to compare the discussed thematic categories, trying to reconstruct the wide debate on the prose during 20s
Smert’ i bessmertie v p’esach «Goloc otca» («Molčanie») i «14 krasnych izbušek» (o sud’be N. Fëdorova v tvorčestve A. Platonova 1930-1940-ch godov)
No full textRecupero di zuccheri da residui agricoli
No full textMolti residui agricoli possono essere trasformati in prodotti energetici (bioetanolo, biogas) e intermedi dell’industria chimica e dei polimeri. Infatti, questi materiali sono costituiti in gran parte da biopolimeri (emicellulosa, cellulosa e lignina) che opportunamente destrutturati e isolati possono costituire la base di una ricca chimica di sintesi e di processi fermentativi che sono fondamentali nella visione della Bioeconomy. I residui della coltivazione del mais a valle della produzione delle cariossidi (stocchi, tutoli, foglie), sono particolarmente interessanti, sia per la composizione sia per la relativa
diffusione in Italia e nelle zone temperate in generale. Volendo stabilire un paragone, si può dire che dal punto di vista della produttività e dell’impatto sull’industria agroalimentare, la pianta del mais riveste un ruolo analogo a quello che la canna da zucchero riveste nell’economia agricola delle zone tropicali. Questo è il motivo per cui abbiamo scelto questo residuo; è da considerare comunque che le deduzioni tratte possono essere applicate con un ottimo margine di affidabilità anche ad altri tipi di residui lignocellulosici. Le sperimentazione condotta ha riguardato il recupero di zuccheri dai carboidrati costituenti il materiale lignocellulosico, previa loro separazione attraverso un processo di pretrattamento, ossia Steam Explosion (SE), che utilizza vapore saturo in un intervallo di temperatura compreso tra 180 - 200 °C. Questo pretrattamento è tra i più utilizzati sia in scala laboratorio che in impianti industriali perché è efficace, economico e a basso impatto ambientale. I trattamenti di SE sono stati eseguiti in un reattore batch da 10 litri capace di processare circa 1 kg di biomassa umida per ciclo. I parametri esaminati sono stati la temperatura del processo e il grado di pre-impregnazione con acido solforico, aggiunto per catalizzare le reazioni di idrolisi. L’ottimizzazione del numero e del tipo dei trattamenti per ritrovare le condizioni ottimizzate e l’analisi statistica dei dati sono stati eseguiti utilizzando specifici software di DoE (design of experiments). I dati sperimentali hanno mostrato che la massima solubilizzazione dei carboidrati può essere ottenuta utilizzando un carico di acido solforico del 2.9% ed una temperatura di 180 °C ad un tempo di trattamento di 5 minuti. In particolare, l’azione dell'acido solforico amplifica gli effetti idrolitici del trattamento di SE frammentando ulteriormente i polimeri della biomassa in oligomeri e monomeri idrosolubili. Inoltre, il suo impiego risulta particolarmente utile a basse temperature dato che incrementa la solubilizzazione della biomassa, soprattutto nel caso dello xilosio che viene solubilizzato all’80%.Many agricultural residues can be converted to energy products (bioethanol, biogas) and chemicals, polymers. In fact, these materials are largely made up of biopolymers (hemicellulose, cellulose and lignin) that appropriately destructured can form the basis of a large chemical synthesis and fermentation processes that are crucial in the view of Bioeconomy. The residues of maize cultivation, after the production of kernels (stalks, cobs, leaves), are particularly interesting, both for their composition and for being largely available in the temperate zones. We can say that from the point of view of productivity and the impact on food and agriculture, the corn plant plays a role analogous to
that of sugar cane plays in the agricultural economy of the tropics. This is why we chose this remnant; It is to be considered, however, that the deductions can be applied with a great margin of reliability also to other types of lignocellulosic residues. The experiments covered the recovery of sugars from carbohydrate of the lignocellulosic material,
after their separation through a pretreatment process, ie Steam Explosion (SE), which uses saturated steam in a temperature range between 180 - 200 ° C. This pretreatment is among the most used both in laboratory and in industrial scale because it is effective, economical and has low environmental impact. The SE treatments were carried out in a 10-liter batch reactor able of processing about 1 kg of wet biomass per cycle. The investigated parameters were temperature and the degree of pre-impregnation
with sulfuric acid added to catalyze the hydrolysis reactions. The optimization of the number and type of treatments to find the optimal conditions and the statistical analysis of data was performed using specific software of DoE (design of experiments). The experimental data showed that the maximum recovery of carbohydrates can be obtained using a load of sulfuric acid of 2.9% and a temperature of 180 °C (at 5 minutes of treatment). In particular, the action of sulfuric acid amplifies the hydrolytic effects of the treatment of SE further fragmenting the polymers of the biomass in water soluble oligomers and monomers. Furthermore, its use is particularly useful at low temperatures since it increases the solubilization of biomass, especially in the case of xylose that is solubilized up to 80%
Unstructured discretisation of a non-local transition model for turbomachinery flows
No full textThe description of transitional flows by means of RANS equations is sometimes based on non local approaches which require the computation of some boundary layer properties. In this work a non-local Laminar Kinetic Energy model is used to predict transitional and separated flows. Usually the non-local term of this model is evaluated along the grid lines of a structured mesh. An alternative approach, which does not rely on grid lines, is introduced in the present work. This new approach allows the use of fully unstructured meshes. Furthermore, it reduces the grid-dependence of the predicted results. The approach is employed to study the transitional flows in the T 106c turbine cascade and around a NACA0021 airfoil by means of a discontinuous Galerkin method. The local nature of the discontinuous Galerkin reconstruction is exploited to implement an adaptive algorithm which automatically refines the mesh in the most significant regions
V.G. Belous, Vol’fila, ili Krizis kul’tury v zerkale obščestvennogo samosoznanija, Mir’, SPb 2007
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