1,721,013 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
Recupero di zuccheri da residui agricoli
Get PDFMolti 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%
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
Supercritical water gasification of scenedesmus dimorphus μ-algae
No full textThe aim of the paper is based on the experimental tests of Gasification in supercritical water for humid biomass, Scenedesmus dimorphus. In this work, experimental tests were carried out in order to understand the main parameters of the SCWG process and their influence varying the total solids content, GGE and CGE gas yield and energy recovery. Based on experimental test and considering literature data about energy demand for microalgae growth and energy required for SCWG process it was possible to evaluate that with minimum total solid content necessary for setting-up a self-sustainable process considering the only energy recovery from the condensation of the water outlet the process. At the same time these simulation were repeated considering of use the enthalpy of water in SCW condition for turbine expansion instead heat recovery obtained not only syngas production usable for biofuels synthesis but also power production. © 2017 Walterde Gruyter GmbH, Berlin/Boston
Microalgae valorisation via accelerated solvent extraction: Optimization of the operative conditions
No full textThe valorisation of microalgae for the production of valuable biomolecules, for their use in several fields, such as cosmetic, pharmaceutical and animal food, by applying technologies able to avoid any kind of alteration of the biomolecule, is becoming a priority research topic. Several techniques can be used, among them Accelerated Solvent Extraction (ASE) with Generally Recognized As Safe (GRAS) solvents is an interesting technology. This paper deals with Accelerated Solvent Extraction investigations for extraction of lutein (C40H56O2, carotenoid belonging to the xanthophylls group) from Haematococcus pluvialis in red phase with a mechanical pre-treatment method to break the cell wall. Experiments were carried out by comparing performance of several solvents both conventional as Chloroform:Methanol (1:1) and Hexane (class 2 according to FDA classification) and solvents normally accepted in the pharmaceuticals and food industry as Acetone and Ethanol (class 3 of FDA classification) by varying extraction conditions (pressure, temperature and time). Copyright © 2018, AIDIC Servizi S.r.l
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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
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