1,720,973 research outputs found
Plastic-to-oil plant, according cracking reactor, and related methods for converting plastic waste into petrochemical products
No full textA feasibility assessment of an integrated plastic waste system adopting mechanical and thermochemical conversion processes
No full textThe large variety and amounts of plastic waste produced worldwide requires to better organize the industrial network devoted to the exploitation of this material by including different processes that allow to recover the “material” as main target. This paper presents the results of the feasibility study developed for an integrated system for plastic waste management designed in such a way to deal with the real market and provide for reliable targets in term of material recovery yields, energy efficiency and waste minimization. The system under study is a combination of mechanical sorting, thermochemical processes and conversion into materials and energy. The quantified block diagrams are used to represent the mass and feedstock energy balances by allowing the calculation of yields of given products. The equipment list for each sub-system is provided together with the installed power for the main component and/or auxiliary; these data allowed to perform the energy balance and to obtain the net energy production by the integrated system. The energy balance demonstrated that the integrated system is feasible while, on the contrary, the single processes are not energetic self-sustainable
Gasification of Recycled Plastic Waste in a Fluidized Bed Reactor: Effect of Operating Conditions
No full textTar removal during the fluidized bed gasification of plastic waste
No full textA recycled polyethylene was fed in a pilot plant bubbling fluidized bed gasifier, having an internal diameter of 0.381 m and a maximum feeding capacity of 90 kg/h. The experimental runs were carried out under various operating conditions: the bed temperature was kept at about 850 °C, the equivalence ratio varied between 0.2 and 0.35, the amount of bed material was between 131 and 215 kg, the fluidizing velocity was between 0.5 and 0.7 m/s, quartz sand and olivine were used as bed material, and air and steam were used as fluidizing reactants. The results confirm that the tar removal treatments applied inside the gasifier (primary methods) can eliminate or strongly reduce the need for a further downstream cleanup of the syngas. In particular, the utilization of a natural olivine as an in situ tar reduction agent remarkably improves the quality of the product gas, in terms of both high hydrogen volumetric fraction and larger syngas yield. © 2008 Elsevier Ltd. All rights reserved
Hydrothermal Carbonization: A Pilot-Scale Reactor Design for Bio-waste and Sludge Pre-treatment
No full textThe purpose of the paper is to illustrate the basis of the design of a pilot-scale reactor built to convert putrescent and high-water content biowaste into a stabilized product by using the Hydrothermal Carbonization process (HTC). The hydrothermal carbonization of selected biowaste has been previously studied in a bench-scale reactor to optimize the process parameters such as the temperature, reaction time, water-to-dry matter ratio and then scaled up at a scale 30 times larger. The new pilot-scale reactor has a volume of 0.1 m3 and has been designed and certified to be operated at 300 °C and 86 bar, allowing a wide range of operating conditions. The design has been structured in two steps: process design (a) and mechanical design (b). The main results of the process design step have been: the installed heat power, the method to provide and control the heating, the minimum reaction time necessary to reach a given yield. The mechanical design focused on the scalability of the reactor, the extraction of reaction products from the reactor at the end of process and increasing of reliability and safety. The designed reactor has been then built, commissioned, and operated in such a way to validate the design criteria and hypotheses. The comparison between the experimental results and the design input dataset confirmed the correctness of the design data input but highlighted that the thermal efficiency of the pilot scale plant was low so indicating the need to enhance it for the demonstrative plant. Graphical Abstract: [Figure not available: see fulltext.]
The O 2-enriched air gasification of coal, plastics and wood in a fluidized bed reactor
No full textThe effect of oxygen-enriched air during fluidized bed co-gasification of a mixture of coal, plastics and wood has been investigated. The main components of the obtained syngas were measured by means of on-line analyzers and a gas chromatograph while those of the condensate phase were off-line analysed by means of a gas chromatography-mass spectrometer (GC-MS). The characterization of condensate phase as well as that of the water used as scrubbing medium completed the performed diagnostics. The experimental results were further elaborated in order to provide material and substances flow analyses inside the plant boundaries. These analyses allowed to obtain the main substance distribution between solid, gaseous and condensate phases and to estimate the conversion efficiency of carbon and hydrogen but also to easily visualise the waste streams produced by the process. The process performance was then evaluated on the basis of parameters related to the conversion efficiency of fuels into valuable products (i.e. by considering tar and particulate as process losses) as well as those related to the energy recovery. © 2011 Elsevier Ltd
Hydrothermal carbonization of digestate and leachate in a lab-scale batch reactor
No full textThe use of biomass as a feedstock for renewable energy and biomaterials production is gaining increasing attention due to economic and environmental issues. Among all substrates, the organic fraction of municipal solid waste represents a valuable resource for anaerobic digestion facility. This process generates biogas, digestate and leachate. The last two streams are by-products, with potential harmful environmental impact and significant disposal costs. Thus, a proper handling of these biowastes is needed. In the present study, a bench-scale hydrothermal carbonization reactor was operated with two mixtures of digestate and water or leachate varying the residence time and the reaction temperature. The results indicated that aforementioned operating parameters affect the composition and the yield of the obtained hydrochar and that the substitution of water with leachate is technically feasible
La valutazione economica del rischio di investimento per gli impianti di recupero di energia da rifiuti
No full textIl volume affronta, da vari versanti, il problema della gestione dei rifiuti e, in particolare, quello del loro trattamento finalizzato al recupero di materia e di energia. La raccolta e lo smaltimento dei rifiuti urbani in Italia costa oltre 6,5 miliardi di Euro all’anno, cui corrisponde, in media, circa 113 Euro/anno per ogni cittadino. Questi costi ambientali ed economici potrebbero essere ridotti, anche drasticamente, con un controllo ....
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