Activated carbons are efficient catalysts for tar cracking, suitable for hot cleaning of the syngas produced during biomass- and waste-to-energy gasification processes. This study investigates the ...conversion of naphthalene, utilised as reference for tar compounds, when catalysed by a coal-derived activated carbon. The attention focuses on the influence of the operating temperature, in the range 750–900 °C, and the size of selected activated carbon, which has been used under form of pellets, granules and powders. The conversion efficiency improves when the temperature raised from 750 °C to 900 °C (from 79% to 99%, for the pellets), and when the catalyst size reduced from pellets to powders (from 79% to 97%, at 750 °C). The diffusional resistance in the catalyst particles has been then quantified in terms of Thiele modulus and internal effectiveness factor. A gradual reduction of catalyst surface area has been also observed for longer tests, due to the progressive deposition of soot from naphthalene decomposition over and inside the porous structure of the activated carbon. The carbon content of these deposits has been quantified, showing larger percentages on the surface of granules and powders.
•Naphthalene is used as reference compound for tars in the syngas from gasification.•Operating temperature and catalyst size have been investigated.•Results indicate a pore diffusion resistance in coarser particles.•Catalyst powders have limited pore diffusion resistance and do not lead to high pressure drops.•Progressive reduction of the catalytic surface area is related to soot deposition.
The paper reports on an experimental study aimed at investigating the potential of performing biomass torrefaction using air instead of nitrogen as a carrier gas, which allows reducing the operating ...costs of upgrading biomass. Specifically, the performances of oxidative and non-oxidative torrefaction treatments were comparatively investigated by using commercial wood pellets and olive pomace pellets as a feedstock. Batch torrefaction tests at three different temperature levels (200, 230 and 250 °C) were performed in a laboratory-scale fluidized bed reactor by fixing the reaction time equal to 15 min; this allowed to investigate the impact of the torrefaction temperature and atmosphere on: a) the distribution of the main output products of the torrefaction process (torrefied solids, condensable volatiles and permanent gases); b) the properties of torrefied pellets as a fuel (i.e., proximate composition, ultimate composition and calorific values); c) the process performances in terms of mass and energy yields of the solid product; and d) the quality of torrefied pellets in terms of mass and energy densities, hardness (shore D) and non-standard durability index. Fluidized-bed torrefaction tests were also complemented by non-isothermal thermogravimetric measurements (TG/DTG/DSC) performed in both air and nitrogen atmospheres. Results show that, under the same operating conditions, the process performance of oxidative torrefaction (i.e., mass and energy yields of the solid product) are worse than that of the non-oxidative treatment, particularly in the case of olive pomace pellets. This is mostly a consequence of the higher degradation rate triggered by oxidative reactions. On the other hand, the physical properties (i.e., mass density, energy density, hardness and durability) of torrefied olive pomace pellets obtained under oxidative atmosphere are better than those obtained via non-oxidative torrefaction. A similar behavior, however, was not observed in the case of woody fir pellets. This confirms that the fluidized bed torrefaction is feedstock-sensitive process; in particular, non-woody olive pomace pellets can be torrefied in oxidative environments, whereas fir pellets are more suitable for non-oxidative torrefaction.
Since the torrefaction treatment of biomass pellets in a fluidized bed reactor has not been investigated so far, findings of this work can be useful to highlight potential advantages related to use of such a technology in this specific application.
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•Torrefaction of biomass pellets in inert and oxidative environment is investigated.•Woody and non-woody biomass pellets are tested as a feedstock.•The mechanical properties of pellets torrefied in air and nitrogen are compared.•Non-woody olive pomace pellets can be torrefied in oxidative environments.•Woody fir pellets are more suitable for non-oxidative torrefaction.
In this work, an innovative process layout for methane production is proposed and investigated with the aim to promote the integration of renewable energies chemical storage via hydrogen production ...by water electrolysis and biomass gasification. The core of the proposed layout is the integration between an experimental fluidized bed gasification system, fed with spruce wood pellets and using Fe/Al2O3 catalyst, and a conceptual methanation unit. This latter was modelled as a series of adiabatic fixed bed reactors with inter-cooling, water condensation at the exit of each reactor, and product recycle. The performance of the methanation system was evaluated by considering that the product stream coming from the gasifier system reacts, after purification and mixing with pure hydrogen coming from an electrolysis cells array, over Ni supported on alumina catalyst. The number of electrolysis cells to be stacked in the hydrogen production unit was evaluated by considering that a constant H2 production able to reach 7:1:1H2:CO:CO2 ratio at the inlet of the methanation unit should be attained.
•Adding steam to air as gasification agent enhances the syngas H2:CO ratio.•Steam-and-air gasification lowers the H2 request from water electrolysis.•High CO and CO2 conversions are achieved in a multistage adiabatic methanation unit.•Syngas to methane could be a viable answer for renewable energies chemical storage.
•Late radiation-associated dysphagia (RAD) in head and neck cancer (HNC) represents a common entity.•Intensity modulated RT (IMRT) is the recommended technique to reduce RAD.•Several topics, such as ...organ at risk, radiation-dose constraints and rehabilitation strategies, need to be clarified.•These topics are analyzed, based on IMRT published data.
In head and neck cancer (HNC) scenario, newer radiotherapy (RT) techniques, such as intensity modulated RT (IMRT), aim to reduce acute and late toxicity without impair tumor response and loco-regional control rates. However, late radiation-associated dysphagia (RAD) remains a major clinical problem and has gained a growing importance in the last few years, especially due to human papilloma virus (HPV)-related HNC favorable prognosis.
The aim of this review was to provide clinical information about late RAD. The main anatomical structures involved in swallowing were described, in order to define potential organ at risk and available radiation-dose constraints in IMRT plan. Finally, possible rehabilitation strategies were proposed. This is expected to represent an opportunity for improved multidisciplinary management in HNC patients.
The paper deals with fluidized bed gasification of a biomass for producing a syngas with optimized hydrogen yield thanks to in-bed catalysis. Four different bed materials have been adopted: inert ...quartzite as reference case, olivine and dolomite as natural catalysts, and Ni-alumina as artificial catalyst. The gasification tests have been carried out at steady state in a pilot-scale bubbling fluidized bed, under operating conditions typical for gasification as reported in the paper. The gas analyses have been performed with dedicated instrumentation, like continuous analyzers and gas chromatograph, and adopting a standard protocol for tar sampling and characterization. The influence of the catalytic materials on the concentration of stable gases (e.g. H
2, CO
2, CO, CH
4 and light hydrocarbons) as well as on the efficiency of tar conversion has been studied. In particular the artificial catalyst has the largest effectiveness in enhancing the H
2 yield as well as in tar reduction. The catalyst gives rise to an elutriation rate significantly lower than that observed for dolomite at comparable
U/
U
mf ratio, denoting a better mechanical resistance. A stable activity of the nickel–alumina catalyst has been observed for the whole duration of reaction tests suggesting that no deactivation phenomena occurred, due to coke deposition or morphological modifications of the particles.
Torrefaction is a thermal pretreatment of biomass feedstocks aimed at their conversion into a commodity solid fuel with more uniform and standard properties. Pressurized torrefactiona novel ...conceptdeserves consideration because of its possible advantages with respect to the atmospheric process, in particular the establishment of favorable conditions for generation of valuable condensed products. The objectives of this research are (i) an investigation on the feasibility of the pressurized, steam-assisted, batch torrefaction of some agro-industrial biomass residues and (ii) the conversion of these latter into solid and liquid products to be used in energy production or chemical processes, with improved characteristics with respect to the raw biomass. The results reported in this article prove that the operation under pressure allows maintaining high water vapor pressure in the system, enhancing the solid biomass conversion to liquid products. The recovery of valuable liquid compounds from the solid residue proved to be further boosted by a subsequent stage of solvent extraction. The condensed liquid fraction resulting from torrefaction turns out to be much higher (i.e., up to 3 times) under pressurized condition than under the atmospheric conditions. The influence of the water-to-fuel feed ratio on the distribution between solid and liquid fractions is also noticeable. Thermodynamic computations demonstrate a decrease of the heat duty required for the torrefaction at the highest pressure (P = 40 atm) due to the presence of liquid water in the final system.
The management of plastic waste is a serious environmental problem, therefore numerous strategies have been explored to reuse/recover these materials, avoiding their disposal in landfills. In ...particular, research has focused on thermochemical conversion processes and especially on pyrolysis processes. Therefore, in this study, a real Plastic Solid Waste (PSW) from COREPLA (Italian national consortium for collection, recycling, and recovery of plastic packaging), deprived of PET, PVC, and PTFE was used as feedstock for batch thermal and catalytic pyrolysis tests. The experiments were performed in a micro-reactor under nitrogen flow, using ɣ-alumina as catalyst. The effects of a variation in pyrolysis temperature (450-650°C) on the gaseous, condensable, and solid products were assessed. The thermal and catalytic pyrolysis tests of LDPE at 550°C were also investigated, as a representative surrogate of the plastics materials found in PSW. Preliminary results highlight that gas and condensate yields increase with pyrolysis temperature (with or without γ-alumina). The condensate products of all experiments were an oily wax made up mainly of long-chain aliphatic hydrocarbons (mostly diesel-like fraction, C
12
-C
20
). The qualitative composition of gaseous and condensable products differs between thermal and catalytic tests. However, the alumina leads to a higher formation of aromatic hydrocarbons.
Objectives
To characterize swallowing deficits in amyotrophic lateral sclerosis (ALS); investigate the delay in dysphagia onset; estimate correlations between dysphagia severity and patients' ...functional status; identify the symptom(s) most likely to predict dysphagia.
Materials and methods
A group of 49 consecutive patients with ALS, 14 with bulbar onset and 35 with spinal onset, underwent swallowing evaluation including bedside and fiberoptic endoscopic examination to detect dysphagia.
Results
Patients with dysphagia were more likely than those without to have bulbar onset ALS (P = 0.02); more severely impaired chewing (P = 0.01); and tongue muscle deficits (P = 0.001). The only variable measured at first examination significantly associated with dysphagia was a more than mild tongue muscle deficit. The only variable useful in predicting dysphagia was a chewing deficit. In 10 of the 49 patients studied, swallowing evaluation disclosed an impaired cough reflex.
Conclusions
Dysphagia in patients with ALS correlates significantly with bulbar onset and with oral swallowing impairment. Fiberoptic swallowing evaluation is a useful tool for detecting swallowing deficits and laryngeal sensitivity in patients with ALS. An impaired cough reflex is an unexpected finding in many patients with ALS.
In healthy subjects (HS), transcranial magnetic stimulation (TMS) applied during ‘linguistic’ tasks discloses excitability changes in the dominant hemisphere primary motor cortex (M1). We ...investigated ‘linguistic’ task‐related cortical excitability modulation in patients with adductor‐type spasmodic dysphonia (ASD), a speech‐related focal dystonia. We studied 10 ASD patients and 10 HS. Speech examination included voice cepstral analysis. We investigated the dominant/non‐dominant M1 excitability at baseline, during ‘linguistic’ (reading aloud/silent reading/producing simple phonation) and ‘non‐linguistic’ tasks (looking at non‐letter strings/producing oral movements). Motor evoked potentials (MEPs) were recorded from the contralateral hand muscles. We measured the cortical silent period (CSP) length and tested MEPs in HS and patients performing the ‘linguistic’ tasks with different voice intensities. We also examined MEPs in HS and ASD during hand‐related ‘action‐verb’ observation. Patients were studied under and not‐under botulinum neurotoxin‐type A (BoNT‐A). In HS, TMS over the dominant M1 elicited larger MEPs during ‘reading aloud’ than during the other ‘linguistic’/‘non‐linguistic’ tasks. Conversely, in ASD, TMS over the dominant M1 elicited increased‐amplitude MEPs during ‘reading aloud’ and ‘syllabic phonation’ tasks. CSP length was shorter in ASD than in HS and remained unchanged in both groups performing ‘linguistic’/‘non‐linguistic’ tasks. In HS and ASD, ‘linguistic’ task‐related excitability changes were present regardless of the different voice intensities. During hand‐related ‘action‐verb’ observation, MEPs decreased in HS, whereas in ASD they increased. In ASD, BoNT‐A improved speech, as demonstrated by cepstral analysis and restored the TMS abnormalities. ASD reflects dominant hemisphere excitability changes related to ‘linguistic’ tasks; BoNT‐A returns these excitability changes to normal.
In healthy subjects, magnetic stimulation over dominant primary motor area elicited larger MEPs during loud reading compared to other linguistic and non linguistic tasks, while in spasmodic dysphonia (ASD) it elicited MEPs of increased amplitude also during syllabic phonation. In ASD, BoNT‐A improved speech as demonstrated by cepstral analysis and restored the TMS abnormalities. We conclude that spasmodic dysphonia is characterized by abnormal dominant speech‐related network activation.
Fluidized bed combustion stems out as one of the most feasible technology to burn sewage sludge. However, the performances of bubbling fluidized bed combustors fueled with pelletized sewage sludge ...are still lacking at pilot scale. In this work, an experimental campaign on a pilot scale bubbling fluidized bed combustor (FBC370), was carried out to investigate the effect of sewage sludge pelletization on combustion behavior. The gaseous and particulate emissions during stable thermal regimes for thermal power ranging roughly from 50 to 65 kW
th
were measured. Under the experimental conditions investigated, a stable and efficient combustion behavior was obtained in terms of low emissions of unburnt species, but a train of cleaning processes is necessary to reduce gaseous and particulate emissions. A two stage de-dusting system for the capture of fine and ultrafine particles and the proper units for the abatement of the NOx, SO
2
, and HCl produced in high concentrations are needed. The temperature profile in the post-combustion zone and stable combustion conditions are critical for the formation of dioxins. On the whole, the sewage sludge pelletization plays an important role in fuel conversion and in the formation of particulate and gaseous macro pollutants. In particular, it is observed that: 1) the partitioning between fly and bottom ash significantly changes reducing the generation of fines particles produced; 2) the stratified combustion of volatile matter and char particles can be enhanced at low fluidization velocity favoring bed agglomeration phenomena; 3) NO emissions are affected by ash accumulation inside the bed when efficient fuel mixing conditions are achieved.
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