experimental investigation on the fixed bed of a small size biomass boiler

Abstract During the last decades, the increase of the world energy consumption promoted the renewable resource development and use. Together with wind, solar and hydro energy, biomasses play a key role in the reduction of the industrial environmental impact; moreover, the biomass combustion systems are very attractive for micro-generation purpose. In this paper, experimental tests on a 140kW small size fixed bed biomass boiler were carried out. The main goal was to study the thermal behavior and some chemical products, such as CO, CO2, Methane and Ethylene, from the combusting fixed bed of the system. In fact, despite the wide amount of literature for the laboratory scale systems, the commercial scale boilers have been seldom studied by the experimental point of view. The data were obtained by varying the operational parameters of the boiler, that are the air excess and the secondary to primary air feeding ratio. Furthermore, the collected data were analyzed and the relationship between the thermal-chemical data and the control variables was discussed

Thermal hazard analysis of organic peroxides by adiabatic calorimetry

Organic peroxides are widely used in the chemical industry as initiators or curing agents for polymerization reactions. However, the use of peroxides presents an intrinsic hazard due to the presence of the highly unstable peroxy group which causes peroxides readily decompose. In present study, the thermal hazards of a selected organic peroxide, the benzoyl peroxide (BPO), were experimentally investigated by using adiabatic calorimetry. On the basis of experimental results, the thermal hazard parameters under adiabatic conditions were estimated. Preliminary data with respect to decomposition onset temperatures and decomposition heat were obtained by simultaneous TG-DSC-FTIR analysis. A Phi-Tec II adiabatic calorimeter was used to study the thermal decomposition of the selected peroxide. The experimental data obtained allowed the assessment of thermokinetic parameters. Decomposition products formed during the experimental runs were sampled and characterized by FTIR and gas chromatographic techniques. The results obtained in the present investigation could be useful for the adoption of inherently safer design in the manufacturing, handling, storage, and disposal of organic peroxides

Wearable Integrated Soft Haptics in a Prosthetic Socket

Modern active prostheses can be used to recover part of the motor function associated with the loss of a hand. Nevertheless, most sensory abilities are lost, and the person has to manage interaction by relying mostly on visual feedback. Despite intensive research devoted to convey touch related cues, very few solutions have been integrated in a real prosthesis worn by a user. This letter describes a soft pneumatic feedback system designed with integrability and wearability among its main concerns. At the system core, two soft pneumatic actuators are placed in contact with the subject's skin and inflated to provide pressure stimuli, which can be used to represent force exerted by the hand grasping. We report on the design and the characterization of the system, including behavioural experiments with able-bodied participants and one prosthesis user. Results from psychophysical, dexterity and usability tests show that the system has the potential to restore sensory feedback in hand amputees, and can be a useful tool for enabling a correct modulation of the force during grasping and manipulation tasks

biomass early stage combustion in a small size boiler experimental and numerical analysis

Abstract The increment in the world energy consumption and the necessity for a sustainable industrial production, indicate that renewable resources may be key actors for future development. In this scenario, biomass appears fundamental for the smooth transition from fossil fuels to lower carbon footprint technologies, and as a moderator agent within the renewable market. The small size biomass combustion application appears as suitable for smart grid and distributed generation applications, but it is necessary to improve the design tools capabilities and the experimental knowledge of these systems. The present work aims at investigating the thermal behaviour of a 140 kW fixed-bed boiler sited at the Biomass to Energy Research Centre (CRIBE) of the University of Pisa and fed with woodchips. Experimental activities were conducted in order to acquire thermal and chemical data. Moreover, a computational fluid dynamic model was developed and validated. Attention was paid to the fixed bed analysis, and the results showed a good model prediction capability, with respect to the reduced computational demand required

Hazards and safety issues associated to the residual solid content in crude edible oil processing

The present work focuses on the hazards connected with edible oil refining during process and maintenance operations. A specific experimental protocol was set up in order to verify the possibility of having fire hazards connected with the unwanted residual solids which might accumulate on the bottom of storage tanks, due to sedimentation, or in process equipment, due to progressive fouling. The analysis of residual solid samples taken from an actual edible oil refinery allowed evaluating the possible formation of flammable mixtures or products during maintenance operations. Specific hazard indexes were defined in order to analyse two case studies which provided indications for the safety enhancement of process and maintenance operations

VIBES: Vibro-Inertial Bionic Enhancement System in a Prosthetic Socket

The use of vibrotactile feedback is of growing interest in the field of prosthetics, but few devices fully integrate this technology in the prosthesis to transmit high-frequency contact information (such as surface roughness and first contact) arising from the interaction of the prosthetic device with external items. This study describes a wearable vibrotactile system for high-frequency tactile information embedded in the prosthetic socket. The device consists of two compact planar vibrotactile actuators in direct contact with the user's skin to transmit tactile cues. These stimuli are directly related to the acceleration profiles recorded with two IMUS placed on the distal phalanx of a soft under-actuated robotic prosthesis (Soft-Hand Pro). We characterized the system from a psychophysical point of view with fifteen able-bodied participants by computing participants' Just Noticeable Difference (JND) related to the discrimination of vibrotactile cues delivered on the index finger, which are associated with the exploration of different sandpapers. Moreover, we performed a pilot experiment with one SoftHand Pro prosthesis user by designing a task, i.e. Active Texture Identification, to investigate if our feedback could enhance users' roughness discrimination. Results indicate that the device can effectively convey contact and texture cues, which users can readily detect and distinguish

On the Time-Invariance Properties of Upper Limb Synergies

In this paper, we present a novel approach to dynamically describe human upper limb trajectories, addressing the question on whether and to which extent synergistic multi-joint behavior is observed and preserved over time evolution and across subjects. To this goal, we performed experiments to collect human upper limb joint angle trajectories and organized them in a dataset of daily living tasks. We then characterized the upper limb poses at each time frame through a technique that we named repeated-principal component analysis (R-PCA). We found that, although there is no strong evidence on the predominance of one principal component (PC) over the others, the subspace identified by the first three PCs takes into account most of the motion variability. We evaluated the stability of these results over time, showing that during the reaching phase, there is a strong consistency of these findings across participants. In other words, our results suggest that there is a time-invariant low-dimensional approximation of upper limb kinematics, which can be used to define a suitable reduced dimensionality control space for upper limb robotic devices in motion phases

The Hydrothermal Carbonization Process for Waste Valorisation: a Study on the Effect of Process Conditions on the Yield and Properties of Hydrochars from Municipal Solid Waste

Hydrothermal carbonization (HTC) has received considerable attention in recent years for its potential to process heterogeneous organic wastes with high moisture contents. Unlike other thermochemical processes, HTC does not require drying of the feedstock as a pre-treatment. Performed in aqueous conditions at moderate temperatures under autogenous pressure, HTC produces a carbon rich solid phase, referred to as hydrochar, which can be directly used as a solid fuel, or it can be better exploited for new applications. In the present work the potential valorization by HTC of a waste stream from mechanical biological treatment of mixed municipal solid waste, namely the under-sieve fraction from the mechanical treatment stage, was explored. This stream does not have any potential for material recovery, and it is usually landfilled after aerobic biostabilization. HTC tests were carried out in a laboratory-scale reactor. The joint effect of different process parameters on the yield and physicochemical properties of the hydrochar produced was investigated. The design of experiments (DoE) / response surface methodology (RSM) approach was used for the analysis of the influence of temperature, time and solid load on the mass yield and properties of hydrochar. Quantitative relationships between responses and process parameters were determined. The results obtained demonstrated the feasibility of HTC for mixed municipal solid waste, suggesting HTC as a promising alternative treatment path to current waste management

Co-precipitation of Cathode Active Materials Precursors in Lithium-ion Batteries Recycling: Experiments and Modeling

Recycling lithium-ion batteries (LIBs) is becoming an imperative task given the large flow of spent batteries that in the next future will have to be managed. Among the current three main recycling routes to convert spent LIBs into recycled products, that is, pyrometallurgy, hydrometallurgy, or direct recycling, the co-precipitation route lies between the last two routes: its key unit operations are the leaching of battery materials and the co-precipitation of a precursor for the re-synthesis of the cathode active material (CAM). High susceptibility to impurities in the leached solution and a strong link between high-quality CAM precursors and the composition of the dissolved metal salts, makes experimental analysis on spent LIBs a crucial step to find the best operating conditions. For this reason, we present an experimental campaign to study the co-precipitation and formation of the complex chemical compounds involved in the process. Moreover, we also exploit the support that rigorous models are giving in many industrial fields, also benefiting chemical engineering and laboratory analysis. Therefore, in this study we also present a rigorous simulation model on UniSim Design® with the thermodynamic package OLI® that enables the possibility to consider most of the different liquid-solid equilibria needed. A validation of the model is performed with experimental data and a sensitivity analysis on metal concentrations, pH, and chelating agent is performed to find the critical parameters that regulate the co-precipitation outcomes. The aim is to optimize the choice of operating conditions to limit the number of laboratory tests and complex analyses that are often expensive and time-consuming