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Li J.,KTH Royal Institute of Technology | Bonvicini G.,International Flame Research Foundation IFRF | Zhang X.,University of Alberta | Yang W.,KTH Royal Institute of Technology | And 2 more authors.
Energy Procedia | Year: 2014

The char oxidation of a torrefied biomass and its parent material was carried out in an isothermal plug flow reactor (IPFR), which is able to rapidly heat the biomass particles to a maximum temperature of 1400°C at a heating rate of 10;4; °C/s, similar to the real conditions found in power plant furnaces. During each char oxidation test, the residues of biomass particles were collected and analyzed to determine the weight loss based on the ash tracer method. According to the experimental results, it can be concluded that chars produced from a torrefied biomass are less reactive than the ones produced, under the same conditions, from its raw material. The apparent kinetics of the torrefied biomass and its parent material are determined by minimizing the difference between the modeled and the experimental results. The predicted weight loss during char oxidation, using the determined kinetics, agrees well with experimental results. © 2014 The Authors. Published by Elsevier Ltd.


Galletti C.,University of Pisa | Giacomazzi E.,ENEA | Giammartini S.,ENEA | Coraggio G.,International Flame Research Foundation IFRF | And 2 more authors.
Energy and Fuels | Year: 2013

Coal combustion is investigated in both air and oxy-fuel conditions by feeding pulses of coal particles in an entrained flow reactor able to provide high residence times. The radiant energy emitted in the range from UV to IR was collected by several photodiodes operating with high acquisition rate. The signal analysis showed the capability of the technique to capture the passage of coal streams and to identify different phenomena (e.g., volatiles ignition, char oxidation). The spatial arrangement of the photodiodes was planned in order to allow also deriving quantitative information, such as particle velocity, ignition delay, and devolatilization time, from the correlation of more signals. The ignition delay was found to be higher in oxy-fuel conditions than in air, mainly because the larger specific heat of the oxy-fuel environment. The proposed diagnostics may help the qualification of advanced experimental apparatus as entrained flow reactors, with the purpose to make them suited for heterogeneous kinetics studies in oxy-fuel conditions. © 2013 American Chemical Society.


Biagini E.,International Flame Research Foundation IFRF | Simone M.,University of Pisa | Barontini F.,University of Pisa | Barontini F.,Centro Of Ricerca Interuniversitario Biomasse Da Energia Cribe | And 3 more authors.
Chemical Engineering Transactions | Year: 2013

The thermochemical conversion of conventional and alternative biofuels is capable of supplying a wide range of energy vectors and chemicals. Peculiarities of such materials require a comprehensive and detailed characterization to provide the fundamental information and face with the issues of each process step. Innovative technologies, advanced model approaches, optimization procedures, need data which comply with relevant standards. The characterization tools described in this work range from lab-scale tools, used to provide the fuel fingerprint, to pilot scale facilities, which operate under industrial scale conditions. Protocols and procedures have been elaborated for all activities to provide reliable and qualified parameters for practical applications and comprehensive codes. The experimental activities have been supported with a broad set of on-line and off-line measurements and analyses, and coupled with modelling activities to qualify the experiments. Finally, a biofuel database, reporting the data collected in the last years, has been developed. Copyright © 2013, AIDIC Servizi S.r.l.


Li J.,KTH Royal Institute of Technology | Bonvicini G.,International Flame Research Foundation IFRF | Biagini E.,University of Pisa | Yang W.,KTH Royal Institute of Technology | And 2 more authors.
Fuel | Year: 2014

The promising properties of torrefied biomass provide a valid co-firing option for large percentage biomass utilization in existing coal-fired boilers. Torrefied biomass is expected to have a better combustion stability than raw biomass and similar to that of coal. The present work will characterizes the oxidation properties of torrefied biomass char and compare with that of raw biomass char. The studied two chars are produced from raw and torrefied biomass in an Isothermal Plug Flow Reactor (IPFR) at high temperature and high heating rate, a sufficient residence time is applied for the completion of the high temperature devolatilization. Char oxidation tests are carried out in the IPFR by varying temperature, oxygen concentration and residence time. The reactivity of two studied chars are analyzed and compared with referenced biomass char and coal char, and the impact of torrefaction on char reactivity is also discussed in this paper. Finally, the char oxidation kinetic parameters are determined using a parameter optimization method, and the obtained kinetics are examined by comparing the experimental and predicted mass conversions. © 2014 Elsevier Ltd. All rights reserved.


Stein-Brzozowska G.,University of Stuttgart | Maier J.,University of Stuttgart | Scheffknecht G.,University of Stuttgart | Cumbo D.,ENEL S.p.A | And 5 more authors.
Energy Procedia | Year: 2013

Operation of oxy-fuel power plants under ultra-supercritical parameters would help to overcome, to a certain extent, efficiency penalties from air separation and CO2-compression units. To improve the knowledge on material behavior under oxy-fuel combustion six candidate superheater alloys, varying from martensitic via iron-base austenitic to nickel-base were chosen and exposed at metal temperature of 580°C and 650°C to real oxy-fuel combustion conditions in 3MW combustion test rig of Enel and subsequently moved for further tests to laboratory corrosion test set-up at IFK. Exact definition of combustion conditions was based on measurements performed by IFRF.

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