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To realize a carbon negative power production technology, it is interesting the option of coupling a Chemical Loping Combustor to a gas turbine. The development of this technology foreseen in the project GTCLC-NEG has some technical barriers, the most important of which is the operation of the chemical looping combustor at high temperature and high pressure conditions. To overcome these limits CFD modeling can be performed to optimize the behavior of the combustor and its design process. This work models the FUEL reactor of a chemical looping combustion plant working in batch mode and based on the reactor available at the Instituto de Carboquimica in Zaragoza, Spain. It is used an oxygen carrier mainly based on 60% mass Fe2O3 and 40% mass Al2O3. Biomethane is fed to the bottom of the fluidized bed with different velocities and mass flows and the composition of the gases at the outlet of the fuel reactor is measured. The results show that it is possible to model a 2 min duration reduction cycle by running the model for a time comprised between a minimum of 4 h and a maximum of 2 days of simulation. Another important result is the modeling of the chemical reactions happening in the reactor. Kinetics is modelled based on Activation energy (66 kJ/mol) and Pre-exponential factor (4.34 × 101 m3n mol−n s−1). The simple kinetic scheme gives reasonable first approximations and can be used to determine the duration of the reaction, the composition of the exhaust gases and the biofuel conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ethanol conversion involved several routes under chemical looping conditions. • Nickel oxide oxidises secondary products from primary ethanol conversion. • Nickel in reduced oxygen carrier catalyses ethanol dehydrogenation or de-composition. • Kinetics for catalytic and non-catalytic reactions determined at high temperature. The use of bio-ethanol in chemical looping combustion (CLC) and reforming (CLR) has the potential to produce energy and/or hydrogen and, as a negative-emissions technology (NET), to remove CO 2 from the atmosphere at low cost following the principles of bio-energy with CO 2 capture and storage (BECCS). The determination of the rate of the chemical processes involving the fuel conversion with the oxygen carrier is required for the modelling and design of a chemical looping unit. In this work, a kinetic study of ethanol conversion is performed considering a NiO-based material as the oxygen carrier. Combined experiments in TGA and fixed bed were conducted. TGA tests confirmed that the oxygen carrier was reduced by a ethanol-containing gaseous stream at temperatures higher than 773 K. An apparent reaction kinetics for the NiO reduction with ethanol was determined, which might be used in simplified fuel reactor models. However, tests performed in a fixed bed revealed that products derived of the ethanol decomposition, such as CH 4 , CO, H 2 were responsible for NiO reduction, instead of the direct reduction with ethanol. High temperature kinetics of processes involved in ethanol conversion, namely dehydration, dehydrogenation and decomposition, were determined. Both, non-catalytic and Ni-catalytic reactions were of relevance under chemical looping conditions. A reaction pathway was described to be used in detailed fuel reactor models of chemical looping units. [ABSTRACT FROM AUTHOR]

The thermochemical conversion of swine manure using chemical looping processes is an alternative for obtaining bioenergy with CO 2 capture and solving environmental problems related to excess nutrients and greenhouse gas emissions. In this study, the combustion of swine manure was performed in a chemical looping with oxygen uncoupling (CLOU) unit at the 0.5 kW th scale with copper-based oxygen carrier particles supported on magnetic MnFe spinel. The effects of the fluidisation agent (CO 2 or steam), air excess (7%–23%), and temperature (800–950 °C) on different parameters, namely the CO 2 capture rate, combustion efficiency, and nitrogenous compound emissions, were analysed. High combustion efficiencies (95%–98%) were achieved, and tar compounds were not detected in the flue gases. Similarly, elevated CO 2 capture efficiency values (82%–99%) were also achieved, which increased by increasing the temperature. Most nitrogen (ca. 93%–96%) is converted into innocuous N 2. The NO concentration increased with temperature, whereas N 2 O and NH 3 concentrations decreased. [Display omitted] • Energy valorization of the swine manure with CLOU technology has been performed. • Magnetic Cu based oxygen carrier was tested in a 0.5 kW th CLOU plant. • High combustion and CO 2 capture efficiencies were reached. • N-fuel was mostly converted to N 2. • NO concentration increased with the temperature whereas N 2 O and NH 3 decreased. [ABSTRACT FROM AUTHOR]

[Display omitted] • The paper presents a review on the application of ilmenite in CLC, CLR and CLOU. • Calcination increase ilmenite reactivity and OTC. • Ilmenite has good reactivity with syngas. • Ilmenite reactivity with methane is lower respect to other oxygen carriers. • Cost of OC makeup for unit of energy released by the FR is a key economic index. To tackle the scale-up of Chemical Looping Processes, the production of efficient and affordable oxygen carriers appears of paramount importance. Ilmenite is an ore-derived oxygen carrier which can be considered surely abundant and cheap. The preparation and the characterization of its reactivity are presented in the following paper. The paper describes briefly the performance of ilmenite relating it to other oxygen carriers, its thermodynamic properties, the kinetics and its use with fuels (solid, liquid and gaseous, including biofuels). Key features for an oxygen carrier are represented by costs and environmental sustainability, oxygen transport capacity and reactivity, as well as specific issues related to its use in fluidized bed reactors, namely agglomeration and attrition behavior. In addition, information about mutual interaction with fuel, considering also the influence of impurities, coke deposition or its effect on the gasification rate of solid fuels, is reported. [ABSTRACT FROM AUTHOR]