Barbara Bosio

Modeling and experimentation of molten carbonate fuel cell reactors in a scale-up process

Modeling and experimental activities are presented for molten carbonate fuel cell electrochemical reactors, starting from the local kinetic study to the overall stack analysis. The inclusion of the micro-model of the electrode-kinetics in the macroscopic model and the study of the effects of gas cross-over phenomena through the electrolyte are among the original features of this work. The model gives new insights into the phenomenological behavior of the process. A good agreement between simulation and experimental results is presented and discussed.

Preliminary experimental and theoretical analysis of limit performance of molten carbonate fuel cells

The aim of this work is to investigate the limit performance of molten carbonate fuel cells due to gas diffusion phenomena in the porous electrodes when high reactant utilisation factors are used. Modelling and experimental activities are presented. An electrode kinetic micromodel has been performed accounting for the effects of the diffusion limits and has been integrated into a macromodel in order to optimise cell performance and operation. Specific tests have been carried out to identify the dependence of anodic as well as cathodic limiting current density on operating parameters using planar square cells produced by Ansaldo Ricerche (ARI). In turn, limiting current measurements have been used in order to identify overall reactant mass transfer coefficients in the complex structure of the electrodes. A good agreement between simulated and experimental results is presented and discussed.

Assessment of Molten Carbonate Fuel Cell Models and Integration With Gas and Steam Cycles

The aim of this work is to investigate the performance of molten carbonate fuel cells (MCFCs), with external sensible heat reformer and gas turbine/steam turbine (GT/ST) combined cycles. The analysis of these MCFC-GT/ST combined cycles has been carried out using the thermo economic modular program (TEMP) modified to allow MCFC, external sensible heat reformer, and catalytic burner performance to be carefully taken into account. The code has been verified through the use of a detailed MCFC model and of the data available for an existing MCFC unit. The thermodynamic and exergy analysis of a number of MCFC combined cycles is presented and discussed, taking into account the influence of technological constraints, also evaluated with the sophisticated model, and the influence of the post-combustion of the fuel directly in the external catalytic burner. The results are presented and discussed in depth.

Clean energy from sugarcane waste: feasibility study of an innovative application of bagasse and barbojo

Abstract Due to the existing difficulty of finding energy sources and reducing pollution, the use of renewable sources and highly efficient technologies for electrical energy production stands out as one of the promising solutions for the future. This paper shows the results of the combination of these two aspects, namely, a molten carbonate fuel cell system fed with biomass derived syngas. In particular, the biogas comes from bagasse and barbojo, the sugarcane residues. So far in developing countries they have been wasted or partly used with poorly efficient technology. The feasibility of such an application is studied by means of the process simulator Aspen Plus

Industrial experience on the development of the molten carbonate fuel cell technology

Abstract The development of the molten carbonate fuel cell (MCFC) technology at Ansaldo Ricerche (ARI) is reported, starting from small scale single cells up to stacks of several kW capacity. The evolution of material and fabrication strategies as well as the progress in terms of electrical performance are described and discussed. The data reported show that the MCFC technology has been successfully tested on stacks in the kW power class, however some problems still need to be solved to improve the stack performance. In particular, better control of the start-up phase, of electrolyte migration through the manifolds and of the gas feed distribution are required, based on the latest experimental data on a 50 cell stack with cell area 0.1 m 2 (cell active area 0.0702 m 2 ), which operated for 780 h with a maximum performance of 4 kW at 206 mA/cm 2 at 50% fuel utilisation. Future development steps, which will lead to the realisation and operation of systems of several hundred kW, are presented.

Deoxygenation of waste cooking oil and non-edible oil for the production of liquid hydrocarbon biofuels

Deoxygenation of waste cooking vegetable oil and Jatropha curcas oil under nitrogen atmosphere was performed in batch and semi-batch experiments using CaO and treated hydrotalcite (MG70) as catalysts at 400 °C. In batch conditions a single liquid fraction (with yields greater than 80 wt.%) was produced containing a high proportion of hydrocarbons (83%). In semi-batch conditions two liquid fractions (separated by a distillation step) were obtained: a light fraction and an intermediate fraction containing amounts of hydrocarbons between 72-80% and 85-88% respectively. In order to assess the possible use of the liquid products as alternative fuels a complete chemical characterization and measurement of their properties were carried out.

Optimisation of the cell shape for industrial MCFC stacks

Abstract The aim of this work is to compare Molten Carbonate Fuel Cell (MCFC) stack behaviour when square and rectangular cells are used, and to discuss the optimisation of their operating conditions. In particular, experimental data have been collected for a stack with square cells of 0.1-m 2 area to validate a stack simulation model; then, the effects of area increase of up to 0.75 m 2 have been predicted, proving the advantage of working with rectangular cells in order to obtain a better temperature and pressure drop management. Moreover, the operating conditions of a rectangular stack have been analysed and optimised when reformed natural gas, as well as coal gas, are used as fuel. The results presented and discussed have been used to guide design and operation of a rectangular stack constructed by Ansaldo Ricerche (ARI).

Concentration polarisation in heterogeneous electrochemical reactions: a consistent kinetic evaluation and its application to molten carbonate fuel cells

Aim of this work is to focus attention on how the concentration polarization, in all electrochemistry applications, is often formulated on the basis of only thermodynamic statements and how it should be written in a kinetic more consistent expression. Moreover, the application of this study to the analysis of molten carbonate fuel cell (MCFC) behaviour has been discussed with reference to diffusion limited operating conditions.

Modelling of flash and stripping phenomena in deaerators for seawater desalination

Abstract In this paper deaeration efficiency is studied and discussed with regard to a seawater desalination plant under construction in Ruwais (United Arab Emirates) for ADNOC (Abu Dhabi National Oil Company). In particular, a modelling activity has been performed in order to optimise deareator design. Seawater flashing and stripping have been investigated, and a simulation code has been set up taking account of mass, energy and momentum balances together with phase equilibrium conditions. Parametric studies have been carried out analysing the effects of seawater and stripping steam flow rates, as well as those of temperature, pressure, packing height and other operating conditions or deaerator geometrical characteristics. Different models have been discussed interpreting flash and stripping phenomena; and in the light of the results obtained, here shown and discussed, new solutions have been proposed to reduce the costs of the deaerator installation and management.

Experimental tests with rice straw on a square-based spouted bed reactor

Abstract A spouting bed reactor using rice straw as feedstock for further gasification purposes was studied in the present work. Experimental fluid dynamic tests were carried out in a conical square-based spouted bed reactor using a mixture of straw and silica, the latter acting as inert material. The influence of the initial bed of particles and the presence of coarse particles in the mixture on the pressure drop and minimum spouting velocity were evaluated. As a result, lower values of pressure drop along the bed were found compared to conventional fluidisation processes. Higher initial bed heights and higher percentage of straw in the mixture resulted in higher values of pressure drop and minimum spouting velocity. A new correlation for a cross section spouted bed reactor was proposed for the prediction of the minimum spouting velocity.