Experimental Analysis of SOFC Fuelled by Ammonia

In this study, ammonia is presented as a feasible fuel for solid oxide fuel cells (SOFCs). Ammonia has several interesting features as fuel due to low-production cost, high-energy density and, focusing on fuel cells and hydrogen application, ammonia is an excellent H2 carrier thanks to high value of volumetric and gravimetric densities. The paper reports experimental test performed to evaluate the feasibility of NH3 directly fed to a 50 cm2 single cell SOFC. A test plan was developed to compare pure ammonia with an equivalent mix of ammonia, nitrogen, and hydrogen and the study of temperature and voltage values strongly indicates that a two stage oxidation of ammonia can be predicted and a previous cracking reaction occurs in the cell due to the nickel catalytic contribution. The study of temperatures and of heat flows show how the cell is cooled down to lower temperature because of heat adsorbed by the reaction and by flow mix entering the anode. The study shows also how for operative temperatures below 800 °C the cracking reaction takes place in the cell active area. Efficiency test demonstrates that the cell can operate at 300 mW cm–2 and 30% efficiency based on ammonia LHV

Theoretical study and performance evaluation of hydrogen production by 200 W solid oxide electrolyzer stack

High temperature steam electrolyzers, taking advantage of high temperature heat, can produce more hydrogen by using less electrical energy than low temperature electrolyzers. This paper presents an experimental study on hydrogen production by using a 200 W solid oxide stack working in reverse mode. A thermodynamic study of the process was performed by measuring the heat and mass balance of stack at different operating conditions. Different definitions of efficiency were used to highlight the limit and potential of the process. The I–V curve, the flow rate measurements and the GC analysis on outlet flows were used to calculate the hydrogen and oxygen productions. In addition, the influence of steam dilution, water utilization and operating temperature on conversion efficiency and stack's thermal balance was evaluated. With this aim, the tests were performed at three operating temperature (700 °C, 750 °C and 800 °C) over a range of steam inlet concentration from 50% to 90% and water utilization up to 70%. The hydrogen and oxygen flows produced by electrolysis, at different loads, were directly measured after water condensation: net flows up to 2.4 ml/(min cm2) of hydrogen and 1.2 ml/(min cm2) of oxygen were measured and compared to the theoretical ones, showing a good agreement

Sulphur compounds removal from natural gas using porous materials for high temprature fuel cell applications

Sulfur compounds present as odorants in natural gas like thiophenes,mercaptans,and sulifdes, cuase severe poisoning on high tempreature fuel cell catalysts evev at very low concentration, below 1 ppm. Therefore a deep sulpfur removal from inlet gas mixture is strongly needed and it has to be coupled with an accurate determination of sulfur concentration in the gas stream. Among the different developed filtering solutions, adsorption using porous materials represents a very attractive option, mainly in view of systems simplicity and costs. In this work, adsorptive removal of organic and inorganic sulfur compounds was carried out ina fixed bed floew reactor, using different types of porous materials, such as virgin and impgregnated activated carbons and zeolites. The purpose was to evaluate sorbet capacity of singulkra adsorbents varying process paramaters such as space velocity. The sorbents display differences in adsorpitve capacity among the individual sulfur compounds in natural gas: a comparison among odorants and H2S adsorption is in particular shown. A composite sorbent was realized and tested in order to exploit the selectivity of singular adsorbent materials

EXPERIMENTAL ANALYSIS OF SOFC FUELLED BY AMMONIA

Ammonia (NH3) has very interesting features as fuel for solid oxide fuel cell (SOFC). This study presents preliminary experimental results on a single cell SOFC fueled by ammonia. The study focuses on the cracking reaction that permits to transform ammonia into N2 and H2. This reaction offers to the fuel cell a perfect mix for the operation in safety and efficient conditions. The study compares several polarization curves realized with pure H2, a mix of H2/N2 and a mix of H2/NH3 and pure NH3 at high operation temperature (800°C). The results show how a complete reaction of NH3 can be predicted and an equivalent performance can be obtained substituting the H2/N2 mix with equivalent amount of ammonia

EXPERIMENTAL TEST OF CARBON CAPTURE FROM COGENERATION PLANT WITH MCFC COUPLED

Molten carbonate fuel cells are natural CO2 separators and concentrators. In this work we analyze a single MCFC behavior feeds with a mixture simulating a cogeneration power plant exhaust gas, so to replicate the coupling with a real plant. The main aim of this work is to understand the MCFC performances, its capability and efficiency to separate CO2, its dependence from critical parameters such as the cathodic carbon dioxide concentration (XCO2) and utilization (UCO2), as well as the partial pressure ratio between oxygen and carbon dioxide (PO2/PCO2) in addition to other derived parameters as the oxygen concentration (XO2), utilization (UO2) and the total cathodic flow rate (Qcat). In particular, in the cathodic section, the carbon dioxide concentration is critical at low values and can both induce quick voltage drop and make the cell sensitive to the other parameters otherwise not so decisive

Experimental test of carbon capture from cogeneration plant with MCFC coupled

Molten carbonate fuel cells are natural CO2 separators and concentrators. In this work we analyze a single MCFC behavior feeds with a mixture simulating a cogeneration power plant exhaust gas, so to replicate the coupling with a real plant. The main aim of this work is to understand the MCFC performances, its capability and efficiency to separate CO2, its dependence from critical parameters such as the cathodic carbon dioxide concentration (XCO2) and utilization (UCO2), as well as the partial pressure ratio between oxygen and carbon dioxide (PO2/PCO2) in addition to other derived parameters as the oxygen concentration (XO2), utilization (UO2) and the total cathodic flow rate (Qcat). In particular, in the cathodic section, the carbon dioxide concentration is critical at low values and can both induce quick voltage drop and make the cell sensitive to the other parameters otherwise not so decisive

Carbon capture with molten carbonate fuel cells: Experimental tests and fuel cell performance assessment

Molten carbonate fuel cells (MCFCs) may operate as CO2 separators and concentrators while generating electric power, being thus a very interesting candidate to be used as carbon capture systems in fossil fired power plants.The main aim of this work is to understand the MCFC performance, its potential and efficiency to separate CO2 from the exhaust gas of fossil fired power plants and the effect of critical parameters such as the cathodic carbon dioxide concentration (XCO2) and utilization (UCO2), as well as the partial pressure ratio between oxygen and carbon dioxide (PO2/PCO2) and other parameters such as the oxygen concentration (XO2), utilization (UO2) and the total cathodic flow rate (Qcat). This was achieved by studying the experimental behaviour of a single MCFC when it is fed with a mixture simulating the composition of the exhaust gases of a combined heat and power plant, in order to point out potential limitations in the fuel cell operating conditions.In particular, the carbon dioxide concentration in the cathodic section was shown to be a critical factor at low values, that can both induce quick voltage drops and make the cell sensitive to the other parameters, which are otherwise not so important

CHARACTERIZATION OF 100W SOFC STACK FED BY CARBON MONOXIDE RICH FUELS

The rapid growth in terms of efficiency and performance of the solid oxide fuel cell (SOFC) technology in recent years has led SOFC to be one of the possible solutions for the exploitation of different types of fuels obtained from fossil or renewable sources. A lot of processes, such as waste incineration or anaerobic digestion, during operation produce exhaust gases that can be efficiently exploited in SOFC systems. SOFCs, thanks to their operating condition, run with standard fuels such hydrogen and methane as well as fuel waste gas, like biogas or landfill gas, or gas plant, like pyrogas. The aim of this work is to compare the performance of an 100W stack SOFC when it is fed by different fuel compositions