Reforming of biogas to hydrogen: a multi-criteria thermodynamic investigation Fabio De Rosa 1 , G. McCullough 2 , D. Rooney 1 , B. Smyth 2 , A. Goguet 1 1 School of Chemistry and Chemical Engineering, CenTACat, Queen’s University Belfast 2 School of Mechanical and Aerospace Engineering, Queen’s University Belfast Linkoping, 7 th September 2016
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Reforming of biogas to hydrogen: a multi-criteria
thermodynamic investigation
Fabio De Rosa1, G. McCullough2, D. Rooney1, B. Smyth2, A. Goguet1
1 School of Chemistry and Chemical Engineering, CenTACat, Queen’s University Belfast2 School of Mechanical and Aerospace Engineering, Queen’s University Belfast
Linkoping, 7th September 2016
Content
INTRO
OBJECTIVES
METHODOLOGY
RESULTS
CONCLUSIONS
FUTURE WORKS
Intro
01
Diesel/Stirling enginePEM fuel cell
1-3kW electrical (residential applications) Combined heat and power generation; Carbon savings; Feed-in tariffs.
Decentralized hydrogen production
Intro
01
The use of hydrogen for energetic purposes could lead to sustainable and more secure energy supplies [1]
Decentralized hydrogen production
Diesel/Stirling enginePEM fuel cell
[1] F. Mueller-Langer, E. Tzimas, M. Kaltschmitt, S. Peteves, International Journal of Hydrogen Energy, 32 (2007) 3797-3810
Intro
01
Small-scale reforming technologies (less capital investment); Refuelling unit tailored to the refuelling site requirements; Reforming unit located at the refuelling site (no extensive H2 delivery infrastructure); No need for H2 storage (very light and flammable gas).
Decentralized hydrogen production
Diesel/Stirling enginePEM fuel cell
Intro
02
Decentralized hydrogen production
• The most economical way to obtain hydrogen as an energy vector is steam reforming of methane/natural gas;
• there is a great interest about auto-thermal reforming and dry reforming of methane/biogas (for practical applications H2O and/or O2 have to be added to the reaction mixture)
Intro
02
Decentralized hydrogen production
• Carbon accumulation on the catalyst surface;• C-H bond is very stable and difficult to be activated (800-1000°C);
High costs associated; Sintering of the catalyst; Exergy lost due to combustion in the heating stage [2]
[2] A.P. Simpson, A.E. Lutz, International Journal of Hydrogen Energy, 32 (2007) 4811-4820
Intro
03
Mixed reforming of natural gas/biogas
Objectives
04
Issues:
Complex network of reactions;
Carbon deposition leading to catalyst replacement;
Up to two thirds of the overall cost of hydrogen production are for feed,
fuel and utilities [3].
Costs and carbon deposition can be lowered by selecting processes and
catalysts which allows low cost feedstock and by selecting optimum
process conditions giving low energy consumption
[3] W. Winter-Madsen, H. Olsson, Haldor Topsøe A/S, Denmark (online)
Problems statement
Objectives
05
To investigate the effect of operating conditions on the energy
requirements, carbon formation and the equilibrium composition of
hydrogen-rich gas produced via mixed reforming of biogas.
Parameter optimization: O2/CH4, H2O/CH4, CO2/CH4, Temperature
• Coke formation not always considered;
• One dimensional analysis (one criteria at a time);
• No Water-Gas Shift stage;
• Narrower ranges investigated;
• First-time application of the MCDM techniques as operating conditions optimization tool
Objectives
06
Mixed reforming of biogas: literature review
Methodology
Thermodynamic simulations
07
- THTS=325°C;
- TLTS=250°C;
- EquilibriumSRM:CH4, H2O, CO, H2, CO2, C(s)
- EquilibriumSHIFT:CO, H2, CO2, H2O
- Basis: 1 mol s-1 CH4
- TSRM=300-1200°C;
- P=1atm;
- EoS=Peng-Robinson;
- Air=79%N2, 21%O2;
- TH1=120°C;
Methodology – MCDM techniques
08
Technique for Order Preference by Similarity to the Ideal Solution
(TOPSIS)
• Alternatives are ranked according to the closeness to the Positive Ideal Solution (C*);
• At the PIS all the benefit criteria are maximized and the costs minimized;
• It needs information about the relative importance of the criteria (weights)
Methodology – MCDM techniques
09
Entropy method
• Used to determine the objective weights of the indexes for MCDM problems ;
• It measures the quantity of useful information provided by data itself (width of data
This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement n. 316838
Project coordinated by the QUESTOR Centre at Queen’s University Belfast www.qub.ac.uk/questor
Results
20
Experimental results: catalysts screening
TFR:100 sccm, 60% CH4, 40% CO2, GHSV:50,000 mL gcat-1 h-1