Thermochemical Studies of Relevance for Black Liquor Combustion and Gasification - The System Na 2 CO 3 -Na 2 S Anders Larsson, Gustav Lindberg, Anders Nordin, Dan Boström, Björn Warnqvist, Erik Rosén, Rainer Backman * Energy and Process Technology, University of Umeå, SE-901 87 Umeå * Åbo Akademi, Process Chemistry Group Mathias Råberg Contents I. Research program (Black Liquor Gasification) II. Uncertainties in thermochemical data III. Phase diagram studies - Na 2 CO 3 -Na 2 S IV. Conclusions V. Future work -----------On-going projects------------ VI. Uncertainties in thermochemical data VII. Thermochemical equilibrium studies
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Thermochemical Studies of Relevance for Black Liquor
Combustion and Gasification - The System Na2CO3-Na2S
Anders Larsson, Gustav Lindberg, Anders Nordin, Dan Boström,
Björn Warnqvist, Erik Rosén, Rainer Backman*
Energy and Process Technology, University of Umeå,SE-901 87 Umeå
A series of HT-XRD diffraction patterns of pure Na2CO3 in the temperature interval 25-800 ºC
HT-XRD results
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Na2S (25 °C) Lin (Cps)
0
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2θ-Scale 23 30 40 50 60 70 80 90
Diffraction pattern of pure Na2S at 25 ºC
0
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23 28 33 38 43 482θ-Scale
T (C
)
Pure Na2CO3
XNa2S = 0.1
0
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23 28 33 38 43 482θ-Scale
T (C
)
Pure Na2CO3 Na2CO3 in mixture Na2S in mixture
XNa2S = 0.1
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23 28 33 38 43 482θ-Scale
T (C
)
Pure Na2CO3 Na2CO3 in mixture Na2S in mixture
XNa2S = 0.15
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23 28 33 38 43 48
2θ-Scale
T (C
)
Pure Na2CO3 Na2CO3 in mixture Na2S in mixture
XNa2S = 0.2
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Phase Diagram Na2CO3-Na2S
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0 0.2 0.4 0.6 0.8 1
XNa2S
T (o C
)
Na2CO3 Na2S
Phase Diagram Na2CO3-Na2S
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0 0.2 0.4 0.6 0.8 1
XNa2S
T (o C
)
HTM data Previous estimated data
Na2CO3 Na2S
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Phase Diagram Na2CO3-Na2S
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0 0.2 0.4 0.6 0.8 1
XNa2S
T (o C
)
HTM data HT-XRD dataPrevious estimated data
Na2CO3 Na2S
Phase Diagram Na2CO3-Na2S
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0 0.2 0.4 0.6 0.8 1
XNa2S
T (o C
)
Na2CO3 Na2S
Na2CO3(s) + Na2S(s)
Liquid
Na2S(s) + LNa2CO3(s) + L
Na2CO3(ss)
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IV. Conclusions
• Phase diagram studies:- HTM: Re-determination of liquidus lines and melting
points of the components were made
- HT-XRD: The extension of the Na2CO3(ss) solid solution in the Na2CO3-Na2S system was determined
V. Future work
• Other systems:- K2CO3-K2S
- Na2S-K2S
- Na2S-NaCl, K2S-KCl
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• Objective:
- Perform sensitivity analysis for the black liquor combustion/gasification chemistry in order to identify species with the most uncertain data and to compare the effect of these uncertainties with the variation in fuel and process variables
• Method:- Systematically performing chemical equilibrium
calculations (with H2S, COS, Na-gases, melting temperatures etc. as target/indicator variables) with uncertainties in thermochemical data included according to an extensive factorial design.
- A program that handles input/output files and changes inthermochemical data has been developed. The program uses ChemApp for equilibrium calculations.
Sensitivity analysisVI. Uncertainties in thermochemical data
Na2S(s)+CO2+H2O=Na2CO3(s,l)+H2Swith different data, pCO2 = 0.15 bar, pH2O = 0.20 bar