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Emissions from melted glass: experimental and theoretical approaches

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  1. Emissions from melted glass: experimental and theoretical approaches MAKAROV Pavel 2st year master student MSU Trainee in SGR: 18/03/2013 – 31/07/2013 Supervisors: BLAHUTA Samuel CONDOLF Cyril

  2. INTRODUCTION

  3. Key questions • What gaseous species are the most stable during volatilization of glass in Na-B-Si-O(-H) system according to literature data? • What thermochemical databases do we have? • Are current databases convenient for simulation of experimental processes?

  4. Summary of presentation • Literature survey on the most stable gaseous species in high temperature (1700 – 1800 K) region; • Volatilization experiments (binary, ternary glasses); • Thermodynamic simulation (FactSage) of the experiments; • Comparison of experimental results to FactSage simulation; • General conclusions; • Perspectives. 1 NaBO2, HBO2 (+NaOH) 2 3 4

  5. (1) NaBO2 (g): literature data, comparison to FactSage Cole et al., 1935 NaBO2 (g) partial pressure (log) Cable et al., 1987 Gorokhov et al., 1971 Nalini et al., 2008 Ivanov, 2002 1000/T, K-1 • Data for NaBO2 (g)weremodified (based on FactPS data); • New databaseFactTESTwascreated; Poor agreement of FactPS and experimental data In high temperature region

  6. (1) How to build new database? NaBO2 (l) ↔ NaBO2 (g) 1) Thermodynamic description ∆G = G(NaBO2(g)) – G(NaBO2(l)) = - RT lnKeq Keq = P(NaBO2(g))/a(NaBO2(l)) a(NaBO2(l))=1 _____________________________________ ∆G = G(NaBO2(g)) – G(NaBO2(l))=- RT lnP(NaBO2(g)) 2) Experimental description lg P = A + B/T FactSage (SLAGA) ? Literature data

  7. (1) NaBO2 (g): literature data, comparison to FactSage 2 B2O3 + Na2O NaBO2 (g)partial pressure (log) Cole et al., 1935 1000/T, K-1 FactTESTisalso efficient for Na2O/B2O3 system withdifferent compositions

  8. (1) HBO2 (g): literature data, comparison to FactSage 1000/T, K-1 B2O3(s) + H2O(g): HBO2 (g) partial pressure (log) 1960 FactPS: Good agreement to Knudsen effusion mass-spectrometricmethod data;

  9. (1) HBO2 (g): literature data, comparison to FactSage B2O3 (l) + H2O (g) = 2 HBO2 (g) Equilibrium constant (log) T, K FactPS: Good agreement for values obtainedfrom transpiration method;

  10. (1) HBO2 (g): literature data, comparison to FactSage 0.5 H2O (g) + 0.5 B2O3 (l or s) = HBO2 (g) y = x FactPScalculationresults in agreement withexperimental (Knudsen effusion method) atdifferent T;

  11. (1) Conclusions on thermodynamic databases? • thermodynamic functions for NaBO2 (g)modified; new database (FactTEST); • thermodynamic functions for HBO2 (g) – no change; still using FactPS.

  12. Summary of presentation • Literaturesurvey on the most stable gaseousspecies in high temperature (1700 – 1800 K) region; • Volatilizationexperiments (binary, ternary glasses); • Thermodynamic simulation (FactSage) of the experiments; • Comparison of experimentalresults to FactSage simulation; • General conclusions; • Perspectives. 2 3 4

  13. (2) Experimentalset-up • Conditions: T = 1475 °C, P(H2O) = 0,19 & 0,65 bar; • Glass: 1) binary (26 wt. % Na2O, 74 wt. % SiO2); 2) ternary (26 wt. % Na2O, 5 wt. % B2O3, 69 wt. % SiO2); Quartz fiberfilter Flacons withdeionized water

  14. Initial composition of glass (2) What changes during the experiment? Composition of glass changes during the experiment 5 series of solutions for eachhourwasanalyzedwith ICP

  15. (2) Analyses used, samplepreparation Ci in each solution Gas / melt composition on eachstep • ICP (for all solutions); • pH – measurments; • μprobe analyses; • SEM/EDS (additional); Verification of ICP & μprobe Final glass composition, concentration profiles Verificationμprobe

  16. Summary of presentation • Literaturesurvey on the most stable gaseousspecies in high temperature (1700 – 1800 K) region; • Volatilizationexperiments (binary, ternary glasses); • Thermodynamic simulation (FactSage) of the experiments; • Comparson of experimentalresults to FactSage simulation; • General conclusions; • Perspectives. 3 4

  17. (3) Thermodynamic simulation (FactSage) of volatilization experiments Qi = ΣQ(i elem) Input for FactSage ICP - output FactSage simulation comparison

  18. (3) Ternary glass: working assumption Na NaBO2 ICP: Ci in each solution Pj we want to calculate B HBO2 ICP resultrecalculation: Main assumption - NaOHamountisnegligible

  19. Summary of presentation • Literaturesurvey on the most stable gaseousspecies in high temperature (1700 – 1800 K) region; • Volatilizationexperiments (binary, ternary glasses); • Thermodynamic simulation (FactSage) of the experiments; • Comparison of experimentalresults to FactSage simulation; • General conclusions; • Perspectives. 4

  20. Na, Si (4) Binary glass: experiment vs FactSage 0,19 bar 0,65 bar NaOH (g)partial pressure (log) NaOH (g)partial pressure (log) Time ↑ Time ↑ FactSage simulation results are close to experimental points

  21. (4) Binary glass: experiment vs FactSage Na, Si μprobe SiO2 ICP µprobe Na2O • Flat profiles (µprobe) → it’s possible to recalculatemelt composition from ICP results; • Differsbetween w(Na2O) for ICP and for µprobe.

  22. Na, Si (4) Binary glass: experiment vs FactSage EDS Na Black particles Glass matrix ? Si O • Precipitationduringcooling of melt; • Precipitateabsorbs Na from glass matrix.

  23. Na, Si, B (4) Ternary glass: experiment vs FactSage T = 1475 °C

  24. Na, Si, B (4) Ternary glass: experiment vs FactSage ICP analysis FactTESTis not suitablebecause of problemswith mass balance at phase equilibriumcalculation (reason – G(T) for NaBO2 (g) in FactTEST)

  25. Na, Si, B (4) Ternary glass: experiment vs FactSage Cross section plotting

  26. Na, Si, B (4) Ternary glass: experiment vs FactSage NaBO2 HBO2 • FactPSresults are in agreement with ICP for NaBO2 (g); • Differs for HBO2 (g) at 0,65 bar: • Possible reasons: - not all condensatewascollected in experiments; • - deffects of thermodynamic glass model in FactSage.

  27. (4) Ternary glass: experiment vs FactSage Na, Si, B μprobe SiO2 B2O3 ICP µprobe Na2O • Flat profiles (µprobe); • Differs (lessthan for binary glass) between w(Na2O) for ICP and for µprobe.

  28. Na, Si, B (4) Ternary glass: experiment vs FactSage EDS Black particles Glass matrix Na Si O • Precipitationduringcooling of melt; • Precipitateabsorbs Na from glass matrix.

  29. (4) Industrial glass (SGR, 2009) Insulation glass (wt. %): SiO2 = 65.6 Al2O3 = 2 B2O3=4.3 CaO=8 MgO=2.7 Na2O (+K2O)=17.0 (K2O=0.6 put as Na2O) T = 1475 °C, P(H2O) = 0,19 bar

  30. (4) Industrial glass (SGR, 2009) 1) FactPScanbeapproached for experiment simulation; 2) FactTESTis not suitable.

  31. (4) Industrial glass (SGR, 2009) NaBO2 HBO2 The same magnitudes for Pilike in ourexperiments → Differs for HBO2 (g) for ternary glass at 0,65 bar couldbeexplained by problems of theoretical glass model in FactSage;

  32. Summary of presentation • Literaturesurvey on the most stable gaseousspecies in high temperature (1700 – 1800 K) region; • Volatilizationexperiments (binary, ternary glasses); • Thermodynamic simulation (FactSage) of the experiments; • Comparison of experimentalresults to FactSage simulation; • General conclusions; • Perspectives.

  33. General conclusions • According to literature analysis: - Thermodynamic properties of NaBO2 (g) in FactPSwere modified; - New FactTESTdatabasewascreated; - Properties of HBO2 (g) are in good agreement with literature data; • Volatilization experiments were carried out; • FactTESTcan not be used for real experiment simulation; • Initial database FactPS was recommended to be used for experiment optimizing.

  34. PERSPECTIVES 1434°C • Verification of Tboiling of pure NaBO2 (g) (literature – 1434°C, FactPS – 1757°C); • Check SLAG database on data correctness, creating new database/ new solution model for glass melt in Na2O-B2O3-SiO2 system; 1757°C NaBO2 (g) partial pressure (log) 1000/T, K-1