Emissions from melted glass: experimental and theoretical approaches

MAKAROV Pavel2st year master student MSU

Trainee in SGR: 18/03/2013 – 31/07/2013

Supervisors: BLAHUTA Samuel

CONDOLF Cyril

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INTRODUCTION

2

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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?

3

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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.

Summary of presentation

4

NaBO2, HBO2 (+NaOH)1

2

3

4

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5

Poor agreement of FactPS and experimental dataIn high temperature region

• Data for NaBO2 (g) were modified (based on FactPS data);• New database FactTEST was created;

NaB

O2

(g) p

arti

al p

ress

ure

(l

og

)

1000/T, K-1

(1) NaBO2 (g): literature data, comparison to FactSage

Cole et al., 1935

Cable et al., 1987 Gorokhov et

al., 1971

Nalini et al., 2008

Ivanov, 2002

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(1) How to build new database?

NaBO2 (l) ↔ NaBO2 (g)

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∆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))

1) Thermodynamic description

2) Experimental descriptionlg P = A + B/T

Literature dataFactSage (SLAGA)

?

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(1) NaBO2 (g): literature data, comparison to FactSage

7FactTEST is also efficient for Na2O/B2O3 system with

different compositions

NaB

O2

(g) p

arti

al p

ress

ure

(l

og

)

1000/T, K-1

2 B2O3 + Na2O

Cole et al., 1935

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(1) HBO2 (g): literature data, comparison to FactSage

8

FactPS: Good agreement to Knudsen effusion mass-spectrometric method data;

HB

O2

(g) p

arti

al p

ress

ure

(l

og

)

1000/T, K-1B2O3(s) + H2O(g):

1960

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(1) HBO2 (g): literature data, comparison to FactSage

9

FactPS: Good agreement for values obtained from transpiration method;

Eq

uili

bri

um

co

nst

ant

(lo

g)

T, K

B2O3 (l) + H2O (g) = 2 HBO2 (g)

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(1) HBO2 (g): literature data, comparison to FactSage

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FactPS calculation results in agreement with experimental (Knudsen effusion method) at different T;

0.5 H2O (g) + 0.5 B2O3 (l or s) = HBO2 (g)

y = x

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(1) Conclusions on thermodynamic databases?

thermodynamic functions for NaBO2 (g) modified; new database (FactTEST);

thermodynamic functions for HBO2 (g) – no change; still using FactPS.

11

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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.

Summary of presentation

12

2

3

4

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(2) Experimental set-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);

13Flacons with deionized water

Quartz fiber filter

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(2) What changes during the experiment?

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Initial composition

of glass

Composition of g

lass

changes d

uring th

e

experim

ent

5 series of solutions for each hour was analyzed with ICP

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(2) Analyses used, sample preparation

ICP (for all solutions);

pH – measurments;

μprobe analyses;

SEM/EDS (additional);

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Ci in each solution

Final glass composition,

concentration profiles

Verification of ICP & μprobe

Verification μprobe

Gas / melt composition on each step

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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;

Comparson of experimental results to FactSage simulation;

General conclusions;

Perspectives.

Summary of presentation

16

3

4

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(3) Thermodynamic simulation (FactSage) of volatilization experiments

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ICP - output FactSage

simulation

comparison

Qi = ΣQ(i elem)

Input for FactSage

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(3) Ternary glass: working assumption

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ICP result recalculation: Main assumption - NaOH amount is negligible

Na

B

NaBO2

HBO2

ICP: Ci in each solution

Pj we want to

calculate

CONFIDENTIAL - Disclosure or reproduction without prior written permission of Saint-Gobain Recherche is prohibited.

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.

Summary of presentation

19

4

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(4) Binary glass: experiment vs FactSage

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0,19 bar 0,65 bar

Time ↑

NaO

H (g

) par

tial

pre

ssu

re

(lo

g)

Time ↑

NaO

H (g

) par

tial

pre

ssu

re

(lo

g)

FactSage simulation results are close to experimental points

Na, Si

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P (H2O) SiO2,

wt. %

Na2O,

wt. %

0.19 bar 73.2 16.8

0.65 bar 73.6 17.4

μprobe

SiO2

Na2O

(4) Binary glass: experiment vs FactSageNa, Si

ICP

µprobe

1) Flat profiles (µprobe) → it’s possible to recalculate melt composition from ICP results;

2) Differs between w(Na2O) for ICP and for µprobe.

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(4) Binary glass: experiment vs FactSage

22

?

EDS

1) Precipitation during cooling of melt;2) Precipitate absorbs Na from glass matrix.

Na, Si

Black particles

SiO

Na Glass matrix

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(4) Ternary glass: experiment vs FactSage

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Na, Si, B

T = 1475 °C

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(4) Ternary glass: experiment vs FactSage

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ICP analysis

FactTEST is not suitable because of problems with mass balance at phase equilibrium calculation (reason – G(T) for NaBO2 (g) in FactTEST)

Na, Si, B

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(4) Ternary glass: experiment vs FactSage

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Cross section plotting

Na, Si, B

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(4) Ternary glass: experiment vs FactSage

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NaBO2 HBO2

1) FactPS results are in agreement with ICP for NaBO2 (g);2) Differs for HBO2 (g) at 0,65 bar: Possible reasons: - not all condensate was collected in experiments;

- deffects of thermodynamic glass model in FactSage.

Na, Si, B

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27

μprobe

SiO2

Na2O

(4) Ternary glass: experiment vs FactSage

ICP µprobe

1) Flat profiles (µprobe);2) Differs (less than for binary glass) between w(Na2O) for ICP and for

µprobe.

Na, Si, B

P (H2O)

SiO2,

wt. %

B2O3,

wt. %Na2O,

wt. %

0.19 bar

72,9 1,6 19,8

0.65 bar

73,2 1,6 20,9

B2O3

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(4) Ternary glass: experiment vs FactSage

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EDS

1) Precipitation during cooling of melt;2) Precipitate absorbs Na from glass matrix.

Na, Si, B

Black particles

O Si

Na Glass matrix

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(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

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(4) Industrial glass (SGR, 2009)

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1) FactPS can be approached for experiment simulation;2) FactTEST is not suitable.

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(4) Industrial glass (SGR, 2009)

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NaBO2 HBO2

The same magnitudes for Pi like in our experiments → Differs for HBO2 (g) for ternary glass at 0,65 bar could be explained by problems of

theoretical glass model in FactSage;

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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.

Summary of presentation

32

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General conclusionsAccording to literature analysis:

- Thermodynamic properties of NaBO2 (g) in FactPS were modified;

- New FactTEST database was created;

- Properties of HBO2 (g) are in good agreement with literature data;

Volatilization experiments were carried out;

FactTEST can not be used for real experiment simulation;

Initial database FactPS was recommended to be used for experiment optimizing.

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PERSPECTIVESVerification 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;

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NaB

O2

(g) p

arti

al p

ress

ure

(l

og

)

1000/T, K-1

1757°C1434°C