Refractory Wear During Gasification

Larry Baxter1, Shrinivas Lokare1, Humberto Garcia2, Bing Liu1

Clearwater Coal Conference

Clearwater, FL

June 2, 2009

Gasification in the Literature

Research by Country

Levelized Cost of Power

GE Energy Radiant

Coal

Cryogenic Oxygen

Slag/Fines

Water

High Pressure

Steam

Radiant Syngas Cooler

Radiant Quench Gasifier

SyngasScrubber

Solids

Saturated Syngas 398OF

Quench Chamber

2,500OF

1,100OF

419OF

Coal

Cryogenic Oxygen

Slag/Fines

Water

High Pressure

Steam

Radiant Syngas Cooler

Radiant Quench Gasifier

SyngasScrubber

Solids

Saturated Syngas 398OF

Quench Chamber

2,500OF

1,100OF

419OF

Coal Slurry63 wt.%

95% O2

Slag/Fines

Syngas 410°F, 800 Psia

Composition (Mole%):H2 26%CO 27%CO2 12%H2O 34%Other 1%H2O/CO = 1.3

Design: Pressurized, single-stage, downward firing, entrained flow, slurry feed, oxygen blown, slagging, radiant and quench cooling

To Acid Gas Removalor

To Shift

ConocoPhillips E-Gas™

Coal Slurry63 wt. %

Stage 2

95 % O2Slag

Quench

Char

Slag/Water Slurry

Syngas Syngas1,700°F, 614 psia

Composition (Mole%):H2 26%CO 37%CO2 14%H2O 15%CH4 4%Other 4%H2O/CO = 0.4

(0.78)

(0.22)

Stage 12,500 oF614 Psia

To Fire-tube boiler

Design: Pressurized, two-stage, upward firing, entrained flow, slurry feed, oxygen blown, slagging, fire-tube boiling syngas cooling, syngas recycle

To Acid Gas Removalor

To Shift

Shell Gasification

Syngas350°F, 600 Psia

Composition (Mole%):H2 29%CO 57%CO2 2%H2O 4%Other 8%H2O/CO = 0.1

DryCoal

Design: Pressurized, single-stage, downward firing, slagging, entrained flow, dry feed, oxygen blown, convective cooler

Convective CoolerSoot Quench& Scrubber

95% O2 HP Steam

650 oF

Steam

Source: “The Shell Gasification Process”, Uhde, ThyssenKrupp Technologies

Syngas Quench2

To Acid Gas Removalor

To Shift

HP Steam

Slag

Gasifier2,700 oF615 psia

Transient Model Formulation

……

Gas

and

Par

ticle

Flo

w D

irect

ion

1

2

n

N -1

N

123 … …m M

gasi

fier

wall

slag/ash

… …m M

… …m M

… …m M

… …m M

……

Gas

and

Par

ticle

Flo

w D

irect

ion

1

2

n

N -1

N

123 … …m M

gasi

fier

wall

slag/ash

… …m M

… …m M

… …m M

… …m M

part

icle

traj

ecto

ry

Simulation – Gas Phase

Simulation – Gas Phase

Efficiency Calculation

Impaction Efficiency Improvement

1321 )()()(1)( aStkdaStkcaStkbStk

  a b c dPotential Flow 0.1238 1.34 -0.034 0.0289Viscous Flow 0.0868 1.9495 -0.457877 -0.047

Corrosion potential

K Cl

S

Si Ca Fe

Chlorides condensation is a major step in corrosion initiation

Complex Inorganic Chemistry

Complex Inorganic Chemistry

Mole Fraction SiO 2

Tem

per

atu

re /C

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 11100

1300

1500

1700

1900

Allen & SnowSchuhmann & EnsioBowen & SchairerGreig

2 Liquids

Cr

Tr

Liquid

Fe 2

SiO

4

1205 ˚C

1928 ˚C

Al2O3-CaO-SiO2 Chemistry

0.2 0.3 0.41340

1360

1380

1400

1420

1440

1460

Me

ltin

g P

oin

t (oC

)

CaO Weight Fraction

Liquid

Solid

Al2O3/SiO2 = 0.34

Refractory-Slag Model

Syngas Tsyn Forced Convection Radiation

Air Tair Free Convection Radiation

Refractory

Slag

Deposited Ash

Steel Shell

Slag Importance

1300 1350 1400 1450 1500 1550 16000.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

Corr

osi

on R

ate

(m

m/h

r)

Temperature (oC)

With Slag Flow Without Slag Flow

Refractory Wear with Time

0.8

0.6

0.4

0.2

0.0

0.00 0.04 0.08 0.12 0.16 0.20 0.24

1000hr

1500hr

Refractory Wear Depth (m)

L (

m)

500hr

0.1 0.2 0.3 0.4 0.5 0.61000

1200

1400

1600

1800

2000

Slag Cold-face Temperature

Solid Region

Melti

ng T

em

pera

ture

(oC

)

CaO Weight Fraction

Liquid Region

Sensitivity to CaO content

0.1 0.2 0.3 0.4 0.5 0.60.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

Corr

osi

on R

ate

(m

m/h

r)

CaO Weight Fraction

Refractory Chemical Corrosion

1440 1460 1480 1500 1520 15400.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

Co

rro

sio

n R

ate

(m

m/h

r)

Temperature (oC)

0.1kg/m2s

0.2kg/m2s

Spalling Mechanisms

Overall Refractory WearChemical dissolution rates depend in complex ways on diffusivities, viscosities, chemical reactions, and temperature.

Spalling mechanisms and rates are not well understood, with quantitative models being mostly empirical.

Net dissolution rates disproportionately depend on minor slag and refractory components, involving complex inorganic chemistry.

Spalling Mechanisms

Spalling

Corrosion

Spalling Mechanisms

1

234

56

Chemistry (weight %)

Point

1 2 3 4 5 6

- Al 6.9 27.3 1.7 2.8 7.5 5.7

- Si 23.9 0.2 0.1 0.1 40.2 3.8

- Fe 20.8 31.7 23.6 0.2 1.5 0.5

- Ca 1.5 - - - 0.5 -

- Cr 0.1 1.5 42.7 62.1 1.5 53.0

Crystalline Phases hercynite, fayalite, enstatite, Iron sulfide, iron cordierite, hermatite

iron-alumina spinel

iron-chrome spinel

Chromia/alumina solid solution Fe-depleted slag Al build-up with Si

Refractory/Slag Profile

Distance from Hot Face (mm)

Bulk Chemistry (wt pct) X-Ray Crystalline Phases

Cr2O3 Al2O3 SiO2 CaO Fe

H.F. to 2.3 80.0 10.8 5.4 0.3 1.6 P= Cr2O3

Tr=M*Cr2O4

6.9 84.2 10.2 3.9 0.3 0.4 P= Cr2O3

Tr=M*Cr2O4

11.4 83.9 10.7 3.2 0.4 0.4 P= Cr2O3

Tr=M*Cr2O4

34.3 83.5 10.4 2.8 0.6 0.4 P= Cr2O3

43.3 83.9 9.3 2.3 0.5 0.2 P= Cr2O3

52.7 85.7 10.5 0.9 0.2 0.2 P= Cr2O3

57.2 86.1 10.5 0.2 0.0 0.2 P= Cr2O3

127 87.4 9.4 0.2 0.2 0.2 P= Cr2O3

Conclusions

• Chemical dissolution and spalling account for most refractory wear.

• Both mechanisms depend on temperature, slag/refractory composition, and slag flow rates, approximately in that order.

• Temperature dependence arises from both transport and solubility issues.

• Both immersion and spinning cup analyses provide good corrosion information, but neither simulates practical systems.

• Temperature, not peak deposition rates, determine maximum corrosion location.

Acknowledgements

• PhD and post-doc students Shrinivas Lokare, Bing Liu developed many of the submodels.

• Partial financial support from U.S. Department of Energy contract DE-AC07-05ID14517 and from corporate sponsors.