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Effect of Vanadium and Nickel Oxides on Effect of Vanadium and Nickel Oxides on PetcokePetcoke Ash/Slag Viscosity Under GasificationAsh/Slag Viscosity Under GasificationPetcokePetcoke Ash/Slag Viscosity Under Gasification Ash/Slag Viscosity Under Gasification
ConditionsConditions
Sarma V Pisupati*Sarma V. PisupatiAditi Khadilkar
John and Willie Leone Family Department f E d Mi l E i iof Energy and Mineral Engineering
EMS Energy Institute
Presented at
New Delhi, February 11-12, 2016
Presentation outline
• Introduction• Introduction• Differences between Pet coke and coal
• Inadequacies in predictive capabilities• Research objectives of this study• Experimental setup and samples used• Influence of Ni and V on the slag viscosityInfluence of Ni and V on the slag viscosity• Interaction mechanisms• S l i d f t di ti• Some conclusions and future direction
Gasification: A Commercial Realityy
Polk, FL Wabash, INNakoso, Japan Tianjin, China
Puertollano, SpainBuggenum, Netherlands Edwardsport, IN
Analysis of USDOE and other project reports indicated over 300 issues that needed to be solved for reliable operation.
Jamnagar, India"Reliance Industries' Jamnagar project...is
f th ld'one of the world's largest gasification projects, processing 9.8 million t/a
t l k fpetroleum coke from the adjacent Reliance refineries.“Power Magazine
Gasification of coal is growing in developing countries for chemicalscountries for chemicals
Source: Higman, C., State of Gasification Industry: Worldwide Gasification database 2014 Update, Gasification Technologies conference, Washington D.C., 2014
Gasifiers operational experience shows issues with availabilityissues with availability
IGCC availability is GCC a a ab y stherefore, the most important technical issue governing the success or failure of these plantsfailure of these plants.
Source: Barnes, Ian, Recent operating experience and improvement of commercial IGCC, IEA report 113/10, 2013
Petroleum coke as gasification feedstock is increasingis increasing
• The amount of petroleum coke, a by-p , yproduct of the oil refining industry, has been increasing and is expected to continue to increase.
• Due to low reactivity, high gasification t t i i d E t i d fltemperature is required. Entrained-flow gasification at high temperature and high pressure is more suitable for petroleumpressure is more suitable for petroleum coke gasification
• Ash of petroleum coke is mainlyAsh of petroleum coke is mainly composed of vanadium and nickel.
Petcoke availability
Source: http://www.Roskill.com/petcoke accessed on Jan 24, 2016
Composition of slag from coal and petcoke from entrained flow gasifier (Texaco) are differentg ( )
Coal PetcokeEastern Western Type A Type B
SiO2 52.1 42.0 4.4 40.6Al2O3 15.4 25.0 1.5 9.6Fe2O3 7 3 20 9 23 0 6 3Fe2O3 7.3 20.9 23.0 6.3CaO 17.4 9.5 7.5 1.4MgO 3.7 -- -- 2.4NiO 20 9 14 0NiO -- -- 20.9 14.0V2O5 -- -- 40.3 16.6Others 4.1 2.6 2.5 9.1Carbon% 9,5 9.7 0.5 0.9
Ash Fusibility, °FID 2120 2140 -- --
Source: Najjar, M. S., Groen, J.C., Craig, J.R., ACS Fuel Chemistry Div. Preprints, NY. August 1991ID 2120 2140
ST 2150 2210 -- --FT 2250 2430 >2700 >2700
y p , g
Rheological properties of petcoke slag need to be studiedneed to be studied
High viscosity Difficult to removeHigh viscosity – Difficult to removeLow viscosity- Refractory corrosionOperating conditions need to be selectedfor optimum viscosityfor optimum viscosity
Models for prediction of viscosity of coalslag are well developed. However, methodsg pto predict viscosity of petcoke slag needdevelopment.
FactSage is also-not an adequate tool forthis as Vanadium compounds not present inthe solution database. It predicted moresolid phase than actually presentsolid phase than actually present.
Source: Marc A. Duchesne et al., Flow behaviour of slags from coal and petroleum coke blends
Slag Viscosity
• Several methods of estimating or measuring the critical viscosity temperature of molten coal ash slagscritical viscosity temperature of molten coal ash slags have been developed over time:
• Empirical modeling based on ash cone fusion temperatures,Empirical modeling based on ash cone fusion temperatures,• Direct measurement of slag viscosity as a function of temperature,
and• Thermophysical modeling based on coal ash composition
P.Y. Hsieh et al. / Fuel Processing Technology 142 (2016) 13–26
Slag formation and ash fusion temperatures
• The AFT results only indicated the initial• The AFT results only indicated the initial deformation temperature (IDT) at 1300 °C, whereas slag formation already , g ystarted to take place from 1000 °C.
• An AFT analyses only supplies y y ppinformation on the temperature where a mass of material, enough to deform the t t f th t t t lstructure of the cone, starts to slag.
• The AFT also gives no information on the ti f th l b l th t i t
J.C. van Dyk et al. Fuel, 88 (2009) 67–74
properties of the slag below that point.
Recent study of synthetic slags did not show a good a good correlation between ST and Tcvg g
NETL (USDOE)
• Correlation between ST and HT with Tcv was found to be poor, with R2 values between 0.04 and 0.06.We observed a positive linear correlation between FT and Tcv, with a R2 value of 0.77.
P.Y. Hsieh et al. , Fuel Processing Technology, 142 (2016) 13–26
p• They also found that it was possible to fit a plane to the Tcv data, using the silica-to-alumina ratio
(S/A) and the iron(III) oxide equivalent (F) as independent variables (R2 = 0.96)
Kalmanovitch or Modified Urbain EquationModified Urbain Equation
Calculation Procedure
Kalmanovitch DP, Frank M. An effective model of viscosity for ash deposition phenomena. University of North Dakota Energy and Mineral Research CenterNorth Dakota, Energy and Mineral Research Center, Energy Foundation Conferences, Grand Forks; 1988. p. 89–10
Plastic Viscosity (Einstein-Roscoe equation)
• S.-H. Seok, S.-M. Jung, Y.-S. Lee, D.-J. Min, Viscosity of highly basic slags, ISIJ Int. 47 2007) 1090–1096• Mukherjee, A., Pisupati, S.V. “Inter-particle interactions in highly concentrated coal-water slurries and their effect on slurry viscosity",
Energy and Fuels, 2015, 29 (6), pp 3675–3683. • Mukherjee, A., Rozelle P. L., Pisupati, S.V. “Effect of Hydrophobicity on Viscosity of Carbonaceous Solids-Water Slurry", Fuel Processing
Technology, 2015, Vol. 137, pp 124-130.
Research Objectives
• To understand the effect of vanadium and nickel oxides on• To understand the effect of vanadium and nickel oxides on Petcoke slag viscosity
• To modify existing empirical correlations such as the Modified Urbain equation for prediction of viscosity of Petcoke slag.Urbain equation for prediction of viscosity of Petcoke slag.
Systematic variation of V and Ni based oxides using synthetic ash performedoxides using synthetic ash performed
Effect of V oxides Effect of Ni oxidesEffect of interaction between V and Ni
Effect of V2O3
between V and Ni oxides3 runs with
increasing V2O53 runs with increasing NiO content without3 runs with
increasing V2O3conversion. Containing both
5content, without NiO
NiO content, without V2O5
Containing both V2O5 and NiO
A baseline without any V or Ni oxides, containing other oxides in the same ratio was also used
Composition of slag samples used in the studythe study
SiO2 Al2O3 Fe2O3 CaO TiO2 K2O MgO Na2O SrO BaO MnO48 07 19 73 14 60 4 867 1 867 5 867 1 467 3 733 1 467 0 267 0 067Baseline 48.07 19.73 14.60 4.867 1.867 5.867 1.467 3.733 1.467 0.267 0.067
V2O5 NiO V2O3
0 35 0
Ratios studied
E l i d 0 35 0
35 0 0
0 25 0
25 0 020000
Example comparing measured viscosities of synthetic and real ash
25 0 0
0 15 0
15 0 0
8 75 26 2 010000
15000
ity (P
a.s)
8.75 26.2 0
17.5 17.5 0
26.2 8.75 024 9 8 75 1 300
5000
Visc
os
24.9 8.75 1.3021 8.75 5.25
13.1 8.75 13.1
1350 1400 1450
Sample Temperature (°C)BR_ASTM BR_syn ash
Several parameters that affect slag viscosity were consideredviscosity were considered
Chemical iti
TemperatureGaseous atmosphere
composition(Ni, V content)
atmosphere
Slag Viscosity
Si fNumber of
Oxidation
Size of crystals
Number of crystals
Oxidation state of phases
18
Methodology used for measurement of slag viscosity
S th ti h C t l Vi it
slag viscosity
Synthetic ash Preparation
Compact slag preparation Grinding of slag Viscosity
Measurement
Theta HT - Rotating Viscometer Specifications
4000Example of
• Maximum furnace temperature = 1600 ˚C
• Viscosity range possible =
Viscometer Specifications
2000
3000
cosi
ty (P
a.s)
pmeasurement data
Viscosity range possible 100 - 4 x 107 cP
• Any gaseous atmosphere or under vacuum 0
1000
1300 1350 1400 1450 1500V
isc
19
Temperature (˚C)
Viscosity Measurement ProcedureSteps involved in the measurement of slag viscosity
Loading slag sample into crucible Room Temperature CO-CO2 mixture
slag viscosity
Insert rotor into liquid1550 oC
CO CO2 mixture inserted into system after
purgingAround 1000 oC
Homogenization 1550 oC - 60 mins
Measurement1550 oC to 1300 oC
Remove rotore o e o o1550 oC
Drain liquid from rotor1550 oC - 25 mins
CoolRoom temperature
20
Reproducibility of the measurements was satisfactorywas satisfactory
1.00E+05
1.00E+04
1.00E+05s)
V17.5Ni17.5
1.00E+03
scos
ity (P
a.s
1.00E+01
1.00E+02Vis
1.00E+001300 1350 1400 1450 1500
Temperature (˚C)
V2O5 and NiO increase slag viscosity
100000
1000
10000
sity
(Pa.
s)
10
100
Vis
cos
1000
10 10 20 30 40
V2O5 content (%)100
osity
(Pa.
s)
1
10Vis
co
10 10 20 30 40
NiO content (%)
Changes in crystalline Ni and V phases
NaCaAl(SiO )VFeO3/Fe2O3
Fe2O3
V2O3
VFeO3/V2O3/Fe2O3
NaCaAl(SiO7)VFeO3/Fe2O3
VFeO3/V2O3/Fe2O3
S i lNiFeO4
FeV2O4 Ni(V2O6)
Fe3O4
Fe3O4/FeV2O4
2 3
MagnetiteNiO NiO
SpinelSpinel
SEM-EDX supports the formation of V-Fe compounds at high V2O5 contentsat high V2O5 contents
V35Ni0
SEM-EDX supports the formation of Ni-Fe compounds at high NiO contentscompounds at high NiO contents
V0Ni35
SEM-EDX supports the interaction between V and Ni phasesp
V17 5Ni17 5V17.5Ni17.5
Image analysis shows fewer larger crystals as V content increasescrystals as V content increases
V35Ni0V0Ni35
V Ni Crystal count Average crystal size
V35Ni0V0Ni35
35 0 1893 4326.5 8.75 971 15317 5 17 5 3667 2917.5 17.5 3667 298.75 26.5 3776 350 35 3689 18
Combination of oxidation state of phases, number and size of crystals determines viscositynumber and size of crystals determines viscosity
Viscosit increases ith higher V content sinceViscosity increases with higher V content since-• V2O5 Ni(V2O6) V2O3FeV2O4 VFeO3
F O F O• Fe3O4 Fe2O3
• Increase in crystal size in spite of decrease in number
Viscosity increases with higher Ni content since-• Number of crystals increases although they are smaller
Effect of addition of vanadium and nickel
Source: Wang et al., Fuel Processing Technology,136, 2015,Pages 25–33
T250 value increased with increasing Ni and V contentand V content
1440
y = 4 9368x + 1287 81420
y = 3.6486x + 1284.6R² = 0.8509
1380140014201440
y = 4.9368x + 1287.8R² = 0.9984
1360
1380
1400
T25
0
132013401360
T25
0
1300
1320
1340
360
126012801300
0 10 20 30 40
1280
1300
0 10 20 30NiO content (%)
0 10 20 30 40V2O5 content (%)
NiO content (%)
Experimental data was fitted to obtain effect of V and Ni content individuallyeffect of V and Ni content individually
250y = 0.1983x2 + 2.108x + 17.334
R² = 1
150
200
sity
(Pa.
s)
50
100
Vis
cos
0 7462 2 0 949 17 334500
00 10 20 30
V2O5 content (%)
y = 0.7462x2 - 0.949x + 17.334R² = 1
300
400
y (P
a.s)
100
200V
isco
sity
00 10 20 30
NiO content (%)
Interaction between Ni and V phases led to a viscosity higher than predicted based on individual effectshigher than predicted based on individual effects
V2O3 V2O5 NiMeasured Viscosity
Calculated values
Ratio of measured to calculated viscosity
0 0 0 17.33 17.33 1.00 15 0 93.58 93.57 1.00 25 0 194 194 1.00 0 0 17 33 17 33 1 00 0 0 17.33 17.33 1.00 0 15 171 171 1.00 0 25 460 460 1.00 17.5 17.5 1280 344.20 3.720 26 8 400 263.69 1.51
P k d Oh t di d th i it f K th it l hi h t i l ti f diPark and Oh studied the viscosity of Korean anthracite slag, which contains a large portion of vanadium trioxide (V2O3). They observed that, in order to keep the slag flowing, the temperature had to be kept above 1,670 °C, which is 270 °C above the typical operating temperature for slurry-feed gasifiers.Park, W.; Oh, M.S. Slagging of petroleum coke ash using Korean anthracites. J. Ind. Eng. Chem. 2008, 14, 350–356.
Conversion to V2O3 increases viscosity before a decreasebefore a decrease
8000020 % i t V2O34000
5000 5 % conversion to V2O3
40000
60000
y (P
a.s)
20 % conversion to V2O3
2000
3000
4000
osity
(Pa.
s)
0
20000
Vis
cosi
ty
0
1000
1200 1300 1400
Vis
co
T (˚C) 1200 1300 1400Temperature (˚C)
4000
5000
s)
50 % conversion to V2O3
Temperature (˚C)
V2O5- 26.25 %, NiO – 8.75%1000
2000
3000
scos
ity (P
a.s
0
1000
1200 1300 1400
Vi
Temperature (˚C)
V2O3 increases viscosity up to a certain concentration with higher number of crystalsconcentration with higher number of crystals
2000
2500
s)1000
1500
2000
isco
sity
(Pa.
0
500
0 5 10 15
Vi
V2O3 (%)
CrystalAvg.
crystal
V2O3 content (%)
V2O3 V2O5 NiCrystal count
crystal size T250 (˚C)
1.3 24 8.75 2745 48.6 1404
5.25 21 8.75 4802 55.6 1427
13.1 13.1 8.75 2072 59.2 1414
Molten Silicate Slag
Covalent polymeric networksCovalent polymeric networks found in molten silicates. SiO4 tetrahedrons are linked by bridging oxygens to form a wide range of structures. The presence of cationic network modifiers breaks down the network, forming non-bridging oxygens to maintainnon bridging oxygens to maintain overall charge balance. The decrease in degree of polymerization leads to a d i i itdecrease in viscosity.
(alkali metal oxides, alkaline earth metal oxides or transition metal oxides.)
Calculation of change of exponent with increasing V content to modify Urbain equationincreasing V content to modify Urbain equation
200
250
300
.s)
V080000
100000
.s)
V15
y = 3E+10e-0.014x
R² = 0.9577
100
150
200
isco
sity
(Pa. y = 3E+37e-0.058x
R² = 0.9636
20000
40000
60000
isco
sity
(Pa.
0
50
1300 1400 1500 1600
Vi
Temperature (˚C)
0
20000
1300 1400 1500 1600
Vi
Temperature (˚C)
2E+42 0 066x60000
80000
.s)
V25
y = 2E+25e-0.034x1500000
2000000
.s)
V35
y = 2E+42e-0.066x
R² = 0.9042
20000
40000
isco
sity
(Pa. y 2E+25e
R² = 0.9325
500000
1000000is
cosi
ty (P
a.
0
0000
1300 1400 1500 1600
Vi
Temperature (˚C)
0
500000
1300 1400 1500 1600
Vi
Temperature (˚C)
Modification of exponent in Urbain equation
0 5 10 15 20 25 30
0 02
-0.01
00 5 10 15 20 25 30
V exponent
y = 9E-05x2 - 0.0042x - 0.014R² = 1
-0.04
-0.03
-0.02
Exp
onen
t
0 07
-0.06
-0.05
-0.07V content
Similar correlations can be developed using the cases with only Ni and Ni-V interaction But still need more data for good fits.
Some Preliminary Conclusions
• Ni and V content in slag increase slag viscosityg g y• V increased viscosity to a greater extent than Ni• Reduction of V phases with oxidation of Fe phases and increase inp p
crystal size contribute to viscosity increase• Number of crystals increase with increasing NiO content therebyy g y
increasing slag viscosity• Interaction occurs between V and Ni phases and leads to a further
increase in viscosity• Up to 20 % conversion of V2O5 to V2O3 increases viscosity with
increasing number of crystals
Future work for reliable operation of gasifiersgasifiers
• Attempts to modify the Urbain equation to predict petcoke slag• Attempts to modify the Urbain equation to predict petcoke slag viscosity have been initiated. They will be refined as more data is collected.
• Interactions of V and Ni with Fe, Si, and other basic oxides need to be examined to understand the effect of blending with gcoal or other niche fuels.
• The phase diagrams for these must be incorporated into FactSage thermodynamic database for more accurate predictions slag phases for Petcoke and blends of Petcoke
d land coal
