preliminary study among conventional pyrolysis and
TRANSCRIPT
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PRELIMINARY STUDY AMONG CONVENTIONAL PYROLYSIS AND CATALYTIC PYROLYSIS OF SEWAGE SLUDGE
M. Azuara*, N. Gil, P.Barcelona, I.Fonts and M.B.Murillo
Thermochemical Processes Group (GPT), Aragon Institute for Engineering Research (I3A), Zaragoza (Spain)
*: e-mail: [email protected]
Bioenergy III: Present and New Perspectives on Biorefineries
Lanzarote (Spain), May 24th, 2011
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 2
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 3
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IntroductionIntroduction and and objectivesobjectives
� The number of wastewater treatment plantshas increased during the last years, due tothe strict legislation (Directive 91/271/EEC).
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 4
Thermochemical processing of sewage sludge via pyrolysis comes up as an interesting alternative
It is necessary to find alternatives for management and valorization of sewage sludge
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IntroductionIntroduction and and objectivesobjectives
� In previous studies (*), pyrolysis of sewage sludge in a fluidized bedyielded a liquid fraction with two organic phases and an aqueous one.
� The organic phases contain a significant amount of triglycerides and fattyacids:– high contribution to the heating value of the liquids
– Viscosity and oxygen content are increased.
� γ-Al2O3 catalysts have shown a good performance in the decarboxylationof triglycerides and fatty acids (**,***)
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 5
* Fonts. I, Juan.A, Gea.G, Murillo.M.B, Sánchez. J. L., Ind. Eng. Chem. Res. 47 (2008) 5376-5385** Konar. S.K, Boocock, D.G.B., Mao, V., Liu, J., Fuel 73 (1994) 642-646
*** Vonghia.E, Boocock, D.G.B., Konar, S.K., Leung, A., Energy Fuels, 9 (1995)
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IntroductionIntroduction and and objectivesobjectives
Main objective:
To improve the properties of the sewage sludge pyrolysisliquid by means of an in-situ catalytic treatment
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liquid by means of an in-situ catalytic treatment
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 7
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 8
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MaterialsMaterials and and methodsmethods
� Anaerobically digested and dried sewage sludge supplied by a Spanishwastewater treatment plant (Madrid Sur (SSM)).
� Particle size: -500 +250 µm
Feedstock analyses
RawRaw material:material:
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Dried sewage sludge
Elemental analysis
Moisture Ash VolatilesFixed
Carbon
ISO-589-1981
ISO-1171-1976
ISO-5623-1974
By difference
wt % units 7.1 41.0 46.6 5.3
Ultimate analysis
C H N S O
ASTM D 5373
ASTMD 5373
ASTM D 5373
ASTM D 4239
By difference
wt % units 27.7 4.4 3.9 0.8 22.2
a The wt-% of hydrogen includes the hydrogen from moisture.
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� Activated γ-Al2O3
γ-Al O chemical composition
MaterialsMaterials and and methodsmethods
CatalystCatalyst::
• Calcined at 600 ºC• Surface area (BET): 142 m
2/g
• Average pore size: 10.5 nm• Volume of mesopores (BJH): 0.4 cm
3/g
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γ-Al2O3 chemical composition
Compound wt %
Al2O3 95.0 min
C 0.05 max
SiO2 0.035 max
Fe2O3 0.025 max
Na2O 0.005 max
TiO2 0.27 max
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MaterialsMaterials and and methodsmethods
Experimental Experimental systemsystem:: • Lab-scale fluidized bed (< 1 kg/h) • Feeding rate: 6 g/min of sewage sludge • N2 flow rate: 4.4 dm
3(STP)/min
• Atmospheric pressure• Continuous feed and ash removal• Hot filter + fixed bed downstream• Liquid condensation system:
• 2 condensers• Electrostatic precipitator
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MaterialsMaterials and and methodsmethods
Experimental Experimental conditionsconditions::
500500500Temperature fixed bed (ºC)
450450450Freeboard temperature (ºC)
550550550Bed temperature fluidized bed reactor (ºC)
321Experiment number
γ-AluminaInert SandBed constituent
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120120120Run time (min)
0.8WHSV (vapour mass flow/mass catalyst) (h-1)
194970Amount of catalyst (g)
1050Height of catalytic bed (cm)
1.21.21.2Gas residence time FBR (s)
500500500Temperature fixed bed (ºC)
1.7
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 13
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 14
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ResultsResults
51,0 51,2 53,0
33,6 30,4 26,4
15,4 16,7 17,6
0,0 1,7 3,0
40%
60%
80%
100%
wt
% o
f e
ach
pro
du
ct Coke
Gas
Liquid
Liquid, char, gas and coke yield distribution versus amount of catalyst
ProductProduct yieldsyields::
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51,0 51,2 53,0
0%
20%
Exp 1 Exp 2 Exp 3
Experiments
wt
% o
f e
ach
pro
du
ct
Char
Gas yield increases when the catalyst load becomes increasedLiquid yield becomes decreased
Low deposition of coke on the catalyst
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ResultsResults
Gas composition during experiment 2 (Fluid. bed: 550 ºC, Fixed bed: 500 ºC, 97g γ-Al2O3).
ProductProduct yieldsyields::
Gas composition remained constant throughout
The product gases were CO, CO , H , C H , C H
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The product gases were CO, CO2, H2, C2H2, C2H4
and C2H6
The presence of γ-Al2O3 did not significantly alter the gas composition
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12,5 6,69,4
3,0
15
20
25
30
35
40
Yie
ld t
o e
ach
ph
ase
(w
t%)
Light organic phase
Viscous organic phase
Organic phase
Aqueous phase
ResultsResults
LiquidLiquid physicochemicalphysicochemical propertiesproperties::
Liquid yield and phase distribution versus amount of catalyst
Inert sand → Three phases
γ-Al2O3: Only two phases of different colours → easier separation.
21,217,9 19,8
0
5
10
15
Exp 1 Exp 2 Exp 3
Experiments
Yie
ld t
o e
ach
ph
ase
(w
t%)
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Organic phase obtained (Exp 2) ≈ total mass of organics (LOP + VOP)
obtained without catalyst.
The organic fraction yield, decreased with the highest catalyst load, and the
HHV increased.
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Elemental composition of organic phases.
% Exp 1 Exp 2
Viscous Light Organic
C 70.54 85.92 79.55
H 8.76 11.83 9.85
ResultsResults
Using γ-Al2O3:
�great reduction of O content�C and H contents very similar to conventional fuels (*)
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N 9.99 1.80 8.27
S 1.02 0.18 0.83
Oc 9.69 0.27 1.5
C oxygen calculated by difference
fuels (*)x N and S contents greater than conventional fuels (*)
(*) Bahadur, N., Boocok, D., Konar,S., Energy Fuels 9 (1995) 248-256
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Material O/C H/CHHV
(MJ/kg)
Exp 1
Light organic phase
0.002 1.65 41.6
O/C ratio, H/C ratio and HHV values
ResultsResults
Organic phase properties:Organic phase properties:
HHV of the organic phase (exp. 2, 3) →possible use as a fuel (40-45 MJ/kg)
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Exp 1phase
Viscous organic phase
0.10 1.49 31.4
Exp 2Organic phase
0.01 1.48 41.3
Exp 3Organic phase
n.a n.a 40.3
*n.a. not analized
possible use as a fuel (40-45 MJ/kg)
The catalyst load had more influence in theorganic phase yield than in its HHV.
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Kinematic viscosity, dinamic viscosity and density values at 32 ºC
Material
Kinematic
viscosity
(cSt)
Dinamic
viscosity
(mPa*s)
Density
(kg/dm3)
API
gravity
Exp 1Viscous organic phase
140 122 0.87 <10
ResultsResults
Organic phase properties:Organic phase properties:
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phase
Exp 2Organic phase
21 19 0.91 13
Exp 3Organic phase
24 22. 0.92 21
Viscosity of the organic phase enhanced with the catalytic process →promising values for its use as a fuel
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 21
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OutlineOutline
� Introduction and Objectives
� Materials and Methods
� Results:
– Product yields– Product yields
– Organic and aqueous phase yields
– Elemental composition of organic phases
– Organic phase properties: relation O/C, H/C, HHV
� Conclusions
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 22
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ConclusionsConclusions
• The enhancement of the fuel properties of pyrolysis liquids from sewagesludge by means of a catalytic treatment with γ-Al2O3 of the pyrolysisvapours generated has been studied in a fixed bed.
• Using γ-Al2O3 as a catalyst a more homogeneous pyrolysis liquid could beobtained. With a load of 94 g of catalyst the yield to the organic phase did not
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 23
obtained. With a load of 94 g of catalyst the yield to the organic phase did notdecrease significantly respect to a pyrolysis experiment without catalyst.
• Using activated γ-Al2O3 long carboxylic acids were converted intoproducts with very little or no oxygen, like aliphatic and aromatichydrocarbons.
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ConclusionsConclusions
• The organic phase obtained in the catalytic process with activated γ-Al2O3 had a greater HHV in comparison to the viscous organic phase.
• The H/C ratio of the organic phase was very similar to that of aconventional fuel.
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• The organic phases obtained in the catalytic process had significantlyminor viscosity values than those of the viscous organic phase.
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PRELIMINARY STUDY AMONG CONVENTIONAL PYROLYSIS
AND CATALYTIC PYROLYSIS OF SEWAGE SLUDGE
M. Azuara*, N. Gil, P.Barcelona, I.Fonts and M.B.Murillo
Thermochemical Processes Group (GPT), Aragon Institute for Engineering Research (I3A), Zaragoza (Spain)
*: e-mail: [email protected]
Bioenergy III: Present and New Perspectives on Biorefineries
Lanzarote (Spain), May 24th, 2011
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LIQUID: Due to the different properties of these 3 phases, they can not be mixed and usedjointly.
Light organic phase: (Yield = 2.3 wt%)
•Composition: aliphatic hydrocarbons, steroids and triglycerides (no water).
•Physicochemical properties: HHV ~ 43 MJ/kg, ρ = 0.94 kg/dm3, µ ~ 22 cP,
pH = 8, moderate nitrogen (2.4 wt%) and sulfur (0.2 wt%) contents.
Aqueous phase: (Yield = 20.7 wt%)
•Composition: water (around 70 wt%), aminosugars, acids (C3-C9), phenolic
compounds, nitrogen-containing compounds and levoglucosan.
•Physicochemical properties: HHV < 15 MJ/kg and high nitrogen content (7.0
wt%).wt%).
Heavy organic phase: (Yield = 9.8 wt%)
•Composition: triglycerides, aminosugars, phenolic compounds, nitrogen-
containing compounds, fatty alcohols, fatty acids and a moderate water content
(~7 wt%).
•Physicochemical properties: HHV ~ 31 MJ/kg, pH = 8-9, µ ~ 430 cP @20 ºC,
high nitrogen (8.8 wt%) and sulfur (1.0 wt%) contents, no soluble in diesel and
bio-diesel.
Picture of the liquid after centrifugation.
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MethodsMethodsOperational conditionsOperational conditions
� A new fixed bed reactor was set up in addition with the fluidized bed plant.Table III shows the most important operational conditions selected to carryout the sewage sludge pyrolysis experiments.
� Feed rate of 6 g/min of sewage sludge and a nitrogen flow of 4.4 dm3
(NTP)/min was kept in each experiment (Fonts et Al, Azuara et Al).
Bioenergy III: Present and New Perspectives on Biorefineries – Lanzarote, May 2011 27
� Since physical characteristics of sewage sludge enabled good fluidizationbehaviour, no fluidization agents, such as sand, were added to the bed.