Biomass Pyrolysis By Dr. Titiladunayo: Part 2

Report
DEVELOPMENT OF A BIOMASS PYROLYSIS
REACTOR AND CHARACTERISATION OF
ITS PRODUCTS FOR INDUSTRIAL
APPLICATIONS
Department of Mechanical Engineering
The Federal University of Technology Akure.
Ondo State. Nigeria
JANUARY, 2012
Introduction



It comprises:- aggregate of all biologically
produced matter inform of:
wood and wood wastes;
 agricultural crops and their waste by-products;
municipal solid wastes;
animal wastes;
wastes from food processing;
and aquatic plants including sea weeds and algae
(Agarwal and Agarwal, 1999; U.S Dept of Energy,
2003).
Biomass is cheap, available, affordable and reliable
It’s a regular source of rural energy in Nigeria, fuel
wood is cheap, easily accessed by both rural &
urban dwellers.
2
– renewable, available,
and abundant on earth.
It is a versatile energy and
chemical resource
It
could be converted into
renewable products that could
significantly supplement the
energy needs of society
Biomass
3
Selected Feedstock Species
(A)
M. excelsa
(B)
A. africana
(C)
E. guineensis
Fig. 17: Sizing of Selected Feedstock for Pyrolysis Experiments
4
Experimentation and Documentation


5
Carbonisation experiments were carried out
at various elevated temperatures for all
samples in the developed electrically fired
‘Fixed-Bed Reactor’ at pre-determined
temps., ranging from 400°C to 800°C and at
100°C intervals.
Fifteen batches (0.5 kg net weight per batch)
each of the selected materials of constant
moisture content were used as feedstock in 3
replicated experiments
Experimentation & Documentation Cont…

By-products of pyrolysis:
 charcoal (solid fuel),
 oils (liquid fuel),
 and pyrogas (non-condensable gaseous products).


6
Experiments were conducted under a quiescent
environment (insufficient or complete absence
of air).
Feedstock residence time, furnace temp. and
pyrolysis (reaction) temp. were recorded as
displayed on the controllers and recorded every
5 min.
Experimental Set-up
Fig. 18: Pyrolysis Experimental set-up
7
Assembling the Fixed-Bed Reactor
8
Fig.19 Assembling the reactor for an Experiment
Fig. 20: Fully Assembled Fixed-Bed Reactor with an
Ongoing Experiment
9
10
Fig. 21:Dismantling the Reactor after an Experiment
The appearance of the Fixed-Bed Reactor and
Furnace at 600 °C and 700 °C respectively
Fig. 22: Appearance of the Fixed-Bed Reactor and
Furnace at 6000C & 7000C respectively (During the Day)
11
The appearance of the Fixed-Bed
Reactor and Furnace at 800 °C
Day Appearance
Night Appearance
Fig. 23: Fixed Bed Reactor after an Experiment
12
Result and Discussion





13
The relationship between Carbonisation and
reaction temperatures for the three species were
positive but not linear (Fig. 4A).
The temperature interactions within species and
between species were significant (p<0.05) as
shown Fig.4B
The mass of the char fractions vary from one
species to the other but a general mass reduction
across higher temperature profile is generally
noticed.
Pyrolysis oil yield also varies with temperature
The sygas fraction varies with temperature.
Result and Discussion




14
The mass of the char fractions vary from one
species to the other but a general mass
reduction across higher temperature profile is
generally noticed.
Pyrolysis oil yield also varies with temperature
The sygas fraction varies with temperature.
Pyroligneous oil is used as solvent and
insecticide
Table 6A: Mean and Standard Deviation of Reaction
Temperature for all samples
React. Temp.
S/No
Species
1
Apa
2
Iroko
3
PKS
Carbonisation Temperature (°C)
400
500
334.67±5.03
3
363.00±8.88
8
366.00±2.00
0
380.33±29.7
04
412.00±5.29
2
390.67±19.3
99
600
700
439.33±2 512.33±15.3 708.67±4.
7.465
08
041
487.67±1 590.67±22.1 685.00±2.
5.373
21
000
520.33±1 617.00±1.73 729.33±1
3.429
2
5.044
Table 6B: Variance ratios (F-calculated) from various ANOVA
tables for Reaction Temperature
F - Value
15
Species Treatment (TR)
Carbonisation Temp.(TC)
Interaction (TR*.TC)
* = significant (p<0.05),
R2=0.991
800
40.388*
773.350*
7.947*
Effect of Carbonisation Temperature
on Reaction Temperature
Reaction Temperature (TR) - ( C)
1000
TApa = 9E-06 Tc3 - 0.014 Tc2 + 7.765 Tc - 1080.
R² = 0.998
900
T Iroko = - 0.188 Tc + 300.6
R² = 0.997
T PKS = 0.001 Tc2 - 0.267 Tc + 298.5
R² = 0.986
800
700
600
500
400
300
Apa React. Temp. (TApa)- (°C)
Iroko React. Temp. (TIroko) - (°C)
PKS React. Temp. (TPKS) - (°C)
200
100
0
300
400
500
600
700
800
900
Carbonisation Temperature (TC) - (ºC)
Fig. 24: Increase of Reaction Temperature with increasing
carbonisation Temperature for all samples
16
Table 7: Mean Reaction Temperature between
Species
Carbonisation
Temp
N 1
400
500
600
700
800
Sig.
9
9
9
9
9
Subset (Reaction Temperatures)
2
3
4
5
354.56
394.33
482.44
573.33
707.67
1.000 1.000 1.000 1.000 1.000
Alpha (α) = 0.5
17
Variance ratios (F-calculated) from various
ANOVA Tables for Reaction Temperature
Table 8: Variance ratios (F-calculated) from various ANOVA
Tables for Reaction Temperature
F - Value
Species Treatment (TR)
40.388*
Carbonisation Temp. (TC)
773.350*
Interaction (TR*.TC)
* = significant (p<0.05),
R2=0.991
7.947*
18
Residence Time (t) -(min)
250
200
t Apa = -9E-08TC4 - 0.174TC2 + 65.51TC - 8983.
R² = 1
t PKS = 2E-08TC4 - 4E-05TC3 + 0.033TC2 - 12.68TC + 1815
R² = 1
t I roko = 2E-06TC3 - 0.002TC2 + 0.897TC - 79.01
R² = 0.999
150
100
50
Apa Wood Residence Time (Tapa)
Iroko Wood Residence Time (TIroko)
PKS Residence Time (TPKS)
0
300
400
500
600
700
800
Carbonisation Temperature (T C) - ( C)
900
Fig.
19 25: Effect of Carbonisation Temperature on Residence Time
Recovering Pyro-liquor through Phase change
Fig.26: Pyrolysis Liquor Recovery
20
Recovered Pyrolysis Liquor at 400 °C,
500 °C, 600 °C, 700 °C, and 800 °C
Pyro-oil from
Palm Kernel
Pyro-oil from
Iroko Wood
Pyro-oil from
Apa Wood
Fig. 27: Pyrolysis oil across selected samples
21
2.80
Mean pH - value across samples
2.60
2.40
2.20
2.00
1.80
1.60
Apa wood (pH-value)
1.40
Iroko wood (pH- value)
PKS (pH-value)
1.20
1.00
300
22
400
500
600
700
Carbonisation Temperature ( C)
800
900
Fig. 28: Acidic - pH for all samples
Mean Pyro-Oil Residual fraction (g) per
500g Batch Size across species
190
185
180
175
170
IROKO
APA
PKS
165
160
300
400
500
600
700
800
900
Carbonisation Temperature (TC) - ( C)
Fig.29: Variation of Pyro-oil yield with Carbonisation Temperature
23
Mean Tar Residual fraction (g) per 500g
Batch Size across species
60
55
50
45
40
35
30
IROKO
APA
PKS
25
20
300
400
500
600
700
800
Carbonisation Temperature (T C) - ( C)
900
Fig.30: Variation of Tar yield with Carbonisation Temperature
24
150
Syngas yield (g) per 500g Batch Size
across species
140
130
120
110
100
Apa wood (NCG)
Iroko wood (NCG)
PKS (NCG)
90
80
70
60
300
400
500
600
700
800
900
Carbonisation Temperature (TC) - ( C)
Fig. 31: Variation of Syngas yield with Carbonisation Temperature
25
Mean Char Residual fraction (g) per
500g Batch Size across Species (CR)
250
C R = -0.083TC + 205.7
R² = 0.979
C R = -0.143TC + 252.8
R² = 0.976
200
C R = -0.095TC + 228.6
R² = 0.957
150
100
IROKO
APA
PKS
50
0
300
400
500
600
700
800
900
Carbonisation Temperature (TC) - ( C)
Fig. 32: Variation of char yield with carbonisation temperature
26
Recovered Carbon & Smokeless
Burning Charcoal
B
A
C
D
27Fig. 33: Charring Residues & Smokeless combustion
Residual yield per species (% wt)
Percentage Residual fractions
for Apa wood (wt%)
120
100
80
60
Syngas yield (NCG)
Tar yield
Pyro-oil yield
Char yield
40
20
0
400
500
600
700
800
Carbonisation Temperature ( C)
Fig. 34: Variation of Apa wood residual fractions with
carbonisation temperature
28
Residual yield per species (% wt)
Percentage Residual fractions
for Iroko wood (wt%)
120
100
80
60
Syngas yield (NCG)
Tar yield
40
Pyro-oil yield
Char yield
20
0
400
500
600
700
800
Carbonisation Temperature (°C)
Fig. 35: Variation of Iroko wood residual fractions with
carbonisation temperature
29
Residual yield per species (% wt)
Percentage Residual fractions
for PKS (wt%)
120
100
80
60
Syngas yield (NCG)
Tar yield
Pyro-oil yield
40
Char yield
20
0
400
500
600
700
800
Carbonisation Temperature ( C)
30
Fig. 36: Variation of Iroko wood residual fractions
with carbonisation temperature
Table 9:Char yield / 1000 kg of feedstock
as a function of temperature
31
Temperature
( °C)
Iroko Derived
charcoal
Apa Wood Derived
Charcoal
PKS Derived
Charcoal
400
500
600
700
800
341.46
334.54
309.06
295.20
278.00
393.66
356.00
332.66
315.86
270.40
388.46
354.46
337.80
321.06
309.34
Table. 10: Pyro-oil yield / 1000 kg of feedstock as
a function of temperature
Temperature Iroko Derived
Apa Wood
( °C)
Pyro-oil
Derived Pyro-oil
400
500
600
700
800
32
339.80
342.74
353.06
359.60
365.06
329.86
334.80
334.14
329.06
350.54
PKS Derived
Pyro-oil
341.00
350.46
365.40
365.46
373.86
Fig.11: Tar yield / 1000 kg of feedstock as a
function of temperature
Temperature
Iroko
Apa Wood PKS Derived
( °C)
Derived Tar Derived Tar
Tar
33
400
99.14
80.26
91.94
500
97.86
100.80
98.80
600
107.00
100.80
90.60
700
102.66
108.74
86.66
800
100.20
104.66
93.80
Fig.12: Syngas yield / 1000 kg of feedstock as
a function of temperature
Temperature
( °C)
Iroko Derived
Syngas
Apa Wood
Derived syngas
PKS Derived
syngas
400
500
600
700
800
219.60
224.86
230.06
242.60
254.74
196.20
208.46
227.34
245.86
274.40
178.60
196.86
206.20
226.80
223.00
34
Material & Products Characterization
(1)
(2)
(4)
(5)
(6)
FTIR and TGA – Analysis
Determine: Proximate analysis of parent stock
and fractions: M.C, V.M, F. C, & Ash content
Determine: Ultimate analysis (Elemental
analysis of Parent stock and fractions)- C, H, O,
N, S, Ash
Energy Content Analysis (HHV)
Density
Moisture Content Determination

36
The moisture content was determined by
using METTLER TOLEDO HB 43-S Hologen,
moisture Analyzer. The result is as shown in
Table 3.
Table 5: Moisture Content (%wt/wt)
BIOMASS
Moisture Content
(%wt/wt)
(i) Apa Wood
(ii) Iroko
(iii) PKS
(iv) Coconut Shell
(v) Gmelina Arborea
(vi) Bamboo
37
REPLICATES (%)
1st
2nd 3rd
4.88
4.27
4.10
5.03
4.87
3.74
4.78
4.40
4.17
4.91
4.90
3.99
4.89
4.23
4.24
4.92
4.98
3.87
MEAN + STDV
4.85 ± 0.06
4.30 ± 0.09
4.17 ± 0.07
4.95 ± 0.07
4.92 ± 0.06
3.87 ± 0.13
Table. 6: BIOMASS Volatile Matter (%wt/wt)
BIOMASS
Volatile Matter (%wt/wt)
1st
2nd
Mean ± STDV
(i)
Apa Wood
A
75.35
82.09
78.72 ± 4.77
(ii)
Iroko Wood
B
82.06
81.962
82.01 ± 0.07
(iii)
Palm Kernel Shell C
(PKS)
77.01
77.23
77.12 ± 0.16
(iv)
Coconut Shell
D
82.3
87.30
84.80 ± 3.54
(v)
Gmelina Arborea
F
93.414
90.08
91.75 ± 2.36
(vi)
Bamboo
E
88.714
85.04
86.88 ± 2.60
Density Determination




The materials were ground to pass through 2 mm filter
Dried to constant weights in the muffle furnace at
103±2°C and later cooled in the desiccator.
Three replicates (0.001kg) measured with high
precision ‘METTLER Balance for compression
Pelletized in the die at a pressure of 5000 Ib/in2 (34.5
MN/m2) for all samples. The diameter (D) and height
(h) of all the pellets were measured with electronic
Veneer Caliper.
• Density of pellet (ρ) =
39
4m/(πD^2 h)
Table. 7: Density of Selected Tropical Biomass (kg/m3)- Oven dry
weight
REPLICATES
S/No
(i)
(ii)
(iii)
(iv)
(v)
(vi)
40
Selected Tropical
Biomass
Apa Wood
Iroko Wood
1st
MEAN + STDV
1029.25
1024.03
1009.09
1020.79 ± 10.46
878.13
874.17
895.60
882.63 ± 11.40
1028.47
1031.59
1038.37
1032.81 ± 5.06
1078.93
1066.51
1105.55
1083.67± 19.95
850.82
857.53
845.85
851.40 ± 5.86
914.82
914.91
930.95
920.23 ± 9.28
B
C
Coconut Shell
D
Bamboo
3rd
A
Palm Kernel Shell
(PKS)
Gmelina Arborea
2nd
F
E
1200
Density (kg/m3)
1000
800
600
400
200
0
Apa Wood Iroko Wood Palm Kernel
Shell (PKS)
41
Coconut
Shell
Gmelina
Arborea
Fig. 27: Selected Woody Biomass
Bamboo
PROXIMATE
ANALYSIS
SAMPLE
*P/Stk
400
500
APA
1.08
1.31±0.01e
1.59±0.02d
ASH
IROKO
600
1.94±0.01 2.21±0.01
c
0.82
4.89±0.02e
6.38±0.49d
2.23
4.07±0.02e
5.19±0.02d
21.06
56.38±0.23e
IROKO
20.93
74.65±0.48e
PKS
18.45
73.65±0.51e
77.86
42.31±0.22a
IROKO
78.25
20.46±0.46a
PKS
79.32
22.28±0.51a
APA
APA
42
FC
VM
2.59±0.02a
8.20±0.01a
b
6.17±0.01 6.26±0.01
c
800
b
7.45±0.01 8.03±0.02
c
PKS
700
6.39±0.11a
b
63.44±0.09 87.33±0.7 94.02±0.1
d
8c
9b
77.35±0.06 81.54±0.0 84.38±0.0
d
4c
2b
78.54±0.07 83.4±0.02 91.64±0.0
d
c
5b
95.36±0.05a
34.97±0.10 10.73±0.7 3.77±0.19
b
d
8c
16.49±0.08 11.01±0.0 7.58±0.01
b
d
3c
16.27±0.06 10.43±0.0 2.09±0.05
b
d
1c
2.05±0.04e
85.13±0.03a
92.3±0.09a
6.66±0.03a
1.29±0.11e
Energy Content Determination




43
Samples were pulverized in Ball Mill, made to
pass through 2 mm filter and dried to constant
weight in an oven at 103±2°C.
Parr 1341 Oxygen Bomb Calorimeter was
standardized with using benzoic acid in three
replicates.
The standard energy was determined to be
2437.9 cal/°C (10.207 kJ/°C).
Each biomass Pellets was fired in the Bomb
Calorimeter and energy determined.
Table 8: Biomass Energy Determination
S/No
Selected Tropical Biomass
Energy Content (kJ/kg)
(i)
Apa Wood
(ii)
Iroko Wood
(iii)
Palm Kernel Shell (PKS)
(iv)
Coconut Shell
(v)
Gmelina Arborea
(vi)
Bamboo
44
REPLICATES
1st
MEAN + STDV
2nd
3rd
A 21.60
B 19.55
21.30
21.47 21.46 ± 0.15
20.42
19.25 19.74± 0.61
C 20.23
D 20.07
20.08
20.68 20.33 ± 0.32
20.12
19.92 20.04 ± 0.11
F 17.84
E 19.46
18.53
17.13 17.83 ± 0.70
17.91
18.88 18.75 ± 0.78
CONCLUSION:
The electrically controlled thermal reactor
plant for the conversion of biomass to charcoal
was successfully developed.
The performance of the reactor was evaluated
over a temperature range of 4000C to 8000C
and was found to be effective in degrading
Palm Kernel (Elaesis Guineensis) Shells, Apa
wood (Afzelium Africana) and Iroko wood to
charcoal at pre-determined conditions.
45
Conclusion Cont….
 Conversion efficiency is higher than reported in
literature.
 Cycle time is much reduced than reported in literature
 Heat promotes the unzipping of biomass polymer
chain in thermochemical reactions
 Biomass’ rate of mass disappearance is a function of
temperature, degree of structural polymerization,
thermal conductivity, material density, heating rate,
thermal intensity, and residence time among others.
 Rapid evolution of volatiles is noticed from 275°C to
600°C. It reduces drastically to near zero between
700°C to 800°C for the selected biomass samples.
46
THANK
YOU
FOR
LISTENING
GOD BLESS YOU ALL
47

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