Grindability of Torrefied Beechwood and Co

Transcription

Grindability of Torrefied Beechwood and
Cofiring with Pulverized Lignite at Pilot Scale
Andreas Ohliger, Malte Förster, Reinhold Kneer
Institute of Heat and Mass Transfer
RWTH Aachen University
2nd International Workshop on Cofiring Biomass with Coal, Copenhagen
March 27, 2012
Outline
1. Torrefaction – What and why?
Reactor
2. Torrefaction Reactor
3. Grindability of Torrefied Beechwood
4. Cofiring in Pulverized Coal Combustion Test Rig
Picture source:
http://static1.essen-und-trinken.de
What Torrefaction Means

Torrefaction

Thermal Treatment of Biomass
300°C
280°C
≈ 10-60 minutes
260°C
240°C
220°C
200°C
180°C
O2
Aim: Upgrading of Biomass

Aims of Torrefaction:

Improvement of Grindability
Picture sources:
http://static1.essen-und-trinken.de ; http://www.dahw.de
http://picmirror.de/bild.php/8952_080308_schimmel.jpg
http://data.lustich.de/bilder/l/14003-holztransport.jpg ; http://thumbs.dreamstime.com/
http://www.heimwerker-tipps.net ; http://media.realisr.com/



Prevention of Biological Decay
Picture sources:




Increase of Energy Density
Picture sources:




Increase of Energy Density

Homogenisation
Picture sources:
Torrefaction Process – schematical
Volatiles
Raw
Biomass
Reactor
Heat
Torrefied
Biomass
Volatiles
Raw
biomass
Reactor
Heat
torrefied
Biomass
Non Condensables:
CO2, CO, H2, CH4,
CxHy, toluene, benzene
Raw
Biomass
Condensables:
Volatiles
H2O, organic acids,
alcohols, furans, ketones,
terpenes, phenols, waxes,
tanins, fatty acids
Reactor
Heat
process according to Bergman et al.:
Torrefaction for biomass co-firing in existing coal-fired
power stations, ECN report ECN-C--05-013, 2005
Torrefied
Biomass
Torrefaction Process – Energy and Mass Flows
Volatiles
kg
Raw
Biomass
100%
100%
Reactor
Heat
kg
= Mass
= Energy
Torrefied
Biomass
Torrefaction Process – Energy and Mass Flows
Volatiles
kg
kg
Raw
Biomass
100%
30%
10%
100%
kg
70%
90%
Reactor
Heat
kg
= Mass
= Energy
Torrefied
Biomass
Torrefaction Reactor Used
Raw Biomass
(approx. 1 kg/h)
Volatiles
Measurement
Ports (Closed)
Øinternal:
Length:
160 mm
1000 mm
Torr. Biomass
Raw Biomass
N2
Volatiles
Measurement
Ports (Closed)
Øinternal:
Length:
160 mm
1000 mm
N2
Torr. Biomass
Raw Biomass
N2
Volatiles
Measurement
Ports (Closed)
Heating Air
N2
Torr. Biomass
Raw Biomass
Volatiles
Measurement
Ports (Closed)
N2
Heating Air
1
2
3
4
5
Temperature Measurements
N2
Torr. Biomass
Parameters of the Study

Temperature: 270, 280, 290, 300 °C
300°C
280°C
260°C
240°C
220°C
200°C
180°C

Residence Time: 20, 40, 60 minutes

Feed Moisture: 0, 10, 20 mass-%
Parameters of the Study

Temperature: 270, 280, 290, 300 °C
300°C
280°C
260°C
Reference Test
240°C
220°C
200°C
180°C

Residence Time: 20, 40, 60 minutes

Feed Moisture: 0, 10, 20 mass-%
Temperature Distribution in Reactor During Reference Test
280°C, 40 Minutes, 10% Moisture in Feed
390
370
Temperature
[°C]
Temperature [°C]
350
THeating Air,inlet
330
310
T3
290
270
time for one
revolution of screw
T4
Begin of Biomass Feeding
End of Biomass Feeding
250
T2
T5
T1
230
0
0:30 3600
1:00 5400
1:30 7200
2:00 9000
2:30 10800
3:00 12600
3:30 14400
4:00
1800
Time[h]
[s]
Time
Energy Density
LHV of Rhenish Lignite (daf = dry, ash-free basis)
100
300°C
25
95
270°C
24
90
280°C 290°C
23
85
22
80
21
75
20
70
19
LHV
raw
65
Energy Yield
18
60
0
10
20
30
40
Mass Loss of the Solid (daf) [%]
50
60
Energy Yield of the Solid (daf) [%]
LHV of the Solid (daf) [MJ/kg]
26
Energy Density and Energy Yield
100
300°C
25
95
270°C
24
90
280°C 290°C
23
85
22
80
21
75
20
70
19
LHV
raw
65
Energy Yield
18
60
0
10
20
30
40
50
60
Energy Yield of the Solid (daf) [%]
LHV of the Solid (daf) [MJ/kg]
26
Grindability of Torrefied Beechwood Chips
3.8
HGI
120
Crushing Ratio
3.4
Grindability
Very Easy
100
3.0
Easy
80
2.6
Moderate
60
2.2
Difficult
40
1.8
Very Difficult
20
1.4
raw
0
0
1.0
10
20
30
40
50
60
Crushing Ratio [-]
Hardgrove Grindability Index [-]
140
3.8
HGI
120
Crushing Ratio
3.4
Grindability
Very Easy
100
Easy
80
Moderate
60
3.0

2.6
2.2
Difficult
40
1.8
Very Difficult
20
1.4
raw
0
0
1.0
10
20
30
40
50
60
Crushing Ratio [-]
140
3.8
120
Crushing Ratio
Grindability
Very Easy
100
Easy
80
Moderate
60
Difficult
40
3.4
3.0
2.6
2.2
1.8
Very Difficult
20
1.4
raw
0
0
1.0
10
20
30
40
50
60
Crushing Ratio [-]
HGI
Range Rhenish Lignite
140
3.8
120
Crushing Ratio
Grindability
Very Easy
100
Easy
80
Moderate
60
Difficult
40
Very Difficult
v
20
raw
0
0
3.4

1.8
3.0
2.6
2.2
1.4
1.0
10
20
30
40
50
60
Crushing Ratio [-]
HGI
Range Rhenish Lignite
140
Composition of Raw Beechwood Chips
Composition [mass-%] (dry)
90
80
70
Charge 1, raw
Charge 2, raw
60
50
40
30
20
10
0
Charge 1,
torrefied
Charge 1, torr.
repetition
Charge 2,
torrefied
Composition of Raw and Torrefied Beechwood Chips
Composition [mass-%] (dry)
90
80
70
Charge 1, raw
Charge 2, raw
60
50
40
30
20
10
0
Charge 1,
torrefied
Charge 1, torr.
repetition
Charge 2,
torrefied
Comparison Lignite, Torrefied Beechwood Chips
Composition [mass-%]
80
70
60
50
40
30
20
10
0
pre-dried
Rhenish Lignite
(RL)
Torrefied
Beechwood
Chips (TBC)
Composition of Fuels for Cofiring Experiments
80
70
60
50
40
30
20
10
0
pre-dried
Rhenish Lignite
(RL)
Torrefied
Beechwood
Chips (TBC)
Mixture 60/40
Mass-%
since the amount
of TBC was not
enough for pure
combustion
Composition of Fuels for Cofiring Experiments
80
70
60
50
40
30
20
10
0
pre-dried
Rhenish Lignite
(RL)
Torrefied
Beechwood
Chips (TBC)
Mixture 60/40
Mass-%
since the amount
of TBC was not
enough for pure
combustion
Pulverised Fuel Combustion Facility
Fuel
Air or O2/CO2
Measurement
Access Ports
(Optically and
by Probes)
4200 mm
Axially
Traversable
Swirl Burner
Ø 400 mm
Facility and burner have
been described in detail by
Stadler, H. et al.:
Experimental investigation
of NOx emissions in
oxycoal combustion.
Fuel, Vol. 90, Issue 4,
Pages 1604-1611, 2011
Pulverised Fuel Combustion Facility
Fuel
Air or O2/CO2
Measurement
Access Ports
(Optically and
by Probes)
Water Quench
500 mm
Axially
Traversable
Swirl Burner
Measurement of
unburned carbon via a
probe at a distance of
500 mm from the burner
Measurement of
pollutant gases
downstream of a
water quench
Concentration of Pollutant Gases in Flue Gas
Concentration in Stack [ppm]
700
600
500
Air, RL
Luft,
RTBK
400
Air, RL/TBC
Luft,
RTBK/tBS
300
21/79%
%21%,
/CO22,
Oxyfuel
21/79
OO22/CO
RL/TBC
RL/TBC
200
100
0
CO
SO
SO2
2*
NO
RL = pre-dried Rhenish
Lignite
TBC = Torrefied Beechwood
Chips
* SO2 values show qualitative indications since
measurement is conducted downstream of a water quench
Burnout at 500 mm Distance from Burner
6
5
Limit for
ESP-Ash
100
99
4
Air, RL
Luft,
RTBK
98
3
Air, RL/TBC
Luft,
RTBK/tBS
97
21/79 %21%,
O2/CO2,
Oxyfuel
RTBK/tBS
RL/TBC
2
96
1
0
95
Ash [%]
CCininAsche
[%]
Conversion
[%]
Umsatz* [%]
Based on Total C
in Fuel
Lignite
Chips
Burnout at 500 mm Distance from Burner
6
5
Limit for
ESP-Ash
100
99
4
Air, RL
Luft,
RTBK
98
3
Air, RL/TBC
Luft,
RTBK/tBS
97
21/79 %21%,
O2/CO2,
Oxyfuel
RTBK/tBS
RL/TBC
2
96
1
0
95
Ash [%]
CCininAsche
[%]
Conversion
[%]
Umsatz* [%]
Based on Total C
in Fuel
Lignite
Chips
Chemiluminescence

Light emission due to non-thermal reason

Transition of a molecule from excited state (*) to ground state

In (gas) flames e.g.: CH*, C2*, CO2* (all visible), OH* (UV)
Picture Source: http://www.uv-elements.de/images/leuchtstab_big.png
Chemiluminescence




In coal flames: strong black body radiation
 usage of OH*, since little thermal radiation at 309 nm
Chemiluminescence




In coal flames: strong black body radiation
 usage of OH*, since little thermal radiation at 309 nm

Formation by: CH + O2 ↔ OH* + CO
Measurement of OH*-Chemiluminescence
CCD-Camera
Amplifier
UV-Filter
(approx. 308 nm)
Quartz Glas
Window
Arrangement/Position of Recorded Pictures
Ø 146 mm
Nozzle-Brick
Wall of Combustion
Chamber
Ø 400 mm
Swirl Burner
Chemiluminescence Results
500
Air-RL
500
Air-RL/TBC
RL
TBC
= pre-dried Rhenish Lignite
= Torrefied Beechwood Chips
500
Air-RL
420
Air-RL/TBC
RL
TBC
Position of the reaction zone is
not influenced by cofiring TBC
500
Air-RL
420
Air-RL/TBC
RL
TBC
Position of the reaction zone is
not influenced by cofiring TBC
500
Air-RL
420
Air-RL/TBC
RL
TBC
85
21/79 % O2/CO2-RL/TBC
Conclusion

WSA’s laboratory reactor  reproducible torrefaction

Torrefaction improves grindability

Ultimate analysis showed: wood Torrefaction

Cofiring high percentages of torrefied wood worked well
lignite
Acknowledgement for OXYCOAL-AC
RWE Power
E.ON Energy
Linde
MAN Diesel & Turbo
Hitachi Power
Europe
WS Wärmeprozesstechnik
Backup
The Term „Torrefaction“

lat. „torrere“, Meanings: roasting, baking, desiccation

French: torréfaction
English:
roasting

= roasting = torrefaction
= torrefaction
Roasting Coffee vs. Torrefaction

Roasting Coffee

Torrefaction
300°C
300°C
280°C
280°C
260°C
260°C
240°C
240°C
220°C
220°C
200°C
180°C
air
200°C
180°C
O2
Position und Größe der Aufnahmen
Ø 146 mm
1400
Brennerstein
Brennkammerwand
800
Ø 400 mm
Ölflamme, Luft
200
Emissionen und Ausbrand bei Staubfeuerung
Luftverbrennung
nur RTBK
Luftverbrennung
RTBK/tBS
Oxyfuelverbrennung
RTBK/tBS
0,7
1,6
1,2
CO Kamin [ppm]
2
2
10
SO2 Kamin [ppm]
334
248
271
NO Kamin [ppm]
621
543
238
C in Asche
[%]

Grindability of Torrefied Beechwood and Co

Transcription

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