reduction for torrefied biomass and coal in pulverized fuel furnaces ndibe... · 2020-01-08 ·...
TRANSCRIPT
Prof. Dr. techn. G. Scheffknecht
Institute of Combustion and Power Plant Technology
E i t l t d f diff i NO f ti dExperimental study of differences in NOX formation and
reduction for torrefied biomass and coal in pulverized fuel
furnaces
11th European Conference on Coal Researchand Its Applications: ECCRIA 11,
University of SheffieldUniversity of Sheffield,5th-7th September 2016.
Collins Ndibe, Jörg Maier, Günter Scheffknecht
Table of Contents
1. Background and introduction
2. Fuels tested
3. Bench scale tests
Description of methodsp
Results and discussion
4 Pil l ( 00kW)4. Pilot scale tests (500kW)
Description of methods
Results and and discussion
5 Concl sions5. Conclusions
2
Background and introduction
Increased use of different biomass fuels(including pre-treated biomass).Understanding the differences in fuel nitrogentransformation will optimize primary controlmeasures.
De-volatilization behavior and nitrogenrelease for pure fuels and mixes.
Combustion and NOX formation behavior Combustion and NOX formation behaviorfor pure fuels and mixes.
Investigate primary reduction/combination Investigate primary reduction/combinationof methods for NOX reduction for purefuels and mixes.
3
IFK-USTUTT‘s 500kW combustion test rig
NOX formation in pulverized fuel (PF) combustionNOX formation in pulverized fuel (PF) combustion
Prompt NOX <5%Thermal NOX < 20%
Prompt NOX <5%
Thermal NOX formation higher combustion temperatures for
coal than that of biomass. overall the formation pathway found to
be less important in PF systems.
PF combustion
Fuel N content (wt. %) Molecular structureof nitrogen
compounds inCoal 0.5 – 2.0
compounds in coals more
aromatic and morestable in coals
Wood 0.03 – 1.0Straw 0.3 – 1.5Other agro-residues 0 4 – 3 5
4
compared tobiomass fuels!
Other agro residues 0.4 3.5Sewage sludge 2.5 – 6.5
Adapted from P. Glarborg et al. / Progress in Energy and Combustion Science 29 (2003) 89-113
Fuel-N conversion during combustion
Gas phaseHCN, NH3
oxidation2a
NOXVolatile-N Secondaryreactions
Reduction2bN2PyrolysisCoal-N Tar-N Soot-N
HeterogeneousreactionsChar-N
Pyrolysis Heating rate, temperature, pressure,
2Homogeneous oxidation/reduction reactions Local stoichiometries Heating rate, temperature, pressure,
fuel structure, stoichiometry Local stoichiometries Reduction with NHi, CO, CHi, soot, char
5Adapted from P. Glarborg et al. / Progress in Energy and Combustion Science 29 (2003) 89-113
Fuels and analysis (proximate/ultimate analysis)
Fuel W A V Fix-C C H N S NCV[%, ar] [%, db] [%, daf] [%, daf] [%, daf] [%, daf] [%, daf] [%, daf] (ar)
C lCoalsEl Cerrejon 2.53 12.2 36.0 64.0 80.6 5.3 1.69 0.65 28.66US High S. 1.6 9.4 38.7 61.3 81.9 5.2 1.59 2.67 30.41
LigniteLignite (LaTBK) 11.3 4.63 57.6 42.4 66.1 5.4 0.61 0.98 20.71
Torrefied biomass pelletsTorr wood 6.1 0.13 79.1 20.9 59.1 4.9 0.2 0.027 19.37Torr wood 6.1 0.13 79.1 20.9 59.1 4.9 0.2 0.027 19.37
Torr wood 2 6.8 0.61 75.5 24.5 54.4 4.7 0.2 0.04 19.20Torr straw 7.9 4.4 76.2 23.8 53.1 4.9 0.52 0.085 17.49Torr forest 8 0 3 1 74 5 25 5 54 6 4 8 0 45 0 04 17 83residues 8.0 3.1 74.5 25.5 54.6 4.8 0.45 0.04 17.83
Non-torrefied woody biomassWood dust 8.0 1.4 79.5 20.5 51.1 4.8 0.63 0.066 17.42
Particle sizeBiomass: D90 < 600μm (Drop tube tests)
D90 < 1mm (Pilot scale tests)
6
( )Hard Coal: D90 < 70μmLignite: D90 < 234μm
Bench scale tests: Pyrolysis reactor
BTS-ER
Pressure: Atmospheric
Temperature range: Up to 1300 °C
Fuels: Coal, Biomass
Fuel mass stream: 500-5000 g/h
Reaction pipe length: 2700 mm
Reaction pipediameter:
80 mm
7
Source: www.ifk.uni-stuttgart.de
Bench scale tests: Combustion reactor
BTS-VR
Pressure: Atmospheric
Temperature range: Up to 1300 °C
Fuels: Coal, Biomass
Fuel mass stream: 500-5000 g/h
Reaction pipe length: 2500 mm
Reaction pipediameter:
200 mm
Gas residence time 4.5s -5.6s
8
USTUTT‘s BTS, 20kW
Source: www.ifk.uni-stuttgart.de
Results of pyrolysis tests: Mass release rates
3480100
ree
Fixed C, % Ash, % Volatiles % Mass release, %
93 84 88
3467
020406080
t.-%
, wat
er fr
0
WD
Cha
r, 80
0°C
TWD
2
Cha
r, 80
0°C
har,
1100
°C EC
har,
1100
°C
TWD
+ E
C)
har,
1100
°C
wt
C C Ch
Ch
50%
(T Ch
Wood dust (WD)
Torr wood dust 2(TWD2)
El Cerrejon coal (EC)
50% (Torr wood +EC coal)( ) ( ) ( ) )
Increase in reactor wall temperature increasesmass loss for torrefied biomass
Mass release much higher for biomass comparedto coal (highest for non torrefied wood)
9
to coal (highest for non torrefied wood).
Pyrolysis tests: N partitioning into volatiles and chary y p g
100%N in char N volatilized
96% 94% 95%
25% 34%
40%
60%
80%te
rfre
e
4% 6% 5%
75% 66%
0%
20%
40%
wt.
% ,
wat
Higher N partitioning into volatile species for biomass and co-fired case. Advantageous for staging.
10
No significant difference in behavior for non-torrefied wood dust.
NOX profiles in drop tube furnace- un-staged andair-staged combustion (1 = 0 75) combustionair-staged combustion (1 = 0.75) combustion
1000
rnac
e
LigniteEC coal
Lignite_stagedEC coal_stagedCombustion
without primary measure
400
600
800
rofil
ein
fur
(ppm
)
without primary measure
Coal, Air
Total = 1,15
0
200
400
NO
X pr OFA
Addition
Total , 5Unstaged Combustion1= 1,15
Air staged Combustion 0 0.5 1 1.5 2 2.5distance from burner (m)
0 0.5 1 1.5 2 2.5
eTorr wood Torr wood_stagedTorr wood 2 Torr wood 2 staged
>1
Air-staged CombustionWith OFA1= 0,75
600
800
1000in
furn
ace
m)
o ood o ood _s agedWood dust Wood dust_staged
200
400
600
NO
Xpr
ofile (p
p
OFA Ash
11
00 0.5 1 1.5 2 2.5
N
distance from burner (m)
AdditionFlue gas
NOX espressed as a fraction of Fuel N-converted: Pure fuels in the drop tube reactorPure fuels in the drop tube reactor
Higher Fuel N conversion for the morevolatile fuels especially during un-stagedcombustion.
Air-staging effective for all fuels in reducing Air staging effective for all fuels in reducingNOX especially for more volatile fuels.
With higher N content, lower N conversion.
60
wt.
%)
30
40
50
onve
rsio
n(w
1= 1,15
10
20
el-N
toN
OX
c
1= 0,75
12
00 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
Fu
Nitrogen content, dab (wt. %)
Co-firing (drop tube tests): NOX emissions,NOX espressed as a fraction of Fuel N-convertedNOX espressed as a fraction of Fuel N converted
1000λ1 = 1,15 λ1 = 0,75
Co-firing may increase or
Co-firing at oxidizing burner400
600
800
OX
(ppm
v) decrease NOX emissions.
Co-firing at oxidizing burnerconditions will increase N conversion.
0
200
400NO
Air staging effective, more so with increasing volatility (i.e co-firing, biomass combustion).
0% (EC Coal) 50% 100% (Torr wood)
λ1 1 15 λ1 0 75
600
800
1000
pmv)
λ1 = 1,15 λ1 = 0,75
Fuel N to NOX conversion during50% fi i ( t %)
200
400
600
NO
X (p
p 50% cofiring, (wt.%)λ1=1,15 λ1=0,75
Measured 34 6Predicted 38 8
13
00% (US Coal) 25% 100% Torr straw
Pilot scale experimental rig (KSVA, 500kWth)Pilot scale experimental rig (KSVA, 500kWth)
distances between levels and length ofdistances between levels and length ofdistances between levels and length of
Measurements performed along thedi d i f l l 2 t 15
Biomass
1
segments in mm
12345
61,000
500
800
650
350
200
160
150
150
150
150
level no.
1
segments in mm
12345
61,000
500
800
650
350
200
160
150
150
150
150
level no.
1
segments in mm
12345
61,000
500
800
650
350
200
160
150
150
150
150
500
800
650
350
200
160
150
150
150
150
level no.radius and axis from level 2 to 15 Gas concentration (O2, CO, NOX) Gas temperature profiles
Coal
2
3
6789
10
111213
2,000
500
800
670
330
160
500
330
160
170
170
170
170
170
170
170
2
3
6789
10
111213
2,000
500
800
670
330
160
500
330
160
170
170
170
170
170
170
170
2
3
6789
10
111213
2,000
500
800
670
330
160
500
330
160
170
170
170
170
170
170
170
500
800
670
330
160
500
330
160
170
170
170
170
170
170
170
4
1415
1617181920
3000
4,000
800
670
500
800
350
350
200
0
170
150
150
150
150
4
1415
1617181920
3000
4,000
800
670
500
800
350
350
200
0
170
150
150
150
150
4
1415
1617181920
3000
4,000
800
670
500
800
350
350
200
0
170
150
150
150
150
800
670
500
800
350
350
200
0
170
150
150
150
150
Low NOX swirlburner
5
21
22
23
24
255,280
1015
765
515
265
140
250
250
250
250
5
21
22
23
24
255,280
1015
765
515
265
140
250
250
250
250
5
21
22
23
24
255,280
1015
765
515
265
140
250
250
250
250
1015
765
515
265
140
250
250
250
250
• Flame video monitoring
6
26
27
28
29
30
890
640
390
1390
1140
250
250
250
250
250
250
6
26
27
28
29
30
890
640
390
1390
1140
250
250
250
250
250
250
6
26
27
28
29
30
890
640
390
1390
1140
250
250
250
250
250
250
890
640
390
1390
1140
250
250
250
250
250
250
14
31
funnel7,060
1640250
7,730
31
funnel7,060
1640250
7,730
31
funnel7,060
1640250
1640250
7,730
Source: www.ifk.uni-stuttgart.de
Bituminous (EC coal) NOX profile- 500kW test rig
1 = 1,151 = 1,15
500
1398
500
15O2(%) T(°C) NOX(ppmv)
500
600
1 ,1 1,15
10001000
ner [
mm
] 10 1000
[]
1500
11651500
Dis
tanc
e fro
m b
urn
1500330
2500
2000
890 62500
2000
0 02500
2000
60 0-400 -200 0
Furnace radial distance [mm]
890,6-400 -200 0
Burner radial distance [mm]
0,0-400 -200 0
Furnace radial distance [mm]
60,0
15
Torr wood NOX profile- 500kW PF test rig
T(°C) NO ( )1 = 1,151 = 1 15
500
1398O2(%) T(°C) NOX(ppmv)
500
15
500
104,6
1 ,1 1,15
1000
[]
1165
1000
urne
r [m
m] 10 1000
2000
1500
1165
2000
1500
Dis
tanc
e fro
m b
u
2000
1500 79,6
400 200 0
2500
890,62500
2000
0 02500
2000
54 6-400 -200 0Furnace radial distance [mm]
,-400 -200 0
Furnace radial distance [mm]
0,0-400 -200 0
Furnace radial distance [mm]
54,6
16
NOX profile 50% co-fired (El Cerrejon coal + Torr wood)
1 = 1,151 = 1,15
500
15
500
1398O2(%) T(°C) NOX(ppmv)
500
400
1 ,
1000
er [m
m] 10 1000 1000
1500
Dis
tanc
e fro
m b
urne
1500
11651500 300
2500
2000
2500
2000
2500
2000
-400 -200 0Furnace radial distance [mm]
0,0-400 -200 0
Furnace radial distance [mm]
890,6-400 -200 0
Furnace radial distance [mm]
200
17
NOX formed as a function of fuel nitrogen content(500kW Tests)(500kW Tests)
600exit
El Cerrejon coal 50% Torr wood + El Cer. Torr wood
distances between levels and length ofdistances between levels and length ofdistances between levels and length of
400
600
ons
at 6
% e
mg/
m3 ) 1
levels and length ofsegments in mm
12345
1,000
500
800
650
350
200
150
150
150
150
level no.
1
levels and length ofsegments in mm
12345
1,000
500
800
650
350
200
150
150
150
150
level no.
1
levels and length ofsegments in mm
12345
1,000
500
800
650
350
200
150
150
150
150
500
800
650
350
200
150
150
150
150
level no.
OFA
Fuel N to NOX conversion during 50% co-firing, (wt.%)
λ1=1,15 λ1=0,9 λ1=0,75Measured 21 12 9
0
200
NO
Xem
issi
oO
2(m
2
3
6789
10
111213
2,000
500
800
670
330
160
500
330
160
170
170
170
170
170
170
2
3
6789
10
111213
2,000
500
800
670
330
160
500
330
160
170
170
170
170
170
170
2
3
6789
10
111213
2,000
500
800
670
330
160
500
330
160
170
170
170
170
170
170
500
800
670
330
160
500
330
160
170
170
170
170
170
170
OFAMeasured 21 12 9Predicted 21 15 13
NOX Unstaged λ1 = 1,15
NOX Staged λ1 = 0,9 NOX Staged λ1 = 0,75
N
El cerrejon coal 50% (Torr wood + El Cer.) Torr wood4
131415
1617181920
3000
4 000
500
800
670
500
800
350
350
200
170
170
150
150
150
150
4
131415
1617181920
3000
4 000
500
800
670
500
800
350
350
200
170
170
150
150
150
150
4
131415
1617181920
3000
4 000
500
800
670
500
800
350
350
200
170
170
150
150
150
150
500
800
670
500
800
350
350
200
170
170
150
150
150
150
202530
onve
rsio
n)
j ( )
5
21
22
23
24
25
4,000
5,280
1015
765
515
265
140
250
250
250
5
21
22
23
24
25
4,000
5,280
1015
765
515
265
140
250
250
250
5
21
22
23
24
25
4,000
5,280
1015
765
515
265
140
250
250
250
1015
765
515
265
140
250
250
250
51015
N to
NO
Xco
(wt.
%)
6
25
26
27
28
29
30
890
640
390
1390
1140
250
250
250
250
250
6
25
26
27
28
29
30
890
640
390
1390
1140
250
250
250
250
250
6
25
26
27
28
29
30
890
640
390
1390
1140
250
250
250
250
250
890
640
390
1390
1140
250
250
250
250
250
18
05
NOX unstaged_λ1=1,15
NOX staged_λ1=0,9 NOX staged_λ1=0,75Fuel
N 31
funnel7,060
1640250
7,730
31
funnel7,060
1640250
7,730
31
funnel7,060
1640250
1640250
7,730
Conclusions
Mass release rates for non torrefied wood higher than for torrefied wood during pyrolysis. g g py y
Fuel N to NOX conversion for biomass is higher compared to coal. Overall emissions onlylower for biomass due to much lower N content.
Co-firing my lead to synergetic effects of lower Fuel N to NOX conversion, but conversion still compared to coal.
Optimized Low NOX burner and air-staging may meet NOX limits for torrefied biomass fuels. Depends on overall N content and biomass type.
Torrefied biomass and non torrefied biomass similar in NOX formation and reduction behaviour.
Most important factors for NOX formation are fuel structure (volatility), N content, furnace and burner configuration.
19
Thank you!
Research work supported via various projects including:SECTOR (EU FP7) https //sector project e /SECTOR (EU FP7): https://sector-project.eu/German Co-firing National Project: https://www.tuhh.de/iet/forschungsprojekte/biomasse-mitverbrennung.htmlBIOPOGEN (KIC Innoenergy):http://www.kic-innoenergy.com/innovationproject/our-innovation-projects/biopogen/
Collins NdibeAcademic Researcher / PhD student Department of Firing Systems- KWFDepartment of Firing Systems KWF,Institute of Combustion and Power Plant Technology, Uni-Stuttgart – IFK, Germany: [email protected]://www ifk uni stuttgart de/
20
http://www.ifk.uni-stuttgart.de/