wood pellets combustion with rich and diluted air in htac furnace author: ramona dinu
Post on 22-Dec-2015
230 views
TRANSCRIPT
Wood pellets combustion with Wood pellets combustion with rich and diluted air in HTAC rich and diluted air in HTAC furnacefurnace
Author: Ramona DINUAuthor: Ramona DINU
Wood pellets combustion with rich and dilWood pellets combustion with rich and diluted air in HTAC furnaceuted air in HTAC furnace
22
Paper objective:Paper objective:
biomass combustion behavior using high temperature air biomass combustion behavior using high temperature air combustion by burning wood pellets into the HTAC furnace. combustion by burning wood pellets into the HTAC furnace.
Measured parameters:Measured parameters:
pellet’s mass reduction;pellet’s mass reduction;
COCO22 and CO flue gases concentrations; and CO flue gases concentrations;
NONOxx emission level; emission level;
ignition time;ignition time;
flame behavior flame behavior
Wood pellets combustion with rich and dilWood pellets combustion with rich and diluted air in HTAC furnaceuted air in HTAC furnace
33
Experimental facility (HTAC furnace):Experimental facility (HTAC furnace):
Legend:1. methane inlet;2. oxidation air inlet;3. oxygen inlet;4. nitrogen inlet;5. burner;6. 1rst part of the combustion
chamber;7. ceramic honeycomb;8. 2nd part of the combustion
chamber;9. cooling chamber;
10. cooling nitrogen inlet;11. pellet inlet flange;12. glass window;13. thermocouple (T1);
14. thermocouple (T2);
15. thermocouple (T3);
16. facility outlet;17. flue gas analysis probe.
Wood pellets combustion with rich and dilWood pellets combustion with rich and diluted air in HTAC furnaceuted air in HTAC furnace
44
Biomass feedstock characteristicsBiomass feedstock characteristics Experiments rangeExperiments range
TemperatureTemperature
(°C)(°C)
OxidizerOxidizer800800 10001000
5 %5 % -- 30s30s 60s60s 180s180s 300s300s -- 30s30s 60s60s 180s180s 300s300s
10 %10 % -- 30s30s 60s60s 180s180s 300s300s -- 30s30s 60s60s 180s180s 300s300s
21 %21 % -- 30s30s 60s60s 180s180s 300s300s -- 30s30s 60s60s 180s180s 300s300s
30 %30 % -- 30s30s 60s60s 180s180s 300s300s -- 30s30s 60s60s 180s180s 300s300s
70 %70 % -- 30s30s 60s60s 180s180s 300s300s -- 30s30s 60s60s 180s180s 300s300s
100 %100 % 15s15s 30s30s 60s60s 180s180s 300s300s 15s15s 30s30s 60s60s 180s180s 300s300s
Physical properties: Physical properties:
Pellet lengthPellet length mm mm 13.00 - 15.00 13.00 - 15.00
Diameter of the pellet Diameter of the pellet mm mm 8.00-9.00 8.00-9.00
Average pellet weight Average pellet weight g g 5.00 5.00
Proximate analysis (wet basis): Proximate analysis (wet basis):
Ash content (550 ºC) Ash content (550 ºC) % % 11.10 11.10
Volatiles content Volatiles content % % 19.41 19.41
Fixed carbon Fixed carbon % % 62.79 62.79
HHV HHV MJ/MJ/kg kg
28.95 28.95
LHV LHV MJ/MJ/kg kg
27.99 27.99
Ultimate analysis (wet basis): Ultimate analysis (wet basis):
Moisture content (105 ºC) Moisture content (105 ºC) % % 6.7 6.7
Carbon (C) Carbon (C) % % 70.91 70.91
Hydrogen (H) Hydrogen (H) % % 3.73 3.73
Oxygen (O) Oxygen (O) % % 5.78 5.78
Nitrogen (N) Nitrogen (N) % % 1.40 1.40
Sulphur (S) Sulphur (S) % % 0.32 0.32
Chlorine (Cl) Chlorine (Cl) % % 0.01 0.01
Wood pellets combustion with rich and dilWood pellets combustion with rich and diluted air in HTAC furnaceuted air in HTAC furnace
55
Experimental Results:Experimental Results:
Mass loss -1000 C
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300
Time [s]
Mas
s [%
]
5% O2 10% O221% O2 30% O270% O2 100% O2
Mass loss - 800 C
0
10
20
30
40
50
60
70
80
90
100
0 50 100 150 200 250 300
Time [s]
Mass [
%]
5% O2 10% O221% O2 30% O270% O2 100% O2
b) NOx emission level
a) Mass loss
NOx 1000
0
500
1000
1500
2000
2500
3000
0 20 40 60 80 100 120 140 160 180
Time [s]
NO
x [p
pm]
O2 70%O2 30%O2 21%O2 10%O2 5%
NOx 800
0
200
400
600
800
1000
1200
1400
0 20 40 60 80 100 120 140 160 180Time [s]
NO
x [p
pm
]
O2 70%O2 30%O2 21%O2 10%O2 5%
Wood pellets combustion with rich and dilWood pellets combustion with rich and diluted air in HTAC furnaceuted air in HTAC furnace
66
Experimental Results:Experimental Results:c) CO2 concentration level
CO2 1000
0
2
4
6
8
10
12
14
16
0 20 40 60 80 100 120 140 160 180
Time [s]
CO
2 [%
]
O2 100%O2 70%O2 30%O2 21%O2 10%O2 5%
CO2 800
0
2
4
6
8
10
12
14
16
18
0 20 40 60 80 100 120 140 160 180Time [s]
CO
2 [%
]
O2 100%O2 70%O2 30%O2 21%O2 10%O2 5%
d) CO concentration levelCO 1000
9.0
9.5
10.0
10.5
11.0
11.5
0 50 100 150 200 250 300Time [s]
CO
[%]
O2 100% O2 70%O2 30% O2 10%O2 5%
CO 800
9,0
9,2
9,4
9,6
9,8
10,0
10,2
0 50 100 150 200 250 300
Time [s]
CO
[%
]
O2 100% O2 70%O2 30% O2 21%O2 5%
Wood pellets combustion with rich and dilWood pellets combustion with rich and diluted air in HTAC furnaceuted air in HTAC furnace
77
Experimental Results:Experimental Results:f) Ignition time and flame behavior
Ignition Time - 5 min
0
5
10
15
20
25
30
35
40
45
0 20 40 60 80 100Oxygen concentartion [%]
Tim
e [s
]
800 C
1000 C
Ignition time - 3 min
0
10
20
30
40
50
60
0 20 40 60 80 100
Oxygen concentration [%]
Tim
e [
s]
800 C
1000 C
5s 10s - ignition 100s 110s 125s - char
Oxidant at 1000 ºC and 5% oxygen concentration
Oxidant at 1000 ºC and 100% oxygen concentration
0s - ignition 2s 7s 70s 170s - char
Wood pellets combustion with rich and dilWood pellets combustion with rich and diluted air in HTAC furnaceuted air in HTAC furnace
88
Conclusions:Conclusions: Pellet mass reduction depends on oxidant temperature;Pellet mass reduction depends on oxidant temperature;
For lower oxidant temperature 800 ºC, the oxygen For lower oxidant temperature 800 ºC, the oxygen concentration has more influence over the mass loss than concentration has more influence over the mass loss than for the temperature of 1000 ºC;for the temperature of 1000 ºC;
The level of NOThe level of NOXX is proportional with the oxygen is proportional with the oxygen concentration and oxidant temperature; concentration and oxidant temperature;
The levels of CO2 and CO are also dependent on oxygen The levels of CO2 and CO are also dependent on oxygen concentration and temperature;concentration and temperature;
The ignition time is strongly influenced by the oxidant The ignition time is strongly influenced by the oxidant temperature and oxygen concentrations. temperature and oxygen concentrations.