in-situ observation of the combustion of air-dried and wet ... · • combustion sequence is...
TRANSCRIPT
![Page 1: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/1.jpg)
Eleanor Binner, Lian Zhang, Sankar BhattacharyaDepartment of Chemical Engineering, Monash University
Chun-Zhu LiCurtin Centre for Advanced Energy Science and Engineering
Curtin University of Technology
InIn--situ Observation of the Combustion of situ Observation of the Combustion of AirAir--Dried and Wet Brown CoalDried and Wet Brown Coal
![Page 2: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/2.jpg)
2/20
Summary
• Australia’s role as a greenhouse gas emitter• Significance of Victorian brown coal research• Victorian State Government initiative• Dried brown coal combustion project• Preliminary results of dried brown coal project• A taster of the oxy-fuel results
![Page 3: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/3.jpg)
3/20
Greenhouse gas emissions per capita
Source: Commonwealth of Australia October 2008 “Australia's Low Pollution Future: The Economics of Climate Change Mitigation”, Table 3.2
![Page 4: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/4.jpg)
4/20
Power generation mix
Oil7%
Gas21%
Hydro15%
Other10%
Coal30%
Nuclear17%
Oil2%
Gas15%
Hydro6%
Other1%
Black Coal55%
Brown Coal21%
Australia 2005-62European Union 20071
1European Wind Energy Association (2008)2Australian Government department of Resources, Energy and Tourism (2008)
![Page 5: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/5.jpg)
5/20
Power generation mix
Oil2%
Gas15%
Hydro6%
Other1%
Black Coal55%
Brown Coal21%
Australia 2005-62
Brown Coal
•Australia has the largest brown coal reserves in the world, and is the fifth largest producer
•Predominant power source of Victoria
•Cheap, abundant source of energy
•Energy content ~10 GJ/tonne
•Brown coal accounts for ~11% of CO2 emissions in Australia
![Page 6: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/6.jpg)
6/20
Recognising the problem
• Victorian State Government “Energy Technology Innovation Strategy”
• Partnering researchers and industry to tackle the problem• Monash coal science group involvement:
– Dried Brown Coal Combustion– Oxy-Fuel Combustion– Gasification– New projects in chemical looping– Collaboration with Japan/India/Europe
![Page 7: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/7.jpg)
7/20
Victorian brown coal properties
• ASTM classification lignite B• High moisture content (50 – 70 wt%)• Low ash content (<2 wt% dry basis)• Volatile metallic species (Na, Mg, Ca)• High Oxygen (>25 wt% db)• Low carbon (<70 wt% db)• Sulphur generally low (<0.5 wt% db)• Abundant pore structures• Close to the properties of German brown coal, especially
Rhineland• Dissimilar to e.g. Czech and Russian brown coal
![Page 8: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/8.jpg)
8/20
Dried brown coal project
• ~20% of thermal energy generated used to evaporate water and superheat steam
• Efficient drying technologies could significantly decrease CO2 emissions per unit of energy produced
• Drying techniques– Evaporative drying– Non-evaporative drying
• This is an experimental study to determine the potential changes to combustion phenomena
– Ignition– Flame characteristics– Char structure– Char reactivity– AAEM volatilisation
• Complemented by modelling activities at CSIRO
![Page 9: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/9.jpg)
9/20
Dried brown coal project
• Drying will effect– Water content– Physical and chemical structure– Reactivity
• We are first using air-dried coal, and wetting it to obtain the ‘wet’ samples
• Later we will consider using coal dried by more realistic drying processes
![Page 10: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/10.jpg)
10/20
Drop tube furnace
Secondarygas
Coalfeeder
Primarygas
Pyrometer
To gas analyser
High-speedcamera
Water-cooled coal injection probe
2000
mm
300
mm
![Page 11: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/11.jpg)
11/20
Drop tube furnace
Secondarygas
Coalfeeder
Primarygas
Pyrometer
To gas analyser
High-speedcamera
Water-cooled coal injection probe
2000
mm
300
mm
![Page 12: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/12.jpg)
12/20
Drop tube furnace
Secondarygas
Coalfeeder
Primarygas
Pyrometer
To gas analyser
High-speedcamera
Water-cooled coal injection probe
2000
mm
300
mm
![Page 13: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/13.jpg)
13/20
![Page 14: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/14.jpg)
14/20
In-situ studies: high speed camera – 2000 fps, 1000°C
Wet Coal~30% water content
<105 um particle size0.2 m from injector
Dry Coal~10% water content
<105 um particle size0.15 m from injector
![Page 15: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/15.jpg)
15/20
Typical Phenomona Wet Coal Image d (m) Dry Coal Image Typical Phenomena
•Flame usually ignites below this window. 0.20 •Flame usually ignites
at this level or above.
•Constant stream of bright particles observed•Often forming localised fireballs•Clouds of steam evident
0.25
•Approximately 70% of the time, single or clusters of particles burning heterogeneously
•Predominantly individual particles 0.30 •Most of the frames
are blank
In-situ studies: ignition delay
![Page 16: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/16.jpg)
16/20
In-situ studies: particle temperature
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 0.651000
1020
1040
1060
1080
1100
1120
1140
1160
1180
1200
1220Av
erag
e P
artic
le T
empe
ratu
re (C
)
Distance from Injector (m)
wet dry
total gas flow rate 10 Lmin-1, coal feeding rate ~0.6 gmin-1
error bars represent ± 1 standard deviation
![Page 17: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/17.jpg)
17/20
In-situ studies: Findings
• Combustion sequence is similar for dry and wet coal• Cloud ignition takes place via a volatile flame, which causes
rapid heat-up of the particles and leads to heterogeneous char combustion
• Steam is evolved in the volatile flame in the wet case, decreasing flame stability and suppressing particle heat-up
• Ignition delay ~ 6 - 20 ms for wet coal in this furnace• Combustion is prolonged in wet coal• The maximum particle temperature is ~ 80°C higher in the dry
case
![Page 18: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/18.jpg)
18/20
Dried brown coal – Possible reasons for differences
• Energy used to vaporise water and superheat steam reduces the temperature in the furnace and cause an ignition delay
• Heat transfer in the furnace is expected to be suppressed by the presence of stream
• Other Involvement of water? – Could suppress volatile escape– Physical changes to char– Gasification of the char and/or evolved volatiles
C + H2 O H2 + COCO + H2 O CO2 + H2
– Could affect the role of alkali and alkaline earth metallic species (AAEM), which have a catalytic effect during brown coal combustion
– ?• Extensive analysis of char and ash planned to determine the chemical
effects of moisture content
![Page 19: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/19.jpg)
19/20Furnace temperature 1000Furnace temperature 1000ooC, particle size 105 C, particle size 105 –– 153 um153 um
100 mm 200 mm 300 mm 400 mm
Air
100 mm 200 mm 300 mm 400 mm
21% O2 + 79% CO2
Oxy-fuel Combustion
![Page 20: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/20.jpg)
20/20
Sankar Bhattacharya: [email protected]
Lian Zhang: [email protected]
Ali Akhavan: [email protected]
Eleanor Binner: [email protected]
![Page 21: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/21.jpg)
21/20
References
• ABARE, Energy and Minerals Branch (2008), Energy in Australia, Australian Government Department of Resources, Energy and Technology, p. 40.
• Australian Government (December 2008), Australia’s greenhouse gas emissions fact sheet
• Commonwealth of Australia (October 2008), Australia's Low Pollution Future: The Economics of Climate Change Mitigation, Table 3.2
• Energy Technology Innovation Division D.P.I., (19th December 2008), Energy Technology Innovation Strategy
• Geoscience Australia (2008), Australian atlas of minerals resources, mines and processing centres, E.a.T. Department of Resources
• Li C-Z (2004), Advances in the Science of Victorian Brown Coal, Chapter 1, Elsevier
![Page 22: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/22.jpg)
22/20
Project partners
ResearchFunding
In-kind contributions
![Page 23: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/23.jpg)
23/20
Reactor Capabilities
• Maximum furnace temperature ~ 1,200 °C.• Coal Feeding Rate 50 – 1,500 mg/min (ideally).• Effective furnace length can be changed by varying the coal injector
length.• Gas flow rate 0.5 – 20 L/min.• Residence times 2 – 20 seconds.• Combustion atmospheres of air, oxygen, carbon dioxide, nitrogen,
steam, or any combination, possible.• Transparent quartz reactor with five observation ports.• High speed camera and pyrometer installed to measure coal particle
temperature, velocity and flame properties.• Gas analyser for continuous on-line monitoring of flue gases (O2 , CO2 ,
CO, SO2 and NO)
![Page 24: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/24.jpg)
24/20
Mass f lowcontrollers
Coalfeeder
Primarygas
ONOFF
Temperaturecontrollers
Oscilloscope
Pyrometer
Secondarygas
Thimble filterSilica gel
Air O2 CO2
Air O2 CO2
PC
To gas analyser(O2, CO2, CO, NO, SO2)
High-speedcamera
HPLC pump
H2O
Drop Tube Reactor
![Page 25: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/25.jpg)
25/20
Photos of the Reactor FacilityPhotos of the Reactor Facility
![Page 26: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/26.jpg)
26/20
Burning coal particle observation:
In-situ observed by a state-of the-art high-speed camera (Motion Pro Y3, IDT Co., Ltd, Germany);
Anti-blooming CMOS sensor to avoid brightness saturation;
Shutter speed: 10~ 2000 frames per second (fps) for 2560 ×
2048;
Pre-calibration on its spatial and time resolutions each time;
Mounted with a macro lens having field of view of 2 cm square,and pixel resolution of ~100 µm (particle size~ 20 µm).
InIn--situ Diagnostic situ Diagnostic MethodsMethods (2)(2)
![Page 27: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/27.jpg)
27/20
Coal Samples Used
PROXIMATE• Ash content is 1.9 % (dry basis)• Moisture content 14.5 % (dry) and 31.9 % (wet)• Volatile 51.6% (db)
ULTIMATE• Carbon 65.3% (db)• Hydrogen 4.7% (db)• Nitrogen 0.55 % (db)
SIZE RANGE• <105 µm and 105 – 152 µm available
![Page 28: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/28.jpg)
28/20
(a) (b) (c) (d)
(e) (f) (g) (h)
(i) (j) (k) (l)
Ignition Studies - Phenomena
Combustion phenomena observed at 500 fps and exposure time ~990 ms for wet and dry coal total gas flow rate 10 Lmin-1, coal feeding rate ~0.6 gmin-1
![Page 29: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/29.jpg)
29/20
AAEM volatilisation - Overview
• Alkali and Alkaline Earth Metallic Species (Na, Ca, Mg) are dispersed in the coal on an atomic level, usually weakly bonded to organic compounds
• They can break these bonds and volatilise easily• They can then bind to inorganic anions such as OH-, SO2
-, Cl-, Al-Si etc.
• They can then condense into very small particles causing fouling and health problems
• Therefore, it is important to understand the effect drying the coal will have on the volatilisation of AAEM
• Investigations to be carried out at Chubu University
![Page 30: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/30.jpg)
30/20
AAEM - Chemical Analysis Techniques
• Computer-Controlled Scanning Electron Microscopy (CCSEM) - determine particle size distribution, particle shape and distribution of elements on the particles. Statistical analysis possible. Of a cross section of material.
• X-Ray Diffraction (XRD) – crystalline species measurement and quantification
• X-Ray Fluorescence (XRF) – elemental composition of ash• X-Ray Photoelectron Spectroscopy (XPS) – empirical formula,
chemical state and electronic state of elements of interest
A physical model of inorganic (ash) transformation during combustion
![Page 31: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/31.jpg)
31/20
AAEM - FactSage
• Chemical modelling package to compare with experimental results
• Transformation of refractory minerals and formation of slag
• Transformation of volatile and semi-volatile metals and especially their vaporisation/condensation
• Used to validate and gain a better understanding of the chemical analysis results
![Page 32: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/32.jpg)
32/20
Sample selection
Temperature 800 – 1000 C
Particle Size 106 – 153 µm
AtmosphereAirNitrogen
Gas Residence Time 2 – 4 seconds
![Page 33: In-situ Observation of the Combustion of Air-Dried and Wet ... · • Combustion sequence is similar for dry and wet coal • Cloud ignition takes place via a volatile flame, which](https://reader030.vdocument.in/reader030/viewer/2022041302/5e13480d01f66951341484f5/html5/thumbnails/33.jpg)
33/20
Australia, Kyoto and beyond
• Australian per capita CO2 emissions are 4.5 times the global average
• Australia ratified Kyoto Protocol in December 2007• Target is to increase emissions by 8% from the 1990 level over
the period 2008 – 2012• Projection is that emissions will be increased by 9% over that
period• Stationary energy emissions have increased by nearly 50%
since 1990• National Emissions Trading Scheme to take effect in 2010• Kyoto successor will be more stringent