Daniel Schneider SO3Reduction
-
Upload
edo-widi-virgian -
Category
Documents
-
view
214 -
download
0
description
Transcript of Daniel Schneider SO3Reduction
![Page 1: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/1.jpg)
SO3 Reduction in the Heavy-oil Fired Furnace
Power Engineering Dept.
Faculty of Mechanical Engineering and Naval Architecture
University of Zagreb, Croatia
mr.sc. Daniel Rolph Schneider
Prof. dr.sc. Željko Bogdan
![Page 2: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/2.jpg)
• Introduction
• Use of heavy-oil fuel, rich in sulphur, in combustors of steam generator furnaces causes increased SOx emission.
• Certain amount of SO2 is transformed into SO3 .
• SO3 reacts, at lower temperature, with water vapour forming sulphuric acidcauses low-temperature corrosion of the steam-generator sections.
![Page 3: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/3.jpg)
• Mathematical model:coupled gas flow and liquid spray physics, non-premixed turbulent flame, Fluent code
• turbulent flow: realizable k- model• radiation heat transfer: discrete ordinates model• liquid fuel spray: discrete second phase, “particle in
cell” model• formation of the pollutants: NOx , postprocessor• combustion model: probability density function (PDF)
formulation• reaction system: equilibrium chemistry formulation*
*OK for major combustion species (except NOx and soot) but not good enough for SO3 formation/destruction modelling!
• SO3 model: model based on finite rate chemistry,
implemented as User Defined Function routine
![Page 4: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/4.jpg)
• Kinetics of SO3 formation/destruction:
1
12 3SO O M SO M (1)
f
b
k
k
2310
1
1200.38 cm 19.2 10 exp
mol sfk RT
Recommended values for the third body reactants [M]: N2 /1.3/, SO2 /10.0/ and H2O /10.0/
2
23 2 2SO O SO O (2)
f
b
k
k
312
2
10064.95 cm 12 10 exp
mol sfk RT
11
1
fb
C
kk
K
22
2
fb
C
kk
K
KC – equilibrium constant
![Page 5: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/5.jpg)
• Mathematical model of SO3 formation:
3
3 3 3
SOSO SO SOj
j j j
Yu Y Γ S
x x x
Transport equation for SO3:
is diffusion coefficient of SO3:
3SOΓ effΓ
3SO
The source term is defined as:
3SOS 3 3 3SO SO SO 3SOS Y M
t t
Schmidt-Prandtl number is: =0.7
The rate of SO3 change for the reactions (1) and (2) is: 3
1 2 2 2 2 1 3 2 3
SOSO O M SO O SO M SO Of b b f
dk k k k
dt
![Page 6: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/6.jpg)
• Results:• Mathematical model was applied to simulate SO3 formation in
the furnace of a real steam generator of the 210 MW oil-fired Power Plant Sisak.
• PP Sisak burns heavy-oil fuel with 2-3% sulphur and exhibits flue gas temperatures of 135-140 C at the exit of the regenerative Ljungström air-heater, reported occurrence of the severe low-temperature corrosion of the generator “cold-end” surfaces.
![Page 7: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/7.jpg)
PRIMARY AIR
SECONDARY AIR
TERTIARY AIR
SECONDARY AIR SWIRLER TERTIARY AIR SWIRLER
ATOMISER NOZZLE
STEAM ATOMISER
TERTIARY AIR INLET SECONDARY AIR INLET
PRIMARY AIR INLET
Fig. 2. Schematic of the burner Fig. 1. Discretization of the furnace
• two oil burners (Fig. 1) on each side-wall of the chamber• the burner consists of the axial/radial inflow type swirl generating
register and the steam atomiser (Y-nozzle)• the airflow is divided into three streams: unswirled primary stream and
then secondary and tertiary streams, which are swirled
![Page 8: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/8.jpg)
Influences of different combustion parameters on SO3 formation (and
CO, NOx, soot) were analysed:
combustion air excess ratio,
magnitude of the swirl of combustion air,
fuel droplet size (as a function of atomising steam pressure and number of the openings of atomiser)
fuel injection spray angle
combustion air distribution (portion of primary, secondary and tertiary stream)
• Analysis:
![Page 9: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/9.jpg)
=1.105 =1.140 =1.175 =1.210
=0.965 =1.000 =1.070=1.035
XSO3
Fig. 3. Distribution of SO3 for different combustion air excess ratios
![Page 10: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/10.jpg)
Fig. 4. Molar fractions of a) SO3 and O , b) CO and H2 , c) NO and mean flue gas temperature, d) SO2 and soot vs. combustion air excess ratio
~50% SO3
soot [-]
soot
![Page 11: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/11.jpg)
XSO3
Fig. 5. Distribution of SO3 for different swirl numbers
S=0.44 S=0.48 S=0.55
S=0.63 S=0.68 S=0.71
![Page 12: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/12.jpg)
~30% SO3
Sl. 6. Molar fractions of a) SO3 and O , b) CO and H2 , c) exit flue gas temperature and heat flux, d) SO2 and soot vs. swirl number
soot [-]
soot
![Page 13: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/13.jpg)
XSO3
d=50 m d=70 m d=100 m d=130 m d=160 m
Fig. 7. Distribution of SO3 for different fuel droplet sizes
![Page 14: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/14.jpg)
~4.5% SO3
50-75% CO
Fig. 8. Molar fractions of a) SO3 and O , b) CO and H2 , c) NO and mean flue gas temperature, d) SO2 and soot vs. fuel droplet size
soot [-]
soot
![Page 15: Daniel Schneider SO3Reduction](https://reader035.fdocuments.in/reader035/viewer/2022081520/55cf9328550346f57b9c4328/html5/thumbnails/15.jpg)
• Conclusion:
• Proposed finite rate chemistry model of SO3 realistically describes SO3
formation/destruction.
• Such a model could be used in analysis of SO3 reduction.
Decrease of the air excess ratio reduced SO3 production, but increased
CO and H2 (incomplete combustion). Increase of magnitude of the swirl of combustion air, the fuel spray angle
and finer spraying (smaller fuel droplet size) lowered SO3 concentration
in lesser extent than the air excess ratio, but improved combustion (reduced CO and H2 formation).
The right strategy would be in combination of all these measures.