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Copyright © 2011: Alternative Petroleum Technologies S.A.
Emulsified Fuels: Improved Combustion of Heavy Oils & Emission Control for Sustainable Fuels
At MEPEC 2011 by
Jyoti Seth, Richard Ellis, and Patrick Grimes
Alternative Petroleum Technologies Inc. www.altpetrol.com 1
Copyright © 2011: Alternative Petroleum Technologies S.A.
● Biodiesel in Engines
● Emission impact of Biodiesel and Biodiesel blends in light of emission norms
● Emulsified Biodiesel as solution for disadvantages of combusting neat biodiesel
● Heavy Fuel Oil in Furnaces
● Increased heavies content and contamination in tanks or during distribution
● Traditional approaches for effectively combusting heavier oil
● Emulsified fuels for improved efficiencies, lower emissions and cleaner operations
2
Copyright © 2011: Alternative Petroleum Technologies S.A.
● Biodiesel can be made from a wide variety of bio-fuel feedstock as well as a range of biodiesel-diesel contents depending on its intended use.
● There is however the problem of elevated NOX emissions from biodiesel, exemplified in this EPA graph showing NOX increasing with the concentration of biofuel.
3
Per
cent
cha
nge
in N
Ox
Em
issi
ons
Copyright © 2011: Alternative Petroleum Technologies S.A.
0.1 -
0.001 -
0.01 -
10 1 0.1 0.01
TIER 3 US 2004
US 2
004
EURO III
EURO
III
EURO
IV
EURO
V
TIER
4
US 2
007
/ 10
PM [g
/kW
h]
NOx [g/kWh]
Diesel 13% Emulsion
Reference: SAE 2003-01-3146. Influence of Water-Diesel Emulsions and EGR on Combustion and Exhaust Emissions of Heavy Duty DI-Diesel Engines equipped with Common-Rail Injection System. Bertola, A; Li, R, Boulouchos, K.
4
Copyright © 2011: Alternative Petroleum Technologies S.A.
● The rule of thumb is that for every 1% water NOx is reduced by 1% and PM by 2%. In fact the value of a percent of water is far greater at low water content for both diesel (B0) and B20.
1.70
0.69
0.15 0.25
1.15
0.24 0.32
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
0 5 10 15 20 25
NO
x R
educ
tion
(%R
educ
tion/
%m
wat
er)
%m Water
NOx Reduction (% Reduction per % water)
B0 B20 5.89
4.08
1.31 0.70
4.68
2.33
0.12 0
1
2
3
4
5
6
7
0 5 10 15 20 25
PM R
educ
tion
(%R
educ
tion/
%m
wat
er)
%m Water
PM Reduction (% Reduction per % water)
B0 B20
5
Copyright © 2011: Alternative Petroleum Technologies S.A.
● Requires -
● Atomization – combustion time
● Fuel-Air ratio – turbulence and mixing
● Flame temperature
Dust & Smoke
Dust is generated when oil is vaporized
but not combined with oxygen
Small carbon particles which are incompletely combusted, gather up
and become smoke, etc.
100-200 µm Heat of Combustion
Evaporative Combustion
6
Copyright © 2011: Alternative Petroleum Technologies S.A.
Parameters/Properties Units IS-1593 max FO sample Recent Trends
i. CCR (residual carbon) % mass 4.0 max 16.11
ii. Asphaltene / tar content % mass - 6.8
iii. Moisture Content % mass 1 max 0.29 Contamination
iv. Sediment % mass 0.25 max 0.03
v. Viscosity @50 degree cSt 250 max 204.3 -
vi. Viscosity @90 degree C cSt - 36.6 -
viii. Sulphur content % mass 4.5 max 3.5 -
ix. Density (@ 15 deg C) g/cc - 0.9761
x. Gross Calorific Value cal/g - 10820 -
Recent years have seen deteriorating quality of furnace oil
7
Copyright © 2011: Alternative Petroleum Technologies S.A.
● Higher viscosity – Affects fuel atomization and hence larger fuel droplets
0.1
1
10
100
1000
1 10 100 1000
Tim
e, t
(ms)
Droplet Size, d (m)
20 ms
68 ms
1.7dt ∝
200 µ
INSUFFICIENT TIME & higher un-burnt residues and increased fouling
8
Copyright © 2011: Alternative Petroleum Technologies S.A.
● Complete combustion needs sufficient Time, Temperature, and Turbulence
● Heavier components such as Asphaltenes, etc. are more viscous and require higher combustion temperature
● Un-burnt carbon and dust accumulate as slag and lead to fouling of boiler furnace and tubes and performance deterioration
0
2
4
6
8
10
0 0.5 1 1.5 2 2.5 3 3.5
Loss
of e
ffici
ency
(%)
Soot Layer Thickness (mm)
9
Copyright © 2011: Alternative Petroleum Technologies S.A.
● To avoid incomplete combustion and un-burnt carbon residue, users operate at high excess air for better mixing and TURBLUENCE
● Lower flame temperature and high stack losses impact efficiency
● Water in oil emulsions aid problems arising due to incomplete combustion
1600
2000
2400
0 2 4 6 8
AFT,
deg
. K
% Excess Oxygen
10
Copyright © 2011: Alternative Petroleum Technologies S.A.
● Emulsion Fuels are not new. When two immiscible fluids, oil and water are sheared together in the presence of a surfactant additive, a stable emulsion can be produced.
Water
Fuel
Additive High Shear
You need (1) enough energy and (2) good chemistry.
Water in OIL
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Copyright © 2011: Alternative Petroleum Technologies S.A.
● Modifications to boilers
● No modifications are necessary
● Protocols for “fuel switching” involve:
● Ensuring storage and recirculation temperatures don’t exceed 100C; and
● Adjusting excess air to for improvement atomization
● Reduction in NOx, enhanced combustion efficiency and lower PM
12
Copyright © 2011: Alternative Petroleum Technologies S.A.
● Micron sized droplets of water initiate secondary atomization and fuel is shattered to fine and turbulent mist of smaller droplets in air
● Improved turbulent mixing and virtually eliminates smoke
13
Copyright © 2011: Alternative Petroleum Technologies S.A.
● At 10% water in oil:
● Theoretical flame temperature (AFT) reduced by 0.65 %
1950
1970
1990
2010
2030
2050
2070
0 5 10 15 20 25
Adia
batic
Fla
me
Tem
p. (K
)
Emulsion Water Content (%)
(-28 K)
(-13 K)
14
Base Fuel
Copyright © 2011: Alternative Petroleum Technologies S.A.
● 10% water in oil is commensurate to
● Small increase in water content of flue gas stream (by 8.5 %)
● Low excess air levels are possible with emulsions
● Small trimming of excess air (6.8 %) is sufficient to off-set temperature reduction due to water
3.0
3.5
4.0
4.5
5.0
5.5
5
6
7
8
9
10
0 5 10 15 20 25
% E
xces
s O
xyge
n
% M
oist
ure
in F
lue
Gas
Emulsion Water Content (%)
(-0.16) (-0.34)
(0.26) (0.54)
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Copyright © 2011: Alternative Petroleum Technologies S.A.
● Relative contributions of
● added water in fuel and
● reduced excess air
● impact following parameters and hence the heat transfer dynamics:
Parameter Water Addition Air Reduction Combined
Flame T
Flame Emissivity
Radiation Heat
Reynolds No -
Prandtl No -
Heat Transfer Coefficient -
Un-burnt HC
Efficiency
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Copyright © 2011: Alternative Petroleum Technologies S.A.
● While efficiency increases with lesser excess oxygen, For every % water, efficiency is reduced by 0.13%
● Efficiency will increase by switching from base fuel operation at 5% to 2.5% excess oxygen efficiency increases from 83.5% to 84.3%
● With scope for further increase through even lower excess O2 and improved combustion
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Copyright © 2011: Alternative Petroleum Technologies S.A.
● Performance of emulsified fuel oil shows improvement over baseline fuel oil
13.4
13.6
13.8
14.0
14.2
14.4
14.6
14.8
15.0
15.2
15.4
15.6
15.8
16.0
0 10 20 30 40 50
Stea
m to
Fue
l Rat
io
Day of operation
14.65
14.68
14.96
FO EFO Same O2 setting
EFO O2 trimming
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Copyright © 2011: Alternative Petroleum Technologies S.A.
0
2
4
6
8
10
75 125 175 225 275
Smok
e In
dex
Fuel Flow Rate (kg/hr)
FO
FOE
with #6 FO (60X)
with FOE (60X)
19
100
120
140
160
180
200
75 125 175 225 275
NO
X (p
pm)
Fuel Flow rate (kg/hr)
FO
FOE
Copyright © 2011: Alternative Petroleum Technologies S.A.
FO FOE FOE + Trim
% Improvement 0.2% 2.1%
Predicted -1.0% 1.0%
Smoke Index 6.0 3.0 3.5
Soot Collection 12 kg / week - 2.4 kg / week
1 Week FO firing 1 Week FOE firing
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Copyright © 2011: Alternative Petroleum Technologies S.A.
● The improved combustion efficiency offered by Emulsion Fuels leads to the following benefits (both in Engines and Boilers):
● Fuel economy;
● Emissions Reductions;
● Reduced Engine / Boiler maintenance.
● These benefits have been illustrated:
1. Marine power generation
2. Port Terminals
3. Industrial Boilers
PORT
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