8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 1/20
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 2/20
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 3/20
Emissions, What Are They?
Nitrogen Oxides (NOx)
Nitric Oxide (NO) & Nitrogen Dioxide (NO2)
Carbon Monoxide (CO)
Aldehydes
Hydrocarbon Recombinations, i.e. CH3OH
Particulates
Soot (Dry Carbon), Oil, Inorganics (Sulfur)
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 4/20
Emissions, What Are They?
Total Hydrocarbons (THC) or Unburned
Hydrocarbons (UHC)
Unburned Fuel CH4, C2H6, C3H8, …...
Also Known as: VOC Volatile Organic Compounds
ROC Reactive Organic Compounds
ROG Reactive Organic Gases
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 5/20
Emissions, Why Are They Bad?
Health Related Issues from Ingestion
Contribute to Acid Rain
Production of Ozone (O3)
Smog Creation
Global Warming
Greenhouse Gases
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 6/20
Emissions, Why Are They Bad? Unburned Hydrocarbons
Promotes Conversion of NO Into Ozone.
Reactivity of Components Vary – Methane - Low
– Butane - High
Therefore Regulations May Specify TotalHydrocarbons, Non-Methane HC, or Non-
Methane Non-Ethane HC
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 7/20
Global Warming
INCREASED REFLECTION BY ATMOSPHERE OF INFRA-RED
RADIATION FROM THE EARTH WARMS THE CLIMATE.
SUN INFRA-RED
RADIATION
greenhouse
gases
ATMOSPHERE
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 8/20
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 9/20
Why Emissions Are Good For Gas
Business!
18
9
5
1.5 1.3 0.5 0.3 0.3
0
2
4
6
8
10
12
14
16
18
20
22
N O x ( g / b h p -
h r )
g/bhp-hr (grams per brake horsepower hour)
Stoich
Gas
D3600 D3500B Turbine
Std.
Comb.
G3500 Turbine
SoLoNOx
G3600 3-Way
Catalyst
(Dual
Stage)
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 10/20
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 11/20
What To Do About Emissions
Reduction Via Control in Combustion Chamber Lean Burn-Cooler Combustion Reduces NOx but Increases
CO
Retard Timing-Cooler Combustion
Reduction Via Aftertreatment of Exhaust Gas
Thermal Reactors Oxidize CO, HC - Corr. Gases (800+ C
Exh Temps-$200/hp)
Catalytic Converters (3-way, Oxidation, SCR)
Particulate Traps (Only Diesel)
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 12/20
NOx Characteristic
NOx
LAMBDA=(A/F actual)/(A/F stoich)
2
4
6
8
10
12 14
16
18
20
22
0.8
Rich Burn LAMBDA Lean Burn
0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 0 O 2
( % D R Y )
N O x
( g / h p - h r )
EXHAUST
OXYGEN
COMBUSTION
TEMP
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 13/20
CO Characteristic
0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 0
2
4 6
8
10
12
14 16
18
20
22
24
C O ( g / h p - h r )
CO
Rich Burn LAMBDA Lean Burn
lack of O 2
Exhaust
Oxygen
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 14/20
NOx (mg/Nm3)
Electrical
efficiency
35
36
37
38
39
40
41
42
43
100 200 400 600 800 1000
1/2 TA Luft TA Luft
Denmark NOx
regulation
Efficiency
Range
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 15/20
What To Do About Emissions
Catalytic Converters
Oxidation Catalyst Used with Lean Burn Reduces CO (50-90%) and HC (50%)
Uses Platinum and Palladium
CO2
H2O
CXH Y
CO
O2
Oxidation Catalyst
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 16/20
Emissions - Units
G / bhp-hr
Reported at Actual Exhaust 02
Use to Calculate Tons / Yr , Lb / Day , etc…..
PPM @ X 02%
Corrected to 15% 02
Use to Compare Other Manufacturers
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 17/20
Emissions - Conversions
PPM measured * (20.9-X% O2)
PPM @ X% O2 = --------------------------------------
(20.9-%O2 measured)
Conversion to Different Exhaust Oxygen Levels
1 ppm NOX = 2.052 mg NOx/Nm3 Exhaust Gas1 ppm CO = 1.25 mg CO/Nm3 Exhaust Gas
1 ppm CH4 = 0.716 mg CH4/Nm3 Exhaust Gas
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 18/20
Conclusion
What are Emissions?
Why are They Bad?
How are They Formed?
What to do About Them.
8/12/2019 GAS ENGINE Air/Fuel Adjustment
http://slidepdf.com/reader/full/gas-engine-airfuel-adjustment 19/20
OPERATION AREA FOR LEAN BURN
STOICHIOMETRIC MIXTURE
LEAN
LEAN MISFIRE
RICH MISFIRE
RICH ESTANDARD
TA LUFT
BEST ECONOMY
0,2
0,4
0,6
0,8
1,0
1,2
1,4
1,6
1,8
L A M B D
A
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210
M.A.P. kPa
D E T O N A T
I O N