Using Monte Carlo Simulation
for Air Emission Inventories
Brian Freeman
Integrated Environmental Solutions Company
Kuwait City, Kuwait
11 June 2013
Agenda
•
•
•
•
•
•
Air Emission Inventories
Concentration Conversions
Air Dispersion Modeling
Source Modeling
Southern Kuwait Example
Evaluating Air Quality Trends
Air Emission Inventories
• The amount and type of emissions from a
process/site per unit time (per annum)
• Emissions from:
– Combustion and thermo-oxidation
– Chemical processes and reactions
– Fugitive sources, leaks and venting
– Tanks and transfer operations
Quantifying Emissions
Cost
CEMS
Stack Monitoring
Software Monitoring
Process Monitoring
Engineering Models
Accuracy
Emission Factor Calculations
• Basic Parametric Calculation
Ei = EFi x Q(t)
Where
Ei = Total Emissions of Species i
EFi = Emissions Factor for Species I
Q(t) = Process feedstock (gas, coal, wood)
• EF are inaccurate, out dated, and not time variant
• EFs are cheap and widely accepted
Emission Sources
Exhaust
VOCs
Tank Vent
Storage Tank
VOCs
Transmission
Leaks
Engine
CO2
CO
NOx
SO2
VOCs
Feedstocks are not Equal
Low Pressure Flare Gas
Component
Methane
Ethane
Propane
n-Butane
H20
CO2
I-Butane
n-Pentane
i-Pentane
n-Hexane
n-Heptane
Benzene
n-Octane
H2S
N2
n-nonane
n-decane
Ave Mol%
53.44%
17.17%
13.48%
4.75%
2.60%
1.84%
1.64%
1.64%
1.16%
0.77%
0.58%
0.38%
0.19%
0.09%
0.09%
0.06%
0.02%
Component MW
Normalizing Components
Should equal 100%
If %Moli is an RV, %Moltot will not sum to 100%
Equally weight the
components to correct:
Goes out the stack…
Air Dispersion Models
•
•
•
•
Weather
Emissions
Topography
Distribution Model
Time Weighted
Average
Concentrations at
Downwind
Receptors
Puff and Plume Models
Time
Approved by regulators
Wind
Puff
Model
Plume
Model
Input Parameters
•
•
•
•
•
•
•
Stack Height (fixed)
Stack Diameter (fixed)
Exit Velocity (variable)
Exit Temperature (variable
Emission Type (fixed)
Emission Rate (variable)
Wind fields (complex)
Concentration Conversion
• Monitors usually measure concentration in ppm
• Models usually work in ug/m3
mg ( ppm ) * P * MW
3
=
* 10
3
m
R *T
Where
P = atmospheric pressure
MW = Molecular Weight of substance
R = gas constant
T = absolute temperature
Random Variables
•
•
•
•
•
•
Feedstock Quantity
Feedstock Composition
Emission Factor
Atmospheric Pressure
Exhaust Temperature
Exhaust Velocity
Concentration
Source
AQMS #1
East Shuaibah
Industrial Area
West Shuaibah
Industrial Area
Source
Um Al Hayman
Residential Area
0 km
AQMS #1 :Fahaheel ,AQMS #2 :Um al Hayman
AQMS #2
10 Km
Controlled Process Emissions
Combined Total of Average of Annual
Emissions (tonnes/year)
Pollutant Process Combustion Total
VOC
6.9
0.2
7.1
NO2
3.6
11.5
15.1
PM
6.6
6.6
SO2
1.3
0.9
2.2
Uncontrolled Process
Emissions
(See Summary Table)
Captured PM
Material
Process
LPG
Pollution
Control
Equipment
Products
Modeling SO2
P1
P2
Modeling SO2 - cont
• Combine P1 and P2 using
– a binomial model (n=1,p=P2)
– Excel if Statement
Converting to ug/m3
AQMS #1
Fahaheel AQMS
Um Al Haymam AQMS
AQMS #2
Distance between Source and Um al Hayman AQMS: 7.9 Km, 140o
Distance between Source and Fahaheel AQMS: 9.45 Km, 360o
CALPUFF INPUTS
Run Length
3 CY*
Time Zone
UTC +0300
Receptor
@ Ground Level
Radius for Modeling
* Calendar Year
15 Km
Coordinate X(m)
220809 E
Coordinate Y(m)
3210657 N
Zone
39R
Stack Height(m)
49
Stack Interior Diameter(m)
3.7
Exit Velocity(m/s)
12
Exit Temperature(K)
313
CY:2008-2010
AQMS #1
5 Km
1 Km
AQMS #2
1 Hr NOX
Emission rate: 15.1 tonnes/yr
CY:2008-2010
AQMS #1
5 Km
1 Km
AQMS #2
1 Hr SO2 (SOX)
Emission rate: 2.2 tonnes/yr
SO2 Contribution
Air Quality Evaluation
Sample 95%
Concentration Frequency
KEPA Ambient
Air Data
Calculated
PDF
Um Al Hamen SO2
2008
2011
KEPA SO2 1 Hr Limit of
0.08 ppm not shown
15% Decrease
ppm
KEPA Limit based on STP of 25 Deg C at 1 ATM
Fahaheel SO2
2008
2009
2010
2011
45% Decrease
ppm
KEPA Limit based on STP of 25 Deg C at 1 ATM
Air Quality Summary
Fahaheel
% Average Change from 2008
NO2
SO2
O3
NO2
SO2
O3
PDF
Mean
116%
-16%
-4%
PDF Sample Sample Sample
Mean Mean 95% Skewness
41%
40%
47%
159%
-13%
-6%
-6%
73%
-9%
-9%
-16%
6%
Um Al Hamen
% Change from 2008
Sample Sample
Sample
Mean
95%
Skewness
116%
159%
300%
-9%
-28%
58%
-4%
1%
2%
NO2 increases
significantly at the
southern sites
SO2 decreases
slightly
O3 stays the same