Transcript Emission Factors 2011 - acma

New UEF Emission Factors for SMC
Production and Compression Molding
David Lipiro
Environmental Compliance & Risk Management
[email protected]
ECRM
Terminology
• SMC = Sheet Molding Compound
• BMC = Bulk Molding Compound
• LCM = Liquid Composites Molding
• UEF = ANSI/ACMA/ICPA UEF-1-2009,
Estimating Emission Factors from Open
Molding and Other Composite Processes
(Current Version)
Factors for VOC Emissions
• Compounding (in UEF) – from SMC
machines – based on ECRM study
• Compression molding (proposed) –
SMC, BMC, LCM – based on EECS
studies (R. Haberlein)
Estimating Emissions
• Emission Factor = ratio
– Lb emitted/lb compound used = E/C = 0.002
– Lb emitted/lb styrene used = E/S = 0.02
• Equivalent Emission Models
– E = 0.002*C
– E = 0.02*S
– Simplest model  constant factor
• Derive models and factors from test data
Emissions vs Styrene Run
25
E, lb/hr
20
E = 0.2S
15
10
S
E
E/S
100
19.55
0.20
80
15.44
0.19
60
12.28
0.20
40
8.44
0.21
20
3.89
0.19
10
1.98
0.20
Average EF =
5
0
0
50
100
S, lb/hr
150
0.20
S
E
E/S
100
25.80
0.26
80
21.29
0.27
60
17.59
0.29
40
13.65
0.34
25
20
8.85
0.44
20
10
7.79
0.78
Emissions vs Styrene Run
40
E = 0.4S
35
E, lb/hr
30
E = 0.2S + 5
Average EF =
15
10
5
0
0
50
100
S, lb/hr
150
0.40
Compounding Emission Model
• Theory
• Lab weight loss experiments at MFG
Research – C. Piper
• Evaluate recent VOC emission tests
of 7 SMC machines
Theory
• Areas where paste is not covered by
carrier film = window to environment
Upper
Lower
• Exposed area A ft2 is constant for each
SMC machine
• Simplest model:
E lb/hr = kA, k = constant
Styrene Content?
• Affects skinover?
• Expected to be important based
on UEF for open molding
Line Speed?
• Skinover effect at longer travel
times  lower emissions at lower
linespeeds?
• Induced air velocity as paste
moves under air  impact
depends on vent airflow patterns?
MFG Lab Tests
• Wt loss by analytical balance + datalogger,
10 readings per second, 6-8 reps
• Constant sample pan area = 0.16379 ft2
• Range of S.G. and styrene % in pastes
used
• “Wind tunnel” w anemometer – simulate
motion-induced airflow
• Run times cover realistic line travel times simulate skinover
Conclusions/Predictions
• Not much skinover effect – most weight loss curves
linear or near
• Styrene content will probably have little impact on
emissions
• Line speed probably won’t effect emissions
• Emissions will vary with open area, temperature and
air velocity - only area practical for permitting
Field Verification
• Method 24 TTE emission tests
• 7 uncontrolled machines – 24”, 48”, 60”
• Wide range of open areas, styrene
contents, linespeeds
• No temperature control at doctor boxes
• Doctor boxes open to nearly closed
Field Data Analysis
• Regression: Emissions vs Predictor
• Predictors compared:
– Area
– Styrene throughput (traditional)
– SMC throughput
Emission vs Total Wet Area, with
Confidence and Prediction Limits
(k=3 for Prediction Limits)
E = 0.1457A - 0.1454
R2 = 0.9917
18
Emissions, lb/hr
16
Actual
14
12
LCL
10
8
UCL
6
LPL
4
UPL
2
0
0
50
100
Area, ft2
150
Figure 2. Throughput Model 1
y = 0.0009x - 1.773
R2 = 0.4
Styrene Emitted, lb/hr
16
1
14
12
2
10
3
8
4
6
5
4
6
2
7
0
0
5,000
10,000
SMC Run, lb/hr
15,000
Compounding Emission
Model in UEF
• Er = 0.1457*A-0.1454, where:
– Er = emission rate of SMC machine, lb/hr
– A = open wet area of machine (including
uncovered doctor box area), ft2
• Emissions = Er * t (hrs)
• Permitting: E is constant when paste
on line - throughput irrelevant
Compression Molding
• SMC, BMC, LCM
• Emissions from charge prep only Once press closes, negligible
emissions
• EECS Study: Charge prep
emissions measured in Method 204
TTE
SMC Compression Molding
• Two “traditional” EFs proposed
based on test data
• Which is best predictor?
• What are underlying models?
Compound Throughput Model
Emissions vs SMC Molded
E = 0.00148C + 0.10955
R2 = 0.74233
1.6
E = 0.002C
Emissions lb/hr
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
100
200
300
400
500
SMC molded, lb/hr
600
700
800
C, lb/hr
16
86
115
229
191
189
306
388
237
319
279
142
628
602
690
690
E, lb/hr
0.027
0.250
0.231
0.540
0.264
0.627
0.651
0.750
0.169
0.672
0.715
0.335
0.736
0.682
1.472
1.200
Average EF =
E/C
0.00164
0.00292
0.00201
0.00236
0.00138
0.00332
0.00213
0.00193
0.00071
0.00211
0.00256
0.00235
0.00117
0.00113
0.00213
0.00174
0.0020
Styrene Throughput Model
Emissions vs Styrene Molded
E = 0.0129S + 0.0646
R2 = 0.8093
1.6
E = 0.0152S
1.4
Emissions lb/hr
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0
20
40
60
Styrene molded, lb/hr
80
100
S, lb/hr
2.16
12.75
15.51
31.80
23.52
28.31
49.35
54.00
27.56
38.22
33.55
15.40
67.16
74.07
95.20
73.84
E, lb/hr
0.027
0.250
0.231
0.540
0.264
0.627
0.651
0.750
0.169
0.672
0.715
0.335
0.736
0.682
1.472
1.200
Average EF =
E/C
0.01250
0.01961
0.01489
0.01698
0.01122
0.02215
0.01319
0.01389
0.00613
0.01758
0.02131
0.02175
0.01096
0.00921
0.01546
0.01625
0.0152
EFs Compared
• E/C = 0.002 is poorer predictor
(R2=0.74, 10% total overestimate)
• E/S = 0.0152 is better predictor
(R2=0.81, 5% total overestimate), same form
as published AP-42 factor
• UEF: E lb = 1.5% styrene lb run vs 2% AP-42
factor
BMC and LCM
• UEF: BMC Molding Emissions = 1.15% of
styrene in compound molded
• UEF: LCM EF, lb styrene / lb paste
molded =
– Spread prep: 0.0072*S% + 0.008
– Pour prep: 0.0022*S% + 0.008
– LCM Emissions = EF * lb paste molded
Why Use These Factors?
• Best available methods to estimate
emissions w/o site testing
• Most credible factors available –
adopted into UEF by transparent ANSI
consensus process involving industry
and state/fed regulators
Thank you for attending
Questions
ECRM