wingra engineering, s.c.1 influence of emission estimates on bact for iron foundry core making...
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Wingra Engineering, S.C. 1
Influence of Emission Estimates on BACT for Iron Foundry Core Making
Steven Klafka, PE, DEEWingra Engineering, S.C.A&WMA Conference 2002
Wingra Engineering, S.C. 2
Iron Foundry Case Study
Existing iron foundry in Indiana. Addition of two coldbox core making
machines with combined capacity of 6 tons per hour.
Project required Prevention of Significant Deterioration (PSD) air quality permit.
Permit requirements included determination of Best Available Control Technology (BACT).
PSD applicability based on plant-wide VOC emissions increase from “debottlenecking”.
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Core Making Process
Cores form internal space in castings. Molten iron poured into molds flows
around core to form internal voids. Cores - mixture of sand & organic
resin. Resin type is phenolic-urethane. Catalyst used to activate resin.
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Core Making Process Cont’d
Mixing Organic binder mixed with silica sand.
Core Forming Sand/resin mixture blown into the mold box. Catalyst injected to cure resin. Catalyst purged from core machine.
Storage Core removed for finishing, storage,
delivery.
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Core Making Flow Diagram
Mixing
CoreMachines
CoreStorage
Baghouse Scrubber
VOCPM, VOC
VOC
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VOC Emissions from Catalyst
VOC generated by catalyst and resin Catalyst Emissions
Triethyl Amine or TEA Typical usage: 2-7 lbs/ton of core Proposed usage: 3 lbs/ton of core Assume 100% of catalyst emitted from core machines.
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VOC Emissions from Resin
Resin Emissions Evaporation of VOC constituents from mixing, core machine & storage Function of resin usage & VOC
content Little attention to resin losses in prior
BACT analyses or permits. Loss Range = 0.1 - 1.0 lbs/ton of core
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Resin VOC Emission Methods
American Foundryman’s Society (AFS) “Form R” booklet. Ohio Cast Metals Association (OCMA) study in 1998. Resin manufacturers evaporation
tests Core making stack tests
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AFS Form R Booklet
Produced by AFS and the Casting Industry Suppliers Association.
Assist foundries with Form R TRI. Provides estimates for reportable
chemicals in core and mold binder. Estimates fraction of resin
remaining in core and fraction released.
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Resin Loss Using AFS Form R
Constituent Content
(%) AFS Loss
(%) Resin Loss
(%) Formaldehyde 0.11 2.00 0.002 Naphthalene 4.92 3.25 0.160
Trimethylbenzene 1.62 3.25 0.053 Total 0.215
Total Resin Loss = 0.215%
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1998 OCMA Study
Laboratory resin evaporation tests.
Measured weight loss during mixing, forming, and storage.
No catalyst used during test. Based on 1% resin in core sand.
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Resin Loss using OCMA Study
Step Time
(hours) Resin Loss
(%) Resin Loss
(% of Total) Mixing 0.03 0.39 12 Machine 0.5 0.55 17 Storage 3 0.77 24 Storage >3 1.55 47 Total 12 3.26 100
Total Resin Loss = 3.26%
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Resin Manufacturer Tests
Based on OCMA methodology. Various resins evaluated to
compare evaporative losses. Resin alternatives suitable for
Indiana project.
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Resin Loss from Manufacturers
Resin Time Elapsed
(hours) Resin Loss
(%) A 3 3.0 B 3 1.2
Total Resin Loss = 1.2 to 3.0%
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Core Making Stack Tests
Conducted on existing operations Tests for mixing and core machine Testing of core storage area not
practical due to open area. Total VOC measured by Method 25 TEA measured by Method 25A
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Resin Loss using Stack Tests Mixing
Method 25A: 0.54 lbs VOC/hr, 0.40% of resin Method 25: 0.61 lbs VOC/hr, 0.45% of resin
Core Machine Method 25A: 14.0 lbs VOC/hr Method 25: 16.5 lbs VOC/hr Method 25: 17.6 lbs TEA/hr, 3.4 lbs VOC/ton TEA emissions > Total VOC Resin loss measurements not possible.
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Resin Loss Comparison
Method AFS OCMAMfg A
Mfg B
Test
Resin Loss(%)
0.215
3.26 3.0 1.2 0.45
VOC @1%(lbs/ton)
0.043
0.65 0.60 0.24 0.09
VOC @1.5%(lbs/ton)
0.06 0.98 0.90 0.36 0.14
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Final Mixing Loss Estimate
Mixing Loss Test used Resin A; project to use Resin B Combined stack test and mfg lab tests Resin B Loss = 0.45% Resin A Loss x (1.2/3.0) = 0.18% Resin B Loss = 0.14 lbs/ton Resin A Loss x (1.2/3.0) = 0.05 lbs/ton
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Core Machine Loss Estimate
Core Machine Loss Combined stack test and mfg lab tests Mfg Total Resin B Loss – Mixing Loss 0.36 – 0.05= 0.31 lbs/ton
Storage Loss Losses included with core machine.
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BACT Control Options Mixing
Regenerative Thermal Oxidizer Carbon Adsorption
Core Machine Packed Bed Scrubber Regenerative Thermal Oxidizer Carbon Adsorption
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Mixing BACT Analysis
Control Alternative Uncontrolled
VOC (lbs per hour)
Cost Effectiveness ($ per ton)
RTO 0.30 609,810 Carbon Adsorption 0.30 161,920
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BACT for Mixing
High cost effectiveness due to relatively low VOC emissions.
IDEM feasibility “threshold” of $8,000 per ton of VOC removed.
No add-on controls required.
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Core Machine BACT Analysis
Control Alternative
Uncontrolled VOC
(lbs per hour)
Controlled VOC
(lbs per hr)
Cost Effectiveness ($ per ton)
Carbon Adsorption
19.86 0.40 14,520
RTO 19.86 0.40 9,041
Scrubber 19.86 2.22 2,835
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BACT for Core Machine
RTO and carbon adsorption exceed IDEM threshold for economic infeasibility.
RTO exceeds cost effectiveness used for prior Wheland BACT of $4,928/ton.
Packed bed scrubber considered BACT.
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RTO Cost Effectiveness Versus Resin Loss
BA
0
20004000
6000
8000
1000012000
14000
0 1 2 3
Resin Loss Emission Factor(lbs per ton of core)
Cost
Eff
ect
iveness
($ p
er
ton V
OC)
2 lbs TEA/ton 3 lbs TEA/ton4 lbs TEA/ton 5 lbs TEA/ton
BA
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Effect of VOC Loss on RTO Cost
Cost effectiveness varies with catalyst usage and resin losses.
Typically values can result in RTO as BACT. If case study foundry had used Resin A --
Core machine resin loss increases from 0.36 to 0.90 lbs/ton.
Cost effectiveness decreases to $7,676/ton. RTO becomes economically feasible and BACT.
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Conclusions Use of RTO on core making
operations will receive serious consideration for future BACT evaluations.
Cost effectiveness and feasibility of control options are dependent on catalyst usage and resin losses.
Resin losses, though small, effect the outcome of the BACT analysis.