# Formaldehyde from Natural Gas Fired

Reciprocating Engines and Turbines

Emission Levels and Testing Methods

Presented to:

Rocky Mountain Environmental Peer Group

July 2002 Meeting

Presented by:

Paul Ottenstein

Technical Director

Air Pollution Testing

# Formaldehyde - Is it worth worrying about?

General Data

Physical Properties

Exposure limits

Health Effects

Sources

Used industrially

Naturally occurring

Product of incomplete combustion

Control

Maintenance

Catalytic Oxidation

Regulatory Issues

HAP

MACT concern for natural gas combustion

AP-42 Emission Factors

APT Test Data

Formaldehyde - How should I test for it?

2,4-Dinitrophenylhydrazine Methods

EPA 0011

CARB 430

FTIR Methods

EPA 318

EPA 320

Colorimetric

CTM 037

EPA 316



# Formaldehyde General DataPhysical PropertiesCGas at room temperature (boiling point = -19.5 C)CVapor density = 1.07 (air = 1)CVery water solubleCGenerally purchased in solution37% formaldehyde, 10% - 15% methanol, 48% - 53% waterFormaldehyde in this solution is hydrated as H C(OH)2 2Exposure Limits(from Material Safety Data Sheet Effective 9/14/00)COSHA0.75 ppm (TWA)2 ppm (STEL)0.5 ppm (TWA action level)CACGIH0.3 ppm (TLV)Health EffectsCRespiratory tract irritant, severe at high levels (25 - 30 ppm) - possibly fatalCSevere skin irritant - redness, pain, possible burnsCChronic inhalation is a suspected (probable) carcinogenFormaldehyde SourcesIndustrial UsesCDomestic use estimated at 1.4 million tons annuallyCThe glue or adhesive in pressed wood products (particle board, hardwood plywood,medium density fiberboard)CPreservatives in some paints, coatings and cosmeticsCDurable press fabrics, draperies, and coated paper productsCInsulation materials (urea-formaldehyde foam and fiberglass insulation)Naturally OccurringCOne of 27 compounds identified in the interstellar space of the Milky WayCPresent in human breathProduct of Incomplete CombustionComplete methane combustion:CH + 2OYCO + 2H O42 22CFinal state of carbon atom is O=C=O (carbon dioxide)COxidation proceeds in stepsCFormaldehyde is formed as a normal intermediate which is typically consumed in the latterstages of combustionCHYH C=O (formaldehyde)YC=O (carbon monoxide)YO=C=O (carbon dioxide)4 2However, the completion can be retarded by:Ccombustion quenching from cooler temperatures (close to walls of the combustion chamber)Crich and lean sections from poor fuel mixingFormaldehyde measurements during the combustion process are much higher (5 to 10 times)than exhaust measurements.Formaldehyde ControlMaintenance has been shown to reduce formaldehyde emissionsEngine IDAs Found HCHOMaintenance ActivitiesFinal HCHO(gm/hp-hr)(gm/hp-hr)Clark HRA-8 0.38 Plugs, head gasket, fuel valve packing, cam/ignition timing, 0.33#23 exhaust port carbon deposit removalClark HRA-8 0.33 Plugs, fuel valves, air starting valves, ignition timing, 0.31#24 intake/exhaust port carbon deposit removalClark HBAT-8 0.71 fuel valves, head gasket, air valve gaskets, fuel leaks, 0.35#25 intake/exhaust port carbon deposit removal, ignition timing,cleaned mineral deposits in aftercoolerCatalytic oxidation systems might control formaldehyde emissionsCatalyst TypeUnitNOControlCO ControlTHC/HCHO ControlXNSCR 4SRB 90% - 99% 90% - 98% ??Oxidation Catalyst 4SLB -- >90% ??2SLB -- 70% - 90+% ??Turbine -- 98% 50%-95%SCR LB (constant load) 77% - 90% -- --Formaldehyde Regulatory IssuesHazardous Air PollutantC180+ Compounds, regulated as “HAPs”CAromatics (BTEX, etc.)CHalogenated (chlorobenzene, 1,2-dibromo-3-chloropropane, etc.)CHeavy metals (Hg, Pb, etc.)CAldehydes (formaldehyde, acetaldehyde, acrolein, etc.)CRegulated by over-all mass emission rate approach (vs. “potential to harm”)C10 tpy any one HAP or 25 tpy any combination = major sourceCFormaldehyde is only likely compound for the 10 tpy, and the 10 tpy will likely betriggered before the 25 tpy with all other HAPsC“Potential to Harm” is probably negligibleCAlleged atmospheric fate is photochemical reaction with <1 day half-lifeCHuman exposure from combustion sources is believed to be smallMACT Concern for Natural Gas CombustionC3-Way (NSCR) catalyst for rich-burn will be MACT floor (required for major sources)CBased on cleanest 12% of unitsCMACT floor is “no control” for lean-burnCCatalyst requirement would include a cost/benefit analysisAP-42 Emission Factors - Reciprocating EnginesFormaldehydeEmission Assumptions CalculationsType Technique # of Factor RSD BSFC O HP for 102tests lb/MMBtu % Btu/bhp-hr %vd ppm gm/bhp-hr tpy2SLB FTIR 58 5.52E-0246.3 8,000 8.0 34.3 0.20 5,1702SLB DNPH 8 4.06E-02 73.7 8,000 8.0 25.2 0.15 7,0294SLB FTIR 32 5.28E-0231.7 8,000 8.0 32.8 0.19 5,4054SLB DNPH 5 1.38E-02 63.7 8,000 8.0 8.6 0.050 20,6804SRB All 18 2.05E-0287.5 8,000 0.0 20.6 0.074 13,921AcetaldehydeEmission Assumptions CalculationsType Technique # of Factor RSD BSFC O HP for 102tests lb/MMBtu % Btu/bhp-hr %vd ppm gm/bhp-hr tpy2SLB FTIR 58 7.76E-0374.6 8,000 8.0 4.8 0.028 36,7772SLB DNPH 4 5.22E-03 34.6 8,000 8.0 3.2 0.019 54,6724SLB FTIR 31 8.36E-0372.9 8,000 8.0 5.2 0.030 34,1374SLB DNPH 1 8.56E-04 -- 8,000 8.0 0.5 0.0031 333,3974SRB All 9 2.79E-0384.5 8,000 0.0 2.8 0.0101 102,290Note: Underlined values are the factors provided in AP-42, 5 Edition, Volume I, Final SectionthAP-42 Emission Factors - TurbinesFormaldehydeEmission Assumptions CalculationsFuel Load Control # of Factor RSD BSFC O HP for 102tests lb/MMBtu % Btu/bhp- %vd ppm gm/bhp-hr tpyhrGas All none 33 3.12E-03 204.0 10,000 14.0 1.52 0.0142 73,176Gas All CO Cat 2 3.60E-04 133.5 10,000 14.0 0.17 0.0016 634,196Gas >80% none 22 7.09E-04206.1 10,000 14.0 0.34 0.0032 322,018Gas >80% CO Cat 2 3.60E-04 133.5 10,000 14.0 0.17 0.0016 634,196Gas <80% none 11 7.94E-03 unk * 10,000 14.0 3.86 0.0360 28,754Oil All none 10 2.45E-04 120.6 10,000 14.0 0.11 0.0011 931,880Oil >80% none 8 2.82E-04115.0 10,000 14.0 0.13 0.0013 809,612* - calculated from "All" and ">80%"AcetaldehydeEmission Assumptions CalculationsFuel Load Control # of Factor RSD BSFC O HP for 102tests lb/MMBtu % Btu/bhp- %vd ppm gm/bhp-hr tpyhrGas All none 9 4.45E-05 64.3 10,000 14.0 0.015 0.00020 5,130,573Gas All CO Cat 2 1.76E-04 139.5 10,000 14.0 0.059 0.00080 1,297,219Gas >80% none 8 4.02E-0568.0 10,000 14.0 0.013 0.00018 5,679,366Gas >80% CO Cat 2 1.76E-04 139.5 10,000 14.0 0.059 0.00080 1,297,219Oil All none 2 3.03E-05 36.9 10,000 14.0 0.010 0.00014 7,535,000Note: Underlined values are the factors provided in AP-42, 5 Edition, Volume I, Final SectionthAP-42 Emission Factors - NotesReciprocating EnginesCNO and CO emission factors are presented for high (90-105%) and low (<90%) loads. HAPsXshowed no clear load dependence and are not broken out by load.CFTIR and DNPH factors are separated for LB engines (FTIR promulgated in Final Section)CEPA claims negative bias in the DNPH data due to oxygen and nitrogenCAcetaldehyde factors are about 1/7 of the formaldehyde factorsTurbinesCGenerally low ppm, except the calculated low-load data setCAlmost 4 ppmC11 measurementsCNO control had no observable impact on aldehyde emissionsXCOxidation catalyst provided only about 50% formaldehyde controlCSection 3.1.4.3. of AP-42 Final Section claims 85%-90% controlCGRI vendor survey indicates a wide range for turbine oxidation catalyst formaldehydecontrol, but generally the expected control is lower (significantly) than expected CO controlCGenerally poor data for predicting emissionsCExtremely large RSD (greater than 100%)CAcetaldehyde actually increases across with oxidation catalyst (indicating data uncertaintyrather than acetaldehyde production)APT Test Data - Reciprocating Engines and TurbinesFormaldehydeEmission Assumptions CalculationsUnit Control # of Factor RSD BSFC O HP for 102tests lb/MMBtu % Btu/bhp-hr %vd ppm gm/bhp-hr tpyLB none 29 5.21E-02 66% 8,000 8.0 47.33 0.1891 5,478LB ox cat 31 7.12E-03 66% 8,000 8.0 6.47 0.0258 40,083** Avg Lean Burn Ox Cat Control Efficiency 86.3%RB none 3 1.01E-02 41% 8,000 0.0 14.87 0.0367 28,256RB NSCR 2 1.57E-03 49% 8,000 0.0 2.31 0.0057 181,776** Avg Rich Burn NSCRControl Efficiency 84.5%Turbine none 6 4.63E-03 177% 10,000 14.0 2.25 0.0210 49,311APT vs. AP-42CLB Reciprocating EnginesCAPT: 0.0521 lb/MMBtuCAP-42 0.0543 lb/MMBtu(weighted average of 2S and 4S FTIR measurements)CRB Reciprocating EnginesCAPT: 0.0101 lb/MMBtuCAP-42: 0.0205 lb/MMBtuCTurbinesCAPT: 0.00463 lb/MMBtuCAP-42: 0.00312 lb/MMBtu(published value for all loads, uncontrolled)Test MethodsThree measurement techniquesCDirect spectrophotometric measurement (FTIR)CIntegrated sample collection, reaction, and chromatographic analysisCIntegrated sample collection, reaction and colorimetric analysisSampling differences for the integrated sampling techniquesCIsokinetic or not?CExpected exhaust gas temperatures would seem to eliminate the need for isokineticsamplingCFTIR measurements will not be isokinetic (in fact, deliberately excluding particulatematter)Work is ongoing to calculate formaldehyde emissions without direct measurementCAttempts to predict based on measurement of CO, NO or NMHC have generally failedX(SeeCharacteristics of Formaldehyde Emissions from Natural Gas-Fired ReciprocatingInternal Combustion Engines in Gas Transmission, Volume III: Evaluation of Low-CostFormaldehyde Measurement Techniques)CAttempts to calculate based on engine parameters show promise(SeeCharacteristics of Formaldehyde Emissions from Natural Gas-FiredReciprocating Internal Combustion Engines in Gas Transmission, Volume I: Phase IPredictive Model for Estimating Formaldehyde Emissions from 2-Stroke Engines)Test Methods - 2,4-Dinitrophenylhydrazine (DNPH) MethodsEPA 0011: Sampling for Selected Aldehyde and Ketone Emissions from Stationary Sources(http://www.epa.gov/epaoswer/hazwaste/test/main.htm)Test Methods for Evaluating Solid Waste, Physical/Chemical MethodsFirst published in 1980, periodically revised - currently on 3 EditionrdA gas sample is extracted isokinetically through an in-stack nozzle, through a heated glass probe,through a series of impingers seeded with 2,4-DNPH absorbing solution, and through a calibrateddry gas meter. Following sampling, the contents of the impingers along with a series of water andmethylene chloride rinses of the nozzle, probe, impingers and connecting hardware are recoveredin an amber glass bottle for off-site analysis. Aldehydes and ketones in the solution react with the2,4-DNPH to form dinitrophenylhydrazone derivatives, which are extracted, solvent exchanged,concentrated, and analyzed using high performance liquid chromatography (HPLC). Qualityassurance samples consist of a Field Blank, Field Spike, and (maybe) a Matrix Spike.CAdvantagesCVast amount of supporting dataCSpeciates most aldehydes (can provide acetaldehyde number), no cross-interferenceCLow detection limits (ppb range) - particularly useful for turbinesCDisadvantagesCOff-site analysisCReagent shelf-life and shipping hazardsCIsokinetic sampling train - requires better access to larger sampling portsC“High” levels of NO can consume the sampling reagent2Test Methods - 2,4-Dinitrophenylhydrazine (DNPH) MethodsCARB 430: Determination of Formaldehyde and Acetaldehyde in Emissions from StationarySources (http://arbis.arb.ca.gov/testmeth/vol3/vol3.htm)Stationary Source Test Methods, Volume 3, Methods for Determining Emissions of Toxic AirContaminants from Stationary SourcesA gas sample is extracted at a constant flow rate, pulled through a stainless steel probe,through two midget impingers seeded with 2,4-DNPH, and through a calibrated dry gasmeter. The impinger contents and a series of water and 2,4-DNPH rinses of the samplinghardware are recovered for off-site HPLC analysis. Quality assurance samples consist ofthree field blanks and a matrix spike (split from one run).CAdvantagesCQuite a bit of supporting data - used extensively in AP-42 data collectionCSpeciates most aldehydes (can provide acetaldehyde number), no cross-interferenceCLow detection limits (ppb range) - particularly useful for turbinesCDisadvantagesCOff-site analysisCReagent shelf-life and shipping hazardsC“High” levels of NO can consume the sampling reagent2Test Methods - FTIRMethod 318 - Extractive FTIR Method for Measurement of Emissions from the Mineral Wool andWool Fiberglass Industries (http://www.epa.gov/ttn/emc/promgate/m-318.pdf)Method 320 - Vapor Phase Organic & Inorganic Emissions by Extractive FTIR(http://www.epa.gov/ttn/emc/promgate/m-320.pdf)40 CFR 63, Appendix AA gas sample is conveyed to an on-site Fourier Transform Infrared spectrometer.Formaldehyde emission levels are recorded by the instrument. Quality assurance samplesconsist of pre-test reference spectra, initial background spectra, and pre and post run spikeanalyses.CAdvantagesCQuite a bit of supporting data - used extensively in AP-42 data collectionCValidated for IC engines in July 1995CSpeciates most aldehydes (can provide acetaldehyde number), no cross-interferenceCReal-time, on-site, semi-continuous emissions dataCDisadvantagesCCost - Consider a hypothetical 2 engine CO/NO /HCHO test in Gillette, WYXCApproximately $26,000 with FTIR, $11,000 with CTM-037CIncreased cost driven by expensive equipment and additional test timeC0.5 ppm detection limit - too high for turbinesTest Methods - Colorimetric (Acetyl Acetone)Conditional Test Method 37 (CTM-037): Method for Measurement of Formaldehyde EmissionsFrom Natural Gas-Fired Stationary Sources - Acetyl Acetone Derivitization Method(http://www.epa.gov/ttn/emc/ctm/ctm-037.pdf)Found on the EPA Technology Transfer Network (TTN) Emission Measurement Center (EMC)websitePromulgation as a 300-series test method is expectedA gas sample is extracted at a constant flow rate, pulled through a stainless steel probe,through two midget impingers seeded with water, and through a calibrated dry gas meter.The impinger contents and a series of water rinses of the sampling hardware are recovered,reacted with acetyl acetone, and analyzed colorimetrically on-site. Quality assurancesamples consist of a field duplicate, a field blank and a field spike.CAdvantagesCValidated against FTIR by GRI (4.7% RA) for IC engines in July 1995CNo problems with NO2COn-site resultsCDisadvantagesCCannot provide acetaldehyde values (in fact, acetaldehyde interferes)Test Methods - Colorimetric (Pararosaniline)Method 316 - Sample & Analysis for Formaldehyde emissions in the Mineral Wool & WoolFiberglass Industries (http://www.epa.gov/ttn/emc/promgate/m-316.pdf)Found on the EPA Technology Transfer Network (TTN) Emission Measurement Center (EMC)websiteA gas sample is extracted at an isokinetic flow rate, pulled through an in-stack stainless steelnozzle, through a heated glass probe, through a series of chilled impingers seeded withwater, and through a calibrated dry gas meter. The impinger contents and a series of waterrinses of the nozzle, probe and impingers are recovered, reacted with pararosaniline, andanalyzed colorimetrically on-site. A field blank is collected and analyzed with the emissionssamples for quality assurance.CAdvantagesCPurple color may be more “unique” (not generally observed in unreacted samples)CNo problems with NO2COn-site resultsCDisadvantagesCCannot provide acetaldehyde values (in fact, acetaldehyde interferes)CIsokinetic sampling train - requires better access to larger sampling portsConclusionsFormaldehyde - Is it worth worrying about?CFormaldehyde from lean burn reciprocating engines is realC10 tons per year will trigger at or near 5,000 horsepower without controlsCoxidation catalysts should extend this to around 40,000 horsepowerCengine maintenance will only bring extraordinarily high engines down to reasonable levelsCFormaldehyde from rich burn reciprocating engines is realCNSCR will effectively reduce formaldehyde to very low levelsCEven without NSCR, 10 tons per year should trigger around 15,000 to 30,000 hpCFormaldehyde from turbines is very lowCA cost benefit analysis will probably not support oxidation catalysts for turbinesFormaldehyde - How should I measure it?CColorimetricCProvides on-site resultsCHas been proven accurate against FTIRCPerformed quickly with relatively inexpensive equipment (reducing total test costs)CFTIRCProvides real-time data for suitably high levels (above 0.5 ppm)CHas been validated for formaldehyde testing on reciprocating enginesCRequires more setup time per source than other technologiesCDNPHCReagent shipping and shelf life are problemsCQuestions exist as to the accuracy for lean burn sourcesCResults are off-site