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 Data
Physical Properties

C Gas at room temperature (boiling point = -19.5 C)C Vapor density = 1.07 (air = 1)C Very water solubleC Generally purchased in solution 

37% formaldehyde, 10% - 15% methanol, 48% - 53% waterFormaldehyde in this solution is hydrated as H C(OH) 2 2

Exposure Limits 

(from Material Safety Data Sheet Effective 9/14/00)C OSHA

0.75 ppm (TWA)2 ppm (STEL)0.5 ppm (TWA action level)

C ACGIH

0.3 ppm (TLV)

Health Effects

C Respiratory tract irritant, severe at high levels (25 - 30 ppm) - possibly fatalC Severe skin irritant - redness, pain, possible burnsC Chronic inhalation is a suspected (probable) carcinogen

Formaldehyde Sources
Industrial Uses

C Domestic use estimated at 1.4 million tons annually

C The glue or adhesive in pressed wood products (particle board, hardw

medium density fiberboard)

C Preservatives in some paints, coatings and cosmeticsC Durable press fabrics, draperies, and coated paper productsC Insulation materials (urea-formaldehyde foam and fiberglass insulation

Naturally Occurring

C One of 27 compounds identified in the interstellar space of the Milky Way

C Present in human breath
Product of Incomplete Combustion

Complete methane combustion:

CH + 2O 42 22 Y CO + 2H O

C Final state of carbon atom is O=C=O (carbon dioxide)C Oxidation proceeds in stepsC Formaldehyde is formed as a normal intermediate which is typically consum

stages of combustion

CH Y H C=O (formaldehyde) Y C=O (carbon monoxide) Y O=C=O (carbon d

4 2

However, the completion can be retarded by:

C combustion quenching from cooler temperatures (close to walls of the combC rich and lean sections from poor fuel mixing

Formaldehyde measurements during the combustion process are much higher (5 than exhaust measurements.
Formaldehyde Control

Maintenance has been shown to reduce formaldehyde emissions

Engine ID As Found HCHO Maintenance Activities 

(gm/hp-hr) 

Clark HRA-8 0.38 Plugs, head gasket, fuel valve packing, cam/ignition timing, 

#23 exhaust port carbon deposit removal

Clark HRA-8 0.33 Plugs, fuel valves, air starting valves, ignition timing, 

#24 intake/exhaust port carbon deposit removal

Clark HBAT-8 0.71 fuel valves, head gasket, air valve gaskets, fuel leaks, 

#25 intake/exhaust port carbon deposit removal, ignition timing,

cleaned mineral deposits in aftercooler

Catalytic oxidation systems might control formaldehyde emissions

Catalyst Type Unit NO Control CO Control TH

X

NSCR 4SRB 90% - 99% 90% - 98% 

Oxidation Catalyst 4SLB -- >90% 

2SLB -- 70% - 90+% 

Turbine -- 98% 

SCR LB (constant load) 77% - 90% -- 
Formaldehyde Regulatory Issues

Hazardous Air Pollutant

C 180+ Compounds, regulated as “HAPs”

C Aromatics (BTEX, etc.)C Halogenated (chlorobenzene, 1,2-dibromo-3-chloropropane, etc.)C Heavy metals (Hg, Pb, etc.)C Aldehydes (formaldehyde, acetaldehyde, acrolein, etc.)

C Regulated by over-all mass emission rate approach (vs. “potential to harm”)

C 10 tpy any one HAP or 25 tpy any combination = major sourceC Formaldehyde is only likely compound for the 10 tpy, and the 10 tpy w

triggered before the 25 tpy with all other HAPs

C “Potential to Harm” is probably negligible

C Alleged atmospheric fate is photochemical reaction with <1 day half-lifC Human exposure from combustion sources is believed to be small

MACT Concern for Natural Gas Combustion

C 3-Way (NSCR) catalyst for rich-burn will be MACT floor (required for major s

C Based on cleanest 12% of units

C MACT floor is “no control” for lean-burn

C Catalyst requirement would include a cost/benefit analysis 
AP-42 Emission Factors - Reciprocating Engines

Formaldehyde

Emission Assumptions Calc

Type Technique # of Factor RSD BSFC O 

2

tests lb/MMBtu % Btu/bhp-hr %vd ppm gm/

2SLB FTIR 58 5.52E-02 46.3 8,000 8.0 34.3 0

2SLB DNPH 8 4.06E-02 73.7 8,000 8.0 25.2 04SLB FTIR 32 5.28E-02 31.7 8,000 8.0 32.8 04SLB DNPH 5 1.38E-02 63.7 8,000 8.0 8.6 0

4SRB All 18 2.05E-02 87.5 8,000 0.0 20.6 0

Acetaldehyde

Emission Assumptions Calc

Type Technique # of Factor RSD BSFC O 

2

tests lb/MMBtu % Btu/bhp-hr %vd ppm gm/

2SLB FTIR 58 7.76E-03 74.6 8,000 8.0 4.8 0

2SLB DNPH 4 5.22E-03 34.6 8,000 8.0 3.2 04SLB FTIR 31 8.36E-03 72.9 8,000 8.0 5.2 04SLB DNPH 1 8.56E-04 -- 8,000 8.0 0.5 0

4SRB All 9 2.79E-03 84.5 8,000 0.0 2.8 0

Note: Underlined values are the factors provided in AP-42, 5 Edition, Volume I, Final Section th
AP-42 Emission Factors - Turbines

Formaldehyde

Emission Assumptions Ca

Fuel Load Control # of Factor RSD BSFC O 

2

tests lb/MMBtu % Btu/bhp- %vd ppm gm

hr

Gas All none 33 3.12E-03 204.0 10,000 14.0 1.52 Gas All CO Cat 2 3.60E-04 133.5 10,000 14.0 0.17 Gas >80% none 22 7.09E-04 206.1 10,000 14.0 0.34 

Gas >80% CO Cat 2 3.60E-04 133.5 10,000 14.0 0.17 Gas <80% none 11 7.94E-03 unk * 10,000 14.0 3.86 

Oil All none 10 2.45E-04 120.6 10,000 14.0 0.11 Oil >80% none 8 2.82E-04 115.0 10,000 14.0 0.13 

* - calculated from "All" and ">80%"

Acetaldehyde

Emission Assumptions Ca

Fuel Load Control # of Factor RSD BSFC O 

2

tests lb/MMBtu % Btu/bhp- %vd ppm gm

hr

Gas All none 9 4.45E-05 64.3 10,000 14.0 0.015 0Gas All CO Cat 2 1.76E-04 139.5 10,000 14.0 0.059 0Gas >80% none 8 4.02E-05 68.0 10,000 14.0 0.013 0

Gas >80% CO Cat 2 1.76E-04 139.5 10,000 14.0 0.059 0

Oil All none 2 3.03E-05 36.9 10,000 14.0 0.010 0

Note: Underlined values are the factors provided in AP-42, 5 Edition, Volume I, Final Section th
AP-42 Emission Factors - Notes

Reciprocating EnginesC NO and CO emission factors are presented for high (90-105%) and low (<90%) lo

X

showed no clear load dependence and are not broken out by load.

C FTIR and DNPH factors are separated for LB engines (FTIR promulgated in Final 

C EPA claims negative bias in the DNPH data due to oxygen and nitrogen

C Acetaldehyde factors are about 1/7 of the formaldehyde factorsTurbinesC Generally low ppm, except the calculated low-load data set

C Almost 4 ppmC 11 measurements

C NO control had no observable impact on aldehyde emissions X

C Oxidation catalyst provided only about 50% formaldehyde control

C Section 3.1.4.3. of AP-42 Final Section claims 85%-90% control C GRI vendor survey indicates a wide range for turbine oxidation catalyst form

control, but generally the expected control is lower (significantly) than expec

C Generally poor data for predicting emissions

C Extremely large RSD (greater than 100%)C Acetaldehyde actually increases across with oxidation catalyst (indicating da

rather than acetaldehyde production)
APT Test Data - Reciprocating Engines and Turbines

Formaldehyde

Emission Assumptions Calc

Unit Control # of Factor RSD BSFC O 

2

tests lb/MMBtu % Btu/bhp-hr %vd ppm gm/

LB none 29 5.21E-02 66% 8,000 8.0 47.33 0LB ox cat 31 7.12E-03 66% 8,000 8.0 6.47 0

** Avg Lean Burn Ox Cat Control Efficiency 86.3%

RB none 3 1.01E-02 41% 8,000 0.0 14.87 0RB NSCR 2 1.57E-03 49% 8,000 0.0 2.31 0

** Avg Rich Burn NSCR Control Efficiency 84.5%

Turbine none 6 4.63E-03 177% 10,000 14.0 2.25 0

APT vs. AP-42C LB Reciprocating Engines

C APT: 0.0521 lb/MMBtuC AP-42 0.0543 lb/MMBtu (weighted average of 2S and 4S FTIR measurements)

C RB Reciprocating Engines

C APT: 0.0101 lb/MMBtuC AP-42: 0.0205 lb/MMBtu

C Turbines

C APT: 0.00463 lb/MMBtuC AP-42: 0.00312 lb/MMBtu (published value for all loads, uncontrolled)
Test Methods

Three measurement techniques

C Direct spectrophotometric measurement (FTIR)C Integrated sample collection, reaction, and chromatographic analysisC Integrated sample collection, reaction and colorimetric analysis

Sampling differences for the integrated sampling techniques

C Isokinetic or not?

C Expected exhaust gas temperatures would seem to eliminate the need 

sampling

C FTIR measurements will not be isokinetic (in fact, deliberately excludin

matter)

Work is ongoing to calculate formaldehyde emissions without direct measuremen

C Attempts to predict based on measurement of CO, NO or NMHC have gene

X

(See Characteristics of Formaldehyde Emissions from Natural Gas-FirInternal Combustion Engines in Gas Transmission, Volume III: EvaluaFormaldehyde Measurement Techniques)

C Attempts to calculate based on engine parameters show promise

(See Characteristics of Formaldehyde Emissions from Natural Gas-Fir

Reciprocating Internal Combustion Engines in Gas Transmission, VoluPredictive Model for Estimating Formaldehyde Emissions from 2-Strok
Test Methods - 2,4-Dinitrophenylhydrazine (DNPH) M

EPA 0011: Sampling for Selected Aldehyde and Ketone Emissions from Stationary (http://www.epa.gov/epaoswer/hazwaste/test/main.htm)

Test Methods for Evaluating Solid Waste, Physical/Chemical Methods

First published in 1980, periodically revised - currently on 3 Edition rdA gas sample is extracted isokinetically through an in-stack nozzle, through a heatthrough a series of impingers seeded with 2,4-DNPH absorbing solution, and throudry gas meter. Following sampling, the contents of the impingers along with a sermethylene chloride rinses of the nozzle, probe, impingers and connecting hardwarin an amber glass bottle for off-site analysis. Aldehydes and ketones in the solutio2,4-DNPH to form dinitrophenylhydrazone derivatives, which are extracted, solvenconcentrated, and analyzed using high performance liquid chromatography (HPLCassurance samples consist of a Field Blank, Field Spike, and (maybe) a Matrix SpC Advantages

C Vast amount of supporting dataC Speciates most aldehydes (can provide acetaldehyde number), no croC Low detection limits (ppb range) - particularly useful for turbines

C Disadvantages

C Off-site analysisC Reagent shelf-life and shipping hazardsC Isokinetic sampling train - requires better access to larger sampling poC “High” levels of NO can consume the sampling reagent 2
Test Methods - 2,4-Dinitrophenylhydrazine (DNPH) M

CARB 430: Determination of Formaldehyde and Acetaldehyde in Emissions from SSources (http://arbis.arb.ca.gov/testmeth/vol3/vol3.htm)

Stationary Source Test Methods, Volume 3, Methods for Determining Emissions o

Contaminants from Stationary Sources

A gas sample is extracted at a constant flow rate, pulled through a stainless through two midget impingers seeded with 2,4-DNPH, and through a calibrameter. The impinger contents and a series of water and 2,4-DNPH rinses of hardware are recovered for off-site HPLC analysis. Quality assurance sampthree field blanks and a matrix spike (split from one run).

C Advantages

C Quite a bit of supporting data - used extensively in AP-42 data collectioC Speciates most aldehydes (can provide acetaldehyde number), no croC Low detection limits (ppb range) - particularly useful for turbines

C Disadvantages

C Off-site analysisC Reagent shelf-life and shipping hazardsC “High” levels of NO can consume the sampling reagent 2
Test Methods - FTIR

Method 318 - Extractive FTIR Method for Measurement of Emissions from the MinWool 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 A

A gas sample is conveyed to an on-site Fourier Transform Infrared spectromFormaldehyde emission levels are recorded by the instrument. Quality assuconsist of pre-test reference spectra, initial background spectra, and pre and analyses. 

C Advantages

C Quite a bit of supporting data - used extensively in AP-42 data collectioC Validated for IC engines in July 1995C Speciates most aldehydes (can provide acetaldehyde number), no croC Real-time, on-site, semi-continuous emissions data

C Disadvantages

C Cost - Consider a hypothetical 2 engine CO/NO /HCHO test in Gillette

X

C Approximately $26,000 with FTIR, $11,000 with CTM-037C Increased cost driven by expensive equipment and additional tes

C 0.5 ppm detection limit - too high for turbines
Test Methods - Colorimetric (Acetyl Acetone)

Conditional Test Method 37 (CTM-037): Method for Measurement of Formaldehyde From 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 CwebsitePromulgation as a 300-series test method is expected

A gas sample is extracted at a constant flow rate, pulled through a stainless through two midget impingers seeded with water, and through a calibrated dThe impinger contents and a series of water rinses of the sampling hardware reacted with acetyl acetone, and analyzed colorimetrically on-site. Quality asamples consist of a field duplicate, a field blank and a field spike.

C Advantages

C Validated against FTIR by GRI (4.7% RA) for IC engines in July 1995C No problems with NO2

C On-site results

C Disadvantages

C Cannot provide acetaldehyde values (in fact, acetaldehyde interferes)
Test Methods - Colorimetric (Pararosaniline)

Method 316 - Sample & Analysis for Formaldehyde emissions in the Mineral Wool Fiberglass Industries (http://www.epa.gov/ttn/emc/promgate/m-316.pdf)

Found on the EPA Technology Transfer Network (TTN) Emission Measurement Cwebsite

A gas sample is extracted at an isokinetic flow rate, pulled through an in-stacnozzle, through a heated glass probe, through a series of chilled impingers swater, and through a calibrated dry gas meter. The impinger contents and a rinses of the nozzle, probe and impingers are recovered, reacted with pararoanalyzed colorimetrically on-site. A field blank is collected and analyzed with samples for quality assurance.

C Advantages

C Purple color may be more “unique” (not generally observed in unreacteC No problems with NO2

C On-site results

C Disadvantages

C Cannot provide acetaldehyde values (in fact, acetaldehyde interferes)C Isokinetic sampling train - requires better access to larger sampling po
Conclusions

Formaldehyde - Is it worth worrying about?C Formaldehyde from lean burn reciprocating engines is real

C 10 tons per year will trigger at or near 5,000 horsepower without controlsC oxidation catalysts should extend this to around 40,000 horsepowerC engine maintenance will only bring extraordinarily high engines down to reas

C Formaldehyde from rich burn reciprocating engines is real

C NSCR will effectively reduce formaldehyde to very low levelsC Even without NSCR, 10 tons per year should trigger around 15,000 to 30,00

C Formaldehyde from turbines is very low

C A cost benefit analysis will probably not support oxidation catalysts for turbin

Formaldehyde - How should I measure it?C Colorimetric

C Provides on-site resultsC Has been proven accurate against FTIRC Performed quickly with relatively inexpensive equipment (reducing total test 

C FTIR 

C Provides real-time data for suitably high levels (above 0.5 ppm)C Has been validated for formaldehyde testing on reciprocating enginesC Requires more setup time per source than other technologies

C DNPH

C Reagent shipping and shelf life are problemsC Questions exist as to the accuracy for lean burn sourcesC Results are off-site