Criteria Air Contaminants

1
Criteria Air Contaminants
2
Introduction

• Criteria air contaminants
• Air emissions only for
• NPRI (beginning with 2002 reporting year)
• OMOE Reg.127 reporting
• most CACs have been on NERM list since its
  inception
• in 2003 this was modified from releases to all
  media to air releases only

- CO - Particulate matter - VOC was covered
earlier
- NOx - SO2
3
Key Issues

• Reporting Thresholds
• NERM/NPRI, OMOE Reg. 127, Alberta
• Reported Species
• NOX, SO2, Particulate
• Major Stack Criteria
• Reporting of stack parameters required for NPRI
  if stacks ? 50m and emissions meet reporting
  thresholds

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General Quantification Methods

• CAC emissions can be estimated using the general
  methodologies described earlier
• direct measurement (CEMs, PEMs, stack testing)
• emission factors
• mass balance
• stoichiometry (fuel usage)

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NOX - origins and effects

• includes NO, NO2 (but not N2O)
• main source is combustion
• N O2 NOX
• the N comes from
• nitrogen in air (thermal NOx)
• nitrogen in fuel (fuel NOx)
• Effects
• precursor to ground level ozone
• precursor to secondary fine particulate nitrates
• acid rain

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Emission Sources - NOX

• Fuel Combustion Sources
• natural gas / fuel oil / wood residue / other
  fuel combustion
• stationary external combustion sources - boilers,
  heaters, furnaces
• stationary internal combustion sources -
  turbines, reciprocating engines, industrial
  engines
• industrial flares

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Reporting Thresholds - NOX

• NERM/NPRI
• 20 tonnes/y (expressed as NO2)
• 5 tonnes/y (as NO2) is criteria for reporting
  stack parameters for stacks ? 50m
• OMOE Reg. 127
• 14 tonnes/y (as NO)

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Emissions Quantification - NOX

• Example
• A chemical facility has a 35 GJ/h boiler which
  burns natural gas. In September of the reporting
  year, the boiler was retrofitted with low-NOX
  burner technology. The facility does not have
  CEM or stack test data for the boiler. Natural
  gas consumption is metered, and data is available
  from gas bills.

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Combustion Emissions - NOX (Contd)
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Combustion Emissions - NOX (Contd)

• Boiler capacity
• 35 GJ/h 33 MMBtu/h
• NOX emission factors AP-42 for boilers lt 100
  MMBtu/h
• Uncontrolled 100 lb/106 scf
• Controlled with low NOX burners 50 lb/106 scf
• Natural gas consumption, from gas bills
• Prior to burner retrofit
• Jan - Sep 325.2 x 106 MJ 8.425 x 106 m3
  2.98 x 108 ft3
• After retrofit with low-NOx burners
• Oct - Dec 91.8 x 106 MJ 2.378 x 106 m3
  8.4 x 107 ft3
• converted using a natural gas heating
  value of 38.6 MJ/m3

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Combustion Emissions - NOX (Contd)

• Total NOX emissions
• Uncontrolled
• 2.98 x 108 ft3 x 100 lb/106 scf
• 29,752 lbs 13.5 tonnes
• Controlled (with low-NOx burners)
• 8.4 x 107 ft3 x 50 lb/106 scf
• 4,199 lbs 1.9 tonnes
• Total NOX emitted
• 13.5 tonnes 1.9 tonnes
• 15.4 tonnes (as NO2)

Note in Ontario, this would be reported as 10.0
tonnes NO
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CO - origins and effects

• typically from incomplete combustion of fuels
• effects
• colourless, odourless, poisonous gas
• can impair perception and judgement
• to a minor extent participatesin smog formation

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Emission Sources - CO

• Fuel Combustion Sources
• natural gas / fuel oil / wood residue / other
  fuel combustion
• stationary external combustion sources - boilers,
  heaters, furnaces
• stationary internal combustion sources -
  turbines, reciprocating engines, industrial
  engines
• industrial flares

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Reporting Thresholds - CO

• NERM/NPRI
• 20 tonnes/y
• 5 tonnes/y is criteria for reporting stack
  parameters for stacks ? 50m
• OMOE Reg. 127
• 20 tonnes/y

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Emissions Quantification - CO

• Example
• A chemical facility has a 35 GJ/h boiler which
  burns natural gas. In September of the reporting
  year, the boiler was retrofitted with low-NOX
  burner technology. The facility has a CEM which
  monitors flow rate and CO concentration from the
  boiler.

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CEM data for CO Emissions
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Combustion Emissions - CO

• CEMS data (sample data point)
• flow rate 310 dscm/min (dry, standard cubic
  metres per minute)
• CO concentration 20.2 ppmv, parts per million
  by volume, dry basis
• calculate hourly emission rate
• 20.2 m3 CO X 310 m3 flue gas X 60 min
  0.376 m3 CO
• 106 m3 flue gas min hr hr
• volume occupied by 1 mole of gas at standard
  conditions 24.45 L
• 0.376 m3 CO X g-mole CO X 1000 L X 28 g
  430 g/hr
• hr 24.45 L m3 g-mole CO
• 0.43 kg/hr

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Combustion Emissions - CO (contd)

• Depending on variability in data, CEM data can be
  used to calculate annual CO emissions based on
  monitored data, e.g.
• can convert from average hourly readings to
  annual mass emissions
• can calculate emissions on a monthly, weekly,
  daily, hourly or even per minute basis and sum up
  to annual emissions

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Combustion Emissions - CO (Contd)

• Emission Factor Calculation
• Boiler capacity
• 35 GJ/h 33 MMBtu/h
• CO emission factors AP-42 for boilers lt 100
  MMBtu/h
• 84 lb/106 scf (retrofit of NOx control does
  not affect CO factor)
• Natural gas consumption
• Jan - Sep 325.2 x 106 MJ 8.425 x 106 m3
  2.98 x 108 ft3
• Oct - Dec 91.8 x 106 MJ 2.378 x 106 m3
  8.4 x 107 ft3
• Natural gas heating value of 38.6 MJ/m3

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Combustion Emissions - CO (Contd)

• Total CO emissions
• (2.98 x 108 8.4 x 107) ft3 x 84 lb/106 scf
• 32,047 lbs
• 14.5 tonnes
• for 8760 hours per year, this 1.65 kg/hr
• compare this to CEM-based estimate of 0.43 kg/hr

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Particulate Matter (PM) - Origins and Effects

• primary PM - emitted directly into the atmosphere
• combustibles, fuels vehicle exhaust open
  burning industrial processes storage piles
  paint overspray etc.
• secondary PM - formed in the atmosphere from
  reactions or transformations of precursors
• effects
• smog
• visibility (PM10 and PM2.5)
• respiratory health

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Emission Sources - PM

• external fuel combustion sources
• boilers
• heaters
• incinerators
• flares
• fugitive dust
• process operations
• wind erosion of exposed storage piles
• bulk materials transfer
• road dust is included under OMOE Reg. 127

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PM Species

• Fine particulate PM2.5
• Particulate matter under 2.5?m
• Inhalable particulate PM10
• Particulate matter under 10?m
• Total particulate PM
• Particulate matter under 100?m

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PM sampling

• Filterable fraction
• Particles trapped by the heated glass fibre
  filter in the front half of a US EPA Method 5
  sampling train
• Condensible fraction
• Material that passes through the filter but is
  condensed in a series of impingers immersed in an
  ice bath in the back half of the sampling train

• only filterable PM is reportable to NPRI

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Comparison of PM Reporting Thresholds
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Combustion Emissions - PM

• Example
• For the same natural gas-fired 35 GJ/h boiler
  at the same chemical plant, an annual source test
  for particulate matter is required under the
  conditions of the air discharge permit issued by
  the local regulatory authority.

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Combustion Emissions - PM (Contd)
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Combustion Emissions - PM (Contd)

• Total PM emissions
• Boiler operating hours
• 5,760 hours/y
• Average PM emission rate from stack tests
• 0.047 kg/hour
• Total annual PM emissions
• 0.047 kg/h x 5,760 h/y
• 271 kg
• 0.271 tonne

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Combustion Emissions - PM10 and PM2.5

• No size speciation profile available for natural
  gas-fired boiler in U.S. EPA SPECIATE
• AP-42 Table 1.4-2 indicates that all PM is
  assumed to be less than 1.0 micrometer in
  diameter. ThereforePM emission factors may be
  used to represent PM10, PM2.5 or PM1 emissions
• i.e., 0.271 tonnes/year PM PM10 PM2.5
• improvement option - use particulate size
  information if available from source testing data

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Fugitive Dust Emissions - PM

• Methodologies
• US EPA correlations and emission factors
• CCPA Source Characterization Guidelines for
  Primary Particulate Matter (March 2001)

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PM Emissions from Cooling Towers

• Draft guidance from NPRI
• should be included in the NPRI 2003 Tool Box on
  the web
• based on US EPA AP-42 Section 13.4
• PM10 (kg/h) Total Liquid Drift (L/L) x
• TSS (kg/L) x throughput (L/min) x 60
  min/hr
• assumptions
• concentration of total suspended solids (TSS) in
  water being cooled is the same as in water
  droplets carried out as liquid drift
• TSS are comprised of PM10 and remain as PM10 once
  water evaporates

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PM Emissions from Cooling Towers (contd)

• U.S. EPA considers this method to give a
  conservatively high PM-10 emission factor
• EPA gives some sample values for liquid drift
• induced draft 0.02 of circulating water flow
• natural draft 0.00088 of circulating water flow
• these factors are rated D and E
• could improve with
• site specific information on use of drift
  eliminators
• data from manufacturer on liquid drift

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SO2 - Origins and Effects

• Combustibles and fuels that contain sulphur
• Combustion S O2 SO2
  SO2 1/2O2 SO3
  SO2 O2 SO42-
• the majority of SOx is SO2 (as much as 98)
• Effects
• precursor to secondary fine
• particulate sulphates
• acid rain sulphuric acid (H2SO4)

SOx
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Emission Sources - SO2

• combustion of S-containing fuels in external and
  internal combustion sources
• natural gas may contain mercaptan to permit
  detection of leaks
• light and heavy fuel oils can contain significant
  amounts of sulphur
• flare emissions
• process releases

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Reporting Thresholds - SO2

• NERM/NPRI - requires reporting of SO2 only
• 20 tonnes/y (as SO2)
• 5 tonnes/y (as SO2) is criteria for reporting
  stack parameters
• OMOE Reg. 127 - requires reporting of SO2 only
• 20 tonnes/y (as SO2)

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Emissions Quantification - SO2

• Example
• The same chemical facility has a second boiler
  with rated capacity of 19 MMBtu/h, which burns
  natural gas and No.2 distillate oil. The boiler
  exhaust is controlled by a wet scrubber which
  testing has shown provides a SOX removal
  efficiency of 80 (by weight).

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Combustion Emissions - SO2 (Contd)

• Boiler fuel consumption
• Natural Gas 3,449,000 m3/y
• with sulphur content of 10 mg/m3
• No. 2 distillate oil 679.4 tonnes/y
• with sulphur content of 0.5 wt

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Combustion Emissions - SO2 (Contd)

• Total S in fuels
• Natural Gas 3,449,000 m3 x 10 mg/m3 34.9 kg
• Distillate 679,400 kg x 0.5 3,397 kg
• Total S 34.9 3,397 3,431.5 kg
• Pre-controlled SO2 emissions
• 3,431.5 kg S x (64/32) molecular weight of
  SO2/S
• 6,863 kg SO2
• 6.9 tonnes
• Post- controlled SO2 emissions
• 6,863 kg SO2 x (100 - 80)
• 1,372.6 kg
• 1.4 tonnes

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Flare Emissions - SO2

• Dispose of S-containing materials e.g. H2S,
  mercaptans
• Assume nominal amount of S in flared gas that is
  representative of facility
• Consider efficiency of flare gas recovery system
  if installed
• For upsets or shutdowns/startups, use operation
  records to determine flared gas quantity and S
  content

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H2SO4 Emissions

• NPRI reportable substance but not a CAC
• Formed in stack during combustion of S-containing
  fuels, where moisture is present
• Reporting threshold of 10 tonnes/y
• Estimation Methods
• ExxonMobil and US EPA

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Guidance Documents / Sources of Information

• NPRI - Supplementary Guide for Reporting CACs
• CCPA
• Guideline for Quantifying Emissions from Chemical
  Facilities, Section 14 - CACs
• Source Characterization Guidelines - Primary
  Particulate Matter and Particulate Precursor
  Emission Estimation Methodologies for Chemical
  Production Facilities

• Ontario MOE - Step by Step Guidelines for
  Calculation, Record Keeping and Reporting for
  Airborne Contaminant Discharges

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Guidance Documents / Sources of Information
(contd)

• U.S. EPA
• AP-42 Compilation of Air Pollutant Emission
  Factors
• FIRE - Factor Information Retrieval System
• SPECIATE - repository of Total Organic Compound
  (TOC) and Particulate Matter (PM) speciated
  profiles for a variety of sources
• PM Calculator
• Australia, National Pollutant Inventory
• Emission Estimation Technique Manuals
• Combustion in Boilers, Chemical Product
  Manufacture, Inorganic Chemicals Manufacturing,
  Organic Chemical Processing Industries