Emissions Calculations 101

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Emissions Calculations 101

• Tim Trumbull
• Iowa Air Emissions Assistance Program
• Iowa Waste Reduction Center
• University of Northern Iowa

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Estimating Emissions

• Developing emission control strategies
• Determining affects of sources and mitigation
  strategies
• Emissions Inventories
• Permit Applications

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Estimation Hierarchy
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Preferred Method of Estimating Emissions

• Continuous Emission Monitoring
• any monitoring effort that continuously
  measures ( I.e. very short averaging time) and
  records emissions
• Very expensive but most accurate

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Second Best Method of Estimating

• Stack Test Data
• Short term scientific tests to quantify an
  emission rate
• Results are applicable only to the conditions
  existing at the time of the test
• Reliable and somewhat expensive

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Third Method of Estimating Emissions

• Material Balance
• Reliable average emission rate
• For use when a high percentage of material is
  lost to the atmosphere
• May be inappropriate when a material is consumed
  or combined in a process
• Need to account for all materials going into and
  coming out of a process

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Fourth Method of Estimating Emissions

• Emission Factors
• Ratios that relate emissions of a pollutant to an
  activity level that can be easily measured .
• Given an emission factor, simple multiplication
  can yield an estimate of emissions
• Represent typical values for an industry, not
  necessarily representative of a specific source

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Fifth Method of Estimating Emissions

• Engineering Estimates
• Term applied to the best approximation that can
  be made when stack testing, material balance, or
  emission factors are not available.
• Usually made by an engineer familiar with a
  specific process, and is based on process
  information

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Material Balance

• Commonly used for surface coating operations
• Required Process rates, material used, material
  properties (from MSDS), and knowledge of process
• Example Spray Paint Booth

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Material Balance

• Sample Exercise

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ACMEs Spray Paint Booth

• ACME Corp. applies a base coat and a top coat to
  each wagon it produces. The paint is sprayed
  directly from the container with no thinning or
  mixing. ACME has a federally enforceable paint
  usage limit of 2000 gallons per year. ACME
  sprayed 1,300 gallons last year (500 gallons of
  base coat and 800 gallons of topcoat). An HVLP
  spray gun with a maximum capacity of 7 gal./hr is
  used. The paint booths filters have a 95
  percent particulate removal efficiency.

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MSDS Information
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Step 1- Determine paint usage

• Since ACME has a usage limit of 2,000 gal/yr,this
  is the maximum amount of paint that they can use.
• If this limit was not in place potential usage
  would be calculated as follows
• Gun capacity x hours/yr gallons / year
• 7.0 gal/hour x 8760 hr/yr 61,320 gal./yr.

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Step 2- Calculate Potential VOC and HAP emissions

• Use the highest constituent amount of VOC and
  HAPs from the base or top coat to calculate
  potential emissions.
• First, determine which paint has the highest
  amount of VOC.
• Base7.21lb/gal x .42 3.02 lb/gal
• Top 8.75 x .25 2.01 lb/gal

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Step 2- Calculate Potential VOC and HAP emissions
(cont)

• Density (lb/gal) x Usage Limit (gal/yr) x Max.
  VOC x ton/2000 lb
• (7.21 lb/gal) x (2000 gal/yr) x 0.42 VOC x (1 ton
  / 2000 lbs)
• 
  3.02 Tons / year VOC
• Use the same formula for each HAP but replace VOC
  with the highest specific HAP from the two
  coatings
• Xylene 8.75 lb/gal x 2000 gal/yr x 0.08 x
  ton/2000 lb 0.7 tons/yr
• Toluene 8.75 lb/gal x 2000 gal/yr x 0.15 x
  ton/2000 lb 1.31 tons/yr
• MEK 8.75 lb/gal x 2000 gal/yr x 0.02 x ton/2000
  lb 0.18 tons/yr

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Step 3 Calculate Potential PM-10 Emissions

• To calculate PM-10 emissions the spray transfer
  efficiency (TE) of the spray gun and the control
  efficiency (CE) of the filter must be inserted
  into our earlier formula for VOC.
• Transfer Efficiency is the percentage of paint
  from the gun that adheres to the part being
  painted.

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Step 3 Potential PM-10 Emissions (Sample
Transfer Efficiencies)
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Step 3 Calculate Potential PM-10 Emissions
(cont)

• The HVLP gun has a transfer efficiency of 65
• The filter control efficiency (CE) is 95
• In ACMEs process, 65 of the paint sprayed hits
  the part and 35 enters the exhaust stream.
• The filter captures 95 of the solids in the
  exhaust.
• The remaining 5 is discharged up the stack

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Step 3 Potential PM-10 Emissions (cont)

• Calculations
• Density (lb/gal) x Usage Limit x Max solids x
  (1-TE) x (1-CE) x ton / 2000 lbs.
• ton/yr PM-10
• 8.75 lb/gal x 2000 gal/yr x 0.75 x (1-.65) x
  (1-.95) x ton/2000 lbs 0.11 tons/yr PM-10

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Step 4- Calculate Maximum Hourly Emissions

• Multiply the capacity of the gun by the weight of
  the heaviest paint and by the highest percentage
  amount of each constituent.
• The paint density multiplied by the percent of
  the pollutant (by weight) equals a pound per
  gallon emission factor.
• To calculate hourly PM-10 emissions the transfer
  efficiency and collection efficiency must be
  included in the formula

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Step 4- Calculate Maximum Hourly Emissions (cont.)

• Gun Capacity (gal/hr) x Density (lb/gal) x Max.
  VOC/HAP VOC or HAP
• Gun Capacity (gal/hr) x Density (lb/gal) x Max
  PM-10 x (1-TE) x (1-CE) PM-10
• VOCs 7 gal/hr x (8.75 lb/gal x 0.42) 25.73
  lb/hr VOC
• Xylene 7 gal/hr x (8.75 lb/gal x 0.08) 4.9
  lb/hr Xylene
• Toluene 7 gal/hr x (8.75 lb/gal x 0.15) 9.19
  lb/hr Toluene
• MEK 7 gal/hr x (8.75 lb/gal x 0.02) 1.23 lb/hr
  MEK
• PM-10 7 gal/hr x (8.75 lb/gal x 0.75) x (1-.65) x
  (1-.95) 0.8 lb/hr PM

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Step 5- Calculate Actual Annual VOC and Toxic
Emissions

• Emissions from each coating must be calculated
  and added together.
• Paint used (gal/yr) x Paint Weight (lb/gal) x
  Pollutant x ton/2000 lbs. Actual Tons/
  year
• VOC-Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.25) 1,750 lb/yr x
  ton/2000 lb 0.875 TPY VOC
• VOC- Base Coat
• 500 gal/yr x (7.21 lb/gal x 0.42) 1,514 lb/yr x
  ton/2000 lb 0.75 TPY VOC
• 
  1.63
  TPY VOC

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Step 5- Calculate Actual Annual VOC and Toxic
Emissions

• Xylene -Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.08) 560 lb/yr x
  ton/2000 lb 0.28 TPY Xylene
• Xylene- Base Coat
• 500 gal/yr x (7.21 lb/gal x 0.02) 72.1 lb/yr x
  ton/2000 lb 0.04 TPY Xylene
• 
  0.32 TPY
  Xylene
• Toluene -Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.0) 0.0 lb/yr x
  ton/2000 lb 0.00 TPY Toluene
• Toluene- Base Coat
• 500 gal/yr x (7.21 lb/gal x 0.15) 540.75 lb/yr x
  ton/2000 lb 0.27 TPY Toluene
• 
  0.27 TPY
  Toluene

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Step 6- Calculating annual PM-10 Emissions

• Use the same formula with the incorporation of
  Transfer and Control Efficiencies
• Top Coat
• 800 gal/yr x (8.75 lb/gal x 0.75) x (1-.65) x
  (1-.95) 122.5 lb/yr x ton/2000 lb
  0.05 Tons/yr PM-10
• Base Coat
• 800 gal/yr x (7.21 lb/gal x 0.58) x (1-.65) x
  (1-.95) 63.09 lb/yr x ton/2000 lb
  0.02 Tons/yr PM-10
• 
  0.07 TPY PM-10

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Emission Factors
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Emission Factors

• An emission factor is a representative value that
  attempts to relate the quantity of a pollutant
  released to the atmosphere with an activity
  associated with the release of that pollutant.
• In most cases, EFs are an average of all
  available data of acceptable quality and are
  generally assumed to be long-term averages for
  all facilities in the source category.

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Emission Factors

• General Equation for Emission Estimation
• E A x EF x (1-ER/100)
• Where
• E emissions
• A activity rate
• EF emission factor
• ER overall emission reduction efficiency,
• further, ER is the efficiency of the control
  system

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Sources of Emission Factors

• AP-42- includes descriptions of activities that
  produce emissions
• FIRE- The Factor Information Retrieval Data
  System menu driven software
• Air CHIEF 9.0 CD-ROM- includes AP-42 and FIRE
• TANKS- estimates VOC HAP emissions from tanks
• CHIEF Bulletin Board System- includes latest
  guidance and information on air emission
  inventories and emission factors
• available at www.epa.gov/ttn/chief

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Other Sources of Emission Factors

• State Published Emission Factors
• Vendor Supplied Emission Factors

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Emission Factor Example

• ACME Company has a welding station that it uses
  to construct wagons.
• Process Gas Metal Arc Welding, E308 electrode
• Maximum Feed Rate 30 lb. electrode per hour
• Actual Throughput 40,000 lbs. Electrode per
  year

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Air CHIEF to find Emission Factors
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(No Transcript)
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ACMEs Welding Station

• SCC No. 30905212
• Emission Factors
• (HAPs from table 12.19-2)
• PM-10 5.4 lbs/1000 lb of electrode consumed
• Cr 0.524 lbs/1000 lb of electrode consumed
• Mn 0.346 lbs/1000 lb of electrode consumed
• Ni 0.184 lbs/1000 lb of electrode consumed

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Step 1- Calculate Annual Potential

• Make sure units of rate and emission factor
  match.
• 30 lb/hr x lb/1000 lb 0.03 1000 lb/hr
• 0.03 1000 lb/hr x 5.4 lb/1000 lb x 8760 hr/yr x
  ton/2000 lb
• 0.71 tons/yr PM-10
• Potential Chromium 0.07 tons/yr
• Potential Manganese 0.05 tons/yr
• Potential Nickel 0.02 tons/yr

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Step 2- Calculate Actual Emission

• Actual PM-10 in tons per year
• 40 1000 lb/yr x 5.4 lb/1000 lb x ton/2000 lb
  0.11 tons/yr
• Use the same formula for the other HAPs with
  their corresponding emission factors
• Actual Chromium 0.01 tons/yr
• Actual Manganese 0.01 tons/yr
• Actual Nickel 0.00

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Emission Factor Cautions

• Because emission factors are an average, 50
  percent of sources will have rates above or below
  the factor used
• Emission factors are neither emission limits nor
  standards
• If a factor for a pollutant is not available from
  EPA, this does not mean that the source does not
  emit a pollutant

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Questions?Contact Info

• Phone [phone]
• E-mail trumbull_at_uni.edu