Using a CO2 Meter To Determine Cracked Heat Exchangers

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Using a CO2 Meter To Determine Cracked Heat
Exchangers
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Heat Exchangers 2 3 years old
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Reasons for measuring CO2?

• By-product of combustion ( gt1ppm)
• Equipment warranty, cost and complexity
• Many existing commercially available meters
• Simple and direct process
• Portable instrumentation

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Propane Emissions1-AP -42 Compilation of Air
Pollutant Emission Factors Vol. 1 - Stationary
Sources USEPA, 5th ed. Section 1.5.

• CO2 12500 lb/1000 gallons
• NOx 14 lb/1000 gallons
• 1 ppm NOx 1 ppm TSNA
• Thereforegtgtgtgtgtgtgt
• CO2 893 ppm
• NOx 1 ppm

Crack
Typical Ambient CO2 Levels 300 450 ppm
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Effect of Fuel Source on TSNA

• Burner TSNA NOx
• Barn Type Configuration (ppm) (lbs) (kg)
• RD Electric Heat Exchange 0 n/a n/a
• RD LPG Direct-fired 2 0.4 0.18
• Commercial LPG Direct-fired 13 2.5 1.14

Flue-Cured Tobacco, 1998
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Direct Fired LP 5,400 9,000 ppm CO2 Pilot
Light Only 700 ppm CO2
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Direct Heat
Heat Exchanger
Heat Exchanger
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Barn Testing Procedure

• Barn must be empty
• Connect the CO2 meter to a 120 volt source and
  allow a 10 minute warm up period
• Close all air dampers to allow recirculation
• Place probe through front exhaust vent or viewing
  port on back wall into air stream

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Close all fresh air dampers
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Insert Probe in Curing Air stream after Heat
Exchanger
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Barn Testing Procedure

• Measure Ambient CO2 after 5-10 minutes
• Set thermostat 30-40oF above outside air
  temperature (maximum 140oF)
• Measure CO2 after 5-10 minutes

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CO2 Meter Results

• If ppm increases lt 100 No cracks
• If ppm 200-300 possible small leaks (check
  again later in season or next season)
• If ppm increase by a factor of 2 or more (gt900
  ppm) inspect closely for cracks and repair or
  replace heat exchanger and Notify Heat Exchanger
  Manufacturer

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Detecting Heat Exchanger Leaks

• Examine combustion chamber and all welds.
• Remove heat exchanger and examine closely
  (Bright flash light)

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Check all Exhaust Flue connections within Curing
chamber
Use high temperature sealant- 2,300oF to
repair?????
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Stack height should be 24 inches above the
highest point of roof line
Repair Flue Pipes
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CO2 Meters
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Direct-Fired Barn Levels
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Indirect-Fired Barn Levels
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Indirect-Fired Barn Levels (Fuel Oil)
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Indirect-Fired Barn Levels (105 oF)