CCV Flames and burners

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  1. Two types of flame
    • Pre-aerated
    • Post-aerated
  2. Visual features of a pre-aerated flame
    Sharp, stable, well defined, blue cone shape.
  3. Visual features of a post-aerated flame
    Floppy, unstable, elongated, luminous yellow.
  4. zones of a flame (pre-aerated)
    A-B burner head/port

    B-C unburnt gas

    C - flame front, this is where the combustion process begins.

    C-D the reaction zone. This is where the chemical reaction takes place.

    D - outer mantle. Is the hottest part of the flame.
  5. what are the 4 intermediary products that are formed during combustion but are not present in the POC when complete combustion occurs.
    • Alcohol,
    • Aldehydes,
    • Carbon,
    • Carbon Monoxide.
  6. Flame speed of a ng pre-aerated flame
    Typically 0.36m/s
  7. Flame speed of a propane pre-aerated flame
    0.46m/s
  8. what is light back and when does it occur
    • Gas/air speed too slow,
    • Flame front moves downwards into the mixing tube.
    • Reaches injector.
  9. What is lift off and when does it occur
    • Over-gassing,
    • gas/air speed greater than flame speed,
    • flame lifts from burner,
    • flame may extinguish if mix is outside flammability limits.
  10. What are the properties of a flame
    • Conducts a current:
    • - ionisation
    • - rectification.

    • Emits light energy:
    • - infra red (IR)
    • - ultra violet (UV)
  11. Causes of incomplete combustion:
    • Main cause is lack of oxygen to the burner.
    • - reduced primary and/or secondary air.
    • - inadequate ventilation
    • - enlarged injectors/excessive burner pressure
    • - vitiated air contaminated with other gases. Oxygen level below 18% accelerates CO production.

    • Flame Chilling
    • Flame Impingement
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CCV Flames and burners
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CCV Flames and burners
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