High-Efficiency Cyclone Troubleshooting

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High-Efficiency Cyclone Troubleshooting

SYMPTOMS:

1. Collection Efficiency is lower than expected

Design basis is wrong

SOLUTION

  • Verify specified design conditions and vendor performance predictions are correct
  • If higher ΔP can be provided by the system air mover and the collection efficiency is close to the desired level, modify high-efficiency cyclone inlet and/or outlet to increase the velocity
  • Replace the high-efficiency cyclone with a better high-efficiency cyclone

Gas leakage into the cyclone

SOLUTION

  • Check and repair any leaks or holes.
  • Check to make sure flange connections are properly gasketted and tight
  • Check and repair feeder valves for proper operation and gas tightness.

Inlet or outlet ductwork is improperly designed

SOLUTION

  • Check and repair inlet and/or outlet ductwork if any flow disturbance is induced into the high-efficiency cyclone

There is an internal obstruction

SOLUTION

  • Insure that any access doors are flush and smooth
  • Insure that there are no instruments or probes sticking into the high-efficiency cyclone flow stream
  • If the high-efficiency cyclone is lined, check for and repair any major erosion that causes sharp edge disturbance to the flow stream
  • If plugging is occurring see item below

2. Plugging

Feeder valve is sized improperly for the particulate loading and density

SOLUTION

  • Resize and replace the feeder valve

Cyclone discharge diameter or dipleg is too small for the particulate loading and apparent density

SOLUTION

  • Redesign and replace lower sections

Dipleg plugs

SOLUTION

  • Add dipleg purges if problem is caused by poor aeration (although the introduction of purge gas itself can reduce collection efficiency this is preferable to 0% collection resulting from a plug).
  • Check and repair dipleg discharge valve

Particulate build up on surfaces

SOLUTION

  • If caused by condensation, insulate and/or heat trace
  • Consider non stick coatings or polished surfaces
  • Periodic vibration and/or air cannon
  • Replace with a cyclone with greater internal clearances
  • Provide easy access for cleaning and maintenance

3. Erosion

Cyclone inlet velocity is too high

SOLUTION

  • Replace the high-efficiency cyclone or modify the inlet so that the inlet velocity is as low as possible (just above the saltation velocity at the minimum flow condition)
  • Reduce the gas flow rate if possible

Particulate is abrasive

SOLUTION

  • Use the lowest possible inlet velocity
  • Make the high-efficiency cyclone out of more abrasion resistant construction. If a combination of corrosion is occurring with erosion then the materials of construction must first be corrosion resistant since virtually all materials will abrade away rapidly when in an oxidized state
  • Use high-efficiency cyclones that have larger diameters
  • Design the installation and high-efficiency cyclone itself so that worn parts can be replaced and/or repaired as economically as possible

4. ΔP is too high

Design basis is wrong

SOLUTION

  • Verify specified design conditions and vendor performance predictions are correct
  • If the high ΔP is not causing any real problem, leave it alone. The high-efficiency cyclone should be providing higher collection efficiency than specified
  • Modify air moving portion of the system to accommodate higher ΔP
  • Enlarge the high-efficiency cyclone inlet or outlet pipe to reduce velocity (note this will reduce the high-efficiency cyclone collection efficiency)
  • Replace the high-efficiency cyclone

Excess air leaking into upstream ductwork

SOLUTION

  • Repair ductwork

5. ΔP is too low

Design basis is wrong

SOLUTION

  • Verify specified design conditions and vendor performance predictions are correct
  • If the low ΔP is not causing any real problem, leave it alone.
  • If the high-efficiency cyclone efficiency is too low by a small margin, modify the inlet and/or outlet to increase velocity
  • Increase the gas flow rate to the high-efficiency cyclone

Leaks into the cyclone

SOLUTION

  • Repair

Internal obstruction

SOLUTION

  • Inspect and clear or repair

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