High-Efficiency Cyclone Trouble Shooting

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High-Efficiency Cyclone Troubl...

High-Efficiency Cyclone Trouble Shooting

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