Improving cyclone efficiancy by recycling the exhaust

[Bill Dufour]

I was looking for something else and found many articles, well above my head. They show that by recycling some of the dirty? exhaust air back into the cyclone you can improve the efficiency of the cyclone. I am not sure if they mean the electrical efficiency or dust removal efficiency or both. I would say it would allow a smaller blower for equal airflow into the cyclone but you would be inducing dust into the fan and causing more fan wear.
I have read of folks adding a blower into a air compressor to increase output measurably. If you can add 2psi to 14.7 PSi air I could see a significant increase. We are not talking crazy pressures like a turbo charger would use.
Bill D

https://onlinelibrary.wiley.com/doi/abs/10.1002/ceat.200600085

[Brice Rogers]

Bill, I think that they are talking about filtering out or removing a higher percentage of particles rather than drawing less power.

I have a 2 HP dust collector with Thien baffle. It works well enough. I also have an older 1 HP DC and a spare cyclone. I've contemplated connecting them in series. That is, dust would go into the cyclone and then through the 1 HP DC and then into the Thien baffle and then through the 2 HP collector and then vented outside.

But I've read that DCs draw less current when the blast gates are closed and more when there is less back pressure. So, I'm wondering if running two in series might damage one or perhaps both DCs.

Bill, you raised an interesting idea. Thanks. I am looking forward to reading the replies of others as well as any more info you may post.

[Ronald Blue]

I suppose if you can make the plumbing work it's possible. Something like a turbocharger on the engine. Except there the exhaust heat drives the turbo and provided the boost. You can use a regen circuit in hydraulics. We pressurize hydraulic tanks to about 3 psi to help prevent pump cavitation. It would be interesting to know if the velocity can be increased by looping some of the discharge air back into the suction side. I wonder if the cyclone is designed for an ideal air volume and if it's increased to much the solids won't drop out properly. Food for thought.

[Ron Selzer]

"I wonder if the cyclone is designed for an ideal air volume and if it's increased to much the solids won't drop out properly. Food for thought"

Have the larger metal cyclone sold on ebay out of New York, as the airflow increased due to different modifications to the system the solids dropped out better to the point it was packed firm in the dust collection bin. Not happy overall with the cyclone and it is in the process of being replaced. Have to go to work now, will expand on this some more tonight or over the weekend.
Ron

[David L Morse]

It increases the collection efficiency, i.e., it decreases cut size.

The electrical efficiency decreases because the cyclone has to handle more air - both the desired throughput and the recycled part. You need a bigger cyclone and a bigger blower.

The principle applies to any separation process, not just cyclones.