what is the purpose of restriction orifice multi holes in fly ash air pneumatic conveying systems

[bboosstteerr]

Hi,

from this link one of the purposes is reduced a noise Link,
but what kind of noise? why its needed for inlet air conveying of fly ash from economizer hopper,

Thanks.

 

[LittleInch]

From the minimal amount of information you've chosen to provide it's not easy to say.

however my guess is that you have a high pressure air supply? which is needed to reduce in pressure?

If you have only one orifice plate with a small hole the air will or is at sonic velocity. That makes a LOT of noise at a high frequency.

Putting a number of plates in series means each one can operate at a velocity at the orifice of less than sonic hence lower noise.

If this is actually for the air with fly ash in it then I can only imagine that they want to keep the velocity down to reduce erosion.

give us a bit more to work on and we might have a different response...

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[bboosstteerr]

the air pressure supply is 7 Bar. the plates only placed at the inlet after the on-off valve. this air is used for conveying fly ash of 6 economizer hopper in series . thank you

 

[LittleInch]

7 bar to nearly atmospheric will be choked flow, i.e. at sonic velocity for a single orifice. You would hear that on the other side of the plant....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[bboosstteerr]

did a choked flow would be a problems for conveying ash to silo?

 

[LittleInch]

No, but just makes a lot of noise and probably erodes the orifice over time and hence your air flow rate would go up over time.

Also depends on the area ratio of orifice to duct as the sonic jet might take a little time to slow down.

Can you give us any more background to this?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Compositepro]

The restrictive orifices described in the linked article have nothing to do with pneumatic conveying. They are used to dissipate energy by turning it into heat and not sound while reducing pressure. Pneumatic conveyors use nozzles in eductors, ejectors, or venturis to convert pressure into kinetic energy in order to convey powders.

Is the question: Why are multiple nozzles used in some ejector pump designs rather than a single nozzle?