8 replies to this topic

[CHEMSTRONG]

I want to know reasons for compressor efficiency loss and various factors responsible for this?

 

Regards,

CHEMSTROng

[SilverShaded]

I want to know reasons for compressor efficiency loss and various factors responsible for this?

 

Regards,

CHEMSTROng

Fouling

[CHEMSTRONG]

yes, that is the main reason but every time, efficiency loss is not due to fouling right ? it can be due to change in turbine speed or feed rate also ?

 any other factors ?

 I am talking about Polytropic efficiency here

[PingPong]

I want to know reasons for compressor efficiency loss and various factors responsible for this?

 

Regards,

CHEMSTROng

Efficiency loss is caused by friction.

 

That's why a centrifugal compressor has a lower efficiency than a reciprocating or screw compressor.

 

The rotating impeller of a centrifugal creates a lot of friction between impeller and gas and therefor part of the work is converted into additional heating of the gas (on top of the heating due to compression alone).
 

[CHEMSTRONG]

Respected Sir,

 

How then increased fouling in compressor increases friction ?

How to evaluate efficiency loss due to fouling as we will have actual compressor efficiency . dow e need to compare this efficiency with design efficiency ?

[SilverShaded]

yes, that is the main reason but every time, efficiency loss is not due to fouling right ? it can be due to change in turbine speed or feed rate also ?

 any other factors ?

 I am talking about Polytropic efficiency here

Yes there is a performance curve associated with every compressor, the manufacturer will supply that and it's typically found by testing.

[SilverShaded]

Respected Sir,

 

How then increased fouling in compressor increases friction ?

How to evaluate efficiency loss due to fouling as we will have actual compressor efficiency . dow e need to compare this efficiency with design efficiency ?

Fouling make the blades rougher and hence more friction.

[breizh]

Hi,

You may find hints in the PPT presentation , link attached.

http://oaktrust.libr....pdf?sequence=1

 

Good luck

Breizh

[PingPong]

Dear Sir,

 

I wanted to know , for a centrifugal compressor without any fouling issue in it, if its Polytropic Efficiency can be around 100 percent or more ? Flow is around 100 MTPH, Discharge temp range is 80 -88 Deg C and pressure ratio is 2 only.

 

Thanks.

 

CHEMSTRONG

I took this related question from another topic by CHEMSTRONG, which I hope he will delete now.

 

Answer: No.

Efficiency of a centrifugal compressor is always well below 100 % due to the rotating impeller creating a lot of friction between impeller and gas, even if the impeller is brand new and perfectly clean.

Fouling, or corrosion, make the impeller surface rough and thereby further lower the efficiency.

 

Efficiency depends very much on volumetric flowrate. A centrifugal compressor with high volumetric design flowrate has higher efficiency than one designed for lower volumetric flowrate.