7 replies to this topic

[CHEMSTRONG]

Dear Sir,

 

For a centrifugal compressor, can we have compressor with liquid and gas mixture in it ( so Vapor fraction less than 1 ). I know Some screw compressor can be liquid filled , but for a centrifugal compressor in Ethylene plant will have liquid also?

 

CHEMSTRONG

Edited by CHEMSTRONG, 17 March 2022 - 11:29 AM.

[Art Montemayor]

A centrifugal compressor in an Ethylene plant should never have any liquid fed to it.

 

Compressors are designed to compress gases; pumps are designed to pump liquids.  Keep it that simple and you won't have any problems.

[CHEMSTRONG]

Dear Sir,

Thanks for your email.

There is CGC Compressor in ethylene in which we have water wash injection to avoid fouling. Plants generally inject water for this compressor near discharge nozzles.

Best Regards,
CHEMStrong

[breizh]

Hi

Refer to the instruction manual given by the manufacturer , good also to talk to the maintenance guy in charge of this equipment .

To get a meaningful reply , share with us a PID of the equipment .

Definitely good for you to read the operating manual and PLC sequences where all steps (compression , washing ,...) should be described .

Good luck

Breizh 

[CHEMSTRONG]

It is not about compressor wash sequence , this water is added externally to control discharge temp of compressor

[PaoloPemi]

you should be able to download this paper
"Centrifugal Compressors in Ethylene Plants" CEP February 2017

for additional details see for example "Challenges of Ethylene Process Compressor Trains: From Design to Start-Up and Operability" Abu Dhabi International Petroleum Exhibition & Conference 2019 , from abstract :

"The impact of fouling on ethylene plant equipment can be substantial. The high possibility of gas polymerization occurring in the cracked gas compressor can lead to efficiency loss and unplanned outages with associated lack of production. An advanced stage-by-stage water injection system coupled with fully removable nozzles during compressor operation and an efficiency monitoring and control system, will reduce operating cost and risk of production loss by providing operators with continuously updated equipment performance"

also you may find several threads discussing wet gas compression at cheresources forum :-)

[breizh]

Hi, 

The document mentioned above.

 

https://www.aiche.or...ep/20170228.pdf

 

As suggested talk to compressor manufacturer about the issue .

 

Breizh

[PingPong]

A CGC in an ethylene plant cracking liquid feeds usually has a valved connection on the inlet piping to each CGC stage (casing).

If deemed necessary these connections can be used to inject wash oil to remove some of the fouling accumulated inside the compressor.

That wash oil has to be mainly aromatic by nature to be able to remove polymeric fouling.

 

Wash oil could be injected intermittently in an amount of typically 1 to 3 volume % on gas flowrate,

or continuously in an amount of typically 0.1 to 0.3 volume % on gas flowrate.

 

Before doing this check with compressor vendor whether these amounts are allowable for that specific compressor,

and whether the wash oil type you intend to use will not damage the coating (if present) of the impeller.