VFD on 600HP centrifugal Compressor

[Brian2903]

Hi all,

Is that possible to apply VFD on 600HP centrifugal air comrpessor? It is 460V and using inlet and bypass valves as the control.

Also, what would be the other methods to control and saving energy?

Thanks in advance.

 

[jraef]

It is a tricky operation. Modulating only the motor speed can lead to surging in the compressor. You need additional intellegence to modulate the valves (vanes) and speed in a coordinated manor. Many of the chiller manufacturers have packages such as that available, as well as a few after market vendors. It is very expensive to develop the control algorithm on your own. I worked for a company that did it (although I didn't work on that project directly), it took them 3 years of field testing (and a very understanding end user) to get it right. The energy savings benefits can be spectacular however, provided your ambient environment warrants it.

JRaef.com
Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[aolalde]

If you can afford the investment for a good VFD, it is very convenient for driving a motor-compressor. With no VFD, the motor starts and moves immediately to full speed, filling the air reservoir to the pressure set up and then the compressor is bypassed or stopped. With a VFD, the motor is allowed to start at a slower pace and then running the compressor at a lower RPM, as it maintains a constant air pressure, with no spikes. This slower startup extends the lives of the motor, bearings, gears, belts, etc, and could result in improved overall efficiency.
To avoid risks of premature motor failure, verify that the original manufacturer considers it “VFD Duty Type”.

 

[jraef]

D'oh! I didn't see it was an AIR compressor, I was thinking of a centrifugal chiller compressor. Never mind my other comments.

The only thing I'll add about air compressor retrofits is to watch out for minimum speeds with regards to lubrication. Some machines use mechanically driven lube pumps which stop working below a certain speed. If it is a problem, many people just replace the lube pump with an electrically driven constant speed version.

JRaef.com
Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[itsmoked]

Most the air compressors over 20HP seem to be going VFD these days. Everyone I've talked to say they absolutely love them.

One place raved that they are going to have less than a year ROI for a 30HP they just installed.

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[oldfieldguy]

I'm working on the installation of two 9000-hp and one 7000-hp installations in gas pipeline service.


old field guy

 

[Brian2903]

Do any one would know how much usually cost for a VFD which suitable for 600HP compressor?

 

[itsmoked]

Ouchy dollars..

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[jraef]

In what currency? This is an international forum.

JRaef.com
Eng-Tips: Help for your job, not for your homework Read faq731-376