Screw and Centrifugal compressors! which is better?

[JERRYCOOL]

If we got a working condition which is suitable for both centrifugal adn screw compressor. Ignore the prices and partial load issues. Which will be prefer to use? And Could anybody tell me how good about Yorks centrifugal compressors for propylene refrigeration system?

Thanks very much!!!!!

[Josip]

Hi, JERRYCOOL

If we got a working condition which is suitable for both centrifugal adn screw compressor. Ignore the prices and partial load issues. Which will be prefer to use? And Could anybody tell me how good about Yorks centrifugal compressors for propylene refrigeration system?

Thanks very much!!!!!

This is probably some petrochemical plant?

.....anyhow I think we need much more info about plant to be able to suggest something....final decision depends on many things....


Best regards, Josip

[TXiceman]

The York multistage centrifugal or "Turbomaster" is a compressor created from the commerical design originally operating on ***** gases. If has been adapted to operate on an lot of gases over the years.

If the customer is asking for API on the compressor, the York is not capabale of coming close to API. For an API machine such as an Elliott, you can add $1MM to the Yrok base price. The difference is like a Mack truck and an Isuzu pick up.

The centrifugal will have better full load performance but is limited on turn down. The more stages and the more side loads, the less turn down. Typically, a centrifugal will onloy turn down to about 50 or 60% flow before you go to hot gas bypass. The centrifugal does not like changing opering conditions.

A screw will generally be slightly less efficient at full load, but will really beat the centrifufgal on turn down. This is especially true of a plant that will be operating part of the time at or below 50% and you can install two 50% or two 60% drive lines wher you can shut down a compressor. Another alternate is to install 3 - 50% compressors for a pip[ed in spare or 4 - 33% machines.

Another issue is the physical size of the plant. The screws, especially the multiples will require more footprint.

You have alot of homework to do on this project.

I would personally prefer to have a plant with multiple screw compressors over a single York.

Ken

[Lowrider]

You'll also have to asses what your lowest load and highest load are going to be. If you lowest load is below the operating specs, then it's perhaps better to look at buying a screw and a centri. With the right controls you can maintain a steady supply temperature.

What loads are we talking about?

An other thing too look at is available voltage at the location, because some centri's, especially the larger ones need for instance 10kV.

[sagittarius]

I think centrifugal compressor is suitable for air-conditioning system. screw compressor is to more regions besides the capacity limits.
I agree with TXiceman.

[Tesla]

It depends on load characteristics - Mainly high load = centrif, average varying load = screw, and lo load = turbocor. Another consideration is the temp and efficiency at that temp.

[JERRYCOOL]

It's propylene system. water cooled condenser, evaporating temp is -6 C.
The compressor will be driven by Motor.
The Motor power is about 4000kw.
York said that their centrifugal compressor is the best of the world. Another company can do the job by Howden screw compressor. We are not sure which is better if price is not a big issue.

[JERRYCOOL]

It's propylene system. water cooled condenser, evaporating temp is -6 C.
The compressor will be driven by Motor.
The Motor power is about 4000kw.
York said that their centrifugal compressor is the best of the world. Another company can do the job by Howden screw compressor. We are not sure which is better if price is not a big issue.

[JERRYCOOL]

We can't split the capacity to 2 or 3 screw compressor because of the room limitaiton.

[JERRYCOOL]

The York multistage centrifugal or "Turbomaster" is a compressor created from the commerical design originally operating on ***** gases. If has been adapted to operate on an lot of gases over the years.

If the customer is asking for API on the compressor, the York is not capabale of coming close to API. For an API machine such as an Elliott, you can add $1MM to the Yrok base price. The difference is like a Mack truck and an Isuzu pick up.

The centrifugal will have better full load performance but is limited on turn down. The more stages and the more side loads, the less turn down. Typically, a centrifugal will onloy turn down to about 50 or 60% flow before you go to hot gas bypass. The centrifugal does not like changing opering conditions.

A screw will generally be slightly less efficient at full load, but will really beat the centrifufgal on turn down.
Ken

I quite agree with Ken.
We can't require York for API. And there is no other company want to compete with York by API centrifugal.
About the turn down issue, there are 3 other screw compressor in operation already. So York recommend to leave centrifugal full running and adjust the load by Screws.
It looks perfect plan.

[TXiceman]

The centrifugal compressor is most efficient at full load. The York centrifugal is a very long way from API. Their exceptions ia about as long as API 610.

The reason the API suppliers like Elliott do not want to compete is that they have a $1MM disadvantage from the start. API 610 requires an API 614 lube system which has dual pimps, dual oil cooler, dual filters, stainless steel piping and lots of expensive instrumentation.

York pretty much has the market controlled fro a non-API hydrocarbon compressor. If the machine is installed in a well designed system, clean, no liquid carry over problems and such, it may run 100,000 hours. But it is not a very forgiving compressor, nor is the limited lube oil system.

If you want an API Refigeration System, talk to FES (GEA). They understand API centrifugals and refrigeration systems. The compressor manufacturers do very well on compressors, but are really limited on system design.

Ken