Ethylene Compression

[hc80482]

We are working on a cracker unit. Ethylene product at battery limits is approximately 650#. Client has indicated that the export pipeline will require pressures as high as 1300#.

Anyone with experience compressing ethylene to pressures this high? Are there any special considerations must be taken into account? Is it better to pump the fluid once it becomes critical?

 

[TD2K]

I worked in an ethane cracker years ago but the ethylene was produced as a liquid at about 175 psig? (it was a long time ago, any exposed flanges were coated in ice so it was pretty chilly). We pumped the ethylene up to 1300 psig and then heated it to take it past the critical temperature.

We also had an ethylene refrigeration loop. Lowest suction pressure was just about atmospheric, discharge was likely 700 psig or so.

I'd talk to Elliott, you're only looking at a 2:1 compression ratio.

 

[Longinthetooth]

The ethane cracker I worked at was the same arrangement as TD2K's. Ethylene came off the splitter at -40C and was pumped up to 1300 psig and then heated to about 5-10C (I think) before it went into the pipeline. Pumps were 9 stage vertical in-ground. I forget who made them.

 

[dcasto]

ethylene is almost always transported above its criticle pressure, typically over 850 psig.

If your ethylene is a saturated liquid at 650 psig (at about 40F), I'd install a pump. A multistage one from bingham for example. If you want deluxe, try a ebara pump.

If the ethylene is a gas at 650 psig and 50F and above, a recip compressor will do just fine. All the chem plant operators laughed when I went this rout and said they'd install a chiller and condense the ethylene and then pump it. lets see, pumps, refrigerastion compressors, chillers, controls, yuck! If you want, you could use a centrifugal compressor, heck we used a bigham pump with modified inpellers raise the pressure on ethylene from 800 psig to 1650 psig in just 8 stages.