Small multi-stage reciprocating compressor 1

[rquery]

I am looking for a list of manufacturers producing small (~200 scfh CO2) multi-stage compressors to boost CO2 pressure from near atmospheric to 1000 psi. Any suggestions appreciated.

 

[zdas04]

That is 69 compression ratios. I like to keep a 3 stage compressor under 4 CR/stage (64 CR total), but this would only be 4.1 ratios so you should be more or less ok.

With your flow rate, compressing CO2 this much gives you around 2.5 hp. With interstage cooling losses, I'd probably look at 3.5 hp motor or 5 hp engine.

I've never looked for a 3.5-5 hp 3-stage compressor so I can't tell you where to look.

David

 

[bcs5274]

there are several manufacturers making small 3 and 4 stage units for cng fueling in the same size as what you are looking for. corken is one reliable unit in small size that works well

 

[zeusfaber]

What part of the world?

A

 

[ARenko]

I'm not sure if they make compressors to handle CO2, but I've used air-driven Haskel gas boosters for boosting small volumes of N2 to high pressure before. Maybe something like that would work.

 

[Montemayor]

rquery:

What you are looking for is a specialty of Rix Compressors.

Go to:

http://www.rixindustries.com/finder.html

Where you can compute the size (Approx. 3 hp) and the specific model they can offer you.

 

[dcasto]

I'd stay away from 3 stages as the discharge temp goes to over 400F A 4 stage will keep the temp closer to 300F.

the rix specified has a 750 psig MAOP, that ain't gonna work unles they give you a waiver.

 

[Montemayor]

dcasto:

The standard for compressing CO2 and liquefying it in the CO2 industry was, for approximately 70 years, a 3-stage compression cycle starting with essentially atmospheric CO2. I designed, installed and operated over 20 of these reciprocating applications in various countries and the usual conditions were, as I remember:

1st Stage Suction = 1 - 1.5 psig, 85 oF
1st Stage Discharge = 60 psig, 250 oF
2nd Stage Suction = 58 psig, 90 oF
2nd Stage Discharge = 260 psig, 275 oF
3rd Stage Suction = 255 psig, 90 oF
3rd Stage Discharge =1,200 psig, 285 oF

I clearly recall that we never came close to the 350 oF. With leaky discharge valves we developed around 325 oF.

Some of the machines were horizontal, in tandem; others were horizontal, balance-opposed. We were the world's largest CO2 producer at the time and we never used a 4-stage recip for this service because a 3-stage did a good job.

I later took some of these compressors and re-bored the 3rd stage oversize to recycle expanded -10 oF vapors generated by expansion of the HP liquid into 250 psig storage tanks. This allowed me to convert what we used to call High Pressure CO2 process to a Low Pressure (250 psig) CO2 process, storing the LP CO2 as saturated liquid and also storing and distributing it as such.

I don't think your concerns about having to use a 4-stage machine are valid.

 

[dcasto]

Monte, how do you get a 65F after cooler temP. Try air cooled with a 125F suction.

 

[Montemayor]

dcasto:

I don't know where the 65F after cooler temP comes from. I don't think I mentioned it and haven't found it in the thread. Have I missed something?

I just wanted to mention the fact that this is not an exceptional or unique application. The Rix compressor recommended by Rix does have a MAWP above 1200 psig - all it is, is a change-out of the 3rd stage cylinder that "sits" on top of the 2nd stage, in tandem. It's a small modification on a small machine and mentioned in their brochure.

Good to visit this forum again, and see the old pros still fighting the good fight with logic, experience, and good sense.

 

[dcasto]

Montemayor

i was just keeping a design simple. a 65F or even a 30F interstage would be achievable with refrigeration. On a huge scale, that might be cost justified. On a little unit, air cooled interstages is the most economical Adding a stage woulfd be a minimal cos.

I went to the rix site and it recommended a unit. that recommendation was for a 750 psig maop unit. I figuired that they would do a custom machine for not much more to get the 1000 required.