PUMP OR COMPRESSOR CO2 AT SUPERCRITICAL CONDITIONS 1

[ratash]

How do you determine whether to pump or compress 97% co2 into a pipeline, when it is in supercritical region?

 

[ratash]

Thanks.

1) Why do I need to purge it out after ESD? My vents all go to atmosphere.

2) I have recipe compressors with automatic clearance pockets for capacity control. Why should I use bypasses for capacity control?

3) Do you know for thh scrubber liquid-out what kind of a vessel I need? I mean does the sump need to be lined with????

Regards.

 

[maddocks]

An auto-purge after shutdown will allow you to clean out the machine and keep it dry and clean and free of the corrosive fluids that will potentially cool and condense in the compressor and piping.

If you have reviewed the capacity curves with the pockets open, and you are haeppy with the capacity, then you do not need to have auto-bypasses. However, I've never come across an acid gas machine that functions within pocket limits. As well, changing VVCP pocket settings tends to be a less than great way to vary recip capacity as it changes volumetric efficiency of the cylinder and modifies interstage pressures and temperatures.

The acid gas water sump vessel should be resistant to carbonic acid attack - you may wish to consider either a coated tank, FRP, or stainless steel.

Does your system contain H2S as well?

 

[ratash]

Thanks.

1. Great point about the purge issue.
2. Where do I add the bypasses (4 stages) for capacity control? I thought for recipes you don't add bypasses.
3. Yes, I do have H2S.
Regards.

 

[maddocks]

Unfortunately we're into some pretty detailed design parameters. I don't think we can do this justice with eng-tips.

You'd better get yourself a qualified consultant with some acid gas experience and review the system with them. As well, you should be talking with your compressor vendor - if they have any acid gas experience, they should be assisting you in your efforts to create a safe, operable system with maximum flexibility.

dcasto - your thoughts?

 

[ratash]

Thanks for your comments. I have no acid gas experience and pretty much most vendors are not interested to answer questions because this is in the budget stage. However, your comments have been very helpful. Regards.

 

[dcasto]

Maddocks and ratash
Yes, you are getting to the ponit where ratash can select a qualifies design person. On eng-tips we all like to help kick start ideas and get the poster to think about it. Then they can use basics and ideas to assist them.

Also, ratash, you have enough data to go get budgetary fiquires, the size of the equipment, the basic materials of construction, the ned or no need for driers, safety systems, capacity control needs, there should be very little ommissions onan RFP/RFQ.

If after ratash gets some info back from the vendors and they don't make sense, ratash could ask opinions here too I suppose.