GAS GUIDE
CO₂ Compression
Well behaved when dry, carbonic acid when wet — and above 7.38 MPa it stops being a gas at all.
Dry CO2 is well behaved; wet CO2 forms carbonic acid and attacks carbon steel readily. Its low isentropic exponent keeps the discharge temperature low, which is why SNP$^{2}$ high ratio CO2 duties are more forgiving than hydrocarbons at the same pressure ratio — but near-critical / dry-ice formation conditions must be checked.
The properties that drive the choice
| Molecular weight | 44.01 |
|---|---|
| Isentropic exponent k (ambient) | 1.289 |
| Hazard profile | none of note |
| Oil-free | Not required by the gas |
| Corrosion | Aggressive when wet |
Which families serve it
| Family | Role in this service | Envelope | |
|---|---|---|---|
| Reciprocating | High-pressure CO₂ duty: injection-adjacent and process boosting | to 400 bar(g) | family page → |
| Oil-injected screw | CO₂ boosting where oil contact is acceptable | to 50 bar(g) | family page → |
| Dry screw | Larger flows at moderate pressure, tolerant of carry-over | to 45 bar(g), differential ≤ 15 bar | family page → |
Where the boundaries sit
- Wet CO₂ forms carbonic acid — anything that can see water needs 316L or better, and the moisture level belongs in the enquiry
- Throttle and start-up conditions can drop the temperature into dry-ice territory; that is an operating-instruction question
- The largest CCUS flows are dynamic-machine territory (centrifugal), outside this site's positive-displacement scope — the tool says so rather than bending a family to fit
Materials
316L or better for any stream that can condense water; dry-ice formation during throttling or start-up deserves an explicit operating instruction.
Related reading
Running a duty point on this gas? The selector on the home page maps gas, pressures, flow and temperature to a machine family with its boundary conditions — free.
Open the tool →