Eastman AdapT for natural gas treatment
Natural gas extracted from the earth may contain valuable hydrocarbon components as well as undesirable contaminants such as water, mercury, carbon dioxide (CO2), hydrogen sulfide (H2S), mercaptans and carbonyl sulfide (COS). These are termed acid gases because they form acids in aqueous solutions. The removal of these contaminants varies based on the intended use, such as liquefied natural gas (LNG) production, pipeline transport or local consumption for power production. Some wells may also contain sulfur species that require removal.
Processes:
Products:
Requirements:
CO2 — The specifications for CO2 removal vary according to the target use.
LNG production — There are stringent specifications due to risk of solidification in the cold box
Pipeline transportation — Generally, up to 2% of CO2 is permitted; this limit is associated with pipeline corrosion, gas calorific value and international gas standards.
Local consumption of natural gas for power production — Higher CO2 concentrations can be accepted because downstream equipment can be adapted to accommodate the higher concentrations.
H2S — Sulfur must be reduced to very low concentrations for safety, corrosion and environmental impact reasons.
Mercaptans and COS — These components can be removed with amine solvents. Their removal is more challenging because they are very weak acids and react less strongly. Each case requires individual evaluation, and the best solution may be to combine amines with other removal technologies.
| Application | Feed — CO2 | Feed — H2S | CO2 spec | H2S spec |
|---|---|---|---|---|
| Power generation | 2%–70% | 0%–20% | 5%–20% | 4–16 ppmv |
| Pipeline gas | 2%–70% | 0%–20% | 2% | 4–16 ppmv |
| LNG | 2%–70% | 0%–20% | 50 ppmv | 4 ppmv |
Considering pressure and temperature
Pressure — The natural gas stream typically enters the treatment facility at high to very high pressure, which benefits acid gas removal and other processes. High pressure allows for greater amine solvent loading, reduces regeneration needs and supports more compact equipment design.
Temperature — It’s important to avoid exceeding temperature limits in the absorber. The temperature bulge, or maximum temperature inside the absorber, can be much higher than the absorption temperature measured in the treated gas and rich amine solvent stream.