The importance of tailoring formulations according to application
The requirements for acid gas removal units can vary significantly based on the gas stream source and intended use. Although specifications for residual sulfur components are often stringent, not all gas streams contain hydrogen sulfide (H2S) or other sulfur species.
CO2 concentration and organic species
The carbon dioxide (CO2) concentration may vary from zero to over 50%, and not every application requires complete removal. The gas stream may also contain traces of organic species like mercaptans or carbonyl sulfide.
Selective amine reactions
Amines have a general affinity for acid gases due to the acid-base reaction, allowing efficient removal with minimal absorption of inert components like hydrocarbons, hydrogen and nitrogen.
However, the reaction kinetics vary significantly based on the amine type and acid gas component. By selecting the appropriate amine or amine combination and optimizing plant design, the acid gas removal system can be tailored to its specific gas composition and treated gas application.
Impact of gas pressure
Gas pressure is another crucial factor in amine selection and plant design. Higher pressures favor absorption, but amines are also capable of working efficiently at low feed pressure. In fact, in such conditions, amines are often preferred because the chemical reactions enable an efficient process. Other solutions, such as physical solvents or membranes, are strongly reliant on pressure for gas separation.
The applications for acid gas removal can be broadly categorized as follows:
- Natural gas processing
- Tail gas treatment
- Acid gas enrichment
- Refinery gas treatment
- Ammonia production
- Syngas treatment
Amine solutions for CO2 removal in flue gas
To address the diverse challenges of these applications, Eastman has developed a product portfolio tailored to various removal needs. The final selection considers processing conditions, economics, robustness and environmental constraints. While Eastman doesn't actively develop solvents for flue gas treatment, our extensive amine portfolio is available to technology developers and operators of flue gas CO2 removal plants.
Gas treatment specifications
| Application | Pressure bar | Feed — CO2 | Feed — H2S | CO2 spec | H2S spec |
|---|---|---|---|---|---|
| Natural gas | 15–100 | 2%–70% | 0%–20% | 50 ppmv–20% | 4–16 ppmv |
| Tail gas treatment | ~ 1 | 2%–30% | 0.5%–3% | Slip! | 10–250 ppmv |
| Acid gas enrichment | ~ 1 |
60%–95% | 5%–30% | Slip! |
10–250 ppmv |
| Refinery gas | 5–150 | 0%–5% | 1%–10% | — | 4–50 ppmv |
| Ammonia | ~ 20 | 15%–25% | 0% | 100–1000 ppmv | N/A |
| Syngas | 5–50 | 5%–30% | 0%–5% | Varies | 1–4 ppmv |
| Flue gas | ~ 1 | 5%–10% | 0% | ~ 1% | N/A |