SWCHEM’s C₂ recovery technology is used to recover and purify C₂ hydrocarbons, mainly ethylene and ethane, from refinery dry gas by utilizing the different adsorption capacities of adsorbents for various gas components under different pressure conditions.
During adsorption at elevated pressure, C₂ and heavier hydrocarbons are selectively adsorbed by the adsorbent, while weakly adsorbed components such as H₂, CH₄, O₂, N₂ and CO pass through the adsorber and are discharged from the outlet.
This technology is suitable for recovering valuable ethylene- and ethane-containing components from FCC dry gas, coking dry gas and other refinery off-gases.
The ethylene recovery process is based on selective adsorption and pressure swing regeneration.
At higher pressure, hydrocarbon components such as ethylene, ethane and other C₂+ components are selectively adsorbed on the adsorbent bed. Weakly adsorbed components, including H₂, CH₄, O₂, N₂ and CO, pass through the adsorber and leave the system as off-gas.
During depressurization or vacuum regeneration, the adsorbed C₂+ hydrocarbons are desorbed from the adsorbent and recovered as semi-product gas. The regenerated adsorber is then returned to the adsorption step for cyclic operation.
After compression, the semi-product gas enters a downstream purification system to remove impurities such as H₂S, organic sulfur compounds, CO₂, arsenic and water, producing purified C₂+-rich gas according to customer requirements.
Applicable feed gases include:
| Item | Data |
|---|---|
| Feed gas | Refinery dry gas |
| Pressure | Dry gas pressure |
| Temperature | Ambient temperature |
| Item | Data |
|---|---|
| Product | Purified C₂-rich gas |
| Arsenic content | < 5 ppb |
| Sulfur and organic sulfur content | < 0.1 ppm |
| CO₂ content | < 1 ppm |
| H₂O content | < 1 ppm |
| O₂ content | < 1 ppm |
Note: Product specifications can be adjusted according to customer applications and project requirements.
The purification units are controlled by dedicated controllers and instruments. Depending on the unit scale, automation level and customer control requirements, a DCS control system consistent with the customer’s main plant may be used, or a standalone PLC control system may be selected.
In addition to conventional PSA sequence control, loop control and other control functions, SWCHEM also provides specialized control strategies for fully automatic load adjustment, fault diagnosis and fault isolation.
The system can support adaptive optimization, self-diagnosis and fault isolation, improving operational flexibility and helping ensure long-term, stable and safe operation of the unit.
SWCHEM provides:
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