Wellman – Lord Process
- This process consists of the following subprocesses:
- Flue gas pre-treatment.
- Sulfur dioxide absorption by sodium sulfite
- Purge treatment
- Sodium sulfite regeneration.
- The concentrated sulfur dioxide stream is processed to a marketable product.
The flue gas is pre - treated to remove the particulate. The sodium sulfite neutralizes the sulfur dioxide:
- Some of the Na2SO3 reacts with O2 and the SO3 present in the flue gas to form Na2SO4 and NaHSO3
- Sodium sulfate does not help in the removal of sulfur dioxide, and is removed. Part of the bisulfate stream is chilled to precipitate the remaining bisulfate. The remaining bisulfate stream is evaporated to release the sulfur dioxide, and regenerate the bisulfite.