The sulphuric acid used as a neutralising agent during tall oil production can be partially replaced by CO2. By adding CO2, the tall soap is adjusted to a neutral pH and the NaHCO3 liquor separated, which can then be fed to chemical recovery. In a further step, acidification and boiling with sulphuric acid (H2SO4) is performed. About 50 % of the H2SO4 can be replaced by CO2.
Possible advantages of using this technology:
- Lower sulphate emissions
- Improved control of the Na/S ratio in chemical recovery cycle
- Savings in H2SO4 and NaOH
As hardware for the feed and dissolution of carbon dioxide, especially in highly viscous mixtures, especially designed nozzles must be used whose tendency to clog is as low as possible.