The CO2 dissolves in water and forms carbonic acid to reduce the pH levels in the brownstock.
Increase productivity and achieve higher process stability by injecting CO2 into the wash water at the final stage of the washing cycle. Lower brownstock pH reduces fiber swelling and leads to a better pulp drainage improving washing efficiency. Lower pH levels also reduce sodium loss in the washing stage.
In case the washed pulp goes to the bleaching process.
CO2 also allows a reduction of the chlorinated agents usedat the first stage, (CDO). Increase content of solids Black Liquor.
Minimise chemical losses at the black liquor.
Recovery system (NaOH); low chemical comsumption (paper machine)