CO2 Acidification

Carbon dioxide acidification of brownstock washers.

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.

CO2 acidification of brownstock washers can reduce your pulp and paper production chemical cost. It can clean up your pulp and reduce overall chemical consumption.
How acidification works
The black liquor and pulp must be separated after they exit the digester so that the pulp can go on to the papermaking process.
This separation occurs on brown stock washers, where water is used to wash the black liquor from the pulp.
Washed pulp

In case the washed pulp goes to the bleaching process.

Reduction of dilution factor

CO2 also allows a reduction of the chlorinated agents usedat the first stage, (CDO). Increase content of solids Black Liquor.

Chemical losses

Minimise chemical losses at the black liquor.

Recovery system

Recovery system (NaOH); low chemical comsumption (paper machine)

Slide to learn about Nippon Gases over time

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