Washing stage 2 and Pulp Storage - process info

After the Washer Feed Tank the pulp will be consist ency controlled to 0,9% and pumped to second washing stage. Similar to Washing stage 1 the second washing stage can consist of one or more washers in parallel depending on capacity requirement. The ash content of the pulp leaving the washers will be reduced to About 1%. The pulp will be conveyed to a MC pump and pumped to the Pulp Storage Tank. 

The pipe between the MC pump and the DIP Storage Tank can be designed (with diameter About 1500 mm and retention time 15-20 min) and serve as a bleach pipe. With this concept hydrosulphite will be added in the MC pump and bleaching take place without the pulp being in contact with air.

The filtrate from the washers will be dumped into the Washer Filtrate Tank. This filtrate will be used for dilution in the disperger, flotation and washing stage 2.

The amount of filtrate from Washing Stage 2 will however not be sufficient for the mentioned dilution points. Therefore some excess white water from TM 5 has to be added to the Washer Filtrate Chest.