Washing Presses

Pulp washing on presses provide a better washing efficiency (70-85%) as compared to washing on filters (with washing efficiency of around 65%). Washing is carried out counter-current to the refining process to ensure maximum removal of dissolved material while using a minimum amount of water. This is done using the minimum quantity of fresh water. Washing presses have higher capital requirements but these can be partly or fully offset by lower building costs and smaller filter tanks. Savings in steam and chemical consumption provide additional benefits for using washing presses (Martin et al., 2000. p.29-30).

Development Status Products
Commercial

Washing PressesCosts & Benefits

Parent Process: Bleaching
Energy Savings Potential

Savings from reduced steam consumption are estimated as 0.38 GJ/t pulp (Martin et al., 2000. p.30).

CO2 Emission Reduction Potential
Costs

Operation cost savings from lower chemical use will be approximately $0.53/t pulp. Capital cost with pre- and post-lignification process equipment has been estimated as $6 million for a plant of capacity 900 tpd (Martin et al., 2000. p.30).