Optimize Dilution Factor in Brownstock Washing

In chemical pulping, the objective of brownstock washing is to remove the maximum amount of black liquor dissolved solids from the pulp with the use of minimum amounts of water. Removal of black liquor solids is important both for the efficiency and cost of bleaching and papermaking processes and for the efficiency of heat recovery and reduction of the use of make-up chemicals. Optimizing the amount of washing water used is essential and requires careful consideration of the implications of amount of water used on washing efficiency and heat recovery efficiencies. Dilution factor optimization control will lower the amount of water that must be evaporated from weak black liquor. Therefore it will reduce steam consumption in the evaporators. The dilution factor can be optimized by controlling shower water flow on the last washing stage to an optimum level by considering the cost of steam, the cost of bleaching chemicals, the impact on effluent quality, and other process variables (NCASI, 2001. p. 71).

Development Status Products
Commercial
Chemical Pulp

Optimize Dilution Factor in Brownstock WashingCosts & Benefits

Parent Process: Chemical Pulping
Energy Savings Potential

In a US based plant, the measure helped reduce natural gas usage by 327 000 GJ/y and saved 45.6 m3 of water per hour. (Kramer et al., 2009. p.91)

CO2 Emission Reduction Potential
Costs

Corresponding cost savings of $580,000/year were realized (Kramer et al., 2009. p.91)

Optimize Dilution Factor in Brownstock Washing Publications

Page Number: 

91

Page Number: 

71-73