The need for brown stock defoamers / wash aids
Foaming, slow drainage (in certain species) and high soda loss are typical challenges faced by the mills in brown stock washing. Surface foam and entrained air are the 2 main types of foam encountered in the pulp mill, with the latter leading to operating problems. Defoamers/wash aids are chemicals added for the purpose of foam control and to facilitate effective washing.
The use of defoamers / wash aids provides the following benefits:
- Effective knock down of foams.
- Improved runnability of pulp on washers.
- Improved drainage in washers.
- Improved washing efficiency in washers.
- Reduced soda loss in washers.
- Reduced bleaching chemical requirements.
- Reduced cost of cooking chemicals.
- Reduced deposit potential in system and lower treatment cost for pitch control.
Defoamers / wash aids are dosed at multiple feed points in the brown stock washing process, O2 delignification and sometimes at the EO stages of bleaching. Dosage levels vary between 0.01 – 0.04 Kg/Adt pulp per application point, with total dosage depending on the different raw material furnishes. Continuous feed is recommended for optimum control.
Defoamers / wash aids are also used in the paper machine, in areas such as the pulp dryer white water system, additives system, size press, coaters & effluent treatment.
Amazon Papyrus has a range of defoamers / wash aids for different fibrous raw materials, system designs and specific purposes. These products are blends of Poly Dimethyl Siloxane (PDMS), hydrophobized silica and surfactants, and are broadly classified as concentrates, water-based and oil-based systems.
Our team of professionals would work with you to select the most appropriate products to meet your specific needs.