Correct use of defoamers

Defoamer, also known as antifoam, is a substance with low surface tension and high surface activity that can inhibit or eliminate foam in liquid. Defoamers are generally made by compounding multiple components. The performance of the main defoamer can be enhanced by compounding surfactants. Whether an active substance is suitable for defoaming depends on its application conditions. Under acidic conditions, stearic acid is a defoamer; And under alkaline conditions, it is a foaming agent. Effective at low temperatures, but ineffective at high temperatures.

1. The addition point of defoamers: Defoamers are generally added in the bleaching and washing sections of pulp mills, and are usually added in the washing machine, concentrator, and pulp tank. Defoamers in the papermaking section are generally added to the pulp box, pulp tank, coating and sizing press of the paper machine. 

2. Addition amount: Generally, using two types of defoamers is more economical and effective than using a higher content of one defoamer, and should be added separately at distant locations. For example, one defoamer is added before the pulping machine, while the other is added in the flow box. 

3. The precipitation problem of defoamers: such as amide defoamers, it can cause precipitation and block the screen plate gaps, which can lead to paper diseases such as fish eye spots due to poor dispersion. Some defoamers can also interfere with the effects of sizing and reinforcement.