Drainage & its Impact and Benefits
Drainage :-
The word “drainage” refers to the ease with which water is released from papermaking furnish, especially in the early part of a paper machine’s forming section. The word “dewatering” is more general, including the effects of vacuum and pressing as means of getting water out of the wet web. Drainage tends to be inhibited by the presence of fiber fines, high basis weight webs, high levels of refining, and any excess of polyelectrolyte’s remaining in the solution phase. Drainage rates often can be increased by the use of highly cationic chemicals such as alum, polyamines, or PEI products. Micro particle programs are designed to increase drainage rates. Factors that increase fiber flocculation are likely to increase initial drainage rates, but they are also likely to hurt the performance of vacuum dewatering and pressing.
In simple Language Fiber is to be retained from the pulp and drain more water in the pulp is called drainage.
Issues that arise due to low retention and drainage:-
In the process of papermaking, the absence of proper retention and drainage can cause the following issues:
• Increased drainage of fillers and fiber particles
• Higher cost of sizing and additives
• Decreased operational efficiency
• Increased deposits
• More time required for cleaning
• Bad formation of paper sheets
• Quick wet-press felt filling
• Higher loss of material to sewers
Benefits of Retention and Drainage Aids :-
For the finest retention of colloids and fine particles during a paper creation process, the zeta potential should be close to zero, aided by retention chemicals.
The main operations conducted by retention and drainage aid include the following:
• Accelerating drainage to provide improved speed to the machine.
• Improving the retention rate of fillers and fines.
• Reducing the use of sizing and wet-end additives.
• Reducing the risks of sheet breaks.
• Improving the operational performance of the paper machine.
• Enhancing the formation of high-quality paper sheets.
• Cleaner system of white water.
• Reducing the downtime related to cleaning everything.
• Improved runnability
• Increased paper quality
• Improved dewatering and retention of papermaking chemicals
• Paper chemical cost savings
• Higher productivity at lower cost
• Longer felt life