In viscose fiber production, cellulose is regenerated into fiber as it is extruded through spinnerets into an acidic spin bath. The bath circulates continuously and gradually picks up suspended solids, dirt and fiber fragments. If these are not removed, they disrupt fiber formation, and because the bath has to keep running, any filtration problem quickly becomes a production problem.
Project at a glance
| Customer | Viscose fiber producer, India |
| Application | Spin bath filtration in FR-grade viscose fiber production |
| Scope | One skid-mounted FUNDABAC® candle filter |
| Process challenge | Continuous removal of suspended solids, dirt and fibers from an acidic spin bath |
Why is spin bath filtration difficult in viscose production?
Spin bath filtration combines three demands that are hard to meet at the same time. The medium is aggressive and acidic, so every wetted part has to withstand corrosion over years of operation. The solids are a mix of fine suspended particles, dirt and fibers, which can blind filter media and must be retained reliably to keep fiber quality consistent. And the filtration has to run continuously, because an interruption in the spin bath means an unplanned stop of the spinning line.
Manual handling adds a further risk. In filters that must be opened for cleaning or cake removal, operators come into contact with acidic solids and liquor, and every opening interrupts operation.
How does the FUNDABAC® candle filter handle spin bath filtration?
DrM has supplied a skid-mounted FUNDABAC® candle filter for spin bath filtration to a producer of FR-grade (fire-resistant, also called flame-retardant) viscose fiber in India, designed for a capacity of 50 m³/h. The suspended solids, dirt and fibers build up as a cake on the filter candles, and the clear filtrate returns to the spin bath.
The system was designed around the requirements of the duty:
- Skid-mounted construction for faster installation on site
- Fully automated operation without manual intervention between filtration cycles
- Heel volume filtration, so the liquid remaining in the vessel is filtered rather than drained
- Dry cake discharge, so operators do not handle acidic solids
- Enclosed design that keeps the acidic liquor contained
Because filtration, heel volume filtration, cake discharge and the return of the filter to operation run as one automated cycle, the spin bath can be filtered continuously without stopping the line for manual cleaning.
Where else is FUNDABAC® filtration applied in a viscose line?
The same technology covers other filtration duties along the viscose line. These include the second bath, acid water and spin bath backwash water filtration, which share the same combination of acidic media and fine solids. Using one filtration technology across several duties simplifies operation, spare parts and maintenance for the producer.
This project adds to DrM’s reference base in viscose and cellulose fiber production, where more than 150 FUNDABAC® filters have been supplied to producers in Asia and Europe for spin bath, sour water and acid wash duties.
