ANDRITZ pulp dryers
The ANDRITZ pulp sheet dryer of today is the result of experience gained from close to 500 pulp dryer installations since 1928 and continuous R&D activities.
More capacity in less space
The ANDRITZ pulp dryer requires less space for a specific production rate – or provides more capacity in a given machine room when replacing an old dryer. The dryers have a capacity from 100-5,000 t/d.
The compact design is a result of high efficiency air impingement on both sides of the pulp web. This provides uniform and high heat transfer to the pulp web.
Low web tension for high operating reliability
The bottom blowboxes, an exclusive ANDRITZ design utilizing the Bernoulli principle, lift the sheet clear of the drying deck and locate it at a fixed distance above the blowbox deck. With this design, the sheet can be dried with minimal web tension and without sheet flutter.
Low tensile strength pulp
Birch, beech, eucalyptus, mixed tropical hardwood, CTMP, and dissolving pulp are examples of low tensile strength pulps that are effectively dried in ANDRITZ dryers.
Low pulp web temperatures for high quality pulp and brightness
The ANDRITZ dryer utilizes heated air to dry and support the pulp web. The web is fed into the upper deck of the dryer, where it is supported by air while making several horizontal passes back and forth along the entire length of the dryer.
The web never touches a heated steel surface.
The impingement system allows gentle drying at low temperatures for the production of consistently high quality pulp with uniform dryness across the width of the sheet.
Brightness is maintained because of a low pulp-web temperature during air drying. The evaporative cooling effect permits evaporation to take place at the low wet bulb temperature of the drying air.
Sheet cooler for fully bleached pulp
The ANDRITZ pulp dryer normally has an integrated sheet cooler, but this can also be supplied as a separate unit. In the integrated design, the bottom decks are equipped with cooling air blowboxes. There are a number of advantages using a sheet cooler:
- Minimum brightness reversion during storage
- No condensation during pulp storage and transport
- Longer cutter knife life
- More uniform bales
Cost-saving design with low energy consumption
Drying in an ANDRITZ dryer results in lower production costs due to reduced energy consumption and less required maintenance. Drying air entering the bottom of the dryer is continuously re-circulated and reheated in the internal air circuits before it is exhausted into the heat recovery system. The heat in the humid exhaust air is utilized primarily to heat the make-up air supplied to the dryer. It can also be further used to heat process water and water for machine room ventilation. Maintenance costs are low, due to the robust design and its few moving parts. Only the fan impellers and rolls move during operation.
ANDRITZ pulp dryer advantages
- The most compact and effective dryer on the market
- Suitable also for the weakest pulp types
- Low steam and electrical power consumption
- Automatic tail threading system for fast threading at full machine speed
- Improved cleaning tools (internal broke nips, broke detection system) for faster cleaning