Key Equipment - DD Washer
spectrum36_dd-washer_cover

EVOLUTION OF THE ANDRITZ DD WASHER

Each generation better than the previous

The DD-Washer was introduced in the early 1980s when the first commercial-scale unit went into production in a kraft pulp mill in Finland. Today, five generations later, every kraft pulp mill in Finland has ordered at least one DD-Washer (the latest order is for Stora Enso’s Kemi mill) – and the washer has achieved global acceptance. With more than 340 installations in 24 countries, the multi-stage washing efficiency and extremely high production throughput of the DD-Washer is clearly preferred for all fiberline washing applications – brownstock, post-oxygen, and bleaching. The largest DD-Washer today has almost 150 times the capacity of the first washer sold.

BENEFITS:

  • Multiple washing stages on a single drum
  • Compact design
  • Extremely high washing efficiency
  • Extremely energy efficient
  • Fractionated filtrates to conserve water
  • Retains fiber qualities: less fiber damage when no mechanical pressing
  • Fast start-up and high availability
  • Production throughput up to 6,250 t/d in a single unit

CLEAR ADVANTAGES OF DISPLACEMENT WASHING

In the early days, almost all mills had vacuum drum filter washers. The main disadvantage was the amount of serial equipment to reach a certain wash result and a limited process temperature. Following this, wash presses were introduced. The main disadvantage was the requirement to dilute and then mechanically press the pulp several times to reach a desired high consistency. The DD-Washer performs all washing stages in a single rotating drum and roughly at the same consistency without dilution. Since there is no mechanical pressing during washing, the DD-Washer is extremely gentle, retaining all the bulk, stiffness, and strength of the original fibers.

spectrum36_dd-washer_002

“The design of the DD-Washer has been perfected through evolution, not revolution. The newest generation features improvements in pulp and filtrate hydraulics to increase throughput by about 20%.”

PASI IMMONEN
Manager Washers and Filters
ANDRITZ Fiber Technologies

Contact us
Downloads
  • EVOLUTION OF THE ANDRITZ DD WASHER PDF : 997 KB