The COMPACT PRESS: Completing the ANDRITZ washing range

The COMPACT PRESS is the latest addition to the high-efficiency pulp washing solutions available from ANDRITZ.

Along with the well-known DD-Washer, the introduction of the COMPACT PRESS now means ANDRITZ covers the complete range of solutions available for effective and efficient pulp washing for all capacities of pulp mills, from the very small to the very large.

The COMPACT PRESS has been named for a good reason; it has a small footprint and is compact in design, making it the perfect retrofit washer for all sizes and capacities of pulp mills, including those with limited space in the fiberline. The presses are available in nine different sizes starting from a capacity of 400 t/d up to 6,000 t/d and are designed to suit all pulping processes, including kraft, semi-chemical, and mechanical pulp. The latest development at ANDRITZ has seen the introduction of a press for the dewatering of mechanical pulp, which is based on the same technology.

The presses have a number of proven advantages that set them apart from other wash presses, including a highly efficient process with high discharge consistency, tough, durable components, and easy maintenance. Over 150 COMPACT PRESS units have been sold to date with the first one being delivered in 2000 and still operating successfully.




Depending on the applications, the presses can be fed from 2% up to 10% feed consistency. What is unique about the COMPACT PRESS in the ANDRITZ washer range is the high discharge consistency – around 30% from the machine, which is beneficial when separating mill waters from the acidic stage to the alkaline stage.

Uniformity of pulp is very important when creating an efficient process, and it is essential to have distribution of pulp evenly spread across the perforated drum. This even distribution is ensured by unique, specially designed screws that are speed controlled so the transport capacity is adjusted to meet the needs of the pulp fed into the machine.

The COMPACT PRESS enables high consistency starting at the dewatering phase where consistency of the pulp is increased by a converging gap between a perforated drum and the static sliding surface of the press. When the consistency has been increased, the wash liquor is then added in two zones. The benefit of the increased consistency means there is less free liquid in the pulp to displace and the wash liquor is used more efficiently, thus saving on chemical costs.

The second phase of the of washing takes place when the pulp is distributed across the full width of the perforated drum and the wash liquor is distributed via a large number of nozzles in two zones to ensure maximum displacement.

The final pressing is done between the two drums where the pulp is pulled by the perforated drum through the press nip where the free liquid is squeezed out. Another unique feature of COMPACT PRESS is the integration of the dilution screw into the press itself, which eliminates the need for a separate dilution screw or device and makes the layout more compact and efficient.

Anders Lindström, Product Manager, COMPACT PRESS ANDRITZ

“Along with its minimal footprint, the COMPACT PRESS has many advantages, including highly efficient washing for producing clean pulp, made-to-last durable components with a long-life cycle, and low cost of ownership due to easy maintenance.”

Anders Lindström

Product Manager, COMPACT PRESS


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The main component of the COMPACT PRESS is the MaxDrum, which has been developed with a solid support structure. The drum is built to last, with some examples already having been in operation for over 20 years. The main feature of the drum is the screen plate, which is over 4 mm thick, and the support structure underneath, which is 70 mm in depth giving maximum strength and support. Along with added strength, this means the drum is extremely fatigue resistant.

The MaxDrum also comes with several safety features, including an overload protection system that allows both drums to move should a foreign object enter the process.

When it comes to maintenance, the COMPACT PRESS has been designed with maximum efficiency in mind. The press is fitted with a service hydraulic system that allows the opening of the machine for access to the drum surface and seals. The vat can be lowered to get access underneath the press, so there is no need to use a powered crane, and full maintenance can be carried out with minimal person hours.