Upgrades, rebuilds, and services for pulp drying plants

Upgrades, rebuilds, and services for the wet end (approach system, screening, cleaning, and pulp dewatering)

• Approach: screening, cleaning, broke conveyor, broke pulper, micra screen
• Headbox: step diffuser headbox with manual or automatic dilution control
• Dilution cross profiler, adjustable during operation, provides even pulp distribution in the headbox
• Former: wire extraction unit (WEU), wire suction roll, anti rewetting unit (ARU), sheet transfer roll, steam blowbox
• Press section: heavy duty press, central suction roll (combi press with pick-up roll), edge trim control (ETC), shoe press with X-nip
• Wire regulating unit with simple, rigid design results in extremely accurate and trouble-free wire regulating
• Bearing protection package designed to eliminate risk of water and condensate entry

Upgrades, rebuilds and services for pulp drying

All ANDRITZ dryers can be extended in height or length by adding drying decks or drying sections. Experience has been gained from more than 30 dryer extensions all over the world.

Examples for upgrades, modernizations and rebuild products for pulp drying

• Improved threading tape made from heat-resistant and moisture-proof Aramid fiber provides a low stretch factor and extended lifetime
• RLEG heat exchanger takes hot humid air from the drying process and uses this to heat process water, resulting in an energy-efficient process
• NEW circulation air fan, with a new FC-type impeller featuring an adjustable pitch angle, results in increased production capacity
• Broke removal solutions, such as an internal broke nip combined with tailor-made hand tools, enable quick and simple broke removal – and reduce downtime significantly if there is a web break.

Upgrades, rebuilds and services for pulp finishing (cutter/layboy and pulp baling)

• Slitter and cross-cutter knife with the new hard-facing technology provides higher wear resistance and better cutting quality
• Modification of cutter (finger and lift table) to hydraulic design gives failsafe and maintenance-free operation
• Post-edge trim adjusts oversized final sheet width and eliminates subsequent problems in the baling line
• Top tape upgrade corrects undesirable sheet flutter and stabilizes production, thus increasing production speed
• Improved hydraulic system at the bale press leads to a much shorter press cycle and increases production capacity
• Rebuild of Duowrap provides a faster and more accurate system
• Upgrade of end fold unit has a positive effect on the subsequent bale handling sequence and storage stacking
• Improvements for chain conveyors, bale tracking systems, limit switches decrease maintenance costs and unplanned shutdowns

Plant surveys; upgrade studies, and pilot plant trials

Service for a pulp drying plant survey typically includes a survey report and a proposal for a plant upgrade with budgetary estimates for the suggested rebuild measures.

Usually this service is based on three steps:

• Survey at mill
• Lab tests and survey report
• Budget proposal

The survey at the mill usually covers the following main process areas:

• Wet end including approach system, screening, cleaning, pulp dewatering
• Pulp drying
• Pulp finishing including cutter/layboy and pulp baling

Lab tests and survey report

Pulp samples are taken at the plant and are tested and further analyzed at ANDRITZ laboratories in Graz, Austria and Växjö, Sweden. The results of the mill survey and the lab tests are concluded in a final survey report which will be sent to the customer with recommendations for improvements. The survey report will be transmitted within an agreed upon time frame after completion of the survey.

Budget proposal

As required for the upgrade study, ANDRITZ will provide a budget proposal for the required modifications and rebuild measures with indication of the shutdown period for the plant upgrade.

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