Higher-level Control of Mercer Rosenthal Debarking Drum Optimizes Wood Efficiency

As a wood products manufacturer, Mercer continuously aims to improve process efficiencies in our operations for greater, sustainable use of the raw material wood. Due to the pulping process at Mercer Rosenthal, the wood material used also creates bioextractives, like tall oil, and green energy. The chipping plant at Mercer Rosenthal processes about 650,000 cubic meters of industrial roundwood into chips annually. Most of the incoming roundwood is delivered by truck, but also by rail. 

To continuously improve resource efficiency, a system was installed to reduce wood losses during the debarking process. This system was installed during the mill’s annual maintenance shutdown in September 2022 by a Finnish supplier. The new system controls the debarking process so that as little bark as necessary is removed from the log.

The system consists of the following components (see figure below):

1. Feedsmart Scanner

One measuring system resides in each of the infeed lines from the log yard and the log wagon line. These scanners are responsible for the detection of the logs in the infeed to the chipper and monitor the overall quantity, quality and dimensions of the logs.

2. Fillsmart Scanner

This system utilizes a laser mounted at the end of the debarking drum for accurate level measurement, determining how many logs are currently in the drum.

3. Barksmart + Logsmart Scanner

This system is mounted in front of the chipper and determines the amount of bark on the logs. It also checks the quantity and dimension of the logs before they are processed into chips.

4. Profismart Scanner

To determine the wood loss, this system is mounted on the bark belt and measures the wood content remaining in the cut bark.

5. Woodsmart Software

This is the control software for optimizing the debarking process to reduce wood losses. Various input signals from the previous scanners are processed to make necessary adjustments. The controls of the debarking drum move the sliding gate at the drum outlet and manage the overall speed accordingly. These changes achieve the desired target values for the specific logs in the drum. Not only has this minimized wood losses, but debarks the logs to continue meeting the quality requirements for the mill’s pulp production.

Since the start-up in October 2022, the system has been running steadily. The following graph shows that wood losses have been significantly reduced since then – from 10% to less than 2%! 

The valuable resource wood is now better conserved thanks to a higher proportion of it being used as raw material for pulp and other wood bioproducts. In addition to reducing waste, the more efficient use of the resource also results in an economic advantage, as it reduces raw material costs for roundwood due to the lesser amounts needed from the forest to produce the same amount of pulp. Thanks to an optimized debarking process, Mercer Rosenthal is significantly more efficient and sustainable in our operations.