Evaluation of novel drum chipper technology: pilot-scale production of short wood chips

Abstract

Impregnation of wood chips with acidic pulping liquors is improved when using short chip lengths. If the average wood chip length is too short, conventional chipping technology will generate excess small material, such as pin chips and fines. The possibility of using newly developed drum chipping technology to produce shortlength wood chips was evaluated with a pilot drum chipper operating at different drum velocities and in-feed angles. With a drum velocity of 30 m/s, the average wood chip lengths and the combined fractions of pin chips and fines were 24 mm and 3.3%, 22 mm and 4.2%, and 17 mm and 8.5%. The highest fractions of total accept chips (large and small accepts), 89% to 90% without screening, were observed for drum velocities of 30–34 m/s and average wood chips lengths of 21–22 mm. The results indicate the potential of drum chipping technology for producing short wood chips with relatively high fractions of accept chips and tolerable fractions of pin chips and fines.

Evaluation of chipping and impregnation of Scots pine heartwood with sulfite cooking liquor

“…Using the ScanChip analyzer the average thickness was 5.1 mm for heartwood and 4.2 mm for sapwood. The difference between the two methods depends on how the average thickness is determined, and the same trend (lower values for the ScanChip analyzer than for the SCAN standard method) has been observed also in earlier studies [9,17]. The trend that wood chips from heartwood were thicker than wood chips from sapwood was also supported by the thickness distribution data (Fig.…”

“…The heartwood and the sapwood pieces were chipped separately using a pilot-scale drum chipper of novel design. The pilot-scale drum chipper, which was constructed by Multi Channel Sweden AB (Bredbyn, Sweden), had a drum with a diameter of 3 m and a width of 20 cm, and was equipped with 16 knives [9]. The knife angles (α = 2.2° and ε' = 30°, [9]) and the T dimension were adjusted to be suitable for production of wood chips with an average length of around 25 mm.…”

“…To get smooth operation and high pulp yields, it is important to have a homogenous feedstock with large fractions of accept chips and small fractions of fines and pin chips. A new wood-chipping technology based on drum chippers has already shown promising results with regard to producing wood chips for the sulfite process [9].…”

“…The aim of this study was to investigate preparation of wood chips from Scots pine and utilization of wood chips originating from heartwood in an acidic sulfite process. The strategy used to obtain heartwood wood chips was to separate heartwood and sapwood before chipping and utilize the new state-of-the-art drum-chipping technology [9] to process the wood. Both heartwood and sapwood were chipped, but, as there are little or no problems associated with impregnation and cooking of sapwood, only the heartwood wood chips were studied in the subsequent impregnation and cooking experiments.…”

The impact of using different wood qualities and wood species on chips produced using a novel type of pilot drum chipper

“…The wood chips were produced using a pilot drum chipper described in a previous paper (Gard Timmerfors and Jönsson 2019). The evaluation of the wood chips was performed using SCAN-CM, a series of manual industrial standard methods (Scandinavian Pulp, Paper and Board Testing Committee's series of test methods for chemical and mechanical pulps and wood chips), and using a ScanChip analyzer.…”