Manipulating Chain Type and Flail Drum Speed for Better Fibre Recovery in Chain-Flail Delimber-Debarker-Chipper Operations

Abstract

A chain-flail delimber-debarker-chipper (CFDDC) was adapted for treating smaller trees than normal by replacing the standard flails with lighter ones, and by reducing flail drum rotation speed. The machine produced 16 full containers (24 t each) for the standard configuration and 24 full containers for the innovative one. For each container the researchers measured: original tree mass, chip mass, time consumption and fuel use. Results indicated that the innovative setting accrued a 12% improvement on fiber recovery compared with the standard setting (control). At the same time, productivity increased by 20% and fuel consumption was reduced by 30%. Product quality was largely unaffected, with bark content remaining below the 1% threshold specification. If at all, product quality was improved through the reduction of fine particles, possibly derived from less diffused fraying. These results have triggered the real scale adoption of the new setting by contractors who participated in the study. The success of the innovative treatment is likely explained by its better alignment with the weaker structure of small trees from low-yielding stands.

Russian sawmill modernization (a case study). Part 1: optimizing processes of low-grade timber debarking and wood chipping

“…This high performance system compares favourably with other debarking machines (Spinelli and de Arruda Moura 2019), has a simpler design, and consumes less energy. Such a technological solution will allow boosting the efficiency of debarking.…”

First trial of a prototype chainflail delimber for the European short rotation poplar plantations

“…While the machine in this study was used for delimbing only, it can certainly be set for integrated delimbing and debarking, if the need arises. To that end, one could simply extend the permanence of the stems under the ail, change the ail rotation speed or replace the chains with a more aggressive type (Spinelli et al 2020a). However, such adjustments would likely decrease productivity and log yield, so they should be pursued only if necessary (Hartsough et al 2000).…”

“…Their ability to buffer tree size effects is best demonstrated by the failure of all CFDD productivity studies to estimate a strong relationship between productivity and stem volume, given that the strongest models yet produced have a coe cient of determination R 2 around 0.30 (McEwan et al 2019, Hartsough et al 2002, Ghaffariyan et al 2013. Furthermore, the delimbing principle adopted by chain ail machines does not rely on a knife sliding along the stem surface and its e ciency is less dependent on stem form (Labelle et al 2016), so that a chain ail can turn into a usable product even those tree portions that are too small or too malformed for recovering with any other processing systems (Buggie 1997, Spinelli et al 2020a). For that reason, CFDD technology is especially popular when dealing with small trees, as normally obtained from short-rotation industrial plantations designed to produce high-quality ber for manufacturing pulpwood or other high-end commodities, rather than low-grade biomass (Spinelli and Hartsough 2006).…”

First trial of a prototype chain-flail delimber for the European short rotation poplar plantations

“…While the machine in this study was used for delimbing only, it can certainly be set for integrated delimbing and debarking, if the need arises. To that end, one could simply extend the permanence of the stems under the flail, change the flail rotation speed or replace the chains with a more aggressive type (Spinelli et al 2020a). However, such adjustments would likely decrease productivity and log yield, so they should be pursued only if necessary (Hartsough et al 2000).…”

“…Their ability to buffer tree size effects is best demonstrated by the failure of all CFDD productivity studies to estimate a strong relationship between productivity and stem volume, given that the strongest models yet produced have a coefficient of determination R 2 around 0.30 (McEwan et al 2019;Hartsough et al 2002;Ghaffariyan et al 2013). Furthermore, the delimbing principle adopted Communicated by: Eric R. Labelle by chainflail machines does not rely on a knife sliding along the stem surface and its efficiency is less dependent on stem form (Labelle et al 2016), so that a chainflail can turn into a usable product even those tree portions that are too small or too malformed for recovering with any other processing systems (Buggie 1991, Spinelli et al 2020a. For that reason, CFDD technology is especially popular when dealing with small trees, as normally obtained from short-rotation industrial plantations designed to produce high-quality fiber for manufacturing pulpwood or other high-end commodities, rather than low-grade biomass (Spinelli and Hartsough 2006).…”