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.
Highlights
Chain-flail delimber-debarker-chippers (CFDDC) are large industrial machines, designed for producing bark-free chips from whole trees in one single pass (Sessions and Kellogg 1994)
A partial explanation could be obtained from the fact that the two studies represented the two opposite extremes of chain-flail delimber-debarker-chipper (CFDDC) operations: the present study described the case of a failed plantation, offering unfavourable work conditions that resulted in a relatively low net productivity level; in contrast, the study by Spinelli et al (2018) represented a best case scenario, where tightly managed operations were deployed on high-yielding plantations and achieved some of the highest productivity levels yet recorded in the existing literature
Productivity is increased by 20% and fuel consumption is lowered by 30%
Summary
Chain-flail delimber-debarker-chippers (CFDDC) are large industrial machines, designed for producing bark-free chips from whole trees in one single pass (Sessions and Kellogg 1994) To this purpose, CFDDCs integrate two functional elements: a chain-flail delimber-debarker and a disc chipper (Thompson and Sturos 1991). CFDDCs integrate two functional elements: a chain-flail delimber-debarker and a disc chipper (Thompson and Sturos 1991) The former knocks off branches and bark from whole trees by using hardened chain links mounted on fast-rotating drums, while the latter turns bark-free stem wood into clean pulp chips (McEwan et al 2019). The high productivity of CFDDC units has been documented by many studies over time, including a very recent long-term experiment based on 60,000 individual load records (Spinelli and De Arruda Moura 2019). The low explanatory power of CFDDC productivity functions is the best witness to the capacity of these machines to compensate for the effect of small tree size through mass-handling: as tree size gets smaller, more trees are gathered in a load, in order to stabilize throughflow
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