| 摘要 |
According to the method, wood chips (16) are introduced into a sheath (10) containing two parallel, meshed screws (12, 14), their threads (12B, 14B) having, in succession, in the downstream direction (S), at least one upstream series and a downstream series of sections (SM, SI, SA) each series of sections comprising a driving zone (SME, SIE, SAE) in which the chips are driven downstream and a braking zone (SMF, SIF, SAF) through which the chips are forced, the chips thus being driven through the sheath (10) while being slowed down in the braking zones and while being converted into fibres (24). The length of stay of the chips in the sheath (10) is between 15 and 80 seconds and the pressure upstream of the braking zone (SMF) of the upstream series (SM) is substantially equal to 90 bar, such that a temperature of between 120oC and 150oC is reached in the sheath (10) without an external supply of heat. |
