Ce manuel assemble les renseignements existants sur la technologie du séchage des placages. Il est destiné aux opérateurs de séchoirs, aux contremaîtres et aux gérants. Il est conçu spécialement pour les usines de l'Est du Canada mais contient des références aux essences et aux méthodes de séchage couramment utilisées dans l'Ouest canadien. Les sujets suivants sont abordés dans ce manuel: humidité du placage, hydromètres, processus de séchage, types de séchoirs, opération et entretien des séchoirs, incendies, pollution et défauts des placages causés par le séchage.
Correction factors are provided for the Delmhorst resistance-type moisture meters equipped with 2-pin insulated electrodes. These factors allow the operator to adjust the meter reading for a wood temperature range of -40 degree centigrade to 50 degree centigrade. Factors are provided for 12 softwood species and 14 hardwood species.
It is well known that the forest biomass used to supply the energy sector must meet the quality standards of energy production facilities. These standards relate to moisture content (TH), particle size, fine particle content and degree of contamination. Customers have their own requirements, which sometimes differ from each other, and the supplier must meet them. The development of a payment system based on quality criteria and energy value seems obvious, but not everything is the obvious, but it is not that simple.
C’est connu: la biomasse forestière utilisée pour approvisionner le secteur de l’énergie doit répondre aux standards de qualité propres aux installations productrices d’énergie. Ces standards concernent la teneur en humidité (TH), la grosseur des particules, la teneur en particules fines et le degré de contamination. Les clients ont leurs exigences, qui diffèrent parfois les uns des autres, et le fournisseur doit les respecter. Le développement d’un système de paiement basé sur les critères de qualité et la valeur énergétique apparait comme une évidence, mais tout n’est pas si simple.
A total of 48 peeler blocks and 256 mini-billets were sampled from mills to investigate the effects of yard storage time, and artificial yard drying and sprinkling on residual moisture contents (MCs) and veneer quality. MC in fresh and stored log inventories varied greatly across mills according to geographic location of their wood supply zones, bark damage and loss, and storage time and conditions. The main findings were as follows:
1. DF logs supplied by three BC mills from the Cariboo, Thompson Okanagan, or Kootenay regions were highly variable in wood MC.
2. Winter-cut DF logs with high sapwood MC stored had good bark retention and high moisture retention over 6 and 9 winter-spring months. No effects on veneer peeling roughness from longer-term winter storage up to 9 months.
3. Summer-cut logs had little or no residual bark, or the bark slipped off very easily during debarking. Exposed, bark-free summer-cut logs can dry and crack on edges and ends very quickly, within a few weeks.
4. A marked decline in veneer quality with piling time in Summer for spruce and DF, suggesting an optimum window of processing of such exposed logs of about two weeks. Veneer quality and recovery suffered markedly once the logs had fully air dried mainly because of edge splits creating natural fragmentation of the ribbon.
5. Mills receiving dry-zone logs with much lower MC have a very limited storage window, especially over winter. As little as 2-3 weeks if bark is damaged or missing.
6. Veneer quality could not be definitively tied to log residual MC. Under the controlled laboratory conditions used here it was observed that peeling quality could still be good at low sapwood MC (35-40%) and or very high (MC>100%). Whether this is still the case in mill production is unknown.
7. Logs must never be allowed to fall below FSP and develop edge-checks or deep end checks.
8. Wax emulsion end sealants were effective at hampering drying and end checking on high MC logs, but not effective on low MC logs.
9. Sprinkling retained log freshness and peel quality in high MC DF for several months and prevented log drying and end splitting as well as inner log staining. Ends absorbed considerable extra moisture. Some variability in peel quality was noted.
10. The prototype EM1000 Ground Penetrating Radar could only be reliably used in log edge mode in DF. The unit would also require re-calibration for the very high sapwood MC in spruce and wet-zone DF logs.