Classifying – separating – and assorting solids – Sorting special items – and certain methods and apparatus for... – Condition responsive means controls separating means
Reexamination Certificate
1998-09-30
2001-01-16
Nguyen, Tuan N. (Department: 3653)
Classifying, separating, and assorting solids
Sorting special items, and certain methods and apparatus for...
Condition responsive means controls separating means
C209S938000, C250S339100, C250S341800
Reexamination Certificate
active
06175092
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to classification of batches of wood chips or the like, and more particularly to a method and apparatus for classifying batches of wood chips according to light reflection characteristics.
BACKGROUND OF THE INVENTION
In the past years, significant efforts have been devoted to develop processes for the production of pulp and paper products aimed at reducing manufacturing costs while improving product quality. Quality control of the raw materials entering in the production of pulp and paper products, particularly regarding wood chips used, has been identified as a key factor in process optimization.
A known approach to control quality of wood chips consists in treating wood chips at the manufacturing stage. Such an approach is employed in the wood chips manufacturing method disclosed in U.S. Pat. No. 5,577,671 issued on Nov. 26, 1996 to Seppanen et al, which method consists of separating from ground whole-tree chips, bark and cellulose wood chips through a series of separation stages including pneumatic separation, vibration segregation with sieve and color difference sorting. The resulting low bark, pale wood chips can be then processed using a minimum quantity of bleaching agent. Although processing cost can be minimized accordingly, added manufacturing cost due to bark separation step may still maintain overall production cost high.
Another known approach consists of sorting trees according to their types prior to wood chips manufacturing, to produce corresponding batches of wood chips presenting desired characteristics associated with these types. Typically, hardwood trees such as poplar, birch and maple are known to generally produce pale wood chips while conifers such as pine, fir and spruce are known to generally yield darker wood chips. In practice, wood chips batches can either be produced from trees of a same type or from a blend of wood chips made from trees of plural types, preferably of a common category, i.e., hardwood trees or conifers, to seek wood chips uniformity. However, chips characteristics basically depending on initial bark content of wood chips used, knowledge of the types of wood chips for a given batch does not necessarily give a reliable indication of the chips quality.
SUMMARY OF INVENTION
It is therefore an object of the present invention to provide a method and apparatus for classifying batches of wood chips or the like according to optical characteristics representative of chips quality or grade.
According to the above object, from a broad aspect of the present invention, there is provided a method for classifying batches of wood chips or the like according to light reflection characteristics, comprising the steps of: a) directing light onto superficial wood chips included in at least a representative portion of an inspected one of said wood chips batches, said superficial wood chips presenting light reflection characteristics being substantially representative of the wood chips of the inspected batch; b) sensing light reflected on the superficial wood chips included in said batch portion to produce electrical signals representing reflection intensity values for the superficial wood chips included in said batch portion; c) deriving from the electrical signals global reflection intensity data characterizing the inspected batch of wood chips; and e) comparing the global reflection intensity data with reference reflection intensity data to provide classification of said inspected batch of wood chips according its light reflection characteristics.
According to a further broad aspect of the present invention, the method comprises the steps of: a) directing light orto superficial wood chips included in at least a representative portion of an inspected one of said wood chips batches, said superficial wood chips presenting light reflection characteristics being substantially representative of the wood chips of the inspected batch; b)sensing light reflected on the superficial wood chips included in said batch portion to produce first electrical signals representing reflection intensity values for the superficial wood chips included in said batch portion; c) measuring moisture of said superficial wood chips to produce second electrical signals representing average moisture values for the superficial wood chips included in said batch portion; d) deriving from said first and second electrical signals global reflection intensity data characterizing the inspected batch of wood chips, said global reflection intensity data being normalized according to a predetermined moisture reference value; and e) comparing the global reflection intensity data with reference reflection intensity data to provide classification of said inspected batch of wood chips according its light reflection characteristics.
According to a still further broad aspect of the present invention, there is provided an apparatus for classifying batches of wood chips or the like according to light reflection characteristics. The apparatus comprises illumination means for directing light onto superficial wood chips included in at least a representative portion of an inspected one of said wood chips batches, said superficial wood chips presenting light reflection characteristics being substantially representative of the wood chips of the inspected batch. The apparatus further comprises image creating means for sensing light reflected on the superficial wood chips included in said batch portion to produce image electrical signals representing reflection intensity values for the wood chips included in said batch portion. The apparatus further comprises means for deriving from the image electrical signals global reflection intensity data for the inspected batch; and means for comparing the global reflection intensity data with reference reflection intensity data to provide classification of said inspected batch of wood chips according its light reflection characteristics.
According to a still further broad aspect of the present invention, the apparatus comprises illumination means for directing light onto superficial wood chips included in at least a representative portion of an inspected one of said wood chips batches, said superficial wood chips presenting light reflection characteristics being substantially representative of the wood chips of the inspected batch, image creating means for sensing light reflected on the superficial wood chips included in said batch portion to produce first electrical signals representing reflection intensity values for the wood chips included in said batch portion, and moisture detector means for producing second electrical signals representing average moisture values for the superficial wood chips included in said batch portion. The apparatus further comprises means for deriving from said first and second electrical signals global reflection intensity data for the inspected batch, said global reflection intensity data being normalized according to a predetermined moisture reference value and means for comparing the global reflection intensity data with reference reflection intensity data to provide classification of said inspected batch of wood chips according its light reflection characteristics.
According to a preferred embodiment of the present invention, a method and apparatus for classifying batches of wood chips or the like according to optical characteristics is provided, which allow optimal use of darker wood chips in pulp and paper processes. Although hardwood wood chips generally require more bleaching agent when being processed, their cellulose fibers may exhibit better physical characteristics than fibers found in conifers for the purpose of producing products presenting particular structural characteristics. Therefore, mixing a relatively small batch of such darker wood chips with a large batch of pale wood chips can produce a blend presenting the quality required for optimal processing, provided the characteristics of the darker wood chips batch have been accurately determined, to adjust parameters of
Binette Sylvain
B{acute over (e)}dard Pierre
Couturier Jean-Pierre
Labb{acute over (e)} Jacques
Centre de Recherche Industrielle du Qu{acute over (e)}bec
Nguyen Tuan N.
Swabey Ogilvy Renault
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