WO2002024350A1

WO2002024350A1 - Apparatus for levelling out fluctuation in a material flow supplied from a bucket feeder

Info

Publication number: WO2002024350A1
Application number: PCT/FI2001/000814
Authority: WO
Inventors: Pekka Kokko
Original assignee: Andritz Oy
Current assignee: Andritz Oy
Priority date: 2000-09-20
Filing date: 2001-09-19
Publication date: 2002-03-28
Anticipated expiration: 2003-03-20
Also published as: AU2001289968A1; FI110173B; FI20002072A0; FI20002072L

Abstract

The invention relates to an apparatus for levelling out intermittent fluctuation caused by design and mechanics of a bucket feeder (6) in a material flow (1) supplied from the bucket feeder (6) onto an inclined sliding plane (2) and containing wood chips (11, 12), sawdust (13) or bark or combinations thereof. The material flow (1) discharging from the bucket feeder (6) has its passage adapted to be affected by providing the same with a number of tumblers (15, 16) applying an impact on the material flow (1) from above or below, or from both sides of the same.

Description

Apparatus for levelling out fluctuation in a material flow supplied from a bucket feeder

The invention relates to an apparatus for levelling out intermittent fluctuation caused by design and mechanics of a bucket feeder in a material flow supplied from the bucket feeder onto an inclined sliding plane and containing wood chips, sawdust or bark or combinations thereof.

This type of apparatus can be used for example in connection with the appara- tus known from Finnish utility model No. 3899. This prior known apparatus is used for sorting wood chips, involving chips in a variety of sizes and similar, substantially hexahedral pieces having a length and a width, as well as a thickness substantially less than the latter, and possibly fines particles, by means of an impulse action, such that the fines particles form a separate fraction and the chips form two or more fractions according to the thickness thereof, the miscellaneous chips and the fines particles being adapted to be sorted from each other by means of one or more separating walls arranged to comply with various trajectories established by means of the impulse action, said apparatus comprising a feeder for supplying the wood chips onto a sloping support sur- face essentially in a single layer, said support surface being dimensioned for adapting the chips to rest upon the longitudinal/lateral surface thereof and for sliding the same on said longitudinal/lateral surface along said sloping support surface over a slit extending thereacross, said slit being adapted to provide an impulse action therethrough by means of a continuous gas flow on the chips or the fines particles presently in line with the slit. Such prior known apparatus is intended for separating a variety of fractions from a high-rate mass flow of wood chips (volume in hundreds of cubic meters an hour), as determined by thickness of the individual chips. This also enables the separation of higher density stuff, such as scrap, as well as irregularly shaped harmful particles. With regard to a faultless operation of the apparatus, it is important that the wood chips to be processed can be spread evenly in a single layer on a sloping support surface included in the apparatus. The bucket feeder enables the dosage of a material to be supplied by a bucket feeder onto an inclined sliding plane at an averagely constant capacity. However, owing to design and mechanics of the apparatus, the material flow emerging from a bucket feeder displays transient fluctuation, the timing of which coincides with the turning of another bucket into a vacant area above the sliding plane. The number of buckets included in a bucket feeder is naturally limited, and even the largest material particle to be handled must fit in the bucket.

It is an object of the invention to eliminate or at least alleviate this drawback, and to provide an apparatus whereby the material to be processed can be delivered as evenly as possible onto a sliding surface and in such a way that the material particles do not lie on top of each other on the sliding plane, but essentially in a single layer.

According to the invention, this object is accomplished in such way that, and an apparatus of the invention is characterized in that that the material flow discharging from the bucket feeder has its passage adapted to be affected by providing the same with a number of tumblers applying an impact on the mate- rial flow from above or below, or from both sides of the same.

In a preferred embodiment of the invention, the arrangement is such that the tumbler comprises a baffle mounted on the inclined sliding plane. The baffle comprises preferably a plate extending lengthwise of the material flow and projecting from the sliding plane. The baffle spreads the material flow in a lateral direction of the sliding plane.

In another preferred embodiment of the invention, the arrangement is such that the tumbler comprises an elastically compliant flap mounted above the material flow discharging from the bucket feeder onto the sliding plane.

The flap is preferably dimensioned for restricting the passage of peak points appearing in the material flow by cutting off the peaks. The flap comprises preferably a rubber skirt extending across the width of the sliding plane. The invention will now be described in more detail with reference to the accompanying drawings, in which:

Fig. 1 shows a bucket feeder in a diagrammatic section, fitted in an ap- paratus for sorting wood chips in separate fractions.

Fig. 2 shows the bucket feeder of fig. 1 in a larger scale and fitted with an apparatus of the invention.

Fig. 1 shows schematically an apparatus for sorting wood chips 1 in separate fractions. Fines particles 13, possibly contained in the wood chips 1 , are sorted out to form a separate fraction and individual chips 11 , 12 are determined by the thickness thereof as excess thickness chips 11 (reject) and accepted chips 12 (accept).

The apparatus comprises a feeder 6 for supplying the wood chips 1 onto a sloping support surface 2 for a substantially single layer. The individual chips 11 , 12 settle in a natural way on the support surface 2 to rest upon the largest surface thereof, i.e. in the case of wood chips, upon the longitudinal/lateral surface thereof.

The support surface 2 is a solid, flat, and durable level surface, which forms a steeply sloping slide surface for the wood chips 1 to be sorted.

The wood chips 1 emerging from the feeder 6 are first adapted to slide down the sloping support surface 2 and then over a slit 3 arranged across the support surface, said slit being adapted to deliver an impulse action 4 directed away from said support surface 2 and applied to one or more chips 11, 12 or fines particles 13 presently in line with the slit. The impulse action is adapted to be produced by means of a gas flow 4, preferably an air flow. The impulse action 4 may have a direction which is perpendicular to the support surface 2, or also at an oblique angle relative to the support surface 2. The air flow is generated by a fan 7. In order to secure uniformity of the impulse action 4, a nozzle chamber 8 is arranged between the fan 7 and the slit 3.

The varying thickness chips 11 , 12 and the eventual fines particles 13 are adapted to be separated from each other in compliance with various trajectories defined by the impulse action 4 for the particles to be sorted.

The fines particles 13, which are smaller in size than the width of the slit 3, adopt a maximum deviation of velocity and, thus, are adapted to be diverted by the action of a baffle/guide plate 14 in a separate fraction into a chute 15.

The individual chips 11 , 12, which are substantially larger in size than the width of the slit 3 and, thus, heavier than said fines particles 13, adopt a deviation of velocity substantially less than that adopted by the fines particles 13 when present in line with the slit 3. A pressure-generated impulse sends the individual chips 11 , 12 flying in different trajectories defined by a chip thickness, and the flow of chips is divided in separate fractions by means of a separating wall 5. The averagely minimum thickness chips 12 fly over the separating wall 5 and are further guided to a discharge screw 10. Respectively, the averagely maximum thickness chips fly a shorter distance and fall into a feeder 6' present between the separating wall 5 and the slit 3.

In the illustrated example, the averagely maximum thickness chips 11 received in the feeder 6' are reprocessed in a lower second apparatus, whereby a fraction thereof (the averagely lightest fraction) is guided over a separating wall 5' further onto the discharge screw 10, and another fraction (the averagely heaviest fraction) falls into a chute fitted between the separating wall 5' and the slit 3 and provided with a discharge screw 9.

Processing of the wood chips 1 is all in all adapted to take place in a dustproof treatment chamber 17. The discharge of air from the chamber 17 is arranged through an opening represented by reference numeral 34. Fig. 2 depicts a detail of the feeder 6, particularly a bucket feeder, applied in conjunction with the apparatus of fig. 1. However, it is obvious that the presently discussed bucket feeder 6 is not intended solely for the apparatus shown in fig. 1 , but is useful elsewhere, as well.

The bucket feeder enables the dosage of a material to be supplied by a bucket feeder onto the inclined sliding plane 2 at an averagely constant capacity. However, owing to design and mechanics of the apparatus, the material flow emerging from a bucket feeder displays transient fluctuation.

In order to overcome this drawback, the material flow 1 discharging from the bucket feeder 6 has its passage adapted to be affected by a number of tumblers 15, 16 arranged in the material flow 1.

In the exemplary embodiment of fig. 2, the tumbler 15 comprises a baffle mounted on the sliding plane 2. The baffle 15 comprises preferably a plate extending lengthwise of the material flow 1 , projecting from the sliding plane 2, and increasing in height in advancing direction of the material flow 1. The tumbler 15 can also be constituted for example by a dowel projecting from the sliding plane 2. The tumblers 15 are preferably mounted at even spaces across the entire width of the sliding plane 2.

It is also possible to arrange a tumbler above the material flow 1 , but in this case it must be elastically compliant. In fig. 2, such a tumbler is represented by reference numeral 16, and it is constituted by a rubber skirt extending across the width of the sliding plane 2, which is dimensioned so as to restrict the passage of peak points appearing in the material flow 1 , by cutting off the peaks.

Claims

1. An apparatus for levelling out intermittent fluctuation caused by design and mechanics of a bucket feeder (6) in a material flow (1) supplied from the bucket feeder (6) onto an inclined sliding plane (2) and containing wood chips (11, 12), sawdust (13) or bark or combinations thereof, characterized in that the material flow (1) discharging from the bucket feeder (6) has its passage adapted to be affected by providing the same with a number of tumblers (15, 16) applying an impact on the material flow (1) from above or below, or from both sides of the same, said tumblers (15) working from below comprising a number of brackets, projecting from the inclined sliding plane (2) and mounted in a mutually spaced relationship across the entire width of the sliding plane (2) and spreading the material flow advancing along the sliding plane (2) in a lateral direction of the sliding plane (2) as the material flow collides with said tumblers (15), and said tumbler (16) working from above comprising an elastically compliant flap mounted above the material flow (1 ) discharging from the bucket feeder (6) onto the sliding plane (2).

2. An apparatus as set forth in claim 1 , characterized in that the tumbler comprises a baffle (15) extending lengthwise of the material flow (1) and projecting from the sliding plane (2).

3. An apparatus as set forth in claim 2, characterized in that the baffle (15) increases in height in advancing direction of the material flow (1).

4. An apparatus as set forth in claim 1 , characterized in that the flap (16) is dimensioned for restricting the passage of peak points appearing in the material flow (1) by cutting off the peaks.

5. An apparatus as set forth in claim 1, characterized in that the flap (16) comprises a rubber skirt extending across the width of the sliding plane (2).