[0001] The invention relates to a method and apparatus for comminuting for combustion or
gasification, suitably in conjunction with a stoker, of wood or cellulose material,
for example, such as is precompressed, or board- or strip-like per se, such as waste
. or offcuts from wood, chip or fiber material, logging debris or household waste
etc.
[0002] Stoking equipment is known for feeding steam boilers with wood chips, for example,
wherein a screw is used to feed the chips from a hopper and into the combustion chamber
of the boiler. Equipment is also known, in which a moving grate feeds fuel from a
fuel hopper to a water pipe boiler, for example.
[0003] However, for board-like or strip-like wood or cellulose material or logging debris
or household waste, which by means of precompression can be spread out and precompressed,
there is no suitable equipment for.rational recovery of the heat from such waste material.
[0004] In actual fact, about 2% of the total chip board production results in waste which
is unusable for building purposes and which is at present dumped or otherwise got
rid of.
[0005] Neither can logging debris or household waste be utilized for the generation of heat
in a rational way at present.
[0006] The present invention intends to remedy this deficiency, and consists primarily of
a method of comminuting the material in question, wherein it is first advanced under
a feed and/or spreading or precompressing means (roll or the like) and is thereafter
taken in between comminuting rolls, which can be made up from rings, and arranged
in pairs, suitably in direct conjunction with the combustion or gasification location,
where each such roll is provided with projections and depressions formed wavily, trapezoidally,
pyramidally or conically, and where the rolls in each pair are adapted in relation
to each other such that the projections of one roll partly engage in the depressions
of the other roll, the rolls being disposed at a distance from each other such that
the substantially board-shaped material is gripped between the rolls, and during its
passage therebetween is bent between the projections and depressions of the rolls
until rupture occurs by exceeding the ultimate elongation, shearing and/or compression
strength of the material, which is thus directly comminuted into pieces suitable for
combustion or gasification.
[0007] The invention also relates to a special comminuting apnaratus or machine for feeding
a combustion or gasification apparatus (e.g. stoker equipment) with wood or cellulose
material which is precompacted or.board- or strip-alike per se, for carrying out the
said method, the .invention substantially consisting of the machine containing at
least one roll pair for receiving the material, where each roll is provided with mutually
alternating projections and depressions around its periphery, corresponding to depressions
and projections, respectively, on the other roll in each such pair, which is driven
with the same peripheral velocity for both rolls, said projections and depressions
having at least along the circumference, but suitably also axially, a form which is
corrugated, trapezoidal, pyramidal or conical, the projections on one roll engaging
in the depressions corresponding thereto on the other roll, the spacing between the
rolls being adjustable such that the sum of a radius to the crest of a projection
on one roll and the radius to the bottom of the complementary depression on the other
roll is less than the distance between the central axes of the rolls.
[0008] The invention otherwise relates to the characterizing features more closely disclosed
by subclaims 2-5 and 7-13.
[0009] Since, in accordance with the invention, a fuel material is used which is board-
or strip-like, or the fuel material is pretreated so that a precompacted layer thereof
is supplied to the comminuting rolls, the advantages are gained that the comminuting
apparatus will funcion such that the material advances itself, that it will be conservative
of energy and can be driven with a very small motor, that it will run comparatively
quietly, that it discharges a uniform lump size suitable for combustion, and that
the apparatus will be robust and easily manufactured, by enabling the roll cylinders
or rings themselves to be cast iron or forged and thus not require the observation
of any accurate tolerances. Finally, the apparatus looks after itself automatically
and requires very litte inspection and service. Its capacity can also be easily varied
by regulating the speed of the rolls, and the lump size can be regulated by adjusting
the distance between the rolls as already mentioned.
[0010] The invention will now be described in detail while referring to the appended drawings,
where.
Fig. 1 schematically illustrates a stoker plant with a comminuting machine in accordance
with the invention, all of which is seen from one side,
Fig. la is a side view of a suitable precompactor with a roll, and
Fig. 2 and 3 a suitable embodiment of a roll ring in accordance with the invention,
seen from one side and in cross section, respectively,
Fig. 4 is an embodiment with axial corrugations on a roll arranged by mounting a plurality
of roll rings in accordance with Figs. 2 and 3 side by side on a tube, and
Fig. 5 illustrates two coacting rolls or roll rings seen from one side, but with a
more acute shape of the projections and depressions than that in Figs. 2 and 3.
[0011] The comminuting machine in accordance with the invention, illustrated together with
a stoker plant in Fig. 1, comprises a pair of comminuting rolls 4, 5 mounted rotatably
and movable in

other about shafts 9 and 10 on a frame 16. In the illustrated embodiment example,
the frame 16 is placed in immediate comiunchich to a feed track 11 in a stoker plant
with a combustion chamber 3 arranged in a boiler. One roll 5 is mounted on a fixed
shaft 10, while the other roll is mounted on a shaft 9, yleldingly suspended in glide
blocks 17 arranged at either end of the shaft 9, said blocks supporting the bearings
of the shaft 9 with the help of springs 13, and via a piston rod 19 can apply pressure
to a piston in a hydraulic cylinder 12. The hydraulic cylinder 12 is connected via
a pipe 13 to a pressure accumulator and a bleed valve, neither of which is shown on
the drawing. In this way, an incompressible disturbing body which could come between
the rolls is caused to unload the hydraulic pressure so that the rolls are moved apart
and the body can be removed. The material which is supplied to the comminuting machine
in Fig. 1 is conceived to consist of wooden chipboard 1, which is first inserted under
a feed roll 2, mounted in a glide block 21by means of a shaft 20. The block in turn
glides upwards and downwards in a frame 22, under the effect of the spring 23, and
a screw actuated by a wheel 24, can be caused to make the roll 2 press harder or less
hard on a substructure 25, which is suspended in the frames 16 and 22, and on which
substructure the chipboard 1 is advanced. As spon as the forward edge of the chipboard
has advanced to the peripheries of the rolls 4 and 5 with their projections 6 and
depressions 7, the board 1 is drawn in between the rolls as a result of these being
adjusted at a certain spacing from each other, corresponding to the thickness of the
chipboard 1. The comminuting machine's rolls 4 and 5 are suitably driven at the same
peripheral velocity by spur gears via a reduction gear from a small power source,
suitably an electric motor, which is not shown on the drawing. The power requirement
for this drive is insignificant. The spacing between the rolls is selected so that
the material fed in, in this case the chipboard 1, is easily drawn in between the
rolls. On the discharge side of the rolls, pieces or lumps 8 of a suitable size for
combustion or gasification will be fed to the stoker feed track 11. Breaking up of
the board 1 occurs by the projections 6 and depressions 7 being formed and the distance
between the rolls 4 and 5 selected such that the board 1 is bent so much between the
projections 6 and depressions 7 that the ultimate elongation, shearing and/or compression
strength of the material is.exceeded.
[0012] Apart from board-like or strip-like wood or cellulose material, precompressed wood
or cellulose material such as waste or rejects of wood, chip or fiber material, logging
debris or household waste etc. can also be comminuted. In this case, as is apparent
from Fig. la, the spreading or precompressing means 2, 21, 23, 22 is provided with
a hopper 26 into which the fuel material, e.g. household waste, can be tipped. In
this case the wheel 24 is screwed down more tightly so that the pressure from the
spring 23 causes the roll 2 to press heavily against the substructure 25. A precompacted
material 1 is thus obtained, which is subsequently fed in between the rolls 4, 5 in
the comminuting machine 4, 5, 17, 16 in the same way as the chipboard 1.
[0013] As is apparent from Fig. 4, the comminuting rolls 4 and 5 can be built up from roll
rings 15 thrust onto a tube 14; said rings being provided with projections 6 and depressions
7. In Fig. 4 seven such rings are conceived as being put together into such a roll.
The rolls are then carried on shafts so that a comminuting machine is formed, of the
kind shown as an example in Fig. 1.
[0014] The rings for the roll illustrated in Fig. 4 are more closely depicted in Fig. 2,
where one such ring is houwn from one side, and in Fig. 3, where it is shown in cross
section along the line A-A in Fig. 2.
[0015] In Fig. 5 there is indicated a more acute form for the projections 6 and depressions
7, which could be conceivable for thinner and more brittle material, both rolls 15
being shown in the starting position close to each other, although in practice they
must be moved apart in correspondence with the thickness of the precompacted material
intended for passing between them.
[0016] The spacing between the rolls 4 and 5 is intended to be controlled in the comminuting
machine illustrated in Fig. 1 by the aid of a hydraulic cylinder 12 with a piston,
supplied with hydraulic fluid at a suitable pressure via the pipe 13. However, it
can also be conceived to allow the adjustment of the relative mutual movement of the
rolls to take place mechanically, e.g. with the aid of vertical screws coacting with
nuts arranged at either end of the shaft 9. The movement of the roll 4 up or down.can
thus be done with the assistance.of an electric motor which drives the vertical screws.
[0017] With hydraulic actuation of the up and down movement of the roll 4, the intended
position of the roll is determined by blocks, against which the roll glide blocks
can be caused to rest. The adjustment of the distance between rolls 4 and 5 can be
controlled conventionally by a thickness sensor, e.g. a photocell, on the upsteam
side of the comminuting machine.
[0018] For breaking up rejected chipboard, it is suitable to make the rolls 4, 5 with a
length of 260 cm, corresponding to the width of the boards produced.
[0019] The adjustment of the roll spacing between a projection crest 6 and the corresponding
depression bottom 7 of the other roll should be between 4 and 40 mm, for corresponding
to prevalent board thicknesses. If the diameter of the rolls at the projection crests
is Dl and the diameter of the rolls at the depression bottoms is D2, with the board
thickness being t and the distance between the centres of the rolls L
A, then the desired distance L
A -

≤ t
s, and thus and thus

[0020] As mentioned, a suitable construction of the rolls 4, 5 is to thrust forged or cast
roll wheels 15 with a thickness of 2 cm and a width of 5-10 cm onto a steel tube 14
with an outside diameter of 40 cm, for example, the wheels being keyed to the tube.
[0021] The roll wheels are provided with projections 6, e.g. in the form of pyramids with
bases of 5 x 5 to 10 x 10 cm and a height of 5 to 10 cm.
[0022] A suitable outside diamter Dl for the roll wheels 15 is from 40 to 120 cm.
[0023] The distance between the pyramids in the peripheral direction is determined by the
fact that the distance between the flanks of the pyramids should be larger than twice
the layer thickness
tS'
[0024] It is also suitable that adjacent wheels are relatively displaced by an amount equal
to half the pitch of the pyramids in the peripheral direction.
[0025] In this mode there is obtained in the board a rectangular or quadratic pressure pattern,
coming from the pyramid apices of two roll wheels with uneven numbers, with a pressure
point from a. pyramid on an intermediate roll wheel with an even number at the intersection
of the diagonals of the rectangle or quadrangle.
[0026] Broken pieces of the board will then be obtained which have an approximately triangular
shape.
[0027] .The driving motor for the rolls can be regulated either in response to the power
requirement for the combustion or gasification plant 3 or in response to the amount
of material which is supplied to the spreading or precompressing means 2, 21, 22.
If the rate of supplying fuel exceeds the power requirement for the combustion or
gasification plant 3, the excessive fuel quantity can be supplied to a buffer store,
not shown on the drawing, placed between the machine 4, 5, 12, 13 and said plant 3.
To facilitate insertion of the compacted fuel material between the rolls 4 and 5,
it is suitable to allow the connecting line of these shafts 9 and 10 to form an obtuse
angle with the input direction of the material.
[0028] An advantage from the point of view of manufacture, maintenance and operation is
that the rolls are formed as cast iron or forged rings keyed to steel tubes. Extremely
simple and cheap fabrication with a very robust construction is thus obtained. Although
the invention has been described in conjunction with a pair of embodiments thereof,
it can be optionally varied and modified within the scope of the following patent
claims.
1. A method of comminuting for combustion or gasification, suitably in conjuction
with a stoker, of wood or cellulose- containing material for example, which is precompressed
or board- or strip-alike per se, such as waste or offcuts from wood, chip or fiber
material, logging debris or household waste, etc., characterized in that the material
(1) in question is first advanced under a feed and/or spreading or precompressing
means (rolls (2) or the like) and is thereafter taken in between comminuting rolls
or rings (4, 5) arranged in pairs, suitably in direct conjuction with the combustion'
or gasification location (3), where each such roll is provided with projections (6)
and'depressions (7) formed wavily, trapezoidally, pyramidally or conically,.and the
rolls (4, 5) in each pair being adapted in relation to each other such that the projections
(6) of one roll (4) partly engage in the depressions (7) of the other roll (5), both
circumferentially and axially, the rolls (4, 5) being disposed at a distance from
each other such that the substantially board-shaped material (1) is gripped between
the rolls (4, 5) and during its passage therebetween is bent between the projections
(6) 'and.depressions (7) of the rolls until rupture occurs by exceeding the ultimate elongation,
shearing and/or compression strength of the material which is directly comminuted,
both longitudially and transversely, into pieces (8), suitable for combustion or gasification.
2.. A method as claimed in claim 1, characterized in that the distance between the
rolls (4, 5) is adjustable and selected such that in a position where a projection
(6) on one roll (4) and a depression (7) on the other roll (5) lies on a line between
the centre lines (9, 10) of both rolls (4, 5), the distance between the crest of the
projection (6) on the one roll (4) and the bottom of the depression (7) on the other
roll (5), measured in the direction of the line, or parallel thereto, is less than
the thickness of the strip- or board-like material (1), whereby the material (1) is
gripped between the rolls (4, 5) and comminuted into suitable lumps or pieces (8).
3. A method as claimed in claim 1 or 2, characterized in that the rotational velocity
of the comminuting rolls (4, 5) is regulated in response to the fuel requirements
of the combustion or gasification plant (3) thus fed.
4. A method as claimed in claim 3, characterized in that as far as feeding material
(1) is available, the comminuting' rolls etc. (4, 5) convey possible feed excess to
a buffer store to one side of the stoker feed track (11).
5. A comminuting apparatus or machine for wood or cellulose material which is precompacted
or board- or strip- shaped per se, specially for supplying a combustion or gasification
apparatus (e.g. a stoker plant) for carrying out the method in accordance with one
or more of claims 1-4, characterized in that it comprises at least one roll pair (4,
5) for receiving the material, where each roll (e.g. 4) is provided about its periphery
with mutually alternating projections (6) and depressions (7) corresponding to depressions
(7) and projections (6), respectively, on the second roll (5) in each such pair, which
are thereby driven with the same peripheral velocity for both rolls (4, 5), said projections
(6) and depressions (7), along the periphery (see Fig. 2) as well as axially (see
Fig. 4.) have corrugated, trapezoidal, pyramidal or conical form, the projections
(6) on one roll (4) engaging in the depressions (7) corresponding thereto on the corresponding
roll (5), the distance between the rolls being adjustable such that the sum of the
radius up to the crest of a projection (6) on one roll (4) and the radius to the bottom
of the depression (7) on the corresponding roll (5) complemental to said crest is
less than the distance between the central axes (9, 10) of the rolls.
6. A machine as claimed in claim 5, characterized by an adjusting means (12) for the
distance between the rolls (4, 5), which is adapted for adjustment so that the distance
constituting the difference between the distance L
A between the central axes (9, 10) of the rolls (4, 5) and the sum of one roll's (4)
radius

up to the crest of a projection (6) and the corresponding roll's radius

to the bottom of the depression (7) on this roll complemental to said crest will be
less than the thickness t
s of the fed-in layer, or that

.
7. as claimed in claim 6, characterized in that its adjusting means (12) for the distance
between the axes (9, 10) of both rolls (4, 5) is controlled mechanically or hydraulically.
8. A machine as claimed in claim 7, characterized in that the adjustment means (12)
consists of screws arranged between the bearings of the rolls, and driven by a reversible
electric motor.
9. A machine as claimed in claim 7, characterized in that adjustment takes place with
the aid of the movement of two hydraulic pistons (12) against spacer blocks corresponding
to the thickness of the fed-in layer (1), it being possible for the hydraulic pressure
momentarily to be reduced to zero on changing these blocks.
10. A machine as claimed in claim 9, characterized in that it is provided with a safety
device (13) which, when an incompressible disturbing body is fed between the rolls
(4, 5) momentarily unloads the hydraulic pressure with the aid of a bleed valve connected
to a pressure accumulator, the accumulator temporarily receiving (via the pipe 3)
the excess of hydraulic liquid caused by the introduction of the disturbing body between
the rolls (4, 5).
11. A machine as claimed in claim 10, characterized in that it is provided on the
discharge side of the rolls (4, 5) with a conveying track (11), which can be temporarily
moved to one side, or raised so that the disturbing body can be removed.
12. A machine as claimed in claim 8, charachterized in that the reversible electric
motor is controlled by a thickness sensor arranged upstream of the machine (4, 5,
12, 13).
13. A machine as claimed in one or more of the preceding claims 5-12, characterized
in that the rolls (4, 5) of the machine are driven via a reduction, e.g. a worm and
wheel, by means of an electric or hydraulic motor or an internal combustion engine
of a power which is small in comparison to the comminuting capacity of the machine
(4, 5, 12, 13), and suitably at a high rate of revolutions.
14. A machine as claimed in claim 13, characterized in that the driving motor is regulated
either with respect to the power requirement for the combustion or gasification plant
(3) or to the amount of material supplied to the machine (4, 5, 12, 13) on its input
side.
15. A machine as claimed in claim 14, characterized in that for the last-mentioned
case, a possible quantity of fuel exceeding the power requirement for the combustion
or gasification plant (3) is supplied to a buffer store between the machine (4, 5,
12, 13) and said plant (3).
16. A machine as claimed in claim 15, characterized in that the driving motor is regulated
with the help of a level monitor in the buffer store.
17. A machine as claimed in claim 6, characterized in that the rolls (4, 5) are made
as cast iron or forged roll rings (15) placed on, and keyed to a steel tube (14).
18. A machine as claimed in claim 17, characterized in that the roll rings (15) mounted
on the steel tube (14) are provided with projections (6) in the shape of pyramids
around their periphery.
19.. A machine as claimed in claim 18, characterized in that the roll rings are mounted
on the steel tube (14) such that those with even numbers are displaced one half of
the pitch between the pyramids in relation to the roll rings with odd numbers.
20. A machine as claimed in one or more of claims 5-19, characterized in that the
outer diameter Dl of the roll rings (15) is within the range of 40 to 120 cm, and
that their width is from 5 to 10 cm, and that the height of the pyramids is between
5 and 10 cm.
21. A machine as claimed in one or more of claims 5-17, characterized in that the
connecting line between the axes (9, 10) of two coacting rolls forms an obtuse angle
with the input direction of the material (1), thereby to facilitate its insertion
between the rolls (4, 5) (e.g. when feeding is done from a stack of boards).