Note: Descriptions are shown in the official language in which they were submitted.
~1485~9
E G L Erlksson, Valberg
A method of comminuting for combustion such wood or cellulose
material as is precompressed, or board- or strip-like per se,
and an apparatus for carrying out the method
. _ . _ . . .
The ~nvention 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 de~ris
or household waste etc.
.
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 pine boiler, for example.
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
i8 no suitable equipment for rational recovery o~ the heat
from such waste material.
In actual fact, about 2% of the total chip board production
results in waste which is unusable for buildin~ purposes and
which is at present dumped or otherwise ~ot rid of.
~either can logging debris or household waste ~e utilized
for the generation of heat in a rational way at present.
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
1~48519
spreadlng or precompressing means (roll or the like) and is
thereafter taken ln between comminuting rolls, which can he
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 de~ressions
formed wavily, trapezoidally, pyramidally or conically, and
where the rolls in each pair are adated 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.
The invention also relates to a special comminuting ap~aratus
or machine for feeding a combustion or gasification ap~aratus
(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 aroun~ 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 spaclng between the rolls being adjustable such that
the sum of a radius to the crest of a projec~ion on one roll
and the radius to the bottom of the comple~entary depression on
the other roll is less than the distance between the central
axes of the rolls.
The invention otherwise relates to the characterizing features
more closely disclosed by subclaims 2-5 and 7~
1~8519
Since, in accordance with the invention, a fuel material is
used which is board- or stri~-like, or the fuel material is
pretreated so that a nrecompacted layer thereof is sunnlied
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 anfl can
be driven with a very small motor, that it will run com~ara-
tively ~uietly, that it discharges a uniform lum~ 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 ca~acity can also be easily
varied by regulating the s~eed of the rolls, and the lump si7e
can be regulated by adjusting the distance between the rolls
as already mentioned.
The lnvention will now be described in detail while referring
t~ 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 si~e,
Fig. la is a side view of a suitable ~recomFactor with
a roll, and
Eig. 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.
The comminuting machine in accordance with the invention,
illustrated together with a stoker ~lant in Fig. 1, comprises
a pair of comminuting rolls 4, 5 mounted rotatabiy and movable
~1~8519
in relation to each other about shafts 9 and 1~ on a frame 16.
In the illustrated embodiment example, the frame 15 is placed in
immediate conjunction 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,
yieldingly 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 1~, 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 insertéd under a feed roll 2, mounted in a glide
block 21by means of a shaft 2~. The block in turn qlides u~wards
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 2S, which is
suspended in the frames 16 and 22, and on which substructure
the chipboard 1 is ad~anced. As soon as the forward edge of
the chipboard has advanced to the peripheries o the rolls 4 and
5 with their project~ons 6 and depressions 7, the board 1 i5
drawn in between the rolls as a result of these being adjusted
at a certaln spacing from each other, corresponding to the
thickness of the chipboard 1. The comminuting machine's rolls
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
~8519
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.
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 he comminuted. In
this case, as is apparent ~rom Fig. la, the spreading or
precompresslng means 2, 21, 23, 22 is provided with a ho~per 26
into which the fuel material, e.g. household waste, can be
tipped. In this case the wheel 24 is screwed down more tightl~
so that the pressure from the spring 23 causes the roll 2 to
press heavily against the substructure 25. A ~recompacted
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.
As is apparent from Fig. 4, the comminuting rolls 4 and 5
can be built up from roll rings lS 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 car~ied on shafts so that a
comminuting machine is formed, of the kind shown as an example
in Fig. 1.
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.
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.
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
1~48519
a hydraulic cylinder 12 with a piston, suoplied with hydraulic
fluid at a suitable pressure via the pipe 13. ~30wever, 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.
With hydraulic actuation of the up and down movement of the
roli 4, the inte~ded 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.
.
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.
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 ~m, for corresponding to Drevalent
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
tS and the dlstance between the centres of the rolls LA,
then the desired distance 1 2
LA (2 ~ 2 ) ~ tsl and thus
LA ~tS + 1 2
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 tu~e 14 with an
outside diameter of 40 cm, for example, the wheels being
keyed to the tube.
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.
1148519
A suitable outside diamter Dl ~or the roll wheels 15 is from
40 to 120 cm.
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 ~
It is also suitable that adjacent wheels are relatively displaced
by an amount equal tc half the pitch of the pyramids in the
peripheral direction.
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.
.
Broken pieces of the board will then be obtained which have
an approximately triangular sha~e.
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 supplled to the spreading or precompressing means 2,
21, 22. If the rate of supplying fuel exceeds the power
requlrement 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.
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. Rxtremely simple and cheap
fabrication with a very robust construction is thus obtained.
-` ~1485~9
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.
