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Патент USA US3060593

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Oct. 30, 1962
Filed March 25, 1959
2 Sheets~Sheet 1
Oct. 30, 1962
Filed March 25, 1959
2 Sheets-Sheet 2
United States Patent O? ice
Patented Oct. 30, 1962
order to regulate the intended height of the material bed.
The invention will now be described more in detail
with reference to the accompanying drawings, showing as
Sven Wallin, Jonkoping, Sweden, assignor to Aktiebolaget
Svenska Flaktfabriken, Stockholm, Sweden
Filed Mar. 23, 1959, Ser. No. 801,049
Claims priority, application Sweden Mar. 25, 1958
3 Claims. (Cl. 34-13)
an example one embodiment of an apparatus made in ac
cordance with the invention and in which:
FIG. 1 is a vertical, ‘longitudinal cross section of the
FIGS. 2 and 3 illustrate cross sections through the ap
paratus, taken on the lines 2—2 and 3—3 respectively of
paratus for drying or other treatment of loose materials 10 FIG. 1.
in form of grains, lumps or ?bers. The invention has
Referring to the drawing, the apparatus comprises a
particular utility in apparatus wherein a gaseous treating
number of superimposed units 1, 2, 3, 4, and 5 which are
medium is caused to pass through the material while
identical, except that the alternate units 1, 3, and 5 are
it is conveyed as a continuous bed in zig-zag passage
mirror images of the intermediate units 2 and 4. Each
ways over a number of superimposed perforated surfaces 15 unit is generally rectangular in form and is provided with
which are provided with guiding side walls.
inlet and outlet openings 6 and 7 respectively for the
In drying or other treatment of such loose materials in
material to be treated in the opposite end walls. In the
prior art apparatus, in order to obtain an effective treat
illustrated apparatus, the unit 1 functions as a pro-heating
ment it has been necessary to supply the treating medium
zone, the units 2, 3 and 4 as drying zones and the unit 5
The present invention relates to a method and an ap
in such a quantity and at such a pressure that the material 20 as a cooling unit for the material. Each unit has a sub
is given a whirling motion, thereby wasting considerable
power. Also relatively large spaces have been required
in the treatment apparatus—since the material by reason
of said whirling motion frequently is raised well above the
stantially horizontal, perforated, intermediate bottom 9
functioning as a conveying surface for the material. A
space 19 below said intermediate bottom functions as a
distributing box for the supplied treating medium. These
normal level of the material bed.
25 distributing boxes are connected to means 11 for supply
The present invention relates to an improved method
ply of the treating medium. Cleaning openings 16 and
and apparatus by which the disadvantages of the prior
17 are provided in the boxes 10 to remove foreign material
art can be eliminated. In practicing the method accord
which may enter the boxes. The openings are closed
ing to the invention, the height of the material bed is
by ?aps which are opened either intermittently or con
regulated in relation to the quantity and pressure of the 30 tinuously to discharge the foreign material. The open
supplied treating medium so that the ?ow velocity of the
ings are dimensioned so that when the openings are open,
medium through the material is sut?cient to overcome the
they do not interrupt the movement of the material
inner frictional resistance of the material and make it
on the conveying surface. As illustrated each unit may
possible for the material to move only by the action of the
be provided with separate ventilators or one single venti
treating medium through said passageways by causing the 35 lator can be used, which by means of distributing ducts
material to ?ow as a continuous bed without any mixing
is connected to said spaces 10 (not shown). The outlet
and to be conveyed along and between the passageways in
openings 12 discharge the treating medium after the
the form of a coherent belt or layer wherein the relative
passage of said medium through the material bed, and,
position of the material particles with respect to one
in the illustrated embodiment, are formed by bevelling all
another remains substantially unchanged. If pulverous
on a horizontal plane, that material will form of its own
the distributing boxes at the bottom along the longitudinal
side walls thereof whereby the arrangement of the outlet
openings will not increase the height of the complete ap
accord a natural angle of repose. However, when drying
medium is passed through the material with insu?‘icient
velocity to cause ?uidization, but sufficient velocity to 4
eliminate most of the internal friction, the granular ma
paratus, which otherwise would be the case if these outlet
openings were arranged in the side walls of the units.
These outlet openings 12 terminate into a common cham
ber 21 provided with an inclined ?lter 22 for the separa
or granular material is caused to fall in a natural position
terial assumes what we refer to hereafter as a modi?ed
tion of chaff and other impurities carried by the treating
angle of repose which is less than the natural angle of
medium. Partitions 23 and 24 form a separate space 25
repose of the material. In accordance with the invention,
in the chamber 21, into which space the outlet from the
when the modi?ed angle of repose is between 0.5“ and 10°, 50 unit '5—-functioning as the cooling zon*e—terrninates.
by reason of the control of the air moving upwardly
The space 25 leads into the fan 11 of the unit 4 by means
therethrough, interruption of the discharge of the material
of a duct 33. A free passage way 27 is provided below the
from the apparatus arrests the ?ow of the material
?lter 22 for a part of the treating medium and for the
throughout the apparatus by reason of its being a coherent
discharge of separated impurities. The above mentioned
55 chamber 21 is connected through a heating element 18
An apparatus for carrying out the method according to
and a transition 19 to the means 11 for the circulation of
the invention consists of a number of super-imposed units,
the treating medium through the units 1, 2 and 3. In
which are identical except that alternate ones are the
the present instance, each fan 11 is driven by an electric
mirror image of the intermediate ones. Each unit is
motor 20. The fan 11 for the cooling unit 5 receives air
formed as a rectangular box equipped with inlet and out
from the atmosphere directly without passing through a
let openings in the opposite end walls for the material to
be treated and is provided with a horizontal, perforated,
intermediate bottom functioning as a conveying plane
By this arrangement it is possible to recirculate the
treating medium in the drying units (as indicated by the
for the material.
arrow A in FIG. 3). In order to exhaust the water evapo
A ventilator connected to the space
below the intermediate bottom for supplying the treating 65 rated in the apparatus a party of the medium must con
medium and a discharge opening for'the medium is pro
tinuously be discharged which takes place partly through
vided above the intermediate bottom at a predetermined
the outlet 32 (see FIG. 1) in the pre-heating unit and
‘distance relative to the height of the bed. Said apparatus
partly through the outlet '26 (see FIG. 2) from the cham
is characterized by a stationary feeding table arranged at
ber 21. A corresponding quantity of compensating air is
the inlet end of each passage way and which declines
supplied to the drying units partly from the cooling unit
steeply towards the perforated intermediate bottom, an
through the chamber 25 (as indicated by the arrow B
adjustable shutter being mounted above said table in
in FIG. 1) and partly from the atomsphere through the
openings 28 arranged in each drying unit (as indicated by
What I claim is:
1. In the treatment of loose, granular or pulverous
the arrow C in FIG. 3). By an adjustment of the free
area of the openings 28 it is possible both to vary as re
materials by means of a gaseous medium in a plurality of
quired the proportion between recirculated air and com
pensating air and to decide to which unit or units out
door air is to be supplied.
walls and wherein the ?oor of each passageway is a ?xed
superimposed passageways equipped with guiding side
substantially horizontal perforated plane and the suc
The treating time for the material is regulated only by
regulating the quantity of discharged material. For this
cessive passageways are connected by vertical passages at
the slanting table 13 and the cooperating adjustable
bed to the extent of imparting to said material a modi?ed
ments 18.
of conveyance of the material in each and every passage
alternate ends of said perforated planes, the method
of moving the material through the successive passage
regulation a discharge pocket 29 is connected to the dis
charge opening 7 of the last unit 5, said pocket extend 10 ways which consists in feeding the material onto said
perforated planes and distributing the material across the
ing across the whole width of the unit. Regulating
width of said passageways to form a bed, passing gaseous
means is mounted in said discharge pocket, and in the
treating medium upward through each perforated plane
present instance is in the form of a rotatable winged
and the material bed thereon, controlling the height of the
wheel 30 with a length corresponding to the width of said
pocket. The winged wheel rotates counterclockwise and 15 material bed in each passageway in correlation to the
quantity and pressure of the treating medium supplied
thereby lifts the material and discharges the same through
thereto to such a value that the ?ow velocity of the
a discharge slot 31. The quantity of the material ?owing
medium overcomes the internal friction of the material
through each unit is regulated by the clearance between
20 angle of repose in the order of 0.5 to 10° whereby said
shutter 14.
material is conveyed along said passageways and passages
Without departing from the invention the construction
in the form of a coherent belt in which the relative posi
of the discharge means can be varied and in the same way
tions of the material particles with respect to one another
the heating of the medium can be carried out by means
are substantially unchanged during movement through
of a direct supply of heated air to the ditferent drying
said passageways and passages and regulating the velocity
units instead of utilizing the illustrated heating ele
Thus, the present invention provides a method and
apparatus for drying and similar treatment of granular
material wherein the material is moved over perforated
bottom plates. The height of the material bed is regulated
relative to the quantity and pressure of the treating
medium supplied to the under surface of the perforated
bottom plates so that the medium substantially overcomes
way and thereby the treatment of the material by adjust
ing the velocity of discharge of the material at the outlet
end of the last passageway.
2. A method according to claim 1 including the step of
providing separate treating medium supply means for each
of said passageways operable to effect ?ow of said treat
ing medium below each perforated plane prior to passing
through said plane in a direction concurrent with that of
the internal friction resistance of the material without
mixing the same. Thus, the material is caused to pass 35 the moving bed of the material.
3. A method according to claim 2 wherein the treat~
through the dryer in the form of a continuous coherent
ment of the material comprises pre-heating, drying and
layer. The material is caused to pass in ?ve separate
cooling in successive passageways respectively, character
runs, the ?rst of which is a preheating run and the last
ized in that the treating medium supplied to each of the
of which is a cooling run, the intermediate runs being
drying runs. Where the material ?ows downwardly 40 different passageways is treated separately and is condi
tioned according to the aforesaid treatment of the material
through the apparatus, the treating medium is caused to
in said passageway.
pass generally upwardly through the apparatus with
partial recirculation in each drying run. In each unit, the
References Cited in the ?le of this patent
medium ?ows under the preforated bottom plate in the
same direction as the material flows over the bottom
plate. The upward ?ow of the treating medium operates
Eaton ______________ __ June 13, 1871
to produce in the material, a modi?ed angle of repose in
Rudbach ____________ __ Jan. 27, 1942
the order of 05° to 10°, preferably about 5", so that the
Ford _______________ _- Jan. 15, 1952
material ?ows through the apparatus as a coherent belt,
at a velocity in each run determined by the velocity of
discharge at the outlet end of the last passageway.
Great Britain ________ __ Feb. 15, 1939
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