U.S. patent number 3,929,628 [Application Number 05/418,830] was granted by the patent office on 1975-12-30 for apparatus for reducing preconditioned garbage to a clinkerless combustible.
This patent grant is currently assigned to Vista Chemical & Fiber Products Inc.. Invention is credited to Pietro G. Denevi, Mark B. DiDuca, Billy J. Slane, Thomas D. Vence.
United States Patent |
3,929,628 |
Denevi , et al. |
December 30, 1975 |
Apparatus for reducing preconditioned garbage to a clinkerless
combustible
Abstract
A closed system between an air seal gated hopper receiving and
funneling the preconditioned garbage into the restricted end of the
tapering air duct through which air from a blower enters to effect
venturi action forcing the garbage toward the lower end of a
vertical stack of zigzag ducts wherein heavier fractions drop out
while lighter fractions discharge into a trommel in a closed
chambered storage bin from which air recirculates back to the
blower from which supplemental air feeds into an air cushion at the
juncture of the tapering air duct with the stack of ducts for
boosting the on coming garbage up into the latter, and means for
controlling air pressure within the ducts of the system.
Inventors: |
Denevi; Pietro G. (Los Gatos,
CA), DiDuca; Mark B. (Los Gatos, CA), Slane; Billy J.
(San Jose, CA), Vence; Thomas D. (San Jose, CA) |
Assignee: |
Vista Chemical & Fiber Products
Inc. (New York, NY)
|
Family
ID: |
25765661 |
Appl.
No.: |
05/418,830 |
Filed: |
November 26, 1973 |
Current U.S.
Class: |
209/36; 209/147;
209/138; 209/149 |
Current CPC
Class: |
B01J
23/46 (20130101); B01J 23/466 (20130101); B07B
9/02 (20130101); B07B 7/01 (20130101) |
Current International
Class: |
B01J
23/46 (20060101); B07B 9/02 (20060101); B07B
7/00 (20060101); B07B 9/00 (20060101); B07B
7/01 (20060101); B07B 009/02 () |
Field of
Search: |
;209/136-139R,146,147,149,154,34-37,30,31 ;241/19,79.1,60,46A
;110/8C,15,18R ;302/29,22,64 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Lutter; Frank W.
Assistant Examiner: Hill; Ralph J.
Attorney, Agent or Firm: Hansen; Leslie M.
Claims
What we claim and desire to protect by Letters Patent is as
follows:
1. Apparatus for disposing of refuse such as garbage and the like
from which heavier ferrous material has been removed and the
remaining refuse ground up, shredded and dried as a preconditioned
material; a closed air system for separating heavier,
non-combustible elements in such material from lighter fractions
therein preliminary to consumption of the latter by fire or
conversion into useful products comprising:
a. a feed conveyor for feeding such preconditioned material to the
closed air system;
b. a hopper for receiving such preconditioned material from said
feed conveyor;
c. an air sealed gate at the open upper end of said hopper openable
by discharge of such preconditioned material from said feed
conveyor into said hopper;
d. an elongated tapering infeed duct having a restricted open end
communicating with the lower end of said hopper for receiving such
preconditioned material therefrom and declinding at a slight angle
relative to horizontal from said restricted open end and expanding
in area progressively therefrom toward a terminal end;
e. a stack of vertically disposed zigzag ducts having its lower end
communicating with the terminal end of said elongated tapering
infeed duct and providing a tortuous path discharging at its upper
end;
f. a closed chambered storage bin communicating with the discharge
upper end of said stack of zigzag ducts;
g. a blower, having a housing communicated with the restricted open
end of said tapering infeed duct for creating a venturi action at
the lower end of said hopper for transmitting such preconditioned
material therefrom and for causing the incoming shredded, dried
material to spread out and flow more loosely and opening through
the gradually expanding elongated tapering infeed duct and into
said stack of zigzag ducts for discharging lighter fractions from
the latter into said storage bin;
h. an air return duct between said closed chambered storage bin and
said blower for recirculating air from the bin to the blower;
i. a baffle wall projecting upwardly from the declining bottom wall
of said elongated tapering infeed duct at the open lower end
thereof for providing a trough-like terminal end therein;
j. a perforated plate mounted in the trough-like terminal end of
said infeed duct and extending tangentially from the bottom wall
thereof toward the upper edge of said baffle wall for providing an
air lift chamber there-between; and
k. a supplemental air supply duct communicating said blower with
said air lift chamber for supplying air through the perforated
plate to creat an air cushion for lifting preconditioned material
therefrom and into the air stream passing from said infeed duct
into the lowermost one of said zigzag ducts in the stack
thereof.
2. A closed system air classifier in accordance with that of claim
1 including a damper in said supplemental air supply duct for
controlling the volume and velocity of air flowing therethrough
from said blower into the air lift chamber of said air cushion.
3. The closed system air classifier in accordance with that of
claim 1 in which said baffle wall extends upwardly from the bottom
wall of said infeed duct in substantial parallelism relative to the
inclined wall of the lowermost one of said zigzig ducts and in
spaced relation to such inclined wall to provide a drop out opening
at the lower end of said stack of zigzag ducts for discharging
heavier fractions of refuse descending therefrom.
4. The closed system air classifier in accordance with that of
claim 3 including:
a. a drop-out duct communicating with the drop out opening at the
lower end of said stack; for receiving heavier fractions of refuse
material descending therefrom;
b. a smaller set of zigzag ducts within the drop-out duct for
receiving the refuse material descending therethrough; and
c. a secondary air duct between said blower and the lowermost one
of said smaller set of zigzag ducts in said drop-out duct for air
lifting any lighter fractions of refuse therefrom back up into said
stack of zigzag ducts of the air classifier.
5. A closed system air classifier in accordance with that of claim
4 including a damper in said secondary air duct for controlling the
volume and velocity of air flowing therethrough from said blower
into the air lift chamber of said air cushion.
6. The closed system air classifier in accordance with that of
claim 5 including:
a. a flume type conveyor at the lower end of said drop-out duct for
receiving and removing the heavier fractions of refuse
therefrom;
b. a trommel screen in said closed chambered storage bin for
receiving the lighter fractions of refuse from the upper end of the
stack of zigzag ducts for sifting out any fines of silicate, grit
and the like therefrom; and
c. a conveyor belt below said trommel screen for receiving fines
therefrom and for discharging said fines into said flume type
conveyor.
7. The closed system air classifier in accordance with that of
claim 6 including:
a. a damper in the housing of said blower;
b. a servo operated solenoid operatively connected to said damper;
and
c. a pressure detecting sensor switch means in the zigzag ducts of
said stack thereof and electrically connected to said servo
operated solenoid for controlling the setting of said damper within
the housing of said blower to deliver the required volume of air
and velocity thereof to said zigzag ducts.
Description
BACKGROUND
This invention relates to garbage disposal systems and to apparatus
in such systems for processing raw garbage preparatory to ultimate
disposal. The invention is particularly directed to a classifier in
such systems for separating heavier elements, especially of the
non-combustable type, from lighter fractions in garbage which are
more easily disposed of by combustion or conducive to formation
into usable and saleable articles.
The overall combination of devices and components for processing
raw garbage are well known in the art. For example, reference to
U.S. Pat. Nos. 3,473,494 and 3,584,587 to GIANNI SIRACUSA may be
had for an understanding of the usual procedure. In such prior type
systems the raw garbage is first loosened up by passage through a
beater for breaking it up into a more friable condition for
separation. In this condition any heavier ferrous metal therein is
magnetically detected, withdrawn and discharged therefrom at a
ferrous metal discharge station. The remaining non-ferrous portion
is then passed through a grinder for crumbling into smaller
segments which are then shredded and passed through a dryer.
Heretofore, it was believed that the product at this stage could be
disposed of by combustion within a furnace by which all of the
remaining material could be consumed. This resulted in a biproduct
of slag or cinders mainly consisting of glass and some of the
plastics which remained in the product. The greatest difficulty
arose from the formation of solid clinkers in the base of the
furnace requiring periodic shut-down to enable workmen to remove
such clinkers. Such removal usually requires a hammer and pick and
more often than not the base or sump of the furnace became damaged
requiring extensive and costly repairs.
It later became apparent that such slag might be kept molten within
the furnace and discharged therefrom in a molten condition. This
requires a heat of greater intensity at the sump level of the
furnace. The intensive heat required rendered the lining of the
furnace frangible and subject to damaging effects within short
periods of time.
THE PRESENT INVENTION
In accordance with the present invention it is an object to subject
the shredded and dried material, free of ferrous metals to further
separation by a classifier. By this object the heavier shredded
particles of non-ferrous metal, glass or silicate grit as well as
plastic are separated from lighter particles of paper, vegetation,
meat scraps, and pulp. Such lighter particles in a fluffed
condition are then subjected to screening in a trommel mill so as
to sift out any fine dust or grit, silicate and the like. The
remaining fluffed material is then more conducive to being
completely consumed by combustion.
It is another object of this invention to store the remaining
lighter, screened fluffed material in a storage bin preparatory to
disposal by either combustion within a furnace; or for suitable
treatment with a bonding agent whereby the material may be
compacted into various forms of usable articles. This may entail
the molding of the treated material into slabs or blocks of
building materials or into cakes and/or pellets by compression for
use in fire places, barbeque pits and the like for heating
purposes.
It is another object of this invention to provide an air classifier
within a closed system including an air return for recirculating
the air from the storage bin back into the blower of the
system.
It is yet another object to provide a venturi arrangement at the
point of admittance of the shredded dried remaining refuse so as to
quickly remove the latter discharging into the main air intake duct
of the system.
These and other objects and advantages of the present invention
will become apparent in the following description when read in the
light of the accompanying five sheets of drawing in which:
FIG. 1 is a diagramatic plan view of the initial treatment and
handling of garbage and the like preliminary to its admittance into
the classifier embodied in the present invention;
FIG. 2 is a foreshortened plan view of the main duct infeed to the
classifier;
FIG. 3 is a diagramatic plan view of the balance of the garbage
treatment and disposal plant embodying and illustrating the closed
air recirculating system of the present invention;
FIG. 4 is a cross section through a trommel screen in the holding
bin of FIG. 3 and taken substantially along line 4--4 therein;
FIG. 5 is a side elevation of a portion of FIGS. 1, 2 and 3 with
parts of the holding bin of the latter shown in section;
FIG. 6 is an enlarged sectional view through the classifier, air
intake and velocity control zone of the arrangement shown in FIG.
5;
FIG. 7 is a modified construction of the air intake and velocity
control zone of the present invention;
FIG. 8 is an enlarged section through the venturi entrance to the
main infeed duct taken substantially along lines 8--8 in each of
FIGS. 1 and 2;
FIG. 9 is a vertical section through FIG. 8 taken substantially
along line 9--9 therein;
FIG. 10 is a horizontal section through FIG. 8 taken substantially
along line 10--10 therein.
FIG. 11 is a longitudinal section through an airlift cushion screen
at the discharge end of the main infeed air duct of FIG. 2 and
taken along line 11--11 therein.
FIG. 12 is a cross section through FIG. 11 taken along line 12--12
therein; and
FIG. 13 is a fragmentary diagramatic perspectus view of the air
infeed duct and air lift cushion of FIGS. 8 and 11 combined.
FIG. 14 is a schematic wiring diagram of the pressure sensor and
servo solenoid control for the damper in the closed air system.
GENERAL DESCRIPTION
Referring to FIGS. 1, 2, 3 and 5 of the drawings the entire
apparatus generally designated 15 includes a preparation section
16; an air classifier 17 (FIG. 5); trommel screen 18, storage bin
19 and a disposal of the final biproduct for example in a furnace
20 disclosed in the present application.
The pre-preparation section 16 as best illustrated in FIG. 1
includes a conveyor 21 by which the raw garbage is put through a
series of devices for transformation into a condition suitable for
disposal. The raw garbage is fed into the conveyor 21 (lower end
FIG. 1) for movement through a hammer mill 22 to loosen up and
separate the congealed refuse into a more flowable condition.
Thence the garbage is conveyed through a magnetic field in a device
23 by which the ferrous portion in the garbage is removed and
discharged therefrom.
Once the ferrous metals are removed from the garbage the latter is
put through a grinder 24 for chopping up the refuse material into a
more friable condition. In this condition the material is put
through a shredder 25 and a dryer 26 for conveyance toward the
classifier 17.
The shredded, dried remaining refuse material designated M is
conveyed toward the classifier by a conveyor belt 27 having a
terminal pulley 28 at its discharge end 29.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention the classifier 17 is
embodied in a closed system 30 between a hopper 31 at the discharge
end 29 of conveyor 27 and the storage bin 19. For this reason the
storage bin 19 is in a closed chamber 32 in which the trommel
screen 18 is housed.
The air classifier 17 is of the zigzag type in which a series of
alternately pitched angular ducts 33 are arranged as a vertical
stack 34 such that there is no direct vertical path therethrough.
The refuse material M from the hopper 31 is transmitted via an air
admittance and velocity control duct 35 toward a juncture 36 of the
lowermost one of the ducts 33 in the stack 34 with a drop-out duct
37.
The duct 35, hereinafter referred to as an infeed duct, is an
elongated duct tapering from a restricted smaller end 38 adjacent
the hopper 31 to an enlarged open end 39 at the juncture 36 of the
duct system. A blower 40 introduces a blast of air into the
restricted end 38 of the infeed duct 35 which effects a venturi
action V. The venturi action V is such that the material M falling
from the hopper 31 is immediately removed therefrom by suction and
moved along the gradually enlarging infeed duct toward the enlarged
open end 39 thereof.
The flow of air and material M is upwardly the tortuous path in the
stack 34 of zigzag ducts 33 for discharge via an arcuate duct 41
the discharge end 42 of which spills downwardly into the trommel
screen 18 in the closed chamber 32 of the storage bin 19. By
passage of the material M upwardly in the zigzag stack 34 any
heavier particles of glass, plastic and the like strike the
inclined walls i thereof and fall back down the declined walls d as
indicated by the solid arrows O in FIG. 6 of the drawings. The
lighter particles of the material M continue upwardly the tortuous
path for discharge into one end of the trommel screen 18 in the bin
19 along the lines of the open arrows S in FIG. 6.
The trommel screen 18 as best seen in FIGS. 3, 4 and 5 is made up
of a wire mesh screen 43 within a plurality of channel shaped rings
44 supported on rollers 44' (FIG. 4). The trommel screen 18 is
caused to rotate by a chain and sprocket drive 45 (FIG. 5) so that
the material M tumbles within the screen 43 to sift out particles
of grit and sand before the material discharges into the storage
bin at the opposite end of the trommel screen.
The foregoing agitation of the material M in the trommel screen
creates a dust which is carried off from the closed chamber 32 in
the bin 19 by the air therein being drawn toward the inlet end 46'
of an air return duct 46 the opposite end of which communicates
with the air intake side of the blower 40 (FIGS. 4, 5 and 7), as a
part of the closed system 30.
The closed system 30 is further enhanced by an air lock in the form
of a gate 47 at the open upper end of the hopper 31 as best
illustrated in FIGS. 6, 7 and 8. It will therein be noted that the
hopper 31 has a vertical wall 48 opposite the discharge end 29 of
the conveyor 27. The side walls 49--49' of the hopper 31 have their
vertical upper portions supported between beams 50--50' which
support the full width of the conveyor 27. The lower portions of
the side walls 49--49' of hopper 31 taper downwardly (FIGS. 9 and
10) to the width of the restricted end 38 of the infeed duct 35.
The gate 47 (FIG. 8) is a hollow segmental structure pivotally
mounted as at 51 across the upper edges of the side walls 49--49'
of the hopper. The hollow structured gate 47 has one radially
disposed door member 52 normally disposed at an angle downwardly
toward the terminal pulley 28 at the discharge end 29 of the
conveyor 27. The material M coming off of the conveyor 27 forces
the door 52 to open to allow the material to fall by gravity into
the hopper and toward the infeed duct 35. Other than the opening of
the gate thus afforded, the hollow structured gate 47 closes the
upper end of the hopper by having an arcuate wall 53 wiping along
an air seal brush or resilient member 54 mounted on the vertical
wall 48 of the hopper 31.
The upper radial portion 55 of the gate 47 is an open structure
having a flange 56 extending from the upper end of the arcuate wall
53 so as to bear against the upper edge of the vertical wall 48 of
the hopper. This serves as a stop for the gate when in its normally
closed condition. The gate 47 may be provided with a weight 57
calculated to cause the gate to close other than against the weight
of the incoming material M from the discharge end 29 of the
conveyor 27.
In the preferred embodiment of the invention, FIGS. 5 and 6, the
blower 40 is shown mounted on a blower housing at the floor F of
the establishment. In this arrangement the blower discharges air
into an air supply duct 58 disposed at an inclined angle upwardly
toward the restricted open end 38 of the infeed duct 35. This
arrangement requires a semicircular hook-like terminal end 59 on
the air supply duct 58 in order to effect a tangent discharge of
air directly into the infeed duct 35. The blower might well be
mounted in place of the hook-like terminal end 59 as indicated at
40' in FIG. 7. In either case the air stream from the blower is
converged into the restricted open end 38 of the infeed duct 35 to
induce a high pressure velocity venturi action V at the lower end
of the hopper 31. A suitable damper D may be embodied in the air
supply duct 58 to regulate the velocity of the air flow from the
blower. In this connection it will be noted (FIGS. 6, 8 and 13)
that the lower end 60 of the vertical wall 48 is curved slightly to
funnel the dropping material M into the gradually spreading infeed
duct 35.
By the foregoing arrangement the incoming shredded and dried
material M is caused to spread out and flow more loosely and openly
into the lowermost duct 33 of the zigzag vertical stack 34 of the
air classifier 17. To assure an air lift action at the juncture 36
of the classifier 17 an air cushion 61 is provided at the enlarged
open end 39 of the infeed duct 35 (FIGS. 6, 11, 12 and 13).
The air cushion 61 is arranged in a trough-like terminal end 62 of
the infeed duct 35 formed by a baffle wall 63 disposed at
substantially the same inclination as the inclined wall i of the
lowermost one of the zigzag ducts 33 in the stack 34. The baffle
plate 63 extends upwardly about one half the heighth of the
enlarged open end 39 of the infeed duct 35 so as to deflect the air
stream upwardly into the stack 34. The air cushion 61 comprises a
sieve-like perforated plate 64 having a curved medial wall 65
beginning inwardly the duct 35 and tangentially from the bottom
wall 66 thereof up to the top edge of the baffle plate 63. The air
cushion 61 also includes diagonally disposed seive-like perforated
plates 67 and 67' between each side of the curved medial wall 65
and the respective side walls of the infeed duct 35 as illustrated
in FIG. 12. The perforated plates 67 and 67' extend into the infeed
duct 35 from an upper edge extending horizontally back from the
upper edge of the baffle plate 63. By this arrangement air chambers
68 and 68' are provided under the diagonally disposed side plates
67 and 67' in communication with a similar air chamber 63' between
the baffle plate 63 and the curved medial wall 65 in the
trough-like terminal end 62 of the infeed duct 35.
The air cushion 61 is further completed by having air supplied to
the chambers 63', 68 and 68' via a supplemental air duct 69
communicated with the main blower 40 of the system. The
supplemental air duct 69 has a restricted discharge end 70
communicating with the trough-like terminal end 62 of the infeed
duct 35 to supply air to the chambers 63, 68 and 68' below the
perforated plates thereof. The opposite end of the supplemental air
duct 69 may be tapped into the main air supply duct 58 as shown in
FIGS. 5 and 6 or direct to the blower housing as shown at 69' in
FIG. 7.
By the foregoing arrangement air blasting upwardly through the
apertures 71 of the sieve-like plates 64 at 65, 67 and 67' lifts
the oncoming material M and merges with the air carrying the latter
through the infeed duct 35. The material M is thereby deflected
upwardly into the lowermost zigzag duct 33 of the vertical stack 34
of the classifier 17. This assures ascension of all of the material
M into the stack 34 before and removal of any heavier fractions
from the infeed duct 35. Such heavier fraction will ultimately meet
resistance along any one of the inclined walls i of the zigzag
ducts and fall by gravity toward the descending walls d as
indicated by the closed arrows in FIG. 6.
The heavier fraction of material M falls out of the lowermost duct
33 of the stack 34 between the baffle plate 63 and opposite wall 72
of the duct 33 (FIG. 6) which is parallel to plate 63 at the
juncture 36 with the drop out duct 37. The heavier fraction of
material M entering the upper end of the drop out duct 37 may be
subjected to air classification by a smaller set of zigzag ducts 73
to assure that any lighter fractions of the material M entering the
drop-out duct will be caused to ascend back up into the stack 34 of
the classifier 17. To this end the smaller set of zigzag ducts 73
have an air supply from the blower 40 via a secondary duct 74. The
secondary duct 74 has communication with the blower via the main
air supply duct 58 and has a terminal end 75 discharging into the
lowermost one of the zigzag ducts of the smaller set 73 thereof.
The same arrangement is shown in FIG. 7 wherein a modified form of
secondary duct 74' extends from the blower 40' to the smaller set
of ducts 73 in the drop-out duct 37.
The heavier fraction of the material M ultimately falls from the
lower end of the drop-out duct 37 into a flume type conveyer 76 for
discharge therefrom. The flume type conveyor 76 also receives sand
and grit by way of a chute 77 (FIG. 5) coming from the end of a
conveyor belt 78 below the trommel screen 18 in the closed
chambered storage bin 19. The fine sand, grit, glass chips and the
like heavier fractions discharged from the flume type conveyor 76
may be used in earth fill and the like. The main point involved is
the separation and removal thereof from the lighter fractions of
the material M reduces to a minimum the problem heretofore
encountered by the formation of slag and/or clinkers in the furnace
20 of a disposal plant.
The lighter fraction of the material M stored in the storage bin 19
may be ultimately consumed by fire in the furnace 20 or may be
compressed into slabs or briquets as desired. AS shown in FIG. 3
wherein the furnace 20 is illustrated, the material M from the
storage bin 19 may be fed automatically therefrom by a screw feed
79. The furnace 20 is shown to have a forced air feed 80 associated
with a fluffer 81 such that the stored lighter fraction of the
material M will be fluffed up preliminary to entrainment into the
forced air feed 80 and into the furnace 20.
SUMMARY
The preconditioned garbage from which ferrous metals have been
removed may contain other metals, glass, grit and plastics in a
ground up shredded condition. In accordance with the present
invention such heavier fractions are separated and removed from
lighter combustible fractions in the preconditioned garbage. This
is accomplished by means of the air classifier 17 disposed betweem
the point of discharge of the feed conveyor 29 and the storage bin
19.
The remaining lighter fraction is thereby reduced to having only a
minimum quantity of any heavier fraction therein before passage to
a combustion chamber or furnace. Actual experience has shown that
for every 1000 pounds of raw garbage treated preliminarily a good
100 pounds of heavier fraction, exclusive of ferrous metals
preliminarily removed, has been separated and collected from the
shredded, dry refuse by the air classifier 17 operated in
accordance with the present invention.
Reviewing the operation it is important to note that the air
classifier 17 is in a closed system 30. This closed system 30
includes the closed chamber 32 of the storage bin 19 and the air
sealed gate 47 on the hopper 31 above the discharge end 29 of the
infeed conveyor 27. It also includes the trommel screen 18 and
conveyor 78 below it within the closed chamber 32. By the trommel
screen the heavier fractions sifted out of the material M entering
the storage bin 19 are removed and discharged via chute 77 into the
flume-type conveyor 76. Any fine particles of dust within the
closed chamber 32 are removed therefrom by the negative pressure
afforded at the entrance end 46' of the air return duct 46 going
back to the blower 40.
The pneumatic portion of the closed system 30 involves the initial
infeed duct 35 and the venturi action V afforded thereby at the
restricted open end 38 thereof. The blast of air from the blower 40
is narrowed down to increase its velocity where the refuse material
M falls from the conveyor 27. Thus the material is quickly removed
toward the enlarged end of the infeed duct 35. It will be noted in
FIGS. 2, 6 and 13 that the duct 35 expands areawise outwardly and
upwardly so that the material carried along by the stream of air
spreads out to approximate the width of the ducts 33 in the stack
34 thereof. Moreover, the bottom wall 66 of the duct 35 is set at a
downward angle at least 15.degree. off horizontal so that the air
stream and material M readily flows toward the juncture 36 between
the upper and lower classifier ducts 34 and 73. Then too the air
cushion 61 provided by the perforated plates 64, 67--67' in the
trough-like terminal end 62 of the duct 35 and the up draft of air
therethrough from the supplemental air duct 69 serves to lift the
material M well into the lowermost duct 33 in the stack 34 thereof.
In combination with the air cushion structure 61 the baffle wall 63
thereof set at an angle comparable to that of the lowermost duct 33
serves therewith as a receiving end of the zigzag ducts 73 in the
drop-out duct 37 below the juncture 36 of the three ducts 35, 33
and 37. This initially isolates the heavier fractions of the
material M falling from the lowermost duct 33 in the stack 34
thereof.
It should here be noted that the volume of material carried by the
air stream upwardly into the stack 34 may not flow as uniformly as
desired. Consequently, the air pressure required to carry any
increase in volume upwardly may have to be increased. This increase
in air velocity and pressure is increased by control of the damper
D in the main air duct 59.
In order to control the pneumatic pressure in the system 30
automatically pneumatic control sensors may be provided in the
zigzag ducts 33 and 73 of the air classifier 17. These sensors,
designated 83 may be of any well known pressure gauges for
detecting the static pressure within the zigzag ducts to determine
the need for a greater or lesser pheumatic pressure therein from
the blower 40. In this event the sensors 83 may be of the
electromechanical type electrically connected in a circuit 85
having a servo operated solenoid 84 therein. The servo operated
solenoid as in U.S. Pat. Nos. 2,950,424 or 3,229,170 may be
operatively connected to the damper D to change or restrict the
flow of air. By this arrangement the velocity of the air flow and
pressure within the duct is automatically adjusted to maintain a
uniform flow of material M through the classifier.
Having thus described the apparatus for reducing preconditioned
garbage to a nonclinker producing combustible in specific detail,
it will be appreciated by those skilled in the art that such
apparatus may be susceptible to variations, alterations and/or
modifications without departing from the spirit or scope of the
appended claims.
* * * * *