Note: Descriptions are shown in the official language in which they were submitted.
1 324591
BACKGROUND
This invention relates to apparatus for preparing, clas-
sifying, and metering particle media useful for various purposes
and especially fox particle blast cleaning and treating systems.
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U.K. Patent ~pplication GB 2,171,624A describes method and
apparatus for cleaning by abrasive blastinq. The input
particles are fed by gravity into a chaxging chamber which is
a cylindrical shell with a rotating bladed rotor therein to
carry the particles to an output leading to an auger which
drives them in a continuous manner into an entraining air
jet stream. Control of the air and particle amounts and
~ ratios is very inprecise and it would seem to be difficult'l to obtain good cleaning effects from the system described es-
pescially for a wide spectrum of surface types and conditions.
i 15 The ~laded rotor or plodder would be difficult or impossible
to seal against substantial pressure differences and control
( shear which could damage delicate particle media. The system
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'~ ~ is gravity dependent and therefore limiting for media which
, tends to pack and plug up the system. The gravity of media
20 passed by the plodder and that by the receiving auger cannot
~! b:e matched in a practical way and necessitates and overflow
to the receiver. The design of the screw or auger does not
due to its design seal against pressure.
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In Canadian Patent Application ~o~ 601,142 filed May
30, 1989 in the name of the same inventors as the present
application, a method and apparatus for particle bla~t
~ cleaning and treating of surfaces is described comprising
¦ metering a flow of particles rom a supply, positively
30 feeding the particle ~low from the metering stage into a
fluidizer, fluidizing the particle flow with a controlled,
~ metered flow of fluid taken from a pressuriæed fluid source,
; pneumatically conveying a particle-fluid stream from the
fluidizing stage to a ~last head, and controlling the fluid
35 flow rates and the particle amount rates and the mass flow
ratios of the flows precisely and over fairly w~de ranges to
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provide a particle blast cleaning and treating effect for a
wide range of surfaces and objects. In that application
method steps and apparatus units for preparing a particle
media for oleaning and treating systems are described and
these include crushing (size reduction), storing (surge vessel)
with level control, metering by pumping, and fluidizing for
transport.
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~ BRIEF SUMMARY OF INVENTION
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It is an object of the present invention to provide apparatus
~` for preparing, classifying~ and metering particle media useful
~or many purposes especially particle blast cleaning and
treating systems in which the particle preparation parameters
are under complete and positive control.
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These and other objects of the invention are achieved by
apparatus for preparing, classifying, and metering particle
rl media useful for various purposes including particle blast
cleaning and treating systems comprising means for kaking
a media having a working particle size range and sending
the media particles along with a fluidizing air input through
a scroll, a classifier/surge tank acting as a cyclone separator
~`l connected to the fluidiæed particle/air stream output of the
scroll, means for taking the lighter portions of the particles
from the cyclone separator and transporting this to recovery
or utilization means, means for taking the heavier portions
~J of the particles from the cyclone separator and transporting
this to utilization means or recovery, metering means for
taking the lighter or heavier portion of the particles from
the cyclone separator in a controlled manner, and means for
taking the metered particle stream from the metering means
and providing along with a pressurized air input, a fluidized
air/particIe output in a controlled manner such that the
air/particle ratios are controlled and the particles are
3 in a steady or pulsed flow as desired.
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1 324591
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 is a schematic flow diagram of a particle media
preparation system for particle blast cleaning and other
purposes,
Figure 2 is a cross-section of apparatus for the system
of Figure 1,
Figure 3 is an end view of the apparatus of Figure 2,
Flgure 4 is of a partially broken view of the apparatus of
Figure 2,
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Figure 5 is a cross-section view of the crusher and
classifier impeller,
~ Figure 6 is a cross-section on A-A of Figure 2 of the
:i~ crusher and scroll,
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~: Figure 7 is a cross-section of the flow metering screw,
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: Figure 8 is a cross-section of the rotary metering pumps,
: Figure 9 is a top view of the rotary metering pump,
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Figure 10 is a cross-section of the rotary cylinder showing
~ the individual chambers,
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~ . Figure 11 shows detail of the labrynth seal for purposes of
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maintaining and isolating pressure in incremental steps,
:30
Figure 12 is a schematic diagram of the particle media
preparation apparatus in a complete particle blast cleaning
~ and treating system.
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1 32459 1
DESCRIPTION OF THE INVENTION
Referring to the drawings, Figure 1 is a schematic flow
diagram of the system wherein the input media material is
fed into crusher ~sizer) 1 which has a fluidizing air input.
The air is added to fluidize and prevent temperature rise of
the media due to the energy introduced for size reduction and
air for cyclonic action. A mechanical impeller 2 which may
run at the crusher/sizer speed or at other desired speeds to
introduce a spin to the sized material and send the material
and the fluidizing air through scroll 3 to initiate cyclone
action in classifier/surge task 4. In addition to providing
surge volume and level control, this vessel provides media
size control by cyclonic action (settling rate difference between
~ larger heavier and smaller lighter particles). An eductor 5
3 generates a forced vortex and a velocity which entrains the
tl 15 finer particles having slower settling rates and fluidizes the
~ entrained media for transport. Velocities and therefore
i~ selection of the fineness of the particles withdrawn are
adjustable by the total entrained air throughout via eductor
,J'I (motive) air rate control. Crusher/sizer speed control
3~ 20 provides further adjustment of fines to coarse particle ratios.
~; ~he system may be run such that the fines are the rejects
to be sent to recovery and the coarser material the product.
~N~ Alternatively, the fines may be the product and the coarser
recycled for additional size reduction. This arrangement
may preclude the need for multiple crushers and size reduction
steps which is the current industrial practice.
Delicate or difficult to handle media (dry, abrasive, etc.
cannot be easlly handled without shear in pumping through any
appreciable pressure rise in known suitable apparatus. Output
I from classifier/surge cyclone 4 is sent via flow metering pump
6 to a rotary cylinder metering pump 8 which is designed to
1
raise the metered particles to the desired pressure with near
l 35 zero shear by passing cylinder chamhers through progressive
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1 3245q 1
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pressure increments with air or their fluid added in a controlled
manner to raise the pressure as required and also fluidize.
The chambers in ~he rotary pump may be fully or partially
loaded at the inlet and the output rate controlled by the rate
of chamber deliveries (by the R.P.M. of the drive motor). For
more control and providing for pulse rate of delivery, the
pump chambers are oversized with respect to the desired
maximum rate and the R.P.M. independently controls the pulse
rate.
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~ Figures 2, 3, and 4 illustrate the above system in more
- detail. A sizer/crusher 1 is driven by crusher speed control
motor 10. Input media is supplied to the crusher by screw
; 15 drive 11 driven by motor 12 (see Figure 4) and classifying air
- is introduced at port 13. From crusher 1 the crushed material
and classifying air is driven by impeller 2 through scroll 3
into classifier/surge task 4 to act as a cyclone classifier.
Scroll 3 also has classifying air injected into the air stream
by air injection devices 3a and 3b positioned as shown in Figure
4. These are known devices and serve to provide an enhanced
-~ rotating air stream to the cyclone classifier. The crusher
and impeller (shown in cross-section in Figure 5 and in a
cross-section in Figure 5 and in a cross-section on A-A of
Figure 2 in Figure 6) may be driven at the same speed or at
differing speeds by suitable drive shaft arrangement. A cut
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~3 (portion) of the media particles can be taken from the cyclone
classifier by eductor nozzle assembly S having an eductor
air input Sa. This material which would be the lighter, finer 30 portion can be taken to reiect, recycled, or if required as
an input to a cleaning, treating, or other utilization system.
The heavier portion of the material from the cyclone is taken
to a metering device preferably a screw device such as shown in
Figure 7. This is driven by a con~rollable motor drive (see
Figure 3). The metering screw is precisely machined and has
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1 32459 1
direct feed entry from the cyclone (via fluidizing and gravity)
through a large open throat and discharges directly into a
rotary metering pump. The metered material from the screw
which would be at a near atmospheric pressure is fed into
the rotary chamber pump driven by a controllable motor 8a.
This pump is shown in more detail in Figur~s 8, 9, 10, and 11.
As seen in cross section in Figure 8 and in top view in Figure 9,
the device comprises a cylindrical housing 15 having a top plate
16 and a bottom plate 17. An input port 18 which would be
connected to the output of the cyclone classifier via the metering
screw serves to introduce the particle material into the device.
A process air injection nozzle introduces fluidizing and
transporting air into the device and a fluidized process feed
is taken at nozzle 20. A rotating cylinder 21 containing a
series of chambers 22 as shown in Figure 10 is shaft mounted
inside housing 15. These chambers which are cylindrical in
shape are sealed top and bottom by a labrynth seal shown in
I detail in Figure 11 and these provide good sealing action
,~ without direct contact between the rotary cylinder and the
housing walls. As the rotary cylinder rotates each of the
chambers comes in turn under port 18 and is filled either fully
or partially as desired with th~ particle material. The chamber
then moves to a position under pressurized air inlet port 25
(see especially Figure 9) which raises the pressure in the
chamber to a first levelO Further pressure levels are introduced
in step-wise fashion as the chamber moves past ports 26, 27,
and 23 until it reaches port 19 where an increased pressurized
air input fluidizes and transports the material to the desired
i, output at port 20 (see Figure 8). The chambers then pass under
air outlet ports 29 and 30 which serve to drop the pressure to
~, the working level for the chambers when they pass to inlet port
~ 18. This pressurized air output may be reused by injecting
;` back into the system at suitable positions.
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Figuxe 12 illustrat~s the media preparation system
described above ln a complete particle blast cleaning and
treating system. The raw media supply is fed to crusher
32 having a fluidizing air input 33 from air source 34,
with the media particles passing through impeller 35, scroll
36 having air injection inputs 36a and 36b to cyclone
classifier 37. The fines portion is taken by eductor 38
and sent to recycle. The heavier portion of the particles
passes to metering screw 19 controlled by motor 39a and then
to rotary cylinder 40 which as described above sends a con-
trolled fluidized air and particle stream to fluidizer 41
having a pressurized air input from air source 34 via control
valve 44. The output air and particle stream from the
fluidizer are transported through line 42 to blast head 43
having accelerating air inlet nozzles 43a and 43b supplied
from the air source via lines 45 and 46 and controlled by
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;1 control valves 47 and 48~ This system provides complete
control of all the parameters required to give excellent
cleaning and treating action to a wide range of surface
conditions.
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It will be readily apparent to a person skilled in the
art that a number of variations and modifications can be
made without departing from the true spiri~ of the invention
which will now be pointed out in the appended clalms.
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