Note: Descriptions are shown in the official language in which they were submitted.
-~32~7~ 13597
BACKGROUND OF TH~ INVENTION:
This invention relates to a method and apparatus
for particle blast cleaning and treating of surfaces.
Sand blast technoloqy has been well developed and
widely used and acceptable cleaning results are able to be
obtained with crude systems and low cost abrasives. However
many types of surfaces of materials are not able to be
cleaned in this way because of damage to the surfaces and
possible effect on the integrity of the objects being
cleaned . Also, aside from environmental considerations
nearby objects are often inconvenienced or damaged by
over spray effects and clean-up is normally time consuming
and costly. Over the last few years the use of other abra-
sive materials such as plastic chips and frozen liquids
such as water (H20) ice, dry ice (C02), and pellets of
; 15 these mixed with certain chemical materials have been
` proposed for use in air blast technology to clean, wash,
decontaminate or otherwise treat surfaces of a wide range
of objects and materials.
The following are patents that show methods and
apparatus using these types of materials:
British Patent No. lr397,102 filed March 22, 1972
Published June 11, 1975
U.S. Patent No. 4,703,590 issued November 3, 1987
U.S. Patent No. 4,769,956 issued September 13, 1988
French Patent App. 80-03099 filed February 8, 1980
Publication No. 2,475,g25
French Patent App. 80-24375 filed November 17, 1980
Publication No. 2,494,160
~ritish Patent App. GB 2,171,624A Published September
3, 1986
Japanese Public Dlsclosure No. 97533 dated August 2,
1975
U.S. Patent No. 3,676~963 issued July 18, 1972
All of these patents disclose abrasive particle blast
systems involving rudimentary apparatus for preparing the
pellets and controlling th~ size, shapes, and condition of
these in relation to the air blast flow streams.
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BRIEF SUMMARY OF THE I~VENTION: ~ 3 2 1 ~ 7
.
It is an object of the present inven-tion to provide a
method and apparatus for cleaning and treating surfaces of
objects and materials using particles wherein the various
parameters such as particle size, shape, amounts and ratios,
and air blast flow velocities are under precise control over
wide ranges such that different surface types and conditions
can be cleaned or treated more effectively, convenien-tly and
economically.
This and other objects of the invention are achieved
by a method of particle blast cleaning and treating of surfaces
comprising metering a flow of particles from a supply,
~^ positively feeding the particle flow from the metering stage
into a fluidizer, fluidizing the particle flow with a controlled
metered flow of fluid taken from a pressurized fluid source,
pneumatically conveying a particle-fluid stream from the fluid-
izing stage to a blast head, and controlling the fluid flow
rates and -the particle amount rates and the mass flow ratios
of the flows precisely and over fairly wide ranges to provide
a particle blast cleaning and treating effect for a wide
range of surfaces and objects.
The objects of the invention are also achieved by
apparatus for effec-ting the above method s-teps.
BRIEF DESCRIPTION OF DRAWING:
FIGURE 1 is a flow diagram of a particle blast cleaning
and treating system according to an embodiment v~ the invention
wherein a wide variety of material including frozen liquids
may be used.
FIGURE 2 is a flow diagram of a particle blast system
similar to that of ~igure 1 but with acceleration input to the
blast head.
FIGURE 3 is a flow diagram of a blast cleaning and
treating system using a batch supply of particles with con-
ditioning of media particles and air supply.
FIGURE 4 is a flow diagram of a complete system using
a continuous production of a frozen liquid such as lH20~ as
the treating material and with integrated system control.
. ~
~3~ 132~78
FIGURE 5 shows typical e~uipment for a bateh media
input system according to the flow diagram of Figure 1.
FIGURE 6 is a eross-seetion of the fluidizer accel-
erator assembly as used in the apparatus shown in Figure 5.
FIGURE 7 is a cross-section of a single stage aceel-
erator/blast head nozzle as used in the apparatus shown in
Figures 3 and 4.
FIGURE 8 is a cross-seetion of a blast head consisting
oE a two stage accelerator, nozzle set as used in the appar-
atus shown in Figures 3 and 4.
FIGURE 9 is a broken sectional view of the system in a
mobile unit.
FIGURE 10 is a diagrammatic view of the air supply
system.
FIGURE 11 is a diagrammatic view of the refrigeration
and ice supply system.
DESCRIPTION OF EMBODIMENTS OF THE INVENTION:
-
Figure 1 is a flow diagram of a blast system using a
media including frozen liquids where the input particles are
fed either from a media fresh or recycle supply to an
atmospherie hopper 2. From the hopper the material is fed
by batch to surge tank 3. Compressed air (or other suitable
gases) is taken from supply 1 and after passing through
filter la, dryer lb having a condensate trap lc to conden-
sate return line ld, and inlet val~e le provides a fluidizing
air supply via surge fluidizer valve 3a eontrolled by press-
ure meter 3b to the surge tank. The media materials then go
to metering device 4 which would typieally be a scroll
positive displaeement pump driven by variable speed motor
4a and eontrolled from computer station 7 to provide a
precisely controlled input to fluidizer/accelerator 5.
This latter also has pressurized air inputs via air flow
control valve 5a controlled from computer station 7 and
fluidizer air control valve 5b connected via pressure
control 5c to pressure control 3b and computer 7 through
flow indication and controller 7a to precisely control the
rate amounts and ratios of the air and treating particle
streams. Output from the fluidizer/accelerator is conveyed
pneumatically to blast nozzle 6.
'
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132~ ~7~
Figure 2 is a blast system similar to that of Figure 1
but where the metering device provides controlled media at a
~ pressure consistent with higher pressure of the fluidizer 5.
Fluidizer 8, control valve 8a assist in pneumatically trans-
porting the media from hopper 2 to metering device 4. Fluid-
izer 5 provides only enough energy to transport the particle
mi~ through the hose without undue damage of the media part-
icles such as ice, plastic chips, nut shells, glass beads,
sand, gritty materials, etc. Acceleration energy is added at the
blast head 6 via additional controlled air. This air input is
; taken from the air supply via air flow control valve 9
controlled by flow indicator and controller 9a connected to
computer 7. If desired additives such as cleaning and
chemical agents may be introduced into the system by adding to
- the particle media feed as shown.
Figure 3 is a more detailed flow diagram of the system
with air as the propellant and ice as the treating media. Air
from a compressed air source 1 is passed through af-tercooler 17
to reservoir 18 and from there through air filter l9a to dryer
20. The aftercooler, reservoir and dryer are connected through
traps 21a, 21b, and 21c to condensate return line 22. Air
under pressure from the reservoir and dryer is fed through air
filter l9b to air flow control valves 23, 24, and 25 with the
flow rates being measured and controlled by flow meters 23a/
24a, and 25a. Ice from a batch supply source 2a is fed into
hopper 2 whose output feed is controlled by variable speed motor
47 and controlled air supply from the compressed air sources
via control valves 2c and 2d.
Ice from the hopper is passed to ice crusher/sizer
29 with the crushed iC2 passing to surge tank 30 and then to
metering apparatus 31 which positively feeds controlled amounts
of ice crystals or pellets to fluidizer 32 where they are com-
bined and fluidized with a pressurized air flow from control
valve 23. Line 33 carries the fluidized air and treating ice
particles into blast head 34 where this flow has injected into
it at entry points 34a and 34b two high velocity air streams
from control valves 24 and 25 via lines 36 and 37 resulting in
a treating particle blast to a work piece for cleaning purposes.
~ ... .. . . .
- 1321~7~
Crusher/sizer 29 is connected to variable speed drive
47, cooled by the refrigerant supply 42, crushes and sizes
the ice Erom the hopper to a controlled working size after
which it is fed into surge tank 30. Pressurized air input
via control valve 48 acts with control valve 49 as an auto-
matic purge system sending reject fines and purge air to
- output line 50. Ice is fed from the surge tank into metering
device 31 which would typically be a scroll positive dis-
placement pump connected to a variable speed drive motor
52 to positively feed a measured supply of ice into fluid-
. izer 32.
Figure 4 is similar to Figure 3 but shows a completesystem including ice making apparatus and a computerized
control system. Water is fed to precooler/deaerator 26
~: 15 and then to ice maker 27. If desired chemicals may be added
to the feed water via line 28. Other media may be added by
; simi.lar process systems for multiphase treating flows. Pre-
coo].er 26 is operated through valve 40 controlled by auto-
matic temperature control 41 to a refrigerant supply 42
having a temperature control 43. The rate of i.ce making in
ice maker 27 is controlled by variable speed drive 44 which
is supplied according to demand of metering rates set by
metering device 52 which is itself the master control point
Coolant demand is through valve 45 controlled by automatic
temperature control 46 to the refrigerant supply 42. The
surge tank 30 also cooled by the refrigerant source had its
level monitored by the level control 51 which controls
variable speed drives 44 and 47 to main-tain the appropriate
ice supply levels. Valves 48 and 49 serve to purge rejects~
As in Figure 3 ice from the surge tank is fed to metering
device 31 and to fluidizer 32 which provides an air/ice
supply via line 33 to blast head 34.
The complete system is monitored and controlled from
master control panel 60 and remote control panels 61 and 62
with connections to -the various air and ice flow control
valves and surge tank level controls.
In essence the overall s~stem is arranged to prepare
treating material in suitable form and to monitor and control
. .
.
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the mass flows of the air and particle flows and the ratios
of these extremely precisely and over fairly wide range such
that a wide spectrum of material surfaces can be treated
without damage to these surfaces and with bestoverall effect.
The system provides a positive, metered controlled flow of
both air and media with propellant energy added at appropriate
points resulting in less energy loss and media damage.
Figure 5 shows the media feed equipment for a batch
pressure pot blast system as shown in Figure 1. The particle
media is fed into hopper 65 and then to surge vessel 66. A
compressed air input is taken from a supply through air flow
control valves 67 which is item 7a of Figure 1 and 68 which
forms items 5a and 5b of Fiyure 1 into fluidizer 69. The
feed passes to metering pump 70 which is item ~ of Figure 1
connected to variable speed drive (4a of figure 1) and to
fluidizer/accelerator 71 having compressed air inputs 71a
and 71b. Output from the Eluidizer/accelerator is piped to
the blast head.
Figure 6 shows the fluidizer/accelerator assembly as
shown in Figure 5 (Item 71). Controlled, metered blast head
media from the metering pump enters at 72 and is accelerated
by a controlled, metered air input to jet nozzle 73. Fluid-
izing air (metered and controlled) is injected at 7~1 and
further fluidizes and accelerates the air/particle media
- 25 stream with the output being piped -to the blast head.
Figure 7 shows a single stage fluidizer/accelerator of
a type that could be used in Figure 2 (Item 6) with the non
or partially fluidized media stream (metered and controlled)
entering at 75 and a metered, controlled air stream injected
at 76. This flow passes into annular distributing chamber
77 through a gap formed by pressure O-ring seal 78 into the
venturi shaped interior to form a fluidizing, accelerating
stream. The output provides a fluidized and accelerated air
stream, controlled and metered to a required degree for trans-
port, conveying and work energy to the blast head.
Figure 8 is a two stage accelerator/fluidizer similar
to that of Figure 7 bu-t for ~ore precise control of conditions,
having a second air input at 76a passing into the interior
.
~7~ ~2~8
via annular distributing chamber 77a and the gap formed
by O-ring seal 78a. This device ~orms the blast heads shown
in Figures 3 and 4 ~Items 34, 34a and 34b).
A mobile version of the system is shown in Figure 9
with the air supply portion in Figure 10 and the refriger-
ation and ice supply portion shown in Figure 11. Power
plant 80 drives compressor 81 drawing ambient air frolll air
intake 82 and sending it via line 83 to air cooler 84.
The air is then passed through condensate trap 84a to air
- 10 xeservoir 85 having condensate trap 86, through air filter
~7 and dryer 88 and through air filter 89 to control valves 90.
The power plant also drives refrigeration plant 91
to provide refrigerant for ice making and cooling the ice
process components. Water from tanks 92 passes through
deaerator 93, and precooler 94 to ice maker and sizer g5.
The ice is crushed in crusher 9~ and passed to metering
device 97 and fluidizer 98 which also has an air input from
control valves 90 to direct a fluidized ice-air stream via
line 99 to the blast heads. As shown, two compressed air
Elows are taken from valves 90 via lines 100a and 100b.
Other elements shown are refrigerant cooler 101, engine
cooler 102, fuel tank 103, control room 104 and control panel
105 (Figure 10).
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