U.S. patent application number 17/620940 was filed with the patent office on 2022-09-22 for apparatus for abrasive cleaning.
The applicant listed for this patent is Jason McKenna. Invention is credited to Jason McKenna.
Application Number | 20220297264 17/620940 |
Document ID | / |
Family ID | 1000006436961 |
Filed Date | 2022-09-22 |
United States Patent
Application |
20220297264 |
Kind Code |
A1 |
McKenna; Jason |
September 22, 2022 |
APPARATUS FOR ABRASIVE CLEANING
Abstract
An apparatus for abrasive cleaning includes an abrasive media
storage vessel for storing a supply of abrasive media at ambient
pressure. The storage vessel has an outlet for supplying abrasive
media into a first gas stream at a first gas pressure in a first
flow passage, the first flow passage supplying a mixture of gas and
abrasive media to an outlet nozzle. A main gas stream communicates
with the outlet nozzle via a second flow passage at a second gas
pressure, the second gas pressure being higher than the first gas
pressure. The mixture of gas and abrasive media from the first flow
passage is entrained into the main gas stream from the second flow
passage in or downstream of the outlet nozzle.
Inventors: |
McKenna; Jason; (Holywood,
County Down, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
McKenna; Jason |
Holywood, County Down |
|
GB |
|
|
Family ID: |
1000006436961 |
Appl. No.: |
17/620940 |
Filed: |
March 24, 2020 |
PCT Filed: |
March 24, 2020 |
PCT NO: |
PCT/EP2020/058157 |
371 Date: |
December 20, 2021 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B24C 5/04 20130101; B24C
7/0061 20130101 |
International
Class: |
B24C 5/04 20060101
B24C005/04; B24C 7/00 20060101 B24C007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2019 |
IB |
PCT/IB2019/055261 |
Claims
1. An apparatus for abrasive cleaning comprising an abrasive media
storage vessel for storing a supply of abrasive media at ambient
pressure, said storage vessel having an outlet supplying abrasive
media into a first gas stream at a first gas pressure in a first
flow passage, said first flow passage supplying a mixture of gas
and abrasive media to an outlet nozzle, a main gas stream
communicating with said outlet nozzle via a second flow passage at
a second gas pressure, the second gas pressure being higher than
the first gas pressure, whereby the mixture of gas and abrasive
media from said first flow passage is entrained into the main gas
stream from said second flow passage in or downstream of said
outlet nozzle.
2. The apparatus of claim 1, wherein the mixture of gas and
abrasive media from said first flow passage is entrained into the
main gas stream from said second flow passage within said outlet
nozzle.
3. The apparatus of claim 1, further comprising a first venturi in
said first flow passage adjacent an outlet of said storage vessel
whereby abrasive media from said storage vessel is entrained into
the first gas stream.
4. The apparatus of claim 3, wherein abrasive media from said
storage vessel passes into a throat of said first venturi under
gravity.
5. The apparatus of claim 4, further comprising a control valve for
controlling the flow of abrasive media from said storage vessel
into said throat of said first venturi.
6. The apparatus of claim 1, further comprising a second venturi
located in or upstream of said outlet nozzle, wherein the mixture
of gas and abrasive media from said first flow passage is entrained
into the main gas stream from said second flow passage in said
second venturi.
7. The apparatus of claim 1, further comprising a pressure
regulator for controlling the first and second gas pressures,
wherein the first and main gas streams are supplied from a common
source of compressed gas.
8. The apparatus of claim 7, wherein the first and main gas streams
comprise air streams from a common source of compressed air.
9. The apparatus of claim 1, further comprising a water source for
selectively adding water into the main gas flow.
10. The apparatus of claim 9, wherein said outlet nozzle comprises
one or more water injection ports, and wherein water is selectively
added to the main gas flow in said outlet nozzle from a water
supply via said one or more water injection ports.
11. The apparatus of claim 10, further comprising a water control
valve for controlling the supply of water to said one or more water
injection ports.
12. The apparatus of claim 10, wherein said one or more water
injection ports are associated with a non-return valve.
13. The apparatus of claim 1, wherein said storage vessel includes
a flow control valve in an outlet at a lower end of said storage
vessel, said flow control valve for controlling the passage of
abrasive media into the first flow passage.
14. The apparatus of claim 13, wherein said flow control valve
comprises a normally open pinch valve.
15. The apparatus of claim 1, further comprising one or more gas
vents at outlet nozzle for venting excess pressure from the first
gas stream as it enters the main gas stream.
16. The apparatus of claim 15, wherein said one or more gas vents
communicate with an outlet passage of said outlet nozzle downstream
of said one or more gas vents.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a .sctn. 371 national stage of
International Application PCT/EP2020/058157, filed Mar. 24, 2020,
which claims priority benefit to International Application
PCT/IB2019/055261, filed Jun. 21, 2019, both of which are hereby
incorporated herein by reference in their entireties. The present
application is also a continuation-in-part of International
Application PCT/IB2019/055261, filed Jun. 21, 2019.
FIELD OF THE INVENTION
[0002] The present invention relates to an apparatus for abrasive
cleaning wherein an abrasive media from a storage vessel is
entrained into a fast flowing gaseous stream, which carries the
abrasive along a hose or conduit to an outlet nozzle, whereby the
abrasive media can be applied to a surface entrained in said fast
flowing gaseous stream via the outlet nozzle.
BACKGROUND OF THE INVENTION
[0003] At present, a variety of different types of equipment are
available for abrasive cleaning for a wide variety of industrial
applications including wall and stone cleaning, tank and container
cleaning, ship or oil rig maintenance, or other industrial
applications where a finishing process may be required such as in
the forging or casting of metal objects, or simple surface
preparation for further processing, for example, painting.
[0004] In the abrasive blast cleaning industry a wide variety of
abrasive media may be used for sand or shot blasting including a
variety of different grades of sand or grit, steel shot, glass
beads or many of a wide variety of other available abrasive
materials. Moreover, blasting may take place in a "wet" and a "dry"
manner. In the case of "wet" blasting, an abrasive media is mixed
with water and this mixture is sprayed under pressure. In the case
of "dry" blasting, the blasting medium is conducted to the spray
nozzle in dry condition and sprayed there under pressure, the
pressure typically being obtained through a feed of compressed
air.
[0005] In existing types of portable blast cleaning machines, the
abrasive media is stored under pressure in a storage hopper from
which the abrasive under pressure may be introduced into a fast
flowing high pressure airstream, which carries the abrasive along a
suitable "blast" hose, which is terminated in a delivery nozzle.
The storage hopper has to be pressurised to avoid the high pressure
airstream from flowing back into the hopper and to deliver the
abrasive media into the airstream by differential pressure.
[0006] The need for a pressurised storage hopper for the abrasive
media requires complex pressure regulation equipment and makes
refilling and inspection of the storage hopper difficult.
Furthermore, the passage of the abrasive media entrained in the
high pressure airstream through the blast hose leads to rapid wear
of the blast hose and frequent replacement as well as safety
concerns for the operator. An example of such known portable blast
cleaning machines can be seen in WO 2018/055012.
SUMMARY OF THE INVENTION
[0007] According to the present invention there is provided an
apparatus for abrasive cleaning comprising an abrasive media
storage vessel for storing a supply of abrasive media at ambient
pressure, the storage vessel having an outlet supplying abrasive
media into a first gas stream at a first gas pressure in a first
flow passage, the first flow passage supplying a mixture of gas and
abrasive media to an outlet nozzle, a main gas stream communicating
with the outlet nozzle via a second flow passage at a second gas
pressure, the second gas pressure being higher than the first gas
pressure, whereby the mixture of gas and abrasive media from the
first flow passage is entrained into the main gas stream from the
second flow passage in or downstream of the outlet nozzle.
[0008] In one embodiment the mixture of gas and abrasive media from
the first flow passage is entrained into the main gas stream from
the second flow passage within the outlet nozzle.
[0009] A first venturi may be provided in the first flow passage
adjacent an outlet of the storage vessel whereby abrasive media
from the storage vessel is entrained into the first gas stream.
Abrasive media from the storage vessel may pass into a throat of
the first venturi under gravity. A control valve may be provided
for controlling the flow of abrasive media from the storage vessel
into the throat of the first venturi.
[0010] The mixture of gas and abrasive media from the first flow
passage may be entrained into the main gas stream from the second
flow passage in a second venturi located in or upstream of the
outlet nozzle.
[0011] The first and main gas streams may be supplied from a common
source of compressed gas, pressure regulator or regulating means
being provided for controlling the first and second gas pressures.
The first and main gas streams may comprise air streams from a
common source of compressed air.
[0012] The apparatus may further comprise a water source or means
for selectively adding water into the main gas flow to selectively
provide dry or wet blasting. Water may be selectively added to the
main gas flow in the outlet nozzle from a water supply via one or
more water injection ports provided in the outlet nozzle. The
supply of water to the one or more water injection ports may be
controlled by a water control valve. Each of the one or more water
injection ports may be associated with a non-return valve.
[0013] Optionally, the storage vessel includes a flow control valve
in an outlet at a lower end of the storage vessel for controlling
the passage of abrasive media into the first flow passage. The flow
control valve may comprise a normally open pinch valve.
[0014] The outlet nozzle may be provided with one or more gas vents
for venting excess pressure from the first gas stream as it enters
the main gas stream. The one or more gas vents may communicate with
an outlet passage of the outlet nozzle downstream of the one or
more gas vents.
[0015] These and other objects, advantages and features of the
invention will become apparent upon review of the following
specification in conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] An apparatus for abrasive cleaning in accordance with
embodiments of the present invention will now be described, by way
of example only, with reference to the accompanying drawings, in
which:--
[0017] FIG. 1 is a front elevation view of an abrasive cleaning
apparatus in accordance with an embodiment of the present
invention;
[0018] FIG. 2 is a side sectional view of the abrasive cleaning
apparatus taken along line A-A in FIG. 1;
[0019] FIG. 3 is a detailed sectional view of the abrasive media
eductor of the apparatus of FIG. 1;
[0020] FIG. 4 is a sectional view of an outlet nozzle of the
apparatus of FIG. 1;
[0021] FIG. 5 is a sectional view of an outlet nozzle in accordance
with an alternative embodiment of the present invention; and
[0022] FIG. 6 is a perspective sectional view of the outlet nozzle
of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] In a first embodiment of the present invention, as
illustrated in the drawings, an apparatus for abrasive cleaning
utilizes an unpressurized abrasive storage hopper 2 mounted on a
wheel frame 4. An abrasive media eductor 6 is mounted below the
hopper 2 communicating with an abrasive media outlet at a lower end
of the storage hopper 2 and adapted to mix abrasive media gravity
fed from the storage hopper 2 into a relatively low pressure first
flow of air in a first air flow passageway 8.
[0024] A venturi induction outlet nozzle 10, such as that shown in
either FIG. 4 or FIG. 5, is adapted to mix the first flow of air
and the abrasive media entrained therein with a main flow of air
supplied by a main air flow passageway 12 at a second and much
higher pressure than the first flow of air, such that the abrasive
media can be projected at a surface from the outlet nozzle 10 in
the combined first and main flows of air for cleaning, profiling or
surface preparation.
[0025] As shown in FIGS. 4 to 6, the main and first air flow
passageways 8,12 converge within the outlet nozzle 10 through
converging and diverging flow paths, causing the first flow of air,
carrying the abrasive media, to be entrained and mixed into the
main flow of air. Therefore the mixing of the abrasive media and
the high pressure flow of air required to achieve the desired
blasting effect only takes place in the outlet nozzle 10, reducing
wear of the apparatus and allowing the abrasive media storage
hopper to be unpressurised.
[0026] The apparatus may be adapted to operate dry when required
through blast selection toggle switches 14 located on a main
control panel 16, or wet as required similarly, wherein water from
a water source can be added to the air flow in or upstream of the
outlet nozzle 10. For example, when wet blasting is selected the
control panel 16 may activate a water pump to inject water under
pressure into the outlet nozzle.
[0027] When wet blasting, water may be injected directly into the
outlet nozzle 10 via one or more water injection ports 20 in the
outlet nozzle 10, to ensure a slurry mix is created prior to
exiting the outlet nozzle 10. Injecting water at the outlet nozzle
10 may eliminate blockages occurring when mixing air, water and
abrasive as the three elements are kept separate until exiting the
outlet nozzle 10.
[0028] The feed of abrasive media from the storage hopper 2 into
the eductor 6 may be controlled by a control valve 18, such as a
pinch valve. The control valve 18 may be controlled in a timed
sequence, optionally via a pneumatic timer module located in the
control panel 16. This abrasive media feed timing may be adjustable
at the control panel from 0 to 60 seconds, such as (but not limited
to) 5 seconds.
[0029] When dry blasting, post wet blasting, the apparatus may be
adapted to purge the main air flow passage with air for an
adjustable time of up to 60 seconds, and may be pre-set at (but not
limited to) 5 seconds, with dry air only, primarily to remove any
moisture that may remain in the main blasting hose. Dry abrasive is
then reintroduced to the blast stream when the timer module feeds
air to the storage hopper control valve (for example pinch valve
18), opening the valve 18 again to reintroduce dry abrasive
particles to the induction air stream, of which dry blasting is
then activated without significant moisture in the lines allowing
the apparatus to revert back to dry media expulsion and thus dry
blast mode.
[0030] When wet blasting, water injection may be monitored via a
water pressure sensor, for example using a normally closed
pneumatic valve. This valve may be adapted to open, for example via
a stainless steel compression spring loaded plunger, only when
sufficient water injection pressure is present from the water pump,
such as (but not limited to) more than 5 bar pressure.
[0031] If insufficient water injection pressure is present, the
system will shut down the flow of abrasive media by ceasing air
supply to the pinch valve 18, ceasing the supply of abrasive whilst
in wet blast mode, primarily for safety in spark controlled
environments to prevent the machine effectively defaulting to dry
blasting mode if the water pump were to fail for example. If this
happens the user can then recheck/reconnect water supply connection
at the control panel 16, to continue wet blasting, or select dry
blasting to continue without water present. An air powered water
pump may be used to pressurise the water outlet from either an
unpressurized or pressurized water source directly to the outlet
nozzle 10 water injection port 20.
[0032] A non-return valve 22 (see FIG. 5) may be located at the
water injection port 20, with a cranking or opening pressure of 5
bar for example, rated up to (but not limited to) 16 bar. This may
ensure that water is only injected when the wet-blast mode is
selected and the "Deadman handle" is activated to activate the
water pump thus enabling water injection.
[0033] A main benefit of the apparatus is that it does not use a
pressure vessel to store the abrasive media or deliver through
differential pressure within a pressure vessel as in an ordinary
pressure sand blast pot. Instead, an unpressurized storage hopper 2
is used that the user can fill with all types of blasting media,
and see the fill level visually and also monitor abrasive usage
whilst in use, eliminating the need for pressure equipment
directives and regulations required for manufacturing pressure
vessel equipment, and eliminating routine vessel inspection and
maintenance.
[0034] Traditionally a pressure vessel is used on the principals of
differential pressure to force abrasive into the blasting stream to
overcome back pressure within the main blasting line, whereas with
the apparatus disclosed herein, abrasive is induced or sucked into
the educator 6 in a relatively low pressure air flow and then
introduced into a high pressure air flow at a secondary induction
point within the outlet nozzle 10. Having a separate main air flow
via the outlet nozzle 10 in conjunction with the lower operating
pressure eductor 6 creates a push-pull method of abrasive induction
into the air/blast stream by venturi effect causing suction of
abrasive particles from the storage hopper 2.
[0035] An air pressure feed to the converging inlet of the eductor
6 may be set at 2 bar, for example, but is not limited to this
pressure. Abrasive is induced by forced induction from the eductor
6 in combination with the higher velocity air passing through the
outlet nozzle 10, then entering the abrasive induction feed located
on the outlet nozzle. This method of abrasive pickup and delivery
prevents the stored abrasive from being mixed with stationary
compressed air within a typical pressure blast pot storage vessel,
which ordinarily can cause blockages due to moisture from
compressed air input.
[0036] Full pressure and flow are obtained with the use of the main
large bore full flow main flow passageway or blasting tube, which
carries unsuppressed full pressure and full flow air directly to
the converging nozzle inlet within the outlet nozzle 10, wherein
the main air flow is mixed with the first air flow carrying the
abrasive media.
[0037] The educator 6 draws abrasive media directly from the
storage hopper 2 via suction whilst wet or dry blasting. Abrasive
media is induced into the first flow of air in the first flow
passageway via negative static pressure and venturi effect. The
delivery of abrasive media may be controlled by a pressure
regulator on the main control panel 16, which directly controls the
opening of the pinch valve 18. This enables the use of an
unpressurized storage vessel 2 to hold stored abrasive media, which
in turn enables the use of very fine abrasives without issues of
moisture build-up mixing with stored abrasive, because the main
flow of compressed air flows directly through the main flow
passageway, bypassing the abrasive media storage vessel 2.
[0038] Activating compressed air through the system may be operated
through a "Deadman switch" located at the outlet nozzle 10, which
may be connected to the main pneumatic circuit and ultimately a
large bore pneumatic solenoid valve which may open and close air
through the system on activating the "Deadman switch". Likewise,
this apparatus may be deactivated at any time by activing a stop
control located on the control panel 16.
[0039] Water Feed Monitoring:
[0040] The water monitoring systems may consist of a brass plunger
valve with an inlet and outlet port, coupled to a pneumatic plunger
valve, which is opened and activated when water injection to the
pump outlet has pressure of more than 5 bar present, for example,
but not limited to this pressure, whilst the water pump is pumping
water in wet blast mode. The circuit may be connected to the
airline controls of the abrasive media storage hopper 2 pinch valve
18, so that if water should cease to be present in wet-blast mode,
abrasive media flow will immediately cease also, preventing the
system running dry unintentionally. This is a safety feature for
wet-blasting in spark controlled environments; water injection rate
of flow can be adjusted by adjusting the water dose valve located
on the main control panel 16.
[0041] Storage Hopper:
[0042] The storage hopper 2 may be manufactured from either metal
or plastic. The storage hopper is an unpressurized vessel and may
include a built-in sieve and lid. The lower end of the storage
hopper 2 may include a 60-degree cone angle to ensure smooth flow
of abrasive to the educator 6. The hopper 2 is maintenance free and
corrosion resistant. Larger or smaller volumes of hopper can be
used with the same working principles with no limit to
capacity.
[0043] Outlet Nozzle:
[0044] The outlet nozzle 10 may be manufactured from any suitable
non-ferrous material, and may have a tungsten carbide liner within
the diverging nozzle part thereof to protect against abrasive wear.
The diverging nozzle part creates venturi suction when in use to
draw abrasive media into the main flow of air. Air feed pressure to
the outlet nozzle may adjustable from 5 to 100 psi, for example,
but is not necessarily limited to these pressures. The outlet
nozzle 10 may utilise interchangeable nozzle inlet 24 and outlet
parts 26 with varying sizes. The outlet part 26 of the nozzle 10
can be interchanged to vary the output patterns effectively with
different air input pressures and flow rates. An air vent 28 may be
provided in the walls of the outlet nozzle 10 to relieve excess
pressure build up through via angled hole at an opposing direction
to the direction of abrasive media delivery induction point. Such
air vent 28 may be provided to relieve excess air pressure existing
from the abrasive eductor line feed. Such excess pressure may be
relieved via such air vent 28 and may be reintroduced at a
downstream point of the outlet nozzle with the purpose of
preventing back pressure at the eductor 6.
[0045] Eductor:
[0046] The eductor 6 (see FIG. 3) may be located below the abrasive
media storage hopper 2, communicating with the hopper 2 via the
pinch valve 18. The pinch valve may be adapted to induce abrasive
media and conveys it directly to the eductor 6 by mains air
pressure fed by a small bore solenoid. Air pressure supplied to the
eductor as the first flow of air may be set at around 2 bar at a
flow rate of around 4.3 litres per second (9 cubic feet per
minute), for example, but not limited to this pressure or flow
rate. The eductor 6 conveys abrasive media via a "pull" method,
forced by air through an abrasive flow tube via a push method and
then again induced directly at the inductor nozzle (see FIG. 3) via
induction or venturi effect via a pull method. This provides a very
reliable method of abrasive media pickup and delivery for abrasive
blasting. As illustrated in FIG. 3, a portion of the main air flow
passage 12 is mounted below the educator 6. A port 30 may be
provided in the main air flow passage 12 which may be used for a
pressure sensor or to inject water.
[0047] The eductor 6 may be manufactured from cast and machined
aluminium or stainless steel with ceramic or tungsten carbide wear
liners internally to protect against abrasive wear of internal
surfaces from abrasive particles conveyed under air pressure.
[0048] Storage Hopper Pinch Valve:
[0049] The pinch valve may be manufactured from stainless steel
and/or aluminium, featuring a normally closed inner rubber sleeve,
the pinch valve is only opened when activing blasting modes, and
the opening force and thus the flow of abrasive can be adjusted by
adjusting the abrasive dose valve located on the machines main
control panel, the abrasive pinch valve controls the rate of
abrasive flow into the venture induction valve by adjusting the
size of the opening from 0-25 mm but not limited to these sizes,
larger or smaller orifice sizes are optional. The abrasive flow may
be adjusted via an air pressure regulator, which either opens the
rubber sleeve for increased flow, or closes for decreased flow of
abrasive. The pinch valve 18 is normally closed, meaning when not
in use the flow of abrasive media is ceased. When air is fed to the
pinch valve, for example activated by the Deadman handle, the valve
18 then opens if the blasting mode selected is dry-blast or
wet-blast.
[0050] The invention is not limited to the embodiments described
herein but can be amended or modified without departing from the
scope of the present invention as defined by the appended claims as
interpreted according to the principles of patent law including the
doctrine of equivalents.
* * * * *