Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
_IELD OF THE INVENTION
This invention relates to air p~rifying apparatus, and
more particularly to a form of apparatus useful for treatment of
contaminated air or smoke generated as a result of a metal
~orking operation such as welding.
BACKGROUND OF THE INVENTION
Welding operations generate substantial amounts of
contaminant gases, exhausts, smoke and the like, as well as
substantial amounts of air-borne contaminant particles. For the
comfort and safety of the welding operator, it is desirable to
conduct the generated smoke and contaminated gases away from the
location of the welding operation, continuously as the welding
operation proceedsu Nevertheless, the smoke and f~mes so
generated are obnoxious, and need to be purified, or
alternatively conducted to a location at which they are
unobjectionable and preferably harmless.
Since welding operations are commonly conducted at a
variety of fixed locations, using portable welding tools and
apparatus, any devices useful in receiving and purifying the
fumes and smoke generated as a result of a welding operation
should also be small and portable, preferably at least as easily
portable as the welding apparatus itself. Moreover, it is of
course desirable that any such apparatus should be kept as
simple and economical to manufacture and maintain as possible.
- 2 - ~ ~
i235
SUM~ARy OF THE INVENTION
It is an object of the present invention to provide a
simple, portable apparatus which will eEficiently purify smoke
and fumes generated as a result of a welding operation~
It is a further objection of the present invention to
provide such an apparatus which will efficiently remove
suspended solid particles from such smoke and fumes.
Other objects and advantages of the present invention
will be apparent from the following description.
The present invention provides an apparatus especially
useful in treating smoke and fumes generated as a result of a
welding operation, which treats the gases by a combination of
centrifugal separation and liquid absorption of contarninants.
The contaminated gas from the location of the welding operation
is drawn by means of a blower through a gas flow conduit, which
extends through a plurality of serially arranged chambers. In
the first chamber, a circulatory motion is induced into the gas
flowing through the conduit, and then the gas encounters a
circumferentially disposed aperture, through which heavy
suspended or entrained particles and part of the gas exit, due
to centrifugal force induced by the circulatory motion.
Substantially clean air proceeds downstream through the conduit,
into a portion disposed in a second chamber. The portion of the
gas and particles which have exited through the circumferential
outlet pass into a water bath, in which the solid particles are
,'Z3S
trapped, with the thus puriEied air proceeding through the water
bath, into the second chamber, where it recombines with the
clean air in the conduit through an inlet aperture. As the thus
purified air exits from the downstream end of the gas flow
conduit, it encounters an impingement surface, suitably provided
with an adhesive coating, to which any remaining, fine entrained
solid particles adhere, leaving substantially pure air to issue
from the downstream end of the apparatus.
Thus by a combination of centrifugal separation and
liquid absorption, substantially clean air is produced, from the
welding location. The apparatus is simple and small, requiring
only very limited power means for operation, calling for
substantially no maintenance except for the periodic replacement
of the liquid bath, and small enough to be readily transportable
along with welding equipment.
Thus according to one aspect of the present invention
there is provided an apparatus for removing suspended solid
particles from a gas stream, and comprising an elongated gas
flow conduit means for causing gas flow therethrough;
swirl inducing means in said conduit adapted to cause
circulatory motion of the gas in said conduit about the
longitudinal axis thereof as the gas moves downstream through
the conduit;
an outlet aperture in said conduit downstream of said
swirl inducing means and extending around at least the major
iZ3~
part of the periphery thereof, to allow exit from the conduit of
the radially outwardly disposed portion of the gas and the
particles entrained therein;
an inlet aperture in said conduit, downstream of the
outlet aperture, the inlet aperture being in fluid communication
with the outlet aperture exteriorly of said conduit through the
intermediary of a liquid bath;
an impingement surface disposed adjacent to the
downstream end of said conduit and arranged to contact gas and
particles entrained therein upon issue from said downstream end
of the conduit;
said impingement surface having particle retaining
means provided thereon.
BRIEF REFERENCE TO THE DRAWINGS
FIGURE 1 is a diagrammatic cross-sectional view through
a preferred embodiment of an apparatus according to the
invention;
FIGURE 2 is a top plan view of the apparatus of FIG. 1,
with the top cover removed.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Preferably the apparatus according to the present
invention comprises a series of chambers, through which the gas
flow conduit extends. The liquid bath, preferably a water bath,
is provided in the first and second upstream chambers, arranged
so that the only fluid communication between the chambers,
exteriorly of the gas flow conduit, is through the liquid bath.
- 5
3~
Then, all the gas and particles which exit through the
peripherally disposed outlet aperture, in the first chamber,
pass into the water bath, wherein the solid particles are
absorbed. Turbulence inducing means are preferably provided in
the water bath, so as to ensure adequate mixing and agitation of
the gas and solid particles within the water bath to provide for
the necessary absorption of particles. The purified air issuing
from the water bath, in the second chamber, can then re-enter
the conduit through the inlet aperture disposed therein. The
size of the inlet aperture, in the second chamber, is preferably
adjustable, and can be set to ensure correct flow
characteristics. The movement of the gas and particles rrom the
first chamber, into the water bath and into the second chamber,
is arranged as a consequence of the action of the gas flow
causing means, which is preferably a blower located downstream
of the end of the gas flow conduit. In this way, the pressure
in the first, upstream chamber increases sufficiently to keep
the air issuing therein moving through the water bath.
The downstream end of the gas flow conduit is
preferably disposed in a third chamber, downstream of a second
chamber and fully isolated therefrom. Then, the impingement
surface can be formed by the lowermost wall of the third
chamber, located adjacent to the downstrearn end of the gas flow
conduit. Preferably also, the portion of the gas flow conduit
in the third chamber includes a reducer section, so as to
3~i
increase the velocity of the ~s flow issuing from the
downstream end of the conduit. In this way, any entrained fine
solid particles can be made to impinge upon the impingement
surface, to adhere to an adhesive or mastic coating preferably
provided thereon.
DETAILED DESCRIPTION OF THE SPECIFIC PREFERRED EMBODIMENTS
In the accompanying drawings, ln which like reference
numerals indicate like parts, there is shown an apparatus
according to the present invention generally comprising a
housing 10 sub-divided into a plurality of compartments,
serially arranged with respect to one another, through which
there passes a gas flow conduit 12. The upstream end 14 of the
gas flow conduit extends beyond the upstream end wall of the
first, upstream chamber 16~ At its upstream end, the conduit is
releasably connected to a flexible hose conduit 1~, leading to
the vicinity of the welding operation being conducted. Within
the first chamber 16 is an upstream conduit portion 20, provided
therein with a set of fixed vanes 22 constituting a swirl
inducing means, and having the form of four vanes defining an
aperture therethrough~ Thus as the air passing downstream
through the conduit section 20 issues from the vicinity of the
vanes 22, it has a circulating, swirl motion as well as a
downstream motion, with the result that heavy solid particles
entrained therein are moved by centrifugal force through the
outer periphery of the conduit section 20.
- 7 -
;
23~ii
Also within first chamber 16, the upstream section 20
oE conduit 12 communicates with the downstream section 2~ o~ the
conduit. I~he upstream end 26 of the downstream section of the
conduit is of smaller diameter than the upstream conduit portion
20, and is disposed concentrically therein, so as to leave a
circumerential gap or aperture 28, around the entire
circumference of the conduit, and through which heavier
entrained particles and portions of the gas stream adjacent the
outer walls of the conduit section 20 can exit, into the chamber
16.
Downstream of first chamber 16 is located a second
chamber 30, separated therefrom by dividing wall 32, through
which gas flow conduit 12 passes in sealing engagement. The
bottom portion of dividing wall 32 is provided with an integral
trough formation 34 with outwardly extending baffles 36 thereon,
and a plugged drain conduit 38 at the bottom portion thereof.
The bottom of trough portion 34 is disposed a short distance
above bottom wall 40 of the first and second chambers. Water 42
is disposed to form a water bath extending through the bottom
portions of the first and second chambers 16, 30. A filler
opening 44 is provided in the top wall of chamber 16, and a
drain plug 46 is provided in the bottom, front wall of chamber
16. Bottom-most wall 40 of the chambers 16, 30 slopes
downwardly towards drain opening 46, to facilitate drainage of
the apparatus and replacement of the water bath therein.
Above the level of the water 42 in second chamber 30,
there ar~ disposed splash plates 48, 50, to avoid excessive
splashing of water 42 from the water bath as air bubbles
therethrough during operation. In the section 24 of the conduit
12 passing through second chamber 30, above the level of the
splash plates, there is provided an inlet aperture 52,
surrounded by an apertured cylindrical sleeve 54, which can be
rotated on conduit section 24 so as to cover more or less of the
aperture 52 and hence adjust the size thereof.
The apparatus is provided with a third chamber 56,
disposed immediately downstream of the second chamber 30, and
separated therefrom by means of dividing wall 58. There is no
fluid communication between chambers 30 and 56 other than via
gas flow conduit 12, so that water 42 is excluded from the
interior of chamber 56 by means of dividing wall 58. The gas
flow conduit 12 within chamber 56 has a downwardly curving
section 60, of circular cross-section, which changes the
direction of flow of the gas therethrough from horizontal to
vertically downward. The lowermost end of conduit section 60
communicates with a reducer section 62, also o~ cross-section,
which in turn terminates at its downward end in a spreader
section 64, of generally triangular form as viewed from the
front. The outlet end of spreader section 64 is disposed at a
short distance above the bottom-most wall 66 of the fourth
chamber 56. This bottom-most wall constitutes an impingement
.95;~3~
surface upon which gases and any entrained, fine particles
issuing from the spreader section 64 at the lowermost,
downstream end of the conduit 12, must impinge at a velocity
enhanced by reducer section 62. Impingement surface 66 is
provided with a coating of mastic, adhesive material, e.g. tar,
so that particles issuing from the spreader section 6~ will
adhere thereto, and be removed from the gas stream.
The apparatus is provided with a fourth chamber 70,
located immediately downstream of third chamber 56, and
separated therefrom by a dividing wall 72. This dividing wall
72 terminates a short distance above impingement surface 66,
leaving a small, slotted communication 74 between third chamber
56 and fourth chamber 70, extending the full width of the
apparatus, through which purified gases can pass into fourth
chamber 70. A blower 76 constituting a means for causing gas
flow through the conduit 12 and the apparatus as a whole is
mounted on the downstream end wall 78 of the fourth chamber 70.
The blower is of conventional form, centrally apertured so that
gases can exit from fourth chamber 70 through the centre of the
blower 76. A fifth chamber 80 is provided downstream of fourth
chamber 70, communication therewith being provided through the
blower 76. On the top wall of chamber 80 is disposed an air
cleaner of conventional form, through which gases may pass into
the atmosphere, from fifth chamber 80.
-- 10 --
5~
Thus the apparatus according to the invention p~rifies
particle-laiden gases by means of both centrifugal separation
and liquid absorption. By means of the swirl inducing means 22
and peripheral outlet aperture 28 in the first chamber, an
initial separation of coarse, entrained particles from the clean
air is effected. These coarse particles are removed in the
water bath, with the gas separated therewith proceeding through
the water bath to be recombined with the clean air in the gas
flow conduit, through inlet aperture 52. The required
regulation to provide smooth operation and even flow can be
devised by adjustment of collar 54 to set the correct size of
inlet aperture 52. By providing for such re-combination of the
purified air from the water bath with the main stream of clean
air in the conduit, the apparatus can be driven by means of a
single blower 76. The provision of the baffles 36 on the trough
formation 34 ensures a sufficient degree of turbulence within
the water bath 42 to ensure thorough mixing of the gas stream
with the water and absorption of the solid particles thereby.
The inclusion of the adhesive or mastic coated impingement
surface 66 provides for a final separation of fine, entrained
solid particles from the gas stream. The efficiency of this
removal is enhanced by the inclusion of the reducer section 62,
to increase the flow velocity ready for impingement on the
surface .
In order to provide maximum flexibility and adjusting
flow characteristics for greatest efficiency, under a variety of
i23~
.. ~
flow conditions, the height of plate 72 can be made adj~stable,
so as to adjust the size of gap 7~, as well as making the si~e
of inlet aperture 52 adj~stable by means of collar 5~1.
The entire apparatus can be made light and portable,
e.g. of plastics material. Its overall length need not exceed
36 inches. It can be mounted on the conventional welding
trolley which a welder commonly uses for transportation of his
gas cylinder, tool, mask and the like. It can be operated with
the minimum of maintenance, requiring only a power source for
the blower, and the periodic draining of the water from the
water bath and refilling thereof.
Whilst a specific preferred embodiment has been
described in detail with reference to the accompanying drawings,
it will be appreciated that modifications and changes therein
can be made, within the skill of the art, without departing from
the scope and spirit of the invention. The scope of the
invention is limited only by the scope of the appended claims.
- 12 -
