Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Z~E~
--2--
This invention relates generally to chimneys and
waste gas ducts of all sizes and for all uses. More genera~ly,
the principle Or this invention is applicable to flui~d
carrying conduits of varlous kinds~ ; ;
In the specific case of chimneys and ducts which~carry
hot or corrosive~waste gas~ there is generally the provislon
of an interio~r llnlng~ o;f~brick, steel, stainless s~teel,
refractory, plastic, or~the like, ;which has the purpose ~of
protecting the~structural wall of~the chlmney or~duct.
; It is an aspect of~thls~inventlon to provlde~a const~
ruction in whlch~t~hls interlor llning may be redu~ced~in~
extent, thlckne~ss o~r;resistanoe to corros~ion and heat, and
in many installations to dis~pense with the lining altogether.~;
This invention provides a system by which the waste
gas is kept séparated~from~the~structural wall or the~chimney~
or duct by a oontlnuous~acke~ of alr which moves along~
with the waste gas.
In genéral,~if~peri~feral air~inlets were prov~ided at~
th~e base of a~chimnéy~or th~e~begi~nning of a duct system,~
the passage o~ thé~wa9te gas would draw external~air~i~nwar~ly~
t~o provlde an~inltial~jacke;t~close~to the inlets.~Howe;ver,;~
without~furth;ér cont~rol,~the~eas~and~;air~would~qulckly;~mix~
and the jacket or protective~effec~t~ would be lost;.~In accord~
ance with this~lnvention,~devlces are provided at lntervals
throughout the length of~the chimney or duct, whlch~devlces
~ ", . .: , ::
~ , , ~ I ' . . . . . :
:: . : .. . ;: . -
. . . ~ ; . : : : ~
_3_
control the lateral movement of the waste gas and therebyprevent the breakdown or loss of the air jacket.
In the specific description which follows, it is
assumed that the chimney or duct is circular in cross-
section, although it would be understood by those skilled
in the art that a circular section is not a prerequisite.
In accordance with this invention, there are provided
rings (or approximations thereto) of a suitable material~
which may be steel, stainless steel, refractory,etc., the
rings having a curved radial section (or approximately so)
and being placed at or near the intended gas/air interface.
These rings may be supported on ribs from the structural
wall
By virtue of the flow of the gas over the curved
surface of the ring, the downstream gas (and air) will be
directed towards the centre of the flow, thereby compen-
sating for the natural tendency to drift outwardly or
radially, and keeping the gas and air separated. At a point
downstream of each ring, the inward effect will be dissipated
by frictional decay, and at that point, another ring would
be provided to reharness the flow of gas.
The air forming the jacket is provided through inlets
around the perifery of the chimney or duct at the upstream
end thereof (at the bottom, in the case Or a chimney), and
at other points as required.
~4~'2~
In the accompanying drawings Figure 1 shows the chimney
in association with a power or manufacturing plant, commercial
or industrial building or the like.
Figure 2 shows a cut-away view of a chimney of the
design of this invention.
Figure 3 shows, by flow arrows, the passage of air and
waste gas through the chimney of this invention.
Essentially, the method of this invention involves the
provision of devices with curved ring surfaces which control
the outward spread of a column of waste gas, thereby assuring
the integrity of a protective jacket of air, also controlled
by the devices.
In Figure 2 the chimney is seen to consist of a con-
ventional horizontal duct 1 through which the waste gas
enters the chimney, an inner partial lining 2, and a number
of ring devices 3 spaced over the height of the chimney,
which are secured to the structural wall 5 by ribs 6.
The gas entering the chimney is translated to a vert-
ical motion in the partial lining 2, and is also thereby
given a plan shape, (usually circular). At Ll are shown air
inlets by which air is drawn into the annular space 9 between
partial lining 2 and the chimney wall 5. Further air inlets
are provided as necessary throughout the height of the
chimney.
The vertical motion of the column of waste gas 7,
--5--
provided either by thermal lift of the gas, or by inlet
pressure, sends the gas through the chimney and over the
curved devices 3, which are situated in the chimney at a
radius so as to be at or near the interface of the waste
gas and air jacket 8. The ring devices 3 are so shaped that
the flow of gas/air over them directs the flow towards the
centre of the chimney. Thus with even relatively low gas
velocity sufficient radially inward movement is provided tQ
contain the gas column 7 and to preserve the integrity of
the surrounding air jacket 8, thus obviating the need for
expensive traditional lining material.
In Figure 3g flow lines of the gas and air are shown
in the chimney in association with two of the curved ring
devices 3. The periferal gas of the gas column 7, and the
air jacXet 8~ flow over the upstream device and are influ-
enced thereby in terms of velocity, pressure and direction.
Someway downstream of that device, the inherent frictional
decay will reduce the effects of the device and the gas
will return to its entrance condition. At that point another
device is provided to reharness the flow. Clearlyg in short
chimneys it may be necessary to provide only one device.
A second application of the principle of this invention
relates to the provision of one or more of the ring devices
at the top of a conventional or existing chimney, as shown
in Figure 4. With such provision, the periferal gas 12 from
~lS4L
--6--
the chimney 13 will be accelorated as it flows over the
device 10 and the depression caused will draw ambient air,
shown as stream arrows 11, into adjacent and parallel flow.
~ith this arrangement the frictional decaying force will
initially be applied to the upwardly moving air 11 surr-
ounding the gas 12, rather than to the gas itself, thus
allowing the column of gas to rise higher before dispersal
in the atmosphere. In this way a better (i.e. higher)
atmospheric diffusion of the gas will be achieved. Alter-
natively, shorter chimneys can be utilised for a given
height for gas dispersal.
The size, shape and interval for the ring devices
will be dependent upon the diameter and velocity of the
gas column. The size and shape of the devices in the second
application will also depend on the gas characteristics.
In order to accommodate expected gas velocity variations
the profile of the devices can be made to be adjustable.
Although this invention has been described in conn-
ection with a 'single flue' chimney, it will be obvious
that the invention will apply equally to multi-flue chimneys.
Furthermore, the uses of the inventive principle herein
described are clearly not limited tochimneys and ducts
carrying waste gas. The flow of any gaseous or liquid
material can be treated in a similar way, using a neutral
fluid surrounding the fluid to be transported. Thus, it is
2~
--7--
considered that this invention is applicable in general
to fluid-carrying conduits.
It will be appreciated that the ring devices, rather
than consisting of smoothly curved unitary annuli, can be
constructed as conical sections~ thus allowing the ring
devices to be made from sheet metal, lfdesired. It would
be further possible to construct the ring device~s in such
a way that a secti~on taken transverse to the axis through
the ring device would show a polygonal shape. This again
would allow the ring devlces to be constructed ~from init~
ially flat sheet~metal.
~: :
... , . :
,
.
;
~, "` : "" ~' -'
.. . '
