Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1036926
This invention relates to the atomisation of certain combustible
materials and also to their combustion thereafter.
The combustible materials envisaged in this invention are materials
which are, or at a temperature up to 300C are, a gas, a liquid, a
particulate solid,or a liquid containing particulatesolids, and are,
or at said temperature are, pumpable or flowable.
Such materials,.for example ga~eous or liquid fuels, only burn com-
p}etely if they are.mixed with the gas containing oxygen. Liquid fuel
burners,include.eQsentially an atomiser. This atomiser i9 generally
accommodated.in.the.burner head,.which i9 mounted.at the extremity of
the body or tube of the.burner. -The,burner forms an integral part of
a-~Dre or less comFlicated apparatu~ which includes suitable means for.
mixing,the,,atomi~ed.fuel with a gas containing oxygen and for producing
the,..desired flame.
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The known,burners.~ake:u~e of three atomising processes, atomising.by
an auxiliary fluid,.mechanical atomising by the pressure of the fuel
and.,atomising by rotating cup. Some burners embody a combination of
~' thes,e processes.
,, . ..., ., ...., .: , .. . ..
Atomising.by an.auYiliary.gas,uses the enèrgy liberated by the
,, expansion.of,compre~set air or vapour.under pressure for dispersing,.
the,,fuel., This,dispersion is.produced by,the meeting of a jet of
liquid,fuel and a jet of the auxiliary gas. The atomising obtained
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by this process,is very.coarse, above all in the case of the.~ore .
viscous fuels...~oreover~ the consumption of auxiliary.fluid i9 quite ,
considerable, genera}ly in excess of 10 kg vapour to 100 kg heavy fue~
oil. .Consumptions of 15 to 20 kg vapour per 100 kg heavy fuel oil are
normal.
In a.burner with mecba~ical atomising by pressure,,the fuel i8 in3ected
tangentially.into a cavity-within ~hich-it,performs,a rapid rotary:.
vement, while maving.towards rhe.orifice,of:the.burner. This...orifice.
i9 arranget in the centre of a cap which.cover~ the cavity.and.consti-
tutes..the.burner.3et. .At the.outlet:of the 3et.or nozzle,.the ~et of .
liquid is in the_form of a.co~ical sheet.. Thi8 type of atomiser only
ailo~s,variation~:in-delivery between -20 ant..t20~... Uariau~ improue-.
ments~.in particu}ar_the heavy oi}.-return burner and.the-touble.feet.
bùr~e~,,allow..greater:flexibility.in.operation;..in spite..of the
compleYity of these burners..and of their supply.circuit, the..extreme
deli~erie~ are at mo~t,in,the.-ratio,of.lO to l. All the.. mechanical .. .
atomiaing.bur~ers produce.drop}ets which,-are.larger the-more..uiscous
the fuel. ,The aize,of the drops also.increases..~ith the..de~iuery..
The nQzzle, ~hich ic e~posed,to the:radiation..of:the flame..and the.
furnace, is frequently obstructet by the formation of coke.
Rotating,cup,burners are,far:less uset:than:r~e.pre~iou~.-ones. The
cup~ which is,drisen-;by:compressed air or an electric motor, atomises
the fuel by centrifuging.
103~;'9Z6
If the problems inherent in the use of liquid fuels, such as heavy
fuel ails, have found satisfactory solutions from a technical point
of view whereas from an economic point of view these solutions are
not free from imperfections, the same cannot be said of the problem
raised by the combustion of by-products that very much more viscous
than the usual uel_oi~ contain suspended solid constituents. For
instance, it is no~ possibIe with any known burner to atomise certain
tars and make them burn properly. Either the burner is obstructed too
quickly, or the atomising of the fuel is far too coarse.
The present invention has as one object the overcoming of this problem
whereby it is possible to burn fuels of very different kinds, only
requiring a moderate consumption of auxiliary fluid and having great
flexibility of operation as regards both the delivery of the fuel and
its physical state.
.
In prior proposals for atomising by an auxiliary gas, the energy
released by the expansion of the latter is first of all used to form
a jet of gas in which this energy is converted into kinetic energy.
Next, in the impact produced between the jet of gas and the jet of
liqu-id fuel, a fraction of the kinetic energy of the two jets is used
ta av~rcome the forces of cohesion of the liquid. The efficiency of
this process is poor for the mere impact of the jets anly makes it
p~s~ible to use a small fraction of the kinetic energy of the fluids
t~-bring about the dispersion-of-the liquid. In othèr prior proposals,
thc inieial jet oi the auxiliary gas is produced by only a partial
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1036926
r~an~.ion r~f thi-. g-ls an~l th~ mix~ure formed by ~h~ meetiny of
thc two j~ts undergoes a further partial oxpc~nsion or expan-
siorls, bv ~assirlg ~hrouqh a nlrrow passaye or several succes-
sive narrow passages, in which fresh divisions of the liquid
~lrops ar~ pLoduc~(l through shearirlg str-~sses. IIowever, the
greater part of the energy liberated under these conditions
by the expansion of the gas is dissipated in heat, so that with
burners that are thus improved, the consumption of auxiliary
gas remains very considerable. Moreover, highly viscous fuels
rapidly choke this type of burner.
According to a broad aspect of the present invention,
there is provided a process for the atomization of a flowable
combustible material in an elongated atomization zone having
an inlet and an outlet, comprising the steps of: ta) feeding
in a substantially concentric and relatively independent feed
relationship at least one stream of an auxiliary gas and at
least one stream of said combustible material, under pressure,
into said inlet of and through said elongated atomization zone
and characterized by having substantially all of the pressure
drop which occurs in said auxiliary gas and said combustible
material in said atomization zone between said inlet and said
outlet thereof, said feeding of said streams being characterized
by said stream of combustible material being substantially non-
atomized by said auxiliary gas stream prior to entry into said
inlet of said atomization zone and said auxiliary gas and said
combustible material streams being mixed substantially completely
in said atomization zone, (b) expanding said auxiliary gas and
simultaneously at spaced intervals along substantially the entire
length of said zone splitting said gas and combustible material
streams into partial streams and recombining said partial streams
and changing the rotational direction of flow of said streams to
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produce an atomized combustlble material at said outlet, (c)
regulating the relative ratio of feed of said auxiliary gas
stream and said combustible material stream into the inlet of
said zone so that at the outlet of said zone there is provided
a substantially continuously atomized combustible material in-
cludinq said auxiliary gas which occupies a substantially :~
`~1 greater volume than that occupied by said combusti~le material,
and (d) passing the atomized combustible material from said
atomization zone through nozzle means located adjacent said
- 10 outlet of said zone and constraining said atomized combustible ~:
material into a predetermined profile. .
~s This prosess makes it possible, for example, to obtain a very fine
~ disperson of the liquid fuel, In this form, the stream of fuel can
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10369Z6
be-mixea very intimately with a stream of oxygen or gas containing
oxygen. The result of this io. that the formation of unburnt matter
can be greatly reduced or even avoided.
Th2re is no critical limit determinîng the minimum value of this
ra-tio. The energy needed to disperse and propel a given delivery of
liquid fuel i8 furnished by the expansion of the auxiliary gas în~ide
the atomiser; it i9 equally possible to use a relatively small
supply of auxiliary gas by injecting it at high pressure into an
atomiser offering high resistance to the flow of fluids as it is on
the:ather hand to use a larger delivery of auxiliary gas injected at
lowEr ~res~urè-into an atomiser offering less resistance to the flow
of fluids.
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For a given delivery of fuel, however, too small a supply of-auxiliary
gas, even at initial pressure which is increased proportionately,
may:le~d-either to the production of an emulsion in which the gas is
the dispersed phase, or-to the production of a m;xed e~ulsion; in
ei~he~:ca~e, this can lead to the production of an emulsion which does
not mLx-satIsfactorily with the gas containing oxygen. As a general
r~le-it:is possible:-to:obtain the results aimed at by-the invention
by using deliveries of:auxiliary gas and fuel whose ratio is such that
the-volume:occupIed by the gas-at the outlet of the mixer is at least
20 to 30 times-greater than that of the liquid, provided that the gas
pres~ure at the inlet of the atomiser is sufficient.
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10361~26
The delivery of liquid fuel ca~ be indefinitely small in relation to
that of the auxiliary gas. Indeed, one af the advantages of the
process is that the delivery of fuel can be reduced and made to
approach zero, while maintaining.constan~ the approprlate pressure
and therefore the delivery of gas to.the atamiser inlet. The atom-
ising of a very small delivery of the fuel is excellent, and if the
aùxiliary gas is compressed air, subsequent combustion of the
atomised fuel is very satisfactory.
In-principle, there is no maximum or minimum limit as regards the
pr-ess~res that can be used at the inlet of the atomiser. Indeed, the
ne-ce8sary-pressure is linked, as has been explained above, to the
deliv~ry of gas and to the characteristics of the mixer. To atomise
a-give~-delivery of fuel, it is possible to use a pressure of about
2-b-ars, or-even less, at the inlet of the atomiser, provided that a
rath~ large supply of auxiliary gas is used, with an atomiser
offering-moderate resistance to the flow of the flu;ds. In practice,
pre-s~res higher than 3 bars, and for preference higher than 5 bars,
make it possible to atomise the fuel, using reasonable deliveries of
auxiliary air. There is no upper limit as regards the pressures
that can be used, but since the delivery of gas has to remain
sufficiently high in relation to that of the fuel, there is no point
in usi~g.e~tremely high pressures. It is-therefore reasonably
possible to use a pressure between 3 and 20 bars. For preference,
the auxiliary gas is taken to the atomiser inlet at a pressure of 5
rO 10 bar~.
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l036æ6
For example, in order to burn a fuel that i5 as viscous, and even
more ao-, a heavy fuel oil, it can be atomi~ed by using a delivery of
auxIliary gas such that the volume occupied by the gas at the outlet
of-th~.mixer is about 60 times as great as the volume of the liquid
an~-by.in~ecting-the fuel and the auxiliary gas at a pressure of
abaut 6 bars-at the inlet of the appropriate atomiser, such as one
de~cribed hereafter, this atomiser delivering to a furnace at
atmospheric pressure.
The auxiliary fluid is a gaseous substance at the pressure and temper-
at~re.-at which it is used. The auxiliary gas i8 for preference
compressed air or steam under pressure, but many other gases can be
use~. .In particular, a fuel gas such as methane can be employed. Very
low quantities can be used. For example, as little as 2 to 3 kg
stea~ to atomise 100 kg heavy fuel oil.
.
For Freference, the pressure of the auxiliary gas at the inlet to the
at~mi~4r, and therefore its-delivery, are largely constant. It is then
poasible to alter the delivery of fuel by merely acting on its pressure
at-the:inlet. The process-makes it possible to vary within hitherto
unequalled proportions the delivery of atomised gas.
The-.iDsention.makes.-it.yassible.to.use several combustible materials
simu-ltaneously or otherwise, with the same apparatus. It is undertood
that the-cumbu~tible.material.can be heterogeneous and that it can
cantain in suspension insoluble solid particles. An example of par-
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1036~;26
ticulate solids is pulverised coal. A slurry of pulverised coal canalso be employed.
An esp-~cially useful aspect of the invention lies in its opening up
the posgibility of using heterogeneous or very viscous materials such
as, for e~ample, viscous petroleum by-product tars, such as tars from
a petroleum refinery steamcracking process.
Again the invention enables the disposal of sludges containing organic
matér~als. The purification of urban effluents and certain industrial
effluents as a rule comprises the separation of sludge containing
organic materials. This sludge is eliminated by spreading or inciner-
ation. Incineration is performed in special furnaces.
Rotary. fur~aces are regularly used with staggered combustion, in the
'
upper ~tages-of which the drying of the sludge takes place. Some
pyralysis of the organic materials is unavoidable, and ignition is very
gradua-}. These-furnaces give off nauseating smoke, whose purification
requirQs post-combustion.
The use af so-called fluidised bed furnaces is tending to become
generalised, especially for the treatment of the waste water from
petro~eum refinerie~. These furnaces have a number of advantages.
~ They have no inner partitiion or machinery. They do not emit gaseous
; organic compounds and combustion in them is complete. Nevertheless,
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1036~Z6
the operstion of an incinerator of this type is delicate, the running
costs are quite high and the calorific yield is poor.
The present invention makes it possible to incinerate sludge and
makes-it possible to burn the organic matter contained in the sludge
substantially completely. The invention makes it possible to incin-
erate pu~pable sludges derived from industrial effluent, for instance,
or from waste water from papermills, sugar refineries, petroleum
refineries, etc. It may be derived from urban effluent. It i9 thus
passible to-incinerate the sludge from sewage stations. The sludge can
be very wet. Polluted water could even be incinerated directly by
this process. It suffices to use a delivery of make-up fuel in
rel~tion to the delivery and composition of the sludge. As make-up
fuel, ~-gas or any pumpable liquid can be employed. It is possible
to us~ natural gas, petroleum gas, a liquefied petroleum gas, a heavy
fuel oil, etc.
In anather aspect-the-invention provides an apparatus for use in the
afareaaid atomisation-and combustion processes, which apparatus com-
prises in combination (i) an atomisation zone, (ii) an ante-chamber
cannecting with the atomisation zone, (iii) at least two feed inlets
to-the ante-chamber, at least one being for a said combustible material,
at least one other for a said auxiliary gas, and (iv) means at or in
the i;l, ediate vicinity of the exit of the atomisation zone for-modifying,
in use; the profi~e of atomised material exiting from the zone; and
in whi~h apparatus the atomisation zone is of generally cylindrical
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~0369Z16
cross-section an~ is proviclcd internally with means ~hicil, by use of the
apparatus, are adapted to impart to streams of fluids multiple shearing
action and changes of rotational direction.
The preferred form of the atomisation zone or chamber is one employing one of
the known stationary mixers, that is to say of the type consisting
of a cylindrical tube in which are inserted appropriate fixed devices
which have the effect of imparting to the fluids passing through the
tube multiple shearings and changes of direction. One example of such a
mixer is disclosed in U.S. Patent No. 3,286,992 issued on Nov.
22, 1966 to Armeniades et al.
The mixer may consist in partlcular of a tube in which a packing is
inserted. This packing may consist of a stack of elements of suitable
shape. Or again, the mixer may consist of a cylindrical tube in which
a series of spirals or stationary helicoidal components are inserted.
Thus a preferred form of atomisation zone containing a succession of
curved elements or vanes whose shape and arrangement are defined as
follow~:-
(a) the width of each vane is very largely equal to the innerdiameter-of the zone and the length of each vane is at least
equal to 1.25 times the inner diameter of the zone,
,
(b) each vane is curved so as to impart in use, to the fluids
passing through the zone, a rotary movement in relation to the
axis of the zone,
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10369Z6
(c) the shape of this vane is that which is obtained from a
rectangular plate whose width is equal to the inner diameter of
the tube, by twisting this plate so as to rotate the short sides
in relation to one another by a certain angle about the great
median,
(d) the long sides of each vane bear in the inner surface of the
tube and each vane divides in two the transverse section of the
tube,
(e) the vanes are oriented in such a way that the lead;ng edge of
~ach vane, except for the first vane above the mixer, forms an
angle with the trailing edge of the preceding vane, and
~f) the vanes are fixed in the zone by any suitable means.
It i8 preferred that:
~a~ the length of each vane is between 103 and 3 times the inner
tiameter of the zone,
,. (b) the angle formed between them by the leading edge and the
-trailing edge of each vane is between 120C and 240C,
(c) same vanes are curved in one directian and al-ternate with vanes
curved in the opposite direction, in largely equal numbers,
` and total between 5 and 30 vanes,
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(d) the leading edge of each vane, except Eor the first vane up-
stream, is in contact and forms an angle of 90 with the trailing
edge of the preceding vane.
The atomisation zone may contain from 5 to 30 vanes. For preference it
c~ntains between 10 and 20.
The vanes can be fixed at a certain distance from one another. For
preference the leading edge of each wing, except for the first vane
above..the mixer, is in contact and forms an angle that is not zero with
the t~ailing edge of the previous vane. This angle can, for instance,
be between 30 and 150. For preference it is about 90.
Use.is:-made for preference of a stationary mixer having largely equal
numb~r~.of vanes-that are curved in both directions. The vanes of both
types.can be distributed at random. For preference, they are arranged
in equ~l:groups, the groups of vanes curved in one direction alternating
with groups.:of vanes curved in the other directionO
.
Special preference is given to the following arrangement: the angle of
twist.of.each vane is about 180; the adjoining vanes are twisted in
apposite.directions; they touch one another, and the edges in contact
form an angle of about 90
For preference, the.vanes.are fixed to.one another by-their points of
contact. This fixing can take place in particular by soldering, welding
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1()369Z6
or bra~ing. The vanes thus assembled can be kept stationary in the tube
by any-suitable means. For preference, ~he lateral edges of the first
vane above the tube are welded/soldered or brazed înside a ring which
has the same inner diameter as the tube and is supported on an extremity
of the latter. This form of assembly makes it possible to take the
mixer-apart and replace the vanes.
Any skilled technician will be able to calculate the characteristics
of the mixer to be used whatever its type, in particular the inner
diamater of the tube, the length of tube occupied by the fixed devices
inserted therein, etc. in relation to the delivery and initial pressure
of the auxiliary gas, as has been fully explained above, so that the
mixer-opposes the flow of that gas with the appropriate resistance.
Certain stationary mixers impart a rotary movement to the stream of
fluids passing through the tube. If the gyratory component of the
the tube, below the last element of the mixer, is considerable, the
speed of the droplets at the outlet from the tube may have a transverse
component such that the angle of opening of ~he jet is ill-adapted to
the shape or aerodynamic characteristics of the furnace. In such a
case, it is desirable for suitable means to be inserted in the tube
immediately below the last element of the mixer, to reduce or cancel
out the gyratory component of the current. These means may consist in
particular of a curved element or vane, having a curve and a length
such that it imparts to the fluids the necessary impetus for reducing
or cancelling the gyratory component of the stream. For example, if
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the mixer comprises a 3uccession of adjoinir~g vanes, in which two
consecutive vanes are twisted in the opposite directions, this mixer
can be modified by docking the last vane of about a quarter of it8
length; the gyratory component of the current below the last vane of
the mixer thus modified is virtually nil.
It is preferred that the curved elements or vanes are inserted forcibly
in the tube and the last vane downstream of the tube rests on a nozzle
forming one part with the latter.
This method of assembly has several advantages. The vanes are no~
expelled from the tube if a weld has given way. The vanes, in particular
the last one downstream, are perfectly stationary and this avoids the
need for welding them to the tube. It is easily possible to replace
the vanes in the event of tamage.
,
The n~zzle is attached to the exit of the mixer, and gives the desired
profi~e to the jet of atomised fuel, and therefore to the flame when
the atomised fuel i8 subsequently burnt.
. .
This nozzle may comprise one or more-cylindrical or conical holes. The
dismeter of the holes is sufficiently large for the stream of fluids to
undergo only a slight 1088 of pressure in traversing them.
If the nozzle is a single cylindrical apertured nozzle then its diameter
is suitably between 0.5 to 0.9, preferably 0.6 to 0.8 of the internal
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diameter of the atomi~ation zone. Where a plurality of holes are pro-
vided in the nozzle, they are suitable arranged to provide a conically-
profiled jet.
The effect of the nozzle gives the jet of atomised fuel and auxiliary
gas tke desired profile. It also greatly improves the homogeneity of
the aIstribution of the fuel in the auxiliary gas. This result was in
no way foreseeable. Finally, the nozzle is advantageously used as a
stop for retaining the curved elements in the atomisation tube.
The st~ream of fluids undergoes a 1088 of pressure in traversing the
a~omiser and it sustains a further 1088 in traversing the nozzle.
Accor~ing to a preferential characteristic of the invention, the atomiser
and the-nozzle act in conjunction in such a wsy that the 1088 of
pres-snre through the nozzle is relatively slight. For preference, the
mixer-and the nozzle-are calculated so that the 1088 of-pressure through
the nazzle-is less than 80~, or better still, less than 50~ of the total
1088 of pressure.
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The rate of flow of the fluids in the atomiser exerts a decisive in-
fluence on the atomising of the fuel. The atomiser is calculated 80
that ~ith the desired deliveries, the flow of the fluids is very
turbulent.
According to a preferred form of carrying out the present invention,
the characteristics of the atomiser, in particular the inner diamater
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1036~Z~i
of the tube and the length occupied by the parts inserted in it, are
calculated so that the auxiliary gas undergoes a loss of pressure
exceeding 3 bars, for preference between 5 and 20 bars, between the
inlet and the outlet of the atomiser, the delivery of auxiliary gas
being-such that it occupies after expansion, at the outlet of the
nozzle, a volume of at least 30 times, or for preference 50 to 150 times,
greater than that of the liquids admitted to the burner operating at
its maximum output. For preference, the characteristics of the
atomiser are also calculated so that under the conditions of pressure
and delivery thus defined, the rate of flow of the fluids at the inlet
to the atomiser is higher than 10 metres/second, or better still, than
:
25 metres/second.
In all cases it is necessary to have as little dead space as possible
downstream of the last element in the atomisation zone, to prevent
caal-escence of atomised droplets. Hence the shortened last curved
element is at the exit to the chamber; or the last full element abuts
the nozzle~
Some embodiments of apparatus for use in atomisation and combustion
proces.s of-the invention will now be described, by way of non~limitative
e~amp~es, reference being made to the accompanying drawings in which:-
Fig. 1 shows one device in longitudinal cross section,
~ig, 2 shows another device in longitudinal cross section,
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1~36~2f~
Figs. 3 and 4 show modifications of the outlet from the device
shown in Fig. 2,
Fig. 5 shows a modification for varying the injection orifice
of the device of Fig. 2,
Fig. 6 shows further modifications of the device of Fig. 2,
and Fig. 7 is a graph showing the supply of tar as a function
of its pressure above the burner.
Referring to Fig. 1, the device comprise5 an inner feed tube 1, leading
through an injecting orifice 9 into ante-chamber 3. A concentric tube
2, having inlet 20, also leads to the chamber 3. Chamber 3 leads to
an atomisation zone comprising a tube 6 in which are housed fifteen
curved elements 4 and one partial such element 5. The tube 6 has an
internal-diameter of 14 mm. The elements 4 are each 20 mm long and
twist through-an angle of 180, alternately in left hand-and right hand
direction. The elements make close fit with the wall of tube 6 and
the e~ements are brazed or otherwise secured to each other at their
points of contact ~at which point the contacting edges are at about
to each other).
The first of elements 4 is secured to a ring 8 secured to tube 6. The
final element 5 is of reduced length, being about three-quarters that
of elements 4, giving an angle of twist of about 135.
The extremity of tube 6 is conically shaped to enable a conical spray
to be obtained.
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Referring to Fig. 2, the basic con~truction is very similar to that in
Fig. 1, like parts being given like reference numerals. A modification
occurs, however, at the exit portion of atomisation zone 6. The
elements 4 terminate with a full element and not the shortened element
5. The-e~tremity of tube 6 is formed into a nozzle 10 which acts to
determine the shape of the spray issuing from the zone and act~ to
retain elements 4 in the tube should they for any reason start to be
ejected. The nozzle outlet 10 i8 for both these reasons located in the
immediate vicinity of the final element 4.
In Fig. 3 the nozzle 10 is a member secured to the end of tube 6. The
nazzle--has a truncated conical inner profile of angle alpha between
60 and 120.
In Fi&. 4 the nozzle lO has several cylindrical apertures 21 distri-
buted in a conical manner to give a spray of a-conical shape of
includ-ed angle beta. Preferably, to avoid dead space, the nozzle 10
has an inwardly projection portion 22.
Wi-th reference to Fig. 5, the apparatus can-be provided with means for
varying-the-injection orifice 9. This means comprises needle valve
rod-13, 14j movable into and from a corresponding seating in the
orifice 9.
~inally, referring to Fig. 6, modifications are made ta provide further
feed inlets such aj 24. Furthermore, for use in atomising certain
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10369;26
combustible materials, the curved elements 4 are replaced by a first
set 26a each element of which is of length about ten times that of
those in the immediately following set 26b,
The following examples illustrate, in non-limitative manner, processes
in accordance with the invention.
Example 1
An apparatus as described with reference to Fig. 1 was employed.
The combustible material used was a hydrocarbon tar having the
following characteristics:-
o
Density at 15 C1.131 Heptane-insoluble17.5
Viscosity at 50 C 975 cst Hexane-insoluble 43.2%
Viscosity at 100C 31 cst Carbon 87.8%
Residual carbon20.5% Hydrogen 7.1%
(Conrsdson method~ Sulphur 5.1%
The tar was preheated to 140C and fed at 8 to 15 bars pressure
at a rate of from 400 to 900 kg/hour. The auxiliary gas was
steam at conatant pressure of 6 bars and feed rate 30 kg/hour.
Upon issuing from the atomisation zone the atomised product was
burnt in-an industrial furnace. A white flame was produced with
no offensive smoke.
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103t~9.26
This is a major advance since previously i-t has not been pos-
sible to burn this type of hydrocarbon tar without producing
black smoke.
Referring now to Fig. 7, the tar pressure, measured upstream
of the tube 1 in bars, is plotted as abscissa. The corres-
ponding supply of tar, in kg/h, is plot-ted as ordinate.
The steam pressure, measured upstream of the tube 2 is con-
stan-t and equal to 6 bars.
In this figure, curve A represents the tar deliveries that are
obtained with a device according to the invention provided with
an injection orifice 9 whose diameter is 2.5 mm. Curve B rep-
resents those which are obtained when the diameter is 3.5 mm.
An attempt was made to burn the same tar under the same condi-
tions, but using injection of the usual type, with atomising
by an auxiliary fluid. This usual type was identical with that
which is represented in Fig. 1, except that no device was in-
serted in the tube 6; the orifice 9 had a diameter of 2.5 mm.
Atomising was faulty and the flame obtained emitted black smoke,
whatever the pressure and delivery of the tar and the steam
above the burner.
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Example 2
An apparatus was used, as represented in the attached Fig. 6,
for incinerating in a furnace sludge derived from the waste liquor
of a petroleum refinery.
The tube 6 has a length of 3.90 m and an inner diameter of 14 mm. In
this tube there was inserted a series of 18 curved elements 26a 200mm
long, and a series sf fifteen curved elements 26b 20mm long. The
leading and trailing edges of each formed an angle of 180. Element~
twisted ~n one rotational direction alternated with tho~e twisted in
the opposite rotational direction.
By means of this apparatus a sludge was atomised (and thereafter
burnt) derived from the residual liquor of a petroleum refinery.
This sludge contained 65Z water, 28% organic material and 7~
solid particles. It was fed into tube 1. A make-up fuel was
used, being a heavy fuel oil having a viscosity of 200 cst at
50 C. The fuel oil was preheated to 140 C, and was fed into tube
2.
r i
To ensure that the atomising and the propulsion of the sludge
- and the fuel oil, an auxiliary gas was used being steam at a
- pressure of 6 bars; being fed into tube 24.
,~ The deliveries were as follows:
,.
/
; - 22 -
10369,Z~
700 kg/hour sludge
200 kg/hour fuel oil
50 kg/h steam.
The combustion of the fuel oil and the organic materials contained
in the sludge was complete.
Example 3
The same operation was used for incinerating a sludge which con-
tained 20% water, 70% liquid organic material and I0% solid
particles. This sludge, like that of Example 2, came from the
waste liquor of an oil refinery.
An auxiliary gas was steam at a pressure of 6 bars.
The deliveries were as follows:
700 kg/hour sludge
50 kg/hour steam
:,
No make-up fuel was needed. The sludge burnt completely.
"
'~'
.,
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