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Method and device for improving COmbUttinn in an infprr<al combustion enr~ine
The present invention relates to a method and to a device for improving the
combustion of fuels in apparatuses in which a mixture of a fuel and an
oxidizer is burnt
in order to provide energy.
Document WO 98/01662 in the name of the Applicants describes a method and
a device of this type. More specifically, in that prior document, the oxidizer
gas inlet of
the apparatus is provided with means intended to hold therein naphthalene in
solid form
so that the oxidizer gas becomes charged with naphthalene by direct
transformation of
the latter from its solid phase into a gas phase, which process will be called
"sublimation" in the present description.
In a preferred version of the device described in the aforementioned document,
the means for holding the naphthalene in the stream of gaseous oxidizer are
formed by
a cartridge placed in a filter located in the line for feeding the oxidizer
gas into the
apparatus.
1 S For example, if the apparatus is an internal combustion engine or a burner
fed
with an oxidizer formed from hydrocarbons, the means for holding the
naphthalene are
placed in the air filter of the apparatus in question.
Moreover, the aforementioned document specifies that the amount of
naphthalene is chosen to have a value which does not exceed 5 mg per liter of
oxidizer
gas sent into the apparatus. However, by means of many tests carried out by
the
Applicants it has turned out that the proportion of naphthalene indicated does
not lead
to the desired effect of improving combustion.
The object of the present invention is to propose a method and a device for
improving combustion, these being improved over those described in the prior
art which
have just been briefly summarized above, and especially to indicate the
effective volume
proportions of sublimable compound with respect to the volume of oxidizer gas
to be
used.
The subpect of the invention is therefore a method for improving the
combustion
of fuels In apparatuses in which a mixture of a fuel and an oxidizer is burnt
in order to
provide energy via which a solid organic compound is sublimed in a stream of
oxidizer
gas prior to it being mixed with a fuel, the resulting mixture then being
burnt in order to
provide energy, characterized in that the sublimed volume proportion of said
organic
compound with respect to the volume of oxidizer gas forming part of said
mixture lies
within a range going from 0.5 ppm to 15 ppm.
According to the invention, the volume proportion of the sublimable organic
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compound may therefore be several orders of magnitude smaller than the
proportion
indicated in the prior art. Moreover, the tests have shown that there is no
combustion
improvement effect outside the range of values indicated. As a result, in
fact, the
amount of sublimable organic compound consumed by the method according to the
Invention is very markedly less than the consumption estimated previously.
According to other characteristics of the method of the invention:
- If it is carried out in an internal combustion engine, said range is from
0.5 ppm
to 2.5 ppm, preferably from 1.2 ppm to 1.5 ppm;
- if it is carried out in an industrial burner. said range Is from 5 ppm to 15
ppm;
- the tests performed by the Applicants have also shown that naphthalene is
not
the only sublimable substance which is suitable for carrying out the
invention.
Consequently, according to other characteristics of the method of the
invention:
said organic compound is chosen from polycyclic aromatic compounds,
polycyclic alicyclic compounds, functionaliaed aromatic compounds,
functionalized
alicyclic compounds, aromatic or aliphatic acids and/or mixtures of these
compounds;
- said sublimable compound is chosen from the group of compounds consisting
of naphthalene, anthracene, cubane, adamantane, camphane, naphthols,
anthraquinone, camphor or mixtures of these compounds;
said sublimable compound is naphthalene, adamantane and/or camphane;
~ the sublimable compound or compounds is/are used in the form of pills
obtained by compacting their powders;
- said pills comprise only a single compound chosen from said group of
compounds:
said pills comprise at least two compounds chosen from said group of
compounds.
The subject of the invention is also an oxidi2er filter for implementing the
method as defined above, comprising a casing having an oxidizer gas inlet and
an
oxidizer gas outlet and, interposed between this inlet and this outlet, a
filtering element,
the filter also comprising a cartridge located downstream of said filtering
element with
respect to the stream of oxidizer gas passing through it, said cartridge
comprising
perforated tubes in which the sublimable organic compound is placed, said
filter being
characterized in that said cartridge comprises at least one support member in
the form
of a band having corrugations gripping said tubes, preferably with an elastic
effect.
By virtue of this particular characteristic of the filter according to the
invention,
the structure of the banded cartridge causes a minimum pressure drop with
respect to
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the stream of oxidizer passing through the filter.
According to other characteristics of this filter according to the invention:
when said filtering element has a cylindrical and annular overall shape, said
support member in the form of a band is elastic and shaped as a C whose arms
are
pushed outward and in that this support member is held in said filtering
element by said
band being applied against its inner wall ;
each arm of said band is extended toward the inside of the C by a corrugated
portion to which a strip, also corrugated, is fastened so as to provide, with
said band,
passages for fastening said tubes;
~ when said filtering element has mainly a flat shape, said support member in
the form of a band comprises two corrugated strips fastened to each other so
as to
define passages for said tubes, said cartridge being placed directly against
said filtering
element, preferably by resting on the latter by gravity;
each tube has no perforations over part of its length so as to contain a
reserve
of sublimable organic compound;
said pills may be stacked in said tubes and pressed by a spring placed at one
of
the ends of the stack of pills;
said support member in the form of a band has omega~shaped corrugations in
which said tubes are held by snap~fastening.
The particular characteristics of the filter that have just been defined
especially
provide the following advantages:
the fastening of the tubes containing the sublimable organic compound by
corrugated bands allows the tubes to be mounted in the cartridge easily;
the amount of compound placed in the filter may be easily varied by choosing
the number of tubes fastened in the corrugated bands. This represents an
advantageous
convenience for the user, even for a non-expert, since he himself will be able
not only to
replace the used filters but also, without any difficulty, to fit the
cartridge into the
apparatus with which the filter is associated.
For example, if the filter is mounted in an automobile engine, it may thus be
easily tailored to the cubic capacity of the engine, in particular if the
cartridge is sold in
the retail trade. Moreover, tailoring to the shape of the filter may be done
without any
problem by suitably placing the tubes with respect to the filter inlet and
outlet.
The structure of the cartridge is such that the tubes are disengaged from the
filtering element and, with regard to the cylindrical configuration
envisioned, it places
the tubes at the center of the oxidizer flow.
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Other characteristics and advantages of the invention will appear in the
course of
the description which follows, given solely by way of example and with
reference to the
appended drawings in which:
Figure 1 shows, in axial sectional view, an oxidizer filter used upstream of
the
inlet manifold of an internal combustion engine, the filter being provided
with a charge
of sublimable organic compound;
- Figure 2 is a radial sectional view of the filter in Figure 1, on the line
of section
- Figure 4 is a vertical sectional view of a flat filter that can be used as
the filter
in Figure 1 and also charged with a sublimable organic compound;
- Figure 5 is a plan view of the filter in Figure 4, its cover having been
removed;
- Figures 6 and 7 show two alternative embodiments allowing tubes filled with
a
sublimable organic compound to be fastened in a filter according to Figures 1
to 3 or 4
and 5.
Figures 1 to 3 show a first embodiment of a filter for implementing the method
according to the invention.
This is an oxidizer filter 1 for an internal combustion engine, comprising a
casing
2 closed by a cover 3, both being of cylindrical overall shape.
The casing 1 has a side inlet orifice 4 intended to be connected to an
oxidizer
intake (not shown), for example an air intake. It also has an axial outlet
orifice 5
intended to be connected to the inlet manifold (also not shown) of an internal
combustion engine.
An annular filtering element 6 of conventional shape and construction is
placed
axially in the filter, it being held in place by any suitable means.
The filter 1 also contains a cartridge 7 containing a sublimable organic
substance. This cartridge 7 comprises two supports 8a and 8b placed inside the
filtering
element 6 at a certain distance apart along the axis of the filter. Each of
these supports
comprises an elastic band 9 bent into the form of a C, the elasticity of which
is such that
the ends of the C have a tendency to move further apart. Consequently, in
order to place
such a support inside the filtering element 6, its ends need to be moved
closer together
for introducing the support into it, and then the ends need to be released so
that the
arms of the C press with an elastic stress against the filtering element 6.
This results in
very convenient mounting/removal of the cartridge 7, requiring no tool. This
arrangement is particularly suitable for making convenient the replacement of
a used
3.'~ cartridge with a full cartridge.
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Beyond the ends of the Gshaped part of the band 9, the latter is bent back
inward and shaped so as to have corrugated parts 10a, lOb and lOc, the peaks
of which
are oriented laterally outward. Each of these corrugated parts is duplicated
by a
corrugated part (lla, llb and llc respectively) of a second band 11, two of
these
5 bands being provided in the example described.
The associated corrugated parts 10a, lla, lOb, llb and lOc, llc define a
passage 12 for a reservoir tube 13 intended to contain the sublimable
compound. Each
of these tubes is formed from a rolled portion of sheetmetal, the longitudinal
edges of
which are not contiguous, thus defining a longitudinal slit 14 (Figure 3). The
rolled
sheetmetal is closed at each end by a plug 15, preferably in a tamperproof
manner.
Moreover, it is perforated in order to form rows of holes 16 lying along
generatrices
which are 90' apart one with respect to another and with respect to the slit
14,
respectively. However, it will be noted that these rows of holes do not extend
over the
entire length of the tubes, the portion corresponding to a distance d of each
tube not
having holes being, in the example described, in that part of the filter
located on the far
side of the inlet 4 with respect to the outlet 5. The reason for this will be
explained
below. Preferably, the apparent surface area of the slit 14 is equal to the
cumulative
apparent surface area of one row of holes 16.
Before being sealed, each tube 13 is filled with solid balls 17 of the
sublimable
organic substance, each ball having a diameter slightly less than the inside
diameter of
the tube. The balls 17 are stacked in the tube 13 and pressed against one
another by a
spring 18 provided inside the tube at one of the ends of the latter. The
reason for having
a portion of each tube with no holes may thus be understood. This is because
the said
portion may serve as a reservoir of balls, those being present in the
reservoir not being
broached by the sublimation until they have descended toward the perforated
portion of
the tube after partial or complete consumption of the balls housed in this
perforated
portion.
In thls regard, it should be noted that the stream of oxidizer in the filter
is
predominantly established in a region lying between the inlet 4 and the outlet
5 of the
filter (in the example, the lower 3l4 region), the rest of the volume of the
filter being
coursed by a stream of oxidizer having a lower flow rate. The location of the
section of
each tube having no holes therefore preferably coincides with this remaining
volume
swept by a small stream of oxidizer.
The cumulative total surface area of the holes 16 and of the slit 14 for all
the
tubes 13 defines the rate of sublimation of the sublimable compound when it is
swept
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by the stream of oxidizer penetrating each tube and leaving therefrom charged
with a
certain proportion of sublimed compound.
This total surface area is chosen in such a way that, especially when taking
into
account the flow rate of oxidizer gas passing through the filter, the
proportion of
S sublimed compound in the stream of gas leaving the filter via the outlet
orifice 5 is
between 0.5 ppm and 2.5 ppm, it being possible to achieve maximum
effectiveness if
this surface area fixes the proportion between 1.2 and 1.5 ppm. In the case of
naphthalene, 1 ppm by volume of sublimed substance corresponds to 5.71 mg of
naphthalene per m3 of oxidizer gas, such as air.
According to the method for improving combustion carried out by using the
oxidizer filter that has just been described, the organic compounds must
sublime
between -15°C and +80°C and they may be chosen from polycyclic
aromatic
compounds, polycyclic alicyclic compounds, functionalized aromatic compounds,
functionalized alicyclic compounds, aromatic or aliphatic acids and/or
mixtures of these
compounds.
!t has turned out that the following compounds are particularly suitable:
naphthalene, anthracene, cubane, adamantane, camphane, naphthols,
anthraquinone
and camphor. It is also possible to use a mixture of two or more of these
substances.
However, at the present time, naphthalene, adamantane and camphane are
preferred
?.0 substances.
It is also advantageous to produce the sublimable organic compound or
compounds in the form of pills obtained by compacting a powder of the compound
or
compounds in question. The shape of the pills will be tailored to the support
intended to
hold them in the stream of oxidizer gas. Ball~shaped pills, as shown above,
fit very well
in an oxidizer filter as described above. However, other shapes are possible,
such as
rods, disks, etC.
The filter described above with regard to Figures 1 to 3 was mounted in a
diesel
engine on a test rig, the engine having firstly undergone tests, with the
filter not having
the cartridge 7, and then the same tests were performed with this cartridge in
place as
shown in Figures 1 to 3. During the two series of tests, the following
parameters were
measured in succession, at full throttle, at idle and during transient
operating phases of
the engine, for three different sublimable organic compounds, namely
naphthalene,
adamantane and camphane, respectively:
torque delivered by the engine;
~ specific fuel consumption;
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CO content of the exhaust gases;
content of unburnt hydrocarbons in the exhaust gases;
opacity of the exhaust gases;
NOx content of the exhaust gases.
S The values of these parameters were measured and the percentage variation
between the values recorded during the first test series and the equivalent
values in the
second series was noted.
Furthermore, the transient phases were examined by taking averages of the
measured values during successive increments in speed from idle to 4000 rpm,
with
hold periods every 500 rpm for one hour.
The results of this comparative study are given in the following table:
CA 02329404 2000-10-20
UJ
Z
V uJN '" rwd~
+ 00 ~ V'O
E-~ U ~
d
N
w
Z
a
N m ~'! m m
o_ 0oO
Q
.
d
+ 0 0 o r.
R
c~~ ~ o
. ~ r~ c".'vn
,~
o ~'!~
a
W Q ~ O r.N 00p
LtJ 1DIs fM
f'
Z
w
J
Q o o
E ui~ r:o
a
z
v7
t" ~ ~ o R " ou~'o
O N N ch
O O O
O t0 N
y .-~N .~
E v
O ay ' n N t~~,C
N .--~rrN
O C
~o O
n .__
m ' _
E .
: _ x
a I-~_ ~ Z ~u
a O Z
v~
cn
U
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In this table, the hyphens mean that the corresponding value was not measured
or was not measurable.
Thus, it may be seen that the use according to the invention of the sublimable
organic compound results in reduced tuel consumption and considerable
improvement
S in the parameters determining the pollution by the exhaust gases of the
engine.
Figures 4 and 5 show another oxidizer gas filter lA having a parallelepipedal
shape. The casing 2A of this filter comprises a cover 3A, a side inlet 4A for
oxidizer gas
and an outlet 5A provided in the cover 3A. The cartridge 7A for the sublimable
organic
compound is shaped in a similar way to that described with regard to Figures 1
to 3,
except the band 9A is not elastic and is developed in a plane resting by
gravity on the
filtering element 6A.
The cartridge comprises tubes 13 similar to those already described, only
three
of these tubes being shown. However, it will be noted that they have holes
along their
entire length and do not have a spring. Moreover, in a space close to the
inlet 4A, there
are no tubes, so as to guarantee as uniform a sublimation of the compound as
possible.
Figure 6 shows an alternative version of fastening the tubes 13 in the filter.
These are held elastically between two corrugated bands 19 suitably fastened
to the wall
of the filter. Figure 7 shows another fastening version in which the tubes 13
are clipped
into omega-shaped housings 20 in a band 21, the latter being suitably fastened
in the
casing of the filter.
Tests performed on industrial burners, especially those that can be used in
central heating plants, have also demonstrated the effectiveness of the method
according to the invention. It has been demonstrated that, compared with a
burner not
equipped with an oxidizer filter according to the invention, a burner so
equipped can
reduce its consumption by up to 22% and the sulfur emanations were eliminated,
the
NOx decreasing by 50°~o and the opacity also being reduced by
50,x.
A filter is not customary in the case of industrial burners. It is therefore
possible
to place a cartridge of sublimable organic substance directly in the oxidizer
gas feed
line. In this case, the proportion of sublimable organic compound preferably
lies within
a range going from 5 ppm to 15 ppm, depending on the type of burner fitted.
