U.S. patent application number 10/550575 was filed with the patent office on 2007-02-15 for method and apparatus for reducing combustion residues in exhaust gases.
Invention is credited to Luigino Fiocco, Lorenzo Musa, Mauro Spadaro Norella.
Application Number | 20070037104 10/550575 |
Document ID | / |
Family ID | 33032954 |
Filed Date | 2007-02-15 |
United States Patent
Application |
20070037104 |
Kind Code |
A1 |
Musa; Lorenzo ; et
al. |
February 15, 2007 |
Method and apparatus for reducing combustion residues in exhaust
gases
Abstract
A method and an apparatus for reducing combustion residues,
particularly pollutants, in exhaust gases generated from the
combustion of fuels such as fossil fuels, wood and similar. The
exhaust gases are treated before releasing them in the environment.
The exhaust gases treatment includes performing a post-combustion
process by submitting the exhaust gases to radiant heat in order to
increase the exhaust gases temperature to a value sufficient to
cause self-combustion.
Inventors: |
Musa; Lorenzo; (Milano,
IT) ; Spadaro Norella; Mauro; (Milano, IT) ;
Fiocco; Luigino; (Milano, IT) |
Correspondence
Address: |
GRAYBEAL, JACKSON, HALEY LLP
155 - 108TH AVENUE NE
SUITE 350
BELLEVUE
WA
98004-5901
US
|
Family ID: |
33032954 |
Appl. No.: |
10/550575 |
Filed: |
December 30, 2003 |
PCT Filed: |
December 30, 2003 |
PCT NO: |
PCT/EP03/51113 |
371 Date: |
August 28, 2006 |
Current U.S.
Class: |
431/5 |
Current CPC
Class: |
F23G 2900/50213
20130101; F02B 37/00 20130101; F01N 13/0093 20140601; Y02T 10/12
20130101; F23K 5/007 20130101; F01N 2610/02 20130101; Y02A 50/20
20180101; B01D 53/34 20130101; F23J 2217/10 20130101; F23G 7/063
20130101; F01N 2240/02 20130101; F01N 3/035 20130101; B01D 53/92
20130101; F01N 3/2066 20130101; F23G 2202/10 20130101; F01N 3/0892
20130101; F01N 3/26 20130101; F23G 5/50 20130101; Y02T 10/24
20130101; F01N 3/021 20130101; F23G 2206/10 20130101; F01N 13/009
20140601; Y02A 50/2325 20180101 |
Class at
Publication: |
431/005 |
International
Class: |
F23G 7/08 20060101
F23G007/08 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 21, 2003 |
IT |
MI2003A000571 |
Nov 12, 2003 |
IT |
M12003A002179 |
Nov 12, 2004 |
IT |
MI2003A002180 |
Claims
1. A method for reducing combustion residues in exhaust gases
generated from the combustion of a fuel, including treating the
exhaust gases before releasing them in the environment, wherein:
said treating the exhaust gases includes a post-combustion process
performed by; feeding the exhaust gases to a radiant combustion
reactor including a radiant combustion chamber and means adapted to
supply energy to the radiant combustion chamber, the radiant
combustion reactor being adapted to transform the supplied energy
into radiant energy radiating within the radiant combustion
chamber; and submitting the exhaust gases to the radiant energy in
the radiant combustion reactor, to raise the temperature of exhaust
gases till a value sufficient to cause self-combustion.
2. The method according to claim 1, in which within the radiant
combustion reactor the temperature of the exhaust gases is
increased to a value in the range from approximately 250.degree. C.
to approximately 1800.degree. C., particularly from approximately
400.degree. C. to approximately 1400.degree. C., preferably from
approximately 900.degree. C. to approximately 1200.degree. C. and,
even more preferably, from approximately 900.degree. C. to
approximately 1100.degree. C.
3. The method according to claim 1, further comprising submitting
the exhaust gases to filtering so as to substantially eliminate
residual uncombusted dust and particulate material present in the
exhaust gases, said filtering being performed at least after the
post-combustion.
4. The method according to claim 3, in which said post-combustion
process is carried out in at least two stages, the method
comprising submitting the exhaust gases to said filtering also
between the two stages.
5. The method according to claim 3, in which said filtering
includes one or more among an active and an inactive filtering.
6. The method according to claim 1, further including pre-heating
the exhaust gases before performing the post-combustion
process.
7. The method according to claim 6, in which said pre-heating the
exhaust gases includes bringing the exhaust gases temperature over
approximately 400.degree. C., preferably in the range from
approximately 400.degree. C. to approximately 700.degree. C.
8. The method according to claim 7, in which said pre-heating the
exhaust gases includes accelerating and compressing the exhaust
gases.
9. The method according to claims 1, further including lowering the
exhaust gases temperature after performing the post-combustion
process before releasing the post-combusted exhaust gases in the
environment.
10. The method according to claim 9, in which the temperature of
the post-combusted exhaust gases is lowered to a value in the range
from approximately 50.degree. C. to approximately 150.degree.
C.
11. The method according to claim 3, in which after said filtering
the temperature of the post-combusted exhaust gases is lowered to a
value in the range from approximately 50.degree. C. to
approximately 150.degree. C.
12. The method according to claim 9, in which said lowering the
temperature of the exhaust gases includes: providing a heat
exchanger; causing the post-combusted gases pass through the heat
exchanger; causing the exhaust gases to be post-combusted invest
the heat exchanger, in order to exploit heat released by
post-combusted exhaust gases for pre-heating the exhaust gases to
be post-combusted.
13. The method according to claims 1, in which the post-combustion
process is carried out continuously, with the exhaust gases to be
submitted to post-combustion being in substantially contiguity
relationship with the post-combusted exhaust gases within the
radiant combustion reactor.
14. The method according to any one of claims 1, in which the
post-combustion process is carried out partially continuously, with
the exhaust gases to be submitted to post-combustion being
separated from the post-combusted exhaust gases within the radiant
combustion reactor at a time of the order of 10.sup.-6 to 10.sup.-2
seconds.
15. The method according to claim 1, in which the post-combustion
process is carried out discontinuously, with the exhaust gases
already submitted to post-combustion being kept substantially
separated from the exhaust gases to be submitted to
post-combustion.
16. An apparatus for reducing combustion residues, particularly
pollutants, in exhaust gases generated from the combustion of fuel,
including a system for the treatment of exhaust gases before
releasing them in the environment, wherein said exhaust gases
treatment system includes a radiant combustion reactor wherein the
exhaust gases pass through, in order to be submitted to radiant
energy for raising the exhaust gases temperature to a value
sufficient to cause self-combustion, thereby a post-combustion
process of the exhaust gases is performed before releasing them in
the environment.
17. The apparatus according to claim 16, in which within the
radiant combustion reactor the exhaust gases temperature is
increased to a value in the range from approximately 250.degree. C.
to approximately 1800.degree. C., Particularly from approximately
400.degree. C. to approximately 1400.degree. C., preferably from
approximately 900.degree. C. to approximately 1200.degree. C., more
preferably from approximately 900.degree. C. to approximately
1100.degree. C.
18. The apparatus according to claim 16, further including a
filtering device adapted to substantially eliminate residual
uncombusted dust and particulate material present in the exhaust
gases, said filtering device being located at least downstream the
radiant combustion reactor.
19. The apparatus according to claim 18, in which said radiant
combustion reactor includes two chambers at the end, one downstream
the other, the filtering device being additionally located between
the two chambers.
20. The apparatus according to claim 18, in which the filtering
device includes one or more among active filters and inactive
filters, particularly selective filters based on ceramic and
zeolite materials.
21. The apparatus according to any one of claims 16, further
including a pre-heating chamber, upstream the radiant combustion
reactor, for pre-heating the exhaust gases before performing the
post-combustion process.
22. The apparatus according to claim 21, in which in said
pre-heating chamber the exhaust gases are pre-heated to a
temperature over approximately 400.degree. C., preferably in the
range from approximately 400.degree. C. to approximately
700.degree. C.
23. The apparatus according to claim 21, in which said pre-heating
chamber includes a device for accelerating and compressing the
exhaust gases, particularly one or more among a fan or an
arrangement of fans, a turbine, a turbo compressor.
24. The apparatus according to claim 23, in which said pre-heating
chamber further includes a Venturi tube for further accelerating
the exhaust gases.
25. The apparatus according to claim 16, further including a
heat-exchange device downstream the radiant combustion reactor, for
lowering the exhaust gases temperature after performing the
post-combustion process before releasing the post-combusted exhaust
gases in the environment.
26. The apparatus according to claim 25, in which the heat-exchange
device is adapted to lower the temperature of the post-combusted
exhaust gases to a value in the range from approximately 50.degree.
C. to approximately 150.degree. C.
27. The apparatus according to claim 25, in which said
heat-exchange device is placed downstream said filtering
device.
28. The apparatus according to claims 25, in which said
heat-exchange device is operatively coupled with the pre-heating
chamber, so that the heat released by the post-combusted exhaust
gases in the heat-exchange device is exploited for pre-heating the
exhaust gases in the pre-heating chamber.
29. The apparatus according to claims 16, further including a
control unit, particularly an electronic, programmable control
unit, for the post-combustion process control.
30. The apparatus according to of claims 16, in which the radiant
combustion chamber includes an enclosed path for the exhaust gases,
and a heating device associated with the enclosed path for heating
walls.
31. The apparatus according to claim 30, in which said heating
includes Joule-effect heaters.
32. The apparatus according to claim 31, in which said enclosed
path includes system of ducts including at least one duct for the
passage of the exhaust gases, and having associated therewith
electrical resistors for heating the duct walls.
33. The apparatus according to claim 32, in which said arrangement
of ducts comprises at least one among a substantially "U"-shaped, a
substantially double "U"-shaped or a substantially "W"-shaped
arrangement of ducts, at least one of said ducts having wound
around it at least one spiral resistor controllably powered for
heating the duct walls.
34. The apparatus according to claim 31, comprising an arrangement
of ducts associated with at least one heat radiating panel, having
embedded therewith a Joule-effect heat generator.
35. The apparatus according to claim 30, in which said heating
system includes an optical radiation source, particularly a
laser.
36. The apparatus according to claim 35, in which said optical
radiation source comprises at least one laser.
37. The apparatus according to claim 36, in which at least one said
laser is operated in pulsed mode.
38. The apparatus according to claim 36, further comprising an
optical radiation reflecting/deflecting arrangement for
reflecting/deflecting the optical radiation onto the enclosed
path.
39. The apparatus according to claims 16, in which a gases
separation system is provided within the radiant combustion reactor
for determining a separation of different parts of the exhaust
gases undergoing different phases of the post-combustion
process.
40. The apparatus according to claim 39, in which said gases
separation system includes a rotor rotatably arranged inside the
radiant combustion reactor.
41. A system including a fuel combustion apparatus in which a fuel
combustion process takes place, and an apparatus for treating
exhaust gases originated by the combustion process, wherein said
apparatus for treating the exhaust gases includes a radiant
combustion reactor wherein the exhaust gases are caused to pass
through, to be submitted to radiant energy for increasing the
exhaust gases temperature to a value sufficient to cause
self-combustion, thereby a post-combustion process of the exhaust
gases is performed before releasing them in the environment.
42. The system according to claim 41, in which said fuel combustion
apparatus is an internal combustion engine, particularly a vehicle
engine.
43. The system according to claim 41, in which said fuel combustion
apparatus is a burner of heating system.
44. The system according to claim 41, in which said fuel combustion
apparatus is a steam boiler for the production of electrical power.
Description
PRIORITY CLAIM
[0001] This application claims priority to PCT Application No.
PCT/EP2003/051113 filed Dec. 30, 2003, which claims priority to
Italian Patent Application Nos. MI2003A000571 filed Mar. 21, 2003,
MI2003A002179 filed Nov. 12, 2003, and MI2003A002180 filed Nov. 12,
2003, which are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to the field of
reduction of environmental pollution, particularly air pollution
caused by the emissions of apparatuses, such as internal-combustion
vehicle engines (Otto cycle, Diesel cycle), burners for heating
systems, generators of vapor for electric power generation plants,
whose operation involves the combustion of fuels, for example
fossil fuels such as hydrocarbon fuels or hydrocarbon containing
fuels such as petroleum, including natural gas, coal, wood and
similar. In particular, the invention relates to a method, and a
related apparatus, for reducing combustion residues, particularly
noxious pollutants, in exhaust gases.
BACKGROUND OF THE INVENTION
[0003] The problem of environmental pollution is nowadays very felt
by people and governments, and efforts are constantly made to find
out solutions for reducing the various human activities impact on
the environment.
[0004] In particular, air pollution caused by the emissions of
apparatuses such as internal-combustion vehicle engines (based on
Otto cycle or Diesel cycle), burners for heating systems, steam
boilers for electric power plants, whose operation involves burning
fuels, particularly fossil fuels, such as hydrocarbon fuels or
hydrocarbon containing fuels like petroleum, including natural gas,
and coal, was probably the first aspect to be recognized in the
more general problem of environmental pollution.
[0005] Although the problem of massive emissions of pollutants into
the atmosphere was starting with the invention of the steam-power
machine at the industrial revolution dawn, it was the impressive
growth of circulating vehicles in urban areas in the decades after
the second world war which brought the problem in foreground.
[0006] Thus, on one side, measures restricting vehicles circulation
were and are still adopted when the situation reaches at crisis
level. On the other side, and in parallel, under the pressure of
governments and of the public opinion, vehicle manufacturers and
research institutes have started to study solutions for the problem
of emissions of noxious pollutants by internal-combustion
engines.
[0007] For example, in the European Union geographic area the
maximum levels of tolerated vehicles emissions have been set by
law, and a system of classification has been introduced for
vehicles engines based on their respective level of pollutants
emissions, in particular, since January 2001, the previous
standards known as EURO1 (introduced in 1987) and EURO2 have been
replaced by the more restricted standard EURO3, which will be
replaced by the even stricter standard EURO4 since January 2006.
This classification imposes that vehicles falling in the lower
classes are not allowed to circulate in case restrictive measures
are issued by governments or public administrations in consequence
to a crisis situation approaching.
[0008] The main pollutants present in exhaust gases of
internal-combustion engines, particularly of Diesel type, are
carbon oxide (CO), carbon dioxide (CO.sub.2), uncombusted
hydrocarbons (HC), various nitrogen oxides (NO.sub.x), and
Particulate Matter (PM), especially carbon particulate.
[0009] Similar substances are found in the exhaust gases of heating
implants and, more generally, of any apparatus whose action
involves the combustion of fuels, particularly fossil fuel.
[0010] Each one of the above mentioned substances is noxious to
human health for one or more reasons, causing cancer, lung disease
and others. Thus, it would be extremely important to reduce as far
as possible, or possibly eliminate, these substances from the
exhaust gases.
SUMMARY OF THE INVENTION
[0011] In view of the state of art above outlined in the foregoing,
an object of the present invention has been to provide an effective
solution to the pollution problem due to the internal combustion
engines emissions and, more generally, to the problem of
environmental pollution due to the emissions of any apparatus whose
action involves the combustion of fuels, particularly but not
limitatively fossil fuel, such as hydrocarbon fuels or hydrocarbon
containing fuels such as petroleum, including natural gas, and
coal, or even wood, and generally any fuel that can be used in a
combustion process.
[0012] The Applicant has found that noxious pollutants (gases,
dust, particulate material, particularly carbon particulate) which
are normally produced by apparatuses whose operation involves the
combustion of fuel, particularly but not limitatively fossil fuel,
such as internal combustion engines and burners of heating systems
of buildings, can be substantially reduced, not to say completely
eliminated, if the exhaust gases are submitted to a treatment that
involves a post-combustion of the exhaust gases, and particularly a
radiant post-combustion, ignited by submitting the exhaust gases to
radiant energy, providing for a relatively fast increase of the
exhaust gases temperature to a value in a properly chosen
temperature range, adapted to essentially destroy the pollutants
present in the exhaust gases.
[0013] For the purposes of the present description, by radiant
combustion there is intended a combustion process that is ignited
by a heat source not involving the presence of a flame, but
irradiating electromagnetic energy, particularly in the range of
wavelengths from InfraRed (IR) to UltraViolet (UV).
[0014] In other words, the Applicant has found that by submitting
the exhaust gases to radiant energy in a suitably designed radiant
reactor, wherein the gases are subjected to a relatively fast
increase of their temperature, up to a value in the properly chosen
temperature range, a substantially perfect post-combustion is
achieved, where, for the purposes of the present invention, by
"perfect" there is meant a post-combustion that allows
substantially the elimination of any noxious component or
substance, such as CO, CO.sub.2, HC, nitrogen oxides, PM, in
particular carbon particulate, sulphur oxides, from the exhaust
gases that are originated by the combustion of fuels.
[0015] According to a first aspect of the present invention, a
method for reducing pollutants in exhaust gases generated from the
combustion of fossil fuel as set forth in the appended independent
method claim 1 is thus provided.
[0016] Summarizing, the method comprises treating the exhaust gases
before releasing them in the environment, by performing a
post-combustion process according to which the exhaust gases are
submitted to radiant energy so as to increase a temperature thereof
to a value sufficient to ignite self-combustion.
[0017] According to a second aspect of the present invention, there
is also provided an apparatus for reducing pollutants in exhaust
gases generated from the combustion of fossil fuel, as set forth in
the appended independent apparatus claim 16.
[0018] In brief, the apparatus comprises means for treating the
exhaust gases before releasing them in the environment, such
treating means comprising a radiant combustion chamber wherein the
exhaust gases are caused to pass through, so as to be submitted to
radiant heat for increasing a temperature thereof to a value
sufficient to ignite self-combustion, thereby a post-combustion
process of the exhaust gases is performed before releasing them in
the environment.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] These and other features and advantages of the present
invention will be made apparent by the following detailed
description of some embodiments thereof, provided merely by way of
non-limitative examples, description that will be conducted making
reference to the annexed drawings, wherein:
[0020] FIG. 1 is a schematic diagram showing, partly in terms of
functional blocks, an apparatus implementing a method according to
an embodiment of the present invention;
[0021] FIG. 2 shows in axonometric view a possible practical
embodiment of the apparatus shown schematically in FIG. 1;
[0022] FIG. 3 schematically shows, in axonometric view, a radiant
combustion reactor of the apparatus of FIG. 1, according to a first
embodiment of the present invention;
[0023] FIG. 4 schematically shows, in axonometric view, a radiant
combustion reactor of the apparatus of FIG. 1, according to a
second embodiment of the present invention;
[0024] FIG. 5 schematically shows, in axonometric view, a radiant
combustion reactor of the apparatus of FIG. 1, according to a third
embodiment of the present invention;
[0025] FIG. 6 schematically shows, in axonometric view, a radiant
combustion reactor of the apparatus of FIG. 1, according to a
fourth embodiment of the present invention;
[0026] FIG. 7 schematically shows, in axonometric view, a radiant
combustion reactor of the apparatus of FIG. 1, according to a fifth
embodiment of the present invention;
[0027] FIG. 8 schematically shows, in longitudinal cross-sectional
view, a radiant combustion reactor of the apparatus of FIG. 1,
according to a sixth embodiment of the present invention;
[0028] FIG. 9 schematically shows, in longitudinal cross-sectional
view, a radiant combustion reactor of the apparatus of FIG. 1,
according to a seventh embodiment of the present invention;
[0029] FIG. 10I depicts quite schematically another type of radiant
combustion reactor adapted to be used in the apparatus of FIG.
1;
[0030] FIG. 11 schematically shows, in axonometric view, a first
possible implementation of the radiant combustion reactor of FIG.
10, in an embodiment of the present invention;
[0031] FIG. 12 schematically shows, in axonometric view, a second
possible implementation of the radiant combustion reactor of FIG.
10, in another embodiment of the present invention;
[0032] FIG. 13 shows rather schematically, in axonometric view, a
third possible implementation of the radiant combustion reactor of
FIG. 10, in still another embodiment of the present invention;
[0033] FIGS. 14A, 14B and 14C schematically shows, in axonometric
view and in cross-section, a first possible implementation of a
third type of radiant combustion reactor adapted to be used in the
apparatus of FIG. 1;
[0034] FIG. 15 schematically shows, in axonometric view, a second
possible implementation of said third type of radiant combustion
reactor; and
[0035] FIG. 16 schematically shows, in axonometric view, a third
possible implementation of the third type of radiant combustion
reactor.
DETAILED DESCRIPTION
[0036] With reference to the drawings, in FIG. 1 a schematic
diagram is provided showing, partly in terms of functional blocks,
an apparatus implementing a pollutants-reduction method according
to an embodiment of the present invention.
[0037] The pollutants-reduction apparatus, denoted globally as 100,
is schematically depicted as placed downstream a block 105,
representative of a generic apparatus of any type whose operation
involves the combustion of fuels, particularly fossil fuels such as
hydrocarbon fuels or hydrocarbon containing fuels such as
petroleum, including natural gas, coal, wood, and the like,
generally any fuel adapted to be used in a combustion process; for
example, the apparatus 105 may be an internal-combustion engine of
a vehicle, particularly but not limitatively of the Diesel type or
based on the Otto cycle, or a burner of a heating system for
buildings, or steam boilers for electric power plants. Downstream
the pollutants-reduction apparatus 100, a block 110 is provided,
schematically representing an exhaust system of any conventional
type, for example a simple muffler of a vehicle.
[0038] In greater detail, the pollutants-reduction apparatus 100
has an input manifold 115i, for receiving combustion exhaust gases
from the apparatus 105; the received exhaust gases are treated by
the apparatus 100 before being released in the environment; the
pollutants-reduction apparatus 100 has an output manifold 115o for
delivering treated exhaust gases to the exhaust system 110 (it is
however observed that the exhaust system 110 might also not be
provided for, and the treated exhaust gases be released directly
into the environment).
[0039] The input manifold 115i leads the exhaust gases to be
treated to a gases pre-heating chamber 120, where the exhaust
gases, received from the apparatus 105 at a relatively low
temperature, are submitted to a preliminary heating process.
Considering for example the case of exhaust gases from an internal
combustion engine, particularly of the Diesel type, the temperature
of the exhaust gases should in theory be around 400-450.degree. C.;
however, experimental trials conducted by the Applicant have
revealed that the exhaust gases temperature is normally lower,
falling in the range from approximately 150.degree. C. to
approximately 300.degree. C. The preliminary heating process in the
pre-heating chamber 120 brings the exhaust gases temperature to a
suitably higher value, preferably a value higher than 400.degree.
C., for example a value in the range from approximately 400.degree.
C. to 700.degree. C. and, preferably, from approximately
550.degree. C. or 600.degree. C. to approximately 700.degree.
C.
[0040] In an embodiment of the present invention, the pre-heating
chamber 120 comprises means adapted to submitting the incoming
exhaust gases to a compression, thereby the gases temperature
rises. In particular, the pre-heating chamber 120 may comprise
means adapted to impart a suitable acceleration to the exhaust
gases, and particularly one or more among a fan (or an arrangement
of fans), a turbine (or an arrangement of turbines), a turbo
compressor; these elements are only schematically indicated in FIG.
1, and identified therein by 121. The acceleration imparted to the
exhaust gases is preferably such that the gas temperature is raised
to approximately 500.degree. C.-600.degree. C.
[0041] Preferably, downstream the means 121 for accelerating the
exhaust gases, a Venturi tube (schematically represented in FIG. 1
and identified therein as 123) is provided, for further compressing
the exhaust gases and thus causing a further increase of the
temperature thereof, for example up to a temperature of
approximately 700.degree. C.
[0042] From the pre-heating chamber 120, the pre-heated gases are
conveyed to a radiant combustion reactor or radiant combustion
chamber 125, situated just downstream the Venturi tube 123.
[0043] The radiant combustion chamber 125, several practical
embodiments of which will be described in greater detail later on,
is a chamber with walls made of suitable material, which are heated
by a heat source to a prescribed temperature, thereby the chamber
walls radiate electromagnetic energy within the chamber (in the way
that approximate the black-body radiation). Within the radiant
combustion chamber 125 the temperature of the exhaust gases is
raised further and rather quickly from the pre-heating temperature,
for example the initial approximately 700.degree. C., to a
temperature in the range from approximately 900.degree. C. to
approximately 1200.degree. C., preferably from approximately
900.degree. C. to approximately 1100.degree. C., suitable to
determine a combustion (post-combustion) of the exhaust gases; more
generally, the upper limit of the temperature of the exhaust gases
may be chosen in such a way that, at such a temperature, the
creation of nitrogen oxides is not relevant; thus, the maximum
temperature of the gases within the combustion chamber 125 may
reach 1300-1400.degree. C. or even higher temperatures, for example
up to 1800.degree. C. The increase in temperature is achieved by
radiant electromagnetic energy, particularly in the wavelength
range from IR to UV, radiating from the walls of the radiant
combustion chamber 125. In case no pre-heating is provided for,
within the radiant combustion chamber the exhaust gases temperature
should be raised from the above-mentioned initial 150.degree.
C.-300.degree. C. to the desired high temperature.
[0044] A possible explanation of the exhaust gases temperature
increase within the radiant combustion chamber can be found in the
radiating effect, according to which the transfer of energy from
the walls of the radiant combustion chamber to the exhaust gases is
proportional to the fourth power of the temperature in Kelvin
degrees.
[0045] By subjecting the exhaust gases to such a fast increase in
temperature, the exhaust gases post-combustion process that is
automatically ignited allows substantially reducing or even
eliminating the harmful, uncombusted particulates present in the
exhaust gases. In particular, in the exhaust gases, typically being
a mix of oxygen, uncombusted hydrocarbons, carbon particulate,
self-combustion is automatically ignited, because the gaseous fluid
in the chamber 125 travels in an environment at a temperature which
is higher than the self-combustion temperature (the specific value
of which depend on the substances present in the exhaust gases),
and the combustion is carried out exploiting the radiant energy
irradiating from the walls of the chamber 125. This substantially
improves the efficiency of the combustion of the carbon
particulates, which is more difficult than that of hydrocarbons
because the combustion time is related exponentially to the size
and shape of the particle.
[0046] It is observed that by ensuring that the gas temperature in
the radiant combustion chamber,125 is sufficiently high, in
particular higher than approximately 450.degree. C., preferably in
the range from approximately 900.degree. C. to approximately
1200.degree. C., and more preferably from approximately 900.degree.
C. to approximately 1100.degree. C., or higher, up to 1800.degree.
C. (generally, a temperature below the temperature at which nitride
oxides start forming), nitride oxides already present in the
exhaust gases are reduced. To this purposes, the post-combustion
process of the exhaust gases may be combined with known reduction
processes, such as the Non-Selective Catalytic Reduction (NSCR)
process, in presence of oxygen (by providing a suitable feed of
oxygen to the radiant combustion chamber, or the Selective
Catalytic Reduction (SCR) process, in presence of a noble catalyst
(e.g., platinum), maintained at high temperature by the flow of the
exhaust gases. It is pointed out that the NSCR and the SCR
processes may be exploited in alternative to one another, or in
combination, depending in particular on the structure, e.g. on the
geometry, of the radiant combustion chamber 125.
[0047] It is also observed that, in the radiant combustion chamber
125, the post-combustion of the exhaust gases takes place at a
constant pressure.
[0048] In FIG. 1 the radiant combustion chamber 125 is shown very
schematically and it is depicted as a substantially "C"-shaped
duct; it is pointed out that this is not to be intended as a
limitation to the present invention; in the following of the
present description, the radiant combustion chamber 125 will be
described in greater detail, and several possible embodiments
thereof will be presented and discussed. In any case, the structure
of the radiant combustion chamber 125, particularly the geometry
thereof, shall be such that it is ensured that the exhaust gases
are submitted to the radiating energy for a time sufficient to
reach the desired temperature, for example a temperature in the
above-mentioned temperature range, adapted to induce the
post-combustion of the pollutants.
[0049] Optionally, a first filtering element 130a is arranged along
the radiant combustion chamber 125 (for example, the radiant
combustion chamber 125 may be made up of two parts in cascade, and
the filtering element 130a may be arranged between the first and
the second part).
[0050] Upon leaving the radiant combustion chamber 125, the
post-combusted exhaust gases are led to a second filtering element
130b.
[0051] Each one or both of the filtering elements 130a and 130b may
comprise active and/or inactive filters, particularly selective
filters, preferably active nanofilters in ceramic/zeolite material,
and are used for trapping residual dust and Particulate Material
(hereinafter, shortly, PM) still present in the exhaust gases after
the post-combustion process in the radiant combustion chamber 125.
An active filter generally acts as a catalyzer with oxidation
reactions; active filters typically are based on metals. An
inactive filter is essentially a trap. It is observed that using
for example zeolite materials, both active and inactive filters can
be realized (placing a zeolite in a bath of gold or palladium
produces an active filter). In particular, the first filtering
element 130a, if provided, allows trapping the residual,
uncombusted dust and PM present in the exhaust gases after a first
post-combustion phase, while the second filtering element 130b,
positioned at the output of the radiant combustion chamber 125,
serves for trapping the uncombusted dust and PM still remaining in
the exhaust gases after the post-combustion. Depending on the type
of nanofilters adopted, the filtering elements may act both as hot
catalysts, and as pure filters,
[0052] It is pointed out that the specific arrangement, the number
and the dimensions of the nanofilters making up the filtering
elements 130a and 130b will depend on the specific type of
apparatus 105 to which the pollutant-reduction apparatus 100 is
intended to be associated with. However, as a general rule,
nanofilters resistant to high temperatures should be used.
[0053] It is also observed that more than one intermediate
filtering element 130a may be provided along the radiant combustion
chamber.
[0054] Preferably, the filtering elements 130a and 130b are
removable from the apparatus 100 and, even more preferably, they
are also reconditionable or recyclable.
[0055] Optionally, means suitable to favor the exit of the
post-combusted gases from the radiant combustion chamber 125 are
provided, as shown in phantom and indicated by 127 in FIG. 1; for
example, such means may comprise another Venturi tube, or any other
device capable of determining a depression downstream the chamber
125.
[0056] After being passed through the second filtering element
130b, the treated exhaust gases (substantially freed of the harmful
pollutants) are led to a heat exchange arrangement 135. In the heat
exchange arrangement 135 the temperature of the treated exhaust
gases is lowered from the approximately 900.degree. C.-1200.degree.
C. to values suitable to avoid thermal shocks, such as a
temperature value of approximately 100.degree. C.-150.degree. C. or
lower, from approximately 50.degree. C.-150.degree. C.
[0057] Expediently, as schematically depicted in the drawing, the
heat exchange arrangement 135 is arranged in such a way that at
least part of the heat released by the treated exhaust gases is
exploited for pre-heating the incoming gases to be treated in the
pre-heating chamber 120, thereby alleviating the burden of the
exhaust gases acceleration means.
[0058] Preferably, the heat exchange arrangement 135 is made of
materials resistant to high temperatures, particularly sodium,
lithium, titanium, etc.), and it may be of the molded metal type,
of the liquid metal type, of the plate type, of the spiral type; in
case the apparatus 100 is intended to be installed on a vehicle,
the heat exchange arrangement shall have a suitably compact
design.
[0059] From the heat exchange arrangement 135, the treated exhaust
gases, from which the harmful pollutants have been substantially
eliminated, are led to the output manifold 115o, and then to the
exhaust system 110 (for example, the muffler of the vehicle).
[0060] A control unit 140 is provided in the apparatus 100 for
controlling the operation of the various components thereof (as
schematized by the dash-and-dot lines in the drawing). In
particular, the control unit 140 comprises electronic control
means, preferably programmable, particularly microprocessor-based
control means, adapted to execute suitable microprograms for
implementing a predefined control flow, and sensors, such as
pressure sensors and temperature sensors for detecting the
operating temperature in the different parts of the apparatus 100,
such as the pre-heating chamber 120, the radiant combustion chamber
125, the heat exchange arrangement 135, the pressure and/or
velocity of the exhaust gases in different points of the path, and
sensors for establishing the percentages of the various pollutants
in the exhaust gases. The control unit may control the heating of
the radiant combustion chamber.
[0061] The specific controls operated by the control unit 140
depend largely on the structure of the radiant combustion chamber
125, but in general the control unit 140 shall at least ensure that
a correct temperature is maintained within the chamber 125.
[0062] FIG. 2 is an axonometric view of a possible practical
implementation of the pollutant-reduction apparatus 100,
particularly adapted to the installation on a vehicle such as a car
or a bus. The different parts of the apparatus shown schematically
in FIG. 1 and described in the foregoing are identified in FIG. 2
with the same reference numerals.
[0063] In the following of the present description, several
different embodiments of the radiant combustion chamber 125 will be
presented, being however intended that the list of presented
alternatives is not to be intended as exhaustive, and several other
embodiments can be devised. It is in fact pointed out that the
specific spatial configuration and structure of the radiant
combustion chamber 125 may depend on the specific application.
[0064] In the embodiment shown in axonometric view in FIG. 3, the
radiant combustion chamber 125 comprises a substantially "U"-shaped
duct 300, having a pair of tubes (radiant tubes) 300a, 300b,
particularly substantially rectilinear, joined to each other and in
communication of fluid with one another, so as to define
thereinside a path for the exhaust gases, wherein the exhaust gases
to be treated, received from the pre-heating chamber 120, are made
to flow. Heating means are associated with the "U"-shaped duct 300
for heating the radiant tubes, for example Joule-effect heaters
and, more particularly, a pair of electric resistors 305a, 305b,
each one associated with a respective one of the two radiant tubes
300a, 300b of the "U"-shaped duct 300; particularly, the two
resistors 305a, 305b are a spiral resistors, each one wound around
the respective rectilinear radiant tube 300a, 300b of the duct 300.
The resistors 305a, 305b are suitably dimensioned (for example,
commercially available resistors of the type Kanthal AM or Kanthal
AF are suitable), and can be connected either in parallel or in
series; an electrical supply (for example provided by the vehicle
battery, schematically indicated in the drawing as 350, or by an
autonomous battery, or by the vehicle alternator) is controlled by
the control unit 140 (as schematized in the drawing by a switch
355). When powered, the heat generated by the resistors by Joule
effect heats the radiant tubes, bringing them to a suitable
temperature, thereby the tubes radiate electromagnetic energy
thereinside.
[0065] In the embodiment shown in axonometric view in FIG. 4, the
radiant combustion chamber 125 comprises two substantially
"U"-shaped ducts 401, 402, similar to the single, substantially
"U"-shaped duct 300 of the previous embodiment, having respective
pairs of substantially rectilinear radiant tubes (only three of
which, denoted 401a, 402a, 402b, are visible in the drawing) joined
to each other and run through in cascade by the exhaust gases. The
two "U"-shaped ducts 401, 402 are associated with heating means, in
the form of four electrical resistors (only three of which, denoted
405a, 405c and 405d, are visible in the drawing) particularly
spiral resistors that, similarly to the resistors 305a, 305b of the
previous embodiment, are each one associated with, and particularly
wound around, a respective substantially rectilinear radiant tube
401a, 401b, 402a, 402b of the ducts 401, 402, so as to cause
heating thereof when powered by the, e.g., battery 350. The
resistors can be connected in parallel, or in series, or partly in
parallel and partly in series.
[0066] The radiant combustion chamber 125 in the embodiment shown
in FIG. 5 comprises instead a generically "W"-shaped arrangement
500 of substantially rectilinear radiant tubes 500a, 500b, 500c and
500d, connected in cascade one to another so as to be all run
through, in succession, by the flow of exhaust gases received from
the pre-heating chamber 120; similarly to the two previous
embodiments, associated with each radiant tube is a respective
electrical resistor 505a, 505b, 505c and 505d, particularly a
spiral resistor wound around the tube, for heating the tube by
Joule effect. For the sake of simplicity, the electrical supply of
the resistors is not expressly shown in the drawing, but it is
clear to those skilled in the art that a connection to, e.g., the
vehicle battery similar to those of the previous embodiments can be
provided for.
[0067] The radiant combustion chamber 125 in the embodiment of FIG.
6 comprises again a substantially "U"-shaped duct 600 through which
the exhaust gases to be treated are made to flow. However,
differently from the previous three embodiments, the heating means
that are associated with the duct 600 are not formed by electrical
resistors spirally wound around the substantially rectilinear tubes
of the duct 600, being instead formed by at least one, preferably a
pair of radiating panels 605a, 605b (one of which shown in phantom,
for the sake of clarity of the drawing) preferably in close-packed
arrangement, each one having embedded therein a respective,
properly dimensioned electrical resistor 607, preferably arranged
according to a winding path; albeit not expressly shown, an
electrical supply similar to those shown in the previous
embodiments is provided for supplying the electrical resistors 607
embedded in the panels 605a, 605b. The duct 600 is thus sandwiched
between the two radiating panels 605a, 605b, and receives heat
therefrom.
[0068] A still different embodiment of radiant combustion chamber
125 is the one depicted in FIG. 7, wherein instead of having a duct
for the exhaust gases formed by tubes, the radiant combustion
chamber 125 comprises a hollow box-shaped enclosure 700, for
example having either generically rectangular or generically
circular cross-section, with an inlet 700i for receiving the
exhaust gases and an outlet 700o for delivering the exhaust gases.
Within the enclosure 700, a plurality of baffles 710 are provided,
arranged so as to define a suitably winding path 715 for the gases
from the inlet 700i to the outlet 700o. The enclosure 700 is
sandwiched between a pair of radiating panels (only one of the two
panels, denoted 705a is shown, for the sake of clarity) with
embedded resistors 707, similar to the panels 605a, 605b of the
previous embodiment.
[0069] FIGS. 8 and 9 show in longitudinal cross-section two further
possible embodiments of the radiant combustion chamber 125. In
particular, in the embodiment of FIG. 8 the radiant combustion
chamber comprises a pair of coaxial ducts 800a and 800b; the inner
duct 800a is hollow and communicates at an end thereof opposite to
the end receiving the exhaust gases from the pre-heating chamber
with the outer duct 800b; the outer duct 800b is substantially an
external lining of the inner duct 800a, and has thereinside baffles
805 defining a substantially helical path for the gases. A suitably
dimensioned spiral electrical resistor 810 is wound around the
outer duct 800b. Around the resistor 810, a thermally-insulating
lining 815 is provided. The exhaust gases are received from the
pre-heating chamber 120 and are fed to the inner duct 800a, through
which the gases flows substantially rectilinearly; then, the gases
pass into the outer duct 805b, which is heated by the electrical
resistor 810 and wherein the gases flows following a generically
helical path, being thus heated to the desired, self-combustion
ignition temperature.
[0070] It is observed that if, as in the schematic arrangement of
FIG. 1, an intermediate filtering 130a is provided for, two coaxial
ducts 800 can be used, one upstream and the other downstream the
filtering element 130a. Similar reasoning applies also to the
previous embodiments, consisting of differently arranged radiant
tubes.
[0071] In a slightly different way, in the embodiment of FIG. 9 an
elongated, generically toroidal body 900, having either generically
circular or rectangular cross-section, has thereinside a
generically helical duct 903 for the gases. The toroidal body 900
is heated by two electric resistors, an inner resistor 910a and an
outer resistor 910b, particularly spiral resistors; the inner
resistor 910a is inserted in the central cavity of the toroidal
body, while the outer resistor 910b is externally wound around the
toroidal body 900; the two resistors are substantially coextensive
to the toroidal body. The exhaust gases flow through the helical
duct 903, and are heated by both the inner and the outer
resistors.
[0072] Clearly, in both the two latter embodiments a resistor
supply arrangement should be provided for, for example similar to
those described in connection with the first embodiments
presented.
[0073] It is observed that the specific dimensions and the material
of the ducts (e.g. the radiant tubes) making up the radiant
combustion chamber 125 depend on the specific application; suitable
materials that can be used for realizing the radiant ducts are for
example INCONEL (an alloy containing tungsten and manganese) and
ceramic. Radiant tubes are also commercially available.
[0074] It is observed that the resistor power supply, controlled by
the control unit 140, should preferably be controlled so as to
track changes in operating conditions, particularly of the
apparatus 105. For example, in some applications, such as in the
case of vehicles, an increased flow of exhaust gases inside the
radiant combustion chamber 125 in consequence of, e.g., an
acceleration of the vehicle, will require a possibly fast
adaptation of the power delivered by the heating resistances, so as
to maintain the temperature within the chamber 125 in the desired
range.
[0075] In order to avoid dispersions of energy, the radiant
combustion chamber 125 is preferably thermally insulated (this has
been schematically depicted in the embodiments of FIGS. 8 and 9:
equivalent thermal insulation should preferably be provided also in
the embodiments of FIGS. 3 to 4, albeit not expressly shown in the
respective drawings), for example by means of refractory
silicon-ceramic materials, or other suitable materials.
[0076] The embodiments of radiant combustion chamber 125 described
up to now, albeit differing from each other in spatial
configuration, are all based on a common, similar heating
principle, involving the use of electric resistances as
Joule-effect heaters.
[0077] Hereinbelow, some further embodiments of the radiant
combustion chamber will be presented which are based on a different
heating principle.
[0078] In detail, instead of using Joule-effect heaters and,
particularly, electrical resistors, one or more optical radiation
source, particularly one or more lasers are exploited for
triggering the radiant reactor, i.e. for heating the radiant
combustion chamber to the desired temperature.
[0079] Lasers are more and more widely exploited in several
applications, either in industry and in consumer products, thanks
to the fact that the emitted optical radiation has is very
homogenous and concentrated, and that they have a very fast
response.
[0080] FIG. 10 shows schematically a radiant combustion chamber 125
of the type exploiting optical radiation, generated by a suitable
source such as a laser, as a heater.
[0081] In detail, the radiant combustion chamber 125 comprises a
combustion reactor enclosure 1000; the spatial configuration of the
combustion reactor enclosure 1000 is not limitative to the present
invention, depending for example on the specific application: thus,
in FIG. 10 the combustion reactor 1000 is schematically depicted as
generically elliptical. The combustion reactor 1000 has walls 1005
made of suitable material, for example INCONEL steel, a composite
material having a ceramic matrix, or special alloys, adapted to
radiate heat when properly heated, and receives thereinside the
exhaust gases to be treated.
[0082] Outside of and around the combustion reactor 1000, an
arrangement of optical radiation reflecting/deflecting elements
1010 is provided, such as mirrors and/or optical prisms,
schematically depicted in the drawing as the internal faces of
walls of a box-shaped casing 1007 containing the combustion reactor
1000.
[0083] The arrangement of optical radiation reflecting/deflecting
elements 1010 reflects/deflects optical radiation 1015 which is
generated by one or more optical radiation sources, particularly
lasers, schematically indicated in the drawing at 1020. It is
observed that the number and the arrangement of the lasers 1020 is
not limitative to the present invention, depending for example on
the shape of the combustion reactor 1000; in the drawing, just by
way of example, four lasers 1020 are shown, each one located at a
respective corner of the box 1007; the lasers 1020 may be fixed or
movable, for example they can be partially rotate and/or be
angularly oriented.
[0084] The optical radiation emitted by the laser(s) 1020,
controlled by the control unit 140, is reflected/deflected by the
optical radiation reflecting/deflecting elements 1010, and hits the
external side of the walls of the combustion reactor 1000, causing
a substantially uniform heating thereof. In this way, the walls of
the combustion reactor are brought to the radiative temperature,
i.e. to a temperature such that a sufficient electromagnetic energy
is radiated from the walls of the combustion reactor into the
enclosure 1000.
[0085] In the following, some possible practical embodiments of
radiant combustion chamber 125 exploiting the optical-based heating
mechanism, particularly the laser-based heating, will be presented,
being intended that such embodiments are mere examples.
[0086] In particular, in the embodiment schematically shown in FIG.
11 the radiant combustion chamber 125 comprises a radiant tube
1100, of suitable material, arranged so as to be traversed by the
exhaust gases coming from the pre-heating chamber 120. Outside the
radiant tube 1100, a light reflecting arrangement 1105 is provided,
schematically depicted as an outer tube coaxial and coextensive to
the radiant tube 1100 and having internal light-reflecting walls.
The light reflecting tube 1105 reflects the laser radiation 1110,
generated by a laser 1120, onto the radiant tube 1100, thereby
causing the heating thereof to the required temperature. The laser
1120 is shown schematically as moving along the axis of the radiant
tube; for example, the laser 1120 may be mounted to a carriage. The
laser 1120 might also be caused to revolve around the tube
1100.
[0087] It is observed that in FIG. 11 (and in the following
drawings) a supply of oxygen (O.sub.2) and ammonia (NH.sub.4) into
the tube 1100, i.e., into the radiant combustion chamber, is
schematically shown; this supply, which is optional and could as
well be provided in any one of the radiant combustion chamber
embodiments described in the foregoing, serves for enabling an NSCR
process for reducing nitrogen oxides during the post-combustion of
the exhaust gases.
[0088] A slightly different arrangement is schematically depicted
in FIG. 12, wherein the radiant combustion chamber 125 comprises a
lined radiant tube 1200 having an inner hollow body 1200a
surrounded by an outer hollow body 1200b, and wherein the exhaust
gases are made to pass in the space 1203 between the inner and the
outer hollow bodies, whilst a laser 1220 is arranged inside the
inner hollow body 1200a, and the latter has reflecting walls
adapted to reflect the laser radiation. Also in this case, the
laser 1220 is schematically depicted as movable along and rotatable
about the axis of the inner hollow body 1200a.
[0089] FIG. 13 shows quite schematically a still different
embodiment of the radiant combustion chamber 125, having a
substantially spherical shape, within which the exhaust gases to be
treated are conveyed. The laser(s) 1320 is arranged externally to
the spherical reaction chamber, and is for example movable so as to
hit different areas of the surface thereof; for example, the
laser(s) is associated to moving means suitable to cause the laser
to revolve around the reaction chamber, so that the laser radiation
hits different points of the chamber external surface and causes a
substantially uniform heating thereof.
[0090] The substantially spherical shape of the combustion chamber
125 in the embodiment of FIG. 13 allows achieving a high
effectiveness in the heating of the exhaust gases conveyed
thereinto. In fact, the incoming exhaust gases, at a lower
temperature, force the gases already undergone to the
post-combustion process to leave the reaction chamber. Also, albeit
not shown in the drawing, an optical radiation
reflecting/deflecting arrangement may also in this case be provided
for.
[0091] It is observed that by properly disaligning the inlet and
the outlet of the gases into/from the reaction chamber, a vortex
can be created inside the reaction chamber that, proximate to the
chamber outlet, optimizes the gas recirculation, favoring the exit
of the portion at a higher temperature. This is further helped by
the Venturi accelerator 127 that may be placed at the exit of the
chamber.
[0092] The use of one or more lasers for heating the radiant
combustion chamber has the advantage of allowing a substantial
reduction in the dimensions of the combustion reactor, because when
turned on the laser(s) cause the reactor walls to almost instantly
reach the desired operating temperature (necessary for inducing
self-combustion of the exhaust gases), and, similarly, the laser(s)
can be turned off almost instantaneously.
[0093] A suitable number of sensors may be associated with the
walls of the radiant combustion chamber so as to enable the control
unit 140 causing the laser radiation to hit the desired areas of
the radiant combustion chamber walls, scanning the surface
according to prescribed patterns in such a way as to cause the
surface be homogeneously hit.
[0094] In particular, a specific control software may be executed
by the control unit 140, according to which the surface to be hit
by the laser radiation is subdivided according to several different
parameters, such as the temperature of the areas already hit by the
radiation, the difference in temperature between these areas and
those not yet hit (the cold areas), the target temperature. A
dynamic temperature map is thus built, and such a map, in addition
to being used by the control unit to control the laser, might also
be displayed, on suitable display devices, to an operator, so as to
enable constantly control the operation of the apparatus.
[0095] The control software may be based on variation calculations
or on perturbation calculation, or on a simpler "fork shoot" (a
term derived from the navy jargon and indicating a successive
approximation process).
[0096] Moreover, the use of laser(s) allows a better
controllability of the whole post-combustion process. In fact, by
properly driving the pulsed laser(s) through the suitably
programmed control unit, the post-combustion process of the exhaust
gases can be controlled finely in dependence of the density of the
exhaust gases and their velocity, which in turn depend on the
engine's RPMs and on the engine operating temperature.
[0097] Additionally, the use of laser(s) reduces the energy
consumption, because only relatively high peak energies are
required.
[0098] The use of lasers thus allows reducing the operation
costs.
[0099] Those skilled in the art will readily understand that the
lasers used, and their optical power, may vary depending on
contingent needs, according to the specific applications. The
laser(s) may be operated in Continuous Wave (CW) mode or,
preferably, in pulsed mode. also, the laser(s) may be of rotating
type, or a laser(s) emitting multiple beams properly
out-of-phase.
[0100] The embodiments shown schematically in FIGS. 14A, 14B and
14C, in FIG. 15 and in FIG. 16 relates to radiant combustion
chambers within which movable means are provided for propelling the
gases during the post-combustion process and/or for varying the
internal geometry of the radiant combustion chamber during
operation. It is pointed out that these, and other equivalent
solutions, may be adopted in either a Joule-effect heated reaction
chamber, or in a radiant combustion chamber heated by optical
radiation, and in general in any type of radiant combustion
chamber, irrespective of the heating means.
[0101] In particular, in FIGS. 14A, 14B and 14C there is
schematically shown, in axonometric and cross-sectional views, a
substantially cylindrical radiant combustion chamber 1400 (depicted
as transparent, for the sake of clarity) with a tri-lobes rotor
1405 rotatably inserted therein, having lobes 1405a, 1405b, 1405c
angularly spaced of approximately 120.degree. from each other, and
with different possible cross-sectional areas, as visible in the
cross-sectional views of FIGS. 14B and 14C.
[0102] A suitable drive arrangement is also provided, not shown in
the drawings, for causing the rotor 1405 to rotate about its axis
inside the chamber.
[0103] If, for example, a laser source is used for heating the
radiant combustion chamber, as in the embodiment of FIG. 11 the
laser radiation hits the chamber from the outside thereof.
Alternatively, the radiant combustion chamber 1400 may be a radiant
tube similar to the radiant tubes of the embodiments of FIGS. 3 to
6, and in this case the heating means may comprise a spiral
electrical resistor wound around the chamber 1400, or one or two
heat radiating panels with electrical resistors embedded
therein.
[0104] The exhaust gases to be treated are conveyed into the
chamber through an inlet 1410i; within the radiant combustion
chamber, the rotation of the rotor 1405 causes a dynamic partition
of the internal space of the chamber into three dynamically-varying
portions, and facilitates the flow of the gases towards an outlet
1410o or 1400o'; while flowing from the inlet to the outlet, the
gases undergoes a post-combustion process due to the radiant energy
radiating from the walls of the chamber 1400.
[0105] It is observed that the inlet 1410i and the outlet 1410o or
1400o' to/from the radiant combustion chamber can either be axially
aligned or not, and either the inlet or the outlet 1410o or 1400o'
or both may even be perpendicular to the chamber axis. As mentioned
in the foregoing, FIGS. 14B and 14C show possible different shapes
of the rotor 1405, differing from each other for the
cross-sectional area. Other shapes are clearly possible.
[0106] In the embodiment of FIG. 15, a rotor 1505 constituted by an
endless screw is rotatably arranged within the cylindrical radiant
combustion chamber 1400 (depicted again as transparent, for
clarity); a suitable drive arrangement, not shown in the drawing,
is provided for rotating the rotor 1505. Also in this case, the
cross-sectional shape of the rotor can vary so as to vary the
internal volume of the post-combustion chamber, in dependence of
the specific application.
[0107] Finally, in the embodiment of FIG. 16 a spherical reaction
chamber 1600 is provided (shown in the drawing in sectional view
along a diametral plane), instead of a cylindrical one, and an
internal rotor 1605 is rotatably arranged within the spherical
reaction chamber 1600. The rotor 1605 has a generically spherical
shape, with three substantially hemispherical depressions 1605a,
1605b and 1605c, the rotor 1605 is thus shaped so as to define
three post-combustion chambers within the chamber 1600, of suitable
volumes.
[0108] As already pointed out, the embodiments shown in FIGS. 14A,
14B, 14C, 15 and 16 do not necessarily require the use of a
laser(s) as a heating means, being possible to exploit them in
connection with more conventional heating means, such as
Joule-effect heaters (electric resistors). However, when used in
association with a laser, the proper control of the motion of the
rotors may optimize the efficiency of the laser pulses.
[0109] The Applicant has found that thanks to the method and
apparatus of the present invention, approximately 90% of the carbon
monoxide, carbon particulate, uncombusted hydrocarbon
(C.sub.xH.sub.y) are eliminated from the exhaust gases, and
nitrogen oxides (NO.sub.x) are reduced of almost 90%.
[0110] The method and apparatus according to the present invention
find application in any system wherein combustion of fuels is
provided for, such as for example internal-combustion engines,
using Diesel fuel, gasoline, methanol, mix of alcohols, natural
gas, LPG, Kerosene, fuel oil, hydrocarbons mixed with water, GECAM,
BLUDIESEL, fuel for planes with additives, masut for marine
engines.
[0111] It is observed that the post-combustion process carried out
in the radiant combustion chamber may be either continuous,
partially continuous or discontinuous (intermittent). By continuous
there is intended a process wherein there is no substantial
separation between the incoming, relatively cold exhaust gases to
be treated and the outgoing, hot and already treated exhaust gases:
the cold phase is contiguous to the hot phase. A partially
continuous post-combustion process is one in which there is a
certain separation in time (for example, of the order of 10.sup.-6
to 10.sup.-2 seconds) between the cold and the hot phases, i.e.
between the cold and the hot gases; this is for example the case
where a combustion chamber such as those of the embodiments of
FIGS. 14A, 14b, 14c, 15 and 16 is used, wherein the provision of
the internal rotor allows for a certain separation of the cold
gases from the hot gases. A discontinuous or intermittent
post-combustion process is instead one in which the post-combustion
chamber is loaded with gases, then the chamber is closed, the
post-combustion process is carried out, the chamber is opened to
discharge the treated gases, and then the process is
re-started.
[0112] It is pointed out that the method and apparatus according to
the present invention can be used in conjunction with other known
pollutants-reduction methods and apparatuses, particularly those
directed to eliminating nitrogen oxides (NO.sub.x), such as
Ignition Time Retardation (ITR), advanced systems of reactant
injection, such as the RJM Aris.TM. technology, water injection,
emulsions, turbocompressed air, air mixed to a fuel, Exhaust Gas
Recirculation (EGR) systems, introduction of refrigerated air, high
injection pressure and change of air/fuel proportion, a turbo
composite, and the like. In particular, all these known techniques
are preferably implemented downstream the apparatus of the present
invention.
[0113] The method and apparatus of the present invention can also
be used in conjunction with the known devices for eliminating
sulphur oxides, particularly sulphur dioxide (SO.sub.2) and
sulphuric oxide (SO.sub.3).
[0114] The apparatus according to the present invention can take
the form of a kit ready to be installed on a vehicle, as a
retrofit
[0115] The method and apparatus according to the present invention
are capable of reducing substantially the emissions of vehicles
propelled by internal-combustion engines, and also
hybrid-propulsion vehicles, with both electrical and
internal-combustion propulsion, will greatly benefit of the
apparatus.
[0116] Although the present invention has been disclosed and
described by way of some embodiments, it is apparent to those
skilled in the art that several modifications to the described
embodiments, as well as other embodiments of the present invention
are possible without departing from the scope thereof as defined in
the appended claims.
[0117] For example, other types of radiant combustion chamber might
be exploited, particularly radiant combustion chambers provided
with different heating means, such as gas burners.
* * * * *