U.S. patent application number 10/206759 was filed with the patent office on 2004-01-29 for apparatus and method for thermal neutralization of gaseous mixtures.
Invention is credited to Korwin, Michel J., Szymborski, Janusz.
Application Number | 20040018460 10/206759 |
Document ID | / |
Family ID | 30115186 |
Filed Date | 2004-01-29 |
United States Patent
Application |
20040018460 |
Kind Code |
A1 |
Korwin, Michel J. ; et
al. |
January 29, 2004 |
Apparatus and method for thermal neutralization of gaseous
mixtures
Abstract
A process atmosphere incinerator for neutralizing chemical
non-innocent gaseous mixtures uses thermally induced neutralization
reactions, and does not rely on the use of auxiliary components. In
these reactions, chemical non-innocent gaseous mixtures are
neutralized to form benign and environmentally friendly products. A
plurality of flame breakers is disposed inside of the reaction
chamber of the process atmosphere incinerator. The flame breakers
introduce variations in gas flow paths and flame patterns, and
provide surfaces of elevated temperature inside the reaction
chamber. The process atmosphere incinerator is constructed in a way
as to support neutralization of a wide range of amounts of
non-innocent gaseous mixtures of arbitrary composition.
Inventors: |
Korwin, Michel J.;
(Westmount, CA) ; Szymborski, Janusz; (Pointe
Claire, CA) |
Correspondence
Address: |
FREEDMAN & ASSOCIATES
117 CENTREPOINTE DRIVE
SUITE 350
NEPEAN, ONTARIO
K2G 5X3
CA
|
Family ID: |
30115186 |
Appl. No.: |
10/206759 |
Filed: |
July 29, 2002 |
Current U.S.
Class: |
431/5 ; 422/182;
431/170; 431/171; 431/7 |
Current CPC
Class: |
F23G 7/065 20130101 |
Class at
Publication: |
431/5 ; 431/7;
431/170; 431/171; 422/182 |
International
Class: |
F23D 021/00; F23D
014/00; F23M 009/06 |
Claims
What is claimed is:
1. A process atmosphere incinerator having a reaction chamber for
thermally reacting gaseous mixtures and a burner connected to said
reaction chamber, said process atmosphere incinerator comprising a
plurality of flame breakers disposed inside said reaction chamber,
said flame breakers providing surfaces of elevated temperatures
within gas flow paths.
2. A process atmosphere incinerator defined in claim 1, wherein the
flame breakers introduce variations in gas flow paths and flame
patterns inside said reaction chamber.
3. A process atmosphere incinerator defined in claim 1, wherein at
least one flame breaker is vertically mounted to the inside of the
reaction chamber, being supported by the floor section of the
reaction chamber.
4. A process atmosphere incinerator defined in claim 3, wherein a
shape of the at least one flame breaker is substantially that of an
elongated parallelepiped, a longitudinal direction of an oblong
base of the flame breaker forming an acute angle with a
longitudinal direction of the reaction chamber.
5. A process atmosphere incinerator defined in claim 4, wherein the
longitudinal direction of the oblong base of the flame breaker
forms an angle of approximately 20.degree. with the longitudinal
direction of the reaction chamber.
6. A process atmosphere incinerator defined in claim 3, wherein the
flame breaker is formed of a ceramic material.
7. A process atmosphere incinerator defined in claim 1, wherein the
burner horizontally introduces a flame into the reaction chamber
along a longitudinal direction thereof.
8. A process atmosphere incinerator defined in claim 1, comprising
a reaction chamber having a baffle disposed above the inlet for the
flame produced by the burner, said baffle horizontally extending
along the longitudinal direction of the reaction chamber.
9. A process atmosphere incinerator defined in claim 8, comprising
a reaction chamber having an inlet for chemically non-innocent
gaseous mixtures and an outlet for neutral gaseous mixtures, said
inlet and set outlet disposed on opposite sides with respect to the
baffle.
10. A process atmosphere incinerator defined in claim 1, further
comprising a process control unit for regulating the conditions of
the chemical reactions inside the reaction chamber, said process
control unit including a sensor disposed for sensing the reaction
conditions inside the reaction chamber, a first valve to regulate
an amount of air fed to the reaction chamber, a second valve to
regulate an amount of fuel fed to the burner, and a controller to
control the amount of air to be fed to the neutralization chamber
and the amount of fuel to be fed to the burner in dependence on the
reaction conditions sensed by sensor.
11. A process atmosphere incinerator defined in claim 1, wherein
the controller comprises a processor.
12. A process atmosphere incinerator having a reaction chamber for
thermally reacting gaseous mixtures, and a burner connected to said
reaction chamber for horizontally introducing a flame into said
reaction chamber along a longitudinal direction thereof, said
process atmosphere incinerator comprising: an inlet for chemically
non-innocent gaseous mixtures disposed on the bottom section of the
reaction chamber; an outlet for neutral gaseous mixtures disposed
on the top section of the reaction chamber; and at least one
partitioning wall inside the reaction chamber for providing a
substantially horizontal gas flow path from the inlet to the
outlet.
13. A process atmosphere incinerator defined in claim 12, wherein
the burner is disposed to horizontally introduce a flame into the
reaction chamber along a longitudinal direction thereof.
14. A process atmosphere incinerator defined in claim 12, further
comprising at least one flame breaker, said at least one flame
breaker being mounted to the inside of the reaction chamber.
15. A process atmosphere incinerator defined in claim 14, wherein
the at least one flame breaker is vertically mounted to the inside
of the reaction chamber, and supported by the floor section of the
reaction chamber.
16. A process atmosphere incinerator defined in claim 15, wherein a
shape of the at least one flame breaker is substantially that of an
elongated parallelepiped, a longitudinal direction of an oblong
base of the flame breaker forming an acute angle with a
longitudinal direction of the reaction chamber.
17. A process atmosphere incinerator defined in claim 16, wherein
the longitudinal direction of the oblong base of the flame breaker
forms an angle of approximately 20.degree. with the longitudinal
direction of the reaction chamber.
18. A process atmosphere incinerator defined in claim 14, wherein
the flame breaker is formed of a ceramic material.
19. A process atmosphere incinerator defined in claim 12, further
comprising a process control unit for regulating the conditions of
the chemical reactions inside the reaction chamber, said process
control unit including a sensor, disposed for sensing the reaction
conditions inside the reaction chamber, a first valve to regulate
an amount of air fed to the reaction chamber, a second valve to
regulate an amount of fuel fed to the burner, and a controller to
control the amount of air to be fed to the neutralization chamber
and the amount of fuel to be fed to the burner in dependence on the
reaction conditions sensed by sensor.
20. A process atmosphere incinerator defined in claim 19, wherein
the controller comprises a processor.
21. A process atmosphere incinerator having a reaction chamber for
thermally reacting gaseous mixtures, a burner connected to said
reaction chamber for horizontally introducing a flame into said
reaction chamber along a longitudinal direction thereof, an outlet
for neutral gaseous mixtures, and at least one gas activation
channel running in a direction through the reaction chamber for
thermally activating gaseous mixtures, said at least one gas
activation channel comprising: a supply pipe for receiving
chemically non-innocent gaseous mixtures; and an outlet for
releasing chemically non-innocent gaseous mixtures into the
reaction chamber.
22. A process atmosphere incinerator defined in claim 21, wherein
the burner is disposed to horizontally introduce a flame into the
reaction chamber along a longitudinal direction thereof.
23. A process atmosphere incinerator defined in claim 21, wherein
the outlet for releasing non-innocent gaseous mixtures of the gas
activation channel is positioned in close proximity to a nozzle of
the burner.
24. A process atmosphere incinerator defined in claim 21, further
comprising at least one flame breaker, said at least one flame
breaker being mounted to the inside of the reaction chamber.
25. A process atmosphere incinerator defined in claim 24, wherein
the at least one flame breaker is vertically mounted to the inside
of the reaction chamber, and supported by the floor section of the
reaction chamber.
26. A process atmosphere incinerator defined in claim 25, wherein a
shape of the at least one flame breaker is substantially that of an
elongated parallelepiped, a longitudinal direction of an oblong
base of the flame breaker forming an acute angle with a
longitudinal direction of the reaction chamber.
27. A process atmosphere incinerator defined in claim 26, wherein
the longitudinal direction of the oblong base of the flame breaker
forms an angle of approximately 20.degree. with the longitudinal
direction of the reaction chamber.
28. A process atmosphere incinerator defined in claim 24, wherein
the flame breaker is formed of a ceramic material.
29. A process atmosphere incinerator defined in claim 21, further
comprising a process control unit for regulating the conditions of
the chemical reactions inside the reaction chamber, said process
control unit including a sensor, disposed for sensing the reaction
conditions inside the reaction chamber, a first valve to regulate
an amount of air fed to the reaction chamber, a second valve to
regulate an amount of fuel fed to the burner, and a controller to
control the amount of air to be fed to the neutralization chamber
and the amount of fuel to be fed to the burner in dependence on the
reaction conditions sensed by sensor.
30. A process atmosphere incinerator defined in claim 29, wherein
the controller comprises a processor.
31. A method for thermally reacting chemically non-innocent gaseous
mixtures, comprising the steps of: introducing chemically
non-innocent gaseous mixtures into a reaction chamber; guiding the
chemically non-innocent gaseous mixture along a gas flow path from
an inlet to an outlet of the reaction chamber; providing surfaces
of elevated temperatures inside the reaction chamber within gas
flow path and between two guiding walls of the reaction chamber,
the surfaces of elevated temperature for providing atmospheric
turbulences thereabouts within gas flow paths inside the reaction
chamber, the turbulences other than those relating to guiding the
gas flow within the gas flow path; subjecting the chemically
non-innocent gaseous mixture to thermally induced chemical
reactions while guiding it through the reaction chamber; cooling
the neutralized gaseous mixture after releasing it from the
reaction chamber, and before releasing it into the ambient
atmosphere; and releasing the neutralized gaseous mixture into the
ambient atmosphere.
32. A method for reacting chemically non-innocent gaseous mixtures
defined in claim 31, wherein the surfaces at elevated temperatures
are provided by at least one flame breaker.
33. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 31, further comprising the step of
providing a predefined temperature inside the reaction chamber by
controlling the amount of heat produced in a combustion of fuel and
air, and by mixing gases inside the reaction chamber with
additional gases at a different temperature.
34. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 33, further comprising the step of
adjusting the predefined temperature to fall within a range from
900.degree. C. to 1100.degree. C.
35. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 31, further comprising the step of
cooling the neutralized gaseous mixture after releasing it from the
reaction chamber and before releasing it into the atmosphere by
mixing the neutralized gas mixture with gases at lower temperature
than the neutralized gas mixture.
36. A method for thermally reacting chemically non-innocent gaseous
mixtures, comprising the steps of: introducing chemically
non-innocent gaseous mixtures into a reaction chamber; introducing
a horizontal flame into the reaction chamber along a longitudinal
direction thereof; guiding the chemically non-innocent gaseous
mixture along a gas flow path from an inlet to an outlet of the
reaction chamber; providing surfaces of elevated temperatures
inside the reaction chamber within gas flow path and between two
guiding walls of the reaction chamber, the surfaces of elevated
temperature for providing atmospheric turbulences thereabouts
within gas flow paths inside the reaction chamber, the turbulences
other than those relating to guiding the gas flow within the gas
flow path; subjecting the chemically non-innocent gaseous mixture
to thermally induced chemical reactions while guiding it through
the reaction chamber; cooling the neutralized gaseous mixture after
releasing it from the reaction chamber, and before releasing it
into the ambient atmosphere; and releasing the neutralized gaseous
mixture into the ambient atmosphere.
37. A method for reacting chemically non-innocent gaseous mixtures
defined in claim 36, wherein the surfaces at elevated temperatures
are provided by at least one flame breaker.
38. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 36, further comprising the step of
providing a predefined temperature inside the reaction chamber by
controlling the amount of heat produced in a combustion of fuel and
air, and by mixing gases inside the reaction chamber with
additional gases at a different temperature.
39. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 38, further comprising the step of
adjusting the predefined temperature to fall within a range from
900.degree. C. to 1100.degree. C.
40. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 36, further comprising the step of
cooling the neutralized gaseous mixture after releasing it from the
reaction chamber and before releasing it into the atmosphere by
mixing the neutralized gaseous mixture with gases at lower
temperature than the neutralized gas mixture.
41. A method for thermally reacting chemically non-innocent gaseous
mixtures, comprising the steps of: thermally activating chemically
non-innocent gaseous mixtures; introducing the thermally activated
chemically non-innocent gaseous mixtures into a reaction chamber;
guiding the chemically non-innocent gaseous mixture along a gas
flow path from an inlet to an outlet of the reaction chamber;
providing surfaces of elevated temperatures inside the reaction
chamber within gas flow path and between two guiding walls of the
reaction chamber, the surfaces of elevated temperature for
providing atmospheric turbulences thereabouts within gas flow paths
inside the reaction chamber, the turbulences other than those
relating to guiding the gas flow within the gas flow path;
subjecting the chemically non-innocent gaseous mixture to thermally
induced chemical reactions while guiding it through the reaction
chamber; cooling the neutralized gaseous mixture after releasing it
from the reaction chamber and before releasing it into the ambient
atmosphere; and releasing the neutralized gaseous mixture into the
ambient atmosphere.
42. A method for reacting chemically non-innocent gaseous mixtures
defined in claim 41, wherein the surfaces at elevated temperatures
are provided by at least one flame breaker.
43. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 41, further comprising the step of
providing a predefined temperature inside the reaction chamber by
controlling the amount of heat produced in a combustion of fuel and
air, and by mixing gases inside the reaction chamber with
additional gases at a different temperature.
44. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 43, further comprising the step of
adjusting the predefined temperature to fall within a range from
900.degree. C. to 1100.degree. C.
45. A method for thermally reacting chemically non-innocent gaseous
mixtures defined in claim 41, further comprising the step of
cooling the neutralized gaseous mixture after releasing it from the
reaction chamber and before releasing it into the ambient
atmosphere by mixing the neutralized gas mixture with gases at
lower temperature than the neutralized gas mixture.
Description
FIELD OF THE INVENTION
[0001] The invention generally relates to incinerators. More
specifically, the invention relates to incinerators used for
neutralizing effluent gaseous mixtures.
BACKGROUND OF THE INVENTION
[0002] During the last decade, the increasing importance of
environmental issues gained growing general recognition. The trend
to promote and enforce environmental friendliness, in the United
States reflected through institutions like the Environmental
Protection Agency (EPA), puts a special emphasis on the issue of
waste disposal in many industrial processes. This applies
especially to chemicals that can be legally released into the
environment, such as ammonia (NH.sub.3). According to the Toxics
Release Inventory (TRI) published by the EPA, the amount of total
air emissions of ammonia totaled 151,065,784 pounds in the U.S. in
1999. However, release of gaseous NH.sub.3 pollutes the environment
to a degree, which in certain cases might damage or even destroy
the ozone layer. Ammonia gas is now being increasingly recognized
as a pollutant, and emission limits are being currently established
by various jurisdictions around the world.
[0003] Many different industries produce effluent gaseous mixtures
containing ammonia, as for example foundries, solvent
manufacturers, asphalt roof shingle manufactures, charcoal
manufacturers, and nitriding and nitrocarburizing plants, among
others. Typical methods to dispose of and/or neutralize ammonia
containing gaseous mixtures include for example treatment of the
effluent gaseous mixture with solutions of an inorganic acid, as
described in U.S. Pat. No. 4,001,374 to Haese, issued Jan. 4, 1977,
and selective oxidation in the presence of a solid catalyst, as
described in U.S. Pat. No. 5,906,803 to Leppalahti, issued May 24,
1999. However, each of theses processes is afflicted with its own
difficulties and drawbacks. The treatment of NH.sub.3 containing
gaseous mixtures with inorganic acids produces chemical waste,
which by itself either has to be disposed of or regenerated. The
oxidation process described by Leppalathi typically applies to
gaseous mixtures containing only traces of ammonia, for example 0.5
Vol. %. Furthermore, this process utilizes the addition of an oxide
of nitrogen (NO.sub.x), a class of compounds carrying their own
individual environmental risks.
[0004] A promising alternative to the above-described methods is
high temperature endothermic dissociation of ammonia in the
presence of a metallic catalyst. During this process, NH.sub.3 is
dissociated into individual dinitrogen (N.sub.2) and dihydrogen
(H.sub.2) molecules, which are both totally benign, and may be
safely released to the environment. Also, no NO.sub.x compounds are
formed. Nevertheless, when this technique is chosen to remove
residual ammonia contained in the effluent gases stemming from a
nitriding process, it is applicable only to small and medium size
nitriding systems. Furthermore, problems generally encountered in
the field of catalysis are also an issue for such an endothermic
dissociation process.
[0005] It would be advantageous to provide an apparatus for
neutralizing ammonia containing gaseous mixtures that is simple and
efficient. Preferably, such a device would not utilize any further
catalytic or auxiliary components. It would be further advantageous
to provide a method, which allows for neutralization of gaseous
mixtures containing ammonia on a large range of scales, being
applicable to mixtures containing only a small amount of NH.sub.3
up to atmospheres of 100% NH.sub.3. It would also be advantageous
to provide an environmentally friendly method, in which
neutralization of ammonia results substantially in products, which
are benign, and which themselves do not provide further
environmental hazards. Of further advantage would be a method that
is cheap, efficient, and thus competitive with existing
technologies.
OBJECT OF THE INVENTION
[0006] In an attempt to overcome the limitations of the prior art
it is an object of the present invention to provide a process
atmosphere incinerator for neutralizing chemical non-innocent
gaseous mixtures that uses a thermally induced neutralization
reaction, and which does not rely on the use of auxiliary
components.
[0007] It is further an object of the present invention to provide
a process atmosphere incinerator, in which chemical non-innocent
gaseous mixtures are neutralized to form benign and environmentally
friendly products.
[0008] It is another object of the present invention to provide a
process atmosphere incinerator design, implementations of which
support neutralization of a wide range of amounts of non-innocent
gaseous mixtures of arbitrary composition.
SUMMARY OF THE INVENTION
[0009] In accordance with an aspect of the present invention, there
is provided a process atmosphere incinerator having a reaction
chamber for thermally reacting gaseous mixtures and a burner
connected to said reaction chamber, the process atmosphere
incinerator comprising a plurality of flame breakers disposed
inside said reaction chamber, the flame breakers providing surfaces
of elevated temperatures within gas flow paths.
[0010] In accordance with another aspect of the present invention,
there is provided a process atmosphere incinerator having a
reaction chamber for thermally reacting gaseous mixtures, and a
burner connected to the reaction chamber for horizontally
introducing a flame into the reaction chamber along a longitudinal
direction thereof, the process atmosphere incinerator having an
inlet for chemically non-innocent gaseous mixtures disposed on the
bottom section of the reaction chamber, an outlet for neutral
gaseous mixtures disposed on the top section of the reaction
chamber, and at least one partitioning wall inside the reaction
chamber for providing a substantially horizontal gas flow path from
the inlet to the outlet.
[0011] In accordance with an aspect of the present invention, there
is further provided a method for thermally reacting chemically
non-innocent gaseous mixtures, comprising the steps of introducing
chemically non-innocent gaseous mixtures into a reaction chamber,
introducing a horizontal flame into the reaction chamber along a
longitudinal direction thereof, providing surfaces of elevated
temperatures within gas flow paths inside the reaction chamber,
subjecting the chemically non-innocent gaseous mixture to thermally
induced chemical reactions while guiding it through the reaction
chamber, cooling the neutralized gaseous mixture before releasing
it from the reaction chamber, and releasing the neutralized gaseous
mixture into the ambient atmosphere.
[0012] In accordance with an aspect of the present invention, there
is also provided a method for thermally reacting chemically
non-innocent gaseous mixtures, comprising the steps of introducing
chemically non-innocent gaseous mixtures into a reaction chamber,
providing atmospheric turbulences within gas flow paths inside the
reaction chamber, providing surfaces of elevated temperatures
within gas flow paths inside the reaction chamber, subjecting the
chemically non-innocent gaseous mixture to thermally induced
chemical reactions while guiding it through the reaction chamber,
cooling the neutralized gaseous mixture before releasing it from
the reaction chamber, and releasing the neutralized gaseous mixture
into the ambient atmosphere.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Exemplary embodiments of the present invention will now be
described in conjunction with the following drawings, in which
similar reference numbers designate similar items:
[0014] FIG. 1 presents a schematic block diagram of a process
atmosphere incinerator;
[0015] FIG. 2 presents a side-view of a neutralization chamber of
the process atmosphere incinerator according to a first embodiment
of the present invention;
[0016] FIG. 3 presents a side view of a neutralization chamber of
the process atmosphere incinerator according to a second embodiment
of the present invention;
[0017] FIG. 4 presents a top view of the neutralization chamber of
the process atmosphere incinerator according to the second
embodiment of the present invention;
[0018] FIG. 5 presents a cross section of the neutralization
chamber of the process atmosphere incinerator according to the
second embodiment of the present invention;
[0019] FIG. 6 presents a top-view of a horizontal neutralization
chamber; and
[0020] FIG. 7 presents a side-view of a vertical neutralization
chamber.
DETAILED DESCRIPTION OF THE INVENTION
[0021] The following description is presented to enable a person
skilled in the art to make and use the invention, and is provided
in the context of a particular application thereof. Various
modifications to the disclosed embodiments will be readily apparent
to those skilled in the art, and the general principles defined
herein are easily applied to other embodiments and applications
without departing from the spirit and the scope of the invention.
Thus, the present invention is not intended to be limited to the
embodiments disclosed, but is to be accorded the widest scope
consistent with the principles and features disclosed herein.
[0022] In FIG. 1, a schematic block diagram of a process atmosphere
incinerator 1 is shown. The main chemical reactions take place in a
horizontal neutralization chamber 2. In the following, when
referring to a neutralization chamber, a horizontal neutralization
chamber is implied, unless specified otherwise. The neutralization
chamber 2 is equipped with an encasement or lining 3. The material
chosen for the lining 3 of the neutralization chamber 2 is selected
to be resilient to chemical corrosion from chemicals to be
neutralized or formed in the neutralization process and to be
resilient to melting at the incinerator operating temperature.
Typically a ceramic material is selected, which is chemically
inert, and serves as insulating layer as well as heat
reservoir.
[0023] The chemical reactions, which take place in the
neutralization chamber, are generally referred to herein as
neutralization reactions of chemically non-innocent gaseous
mixtures. Non-innocent gaseous mixtures contain substances in the
gas phase, which do not behave neutral in the sense of any common
acid/base-theory, including the HSAB concept of Pearson. Thus,
gaseous mixtures, which do not contain ammonia as in the present
example, but possibly contain hydrogen sulfide or carbon monoxide,
would qualify as non-innocent gaseous mixtures. A neutralization
reaction refers to any chemical reaction, in which the non-innocent
component of a gaseous mixture is transformed into one or more
neutral products. Since the neutralization reaction is thermally
initiated, the apparatus described in the present invention is
referred to as an incinerator. Since commonly gaseous mixtures to
be neutralized often are effluent gases stemming from certain
industrial processes, the apparatus described in the present
invention is referred to as a process atmosphere incinerator. Of
course, the use of such a process atmosphere incinerator is not
limited to the common or typical uses thereof. The neutralization
chamber 2 of the present embodiment is a specific example of a
reaction chamber for chemically reacting gaseous mixtures.
[0024] A burner nozzle 4 is connected to one of the sidewalls of
the neutralization chamber 2. The burner nozzle 4 horizontally
introduces a flame into the neutralization chamber along a
longitudinal direction thereof. The flame adjusts the reaction
conditions inside the neutralization chamber to a certain
temperature as well as to a certain atmospheric composition. The
burner nozzle 4 is connected to an air blower 5, and to a fuel feed
line 6. The combination of the burner nozzle 4, the air blower 5,
and the fuel feed line 6 is referred to as a burner. Typically,
natural gas is used as a fuel source to operate the burner.
Furthermore, an additional air feed line 7 is connected to the
neutralization chamber 2 for a fine-tuning of the combustion
conditions, and for an adjustment of the conditions for the
neutralization reaction. The gaseous mixture to be neutralized is
introduced through a feed line 8 into the neutralization chamber
2.
[0025] In the example of neutralizing NH.sub.3 under oxidative
conditions, three reactions are of major importance. The
neutralization reaction begins with the oxidation of ammonia to
form nitrogen oxides, for example nitrogen monoxide NO, as shown in
equation 1:
4NH.sub.3+5O.sub.2.fwdarw.4NO+6H.sub.2O+904 kJ/mol (1)
[0026] Nitrogen monoxide further reacts with additional ammonia to
produce dinitrogen and water, equation 2, both of which are benign
and natural occurring components in earth's atmosphere:
4NH.sub.3+6NO.fwdarw.5N.sub.2+6H.sub.2O+1816 kJ/mol (2)
[0027] Also, ammonia partly dissociates following an endothermic
decomposition reaction, as shown in equation 3:
2NH.sub.3.fwdarw.N.sub.2+3H.sub.2-94 kJ/mol (3)
[0028] As can be seen from the reaction equations, reactions 1 and
2 are exothermic, and produce heat, whereas reaction 3 is
endothermic, and consumes heat. For the overall reaction to
proceed, well-defined reaction conditions are desirable, in which a
fine balance between the three reactions is achieved. A certain
amount of heat and thus a certain temperature is preferable to
initiate the chemical reactions. On the other hand, if the
temperature is too high, reactions, in which heat is produced, will
be hampered. This effect will be most pronounced for the reaction,
in which the largest amount of heat is produced, namely reaction 2
(+1816 kJ/mol). As a consequence, not all the nitrogen monoxide
formed in reaction 1 will be consumed, which in turn leads to an
increased NO.sub.x level in the neutralized gaseous mixture
released to the atmosphere. It has been found that the
neutralization of ammonia using the apparatus and method of the
present embodiment is best carried out in a temperature range of
900-1100.degree. C. In this case, the average amount of NO.sub.x in
the emission gas released through a flue 9 to the ambient
atmosphere is less than 40 mg/m.sup.3. It has also been found that
the process according to the present invention almost
quantitatively neutralizes all ammonia present in an effluent gas.
The average amount of NH.sub.3 in the emission gas is less than 6
mg/m.sup.3.
[0029] A process control unit automatically adjusts the conditions
in the neutralization chamber 2. The process control unit comprises
a processor 10, which is connected to a sensor 11 for sensing the
conditions inside the neutralization chamber 2, to a control valve
12 for adjusting the amount of fuel fed to the burner, and to a
control valve 13, for adjusting the amount of additional air
introduced into the neutralization chamber 2. Thus, the process
control unit automatically maintains the optimum temperature
necessary to neutralize a known gaseous mixture. Depending on the
composition of the gaseous mixture to be neutralized, the overall
reaction might be either endothermic or exothermic. The amount of
oxygen, and therefore the amount of air supplied to the
neutralization chamber is adjusted to ensure that it is sufficient
to react with all the gases present. This includes not only the
gases to be neutralized, but also gaseous fuel and other reactants
if any as well. When the amount of exothermically reacting gases in
the gaseous mixture to be neutralized is low, more natural gas is
used to help to maintain an adequate reaction temperature. This is
typically the case in nitriding atmospheres diluted by N.sub.2. In
the case of the gaseous mixture to be neutralized containing a
higher amount of exothermically reacting gases, such as H.sub.2, a
vigorous reaction releasing large amounts of heat is generated and
the temperature of combustion rises. However, as illustrated above,
excessively high temperature is conducive to the generation of an
increased amount of NO.sub.x in the gases released by the process
atmosphere incinerator 1. To compensate for this effect, the
process control unit automatically adjusts the amounts of air and
natural gases. The processor 10 receives data from the sensor 11,
and accordingly adjusts the flow of air and fuel through an
automated setting of the control valves 12 and 13. The addition of
air not only serves to provide the adequate amount of oxygen, but
also helps to adjust the temperature of the reaction mixture.
[0030] In FIG. 2, a side-view down the latitudinal direction of the
neutralization chamber 2 according to a first embodiment of the
present invention is shown. The burner nozzle 4 is positioned in a
sidewall of the neutralization chamber as to introduce a flame into
the neutralization chamber along a longitudinal direction thereof.
A baffle 21, which extends horizontally along the longitudinal
direction of the neutralization chamber, and which is positioned
right above the burner nozzle 4, further helps to guide the flame
along the desired direction. An inlet 22 for the gaseous mixture to
be neutralized is positioned in the floor section of the
neutralization chamber, and right below the burner nozzle.
Alternatively, the gas inlet 22 for the gaseous mixture to be
neutralized is disposed in the same wall of the neutralization
chamber 2 as the burner nozzle 4. It is advantageous to place the
inlet 22 for the gaseous mixture to be neutralized below the burner
nozzle 4, so that the incoming gaseous mixture is directly
conducted to the hot zone of the neutralization chamber 2. An
outlet 23 connects the neutralization chamber 2 to the flue 9,
through which the neutralized gaseous mixture is released to the
atmosphere. The outlet 23 is disposed on the top section of the
neutralization chamber, and on the opposite site of the baffle 21,
with respect to the gas inlet 22. The baffle 21 not only serves to
direct the flame of the burner along a desired direction, but also
assists in guiding the gaseous mixture through the neutralization
chamber 2.
[0031] A plurality of flame breakers 24 is mounted inside the
neutralization chamber 2. A shape of a flame breaker 24 is
preferably that of an elongated parallelepiped, the flame breaker
24 being mounted vertically to the floor section of the
neutralization chamber 2. The direction of longitudinal extension
of the flame breaker 24 is perpendicular to the direction of
longitudinal extension of the flame introduced by the burner nozzle
4 into the neutralization chamber 2. Thus, the flame produced by
the burner strikes the plurality of flame breakers 24, and is
therefore disturbed. Breaking of the flame inside the
neutralization chamber 2 then introduces atmospheric disturbances
in the reactive region of the neutralization chamber 2. Here, the
reactive region is essentially the area where the flame breakers 24
are located. The plurality of flame breakers 24 fulfills a variety
of functions. The atmospheric turbulences introduced by the flame
breakers 24 result in a thorough mixing of the gases present in the
neutralization chamber 2, and avoid the build-up of either
temperature or concentration gradients. This promotes uniform
reaction conditions throughout the reactive region, and further
promotes an even distribution of the gaseous mixture inside the
neutralization chamber 2. Since the flame breakers 24 present an
obstacle in the path the gas travels from the inlet 22 through the
neutralization chamber to the outlet 23, the flame breakers 24
enhance the duration of stay of a single gas molecule in the
reactive region of the neutralization chamber 2. This causes an
increase of time available for a chemical reaction, and
consequently an increase in conversion rate. Also, the flame
breakers 24 provide a reactive surface, which possibly adsorbs
certain gases. It is believed that adsorption is in many cases an
essential step for activation of molecules to be neutralized, and
for initial predissociation. Gas molecules, like NH.sub.3, hit the
surface of the flame breaker 24, and undergo homolytic or
heterolytic bond cleavage, creating reactive radicals or ions.
These reactive species then undergo further reactions, eventually
leading to the formation of the final products. The presence of the
flame breakers 24 is therefore important in the conversion of
chemically non-innocent gaseous mixtures.
[0032] Alternatively, the flame breaker 24 is provided in the form
of a perforated brick. The perforation of the flame breaker 24
serves several purposes. Amongst other advantages, it increases the
amount of atmospheric turbulences in the neutralization chamber 2,
thus enhancing the beneficial effects resulting from atmospheric
disturbances as described above. The perforation also provides an
increased surface area of the flame breaker 24, thus allowing a
larger amount of gases to be adsorbed at the flame breaker 24.
[0033] According to the present embodiment, the flame breakers 24
are manufactured from a ceramic material. This material has a high
specific heat capacity, and serves as a heat reservoir. In
operation, the flame breakers 24 help to provide a certain base
temperature, which can be fine-tuned by admixture of ambient air,
and by adjusting the ratio of oxygen and fuel. The ceramic material
is chemically inert, and resistant to many of the reactive species
present in the gaseous mixture or adsorbed to the surface of the
flame breakers 24, even including nitride ions N.sup.3-. Thus, the
ceramic material not only ensures a high life span of the flame
breakers 24, but also reproducible reaction conditions. Further,
the flame breakers act to absorb heat from exothermic reactions
thereby mitigating the effects of rapidly progressing exothermic
reactions by reducing the rapid temperature rise within the chamber
caused thereby.
[0034] An inlet 25 for additional air is disposed in close
proximity to the outlet 23 for the neutralized gaseous mixture. The
additional air fed into the neutralization chamber 2 is usually at
ambient temperature, and therefore at a substantially lower
temperature than the inside of the neutralization chamber. Part of
the additional air coming from the inlet 25 will travel to the
reactive region of the neutralization chamber, thus providing the
adequate amount of oxygen to maintain chemical reactions. While
traveling inside the neutralization chamber 2, the additional air
will get into contact with the lining 3 and the flame breakers 24,
causing a certain degree of cooling of these components, and thus
adjusting the reaction conditions inside the neutralization chamber
2. Since the inlet 25 is disposed in vicinity to the outlet 23,
part of the additional air also mixes with the neutralized gaseous
mixture. This will rapidly cool down and dilute the effluent. This
way, it is safer to release the effluent from the neutralization
chamber. Components like the flue 9 or any other components, which
are in contact with the effluent from the process atmosphere
incinerator 1, do not have to withstand excessive thermal stress.
Also, the concentration of chemically non-innocent components in
the effluent, which is already very low due to the efficiency of
the apparatus described in the embodiment of the present invention,
is further reduced.
[0035] In FIG. 3, a side-view down the latitudinal direction of the
neutralization chamber 2 according to a second embodiment of the
present invention is shown. The baffle 21, the outlet 23, the flame
breaker 24, as well as the inlet 25 for additional air fulfill the
same functions as described above. Under a ceramic base plate 26
covering the floor section of the neutralization chamber 2, there
is running along the longitudinal direction thereof at least one
gas activation channel 27. The gas activation channel 27 comprises
a supply pipe 28 and a gas inlet 29, the supply pipe 28 and the gas
inlet 29 being positioned at opposite sites of the gas activation
channel 27. The gas inlet 29 is positioned in close proximity to
and below the burner nozzle 4. In operation of the process
atmosphere incinerator, the gas activation channel 27, which
extends through substantially the whole length of the
neutralization chamber 2, is heated to elevated temperatures. A
non-innocent gas mixture to be neutralized enters the
neutralization chamber through the supply pipe 28, passes through
the gas activation channel 27, and enters the reactive zone of the
neutralization chamber through the gas inlet 29. While passing
through the gas activation channel 27, the non-innocent gas mixture
to be neutralized is preheated. Preheating the non-innocent gas
mixture supports and aids the neutralization process. For example,
at elevated temperatures, the chemical equilibrium between ammonia
and H.sub.2 and N.sub.2, is shifted towards the side of the benign
dissociation products dihydrogen and dinitrogen, compare reaction
3. Thus, a certain amount of ammonia in the gas mixture to be
neutralized dissociates into H.sub.2 and N.sub.2, even before
reaching the combustion zone.
[0036] In FIG. 4, a top-view of the neutralization chamber 2
according to the second embodiment of the present invention is
shown. The neutralization chamber 2 comprises three gas activation
channels 27, each gas activation channel having a supply pipe 28
and a gas inlet 29. Alternatively, the neutralization chamber
comprises any other number of gas activation channels 27. The gas
activation channels 27 are welded from a shaped strip of a metallic
material. Preferably, the gas activation channels 27 are made from
Inconel.RTM., a nickel-chromium alloy consisting of about 70% Ni,
20% Cr, and additional metals, for example iron, Fe. Such alloys
are resistant to oxidation, reducing environments, corrosive
environments and high temperature environments, and posses good
mechanical properties. Therefore, Inconel.RTM. is well suited for
the use in furnace mufflers and heat-treating equipment.
Alternatively, the gas activation channels 27 are made from any
other material possessing a suitable amount of chemical inertness
to the conditions applied by the heated non-innocent gas mixtures,
and appropriate thermal conductivity.
[0037] In FIG. 5, a cross section of the neutralization chamber 2
according to the second embodiment of the present invention is
shown. Three gas activation channels 27 are shown disposed beneath
the ceramic base plate 26. The gas activation channels 27 posses a
rectangular cross-section. Alternatively, the gas activation are
made in a way as to possess any other type of suitable
cross-section, such as a round cross-section, a square
cross-section, or the like. Also, other ways of guiding the gas
activation channels 27 through the neutralization chamber are
easily envisioned. For example, the gas activation channels 27 are
positioned at the sidewalls of the neutralization chamber 2, or the
gas activation channels run through the neutralization chamber 2.
Preferably, the gas activation channels are provided as straight
tubular constructions. Alternatively, bent and winding tubular
constructions are provided as gas activation channels 27. When the
process atmosphere incinerator serves a plurality of different
processes at the same time, the effluent gaseous mixtures stemming
form each process are directed to different gas activation channels
27. If the process atmosphere incinerator serves only one process,
the effluent gaseous mixture is distributed among the plurality of
gas activation channels 27.
[0038] The neutralization chamber 2 according to the embodiments of
the present invention is preferably a horizontal neutralization
chamber. Alternatively, the neutralization chamber 2 is a vertical
neutralization chamber. Referring now to FIG. 6, a top-view of a
horizontal neutralization chamber 30 is shown. The sensor 11 is
mounted to a sidewall of the horizontal neutralization chamber 30,
and senses the atmospheric conditions in the reactive region of the
horizontal neutralization chamber 30. A longitudinal direction of
an oblong base of the flame breaker 24 forms an angle .xi. with the
longitudinal direction of the horizontal neutralization chamber 30.
The angle .xi. can be adjusted as to provide the best conditions
for flame breaking, leading to the highest conversion rates and the
lowest production of undesirable side products. In the apparatus
described in present invention, the angle .xi. amounts
approximately to 20.degree.. Alternative arrangements of flame
breakers include for example an asymmetric distribution of flame
breakers inside the neutralization chamber.
[0039] The horizontal design of the neutralization chamber 2 is
significant to the present invention for a variety of reasons. It
allows for a compact arrangement of the components comprising the
neutralization chamber 2, and it also allows for a facile extension
of the capacity of the process atmosphere incinerator. Given a
predefined spacing between two flame breakers 24, increasing the
number of flame breakers 24 increases the size of the reactive zone
of the neutralization chamber. This in turn increases the maximum
process gas flow. Process atmosphere incinerators 1 according to
the present invention with a process gas flow in the range from 65
l/min up to 1000 l/min have been demonstrated. Depending on the
size of the neutralization chamber 2, the capacity of the burner 4,
and the number of flame breakers 24 disposed inside the
neutralization chamber 2, among other characteristics of the
process atmosphere incinerator 1, some flame breakers of the
plurality of flame breakers 24 are not within the path of the flame
created by the burner 4. However, all of the flame breakers 24
fulfill the important functions of introducing atmospheric
turbulences inside the neutralization chamber 2, and prolonging the
duration of stay of molecules to be neutralized in the reactive
region. Optionally, two flames are introduced into the
neutralization chamber from two burner nozzles disposed on opposing
sides of the neutralization chamber. The horizontal design further
allows for a vertical arrangement of the flame breakers. This
enables one to build the flame breakers using commercially
available ceramic building blocks. On the other hand, a vertical
design of the neutralization chamber would lend itself to a
construction, in which the flame breakers are to be horizontally
mounted. The thermal stress then is likely to cause the flame
breakers to fail under gravitational strain. In order to avoid
this, tailor-made flame breakers are to be used, dramatically
increasing the production cost of a process atmosphere incinerator.
Even though the use of horizontal flame breakers is believed to be
less preferred, horizontally disposed flame breakers still benefit
substantially from the inventive features of the invention, and
their use is not intended to be excluded.
[0040] In FIG. 7, a side-view down the latitudinal direction of a
vertical neutralization chamber 40 is shown. Like the horizontal
neutralization chamber 30, the vertical neutralization chamber 40
comprises an inlet 22 for the gaseous mixture to be neutralized, an
outlet 23 for the neutralized gaseous mixtures, and a plurality of
flame breakers 24. Further, a burner nozzle 4 is disposed in one of
the walls of the vertical neutralization chamber 40.
Advantageously, the burner nozzle 4 is disposed in the lower
section of the vertical neutralization chamber 40. Further
advantageously, the burner nozzle 4 is disposed in the floor
section of said vertical neutralization chamber 40. In this
example, the flame breakers 24 are horizontally mounted.
Nevertheless, the flame breakers 24 fulfill the basic functions of
introducing atmospheric turbulences inside the vertical
neutralization chamber 40, and providing surfaces at elevated
temperatures, which help to control the reaction temperature inside
the vertical neutralization chamber 40, prolong the duration of
stay of molecules to be neutralized in the reactive region of the
vertical neutralization chamber 40, and support possible activation
through predissociation of molecules to be neutralized. Of course,
various other designs of neutralization chambers are envisaged, in
which flamebreakers serve the same purpose as described above.
[0041] As previously mentioned, the shape of the flame breaker 24
is preferably that of an elongated parallelepiped. However, the
shape of the flame breaker 24 is optionally varied as to provide
the most efficient atmospheric turbulences for a certain
construction of the neutralization chamber. The most effective
shape of the flame breaker 24 depends on whether the flame breakers
24 are used in vertically or horizontally operating process
atmosphere incinerators. For example, the shape of the flame
breaker is optionally chosen as an elongated triangular prism.
Further optionally, the sidewalls of the flamebreakers constitute
curved surfaces, rather than plane surfaces. It is possible to
envisage flame breakers 24 having concave surfaces, convex
surfaces, or any combination of all of the above-mentioned surface
types. Alternatively, the shape of the flame breaker 24 is that of
a plate having perforations or holes for passage through of the
flame and the gases inside the neutralization chamber 2. These
openings in the flame breakers 24 cause a vigorous mixing of the
gases inside the neutralization chamber 2. Various other shapes and
forms of the flame breakers 24 are easily envisioned.
[0042] The process atmosphere incinerator 1 of the present
invention also lends itself to catalytic applications. Optionally,
the flame breakers 24 are coated with catalytically active
material. Such a treatment then extends the scope of the apparatus
described in the present invention to include a whole variety of
neutralization reactions carried out in the gas phase.
[0043] It is further possible to incorporate heat-exchanging
elements (not shown) inside the neutralization chamber 2. Since in
many cases the neutralization reactions are exothermic reactions, a
certain amount of excess heat is produced during the neutralization
of chemical non-innocent gaseous mixtures. The heat-exchanging
elements are not only used to dispose of the excess heat, but also
to introduce the energy gained from the neutralization reaction
into other processes. The excess heat is for example used to
preheat the chemically non-innocent gaseous mixtures to be
neutralized. This way, the portion of the time the gaseous mixture
stays in the reactive region, which is spend to thermally activate
the molecules to be neutralized, is significantly reduced.
Therefore, the amount of time available for the neutralization
reaction is increased, and the efficiency of the process atmosphere
incinerator 1 is enhanced.
[0044] Although the present invention has been described with
respect to specific embodiments thereof, various changes and
modifications can be carried out by those skilled in the art
without departing from the scope of the invention. Therefore, it is
intended that the present invention encompass such changes and
modifications as fall within the scope of the appended claims.
* * * * *