U.S. patent application number 10/623686 was filed with the patent office on 2005-01-27 for simultaneous reduction in nox and carbon in ash from using manganese in coal burners.
Invention is credited to DiGiamberardino, Tommaso, Factor, Stephen A..
Application Number | 20050016057 10/623686 |
Document ID | / |
Family ID | 33490858 |
Filed Date | 2005-01-27 |
United States Patent
Application |
20050016057 |
Kind Code |
A1 |
Factor, Stephen A. ; et
al. |
January 27, 2005 |
Simultaneous reduction in NOx and carbon in ash from using
manganese in coal burners
Abstract
The present invention relates to an additive and method to
simultaneously reduce both the carbon in ash and the NOx production
levels resulting from the combustion of coal by the use of at least
one manganese-containing additive. Use of a manganese-containing
additive in a coal burning utility furnace results in both a lower
carbon in ash content and lower NOx emissions.
Inventors: |
Factor, Stephen A.;
(Richmond, VA) ; DiGiamberardino, Tommaso; (Ittre,
BE) |
Correspondence
Address: |
Mr. Dennis H. Rainear
Patent & Trademark Division
Ethyl Petroleum Additives, Inc.
330 South Fourth Street
Richmond
VA
23219
US
|
Family ID: |
33490858 |
Appl. No.: |
10/623686 |
Filed: |
July 21, 2003 |
Current U.S.
Class: |
44/354 ; 44/358;
44/359; 44/363; 44/365; 44/366 |
Current CPC
Class: |
C10L 10/02 20130101;
C10L 10/06 20130101; C10L 9/10 20130101 |
Class at
Publication: |
044/354 ;
044/358; 044/359; 044/363; 044/365; 044/366 |
International
Class: |
C10L 005/00; C10L
001/18; C10L 001/30; C10L 001/26; C10L 001/24 |
Claims
What is claimed is:
1. A method of reducing both the amount of carbon in fly ash and
the amount of NOx resulting from the combustion of coal, the method
comprising combining coal and an additive that comprises a
manganese-containing compound forming a mixture thereof; and
combusting said mixture in a combustion chamber; the
manganese-containing compound being present in an amount effective
to reduce both the amount of carbon in fly ash and the amount of
NOx resulting from the combusting of the coal in the combustion
chamber.
2. The method as described in claim 1, wherein the manganese
compound is an organometallic compound.
3. The method as described in claim 2, wherein the organo portion
of the organometallic compound is derived from a material selected
from the group consisting of alcohols, aldehydes, ketones, esters,
anhydrides, sulfonates, phosphonates, naphthenates, chelates,
phenates, crown ethers, carboxylic acids, amides, acetyl acetonates
and mixtures thereof.
4. The method described in claim 2, wherein the organometallic
compound comprises methylcyclopentadienyl manganese
tricarbonyl.
5. The method described in claim 2, wherein the manganese compound
is selected from the following group: cyclopentadienyl manganese
tricarbonyl, methylcyclopentadienyl manganese tricarbonyl,
dimethylcyclopentadienyl manganese tricarbonyl,
trimethylcyclopentadienyl manganese tricarbonyl,
tetramethylcyclopentadienyl manganese tricarbonyl,
pentamethylcyclopentadienyl manganese tricarbonyl,
ethylcyclopentadienyl manganese tricarbonyl,
diethylcyclopentadienyl manganese tricarbonyl,
propylcyclopentadienyl manganese tricarbonyl,
isopropylcyclopentadienyl manganese tricarbonyl,
tert-butylcyclopentadienyl manganese tricarbonyl,
octylcyclopentadienyl manganese tricarbonyl,
dodecylcyclopentadienyl manganese tricarbonyl,
ethylmethylcyclopentadienyl manganese tricarbonyl, indenyl
manganese tricarbonyl, and the like, including mixtures of two or
more such compounds.
6. The method of claim 1, wherein the manganese-containing compound
is selected from the group consisting of manganese oxides,
manganese sulfates, and manganese phosphates.
7. The method as described in claim 1, wherein the manganese
compound comprises about 20 ppm of the coal.
8. The method as described in claim 1, wherein the manganese
compound comprises about 5 to 100 ppm of the coal.
9. The method as described in claim 1, wherein the manganese
compound comprises about 1 to 500 ppm of the coal.
10. The method as described in claim 1, wherein the additive is
introduced into an air stream that carries the coal into the
combustion chamber.
11. A method of reducing both the amount of carbon in fly ash and
the amount of NOx resulting from the combustion of coal, the method
comprising combining coal and an additive that comprises a
manganese-containing compound forming a mixture thereof; and
combusting said mixture in a combustion chamber; the
manganese-containing compound being present in an amount effective
to reduce both the amount of carbon in fly ash and the amount of
NOx resulting from the combusting of the coal in the combustion
chamber, wherein the additive is introduced directly into the
combustion chamber separately from the coal.
12. The method as described in claim 11, wherein the additive is
introduced into a flue gas recirculation stream.
13. The method as described in claim 11, wherein the additive is
introduced into a secondary air stream that is delivered into the
combustion chamber.
14. A method of reducing both the amount of carbon in fly ash and
the amount of NOx resulting from the combustion of coal, the method
comprising: combining coal and an additive that comprises a
manganese compound to form a mixture thereof; introducing the
mixture of coal and additive into a coal burning combustion
chamber; combusting the mixture in the combustion chamber; and the
manganese compound being present in an amount effective to reduce
both the amount of carbon in fly ash and the amount of NOx
resulting from the combustion of the coal in the combustion
chamber.
15. A coal additive for use in reducing both the amount of carbon
in the fly ash and the amount of NOx resulting from the combustion
of coal, the additive comprising a manganese compound wherein the
manganese compound is added to the coal prior to combustion at a
treat rate of about 1 to 500 ppm of the coal.
16. The coal additive as described in claim 14, wherein the
manganese compound is added to the coal prior to combustion at a
treat rate of about 5 to 100 ppm of the coal.
17. The coal additive as described in claim 14, wherein the
manganese compound is added to the coal prior to combustion at a
treat rate of about 20 ppm of the coal.
18. A method of reducing simultaneously the amount of carbon in fly
ash, the amount of NOx, and the amount of carbon monoxide resulting
from the combustion of coal, the method comprising combining coal
and an additive that comprises a manganese-containing compound
forming a mixture thereof; and combusting said mixture in a
combustion chamber; the manganese-containing compound being present
in an amount effective to reduce the amount of carbon in fly ash,
the amount of NOx, and the amount of carbon monoxide resulting from
the combusting of the coal in the combustion chamber.
19. A method of reducing both the amount of carbon monoxide and the
amount of NOx resulting from the combustion of coal, the method
comprising combining coal and an additive that comprises a
manganese-containing compound forming a mixture thereof; and
combusting said mixture in a combustion chamber; the
manganese-containing compound being present in an amount effective
to reduce both the amount of carbon monoxide and the amount of NOx
resulting from the combusting of the coal in the combustion
chamber.
20. A method of reducing both the amount of carbon in fly ash and
the amount of NOx resulting from the combustion of coal, the method
comprising combusting coal in the presence of at least 1 ppm of a
manganese-containing additive, whereby the amount of carbon in fly
ash and the amount of NOx resulting from the combustion of said
coal are both reduced relative to the amounts of carbon in fly ash
and NOx resulting from the combustion of coal in the absence of the
manganese-containing additive.
21. A method for stabilizing coal combustion by combusting coal in
the presence of at least 1 ppm of a manganese-containing additive,
whereby the amount of carbon in fly ash and the amount of NOx
resulting from the combustion of said coal are both reduced
relative to the amounts of carbon in fly ash and NOx resulting from
the combustion of coal in the absence of the manganese-containing
additive, and whereby combustion stability is improved relative to
the combustion stability of the coal in the absence of the
manganese-containing additive.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an additive and a method
for simultaneously reducing the production of both NOx and carbon
in ash from the combustion of fuel containing coal by means of
adding to the fuel an effective amount of a manganese compound.
BACKGROUND
[0002] When burning fuels such as fuel oil and coal in boilers,
incinerators, and utility furnaces, the ability to achieve high
combustion efficiency and low emissions is of paramount importance.
One of the most direct ways to improve combustion efficiency is to
increase the volume of combustion air in order to ensure a complete
oxidation of carbon-carbon, carbon-hydrogen, and carbon-heteroatom
bonds to give combustion products of carbon dioxide and water.
Higher carbon dioxide content in the combustion products means
increased combustion efficiency and also lower carbon content in
the ash. Unfortunately, an increase in the volume of combustion air
can promote NOx formation. In other words, with increased
combustion air, there is an inverse relationship between combustion
efficiency (reduced carbon in ash) and NOx production, such that
when one is improved, the other deteriorates. This problem is
particularly manifest in combustion systems employing a
recirculation of exhaust gases, such as those commonly referred to
as Flue Gas Recirculation (FGR) systems. By lowering the flame
temperature, FGR lowers NO.sub.x at the expense of increased carbon
in ash. Conventional combustion science ascribed to this type of
combustion at ambient pressure teaches that there is a trade-off
between NOx and unburned carbon, namely measures that are designed
to lower NOx will inherently increase levels of unburned carbon,
and vice versa. Metal-containing additives are known to achieve one
or the other, in various combustion systems, but not both
simultaneously. Previous and conventional attempts to get around
this usually required a series of multiple methods applied to each
carbon burnout and NOx independently in order to keep them under
control or at acceptable levels.
SUMMARY OF THE EMBODIMENTS
[0003] In an embodiment, the present invention relates to methods
to improve both the carbon burnout (i.e., lower carbon in ash) of
coal burning facilities and the NOx production levels by the use of
at least one manganese-containing additive compound. Use of a
manganese-containing additive in a coal burning facility, such as a
utility furnace, as taught herein, results in both a lower carbon
in ash content and lower NOx emissions.
[0004] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory only and are intended to provide further
explanation of the present invention, as claimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 illustrates the performance of a manganese containing
additive on NOx reduction.
[0006] FIG. 2 illustrates the reduction of carbon in ash and carbon
monoxide by the use of a manganese-containing additive.
DETAILED DESCRIPTION OF EMBODIMENTS
[0007] Conventional combustion science ascribed to the combustion
of coal at ambient pressure teaches that there is a trade-off
between NOx and unburned carbon. Namely, measures that are designed
to lower NOx will inherently increase levels of unburned carbon,
and vice versa.
[0008] In an embodiment herein, a manganese-containing additive is
combined with a fuel containing, inter alia, coal. The
manganese-containing additive catalyzes an improved carbon burnout
(i.e. lowering carbon in ash) during the entire combustion
process--both in the high and low temperature regions of the
combustion system (i.e. in the flame front with temperatures as
high as 3600.degree. F. and downstream of this to temperatures as
low as 550.degree. F.).
[0009] On the other hand, NOx reduction occurs only downstream of
the flame front at temperatures outside the significant thermal NOx
forming temperature range that is above 2500.degree. F. Below about
2500.degree., NOx competes with oxygen in the carbon oxidation of
manganese-containing combustion byproduct particulate (soot or fly
ash). The manganese catalyzes this carbon oxidation reaction, which
is faster when NOx is the source of oxygen and when the
temperatures fall. This carbon oxidation by NOx catalyzed by
manganese is efficacious down to a temperature of about 550.degree.
F. This NOx reduction chemistry can take place on carbon-containing
particulate such as soot or fly ash, even when the combustion
settings are at a high air to fuel ratio (i.e. running at excess
oxygen to stoichiometric, or fuel lean). This is because the
environment at the carbon-containing particulate is fuel rich, a
condition necessary for NOx reduction. Thus, the manganese mixed
with the carbon-containing particulate (fuel-rich) is able to
catalyze carbon burnout utilizing either combustion oxygen or NOx
as the oxidant. In this manner, carbon in ash is lowered
simultaneously with a NOx reduction. Carbon monoxide (CO) levels
also drop during use of a manganese-containing additive, showing
improved combustion efficiency in converting carbon to the more
oxidized carbon dioxide combustion product.
[0010] Therefore in another embodiment herein is presented a method
of reducing simultaneously the amount of carbon in fly ash, the
amount of NOx, and the amount of carbon monoxide resulting from the
combustion of coal, the method comprising combining coal and an
additive that comprises a manganese-containing compound forming a
mixture thereof; and combusting said mixture in a combustion
chamber; the manganese-containing compound being present in an
amount effective to reduce the amount of carbon in fly ash, the
amount of NOx, and the amount of carbon monoxide resulting from the
combusting of the coal in the combustion chamber.
[0011] Yet another embodiment provides a method of simultaneously
reducing both the amount of carbon monoxide and the amount of NOx
resulting from the combustion of coal, the method comprising
combining coal and an additive that comprises a
manganese-containing compound forming a mixture thereof; and
combusting said mixture in a combustion chamber; the
manganese-containing compound being present in an amount effective
to reduce both the amount of carbon monoxide and the amount of NOx
resulting from the combusting of the coal in the combustion
chamber.
[0012] An additional embodiment provides a method of reducing both
the amount of carbon in fly ash and the amount of NOx resulting
from the combustion of coal, the method comprising combusting coal
in the presence of at least 1 ppm of a manganese-containing
additive, whereby the amount of carbon in fly ash and the amount of
NOx resulting from the combustion of said coal are both reduced
relative to the amounts of carbon in fly ash and NOx resulting from
the combustion of coal in the absence of the manganese-containing
additive.
[0013] Yet another additional embodiment provides a method for
stabilizing combustion while operating in the FGR mode. When the
furnace is operated at an FGR rate to achieve significant NOx
reduction, combustion instability is normally experienced as a
result of the cooler flame due to the FGR. This instability leads
to combustion inefficiency and increased hydrocarbon, carbon
monoxide, and particulate with high carbon content (smoke and
soot). Thus is provided a method for stabilizing coal combustion by
combusting coal in the presence of at least 1 ppm of a
manganese-containing additive, whereby the amount of carbon in fly
ash and the amount of NOx resulting from the combustion of said
coal are both reduced relative to the amounts of carbon in fly ash
and NOx resulting from the combustion of coal in the absence of the
manganese-containing additive, and whereby combustion stability is
improved relative to the combustion stability of the coal in the
absence of the manganese-containing additive.
[0014] Examples of manganese-containing compounds useful herein as
coal additives include both inorganic and organometallic compounds.
Inorganic manganese compounds useful herein can include one or more
of manganese oxides, manganese sulfates, and manganese
phosphates.
[0015] Preferred organometallic compounds in an embodiment of the
present invention include alcohols, aldehydes, ketones, esters,
anhydrides, sulfonates, phosphonates, naphthenates, chelates,
phenates, crown ethers, carboxylic acids, amides, acetyl
acetonates, and mixtures thereof. Manganese containing
organometallic compounds include manganese tricarbonyl compounds.
Such compounds are taught, for example, in U.S. Pat. Nos.
4,568,357; 4,674,447; 5,113,803; 5,599,357; 5,944,858 and European
Patent No. 466 512 B1.
[0016] Suitable manganese tricarbonyl compounds which can be used
include cyclopentadienyl manganese tricarbonyl,
methylcyclopentadienyl manganese tricarbonyl,
dimethylcyclopentadienyl manganese tricarbonyl,
trimethylcyclopentadienyl manganese tricarbonyl,
tetramethylcyclopentadie- nyl manganese tricarbonyl,
pentamethylcyclopentadienyl manganese tricarbonyl,
ethylcyclopentadienyl manganese tricarbonyl,
diethylcyclopentadienyl manganese tricarbonyl,
propylcyclopentadienyl manganese tricarbonyl,
isopropylcyclopentadienyl manganese tricarbonyl,
tert-butylcyclopentadienyl manganese tricarbonyl,
octylcyclopentadienyl manganese tricarbonyl,
dodecylcyclopentadienyl manganese tricarbonyl,
ethylmethylcyclopentadienyl manganese tricarbonyl, indenyl
manganese tricarbonyl, and the like, including mixtures of two or
more such compounds. One example is the cyclopentadienyl manganese
tricarbonyls which are liquid at room temperature such as
methylcyclopentadienyl manganese tricarbonyl, ethylcyclopentadienyl
manganese tricarbonyl, liquid mixtures of cyclopentadienyl
manganese tricarbonyl and methylcyclopentadienyl manganese
tricarbonyl, mixtures of methylcyclopentadienyl manganese
tricarbonyl and ethylcyclopentadienyl manganese tricarbonyl,
etc.
[0017] Preparation of such compounds is described in the
literature, for example, U.S. Pat. No. 2,818,417, the disclosure of
which is incorporated herein in its entirety.
[0018] The combustion systems that may use the manganese-containing
coal additive compounds described herein include any and all
internal and external combustion devices, machines, engines,
turbine engines, boilers, incinerators, evaporative burners,
stationary burners and the like which can combust or in which can
be combusted a hydrocarbonacous fuel such as coal. Coal burning
furnaces, particularly large systems, are all uniquely designed.
However, most have primary air streams that deliver coal to and
through a grinding process and eventually to the combustion chamber
in the furnace. In the furnace, there may be one or more secondary
air streams that also feed air into the combustion chamber.
[0019] The manganese-containing coal additive compound can be mixed
with the coal either before or simultaneously in the combustion
chamber. For instance, the manganese compound may be injected into
the primary air stream for mixing with the coal before the
combustion chamber. Alternatively, the manganese compound may be
injected with a secondary air stream into and mixed in with the
coal in the combustion chamber. Finally, the additive having the
manganese compound may be injected separately into the coal and
directly into the combustion chamber. In any alternative, there
will be conditions that cause the effective mixture of the additive
having the manganese compound in the coal so that the manganese
atoms will be present and available for catalytic activity. The
additive can be a liquid form so that it is miscible with liquid
fuels and easily dispersed in the combustion air by atomizing
nozzles and mild heat.
[0020] The treat rate of the manganese compound with the coal is
between 1 to about 500 ppm. An alternative treat rate is from about
5 to 100 ppm manganese. In a further embodiment, the treat rate is
20 ppm manganese to the coal.
[0021] The following example further illustrates certain aspects of
the present invention but does not limit the present invention.
EXAMPLE
[0022] A test was carried out in a 300 megawatt (MW) coal-burning
utility furnace. The testing, which lasted 46 days, was roughly
split into periods. The first period was a baseline conducted
without the use of the manganese-containing additive, the second
was conducted with the manganese-containing additive added, and the
last period was the baseline repeat. The manganese-containing
additive was injected into a flue gas recirculation stream. As a
result of the introduction of the manganese-containing additive,
NOx levels were observed to drop from an average of 189 ppm to 155
ppm, a lowering of 18%. At the same time, as a result of the
introduction of the manganese-containing additive, the amount of
carbon in ash fell from an average of about 20.4% to 9.4%, a
decrease of about 54%. To simultaneously lower NOx and carbon in
ash with one method or a single additive is unexpected in this type
of combustion.
[0023] FIGS. 1 and 2 demonstrate the results of the use of a
manganese-containing additive in the simultaneous lowering of
carbon in ash and NOx in the combustion products from the foregoing
example. FIG. 2 demonstrates the results of the use of a
manganese-containing additive in the simultaneous lowering of
carbon in ash, NOx, and carbon monoxide in the combustion products
from the foregoing example. The data were collected from a
coal-fired unit burning the same coal for the entire period, and
are based on the daily average data at 200 MW plus or minus 10 MW.
"GB" represents the introduction of a manganese-containing coal
additive referred to as Greenburn.RTM. 2001HF Combustion Catalyst
into the combustion unit. As can be seen from the results, there
was a substantial simultaneous reduction in NOx, carbon in ash, and
carbon monoxide. The resulting reduction in NOX was 17%, the
reduction in fly ash carbon content was 48%, and the reduction in
flue gas carbon monoxide was 30%.
[0024] It is to be understood that the reactants and components
referred to by chemical name anywhere in the specification or
claims hereof, whether referred to in the singular or plural, are
identified as they exist prior to coming into contact with another
substance referred to by chemical name or chemical type (e.g., base
fuel, solvent, etc.). It matters not what chemical changes,
transformations and/or reactions, if any, take place in the
resulting mixture or solution or reaction medium as such changes,
transformations and/or reactions are the natural result of bringing
the specified reactants and/or components together under the
conditions called for pursuant to this disclosure. Thus the
reactants and components are identified as ingredients to be
brought together either in performing a desired chemical reaction
(such as formation of the organometallic compound) or in forming a
desired composition (such as an additive concentrate or additized
fuel blend). It will also be recognized that the additive
components can be added or blended into or with the base fuels
individually per se and/or as components used in forming preformed
additive combinations and/or sub-combinations. Accordingly, even
though the claims hereinafter may refer to substances, components
and/or ingredients in the present tense ("comprises", "is", etc.),
the reference is to the substance, components or ingredient as it
existed at the time just before it was first blended or mixed with
one or more other substances, components and/or ingredients in
accordance with the present disclosure. The fact that the
substance, components or ingredient may have lost its original
identity through a chemical reaction or transformation during the
course of such blending or mixing operations or immediately
thereafter is thus wholly immaterial for an accurate understanding
and appreciation of this disclosure and the claims thereof.
[0025] At numerous places throughout this specification, reference
has been made to a number of U.S. patents, published foreign patent
applications and published technical papers. All such cited
documents are expressly incorporated in full into this disclosure
as if fully set forth herein.
[0026] This invention is susceptible to considerable variation in
its practice. Therefore the foregoing description is not intended
to limit, and should not be construed as limiting, the invention to
the particular exemplifications presented hereinabove. Rather, what
is intended to be covered is as set forth in the ensuing claims and
the equivalents thereof permitted as a matter of law.
[0027] Patentee does not intend to dedicate any disclosed
embodiments to the public, and to the extent any disclosed
modifications or alterations may not literally fall within the
scope of the claims, they are considered to be part of the
invention under the doctrine of equivalents.
* * * * *