U.S. patent application number 11/623402 was filed with the patent office on 2008-07-17 for safe combustion additives and methods of formulation.
Invention is credited to Allen A. Aradi, Stephen A. Factor, Gregory H. Guinther, Joseph W. Roos.
Application Number | 20080168709 11/623402 |
Document ID | / |
Family ID | 39332165 |
Filed Date | 2008-07-17 |
United States Patent
Application |
20080168709 |
Kind Code |
A1 |
Aradi; Allen A. ; et
al. |
July 17, 2008 |
SAFE COMBUSTION ADDITIVES AND METHODS OF FORMULATION
Abstract
A safe, metal-containing combustion additive and a method of
formulation is directed for use in connection with utility and
industrial furnaces. The additive includes a metal-containing
catalyst, a ligand for complexing with the catalyst and a solvent
for carrying the catalyst/ligand complex. The vapor pressure of the
additive is less than about 200.times.10.sup.-5 Torr at 100.degree.
F.
Inventors: |
Aradi; Allen A.; (Glen
Allen, VA) ; Factor; Stephen A.; (Richmond, VA)
; Guinther; Gregory H.; (Richmond, VA) ; Roos;
Joseph W.; (Mechanicsville, VA) |
Correspondence
Address: |
NEWMARKET SERVICES CORPORATION;c/o Thomas & Raring, P.C.
536 GRANITE AVENUE
RICHMOND
VA
23226
US
|
Family ID: |
39332165 |
Appl. No.: |
11/623402 |
Filed: |
January 16, 2007 |
Current U.S.
Class: |
44/641 |
Current CPC
Class: |
C10L 9/10 20130101; C10L
1/1886 20130101; C10L 1/305 20130101; C10L 1/1888 20130101; C10L
10/02 20130101; C10L 10/04 20130101; C10L 1/14 20130101; C10L
1/2608 20130101; C10L 1/2437 20130101; C10L 1/1881 20130101; C10L
10/00 20130101; C10L 1/1814 20130101; C10L 1/189 20130101; C10L
1/1828 20130101; C10L 1/1616 20130101; C10L 1/301 20130101 |
Class at
Publication: |
44/641 |
International
Class: |
C10L 9/10 20060101
C10L009/10 |
Claims
1. A combustion additive for use in utility and/or industrial
furnaces, the additive comprising: a metal-containing catalyst, a
ligand for complexing with the catalyst, and a solvent for carrying
the catalyst/ligand complex, wherein the vapor pressure of the
additive is less than about 200.times.10.sup.-5 Torr at 100.degree.
F.
2. The combustion additive described in claim 1, wherein the
catalyst is comprised of a plurality of metals.
3. A combustion additive as described in claim 1, wherein the
catalyst is comprised of manganese.
4. A combustion additive as described in claim 2, wherein the
catalyst is comprised of a plurality of metals selected from the
group consisting of manganese, calcium, magnesium, potassium, zinc,
copper and aluminum.
5. A combustion additive as described in claim 1, wherein the
catalyst is comprised of a metal selected from the group consisting
of manganese, calcium, magnesium, potassium, zinc, copper and
aluminum.
6. A combustion additive as described in claim 1, wherein the
ligand is selected from the group consisting of fossil fuel derived
carboxylates, natural product derived carboxylates, and synthetic
carboxylates and mixtures thereof.
7. A combustion additive as described in claim 1, wherein the
additive has a HMIS health rating of one or zero.
8. A combustion additive as described in claim 6, wherein the
additive has a HMIS health rating of one or zero.
9. A combustion additive as described in claim 1, wherein the vapor
pressure of the additive is less than about 70.times.10.sup.-5 Torr
at 100.degree. F.
10. A method of formulating a combustion additive for use in
utility and/or industrial furnaces, the method comprising:
selecting a metal-containing catalyst for use in utility and/or
industrial furnaces, complexing the metal-containing catalyst with
a ligand, and adding a solvent to carry the catalyst/ligand
complex, wherein the vapor pressure of the additive is less than
about 200.times.10.sup.-5 Torr at 100.degree. F.
11. The method described in claim 10, wherein the catalyst is
comprised of a plurality of metals.
12. A method as described in claim 10, wherein the catalyst is
comprised of manganese.
13. A method as described in claim 11, wherein the catalyst is
comprised of a plurality of metals selected from the group
consisting of manganese, calcium, magnesium, potassium, zinc,
copper and aluminum.
14. A method as described in claim 10, wherein the catalyst is
comprised of a metal selected from the group consisting of
manganese, calcium, magnesium, potassium, zinc, copper and
aluminum.
15. A method as described in claim 10, wherein the ligand is
selected from the group consisting of fossil fuel derived
carboxylates, natural product derived carboxylates, and synthetic
carboxylates and mixtures thereof.
16. A method as described in claim 10, wherein the additive has a
HMIS health rating of one or zero.
17. A method as described in claim 10, wherein the additive has a
HMIS health rating of one or zero.
18. A method as described in claim 10, wherein the pressure of the
additive is less than 70.times.10.sup.-5 Torr at 100.degree. F.
19. A method of minimizing health exposure to combustion additives
to be used in utility and/or industrial furnaces, the method
comprising: selecting a metal-containing catalyst for use in
utility and/or industrial furnaces, complexing the metal-containing
catalyst with a ligand, and adding a solvent to carry the
catalyst/ligand complex, wherein the vapor pressure of the additive
is less than about 200.times.10.sup.-5 Torr at 100.degree. F.
20. A method as described in claim 19, wherein the pressure of the
additive is less than 70.times.10.sup.-5 Torr at 100.degree. F.
21. A packaged product comprising: (a) the combustion additive of
claim 1, (b) packaging on, around or associated with said additive,
and (c) indicia or labeling on said packaging, said indicia or
labeling indicating a HMIS health rating of one or zero.
Description
[0001] The present invention relates to metal-containing combustion
additives for use in utility and industrial furnaces. Specifically,
the additive and methods of formulation are relatively safe from
the perspective of health ratings, thereby resulting in more
user-friendly working conditions.
BACKGROUND
[0002] Oil and coal burning utility boilers and furnaces suffer
from environmental issues due to particulate, NO.sub.x, and
SO.sub.x pollutant emissions. As control of environmental emissions
through additive treatment of fuels in use at utility power plants
becomes increasingly important, the issue of safe storage and use
of additives on the plant site gains more attention. Therefore
utility power plant operators no longer just focus on the efficacy
of the additive to perform as promised, but also are concerned
about the safety of having such chemicals stored and used on site.
As a result, it is desirable to formulate these additives with this
point foremost in mind.
[0003] These additives have to be stored on site in reasonable
amounts to perform the intended task without interruption of fuel
treatment. This is because their peak effectiveness often depends
on continuous treatment of the fuel to maintain a fresh active
layer of additive combustion byproducts on the surfaces in the
radiant zone (furnace) and convective zone (downstream of the
furnace). Although most of these additives operate in the gas phase
on combusting fuel vapor and particles, an induction period is
often observed before signs of the intended effects are seen;
implying that surface supported heterogeneous chemistry also plays
a major role. Interruption in additive treat results in a shut down
in surface supported activity, as the surface active layer is
quickly covered with deposit from untreated fuel. To avoid this
problem, additive suppliers need to store large amounts of additive
on site, and these amounts can be tank trailer volumes (2,500
gallons and above). Additive storage locations on plant sites are
usually above ground, semi-permanent, and permanent structures
constructed by the additive supplier, with the exact location
dictated by space in the proximity of the chosen fuel treatment
location.
[0004] The HMIS hazard labeling of chemicals ranks the hazard level
between 0 and 4, in order of decreasing safety. A chemical with a
HMIS label of 1 or below is usually considered safe because
exposure through aspiration is not dangerous. Anything above 1 may
be considered potentially hazardous through skin contact, ingestion
and aspiration and poses a storage and use safety risk requiring
special precautions by those in the immediate environment.
SUMMARY
[0005] Accordingly, it is an object of the present invention to
provide a safe combustion additive and a method for formulating a
safe combustion additive for use in utility and industrial furnaces
that addresses the foregoing concerns and needs. The present
invention not only addresses the requirements of HMIS standards,
but also goes further by recognizing that inhalation through
aspiration can be a significant health hazard in the real world
where chemicals such as fuel additives may be handled.
[0006] In one example, a combustion additive for use in utility and
industrial furnaces comprises a metal-containing catalyst. The
additive further comprises a ligand for complexing with the
catalyst, and a solvent for carrying the catalyst/ligand complex.
The vapor pressure of the additive is less than about
200.times.10.sup.-5 Torr at 100.degree. F. The catalyst may be
comprised of a plurality of metals. The catalyst may be comprised
of manganese. The catalyst may be comprised of a plurality of
metals selected from the group consisting of manganese, calcium,
magnesium, potassium, zinc and aluminum. The ligand may be selected
from the group consisting of fossil fuel derived carboxylates,
natural product derived carboxylates, genetically engineered
natural product derived carboxylates, and synthetic carboxylates
and mixtures thereof. The additive may have a HMIS health rating of
1 or 0. The vapor pressure of the additive may be less than about
70.times.10.sup.-5 Torr at 100.degree. F.
[0007] In a further alternative, the invention includes a method of
formulating a combustion additive for use in utility and industrial
furnaces. The method includes selecting a metal containing catalyst
for use in utility and industrial furnaces, complexing the metal
containing catalyst with a ligand, and adding a solvent to carry
the catalyst/ligand complex. The vapor pressure of the additive is
less than about 200.times.10.sup.-5 Torr at 100.degree. F. The
catalyst may be comprised of a plurality of metals. The catalyst
may be comprised of manganese. The catalyst may be comprised of a
plurality of metals selected from the group consisting of
manganese, calcium, magnesium, potassium, zinc and aluminum. The
ligand may be selected from the group consisting of fossil fuel
derived carboxylates, natural product derived carboxylates,
genetically engineered natural product derived carboxylates, and
synthetic carboxylates and mixtures thereof. The additive may have
a HMIS health rating of 1 or 0. The vapor pressure of the additive
may be less than about 70.times.10.sup.-5 Torr at 100.degree.
F.
DETAILED DESCRIPTION
[0008] Health hazards may result from the following: inhalation,
eye contact, skin contact, and ingestion of fuels and/or fuel
additives. Health hazards caused by eye contact, skin contact, and
inhalation can be prevented with warning signs on a container to
wear gloves and avoid getting the chemical near the eyes or mouth.
However, the "inhalation" hazard is more problematic in that by the
time one reads the label they may have already been exposed.
[0009] To inhale something, it has to be in a vapor state, or a
mist form. Therefore, the ability of an additive to convert to this
physical state must be minimized. An additive formulation where the
components exhibit a zero vapor pressure at ambient storage and
handling conditions can reasonably be assumed to be benign with
regard to passive inhalation by those handling it. Therefore,
designing additives to minimize this health hazard dictates that
first, the vapor pressure of all components in the formulation be
minimized in the package. Second, the additive concentrate must be
at a dilution level that lowers the HMIS health hazard rating of
each component to "1" or below.
[0010] This invention aspires to minimize health exposure to
additive formulations by means of the vapor vector. Most active
ingredients in fuel additives are either high molecular weight
compounds, or inorganics, or organometallics, all of which exhibit
such low vapor pressures that exposure through aspiration is
minimal. However, the fluidizing liquid matrix is likely to contain
organics with relatively high vapor pressures. Volatilization of
the additive active ingredients is facilitated by such low vapor
pressure organics. This invention addresses that problem by
providing a methodology to ensure that the additive fluidizing
matrix itself exhibits a low vapor pressure.
[0011] Volatility is the key feature influencing the HMIS hazard
ratings of metallic additives because of the potential danger of
intake through aspiration. This invention recognizes that the
volatility of such organometallic compounds is highly dependent on
the ligands stabilizing the metal. Therefore the most important
first step towards minimizing volatility of such organometallics is
to choose ligands which themselves are non volatile and have a HMIS
health hazard label of 1 or less. Such ligands include carboxylic
acids such as naphthenic, salicylic, phenolic, tall oil derived
fatty acids such as CENTURY 1164 (Arizona Chemical Co.), and other
plant and animal derived fatty acids and mixtures thereof. To
improve cold temperature properties, mixtures of carboxylic acids
with alkyl group branchings and unsaturation are preferred because
potential crystal lattice ordering with temperature lowering is
disrupted. Unsaturation in the ligand backbone is highly preferred
because of its role in laminar flame acceleration. Other ligands
can be chosen from appropriate organosulfonates and
organophosphonates.
[0012] This invention also recognizes that if solvents are desired
to complete the additive formulation, then these solvents may also
have a HMIS health hazard label of 1 or less. The use of the term
"solvents" herein includes generally carriers and fluidizers and
other compounds for carrying the catalyst/ligand described herein.
Such solvents can be found in low aromatic Group I and Group II
basestocks with a cSt of 4 at 100.degree. C. Examples of
appropriate solvents are: 1) GP II 100SN, 98 VI at about 4.0 cSt at
100.degree. C. from Motiva, and b) GP I 150SN, 88 VI with 4.5 cSt
at 100.degree. C. from ExxonMobil. Other solvents of similar
characteristics and HMIS hazard label of 1 and below may also be
used.
[0013] Single metals that may be derivatized according to this
recipe to be used in utility power plants as combustion catalysts
are Ca, Cr, Mn, Fe, Co, Cu (only with coal), Sr, Y, Ru, Rh, Pd, La,
Re, Os, Ir, Pt, and Ce. The respective carboxylates can be made
from the appropriate metal starting material (oxide, hydroxide,
etc) and carboxylic acid and a solvent as defined above.
[0014] For a wider functional scope, multimetallics may be
necessary. In such a case, a first co-catalyst may be necessary.
For example, if additional slag modification is necessary, a
magnesium carboxylate co-catalyst may be prepared according to the
recipe above and blended with a single metal combustion catalyst as
described above. The ratio of the catalyst/co-catalyst may span the
range of 1/0.5 through 1/6. If the additive formulation is to be
used in a vanadium containing fuel oil then the amount of the Mg
co-catalyst should be about stoichiometric with the concentration
of the vanadium in the fuel. When the combustion catalyst is Mn
based, then the final formulation should be a concentrate designed
to deliver between about 10 to 50 ppm Mn metal or about 20 to 30
ppm Mn metal. Since Mn, Pd, Pt and Cu based combustion catalysts
are believed to be among the most efficient carbon burnout
catalysts, the treat rates using metal carboxylate combustion
catalysts such as those made from Ca, Cr, Fe, Co, Sr, Y, Ru, Rh,
La, Re, Os, Ir, and Ce would likely have to be higher and may span
the range of about 10-100 ppm, or alternatively, about 20-80 ppm
metal.
[0015] In instances where the carbon containing combustion
byproducts tend to form intractable sticky solids of large particle
size, then a second co-catalyst derived from the alkali metal group
(Li, Na, K, etc) may be necessary. Because of their low ionization
energies, alkali metals are known to ionize very quickly in the
flame and glom onto young soot as it forms. Being charged, they
inhibit agglomeration of the soot particles thus maintaining the
highest possible soot surface area to oxidation. Since this second
co-catalyst's effectiveness is proportional to the number of atoms
that ionize, rather higher concentrations may be necessary to
achieve the desired goal. Therefore the alkali metal carboxylate in
the formulation concentrate should be designed to deliver between
about 10-500 ppm, or alternatively, about 20-100 ppm metal to the
fuel.
[0016] Table 1 presents examples of additive formulations arrived
at by following the concepts of this invention. In this set of
examples, the metal catalyst that would under many circumstances
push the HMIS health hazard rating of the respective additive
formulation is manganese. At equal concentrations, the manganese
from MMT would have a much higher risk to inhalation than that from
manganese carboxylate, based on the fact that the former has a
vapor pressure of 0.05 mm Hg at 20.degree. C. while the latter
exhibits a vapor pressure of 0.00 mm Hg at the same temperature. On
this basis alone, use of Mn-carboxylate as the combustion catalyst
in the additive formulations should yield a HMIS health hazard
rating of less than "2" by inhalation, provided the carboxylic acid
ligands and the solvents used are rated below a "2" as described
elsewhere in this text.
TABLE-US-00001 TABLE 1 Stationary Burner Additive Formulations
Designed to Minimize Exposure Through Inhalation. Metal Ratios
Examples Mn Ca Mg K Zn Al Wt % Mn 1 1 (MMT) 1.26 2 1 (MMT) 9 (Lig)
1.26 3 1 (MMT) 7 (Lig) 2 (Lig) 1.26 4 1 (MMT) 6 (Lig) 1.26 5 1
(MMT) 3 (Lig) 1 (Lig) 1 (Lig) 1.26 6 1 (MMT) 4 (Lig) 1 (Lig) 1.26 7
1 (MMT) 1 (Lig) 4 (Lig) 1.26 8 1 (MMT)/1 (Lig) 3 (Lig) 1 (Lig) 2.57
9 1 (MMT)/1 (Lig) 2.57 10 1 (MMT)/1 (Lig) 1 (Lig) 2.57 11 1 (MMT)/1
(Lig) 2 (Lig) 3.78 12 1 (MMT)/2 (Lig) 1 (Lig) 1 (Lig) 3 (Lig) 3.78
13 1 (MMT)/2 (Lig) 2 (Lig) 1 (Lig) 3 (Lig) 3.78 14 1 (Lig) 0.2
(Lig) 0.2 (Lig) 0.5 (Lig) 12
[0017] In Table 1, the metal ratios have units of weight percent
(wt %). The main combustion catalyst is manganese either as
methylcyclopentadienyl manganese tricarbonyl (MMT.RTM.) or a
manganese carboxylate. "Lig" refers to "ligand" which may be
carboxylic acid derived, acetylacetonate, chelating olefins,
aromatics such as cyclopentadiene, and substituted
cyclopentadienes, and other stabilizing ligands with a HMIS health
hazard rating of "2" and below that promote oil solubility of the
manganese compound. The co-catalysts are calcium (Ca) and potassium
(K) derived organometallic compounds. Magnesium (Mg), zinc (Zn),
and aluminum (Al) are slag and deposit modifiers. In general,
magnesium and zinc are preferred for acidic slags and deposits
(fuel oil combustion deposits), whereas zinc and aluminum are ideal
for modifying basic slags (coal combustion deposits). Since
manganese would be the metal with the highest HMIS rating in Table
1, the design of this invention focuses primarily on controlling
the possible health hazard by inhalation of this metal. Pure
commercial grade MMT (24.7% Mn) has a HMIS health hazard rating of
"3". On dilution to 5% MMT (1.26% Mn) the HMIS rating falls to a
safe level of "1", based on the dilution factor alone. That is
where the "1.26" in the column titled "Wt % Mn" in the additive
formulations comes from. Therefore, so long as MMT is a component
of the package, this Mn concentration cannot be exceeded.
[0018] In order to increase the concentration of Mn in the
formulations, a second source of Mn with a lower HMIS health hazard
rating is used as a top treat. A typical example is a manganese
carboxylate with a vapor pressure of 0.00 mm Hg at 20.degree. C.,
with the logic here being, if it is not in the vapor phase at the
plant storage site it cannot be inhaled.
[0019] Examples 1 to 7 are suitable additive formulations for use
in fuel oil for improvement in combustion, opacity, slag/deposit,
and minimization of both hot and cold corrosion.
[0020] Examples 8 to 14 are aimed at coal burning utility and other
stationary burner set ups, with the same benefits as listed
above.
[0021] The vapor pressures of commercially available additive
fluidizer components were studied and from that study "superior"
fluids were identified with vapor pressures of not more than
1.5.times.10.sup.-4 Torr at 68.degree. F., and less than
70.times.10.sup.-5 Torr at 100.degree. F. (see Table 2). These are
the temperature conditions likely to be experienced during
transportation, storage, and handling at end user sites. Similarly
"good" fluids were identified with vapor pressures less than
5.0.times.10.sup.-4 Torr at 68.degree. F. and less than
200.times.10.sup.-5 Torr at 100.degree. F. (Table 3). The tabulated
lists are but examples of suitable fluids. Of more importance are
the respective vapor pressure ranges that can be used as a guide to
select suitable fluidizing components.
TABLE-US-00002 TABLE 2 Temperatures Tested for Vapor Pressures
Superior Fluids (.degree. F.) (in Torr .times. 10.sup.-5) Supplier
Oil Name Group 68 100 Petro Canada P5300 II 0.14 1.00 Petro Canada
VHV18 III 0.21 1.10 Motiva Star 12 II 0.07 3.70 Petro Canada VHVI4
III 0.95 5.40 Petro Canada VHVI6 III 1.70 9.00 Petro Canada P1003
(II+) 6.60 32.00 Petro Canada P2305 II 7.00 35.00 Petro Canada
P1020 II 9.00 43.00 Petro Canada P1017 II 15.00 70.00
TABLE-US-00003 TABLE 3 Temperatures Tested for Vapor Pressures Good
Fluids (.degree. F.) (in Torr .times. 10.sup.-5) Supplier Oil Name
Group 68 100 SK Yubase 4 III 18.00 75.00 Petro Canada P1810 II
23.00 90.00 Motiva Star 5 II 40.00 170.00 Petro Canada EVHVI24 III
47.00 200.00 Petro Canada PL65 II 47.00 200.00
[0022] With the critical components thus defined, these additives
may be formulated according to known techniques, with appropriate
solvents and ancillary components (cold flow improvers, detergents,
antistatic agents, etc) as need be. The ratios indicated may be
changed to meet changing fuel compositions and
burner/furnace/boiler operation parameters. This invention
recognizes such differences and covers them.
[0023] Other metals that are combustion catalyst and may substitute
in for Mn are Ca, Sr, Cr, Fe, Cu, Ru, Rh, Pd, La, Ir, Pt, and Ce.
To determine safe concentrations, the same logic would apply with
regard to vapor pressure and dilution.
[0024] Safer additive formulations made according to the recipe
outlined above would be added to the fuel, combustion air,
secondary air, overfire air, combustion charge, or flue gas in oil
and coal burning furnaces and boiler systems to control emissions
such as particulate and NO.sub.x; to minimize corrosion in the
waterwall fuel rich regions near staged low-NO.sub.x burners, and
to minimize low temperature corrosion in the flue gas by inhibiting
oxidation of SO.sub.2 to corrosive SO.sub.3.
[0025] The invention is further directed to packaged products that
contain the additive described herein. Briefly, the additive may be
stored in packages prior to use--the packages including, but not
limited to, drums, totes, barrels, tanks, etc. These packages would
include indicia or labeling thereon, or otherwise near or in close
proximity thereto, that indicates an HMIS health rating of one or
zero. The unprecedented benefits of such labeling or indicia on a
package are significant. Any person on or near a utility work site
will know that the contents of the package are relatively safe and
not volatile.
[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
* * * * *