CA2120241A1 - Emulsification system for light fuel oil emulsions - Google Patents

Abstract

The present invention relates to a fuel oil composition useful for controlling the emission of nitrogen oxides from turbines. The composition comprises an emulsion formed from water and a light fuel oil, the emulsion further comprising an emulsification system which comprises an alkanolamide; a phenolic surfactant; and, optionally, a difunctional block polymer terminating in a primary hydroxyl group.

Description

WOg3/07238 PCT/US92/OXO8~ ~

212~2~1 DESCRIPTION
:: ' EMULSIFICA~ION SYS~M FOR LIGHT ~UEL OTL E~ULSIONS
, ~:
Technical Field : . The present in~ention relates to a fuel oil composition which comprisPs an emulsion of water and a light fuel oil with an emu~sification system comprising ~~
an alkanolamide, a phenoIic surfactant, and, optionally, a difunctional bl~ock polymer. By forming the described :~
emulsion, impro~ements are obtained in the combustion ``
efficiency ~of the: fuel oil in order to reduce the emissions ~ of nitrogen oxides (NOX, where x i5 an ;integer,: gener~ally 1 or 2),~ and visible emissions ;~
(particulatesj whi~h lead to plume opacity) to the atmosphere. : ~ - :
., ~
Stationary and~ ~mobile combustion units have been identified as sources of nitrogen oxides emissions to the atmosphere. : :Electric power generating utilities, in ; fact, ha~e ~ been identified as a prime contributor of NOX emissions. :Nitrogen oxides can fo~m from the combustion of organic and inorganic nitrogen compounds in ~: ~ fuel ~nd, at higher temperatures, from thermal oxidation : of nitrogen in ~combustion air. Combustion or gas turbines are considered to be even more pr~ne to generate NOX becau~e of the "favorable" high temperature and W093/n7238 PCT/US92/~8083 212~241 .

pressure conditions existing therein, as well as their more oxidative operating conditions.

Nitrogen oxides are troublesome pollutants and comprise a maj or irritant in smog. It is further S believed that nitrogen oxides can cause or enhance the process known ~s photochemicaI smog formation through a series of: reactions ;~in the presence of sunlight and hydrocarbons. Moreover, nitrogen oxides are a significant contributor to acid rain and have been i~plicated in ;the ~undesirab1e warming of the atmosphere through what is known as the "greenhouse effect" and in the depletion of the ozone layer. In addition, gas turbines o~ten ~emit ~a visible~ plume which is highly undesirable since }t causes concern am~ng the general ;15 population in areas surrounding the facility.

In the ~past~, ; direct water injection into the combustlon:: chambér;~of ~ a stationary electric power enerating~ sour~e has been utilized to reduce NOX by QWering the peak ~flame temperatures. This can be 20:::e~ffective at achi~ving substantial NO~ reductions. The use ~of direct: water~ injection, though, has several disadvantages,~ including water:fe~d rates:which can reach 1.;5 ~x ~fue} rates or~higher, high:~installa ion costs, and high~ energy:loss~due~to cooling. Furthermore, the direct : 25 addition ~of water may involve thermal shock which can cause thermal ~ontraction and cracking of the liners in the:combustion;bo~

The emulsification~ of heavy (i.e., residual or ~6) ~:~ fusl: oils with: water prior to combustion has been suggested to induce a ~Imicro explosion" to impro~e :

'~
~ .

~'~9~/0723X PCT/US92/0808~
212~2~1 combustion efficiency. Emulsification systems for heavy fuel oils, though, have been found to be unsuccessful at emulsifying lighter grades of fuel oil. It is believed this is because the heavy fuel oils comprise a high viscosity grade of oil rich in polynuclear aromatic and long chain polymeric hydrocarbons. The high aromatic content and, therefore, polar nature of the heavy fuel oils make them amenable to emulsification by a large variety of conventional polar surfactants.
, .
Con~rariwise, lighter fuel oils such as #1 oil, #2 oil, or #4 oil comprise much lower boiling fractions than the heavy fuel oils. Light fuel oils contain very little to almost no aromatic compounds and consist of rel~tively ~, low molecular ~ weight aliphatic and naphthenic hydrocarbons. It is well documented that many surfactants are not readily soluble in naphthenic/
aliphatic hydrocarbons~ such~ as kero5ene. Because of this, ~ such hydrocarbons are not readily emulsified by many classes o~ surfactants, such as nonylphenol 20 ~e~hox~ylates or~ ethoxylated sugars, which have been found t~be~ of limited effecti~eness when used alone and which have~ little ~or ~no ~solubility in aliphat~ic hydrocarbons 5UC~ ~ as ~erosene ; (#l fuel oil). Because of this dichotomy in chemical propertias, different emulsifier

2~5 ;chemistries ~ are~ needed when emulsions are formed using lighter fuel oils.

Although emulsifiers for water and fuel oil emulsions h~ave,; in ~he past,~ been described, such as ethoxylat~d ~ nonylphenols and the like, disclosed by Puttock and ,~; 30 Somer~ille in U.S. Patent 5,000,757, sNitable systems for ~maintaining a superior water and light fuel oil emulsion have not been adequately disclosed.

W093/0723~ PCT/~S92/0808~
21202lil What is desired, therefore, is an emulsification system for water and light fuel oil emulsions which, when combusted, may absorb heat required to rapidly flash the water to steam which to reduce peak flame temperature and thus control thermal NOX formation; and also lead to improved atomiæation and thereby improve fuel ~ombustion.

DisclQsure of Invention The present invention relates to a water and fuel oil : emulsion for reducing nitrogen oxides emissions and impro~ing combustion efficiency in a stationary, electric powered generating source, especially a gas turbine (the erm "gas turbine" will be considered to be interchange-~: able with the term "combustion turbine" for the purposes ~: : of this disclosure~. In particular, this invention .
relates to a stable water and light fuel ~il emulsion.
The subject emulsi~n can be either a water-in-fuel oil or a fuel oil-in-water emulsion, although water-in-fuel oil emulsions are generally preferred for most applications and:can be used:as the fuel for a gas turbine.

20 : ~ The oil phase~ in the inventive emulsions comprises a light crude naphtha~fuel oil by which is meant a fuel oil having little or no aromatic compounds and consisting essentially of relatively low molecular weight aliphatic and naphthenic hydroca~rbons. In the refining arts, light crude naphtha re~ers specifically to the first liquid distillation fraction, which has a boiling range of about : 90F to about 17~F. This is distinguished from heavy . : crude naphtha, which is the second distilla~ion fraction, with a boiling range of about 325F to about 425F.
"Naphthenic'l is an industrial erm which refers to fully saturated cyclic hydrocarbons having the general for~ula CnH2n. "Aliphatic" is an industr~al term which W093/07238 P~T/US92/08083 21202~1 refers to fully saturated linear hydrocarbons having the ge~eral formula CnH2n~2 Suitable fuels are those having a viscosity o* about 5 SSF to about 125 SSF, preferably about 38 SSF to about : 5 100 SSF, at 100F and a specific gravity of about 0.80 to about 0.95 at 77-F. Such fuels include fuels conventionally known ~as diesel fuel, distillate fuel, #2 oil, or #4 oil, ~as: defined by the American Society of ~ Testing and Measurement (ASTM) standard specification for : : lO fuel oi~ls (designation : D 396-86). Especially preferred are distillate~ fuels.~ ~Included among these are kerosene : ~(or ASTM ~grade~:;no.~ l fuel oil) and jet fuels, both commercial and military, commonly referred to as ~et-A, p-~and~JP-5 5~ The: ~subject emul~sions advantageously comprise water-in-~fuel oil;~emulsions~having~ up~ to about 95% water by weight.~ The ~emulsions~;which~have the most practical significance~ in~combustion~applications are those having about:~ 5% ~to ab~out~::5~0%~water~and are~preferably about 10%
20~ to;~about~ 3~5%~ :water-in-fuel oil:by weight. In addition, it~ is~ recognlzed~:that:~as the~amount of:the discontinuous phase~ (i.e~ th~e;~ water~in:a water-in-fuel oil emulsion) increases,~the p~ssibility of :inversion arises. For instance,~: in~ an~emu}sion ~ontaining up~ to about 65%
2~5~:water-in-fuel :~:;oil~ nversion ;will:cause the emulsion to ~;: : :become :a ~fuel oil-in-wa~er emulsi~n comprising about 35%
: of the:oil phas~e.

Although ;~demineralized water;~is not re~uired for successful control~ of nitrogen oxides and opacity, the 30~u5e:~ of~ de~mineralized~ water in:~ the emulsion formed according to; the~process of this:invention is preferred in order: t~ avoid:the deposit:of-minerals from the water ~: :

W093/0723X PCT/~S92/080X~

~ 1 ~ 0 ~ 6-on the blades and other internal surfaces of the gas turbine. In this way, turbine life is extended and maintenance and outage time significantly reduced.

The inventive emulsions are prepared~such that the discontinuous phase preferably has a p~rticle size wherein at least about 70% of the droplets are below about 5 microns Sauter mean diameter. More preferably, at least ~about 85%, and most preferably~at least about 90%, of the droplets~ are below about 5 microns Sauter mean diameter for~emulsion stability.

Emulsion stability is~ largely related~ to droplet size. The primary driving force for emulsion separation is the large~energy~associàted with pla~ing oil molecules in~ close proximity~to ~water molecules in the form of l5~ small~ ~droplets.~ Emulsion~breakdown is controlled by how quickly ~droplets~ coalesce~. ~ Emulsion stability can be enhanced by the~ use~of surfactants and the like, whîch act~ as~ emulsifiers~ or~ emulsion stabilizers. These génerally ~work ~by~fo ~ ing repulsive layPrs between 20~ droplets~prohibiting coa~lescence.

The~ gravltat~onal~ driving force for phase separation is~ much ~more ~;prominent for~large droplats, so emulsions c~ntaining ~ arge~droplets~separate~most xapidly. Smaller droplets` also ~ settle,~ but can be less prone to 25 ~coalescence, wh~ich~is~the cause of creaming. If droplets are sufficiently ~small, the force of gra~ity acting on ;the ~droplet~is~small compared to~thermal~fluctuations or subtle mechanical ~agitation forces. In this case the emul~ion can become~stable almost indefinitely, although

3~0 ~given a long enough~ period of time or a combination of thermal fluctuations~ these ~emulsions will eventually separate.

.

~: :

W093/0723X PCT/US92/0~0~
21202~

":
Although it is possible to emulsify the water and ~-light fuel oil and inj ect directly into the combustion can or other combustion zone, generally it is required that water and light fuel oil emulsi~ns exhibit a high degree of stability. For instance, since gas turbines ~re often operated as "peaking" units which do not operate regularly, an emulsified fuel may sit stagnant for extended periods or with only mild recirculation in the fuel line. To avoid separation of the emulsion, which can cause slugs~of water to be injected through the burner nozzle leading to combustion problems and possible engine damage, an emulsification~system must be employed to maintain the emulsion.
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15~ ~Advantageously, the~ emulsification system utilized comprises about 25~ to about 85~ by weight of an amide, especlally~ an ~alkanol~amide~or n-substituted alkyl amine;
about~5~to about~25%~by~weight of a phenolic surfactant;
and~about 0% to ~about 40% by~weight o~ a difunctional 20~ block; ~polymer terminating in a primary hydroxyl grou~
More~ preferably,~ the~ amide comprises about 45% to about 65%~ ~of the emulsification~system: the phenolic surfactant about~5% to about~15%;~and the difunctional block polymer about 30% to about~40% of the emulsification system.

25~ Suitable~n-substituted~alkyl amines and alkanolamides which can function~ to stabilize the emulsion of the present invention~ are those formed by the ~ondensation of, respectively, an alkyl amine and an organic acid or a ;hy~roxyalkyl ~amine ~and ~an organic acid, which is 30;~preferably of a ~length normally associated with fatty acids. They can~be mono-, di-, or triethanolamines and , ~
include any one~ or more of the following: oleic diethanolamide, cocamide diethanolamine (DEA), lauramide DEA, polyoxyethylene (PoEj cocamide, cocamide monoethanolamine (MEA), POE lauramide DEA, oleamide DEA, :~
, W093/0723~ PCT/US92/0~08~
2121)~1 linoleamide DEA, stearamide MEA, and oleic triethanolamine, as well as mixtures thereof. Such alkanolamides are commercially available, incll~ding those under trade names such as Clindrol 100-0, from Clintwood Chemical Company of Chicago, Illinois; Schercomid ODA, from Scher Chemicals, Inc. of Clifton, New Jersey;
Schercomid SO-A, also from Scher Chemicals, Inc.; and Mazamide0, and the Mazamide series from PPG-Mazer Products Corp. of Gurnee, Illinois.

The phenolic surfactant is preferably an ethoxylated alkyl phenol ~such as an ethoxylated nonylphenol or octylphenol, especially ethylene oxide nonylphenol which is available commercially under the tradename Triton N
from Union Carbide Corporation of Danbury, Connecticut and ~I;gepal CO ~from Rhone-Poulenc Company of Wilmington, Delaware.
.
The~block polymer which is an optional element of the emulsification system of the present invention ; advantageously comprises a nonionic, difunctional block 20~polymer~ which terminates in a~ primary hydroxyl group and has~ a molecùlar wéight ranging from about 1,000 to above about; 15,000. Such polymers are generally considered to bè~polyoxyalkylene ~derivatives o~ propylene glycol and are commercially ava~ilable ~under the tradename Pluronic 25 ~from~BASF-Wyandotte ~Company~ of Wyandotte, New Jersey.
Preferred among these polymers are propylene oxide/ethylene~ oxide block polymers commercially ~available as Pluronic 17Rl.
,:
In addition t~ ~ the noted components, the emulsification system of the present in~ention may further comprise up t~ about 30% and preferably about 10 t~ about 25% of a light crude naphtha fuel oil, most .

W093/07238 PCT~US92/080~
212U2l11 g preferably the light crude naphtha fuel oil which : comprises the continuous phase of the inventive emulsion. It has been found that inclusion of the fuel oil in the emulsification system can in some cases increase emulsion stability of the emulsion itself. In addition, other components such as salts of alkylated ~: sulfates or s~lfonates such as sodium lauryl iulfate and alkanolamine sulfonates :may also be included in the : inventive~emulsification system.

The use of he noted~emulsification system provides 10: chemi~cal emulsification,~ which: is dependent on hydro-phylic-lipophylic balance: (HLB), as well as on the chemical nature~ of the ::emulsifier. The HLB of an emuls~ifier is~ an~expression of the balancie of the size and ~strength of the hydrophylic and:ths lipophylic groups 15~:~ of~ the composition~. The~HLB system, which was developed as~ a~ :guide to emulsifiers by ICI Americas, Inc. of Wi~lmingti~n, Delaware~ can-~be;:determineid in a number of ways, ;most conveniently: for~ the purposes of this invention ~ by ~ ~th~e~ solubility or :dispersability 20~ characteristics~of~ the~ emulsifier in water, from no : dispersability~(HLB range:of 1-4);to clear solution (HLB
range~;of~13:~or qreater).~

The ~:~emulsi:~iers:::useful in the present invention ~ :should: most ~preférably~have an HLB of:8 or less, meaning :~: :25~:that : after ~igorous: :agitation~ they form a milky ;~ d~ispersion in water :~(HLB range of 6-8), poor dispersion in water ~HLB range~o~ 4-6), or show no dispersability in water~HLB r~nge ~of~less than~4).~ Although the precise , e~planation is unknown,: it is;bel~eved that the in~enti~e 30 ~emulsification s~Gtem ~provides superior emulsification ;because it~ comprises~ a~ plurality of components of different :HLB values. Desirably,~ the emulsi*ication . .

W093/0723~ PCT/US92/~808~
21~U2~1 -10- ~;",,~

system has a combined HLB of at least about 4.o, more preferably about 5.1 to about 7.0 to achieve this superior emulsification.

For instance, an emulsification system which comprises 70% oleic diethanolamide (average HLB 6), 10%
ethylene oxide nonylphenol (average HLB 13), and 20% #2 ~uel oil has a combined HLB of about 5.5 (70% x 6 plus 10% x 13). An emulsification system which comprises 50%
: oleic diethanolamide,~ 15% ethylene oxide nonylphenol and 35% of a ~propylene oxide/ethylene oxide block polymer : (~verage HLB 2.5)~ has a:combined HLB of about 5.8 (50% x .
6 plus 15% x 13 plus 35% x 2.5). Such emulsification systems ~would provide superior emulsification as compared with an ~emulsifier comprising 80% oleic diethanolamine ;15 ~and 20%~#2 fuel oil,~which has an HLB of about 4.8 ~80% x Desiràbly, :the::~emulsification system of the present invention:: should::~be~present at a level which will ensure e~ective emulsifioAtion. Preferably, the emulsification :20~system: is~present~ at a level of at least about 0.05% by weight;;~of ~the emulsi~on:~to do:so. Although there is no : :true; upper limit~`to~: t~e amount :of:the emulsi~ication system which is~:present, with higher levels leading to greater~emulsification~ and for longer pexiods, there is : 25`~ generally:~ no need`~ for more ~than about 5.0~ by weight, nor, in fact, more than about 3.0% by weight.
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It is also~:.possible to utilize ~physical emulsion stabiIizer in combination with the em~lsification system no~ed :above to maximize the stability o~ the emulsion ~: 30 achieYed in the process of the present invention. ~se of~ ~ physical stabilizers also provides economic benefits dus to their relativ~ly low cost. Although not wishing to be W093/~7238 PCT/US92/0808~
21202~ ~

bound by any theory, it is believed that physical stabilizers increase emulsion stability by increasing the viscosity of immiscible phases such that separation of the oil/water interface is retarded. Exemplary of : 5 suitable physical : stabilizers are waxes, cellulose products, and gums such as whalen gum and xanthan gum.

When utilizing both:; the emulsification system and ::~ physicaI emulsion stabilizers, the physical stabilizer is : present in an amount of about 0.05~ to about 5% by weight of. the combination~ of :chemical emulsifier and the p~ysical stabilizer. ;~ The~ resulting combination :emulsifier/stabilizer ~ can~then be used at the same levels :noted~a~ove for;the~se~of~the~emulsification system.

The~:emulsification:~provided~: must. be sufficient to ; 15~`msintain ~the :~emulsion ~to ~a greater extent than if the :emulsi:f~ication :system~ was~not~present and to as great an ex~ent ~ as ~possibl0.~ The~actual level of emulsif:ication ;will~ va~y~ ;depending~upon the percentage of oil and water ~ in~ the~ emuls~on~ and~ the~ particular fuel oil utilized.
: ~ 20 ~For~ exampl`e~when~;;:;the~icontinuous~phase~is~#2 oil, it is h~i;ghly~ desired~that~no~ more~ than about 0~1% water se~paration~ be~:present~: in the~ emulsion, ~and t~at the emulsion~ is~mainta~îned~;that:way at~ambient~conditions for t~; least~ about~:two;hours. ~ ~ ient conditions/ ~hat is, 25~ thé~conditions~ o~ which the~emulsian~is expected to be exposed, include ~the temperature in the gas turbine fuel ; feed ~:~lines. S~uch~;temperatures can be up to about 65C, ometimes ~up ~to~ about~ 90C and~ even~as high as about lO~O~-C;for~short~periods of~;time~

30~ The: emulsion: used~ in the process~ o~ the present invention. aan~ be ~formed using~ a suitable ~mechani~al emuisifying apparatus~ which would be` familiar to the : : :: :: .

:~ : `:

W093/0723~ PCT/US92/08~8~ ~
2120~1 .
skilled artisan. Advantageously, the apparatus is an in-line emulsifying device for most efficiency. The emulsion is formed by feeding both the water and the fuel oil in the desired proportions to the emulsifying apparatus, and emulsif ication system can either be admixed or dispersed into one or both of the components before emulsification or can be added to the emulsion after it is formed.

Preferably, the em~lsification system is present at the time of emulsifying the water and fuel oil. ~ost ad~antageously,~ the :emulsification system is provided in the water phase, depending on its H~B. It has been found that the emulsions noted above with the chemical ;; emulsifiers can be stabilized at up to about 95 water-in-fuel :oil or up to about 35% fuel oil-in-water.
: :In fact,~ with mild agitation;, such~as rPcirculation, it s believed that the emulsions can stay in suspension indefinitely.

S~rprislngly,~ the~ emulslon can then be introduced 20~ into the~ combus~lon~ ~can of the gas turbine ~hrough the fuel~feed lines: and~: burner:nozzles conventionally used with~such~ combust~ion~ apparatus. There is no need for modiflcation ~of the~ gas ~turbine~ fuel feed lines or combusti~n~ :can :to ~accommodate the emulsion used i~ the :process of~his invent;ion.~

Although no~ wishing to b~ bound by any theory, it is believed that the use~ of an emulsion provides ~triking advan~ages over separate water injection systems because ~ the water is being~ provided internal to the flame. By :~ 3~ ~doing so, l~ss water is required to ~chie~e superior ~ results,~ -which ~ reduces the deleterious effect~ of :

W093/0723~ PCT/US92/080X~
~-1202lll directly introducing large amounts of water to the combustion zone of the gas turbine.

Because of the advantages of introducing water internal to the flame, utilization of the inventîve process results in a reduced use of demineralized water .: (since the emulsion contains less than the at least 1:1 : ratio of water to fuel oiI used when water is injected ;: directly into the combustion can), and leads to l~ss :
thermal stress which reduces maintenance cost and outage :~ : 10~ ~time.

When the emulsified fuel is introduced into the co~bustion zone, the heat of vaporization from the burning ;fuel ;causes:~ the~; emulsified water droplets to become steam, :which :creates a secondary atomization.
This~secondary atomization~ improves ~combustion and incréases:~ the~gas volume.~ In addition, the heat re~uired to ~change the water to steam is believed to reduce the flamè~ temperature~of the combustion~which h~lps to reduce for~tion~of~nitragen oxides.

Additlonally~, ~use~of the~water/fuel;oil emulsion can result~ in::~:substantial ~:elimination~ of the need for an expensive, ~ independent ~smoke~ :suppressant additive.
Typi;cal:ly/~such~ addit~ives are heavy metal based products which~ can ~form :~deposits on the turb;ine blades, reducing efficiency and~ inGreasing maintenance costs. By the use of emulsions in~ the process of this invention, a 90% or greater~ reduction ~ in: smoke suppressant~additive use has been~achieved, which~;increases:the blade life due to reduced deposits~ and~ reates less wear on the turbine 30 :~blade coatings.: m ese~advantages~all lead t~ significant ~avings m operaeing and maintenance cost8.

~ ~ ~ ' '"
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WOs3/07238 PCT/US92/0808~

2 ~ 2 0 2 !11 -14-Furthermore, when compared to a separate water injection system, the use of the pro~ess of this invention leads to improved engine fuel system integrity;
the engine burns cooler, which, as noted, leads to less thermal stress; it is believed that the gas turbine can assume a higher load capacity; and compliance with environmental regulations is more easily obtainable.

;' In addition to its use as the sole fuel for a gas turbine, the emulsion of the present invention can also ~be used in a gas turbine which primarily fires natural gas,~ such as~is~ taught~ by Brown and Sprague in U.S.
Patent Application having Serial No. 07/751,170, entitled "Reducing Nitrogen 'Oxides Emissions by Dual Fuel Firing of ~a Turbine",~ ~filed~August 28, 1991, the disclosure of 15~which~ is incorporated~heréin by~reference. By the use of a~ manifold which~ permits~ the dùal injection of both natural gas~and the~inventive emulsion, it has been found th~t~ the ~nitrogen~ oxides content of the effluent can be substantially reduced~ when compared wlth the effluent 20~ ~when~natural; g'as is~ ired alone. Although not fully u*derstood, ~it~ is'~ believed ;that; the addition of the emulsion permits ~firing at a lower flame temperature due to the~water~;introdu'ction without the~disadvantages of direce~water inie-tion~into the combust~ion can.

5~ The~following examples further illustrate and explain the invention bu~ are not considered limiting.

Example I

Em~lsions ~of ~water in #2 fuel oil at water contents of~ 16.7%, 28.6%,` 33.3%, and 41.2% by weight, respectiuely, ar ~prepared by mixing the fu~l oil and water for five minutese~ When an emulsifier is present as . .
~ ' noted below, it is used at a level of 0.1% for the 16.7~
:.
.

:

W093/0723X PCT/US~2/0~B~
21 2D2~l emulsion (Emulsion #1) and 0.2% for the remaining emulsions (Emulsions #2, #3, and #4, respectively). The mixture is then put in a manual Chase-Logeman brand hand homogenizer. The homogenizer is set at 1 1/2 turns open and homogenization conducted for sufficient time to pump 100 milliliters Sml) of liquid into a receiving flask.

Four samples of the emulsions are prepared; a first with no emulsifter to be used as a blank; a second with an emulsifier comprising 80% oleic diethanolamine and 20%
:~ 10 #2 :fuel: oil ~emulsifier 1) to be used as a control; a : hird~ with an: emulsifier compri~ing 70% oleic diethanolamine, 10% ethylene oxide nonylphenol, and 20%
#2 *uel oil (emulsifier 2); and a fourth with an emulsifier com~rising 50% oleic diethanolamine, 15%
ethylene oxide ~nonylphenol, and 35% of a propylene oxide/ethylene oxide block polymer commercially available as~PLURONIC 17Rl (~e~ulsifier 3).

After homogenization, ~60 milliliters (mls) of each : sample::is placed~into:a beaker, to which is added 60 mls 2~0~ of #2 ~fuel oil.~ The resulting mixture is then mixed for ten~: mlnutes. A::sample of each mixture is then placed in a 100 :ml:centrifuge:tube and~subjected to centrifugation far ;15 minutes :~at ~2500 revolutions per minute (rpm).
:: ~
Stability~ is determined by the amount of free water on the~bottom~ of the:centrifuge tubè after centrifugation, : and the amsunt of emulsification in ~he top fuel oil : layer (distinguished by a darker and creamy appearance) : or the amoun~ of emulsified water layer ~distinguished as ;: : : a thick, white int~rmediate layer~.

-:: 3Q It is found that emulsifier 1 lead~ to an oil phase ~similar to the blank and a water phase comprising a large, white, creamy layer, whereas emulsifiers 2 and 3 W093t07238 PCT/US92/~808~
212132~1 result in a large, cloudy layer in the oil phase and a water phase having a volume smaller to or similar to that of emulsifier 1. It is believed the cloudy oil layer of emulsifiers 2 and 3 indicates that water remains 5 stabilized within the oil after centrifugation in the form of a water-in-oil emulsion. In addition, : emulsifiers 2 and 3 give better oil phase stability compared to the blank, whereas emulsifier 1 gives an oil ::
phase stability similar to the blank. ~
~: ~ .. , .
: ExamPle II
~: .
An emulsion comprising 33% water in #4 fuel oil having : a~:specific~ gravity :of 0.885 at 77F and~ a ; viscosity of 6 S:SF~at:122~F was formed according to the procedure detailed~in~Example l and divided into a blank 15~and~three samples~usin~g:0.2%~of emulsifiers l, 2, and 3, respectively. The:::stability of:the emulsions is tested by ~ the~:centrifugatlon~ method~ described above and the ~:
results~set:out~in~;Tabl~e l.

TABL~

20~ Free~ White* Other Total ~.
Emulsion~ Observations Emulsion Blank : :~: 0.1~ :27 separation 27%
: apparent :
Emulsifier 1 0.50 75 white clear oil 75%
25~ : phase Emulsifier 2 0.15 :::31 wh te 69% cloudy 100~
: `:: : oil phase*`* ::
Emulsifier 3 0.15 ~: 35~white 65~ cloudy: 10Q%
: oil pha e ~ 30 * oil in water emulsion : ** water in oil emulsion, generally considered more : desirable for ~inventive application :

W093/~7238 PCT/US92/0808~
2~202~11 Emulsifier l gave the largest volume (75%) of an emulsified water Iayer and higher, undesirable free water. The cloudiness in the oil phase observed with emulsifiers 2 and 3 is believed to be highly stable microemulsion droplets.

ExamPle III

~ An emulsion :comprising 43.2% water in #2 fuel oil is : ~ ~formed and divided into two:samples, one comprising 0.2%
of ~ emulsifier ~ and the~ second comprising 0.2% of :10 em~lsifier 3.~ The~ emulsion~ is ~ormed~using an Emulsa brand in-line èmuIsifier~available from Todd Combustion, ,Inc., of Stamford,~ Connecticut, with emulsion stability measured~ by ~centrifugation as described~ above. The results~ are~ s t out ~:in:Ta~le TI, which illustrates the lS~ :in~reaséd~ emulsification~ provided by emulsifier 3 over emu~si:fier ~ l due~to~ the~presence~of a mixed surfactant emulsi~ication system.`~

ApPearance '2~0~ Oil~ % Emulsion % Water Emulsifier~ 47~ 22 31 Emulsi~fier 3~ 19 ~ 71 lO

. : Example IV
.:
The~; effect~of~varying levels of emulsifiars on diesel 25~fuel,::,kerosene: and ~#2 fuel oil emulsions is illustrated by ~forming: émulsi~ons~according ' th procedure detailed in~ Example I using~emùlsifier:2 at levels o~ O~l~, 0~2%, : and ~;~.4~ m e~results are set out in Table III (for : :
~ ' di sel fuel~, Table ~lV (for kerosene), and Table V ~for ~: : : : :

-W093/0723~ PCT/US92/0~0~

~120~41 -18-#2 fuel oil).

Table III

Diesel Fuel % Water in % % %
5 Emulsion Emulsifier Emulsion Free Water 0.1 99.75 0.25 ::
0~1 96.5 3.5 0.1 77.0 23.0 0.2 100.0 0 ~
0~2 100.0 0 .
lS : 0.2 97.7 2.3 0.2 95.2 4.~
0.4 100 -0.4 99.95 0.05 : 15 15 0.4 99.95 ~.05 ~::
0.~ 100~0 0 .:
~:~ : 45 0.4 100.0 ~ ~:

.-:
.
Table IV :.
20 :~ Kerosene ~-~
:Water in ~ ~ % %
EmulsionEmuIsifier Emulsion Free Water -:.
~.1 99.8 0.20 ~: 10 ~ 0.1 99.75 0.25 15 ~ 0.1 99.75 0025 : :~.1 100.0 0 :~
- 0.2 99.8 ~.2~ ::
: : 10 ~.2 99.7~ 0025 ~0.2 1~0.0 0.2 10~.~ 0 ~ 0~4 10~.0 0 0.4 99.95 0. as ~5 0.4 99.95 ~.05 0~4 lOOo~) O
0~4 100~0 0 W093/0723~ ~CT/US92~U8083 21202~1 Table V
#2 Fuel Oil % Water in % % %
Emulsion Emulsifier Emulsion Free Water 0.4 99.95 0~05 ~.4 100.0 0 0.4 100.0 o -0.4 100.9 0 0.4 100.0 0 :

., .
:10The results illustrate the fact that increased emulsification can be achieved using increased levels of . .
the emulsification system used, regardless of the light fuel oils with which the emulsion is formed.

: ~ ~ Example V

., 15The effect on NOX emissions of using the inventive emulsions is illustrated by firing a ga turbine using #2 fuel oil (~aseline) and~ 2 55% water-in-~il emulsion : comprising:: 0.26%~: of emulsifier 3 (emulsion)~ The ~: ~ : wattage,: nitrogen oxides levels (further:broken down into NO and NO2~, carbon :monoxide levels, excess oxygen and :~: temperature:for each run are set out in Table VI.

: :: TABLE ~I

:~ Temp~
Meqawattaq~_ % O
25 Baseline 33 16.9 712 71 59 12 90 :
Baseline 32.5 17.0 716 84 71 13 ~0 : Emulsion 32~0 17.0 732 40 26 14 130 It shvuld be noted that firing the turbine with an W093/0723~ PCT/~S92/OX08~

21~02~1 -20-emulsion according to the present invention results in significant reductions in NO and total Nox as compared with baseline. In addition, although fired at a lower ;
wattage, the emulsion resulted in a higher effluent 5 temperature (indicating more efficient combustion) as compared with baseline. `

The above description is for the purpose of teaching `
.
: the person of ordinary skill in the art how to practice : ~:the present invention, and it is not intended to detail 10 all of those obv:ious modifications and variations of it w~ich :will become~ apparent to the skilled worker upon reading the description~. It is intended, however, that ;~ all such obvious mo:difications and variations be included : within the ~scope~ :of the present invention which is 15~ defined by~ the~following claims.

: ~ ~ ` : :
.~ :

-:'

Claims (15)

Claims

1. A fuel oil composition effective for reducing the emission of nitrogen oxides from a turbine, comprising an emulsion which comprises water and a light crude naphtha fuel oil, said emulsion further comprising an emulsification system which comprises:
a) about 25% to about 85% of an amide;
b) about 5% to about 25% of a phenolic surfactant;
and c) about 0% to about 40% of a difunctional block polymer terminating in a primary hydroxyl group.

2. The composition of claim 1, wherein said light crude naphtha fuel oil comprises distillate fuels, #2 oil, kerosene, jet fuels, and diesel fuels.

3. The composition of claim 2, wherein said amide comprise an alkanolamide formed by condensation of a hyroxyalkyl amine with an organic acid.

4. The composition of claim 2, wherein said phenolic surfactant comprise an ethoxylated alkylphenol.

5. The composition of claim 4, wherein said ethoxylated alkylphenol comprises ethylene oxide nonylphenyl.

6. The composition of claim 2, wherein said difunctional block polymer comprises propylene oxide/ethylene oxide block polymer.

7. The composition of claim 4, wherein said emulsifica-tion system further comprises from 0% to about 30% of a light crude naphtha fuel oil selected from the group consisting of distillate fuels, #2 oil, kerosene, jet fuel, and diesel fuel.

8. The composition of claim 1, which further comprises up to about 85% water-in-fuel oil.

9. The composition of claim 8, wherein said emulsification system is present in an amount of about 0.05% to about 5.0% by weight.

10. An emulsification system for a water and light crude naphtha fuel oil emulsion, said emulsification comprising:
a) about 25% to about 85% of an amide;
b) about 5% to about 25% of a phenolic surfactant;
and c) about 0% to about 40% of a difunctional block polymer terminating in a primary hydroxyl group.

11. The emulsification system of claim 10, wherein said amide comprises an alkanolamide formed by condensation of a hydroxyalkyl amine with an organic acid.

12. The emulsification system of claim 10, wherein said phenolic surfactant comprises an ethoxylated alkylphenol.

13. The emulsification system of claim 12, wherein said ethoxylated alkylphenol comprises ethylene oxide nonylphenyl.

14. The emulsification system of claim 10, wherein said difunctional block polymer comprises propylene oxide/ethylene oxide block polymer.

15. The emulsification system of claim 12, which further comprises from 0% to about 30% of a light crude naphtha fuel oil selected from the group consisting of distillate fuels, #2 oil, kerosene, jet fuel, and diesel fuel.