CA1333331C - Process for controlling sulfur-oxide formation and emissions when burning a combustible fuel formed as a hydrocarbon in water emulsion - Google Patents

Abstract

A process for controlling sulfur-oxide formation and emissions when burning a combustible fuel prepared from a hydrocarbon containing sulfur comprising forming a hydrocarbon in water emulsion and adding to the hydrocarbon in water emulsion a water soluble additive selected from the group consisting of Na+, K+, Li+, Ca++, Ba++, Mg++, Fe+++ and mixtures thereof so as to obtain SO2 emission levels upon combustion of said emulsion of less than or equal to 1.50 LB/MMBTU.

Description

1 33333~

BACKGROUN~ OF THE INVENTION
The present invention relates to a process for the preparation of liquid fuels and, more ~articularly, a process that allows a high sulfur fuel to be converted into energy by combustion with a substantial reduction in sulfur oxide emissions.
Low gravity, viscous hydrocarbons found in Canada, The Soviet Union, United States, China and Venezuela are normally liquid with viscosities ranging from 10,000 to 200,000 CP and API gravities of less than 12. These hydrocarbons are currently produced either by mechanical pumping, steam injection or by mining techni~ues.
Wide-spread use of these materials as fuels is precluded for a number of reasons which include difficulty in production, trans~ortation and han~linq of the material and, more importantly, unfavorable combustion characteristics including high sulfur oxide emissions and unburned solias. To date, there are two commercial processes practiced by power plant~ to reduce sulfur oxide emissions. The first process is furnace limestone injection wherein limestone injected into the furnace -2- ~

reacts with the sulfur oxides to form solid sulfate particles which are removed from the flue gas by conventional particulate control devices. The cost for burning a typical high sulfur fuel by the lime-stone injection method is between two to three dollars per barrel and the amount of sulfur oxides removed by the method is in the neighbourhood of 50%. A more effective process for removing sulfur oxides from power plants comprises flue gas desulfurization wherein CaO + H20 are mixed with the flue gases from the furnace. In this process 90% of the sulfur oxides are removed; however, the cost for burning a barrel of fuel using the process is between four and five dollars per barrel. Because of the foregoing, the high sulfur content, viscous hydrocarbons have not been successfully used on a commercial basis as fuels due to the high costs associated with their burning.
Naturally it would be highly desirable to be able to use the hydrocarbons of the type set forth above as a fuel.
Accordingly, the present invention se-eks to provide a process for the production of a combustible fuel from bitumens and residual fuel oils.

1 3 ~`3~ ~

In particular the present invention seeks to produce a liquid fuel from natural bitumens and residual fuel oils by forming an oil in water emulsion.
Further the present invention seeks to provide an oil in water emulsion for use as a liquid fuel having characteristics for optimizing the combustion process.
Still further the present invention seeks to provide optimum burning conditions for the combustion of an oil in water emulsion of natural bitumens and residual fuels so as to obtain excellent combustion efficiency, low unburned particulate solids and low sulfur oxide emissions.
~ he present invention relates to a process for burning a combustible fuel in the form of an oil in water emulsion, and, more particularly a process for controlling sulfur oxide formation and emissions when burning a sulfur containing hydrocarbon as an oil in water emulsion.
It is well known in the art to form oil in water emulsions either from naturally occurring bitumens or .~

residual oil in order to facilitate the production and/or transportation of these viscous hydrocarbons.
Typical processes are disclosed in U.S. Patent Nos.

3,380,531; 3,467,195; 3,519,006; 3,943,954; 4,099,537;

4,108,193; 4,239,052 and 4,570,656. In addition to the foregoing, the prior art teaches that oil in water emulsions formed from naturally occurring bitumens and/or residual oils can be used as combustible fuels.
See, for example, U.S. Patent Nos. 4,144,015;
4,378,230 and 4,618,348.
The present invention is drawn to a process for controlling sulfur-oxide formation and emissions when burning a combustible fuel prepared as an emulsion of a sulfur containing hydrocarbon, either a naturally occurring bitumen or a residual fuel oil, in water.
In accordance with the present invention, a hydrocarbon and water is admixed with an emulsifier to form a hydrocarbon in water emulsion. The water content, which generally depends on the type of hydrocarbon (heavy or light) being used, is generally 5 to 40% by volume. As the emulsion is being used as a combustible fuel the water content is preferably less than 30% by volume. The emulsifying agent, which is selected from any well known agent, is preferably present in an amount of between 0.1 to 5.0% by weight based on the total weight 3 3 3 ~

of oil in water emulsion. The emulsion may be prepared in the manner described in any of the ~rior art patents referred to above.
In accor~ance with the present invention, an additive which captures sulfur and prohihits the formation and the emission of sulfur oxides during combustion of the hydrocarbon in water emulsion is added to the emulsion prior to the combustion of same. The preferred additives for use in the process of the present invention are water soluble and are selected from the group consisting of ~a , ~ , Li , Ca Ba , Mg , Fe and mixtures thereof. The additive is added to the emulsion in a molar ratio amount of additive to sulfur in said hydrocarbon so as to obtain SO2 emissions upon combustion of the emulsion of less than or equal to 1.50 lb/MMBTU. It has been found that in order to o~tain the desired emissions level the additive must be present in a molar ratio of additive to sulfur of qreater than or equal to .050, preferably .100, in the hydrocarbon in ~ater emulsion.
While the level of ad~itive to obtain the desired resutt depends on the particular additive or combination of additives employed it has been found that a molar ratio of at teast .050 of additive to sulfur is required.

33~331 The emulsion as prepared above is then burned under the following conditions: fuel temperature (F) of 60 to 176 (i.e., 15.5 to 80C), preferably 68 to 140 (i.e., 20 to 60C), steam/fuel ratio (wt/wt) of 0.05 to 0.5, preferably 0.05 to 0.4, air/fuel ratio (wt/wt) of 0.05 to 0.4, preferably 0.05 to 0.3, and steam pressure (Bar) of 1.5 to 6, preferably 2 to 4, or air pressure (Bar) of 2 to 7, preferably 2 to 4.
In accordance with the present invention it has been found that the oil in water emulsion fuel produced in the process of the present invention when conditioned in accordance with the present invention and burned under controlled operating conditions results in a combustion efficiency of 99.9%, a low particulate solids content and sulfur oxide emissions consistent with that obtained when burning traditional No. 6 fuel oil. In addition, the amount of sulfur eliminated is in excess of 90%.
Conveniently the emulsion may have a droplet size for the oil of 10-60~m.
In accordance with the present invention, the process of the present invention is drawn to the preparation and burning of a fuel formed from a naturally occurring bitumen or residual fuel oil product. One of the fuels for which the process is suitable is a bitumen crude oil having a high sulfur . . .

1 333 33 1 ~6-335 -content such as those crudes typically found in the ~rinoco ~elt of Venezuela. ~he bitumen or residual oil has the following chemical and physical properties: C
wt.~ of 78.2 to 85.5, H wt.% of 9.0 to 10.8, ~ wt.~ of - 0.2 to L.3, N wt.% of 0.50 to 0.70, ~S wt.% of 2 to 4.5, ~sh wt.~ of 0.05 to 0.33, Vanadium, ~pm of 50 to 1000, ~ickel, ppm of 20 to 500, Iron, ppm of 5 to 60, Sodium, ~Pm of 30 to 200, Gravitv, ~PI of 1.0 to 12.~, Viscosity (CST~, 122F of 1,000 to 5,100,000, Viscosity (~ST~, 210F of 40 to l6,000, L~V (~TU/lb~ o~ 15,000 to 19,000, and ~sphaltenes wt.% of 9.0 to 15Ø In accordance with the present invention, a mixture comprising water and an emulsifying a~ditive is mixed with a viscous hydrocarhon or resiAual fuel oil so as to form an oil in water emulsion. It is a critical feature of the ~resent invention that the characteristics of the oil in water emulsion be such as to oPtimize combustion of the oil in water emulsion. ~he oil in water emulsion should be characterized by a water content of about between 5 to 40 vol.%, ~referably about between 15 to 35 vol.~. In accordance with the present invention, an a~itive which caPtures sulfur an~ Prohibits the formation and the emission of sulfur oxides during combustion of the hydrocarbon in water emulsion is adde~
to the emulsion prior to the combustion of same. ~he 1 3 ~333 ~ 86-335 preferred additives for use in the process of the ~resent invention are water soluble and are selected from the group consisting of Na , K , Li , Ca Ba , ~g , Fe and mixtures thereof The additive is added to the emulsion in a molar ratio amount of additive to sulfur in said hydrocarbon so as to obtain SO2 emissions upon combustion of the emulsion of less than or equal to 1.50 lb/MMBTU. It has been found that in order to obtain the desired emissions level the additive must be present in a molar ratio of additive to sulfur of greater than or equal to .OS0, preferably .100, in the hydrocarbon in water emulsion.
~hile the level of additive to obtain the desired result depends on the particular additive or combinat;on of additives employed it has been found that a molar ratio of at least .050 of additive to sulfur is required.
As noted above, the water also contains an emulsifier additive. The emulsifier is added so as to obtain an amount of about between 0.1 to 5.0 wt.~, preferably from about between 0.1 to 1.0 wt.~, based on the total weiqht of the oil in water emulsion produce~.
In accordance with the present invention, the emulsifier additive is selected from the grou~ consisting of anionic surfactants, non-ionic surfactants, cationic surfactants, mixtures of anionic and non-ionic surfactants and mixtures of cationic and non-ionic surfactants. The non-ionic surfactants suitable for use in the process are selected from the group consisting of ethoxylated alkyl phenols, ethoxylated alcohols, ethoxylated sorbitan esters and mixtures thereof. Suitable cationic surfactants are selected from the group consisting of the hydrochlorides of fatty diamines, imidazolines, ethoxylated amines, amido-amines, quaternary ammonium compounds and mixtures thereof while suitable anionic surfactants are selected from the group consisting of long chain carboxylic, sulphonic acids and mixtures thereof. A
preferred surfactant is a non-ionic surfactant with a hydrophilic-lipophilic balance of greater than 13 such as nonylphenol oxyalkylated with 20 ethylene oxide units. Preferred anionic surfactants are selected from the group consisting of alkylaryl sulfonate, alkylaryl sulfate and mixtures thereof.
It has been found that the content of the sulfur capturing additive in the oil in water emulsion has a great effect on its combustion characteristics, particularly on sulfur oxide emissions. It is believed that, due to high interfacial bitumen-water surface to volume ratio, the additives react with sulfur compounds present in the fuel to produce sulfides such as sodium D
, - 1 3~333 1 86-335 sulfi~e, potassium sulfide, magnesium sulfide and calcium sulfide, etc. Durinq combustion, these sulfides are oxidized to sulfates thus fixing sulfur to the combustion ashes and thus preventing sulfur from going into the atmosphere as part of the flue gases. ~he amount of additive required depends on (1) the amount of sulfur in the hydrocarbon, and (2~ the particular additive being used.
Once the oil in water emulsion is conditioned it is ready for burning. Any conventional oil gun burner can be employed such as an internal mixing burner or other twin fluid atomizers. Atomization using steam or`air under the following operatinq conditions is preferred:
fuel temperature (F~ of 60 to 176, preferably 60 to 140, steam/fuel ratio (wt!wt~ of 0.05 to 0.5, preferably 0.05 to 0.4, air/fuel ratio (wt/wt) of 0.05 to 0.4, preferably 0.05 to 0.3, and steam pressure (Bar) of 1.5 to 6, preferably 2 to 4, or air pressure (Bar~ of 2 to 7, preferably 2 to 4. Under these conditions excellent atomization and efficient combustion was obtained coupled with goo~ flame stability~
Advantages of the present invention will be made clear from a consi~eration of the followinq examples.

EXAMPLE I
In order to demonstrate the effect of the additive of the present invention on the combustion characteristics of the oil in water emulsions of the present invention, seven bitumen in water emulsions were prepared having the compositional characteristics set forth below in ~able 1.

TABLE I

FUEL r~ Tr~`-~TSTICS

~r~'rTNE EMULSION EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION #1 #2 #3 #4 #5 #6 ADDITIVE/SULFUR
(MOLAR/RATIO) 0 0.011 0.019 0.027 0.036 0.097 0.035 Na (% molar) 0 95.4 95.4 95.4 95 4 95 4 95 4 I K (% molar) 0 0.7 o 7 0 7 0 7 0 7 0 7 w Li (% molar) 0 1.4 1.4 1.4 1.4 1.4 1.4 I Mg (% molar) 0 2.5 2.5 2.5 2.5 2.5 2.5 LHV (BTU/LB) 13337 13277 13158 13041 12926 12900 12900 VOL % OF BITUMEN 78.0 77.9 77.i 77.5 77.3 70 70 '-~
VOL % OF WATER 22.0 22.1 22.3 22.5 22.7 30 30 ~'J
WT. % OF SULF~R 3.0 3.0 3.0 3.0 2.9 2.7 2.7 Combustion tests were conducted un~er t~e operating conditions set forth in Table II.

-l4-TABLE II

OPERATING CONDITIONS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION #1 #2 #3 #4 #5 #6 FEED RATE (LB/H) 59.9 60.0 60.1 60.3 60.4 63.7 63.7 THERMAL INPUT (MMBTU/H) 0.82 0.82 0.82 0.82 0.82 0.82 0.82 FUEL TEMPERATURE (F) 154 154 154 154 154 154 152 STEAM/FUEL RATIO (W/W) 0.30 0.30 0.30 0.30 0.30 0.30 0.30 STEAM PRESSURE (BAR) 2.4 2.4 2.4 2.4 2.4 2.4 2.4 MEAN DROPLET SIZE (~m) 14 14 14 14 14 14 14 1 3 7~333 ~ 86-335 The combustion characteristics are summarize~ in Table III below.

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S ~O ~D
G~ o z H
ul ~r ,~ # 0 1--o a~~ ~.
--~ ~ o . ~~ a~

Z o H O
Ul ~
U ~ # ~D ~ CO X

G~ HO #
H E- Ul ~
H ~ 1 Z
H ~ ~ O ~a` O O
~ ~ --I ~D a~ o C1~ H
:~ ~ G~
0~ ~ z ::~ Z

E-~ Ul ~ ~ ~r co O
Ul O
0~ ~ _ ~~ ~ ~ ~ ~ ~ C'' G'l Ul Z O

; Ul G
l-- CO C
U ~ oer --~ o ,, Z
~ ~ ~D '7 O~ I O~ C O
C G ~
~ 'Q
O
UQ
Il Z
o ~ _ Z
d~ O
z m dP O ~
~ Z -- H l':C
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E~ H Z ~t ~
dr _ m E~ H5 Z a o d~ ^ ~ ^ -- ~ E~ G~l G~
O ~ --~ DJ m ~ F G~ UQ H CC Ga~
Q- O~ ~ 0~ ~ UQ
~ ~_ _ _ _ : ~ O ~:
UQ m ~ X O ~,) G3 O O ~ O O O O UQ ~ *
OUQ UQUQ Z * ~ * *

13~;333 1 86-335 Table III clearly indicates that as the ratio of additive to sulfur increases the combustion efficiency of the emulsifled hydrocarbon fuels improves to 99.9~.
In adAition to the foreqoing, the comparative data of mable III shows that ~S02 and ~03 emission levels improve as the additive to sulfur ratio increases. As can be seen from emulsion No. 5, the efficiency of ~2 removal is in excess of 90~ at an additive to sulfur ratio of .097. In addition, the sulfur oxide emissions in LB/MMBTU is far less than the 1.50 LB/MMBTU obtained when burning No. 6 fuel oil. In addition, the burning of said optimized oil in water emulsions leads to a substantial decrease of sulfur trioxi~e formation thus preventing corrosion of heat transfer surfaces due to sulfuric acid conAensation (low temPeratUre corrosion~.
Furthermore, the burning of saiA ootimized oil in water emulsion leads to the formation of high melting ~oint ashes thus preventing corrosion of heat transfer surfaces due to vanaAium attack (high temperature corrosion~. Note that the primary additive in these tests is so~ium.
In a~dition, com~arison of emulsions No. 4 and No.

6, burned with same additive to sulfur molar ratio, shows that dilution of bitumen in the aqueous phase (from 77.3 to 70.0 ~ercent volume) has no effect on 1 3 ~333 1 ~6-335 combustion characteristics while ren~ering equivalent S2 re~uction (53.7 vs. 52.3 percent~.

EXAMPLE II
Six a~ditional oil in water emulsions were prepared employinq the same bitumen of Example I. The com~ositional characteristics of these emulsions are set forth in Table IV helow.

TABLE IV

FUEL CHARACTERISTICS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION #7 ~8 #9 #10 #11 ADDITIVE/SULFUR
(MOLAR/RATIO) -- 0.014 0.027 0.035 0.044 0.036 O Na (% molar) 0 95.4 95.4 95.4 95.4 95 4 K (% molar) 0 0.7 0.7 0.7 0.7 0 7 Li (% molar) 0 1.4 1.4 1.4 1.4 1.4 Mg (% molar) 0 2.5 2.5 2.5 2.5 2.5 LHV (BTU/LB) 13083 12739 12429 12119 11826 12900 ~J~
VOL ~ OF BITUMEN 76 74 72.2 70.4 68.7 70 VOL % OF WATER . 24 26 27.8 29.6 31.3 30 _~
WEIGHT % OF SULFUR 2.9 2.8 2.8 2.7 2.6 2.7 t 3 ~333 ~ 86-335 ~ hese emulsions were combuste~ un~er the o~erating con~itions set forth in Table V, TABLE V

OPERATING CONDITIONS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION #7 #8 ~9 #10 #11 FEED RATE (LB/H) 55.1 56.5 57.8 59.4 60.9 63.7 THERMAL INPUT (MMBTU/H) 0.75 0.75 0.75 0.75 0.75 0.82 I FUEL TEMPERATURE (F) 149 149 149 149 149 154 I STEAM/FUEL RATIO (W/W) 0.30 0.30 0.30 0.30 0.30 0.30 STEAM PRESSURE (BAR) 2.4 2.4 2.4 2.4 2.4 2.4 W
MEAN DROPLET SIZE (~m) 32 32 32 32 32 32 1 3 ~333 1 The combustion characteristics are summarize~ in Table Vl, U~ ~
~ # o ~ , o z o U o #

Z o o o U~
o o , ~
un z ~J O
': ~ # O O ~ Z

Z ~ Z
O ~ t' U~ ~-- ~ C
# O ~ U~ ~0 0 Z ~ ~r o a~ ~ ~ ~
O ~ _~ ~ ~ ~ ~ ~ O
cn ~, Z u, o~ Z O
o ~ ~ O O ~ ~ ~ ~ C' ~ o I o~ o o ~ .
o u~ c~
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dP ~ ~ ~ H Z ~ O
o ~ I cL m ~ ~ 8 ~ ~
g ~ ~ ~ ~ oc m H o ~ o ~ un m ,, ,~ ~ x o c~ ~
o o ~ o o o o un ~c *
o u~ cn un z ~c 1 3 ' 3 ~ 86-335 Again, it is clear from Table VI that an increase in additive to sulfur ratio results in improved combustion efficiency and superior sulfur oxide emisSiOnS. ~ote that sodium was the primary element in the additive.
In addition, ~omPariSOn of emulsion No. 11 with emulsion ~o. 6 from previous example, both burned at identical thermal input (0.82 ~MBTU/H), shows that the difference in mean droplet size (34 vs. 14 ~m) does not affect combustion characteristics while rendering equivalent SO2 captures (51.7 vs. 52.3 percent) when burned with same ad~itive to sulfur molar ratio.
Further, a comparison of emulsions ~o. 9 and ~o.
11, shows that SO2 capture does not depend on thermal input.

EXAMPLE III
Seven further oil in water emulsionæ were prepared employing a residual fuel oil as the viscous hydrocarbon. The compositional characteristics of these emulsions are set forth below in Table VII.

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#
~ ~ - - o ~ r~
c~o o~ o o o ~
o ~ ~o tn-l ~
#
~ o o~ o o o o ~n ~n~
#o o u~ ut o s a~
o a~ o o o --I ~o o ~ ~r cn-l ~
~ #
tn O~ O O O --I r~
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r ' cn_~
o o L~
CD ~ ~ O a~ O O O
Z
~n ~ ~, ~ o o u~
~ o ~ o o o ~
c~ z z o cn c~ ~ co t ~ o cr~
c ~ I o o o o ~ r~ ~ ~

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O O O O -- E~
E E E E m ~ ~:
m 3 u~
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c~ E~ O O O
S o CD 1 4 C d~ dll dO
C~ ~ O O

1 3 ~33 3 1 86-335 Combust ion teStS were run un~er the foLlowing operating conditions.

TABLE VIII

OPERATING CONDITIONS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION #12 #13 #14 #15 #16 #17 FEED RATE (LB/H) 55.1 57.2 59.2 59.2 62 64.7 66 THERMAL INPUT (MMBTU/H) 0.75 0.75 0.75 0.75 0.75 0.75 0.75 c~
FUEL TEMPERATURE (F) 149 149 149 149 149 149 149 STEAM/FUEL RATIO (W/W~ 0.30 0.30 0.30 0.30 0.30 0.30 0.30 ~J~!
STEAM PRESSURE (BAR) 2.4 2.4 2.4 2.4 2.4 2.4 2.4 MEAN DROPLET SIZE (~m) 32 32 32 32 32 32 32 W

1 3 ,3~3 1 86-335 The combustion characteristics are summarize~ in Table IX below.

TABLE IX

COMBUSTION CHARACTERISTICS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION ~12 ~13 ~14 #15 #16 . t17 C2 (vol.g) 13.5 13,4 14 14 13.5 14 13.2 Co (ppm) 61 30 60 18 10 13 10 2 (vol.%) 3.0 3.2 2.9 2.6 3.2 2.9 3 S2 (ppm) 2357 1650 1367 1250 940 500 167 w S2 (LB/MMBTU) 3.6 2.5 2.1 1.9 1.4 0.8 0.3 SO3 (ppm) 18 16 9 8 7 6 nil NOx (ppm) 500 510 400 430 360 240 218 i~;
*S2 REDUCTION (%) -- 30.0 42.0 47.0 60.0 79.0 93.0 **COMBUSTION
EFFICIENCY (%) 99.9 99.9 99.9 99.9 99.9 99.9 99.8 * S2 REDUCTION (%) = SO2 BASELINE - SO2 EMULSION t X 100 w ** BASED ON CARBON CONVERSION

1 33333~ 86-335 Table IX again clearly indicates, as did Tables III
and VI, that as the ratio of additive to sulfur increases the combustion efficiency of the emulsified hydrocarbon fuels improves. In addition, Table IX
clearly shows that sulfur oxide emission levels decrease as the additive to sulfur ratio increases. Again it can be seen from emulsions 16 and 17 that sulfur oxide emissions obtained are less than that attainable when burning No. 6 fuel oil. Note that magnesium was the ~rimary element in the additive.

EXAMPLE IV
An additional six oil in water emulsions were prepared using a high sulfur No. 6 fuel oil as the hydrocarbon component. The compositional characteristics of these emulsions are set forth below in Table X.

TABLE X

FUEL CHARACTERISTICS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION #18 Yl9 #20 #21 #22 I ADDITIVE/SULFUR
w (MOLAR/RATIO) -- 0.007 0.019 0.032 0.045 0.15 Na (% molar) 0 95.4 95.4 95.4 95.4 95.4 K (% molar) O 0.7 0.7 0.7 0.7 0.7 Li (% molar) 0 1.4 1.4 1.4 1.4 1.4 Mg (% molar) 0 2.5 2.5 2.5 2.5 2.5 ( , LHV (BTU/LB) 13215 13215 13215 13215 13215 12686 VOL % OF FUEL 75 75 75 75 75 72 VOL % OF WATER 25 25 25 25 25 28 WT. ~ OF SUL~UR 1.9 1.9 1.9 1.9 1.9 1.9 1 33333~

Combustion tests were conducted under the O~eratin~
conditions set forth in Table XI.

TABLE XI

OPERATING CONDITIONS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION tl8 tl9 t20 ~21 #22 FEED RATE (LB/H) 54.5 54.5 54.5 54.5 54.5 56.8 I THERMAL INPUT (MMBTU/H) 0.75 0.75 0.75 0.75 0.75 0.75 w PUEL TEMPERATURE (F) 149 149 149 149 149 149 STEAM/FUEL RATIO (W/W) 0.30 0.30 0.30 0.30 0.30 0.30 ~!
STEAM PRESSURE (BAR) 2.4 2.4 2.4 2.4 2.4 2.4 W
MEAN DROPLET SIZE (~m) 34 34 34 34 34 34 --~

13'S7~3~ 86-335 The combustion characteristics and these emulsions are summarized in Table XII.

TABLE XII

COMBUSTION CHARACTERISTICS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION #-18 #19 #20 #21 #22 C2 (vol.%) 14.3 14.2 14.1 14.2 14.0 13.9 Co (ppm) 10 12 8 14 10 8 2 (vol.%) 2.9 2.9 3 2.8 2.9 3 S2 (ppm) 1730 1522 1384 1176 858 62 o~ <~
S2 (LB/MMBTU) 2.5 2.2 2.0 1.7 1.2 0.1 ~1 SO3 (ppm) 12 14 8 8 9 nil NOx (ppm) 210 212 209 215 214 223 ~S2 REDUCTION (%) -- 12.0 20.0 32.0 50.4 96.4 **COMBUSTION
EFFICIENCY (%) 99.8 99.9 99.9 99.9 99.9 99.9 w S2 REDUCTION (%) = SO2 BASELINE - SO2 EMULSION ~ w ** BASED ON CARBON CONVERSION

13`~333~ 86-335 Again, as was the case in Examples I-III, Table XII
clearly shows the effect o~ the additives of the present invention on the sulfur emissions when these emulsions are burned as a fuel. Note that sodium was the primary element in the additive.

EXAMPLE V
A final seven oil in water emulsions were prepared using a high sulfur vacuum gas oil as the hydrocarbon component of the emulsion. The compositional . 10 characteristics o~ the emulsions are set forth below in Table XIII.

13 i`3331 o cn O ~ O

H 1~
U~ ~ O
# o ~r ~ O ~ O --I ~ ~ I~
Z
H ~O
U~ ~ O
# o ~r o a~ o o u~ ~In O
U~ ~ #
O ~ O _~ ~ _1 1 . O
X _ ~ ~
cn ~ ~ o , ~ # ~
IIS r ~ O C~ O ~

U~ ~ ~ O
# o ~r ~ o r~
1 ~ o a~ o ~ Z
Z O
_' U~ O
~ ~ (~
C
I O O O O

O O O O ^ ~ E~ ~

O O O

C
~ O O E~

1 33333~

-These emulsions were combuste~ unaer the operating con~itions set forth in Table XIV.

TABLE XIV

OPERATING CONDITIONS

BASELINE EMULSION EMULSION EMULSION EMULSION EMULSION EMULSION
EMULSION t23 #24 #25 #26 #27 #28 FEED RATE (LB/H) 54 54 54 54 54 54 57 THERMAL INPUT (MMBTU/H) 0.75 0.75 0.75 0.75 0.75 0.75 0.75 o ~
FUEL TEMPERATURE (F) 149 148 77 79 147 147 149 ~J~
STEAM/FUEL RATIO (W/W) 0.15 0.15 0.15 0.15 0.15 0.15 0.05 ~J_ STEAM PRESSURE (BAR) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 ~J~
MEAN DROPLET SIZE (4m) 14 14 14 14 14 14 14 .

~ 33333 1 86-335 The combustion characteristics are summarized in the Table XV below.

U~ a~
t~
~ # . a~ o o S~ O
~~ ~~ ~ O ~ ~ ~ C~'~
o H

U~ I`
t~
O
~ ~ o ~ O a~
t~ --' ~ ~ ~ o ~ ~ a~ a~
z H
U~ ~D
t~ ~ ,r~ 1~1 X ~ CO ~ O
~ ~ ~ U~ O
t~ r o ~ ~~ a~

Z O
H O
t~ O a~ X
U~ ~ # . Od' O
~ ~: ~ o o --4 o a~
U
tr O
U~ ~
X ~ ~ #. O~ O ~ o O
S,., ," ,_ O ~ a~ H
t~ I ~ U~
m ~ z ~ z H ~ t U, 3 # . ~ ~ ~ o ~ . u~ t ~ ~ ~ O r~ ~. ~
m ~ ts~ U
C~ ~ Z - Z
1-- H t t U~ ~
~ U
U ~ ~ O ~ O ,~, Z
~ ~ ~ O CO o ~ I ~ t O
O t~
U~ ~
o _ Z

Z -- H ~
~ O E~ ~
E-l H Z~ ~) m E~ o ~ ~ z dP ~ e ~ H æ t~
dP ^ ~ ^ ^ ~ E~ t~ t~
E ~ 6t ~ u~ H P t~
~:> C4g P~ t~ ~ ~tr~ ~ tH~ o~ u~
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1 3~333 1 Once again the effect of the additives on the sulfur oxide emissions is clearly demonstrated. ~s the ratio of additive to sulfur increases the combustion efficiency of the emulsified hydrocarbon fuels im~roves to 99.9%. SO2 and SO3 emission levels improves as the additive to sulfur ratio increases. As can be seen from emulsion numbers 25, 26, 27 and 28, the efficiency f ~S2 removal increases as the additive to sulfur ratio increases. In addition, the sulfur oxide emissions in LB/MMBTU for emulsions 25-28 are equal to or less than that obtained when burning No. 6 fuel oil.

EXAMPLE Vl Major component of ash produced when burning these emulsified fuels such as emulsions ~o. 15, ~o. 16 and ~ 17 was reported as 3 MgO.V2O5 (magneslum orthovanadate~ whose melting point is 2174F. Magnesium orthovanadate is a very well known corrosion inhibitor for vanadium attack in combustion systems. Therefore, ashes from emulsions burnt using additives consisting of elements selected from the qroup of Ca , Ba ~g and Fe or mixtures thereof and ashes from emulsions burnt using additives consisting of elements selected from the grou~ of ~a , K , Li and Mg , where Mq is the primary element will render high temperature-corrosion free combustion. Such high temperature corrosion is normally cause~, in liquid hydrocar~on combustion, by vanadium low melting point compounds.
This invention may be embodied in other forms or carried out in other ways without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered as in all respects illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.

Claims (19)

1. A process for controlling sulfur-oxide formation and emissions when burning a combustible fuel prepared from a hydrocarbon containing sulfur comprising:
a) providing a sulfur containing hydrocarbon having the following chemical and physical properties:
C wt. % of 78.2 to 85.5;
H wt. % of 9.0 to 10.8;
O wt. % of 0.2 to 1.3;
N wt. % of 0.05 to 0.70;
S wt. % of 2 to 4.5;
Ash wt. % of 0.05 to 0.33;
Vanadium, ppm of 50 to 1000;
Nickel, ppm of 20 to 500;
Iron, ppm of 5 to 60;
Sodium, ppm of 30 to 200;
Gravity, °API of 1.0 to 12.0;
Viscosity (CST): 122°F. of 1,000 to 5,100,000; 210°F. of 40 to 16,000;
LHV (BTU/lb) of 15,000 to 19,000, and Asphaltenes wt. % of 9.0 to 15.0;
(b) forming a hydrocarbon in water emulsion having a water content of 5 to 40%, by volume, by admixing said sulfur containing hydrocarbon and water with an emulsifier and a water soluble additive selected from the group consisting of Na+, K+, Li+, Ca++, Ba++, Mg++, Fe+++ and mixtures thereof, said additive being added in a molar ration amount of additive to sulfur in said hydrocarbon so as to obtain SO2 emission levels upon combustion of said emulsion of less than or equal to 1.50 lb/MMBTU, said emulsifiers being present in an amount of between 0.1 to 5.0%, by weight, based on the total weight of the hydrocarbon in water emulsion; and (c) burning said emulsion at a fuel temperature of 15.5 to 80°C. and i) a steam/fuel ratio of 0.05 to 0.5 wt/wt and a steam pressure of 1.5 to 6 Bar, or ii) an air/fuel ratio of 0.05 to 0.4 wt/wt and an air pressure of 2 to 7 Bar.

2. A process according to claim 1, wherein said molar ratio of additive to sulfur is greater than or equal to .050 in said hydrocarbon in water emulsion.

3. A process according to claim 1, wherein said molar ratio of additive to sulfur is greater than or equal to .100 in said hydrocarbon in water emulsion.

4. A process according to claim 1 wherein said emulsifier additive is selected from the group consisting of anionic surfactants, non-ionic surfactants, cationic surfactants and mixtures of cationic and non-ionic surfactants.

5. A process according to claim 4 wherein said non-ionic surfactants are selected from the group consisting of ethoxylated alkyl phenols, ethoxylated alcohols, ethoxylated sorbitan esters and mixtures thereof.

6. A process according to claim 4 wherein said cationic surfactants are selected from the group consisting of the hydrochlorides of fatty diamines, imidazolines, ethoxylated amines, amido-amines, quaternary ammonium compounds and mixtures thereof.

7. A process according to claim 4 wherein said anionic surfactants are selected from the group consisting of long chain carboxylic, sulfonic acids and mixtures thereof.

8. A process according to claim 1, wherein said emulsifier additive is non-ionic surfactant with a hydrophilic-lipophilic balance of greater than 13.

9. A process according to claim 8, wherein said non-ionic surfactant is nonylphenol oxyalkylated with 20 ethylene oxide units.

10. A process according to claim 7, wherein said anionic surfactant is selected from the group consisting of alkylaryl sulfonate, alkylaryl sulfate and mixtures thereof.

11. A process according to claim 1, wherein said emulsifier additive is present in an amount of about between 0.1 to 5%, by weight, based on the total weight of the oil in water emulsion.

12. A process according to claim 1, including conditioning said oil in water emulsion so as to obtain an oil in water emulsion characterized by a water content of from about 5-30 wt. %, a droplet size of from about 10-60 µm.

13. A process according to claim 1, wherein said fuel temperature is 20 to 80°C.

14. A process according to claim 1, wherein said burning is under the following operating conditions:
fuel temperature (°C) of 20 to 60; and i) steam/fuel ratio (wt/wt) of 0.05 to 0.4;
and steam pressure (Bar) of 2 to 4 Bar; or ii) air/fuel ratio (wt/wt) of 0.05 to 0.3; and air pressure of 2 to 4 Bar.

15. A process according to claim 1, 3, 4, 5, 6, 7, 8, 9, 10 or 11, wherein step b) comprises forming an oil in water emulsion having said water content of from about 5-40 vol. %, an oil droplet size of from about 10-60 µm and a molar ratio amount of additive to sulfur in said hydrocarbon of greater than or equal to 0.050 in order to reduce the amount of sulfur emissions produced during subsequent burning as a liquid fuel, and including a step of heating said oil in water emulsion to a temperature of 20 to 80°C. and atomizing said fuel with a diluent selected from the group consisting of steam and air wherein said steam is at a pressure of 1.5 to 6 Bar in a steam to fuel ratio of 0.05 to 0.5 and said air is at a pressure of 2 to 7 Bar in an air to fuel ratio of 0.05 to 0.4; and step c) comprises burning said atomized fuel whereby SO2 emission levels of less than or equal to 1.50 lb/MMBTU are obtained.

16. A process according to claim 15, wherein said fuel temperature is 20 to 60°C., said steam pressure is 2 to 4 Bar and said steam to fuel ratio is 0.05 to 0.4; or said pressure is 2 to 4 Bar and said air to fuel ratio is 0.05 to 0.3.

17. A hydrocarbon combustible fuel comprising a sulfur-containing hydrocarbon-in-water emulsion and a sulfur capturing additive selected from the group consisting of Na+, K+, Li+, Ca++, Ba++, Mg++, Fe+++
and mixtures thereof, said additive being present in said emulsion in a molar ratio of additive to sulfur of greater than or equal to 0.05, said sulfur containing hydrocarbon having the following chemical and physical properties:
C wt. % of 78.2 to 85.5;
H wt. % of 9.0 to 10.8;

O wt. % of 0.2 to 1.3;
N wt. % of 0.05 to 0.70;
S wt. % of 2 to 4.5;
Ash wt. % of 0.05 to 0.33;
Vanadium, ppm of 50 to 1000;
Nickel, ppm of 20 to 500;
Iron, ppm of 5 to 60;
Sodium, ppm of 30 to 200;
Gravity, °API of 1.0 to 12.0;
Viscosity (CST): 122°F. of 1,000 to 5,100,000; 210°F. of 40 to 16,000;
LHV (BTU/lb) of 15,000 to 19,000, and Asphaltenes wt. % of 9.0 to 15.0;
said emulsion having a water content of 5 to 40%, by volume, said emulsifier being present in an amount of between 0.1 to 5.0%, by weight, based on the total weight of the hydrocarbon-in-water emulsion.

18. A fuel according to claim 17, wherein said hydrocarbon contains sulfur and said additive is present in said emulsion in a molar ratio of additive to sulfur of greater than or equal to 0.1.

19. A hydrocarbon combustible fuel comprising a hydrocarbon-in-water emulsion comprising a sulfur capturing additive, an emulsifier and a sulfur containing hydrocarbon having the following chemical and physical properties:
C wt. % of 78.2 to 85.5;
H wt. % of 9.0 to 10.8;
O wt. % of 0.2 to 1.3;
N wt. % of 0.05 to 0.70;
S wt. % of 2 to 4.5;
Ash wt. % of 0.05 to 0.33;
Vanadium, ppm of 50 to 1000;
Nickel, ppm of 20 to 500;

Iron, ppm of 5 to 60;
Sodium, ppm of 30 to 200;
Gravity, °API of 1.0 to 12.0;
Viscosity (CST): 122°F. of 1,000 to 5,100,000; 210°F. of 40 to 16,000;
LHV (BTU/lb) of 15,000 to 19,000 and Asphaltenes wt. % of 9.0 to 15.0;
said sulfur capturing additive being selected from the group consisting of Na+, K+, Li+, Ca++, Ba++, Mg++, Fe+++ and mixtures thereof, said hydrocarbon in water emulsion having a water content of from about 5 to 30 volume percent, an oil droplet size of from about 10 to 60 µm and a molar ratio amount of sulfur capturing additive to sulfur in the hydrocarbon of greater than or equal to .100 in order to reduce the amount of sulfur emissions produced during subsequent combustion of said hydrocarbon in water emulsion by at least 90%
so as to obtain SO2 emissions upon combustion of less than or equal to 1.50 lb/MMBTU.