CA1168869A - Emulsified fossil fuel slurries for combustion applications - Google Patents

Abstract

Abstract Development of auxiliary fuel injection at the tuyeres for blast furnaces began prior to 1958, and the first commercial application occurred in June, 1959, using natural gas. This initial work was based on a search for a more economical means to provide the chemical and thermal requirements for the manufacture of pig iron from iron ore. Successful injection of auxiliary fuels has progressed from two furnaces in 1960 to an estimated 80 to 90%
of over 200 furnaces in operation today.
The hydrocarbon fuels used today are: natural gas, coke-oven gas, heavy and residual oils, tar and pulverized coal with the last one applied to only two furnaces in the country. The two -major fuels used are natural gas and residual oil. Many of the furnaces using natural gas have been changing to oil or tar.
Research and development has continued toward increasing the injection rates in order to both increase iron production and reduce the coke rate (due to a lack of coke manufacturing capacity).
Since the oil embargo and the shortages of fuel oils and natural gas, the steel industry has expanded its search to include the substitution of natural gas and oil for either pulverized coal, coal/oil slurries or coal/coal tar slurries. In the majority of installations the present cost of new, coal handling and crushing facilities is prohibitive in today's economy and the slurry approach is more attractive. However, the problem with slurries is that the pulverized coal has a decided tendency to settle, causing plugging problems and increasing maintenance costs.

An easy, economical method for manufacturing stable slurries (ones in which the coal will not settle) is with the use of our HIPR-Fluid* struc-tured emulsion technology using our HIPR-Fluid emulsifiers. Based on our HIPR patents, we have been capable of transporting coal up to 1112"
* Trademark, Petrolite Corporation, High Internal Phase Ratio.

Description

1! 1 6 ~

. our recent energy crisis highlighted the importance of extending our liquid hydrocarbon resources and of conserving them for uses other than as fuels. The im-portance of coal as an abundant source of ener~y for fuel purposes was clearly indicated, but coal, being a solid, is difficult if not impossible to handle in a simpl~ feed system havinq uniform fuel properties. Therefore it would be hiqhly desirable to be able to handle coal as a liquid ~uel where it could be furnished to combustion equipment as a stable, pumpable slurry of uniform consistency.

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Heretofore, various slurries of coal have been prepared but such slurries have various difficulties associated with them in that the particles of coal settle to the bottom under static conditions making it difficult or impossible to utilize the coal or combustible solids in the slurry due to a non-uniform slurry composition containing various proportions of solids and liquids resulting in some cases in an unpumpable compacted paste containing most of the solids and a fluid liquid con-taining little of the solids. Therefore, it is highly desirable to have coal slurries which are prepared such that the coal particles or other combustible solids are uniform in size and distribution throughout the slurry and such that the solids do not settle out thus making such specially prepared coal or combustible solids slurry in a form that has a uniform composition of solids and liquids and in a form that is capable of being delivered to various combustion devices as a stable, pumpable, uniform and non-settling composition~
In preparing the "fluid coal" of this invention, it is necessary to comminute large particles of coal into smaller particles. Comminuting coal in a dry state is hazardous because the presence of coal dust in air due to such comminution forms an explosive mixture. In addi-tion, where coal is first comminuted and then added to the emulsion, apart from the explosive hazard and the difficulty of incorporating large concentrations of coal in the emulsion~ the process involves two steps.
We have now discovered a process which comprises the in situ comminution of coal in the emulsion or during a stage in the preparation of the emulsion~ Thus, the . . ~ . .

~ 1 6~,~,69 present process is essentially a one step process which avoids the necessity of a two step process of first comminuting coal separatel~ in a dry state, with the accompanying problems of explosive coal dust and then adding the dry comminuted coal to the emulsion.
According to one aspect of t:he invention there is provided a process of preparing a non-settling coal-containing emulsion which comprises adding coal, in an amount of about 30% to about 60~ by weight, to a high internal phase ratio emulsion or during the preparation of a high internal phase ratio emulsion, said emulsion comprising an emulsifying agent, an emulsifiable oil and water, said water being the external phase, and comminut-ing the coal in situ.
According to another aspect of the invention there is provided a method of preparing a stabilized fuel slurry having liquid fuel oil present in the range of from about 32% by weight to about 45% by weight, solid fuel particles with diameters as large as about 1/4" present in the range of from about 30% by weight to about 60~ by weight, water present in the range of from about 4.5% by weight to about 5% by weight and an emulsifier capable of forming a thixo-tropic water external-oil high internal phase emulsion present in the range of from about 0.5% by weight to about 5% by weight, said method comprising adding solid fuel to a high internal phase ratio emulsion or during the prepara-tion of a high internal phase ratio emulsion, agitating the mixture to form a thixotropic water external~oil high internal phase emulsion and to comminute the solid fuel particles, to form a stabilized fuel slurry having solid fuel particles with diameters as large as about 1/4 inch.

fi 9 According to yet another aspect of the invention there is provided a method of preparing a stabilized coal slurry comprising adding solid coal to a high internal phase ratio emulsion or during the preparation of a high internal phase ratio emulsion, agitating the mixture to form a thixotropic water externall-oil high internal phase emulsion and comminuting the coal ln situ~
The stable, pumpable, uniform, non-settling coal slurries formed by in situ comminution can be handled as uniform compositions, i.e., the coal or solids will not settle out when the mixture is either in a static or a dynamic state. Stated another way, the coal or combus-tible solids slurries of this invention can be handled and stored as stable, uniform, pumpable, non-settling compositions without incurring the problems associated with slurries in a static mode, i.e., the problems associated with slurries in storage or interim use where the solids might settle and thereby produce non-uniform compositions which have unstable pumping cycles and combustion characteristics.
For example, when slurries of coal in oil are prepared for injection into steel mill blast furnaces, the particles of coal settle out thus making it difficult to pump a fuel to the furnace which has a uniform solids/liquid compo-sition. Petroleum in various forms has been used in blast furnace operations and thus petroleum or water/oil emulsions or suspensions of petroleum have been employed.
~lowever in view of the abundance and relative low cost of coal, it is highly desirable to extend the use of petroleum 3~ as a fuel. Therefore being able to handle coal as a fuel extender in a stable, pumpable, uniform, non-settling ~.~

1 3 ~ , 6 9 slurry form similar to that used for petroleurn fuels or water-petroleum emulsions is highly desirable.
Our method produces oil emulsions which are heavily loaded with coal or other combustible solids and which can be handled and pumped with the ease of petroleum, while making use of the low cost and availability of coal or other solids. By this method emulsions of fluid coal can be delivered as a fluid to a combustion chamber regardless of the composition's previous static or dynamic state.
Coal-loaded emulsions can be prepared by a variety of methods, including the Eollowing:
(1) The emulsion is first prepared and the coal added thereto is comminuted in situ;

(2) The exterior phase, such as water and emulsifier, is placed in a vessel, and the coal added thereto is comminuted as oil is added to the vessel to prepare the emulsion;

(3) The water-emulsifier exterior phase is added to a vessel and the coal added thereto is comminuted in situ so that the coal particles are thoroughly wetted with the water-emulsifier mixture. Thereupon, oil is added to the water-emulsifier-comminuted coal system with mixing to form the coal-loaded emulsion;

(4) Coal was thoroughly wetted with the water-emulsifier system and the oil phase was added thereto as the coal is comminuted to yield a coal-loaded non-settling emulsion.

(5) Processes combining features of the above 4 processes.
The comminuted coal employed may be any size which can be prepared into the emulsions of this invention such as about 1/4" or less, for exampler about 1/8" or less, but preferably about 14 to 16 Mesh or less with an optimum of ?, ~, 6 9 about 30 Mesh or less, including as low as 200 Mesh. The particular size will depend upon the type of coa~ avail-able, the system in which it is to be used, the available equipment, etc.
The amount of coal in the emulsion may be at least about 30% by weight, such as at least about 40%, for example at least about 50%, but preferably at least 40 with an optimum of about 50-60~.
The oil employed may be any of the substances which are practically insoluble in water. These include the animal oils of both land and marine animals; vegetable oils, petroleum or mineral oils of various classes including those of open chain hydrocarbons, cyclic hydrocarbons or cycloparaffins; resin oils and wood distillates; various oils obtained from petroleum pro-ducts such as gasolines, naphthas, gas fuel, lubricating~
residual, and heavier oils; coal distillate inc~uding benzene, toluene solvent naphtha, cresote oil and anthracene oil and coal tar.
In the preferred embodiment the coal is substantially wetted with the water-emulsifier system before or during comminution and the oil phase added thereto to form the coal-loaded emulsion.
A wide variety of emulsifiers can be emplo~ed in preparing the slurries of this invention including cationic, anionic, nonionic, ampholytic or combinations thereof, such as for example the emulsifier described in U.S.P. 3,732,16~. The preferred type of emulsifier is nonionic.
The emulsifier employed in the following examples is described in Emulsifier Example 1.

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Emulsifier Example 1 The emulsifier used is a blend of three o~yalkylated compounds, The first compound (1) is an oxyethylated dinonylphenol using ~.29 weights of ethylene oxide per weight of dLnonylphenol. The second compound (2) is an oxyalkylated linear alkyl chain C-8 to C-10 alcohol using 1.0 weights of propylene oxide and then 2.0 weights of ethylene oxide per weight of alcohol. The third compound (3) is an oxyalkylated butylphenol formaldehyde resin using 80~0 weights of propylene oxide and then 80.0 weights of ethylene oxide per weight of resin. These compounds are blended with water using 80 wt % water and 20 wt % emulsifier blend which is 31.5 wt % compound (1), 37.7 wt % compound (2) and 30.8 wt % compound (3).
The following examples are presented by way of illus-tration and not of limitation.

Example A
The following example illustrates the preparation of a coal-water slurry (i.e., non-emulsion slurry).
A mixer, a jacketed, high speed impeller-grinder, was used. First a mixture of coal and No. 6 residual fuel oil was produced. Thirty five pounds of oil were introduced into the mixer and with the lid closed and the impeller running, 35 pounds of Illinois coal were added in about two minutes, and the mix allowed to grind for 10 minutes with the temperature reaching about 160F. resulting in a fluid gritty slurry. However, the coal solids settle out rapidly and within two hours most of the coal had settled.

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i i ~ rJ ~ r~ y Example B
Using the same equipment and operatlng procedure of Example A, emulsions containing the coal were prepared.
Emulsifier and water were firs-t placed in the mixer using 1.75 pounds of emulsifier and 4.~5 pounds water. Approx-imately 5 pounds of residual fuel oil was added until the total liquid level reached the mixer impeller. The lid was then closed and the mixer started. The remaining -approximately 24 pounds of xesidual oil was then added 1~ through a port while the mixer was running producing an 80/20 oil-in-water emulsion. The Illinois coal was then added, 35 pounds, and -this mixture ground for 10 minutes. A
non-settling emulsion containing 50% by wt coal was produced.

Example C
Using the same procedure as Example A, another slurry emulsion was produced using 0.875pounds emulsifier, 2.625 pounds water, 31.5 pounds of residual oil and 35 pounds of coal. Resulting mixture was a non-settling emulsion containing 50% by weight coal.

Example D
The procedure of Example A was repeated using 0.4 pound emulsifier, 3.1 pounds water, 31.5 pounds of cGal tar and 35 pounds coal. The resulting mixture was a non-settling emulsion containing 50% by weight coal and 45% by weight coal tar.
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Example E
Another mixture was produced according to the follow-ing procedure. Emulsifier, 0.4 pounds, and water, 3.1 pounds, were mixed and l pound of this water-emulsifier blend was placed in a twin-cone blender with 35 pounds of coal and tumbled 'or one hour, -thoroughl~ wetting the coal. ~his wetted coal and the remaining 2.5 pounds of emulsifier-water mixture were loaded into the mixer of Example A and 31.5 pounds of residual fuel oil were added while the mixer was running. This mixture was mixed for lO minutes with the temperature being held to 120 with cooling water. The resulting mixture was a non-settling emulsion containing 50~ by weight coal and 45~ by weight residual oil.

Ex mple F
Another procedure for producing these coal slurry emulsions was as follows: The coal was weighed into a container and the required amount of emulsifier-water mixture added and thoroughly mixed with the coal until the coal was completely wetted at which time the fuel oil or coal tar was added and mixed with the wetted coal producing non-settling coal/fuel oil or coal/coal tar emulsions.

The following table is a summary of emulsified coal formulations.

3 ~ 9 m Ln ~ o Ln U ~
r-( I I ~n l ~r ~r l l ~ l~ ~r In In r-l O l~') 11'1 m r~ I I Ln ~ I I ~) N I
. . ~ ~D ~ m In u~
O O ~ Ln r l I Ln I I
~1 n It t o I In I In ~q ~1 I ~) I ~ I ~
Ln ~ ~ ~t) ~ cq . Ln u~
co O u~ In a) .. ~ ~r Ln I I I ~r ~ ~ I I ~ ~ m U~ Ln O Ln Ln m ~ . .
Ln I I q~ I r J ~ I I ~ I al .
~D .
S
I I O IO I ~CO I It~ IO~
D ~ r l Ln trl tq .
u~I I ! I ~ I I 1~ o~ I Ln ~D ~r ~1 Ln ~t .
a~ ~ O O , u~ .1 1` 1 100 In ; ~ ~ ¢ ~ Ln tV7 h I I o o I I ,¢ In I ~ I co I In ~ ~ ~ Ln .
I o I o ~ r I~ I I I oo Ln ~D ~ r l n ~ ~
. ., r-l O O ~ r` 0:~ In ~D I I ~ I I ~'C . 'I Ln I I ~ I m u~ ~q . . ~ .
a . r l ~ ~r O O
~_) C.) ~1 ' ~ ~1 0 0 a~ ~rl Ql r/:1 O r~1 0 W lU
r-l ~ -IJ * ~1 ~ ~ * Id Id ) Ul r~~1 ~) 1~ a) U~~I S l . O ~ 1 o ~1 ~
~ m a ~ u a ~
F4W 0 ~ r l~rl --1 a) ~ ~ ~1 ~1 ~1) ~ ~, a.J tn ~r-l 0 ~ tD 0 al ~1 U~
~1~!) O ~~1 ~ ~ al o i~ r l ~ (13 U ~
~ 5 e ~ ~ ~ ~ e a) u~
r~ 1 ~ Q)r-l ~) ~ rl ~ ~ r-l m r-l ~rl E~ Ul ~ U r-l m r~ l Lû ~ Ot~
~ X S-J ~ h ~ ~ # h a)S l rd O O
e ~ e = I ~ h C.) Z;
~ 00 er ~ ~ ~ e ~ ~ 0 X ~ ~ t~ O ~ (~ ~X ~ r-l ~ O ~D ~ ~ ~ m rS~, _I ~ U ~ X 3 U W r~ #: ~ U X 3 ~ *

3 ~ 9 The emulsions of this invention have a high internal oily phase and a low external non-oily phase. High internal phase ratio emulsions have been described in the following patents and the materials and methods disclosed therein may be employed in practicing the present invention:

U.S.P. 3,343,599 METHOD OF REDUCING THE POROSITY OF
SUBTERRANEAN POROUS FORMATIONS

U.S.P. 3,352,109 HYBRID THIXOTROPIC ROCKET AND JET FUELS
COMPRISING OIL IN WATER EMULSIONS

U.S.P. 3,378,418 METHOD OF RESOLVING THIXOTROPIC JET AND
ROCKET FUEI, E'MULSIONS
U.S.P. 3,396,537 HYBRID FUEL II
U.S.P. 3,490,237 THIXOTROPIC OIL-IN-WATER EMULSION FUELS
U.S.P. 3,523,826 PROCESS OF CLEANING PIPING SYSTEMS
U.S.P. 3,539,406 ESSENTIALLY NONAQUEOUS EMULSIONS

U.S.P. 3,565,817 CONTINUOUS PROCESS FOR THE PREPARATION
OF EMULSIONS

U.S.P. 3,613,372 METHOD OF PROVIDING POWER WITH
ESSENTIALLY NONAQUEOUS EMULSIONS
U.S.P. 3,617,095 METHOD OF TRANSPORTING BULK SOLIDS
Since the particles of coal are packed into the emulsion structure, it is difficult to state whether the coal, which is preferably water wetted, is part oE the aqueous phase or suspended in an emulsion but not a part thereof. We do not wish to be bound by theoretical considerations as to the type of emulsion provided the emulsion possesses the desired characteristics of the present invention. Regardless of the type of emulsion, hy in situ comminution, the particles of coal are dispersed and 3 ~; ~3 packed into the emulsion so as to form "fluid coal"
possessing the characteristics of the present invention.
The coal slurries of this invention can be burned in blast furnaces, in turbine engines, in magneto hydro-dynamic generators, in direct firecl boilers, as well as in other combustion systems. At prPsent prices the cost savings of a 50% by weight coal/oil slurry is approximately as follows:
(1) Residual oil = $2.00/million BTU
(2) Residual oil ~ coal = $1.43/million BTU.

Use Example The coal slurry emulsion of Example E was stored for approximately 2 weeks without evidence of settling.
The slurry emulsion was then circulated and heated to 160F for two hours while being injected into one lance of a blast furnace. After injection, the feed lines and lance showed no evidence of plugging or coking and operation of the blast furnace was satisfactory~
Similarly the slurry emulsions can be utilized in firing steam boilers, turbines and other direct fired combustion systems as well as in magneto hydrodynamic generators wherein the suspended solids will assist in developing highly ionized gases used for increased generator efficiency.

Claims (11)

The embodiments of the invention in which an exclusive pro-perty or privilege is claimed are defined as follows:

1. A process of preparing a non-settling coal-containing emulsion which comprises adding coal, in an amount of about 30% to about 60% by weight, to a high internal phase ratio emulsion or during the preparation of a high internal phase ratio emulsion, said emulsion comprising an emulsifying agent, an emulsifiable oil and water, said water being the external phase, and comminuting the coal in situ.

2. The process of claim 1 where the coal is substantial-ly wetted with a water-emulsifier system before and during the comminution.

3. The process of claim 1 or 2 where the high internal phase ratio emulsion is an 80-20% by volume oil-in-water emulsion

4. The process according to claim 1 wherein a stabilized fuel slurry is prepared, the emulsifiable oil is liquid fuel oil, the liquid fuel oil is present in the range of from about 32% by weight to about 45% by weight, solid fuel particles with diameters as large as about 1/4 inch are present in the range of from about 30% to 60% by weight, water is present in the range of from about 4.5% to about 5% by weight and an emulsi-fier capable of forming a thixotropic water external-oil high internal phase emulsion is present in the range of from about 0.5% to 5%, and the process comprises providing a liquid fuel oil, adding an emulsifier and solid coal particles and water to the liquid fuel oil, agitating the solid coal particles with the water, the liquid fuel oil and the emulsifier to form a thixotropic water external-high internal phase emulsion and to comminute the solid coal particles, whereby a stabilized fuel slurry having solid coal particles with diameters as large as about 1/4 inch is formed.

5. The process of preparing a stabilized fuel slurry according to claim 4 wherein the liquid fuel is a petroleum oil.

6. The process of preparing a stabilized fuel slurry according to claim 4, wherein the liquid fuel oil is coal tar.

7. The process of preparing a stabilized fuel slurry according to claim 4, wherein said coal particles are comminuted until the largest of said particles is no larger than about 1/8 inch in diameter.

8. The process of preparing a stabilized fuel slurry according to claim 4 wherein the slurry is maintained at a temperature above about 100°F during the mixing of the liquid fuel oil and the emulsifier and the solid fuel particles

9. The process of preparing a stabilized fuel slurry according to claim 4 having a petroleum present in the range of from about 32% by weight to about 45% by weight, coal par-ticles with diameters as large as about 1/4 inch present in the range of from about 30% by weight to about 60% by weight, water present in the range of from about 4.5% to about 5% by weight, and an emulsifier capable of forming a thixotropic water external-oil high internal phase emulsion present in the range of from about 0.05% to 5%, said process comprising providing a liquid petroleum oil, adding an emulsifier and water to the petroleum oil, mixing the petroleum oil and the emulsifier and the water for a period of at least 1 minute to form the thixotropic water external-oil high internal phase emulsion, adding coal particles to the emulsion, and mechanically mixing the emulsion and the coal particles for a period of time of about 10 minutes to comminute the coal particles and to form a stabilized slurry having coal particles with diameters as large as about 1/4 inch.

10. A method of preparing a stabilized fuel slurry having liquid fuel oil present in the range of from about 32%
by weight to about 45% by weight, solid fuel particles with diameters as large as about 1/4" present in the range of from about 30% by weight to about 60% by weight, water present in the range of from about 4.5% by weight to about 5% by weight and an emulsifier capable of forming a thixo-tropic water external-oil high internal phase emulsion present in the range of from about 0.5% by weight to about 5% by weight, said method comprising adding solid fuel to a high internal phase ratio emulsion or during the prepara-tion of a high internal phase ratio emulsion, agitating the mixture to form a thixotropic water external-oil high internal phase emulsion and to comminute the solid fuel particles, to form a stabilized fuel slurry having solid fuel particles with diameters as large as about 1/4 inch.

11. A method of preparing a stabilized coal slurry com-prising adding solid coal to a high internal phase ratio emulsion or during the preparation of a high internal phase ratio emulsion, agitating the mixture to form a thixotropic water external-oil high internal phase emulsion and comminuting the coal in situ.