US20080148626A1 - Multiple polydispersed fuel emulsion - Google Patents

Abstract

Multi faceted technology for the combustion and transportation of emulsified hydrocarbon fuel. The fuel comprises a composite of a plurality of hydrocarbon in water emulsions. The composite emulsion has a unimodal hydrocarbon particle distribution, with the hydrocarbon being present in an amount of between 64% and 90% by volume.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This is the first application filed for the present invention.
TECHNICAL FIELD
• The present invention relates to a hydrocarbon emulsion formation where the emulsion has a plurality of particle modal distributions and further relates to a method of transporting the emulsion.
BACKGROUND OF THE INVENTION
• Emulsified hydrocarbon fuels have become increasingly important as a useful fuel for steam generation in power plant and other steam raising facilities to replace coal and petroleum coke, has environmental drawbacks, and natural gas which is relatively more expensive. The high cost of natural gas has particular ramifications in the petroleum processing art and specifically in the steam assisted gravity drainage technique (SAGD) as related to the production of heavy oils and natural bitumens. As is known, the SAGD and congener techniques require the use of steam turbines for injecting steam into a subterranean formation to mobilize highly viscous hydrocarbon material. Conventionally, natural gas has been used to fire the steam generators, however, this is unattractive from a financial point of view and has other inherent drawbacks. With the advent of emulsified hydrocarbons, especially those manufactured from hydrocarbons or their products from indigenous hydrocarbon production, it has been found that the heat content is adequate to burn in a steam generation environment.
• One of the first pioneering fuels in this field was Orimulsion, manufactured in Venezuela by Bitor, and shipped worldwide to supply power generation plants. Building on the success of Orimulsion, other emulsified fuels have been developed such as MSAR™ (Multi-Phase Superfine Atomized Residue), by Quadrise Ltd. and now further developed by Quadrise Canada Fuel Systems, Inc. MSAR™ is an oil-in-water emulsion fuel where the oil is a hydrocarbon with an API gravity between 15 and −10. Typical oil-water ratios lie in the range 65% to 74%. Because of the presence of oil droplets in water, MSAR™ is essentially a pre-atomized fuel. This means that the burner atomizer does not do mechanical work to produce oil droplets, as in conventional fuel oil combustion, but that it is the emulsion manufacturing equipment that produces the oil droplets. Pre-atomization literally means ‘before the atomizer’ and so the MSAR™ manufacturing equipment is essentially the atomizer of this process. Typical mean droplet size characteristics of MSAR™ are around 5 microns, whereas typical mean droplet size characteristics produced during fuel oil atomization in a burner atomizer are between 150 and 200 microns. Therefore, the enormous increase in surface area brought about by producing much smaller droplets in the MSAR™ production process, compared with a conventional burner atomizer, leads to much more rapid and complete combustion, despite the fact that there are significant quantities of water present. In addition, when MSAR™ passes through a conventional atomizer, as it must do in order to be combusted, 150-200 micron water droplets containing the 5 micron oil droplets are formed. Water therefore finds itself located in the interstitial zones between each assembly of oil droplets. This interstitial water, between the oil droplets, spontaneously vaporizes and this leads to further break-up of the already small (5 micron) droplets. This process is known as secondary atomization. Because of this secondary atomization and the earlier described pre-atomization, MSAR™ has been found to be a particularly effective fuel, with a carbon burnout rate of 99.99%. Carbon burnout is obviously an important aspect of any combustion process and the fact that MSAR™ carbon burnout is so high, substantially reduces the amount of carbon coated ash that collects in the burner and/or furnace. As is known, if the carbon burnout is low, then carbon will deposit with ash on boiler surfaces and will effectively lead to the production of coke; this leads to inefficiencies and/or inoperability in the overall process. By providing a 99.99% carbon burnout rate, these problems are obviated.
• Whilst the extremely small droplet size associated with MSAR™ has distinct advantages for the combustion process, it has disadvantages for the handling and pumping processes because the smaller the droplets, the more viscous the MSAR™. Therefore, in order to further advance emulsion fuel technology, present research, conducted by other organizations, has developed means by which the extremely small droplet size can be maintained whilst simultaneously reducing viscosity leading to improvements in storage, handling and transportation generally. Consequently, research has gone in the direction of bimodal emulsions, i.e. emulsions which have two distinct droplet size peaks in their droplet size profile.
• This is reflected in, for example, U.S. Pat. No. 5,419,852 issued May 30, 1995 to Rivas, et al and U.S. Pat. No. 5,503,772, issued Apr. 2, 1996 to Rivas et al, inter alia. In these references, specific blends of independently produced and discretely different characteristic emulsions are used to describe the invention. The conclusion is made that the bimodal emulsions can be prepared to reduce viscosity and illustrate that the final emulsion is distinctively bimodal in its physical characteristics.
• Although it is desirable to have a bimodal emulsion, this technology is not without limitation. It is known in the art that the larger the average particle size is, the lower the viscosity of the mixture. Unfortunately, the larger the particles in an emulsified fuel, the greater the length of time it takes for the oil droplet to combust and travel down the furnace which results in the requirement for a longer furnace. In the event that the furnace is of an insufficient length for the selected fuel, then unburnt hydrocarbon material and/or smoke become undesirable attributes. In this manner, the existing technology is limited by the equipment used which can add costs, complications and other problems related to pollution in the overall process.
• Given the state of the art, it has now been recognized that the viscosity drives the overall system towards bigger oil droplets in the fuel, while the combustion results in the driving of the system towards smaller oil droplets. Accordingly, it would be desirable to have a formulation that results in the change in the particle size distribution of the fuel emulsion to reduce viscosity, but also to improve combustion. These latter two properties are most desirable to provide a very efficient high enthalpy emulsified fuel. Having the formation of an emulsion with the above noted properties as a goal, a novel approach was taken to resolve these properties into an emulsion.
• It was found particularly effective to look at the packing of particles in the prior art and adopt this technology. This approach had not previously been applied to the field of emulsions for the purpose of generating a composite emulsion having the most desirable properties, namely a broad particle distribution composed of n-modal distributions, but maintaining, as far as is practically possible, the n-modal distributions as a single peak or unimodal distribution.
• Representative of the particle packing references was gleaned from the Journal of Computational Physics 202 (2005), 737-764, and particularly an article entitledNeighbor list collision-driven molecular dynamics simulation for non-spherical hard particles. I. Algorithmic details. A general algorithm for a system of particles having relatively small aspect ratios with small variations in size. The article was authorized by Donev et al. A further article by the same author entitled,Neighbor list collision-driven molecular dynamics simulation for non-spherical hard particles. II. Applications to ellipses and ellipsoids, Journal of Computational Physics 202 (2005), 765-793, was also reviewed. Other general references in the spherical packing technology include: the articleModeling the packing of granular media by dissipative particle dynamics on an SGI Origin2000,using DL_—POLY with MPI, Elliott et al;Packing and Viscosity of Concentrated Polydisperse Coal-Water Slurries, Veytsman et al,Energy and Fuels1998, 12, 1031-1039;Is Random Close Packing of Spheres Well Defined? Physical Review Letters, 6 Mar. 2000, Torquato et al.; andThe random packing of heterogeneous propellants, KNOTT et al.
• In view of the prior art in the emulsion field, there still exists a need for an emulsion which facilitates changes in particle size distribution of the fuel emulsion to reduce viscosity, but also one which has improved combustion and does not lead to poor carbon burnout. The technology herein provides for burn optimization of the emulsion.
• By applying the packing models from solid fuel to the instant technology, it was found that the wider the particle size distribution, the lower the viscosity of the emulsion.
• The present invention has now collated the most desirable properties for a fuel emulsion where the final emulsion is effectively a composite emulsion of at least two precursory emulsions and which composite emulsion provides for a unimodal distribution, i.e. a single peak, emulsion as opposed to bimodal distribution which is exemplified in the prior art. Unimodal as used herein, refers to a majority peak with the potential for shoulders, but absent discrete peaks.
• The present invention has successfully unified unrelated technologies to result in a particularly efficient composite fuel emulsion.
SUMMARY OF THE INVENTION
• One aspect of the present invention is to provide a substantially improved atomized fuel emulsion, which emulsion is a composite fuel emulsion having very desirable burn properties, calorific value and which can be custom designed for burning in any furnace or burning arrangement which is vastly different from the prior art.
• According to a further aspect of one embodiment of the present invention, there is provided an emulsified hydrocarbon fuel, comprising a composite of a plurality of hydrocarbon-in-water emulsions, the composite emulsion having a unimodal hydrocarbon particle distribution, the hydrocarbon being present in an amount of between 64% and 90% by volume.
• As noted herein previously with respect to the prior art, high oil content in the oil-in-water emulsion has been recognized previously, however, the emulsion formed in the prior art is bimodal. By making use of the instant technology, not only is the hydrocarbon content exceedingly high, but the viscosity is reduced for the overall system relative to the independent viscosities of the precursor emulsions forming the composite and further, the carbon burnout rate is particularly attractive at greater than four nine effectiveness.
• The precursor emulsions may contain the same hydrocarbon material or different hydrocarbon materials depending upon the specific use of the emulsion. In addition, the particle size distributions and droplet size may be the same or different. In the instance where the size distributions are the same, the hydrocarbon material will be different in the discrete emulsions. As a further possibility, the composite emulsion may be a composite emulsion combined with a hydrocarbon in water emulsion. Similar to that noted above, the composite emulsion and hydrocarbon in water may comprise the same or different hydrocarbon material, same or different droplet size and/or the same or different particle size distribution.
• According to a further aspect of one embodiment of the present invention there is provided a method of formulating a composite emulsion made from different hydrocarbon materials which possess widely differing viscosities and therefore widely differing emulsion preparation temperatures. Consequently, the precursor emulsion which is made at the lower temperature can be used as a cooling agent when mixed with the precursor emulsion which is made at the higher temperature. This obviates or reduces the need to use heat exchangers to reduce the temperature of emulsions which are made above 100 deg C. to below 100 deg C. prior to storage.
• According to a further aspect of one embodiment of the present invention there is provided a method of formulating a composite emulsion having unimodal particle distribution with reduced viscosity relative to precursor emulsions used to form said composite emulsion: providing a system having an n-modal particle distribution; forming a precursor emulsion for each n-modal distribution present in the system, each precursor emulsion having a characteristic viscosity; and mixing precursor emulsions to form the composite emulsion with a unimodal size distribution and reduced viscosity relative to each precursor emulsion.
• As briefly discussed herein previously, it has been found that by making use of the composite emulsion, the same has a viscosity which readily facilitates transportation, despite the high content of hydrocarbon material present in the emulsion. It is believed this is due to the unimodal particle size distribution which, inherently provides a broader spectrum of particle sizes. This, in turn, commensurately provides advantage in mixture viscosity.
• A still further aspect of one embodiment of the present invention is to provide a method for transporting viscous hydrocarbon material comprising: providing a source of hydrocarbon material; generating a plurality of emulsions of the hydrocarbon material, each emulsion having a characteristic viscosity, each emulsion having a different particle size distribution; mixing the plurality of emulsions in a predetermined ratio to form a composite emulsion having a lower viscosity relative to the plurality of emulsions; and mobilizing the composite emulsion.
• A still further aspect of one embodiment of the present invention is a method of maximizing viscous hydrocarbon content in an aqueous system for storage or transport, comprising: providing a hydrocarbon emulsion having a hydrocarbon internal phase volume sufficiently high such that the droplets in the emulsion are aspherical; converting the emulsion at least to a bimodal emulsion system; forming at least two precursor emulsions from the system; mixing the precursor emulsions in a predetermined ratio to effect reduced viscosity; and synthesizing a composite emulsion from the precursor emulsions having the reduced viscosity.
• A still further aspect of one embodiment of the present invention is a method of formulating a composite emulsion having unimodal particle distribution with reduced viscosity relative to precursor emulsions: providing a system having an n-modal particle distribution; forming a precursor emulsion for each modal distribution present in the system; each the precursor emulsion having a characteristic viscosity; forming a plurality of composite emulsions each having a unimodal size distribution and reduced viscosity relative to each the precursor emulsions; and mixing the composite emulsions to form an amalgamated composite emulsion having a unimodal particle distribution and reduced viscosity relative to the viscosity of the composite emulsions.
• In accordance with another beneficial aspect of one embodiment of the present invention, it was found that the HIPR (High Internal Phase Ratio) emulsions, which have extremely high hydrocarbon material content in the emulsion, could also be transported efficiently. By making use of the high internal phase ratio emulsion, it was discovered that these emulsions can be converted to at least a bimodal or n-modal emulsion system depending upon the number of particle size distributions within the HIPR emulsion and then these individual bimodal emulsions could be formed into precursor emulsions and mixed to form a composite emulsion in accordance with the methodology previously discussed herein. In this matter, aspherical or substantially non-spherical oil in water particles can be reconfigured or converted into discreet modes for individual emulsion synthesis with subsequent mixing for composition of a more favorably transportable composite emulsion. This has particular utility in permitting mobilization of high hydrocarbon content material without expensive unit operations conventionally attributed to processes in the prior art such as pre-heating, the addition of diluents or other viscosity reducing agents. The material can simply be converted, to a composite emulsion and once so converted, inherently has the same transportation advantages of the composite emulsions discussed herein previously.
• A method of modifying at least one of the combustion, storage and transportation characteristics of an emulsion during at least one of pre-formation, at formation and post formation, comprising: providing an emulsion; treating the emulsion to a unit selected from the groups consisting of additive addition, mechanical processing, chemical processing, physical processing and combinations thereof; and modifying at least one characteristic of the characteristics of the emulsion from treatment.
BRIEF DESCRIPTION OF THE DRAWINGS
• Having thus generally described the invention, reference can now be made to the accompanying drawings illustrating preferred embodiments and in which:
• FIG. 1 is a schematic illustration of the overall synthesis mechanism of the instant technology;
• FIG. 1A is a schematic illustration of a variation in the overall synthesis mechanism of the instant technology;
• FIG. 2 is a graphical illustration of particle size as a function of shear;
• FIGS. 3A and 3B are graphical illustrations of viscosity as a function of droplet size ratio;
• FIG. 4 is graphical illustration of percentage of oil in the emulsion as a function of further length;
• FIG. 5 is a graphical illustration of two precursors and a composite emulsion of a surfactant in 70% NE Alberta bitumen for a median particle size of 5 μm and 24 μm;
• FIG. 6 is a graphical illustration of the composite emulsion viscosity for varying percentages of the same median particle size;
• FIG. 7 is a graphical illustration of a two modal distribution for North Eastern Alberta bitumen particles with two particle sizes (5 microns and 10 microns);
• FIG. 8 is a graphical illustration of viscosity as a function of the percentage of 5 micron MSAR™ used in the precursory emulsion and percentage of 10 micron MSAR™ used in the second precursory emulsion;
• FIGS. 8A through 8C illustrate particle distributions for composite emulsions formed from the 5 and 10 micron individual emulsions for 5 and 10 micron percentages of 20% and 80%, 50% and 50% and 80% and 20%, respectively;
• FIG. 9 illustrates the individual distributions for a 6micron 12 micron mode where both precursory emulsions are formed using a surfactant and a 70% content of refinery residue;
• FIG. 10 illustrates a viscosity as a function of the MSAR™ mixture composed of 5 microns in the first emulsion and 12 microns in the second emulsion;
• FIGS. 10A through 10C illustrate the result of the particle distribution in the composite emulsions for the 6 and 12 micron particles in the following percentages: 20% and 80%, 50% and 50% and 80% and 20%, respectively;
• FIG. 11 is a graphical illustration of the precursors whereemulsion number1 comprises 6 micron median particle size distribution and emulsion to a 16 micron median particle size distribution;
• FIG. 12 is a graphical representation of the viscosities of the MSAR™ mixtures composed of 6 micron and 16micron 80/100 Asphalt MSAR™;
• FIGS. 12A through 12C illustrate varying percentages of 6 micron and 16 micron particles, namely 20% and 80%, 80% and 20%, and 50% and 50%, respectively;
• FIG. 13 is front view of a burner where the illustration is of a North Eastern Alberta bitumen MSAR™ fuel number1 being combusted;
• FIG. 14 is a side view of the flame illustrated inFIG. 13;
• FIG. 15 is an illustration of the coke deposits on the nozzle subsequent to the combustion of the fuel being burned inFIGS. 13 and 14;
• FIG. 16 is a view similar toFIG. 15 after a second burning run ofMSAR™ fuel1;
• FIG. 17 is a view of the combustion from the burner of the North Eastern Alberta bitumenMSAR™ fuel2;
• FIG. 18 is a photograph of the nozzle after combustion of theMSAR™ fuel2 illustrating the coke deposit;
• FIG. 19 is a figure depicting the flame generated from the burning of the North Eastern Alberta bitumen MSAR™ composite fuel between theMSAR™ fuel1 andMSAR™ fuel2;
• FIG. 20 is a side view of the flame ofFIG. 19; and
• FIG. 21 is an illustration of the burner nozzle illustrating the minimum deposition of coke on the nozzle.
• It will be noted that throughout the appended drawings, like features are identified by like reference numerals.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
• Referring now toFIG. 1, shown is the overall synthesis mechanism globally denoted bynumeral10. The synthesis mechanism includes two broad steps denoted bynumerals12 and14. Instep12, ahydrocarbon material16 is mixed withwater20 containing asurfactant18 and the material, as a mixture, is mixed in amixing device22.
• The hydrocarbon material may comprise any hydrocarbon material fuel, non limiting examples of which include natural gas, bitumen, fuel oil, heavy oil, residuum, emulsified fuel, multiphase superfine atomized residue (MSAR™), asphaltenes, petcoke, coal, and combinations thereof. It is desirable to employ hydrocarbon material of less than 18 API. The use of an emulsion stabilizer (a chemical composition which presents premature phase separation of the emulsion), stabilizes phase separation. The surfactants are useful for this as well as a host of other members in the class of stabilizers.
• In terms of the surfactants, it is well known in this art that the surfactants may be non-ionic, zwitterionic, cationic or anionic or mixtures thereof. Further, they may be in a liquid, solid or gaseous state. It is well within the purview of the scope of this invention to use combinations of materials to achieve a properly dispersed system normally attributable to emulsions.
• The mixer may comprise any suitable mixer known to those skilled in the art. Suitable amounts for the emulsion stabilizer or surfactant comprise between 0.01% by weight to 5.0% by weight of the emulsion with the hydrocarbon comprising any amount up to 90% by weight. In the example, a mixer such as a colloidal mill, is used. Once the materials are subjected to the colloidal mill afirst precursor emulsion24 is generated. Similar steps are effected to result in the secondprecursory emulsion24′, with common steps from the preparation of emulsion one being denoted by similar numerals with prime designations.
• Onceprecursor emulsion24 and thesecond precursor emulsion24′ are formed, the two are introduced into amixing device26 which may comprise a similar shear apparatus as the colloidal mill or more likely a further selected device such as an in-line static mixer.
• In theindividual emulsions24 and24′, one of the emulsions will have a smaller average particle diameter relative to the second emulsion. These are then mixed together in a predetermined ratio to form thecomposite emulsion28 which is a multiple polydispersed fuel emulsion. The preset ratio can be determined by making use of a particle packing algorithm such as that which has been set forth in the discussion of the prior art. The use of this algorithm was previously applied to solid based rocket fuels and by making use of the algorithm in the synthesis of a composite emulsion, a very successful result has been encountered. One of the particularly attractive results is that the composite emulsion has a viscosity that is less than the viscosity of the precursor emulsions by a factor of between 3 and 5 times the viscosity of the precursor emulsion containing the small droplets. A further advantage that flows from this unification of unrelated technologies is the requirement for lower preheat temperatures in the composite emulsion as opposed to those preheat temperatures required for the previous or precursor emulsions.
• Conveniently, the composite emulsion also has been found to have much improved dynamic and static stability and handling (anything in-between manufacture and burner tip, e.g. storage, valves, pipes, tanks, etc) characteristics and therefore easier storage and transportation possibilities. In burn testing, the composite emulsions provided greater than 99.99% carbon burnout, despite the fact that the emulsion contained a high percentage of the hydrocarbon material in water.
• Referring now toFIG. 1A, shown is a variation of the overall arrangement shown inFIG. 1. In this embodiment, the process may be modified at various stages to effect the transportation storage and/or combustion of the individual components within the emulsions or the composite emulsion itself. In this manner,FIG. 1A provides for modification of at least one of the above noted aspects by modification at the pre-synthesis mixing point prior to the surfactant and water entering themill22 as denoted by numeral30 or as a further option by modifying the hydrocarbon prior to introduction to the mill, this step being indicated bynumeral32. As a further possibility, the emulsion may be modified at the point of fabrication, denoted by numeral34 or subsequent to formation at36. In respect of similar numerals with prime designations, these steps apply toemulsion number2 designated by numeral24′. As a further possibility, once thefirst emulsion24 andsecond emulsion24′ are introduced, they may modified atmixer26 denoted by numeral38 or subsequently modified once thecomposite emulsion28 has been formed. This step is denoted bynumeral40.
• By the variation in this process as depicted byFIG. 1A, the emulsion may be modified in terms of combustion, storage and/or transportation characteristics during at least one of pre-formation, at formation and post formation where the modification involves a unit operation selected from at least additive addition, mechanical processing, chemical processing and physical processing, as well as combinations thereof. The additive addition will be discussed herein after.
• Referring now toFIG. 2, shown is a schematic graphical illustration of particle size as a function of the amount of shear. This permits the selection of different particle size distributions for the emulsions by changing the amount of shear used to make particles for the emulsion. It is known that the amount of shear is related to the average particle size and width of distribution as shown inFIG. 2. The lowest droplet size is related to the parameters used to formulate the emulsion. The shear amount is increased by increasing the residence time in the mixing device, or increasing the speed at which the rotatable mixing device rotates.
• It has been found that it is convenient to maintain the surfactant concentration relative to the oil content as substantively the same for precursor emulsions for purposes of stability. This is exemplary only, variations in the concentration of the surfactant can occur depending upon the final desired characteristics for the composite emulsion. In situations when different surfactants are used for different composite emulsions, the surfactants will, for course, be compatible. The examples have been discussed previously and other examples will be apparent to those skilled.
• Referring now toFIGS. 3A and 3B, shown are schematic graphical illustrations of viscosity as a function of a ratio of small droplets versus big droplets with the larger droplets being represented on the left hand side of the graphs.
• Referring now toFIG. 4, shown is a schematic illustration of the percent of the oil content in the emulsion as a function of the length of furnace required to completely burn the fuel.
• Referring now toFIG. 5, shown is pre-mix particle distributions for a bimodal system where numeral1 represents an emulsion containing surfactant with 70% North Eastern Alberta bitumen with the balance comprising water. The first distribution was formulated using a high shear mixer at a high revolution. The median particle size in this distribution was 5 microns whereas indistribution number2, the median particle size was 24 microns. In the premix it is evident that each emulsion possesses a distinctly different mean and median droplet size.
• FIG. 6 is a graphical representation of viscosity as a function of percentage of 5 micron MSAR™ emulsion and 24 micron MSAR™ used in the mixture. InsetFIG. 6A is a distribution representation for a 20% 5 micron and 80% 24 micron mixture having a characteristic viscosity indicated by the arrow in the graph ofFIG. 6, whereasFIG. 6B is an inset where the mixture or composite emulsion contained 80% 5 micron particle size and 20% 24 micron particle size with the arrow pointing inFIG. 6 to the characteristic viscosity. Finally, insetFIG. 6C depicts a 50/50 blend of 24 micron and 5 micron particles with the characteristic of viscosity being indicated by the arrow. From a review ofFIGS. 6A through 6C, it is evident that the particle distribution representations are effectively unimodal despite containing two individual emulsions which independently possess distinctly different mean and median droplet sizes.
• As a further representation,FIG. 7 provides a North Eastern Alberta bitumen particle distribution where there is a greater degree of overlap between the two modal distributions in view of the median particle size. In this representation, similar materials were used with respect to the previous discussion with the 5 micron median particle distribution being represented by numeral1 which occurred at a relatively high speed, whereaspeak2 comprises medial particle distribution of 10 microns which was created at a lower speed. This is an example; mixing can occur in a low and high intensity mixer with the rpm selected based on final requirements.
• FIG. 8 illustrates a viscosity as a function of the percentage of 5 micron MSAR™ used in the precursory emulsion and percentage of 10 micron MSAR™ used in the second precursory emulsion. Insets8A,8B, and8C illustrate particle distributions for composite emulsion formed from the 5 and 10 micron individual emulsions for 5 and 10 micron percentages of 20% and 80%, 50% and 50%, and 80% and 20%, respectively. Individual arrows from each of insets8A through8C are representative of the viscosity of the individual final composite mixtures of insets8A,8B and8C.
• InFIG. 9, a further hydrocarbon material was employed for synthesizing the composite emulsion.FIG. 9 illustrates the individual distributions for a 6 micron and 12 micron mode where both precursor emulsions were formed using a suitable surfactant and a 70% content ofrefinery tank9 with a balance of water. The contents of the refinery residue are approximately 10% gas oil and 90% viscous hydrocarbon material. The 6 micron distribution was generated at a relatively high speed, whereas the 12 micron was generated at a lower speed.
• FIG. 10 illustrates the viscosity as a function of the MSAR™ mixture composed of 5 microns in the first emulsion and 12 microns in the second emulsion.FIGS. 10A through 10C illustrate the results of the particle distribution in the composite emulsion for the 6 and 12 micron particles in the following percentages: 20% and 80%, 50% and 50% and 80% and 20%, respectively.
• As is evident from the inset illustrations, each has a characteristic viscosity indicated on the graphical representation ofFIG. 10. Further, similar to the previous examples noted, the composite emulsion in all cases is effectively unimodal and accordingly provides a broad particle size distribution.
• FIG. 11 tabulates the characteristics of pre-cursor emulsion whereemulsion number1 comprises 6 micron median particle size distribution and emulsion2 a 16 micron median particle size distribution. In this example, the surfactant was employed as the surfactant with the hydrocarbon material comprising 70% 80/100 Asphalt with the balance being water. The 6 micron distribution was formulated using the mill at a relatively high speed where the 16 micron was synthesized at a lower speed.
• Similar data to the examples presented previously are presented inFIG. 12 where the viscosity is represented. InsetFIGS. 12A through 12C represent specific composite emulsion formulations of 6 and 16 micron distributions in the following amounts: 20% and 80%, 80% and 20%, and 50% and 50%, respectively.
• Once again, the composite emulsion demonstrates a unimodal particle distribution with characteristic viscosities for each of the insets12A through12C.
• From the results, it is evident that the instant methodology results in the desirable formulation of unimodal composite fuel emulsion from discrete precursory emulsions. It is known that the oil content or hydrocarbon material content of oil in water emulsions of the prior art is generally limited to approximately 70% since greater content beyond this point increases the viscosity of the emulsion exponentially. This is clearly contrary to the desired properties that have been achieved with the instant methodology. By making use of the protocol as set forth herein, the oil content can be increased to up to 90% whilst still maintaining relatively low viscosities compared with conventional or HIPR emulsification. It is believed that the packing of the droplets in the multiple polydispersed fuel emulsions set forth herein is significantly better in normal emulsions not presenting unimodal distributions.
• A host of very useful features flow from the use of this methodology not only to make an improved emulsified fuel with higher carbon burnout than the individual emulsions in the composite, but also the lower water requirement for transportation.
• As discussed briefly, one of the major advantages of the instant technology is that HIPR emulsions which are characteristically composed of aspherical particles which are generally polyhedral which can be converted into individual emulsions and then subsequently combined to form a composite mixture having the advantages that flow from the instant technology. In this manner, the HIPR emulsions can be converted to provide the desirable properties of a composite emulsion in terms of having a wider particle distribution with reduced viscosity and improved combustion. It is a well known fact that HIPR emulsions have exceptionally high viscosities, and are very shear thinning. It has not been previously proposed to convert HIPR emulsions into discrete emulsions for a combination such as that which is disclosed herein to provide for reduced viscosity with enhanced combustion. It has not been previously recognized to employ HIPR emulsions which are capable of having a 99.99% carbon burnout rate.
• With respect to convenience of use, the emulsion technology set forth herein allows the emulsion to be designed for the furnace or burning arrangement individually as opposed to having to design a furnace to specifically burn the emulsion. The cost savings on this point are extremely substantial; the modification of the emulsion is obviously a much less involved exercise than having to design and fabricate a new piece of expensive equipment.
• Further, depending upon economics and the requirements for the composite emulsion the precursor emulsions are not limited in number and are well within the scope of the instant technology to provide an n-modal system. The individual emulsions would have to be formulated and then subsequently mixed together to form the composite emulsion as an attendant feature to this aspect of the invention, individual groups of emulsions may be mixed to form composite emulsions and the so formed composite emulsions then further mixed to form an amalgamated emulsion of individual composite emulsions. In terms of bi or multi-modal distributions used to form a composite emulsion, the composite may be reintroduced into a shear or mixing device to form a processed composite emulsion.
• Having now delineated the details of the invention, reference will now be made to the following example:
EXAMPLE
• Three fuel types were examined:
• • 1) North Eastern Alberta bitumenMSAR™ fuel2 with particle size 5.5 μm;
  • 2) North Eastern Alberta bitumenMSAR™ fuel1 withparticle size 22 μm; and
  • 3) 50/50 mixture of North Eastern Alberta bitumenMSAR™ fuel1 andMSAR™ fuel2 with particle size 5-22 μm.
• Experiments began with the fuel having the larger droplet (MSAR™ fuel2).
• A fuel firing rate of 30 kg/h, lower than the normal 36 kg/h, was used to avoid possible fuel plugging since the fuel contained larger sized droplets. The same fuel firing rate was used for the other fuel types to maintain consistency among the conditions.
• The initial temperature for theMSAR™ fuel1 was a fuel temperature of 85° C. and was slowly increased to 100° C., based on the flame characteristics observed.
• Other parameters followed for the protocol were:
• Atomizing air temperature of 108° C.;
• 78-79° C. at burner;
• Combustion air temperature of 108° C.
• O₂6.7, 6.2
• Parameters observed for theMSAR™ fuel2 fuel type were:
• An atomizing air temperature of 84° C.;
• Combustion air temperature of 84° C.;
• A fuel temperature of 65° C.; and
• O₂5.2, 5.3

• TABLE 1
  Properties of MSAR Fuels (wet basis)

  	22 μm		50:50Mixture
  	MSAR
  	5 μm MSAR	(22 and 5 μm)

  Density by Helium Pyrometer	1005	1004	1006
  at 15° C., kg/m3
  Calorific Value, cal/g	6745	7003	6860
  MJ/kg	28.24	29.32	28.72
  BTU/lb	12141	12605	12348
  Water by distillation,wt %	30	30	30
  Carbon, wt %	55.4	59.2	58.5
  Hydrogen, wt %	11.5	11.0	10.5
  Sulphur, wt %	3.29	3.41	3.45
  Nitrogen, wt %	<0.50	<0.50	<0.50
  Ash, wt %	0.051	0.034	0.049

• TABLE 2
  Furnace Operating Conditions and Emission Results

  				50:50 Mixture
  	Natural Gas	22 μm MSAR	5 μm MSAR	(22 and 5 μm)

  Fuel
  Flow rate, kg/h	20		29.69		29.80		29.83

  Thermal input	GJ/h	1.063		0.839		0.874		0.857
  	MMBTU/h	1.007		0.795		0.828		0.812
  	KW	295		233		243		239

  Temperature, ° C.
  At tank outlet	—		52.8		53.0		52.8
  At burner	29.5		78.4		75.3		76.5
  Pressure at burner, kPa	—		96		103		96
  Mean particle size μm	—		22		5		22 &5
  Atomizing air
  Flow rate, kg/h at NTP	39		29		29		25
  Temperature at burner, ° C.	23		97		84		80
  Pressure at burner, kPa	69		21		28		14
  Combustion air
  Flow rate, kg/h at NTP	382		424		433		468
  Temperature at burner, ° C.	33		107		83		88
  Flue gas
  Furnace exit temperature, ° C.	406		393		404		431
  Flow rate, Nm3/MJ of fuel*	0.256		0.364		0.332		0.321
  Particulate loading, g/Nm3	—		0.189		0.124		0.146
  Flue gas analyses, volume basis
  O2, %	3.5	3.5	5.79	3.5	5.2	3.5	4.4
  CO2, %	9.1	12.9	11.20	13.0	11.7	12.9	12.2
  CO, ppm	13	90	78	71	60	46	44
  NO, ppm	64	231	201	344	290	300	284
  SO2, ppm	—	2794	2426	2853	2581	2752	2603
  Flue gas emission, g/MJ of fuel
  NOx	0.022		0.098		0.129		0.122
  SO2	—		2.526		2.452		2.392
  Particulate	—		0.069		0.042		0.047
  Carbon on particulate, wt %**	—		39.2/38.5		33.0/3.4		6.1/2.3
  Particulate concentration, g/g of	—		0.0028		0.0018		0.0019
  fuel
  *Calculations based on stoichiometric combustion and oxygen content of flue gas
  **The carbon result is an estimate only as filter paper was analyzed along with the powder sample

• TABLE 3
  Comparison of Thermal Heat Transfer for Natural Gas andMSAR

  Natural

  	22μm	5 μm	50:50 Mixture
  	Gas	MSAR	MSAR	(22 and 5 μm)

  Fuel
  Thermal input, GJ/h	1.063	0.839	0.874	0.857
  MMBTU/h	1.007	0.795	0.828	0.812
  KW	295	233	243	239
  Thermal heat transfer,kW
  Circuit
  1–10	123.95	116.21	117.38	117.13
  Circuit 11–20	23.11	32.45	27.84	33.05
  Circuit 21–28	1.85	1.62	0.97	1.16
  Total (1–28)	157.91	150.28	146.19	151.94
  Total W/cm2of thermal	1.21	1.16	1.12	1.17
  surface
  Heat transfer rate, kW/MJ	0.149	0.208	0.175	0.171
  of fuel input
  Percent of thermal fuel	53.5	64.4	60.1	63.6
  input extracted in thermal
  plate

• From a review of the data presented in the tables and, with specific reference to Table 3 it is evident that the MSAR™ blend or the composite emulsion provides a high thermal efficiency which exceeds the value for the 5 μm MSAR™ and approximates the 22 μm MSAR™.
• In furtherance of the significant benefits that have been realized in the composite emulsion, Table 2 provides flue gas emission data which again provides evidence that the NO_xand SO₂emissions are very appealing from an environmental point of view in the blend. It is particularly note worthy that the MSAR™ blend composite has a lower carbon content in the particulates and a lower CO concentration in the flue gas than the precursor emulsions, indicating a much better carbon burnout for the composite emulsion.
• Perhaps the most appealing group of data is provided for in Table 3 where the thermal heat transfer data is indicated. Reference to the percent of thermal fuel input extracted in the examples clearly provides for very favourable energy for the composite relative to that for natural gas.
• The data presented herein is further corroborated byFIGS. 13 through 21.
• Referring toFIG. 13, shown is a photograph of a burner where the North Eastern Alberta bitumenMSAR™ fuel1 is being combusted. The flame shape is illustrated in the Figure.
• FIG. 14 illustrates a side view of the flame from the burner of the fuel being burned inFIG. 13.
• FIGS. 15 and 16 illustrate the coke deposit on the nozzle of the burner after the first run of burn, whileFIG. 16 illustrates the coke deposit on the nozzle of the burner after a second run; the difference being fairly significant.
• FIG. 17 provides a view of the burner during the burn of the North Eastern Alberta bitumenMSAR™ fuel2.
• FIG. 18 illustrates the coke deposit on the nozzle of the burner subsequent to the combustion of theMSAR™ fuel2.
• InFIG. 19, the burning of the composite emulsion is indicated in the photograph. It is interesting to note that the flame shape is much more consolidated than the flame shape of the individual precursor emulsions when burned. This is further corroborated byFIG. 20, which shows a fairly significant flame length and intensity when taken from a side view of the burner. As discussed herein previously with respect to the burn characteristics and other features of the composite emulsion,FIG. 21 illustrates the cleanliness of the flame; the coke deposit on the nozzle subsequent to burning is virtually non-existent when one compares this illustration with the coke deposits fromFIG. 16 relating to the combustion ofMSAR™ fuel1.
CONCLUSIONS
• Having regard to the photographic data and physical data presented during the testing of the composite emulsion, it is evident that the composite emulsion has many significant benefits over the burning of the precursor emulsions and in many cases approximates the beneficial features of burning natural gas. Obviously, the combustion of the composite emulsion provides a more desirable energy output from a lower monoxide emission, lower coke deposits at the burner nozzle, lower sulfur dioxide emissions among other very desirable properties. As evinced form the Figures, the composite emulsion flame characteristics provide for a much brighter and more stable flame with less brownish discolouration, lower carbon monoxide emission among other features.
• The embodiments of the invention described above are intended to be exemplary only. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.

Claims (18)

1. An emulsified hydrocarbon fuel, comprising a composite of a plurality of hydrocarbon in water emulsions and emulsion stabilizer, said composite emulsion having a unimodal hydrocarbon particle distribution, said hydrocarbon being present in an amount of between 64% and 90% by volume.

2. The emulsified hydrocarbon fuel as set forth inclaim 1, wherein said fuel comprises at least two different precursor emulsions.

3. The emulsified hydrocarbon fuel as set forth inclaim 2, wherein said precursor emulsions each contain a different hydrocarbon particle size.

4. The emulsified hydrocarbon fuel as set forth inclaim 3, wherein said precursor emulsions contain the same hydrocarbon material.

5. The emulsified hydrocarbon fuel as set forth inclaim 3, wherein said precursor emulsions contain different hydrocarbon material.

6. The emulsified hydrocarbon fuel as set forth inclaim 5, wherein each precursor emulsion has a different rate of combustion.

7. The emulsified hydrocarbon fuel as set forth inclaim 2, wherein said emulsified hydrocarbon fuel is a composite emulsion fuel containing at least two different emulsions in a predetermined ratio.

8. The emulsified hydrocarbon fuel as set forth inclaim 3, wherein said particle size of one emulsion is large relative to said particle size of the second emulsion.

9. The emulsified hydrocarbon fuel as set forth inclaim 7, wherein each precursor emulsion has a characteristic viscosity, said composite emulsion fuel having a viscosity which is less than each characteristic viscosity of each precursor emulsion.

10. The emulsified hydrocarbon fuel as set forth inclaim 9, wherein said composite emulsion has a viscosity between 300% and 500% less than the viscosity of the emulsion containing smaller particles.

11. The emulsified hydrocarbon fuel as set forth inclaim 1, wherein said composite emulsion has a carbon burnout rate of at least 99.99%.

12. The emulsified hydrocarbon fuel as set forth inclaim 1, wherein said composite has a unimodal particle size distribution formed from mixing a bimodal distribution of said at least two precursor emulsions.

13. The emulsified hydrocarbon fuel as set forth inclaim 1, wherein said composite is a multiple polydispersed fuel emulsion.

14. The emulsified hydrocarbon fuel as set forth inclaim 1, wherein said fuel is a liquid fuel emulsified in an aqueous matrix hydrocarbon.

15. The emulsified hydrocarbon fuel as set forth inclaim 1, wherein said hydrocarbon material, comprises less than 18 API.

16. The emulsified hydrocarbon fuel as set forth inclaim 1, wherein said emulsion stabilizer is present in an amount between 0.01% and 5.0% by weight of said emulsion.

17. The emulsified hydrocarbon fuel as set forth inclaim 16, wherein said emulsion stabilizer is a surfactant.

18-61. (canceled)

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