Fuel Emulsions Using Biomass Pyrolysis Products as an Emulsifier

Jan 14, 2003 - Emulsion Group, University of Oriente, Santiago de Cuba, Cuba. Received February 15, 2002. The addition of water to petroleum-derived f...
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Energy & Fuels 2003, 17, 302-307

Fuel Emulsions Using Biomass Pyrolysis Products as an Emulsifier Agent Jose´ Falco´n Herna´ndez* and Jose´ Carbonell Morla´‡ Emulsion Group, University of Oriente, Santiago de Cuba, Cuba Received February 15, 2002

The addition of water to petroleum-derived fuels has been an area of intense research for many years as an alternative to reduce emissions produced by fuel combustion (NOx, smoke, etc.). Additionally, some improvement in fuel consumption has been observed when using fuel emulsions. The handling of heavy and very viscous crude and refined oils has been improved when using emulsions. The present work comprises the results which have been accumulated for the utilization and studies of the pyrolysis products as tensioactive agents for preparation of watery emulsions of crude and distillated fractions from the petroleum. The behavior of the inverse and direct emulsions prepared with pyrolysis product emulsifier agents and studies about the inversion of one into another for adjustment of the handling and combustion of heavy and viscous petroleum products are discussed. Characterization of the emulsifier agent compositions and their effects on the superficial and interfacial tensions, the emulsion rheology, combustion particularities, and other aspects are presented. The results of the Group of Emulsion at the University of Oriente regarding the watery fuel emulsion applications in different combustion systems and other uses are presented as well.

1. Introduction Emulsions and emulsification processes of petroleum and its derived products are considered a very important practice in industry nowadays. The separation of emulsified water (with high salt content) from crude oils is one of the main steps in refineries. It is well-known that the combustion of watery emulsions reduces the unburned fuel (soot) and the NOx concentration in the combustion gas products. The use of emulsions has contributed to the decrease in the number of accidents during storage and handling. It has been reported that the use of emulsified fuels can help to increase the energetic efficiency of some combustion processes.1-5 When handling heavy petroleum fractions (such as asphalts, mazut, fuel oil), watery emulsions may be used to reduce viscosity, thus avoiding the use of expensive organic solvents and reducing the energetic consumption during heating.6,7 An emulsion results from a mechanical mixture of two non-miscible liquids. The system formed by dispersed * Corresponding author. E-mail: [email protected] ‡ E-mail: [email protected] (1) Murayama, H., et al. Experimental Reduction of NOx, Smoke and BSCF in a Diesel Using Uniquely Produced Water (0-80%) to Fuel Emulsion; SAE Technical Paper Series 780224, 1978. (2) Ishida, H.; Watanabe, H.; Tsukahara, M. Influence of Emulsified Fuel Properties on the Reduction of BSCF in a Diesel Engine; SAE Technical Paper Series 891841, 1989. (3) Ishida, H.; Watanabe, H. Flame Suppression of Our Liquid Pool by W/O Emulsification. Comb. Sci. Technol. 1990, 71, 145-154. (4) Harbach, A. J.; Argosta, V. M. Effects of Emulsified Fuel on Combustion in Four-Stroke Diesel Engine. J. Ship Res. 1991, 35 (4), 356-363. (5) Vorshev, Yu. I. Ispolsobanie Bodnye Toplyvnie Emulsiy v Diesel Moriak Dvigatel; Dvigatelstroenie, No. 12, 1986 (in Russian). (6) Ahmed, N. S., et al. Formation of Fluid Heavy Oil-in-Water Emulsions for Pipeline Transportation. Fuel 1998, 78, 593-600. (7) Velazquez, M. Asfaltos; Revolucionaria, Inst. del Libro, La Habana, 1972.

droplets of one phase into the other is stable only for a limited period of time.8 The tenso-active substances (TAS) play a very important role in stabilizing the emulsions. These compounds are also called emulsifier agents or surfactants. They are adsorbed in oriented form in the liquid interfaces, helping the dispersion of the droplets. The TSA creates an energetic barrier, preventing droplet agglomeration phenomena such as flocculation and coagulation.9,10 The emulsions can be classified on the basis of the nature of their continuous and disperse phases into three groups: direct (O/W), inverse (W/O), or mixture. The type of emulsion has a big influence on their practical use. For example, direct water-fuel emulsions show less viscosity than inverse ones. This property is very important for heavy fuel oil handling. However, inverse emulsions are better for combustion where droplet micro-explosion is necessary to improve atomization quality.11 Among emulsion characteristics, the stability has great importance.12 The stability depends not only on the TAS used, but the emulsion preparation parameters and post-preparation conditions. The simple observation of the time elapsed from the moment the emulsion preparation is finished and the one in which the flocculated zones appear (the emulsion is broken) may be used as a parameter quantifying the (8) Schukin, E. D., et al. Quı´mica Coloidal; Mir: Moscow, 1988. (9) Hunter, R. J. Foundation of Colloid Science; Clarendon Press: Oxford, NY, 1989. (10) Vold, R. D.; Vold, M. J. Colloid and Interface Chemistry; Addison-Wesley Reading, MA, 1983. (11) Cherng-Yuan, L., et al. An Experimental Investigation of Burning Droplets of Emulsified Marine Fuel Oils with Water. J. Ship Res. 1995, 39 (1), 95-101. (12) Cavallo, J.; Chang, D. Emulsion Preparation and Stability. Chem. Eng. Prog. 1990, June.

10.1021/ef020030i CCC: $25.00 © 2003 American Chemical Society Published on Web 01/14/2003

Biomass Pyrolysis Products as Fuel Emulsifier

emulsion stability. The sequential measurement of some emulsions’ physical properties such as viscosity, density, droplet size distribution, freezing temperature, electrical conductivity, phase composition, and other properties may be used too, as indicators of emulsion stability.8,9,12 In the case of using water-fuel emulsions, it is necessary to consider other fuel characteristics relevant to combustion, such as heating value, ignition temperature, micro-explosion tendency, and so on. The Group of Emulsion at the University of Oriente in Santiago de Cuba has been working for more than 10 years on the production and use of emulsifier agents from pyrolysis products for the preparation of fuel emulsions. These emulsions have been successfully used in open (boilers, furnaces, etc.) and closed (engines, motors) combustion systems. A review of emulsion and emulsifying agent characteristics as well as some examples of their practical use are described in the sections that follow. 2. Experimental Section The experimental tests have been carried out at laboratory, bench, and industrial scales. These tests have included the formulation and improvement of emulsifying agents using pyrolysis products from different feedstock and pyrolysis installations. As such, pyrolysis products from sugarcane bagasse, wood sawdust, rice, coffee shells, and other biomass materials were obtained under vacuum or atmospheric pressure in moving and fixed beds. All of those products have been tested. The physical and chemical properties (density, pH, conductivity, superficial tension, as well as chemical composition) of the fuels as well as pyrolysis products used in the emulsion preparation were determined. The chemical characterization of the bio-oils was performed using wet analysis methods, gas chromatography (GC), and gas chromatography-mass spectroscopy (GC-MS). The superficial and interfacial tension was measured using a bubble captive Rebinder apparatus, K 8, and an Autotensiomat Fisher model 207 tensiometer. The emulsions were prepared using different systems such as stirrers, colloidal mills, pumps, and ultrasonic mixers. The stability of emulsions was determined measuring their change in properties (viscosity, density, conductivity) and other characteristics with time during storage. Emulsion stability characteristics were determined under non static conditions. Tests involving centrifugal forces, under high pressure in nozzles, when increasing and diminishing temperature and in the specific preparation conditions of engine injectors, emulsion plants, and fuel emulsifiers, have been conducted as well. The size of the droplets was measured using microscopic observations (microscopy JenaLumar, Olympia, and KarlZeiss). The emulsion viscosity was determined as a function of rheological emulsion characteristics, employing rotational (Rheotest), Saybolt, Cannon-Fenske, and Brookfield viscometers. The emulsified fuel has been evaluated using techniques commonly employed for fuel characterization. Measurements such as flash point, ignition temperature, heating values, micro-explosion temperature, corrosion, carbon residue, and ash content have been performed. The micro-explosion studies were performed employing the method proposed by Tsukahara.2 This method consists of adding emulsified fuel droplets over a hot plate with regulation of temperature. The combustion of emulsified fuels was conducted in open and closed fire systems. As a closed combustion system,a bench-scale diesel engine “Raba-Man Ikarus” (140 HP) was used. The engine was adapted to regulate and measure exterior speed, charge, power output, fuel consumption, soot

Energy & Fuels, Vol. 17, No. 2, 2003 303 in gases, and other characteristics. Emulsion combustion studies in trucks, tractors, cars, and other vehicless were performed in different enterprises of the Cuban east region. The evaluation of emulsified fuel in open combustion systems has been conducted in medium- and low-capacity boilers, in cement kilns, and in other material dryers. Data from studies of the effect of the emulsifier and emulsification equipment have been accumulated for more than 6 years in these installations.

3. Results and Discussion The results obtained using biomass-derived products as emulsifiers are reported in the section that follows. The characteristics of commercial emulsifying agents, petroleum-water emulsions, and experiences with pyrolysis product emulsifying agents are pointed out. An analysis of the effect of pyrolysis product components on tensioactive characteristics of the emulsifying agent, the influence of the petroleum components on emulsion stability, emulsified fuel use on combustion, and future thematic development is reported. 3.1. Emulsifier Agent. The physicochemical properties of products generated through various pyrolysis technologies under a wide range of operating conditions for different feedstocks have been widely reported in the literature.13,14 The large number of chemical species (more than 200 biomass-derived species) present in biooils is the major problem faced during its characterization.15,16 The bio-oils can be divided into as:water, GCMS detectable compounds, and high-molecular-weight not detectable compounds. Another approach to characterize the biomass-derived products could be from the viewpoint of their principal functional groups (carboxyl, carbonyl, hydroxyl, phenolic, and methoxyl).17 The liquid pyrolysis products used in our work are primarily separated into two classes: tar and acid water (pyrolygneous acid). The tar is the rich organic fraction containing phenols and other cyclic and high-molecularweight compounds. The acid water contains a large amount of water, acetic acid, alcohols, and other short polar organic compounds.18,19 Phenols can be extracted from the tars through an alkalinizing treatment.20 The “phenolates” extracted have well-recognized surfactant characteristics. This fraction can be used as a surfactant after its mixture with short organic chain compounds, such as alcohol and acetate, and pH regulators. (13) Fagernas, L. Chemical and Physical Characterization of Biomass-Based Pyrolysis Oils. Literature review. Espoo 1995, Technical Research Center of Finland. VTT-Research Notes 1706; 113 pp. (14) Radlein, D. The Production of Chemical from Fast Pyrolysis BioOils; Fast Pyrolysis of Biomass. A Handbook. CPL Scientific Publishing Ltd., 1999; pp 164-188. (15) Goos, A. W. In Wood Chemistry, 2nd ed.; Wise, L. E, Jahn, E. C., Eds.; ACS Monograph 97; American Chemical Society: Washington, DC, 1952; Vol. 2, 826 pp. (16) Meir, D. New Methods for Chemical and Physical Characterization and Round Robin Testing. Fast Pyrolysis of Biomass. A Handbook. CPL Scientific Publishing Ltd., 1999; IV-II, pp 92-101. (17) Nicolaides, G. M. The Chemical Characterization of Pyrolytic Oils; M.A.Sc. Thesis, University of Waterloo, 1984. (18) Pakdel, H.; Roy, C. Hydrocarbon Content of Liquid Products and Tar from Pyrolysis and Gasification of Wood. Energy Fuels 1991, 5, 427-436. (19) Pakdel, H.; Roy, C. Chemical Characterization of Wood Pyrolysis Oil Obtained in a Vacuum Pyrolysis Multiple Hearth Reactor. ACS Symp. Ser. 1988, 376, 203-220. (20) Brossard, L. Desarrollo de un Aditivo Espumante a Partı´r de Piro´ lisis de Materiales Lignocelulo´ sicos. Ph.D. Thesis, Universidad de Oriente, 1996.


Energy & Fuels, Vol. 17, No. 2, 2003

Herna´ ndez and Morla´

Table 1. Main Compounds Detected in Emulgents P and b by GC-MS compound propanoic acid, ethyl ester 1,2-ethanediol ethane, 1,1-diethoxy1-butanol, 3-methyl1-hydroxy-2-butanone 1-cyclopenten-1-one, 2-methylethanone, 1-(2-furanyl)butyrolactone 2-furancarboxaldehyde, 5-methyl2-cyclopenten-1-one, 3-methylphenol 1,2-cyclopentanedione, 3-methyl2,3-dimethylcyclopent-2-en-1-one phenol, 2-methylphenol, 2-methoxy2-cyclopenten-1-one, 3-ethyl-2-hydroxyphenol, 2,4-dimethylphenol, 4-ethylphenol, 2-methoxy-4-methyl1,2-benzenediol 1,4:3,6-dianhydro-R-D-glucopyranose phenol, 4-ethyl-2-methoxy-

Emulgent ba

1 3 3 4 4 3 3 4 3 3 4 4 3 3 3 4 3 3 4

Emulgent Pa 3 3 2 4 1 1 4 4 1 4 4 3 1 3 4 1


In the column appears the number of the Emulgents in which the compound is detected (see Table 2).

The Group of Emulsion at the University of Oriente was granted an invention register (patent) for an emulsifying agent21 formed by a mixture of alkalized tar, pyrolygneous acid, and ethyl alcohol in appropriate proportion to regulate its tenso-active properties. Later, the Emulsion Group continued developing studies about the use of pyrolysis products obtained from different feedstocks, such as sugarcane bagasse, sawdust, and rice and coffee shells. Pyrolysis products of rice and coffee shells give liquids with higher pH than bagasse and sawdust, and good emulsifier agents have not obtained from them. There is also the dependence between the employed pyrolysis process and liquid pyrolysis composition, which is reflected in the emulsifier agent and emulsion characteristics. Studies of these dependences have been carried out and a paper must be presented to the Third World Congress on Emulsion.31 In the present work two emulsifier agent types are reported: Emulgent Psusing pyrolysis products from a tubular reactor working at atmospheric pressuresand Emulgent bswhere the tar was substituted by sugarcane bagasse bio-oils obtained under vacuum at the Vacuum Pyrolysis Laboratory at Laval University, Canada.24 Table 1 shows the main compounds present in the emulsifier agents (Emulgents P and b) obtained with different pH values (see Table 2), detected by GC-MS. Table 2 shows the superficial tension versus pH of Emulgents P and b prepared using different proportions of pyrolygneous acid, phenolate, and alcohol under similar conditions. The surface tension of two com(21) Falcon, J., et al. Registro de Invencio´n No. 22253, ONITEEM, Cuba, 1994. (22) Falco´n, J., et al. Characterization of Emulsifier Agents Obtained from Pyrolysis Products. XIV International Conference of Chemistry, University of Oriente, Santiago de Cuba, 1996. (23) Fior, M. S.; Farouq, Ali M. Optimal Emulsion Design for the Recovery of a Saskatchewan Crude. 40th Annual Meeting of the Petroleum Society of CIM, 1989. (24) Garcia, M., et al. Vacuum Pyrolysis of Sugarcane Bagasse. Conference Reciclaje in Metanica Convention, La Habana, 2000.

Figure 1. Water superficial tension values adding different concentration of Emulgent P and b. Table 2. Superficial Tension (δ in mN/m) of Emulgents P and b, Prepared to Different Composition and pH Values in Similar Conditions and of the Products Tween 80 and Ionet S 2 Emulgent P

Emulgent b


δ (mN/m)


δ (mN/m)

5.16 6.04 6.99 8.85 Tween 80

40.72 40.96 43.03 41.08 35.65

4.96 6.02 6.85 7.09 Ionet S 2

33.16 33.90 32.28 34.51 32.96

mercial surfactants (Ionet S2 and Tween 80) is presented for comparison. As can be observed in Table 2, it is possible to regulate the superficial tension of an emulsifier agent by changing the source of pyrolysis products used as well as its proportion in the mixture. Also, changes in the electrokinetic potential for the double layer theory are observed. Figure 1 shows the water superficial tension with different agents and concentrations. Emulsifier P with pH ) 6.99 and σ ) 43.03 mN/m and Emulsifier b with pH ) 4.96 and σ ) 33.16 mN/m give non-water superficial tension proportionately to emulsifying agent values. This and the observed water superficial tension variations denote the possibility of selective adsorption of determined compounds from the emulsifying agents. 3.2. Petroleum-Water Emulsions. Petroleum is commonly found in deposits as a water-petroleum emulsion, and this is why de-emulsification and washing is the first petroleum refining step. This operation has as its objective to extract water and high salt contents from the crude oil. The high stability of natural petroleum emulsions is associated with the presence of highmolecular-weight compounds such as resins, asphaltenes, etc.,23 and high salt content in the water as well. Also, the high viscosity and density of some crude oils help the stability of their emulsions with water.25 The stability ofwater emulsions of refined petroleum products such as turbo-fuel, kerosene, gas oil, fuel oil, and other combustibles is reduced with the decrease in its molecular weight, density, and viscosity. The presence of small quantities of larger compounds may contribute considerably to the stabilization of such emulsions. This phenomenon has been used by many authors to increase the stability of light fuel emulsions.26 (25) Fingas, M., et al. Water-in-Oil Emulsions Results of Formation Studies and Applicability to Oil Spill Modelling. Spill Sci. Technol. 1999, 5 (1), 81-91.

Biomass Pyrolysis Products as Fuel Emulsifier

Energy & Fuels, Vol. 17, No. 2, 2003 305

Figure 2. Flow curves of gas oil-water emulsions.

For emulsified fuels, it is very important to be able to obtain different stabile and reversible emulsions (O/W and W/O). The formulation of direct emulsions (O/W) could be very important for fuel transportation where the reduction of viscosity is desirable.6 However, during combustion of emulsified fuels, it is necessary to feed an inverse emulsion (W/O) to the combustion chamber. These emulsions will help to produce a secondary atomization due to the micro-explosion phenomena.2,5,11,26 As such, the best condition for the use of emulsified fuels is the one in which direct emulsions are prepared for handling, but where the emulsion can be reversed just before its combustion. This is our research goal with this work. The emulsion stability as well as its reversibility depend on the compounds adsorbed in the interfacial barrier and the structure formed. The structure of the interfacial barrier is linked directly with the nature of the emulsifier agent compounds adsorbed. For emulsion inversion, other factors should be taken into consideration, such as the temperature and the introduction of a third competitive phase (for example, air).26 A large amount of data has been accumulated regarding the characteristics and combustion properties of the emulsions formed.26-28 Beginning with gas oil-water emulsions in the 1990’s, the studies in the following directions have continued: different oil emulsions (diesel, kerosene, fuel oil, asphalt crude petroleum), improved emulsifier agents, and determination of the influence of important factors on emulsion stability. The viscosity is an important parameter related to the emulsion stability and its flow characteristics.27 The emulsion rheological model is dependent on emulsion type, the phases ratio, tensioactive nature, and other such factors. For a long time the Group of Emulsion at the University of Oriente has been conducting rheological studies of different kinds of fuel emulsions. Below, some experiences with the emulsions prepared with pyrolysis product emulsifier agents are considered: In Figure 2 are shown some curves of flow of the gas oil-water emulsions (gas oil-water ratio 20:80) that were determined using a rotational viscometer Rheotest II. All the emulsions were prepared using a helices (26) Falco´n, J., et al. Emulgente para Emulsiones Combustibles Gas Oil-Agua. Rev. Tecnologia Quimica 1993, 14 (2). (27) Falco´n, J., et al. Emulgente a Partir de los Productos de Piro´lisis de Materiales Lignocelulo´sicos. Emulgente a Partir de los Productos de Piro´lisis de Materiales Lignocelulo´sicos. Rev. Tecnologia Quimica 1993, 14 (3). (28) Falcon, J.; Carbonell, J. Empleo de Emulsiones en Hornos y Calderas; CIER-99, 1999.

Figure 3. Cuban crude petroleum-water emulsions employing Emulgents P and b with different pH and conditions.

stirrer with speed 3400 min-1 and retention time of 5 min. Gas oil emulsions with different Emulgent P concentrations (0, 2, 3, 4, and 5 wt %) were prepared using fuel oil as additive (1:1000). In these conditions an inverse emulsion (W/O) is obtained. As can be observed in Figure 2, the emulsions show a pseudo-plastic behavior and their viscosity is influenced by the emulsifier agent concentration, by the fuel oil used as an additive, and by the preparation conditions. It has been observed that the emulsion viscosity may be above or under gas oil viscosity, depending on the previously mentioned parameters. Similar rheological studies had been carried out using kerosene, fuel oil, asphalt, and Cuban crude oil. In these studies the emulsifier agent proved to be able to stabilize inverse emulsions (W/O). For these kinds of emulsions, the water droplets can be encapsulated for periods as long as one year, showing a great stability under pressure. However, the water-phase sedimentation appears after a determined time depending on water and emulsifier agent concentrations, of the viscosity and density differences between the water and the fuel. The stable direct emulsions (O/W) are more difficult to produce and have only been obtained for certain conditions. A more complex behavior has been observed in Cuban crude oil emulsions because of the presence of many oil components with tenso-active properties. These compounds provoke strong structural differences in the water-oil inter-phase. These differences are reflected in the kind of emulsion obtained and its stability. Figure 3 shows the shear stress versus the shear rate obtained for Cuban crude oil emulsions prepared with Emulgents b and P at different pH values. Emulgent P always gave direct emulsions (O/W) with viscosity lower than that of crude petroleum, while Emulgent b gave inverse emulsions (W/O) with high viscosity. With Emulgent b, it is possible to obtain emulsions with the same or lower than crude petroleum, reducing the W:O ratio and emulsifier agent concentration in the water phase of the emulsion. The use of seawater increases the direct emulsion viscosity compared to that of fluent water. Figures 4 and 5 show the flow curves at different temperatures for direct emulsions prepared with Emulgent P at pH 5.16 and concentration of 8 wt % of water.


Energy & Fuels, Vol. 17, No. 2, 2003

Figure 4. Flow curves of direct emulsion prepared with Emulgent P at pH ) 5.16 and W:O ) 60:40.

The water/oil ratios were 50:50 and 40:60, respectively. In Figure 4 can be observed the unexpected result that the emulsion viscosity increases with the temperature. This result can be due to the formation of new interphase structures under the temperature effect. In Figure 5, it can be appreciated that the viscosity increase is higher at low shear rate. However, after reaching a certain shear rate, the structure is broken and viscosity decreases abruptly to levels that correspond to the ones expected for an increase in the temperature. The changes in the emulsion’s viscosity depicted in Figures 4 and 5 can be explained by the presence of viscoelastic features in the water-crude oil emulsions when using pyrolysis-derived products. Because of the importance of this behavior on the emulsion inversion control, nore extensive studies are been conducted. 3.3. Combustion Experiences Using PyrolysisDerived Emulsifier Agents. Emulsifier agents obtained from pyrolysis products have been employed in the preparation of emulsions for combustion in open and closed systems as well as in the preparation of asphaltpaintings. Together with the emulsion use, studies about the influence of water in combustion have been carried out. Next, some data about the use of emulsifying agents in fuel-emulsion combustion are reported. Laboratory and bench-scale combustion studies were conducted with the objective of establishing the most efficient utilization of emulsified fuel. Tests using emulsified diesel (gas oil) fuel prepared with Emulsifier

Herna´ ndez and Morla´

P were carried out in the bench-scale diesel engine “Raba-Man Ikarus” of 140 HP. The water concentrations in the emulsions were between 5 and 20%. The most important engine characteristics (rotation speed, nominal charge, power output, escape gases composition, specific fuel consumption, and others) were evaluated with the emulsified fuels and compared to the ones obtained when used non-emulsified fuels. In Figure 6 are depicted the engine regulation characteristics for an external velocity (1700 min-1) changing water content in the emulsified fuel and the injection angle. As can be observed in this figure, the combustion of emulsified fuels behaves differently from the combustion of non-emulsified fuels. It was necessary to adjust the advance injection angle to 24°. When comparing the decrease of the motor power output (Ne) and torsion moment (Me) with the specific fuel consumption (Cm), we observe that there has been an increase in efficiency. The best results were obtained for emulsions containing between 10 and 15% water. Experiments using emulsified diesel fuels (gas oil) with Emulgent P have been carried out in cars, trucks, tractors, motors, and other combustion systems in different enterprises in the Cuban east region.28,29 The evaluation of water-heavy oil emulsified fuels has been carried out in two PKM boilers (4 t/h of vapor) at the General Hospital in Santiago de Cuba city. This installation has been used in the study of emulsified fuel combustion for many years. Measurement of fuel oil consumption, NOx and soot in combustion gases, boiler tube corrosion, etc., were carried out in these boilers. In all cases, the emulsifier agents obtained from pyrolysis products ensured stable inverse emulsions which burn under appropriate conditions. Additionally, positive improvements in atmospheric pollution, specific fuel consumption, number, and time employed in the maintenance have been observed. A tendency to reduce specific fuel consumption when the water content of the emulsion is increased can be observed in Figure 7. The data reported correspond to activities conducted during more than a 2-year period. The optimum water content changes depending on the boiler characteristics.

Figure 5. Flow curves of direct emulsion prepared with Emulgent P at pH ) 5.16 and W:O ) 50:50.

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Energy & Fuels, Vol. 17, No. 2, 2003 307

Table 3. Combustion Tests of the Emulsified Fuels in a Kiln Dryer material type

solid feed, T


2309 1166 1749

non-emulsified fuel fuel, liters humidity, % 27115 14096 21661

2.41 3.33 2.53

consumption, l/T

solid feed, T

11.74 12.09 12.38

739 369 339

emulsified fuel fuel, liters humidity, % 8248 4026 3889

consumption, l/T

2.44 2.08 3.76

11.16 10.91 11.47

Table 4. Viscosity of Water-Cuban Crude Petroleum Emulsions Varying Temperature, W:O Ratio, and Emulsifier P Concentration in the Water no.

Emulsifier P in water, wt %

emulsion crude content, wt %

temperature, °C

viscosity (cSt)

3 3 3 6 3 6 3 6 6

50 50 60 50 50 60 60 50 60 100 100

27 82 82 82 50 82 50 50 50 50 82

145 576 1000 1001 1425 1875 1794 2476 3107 1701.2 1031.5

1 2 3 4 5 6 7 8 9 10 11

Figure 6. Diminution of the power output (Ne), torsion moment (Me), and fuel consumption (Cm) of the engine with different water content in the emulsion.

Figure 7. Fuel consumption vs water content in the emulsion.

The emulsified fuels have also been used in the drying of rock and sand particles for the preparation of concrete asphalt in a kiln furnace. The data obtained for dried rock (D), mixture of rock and sand (AD), and sand (A) using emulsified and non-emulsified fuel oil-water is shown in Table 3. As can be appreciated, fuel economy is obtained when using emulsified fuel. Other parameters such as the emulsion effects on the unburned fuel, in the dust collection system, and in the heat distribution in the kiln were determined too. At present, the Group of Emulsion at the University of Oriente is carrying out experiments related to the handling and combustion of Cuban crude oils. Other areas of interest are emulsion behavior during ocean spills, factors affecting the inversion of emulsion and its control, and stratification of fuel mixtures and emulsions during long-term storage. The tests performed until now have demonstrated that crude oil direct emulsions using pyrolysis product emulsifier (29) Falco´n, J.; Carbonell, J. Trabajos Realizados por el Grupo de Emulsiones Combustibles de la Universidad de Oriente. XII Forum Nacional de Ciencia y Tecnica, La Habana, 1999.

agents could be used to reduce the viscosity of the system.30 In Table 4 is reported the viscosity of waterCuban crude oils emulsions, measured using a SayboltFurol viscometer at different temperatures and Emulgent P concentrations. We bserve that at atmospheric temperature (28 °C) the emulsion has a low viscosity due to the formation of a direct emulsion (O/W). When the temperature increases to 50 °C, the emulsion inversion (to W/O) occurs and the emulsion viscosity increases abruptly. Later, the viscosity diminishes upon temperature increases. In the same table it is also possible to observe the effect of the emulsifier agent concentration on the emulsion viscosity. Much research work is still needed to determine the influence of many other factors on emulsion behavior when using emulsifier agents obtained from pyrolysis products. 4. Conclusions • Biomass-derived pyrolysis products can be used in the formulation of emulsifier agents. These agents can be used in the preparation of emulsified fuels with improved combustion and handling properties. • The pyrolysis product emulsifier agents are more effective for inverse emulsion (W/O) preparation of the fuel and petroleum; however, it is also possible to obtain direct emulsions (W/O) with the emulsifier agents. The possibilities of inversion of one kind of emulsion to another using these emulsifier agents are currently under study. • The experiments conducted with different wateremulsified fuels using pyrolysis-derived emulsifier agents in both open and closed combustion systems have shown that these emulsions could have many advantages in reducing pollution, facilitating the handling of highly viscous fuels, and improving the energetic efficiency of combustion systems. EF020030I (30) Ferro, A. Estudio de la Sustitucio´ n de las Pinturas Asfa´ lticas Convencionales por Emulsiones de Crudo Cubano con Emulgente P. M.Sc. Thesis, Universidad de Oriente, 2000. (31) Falcon, J.; Carbonell, J. Emulsifier Agents from Pyrolysis Products for Petroleum and Derived Product Watery Emulsions. Paper sent to Third World Congress on Emulsion, Lyon, France, September 2002.