Showing papers on "Emulsified fuel published in 2009"

Application of DSC for Emulsified System Characterization

Abstract: This paper will describe how Differential Scanning Calorimetry (DSC) may be used to characterize emulsions, especially the concentrated and opaque water-in-oil emulsions encountered in the oil industry. After a presentation of the technique, we will point out how it is possible, from a single test performed on an emulsion sample without dilution, to get information about the solidification and melting properties of these complex fluids, the emulsion type, the amount of water, the presence of solute, the stability and even the droplet size. Some examples of applications are given concerning oilfield emulsions and oil-based mud systems.

Effect of Inorganic Solids, Wax to Asphaltene Ratio, and Water Cut on the Stability of Water-in-Crude Oil Emulsions

Abstract: The formation of stable water-in-crude oil emulsions during petroleum production and refinery may create sever and costly separation problems. It is very important to understand the mechanism and factors contributing to the formation and stabilization of such emulsions for both great economic and environmental development. This article investigates some of the factors controlling the stability of water-in-crude oil emulsions formed in Burgan oil field in Kuwait. Water-in-crude oil emulsion samples collected from Burgan oil filed have been used to separate asphaltenes, resins, waxes, and crude oil fractions. These fractions were used to prepare emulsion samples to study the effect of solid particles (Fe3O4) on the stability of emulsions samples. Results indicate that high solid content lead to higher degree of emulsion stability. Stability of emulsion samples under various waxes to asphaltenes (W/A) ratios have also been tested. These tests showed that at low W/A content, the emulsions were very stable. Wh...

Preparation and Flow Behaviour of Oil‐In‐Water Emulsions Stabilised by Hydrophilic Silica Particles

Abstract: Emulsions are a common form of material and are encountered in products including foods, cosmetics, and pharmaceuticals. Appropriate formulation and processing ensures stability and quality. The research reported is concerned with the use of nano-particles for interfacial stabilisation of oil-in-water (o/w) emulsions. This is a route far less often chosen by formulation engineers than interfacial stabilisation based on small molecular surfactants. Known concepts of stabilising simple o/w emulsions with hydrophilic silica particles were applied. The emulsion components were carefully selected in view of their application relevance in consumer goods such as foods and creams. Emulsions stable against coalescence were formulated based on discrete 230 nm silica particles and corn oil. The viscosity behaviour of the emulsions was characterised after suppressing creaming through dissolution of a thickening agent in the continuous emulsion phase. The emulsions were shear-thinning and viscosity levels were reduced after removal of free particles. Particle stabilisation of o/w interfaces alters the product characteristics of emulsion-based products, giving formulation engineers novel ways to adjust product rheologies.

Synthesis of macroporous silica from solid-stabilised emulsion templates

Abstract: We have investigated the microstructures of the solid residue left behind after the evaporation of solid-stabilised emulsions. The correlation between the microstructure and the properties and preparation conditions of the emulsions will be thoroughly discussed. The type of microstructure is related to the conditions (oil type, oil content, particle type, particle concentration and emulsion type) of the initial emulsion. Solid residues left after evaporation of oil-in-water emulsions containing volatile oils (relative to water) show a “knobbly” microstructure. When oils with similar or lower vapour pressure to that of water were used, “sponge-like” structures were obtained. For emulsions containing volatile oils, the mean drop diameter is similar to the mean pore diameter, whereas when oils with low vapour pressure are used, the pores are much smaller. Finally, this paper will illustrate that stable toluene-in-water emulsions leave porous microstructures, whereas water-in-toluene emulsions and emulsions close to the phase inversion show sheet-like or “knobbly” structure.

Role of liquid crystal in the emulsification of a gel emulsion with high internal phase fraction.

Abstract: A gel emulsion with high internal oil phase volume fraction was formed via an inversion process induced by a water-oil ratio change. The process involved the formation of intermediate multiple emulsions prior to inversion. The multiple emulsions contain a liquid crystal formed by the surfactant with water; this was both predicted by the equilibrium phase diagram as well as observed using polarization microscopy. These multiple emulsions were more stable compared to alternative multiple emulsions prepared in the same way with a surfactant that does not form liquid crystals. While the formation of a stable intermediate multiple emulsion may not be a necessary condition for the inversion to occur, the transitional presence of a liquid crystal proved to be a significant factor in the stabilization of the intermediate multiple emulsions. The resulting gel emulsion contained a small fraction of the liquid crystal according to the phase diagram, and it exhibited excellent stability.

Utilizing Water Emulsification to Reduce NOx and Particulate Emissions Associated with Biodiesel

Abstract: A key barrier limiting extended utilization of biodiesel is higher NOx emissions compared to petrodiesel fuels. The reason for this effect is unclear, but various researchers have attributed this phenomena to the higher liquid bulk modulus associated with biodiesel and the additional heat released during the breaking of C-C double bonds in the methyl ester groups. In this study, water was incorporated into neat biodiesel (B100) as an emulsion in an attempt to lower NOx and particulate matter (PM) emissions. A biodiesel emulsion containing 10wt% water was formulated and evaluated against an ultra-low-sulfur petroleum diesel (ULSD) and neat biodiesel (B100) in a light-duty diesel engine operated at 1500 rpm and at loads of 68 and 102 Nm (50 and 75 ft-lbs). The influence of exhaust gas recirculation (EGR) was also examined. The incorporation of water was found to significantly lower the NOx emissions of B100 while maintaining fuel efficiency when operating at 0% and 27% EGR; however, NOx emissions were observed to increase slightly for the emulsified fuel when the engine load was raised to 102 Nm (75 ft-lbs). The soot fraction of the particulates (as determined using an opacity meter) was much lower for the B100 and B100-water emulsion compared to the ULSD. In contrast, total PM mass (for the three fuel types) was unchanged for the 0% EGR condition but was significantly lower for the B100 and B100-emulsion during the 27% EGR condition compared to the ULSD. Analysis of the emissions and heat release data indicate that water enhances air-fuel premixing to maintain fuel economy and lower soot formation. The exhaust chemistry of the biodiesel base fuels (B100 and water-emulsified B100) was found to be unique in that they contained measurable levels of methyl alkenoates, which were not found for the ULSD. These compounds were formed by the partial cracking of the methyl ester groups during combustion.

Water-in-Diesel Microemulsions Studied by NMR Diffusometry

Abstract: Water-in-diesel microemulsion fuels are attractive in that they are thermodynamically stable and visually similar to regular diesel. This is contrary to water-in-diesel emulsion fuels, which are inherently unstable and have a milk-like appearance. Both emulsion- and microemulsion-based fuels give large reductions in soot emissions in combustion. In this work microemulsions have been formulated with nonionic surfactants and with varying amounts of water and the microemulsion regions have been determined in the temperature interval from 17 to 50°C. The extension of the microemulsion regions has been assessed with amount of surfactant, type of surfactant and temperature as parameters. The internal structure of the microemulsions has been investigated by NMR diffusometry by which the diffusion coefficients of diesel hydrocarbons, water and the surfactants are determined. The diffusometry measurements indicate that the water is present as spherical water domains. They also show that as the amount of water incr...

Experimental investigation and performance evaluation of DI diesel engine fueled by waste oil-diesel mixture in emulsion with water

Abstract: Exploitation of the natural reserves of petroleum products has put a tremendous onus on the automotive industry. Increasing pollution levels and the depletion of the petroleum reserves have lead to the search for alternate fuel sources for internal combustion engines. Usage of vegetable oils poses some challenges like poor spray penetration, valve sticking and clogging of injector nozzles. Most of these problems may be solved by partial substitution of diesel with vegetable oil. In this work, the performance and emission characteristics of a direct injection diesel engine fueled by waste cooking oil-diesel emulsion with different water contents are evaluated. The use of waste cooking oil-diesel emulsion lowers the peak temperature, which reduces the formation of NOx. Moreover the phenomenon of micro explosion that results during the combustion of an emulsified fuel finely atomizes the fuel droplets and thus enhances combustion. Experiments show that CO concentration is reduced as the water content is increased and it is seen that 20% water content gives optimum results. Also, there is a significant reduction in NOx emissions.

Formulation and combustion of emulsified fuel: The changes in emission of carbonaceous residue

Abstract: Burning dense, viscous combustibles such as heavy fuel-oil as a water-in-oil emulsified combustible enables to decrease the emission of solid carbonaceous residue, in comparison with raw, non-emulsified combustible. This is due to the phenomenon of micro-explosion, meaning the rapid (<0.1 ms) vaporization of the water droplets inside the emulsion, breaking up the initial emulsion droplet into numerous and faster 'daughter-droplets'. The present work is based on a small-scale furnace (300 kW max.) feed with heavy fuel-oil mixed with 10-20% of gasoil, with and without emulsion of water. The emulsification of combustible enables to record a reproducible lowering in emission of carbonaceous residue from the combustion of emulsified fuel, in comparison with raw fuel. This is added to a variation in granulometry of carbonaceous residue, hereby considered as an indicator of second atomization. Copyright (C) 2009 John Wiley & Sons, Ltd.

Performance and emissions of motorcycle engines using water-fuel emulsions

Abstract: This article studied water?gasoline emulsions for reducing the NOx emissions of a motorcycle engine. Emulsified gasoline fuels of 0, 5, 10 and 15% water by volume were used in a four-stroke, 125 cc, port injection, spark-ignition engine. Both full throttle speed ranging from 2,000 to 7,000 rpm and low load were tested. The engine torque, fuel consumption, exhaust emissions and combustion characteristics were investigated. The experimental results show that the engine torque and fuel consumption are improved for 5 and 10% water emulsions. However, at 15%, the engine torque and fuel consumption deteriorate and the exhaust temperature is increased owing to slow burn rate. The exhaust emissions of NOx and CO decrease as the water percentage in the emulsion increases. A higher oxygen concentration in exhaust gas of emulsified fuel was found, which results in lower CO emission. The HC emission is increased with increasing water content, which might be caused by the thicker quench layer of emulsified fuel combustion. An appropriate concentration of water in the emulsified gasoline fuel for a 125 cc motorcycle engine is found to be 10%.

Experimental Investigation of Emulsion Stability in Gas/Oil Separation Plants

Abstract: SummaryThis paper presents an experimental study performed to charac-terize the stability of emulsion samples collected from different Gas/Oil Separation Plants (GOSPs). The first part of the study (Al-Ghamdi et al. 2007) focused on the analyses of separated phases. Many techniques (differential scanning calorimetry, Karl Fischer titration, rheology, optical microscopy, and cryo-scanning electron microscopy) were applied to analyze and characterize the separated phases: crude oil, emulsion, and free water. In the second part of this study, the stability of residual emulsions was investi-gated against several chemical demulsifiers by using bottle tests and an automated vertical-scan macroscopic analyzer (Turbiscan; Formulaction; Toulouse, France). This instrument is used to obtain kinetics of separation of concentrated and opaque dispersed sys-tems such as emulsions, suspensions, and foams. Interfacial ten-sion measurements were also made to obtain information about the interfacial behavior of samples including viscoelasticity properties of the film. The results of transient emulsion-separation experi-ments provide some useful insights into their behavior, stability, and tightness. The study highlights the main physicochemical parameters responsible for the varying tightness of these emulsions and should help provide recommendations to optimize their treat-ment costs and resolve emulsion issues in the GOSPs.IntroductionThe formation of stable water-in-crude-oil emulsions during oil production poses significant challenges during oil/water separa-tion in surface production facilities (Kokal 2006; Schramm 1992). These emulsions can be very stable because of the presence of rigid films formed by polar compounds, such as asphaltenes and resins, and other fine solids (Graham 1988; Papirer et al. 1982; Bridie et al. 1980; Ese et al. 1997; Jones et al. 1978; McLean and Kilpatrick 1997). Effective separation of crude oil and water is essential to ensure the quality of separated phases at the lowest cost. Crude-oil dehydration is generally accomplished by a combination of mechan-ical, electrical, thermal, and chemical methods. The addition of chemical additives is by far the most common method in emulsion breaking. The chemicals disrupt the interfacial film and enhance emulsion breaking (Schramm 1992; Lissant 1983).Earlier studies (Kokal and Al-Ghamdi 2007, 2008) have shown the importance of emulsion characteristics on the performance and optimization of oil/water separation. The present study was per-formed to carry out an in-depth analysis of the main physicochemi-cal properties of emulsions and the link to their behavior in the field. The main objective is to provide recommendations to reduce treatment costs and optimize oil/water separation in the field.In the first part of this study (Al-Ghamdi et al. 2007), a strict and rigorous method was applied to characterize the behavior and com-position of emulsion samples from several GOSPs. The samples first were separated to identify the amount of separated oil, water, and residual emulsion. Each phase then was analyzed separately. Bulk properties (viscosity, density) and chemical composition of crude oils were determined. Salinity and geochemical analysis of the separated water were made when possible or assessed by dif-ferential scanning calorimetry (DSC) in other cases. The residual emulsions were characterized using several techniques including Karl Fischer titration to determine the water content, DSC, optical microscopy or cryo-scanning electron microscopy (cryo-SEM) to assess the size and polydispersity of the dispersed droplets. The second part of this work addresses the stability of residual emulsions from selected samples using chemical demulsifiers. The efficiency of several chemical additives, including field demulsi-fiers, was determined using bottle tests and an automated vertical-scan macroscopic analyzer. Rheological behavior and fine-solids content of emulsions were also measured. Interfacial tension measurements were made to investigate the interfacial behavior of selected samples including viscoelasticity properties of the films.Materials and Methods

Direct Determination of V, Ni, and Co in Emulsified Fuel Oil Samples by Electrothermal Atomic Absorption Spectrometry (ETAAS)

Abstract: A direct, simple, and fast procedure is presented to determine V and Ni in fuel oil samples as emulsions by electrothermal atomic absorption spectrometry (ETAAS). Fractional experimental designs were applied to find the most significant variables affecting the preparation of the sample in terms of the analytical performance and also of the stability of the emulsion. Emulsions were directly prepared into the autosampler cups of the AAS instrument taking 0.25 mL of the fuel oil sample dissolved in toluene and adding HNO 3 , xylene, Triton X-100, and ultrapure water to a final volume of 1 mL. This procedure was extended to Co determination. The method was validated with the standard reference material SRM 1634c Fuel Oil, obtaining satisfactory accuracy (107%, 101%, and 103% recovery for V, Ni, and Co, respectively) and overall precision (RSD <10%) for the three elements. The limits of detection of the method were 5.7, 6.5, and 0.07 μg g -1 for V, Ni and Co, respectively, and the characteristic masses for the emulsion were 42.2 ± 3.8 pg for V, 22.3 ± 2.3 pg for Ni, and 11.7 ± 0.8 pg for Co. The established procedure reduces sample manipulation, minimizes the amount of reagents employed, allowing the determination of V, Ni, and Co in a unique emulsion using direct calibration with aqueous standard solutions. Ten fuel oil samples derived from an oil spill were analyzed applying this procedure.

Rheology and stability of olive oil cream emulsion stabilized by sucrose fatty acid esters nonionic surfactants

Abstract: The influence of oil and surfactant concentration to the stability and rheological behavior of the olive oil emulsions stabilized with sucrose fatty acid ester was evaluated through an accelerated aging test at 45oC. The stability of the emulsion in this study was examined by the appearance of phase separation in the emulsion, mean droplet size and Zeta potential over one month. The effect of accelerated ageing on the emulsions rheological properties was investigated using oscillatory measurements and a viscometry test at the interval of one day, one week and one month of storage time. The droplet size of the emulsions was found to decrease with the increase in the oil and surfactant concentrations which give effect on the viscosity and yield stress of the emulsions. The flow curve of the emulsions always exhibited shear thinning behavior and obeys the Power Law viscosity. The shear thinning effect of the emulsions was found to be decreased when the oil and surfactant concentration increased due to the smaller droplet size and narrower size distribution. The dynamic properties of the emulsions were also affected by the oil and surfactant content which indicates the stronger structural integrity and greater interdroplet interactions. The viscoelasticity of the emulsions was enhanced by the increased in the oil and surfactant concentrations. The emulsions with higher oil composition show greater elasticity which implies strong dynamic rigidity of the emulsions. The emulsions with 80% oil were the most stable emulsions with longest shelf-life.

Heat-sensitive emulsions

Abstract: The invention relates to heat-sensitive emulsions that can be destabilized by increasing the temperature. The emulsions include a copolymer with amphiphilic blocks.

Viscosity of Concentrated Emulsions: Relative Effect of Granulometry and Multiphase Morphology

Abstract: High viscosity and high density make heavy and extra heavy crude oils very difficult to produce. They cannot be pumped in their natural state and advanced technologies are required. Formation of oil-in-water emulsions is one of them. A typical emulsion contains 65% of dispersed phase and has a viscosity lower than 500 mPa.s. Current research is aimed at increasing the crude oil content at reduced costs with still good stability and low viscosity. Consequently, an experimental study was dedicated to the relationship between the structure and the rheological properties of heavy oil emulsions. Particular attention was paid to process parameters employed to prepare emulsions. Depending on the shear device, various emulsions have been obtained, either simple or multiple, monodisperse or bimodal. The resulting viscosity is discussed. It is particularly low when the emulsion is either coarse and unimodal or fine and simple. The highest viscosity is obtained when the emulsion is fine and multiple. The ex...

Preparation method of emulsified fuel oil

Abstract: Provided are an emulsified fuel oil which improves combustion efficiency and reduces emission of pollutants by lowering viscosity of the emulsified fuel oil and reducing the size of emulsified fuel oil particles, thereby greatly increasing the specific surface area of the particles, and a preparation method thereof A preparation method of an emulsified fuel oil comprises: a first process of injecting Bunker A oil, Bunker B oil, or Bunker C oil as heavy oil into a mixer from a raw material tank of which temperature is controllable, adding an emulsifying agent in the heavy oil, sufficiently mixing the heavy oil with the emulsifying agent, injecting water in the mixture, and sufficiently agitating the resulting material to prepare a W/O type emulsion; and a second process of preparing an emulsion containing more uniform nanoparticles from the W/O type emulsion using a mechanical apparatus such as a Homomixer, line mixer, homogenizer, or colloid mill as an emulsifier for improving stability of the W/O type emulsion prepared in the first process The first and second processes may be performed as one process in the mixer or emulsifier The second process may be performed continuously or discontinuously

Emulsified fuel combustion apparatus

Abstract: PROBLEM TO BE SOLVED: To provide an emulsified fuel combustion apparatus with a novel structure capable of improving combustion efficiency of emulsified fuel. SOLUTION: A combustion chamber 16 is partitioned by a partition member 30 having fire resistance in a jetting direction of the emulsified fuel by an injection nozzle 24. Two combustion spaces 36, 38 formed on both sides of the partition member 30 in the combustion chamber 16 are communicated with each other through a communication hole 32 piercing the partition member 30. COPYRIGHT: (C)2009,JPO&INPIT

Formation vessel which forms fuel prepared by emulsifying mixture of liquid fuel such as heavy oil or gas oil optionally mixed with frying oil or regenerated used frying oil or regenerated waste oil, mixing preparation vessel for homogenizing composition of water and oil, or boiler fuel feed apparatus which stably feeds fuel into nozzle and uses feed tank/fuel return apparatus

Abstract: PROBLEM TO BE SOLVED: To provide a method for producing an emulsified fuel, wherein emulsification can be performed without using a surface active agent or an emulsifier, for example, easily available tap water, or the like can be utilized as the water added, water and oil made homogenized and stabilized by means of a mixing preparation vessel is fed to a formation vessel where they form an emulsified fuel, the heating value is equivalent to that of heavy oil itself, and the emission of waste gases such as carbon dioxide can be reduced. SOLUTION: A mixture of a liquid fuel such as heavy oil or gas oil with ordinary water in a volume ratio of 8-26% optionally mixed with frying oil, regenerated frying oil, regenerated waste oil, or the like in a volume ratio of 3-30% is fed to a storage tank. When the oil and water in the storage tank is sent to an emulsion formation vessel, they kept in a state homogenized and stabilized in the mixing preparation vessel of the storage tank is sent to a formation vessel. The oil and water sent to the formation vessel repeat pressurization and collision therein to form an emulsified fuel. COPYRIGHT: (C)2011,JPO&INPIT

Generator for producing emulsion fuel by mixing water to heavy oil, light oil, tempura oil, regenerated oil of waste tempura oil or the like and boiler fuel supply apparatus using the generator

Abstract: PROBLEM TO BE SOLVED: To provide a generator for producing an emulsion fuel which is emulsified in such a state that the ratio of oil to water is uniform and stable, has the same heat quantity as that in heavy oil only and further can reduce sulfur oxide or the like in discharge gas, when adding water to liquid fuel such as heavy boil, light oil, tempura oil, regenerated oil of waste tempura oil or the like to produce the emulsion fuel, by using familiar city water according to a method of adding no emulsifier as the water to be added. SOLUTION: Volume ratio 8 to 26% of ordinary water is mixed to fuel such as heavy oil, light oil, tempura oil, regenerated oil of waste tempura oil or the like and, when oil and water charged into a storage tank are sent to an emulsion generator, the oil and water are sent while being made uniform in a compounding adjusting device of the storage tank. The oil and water sent to the generator are subjected to pressurizing collision to form an emulsified fuel. The emulsified fuel has the same heat quantity as that of heavy oil and perfect combustion is performed. COPYRIGHT: (C)2011,JPO&INPIT

Evaluation of exhaust emission from emulsified fuels in diesel engine

Abstract: Fuel economy along with high thermal efficiency is the main incentive of diesel engine applications. However, pollutant gasses exhausted from diesel engines are considered as the important sources of air pollution. Emulsification the fuel by different percentage of water has been studied in this research and its effect on pollutant emissions has been investigated. Considerable reduction in NOX emission and less specific fuel consumption were observed when emulsified fuels were used. To determine the optimum water/diesel ratio, a factor (SEF) has been defined in this article which demonstrated that emulsified fuel 20% had the best performance comparing to 10%, 15%and neat diesel.

Method and equipment for emulsifying fuel liquid

Abstract: The invention discloses a method and equipment which can mix and emulsify denatured alcohol containing low-content ethanol, or seed oil, or water with petrochemical fuel. The emulsification of liquid fuel comprises the following steps: all fuels to be mixed and emulsified enter respective constant pressure container; the fuels are premixed in a premixing container according to the preset proportion; the mixed fuel is pressurized; the emulsified fuels enter a pressurizing container after the oil-gas separation, thus the emulsified fuel to be combusted is formed. All processes of mixing, transporting and emulsifying of all fuels are all in a mixing state and under the action of various ultrasonic waves, and therefore, the emulsification effect is good. Furthermore, compared with the prior emulsification art, the invention has remarkable effect and economic and social benefits of saving energy and reducing pollution.

Method and apparatus for manufacturing emulsion fuel

Abstract: PROBLEM TO BE SOLVED: To provide a method and an apparatus for manufacturing emulsified fuel, performing stable operation in view of operation. SOLUTION: In this manufacturing method, oil and water subjected to micro-clustering or undulating by a water treatment device are mixed, and emulsified by a fluid emulsifier to continuously manufacture emulsified fuel. The above problem is solved by the method and apparatus for manufacturing emulsified fuel, in which the fluid type emulsifier includes a self-circulation line. COPYRIGHT: (C)2009,JPO&INPIT

Manufacturing installation of emulsified fuel

Abstract: The utility model discloses an emulsified fuel producer. The emulsified fuel producer is a device that prepares emulsified fuel according to a specific sequence in which emulsifier is first added in water and then mixed with fuel oil. A water supply system (3) and an emulsifier supply system (5) are respectively connected with conveying tools (8), (9) and then connected with a first nano-processor (12); a raw oil supply system (7) is connected with a conveying tool (10); at a piping joint (11), the raw oil supply system (7) and the first nano-processor (12) are jointly connected with a second nano-processor (13), which leads to a flow controller (14) and is connected with an emulsified fuel output end (15); and a reprocessing system and an A circulation system or a B circulation system can be added. The utility model can uses various oils as raw oil, such as diesel oil, heavy oil, industrial waste oil and vegetable oil and waste edible oil; the produced emulsified fuel has the advantages of good stability, high combustion efficiency, energy saving and emission reduction; and the emulsified fuel producer, which is automatic and miniaturized, can be designed for and mounted on a fuel oil device and can save space.

Emulsified fuel and process for production of same

Abstract: An emulsified fuel is produced by adding both slaked lime and urea to a system composed of both a fuel oil (which is a liquid fossil fuel) and a functional water prepared by subjecting water to physical treatment, unifying all the components by emulsification, and mixing the obtained emulsion into an ultrafine emulsion. The emulsified fuel brings about reduction in the concentrations of NO x and SO x in exhaust combustion gas even when the combustion system is not provided with a special device for the treatment of exhaust gas.

Combustion apparatus for emulsified fuel

Abstract: PROBLEM TO BE SOLVED: To provide a combustion apparatus for emulsified fuel can obtain approximately the same calorific value as that of petroleum fuel even when the emulsified fuel is used. SOLUTION: A heat resistant metallic flame guiding cylinder 24 is mounted around an outer wall of a member forming an injection port 20 of a burner 16, and a flame injected from the burner 16 is guided to inside of a combustion chamber 14 via an inner space 26 of the flame guiding cylinder 24. When the length from the injection port 20 of the burner 16 to an opening part 30 of the flame guiding cylinder 24 is represented as P and the length from the injection port 20 of the burner 16 to a heat exchanger 18 or an inner wall of a body 12 forming the combustion chamber 14 as Q, 0.3Q≤P is achieved. Thus, emulsified fuel which is not burned by the burner 16 can be completely burned in the inner space 26 of the flame guiding cylinder 24, and the heat quantity by combustion of the emulsified fuel can be made approximately equal to that of petroleum fuel. COPYRIGHT: (C)2010,JPO&INPIT