JPH07318042A - Burning method for heavy oil emulsion fuel - Google Patents

Abstract

PURPOSE:To provide a method for cleanly burning heavy oil emulsion fuel in which atmospheric contamination substance quantity in exhaust gas generated at the time of burning the fuel can be reduced. CONSTITUTION:Oil-in-water heavy oil emulsion fuel emulsified by surfactant blend in which nonionic surfactant having a clouding point of 98 deg.C or higher or (a) nonionic surfactant and (b) at least one type of surfactant selected from anionic surfactant, cationic surfactant and alphameric surfactant are mixed by weight of (a):(b)=0:100-60:40 is so preliminarily heated that a burner base temperature becomes 80-98 deg.C, and then burned.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for burning heavy oil emulsion fuel. More specifically, an oil-in-water type heavy oil emulsion fuel containing heavy oil, water and a specific surfactant as essential components is preheated to a burner source temperature of 80 to 98 ° C and then burned. Thus, it relates to a clean combustion method for reducing the amount of air pollutants in exhaust gas.

[0002]

2. Description of the Related Art In recent years,
Petroleum, which has been used most as a primary energy source, has reached the limit of its reserves and its price soaring, and development of alternative energy for petroleum is required.
On the other hand, interest in the global environment is increasing, and the cleanliness of combustion exhaust gas are also increasing as a social demand. Against this background, as a new fossil fuel, oil sands, bitumen, heavy oils such as petroleum distillation residues and asphalt are being considered as fuels.

However, these heavy oils usually contain vacuum distillation residue of about 420 to 450 ° C. and a heavy fraction of about 60 to 70.
It is an oily substance containing not less than wt% and does not flow as it is or has a high viscosity of tens of thousands of centipoise or more. Therefore, to use as fuel, 280-300 ℃
It is a fuel that is extremely difficult to use because it is difficult to handle and atomize unless it is heated to a high temperature, and it is prone to blockage troubles in the piping of combustion boilers. An oil-in-water emulsion is effective as a method for making such a highly viscous heavy oil fluid even at room temperature.

However, when the oil-in-water emulsion is burned, there are problems that the oil film is wrapped in a water film, the ignitability is poor, and the unburned content increases. In order to solve such a problem, before burning the oil-in-water emulsion, preheating it to improve the fluidity,
Improvements have been made to the spray conditions from the burners. For example, Japanese Laid-Open Patent Publication No. 63-501578 discloses a combustion method in which a pitch emulsion in water is preheated to at least 60 ° C. prior to combustion. Further, in JP-A-63-54498, an emulsion of bitumen crude oil is heated to 20 to 80 ° C,
A method is disclosed in which the material is preferably preheated to 20 to 60 ° C and burned. However, in these methods, the optimum temperature for preheating is about 60 ° C., and no consideration is given to temperatures above that. That is, in the conventional emulsion, when heated, it causes aggregation and phase separation, and can be heated only to about 60 ° C., sufficient combustibility cannot be obtained, and the amount of dust in exhaust gas increases, which is a problem. Therefore, an object of the present invention is to provide a clean combustion method capable of reducing the amount of atmospheric pollutants in exhaust gas generated during the combustion of heavy oil emulsion fuel.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have prepared an oil-in-water type heavy oil emulsion fuel emulsified with a specific surfactant in a specific temperature range. The present invention has been completed by discovering that the concentration of nitrogen oxides and soot in the exhaust gas can be controlled within a target value, for example, within a regulation standard of the Air Pollution Control Act by burning after heating.

That is, the present invention relates to the method for burning heavy oil emulsion fuel described in 1) to 3) below. 1) It is characterized in that an oil-in-water heavy oil emulsion fuel emulsified with a nonionic surfactant having a cloud point of 98 ° C or higher is preheated to a burner source temperature of 80 to 98 ° C and then burned. Combustion method of heavy oil emulsion fuel. 2) (a) a nonionic surfactant, and (b) at least one surfactant selected from anionic surfactants, cationic surfactants and amphoteric surfactants,
(a): (b) = oil-in-water type heavy oil emulsion fuel emulsified with a surfactant mixture mixed in a weight ratio of 0: 100 to 60:40, the burner source temperature becomes 80 to 98 ° C. A method for burning heavy oil emulsion fuel, characterized in that it is preheated and then burned. 3) The apparent viscosity when preheated is 100 s ^-1 shear rate.
The method for burning heavy oil emulsion fuel according to 1) or 2) above, wherein the fuel oil is 1 to 50 cP.

The effect of reducing the concentration of soot and nitrogen oxides in exhaust gas by the combustion method of the present invention is estimated as follows. Dozens of% for heavy oil emulsion fuel
Water is included. This water is suddenly heated in the combustion furnace and bumps to boil off the oil existing in the vicinity. This phenomenon is called secondary atomization of oil droplets due to steam explosion. In a direct fuel injection type combustor such as a boiler or a heating furnace, oil droplets sprayed from a burner are secondary atomized by steam explosion during combustion. Due to the effect of secondary atomization due to this steam explosion and the effect of the existence of water itself,
The combustion pattern of oil droplets changes greatly. That is, the atomization improves the contactability / mixability with oxygen, and the promotion of the water-gas reaction improves the combustibility, thereby significantly reducing the generation of soot and dust. In addition, the reduction of the flame temperature due to the latent heat of vaporization of water and the short-time passage of fine particles in the high temperature range will significantly reduce the thermal NO _x . The secondary atomization due to this steam explosion is
Heavy oil emulsion fuel, burner source temperature 80 ~ 98 ℃
When preheated to improve the fluidity,
It is presumed that it can occur more effectively and can simultaneously reduce soot and nitrogen oxides.

The heavy oil emulsion fuel in the present invention is an oil-in-water type, and its composition is heavy oil, water, and a nonionic surfactant having a cloud point of 98 ° C. or higher, or (a) a nonionic interface. An active agent and (b) at least one surfactant selected from anionic surfactants, cationic surfactants and amphoteric surfactants, (a): (b) = 0: 100-
The surfactant blended in a weight ratio of 60:40 is an essential ingredient. In addition to these components, if necessary, a polymer stabilizer, a water-soluble polymer, a polyhydric alcohol, an oil / fat, a fatty acid, a fatty acid ester, an oligosaccharide or an oligosaccharide derivative, etc. may be added.

The composition of the heavy oil emulsion fuel used in the present invention is not particularly limited, but preferably 50 to 80% by weight of heavy oil, 10 to 50% by weight of water, and a surfactant. Is 0.01 to 10% by weight. By setting the heavy oil concentration to 50 to 80% by weight, it is possible to suppress the apparent viscosity when preheated to 80 to 98 ° C within the range of ¹ to 50 cP at a shear rate of 100 s ^-1 . The purpose of preheating is to lower the viscosity of the heavy oil emulsion to improve the spray state during combustion, and to raise the temperature of the heavy oil, which has poor ignitability, to improve the combustibility. To be This apparent viscosity
If it exceeds 50 cP, a good spray state cannot be obtained. Also, if it is less than 1 cP, the viscosity during storage is low and there is a risk that stability may be a problem.

In the present invention, a disperser such as a homomixer, a homogenizer, a line mixer, a milder, a static mixer or a motionless mixer can be used for preparing the heavy oil emulsion. In the present invention, after preparing a heavy oil emulsion consisting of heavy oil, water and a specific surfactant as described above, prior to combustion, preheating is performed so that the burner source temperature becomes 80 to 98 ° C. It is necessary to. If the preheating temperature is less than 80 ° C, the effect of improving the ignitability of heavy oil is not sufficient. Further, if the temperature exceeds 98 ° C, depending on the composition of the emulsion, agglomeration or separation occurs, and there is a risk of clogging the nozzle.

In the present invention, the burner used for combustion may be the burner used for combustion of petroleum-based fluid fuel, but a high pressure atomization burner is particularly preferable.

As the surfactant in the present invention, when the nonionic surfactant is used alone, among the nonionic surfactants listed below, those having a cloud point of 98 ° C. or higher are used. When used in combination with other nonionic surfactant, (a) nonionic surfactant,
(b) at least one surfactant selected from anionic surfactants, cationic surfactants and amphoteric surfactants, and (a): (b) = 0: 100 to 60:40 When blended in a weight ratio, all of the nonionic surfactants listed below can be selected and used. <Nonionic Surfactant> (i) An alkylene oxide adduct of a compound having a phenolic hydroxyl group such as phenol, cresol, butylphenol, nonylphenol, dinonylphenol, dodecylphenol, paracumylphenol, and bisphenol A. (Ii) An alkylene oxide adduct of a formaldehyde condensate of a compound having a phenolic hydroxyl group such as alkylphenol, phenol, metacresol, styrenated phenol, and benzylated phenol. The average degree of condensation is
It is 1.2 to 100, preferably 8 to 40.

(Iii) An alkylene oxide adduct of a monohydric aliphatic alcohol having 2 to 50 carbon atoms. (Iv) An alkylene oxide adduct of a monovalent aliphatic amine having 2 to 50 carbon atoms. (V) A block or random addition polymer of alkylene oxide. (Vi) Alkylene oxide adduct of polyhydric alcohol. (Vii) An alkylene oxide adduct of an ester of a polyhydric alcohol and a fatty acid having 8 to 18 carbon atoms.

(Viii) An alkylene oxide adduct of a polyvalent amine having a plurality of active hydrogens such as ethylenediamine, tetraethylenediamine, polyethyleneimine (molecular weight 600 to 10,000). (Ix) A product obtained by adding an alkylene oxide to a mixture of 1 mol of a triglyceride type oil and fat and 0.1 to 5 mol of a polyhydric alcohol and / or water.

The polyhydric alcohols (vi) and (vii) include glycerin, trimethylolpropane, pentaerythritol, sorbitol, sucrose, polyglycerin, ethylene glycol, polyethylene glycol, propylene glycol, polypropylene glycol, etc. It is illustrated.

The solubility of these nonionic surfactants in water suddenly deteriorates at a certain temperature. This temperature is called a cloud point and can be measured by the following method. A 2% by weight aqueous solution of a nonionic surfactant is prepared, and the temperature is slowly raised with stirring. As the temperature rises, the water molecules bound to the alkylene oxide chain of the nonionic surfactant are dissociated and the hydrophilicity decreases, and finally the water dissolves in water and cannot exist, and the nonionic surfactant precipitates.
This point can be detected by sudden clouding of the aqueous solution,
The temperature at that time is the cloud point. For example, in the case of ethylene oxide adduct of nonylphenol, the cloud point of ethylene oxide 12 mol adduct is 80 ° C., and the cloud point becomes higher as the number of added ethylene oxide mols increases.

When an oil-in-water emulsion emulsified with a nonionic surfactant is heated to a temperature above the cloud point of the surfactant, the surfactant cannot exist in the water phase and the interfacial tension between water and oil is increased. Grows and the emulsion is easily broken and separation occurs. The same thing happens with heavy oil emulsions, and when heated, high-viscosity heavy oil separates,
It causes inconvenient troubles such as line blockage. Therefore, in the present invention, in order to improve the flammability, even if preheating to 80 ~ 98 ℃ in the burner source before combustion, in order to prevent the separation of the emulsion does not occur, the nonionic surfactant used The cloud point must be 98 ° C or higher.

Further, (a) a nonionic surfactant, (b)
At least one surface active agent selected from anionic surface active agents, cationic surface active agents and amphoteric surface active agents in a weight ratio of (a) :( b) = 0: 100 to 60:40. When used in combination, it became clear that a stable heavy oil emulsion can be obtained which does not cause problems such as separation and aggregation even when the heavy oil emulsion is heated to 80 to 98 ° C. Therefore, in the present invention, such a surfactant composition may be used in place of the nonionic surfactant having a cloud point of 98 ° C. or higher. When the weight ratio of (a) and (b) is out of the above range, heating or heating the heavy oil emulsion to 80 to 98 ° C causes separation or aggregation, which is not preferable. Examples of the anionic surfactant, cationic surfactant and amphoteric surfactant that can be used here include the following.

<Anionic Surfactant> (I) Formaldehyde condensate of sulfonic acid or sulfonate of aromatic ring compound such as naphthalene, alkylnaphthalene, alkylphenol and alkylbenzene. Preferably, the average degree of condensation of formaldehyde is 1.2-100
Is. (II) Lignin sulfonic acid, lignin sulfonate, derivatives thereof, formaldehyde condensates of lignin sulfonic acid and sulfonic acids of aromatic compounds such as naphthalene and alkylnaphthalene, and salts thereof. Preferably, the average degree of condensation of formaldehyde is 1.2-50. (III) Polystyrene sulfonic acid or a salt thereof, a copolymer of styrene sulfonic acid and another copolymerizable monomer, and a salt thereof. Preferably the molecular weight is between 500 and 500,000. (IV) A dicyclopentadienesulfonic acid polymer or a salt thereof. Preferably, the molecular weight of the polymer is 500 to 500,000.

(V) A copolymer of maleic anhydride or / and itaconic anhydride with another copolymerizable monomer, and an acid or salt thereof. Preferably the molecular weight is between 500 and 500,000. (VI) Maleates of liquid polybutadiene and salts thereof.
Preferably, the liquid polybutadiene has a molecular weight of 500,000 to 200,000.

(VII) The following anionic surfactant having one or two hydrophilic groups in the molecule. (a) Sulfate ester salt of an alcohol having 4 to 18 carbon atoms. (b) Alkane, alkene or / and alkylaryl sulfonic acid having 4 to 18 carbon atoms or a salt thereof. (c) Sulfates or phosphates of alkylene oxide adducts of compounds having one or more active hydrogens in the molecule, and salts thereof. (d) A sulfosuccinate which is an ester of a saturated or unsaturated fatty acid having 4 to 22 carbon atoms. (e) Alkyl diphenyl ether disulfonic acid or a salt thereof. The alkyl group is an alkyl group having 8 to 18 carbon atoms. (f) Rosin acid or a salt thereof. Tall oil mixed acid which is a mixed acid of rosin acid and higher fatty acid and its salt. (g) Alkane or alkene fatty acid having 4 to 18 carbon atoms and salts thereof. (h) An α-sulfo fatty acid ester salt represented by the following general formula (1).

[0022]

[Chemical 1]

However, R ₁ is an alkyl or alkenyl group having 6 to 22 carbon atoms, R ₂ is an alkyl group having 1 to 22 carbon atoms, and M is 1
A divalent or divalent metal atom, NH ₄ or an organic amine, and n represents 1 or 2.

Regarding the compounds (I) to (VII), as salts, lower amines such as ammonium, monoethanolamine, diethanolamine, triethanolamine and triethylamine, alkali metals such as sodium, potassium, magnesium and calcium, or alkalis. Examples are earth metals.

<Cationic Surfactant and Amphoteric Surfactant> (I) An alkyl or / and alkenylamine salt obtained by neutralizing an alkyl or / and alkenylamine having 4 to 18 carbon atoms with an inorganic acid or an organic acid. (II) A quaternary ammonium salt represented by the following formulas (2) to (4).

[0026]

[Chemical 2]

[0027]

[Chemical 3]

[0028]

[Chemical 4]

(III) An alkyl betaine represented by the following formula (5).

[0030]

[Chemical 5]

(IV) An alkylamine oxide represented by the following formula (6).

[0032]

[Chemical 6]

(V) An alkylalanine represented by the following formula (7).

[0034]

[Chemical 7]

(VI) A polyamate represented by the following formula (8) or (9).

[0036]

[Chemical 8]

(VII) A polyamine salt represented by the following formula (10) or (11).

R ₉ NHC ₃ H ₆ NHX '(10) R ₉ NH (C ₃ H ₆ NH) ₂ X' (11) (wherein R ₉ has the same meaning as described above, X'is an inorganic acid or It is an organic acid.) (VIII) An imidazoline-type amphoteric surfactant represented by the following formula (12).

[0039]

[Chemical 9]

(IX) A sulfobetaine-type amphoteric surfactant represented by the following formula (13).

[0041]

[Chemical 10]

The content of the surfactant in the heavy oil emulsion is preferably 0.01 to 10% by weight. If the blending amount is smaller than this, the emulsification and emulsion stability of the heavy oil are insufficient, and if the blending amount is larger than this, not only is it uneconomical, but foaming during emulsification and particle size control are difficult, which is not preferable.

The heavy oil used in the present invention is an oil that has poor fluidity at room temperature and does not flow unless heated to a high temperature, and includes the following oils. (1) Mixtures of petroleum-based asphalts and their oils (2) Various treated petroleum-based asphalts, their intermediate products, residues, and mixtures thereof (3) High pour point oils that do not flow at room temperature (4) Petroleum-based tar pitch And oil mixture thereof (5) Bitumens, natural asphalt, orinocotal If further limited, those containing 90% by weight or more of a component having a boiling point of 340 ° C or higher at normal pressure are preferable.

In the present invention, if necessary, a polyhydric alcohol and / or a polymer stabilizer may be added for the purpose of further improving the stability. Any polyhydric alcohol may be used as long as it has two or more hydroxyl groups in the molecule and is soluble in water. For example, glycerin, polyglycerin, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, sorbitol,
Glucose and the like. The content of the polyhydric alcohol in the emulsion is preferably 0.1 to 50% by weight. As the polymer stabilizer, various water-soluble polymers having a molecular weight of 10,000 or more shown in Table 1 can be blended, and the blending amount of the polymer stabilizer in the emulsion is preferably 0.005 to 3% by weight.

[0045]

[Table 1]

[0046]

As described above, according to the method for burning heavy oil emulsion fuel according to the present invention, it is difficult to clean the exhaust gas due to the large amount of nitrogen, residual carbon, heavy metals, etc. Heavy oils such as bitumen and asphalt that have not been effectively used as energy,
This is a revolutionary combustion technology that can be used like petroleum-based fluid fuels.

[0047]

EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 3 and Comparative Examples 1 to 8 Using the following heavy oils, water and surfactants as raw materials, heavy oil emulsion fuels were prepared by the following method, and a combustion test was conducted by the following method. . The results are shown in Table 3. <Materials used> Heavy oil: Asphalt extracted from Arabian light crude oil (specific gravity 1.018, viscosity 1080cP / 100 ° C, softening point 29 ° C,
Penetration 400/25 ℃) Water: Water supply Surfactant: Nonionic surfactant Emulgen 920 (Polyoxyethylene nonylphenyl ether, Kao Co., cloud point 98 ° C) Emulgen 911 (Polyoxyethylene nonylphenyl) ether, manufactured by Kao Corporation, cloud point 74 ° C.) the raw material <preparation of a heavy oil emulsified fuel> weighed as shown in Table 1, the asphalt into a reaction vessel of 5 m ³ (So径1.9 m), water and Each of the surfactants was heated to 80 ° C. and then charged, and the mixture was stirred for 60 minutes while maintaining the temperature at 80 ° C. The stirring blade type is a Fadler blade, the blade diameter is 1.1 m, and the rotation speed is 64 rpm. After the completion of the preliminary stirring, a PL-SL type line mixer manufactured by Tokushu Kika Kogyo Co., Ltd. was used to emulsify in a batch circulation system.
The rotation speed of the mixer was 3600 rpm, and the emulsification time was 4 hours. After emulsification, cool to 20 ℃ over 10 hours,
Two kinds of heavy oil emulsion fuel of 00 kg were prepared and used as an emulsion fuel for combustion test. Hereinafter, these fuels are referred to as fuels 920 and 911.

[0049]

[Table 1]

<Combustion test method> A combustion test was carried out using the two types of heavy oil emulsion fuels obtained above and C heavy oil as a control. Table 2 shows the general properties of the above two types of heavy oil emulsion fuels and C heavy oil used in the test.

[0051]

[Table 2]

These fuels are 60 for fuel 920 and 911,
The heavy fuel oil C was preheated to 90 ° C. at temperatures of 70, 75, 80, 85, and 90 ° C. and burned. A natural circulation type water can boiler (manufactured by Kawasaki Heavy Industries, Ltd.) was used for combustion, and a steam spray internal mixing type (manufactured by Volcano) was used as a burner. The standard flow rate of fuel is 1,000 liters / hr for heavy fuel oil C
In 911 and 911, the combustion heat quantity is almost the same as C heavy oil.
The flow rate was 1,400 liter / hr. The atomizing condition is
Steam temperature 190 ℃, flow rate 100 liters / hr, pressure = 6.
The standard was 0 kg / cm ² and the fine adjustment was made according to the combustion state. Amount of dust in exhaust gas (JIS Z-8808) and amount of nitrogen oxides
(JIS K-0104) was measured, and the state in which unburned components were scattered and adhered to the glass surface of the observation window provided at the bottom of the furnace was observed.
The oxygen concentration in the exhaust gas was about 4%.

[0053]

[Table 3]

Note) *: The burner nozzle was blocked due to the destruction of the emulsion.

Examples 4 to 9 and Comparative Examples 9 to 11 Next, the effects of the composition of the surfactant of the present invention will be shown by a heating stability test which is found to correlate with the amount of unburned substances deposited in the combustion test. . Using the following heavy oil, water and surfactant as raw materials, a heavy oil emulsion fuel was prepared by the following method, and a heating stability test was conducted by the following method. The results are shown in Table 5. <Materials used> Heavy oil: Asphalt same as in Example 212 g Water: Ion-exchanged water 86.0 g Surfactant: Surfactant having the composition shown in Table 4

[0056]

[Table 4]

Note) * 1: Emulgen 921 polyoxyethylene nonyl phenyl ether (manufactured by Kao Corporation, cloud point 100 ° C or higher) * 2: Emulgen 920 polyoxyethylene nonyl phenyl ether (manufactured by Kao Corporation, cloud point 98) ℃) * 3: Emulgen 911 polyoxyethylene nonylphenyl ether (manufactured by Kao Corporation, cloud point 74 ° C) * 4: Mighty 150 Naphthalenesulfonic acid formalin condensate (Kao Corporation)
* 5: Acetamine 86 stearylamine acetate (manufactured by Kao Corporation) * 6: Amphitol 86B Stearyl dimethyl betaine (manufactured by Kao Corporation) * 7: CMC1190 carboxymethyl cellulose Na salt (manufactured by Daicel Chemical Industries, Ltd.) < Preparation method of heavy oil emulsion fuel> 800 ml of the above raw materials
It was weighed in a stainless steel container, and an emulsion was prepared at a temperature of 80 ° C. using a TK homomixer (with a low-viscosity stirring blade) manufactured by Tokushu Kika Kogyo Co., Ltd. Rotation speed of the stirring blade is 10,0
The stirring time was set to 00 rpm and the stirring time was 3 minutes.

<Heat Stability Test> 50 g of the prepared heavy oil emulsion is weighed in a 100 ml cylinder and immersed in a warm water bath at 80 ° C. A very small amount of liquid paraffin was added on the surface to prevent evaporation of water. After soaking in a warm water tank at 80 ° C for 1 hour, the mixture was allowed to cool to room temperature, the sample was passed through a 100 mesh sieve, and the amount of heavy oil remaining on the sieve was measured by the following method. Method for measuring the residue on 100 mesh sieve 50 g of ion-exchanged water is added to the sample weighed in a cylinder and mixed uniformly, and then the mixture is passed through a 100 mesh JIS standard sieve (JIS Z 88) having a diameter of 8 cm. Ion exchange water in the same cylinder
While washing the cylinder with 50 g, wash the emulsion on the sieve. After washing three times, the residue on the sieve is dried and weighed.

[0059]

[Table 5]

As is clear from Table 5, of the examples of the present invention.
It can be seen that the residue on the 100-mesh screen is very small compared to the comparative example. As shown in FIG. 1, such a residue on the 100-mesh screen has a correlation with the amount of unburned substances adhered in the combustion test conducted in Example 1. When the residue on the 100-mesh screen is small, the combustion efficiency is low. It turns out that is good.

[Brief description of drawings]

FIG. 1 is a diagram showing a correlation between a residue on a 100-mesh screen and an amount of unburned substances attached.

Claims (3)

[Claims] 1. An oil-in-water type heavy oil emulsion fuel emulsified with a nonionic surfactant having a cloud point of 98 ° C. or higher is preheated to a burner source temperature of 80 to 98 ° C. and then burned. A method for burning heavy oil emulsion fuel, comprising: 2. (a) a nonionic surfactant, and (b) at least one surfactant selected from anionic surfactants, cationic surfactants and amphoteric surfactants, a): (b) = 0.100 to 60:40 The oil-in-water type heavy oil emulsion fuel emulsified with the surfactant mixture mixed at a weight ratio of 80: 98 ° C A method for burning a heavy oil emulsion fuel, characterized in that the fuel is burned after preheating. 3. The method for burning a heavy oil emulsion fuel according to claim ¹ , wherein the apparent viscosity when preheated is ¹ to 50 cP at a shear rate of 100 s ⁻¹ .