JPH1121571A - W/o heavy oil/water emulsion fuel, additive therefor, emulsifying equipment and method for combusting heavy oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an emulsion fuel which can be stored for a long term, has improved efficiency of combustion and prevents the exhaustion of harmful substances by stably dispersing in the form of droplets having a specified diameter the aqueous phase of a W/O heavy oil/water emulsion prepared by dispersing water containing a specified amounts of an inorganic base and an inorganic salt which are water-soluble and are of non-ammonia-based types in heavy oil. SOLUTION: This fuel contains 1-70 vol.% water phase and 0.3-40 wt.%, based on the water phase, in total, inorganic base and inorganic salt. The water phase has a diameter of 20 μm or below. The inorganic base and the inorganic salt are desirably sodium hydroxide and sodium chloride. A water supply pipe 31 and a supply pipe 32 for a concentrated aqueous solution of additives join together at a nozzle mixer 10 and further unite with fuel C supply pipe 34 at the mixer 10. An in-line mixer 2 is inserted serially into the middle of a pipe 35. Pumps P1-3, valves V1-4 and control needle valves NV 1 and 2 realize a specified mixing ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel oil-water emulsion fuel in which fuel oil is made into an emulsion with water in order to improve the combustion characteristics or handleability of fuel oil. The present invention also relates to an additive for emulsifying or improving combustion characteristics for this purpose, and to an emulsifying apparatus for producing this emulsion. Further, the present invention relates to a method for burning heavy oils using such a material.

[0002] The present invention is, in particular, a W / O (water in oil) heavy oil-water emulsion fuel in which water is dispersed in a heavy fuel oil such as heavy fuel oil C, wherein an inorganic additive is used. About things.

[0003]

2. Description of the Related Art In large boilers used for power generation, large ships, steam generation in large-scale factories, and the like,
Heavy heavy oil such as heavy B oil or heavy C oil is mainly used. This is because these heavy fuel oils are inexpensive, although they need to be heated to 80 ° C. or higher during boiler combustion.

[0004] However, these heavy fuel oils not only have a higher content of sulfur and the like than the gas and light fuel oils, and are difficult to completely burn. A large amount of incomplete combustion products such as substances, carbon monoxide, and soot were generated, causing air pollution. If such measures are not taken and air pollution is left unchecked, it will threaten not only humanity but also the survival of animals and plants on earth.

For this reason, boilers have been improved, and pollution control devices such as desulfurization devices and soot removal devices have been installed.

[0006] However, such pollution control devices require considerable equipment, maintenance, and management effort.
Further, the efficiency of removing harmful substances is not perfect.

Further, since the combustion in the boiler does not lead to complete combustion, incomplete combustion products adhere to the boiler and the exhaust pipe, which adversely affects the boiler equipment, thereby increasing not only the maintenance cost but also the thermal efficiency. Was causing the decline.

[0008]

It has long been known that when water is dispersed in heavy oil to make a heavy oil-water emulsion fuel, the combustion efficiency is increased. Therefore, an emulsifier (surfactant) is used. The method used and the method using strong mechanical mixing have been tried and partially put into practical use.

However, in the case of using an emulsion fuel dispersed with an emulsifier, when a combustion device for heavy fuel oil C is used, it is heated in a reserve tank of the combustion device for heavy fuel oil C which is heated to 80 ° C. or more before being supplied to the boiler. However, there is a problem that heavy oil and water are separated.

In addition, when mechanical mixing is used, a mixing and stirring device must be attached to the combustion device so as to perform stirring and mixing immediately before supply to the boiler, which imposes a burden on capital investment and maintenance. large.

Further, in the above-mentioned conventional method, it cannot be expected at all that the emission of sulfur oxides is suppressed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and can be stored for a long period of time, can be stably maintained under heating at 80 ° C. or more, improves combustion efficiency, and discharges harmful substances. To provide a heavy oil-water emulsion fuel capable of sufficiently suppressing the occurrence of water.

[0013]

The fuel oil-water emulsion fuel according to claim 1 is a W / O type heavy oil-water emulsion fuel in which water is dispersed in heavy oil such as C heavy oil. A water-soluble and non-ammonia-based inorganic base and an inorganic salt, or an additive comprising any one of these, containing 0 to 70% by volume of a phase in an aqueous phase in total of the inorganic base and the inorganic salt. 0.3 to 40% by weight, characterized in that at room temperature the water phase is stably dispersed with a diameter of substantially 20 μm or less.

[0014] With the above configuration, long-term storage is possible and stable holding under heating at 80 ° C or higher is possible.
3. The heavy oil according to claim 2, wherein the combustion characteristics can be improved.
The water oil according to claim 1, wherein the fuel is a water emulsion fuel.
The water emulsion fuel is characterized in that the additive contains an inorganic base or a basic inorganic salt in an amount of 0.2% by weight or more based on the whole emulsion fuel.

According to the above configuration, the sulfur oxides can be absorbed and the emission can be suppressed, and the corrosion of the piping can be suppressed.

The fuel oil-water emulsion fuel according to claim 3 is characterized in that, in the fuel oil-water emulsion fuel according to claim 2, the additive comprises sodium hydroxide and sodium chloride.

According to the above configuration, the ash generated by the addition of the inorganic additive hardly sticks to the wall of the boiler or the exhaust pipe. Therefore, the harmful effects due to the addition of the inorganic additive are sufficiently prevented.

According to a fourth aspect of the present invention, there is provided a fuel oil-water emulsion fuel according to the first aspect, wherein the additive comprises calcium chloride.

The additive for a heavy oil-water emulsion fuel according to claim 5 is an additive for dispersing water in a heavy oil such as heavy fuel C to produce a W / O type heavy oil-water emulsion fuel. So, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium chloride,
It is characterized by comprising at least one compound selected from the group consisting of potassium chloride and calcium chloride.

[0020] In the emulsifying apparatus for producing a heavy oil-water emulsion fuel according to claim 6, water or an aqueous solution is dispersed in a highly viscous heavy oil such as heavy fuel C to produce a W / O type heavy oil-water emulsion fuel. An emulsifying apparatus for supplying the water or the aqueous solution into the heavy oil, a tip of a nozzle is disposed at a substantially center of a flow path of the heavy oil, in a direction in which the heavy oil flows, and mixed by the nozzle. The heavy oil-water mixture is further mixed in a channel provided with baffles or in a meandering channel.

With the above configuration, for heavy oil of high viscosity,
Low-viscosity water or an aqueous solution of an additive with low affinity can be easily and reliably mixed, and a complicated stirring device such as a rotary stirring blade or a meshing gear is not required. Therefore, low cost and high reliability can be realized.

According to a seventh aspect of the present invention, there is provided a method of burning heavy oils in which an inorganic aqueous solution is dispersed and burned in heavy oils such as heavy oil C or heavy oil from an oil sand. The mixture of the heavy oil and the inorganic aqueous solution contains the aqueous inorganic solution in an amount of 1 to 70% by volume, and the mixture is blended so that the water-soluble inorganic substance is contained in an amount of 0.1 to 5% by weight. After mixing, the resulting mixture is once held at a temperature of 80 ° C. or higher and then supplied to a combustion furnace.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION The heavy oil-water emulsion fuel of the present invention is a W / O type heavy oil-water emulsion fuel in which water is dispersed in a heavy oil such as C heavy oil, wherein the water phase is 1-70. % By volume, preferably 20 to 50% by volume, more preferably 1%
0 to 30% by volume, containing 0.3 to 40% by weight, preferably 1 to 30% by weight, more preferably 10 to 30% by weight of a suitable inorganic additive in the water phase, and is stored for a long time. A possible stable emulsion is formed.

The amount of the inorganic additive added to the whole heavy oil-water emulsion fuel is 0.2 to 10% by weight, preferably 0.3 to 5% by weight.

As the heavy oil to be used, C heavy oil having low fluidity at normal temperature is suitable. However, heavy oil obtained from an oil sand can be used in exactly the same manner.

As the inorganic base and the inorganic salt used in the additive of the present invention, preferred are sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium chloride, potassium chloride, and calcium chloride. These are water-soluble and inexpensive.

As the additives of the present invention, from the above,
It is preferable to select and use an inorganic base or a basic inorganic salt such as sodium hydroxide or potassium carbonate. in particular,
It is preferable to use sodium hydroxide and sodium chloride in combination.

[0028] When sodium hydroxide and sodium chloride are used in combination, for example, a preferable composition is such that the volume percentage of the aqueous phase is 10 to 30 volume%, and the concentration of sodium hydroxide and sodium chloride in the aqueous phase is as follows. , Each one
0 to 20% by weight.

When mixing the water containing the additive of the present invention with heavy fuel oil C, the temperature of the water is preferably 30 to 80 ° C.

An embodiment of the present invention will be described below.

<Additives> As additives, sodium hydroxide and sodium chloride were used in combination. In particular, an aqueous solution having the composition and properties shown in Table 1 was used.

[0032]

[Table 1] <Production of Fuel Oil-Water Emulsion Fuel> A fuel oil-water emulsion fuel was produced by first adding and mixing the aqueous solution of the additive shown in Table 1 with water, and then adding and mixing water containing the additive with Fuel C oil.

In the case of producing an emulsion fuel, the ratios of the volume of water to the total volume of heavy fuel oil C and water were set to 20, 30 and 50%, respectively, and these were set to Examples 1 to 3, respectively.
In any case, the net weight of the aqueous additive solution in Table 1, that is,
It was added so that the total weight of sodium hydroxide and sodium chloride was 0.3% of the total weight of the heavy oil-water emulsion fuel.

An emulsifying apparatus used for producing such a heavy oil-water emulsion fuel will be described with reference to FIGS.

FIG. 1 shows a piping diagram of the emulsifying apparatus.

As shown in the figure, a supply pipe 32 for a concentrated aqueous solution of an additive is connected to a water supply pipe 31 by a nozzle mixer 10.
In the nozzle mixer 10
In the nozzle mixer 1, the supply pipe 33 of the water containing the additive from the water merges with the C heavy oil supply pipe 34. And the pipe 3 for the C heavy oil-water mixture from the nozzle mixer 1
In the middle of 5, two inline mixers 2 are inserted in series.

As shown in the figure, pumps P1, P2
And P3 are provided in supply pipes 32, 33 and 35, respectively, and automatic valves V1, V2, V3 and V4 are provided in supply pipes 31, 33, 34 and 35, respectively. In addition, automatic control needle valve NV
1 and NV2 are provided before the nozzle mixers 10 and 1 in the supply pipes 32 and 33. By means of these pumps and valves, constant-volume supply for realizing a predetermined mixing ratio is realized.

FIG. 2 is a sectional perspective view of the nozzle mixer 1. Although the nozzle mixer 1 for mixing the water containing the additive into the heavy fuel oil C is shown, the nozzle mixer 10 for mixing the concentrated aqueous solution of the additive into the water has exactly the same structure.

As shown in FIG. 2, the supply pipe 34 for heavy fuel oil C
And a pipe 35 for C heavy oil / water mixture having substantially the same diameter as the joint section 12 having a diameter slightly larger than these pipes.
Connect with A pipe 34 is connected to the joint 12.
And 35, the supply pipe 33 of the water containing the additive having a smaller diameter than the pipes 34, 35 penetrates.

In the joint portion 12, heavy fuel oil C flowing from the pipe 34 to the pipe 35 flows on both sides of the pipe 33 arranged so as to block a substantially central portion of the flow path (the front side and the back side in the drawing). It will make a detour.

In the pipe 33 lying in the cavity of the joint portion 12, at a position corresponding to substantially the center of the entire C fuel oil supply flow path, the addition nozzle 11 whose tip is directed toward the pipe 35, that is, on the downstream side. Is provided. By this addition nozzle 11, the pipe 3
Additive water from 3 is added.

On the other hand, the tip of the pipe 33 that has penetrated the joint portion 12 and has come out (usually arranged at the lower end).
Is closed by a blind screw cap 13 for draining.

FIGS. 3 and 4 are a perspective sectional view and a radial sectional view, respectively, of the in-line mixer 2. FIG.
Is a cross-sectional perspective view taken in the direction of the pipe flow path slightly before the center axis of the pipe. A plurality of mixing blade-type fixed stirring blades (baffles) 21 are arranged in the pipe 22, whereby the liquid passing through the pipe is stirred and mixed. Each fixed stirring blade 21 has a line segment shape that bisects the inside of the pipe 22 in a radial cross section, and the line segment is gradually rotated to 180 degrees for a predetermined length in the pipe flow path direction. It is shaped like a ribbon. The adjacent fixed stirring blade 21
The two fixed stirring blades 21 contact each other at the center of the pipe flow path.
Are arranged so that the edges are orthogonal to each other.

Since the emulsifying device is configured as described above,
The high-viscosity C heavy oil and the low-viscosity additive-containing water are easily and reliably mixed by the simple and rational nozzle mixer 1 and the in-line mixer 2. In particular, there is no need for an external force other than liquid feeding by a pump, and there is no need for a complicated stirring device such as a rotary stirring blade or a meshing gear.
Therefore, low cost and high reliability can be realized.

<Analytical Value of Fuel> The analytical values of the fuel oil-water emulsion fuels of Examples 1 to 3 were analyzed together with the analytical values of C heavy oil.
It is shown in Table 2. The analysis was performed by requesting the analysis office of the Japan Institute of Energy.

[0046]

[Table 2] From the values of the kinematic viscosity at the bottom of Table 2 above, it is known that the viscosity of the heavy oil-water emulsion fuel is higher than that of the C heavy oil. It is considered that such a high viscosity is an important cause for forming a stable emulsion as described below.

<Evaluation of Emulsion Stability> Next, a heavy oil-water emulsion fuel having the same composition as in Example 3 was subjected to a centrifugal separation test and a microscopic test.

These tests were carried out by requesting the RIKEN Osaka Branch through the Japan Maritime Inspection Association. The preparation of the emulsion fuel for these tests is described in Table 1, C
This was carried out by adding an equivalent amount of water at 80 ° C. to heavy oil, adding 0.3% by net weight of an additive having the composition shown in Table 1, and mixing with a mixer. Then, it was subjected to a test after storage at 25 ° C. for 7 days.

The centrifugation test was performed as follows. After heating 100 ml of the emulsion fuel in a water bath at 60 ° C. or 80 ° C. for 20 minutes, a centrifuge adjusted to 60 ± 2 ° C. or 80 ± 2 ° C. at 600 G (600 × gravity acceleration).
Rotated for 0 minutes. Then, the volume of the separated water was read.

Table 3 shows the results of the centrifugation test.

[0051]

[Table 3] FIG. 5 shows the results of microscopic photographing. The observation temperature is 25 ° C. It is known that the water phase is stably dispersed with a diameter of 10 μm or less.

As is known from these results, the heavy oil-water emulsion fuel of the present embodiment forms an extremely stable emulsion.

<Test furnace combustion test> Next, a combustion test was performed on the heavy oil-water emulsion fuel of Example 2.

The combustion test was performed on request from Chugai Furnace Industry Co., Ltd. Combustion Laboratory. The test furnace is No. 6 furnace of the Institute,
The burner used was PLB-5E8. Furnace temperature is 1
The temperature was set to about 000 ° C., and the appearance of the combustion state was visually observed, and the exhaust gas was measured by a measuring instrument. The smoke (smoke) concentration in the exhaust gas is a value indicated by a smoke tester.

According to the test report of the Combustion Laboratory of Chugai Furnace Industry Co., Ltd. (created on January 17, 1994), the fuel oil-water emulsion fuel of the example was compared with fuel oil C (alone). Were as follows.

(1) Even if the combustion is performed at a low air ratio (m = 1.02, the residual oxygen concentration in the furnace is 0.4 to 0.6%), the smoke concentration is no. 1 and low. Fuel C has a higher air ratio (m =
1.05, the residual oxygen concentration in the furnace is 0.9%). 3. Thus, heavy oil-water emulsion fuels can burn at lower air ratios.

Here, the air ratio m is the ratio of the oxygen amount of the supplied air to the oxygen amount required for complete combustion of the fuel. Further, the residual oxygen concentration in the furnace is an actually measured value of the exhaust gas.

(2) The shape of the flame was good, and there was no burning state of sparks peculiar to heavy fuel oil C. Here, the burning state in which sparks fly means that some large oil droplets burn as single oil droplets outside the flame.

(3) The luminance of the frame decreased, and the frame became slightly pale orange. Such a decrease in flame brightness is due to the water gas reaction. The occurrence of a water gas reaction means that the emulsion was complete.

(4) The frame has a large diameter and a short length.

(5) It is gelled and has high viscosity.

On the other hand, the nitrogen oxide concentration of the exhaust gas is 8 to 10% higher than that of heavy fuel oil C (test at 11% oxygen concentration). This is considered to be due to the fact that the tile temperature and the flame temperature were increased because the burning speed was increased.

However, it is considered that the nitrogen oxide emission concentration must be able to be equal to or lower than that of the heavy fuel oil C by slightly improving the combustion conditions and the boiler.
This is because the slight increase in the nitrogen oxide concentration is not due to the poor combustion characteristics such as abnormal combustion, but is considered to be due to the improvement in the combustion speed as described above.

Table 4 shows detailed data of the above combustion test.

[0065]

[Table 4] Although omitted in Table 4 above, the oil flow rate was 13.2-1.
3.4 liter / h, oil discharge pressure 0.22kg / h
cm ² , the oil holding temperature was 101 to 104 ° C., and the burner scale was 6.5. The combustion capacity is 8.15.
８8.27 × 104 Kcal / liter, and the furnace pressure was 4 to 5 Torr. The pressure and temperature of the combustion air before the orifice were 750 Torr and 20 ° C.

<Combustion Test of Actual Emulsion> Next, a combustion test was performed on the emulsion fuel of the present invention using an actual combustion furnace for heavy fuel oil C. The furnaces tested were actually operating in a large factory.

In this test, sodium hydroxide and sodium chloride each having a concentration of 15% by weight were used as an aqueous solution to be mixed with heavy fuel oil C. Mixing of C heavy oil and water was performed by heating the water to 80 ° C. using the above emulsifying apparatus.

The combustion furnace used in the test is a 55t type manufactured by Automobile Manufacturing Co., Ltd. The operating conditions of the combustion furnace were kept constant while maintaining the optimum conditions for heavy fuel oil C.

Combustion is performed by changing the composition of the heavy oil C and the above-mentioned aqueous solution containing the additive, and nitrogen oxides (NO
x) concentration and oxygen concentration were measured. The results are shown in FIGS. 6 and 7 show the results before and after passing through the desulfurization device, respectively.

As shown in FIGS. 6 and 7, when the emulsion fuel of the present invention was used, the concentration of nitrogen oxides decreased. In particular, the volume ratio of C heavy oil and aqueous solution is 3000 /
A remarkable effect was observed when the ratio was 600 to 2800/1000.

In FIG. 6, the oxygen concentration was extremely large in the measured value, and is simply shown as reference data. Looking at the results when the volume ratio of C heavy oil and water is 2700/1000, it is known that the concentration of nitrogen oxides is remarkably reduced although the oxygen concentration is not reduced at all. Thus, it is known that the decrease in the nitrogen oxide concentration shown in FIGS. 6 and 7 is not due to the decrease in the oxygen concentration.

Although the results of the actual machine test seem to be different from the results in the test furnace described above, no decrease in the nitrogen oxide concentration was observed in the test furnace because the combustion conditions were not always appropriate. It is considered something.

In the above-mentioned actual combustion test, the boiler wall,
In particular, little adhesion of heat exchanger soot was observed, and thus a remarkable improvement in thermal efficiency was observed. In this way, soot adhesion is prevented, so that the emulsion fuel of the present invention eliminates the need for soot removal.

Although no data is shown, the emission of sulfur oxides was dramatically reduced.

When observing the state of the flame at the time of combustion, the elongation of the flame is better and the color is bluer than in the case of heavy fuel oil C alone. It was known that.

Although the above examples show only experimental examples for heavy fuel oil C, other than heavy fuel oil C, a COM fuel (Coal Oil Mixture) in which finely divided coal is dispersed in heavy oil, or heavy oil from oil sands (Orinocotar) was also emulsified in the same manner, and after standing for one week, no separation was observed at all, and it was a stable emulsion. Therefore, even when an emulsion fuel is obtained by using these fuel oils instead of the C heavy oil, exactly the same effects as in the above embodiment can be obtained.

[0077]

According to the present invention, a fuel oil-water emulsion fuel using heavy fuel oil C can be stored for a long time, can be stably maintained even under heating at 80 ° C. or higher, improves combustion efficiency, and emits harmful substances. Is provided that can sufficiently suppress the

[Brief description of the drawings]

FIG. 1 is a piping diagram showing an emulsifying apparatus for preparing a heavy oil-water emulsion fuel.

FIG. 2 is a cross-sectional perspective view showing an addition nozzle of the emulsifying device of FIG.

FIG. 3 is a sectional perspective view showing an in-line mixer of the emulsifying device of FIG.

FIG. 4 is a radial sectional view showing an in-line mixer of the emulsifying apparatus of FIG.

FIG. 5 is a micrograph of a heavy oil-water emulsion fuel of an example.

FIG. 6 is a graph showing the concentration of nitrogen oxides in exhaust gas in an actual combustion test. The measurement results before passing through the desulfurization device are shown.

FIG. 7 is a graph showing the concentration of nitrogen oxides in exhaust gas in an actual combustion test, as in FIG. The measurement results after passing through the desulfurization device are shown.

[Explanation of symbols]

 1,10 Nozzle mixer 11 Nozzle 12 Main pipe joint 13 Blind screw cap for drain 2 In-line mixer 21 Fixed stirring blade 31,32,33,34,35 Pipe V1, V2, V3, V4 Automatic valve NV1, NV2 Automatic Control needle valve P1, P2, P3 Pump

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[Procedure amendment]

[Submission date] July 14, 1997

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG. 4

FIG.

FIG. 2

FIG. 3

FIG. 5

FIG. 6

FIG. 7

Claims (7)

[Claims] 1. A W / O in which water is dispersed in heavy oil such as C heavy oil.
A heavy oil-water emulsion fuel, comprising 1 to 70% by volume of a water phase, a water-soluble and non-ammonia-based inorganic base and / or an inorganic salt, or an additive comprising any of these. A heavy oil comprising 0.3 to 40% by weight in the water phase in total of water and an inorganic salt, wherein the water phase has a diameter of substantially 20 μm or less and is stably dispersed at room temperature. Water emulsion fuel. 2. The fuel oil-water emulsion fuel according to claim 1, wherein the additive comprises an inorganic base or a basic inorganic salt.
A heavy oil-water emulsion fuel containing 0.2% by weight or more of the whole emulsion fuel. 3. The fuel oil / water emulsion fuel according to claim 2, wherein the additive comprises sodium hydroxide and sodium chloride. 4. The fuel oil / water emulsion fuel according to claim 1, wherein said additive comprises calcium chloride. 5. W / O by dispersing water in heavy oil such as C heavy oil
Additive for producing a heavy oil-water emulsion fuel of the type comprising sodium hydroxide, potassium hydroxide, sodium carbonate,
An additive for a heavy oil-water emulsion fuel, comprising at least one compound selected from the group consisting of potassium carbonate, sodium chloride, potassium chloride, and calcium chloride. 6. An emulsifying apparatus for producing a W / O type heavy oil-water emulsion fuel by dispersing water or an aqueous solution in a highly viscous heavy oil such as C heavy oil. The tip of a nozzle for supplying the heavy oil is disposed substantially in the center of the flow path of the heavy oil in the direction in which the heavy oil flows, and the heavy oil-water mixture mixed by the nozzle is provided in a flow path provided with a baffle plate. Alternatively, an emulsifying apparatus for producing a heavy oil-water emulsion fuel, which is further mixed in a meandering flow path. 7. A method for burning heavy oils in which an inorganic aqueous solution is dispersed and burned in heavy oils such as heavy oil C and heavy oil from an oil sand, wherein the heavy oil and the inorganic aqueous solution are mixed with each other. In the mixture, an inorganic aqueous solution
70% by volume, and the water-soluble inorganic substance is blended and mixed so as to contain 0.1 to 5% by weight in the mixture. After that, the obtained blended mixture is once held at a temperature of 80 ° C. or more, A method for burning heavy oils, which is supplied to a combustion furnace.