Combustion method using fuel combustion device, method for manufacturing cement, and cement firing equipment

Abstract

The invention provides a combustion method using a fuel combustion device, a cement manufacturing method, and a cement firing facility provided with the fuel combustion device, and the fuel combustion device is provided with a fuel supply mechanism. The fuel supply mechanism is provided with a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder. The present invention provides a combustion method using a fuel combustion device, a method for manufacturing cement, and a cement firing facility provided with the fuel combustion device, which can reduce the amount of fossil fuel (as fuel supplied to the fuel combustion device provided in various facilities such as the cement firing facility), and maintain the amount of radiant heat transfer from various burners, thereby reducing the amount of fossil fuel used as fuel supplied to the fuel combustion device provided in the various facilities such as the cement firing facility. As a result, the amount of heat transferred to a heated object such as a powder raw material of cement clinker is maintained so as to maintain a state suitable for firing the heated object, the amount of carbon dioxide discharged from the various devices is reduced, and the various devices can be operated at low cost.

Description

Technical Field

[0001] The invention relates to a combustion method using a fuel combustion device and cement burning equipment. Background Art

[0002] In recent years, growing concern about global warming has led to calls for reducing atmospheric carbon dioxide emissions. Research is underway to reduce and recover atmospheric emissions of exhaust gases containing carbon dioxide generated during operations at various facilities, including power plants, incinerators, cement plants, steel mills, and industrial equipment. Reducing carbon dioxide emissions from cement plants is particularly pressing.

[0003] Various efforts have been made to reduce the emission of carbon dioxide in cement burning equipment. For example, Patent Document 1 discloses the use of combustible gas as the main fuel and combustible waste as the auxiliary fuel in the main burner blown into the cement kiln. In addition, Patent Document 2 discloses a technology for burning cement clinker by supplying carbon-containing heat energy and ammonia to the burning furnace, and Patent Document 3 discloses a fuel combustion equipment comprising a fuel supply unit having an injection unit for injecting ammonia-containing gas containing ammonia. Among the methods described in Patent Documents 1 to 3 are the following technologies: using combustible gas, non-fossil fuel, carbon-free fuel, etc., wherein the emission of carbon dioxide is reduced by using fuels such as non-fossil fuel and carbon-free fuel.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-52746

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-137579

[0008] Patent Document 3: Japanese Patent Application Publication No. 2019-172484 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] The present invention has been completed in view of this actual situation, and its purpose is to provide a combustion method using a combustion device, a cement manufacturing method, and a cement firing equipment equipped with a fuel combustion device. The combustion method using the combustion device, the cement manufacturing method, and the cement firing equipment equipped with a fuel combustion device reduce the use of fossil fuel (as fuel supplied to the fuel combustion devices equipped with various equipment such as cement firing equipment) while maintaining the radiation heat transfer amount of various burners, thereby maintaining the heat transferred to the heating objects such as the powdered raw materials of the cement clinker to maintain a state suitable for its firing, reducing the emission of carbon dioxide discharged from the various equipment, and being able to operate the various equipment at a low cost.

[0011] Solutions for solving problems

[0012] In order to solve the above-mentioned problems, the present invention provides the following method for operating a fuel combustion device.

[0013] 1. A combustion method using a fuel combustion device, wherein the fuel combustion device includes a fuel supply mechanism, the fuel supply mechanism including a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

[0014] Furthermore, the present invention provides the following method for operating a fuel combustion device as a preferred embodiment.

[0015] 2. The combustion method using a fuel combustion device according to 1 above, wherein the combustible powder is at least one powder selected from fossil fuels, non-fossil fuels, and combustible wastes.

[0016] 3. The combustion method using the fuel combustion device according to 2 above, wherein the combustible powder is coal powder.

[0017] 4. The combustion method using a combustion fuel device according to any one of 1 to 3 above, wherein the fuel gas is at least one fuel gas selected from a combustible gas and a carbon-free gas fuel.

[0018] 5. The combustion method using a fuel combustion device according to 4 above, wherein the combustible gas is at least one gas selected from fossil fuels and non-fossil fuels.

[0019] 6. The combustion method using the fuel combustion device according to 4 or 5 above, wherein the carbon-free gaseous fuel is at least one gas selected from ammonia and hydrogen.

[0020] 7. The combustion method using a fuel combustion device according to any one of 1 to 6 above, wherein the non-combustible powder is at least one powder selected from desalination dust, biomass incineration ash, coal ash, dust at the bottom of a clinker cooler, and garbage incineration ash.

[0021] 8. The combustion method using a fuel combustion device according to any one of 1 to 7 above, wherein the volume-based average particle size of the non-combustible powder is 0.1 μm or more and 50 μm or less.

[0022] 9. The combustion method using a fuel combustion device according to any one of 1 to 8 above, wherein the water content of the non-combustible powder is 5% by mass or less.

[0023] 10. The combustion method using a fuel combustion device according to any one of 1 to 9 above, wherein the loss on ignition of the non-combustible powder is 10% or less.

[0024] 11. A combustion method using a fuel combustion device according to any one of 1 to 10 above, wherein the supply amount of the non-combustible powder is set to be greater than 0.1 parts by mass and less than 10 parts by mass relative to 1 part by mass of the supply amount of the combustible powder corresponding to the total calorific value equal to the total calorific value of the fuel gas.

[0025] 12. A combustion method using a fuel combustion device according to any one of 1 to 11 above, wherein the fuel combustion device has a combustible powder injection mechanism for injecting the combustible powder, a fuel gas injection mechanism for injecting the fuel gas, and a non-combustible powder injection mechanism for injecting the non-combustible powder.

[0026] 13. The combustion method using the fuel combustion device according to 12 above, wherein the combustible powder includes coal powder, and the non-combustible powder injection mechanism injects the coal powder and the non-combustible powder.

[0027] 14. The combustion method using the fuel combustion device according to any one of 1 to 13 above, which is used for combustion in a kiln burner provided in a rotary kiln in a cement burning facility.

[0028] Furthermore, the present invention provides the following method for producing cement.

[0029] 15. A method for manufacturing cement, wherein a fuel combustion device is used as a kiln burner of a rotary kiln in a cement burning device, and the fuel combustion device is provided with a fuel supply mechanism, wherein the fuel supply mechanism has a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

[0030] Furthermore, the present invention provides a cement burning facility equipped with the following fuel combustion device.

[0031] 16. A cement burning equipment, wherein a fuel combustion device is used as a kiln burner of a rotary kiln, and the fuel combustion device has a fuel supply mechanism, and the fuel supply mechanism has a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

[0032] Effects of the Invention

[0033] According to the present invention, while reducing the use of fossil fuel (as fuel supplied to the fuel combustion devices of various equipment such as cement burning equipment), the radiation heat transfer of various burners is maintained, thereby maintaining the heat transferred to the heating objects such as powdered raw materials of cement clinker to maintain a state suitable for the burning, reducing the emission of carbon dioxide discharged from the various equipment, and operating the various equipment at a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic diagram showing a preferred embodiment of an injection mechanism of a fuel supply device used in the combustion method of this embodiment.

[0035] Figure 2 This is a graph showing the temperature inside the rotary kiln relative to the distance from the front end of the kiln burner in Examples and Comparative Examples.

[0036] Figure 3 This is a graph showing the temperature inside the rotary kiln relative to the distance from the front end of the kiln burner in Examples and Comparative Examples.

[0037] Figure 4 This is a graph showing the amount of radiation heat transferred in a rotary kiln relative to the distance from the front end of the kiln burner in Examples and Comparative Examples.

[0038] Figure 5 This is a graph showing the amount of radiation heat transferred in a rotary kiln relative to the distance from the front end of the kiln burner in Examples and Comparative Examples. DETAILED DESCRIPTION

[0039] Hereinafter, an embodiment of the present invention (hereinafter sometimes referred to as "the present embodiment") will be described. The present invention is not limited to the following embodiment, and can be implemented with arbitrary changes within the scope that does not hinder the effect of the invention. In addition, the expression of the numerical range of "AA to BB" in this specification means "above AA and below BB". Moreover, in this specification, the numerical values ​​involved in "above", "below" and "~" related to the description of the numerical range are numerical values ​​that can be arbitrarily combined. For example, when a certain numerical range is recorded as "CC to DD" and "EE to FF", numerical ranges such as "CC to FF" and "EE to DD" are also included.

[0040] [Combustion method using a fuel combustion device]

[0041] In the combustion method using the fuel combustion device of this embodiment, the fuel combustion device includes a fuel supply mechanism having a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

[0042] As mentioned above, various studies are underway to reduce carbon dioxide emissions, such as the methods disclosed in the aforementioned patent documents 1 to 3. Reducing carbon dioxide emissions is one of the important topics, but maintaining a good combustion state of the burners of the various devices mentioned above, and further maintaining the heat transferred to the heating objects such as the powdered raw materials of the cement clinker to maintain a state suitable for their burning, is extremely important in terms of operational stability, reduction in fuel consumption, and product quality, and therefore attention has begun to be paid to these performances. Therefore, it is required not only to reduce carbon dioxide emissions, but also to achieve a high level of balance between reducing carbon dioxide emissions, maintaining operational stability, reducing fuel consumption, and achieving excellent product quality.

[0043] The methods described in Patent Documents 1 to 3 are effective for reducing carbon dioxide emissions. However, with increasing emphasis on operational stability, fuel consumption reduction, and product quality, the methods described in these patent documents are known to have room for improvement in terms of maintaining a good combustion state and, consequently, the ease of adjustment required to maintain the heat transferred to the heating object, such as the powdered raw material of the cement clinker, in order to maintain a state suitable for its calcination.

[0044] For example, the method described in Patent Document 1 uses combustible gas as the main fuel and combustible waste as the auxiliary fuel, with the combustible waste promoting heating by radiation. However, since the combustible waste contributes to both heating by radiation and combustion, increasing heating by radiation requires also promoting heating by combustion. This poses the challenge of maintaining a stable combustion state and, consequently, maintaining the heat transferred to the heating target, such as the powdered raw material of the cement clinker, to maintain a state suitable for its calcination.

[0045] Furthermore, the method described in Patent Document 2 uses fossil fuels such as heavy oil A and ammonia, while the method described in Patent Document 3 uses ammonia-containing gas, fossil fuels, etc. as other fuels that do not contain ammonia. However, the methods described in these patent documents do not provide sufficient heating by radiation, and there is room for improvement in terms of increasing the heating by radiation.

[0046] In the combustion method using the fuel combustion device of this embodiment, combustible powder, fuel gas, and non-combustible powder are supplied. The combined use of combustible powder and fuel gas improves combustion efficiency, thereby reducing the use of fossil fuels. Furthermore, the supply of non-combustible powder maintains the amount of radiant heat transfer, thereby maintaining the heat transferred to the heating object, such as the powdered raw material of the cement clinker, to maintain a state suitable for its firing. These effects can reduce carbon dioxide emissions from various devices as a whole, and enable the operation of various devices at a low cost.

[0047] The fuel combustion device used in the combustion method of this embodiment will be described starting from the fuel used.

[0048] (Combustible powder)

[0049] Examples of the combustible powder supplied by the combustible powder supply mechanism include, for example, fossil fuels such as coal; wood biomass fuels such as firewood, charcoal, sawdust briquettes, sawdust charcoal, briquettes, and wood powder; herbaceous biomass fuels obtained by carbonizing, semi-carbonizing, or pelletizing various herbaceous plants such as mowed grasses, weeds, and forage crops; waste biomass fuels obtained by converting organic waste such as food waste, livestock manure, and sewage sludge into RDF (Refuse Derived Fuel) or RPF (Refuse Paper & Plastic Fuel); non-fossil fuels such as wood chips; and combustible waste such as waste plastics, meat and bone meal, and fiber scraps. Among these, coal powder is preferred in view of its ease and stability in availability.

[0050] These combustible powders can be used alone or in combination of two or more.

[0051] The shape of the combustible powder is not particularly limited as long as it can pass through the flow path of the burner described later. Considering factors such as improving combustion efficiency to reduce fossil fuel usage, reducing carbon dioxide emissions, and ease of handling, the maximum length is generally 5 mm or less, preferably 2 mm or less, more preferably 1 mm or less, and even more preferably 0.5 mm or less. There is no particular lower limit.

[0052] (Fuel gas)

[0053] Preferred examples of the fuel gas supplied by the fuel gas supply mechanism include combustible gases such as gaseous fossil fuels and non-fossil fuels, and carbon-free gaseous fuels such as hydrogen and ammonia. Representative examples of gaseous fossil fuels include natural gas; gas obtained by dry distillation of coal; coal gas such as aqueous gas obtained by steam reforming solid fuels such as charcoal and coal; and oil gas obtained by thermal decomposition of petroleum fractions such as heavy oil. Preferred examples of non-fossil fuels include synthesis gas such as synthetic methane.

[0054] Among the above, carbon-free gas fuel and synthesis gas are preferred from the viewpoint of reducing carbon dioxide emissions. These fuel gases can be used alone or in combination of two or more.

[0055] The amount of fuel gas used is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and even more preferably 8 parts by mass or more, per 100 parts by mass of the combustible powder used. The upper limit is preferably 20 parts by mass or less, more preferably 18 parts by mass or less, and even more preferably 15 parts by mass or less. Setting the amount of fuel gas used within this range improves combustion efficiency, reduces fossil fuel usage, and reduces carbon dioxide emissions.

[0056] (Non-combustible powder)

[0057] Preferred examples of non-combustible powders supplied by the non-combustible powder supply mechanism include so-called dust (coal dust) and combustion residue (ash). Dust (coal dust) and combustion residue (ash) are both powders such as coal dust and ash resulting from the combustion and burning of combustible materials, and therefore are non-combustible powders, not combustible powders.

[0058] Therefore, it can be said that the non-combustible powder maintains the heat transferred to the heating object such as the powder raw material of the cement clinker by maintaining the radiation heat transfer in the combustion method of this embodiment, thereby helping to maintain the state suitable for its burning, but does not help to improve the combustibility.

[0059] Examples of dust (coal dust) include desalination dust, waste sand dust, electric furnace dust, converter dust, steel dust, paper sludge incineration dust, cyclone capture dust, and dust at the bottom of a clinker cooler (AQC dust), which are discharged from various factory equipment. For convenience, dust discharged from various factory equipment using the combustion method of this embodiment is preferably used. For example, when the combustion method of this embodiment is used in a cement clinker burning plant, desalination dust and dust at the bottom of a clinker cooler are preferably used.

[0060] These dusts (coal dust) can be used alone or in combination of two or more.

[0061] As combustion residue (ash), coal ash (fly ash), biomass incineration ash, garbage incineration ash, coke ash, heavy oil combustion ash, flue ash, sewer incineration ash, paper sludge incineration ash, etc., which are discharged from various factory equipment, can be cited. If convenience is taken into consideration, it is preferred to use dust discharged from various factory equipment using the combustion method of this embodiment. For example, when the combustion method of this embodiment is used in cement clinker burning equipment, coal ash, biomass incineration ash, and garbage incineration ash are preferably used.

[0062] These combustion residues (ashes) can be used alone or in combination of two or more.

[0063] The volume-based average particle size of the non-combustible powder is not particularly limited as long as it is a shape that can pass through the flow path of the burner described later. Considering the improvement of the burning state of the heating object, such as the powdered raw material of cement clinker, based on radiant heat transfer to reduce the use of fossil fuels, reduce carbon dioxide emissions, and ease of handling, the volume-based average particle size of the non-combustible powder is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 1 μm or more. The upper limit is preferably 50 μm or less, more preferably 45 μm or less, and even more preferably 30 μm or less.

[0064] The volume-based average particle size is the particle size (D) at which the cumulative volume percentage is 50%, which can be measured by a laser diffraction particle size distribution measurement method. 50 ).

[0065] If it is considered to improve the burning state of the heating object such as the powder raw material of cement clinker based on the radiation heat transfer to reduce the use of fossil fuels and reduce the emission of carbon dioxide, the lower the moisture content of the non-combustible powder, the better, preferably below 5 mass%, more preferably below 3 mass%, and even more preferably below 1 mass%.

[0066] Considering the need to improve the burning state of materials such as cement clinker powder raw materials, which are heated by radiant heat transfer, to reduce fossil fuel usage and carbon dioxide emissions, the lower the loss on ignition of non-combustible powder, the better. It is typically 10% or less, preferably 8% or less, more preferably 6% or less, and even more preferably 5% or less. Loss on ignition is an indicator of the level of unburned carbon. As described above, the non-combustible powder used in the combustion method of this embodiment has a low loss on ignition, meaning it does not contribute to combustibility and is therefore non-combustible.

[0067] The loss on ignition of the non-combustible powder can be measured in accordance with the method specified in "8.3 Loss on ignition" of JIS A6201:2015 (fly ash for concrete).

[0068] The supply amount of non-combustible powder is preferably 0.1 parts by mass or more, more preferably 0.3 parts by mass or more, and further preferably 0.5 parts by mass or more relative to 1 part by mass of the supply amount of combustible powder equivalent to the total calorific value of the fuel gas. As an upper limit, it is preferably 10 parts by mass or less, more preferably 8 parts by mass or less, further preferably 5 parts by mass or less, and further preferably 3.5 parts by mass or less.

[0069] For example, combustible powders such as coal typically contain ash. The present inventors, focusing on the fact that when fuel gas is used instead of combustible powder, insufficient ash reduces the amount of radiant heat transfer. This results in a decrease in the amount of heat transferred to the heating object, such as the powdered raw materials of cement clinker, leading to a deterioration in the burning state. They have therefore investigated the use of non-combustible powders to supplement the ash. In the combustion method of this embodiment, fuel gas is used to reduce the amount of combustible powder used, and non-combustible powder is supplied to address the ash deficiency caused by the reduced amount of combustible powder used.

[0070] According to the combustion method of this embodiment, the non-combustible powder is supplied within the above-mentioned range according to the type and amount of combustible powder and fuel gas used. This allows the ash supply to be adjusted, thereby facilitating the maintenance of the radiant heat transfer. For example, by increasing the amount of heat transferred to the heating object, such as the powdered raw material of the cement clinker, the burning state can be easily improved. As a result, combustion efficiency can be improved, thereby reducing the use of fossil fuels and, consequently, reducing carbon dioxide emissions. Furthermore, as described above, the use of non-fossil fuels, carbon-free gas fuels, etc. as fuel gas can further contribute to reducing carbon dioxide emissions.

[0071] (Fuel supply mechanism)

[0072] The fuel combustion device used in the combustion method of this embodiment includes a fuel supply mechanism comprising a combustible powder supply mechanism for supplying the combustible powder, a fuel gas supply mechanism for supplying the fuel gas, and a non-combustible powder supply mechanism for supplying the non-combustible powder. The fuel supply mechanism enables the supply of combustible powder, fuel gas, and non-combustible powder, and the combustion of these fuels.

[0073] The fuel supply mechanism is not particularly limited in form as long as it can supply combustible powder, fuel gas, and non-combustible powder. For example, in the case of a combustible powder supply mechanism, it is preferably configured to allow air delivery using a conveying gas when supplying the combustible powder. More specifically, it may include an injector (or in-line mixer) for introducing the combustible powder into a conveying gas such as air, and an instrument assembly such as a metered feeder for quantitatively supplying the combustible powder into the conveying gas. Furthermore, it may include piping, a blower, and other equipment for conveying the combustible powder.

[0074] Furthermore, the non-combustible powder supply mechanism is also the same as the combustible powder supply mechanism described above.

[0075] The fuel gas supply mechanism only needs to include piping for supplying fuel gas, and may also include an ejector (or a line mixer) for introducing air or other gases as needed. In addition, in order to monitor and adjust the flow rate of the fuel gas, instrument components such as a flow meter and a flow control valve may be included.

[0076] (Injection mechanism)

[0077] The fuel supply device used in the combustion method of this embodiment preferably includes, in addition to the aforementioned fuel supply mechanism, a fuel injection mechanism comprising a combustible powder injection mechanism for injecting combustible powder, a fuel gas injection mechanism for injecting fuel gas, and a non-combustible powder injection mechanism for injecting non-combustible powder. The fuel injection mechanism enables more uniform injection of the fuel and non-heating powder. This improves combustion efficiency, reduces fossil fuel usage, and, as a result, reduces carbon dioxide emissions.

[0078] use Figure 1 An injection mechanism preferably included in the fuel supply device will be described. Figure 1 This is a schematic diagram showing a preferred embodiment of an injection mechanism preferably included in the fuel supply device used in the combustion method of this embodiment. Figure 1In the figure, the injection port of a kiln burner, a type of fuel combustion device, is shown as an injection mechanism. A rotary kiln is a device used in cement calcining plants to burn the powdered raw materials for cement clinker. The kiln burner is a fuel combustion device used to burn the powdered raw materials for cement clinker.

[0079] Figure 1 The kiln burner shown is cylindrical with a circular cross-section. It has five types of nozzles, nozzles 11 to 15, as nozzles. These nozzles 11 to 15 are arranged along multiple concentric circles, with two nozzles, nozzles 11 and 12, located in the innermost region. An annular nozzle 13 is provided as it moves further outward. Multiple circular nozzles 14 are provided along the circumference of the concentric circles, and multiple circular nozzles 15 are provided on the outer circumference.

[0080] The injection port 13 is preferably used as an injection port for the main fuel. In the combustion method of this embodiment, it is preferred to inject at least one of a combustible powder and a fuel gas (hereinafter, the combustible powder and the fuel gas injected from the injection port 13 are sometimes referred to as the "main fuel"). In this case, the combustible powder is preferably coal powder. By injecting the main fuel from the injection port 13, the combustion state can be improved. In addition, since the combustion efficiency can be improved, the amount of fossil fuel used can be reduced, and as a result, the emission of carbon dioxide can be reduced. In addition, it is preferred to inject the above-mentioned main fuel and non-combustible powder from the injection port 13.

[0081] Injection ports 11 and 12 inject fuel supplied from a fuel supply mechanism toward the inner circumference of the annular main fuel injected from injection port 13. In addition to the above-mentioned main fuels of combustible powder and fuel gas, the fuel injected from injection ports 11 and 12 may also be a combustible liquid.

[0082] Representative examples of combustible liquids include fossil fuels such as kerosene, heavy oil, and recycled oil; combustible wastes such as waste oil and waste glycerin; and renewable fuels such as recycled fuels produced from waste vegetable oils (e.g., vegetable waste cooking oil) and other industrial wastes.

[0083] Injection ports 11-13 form a circular or annular flow path parallel to the central axis of the cylindrical kiln burner. The rotation angle of the main fuel through these injection ports is preferably set to 0°. The rotation angle values ​​in this specification are set values. In practice, the rotation angle during main fuel injection will vary. If any variation occurs, it is typically within ±10°.

[0084] Regarding the injection ports 11 and 12 provided on the innermost circumference, Figure 1In FIG, the opening of the injection port 12 is shown as being larger than the opening of the injection port 11. Thus, the openings of the injection ports 11 and 12 may be different or the same.

[0085] exist Figure 1 While the figure shows that each of the injection ports 11 and 12 is provided with one, multiple injection ports may also be provided. In this case, for example, a single injection port 11 may be provided, and two injection ports 12 with larger openings may be provided. It is preferable to provide more injection ports 11 with smaller openings than injection ports 12 with larger openings. By providing more injection ports 11 with smaller openings, the flow rate of the main fuel or combustible liquid can be increased, thereby improving the combustion state. Furthermore, since the combustion efficiency can be improved, the use of fossil fuels can be reduced, and as a result, the emission of carbon dioxide can be reduced.

[0086] As the number of the injection ports 11, according to the injection mechanism ( Figure 1 The size of the burner (in the case of a kiln burner), the type of fuel used, and other factors can vary, so it cannot be generalized. However, one or two are preferred, and one is more preferred. Similarly to the number of injection ports 11, there cannot be generalized numbers, but one or more is preferred. The upper limit is preferably four or fewer, more preferably three or fewer, and even more preferably two or fewer.

[0087] When injecting the main fuel into injection port 13, the injection velocity of the main fuel is preferably 15 m / s or greater, more preferably 20 m / s or greater, and even more preferably 25 m / s or greater. The upper limit is preferably 60 m / s or less. Within this range, the main fuel injected from injection port 13 flows in a straight line, achieving a good combustion state. This allows combustion at a higher temperature (approximately 1450°C in a rotary kiln). Furthermore, by improving combustion efficiency, the use of fossil fuels can be reduced, easily reducing carbon dioxide emissions.

[0088] As described above, the combustible powder is usually sprayed together with a conveying gas such as air, and therefore the spraying speed of the combustible powder becomes the flow speed of the conveying gas.

[0089] When combustible powder or combustible powder and non-combustible powder are injected from the injection port 13, the amount of conveying air used varies depending on the type of combustible powder used as the main fuel, so it cannot be generalized. However, it is generally 3 Nm / s for 1 ton of combustible powder or 1 ton of the combined amount of combustible powder and non-combustible powder. 3 Above, preferably 5Nm 3 More than 10 Nm 3 Above, as the upper limit, usually 25Nm 3 Below, preferably 20Nm 3the following.

[0090] Furthermore, when combustible powder and non-combustible powder are ejected from the ejection port 13, the amount of combustible powder used is different depending on the type of combustible powder and non-combustible powder, so it cannot be generalized, but the amount of combustible powder used is usually 3 parts by mass or more, preferably 5 parts by mass or more relative to 1 part by mass of non-combustible powder, and the upper limit is usually 15 parts by mass or less, preferably 13 parts by mass or less.

[0091] The injection port 14 is provided on the outer peripheral side of the injection port 13 serving as the main fuel injection port and is the closest injection port. In addition, the injection port 15 is provided on the outer peripheral side thereof.

[0092] The injection port 14 is preferably used as a fuel gas or non-combustible powder injection mechanism. By injecting non-combustible powder from near the injection port 13, which serves as the main fuel injection mechanism, the radiant heat transfer from the non-heating powder can be more effectively utilized, thereby improving the burning state of the heating object, such as the powdered raw material of cement clinker. Furthermore, injecting fuel gas can improve combustion efficiency. Therefore, in either case, the use of fossil fuels can be reduced, and as a result, carbon dioxide emissions can be reduced.

[0093] When injection port 14 is used as a non-combustible powder injection mechanism, it is preferred that injection port 14 inject coal powder as a combustible powder along with the non-combustible powder. In other words, the non-combustible powder injection mechanism is preferably a mechanism that injects coal powder and non-combustible powder. This allows for more efficient utilization of the radiant heat transfer from the non-combustible powder, further improving the burning state of the heated material, such as the powdered raw material for cement clinker. Furthermore, since combustion efficiency can be further improved, the use of fossil fuels can be further reduced, resulting in a reduction in carbon dioxide emissions.

[0094] The fuel gas and air can be injected from the injection port 14 separately or simultaneously. When the fuel gas and air are injected simultaneously, the amount of air used per ton of fuel gas varies depending on the type of fuel gas and cannot be generalized. However, it is generally 3 Nm / s per ton of fuel gas. 3 Above, preferably 5Nm 3 Above, as the upper limit, usually 20Nm 3 Below, preferably 15Nm 3 the following.

[0095] The injection port 15 is generally used as a fuel gas or air injection mechanism. The injection velocity of the fuel gas or air in the injection port 15 is preferably 50 m / s or more, more preferably 70 m / s or more, and even more preferably 100 m / s or more, with an upper limit of 300 m / s or less.

[0096] Furthermore, the swirl speed of the fuel gas and air injected from the injection port 15 is preferably set to 0° or higher, and the upper limit is preferably 30° or lower, and more preferably 15° or lower.

[0097] If the injection port 15 is used as a fuel gas or air injection mechanism and its injection velocity is set within the above-mentioned range, the combustion state can be improved. Furthermore, since the combustion efficiency can be improved, the amount of fossil fuel used can be reduced, and as a result, the amount of carbon dioxide emissions can be reduced. The same applies when the rotation speed is set within the above-mentioned range.

[0098] The injection ports 14 and 15 show that a plurality of circular flow paths are arranged at equal intervals on the circumferences of different concentric circles. The injection port 14 is composed of a total of 26 circular flow paths, and the injection port 15 is composed of a total of 18 circular flow paths. Figure 1 The number of flow paths of the injection ports 14 and 15 shown is merely a preferred embodiment and is not limiting. The total number of injection ports 14 may be the same as or different from the total number of injection ports 15. From the perspective of improving combustion efficiency, the total number of injection ports 14 is preferably greater than the total number of injection ports 15.

[0099] The number of injection ports 14 cannot be determined in the same manner as the injection ports 11, but is preferably 12 or more, more preferably 16 or more, and even more preferably 20 or more. The upper limit is preferably 32 or less, more preferably 30 or less, and even more preferably 28 or less. The number of injection ports 15 cannot be determined in the same manner as the injection ports 14, but is preferably 12 or more, more preferably 14 or more, and even more preferably 16 or more. The upper limit is preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less.

[0100] The injection ports 14 and 15 have the above-described structure, which can improve the combustion state and combustion efficiency, thereby reducing the amount of fossil fuel used and, as a result, reducing the amount of carbon dioxide emissions.

[0101] The combustion method of this embodiment can be adopted in equipment equipped with a fuel combustion device that burns combustible powders such as fossil fuels. For example, it can preferably be adopted in equipment installed in cement burning equipment, specifically, the combustion of a burner installed in a suspension preheater that preheats and calcines powder raw materials, a rotary kiln that burns the preheated and calcined powder raw materials to produce cement clinker, etc.

[0102] Among them, it can be preferably used for combustion in a rotary kiln burner. That is, the fuel combustion device used in the combustion method of this embodiment is preferably used as a burner for combustion in a suspension preheater or a rotary kiln installed in a cement burning facility. For example, considering that it can perform extremely high temperature combustion of approximately 1450°C, it is preferably used as a burner for combustion in a rotary kiln (rotary kiln burner).

[0103] [Method for producing cement]

[0104] The method for producing cement according to the present embodiment is the following method for producing cement:

[0105] A fuel combustion device is used as a kiln burner of a rotary kiln in a cement burning facility. The fuel combustion device includes a fuel supply mechanism having a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

[0106] Combustible powder and a combustible powder supply mechanism for supplying it, fuel gas and a fuel gas supply mechanism for supplying it, non-combustible powder and a non-combustible powder supply mechanism for supplying it, a fuel supply mechanism having a combustible powder supply mechanism, a fuel gas supply mechanism and a non-combustible powder supply mechanism, and a fuel combustion device having these supply mechanisms, as described in the combustion method of the fuel combustion device using the above-mentioned embodiment.

[0107] The fuel supply device used in the manufacturing method of this embodiment preferably includes a fuel injection mechanism having a combustible powder injection mechanism, a fuel gas injection mechanism, and a non-combustible powder injection mechanism, as described in the combustion method of the above-mentioned fuel combustion device.

[0108] Furthermore, various conditions in the fuel gas supply mechanism and the fuel injection mechanism, the kiln burner included in the rotary kiln in the cement burning facility, etc. are the same as those described in the combustion method using the fuel combustion device of the present embodiment.

[0109] [Cement burning equipment]

[0110] The cement burning equipment of this embodiment is the following equipment:

[0111] The fuel combustion device is used as a kiln burner of the rotary kiln. The fuel combustion device includes a fuel supply mechanism having a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

[0112] The cement burning equipment of this embodiment can be equipped with the equipment that is equipped in known cement burning equipment, such as a drying and crushing device for drying and crushing cement raw materials to obtain powdered raw materials, a suspension preheater for preheating and calcining the powdered raw materials, a rotary kiln for burning the preheated and calcined powdered raw materials to produce cement clinker, a clinker cooler for cooling cement clinker, and an exhaust gas cooling device for cooling exhaust gas discharged from the suspension preheater.

[0113] The fuel combustion device in the cement burning facility of this embodiment is used as a burner provided in a rotary kiln for burning the preheated and calcined powdered raw materials to produce cement clinker.

[0114] Example

[0115] Next, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[0116] Internal combustion analysis within the rotary kiln was performed using simulation software ("Ansys Fluent (product name)", manufactured by ANSYS, Inc.). The simulation conditions are as follows. To reduce the computational load, the combustion analysis was conducted on the entire length of the rotary kiln (30 m) (on the side where the kiln burners are installed).

[0117] Rotary kiln: diameter: 3.1m, length: 66m

[0118] Kiln burner: with Figure 1 Kiln burner with jets shown (diameter: 1.0 m, length: 6.5 m, jet 11: circular with a diameter of 0.2 m, jet 12: circular with a diameter of 0.25 m, jet 13: width 0.13 m, jet 14: circular with a diameter of 0.13 m, jet 15: circular with a diameter of 0.15 m)

[0119] Coal powder (combustible powder)

[0120] Low calorific value: 28946kJ / kg

[0121] Moisture: 3% by mass

[0122] Volatile content: 37% by mass

[0123] Ash content: 8% by mass

[0124] Solid carbon content: 51% by mass

[0125] Natural gas (fuel gas)

[0126] Composition: Methane 100%

[0127] Low calorific value: 35.90MJ / Nm 3

[0128] The properties of the non-combustible powder are shown in the following Table 1. The loss on ignition and the moisture content were 0.

[0129] [Table 1]

[0130]

[0131] (Examples 1 to 8 and Comparative Examples 1 and 2)

[0132] The temperature and radiant heat transfer within the kiln were calculated through simulation when the combustible powder, fuel gas, non-combustible powder, and air were injected from each injection port at the flow rates shown in Table 2 below. The air supplied from each injection port serves as both transport air for the combustible and non-combustible powders and combustion air. Furthermore, secondary air is high-temperature air obtained after cooling high-temperature cement clinker in a clinker cooler and is introduced into the rotary kiln at the temperatures listed in Table 2.

[0133] The simulation software used in the examples and comparative examples is general-purpose software used for simulating cement clinker kiln burners and other similar firing machines. Furthermore, a comparison of the simulation results of Comparative Example 1, representing prior operational performance, with prior operational conditions confirmed that the location of the highest temperature within the kiln and the temperature at the kiln outlet were substantially consistent with the operational conditions, demonstrating a high degree of reliability.

[0134] [Table 2]

[0135]

[0136] The simulation results are shown in Figures 2 to 5 . Figure 2 The temperature in the rotary kiln relative to the distance from the front end of the kiln burner in Examples 1 to 5 and Comparative Examples 1 and 2 is shown. Figure 3 The temperature inside the rotary kiln is shown relative to the distance from the kiln burner tip for Examples 6-8 and Comparative Examples 1-2. The combustion method of this embodiment confirmed that the temperature inside the rotary kiln can be maintained at a high temperature. Regarding Example 5, while the temperature inside the rotary kiln was lower than that in the other examples, it was within the allowable range. Furthermore, as will be described later, the radiation heat transfer was high and excellent, resulting in no problems with the production of clinker.

[0137] Regarding Comparative Examples 1 and 2, which did not use non-combustible powder, Comparative Example 1 adjusts the amount of coal used to achieve results comparable to those of the Example. However, it was confirmed that an increase of approximately 20% was necessary compared to the Example. Furthermore, in Comparative Example 1, a particularly low temperature trend was observed in the area near the kiln burner.

[0138] Figure 4 The ratio of the radiation heat transfer amount in the rotary kiln relative to the distance from the kiln burner tip for Examples 1 to 5 and Comparative Example 2 is shown, with the value of Comparative Example 1 being 100. Figure 5 The ratios of the radiation heat transfer amount in the rotary kiln relative to the distance from the kiln burner tip for Examples 2, 6 to 8, and Comparative Example 2 are shown, with the value for Comparative Example 1 being 100.

[0139] The results of the example show that while the radiation heat transfer rate is lower than that of Comparative Example 1 (below 100), it is equal to or exceeds that in the area 8 meters or more from the kiln burner tip, maintaining a suitable state for cement clinker firing. Maintaining the radiation heat transfer rate in the area between 8 meters and approximately 20 meters from the kiln burner tip is particularly effective in maintaining a suitable state for cement clinker firing. Furthermore, the aforementioned area can of course be changed depending on operating conditions such as the size of the rotary kiln, cement clinker production capacity, and burner size.

[0140] Furthermore, the radiation heat transfer amount in the rotary kiln of the embodiment showed an increasing trend compared to that of the comparative example 2, and it is considered that the radiation heat transfer amount was good when firing cement clinker.

Claims

1. A combustion method using a fuel combustion device, wherein: The fuel combustion device includes a fuel supply mechanism having a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

2. The combustion method using a fuel combustion device according to claim 1, wherein: The combustible powder is at least one powder selected from fossil fuels, non-fossil fuels and combustible wastes.

3. The combustion method using a fuel combustion device according to claim 2, wherein: The combustible powder is coal powder.

4. The combustion method using a combustion fuel device according to claim 1 or 2, wherein: The fuel gas is at least one fuel gas selected from combustible gas and carbon-free gas fuel.

5. The combustion method using a fuel combustion device according to claim 4, wherein: The combustible gas is at least one gas selected from fossil fuels and non-fossil fuels.

6. The combustion method using a fuel combustion device according to claim 4, wherein: The carbon-free gaseous fuel is at least one gas selected from ammonia and hydrogen.

7. The combustion method using a fuel combustion device according to claim 1 or 2, wherein: The non-combustible powder is at least one powder selected from desalination dust, biomass incineration ash, coal ash, dust at the bottom of the clinker cooler and garbage incineration ash.

8. The combustion method using a fuel combustion device according to claim 1 or 2, wherein: The non-combustible powder has a volume-based average particle size of 0.1 μm or more and 50 μm or less.

9. The combustion method using a fuel combustion device according to claim 1 or 2, wherein: The water content of the non-combustible powder is 5% by mass or less.

10. The combustion method using a fuel combustion device according to claim 1 or 2, wherein: The loss on ignition of the non-combustible powder is less than 10%.

11. The combustion method using a fuel combustion device according to claim 1 or 2, wherein: The supply amount of the non-combustible powder is set to 0.1 parts by mass or more and 10 parts by mass or less per 1 part by mass of the supply amount of the combustible powder corresponding to the same total calorific value as that of the fuel gas.

12. The combustion method using a fuel combustion device according to claim 1 or 2, wherein: The fuel combustion device includes a combustible powder injection mechanism for injecting the combustible powder, a fuel gas injection mechanism for injecting the fuel gas, and a non-combustible powder injection mechanism for injecting the non-combustible powder.

13. The combustion method using a fuel combustion device according to claim 12, wherein: The combustible powder includes coal powder, and the non-combustible powder injection mechanism injects the coal powder and the non-combustible powder.

14. The combustion method using a fuel combustion device according to claim 1 or 2, which is used for combustion in a kiln burner provided in a rotary kiln in a cement burning facility.

15. A method for producing cement, wherein: A fuel combustion device is used as a kiln burner of a rotary kiln in a cement burning facility. The fuel combustion device includes a fuel supply mechanism having a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

16. A cement burning device, wherein: The fuel combustion device is used as a kiln burner of the rotary kiln. The fuel combustion device includes a fuel supply mechanism having a combustible powder supply mechanism for supplying combustible powder, a fuel gas supply mechanism for supplying fuel gas, and a non-combustible powder supply mechanism for supplying non-combustible powder.

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