WO2018021249A1 - 電気炉用助燃バーナー - Google Patents
電気炉用助燃バーナー Download PDFInfo
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- WO2018021249A1 WO2018021249A1 PCT/JP2017/026716 JP2017026716W WO2018021249A1 WO 2018021249 A1 WO2018021249 A1 WO 2018021249A1 JP 2017026716 W JP2017026716 W JP 2017026716W WO 2018021249 A1 WO2018021249 A1 WO 2018021249A1
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- combustion
- burner
- injection pipe
- solid fuel
- gas
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D17/00—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel
- F23D17/005—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel gaseous or pulverulent fuel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C1/00—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air
- F23C1/12—Combustion apparatus specially adapted for combustion of two or more kinds of fuel simultaneously or alternately, at least one kind of fuel being either a fluid fuel or a solid fuel suspended in a carrier gas or air gaseous and pulverulent fuel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/20—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone
- F23D14/22—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone with separate air and gas feed ducts, e.g. with ducts running parallel or crossing each other
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D14/00—Burners for combustion of a gas, e.g. of a gas stored under pressure as a liquid
- F23D14/20—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone
- F23D14/22—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone with separate air and gas feed ducts, e.g. with ducts running parallel or crossing each other
- F23D14/24—Non-premix gas burners, i.e. in which gaseous fuel is mixed with combustion air on arrival at the combustion zone with separate air and gas feed ducts, e.g. with ducts running parallel or crossing each other at least one of the fluids being submitted to a swirling motion
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D17/00—Burners for combustion conjointly or alternatively of gaseous or liquid or pulverulent fuel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
- F27B3/08—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces heated electrically, with or without any other source of heat
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
- F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
- F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
- F27B3/12—Working chambers or casings; Supports therefor
- F27B3/16—Walls; Roofs
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D3/00—Charging; Discharging; Manipulation of charge
- F27D3/16—Introducing a fluid jet or current into the charge
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D7/00—Forming, maintaining, or circulating atmospheres in heating chambers
- F27D7/02—Supplying steam, vapour, gases, or liquids
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23D—BURNERS
- F23D2204/00—Burners adapted for simultaneous or alternative combustion having more than one fuel supply
- F23D2204/20—Burners adapted for simultaneous or alternative combustion having more than one fuel supply gaseous and pulverulent fuel
Definitions
- the present invention relates to an auxiliary burner attached to an electric furnace for producing molten iron by melting iron-based scrap.
- an auxiliary burner is installed at the cold spot, and the cold spot is used with this auxiliary burner.
- a method of preheating, cutting and melting iron-based scrap located in the area has been adopted.
- auxiliary combustion burner for example, in Patent Document 1, oxygen gas for scattering of incombustibles and cutting of iron-based scrap is ejected from the center, and fuel is further supplied from the outer periphery of the oxygen gas.
- a burner having a triple tube structure for injecting combustion oxygen gas from the outer peripheral portion, and in order to increase the speed of the oxygen gas ejected from the central portion, a constricted portion at the tip of the central oxygen gas ejection tube In order to impart a swirling force to the combustion oxygen gas ejected from the outermost periphery, a high-speed pure electric furnace for electric furnaces in which swirl vanes are installed in an annular space formed by a fuel ejection pipe and a combustion oxygen gas ejection pipe An oxygen-assisted burner has been proposed.
- Patent Document 2 proposes an electric furnace burner facility that expands the directivity of the burner flame to a wide range by decentering the nozzle tip of the auxiliary burner and rotating the burner.
- Patent Documents 1 and 2 have a problem that the target of fuel is limited to expensive gaseous fuel.
- Inexpensive fuels include solid fuels such as coal, but solid fuels are generally more difficult to burn faster than gaseous fuels and may misfire in some conditions, and solid fuels can be used as auxiliary burners. Use was difficult.
- this invention aims at providing the auxiliary burner for electric furnaces which can make the heating effect of iron-based scrap high and uniform by burning solid fuel with gaseous fuel appropriately and efficiently.
- auxiliary furnace burner for electric furnaces that can use solid fuel such as coal
- present inventors have developed a multi-tube auxiliary combustion burner that uses gaseous fuel and solid fuel as fuel, and supports combustion that is injected from the outermost periphery. By giving swirl to specific gas under specific conditions, solid fuel can be combusted together with gaseous fuel appropriately and efficiently, which improves the scrap heating effect and also makes the flame temperature of the burner uniform. I found.
- An electric furnace auxiliary burner attached to an electric furnace for producing molten iron by melting iron-based scrap, and using gaseous fuel and solid fuel as fuel A solid fuel injection pipe that divides a first flow path through which the solid fuel passes and injects the solid fuel from a tip of the first flow path; A second flow path that is disposed around the solid fuel injection pipe and through which the gaseous fuel passes is defined between the solid fuel injection pipe and an outer wall of the solid fuel injection pipe, and the gaseous fuel is injected from a tip of the second flow path.
- a gaseous fuel injection tube A third flow path that is disposed around the gaseous fuel injection pipe and through which the combustion-supporting gas passes is formed between the gas fuel injection pipe and an outer wall of the gaseous fuel injection pipe, and the combustion-supporting gas is provided from the tip of the third flow path.
- Q / P is 1.0 or more and 1.2 or less, where Q is the length of each swirling blade in the circumferential direction and P is the installation interval of the plurality of swirling blades in the circumferential direction.
- auxiliary burner of the present invention it is possible to make the heating effect of the iron-based scrap high and uniform by appropriately and efficiently burning the solid fuel together with the gaseous fuel.
- auxiliary furnace burner 100 for an electric furnace according to an embodiment of the present invention will be described with reference to FIGS.
- the auxiliary combustion burner 100 of this embodiment is attached to an electric furnace for producing molten iron by melting iron-based scrap, and uses gaseous fuel and solid fuel as fuel.
- the main body part for supplying fuel and supporting gas is a triple in which the solid fuel injection pipe 1, the gaseous fuel injection pipe 2, and the combustion supporting gas injection pipe 3 are arranged coaxially in this order from the center side. It has a tube structure.
- the solid fuel injection pipe 1 defines a solid fuel flow path 10 (first flow path) through which solid fuel passes, and the solid fuel flow path 10 has a circular solid fuel discharge port 11 at the tip thereof.
- the gaseous fuel injection pipe 2 is arranged around the solid fuel injection pipe 1 and defines a gaseous fuel flow path 20 (second flow path) through which the gaseous fuel passes between the solid fuel injection pipe 1 and the outer wall thereof.
- the tip of the gaseous fuel flow path 20 is a ring-shaped gaseous fuel discharge port 21 from which gaseous fuel is injected.
- the combustion-supporting gas injection pipe 3 is disposed around the gaseous fuel injection pipe 2, and the combustion-supporting gas flow path 30 (third flow path) through which the combustion-supporting gas passes with the outer wall of the gaseous fuel injection pipe 2.
- the tip of the combustion-supporting gas flow path 30 is a ring-shaped combustion-supporting gas discharge port 31 from which fuel-supporting fuel is injected.
- the solid fuel injection pipe 1 and the gas fuel injection pipe 2 are both at the same position along the burner axis, and only the outermost combustion-supporting gas injection pipe 3 has a tip of 10 to It protrudes about 200mm.
- the inner diameter of each of the injection pipes 1, 2, and 3 is not particularly limited.
- the solid fuel injection pipe 1 has an inner diameter of about 10 to 40 mm
- the gas fuel injection pipe 2 has an inner diameter of about 20 to 60 mm
- a combustion-supporting gas injection pipe is about 40 to 100 mm.
- the thickness of each spray tube is not particularly limited, but is generally about 2 to 20 mm.
- a burner gas supply port 32 is provided on the rear end side of the burner. Is supplied.
- a gaseous fuel supply port 22 is provided on the burner rear end side of the gaseous fuel injection pipe 2, and gaseous fuel is supplied to the gaseous fuel flow path 20 through this.
- a solid fuel supply port 12 is provided on the burner rear end side of the solid fuel injection pipe 1, and the solid fuel is supplied to the solid fuel flow path 30 together with the carrier gas via this.
- a combustion-supporting gas supply mechanism (not shown) is connected to the combustion-supporting gas supply port 32, and this supplies the combustion-supporting gas to the combustion-supporting gas supply port 32.
- a gaseous fuel supply mechanism (not shown) is connected to the gaseous fuel supply port 22 and supplies gaseous fuel to the gaseous fuel supply port 22.
- a solid fuel supply mechanism and a carrier gas supply mechanism (both not shown) are connected to the solid fuel supply port 12, and these supply the solid fuel and carrier gas to the solid fuel supply port 12.
- an inner tube and an outer tube are further coaxially arranged outside the flame-supporting gas injection tube 3, and between the outer tube and the inner tube, and between the inner tube and the tube.
- cooling fluid flow paths (cooling fluid forward path and return path) that are in communication with each other are formed.
- Examples of the fuel that can be used for the auxiliary burner of the present embodiment include the following.
- Examples of the gaseous fuel include LPG (liquefied petroleum gas), LNG (liquefied natural gas), hydrogen, ironworks by-product gas (C gas, B gas, etc.), a mixed gas of two or more of these, and the like. One or more of these can be used.
- Examples of the solid fuel include powdered solid fuels such as coal (pulverized coal), plastics (particulate or powdery, including waste plastics), and one or more of these can be used. Coal (pulverized coal) is particularly preferred.
- As the combustion-supporting gas pure oxygen (industrial oxygen), oxygen-enriched air, or air may be used, but pure oxygen is preferably used.
- As the carrier gas for example, nitrogen can be used.
- the amount of oxygen necessary for combustion is specifically calculated under the following conditions. That is, as calculation conditions, the calorific value of LNG is 9700 kcal / Nm 3, and the calorific value of pulverized coal as a solid fuel is 6250 kcal / kg. In addition, 90% of the total energy of the auxiliary burner is supplied from solid fuel and 10% from gaseous fuel. For example, when LNG is supplied at 10 Nm 3 / h, the calorific value is 97 Mcal / h. In this case, it is necessary to supply 873 Mcal / h, which is a difference from 970 Mcal / h, which is the target total calorific value of the burner, from pulverized coal, and the supply amount is about 140 kg / h.
- the theoretical amount of oxygen is calculated from the carbon content and hydrogen content in the fuel, the theoretical oxygen content of the LNG is 2.25Nm 3 / Nm 3 nm, the theoretical oxygen amount of the pulverized coal is at 1.5 Nm 3 / kg approximately .
- the support gas discharge port 31 has a discharge area that is 20 times or more that of the gaseous fuel discharge port 21 and the solid fuel discharge port 11. (Radial cross-sectional area) is required. For this reason, it is reasonable to arrange the combustion-supporting gas discharge ports 31 on the outermost peripheral portion of the burner in terms of the burner layout. In addition, when air is used as the combustion-supporting gas instead of pure oxygen, a flow rate five times higher is required. Also in this case, for the same reason, it is reasonable to arrange the combustion-supporting gas discharge port 31 on the outermost peripheral portion of the burner.
- the combustion-supporting gas flow path 30 is provided with a plurality of swirling blades 4 for rotating the combustion-supporting gas at a predetermined interval in the circumferential direction (swinging in the circumferential direction of the burner; the same applies hereinafter).
- the solid fuel can be combusted appropriately and efficiently, thereby improving the scrap heating effect and further making the flame temperature of the burner uniform.
- the scrap in the electric furnace can be efficiently heated or melted.
- combustible substance As the elements necessary for combustion, there are three elements: a combustible substance, oxygen, and temperature (fire source). Moreover, regarding the state of the combustible substance, the ease of combustion is the order of gas, liquid, and solid. This is because if the combustible substance is in a gaseous state, mixing of the combustible substance and oxygen is easy, and continuation of combustion (chain reaction) is performed.
- gas fuel When gas fuel is burned as a flammable substance using an auxiliary burner, gas fuel generally burns immediately after being injected from the tip of the burner, depending on the oxygen concentration, the flow rate of the gas fuel, and the shape of the burner tip. To do.
- a solid fuel typified by coal when used as a combustible substance, it is difficult to burn it as quickly as a gaseous fuel. This is due to the fact that the ignition temperature of coal is about 400 to 600 ° C., and that it is necessary to maintain this ignition temperature and to increase the temperature to the ignition temperature.
- the temperature rising time until the solid fuel reaches the ignition temperature depends on the particle size (specific surface area) of the solid fuel, and if the particles are made fine, the ignition time can be shortened. This is because the combustion reaction proceeds by maintaining the ignition temperature and reacting the combustible substance with oxygen. In order to advance the combustion reaction efficiently, it is important to sequentially generate efficient heating of coal and the reaction between coal and oxygen.
- the auxiliary burner of the present embodiment improves the efficient heating of the coal as described above and the reaction between the combustible substance and oxygen by using gas swirling.
- LNG liquefied natural gas
- coal pulverized coal
- pure oxygen is used as the combustion-supporting gas.
- the ignition temperature of the fuel is generally solid fuel> liquid fuel> gaseous fuel.
- Carbon dioxide which is an incombustible gas
- LNG which is fuel
- coal with oxygen Nonflammable gas inhibits the continuation of combustion (chain reaction) and causes a decrease in combustibility.
- coal is supplied with carrier gas, if there is much flow volume of carrier gas, since the temperature of the specific heat of carrier gas will fall, combustibility will generally improve if the solid-gas ratio is enlarged.
- the state where the solid-gas ratio is large is a condition where coal is in a dense state, and the reaction with heat and oxygen from the outside is not easily transmitted to the central part. In order to burn coal efficiently, it is important to create conditions where heat and oxygen are sufficiently present around the coal in the coal combustion field.
- the angle ⁇ (FIG. 3) formed with respect to the burner axis of the plurality of swirling blades 4 needs to be 5 ° or more and 45 ° or less. If the angle ⁇ of the swirl vane 4 is less than 5 °, sufficient swirl cannot be imparted to the combustion-supporting gas, and the effects of the present invention as described above cannot be sufficiently obtained. On the other hand, if the angle ⁇ of the swirl vane 4 exceeds 45 °, the combustion-supporting gas diffuses to the outside too much, and in this case, it is not possible to create a condition in which heat and oxygen are sufficiently present around the coal in the combustion field. However, the effects of the present invention as described above cannot be sufficiently obtained. From the above viewpoint, the more preferable angle ⁇ of the swirl vane 4 is 10 ° or more and 30 ° or less.
- the number of swirling blades 4 and the thickness of the swirling blades 4 are not particularly limited. However, while sufficient swirling is imparted to the combustion-supporting gas, the flow of the combustion-supporting gas is not hindered, and the blades In order to prevent deformation, the number of swirling blades 4 is suitably 8 or more and 16 or less, and the thickness of the blades is suitably about 1 to 10 mm.
- the installation position of the swirl vane 4 in the burner axial direction is not particularly limited as long as it is within the combustion-supporting gas flow path 30, but the tip of the combustion-supporting gas flow path 30 (fuel support gas discharge port 31) If it is too far from the target, there is a possibility that the target turning angle cannot be maintained before the combustion-supporting gas that has passed through the turning blade 4 is mixed with the gaseous fuel.
- the distance L B in the burner axis direction between the tip of the swirl vane 4 on the side of the combustion-supporting gas discharge port 31 and the combustion-supporting gas discharge port 31 is preferably about 10 to 50 mm.
- the length L A of the swirl vane 4 in the burner axis direction is obtained at 40mm or more. Further, the length L A, it is preferable from the viewpoint of the manufacturing cost of the blade is less than 100mm.
- each swirl vane 4 in the circumferential direction of the combustion-supporting gas passage 30 is defined as Q
- the interval in the circumferential direction of the plurality of swirling blades 4 in the circumferential direction of the combustion-supporting gas passage 30 is defined as Q.
- the swirl vane 4 may be a method of incorporating itself into a pipe body (injection pipe), or may be machined so as to be integrated with the pipe body.
- the combustion-supporting gas discharge port 31 has a discharge area (radial cut-off) at which the combustion-supporting gas discharge speed from the combustion-supporting gas discharge port at the minimum supply amount of the combustion-supporting gas is 10 m / s or more. Area).
- the “minimum supply amount” refers to the minimum supply amount that does not cause non-uniform combustion of the solid fuel and does not clog unburned solid fuel in the flow path.
- the scrap heating effect is improved and the flame temperature of the burner is made uniform by appropriately and efficiently burning the solid fuel together with the gaseous fuel.
- the auxiliary combustion burner 100 of the present embodiment has the following additional effects. That is, in this embodiment, the length of the flame is changed according to the distance from the scrap to be heated or melted by changing the ratio of solid fuel to the total fuel (calorific value conversion, hereinafter simply referred to as “solid fuel ratio”). The height can be adjusted arbitrarily.
- the auxiliary burner has a relatively low gas flow rate, the spout of molten iron or molten slag may clog the gas discharge port. Since the splash is purged, the gas discharge port is not easily clogged by the splash.
- FIG. 4 schematically shows an example of the usage state of the auxiliary burner 100 of the present embodiment (vertical cross section in the radial direction of the electric furnace), 7 is a furnace body, 8 is an electrode, 100 is an auxiliary burner, x is scrap.
- the auxiliary burner 100 is installed with an appropriate dip angle. In general, a plurality of auxiliary burners 100 are installed so that scrap in a so-called cold spot in an electric furnace can be heated or melted.
- the flame length varies depending on the ignition temperature of the fuel used for the auxiliary burner. Since solid fuel and gaseous fuel have different ignition temperatures, the flame length of the auxiliary burner (that is, the flame temperature at a certain distance from the burner) can be arbitrarily adjusted by changing the solid fuel ratio. .
- a combustion field that is equal to or higher than the ignition temperature of the solid fuel is created by the combustion of the gaseous fuel and the combustion-supporting gas, and the solid fuel is sent to the combustion field so that the solid fuel is sent.
- the temperature of the fuel rises to the ignition temperature, and solid fuel combustion (vaporization ⁇ ignition) occurs. Since the amount of heat necessary for increasing the temperature of the solid fuel is consumed, the flame temperature decreases, but the temperature increases in the region where the solid fuel is ignited. Therefore, when the solid fuel ratio is low, the flame generated by the auxiliary combustion burner of the present embodiment has a high temperature near the tip of the burner (that is, a short flame).
- the solid fuel ratio is increased, the endothermic heat of the solid fuel is increased. Due to subsequent heat generation, a high temperature is obtained even at a position far from the burner tip (that is, a long flame is formed). Therefore, by changing the solid fuel ratio, the flame length (that is, the flame temperature at a position away from the burner by a certain distance) can be controlled.
- FIG. 5 schematically shows a change in flame length when the solid fuel ratio is changed in the auxiliary burner of the present embodiment.
- the solid line is the flame temperature at a position 0.2 m away from the burner tip in the burner axis direction
- the broken line is the flame temperature at a position 0.4 m away from the burner tip
- the horizontal axis is the gaseous fuel. + The ratio of solid fuel in solid fuel.
- the flame temperature at the 0.2 m position in the vicinity of the burner is high when the solid fuel ratio is low, but a rapid temperature drop occurs at the 0.4 m position. That is, the flame length is short.
- the flame temperature at the 0.2 m position in the vicinity of the burner is lower than that in the case of 100% gas fuel, but the temperature is almost lowered even at the 0.4 m position. Absent. That is, the flame length is long. This is because the gaseous fuel is preferentially burned in the vicinity of the burner, and the solid fuel heated in the flame is burned at a position of 0.4 m to maintain the temperature.
- the distance between the auxiliary burner and the scrap changes due to the charging, additional charging and melting of the scrap.
- the distance between the auxiliary burner and the scrap is small at the start of operation or at the initial stage after the additional loading, and increases with the progress of melting of the scrap. This is because the distance from the undissolved scrap to the auxiliary burner increases with the progress of melting of the scrap because the scrap is first melted in order from the scrap closest to the auxiliary burner.
- the auxiliary burner of the present embodiment adjusts (changes) the flame length by changing the solid fuel ratio according to the distance from the scrap to be heated or melted, and the flame is not affected by the distance between the scrap and the auxiliary burner. Can reach scrap.
- the charging of scraps is performed about 2 to 3 times.
- the operation of the electric furnace begins with the start of energization and the start of use of the auxiliary burner after the initial scrap is charged.
- the start of operation there are cases where some of the molten iron from the previous operation remains and there is molten metal at the bottom, and there are cases where the entire molten iron from the previous operation is discharged and the furnace is empty. There is no.
- the initial stage after charging the scrap is a situation where the bulk density is high and the entire interior of the electric furnace is filled with scrap. Therefore, the distance between the tip of the auxiliary burner and the scrap is close.
- the distance between the tip of the auxiliary burner and the scrap in the initial stage after charging the scrap is about 0.5 m. This is because, if the distance between the tip of the auxiliary burner and the scrap is too close, the splash that is generated when the scrap melts adheres to the auxiliary burner.
- tip part height is based also on the characteristic of a furnace, it is common that it is 1 m or more upwards from the hot-water surface height after scrap burn-off.
- the melting proceeds from the scrap that is in contact with the molten iron, near the electrodes, and near the auxiliary burner.
- the scrap in the vicinity of the auxiliary burner always has a distance of about 0.5m because the scrap at the top falls as it melts in the initial stage after charging the scrap, but there is always a distance of about 0.5m. . If the distance from the scrap increases, the heat of the auxiliary burner cannot be efficiently supplied to the scrap. Therefore, conventionally, an operation to stop the auxiliary burner has been performed.
- the solid fuel ratio is lowered and the scrap is melted with a short flame, and when the melting progresses and the distance of the scrap becomes long, the solid
- the operation time can be shortened and the power consumption can be reduced. Since the distance between the auxiliary burner and the scrap changes by inserting the scraps about 2 to 3 times, the scrap can be efficiently dissolved by appropriately changing the solid fuel ratio each time.
- the distance between the auxiliary burner and the scrap it is necessary to know the distance between the auxiliary burner and the scrap.
- a laser distance meter is installed in the auxiliary burner, and the distance to the scrap can be measured by this laser distance meter.
- the situation in the furnace can be observed with a monitoring camera through a window such as a discharge port.
- the distance to the scrap can be grasped by observation in the furnace with the monitoring camera.
- information useful for grasping the distance may be obtained from the operation data.
- the iron plate was heated using the auxiliary burner having the structure shown in FIGS. 1 to 3, and the temperature of the iron plate was measured.
- the output of the burner is 590 Mcal / h.
- LNG gaseous fuel
- pulverized coal solid fuel
- pure oxygen was used as the combustion-supporting gas. While pulverized coal is injected from the central solid fuel injection pipe using nitrogen as a carrier gas, LNG is injected from the outer gas fuel injection pipe, and pure oxygen is injected from the outer (outermost circumference) combustion-supporting gas injection pipe, respectively. did.
- the specifications of pulverized coal are shown in Table 1.
- the LNG flow rate was 6.1 Nm 3 / h
- the pulverized coal supply rate was 85 kg / h
- the oxygen flow rate was 155 Nm 3 / h
- the flow rate of nitrogen for conveying the pulverized coal was 6.7 Nm 3 / h.
- the discharge area of the combustion-supporting gas discharge port 31 is 2064 mm 2
- the oxygen flow rate calculated from the oxygen flow rate is 21 m / s.
- the solid fuel ratio was 90%.
- the amount of blown oxygen was calculated by the above formula (1) with an oxygen ratio of 1.1.
- Table 2 shows the angle ⁇ of the swirl vane provided in the flow path of the combustion-supporting gas injection pipe at each level and the value of Q / P.
- the swirl vane having an angle of 0 ° is not intended to swirl the combustion-supporting gas, but is provided as a member that holds the gaseous fuel injection pipe 2 and the combustion-supporting gas injection pipe 3 concentrically.
- the number of swirl vanes eight, L B is 40 mm, P was 30 mm.
- FIG. 6 shows an outline of a combustion test using an auxiliary burner.
- 6A shows a combustion test method
- FIG. 6B shows a thermocouple installation position with respect to an iron plate used in the combustion test.
- the dimensions of the iron plate used for temperature measurement were 500 mm long, 500 mm wide and 4 mm thick, and SS400 was used.
- a K-type thermocouple is placed on the opposite side of the burner flame surface, one at the center of the plate, one at a position 100 mm left and right from the center, and one at a position 200 mm left and right from the center. A total of 5 locations were installed.
- a heat insulating material (fireproof board) having a thickness of 25 mm was installed on the iron plate surface side where the K-type thermocouple was installed.
- This iron plate with a heat insulating material was placed in a furnace (furnace temperature: room temperature) provided with an opening for introducing a burner flame on the front surface facing the auxiliary burner.
- the distance from the tip of the burner to the iron plate was 1.0 m assuming an electric furnace operation.
- the experiment was started with burner ignition, the output of the thermocouple installed on the iron plate was taken into a data logger, and the temperature of the iron plate was measured over time. In about 10 minutes after the start of the experiment, the temperature of the five thermocouples became constant. This temperature was defined as the maximum heating temperature.
- Table 2 shows the maximum heating temperature at 5 points and the average temperature at each level. Further, as an index of temperature variation at 5 points, a value of (maximum temperature among 5 points) ⁇ average temperature and a value of average temperature ⁇ (minimum temperature among 5 points) are shown. When each value exceeded 50 degreeC, it determined with it being inferior.
- the angle ⁇ of the swirl vane is fixed at 45 °, and the Q / P value is changed variously.
- a Q / P of 1.0 or more and 1.2 or less was obtained. In 5, 7, and 8, it was possible to reduce the variation particularly at 5 points.
- the burner output 590 Mcal / h in this test is a scale installed in an electric furnace of 60 t / ch, and an actual scale test was conducted. Therefore, it is clear that the same effect can be expected in an actual electric furnace.
- auxiliary burner of the present invention it is possible to make the heating effect of the iron-based scrap high and uniform by appropriately and efficiently burning the solid fuel together with the gaseous fuel.
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Abstract
Description
[1]鉄系スクラップを溶解して溶鉄を製造する電気炉に付設され、燃料として気体燃料と固体燃料を用いる電気炉用助燃バーナーであって、
前記固体燃料が通過する第1流路を区画し、該第1流路の先端から前記固体燃料を噴射する固体燃料噴射管と、
前記固体燃料噴射管の周囲に配置され、前記固体燃料噴射管の外壁との間で前記気体燃料が通過する第2流路を区画し、該第2流路の先端から前記気体燃料を噴射する気体燃料噴射管と、
前記気体燃料噴射管の周囲に配置され、前記気体燃料噴射管の外壁との間で支燃性ガスが通過する第3流路を区画し、該第3流路の先端から前記支燃性ガスを噴射する支燃性ガス噴射管と、
前記第3流路に、その周方向に所定間隔で配置された、前記支燃性ガスを旋回させるための複数枚の旋回羽根と、
を有し、前記複数枚の旋回羽根のバーナー軸線に対してなす角度θが5°以上45°以下であることを特徴とする電気炉用助燃バーナー。
支燃性ガスの流量は、供給ガス量の中で最も多いことから、他の供給ガス(気体燃料及び搬送気体)と流速を合せるためには、支燃性ガス吐出口31の吐出面積を気体燃料吐出口21や固体燃料吐出口11よりも大きくする必要がある。その観点から、支燃性ガス噴射管3は最外周とするのが最適である。以下、支燃性ガスとして酸素を、気体燃料としてLNGを、固体燃料として微粉炭をそれぞれ使用する場合を例に説明する。
まず、燃焼に必要な酸素の量は下記(1)式により算出される。
燃焼に必要な酸素量=酸素比(係数)×[LNG流量×LNGの理論酸素量+微粉炭供給量×微粉炭の理論酸素量] …(1)
支燃性ガス流路30には、その周方向に所定間隔で、支燃性ガスを旋回(バーナー周方向での旋回。以下同様)させるための複数枚の旋回羽根4が設けられる。支燃性ガスに旋回を付与することにより、固体燃料を適切かつ効率的に燃焼させることができ、これによりスクラップ加熱効果が向上し、さらに、バーナーの火炎温度が均一化される。その結果、電気炉内のスクラップを効率よく加熱又は溶解することができる。
1 固体燃料噴射管
2 気体燃料噴射管
3 支燃性ガス噴射管
4 旋回羽根
7 炉体
8 電極
x 鉄系スクラップ
10 固体燃料流路(第1流路)
11 固体燃料吐出口
12 固体燃料供給口
20 気体燃料流路(第2流路)
21 気体燃料吐出口
22 気体燃料供給口
30 支燃性ガス流路(第3流路)
31 支燃性ガス吐出口
32 支燃性ガス供給口
θ 旋回羽根のバーナー軸線に対してなす角
Q 旋回羽根の第3流路周方向における長さ
P 旋回羽根の第3流路周方向における設置間隔
Claims (4)
- 鉄系スクラップを溶解して溶鉄を製造する電気炉に付設され、燃料として気体燃料と固体燃料を用いる電気炉用助燃バーナーであって、
前記固体燃料が通過する第1流路を区画し、該第1流路の先端から前記固体燃料を噴射する固体燃料噴射管と、
前記固体燃料噴射管の周囲に配置され、前記固体燃料噴射管の外壁との間で前記気体燃料が通過する第2流路を区画し、該第2流路の先端から前記気体燃料を噴射する気体燃料噴射管と、
前記気体燃料噴射管の周囲に配置され、前記気体燃料噴射管の外壁との間で支燃性ガスが通過する第3流路を区画し、該第3流路の先端から前記支燃性ガスを噴射する支燃性ガス噴射管と、
前記第3流路に、その周方向に所定間隔で配置された、前記支燃性ガスを旋回させるための複数枚の旋回羽根と、
を有し、前記複数枚の旋回羽根のバーナー軸線に対してなす角度θが5°以上45°以下であることを特徴とする電気炉用助燃バーナー。 - 前記角度θが10°以上30°以下である、請求項1に記載の電気炉用助燃バーナー。
- 各々の前記旋回羽根の前記周方向における長さをQとし、前記複数枚の旋回羽根の前記周方向における設置間隔をPとしたとき、Q/Pが1.0以上1.2以下である、請求項1又は2に記載の電気炉用助燃バーナー。
- 前記第3流路の先端が、前記支燃性ガスの最小供給量における支燃性ガス吐出速度が10m/s以上となるような吐出面積を有する、請求項1~3のいずれか一項に記載の電気炉用助燃バーナー。
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US20220390108A1 (en) * | 2021-06-08 | 2022-12-08 | Forney Corporation | High-capacity igniter |
US20240019118A1 (en) * | 2022-07-12 | 2024-01-18 | Air Products And Chemicals, Inc. | Burner, System, and Method for Hydrogen-Enhanced Pulverized Coal Ignition |
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JP6580710B2 (ja) | 2019-09-25 |
CN109642724A (zh) | 2019-04-16 |
KR102211258B1 (ko) | 2021-02-02 |
JPWO2018021249A1 (ja) | 2018-08-02 |
KR20190027916A (ko) | 2019-03-15 |
US20190271465A1 (en) | 2019-09-05 |
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