JP7174915B2 - Nozzle tip manufacturing method and fuel nozzle manufacturing method - Google Patents

Description

The present invention relates to a nozzle tip used in a regenerative burner, a fuel nozzle for a regenerative burner provided with this nozzle tip, and a regenerative burner provided with this fuel nozzle.

As furnace equipment such as a heat treatment furnace and a steel heating furnace, there is a furnace equipped with a regenerative burner (for example, Patent Document 1). The regenerative burner is installed on the first furnace wall of the furnace body and the second furnace wall facing the first furnace wall. Each regenerative burner has an air port and a fuel port, and the air port communicates with the heat storage chamber. For a predetermined time, the first regenerative burner provided on the first furnace wall is operated for combustion, exhaust gas is sucked from the air port of the second regenerative burner provided on the second furnace wall, and the second regenerative chamber is formed. and store heat in the heat storage material. During this time, the air supplied to the first regenerative burner has been heated in the first heat storage chamber.

After the predetermined time has elapsed, the second regenerative burner is operated for a predetermined period of time, and the exhaust gas is sucked from the air port of the first regenerative burner and stored in the heat storage material of the first heat storage chamber. During this time, the air supplied to the air port of the second regenerative burner has been heated in the second heat storage chamber. This cycle is then repeated.
In addition to this example, there are also those that are arranged side by side and repeat the combustion operation and the exhaust gas suction operation.

A fuel pipe is inserted into the fuel port. Since the tip of the fuel pipe is installed so that it is substantially flush with the furnace wall surface, the tip receives high-temperature radiant heat in the furnace and is exposed to the combustion gas atmosphere in the furnace. Metal pipes are likely to corrode due to scales, etc., and cracks may occur due to burning or thermal shock. Therefore, conventionally, a cooling mechanism for cooling the tip of the fuel pipe with water or air is provided, which increases the equipment cost and simultaneously injects fuel gas from the inner pipe and cooling air from the outer pipe with a double metal pipe structure. It was also an energy loss due to the configuration.

Japanese Unexamined Patent Application Publication No. 2007-3036

The present invention provides a regenerative burner nozzle tip that does not require a cooling mechanism for the tip of a fuel injection hole nozzle (hereinafter referred to as a fuel nozzle), a regenerative burner fuel nozzle that includes this nozzle tip, and a regenerator that includes this fuel nozzle. An object of the present invention is to provide a burner and an industrial furnace equipped with this regenerative burner.

The gist of the present invention is as follows.

[1] A tubular nozzle tip having an inner hole, which is provided at the tip of a fuel nozzle of a regenerative burner and is made of an inorganic fiber molding.

[2] The nozzle tip according to [1], wherein the inorganic fiber molded body is composed of a plurality of inorganic fiber blocks, and the inorganic fiber blocks are a laminate of needle blankets.

[3] A nozzle tip according to [2], wherein the ends in the thickness direction of the laminate of the needle blankets are installed so as to be the inner hole surface and the tip end surface of the nozzle tip.

[4] The nozzle tip according to any one of [1] to [3], wherein the inorganic fibers are alumina-silica fibers.

[5] The nozzle tip according to any one of [1] to [4], wherein the inorganic fiber molding contains an inorganic binder.

[6] The nozzle tip according to any one of [1] to [5], wherein the inorganic binder contains an alumina component.

[7] The nozzle tip according to any one of [1] to [6], wherein the inorganic fiber molding contains an iron oxide corrosion resistant composition.

[8] A nozzle tip according to any one of [1] to [7], wherein the nozzle tip has a higher bulk density toward the inner periphery.

[9] A fuel nozzle for a regenerative burner inserted into a fuel port of a regenerative burner, wherein any one of [1] to [8] is attached to a metal cylindrical nozzle body and the tip of the nozzle body. A fuel nozzle having a nozzle tip as described.

[10] In [9], the base end of the nozzle tip is fitted inside the tip of the nozzle body, and a screw attached to the tip of the nozzle body in a centripetal direction is inserted into the nozzle tip. A fuel nozzle characterized by:

[11] A regenerative burner having an air port, a fuel port, a fuel nozzle inserted into the fuel port, and a heat storage chamber communicating with the air port, wherein the fuel nozzle is any of [9] to [10]. A regenerative burner characterized by being the fuel nozzle according to any one of the above.

[12] An industrial furnace having the regenerator burner according to [11].

Since the nozzle tip of the present invention is made of an inorganic fiber molding, it has good fire resistance, corrosion resistance, and thermal shock resistance, and does not require a cooling mechanism. An industrial furnace having a regenerative burner equipped with the nozzle tip of the present invention can save several percent of energy compared with the conventional one.

1 is a perspective view of a nozzle tip according to an embodiment; FIG. 4 is a cross-sectional view of a nozzle tip according to an embodiment; FIG. FIG. 4 is a cross-sectional view of the tip portion of the fuel nozzle according to the embodiment; FIG. 4 is a cross-sectional view of the tip portion of the fuel nozzle according to the embodiment; It is a cross-sectional view of a furnace body in which a regenerative burner according to an embodiment is installed. It is sectional drawing of the furnace body which installed the regenerative burner which concerns on another embodiment. It is a perspective view explaining a manufacturing method of a nozzle tip concerning an embodiment. It is a sectional view explaining a manufacturing method of a nozzle tip concerning an embodiment. FIG. 9 is a cross-sectional view taken along line IX-IX of FIG. 8;

Embodiments will be described below with reference to the drawings.

1 and 2 show a nozzle tip according to an embodiment. This nozzle tip 1 is made of an inorganic fiber molding. This nozzle tip 1 has a substantially cylindrical shape with an inner hole 1a. The inner hole 1a extends axially through the axial portion of the nozzle tip 1 . In the nozzle tip 1, as shown in FIG. 4, the axial direction X on the distal end side may be in an oblique direction to the axial center on the proximal end side.

In this embodiment, the outer peripheral surface of the nozzle tip 1 on the base end side is provided with a concave stepped portion 1b having a diameter smaller than that on the tip end side.

FIG. 3 is an axial cross-sectional view of the tip of a fuel nozzle 2 having this nozzle tip 1. As shown in FIG. This fuel nozzle 2 has a nozzle body 3 made of a metal pipe and a nozzle tip 1 attached to the tip of the nozzle body 3 . The tip of the nozzle body 3 is fitted onto the concave stepped portion 1b of the nozzle tip 1 . A screw 4 is driven from the outer peripheral surface of the tip of the nozzle body 3 in a centripetal direction, and the nozzle tip 1 is immovably attached to the nozzle body 3 by inserting the screw 4 into the nozzle tip 1 . Regarding the method of fixing the nozzle tip 1 and the nozzle main body 3, an adhesive such as mortar is applied to the inner periphery near the tip of the nozzle main body 3 in contact with the nozzle tip 1, and the nozzle tip 1 and the nozzle main body 3 are fixed together. may be fixed by adhesive.

A protruding portion 3a is provided around the inner periphery of the nozzle body 3 in the vicinity of the tip. The proximal end surface of the nozzle tip 1 abuts the distal end side falling surface 3b of the convex portion 3a. The convex portion 3a has a first inner peripheral surface 3c that has the same diameter as the inner hole 1a of the nozzle tip 1 and is coaxial.

Preferably, as shown in FIG. 4, it has a tapered second inner peripheral surface 3d whose diameter increases with increasing distance from the first inner peripheral surface 3c. In this manner, the inner hole 1a and the first inner peripheral surface 3c are made to have the same diameter and are coaxial, and the tapered inner peripheral surface 3d is provided. .

The outer diameter of the tip of the nozzle tip 1 and the outer diameter of the concave stepped portion 1b may be appropriately adjusted according to the size of the fuel nozzle 2. Since it is ~150 mm, it is preferably within this range.

FIG. 5 is a horizontal sectional view of the wall surface 6 of the furnace body provided with the regenerative burner 5 having the fuel nozzle 2. As shown in FIG.

A regenerative burner 5 is fitted in a regenerative burner installation opening 6 a provided in the wall surface 6 of the furnace body. This regenerative burner 5 has a burner tile 10 made of castable refractory and a pair of fuel nozzles 2 attached to the burner tile 10 .

The burner tile 10 is arranged so that the tip surface 10 a is flush with the furnace inner surface of the furnace body wall surface 6 . An air chamber 11 is provided on the rear side in the burner tile 10, and an air port 12 is provided through the air chamber 11 to the tip surface of the burner tile. A pair of fuel nozzle installation holes (fuel ports) 13, 13 are provided with the air port 12 interposed therebetween. Each fuel nozzle installation hole 13 penetrates from the tip surface 10a of the burner tile 10 to the rear surface in a direction perpendicular to the tip surface 10a.

A fuel nozzle 2 is inserted into each fuel nozzle installation hole 13 . The tip surface of the nozzle tip 1 at the tip of the fuel nozzle 2 is flush with the tip surface 10 a of the burner tile 10 . A nozzle tip 1 having an inner hole 1a extending in the axial direction of the fuel nozzle 2 is adopted. are arranged parallel to the

The air chamber 11 communicates with a regenerative burner heat storage chamber (not shown). A fuel pipe (not shown) is connected to the rear end side of the fuel nozzle 2 .

When the regenerative burner 5 performs combustion operation, the air heated in the heat storage chamber is jetted from the air chamber 11 through the air port 12 into the furnace. Further, fuel (in this case, gas fuel) is ejected from the fuel nozzle 2, mixed with air, and combusted.

When the regenerative burner 5 performs the heat storage operation, the fuel supply to the fuel nozzle 2 is stopped and the in-furnace combustion exhaust gas is sent to the heat storage chamber through the air port 12 and the air chamber 11 .

In this embodiment, since the tip of the fuel nozzle 2 is composed of the nozzle tip 1 made of the inorganic fiber molding, the tip of the fuel nozzle 2 has good fire resistance, corrosion resistance, and thermal shock resistance. . Also, a cooling mechanism for the tip portion is not required.

In the above embodiment, the axial direction X of the tip of the inner hole 1a of the nozzle tip 1 is parallel to the axial line of the air port 12. When the fuel nozzle installation hole 13' is provided obliquely to the inner surface of the furnace, the inner hole 1a of the nozzle tip 1' extends in the axial direction of the fuel nozzle 2 as in the case of the nozzle tip 1. However, the fuel nozzle 2 is arranged so that the axial direction X of the tip of the inner hole 1 a intersects with the extension of the axial direction of the air port 12 . Other configurations in FIG. 6 are the same as in FIG. 5, and the same reference numerals denote the same parts.

A method of manufacturing the nozzle tip 1 will be described with reference to FIGS.

In this manufacturing method, as shown in FIG. 7, a plurality of inorganic fiber blocks 20 are used. The block 20 has a substantially rectangular parallelepiped shape with a first end surface 25 and a second end surface 26, and has a slope 24a on one longitudinal side surface. Thus, the block 20 has a substantially trapezoidal shape having a narrow first longitudinal side surface 21 and a second longitudinal side surface 22 parallel to the first longitudinal side surface 21 .

A planar third longitudinal side 23 is formed between the first longitudinal side 21 and one long side of the second longitudinal side 22 . A fourth longitudinal side 24 is formed on the side opposite to the third longitudinal side 23 . The first longitudinal side surface 21 side of the fourth longitudinal side surface 24 is the inclined surface 24a.

A notch 27 is provided at the intersection of the second end surface 26 and the second longitudinal side surface 22 of the block 20 .

Each block 20 has a third longitudinal side surface 23 in contact with a fourth longitudinal side surface 24 of an adjacent block 20 and a first longitudinal side surface 21 in contact with the outer peripheral surface of the cylindrical portion 31 of the inner mold 30. They are arranged on the outer circumference of the cylindrical portion 31 .

By strongly pressing the adjacent blocks 20 together, each block 20 is compressed in the T direction (the direction in which the third longitudinal side 23 and the fourth longitudinal side 24 approach) in FIG. , 20 are in close contact with each other without a gap, forming a tubular body surrounding the tubular portion 31 .

In this cylindrical body, the inner peripheral side is more strongly compressed in the T direction. can be controlled and moldability is good. In particular, it is preferable that the compressibility of the bulk density on the inner peripheral side is 30 to 65% and the compressibility of the bulk density on the outer peripheral side is 20 to 40%.

An inorganic fiber sheet 28 is wound around the outer periphery of this cylindrical body. Although the sheet 28 is wound in two layers in this embodiment, it may be wound in one layer or in three or more layers.

An outer mold (not shown) is attached so as to surround the outer circumference of the sheet 28 .

The inner mold 30 has the tubular portion 31 and flanges 32 and 33 provided at both ends of the tubular portion 31, respectively. A large number of small holes 34 are provided in the tubular portion 31 . The tubular portion 31 is manufactured using, for example, a punching plate. One flange 32 is detachable from the cylindrical portion 31 .

The outer mold (not shown) has the same shape as the inner mold 30, but the outer mold consists of a pair of half-split bodies, and by combining the pair of half-split bodies, the sheet 28 is wrapped around the inside thereof. It has the same shape as the inorganic fiber block 20 . The cylindrical body with the sheet 28 is sandwiched between a pair of half-split bodies, and the cylindrical body with the sheet 28 is compressed in the diameter-reducing direction to form a compressed body 29 (FIG. 8).

The compressed body 29 sandwiched between the inner mold 30 and the outer mold is impregnated with an inorganic binder liquid. At this time, the inorganic binder liquid is supplied from the outer peripheral surface side of the compressed body 29 through the outer mold having a large number of small holes like the inner mold 30, and the inside of the cylindrical portion 31 of the inner mold 30 is sucked. It is preferable to suck and discharge the binder liquid from the inner peripheral side of the compressed body. In this way, a large amount of the inorganic binder liquid adheres and remains toward the inner peripheral side of the compressed body. In addition, the suction causes the inorganic binder to adhere and remain mainly in the vicinity of the intersections of the inorganic fibers.

Next, the compressed body to which the inorganic binder liquid is adhered is dried. In order to perform this drying, it is preferable to apply warm air from the outer peripheral side while sucking the inside of the cylindrical portion 31, but it is not limited to this. After drying, the mold is removed (the outer mold and the inner mold 30 are removed) and then fired to bake the inorganic binder onto the inorganic fibers. After that, if necessary, burrs are removed by cutting, and the product is finished to standard dimensions. Thus, the nozzle tip 1 is manufactured.

In the nozzle tip 1 manufactured in this manner, the inner peripheral side of the compressed body 29 has a higher bulk density, and the binder adhesion amount gradually increases toward the inner hole side. A high bulk density portion having high fiber binding strength is formed along the . By providing this high bulk density portion, the nozzle tip becomes excellent in wind corrosion resistance. The bulk density in the range from the innermost peripheral surface of the nozzle tip 1 to 5 mm is preferably 1.1 to 4.0 times, particularly 1.5 to 3.0 times the bulk density on the outermost peripheral side.
The binder concentration in the range from the innermost peripheral surface of the nozzle tip 1 to 5 mm is preferably 15 parts by weight or more and 300 parts by weight or less per 100 parts by weight of the inorganic fibers.

This nozzle tip is composed of an inorganic fiber and an inorganic binder, is excellent in fire resistance, corrosion resistance, heat resistance, and thermal shock resistance, and does not require preheating when raising the temperature. Moreover, a cooling mechanism such as water cooling or air cooling is not required. Furthermore, it is lightweight and excellent in handling.

As inorganic fibers, alumina fibers having an alumina weight fraction of 65% by weight or more are preferable, and specific examples include alumina/silica, zirconia, spinel, titania, and the like containing these alone or in combination, but particularly Alumina/silica fibers, particularly polycrystalline alumina/silica fibers, are preferable in terms of heat resistance, fiber strength (toughness), and safety.

The alumina/silica composition ratio (weight ratio) of the alumina/silica fiber is preferably in the range called mullite composition or high alumina composition of 65 to 98/35 to 2, more preferably 70 to 95/30 to 5, particularly preferably in the range of 70-74/30-26.

It is preferable that 80% by weight or more, preferably 90% by weight or more, particularly preferably the total amount of the inorganic fibers is polycrystalline alumina/silica fibers having the above mullite composition.

In addition, the inorganic fiber contains 3 to 20% by weight of CaO, 70 to 94.5% by weight of Al ₂ O ₃ and 1 to 10% by weight of MgO, and the total content of CaO, Al ₂ O ₃ and MgO is the fiber Inorganic fibers that are 95% or more by weight of the total are also suitable. This inorganic fiber has excellent scale resistance and sufficient fiber strength as a heat insulating material.

Preferably, the block 20 comprises a laminate of needled blankets. In this case, it is preferable for the blanket to be installed so that the ends in the thickness direction thereof correspond to the inner hole surface and the tip end surface (the surface in the direction T in FIG. 7) of the nozzle tip, in terms of resistance to wind erosion caused by the fuel gas.

The inorganic fiber sheet 28 is also preferably made of a similar needle blanket.

<Inorganic binder>
The inorganic binder is not particularly limited as long as it is an inorganic fine particle. The inorganic binder material may contain one or more of an alumina component, a zirconia component, a titania component, a magnesia component, a calcia component, and the like. It is preferable to contain an alumina component, a calcia component, or a spinel component in terms of excellent mechanical properties such as wind corrosion resistance when the blanket is molded into a nozzle tip or the like. is more preferable because it can suppress corrosion due to FeO scale, and it is particularly preferable to contain an alumina component and a calcia component because it can further suppress corrosion due to FeO scale and effects can be seen even with a small addition.
The average particle size of the inorganic binder is usually 4 to 30 nm, more preferably 7 to 15 nm.
Raw materials for the inorganic binder may be inorganic sols, metal salts, or mixtures thereof that form oxides after firing.

The inorganic sol is not limited as long as an inorganic binder is uniformly dispersed in a liquid solvent, and examples include one or more of alumina sol, zirconia sol, titania sol, magnesia sol, calcia sol, and the like. Examples of metal salts include organic acid salts of the above metals such as formic acid, acetic acid, citric acid, oxalic acid, benzoic acid and malic acid, and mineral acid salts such as nitric acid. Alumina sol is preferable because its coefficient of thermal expansion is close to that of the inorganic fiber aggregate.

As inorganic binders for nozzle tips used in furnaces in which iron oxide components are present in the atmosphere, such as heating furnaces for steel products, alumina components (e.g., Al ₂ O ₃ ) and calcia components, which are iron oxide corrosion-resistant compositions, are used. (eg CaO) or a spinel-based composition comprising an alumina component (eg Al ₂ O ₃ ) and a magnesia component (eg MgO). This inorganic binder is particularly effective when the inorganic fibers of the nozzle tip are mullite (3Al ₂ O ₃ .1SiO ₂ ) fibers.

The average adhesion amount of the inorganic binder for the nozzle tip is 2 to 100 parts by mass, more preferably 10 to 60 parts by mass, based on 100 parts by mass of the inorganic fibers. Being in the above range is preferable in that scale resistance is improved, heat shrinkage is good, and moldability is good.

That is, the FeO or Fe ₂ O ₃ component in the furnace atmosphere dissolves in mullite in a high temperature range of 1000° C. or higher, and FeO or Fe ₂ O ₃ reacts with SiO ₂ to generate a low melting point phase. , the remaining alumina component crystallizes (becomes α-alumina). The formation of the low melting point phase makes the mullite fibers susceptible to corrosion.

If a magnesia (MgO) component or a calcia (CaO) component is present in the inorganic binder, the calcia component will be incorporated into the mullite fiber, particularly the fiber surface (peripheral surface of the single fiber) during the binder baking process. Since the MgO-containing mullite and the CaO-containing mullite have low reactivity with FeO or Fe ₂ O ₃ , the iron oxide corrosion resistance of the mullite fiber is improved.

The amount of magnesia and calcia components attached is 0.3 to 20 parts by mass, more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the inorganic fiber. Being in the above range is preferable in that scale resistance is improved, heat shrinkage is good, and moldability is good.

When the inorganic binder contains an alumina component and a calcia component, a calcium acetate solution in which alumina fine particles are dispersed is used as the inorganic binder liquid, and the baking temperature (firing temperature) of the inorganic binder is 900 to 1300°C, particularly 950 to 1250°C. °C is preferable.

The above-described embodiment is an example of the present invention, and the present invention may be in a form other than the above. For example, in the above-described embodiment, the recessed stepped portion 1b of the nozzle tip 1 is formed by providing the notch portion 27 in the block 20, but the nozzle nozzle tip element after the binder is adhered, dried, and fired. The concave step portion 1b may be formed by cutting the body.

Reference Signs List 1, 1' nozzle tip 1a inner hole 2 fuel nozzle 3 nozzle body 4 screw 5, 5' regenerative burner 6 furnace wall surface 10 burner tile 11 air chamber 12 air port 13, 13' fuel nozzle installation hole 20 inorganic fiber block 28 inorganic Fiber sheet 29 Compressed body 30 Inner mold

Claims (5)

In a method for manufacturing a cylindrical nozzle tip having an inner hole, which is provided at the tip of a fuel nozzle of a regenerative burner,
The nozzle tip is composed of a plurality of inorganic fiber blocks arranged in a circumferential direction surrounding the inner hole, and the nozzle tip is a cylindrical body in which the inorganic fiber blocks adjacent to each other in the circumferential direction are in close contact with each other without gaps. A method for manufacturing a nozzle tip, wherein the cylindrical body has a higher bulk density toward the inner periphery,
a first longitudinal side, a second longitudinal side parallel to the first longitudinal side, a planar third longitudinal side between the first longitudinal side and one long side of the second longitudinal side; It has a fourth longitudinal side opposite to the third longitudinal side, and a first end face and a second end face that intersect with the first to fourth longitudinal sides. A method for manufacturing a nozzle tip using an inorganic fiber block having an inclined surface that approaches a third longitudinal side toward the first longitudinal side, the method comprising:
The inorganic fiber block is made of a needle blanket of alumina-silica fibers,
A plurality of inorganic fiber blocks are placed on the outer peripheral surface of a cylindrical portion of an inner mold having a cylindrical portion so as to surround the outer peripheral surface, and the inorganic fiber blocks are adjacent to the third longitudinal side. and the first longitudinal side faces the outer peripheral surface of the cylindrical portion, and the adjacent inorganic fiber blocks are pressed against each other, and each inorganic fiber block is compressed in the direction connecting the third longitudinal side and the fourth longitudinal side, and the adjacent inorganic fiber blocks are brought into close contact with each other without gaps to form a tubular body surrounding the tubular portion,
When compressing each inorganic fiber block in the thickness direction, the compressibility of the bulk density on the inner peripheral side of the cylindrical body is set to 30 to 65%, and the compressibility of the bulk density on the outer peripheral side is set to 20 to 40%,
An inorganic fiber sheet is wrapped around the outer periphery of the cylindrical body to form a sheet-attached cylindrical body,
An outer mold consisting of a pair of half-split bodies is attached so as to surround the outer periphery of the tubular body with the sheet. Compressed to form a compressed body,
The inner mold and outerAshimpregnating the compressed body sandwiched between the molds with an inorganic binder liquid to form an inorganic binder liquid-adhered compressed body;
Next, the compressed body with the inorganic binder liquid is dried,
After drying, remove the outer mold and the inner mold,
After that, it is fired to bake the inorganic binder liquid onto the inorganic fibers.
A method for manufacturing a nozzle tip comprising steps. 2. The method of manufacturing a nozzle tip according to claim 1, wherein said inorganic fibers are alumina-silica fibers. 3. The method of manufacturing a nozzle tip according to claim 1, wherein said inorganic binder liquid contains an alumina component. 4. The method for manufacturing a nozzle tip according to claim 1, wherein said inorganic binder liquid contains an iron oxide corrosion resistant composition. In a method of manufacturing a fuel nozzle for a regenerative burner to be inserted into a fuel port of a regenerative burner, the manufacturing method of the nozzle tip according to any one of claims 1 to 4 is attached to the tip of the metallic cylindrical nozzle body. A method of manufacturing a fuel nozzle comprising the step of attaching a nozzle tip manufactured in

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