JP6792528B2 - Rotary hearth furnace and its modification method - Google Patents

Description

The present invention is premised on the use of a heat storage type burner, and it is possible to improve the stirring property of the furnace air in the furnace and make the temperature distribution in the furnace uniform while sufficiently exerting the energy saving effect thereof. At the same time, the present invention relates to a rotary hearth furnace capable of increasing the number of installable units by appropriately arranging burners and ensuring a sufficient amount of combustion, and a method for modifying the rotary hearth furnace.

Conventionally, the "rotary hearth furnace" of Patent Document 1 is known as an indicator of a rotary hearth furnace. With respect to the generation of the atmosphere in the furnace for this type of rotary hearth furnace, Patent Document 2 "raw material mass for producing reduced iron" is known. In Patent Document 2, a plurality of burners are arranged on the outer peripheral wall of a rotary hearth furnace to generate a flame toward the inside of the furnace, and exhaust is performed from a single exhaust port on the ceiling.

On the other hand, in the "non-ferrous metal melting furnace device" of Patent Document 4, the heat storage type alternating combustion burner is cylindrical by using the technique of alternating combustion of the heat storage type burner as disclosed in the "heating furnace" of Patent Document 3. It is arranged on the furnace wall of.

Japanese Patent No. 5841296 Japanese Unexamined Patent Publication No. 2013-14791 Japanese Unexamined Patent Publication No. 2012-11588 Japanese Unexamined Patent Publication No. 7-71879

Regarding the generation of the atmosphere in the furnace, Patent Document 2 has a problem that the temperature distribution in the furnace is non-uniform because the distances from each of the plurality of burners to the single exhaust port are different.

In Patent Document 4, since the adjacent heat storage type burners are alternately burned alternately, the heat generated by the flame of the burner in the combustion mode is immediately sucked by the burner in the adjacent exhaust mode, and an energy saving effect can be obtained. At the same time, there is a problem that the temperature distribution in the furnace becomes uneven.

Further, as in Patent Document 2 and Patent Document 4, if a plurality of burners are simply arranged around the outer peripheral wall portion or the cylindrical furnace wall, the agitation of the furnace air in the furnace is poor and the temperature distribution in the furnace is uniform. There was a problem that it was not possible to secure sufficient conversion. Further, there is also a problem that it is not possible to install a number of burners that can secure the required amount of combustion in the surrounding space only by installing the burners around the outer peripheral wall and the furnace wall.

The present invention has been devised in view of the above-mentioned conventional problems, and on the premise that a heat storage type burner is used, the stirring property of the furnace air in the furnace is improved while sufficiently exerting the energy saving effect. It is possible to make the temperature distribution in the furnace uniform, and increase the installation space of the burner by using the ceiling to increase the number of burners that can be installed and secure a larger amount of combustion than before. It is an object of the present invention to provide a rotary hearth furnace capable of the above and a method for modifying the same.

The rotary hearth furnace according to the present invention is a rotary hearth furnace in which a rotary hearth is provided in a furnace formed by surrounding at least a cylindrical outer peripheral wall portion and a ceiling portion, and the above ceiling portion has the above. A heat storage type ceiling burner provided with the crater facing into the furnace, and a heat storage type peripheral wall provided on the outer peripheral wall with the crater facing into the furnace from the tangential direction thereof and alternately burned with the ceiling burner. The ceiling burner and the peripheral wall burner are provided in a plurality and the same number, the ceiling burners are arranged at equal intervals in the rotation direction of the rotary hearth, and the peripheral wall burners are adjacent ceiling burners. It is characterized in that it is arranged in the middle of each other .

The ceiling burner is a burner that produces a swirling flame.

The crater portion of the peripheral wall burner is characterized in that the swivel type flame of the ceiling burner is directed in a direction opposite to the direction along the outer peripheral wall portion.

The crater portion of the ceiling burner is formed so as to expand toward the inside of the furnace.

The method for remodeling a rotary hearth furnace according to the present invention is a method for remodeling an existing rotary hearth furnace in which a rotary hearth is provided in a furnace formed by surrounding at least a cylindrical outer peripheral wall portion and a ceiling portion. Te, to the ceiling of the existing rotary hearth furnace, toward the crater portion into the furnace, the regenerative ceiling burners provided on the outer peripheral wall portion, toward the crater portion from tangentially into the furnace A heat storage type peripheral wall burner that is alternately burned with the ceiling burner is provided, a plurality of the ceiling burners and the peripheral wall burners are provided in the same number, and the ceiling burners are arranged at equal intervals in the rotation direction of the rotary hearth. It is characterized in that the peripheral wall burner is arranged and modified between the adjacent ceiling burners .

In the rotary hearth furnace and the method for modifying the rotary hearth furnace according to the present invention, it is possible to improve the agitation of the furnace air in the furnace and make the temperature distribution in the furnace uniform while sufficiently exerting the energy saving effect. At the same time, by increasing the installation space of the burner by using the ceiling part, the number of burners that can be installed can be increased, and a larger amount of combustion can be secured than before.

It is a perspective view which shows typically one preferable embodiment of the rotary hearth furnace which concerns on this invention and the modification method thereof. FIG. 5 is a plan sectional view illustrating a combustion state of a ceiling burner in the rotary hearth furnace shown in FIG. 1. It is explanatory drawing explaining the main part of the ceiling burner applied to the rotary hearth furnace shown in FIG. It is explanatory drawing which shows the equipment layout of the rotary hearth furnace shown in FIG. 1 when the ceiling burner is in a combustion mode, and the peripheral wall burner is in an exhaust mode. FIG. 5 is a plan sectional view illustrating a combustion state of a peripheral wall burner in the rotary hearth furnace shown in FIG. 1. It is explanatory drawing which shows the equipment layout of the rotary hearth furnace shown in FIG. 1, and shows the peripheral wall burner in the combustion mode, and the ceiling burner in the exhaust mode. It is a side sectional view which shows the modification of the ceiling burner applied to the rotary hearth furnace which concerns on this invention.

Hereinafter, a preferred embodiment of the rotary hearth furnace and the method for modifying the rotary hearth furnace according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a perspective view schematically showing a preferred embodiment of the rotary hearth furnace according to the present embodiment, and FIG. 2 is the rotary hearth furnace shown in FIG. 1, showing the combustion state of the ceiling burner. A plan sectional view to be described, FIG. 3 is an explanatory view for explaining a main part of the ceiling burner applied to the rotary hearth furnace shown in FIG. 1, and FIG. 4 is an equipment layout of the rotary hearth furnace shown in FIG. An explanatory view showing the ceiling burner in the combustion mode and the peripheral wall burner in the exhaust mode, FIG. 5 is a plan sectional view illustrating the combustion state of the peripheral wall burner in the rotary hearth furnace shown in FIG. FIG. 6 is an explanatory diagram showing the equipment layout of the rotary hearth furnace shown in FIG. 1 when the peripheral wall burner is in the combustion mode and the ceiling burner is in the exhaust mode.

As shown in FIGS. 1 and 2, the rotary hearth furnace 1 according to the present embodiment has an annular rotary hearth 2 that is horizontally rotationally driven clockwise or counterclockwise with a furnace body 3 from above. Consists of covering. The furnace body 3 is a cylindrical inner peripheral wall portion 4 provided located inside the inner peripheral edge of the annular rotary hearth 2, and a cylindrical body provided located outside the outer peripheral edge of the rotary hearth 2. It is composed of an outer peripheral wall portion 5 having a shape, and an annular ceiling portion 6 provided above the rotary hearth 2 so as to bridge between the upper end portion of the outer peripheral wall portion 5 and the upper end portion of the inner peripheral wall portion 4. , The rotary hearth 2 is provided in the furnace F partitioned by the furnace body 3.

The object to be heated (not shown) is placed on the rotary hearth 2 from an inlet (not shown) provided on the outer peripheral wall portion 5, heated while rotating, and provided on the outer peripheral wall portion 5. It is taken out from the outlet (not shown).

The ceiling portion 6 is provided with at least one heat storage type ceiling burner 7 in the present embodiment. The plurality of ceiling burners 7 are arranged at equal intervals in the rotation direction of the rotary hearth 2 (indicated by an arrow R in the drawing). In the illustrated example, four ceiling burners 7 are provided at 90 ° intervals. As shown in FIG. 3, the ceiling burner 7 is provided with its crater portion 7a penetrating the ceiling portion 6 and facing the inside F of the furnace, whereby the flame Mc is directed directly below the ceiling portion 6. ..

At least one, in the present embodiment, a plurality of heat storage type peripheral wall burners 8 are provided on the outer peripheral wall portion 5 below the ceiling portion 6. Similar to the ceiling burner 7, the plurality of peripheral wall burners 8 are arranged at equal intervals in the rotation direction of the rotary hearth 2. In relation to the ceiling burner 7, the peripheral wall burners 8 are arranged in the same number as the ceiling burners 7 at an intermediate position between the ceiling burners 7 adjacent to each other in the rotation direction of the rotary hearth 2. In the illustrated example, four peripheral wall burners 8 are provided alternately with four ceiling burners 7 at intervals of 90 °.

Further, the ceiling burner 7 is located above, while the peripheral wall burner 8 is located below it. As shown in FIG. 2, the peripheral wall burner 8 has its crater portion 8a connected to the outer peripheral wall portion 5 from the tangential direction of its plane circular shape, whereby the flame Mw is directed along the outer peripheral wall portion 5. ing. The ceiling burner 7 and the peripheral wall burner 8 provided in the same number are set as one set, and alternating combustion is performed in this set as a unit.

Both the ceiling burner 7 and the peripheral wall burner 8 are heat storage type burners. The heat storage type burner itself is well known, and as shown in FIGS. 1, 2, 4 to 6, the burner bodies 7b and 8b having craters 7a and 8a opened toward the inside F and the craters. On the opposite side of the portions 7a and 8a, heat storage portions 7c and 8c provided directly connected to the burner main bodies 7b and 8b are provided.

Then, a combustion mode in which flames Mc and Mw are ejected from the craters 7a and 8a of the burner bodies 7b and 8b toward the furnace F to heat the furnace F, and a furnace air of the furnace F from the craters 7a and 8a. The exhaust mode in which is discharged as exhaust Ec and Ew is alternately and repeatedly operated by the ceiling burner 7 and the peripheral wall burner 8 of the rotary hearth furnace 1 according to the present embodiment. The furnace air that fills the furnace F during the combustion operation of the burners 7 and 8 becomes exhaust Ec and Ew when discharged from the furnace F. Therefore, in the following explanation, the discharged furnace air is referred to as exhaust Ec. , Ew.

In the heat storage type burner, in the exhaust mode, the exhaust Ec and Ew discharged from the furnace F are circulated to the heat storage units 7c and 8c, whereby the exhaust heat of the exhaust Ec and Ew is stored in the heat storage units 7c and 8c. The exhaust that has passed through the heat storage units 7c and 8c is cooled and discharged to the exhaust system 9. After that, when the operation is switched from the exhaust mode to the combustion mode, the air supply of the air supply system 10 having the air supply blower 10a Combustion air is circulated to the heat storage units 7c and 8c by the action, and the combustion air is preheated (heated) by the exhaust heat of the exhaust Ec and Ew stored in the heat storage units 7c and 8c.

Then, the preheated combustion air is supplied to the burner bodies 7b and 8b, mixed with the fuel gas f supplied through the fuel nozzles 12a provided in the vicinity of the craters 7a and 8a, and burned. The burner bodies 7b and 8b generate flames Mc and Mw by energy-saving operation using exhaust heat.

When a heat storage type burner is used, at least one pair of the heat storage type burners, that is, the ceiling burner 7 and the peripheral wall burner 8, is used so that the temperature inside the furnace does not fluctuate as the operation mode is switched between the combustion mode and the exhaust mode. Used in combination.

When one of the heat storage burners (for example, ceiling burner 7) is in combustion mode, the other heat storage burner (for example, peripheral wall burner 8) is operated in exhaust mode, and when the former is switched to exhaust mode, the latter. The operation is controlled so that the combustion mode and the exhaust mode alternate between the pair of heat storage burners at regular time intervals (for example, 1 minute intervals) so that the combustion mode can be switched to the combustion mode.

In the heat storage portions 7c and 8c of the burners 7 and 8, the crater portions 7a and 8a facing the furnace F are the exhaust inlet side (combustion air outlet side), and the side opposite to the crater portions 7a and 8a is the exhaust outlet side ( It becomes the combustion air inlet side).

Therefore, in the heat storage units 7c and 8c of each of the heat storage type burners, in the exhaust mode, the exhaust Ec and Ew flow from the crater portions 7a and 8a toward the heat storage units 7c and 8c and exhaust outlets of the heat storage units 7c and 8c. The combustion air is discharged from the side to the exhaust system 9, and in the combustion mode, the combustion air is supplied from the air supply system 10 to the exhaust outlet side of the heat storage units 7c and 8c, and is supplied from the heat storage units 7c and 8c to the craters 7a and 8a. It is preheated by circulating toward it.

In the rotary hearth furnace 1 according to the present embodiment, the ceiling burner 7 and the peripheral wall burner 8 are burner bodies 7b and 8b having crater portions 7a and 8a opened toward the inside F, respectively, and burner bodies 7b and 8b. A fuel gas that is provided adjacent to the heat storage portions 7c and 8c connected to the crater portions 7a and 8a on the opposite sides and the burner main bodies 7b and 8b and mixed with combustion air to generate flames Mc and Mw. A fuel nozzle 12a that injects fuel such as f toward the craters 7a and 8a, a fuel supply pipe 12b that is connected to the fuel nozzle 12a and supplies the fuel f, and a fuel supply pipe 12b are provided to supply the fuel f. The fuel supply system 12 consisting of the fuel on-off valve 12c (in the figure, the white display is open; the black solid display is closed) for controlling the stop, the air supply blower 10a for supplying combustion air, and the amount of air supply are adjusted. It has an air supply damper 10b to be used, and an openable and closable air supply valve 10c (in the figure, the white display is open; the solid black display is closed) that controls the supply and stop of combustion air, and the heat storage units 7c and 8c. An air supply system 10 for supplying combustion air toward the exhaust outlet side and an openable and closable exhaust valve 9a for controlling the discharge / stop of exhaust Ec and Ew (in the figure, the white display is open; solid black display). Has an exhaust damper 9b that adjusts the amount of exhaust, and heat storage units 7c, 8c so that the exhaust Ec, Ew of the furnace F is discharged toward the flue 9c through the crater portions 7a, 8a. It is configured to include an exhaust system 9 through which exhausts Ec and Ew flowing out from the exhaust outlet side of the above are distributed. The flue 9c is connected to the chimney 9d.

In detail, the air supply system 10 is provided with an air supply blower 10a, and is supplied with an air supply collecting pipe 10d capable of supplying combustion air to both the ceiling burner 7 and the peripheral wall burner 8 as a set. A plurality of air supply pipes 10e branched from the air collecting pipe 10d and for supplying combustion air to the heat storage portions 7c and 8c of the ceiling burner 7 and the peripheral wall burner 8, respectively, and the above-mentioned air supply pipes 10e provided. It is composed of an air supply valve 10c.

Specifically, the exhaust system 9 is connected to the flue 9c and branches from an exhaust collecting pipe 9e capable of exhausting exhaust Ec and Ew from both a pair of ceiling burners 7 and a peripheral wall burner 8 and an exhaust collecting pipe 9e. It is composed of an exhaust pipe 9f for exhausting exhaust Ec and Ew from the heat storage portions 7c and 8c of the ceiling burner 7 and the peripheral wall burner 8, respectively, and the exhaust valve 9a provided for each exhaust pipe 9f. Will be done.

In either the ceiling burner 7 or the peripheral wall burner 8, the air supply valve 10c supplies combustion air to the craters 7a and 8a of the burners 7b and 8b via the heat storage portions 7c and 8c in the combustion mode. It is opened to stop the supply of combustion air when in exhaust mode.

Regardless of whether the exhaust valve 9a is the ceiling burner 7 or the peripheral wall burner 8, in the exhaust mode, the exhaust Ec and Ew of the furnace F are passed through the heat storage portions 7c and 8c to the crater portions 7a of the burner main bodies 7b and 8b. , 8a, opened to exhaust, and in combustion mode, closed to stop exhaust Ec, Ew. The air supply blower 10a is normally always operated during the operation of the rotary hearth furnace 1.

The fuel on-off valve 12c is opened to supply the fuel f to the fuel nozzle 12a in the combustion mode, and stops the supply of the fuel f in the exhaust mode, regardless of whether the ceiling burner 7 or the peripheral wall burner 8 is used. Closed to do.

As illustrated in FIG. 4, in the ceiling burner 7 in the combustion mode, the exhaust valve 9a is closed and the air supply valve 10c is opened, and the combustion air sent by the air supply action of the air supply system 10 is charged. , It is distributed from the air supply collecting pipe 10d of the air supply system 10 to the heat storage unit 7c via the air supply valve 10c of the air supply pipe 10e, and is further supplied from the heat storage unit 7c to the crater portion 7a of the burner main body 7b. It has become.

Then, the fuel on-off valve 12c of the fuel nozzle 12a is opened, the fuel f is supplied from the fuel supply pipe 12b toward the crater portion 7a, and the flame Mc is formed. When the inside of the furnace body 3 is equal to or higher than the self-combustion temperature of the fuel f, it spontaneously ignites, but when the temperature is lower than that, it is ignited by a spark plug or a pilot burner (not shown).

On the other hand, in the peripheral wall burner 8 in the exhaust mode, the exhaust valve 9a is opened and the air supply valve 10c is closed, and the exhaust Ec in the furnace F is circulated from the crater portion 8a of the burner main body 8b to the heat storage portion 8c. Further, the heat is discharged from the heat storage unit 8c from the exhaust pipe 9f to the exhaust collecting pipe 9e of the exhaust system 9 via the exhaust valve 9a.

The ceiling burner 7 is further referred to as a swirl flame generation type burner that generates a swirl type flame Mc from the ceiling portion 6 toward the furnace F immediately below the ceiling portion 6. As shown in FIG. 3, the ceiling burner 7 is formed in a cylindrical shape in which the crater portion 7a side of the burner main body 7b determines the cylindrical space 11 inside. FIG. 3A is a side sectional view of the ceiling burner 7 around the crater portion 7a, and FIG. 3B is a sectional view taken along the line AA in FIG. 3A. The cylindrical space 11 constitutes a combustion chamber that generates a flame Mc with the fuel f from the fuel nozzle 12a.

Further, the burner main body 7b has a nozzle flow path 13 that opens in the upper part of the cylindrical space 11. The nozzle flow path 13 has a first side surface 13a formed of a plane in contact with the cylindrical surface of the cylindrical space 11 and a second side surface formed of a plane extending in parallel with the first side surface 13a facing the first side surface 13a. It includes a 13b and a third side surface 13c formed of a plane that bends from the second side surface 13b and extends at an angle of 90 ° and is in contact with the cylindrical space 11.

Further, the top surface 13d of the nozzle flow path 13 extends so as to be continuous with the top surface of the cylindrical space 11, and the bottom surface 13e of the nozzle flow path 13 is parallel to the top surface. That is, the top surface 13d and the bottom surface 13e of the nozzle flow path 13 are planes that intersect at right angles to the central axis X of the cylindrical space 11.

The nozzle flow path 13 is defined by a first side surface 13a and a second side surface 13b, and has two contacts, a slit-shaped approach portion 14 having a constant cross section and a cylindrical space 11 intersecting each other at an angle of 90 ° or less. It consists of an opening 15 defined by a first side surface 13a and a third side surface 13c, which are surfaces. The other end of the nozzle flow path 13 communicates with the heat storage unit 7c. The fuel nozzle 12a is opened toward the cylindrical space 11.

The combustion air is blown from the nozzle flow path 13 in the tangential direction along the cylindrical inner wall of the burner main body 7b forming the cylindrical space 11, and a spirally swirling airflow is formed in the cylindrical space 11. The flame Mc formed by burning the fuel f supplied from the fuel nozzle 12a rides on this swirling airflow and extends spirally. The flame Mc ejected from the crater portion 7a into the furnace F rides on the swirling airflow and forms a spiral flow that spreads outward in the radial direction over the entire circumference, and the flame Mc swirls and forms an umbrella shape. It spreads and is formed.

On the other hand, the peripheral wall burner 8 generates a flame Mw that goes straight from the crater portion 8a, and the flame Mw of the peripheral wall burner 8 is along the outer peripheral wall portion 5 as shown in FIG. The flame Mw of the peripheral wall burner 8 is a long flame having a long linear distance from the crater portion 8a to the flame tip, while the flame Mc of the ceiling burner 7 has a linear distance from the crater portion 7a to the flame tip due to the swirling action. It is said to be a short short flame.

As a result, the distance between the heated object placed on the rotary hearth 2 and the flames Mc and Mw is secured, so that the flames Mc and Mw come into contact with the heated object and become locally hot. It also prevents damage to the object to be heated. Further, the entire furnace body 3 can be miniaturized.

As shown in FIG. 2, the crater portion 8a of the peripheral wall burner 8 is directed so that the flame Mc of the ceiling burner 7 swirling in the furnace F faces the direction along the outer peripheral wall portion 5. That is, as can be understood by looking at FIG. 5 together with FIG. 2, if the peripheral wall burner 8 and the ceiling burner 7 are burned at the same time, the flame Mw of the peripheral wall burner 8 and the flame Mc of the ceiling burner 7 become the outer peripheral wall. The crater portion 8a of the peripheral wall burner 8 is faced in a direction that causes a collision just inside the portion 5. Actually, since the peripheral wall burner 8 and the ceiling burner 7 are alternately burned, there is no collision between the flames Mc and Mw.

In other words, when the flame Mc of the ceiling burner 7 is viewed from the position of the outer peripheral wall portion 5 due to the relationship between the pair of peripheral wall burners 8 and the ceiling burner 7 for alternating combustion, the flame Mc turns counterclockwise. The crater portion 8a of the peripheral wall burner 8 is provided on the right side from the viewing position, and is provided on the left side when the flame Mc turns clockwise.

Then, as shown in FIGS. 2 and 5, the furnace air (exhaust) in the furnace F becomes a unidirectional flow toward the ceiling burner 7 (indicated by the arrow Dw in FIG. 5) when the peripheral wall burner 8 burns. On the other hand, when the ceiling burner 7 is burned, the flow is in the opposite direction toward the peripheral wall burner 8 (indicated by the arrow Dc in FIG. 2), and the alternating combustion for switching between the ceiling burner 7 and the peripheral wall burner 8 is repeated. , The furnace air repeatedly flows in the opposite directions.

Since the furnace air repeatedly flows in the opposite directions in the forward and reverse directions, the direction of the flame Mw of the peripheral wall burner 8 may be the direction along the rotation direction R of the rotary hearth 2, or opposite to the rotation direction R. The orientation may be either. Similarly, the turning direction of the flame Mc of the ceiling burner 7 may be either a right turn or a left turn as long as the above relationship with the peripheral wall burner 8 is maintained.

Next, the operation of the rotary hearth furnace 1 according to the present embodiment will be described. During the operation of the rotary hearth furnace 1, as shown in FIGS. 2 and 4, when the ceiling burner 7 is in the combustion mode and the peripheral wall burner 8 is in the exhaust mode, the combustion air and the fuel nozzle heated by the heat storage unit 7c The flame Mc generated at the crater portion 7a of each ceiling burner 7 by the fuel f from 12a spreads from a plurality of places toward the inside F as a swirling flow of a short flame, and the furnace air due to this swirling flame spreads from the inside F. It spreads to.

The crater undergoing the swirling action is directed in one direction around the outer peripheral wall portion 5 along the circumferential direction of the furnace body 3 (in the opposite direction around the inner peripheral wall portion 4), and is the entire inside F of the furnace. It is discharged as exhaust Ec from each crater portion 8a of the plurality of peripheral wall burners 8 provided on the outer peripheral wall portion 5 below the ceiling portion 6 while spreading to.

Next, when the ceiling burner 7 is switched to the exhaust mode and the peripheral wall burner 8 is switched to the combustion mode, the long flame generated at the crater portion 8a of each peripheral wall burner 8 is as shown in FIGS. 5 and 6. The flame Mw traveling straight spreads to the inside F along the outer peripheral wall portion 5, and the furnace air due to this long flame diffuses into the inside F.

The crater air spreads around the outer peripheral wall portion 5 along the circumferential direction of the furnace body 3 in the direction opposite to that at the time of combustion of the ceiling burner 7 throughout the furnace F, and the ceiling portion 6 above the outer peripheral wall portion 5 It is discharged as exhaust Ew from each crater portion 8a of the plurality of ceiling burners 7 provided in the above. Then, each time the mode is switched between the ceiling burner 7 and the peripheral wall burner 8, the flow of the furnace air repeats from top to bottom, from bottom to top, and also in the opposite directions around the outer peripheral wall portion 5. It is designed to switch repeatedly.

By such a three-dimensional stirring action, the temperature of the entire furnace F is made uniform, the furnace air comes into contact with the object to be heated from various directions, and the object to be heated is also uniformly heated.

In the rotary hearth furnace 1 according to the present embodiment, the heat storage type ceiling burner 7 provided on the ceiling portion 6 with the crater portion 7a facing the inside F and the outer peripheral wall portion 5 from the tangential direction thereof. Since the crater portion 8a is provided toward the furnace F and the ceiling burner 7 and the heat storage type peripheral wall burner 8 for alternating combustion are provided, the peripheral wall burner 8 and the ceiling burner 7 alternate during the operation of the rotary hearth furnace 1. By being burned, the furnace air in the furnace F flows from the ceiling portion 6 toward the outer peripheral wall portion 5 below it, and flows from the outer peripheral wall portion 5 toward the ceiling portion 6 above it. It is repeated, and the flow along the outer peripheral wall portion 5 is also repeatedly switched in the opposite directions, so that the stirring action of the furnace air in the furnace F can be promoted. As a result, the temperature distribution in the furnace can be made uniform.

Further, the flame Mc generated by the ceiling burner 7 flows from the ceiling 6 along the ceiling surface without directly heading to the crater portion 8a of the peripheral wall burner 8, and the flame Mw generated by the peripheral wall burner 8 also flows. And the exhaust Ew does not go directly to the crater portion 7a of the ceiling burner 7 of the ceiling portion 6, but goes toward the circumferential direction of the outer peripheral wall portion 5, so that the object to be heated on the rotary hearth 2 is flamed. It becomes difficult for Mc and Mw to come into contact with each other, and it is possible to prevent the flame Mc and Mw from coming into contact with the object to be heated and causing damage. Further, it is possible to prevent the exhausts Ec and Ew of the ceiling burner 7 and the peripheral wall burner 8 from being immediately discharged from the neighboring craters 7a and 8a, and the energy saving effect of the heat storage type burner can be sufficiently exhibited.

Since the heat storage type burner is attached to the ceiling portion 6 and the outer peripheral wall portion 5 as a set, a wider installation space for the burner is secured up to the ceiling portion 6 as compared with the case where the burner is provided only on the outer peripheral wall portion 5. It is possible to obtain a layout that can increase the number of burner equipment, and it is possible to secure a larger amount of combustion than before.

Since the ceiling burner 7 is a swirling flame generation type burner, the furnace air not only flows up and down between the ceiling portion 6 and the outer peripheral wall portion 5 and is agitated, but also by the swirling flame Mc of the ceiling burner 7. The stirring action can be further promoted.

The direction of the crater portion 8a of the peripheral wall burner 8 is directed so that the swivel type flame Mc of the ceiling burner 7 faces the direction along the outer peripheral wall portion 5, and the outer peripheral wall is accompanied by the swirling flow by the ceiling burner 7. The furnace air flowing along the portion 5 smoothly flows into the crater portion 8a of the peripheral wall burner 8 facing the direction opposite to the direction of the flow as an exhaust Ec, so that it can be smoothly discharged. The furnace air flowing along the outer peripheral wall portion 5 along with the flame Mw of the peripheral wall burner 8 can also flow into the crater portion 7a of the ceiling burner 7 as exhaust Ew without any trouble and be discharged satisfactorily.

A plurality of and the same number of ceiling burners 7 and peripheral wall burners 8 are provided, the ceiling burners 7 are arranged at equal intervals in the rotation direction R of the rotary hearth 2, and the peripheral wall burners 8 are located between the adjacent ceiling burners 7. Since the burners 7 and 8 are arranged evenly in the rotary hearth furnace 1 as a whole, the temperature distribution in the furnace can be appropriately made uniform from the viewpoint of the burner arrangement.

FIG. 7 is a side sectional view showing a modified example of the ceiling burner 7 used in the rotary hearth furnace 1 according to the above embodiment. In this modification, the crater portion 7a of the ceiling burner 7 is formed so as to expand toward the inside F in order to increase the turning radius of the swivel type flame Mc.

That is, as shown in the figure, the crater portion 7a is formed with a diameter-expanded portion that defines a diameter-expanded space 16 that expands in diameter from the cylindrical space 11 toward the inside F of the furnace. A combustion chamber is composed of a cylindrical space 11 and an enlarged diameter space 16. The diameter-expanding space 16 has a larger diameter-expanding ratio toward the F side in the furnace.

When the flame Mc (swirl airflow) generated in the cylindrical space 11 reaches the enlarged diameter space 16, the swirling radius of the swirling airflow expands according to the shape. Then, the swirling airflow reaching the inside F forms a spiral flow that spreads outward in the radial direction and along the ceiling portion 6 all around. As a result, the apparent flame Mc spreads like an umbrella. Since the swirling flow of the flame Mc of the ceiling burner 7 is expanded in this way, the uniformization of the temperature distribution in the furnace can be further promoted, and the flame Mc can be made less likely to come into contact with the object to be heated.

Further, for example, when the rotary hearth furnace as in Patent Document 2 is an existing one, if a heat storage type ceiling burner 7 is added to the furnace and the peripheral wall burner is replaced with the heat storage type peripheral wall burner 8, the furnace can be modified. That is, as a method of modifying an existing rotary hearth furnace in which a rotary hearth 2 is provided in a furnace F formed by surrounding at least a cylindrical outer peripheral wall portion 5 and a ceiling portion 6, the existing rotary hearth furnace 1 is used. A heat storage type ceiling burner 7 is provided on the ceiling portion 6 of the above with the crater portion 7a directed toward the inside F, and the crater portion 8a is directed toward the inside F from the tangential direction thereof on the outer peripheral wall portion 5 with the ceiling burner 7. A heat storage type peripheral wall burner 8 for alternating combustion is provided, a plurality of ceiling burners 7 and a peripheral wall burner 8 are provided in the same number, and the ceiling burners 7 are arranged at equal intervals in the rotation direction of the rotary hearth 2 and the peripheral wall burner 8 is provided. Is arranged in the middle between the adjacent ceiling burners 7 and remodeled, even if the rotary hearth furnace is already installed , the same operation and effect as that of the rotary hearth furnace 1 of the above embodiment Can be obtained.

1 Rotating hearth furnace 2 Rotating hearth 3 Furnace 4 Inner peripheral wall 5 Outer wall 6 Ceiling 7 Heat storage type ceiling burner 7a Ceiling burner crater 7b, 8b Burner body 7c, 8c Heat storage part 8 Heat storage type peripheral wall burner 8a Peripheral wall burner crater 9 Exhaust system 9a Exhaust valve 9b Exhaust damper 9c Smoke path 9d Chimney 9e Exhaust collecting pipe 9f Exhaust pipe 10 Air supply system 10a Air supply blower 10b Air supply damper 10c Air supply valve 10d Air supply collecting pipe 10e Air pipe 11 Cylindrical space 12 Fuel supply system 12a Fuel nozzle 12b Fuel supply pipe 12c Fuel on-off valve 13 Nozzle flow path 13a First side surface 13b Second side surface 13c Third side surface 13d Top surface 13e Bottom surface 14 Running part 15 Opening 16 Expanded space Dc Flow of furnace air when burning the ceiling burner Dw Flow of furnace air when burning the peripheral wall burner Ec Exhaust of the ceiling burner Ew Exhaust of the peripheral wall burner F Fuel gas in the furnace Mc Flame of the ceiling burner Mw Peripheral wall burner Flame R Direction of rotation of the rotating hearth X Central axis of cylindrical space

Claims (5)

A rotary hearth furnace in which a rotary hearth is provided in a furnace formed by surrounding at least a cylindrical outer peripheral wall and ceiling.
A heat storage type ceiling burner provided on the ceiling portion with the crater portion facing into the furnace, and a heat storage type ceiling burner provided on the outer peripheral wall portion with the crater portion facing into the furnace from the tangential direction thereof, and alternate with the ceiling burner. Equipped with a heat storage type peripheral wall burner that is burned
The ceiling burners and the peripheral wall burners are provided in a plurality and the same number, the ceiling burners are arranged at equal intervals in the rotation direction of the rotary hearth, and the peripheral wall burners are arranged between the adjacent ceiling burners. A rotary hearth furnace characterized by being installed . The rotary hearth furnace according to claim 1, wherein the ceiling burner is a burner that generates a swirling flame. The rotary hearth furnace according to claim 2, wherein the crater portion of the peripheral wall burner is directed in a direction in which the swivel type flame of the ceiling burner is directed in a direction opposite to the direction along the outer peripheral wall portion. The rotary hearth furnace according to claim 2 or 3, wherein the crater portion of the ceiling burner is formed so as to expand toward the inside of the furnace. It is a method of modifying an existing rotary hearth furnace in which a rotary hearth is provided in a furnace formed by surrounding at least a cylindrical outer peripheral wall and ceiling.
To the ceiling of the existing rotary hearth furnace, toward the crater portion into the furnace, the regenerative ceiling burners provided on the outer peripheral wall portion, toward the crater portion from tangentially into the furnace, the A heat storage type peripheral wall burner that is alternately burned with the ceiling burner is installed.
The ceiling burners and the peripheral wall burners are provided in a plurality and the same number, the ceiling burners are arranged at equal intervals in the rotation direction of the rotary hearth, and the peripheral wall burners are arranged between the adjacent ceiling burners. A method of remodeling a rotary hearth furnace, which is characterized by being installed and remodeled.

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