Batch-type annealing furnace

Abstract

A batch-type annealing furnace is disclosed. A batch-type annealing furnace according to an embodiment may include: an annealing chamber accommodating a material coil; a combustion chamber provided with a burner jetting a flame and partitioned in a state capable of ventilation with the annealing chamber; a blowing fan providing a blowing force such that a fluid in the combustion chamber is blown to the annealing chamber; a duct guiding a flow of the fluid blown from the combustion chamber to the annealing chamber; and a nozzle connected to the duct to inject the fluid guided to the annealing chamber through the duct onto the coil.

Description

[Technical Field]

[0001] The present disclosure relates to a batch-type annealing furnace.[Background Art]

[0002] In a steel process, a coil manufactured by rolling is subjected to an annealing treatment to remove work hardening.

[0003] Among annealing furnaces for the annealing treatment, there are a continuous annealing furnace in which a coil is unwound and continuously heat-treated, and a batch-type annealing furnace in which a coil is heat-treated in a wound state.

[0004] In the case of the batch-type annealing furnace, heat treatment of the coil is possible even in a narrow space, so facility investment costs are low, and a range of materials used is wide, providing an advantage that expansion of use is easy.

[0005] Among the batch-type annealing furnaces, there is a type that directly heats the coil using a burner installed inside an annealing chamber. At this time, the burner generates a flame at a high temperature of 1800°C or higher, and the coil in the annealing chamber is heated by radiant heat from the flame.

[0006] However, in a heating method in which the coil is heated while directly exposed to the flame, there is a high concern that an outer turn portion side of the coil adjacent to the flame is overheated, resulting in over-annealing or rupture.

[0007] In addition, at this time, since the coil is heated to different temperatures for each portion depending on a distance from the flame, it may be difficult to uniformly anneal the coil as a whole.[Disclosure][Technical Problem]

[0008] An aspect of the present disclosure provides a batch-type annealing furnace capable of uniformly annealing a coil without a concern of being locally over-annealed or ruptured.

[0009] An aspect of the present disclosure provides a batch-type annealing furnace capable of reducing an amount of NOx generation according to an annealing treatment of a coil.[Technical Solution]

[0010] A batch-type annealing furnace according to the spirit of the present disclosure may include: an annealing chamber accommodating a material coil; a combustion chamber provided with a burner jetting a flame and partitioned in a state capable of ventilation with the annealing chamber; a blowing fan providing a blowing force such that a fluid in the combustion chamber is blown to the annealing chamber; a duct guiding a flow of the fluid blown from the combustion chamber to the annealing chamber; and a nozzle connected to the duct to inject the fluid guided to the annealing chamber through the duct onto the coil.

[0011] A plurality of coils may be accommodated in the annealing chamber, and the nozzle may be configured in plural numbers to individually inject the fluid onto each coil.

[0012] The nozzle may inject the fluid into a hollow portion at a center of the coil.

[0013] The nozzle may be provided as a single-hole type having one injection hole, and a center of the injection hole may coincide with a center of the hollow portion.

[0014] The nozzle may be provided as a multi-hole type having a plurality of injection holes, and the plurality of injection holes may include a first injection hole having a center coincident with a center of the hollow portion, and a plurality of second injection holes disposed around the first injection hole.

[0015] The first injection hole may have a larger diameter than the second injection holes.

[0016] The nozzle may be provided as a multi-hole type having a plurality of injection holes, and each of the plurality of injection holes may have a same diameter.

[0017] The plurality of injection holes may be located on a same plane and arranged at equal intervals.

[0018] A plurality of coils may be accommodated in the annealing chamber, a plurality of nozzles may be assigned to each coil, and the plurality of nozzles assigned to each coil may inject the fluid to different portions of each coil.

[0019] An exhaust flow path opened and closed by a first opening / closing means may be connected to the annealing chamber for discharging an internal fluid, an external air introduction flow path opened and closed by a second opening / closing means may be connected to the duct for introducing external air, the duct may include a main flow path extending from the combustion chamber and a connection flow path connecting the main flow path and the nozzle, the blowing fan may be installed on the main flow path, and the batch-type annealing furnace may further include: a bypass flow path connecting to detour between two points of the main flow path toward an upstream side of a point where the blowing fan is installed; a flow switching valve provided at an intersection between the main flow path and the bypass flow path such that the fluid flowing in a direction of the nozzle passes through any one of the bypass flow path and the main flow path in a section between both ends of the bypass flow path; and a cooler for cooling the bypass flow path.

[0020] The combustion chamber and the annealing chamber may be partitioned in a state capable of ventilation through a partition wall having a ventilation hole, and the partition wall may be provided with a flame blocking unit for blocking the flame of the combustion chamber from flowing into the annealing chamber through the ventilation hole.

[0021] The combustion chamber and the annealing chamber may be partitioned in a state capable of ventilation through a partition wall having a ventilation hole, and a body of the burner may be installed such that a jetting direction of the flame avoids a direction of the partition wall.

[0022] The combustion chamber and the annealing chamber may be partitioned in a state capable of ventilation through a partition wall having a ventilation hole, the burner may include an outlet for jetting the flame, and the outlet may be provided in the burner such that a jetting direction of the flame avoids a direction of the partition wall.

[0023] The burner may be configured in plural numbers, and at least one of the plurality of burners may have a capacity different from a remainder.[Advantageous Effects]

[0024] According to the present disclosure, it is possible to provide a batch-type annealing furnace capable of uniformly annealing a coil without a concern of being locally over-annealed or ruptured.

[0025] According to the present disclosure, it is possible to provide a batch-type annealing furnace capable of reducing an amount of NOx generation according to an annealing treatment of a coil.[Description of Drawings]

[0026] FIGS. 1 to 3 are perspective views of a batch-type annealing furnace according to an embodiment, showing a structure of the batch-type annealing furnace viewed from various directions. FIGS. 4 and 5 are perspective views of the batch-type annealing furnace according to an embodiment, showing an inside of an annealing chamber. FIG. 6 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a heating process is being performed. FIG. 7 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a cooling process is being performed. FIG. 8 is an enlarged front view of a nozzle and a coil in the batch-type annealing furnace according to an embodiment. FIG. 9 is a side view of FIG. 8, and FIG. 10 is a modified example. FIGS. 11 to 13 show other modified examples of the nozzle in the batch-type annealing furnace according to an embodiment. FIG. 14 shows a modified example of the batch-type annealing furnace according to an embodiment. FIG. 15 is a main part view showing another modified example of the batch-type annealing furnace according to an embodiment. FIG. 16 is a main part view showing still another modified example of the batch-type annealing furnace according to an embodiment. [Mode for Invention]

[0027] Throughout the specification, the same reference numerals refer to the same components. The present specification does not describe all elements of the embodiments, and general contents in the technical field to which the present invention belongs or overlapping contents between the embodiments are omitted. Terms such as "unit, module, member, block" used in the specification may be implemented as software or hardware, and according to embodiments, a plurality of "units, modules, members, blocks" may be implemented as a single component, or a single "unit, module, member, block" may include a plurality of components.

[0028] Throughout the specification, when a part is referred to as being "connected" to another part, this includes not only a case where it is directly connected but also a case where it is indirectly connected, and the indirect connection includes connecting through a wireless communication network.

[0029] Also, when a part is referred to as "including" a component, this means that it may further include other components rather than excluding other components unless specifically stated to the contrary.

[0030] Throughout the specification, when a member is located "on" another member, this includes not only a case where a member is in contact with another member but also a case where another member exists between two members.

[0031] Terms such as first, second, etc. are used to distinguish one component from another component, and the components are not limited by the aforementioned terms.

[0032] The singular expression includes the plural expression unless the context clearly dictates otherwise.

[0033] Identification codes for each step are used for convenience of description, and the identification codes do not describe the order of each step, and each step may be performed differently from the specified order unless the context clearly states a specific order.

[0034] The term "and / or" may include a combination of a plurality of related described components or any component among a plurality of related described components.

[0035] Hereinafter, the operating principle and embodiments of the present invention will be described with reference to the accompanying drawings.

[0036] For reference, FIGS. 1 to 3 are perspective views of a batch-type annealing furnace according to an embodiment, showing a structure of the batch-type annealing furnace viewed from various directions. FIGS. 4 and 5 are perspective views of the batch-type annealing furnace according to an embodiment, showing an inside of an annealing chamber. FIG. 6 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a heating process is being performed. FIG. 7 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a cooling process is being performed.

[0037] As shown in FIGS. 1 to 7, a batch-type annealing furnace 1 according to an embodiment may include an annealing chamber 10, a combustion chamber 20 partitioned in a state capable of ventilation with the annealing chamber 10, a blowing fan 30 providing a blowing force such that a fluid in the combustion chamber 20 is blown to the annealing chamber 10, a duct 40 guiding a flow of the fluid blown from the combustion chamber 20 to the annealing chamber 10, and a nozzle 50 injecting the fluid guided to the annealing chamber 10 through the duct 40 onto a coil 2.

[0038] A material coil 2 to be subjected to an annealing treatment may be accommodated in the annealing chamber 10. The batch-type annealing furnace 1 is provided with a furnace body 1a, and the annealing chamber 10 may be provided through a space on one side inside the furnace body 1a. The coil 2 may be accommodated in the annealing chamber 10 so as to be supported by a support member 3 installed on a bottom of the annealing chamber 10. In the annealing chamber 10, a plurality of coils 2 may be disposed along a longitudinal direction of the annealing chamber 10. The plurality of coils 2 may be accommodated in the annealing chamber 10 to form a multi-stage structure in a form in which a part is supported by the support member 3 and another part is stacked on an upper part between the coils 2 supported by the support member 3.

[0039] An exhaust flow path 61 for discharging an internal fluid of the annealing chamber 10 is connected to one side of the annealing chamber 10, and the exhaust flow path 61 may be opened and closed by an opening / closing means 62. The opening / closing means 62 may be a first opening / closing means.

[0040] The combustion chamber 20 may be provided with a burner 21 jetting a flame. The combustion chamber 20 may be provided through a space on the other side inside the furnace body 1a. The burner 21 is configured in plural numbers, and air and fuel as an oxidant may be supplied together to each burner 21. As an ignition device is operated, a flame may be jetted into the combustion chamber 20 through the burner 21.

[0041] Inside the furnace body 1a, a partition wall 60 having a ventilation hole 61 may be provided to partition the combustion chamber 20 and the annealing chamber 10 in a state capable of ventilation.

[0042] The duct 40 may be provided to guide the fluid of the combustion chamber 20 to the annealing chamber 10. The duct 40 may be provided to connect the combustion chamber 20 and the annealing chamber 10 outside the combustion chamber 20 and the annealing chamber 10.

[0043] The duct 40 may include a main flow path 41 extending from the combustion chamber 20 and a connection flow path 42 connecting the main flow path 41 and the nozzle 50. The main flow path 41 may be connected to the combustion chamber 20 through a bottom surface of the combustion chamber 20.

[0044] The blowing fan 30 is installed in the duct 40 and may perform a blowing action such that the fluid in the combustion chamber 20 is guided to the annealing chamber 10 along the duct 40. The blowing fan 30 may be installed on the main flow path 41 of the duct 40. The blowing fan 30 may be configured as a single or plural unit depending on a shape or branching structure of the duct 40.

[0045] An external air introduction flow path 71 for introduction of external air is connected to the duct 40, and the external air introduction flow path 71 may be opened and closed by an opening / closing means 72. The opening / closing means 72 may be a second opening / closing means.

[0046] The nozzle 50 is installed at an end of the connection flow path 42 and installed to inject the fluid into the annealing chamber 10 so that the fluid guided to the annealing chamber 10 through the connection flow path 42 is injected onto the coil 2.

[0047] The batch-type annealing furnace 1 configured as described above may directly inject high-temperature combustion heat generated in the combustion chamber 20 by the flame jetted from the burner 21 onto the coil 2 through the nozzle 50.

[0048] Therefore, according to the batch-type annealing furnace 1 according to the present embodiment, by preventing the coil 2 from being exposed to the flame of the burner 21 during a process of performing the heating process of the annealing treatment, it is possible to prevent the coil 2 from being locally over-annealed or ruptured by the flame.

[0049] In addition, at this time, by allowing the high-temperature combustion heat formed in the combustion chamber 20 through the flame to be directly injected onto the coil 2 through the duct 40 and the nozzle 50, the coil 2 may be uniformly annealed as a whole using a convection phenomenon of the combustion heat.

[0050] The nozzle 50 is configured in plural numbers to individually inject the fluid onto each coil 2 disposed in the annealing chamber 10, thereby increasing heating efficiency of the coil 2 by the combustion heat.

[0051] For example, the nozzle 50 may be configured with a number corresponding to the number of coils 2 so that the combustion heat is individually injected onto each coil 2.

[0052] Also, as shown in the drawing, a plurality of nozzles 50 may be assigned to each coil 2. The plurality of nozzles 50 assigned to each coil 2 inject the fluid to different portions of each coil 2, thereby allowing various portions of the coil 2 to be heated more evenly by the combustion heat injected through the nozzles 50. For example, some nozzles 50 among the plurality of nozzles 50 may be disposed in the annealing chamber 10 at a position corresponding to one end of the coil 2 to inject the fluid toward the one end of the coil 2, and remaining nozzles 50 may be disposed in the annealing chamber 10 at a position corresponding to the other end of the coil 2 to inject the fluid toward the other end of the coil 2.

[0053] The connection flow path 42 of the duct 40 may include a plurality of first connection flow paths 42a branching from the main flow path, and a second connection flow path 42b branching from each of the first connection flow paths 42a and connected to the nozzle 50. For example, the first connection flow path 42a may be configured as a pair.

[0054] Also, each nozzle 50 may be provided to inject the fluid into a hollow portion 2a at the center of the corresponding coil 2. The fluid injected into the hollow portion 2a of the coil 2 by the nozzle 50 may secure straight flowability. This may contribute to ensuring an overall circulation flow of the combustion heat supplied from the combustion chamber 20 to the annealing chamber 10 through the duct 40 and flowing back into the combustion chamber 20.

[0055] As shown in FIGS. 8 and 9, the nozzle 50 may be provided as a single-hole type having one injection hole 51, wherein a center of the injection hole 51 coincides with a center of the hollow portion 2a of the coil 2. Such a nozzle 50 is provided with one injection hole 51, so the structure is simplified, while the fluid can be accurately injected in a direction of the center of the hollow portion 2a by the injection hole 51. The fluid injected in the direction of the center of the hollow portion 2a gradually expands and can contact the hollow portion 2a of the coil 2 and a circumference thereof evenly as a whole.

[0056] The injection hole 51 may be provided such that a diameter gradually decreases in a jetting direction of the fluid so that straightness of the injected fluid can be further increased. Also, as shown in FIG. 10, the injection hole 51 may be provided such that a diameter gradually expands in the jetting direction of the fluid so that expandability of the injected fluid can be further increased.

[0057] FIGS. 11 to 13 show modified examples of the nozzle 50.

[0058] As shown in FIG. 11, a nozzle 50a may be provided as a multi-hole type having a plurality of injection holes 51a and 52a. In such a nozzle 50a, the injection holes 51a and 52a may include a central first injection hole 51a having a center coincident with the center of the hollow portion 2a of the coil 2, and a plurality of second injection holes 52a disposed around the first injection hole 51a. The central first injection hole 51a is responsible for a function of improving straightness of fluid injection, and the second injection holes 52a disposed around the first injection hole 51a may be responsible for a function of increasing expandability of fluid injection.

[0059] Considering that the first injection hole 51a is configured as one, the first injection hole 51a may be provided to have a relatively larger diameter than the second injection holes 52a provided in plural numbers so that the straightness and expandability of the injected fluid can be evenly increased.

[0060] As shown in FIGS. 12 and 13, nozzles 50b and 50c are provided as a multi-hole type having a plurality of injection holes 51b and 51c, and the plurality of injection holes 51b and 51c may be provided to have the same diameter, respectively. In addition, in the nozzle 50c, the plurality of injection holes 51c disposed on the same plane may be arranged to be at equal intervals from each other. These nozzles 50b and 50c facilitate an increase in an injection area for injecting the fluid, so even when disposed to inject the fluid between the coils 2, the fluid can be smoothly supplied to each coil 2.

[0061] An annealing treatment process of the coil 2 using the batch-type annealing furnace 1 according to an embodiment will be described as follows.

[0062] The coil 2 may be annealed by sequentially undergoing a heating process, a soaking process, and a cooling process.

[0063] Referring back to FIG. 6, in the heating process, the burner 21 is operated to generate a flame in the combustion chamber 20, and the blowing fan 30 may be operated in a state where the exhaust flow path 61 and the external air introduction flow path 71 are closed using the first opening / closing means 62 and the second opening / closing means 72.

[0064] Accordingly, the combustion heat formed in the combustion chamber 20 through the flame is guided to the annealing chamber 10 through the duct 40 and then injected into each coil 2 through the nozzle 50 to heat the coil 2. The heat that has heated the coil 2 flows back into the combustion chamber 20 through the ventilation hole 61 formed in the partition wall 60, and the heat introduced into the combustion chamber 20 may be guided back to the duct 40 together with heat generated through the flame. This circulation flow of heat may be continuously performed until the coil 2 reaches a target annealing temperature. For example, the annealing temperature may be approximately 650 to 850°C.

[0065] Therefore, the coil 2 can be uniformly annealed as a whole by the high-temperature heat formed in the combustion chamber 20 without a concern of being locally over-annealed or ruptured by the flame of the combustion chamber 20.

[0066] In addition, at this time, since the coil 2 can be sufficiently heated even in a state where a temperature of the flame is lowered by a circulation structure of combustion heat circulating through the combustion chamber 20 and the annealing chamber 10, an amount of NOx generation caused by the flame can be reduced. A low NOx burner may be used as the burner 21.

[0067] After the heating process, a soaking process of maintaining the annealing temperature for a certain period of time to soak an internal structure of the coil 2 is performed, and after the soaking process, a cooling process of cooling the soaked coil may be performed.

[0068] In order to further reduce the amount of NOx generation, the plurality of burners 21 may be provided in the combustion chamber 20 so that those for use in the heating process and those for use in the soaking process have different capacities. When the burners 21 having different capacities are used separately in the heating process and the soaking process, load factor control of the burners 21 becomes easy and burner control is stabilized, so a NOx reduction rate by the burner 21 can be further increased.

[0069] Referring back to FIG. 7, in the cooling process, the operation of the burner 21 is stopped, and the exhaust flow path 61 and the external air introduction flow path 71 may be opened by the first opening / closing means 62 and the second opening / closing means 72. In this state, the blowing fan 30 continuously exhausts the high-temperature heat inside the annealing chamber 10 while continuously circulating external air introduced through the external air introduction flow path 71 along the same path as in the heating process, thereby cooling the coil 2 to a room temperature. Accordingly, the annealing treatment of the coil 2 can be completed.

[0070] FIG. 14 shows a modified example of the batch-type annealing furnace 1 according to an embodiment.

[0071] As shown in FIG. 14, the batch-type annealing furnace 1 is for increasing efficiency of the cooling process, and may further include a bypass flow path 81, flow switching valves 82 and 83, and a cooler 84 installed in the duct 40.

[0072] The bypass flow path 81 may connect to detour between two points of the main flow path 41 toward an upstream side of a point where the blowing fan 50 is installed.

[0073] The flow switching valves 82 and 83 may be provided at an intersection between the main flow path 41 and the bypass flow path 81 such that the fluid flowing in a direction of the nozzle 50 passes through any one of the bypass flow path 81 and the main flow path 41 in a section between both ends of the bypass flow path 81.

[0074] The cooler 84 may be provided to cool the bypass flow path 81. The cooler 84 is installed to be in contact with or close to the bypass flow path 81 to cool the fluid passing through the bypass flow path 81. A water-cooled cooler may be used as the cooler 84.

[0075] The cooling process of the annealing treatment may be divided into a primary cooling process and a secondary cooling process. In the case of general steel, surface oxidation is not induced at a temperature of approximately 200°C or lower for the coil 2. Considering this, in the primary cooling process, the coil 2 may be cooled to a temperature of approximately 200°C in a state where the exhaust flow path 61 and the external air introduction flow path 71 are closed so that contact between the coil 2 and oxygen can be blocked to prevent oxidation of the coil 2. For reference, the temperature at which surface oxidation is not induced may vary depending on a steel type. For example, in the case of stainless steel, the temperature at which surface oxidation is not induced may be approximately 750°C.

[0076] At this time, the flow switching valves 82 and 83 are switched so that the combustion heat guided from the combustion chamber 20 to the duct 40 passes through the bypass flow path 81, and the cooler 84 may be driven to cool the fluid passing through the bypass flow path 81. In FIG. 14, a dotted arrow indicates a flow of heat passing through the bypass flow path 81 at this time, and a solid arrow indicates a flow of heat passing through the duct 40 in the heating process. Therefore, in the primary cooling process, internal heat of the annealing furnace 1 is cooled by the cooler 84 in a process of circulating to pass through the bypass flow path 81, and the coil 2 can be cooled through the fluid cooled by the cooler 84.

[0077] This cooling action is performed at least at an initial stage of the primary cooling process, contributing to shortening an overall cooling process time.

[0078] In the secondary cooling process, since there is no concern that the coil 2 is oxidized by external air, the external air introduction flow path 71 and the exhaust flow path 61 can be opened so that external air is introduced. Therefore, the coil 2 can be rapidly cooled to room temperature by external air introduced into the annealing furnace 1 by the action of the blowing fan 30 and a cooling action of the cooler 84.

[0079] Therefore, according to the batch-type annealing furnace 1 according to an embodiment, it is possible to prevent the coil 2 from being heated in a direct fire manner by the flame while preventing an overall heat treatment process speed from decreasing.

[0080] FIG. 15 shows another modified example of the batch-type annealing furnace 1 according to an embodiment.

[0081] As shown in FIG. 15, the partition wall 60 partitioning the annealing chamber 10 and the combustion chamber 20 may be provided with a flame blocking unit 90 that blocks the flame of the combustion chamber 20 from flowing into the annealing chamber 10 through the ventilation hole 61.

[0082] The flame blocking unit 90 may be installed in each of the plurality of ventilation holes 61. The flame blocking unit 90 may include a fixing part 91 fixed to the partition wall 60, and a cover part 92 extending from the fixing part 91 to cover the ventilation hole 61 in a spaced state. The fixing part 91 is fixed to one surface of the partition wall 60 around the ventilation hole 61 facing the combustion chamber 20, and the cover part 92 is bent and extended from an end of the fixing part 91 in a direction of the combustion chamber 20 so as to cover the ventilation hole 61 in a spaced state, thereby allowing ventilation action by the ventilation hole 61 while blocking the flame from penetrating into the annealing chamber 10 through the ventilation hole 61.

[0083] Therefore, the batch-type annealing furnace 1 provided with the flame blocking unit 90 fundamentally blocks the flame formed in the combustion chamber 20 from penetrating into the annealing chamber 10 through the partition wall 60, thereby more reliably preventing the coil 2 from being damaged by the flame.

[0084] FIG. 16 shows still another modified example of the batch-type annealing furnace 1 according to an embodiment.

[0085] As shown in FIG. 16, the burner 21 installed in the combustion chamber 20 may be provided such that a jetting direction of the flame avoids a direction of the partition wall 60.

[0086] To this end, a body 21a of the burner 21 may be installed in the combustion chamber 20 such that the jetting direction of the flame avoids the partition wall direction, or an outlet 21b provided at a tip of the body 21a to jet the flame may be provided such that the jetting direction of the flame avoids the direction of the partition wall 60.

[0087] The batch-type annealing furnace 1 configured as described above can prevent the flame formed in the combustion chamber 20 from penetrating into the annealing chamber 10 through the partition wall 60 even in a state where a separate component such as the flame blocking unit 90 is not added.

Examples

Embodiment Construction

[0027]Throughout the specification, the same reference numerals refer to the same components. The present specification does not describe all elements of the embodiments, and general contents in the technical field to which the present invention belongs or overlapping contents between the embodiments are omitted. Terms such as "unit, module, member, block" used in the specification may be implemented as software or hardware, and according to embodiments, a plurality of "units, modules, members, blocks" may be implemented as a single component, or a single "unit, module, member, block" may include a plurality of components.

[0028]Throughout the specification, when a part is referred to as being "connected" to another part, this includes not only a case where it is directly connected but also a case where it is indirectly connected, and the indirect connection includes connecting through a wireless communication network.

[0029]Also, when a part is referred to as "including" a component,...

[Technical Field]

[0001] The present disclosure relates to a batch-type annealing furnace.[Background Art]

[0002] In a steel process, a coil manufactured by rolling is subjected to an annealing treatment to remove work hardening.

[0003] Among annealing furnaces for the annealing treatment, there are a continuous annealing furnace in which a coil is unwound and continuously heat-treated, and a batch-type annealing furnace in which a coil is heat-treated in a wound state.

[0004] In the case of the batch-type annealing furnace, heat treatment of the coil is possible even in a narrow space, so facility investment costs are low, and a range of materials used is wide, providing an advantage that expansion of use is easy.

[0005] Among the batch-type annealing furnaces, there is a type that directly heats the coil using a burner installed inside an annealing chamber. At this time, the burner generates a flame at a high temperature of 1800°C or higher, and the coil in the annealing chamber is heated by radiant heat from the flame.

[0006] However, in a heating method in which the coil is heated while directly exposed to the flame, there is a high concern that an outer turn portion side of the coil adjacent to the flame is overheated, resulting in over-annealing or rupture.

[0007] In addition, at this time, since the coil is heated to different temperatures for each portion depending on a distance from the flame, it may be difficult to uniformly anneal the coil as a whole.[Disclosure][Technical Problem]

[0008] An aspect of the present disclosure provides a batch-type annealing furnace capable of uniformly annealing a coil without a concern of being locally over-annealed or ruptured.

[0009] An aspect of the present disclosure provides a batch-type annealing furnace capable of reducing an amount of NOx generation according to an annealing treatment of a coil.[Technical Solution]

[0010] A batch-type annealing furnace according to the spirit of the present disclosure may include: an annealing chamber accommodating a material coil; a combustion chamber provided with a burner jetting a flame and partitioned in a state capable of ventilation with the annealing chamber; a blowing fan providing a blowing force such that a fluid in the combustion chamber is blown to the annealing chamber; a duct guiding a flow of the fluid blown from the combustion chamber to the annealing chamber; and a nozzle connected to the duct to inject the fluid guided to the annealing chamber through the duct onto the coil.

[0011] A plurality of coils may be accommodated in the annealing chamber, and the nozzle may be configured in plural numbers to individually inject the fluid onto each coil.

[0012] The nozzle may inject the fluid into a hollow portion at a center of the coil.

[0013] The nozzle may be provided as a single-hole type having one injection hole, and a center of the injection hole may coincide with a center of the hollow portion.

[0014] The nozzle may be provided as a multi-hole type having a plurality of injection holes, and the plurality of injection holes may include a first injection hole having a center coincident with a center of the hollow portion, and a plurality of second injection holes disposed around the first injection hole.

[0015] The first injection hole may have a larger diameter than the second injection holes.

[0016] The nozzle may be provided as a multi-hole type having a plurality of injection holes, and each of the plurality of injection holes may have a same diameter.

[0017] The plurality of injection holes may be located on a same plane and arranged at equal intervals.

[0018] A plurality of coils may be accommodated in the annealing chamber, a plurality of nozzles may be assigned to each coil, and the plurality of nozzles assigned to each coil may inject the fluid to different portions of each coil.

[0019] An exhaust flow path opened and closed by a first opening / closing means may be connected to the annealing chamber for discharging an internal fluid, an external air introduction flow path opened and closed by a second opening / closing means may be connected to the duct for introducing external air, the duct may include a main flow path extending from the combustion chamber and a connection flow path connecting the main flow path and the nozzle, the blowing fan may be installed on the main flow path, and the batch-type annealing furnace may further include: a bypass flow path connecting to detour between two points of the main flow path toward an upstream side of a point where the blowing fan is installed; a flow switching valve provided at an intersection between the main flow path and the bypass flow path such that the fluid flowing in a direction of the nozzle passes through any one of the bypass flow path and the main flow path in a section between both ends of the bypass flow path; and a cooler for cooling the bypass flow path.

[0020] The combustion chamber and the annealing chamber may be partitioned in a state capable of ventilation through a partition wall having a ventilation hole, and the partition wall may be provided with a flame blocking unit for blocking the flame of the combustion chamber from flowing into the annealing chamber through the ventilation hole.

[0021] The combustion chamber and the annealing chamber may be partitioned in a state capable of ventilation through a partition wall having a ventilation hole, and a body of the burner may be installed such that a jetting direction of the flame avoids a direction of the partition wall.

[0022] The combustion chamber and the annealing chamber may be partitioned in a state capable of ventilation through a partition wall having a ventilation hole, the burner may include an outlet for jetting the flame, and the outlet may be provided in the burner such that a jetting direction of the flame avoids a direction of the partition wall.

[0023] The burner may be configured in plural numbers, and at least one of the plurality of burners may have a capacity different from a remainder.[Advantageous Effects]

[0024] According to the present disclosure, it is possible to provide a batch-type annealing furnace capable of uniformly annealing a coil without a concern of being locally over-annealed or ruptured.

[0025] According to the present disclosure, it is possible to provide a batch-type annealing furnace capable of reducing an amount of NOx generation according to an annealing treatment of a coil.[Description of Drawings]

[0026] FIGS. 1 to 3 are perspective views of a batch-type annealing furnace according to an embodiment, showing a structure of the batch-type annealing furnace viewed from various directions. FIGS. 4 and 5 are perspective views of the batch-type annealing furnace according to an embodiment, showing an inside of an annealing chamber. FIG. 6 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a heating process is being performed. FIG. 7 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a cooling process is being performed. FIG. 8 is an enlarged front view of a nozzle and a coil in the batch-type annealing furnace according to an embodiment. FIG. 9 is a side view of FIG. 8, and FIG. 10 is a modified example. FIGS. 11 to 13 show other modified examples of the nozzle in the batch-type annealing furnace according to an embodiment. FIG. 14 shows a modified example of the batch-type annealing furnace according to an embodiment. FIG. 15 is a main part view showing another modified example of the batch-type annealing furnace according to an embodiment. FIG. 16 is a main part view showing still another modified example of the batch-type annealing furnace according to an embodiment. [Mode for Invention]

[0027] Throughout the specification, the same reference numerals refer to the same components. The present specification does not describe all elements of the embodiments, and general contents in the technical field to which the present invention belongs or overlapping contents between the embodiments are omitted. Terms such as "unit, module, member, block" used in the specification may be implemented as software or hardware, and according to embodiments, a plurality of "units, modules, members, blocks" may be implemented as a single component, or a single "unit, module, member, block" may include a plurality of components.

[0028] Throughout the specification, when a part is referred to as being "connected" to another part, this includes not only a case where it is directly connected but also a case where it is indirectly connected, and the indirect connection includes connecting through a wireless communication network.

[0029] Also, when a part is referred to as "including" a component, this means that it may further include other components rather than excluding other components unless specifically stated to the contrary.

[0030] Throughout the specification, when a member is located "on" another member, this includes not only a case where a member is in contact with another member but also a case where another member exists between two members.

[0031] Terms such as first, second, etc. are used to distinguish one component from another component, and the components are not limited by the aforementioned terms.

[0032] The singular expression includes the plural expression unless the context clearly dictates otherwise.

[0033] Identification codes for each step are used for convenience of description, and the identification codes do not describe the order of each step, and each step may be performed differently from the specified order unless the context clearly states a specific order.

[0034] The term "and / or" may include a combination of a plurality of related described components or any component among a plurality of related described components.

[0035] Hereinafter, the operating principle and embodiments of the present invention will be described with reference to the accompanying drawings.

[0036] For reference, FIGS. 1 to 3 are perspective views of a batch-type annealing furnace according to an embodiment, showing a structure of the batch-type annealing furnace viewed from various directions. FIGS. 4 and 5 are perspective views of the batch-type annealing furnace according to an embodiment, showing an inside of an annealing chamber. FIG. 6 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a heating process is being performed. FIG. 7 shows the batch-type annealing furnace according to an embodiment, illustrating a state in which a cooling process is being performed.

[0037] As shown in FIGS. 1 to 7, a batch-type annealing furnace 1 according to an embodiment may include an annealing chamber 10, a combustion chamber 20 partitioned in a state capable of ventilation with the annealing chamber 10, a blowing fan 30 providing a blowing force such that a fluid in the combustion chamber 20 is blown to the annealing chamber 10, a duct 40 guiding a flow of the fluid blown from the combustion chamber 20 to the annealing chamber 10, and a nozzle 50 injecting the fluid guided to the annealing chamber 10 through the duct 40 onto a coil 2.

[0038] A material coil 2 to be subjected to an annealing treatment may be accommodated in the annealing chamber 10. The batch-type annealing furnace 1 is provided with a furnace body 1a, and the annealing chamber 10 may be provided through a space on one side inside the furnace body 1a. The coil 2 may be accommodated in the annealing chamber 10 so as to be supported by a support member 3 installed on a bottom of the annealing chamber 10. In the annealing chamber 10, a plurality of coils 2 may be disposed along a longitudinal direction of the annealing chamber 10. The plurality of coils 2 may be accommodated in the annealing chamber 10 to form a multi-stage structure in a form in which a part is supported by the support member 3 and another part is stacked on an upper part between the coils 2 supported by the support member 3.

[0039] An exhaust flow path 61 for discharging an internal fluid of the annealing chamber 10 is connected to one side of the annealing chamber 10, and the exhaust flow path 61 may be opened and closed by an opening / closing means 62. The opening / closing means 62 may be a first opening / closing means.

[0040] The combustion chamber 20 may be provided with a burner 21 jetting a flame. The combustion chamber 20 may be provided through a space on the other side inside the furnace body 1a. The burner 21 is configured in plural numbers, and air and fuel as an oxidant may be supplied together to each burner 21. As an ignition device is operated, a flame may be jetted into the combustion chamber 20 through the burner 21.

[0041] Inside the furnace body 1a, a partition wall 60 having a ventilation hole 61 may be provided to partition the combustion chamber 20 and the annealing chamber 10 in a state capable of ventilation.

[0042] The duct 40 may be provided to guide the fluid of the combustion chamber 20 to the annealing chamber 10. The duct 40 may be provided to connect the combustion chamber 20 and the annealing chamber 10 outside the combustion chamber 20 and the annealing chamber 10.

[0043] The duct 40 may include a main flow path 41 extending from the combustion chamber 20 and a connection flow path 42 connecting the main flow path 41 and the nozzle 50. The main flow path 41 may be connected to the combustion chamber 20 through a bottom surface of the combustion chamber 20.

[0044] The blowing fan 30 is installed in the duct 40 and may perform a blowing action such that the fluid in the combustion chamber 20 is guided to the annealing chamber 10 along the duct 40. The blowing fan 30 may be installed on the main flow path 41 of the duct 40. The blowing fan 30 may be configured as a single or plural unit depending on a shape or branching structure of the duct 40.

[0045] An external air introduction flow path 71 for introduction of external air is connected to the duct 40, and the external air introduction flow path 71 may be opened and closed by an opening / closing means 72. The opening / closing means 72 may be a second opening / closing means.

[0046] The nozzle 50 is installed at an end of the connection flow path 42 and installed to inject the fluid into the annealing chamber 10 so that the fluid guided to the annealing chamber 10 through the connection flow path 42 is injected onto the coil 2.

[0047] The batch-type annealing furnace 1 configured as described above may directly inject high-temperature combustion heat generated in the combustion chamber 20 by the flame jetted from the burner 21 onto the coil 2 through the nozzle 50.

[0048] Therefore, according to the batch-type annealing furnace 1 according to the present embodiment, by preventing the coil 2 from being exposed to the flame of the burner 21 during a process of performing the heating process of the annealing treatment, it is possible to prevent the coil 2 from being locally over-annealed or ruptured by the flame.

[0049] In addition, at this time, by allowing the high-temperature combustion heat formed in the combustion chamber 20 through the flame to be directly injected onto the coil 2 through the duct 40 and the nozzle 50, the coil 2 may be uniformly annealed as a whole using a convection phenomenon of the combustion heat.

[0050] The nozzle 50 is configured in plural numbers to individually inject the fluid onto each coil 2 disposed in the annealing chamber 10, thereby increasing heating efficiency of the coil 2 by the combustion heat.

[0051] For example, the nozzle 50 may be configured with a number corresponding to the number of coils 2 so that the combustion heat is individually injected onto each coil 2.

[0052] Also, as shown in the drawing, a plurality of nozzles 50 may be assigned to each coil 2. The plurality of nozzles 50 assigned to each coil 2 inject the fluid to different portions of each coil 2, thereby allowing various portions of the coil 2 to be heated more evenly by the combustion heat injected through the nozzles 50. For example, some nozzles 50 among the plurality of nozzles 50 may be disposed in the annealing chamber 10 at a position corresponding to one end of the coil 2 to inject the fluid toward the one end of the coil 2, and remaining nozzles 50 may be disposed in the annealing chamber 10 at a position corresponding to the other end of the coil 2 to inject the fluid toward the other end of the coil 2.

[0053] The connection flow path 42 of the duct 40 may include a plurality of first connection flow paths 42a branching from the main flow path, and a second connection flow path 42b branching from each of the first connection flow paths 42a and connected to the nozzle 50. For example, the first connection flow path 42a may be configured as a pair.

[0054] Also, each nozzle 50 may be provided to inject the fluid into a hollow portion 2a at the center of the corresponding coil 2. The fluid injected into the hollow portion 2a of the coil 2 by the nozzle 50 may secure straight flowability. This may contribute to ensuring an overall circulation flow of the combustion heat supplied from the combustion chamber 20 to the annealing chamber 10 through the duct 40 and flowing back into the combustion chamber 20.

[0055] As shown in FIGS. 8 and 9, the nozzle 50 may be provided as a single-hole type having one injection hole 51, wherein a center of the injection hole 51 coincides with a center of the hollow portion 2a of the coil 2. Such a nozzle 50 is provided with one injection hole 51, so the structure is simplified, while the fluid can be accurately injected in a direction of the center of the hollow portion 2a by the injection hole 51. The fluid injected in the direction of the center of the hollow portion 2a gradually expands and can contact the hollow portion 2a of the coil 2 and a circumference thereof evenly as a whole.

[0056] The injection hole 51 may be provided such that a diameter gradually decreases in a jetting direction of the fluid so that straightness of the injected fluid can be further increased. Also, as shown in FIG. 10, the injection hole 51 may be provided such that a diameter gradually expands in the jetting direction of the fluid so that expandability of the injected fluid can be further increased.

[0057] FIGS. 11 to 13 show modified examples of the nozzle 50.

[0058] As shown in FIG. 11, a nozzle 50a may be provided as a multi-hole type having a plurality of injection holes 51a and 52a. In such a nozzle 50a, the injection holes 51a and 52a may include a central first injection hole 51a having a center coincident with the center of the hollow portion 2a of the coil 2, and a plurality of second injection holes 52a disposed around the first injection hole 51a. The central first injection hole 51a is responsible for a function of improving straightness of fluid injection, and the second injection holes 52a disposed around the first injection hole 51a may be responsible for a function of increasing expandability of fluid injection.

[0059] Considering that the first injection hole 51a is configured as one, the first injection hole 51a may be provided to have a relatively larger diameter than the second injection holes 52a provided in plural numbers so that the straightness and expandability of the injected fluid can be evenly increased.

[0060] As shown in FIGS. 12 and 13, nozzles 50b and 50c are provided as a multi-hole type having a plurality of injection holes 51b and 51c, and the plurality of injection holes 51b and 51c may be provided to have the same diameter, respectively. In addition, in the nozzle 50c, the plurality of injection holes 51c disposed on the same plane may be arranged to be at equal intervals from each other. These nozzles 50b and 50c facilitate an increase in an injection area for injecting the fluid, so even when disposed to inject the fluid between the coils 2, the fluid can be smoothly supplied to each coil 2.

[0061] An annealing treatment process of the coil 2 using the batch-type annealing furnace 1 according to an embodiment will be described as follows.

[0062] The coil 2 may be annealed by sequentially undergoing a heating process, a soaking process, and a cooling process.

[0063] Referring back to FIG. 6, in the heating process, the burner 21 is operated to generate a flame in the combustion chamber 20, and the blowing fan 30 may be operated in a state where the exhaust flow path 61 and the external air introduction flow path 71 are closed using the first opening / closing means 62 and the second opening / closing means 72.

[0064] Accordingly, the combustion heat formed in the combustion chamber 20 through the flame is guided to the annealing chamber 10 through the duct 40 and then injected into each coil 2 through the nozzle 50 to heat the coil 2. The heat that has heated the coil 2 flows back into the combustion chamber 20 through the ventilation hole 61 formed in the partition wall 60, and the heat introduced into the combustion chamber 20 may be guided back to the duct 40 together with heat generated through the flame. This circulation flow of heat may be continuously performed until the coil 2 reaches a target annealing temperature. For example, the annealing temperature may be approximately 650 to 850°C.

[0065] Therefore, the coil 2 can be uniformly annealed as a whole by the high-temperature heat formed in the combustion chamber 20 without a concern of being locally over-annealed or ruptured by the flame of the combustion chamber 20.

[0066] In addition, at this time, since the coil 2 can be sufficiently heated even in a state where a temperature of the flame is lowered by a circulation structure of combustion heat circulating through the combustion chamber 20 and the annealing chamber 10, an amount of NOx generation caused by the flame can be reduced. A low NOx burner may be used as the burner 21.

[0067] After the heating process, a soaking process of maintaining the annealing temperature for a certain period of time to soak an internal structure of the coil 2 is performed, and after the soaking process, a cooling process of cooling the soaked coil may be performed.

[0068] In order to further reduce the amount of NOx generation, the plurality of burners 21 may be provided in the combustion chamber 20 so that those for use in the heating process and those for use in the soaking process have different capacities. When the burners 21 having different capacities are used separately in the heating process and the soaking process, load factor control of the burners 21 becomes easy and burner control is stabilized, so a NOx reduction rate by the burner 21 can be further increased.

[0069] Referring back to FIG. 7, in the cooling process, the operation of the burner 21 is stopped, and the exhaust flow path 61 and the external air introduction flow path 71 may be opened by the first opening / closing means 62 and the second opening / closing means 72. In this state, the blowing fan 30 continuously exhausts the high-temperature heat inside the annealing chamber 10 while continuously circulating external air introduced through the external air introduction flow path 71 along the same path as in the heating process, thereby cooling the coil 2 to a room temperature. Accordingly, the annealing treatment of the coil 2 can be completed.

[0070] FIG. 14 shows a modified example of the batch-type annealing furnace 1 according to an embodiment.

[0071] As shown in FIG. 14, the batch-type annealing furnace 1 is for increasing efficiency of the cooling process, and may further include a bypass flow path 81, flow switching valves 82 and 83, and a cooler 84 installed in the duct 40.

[0072] The bypass flow path 81 may connect to detour between two points of the main flow path 41 toward an upstream side of a point where the blowing fan 50 is installed.

[0073] The flow switching valves 82 and 83 may be provided at an intersection between the main flow path 41 and the bypass flow path 81 such that the fluid flowing in a direction of the nozzle 50 passes through any one of the bypass flow path 81 and the main flow path 41 in a section between both ends of the bypass flow path 81.

[0074] The cooler 84 may be provided to cool the bypass flow path 81. The cooler 84 is installed to be in contact with or close to the bypass flow path 81 to cool the fluid passing through the bypass flow path 81. A water-cooled cooler may be used as the cooler 84.

[0075] The cooling process of the annealing treatment may be divided into a primary cooling process and a secondary cooling process. In the case of general steel, surface oxidation is not induced at a temperature of approximately 200°C or lower for the coil 2. Considering this, in the primary cooling process, the coil 2 may be cooled to a temperature of approximately 200°C in a state where the exhaust flow path 61 and the external air introduction flow path 71 are closed so that contact between the coil 2 and oxygen can be blocked to prevent oxidation of the coil 2. For reference, the temperature at which surface oxidation is not induced may vary depending on a steel type. For example, in the case of stainless steel, the temperature at which surface oxidation is not induced may be approximately 750°C.

[0076] At this time, the flow switching valves 82 and 83 are switched so that the combustion heat guided from the combustion chamber 20 to the duct 40 passes through the bypass flow path 81, and the cooler 84 may be driven to cool the fluid passing through the bypass flow path 81. In FIG. 14, a dotted arrow indicates a flow of heat passing through the bypass flow path 81 at this time, and a solid arrow indicates a flow of heat passing through the duct 40 in the heating process. Therefore, in the primary cooling process, internal heat of the annealing furnace 1 is cooled by the cooler 84 in a process of circulating to pass through the bypass flow path 81, and the coil 2 can be cooled through the fluid cooled by the cooler 84.

[0077] This cooling action is performed at least at an initial stage of the primary cooling process, contributing to shortening an overall cooling process time.

[0078] In the secondary cooling process, since there is no concern that the coil 2 is oxidized by external air, the external air introduction flow path 71 and the exhaust flow path 61 can be opened so that external air is introduced. Therefore, the coil 2 can be rapidly cooled to room temperature by external air introduced into the annealing furnace 1 by the action of the blowing fan 30 and a cooling action of the cooler 84.

[0079] Therefore, according to the batch-type annealing furnace 1 according to an embodiment, it is possible to prevent the coil 2 from being heated in a direct fire manner by the flame while preventing an overall heat treatment process speed from decreasing.

[0080] FIG. 15 shows another modified example of the batch-type annealing furnace 1 according to an embodiment.

[0081] As shown in FIG. 15, the partition wall 60 partitioning the annealing chamber 10 and the combustion chamber 20 may be provided with a flame blocking unit 90 that blocks the flame of the combustion chamber 20 from flowing into the annealing chamber 10 through the ventilation hole 61.

[0082] The flame blocking unit 90 may be installed in each of the plurality of ventilation holes 61. The flame blocking unit 90 may include a fixing part 91 fixed to the partition wall 60, and a cover part 92 extending from the fixing part 91 to cover the ventilation hole 61 in a spaced state. The fixing part 91 is fixed to one surface of the partition wall 60 around the ventilation hole 61 facing the combustion chamber 20, and the cover part 92 is bent and extended from an end of the fixing part 91 in a direction of the combustion chamber 20 so as to cover the ventilation hole 61 in a spaced state, thereby allowing ventilation action by the ventilation hole 61 while blocking the flame from penetrating into the annealing chamber 10 through the ventilation hole 61.

[0083] Therefore, the batch-type annealing furnace 1 provided with the flame blocking unit 90 fundamentally blocks the flame formed in the combustion chamber 20 from penetrating into the annealing chamber 10 through the partition wall 60, thereby more reliably preventing the coil 2 from being damaged by the flame.

[0084] FIG. 16 shows still another modified example of the batch-type annealing furnace 1 according to an embodiment.

[0085] As shown in FIG. 16, the burner 21 installed in the combustion chamber 20 may be provided such that a jetting direction of the flame avoids a direction of the partition wall 60.

[0086] To this end, a body 21a of the burner 21 may be installed in the combustion chamber 20 such that the jetting direction of the flame avoids the partition wall direction, or an outlet 21b provided at a tip of the body 21a to jet the flame may be provided such that the jetting direction of the flame avoids the direction of the partition wall 60.

[0087] The batch-type annealing furnace 1 configured as described above can prevent the flame formed in the combustion chamber 20 from penetrating into the annealing chamber 10 through the partition wall 60 even in a state where a separate component such as the flame blocking unit 90 is not added.

Examples

Embodiment Construction

[0027]Throughout the specification, the same reference numerals refer to the same components. The present specification does not describe all elements of the embodiments, and general contents in the technical field to which the present invention belongs or overlapping contents between the embodiments are omitted. Terms such as "unit, module, member, block" used in the specification may be implemented as software or hardware, and according to embodiments, a plurality of "units, modules, members, blocks" may be implemented as a single component, or a single "unit, module, member, block" may include a plurality of components.

[0028]Throughout the specification, when a part is referred to as being "connected" to another part, this includes not only a case where it is directly connected but also a case where it is indirectly connected, and the indirect connection includes connecting through a wireless communication network.

[0029]Also, when a part is referred to as "including" a component,...

Claims

1. A batch-type annealing furnace comprising: an annealing chamber accommodating a material coil; a combustion chamber provided with a burner for jetting a flame, the combustion chamber being partitioned in a state capable of ventilation with the annealing chamber; a blowing fan providing a blowing force such that a fluid in the combustion chamber is blown to the annealing chamber; a duct guiding a flow of the fluid blown from the combustion chamber to the annealing chamber; and a nozzle connected to the duct to inject the fluid guided to the annealing chamber through the duct onto the coil.

2. The batch-type annealing furnace of claim 1, wherein a plurality of coils are accommodated in the annealing chamber, and the nozzle is configured in plural numbers to individually inject the fluid onto each coil.

3. The batch-type annealing furnace of claim 1, wherein the nozzle injects the fluid into a hollow portion at a center of the coil.

4. The batch-type annealing furnace of claim 3, wherein the nozzle is provided as a single-hole type having one injection hole, and a center of the injection hole coincides with a center of the hollow portion.

5. The batch-type annealing furnace of claim 3, wherein the nozzle is provided as a multi-hole type having a plurality of injection holes, and the plurality of injection holes include a first injection hole having a center coincident with a center of the hollow portion, and a plurality of second injection holes disposed around the first injection hole.

6. The batch-type annealing furnace of claim 5, wherein the first injection hole has a larger diameter than the second injection holes.

7. The batch-type annealing furnace of claim 1, wherein the nozzle is provided as a multi-hole type having a plurality of injection holes, and each of the plurality of injection holes has a same diameter.

8. The batch-type annealing furnace of claim 7, wherein the plurality of injection holes are located on a same plane and arranged at equal intervals.

9. The batch-type annealing furnace of claim 1, wherein a plurality of coils are accommodated in the annealing chamber, a plurality of nozzles are assigned to each coil, and the plurality of nozzles assigned to each coil inject the fluid to different portions of each coil.

10. The batch-type annealing furnace of claim 1, wherein an exhaust flow path opened and closed by a first opening / closing means is connected to the annealing chamber for discharging an internal fluid, an external air introduction flow path opened and closed by a second opening / closing means is connected to the duct for introducing external air, the duct includes a main flow path extending from the combustion chamber and a connection flow path connecting the main flow path and the nozzle, the blowing fan is installed on the main flow path, and the batch-type annealing furnace further comprises: a bypass flow path connecting to detour between two points of the main flow path toward an upstream side of a point where the blowing fan is installed; a flow switching valve provided at an intersection between the main flow path and the bypass flow path such that the fluid flowing in a direction of the nozzle passes through any one of the bypass flow path and the main flow path in a section between both ends of the bypass flow path; and a cooler for cooling the bypass flow path.

11. The batch-type annealing furnace of claim 1, wherein the combustion chamber and the annealing chamber are partitioned in a state capable of ventilation through a partition wall having a ventilation hole, and the partition wall is provided with a flame blocking unit for blocking the flame of the combustion chamber from flowing into the annealing chamber through the ventilation hole.

12. The batch-type annealing furnace of claim 1, wherein the combustion chamber and the annealing chamber are partitioned in a state capable of ventilation through a partition wall having a ventilation hole, and a body of the burner is installed such that a jetting direction of the flame avoids a direction of the partition wall.

13. The batch-type annealing furnace of claim 1, wherein the combustion chamber and the annealing chamber are partitioned in a state capable of ventilation through a partition wall having a ventilation hole, the burner includes an outlet for jetting the flame, and the outlet is provided in the burner such that a jetting direction of the flame avoids a direction of the partition wall.

14. The batch-type annealing furnace of claim 1, wherein the burner is configured in plural numbers, and at least one of the plurality of burners has a capacity different from a remainder.

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