JP2008151384A - Supporting structure of nozzle unit of furnace bottom, nozzle unit replacement method, and nozzle unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a supporting structure of a nozzle unit of a furnace bottom, a nozzle unit replacement method and the nozzle unit, capable of easily performing demolition work and easily reconstructing a nozzle portion in reconstructing the nozzle portion disposed on the furnace bottom. <P>SOLUTION: In this supporting structure of the nozzle unit, the nozzle unit in which a pore tube 80 is received and disposed in a receiving bracket 71 having a flange 71a of a diameter smaller than a supporting plate 33, is disposed on a cinder notch 32a in a state of being retained to the supporting plate 33 by the flange 71a. A plurality of throat bricks 81 and the like having a size smaller than an outer diameter of the supporting plate 33 and larger than an outer diameter of the flange 71a are stacked on the pore tube 80. A through hole and the like of the throat brick 81 and the like and a nozzle hole 80a of the pore tube 80 are communicated with each other, and fire-proof bricks 40A and the like joined to the throat bricks 81 and the like are stacked on the supporting plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a support structure for a nozzle unit on a furnace bottom, a method for replacing a nozzle unit, and a nozzle unit, and more particularly, a support structure for a nozzle unit for discharging a melt in the furnace from the furnace bottom, a method for replacing the nozzle unit, and a nozzle. It is about the unit.

  2. Description of the Related Art Conventionally, for example, as an apparatus that melts radioactive waste from a nuclear power plant facility at an extremely high temperature, an apparatus that can process the radioactive waste by generating a high temperature with a plasma torch has been proposed. . In such an apparatus, for example, a centrifugal furnace is disposed in the lower part of the plasma chamber, and the waste thrown into the centrifugal furnace is melted together with the waste container by the plasma and pressed against the wall by the centrifugal force by the rotation of the centrifugal furnace. Therefore, the center of the furnace is not positioned at the center of the furnace bottom (that is, the bottom of the centrifugal furnace). And when all of the thrown-in waste is melted together with the waste container by plasma, the rotation of the centrifugal furnace is decelerated, and the melt is passed through the nozzle hole of the nozzle part provided in the center part of the furnace bottom, The gas is discharged to the outside through a discharge port provided below the plasma chamber.

  A conventional configuration of this nozzle portion will be described with reference to FIGS. FIG. 6 shows a cross-sectional view of the centrifugal furnace 100. The centrifugal furnace 100 includes a bottomed cylindrical iron skin 102 and a lining layer 140 provided on the inner peripheral surface of the iron skin 102 and the furnace bottom. The lining layer 140 is formed by laminating a plurality of refractory bricks, but for convenience of explanation, it is drawn as a single layer in FIG.

  Further, a nozzle portion 150 protruding downward is provided at the center of the furnace bottom. The receiving metal fitting 104 constituting a part of the nozzle portion 150 is formed in a bottomed cylindrical shape and is latched via a flange 105 to a tap hole 103 provided at the center of the iron shell 102 on the furnace bottom. ing. A hole 107 having a circular cross section is formed in the bottom portion 106 of the metal fitting 104.

  On the bottom portion 106, a ring-shaped pore tube 110 made of refractory bricks is placed. The outer diameter of the pore tube 110 is smaller than the inner diameter of the receiving metal fitting 104 so as to have a gap. The lower part of the pore tube 110 protrudes downward from the hole 107. A nozzle hole 113 is formed in the center of the pore tube 110. Further, ring-shaped throat bricks 118 and 119 having the same diameter made of refractory bricks are placed on the upper surface of the pore tube 110 in layers. The central holes of the throat bricks 118 and 119 are arranged so as to coincide with each other and communicate with the nozzle hole 113. The outer diameters of the throat bricks 118 and 119 are the same as the outer diameter of the pore tube 110.

  As shown in FIG. 7, the refractory brick 140 </ b> A as the lowermost layer of the lining layer 140 is placed on the flange 105. A plurality of fire bricks (not shown) are placed on the fire brick 140A. Further, as shown in FIG. 6, the entire outer periphery of the throat bricks 118 and 119 is joined to the refractory bricks constituting the lining layer 140. Castable 120 is filled between the refractory bricks 140 </ b> A located at the lower outer periphery and lower layer of the throat brick 118 and between the pore tube 110 and the inner peripheral surface of the receiving metal fitting 104. In addition, the outer periphery of the lower portion of the pore tube 110 protruding from the bottom portion 106 and the lower surface of the bottom portion 106 are covered with a castable 121.

  Thus, the nozzle part 150 is comprised by the metal fitting 104, the pore tube 110, the castable 120, 121 grade | etc.,.

  By the way, in such an apparatus, it is necessary to reconstruct the nozzle part 150 in order to melt | dissolve the refractory brick which comprises the nozzle part provided in the center part of the bottom of a centrifugal furnace. However, conventionally, when the nozzle portion 150 is reconstructed, as shown in FIGS. 6 and 7, a lining layer 140 including a refractory brick 140 </ b> A and the like is provided on the flange 105 of the metal fitting 104. Therefore, not only dismantling and removal of the throat bricks 119 and 118 but also the lining layer 140 including the refractory brick 140A in the dismantling range shown in FIG. The member had to be removed. Conventionally, after the old nozzle portion 150 is removed, a new receiving metal fitting 104 is latched to the outlet 103 via the flange 105, and then the pore tube 110 is assembled or the castable 120 is filled. It was necessary to carry out work such as putting in.

  Usually, in order to reconstruct the conventional nozzle part, the lining layer 140 including the refractory brick 140A and the like, the throat bricks 119 and 118 and the like are disassembled on the first day, and the receiving bracket 104 is taken out. Disassemble the pore tube 110 and the like. On the second day, for the construction of the castable 121 on the lower surface of the metal fitting 104, the castable 121 is constructed in a predetermined shape with the metal fitting 104 fixed to a frame (not shown). On the third day, the receiving metal fitting 104 is set in the furnace, a new pore tube 110 is set in the receiving metal fitting 104, the outer periphery of those members is casted, and a part of the castable 120 is formed. After the fourth day, the lining layer 140 including the refractory brick 140A as the furnace bottom brick is set, and the remaining portion of the castable 120 is formed. Thus, conventionally, there has been a problem that takes time.

  The present invention, when reconstructing the nozzle portion provided in the furnace bottom, it is possible to easily perform the dismantling work, and the nozzle unit support structure of the furnace bottom capable of easily reconstructing the nozzle portion, a method for replacing the nozzle unit, And providing a nozzle unit.

  In order to achieve the above object, the invention according to claim 1 is a cylindrical shape in which a ring-shaped support plate is disposed on the periphery of the tap hole provided in the furnace bottom and has a flange having a smaller diameter than the support plate. A nozzle unit configured by accommodating a pore tube in a receiving metal fitting is hooked to the support plate by the flange and is arranged at the outlet, and the outside of the support plate is placed on the pore tube. A nozzle unit characterized in that a plurality of throat bricks having a diameter smaller than the diameter and exceeding the outer diameter of the flange are laminated, and a throat portion of the throat brick and a through hole of the pore tube are communicated with each other. The support structure is the gist.

The invention of claim 2 is characterized in that, in claim 1, outer diameters of the plurality of throat bricks are formed to have the same diameter.
The invention of claim 3 forms a moving space by removing the throat brick arranged above the nozzle unit with respect to the furnace bottom having the nozzle unit support structure according to claim 1 or claim 2. A step of releasing the latching of the nozzle unit with the support plate and removing the nozzle unit through the moving space, and a pore tube pre-stored in a cylindrical metal fitting having a smaller diameter flange than the support plate A new nozzle unit configured to be hung on the support plate through the moving space, and having a diameter smaller than the outer diameter of the support plate on the new nozzle unit and exceeding the outer diameter of the flange And a step of laminating a plurality of throat bricks having a size in the moving space. It is an gist.

  The gist of the invention of claim 4 is a nozzle unit, characterized in that a latching flange is formed in a cylindrical metal fitting, and a pore tube having a nozzle hole is housed and fixed in the metal fitting. Is.

  According to a fifth aspect of the present invention, in the fourth aspect, the flange includes a jig mounting portion for detachably mounting the jig.

  According to the first aspect of the present invention, since the space for removing and moving the nozzle unit is formed simply by dismantling the laminated throat bricks, the nozzle unit can be easily removed. Therefore, when reconstructing the nozzle part provided in the furnace bottom, it is possible to easily perform the dismantling operation and to easily reconstruct the nozzle part.

  According to the invention of claim 2, since the outer diameters of the plurality of throat bricks are formed to be the same diameter, when disassembling the throat brick, the entire space area in which the nozzle unit can be easily detached and moved is removed. It can be a circle with the same cross-sectional diameter. As a result, since there is nothing to interfere when removing the nozzle unit or inserting a new nozzle unit, the operation of removing the nozzle unit or inserting a new nozzle unit can be performed smoothly.

  According to the third aspect of the present invention, the space for removing and moving the nozzle unit is formed simply by disassembling the laminated throat bricks, so that the nozzle unit can be easily removed. Therefore, when reconstructing the nozzle part provided in the furnace bottom, it is possible to easily perform the dismantling operation and to easily reconstruct the nozzle part.

  According to the invention of claim 4, since it can be used as the nozzle unit of claim 1 or claim 3 and the pore tube is housed and fixed in advance in the receiving metal fitting, the nozzle part can be quickly moved with respect to the furnace bottom. Can be built.

  According to the invention of claim 5, by providing a jig mounting portion for detachably mounting the jig, using the jig, the nozzle unit can be easily hooked on the support plate, The latch can be released. As a result, the nozzle portion can be easily reconstructed.

Hereinafter, an embodiment in which the present invention is embodied in a plasma furnace that melts and processes radioactive waste with plasma will be described with reference to FIGS.
As shown in FIG. 1, the plasma furnace 10 includes a plasma chamber 20 and a centrifugal furnace 30 disposed below the plasma chamber 20. A plasma torch (not shown) is mounted on the top of the plasma chamber 20. Further, an inlet (not shown) is also received at the top of the plasma chamber 20, and a waste container such as a drum can in which waste is stored can be introduced into the chamber through the inlet. A refractory material 25 made of refractory bricks is arranged in a layered structure on the inner peripheral surface and inner top surface of the plasma chamber 20. In the drawing, for convenience of explanation, the refractory material 25 is drawn in a single layer.

  The centrifugal furnace 30 disposed in the lower part of the plasma chamber 20 is formed in a bottomed cylindrical shape and is rotatably supported via a support device (not shown). The centrifugal furnace 30 can be rotated by a rotating device (not shown).

  The centrifugal furnace 30 includes a bottomed cylindrical iron skin 32 and a lining layer 40 provided on the inner peripheral surface of the iron skin 32 and the furnace bottom. The lining layer 40 is configured by laminating a plurality of refractory bricks, but is illustrated as a single layer in FIG. 1 for convenience of explanation. Further, a nozzle portion 50 protruding downward is formed at the center of the bottom of the centrifugal furnace 30.

  The centrifugal furnace 30 is rotated when the waste thrown into the centrifugal furnace 30 is melted together with the waste container by plasma. Due to the rotation of the centrifugal furnace 30, the melt is pressed against the wall by centrifugal force so as not to be positioned at the center of the furnace bottom. Then, when all of the thrown-in waste is melted together with the waste container by the plasma, the rotation of the centrifugal furnace 30 is decelerated, and the melt is discharged through the nozzle portion 50 and disposed below the plasma chamber 20. It is discharged to the outside through the outlet 70.

Next, the nozzle unit 50 will be described in detail. In this embodiment, the nozzle part 50 is comprised by the nozzle unit.
At the center of the furnace bottom of the iron shell 32 where the nozzle part 50 is provided, a tap hole 32a having a circular cross section is formed, and a support plate 33 having a circular ring shape is fitted to the tap hole 32a. Yes. In the present embodiment, the support plate 33 is formed in a lateral L shape in cross section, and a downwardly extending protrusion 33a is fitted in the tap hole 32a (see FIG. 3). A receiving metal 71 constituting a part of the nozzle portion 50 (that is, the nozzle unit) is formed in a bottomed cylindrical shape as shown in FIGS. 4 and 5, and is connected to the support plate 33 via a flange 71a. It is hung up. A hole 71 d having a circular cross section is formed in the bottom 71 b of the receiving metal 71. The flange 71a is formed with a plurality of bolt holes 71g as jig mounting portions spaced apart from each other by a predetermined distance.

As shown in FIG. 3, a ring-shaped pore tube 75 made of refractory bricks is placed on the bottom 71 b of the receiving metal 71. The outer diameter of the pore tube 75 is smaller than the inner diameter of the metal fitting 71 so as to have a gap. On the pore tube 75,
A pore tube 80 made of refractory brick is placed. The pore tube 80 has the same outer diameter as that of the pore tube 75 above the central portion in the vertical direction. A portion below the central portion in the vertical direction of the pore tube 80 protrudes downward through a through hole 76 provided in the center of the pore tube 75.

  The lower portion of the pore tube 80 is formed in a cylindrical shape as shown in FIG. 3 and has a tapered surface so that the outer periphery thereof becomes thinner as it goes downward. When the lower portion of the pore tube 80 is penetrated into the pore tube 75, the pore tube 80 is prevented from being detached from the pore tube 75 by its tapered surface. A central hole formed along the axis of the pore tube 80 becomes a nozzle hole 80a. And the lower end of the pore tube 80 protrudes below from the bottom part 71b of the receiving metal 71 as shown in FIG. Further, as shown in FIG. 3, the upper surface of the pore tube 80 protrudes slightly above the side wall 71e. As shown in FIG. 3, a castable 83 is filled in the gap formed between the outer periphery of the pore tube 80 and the side wall 71e. When the nozzle unit is shipped from the factory, the upper surface of the castable 83 is flush with the upper surface of the flange 71a as shown in FIG.

  Further, as shown in FIG. 3, an iron skin 85 is fixed to the lower end of the side wall 71e in an annular shape by welding. The diameter of the iron skin 85 is shortened toward the bottom. A plurality of anchors 86 made of a V-shaped iron piece are fixed to the bottom surface of the bottom 71b by welding. The space surrounded by the cylindrical ceramic sheet 88 that is spaced apart from the bottom surface of the bottom 71 b of the metal fitting 71, the iron skin 85, and the outer peripheral surface of the pore tube 80 is filled with castable 89.

Thus, the nozzle unit which is the nozzle unit 50 is constituted by the receiving metal 71, the pore tubes 75 and 80, the castables 83 and 89, the iron skin 85 and the like.
Further, as shown in FIG. 2, cylindrical throat bricks 81 and 82 made of refractory bricks are laminated on the pore tube 80. The outer diameters of the throat bricks 81 and 82 are smaller than the outer diameter of the support plate 33 and have a length equal to or longer than the outer diameter of the flange 71 a of the receiving metal 71. The central through holes 81 a and 82 a serving as the throat portions of the throat bricks 81 and 82 are communicated with the nozzle hole 80 a of the pore tube 80.

Further, refractory bricks constituting the lining layer 40 are joined to the outer periphery of the pore tube 80 and the throat bricks 81 and 82 of the nozzle unit 50 (nozzle unit).
The lowermost refractory brick 40A in the lining layer 40 is placed on the support plate 33 as shown in FIG. A space surrounded by the refractory bricks 40A and the refractory bricks located above the refractory bricks 40A is a storage space for the throat bricks 81 and 82 and a part of the nozzle portions 50, and the nozzle portion 50 ( That is, it becomes a moving space when the nozzle unit is replaced. The upper surface of the throat brick 82 and the upper surface of the lining layer 40 are flush with each other. 3, the lower surface of the throat brick 81 that is not joined to the pore tube 80, the castable 83 facing the lower surface, the flange 71a and the support plate 33, the outer peripheral surface of the pore tube 80, and the refractory brick 40A are surrounded. The space is filled with a castable 84 as the nozzle unit.

(Operation of the embodiment)
Now, in the centrifugal furnace 30 configured as described above, the replacement work of the nozzle unit 50 (nozzle unit) performed for melting the refractory bricks constituting the nozzle unit 50 will be described.

  First, as shown in FIG. 2, the worker disassembles the throat bricks 82 and 81 and removes them from the furnace bottom. By removing the throat bricks 82 and 81, movement exchange of the nozzle unit 50 (nozzle unit) is formed. Next, the castable 84 is removed, the flange 71a is exposed, and a plurality of bolts B are screwed into the respective bolt holes 71g to the flange 71a of the receiving metal 71 as shown in FIG. A tool G is attached (only one jig G is shown in FIG. 3). Thereafter, the worker pulls up the nozzle unit 50 (nozzle unit) through the jig G through the moving space. As a result, the old nozzle portion 50 (nozzle unit) is removed from the tap port 32a after the latching of the support plate 33 is released.

  Thereafter, the worker puts a new nozzle portion 50 (nozzle unit) to which the jig G is attached in the same manner as described above into the outlet 32a through the moving space using the jig G. Then, the flange 71 a of the new nozzle unit 50 (nozzle unit) is hooked on the support plate 33.

  At this time, a storage space surrounded by the castable 83 of the nozzle portion 50, the flange 71a and the support plate 33, the outer peripheral surface of the pore tube 80, and the refractory brick 40A is formed. The castable 84 is filled into the storage space up to a line indicated by a two-dot chain line in FIG. Thereafter, the throat bricks 81 and 82 are stacked on the pore tube 80.

  According to the above method, the dismantling of the throat bricks 81 and 82, the setting of the nozzle unit 50 (nozzle unit), and the filling operation of the castable 84 are performed on the first day. The operation of laminating the next throat bricks 81 and 82 on the pore tube 80 is performed on the second day.

Now, the effect of this embodiment will be described.
(1) In the support structure of the nozzle part 50 (nozzle unit) of this embodiment, the ring-shaped support plate 33 is arrange | positioned at the periphery of the tap hole 32a provided in the furnace bottom. A nozzle portion 50 (nozzle unit) configured by accommodating and arranging a pore tube 80 having a nozzle hole 77 in a cylindrical receiving metal 71 having a flange 71 a having a smaller diameter than the support plate 33 is provided with respect to the support plate 33. It is hooked by a flange 71a and is arranged at the tap opening 32a. A plurality of throat bricks 81 and 82 having a diameter smaller than the outer diameter of the support plate 33 and exceeding the outer diameter of the flange 71 a are stacked on the pore tube 80. Further, the through holes 81a and 82a (throat portion) of the throat bricks 81 and 82 and the nozzle hole 80a of the pore tube 80 communicate with each other, and the refractory brick 40A and the like joined to the throat bricks 81 and 82 are laminated on the support plate 33. Has been.

  As a result, in this embodiment, a space (moving space) in which the nozzle unit 50 (nozzle unit) can be removed and moved by simply disassembling the stacked throat bricks 81 and 82 is formed. Unit) can be removed easily. Therefore, when the nozzle part 50 (nozzle unit) provided in the furnace bottom is reconstructed, the disassembly work can be easily performed, and the nozzle part 50 (nozzle unit) can be easily reconstructed.

  For example, the dismantling range of the bottom of the furnace is a wide range including the refractory bricks 140A and the like and the throat bricks 118 and 119 in FIG. 6 showing the prior art, whereas in the present embodiment, the range including the throat bricks 81 and 82 is narrow. Dismantling within a range is sufficient, and the dismantling time can be shortened.

  Furthermore, the fact that the dismantling range is narrow does not dismantle the refractory brick 40A or the refractory brick above the refractory brick 40A, so after setting the nozzle portion 50, a new refractory brick located above the refractory brick 40A or its There is no need to prepare the refractory brick 40A located below, and the material cost can be reduced. In the prior art, the refractory brick 140A and the refractory bricks located in the vicinity of the refractory brick 140A are dismantled to require a new refractory brick, and the material cost is increased.

  In addition, conventionally, it is necessary to construct the castable 121 provided on the bottom lower surface side of the catch 104 shown in FIG. 7, but in this embodiment, since the nozzle unit is pre-made at the factory, There is no need to do it. Conventionally, it took three days from dismantling the furnace bottom to setting the nozzle metal fitting, but this embodiment has the advantage of one day.

  (2) In this embodiment, the outer diameters of the plurality of throat bricks 81 and 82 are formed to have the same diameter. As a result, when disassembling the throat bricks 81 and 82, the entire space area in which the nozzle portion 50 (nozzle unit) can be easily removed and moved can be made circular with the same cross-section. As a result, since there is nothing to interfere when removing the nozzle unit 50 (nozzle unit) or inserting a new nozzle unit 50 (nozzle unit), the removal work of the nozzle unit 50 (nozzle unit) or the new nozzle unit 50 is performed. The operation of inserting the (nozzle unit) can be performed smoothly.

(3) In the method for replacing the nozzle unit 50 according to the present embodiment, the nozzle unit 50 (nozzle unit) with respect to the furnace bottom having the support structure for the nozzle unit 50 (nozzle unit) described in (1) and (2) above. The throat brick arranged above the slab was removed to form a moving space. Subsequently, the hooking of the nozzle part 50 (nozzle unit) with the support plate 33 is released and removed through the moving space.
Next, a new nozzle portion 50 (nozzle unit) configured by accommodating and arranging the pore tube 80 in advance in a cylindrical metal fitting 71 having a flange 71a having a diameter smaller than that of the support plate 33 is inserted into the support plate 33 through the moving space. I tried to hang it on. A plurality of throat bricks 81 and 82 having a diameter smaller than the outer diameter of the support plate 33 and exceeding the outer diameter of the flange 71a are stacked on the new nozzle portion 50 (nozzle unit) in the moving space. I did it.

  As a result, a space (moving space) in which the nozzle unit 50 (nozzle unit) can be removed and moved by simply disassembling the laminated throat bricks 81 and 82 is formed, so that the nozzle unit 50 (nozzle unit) can be easily formed. Can be removed. Therefore, when reconstructing the nozzle part 50 provided in the furnace bottom, it is possible to easily perform the dismantling work and to easily reconstruct the nozzle part.

  (4) In the nozzle portion 50 of the present embodiment, a latching flange 71 a is formed in a cylindrical receiving metal 71, and a pore tube 80 having a nozzle hole 77 is housed and fixed in the receiving metal 71. As a result, it can be used as the nozzle part 50 (nozzle unit) of the above (1), and since the pore tube 80 is housed and fixed in the receiving metal 71 in advance, the nozzle part is quickly constructed with respect to the furnace bottom. be able to.

  (5) In the nozzle portion 50 (nozzle unit) of the present embodiment, a bolt hole 71g (jig attachment portion) for detachably attaching the jig G is provided in the flange 71a. As a result, by providing a bolt hole 71g (jig attachment part) for detachably attaching the jig G, the nozzle part 50 (nozzle unit) is attached to the support plate 33 using the jig G. It can be easily latched or released. As a result, the nozzle unit 50 can be easily reconstructed.

(6) In the present embodiment, the receiving metal 71 is configured as a single unit, unlike the conventional receiving metal 104, so that the number of parts can be reduced.
In addition, this invention is not limited to the said embodiment, You may change as follows.

In the above embodiment, the pore tube 80 is formed from a single refractory brick, but the number is not limited and may be formed from a plurality of refractory bricks.
In the above-described embodiment, the bolt hole 71g is provided in the flange 71a as the jig mounting portion. However, the jig mounting portion is not limited to the bolt hole 71g, or a hole to which the jig can be attached and detached, or You may form by a notch.

  In the configuration of the embodiment, the pore tube 75 and the pore tube 80 may be integrated.

The sectional view of the plasma furnace of one embodiment of the present invention. Similarly sectional drawing of a centrifugal furnace. The principal part enlarged view which similarly shows the support structure of a nozzle part. The top view of a receiving metal fitting similarly. Sectional drawing of a receiving metal fitting similarly. Sectional drawing of the conventional centrifugal furnace. The principal part enlarged view which shows the support structure of the conventional nozzle part.

Explanation of symbols

32 ... Iron skin, 32a ... Outlet, 33 ... Support plate, 40A ... Refractory brick,
50 ... Nozzle part (nozzle unit), 71 ... Bracket, 71a ... Flange,
80 ... Pore tube, 80a ... Nozzle hole, 81 ... Throat brick, 81a ... Through hole (throat part), 82 ... Throat brick, 82a ... Through hole (throat part).

Claims (5)

A ring-shaped support plate is arranged at the periphery of the tap hole provided in the furnace bottom,
A nozzle unit configured by accommodating and arranging a pore tube having a nozzle hole in a cylindrical receiving metal fitting having a flange having a diameter smaller than that of the support plate is hung on the support plate by the flange. Placed at the spearhead,
A plurality of throat bricks having a diameter smaller than the outer diameter of the support plate and exceeding the outer diameter of the flange are stacked on the pore tube, and the throat portion of the throat brick and the nozzle hole of the pore tube communicate with each other. A support structure for a nozzle unit, wherein   The support structure for a nozzle unit according to claim 1, wherein the plurality of throat bricks have the same outer diameter. Removing the throat brick disposed above the nozzle unit to form a moving space with respect to the furnace bottom having the support structure for the nozzle unit according to claim 1 or 2,
Unlocking the nozzle unit with the support plate and removing it through the moving space;
A step of hooking a new nozzle unit configured by storing and arranging a pore tube in advance in a cylindrical receiving bracket having a flange having a smaller diameter than the support plate to the support plate through the moving space;
And laminating a plurality of throat bricks having a diameter smaller than the outer diameter of the support plate and exceeding the outer diameter of the flange on the new nozzle unit in the moving space. How to replace the nozzle unit.   A nozzle unit characterized in that a latching flange is formed on a cylindrical metal fitting, and a pore tube having a nozzle hole is housed and fixed in the metal fitting.   The nozzle unit according to claim 4, wherein the flange is provided with a jig attachment portion for detachably attaching a jig.

Images