JP4485321B2 - Batch furnace - Google Patents

Description

  The present invention relates to a batch-type heating furnace, and more particularly to a batch-type heating furnace that can uniformly and efficiently heat a workpiece such as ceramics.

Horizontal electric furnaces are widely used for calcining and main firing of ceramics such as dielectric materials and piezoelectric materials.
Such a horizontal electric furnace has a structure in which a cylindrical furnace core tube is inserted in a horizontal direction (horizontal direction) into a furnace body in which a heater or the like is installed. The container is placed in the furnace core tube and heated for a certain time.

  However, the horizontal electric furnace described above is small and suitable for firing a small amount of sample, but since the object to be processed is heated in a furnace core tube, Heat was not uniformly transmitted to individual particles, and there was a drawback that quality variations were likely to occur. Further, when heat treatment is performed while introducing various gases and reacting with the object to be processed, there is a concern that the object to be processed does not come into uniform contact with the introduced gas and uneven reaction occurs.

  Therefore, a cylindrical furnace core tube having one end closed with a lid and a removable cap attached to the other end is supported so as to be rotationally driven in a furnace body equipped with a heating means such as a burner or a heater. A predetermined amount is put into the furnace core tube by removing the cap, and the object to be processed is fired by performing heat treatment for a predetermined time while the cap is closed and the furnace core tube is rotationally driven. Patent Document 1 discloses a batch-type rotary kiln configured to open and discharge a fired product from the furnace core tube.

  In addition, when heating the workpiece in an inert gas atmosphere or a reducing gas atmosphere, an inert gas such as nitrogen gas or a reducing gas such as hydrogen is supplied from one end of the furnace core tube to the furnace core. In general, the gas supplied into the tube and discharged from the other end of the furnace core tube is discharged.

JP 2000-297986 A

  According to the batch type rotary kiln disclosed in the above-mentioned Patent Document 1, even when the object to be processed is a powder, since it receives a stirring action by the rotation of the furnace core tube, compared to the horizontal electric furnace described above, Although it is considered that the quality variation can be improved, it still has the following drawbacks.

  That is, the heating furnace shown in Patent Document 1 has a structure in which a furnace core tube is installed over the entire width of the furnace body, and the workpiece is heated using the entire area of the furnace core tube. Has a temperature distribution, that is, temperature unevenness with respect to the object to be processed. Generally, the temperature at the center of the furnace core tube is high, and the temperature tends to be lower at both ends of the furnace core tube. Therefore, the amount of heat received by the object to be processed varies greatly depending on where the object to be processed has stayed for many hours in the furnace core tube, and this causes variations in the quality of the processed object (firing unevenness). There was sorrow.

  In the heating furnace shown in the above-mentioned Patent Document 1, since the furnace core tube is not easily removable, it is difficult to sufficiently clean the inside of the furnace core tube. Since there is no effective prevention or mitigation measure against the adherence of the object to be treated, these are also factors that hinder the uniform heating of the object to be treated, and there is a concern that the quality of the object to be treated may vary. .

  Furthermore, in general, when heating the object to be processed in an inert gas atmosphere or a reducing gas atmosphere, the inert gas or the reducing gas is simply flowed in the furnace core tube in one direction. In the so-called one-way flow method, the internal air is not sufficiently replaced, and the contact with the object to be processed is not sufficient.

  The present invention has been made in view of the problems of the background art described above, and an object of the present invention is to provide a batch-type heating furnace capable of heating an object to be processed such as ceramics uniformly and efficiently.

In order to achieve the above-described object, the present invention provides a furnace body provided with heating means, a furnace core tube supported so as to be rotationally driven in the furnace body, and a soaking zone in the vicinity of the soaking zone inside the furnace core tube. A ring-shaped reflecting plate that is inserted and supported and includes a container for processing objects that rotates as the furnace core tube rotates, and is attached to the outer peripheral surface of the furnace core tube between the furnace body and the furnace core tube. And a ring-shaped heat insulating material attached to the side wall portion of the furnace body located on the outer peripheral portion of the reflecting plate, and a ring-shaped plate attached to the side wall portion of the furnace body covering the reflecting plate and the heat insulating material It was set as the batch type heating furnace provided with the heat labyrinth .

Here, as a preferred embodiment of the present invention , a hole is formed in the end wall of the storage container, and a gas introduction pipe is inserted into the storage container through the hole. Further , a scraper is attached to a portion of the gas introduction pipe inserted into the storage container.

Further, the reflecting plate is formed of a white ceramic, the heat insulating material to form a black ceramic, the plates are formed of aluminum.

  According to the batch-type heating furnace according to the present invention described above, since the storage container rotates with the rotation of the furnace core tube in the vicinity of the soaking zone inside the furnace core tube, the object to be processed put in the storage container is In addition, a processed product with good quality without variation is obtained by being stirred and heated uniformly. In addition, according to the present invention, since the object to be processed is heated not in the furnace core tube, which is difficult to clean, but in a storage container that can be easily removed and cleaned, the object to be processed can be heated uniformly. Moreover, there is no worry that impurities are mixed in the processed material.

Further, according to the batch-type heating furnace according to the present invention, a ring-shaped reflecting plate attached to the outer peripheral surface of the furnace core tube between the furnace body and the furnace core tube, and a position on the outer peripheral portion of the reflecting plate. Since a heat labyrinth is provided that includes a ring-shaped heat insulating material attached to the side wall portion of the furnace body and a ring-shaped plate attached to the side wall portion of the furnace body covering the reflector and the heat insulating material, Heat can be prevented from being released from the gap between the furnace body and the furnace core tube, and the temperature distribution of the furnace core tube can be suppressed. Moreover, despite the simple structure, it is possible to effectively prevent heat, particularly heat radiation, mainly radiant heat.

Further, when a hole is formed in the end wall of the storage container, and a gas introduction pipe is inserted into the storage container through the hole, an inert gas or a reducing gas is directly supplied into the storage container through the introduction pipe. Can be filled with the supplied gas in a very short time, and the gas can be efficiently brought into contact with the object to be processed, so that a homogeneous processed object without reaction unevenness can be obtained. it can. Further, when a scraper is attached to the portion of the gas introduction pipe inserted into the storage container, the scraper prevents the workpiece from adhering to the inner wall of the storage container, and immediately scrapes off even if it adheres. Therefore, the object to be processed can be baked without unevenness.

Furthermore, the reflector is formed of a white ceramic, the heat insulating material to form a black ceramic, when the plates are formed of aluminum, high heat resistance, and, become more highly shielding effect heat dissipation preventing structure, heat As a result, the temperature rise of the structure outside the furnace and the atmosphere can be suppressed, and safety is improved.

Embodiments of the batch heating furnace according to the present invention will be described in detail below with reference to the drawings.
Here, FIG. 1 is a longitudinal sectional view conceptually showing the entire batch heating furnace according to the present invention. FIG. 2 is an enlarged cross-sectional view showing both end portions of the furnace core tube, where (a) shows the non-driving side and (b) shows the driving side. FIG. 3 is an exploded perspective view showing a container for processing objects. FIG. 4 is a cross-sectional view of a portion along line AA in FIG. FIG. 5 is a longitudinal sectional view showing another embodiment of the container for processing objects. FIG. 6 is a longitudinal sectional view showing a state where the gas introduction pipe is inserted into the storage container. FIG. 7 is a cross-sectional view of the storage container showing a state in which a scraper is attached to the gas introduction pipe. FIG. 8 is a partially enlarged longitudinal sectional view showing the heat labyrinth between the furnace body and the furnace core tube. FIG. 9 is a cross-sectional view showing a structure for attaching the reflector to the furnace core tube.

  In FIG. 1, reference numeral 1 denotes a cylindrical ceramic furnace core tube, and the furnace core tube 1 is inserted into a furnace body 3 having a heater 2 therein. The furnace core tube 1 is rotatably supported at both ends by a set of two rollers 6 and 7 that are rotatably attached to the upper portions of the brackets 4 and 5, respectively.

  Reference numeral 8 denotes a motor. A chain 11 is stretched between a sprocket 9 attached to the shaft of the motor 8 and a sprocket 10 attached to the rotation shaft of the one roller 7 to drive the motor 8. Thus, the furnace core tube 1 is configured to be rotationally driven around its axis.

  Further, as shown in detail in FIGS. 2 (a) and 2 (b), thick rotation supports 12 and 13 are attached to both ends of the furnace core tube 1, respectively. The rotary supports 12 and 13 have notches 12a and 13a formed on the inner surface of one end portion in accordance with the outer diameter of the furnace core tube 1, and the notches 12a and 13a have ends of the furnace core tube 1 at the notches 12a and 13a. The parts are fixed by being fitted or bonded.

  Further, female screws 12b and 13b are formed on the inner surfaces of the other ends of the rotation supports 12 and 13, respectively, and male screws 14a and 15a that are screwed into the female screws 12b and 13b are provided with hooks. The end plates 14 and 15 are screwed into the end portions of the rotary supports 12 and 13, respectively, so that both end portions of the furnace core tube 1 are closed.

  In FIGS. 2A and 2B, reference numerals 16 and 17 denote heat-resistant O-rings for ensuring the sealing of the rotary supports 12 and 13 and the end plates 14 and 15, respectively. Further, a groove 18 having a width slightly wider than the width of the roller 6 is provided on the entire surface of the surface of the rotation support 12 on the counter drive side shown in FIG. The furnace core tube 1 is prevented from being displaced in the axial direction during operation. On the other hand, the drive-side rotation support 13 shown in FIG. 2B is not provided with the groove as described above. This is to allow the furnace core tube 1 to extend in the longitudinal direction due to thermal expansion. The furnace body 3, the brackets 4, 5 and the motor 8 are all fixed to a base 19.

  Further, in FIG. 1, reference numeral 20 denotes a storage container, and the storage container 20 is placed in the soaking zone of the furnace core tube 1, for example, near the center in the longitudinal direction of the furnace core tube 1 in a state where the workpiece P is put. Is interpolated and supported. As shown in FIG. 3, the storage container 20 has a cylindrical main body 21 in which female screws 21 a are formed on the inner surfaces of both ends, and male screws 22 a that are respectively screwed into both ends of the cylindrical main body 21. A substantially disc-shaped lid 22 is provided. Both the cylindrical main body 21 and the lid body 22 constituting the storage container 20 are formed of ceramics, for example, ceramics such as mullite and alumina, and the outer diameter thereof is slightly (2 It is designed to be small (˜5 mm). Moreover, it is preferable that the length is designed to be 1/5 to 1/2 of the effective dimension L of the furnace core tube 1 from the relationship with the soaking zone width of the furnace core tube 1.

  A through hole 23 is provided in the center of the lid body 22. Further, a scraping blade 24 is provided on the inner surface of the cylindrical main body 21. The scraping blades 24 are attached to the inner surface of the cylindrical main body 21 at three equal intervals (equal angles) as shown in FIG. This scraping blade 24 is used when the processing object P is not mixed by sliding on the inner surface of the storage container 20 even when the storage container 20 rotates as the furnace core tube 1 rotates. This is effective when mixing P with stirring.

  FIG. 5 is a longitudinal sectional view showing another embodiment of the storage container 20. As shown in the figure, the storage container 20 is formed by forming funnel-shaped notches 25 communicating with the through holes 23 on the inner side of one lid 22 and the outer side of the other lid 22, respectively. is there. By forming such a funnel-shaped notch 25, the workpiece P can be easily put in and out without removing the lid 22 from the cylindrical main body 21.

  The storage container 20 is supported by a spacer 26 in the vicinity of the center portion in the longitudinal direction of the furnace core tube 1 (near the soaking zone) X. The spacer 26 is specifically an elongated cylindrical member. However, it is not limited to this shape, and may be a cylindrical member having the same diameter as the cylindrical main body 21 of the storage container 20 and a long length. Further, instead of one spacer 26, a protrusion may be provided at a predetermined position on the inner surface of the furnace core tube 1.

  Through holes 27 and 28 are respectively provided in the center portions of the end plates 14 and 15 that close both ends of the furnace core tube 1. As shown in FIG. 1, the gas introduction pipe 29 is inserted into the furnace core pipe 1 through the through hole 28 of one end plate 15. The gas introduction pipe 29 is rotatably supported by a rotary joint 30 attached to the end plate 15, and is configured to be able to maintain a stationary state regardless of the rotation of the furnace core pipe 1.

  As shown in FIG. 6, the gas introduction pipe 29 is provided with a large number of holes 31 at equal intervals in a plurality of rows and in a staggered arrangement. The gas introduction pipe 29 is inserted over the entire axial direction into the storage container 20 through the through hole 23 of the lid body 22 described above. Further, as shown in FIG. 7, a scraper 32 can be provided in a portion of the gas introduction pipe 29 existing in the storage container 20. This scraper 32 has a strong adherence to the object P to be processed, and prevents the object to be fused to the inner wall of the storage container 20 during baking or the objects to be processed from fusing together. Effectively used to take or loosen. In addition, when this scraper 32 is attached, the scraping blade 24 of the workpiece cannot be attached. Further, for example, as shown in FIG. 7, it is preferable that the scraper 32 is fixed at an arbitrary position from the viewpoint of the scraping effect. Therefore, it is better not to rotate the gas introduction pipe 29.

  In FIG. 1, 33 is a heat labyrinth between the furnace body 3 and the furnace core tube 1. The heat labyrinth 33 is for preventing heat radiation by radiant heat mainly from far infrared rays from the gap between the furnace body 3 and the furnace core tube 1 and improving thermal efficiency. As shown in FIG. 8, the heat labyrinth 33 includes a ring-shaped reflecting plate 34 attached to the outer peripheral surface at the end of the furnace core tube 1 protruding from the furnace body 3, and an outer periphery of the reflecting plate 34. The ring-shaped heat insulating material 35 attached to the side wall portion of the furnace body 3 located in the section, and the L-shaped cross section attached to the side wall portion of the furnace body 3 covering the reflector 34 and the heat insulating material 35 from the outside. It is comprised with the ring-shaped plate 36. FIG.

  The reflecting plate 34 and the heat insulating material 35 are both preferably made of ceramics. In particular, the reflecting plate 34 is preferably formed of white ceramics from the viewpoint of reflection efficiency. It is preferable to be formed of black ceramics because it can absorb far-infrared rays that are irregularly reflected and further improve the shielding effect. In addition, the use of an aluminum plate with little radiation heat dissipation for the plate 36 located on the outermost side of the heat labyrinth 33 can further reduce far-infrared radiation to the outside of the furnace body 3. This is preferable because the temperature rise of the external structure and the atmosphere can be suppressed.

As a method for attaching the ring-shaped reflector 34 to the outer peripheral surface of the furnace core tube 1, for example, as shown in FIG. 9, the reflector 34 is divided into two parts (substantially semicircular), and the furnace core tube is formed from the outside. A method of sandwiching 1 and tightening with a bolt 37 is employed.
In FIG. 1, reference numeral 38 denotes a safety cover that covers the entire apparatus, and 39 denotes a safety door switch of the safety cover 38.

Next, a method for operating the batch heating furnace according to the present invention configured as described above will be described.
First, one lid body 22 of the storage container 20 is opened, a certain amount of the processing object P is put into the storage container 20, and the lid body 22 is closed. Here, the standard of the input amount is about 25% of the volume of the storage container 20. If more than this is added, the workpiece P is difficult to be mixed during heating, and there is a concern that it will not be heated uniformly. Further, when various gases are supplied from the gas introduction pipe 29 into the storage container 20, depending on the supply speed of the gas, the workpiece P is blown off by the ejection of the gas, and the through hole formed in the lid body 22. There is also a concern that the workpiece P may be discharged into the furnace core tube 1 through 23.

  Next, one end plate 14 is removed, and the spacer 26, the storage container 20, and the spacer 26 are inserted into the furnace core tube 1 in this order, the end plate 14 is tightened, the safety cover 38 is closed, and the safety door switch 39 is activated. Let

  Subsequently, a heating rate, a firing time, a cooling rate, a rotation speed of the furnace core tube 1 (motor 8), and the like are input to an operation panel (not shown), and if necessary, before the heating operation, Various gases (inert gas, reducing gas, etc.) are supplied into the furnace core tube 1 and the storage container 20 through the introduction tube 29 to replace the internal air. In this case, when the furnace core tube 1 is rotated, the air in the workpiece P is also efficiently replaced.

  Next, firing is started based on a program input to the operation panel. Then, the storage container 20 follows the rotation of the furnace core tube 1 and hardly rotates within the furnace core tube 1 and rotates in the same direction. And the to-be-processed object P is stirred and mixed by the scraping blade | wing 24 attached to the inner surface of the storage container 20, and baking advances, heating uniformly. Further, when various reaction gases are supplied, the various reaction gases are ejected through the numerous holes 31 of the gas introduction pipe 29 to the surface of the workpiece P that has been agitated and mixed and replaced. The mixture is evenly mixed with the workpiece P and firing proceeds while uniformly reacting with various reaction gases.

  When the firing process based on the program ends and the temperature in the furnace core tube 1 falls to a safe temperature (for example, 40 ° C.) or lower, the safety door switch 39 is released. Therefore, the safety cover 38 is opened, the storage container 20 is taken out from the furnace core tube 1 in the reverse order to the above, and the processed product is taken out from the storage container 20.

  The embodiment of the batch heating furnace according to the present invention has been described above. However, the present invention is not limited to the embodiment described above, and the technical aspects of the present invention described in the claims are described below. It goes without saying that various modifications and changes are possible within the scope of the idea.

  Next, examples of baking treatment using the batch heating furnace of the present invention described above will be described together with comparative examples.

-Material to be treated-
Formulation of lithium carbonate [Li ₂ CO ₃ ], iron hydroxide oxide [FeOOH], manganese oxide [Mn ₂ O ₃ ] and lithium iron manganate [Li (Fe _1/2 Mn _1/2 ) O ₂ ] Each was weighed so as to have a ratio, and mixed and ground using a grinding machine (manufactured by Nara Machinery Co., Ltd .: Mechano Micros).
In addition, the processing conditions by an attritor were as follows: processing time: 90 min, vessel rotation speed: 200 min ⁻¹ , rotor rotation speed: 1000 min ⁻¹ .

-Example-
The object to be processed prepared by the above method was fired using the batch heating furnace of the present invention shown in FIG.
The operating conditions were as follows: firing temperature: 800 ° C., firing time: 1 hour, rotation speed of furnace core tube: 5 min ⁻¹ , charged amount of object to be processed: 10 ml, atmospheric gas: argon 200 ml / min.

-Comparative example-
As a comparative example, using a horizontal heating furnace (manufactured by Asahi Rika Seisakusho Co., Ltd .: ARF-50M), the same workpiece as in the above example was baked under the same operating conditions as in the above example.

-Evaluation-
The X-ray diffraction patterns of the fired products obtained in the examples and comparative examples are shown in FIG.
From the figure, it can be seen that all of the fired products obtained from the batch heating furnace of the present invention are cubic single-phase particles. On the other hand, it can be seen that the fired product obtained from a conventional horizontal heating furnace is a mixture of cubic and hexagonal crystals.
From the above, it was found that the batch heating furnace of the present invention can uniformly and efficiently heat the workpiece.

It is the longitudinal cross-sectional view which showed notionally the whole batch type heating furnace which concerns on this invention. FIG. 2 is an enlarged cross-sectional view showing both end portions of the furnace core tube, where (a) shows the non-driving side and (b) shows the driving side. FIG. 3 is an exploded perspective view showing a container for processing objects. FIG. 4 is a cross-sectional view of a portion along line AA in FIG. FIG. 5 is a longitudinal sectional view showing another embodiment of the container for processing objects. FIG. 6 is a longitudinal sectional view showing a state where the gas introduction pipe is inserted into the storage container. FIG. 7 is a cross-sectional view of the storage container showing a state in which a scraper is attached to the gas introduction pipe. FIG. 8 is a partially enlarged longitudinal sectional view showing the heat labyrinth between the furnace body and the furnace core tube. FIG. 9 is a cross-sectional view showing a structure for attaching the reflector to the furnace core tube. FIG. _{2 is} an X-ray diffraction pattern of lithium iron manganate [Li (Fe _1/2 Mn _1/2 ) O ₂ ] powder obtained by processing with the apparatus of the present invention and the apparatus of a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Core tube 2 Heater 3 Furnace body 4 Bracket 5 Bracket 6 Roller 7 Roller 8 Motor 9 Sprocket 10 Sprocket 11 Chain 12 Rotation support 12a Notch 12b Female screw 13 Rotation support 13a Notch 14b Female screw 14 End plate 14a Male screw DESCRIPTION OF SYMBOLS 15 End plate 15a Male screw 16 O-ring 17 O-ring 18 Groove 19 Base 20 Storage container 21 Cylindrical main body 21a Female screw 22 Lid 22a Male screw 23 Through-hole 24 Raising blade 25 Notch 26 Spacer 27 Through-hole 28 Through Hole 29 Gas introduction pipe 30 Rotary joint 31 Hole 32 Scraper 33 Heat labyrinth 34 Reflector 35 Heat insulating material 36 Plate 37 Bolt 38 Safety cover 39 Safety door switch X Soaking tropics L Effective length of furnace core tube P

Claims (4)

A furnace body provided with a heating means, a furnace core tube supported so as to be rotationally driven in the furnace body, and inserted and supported in the vicinity of the soaking zone inside the furnace core tube, and rotated as the furnace core tube rotates. A ring-shaped reflecting plate attached to the outer peripheral surface of the furnace core tube between the furnace body and the furnace core tube, and a furnace located on the outer peripheral portion of the reflecting plate A heat labyrinth comprising a ring-shaped heat insulating material attached to the side wall portion of the body and a ring-shaped plate attached to the side wall portion of the furnace body covering the reflector and the heat insulating material is provided. A batch heating furnace. The batch heating furnace according to claim 1, wherein a hole is formed in an end wall of the storage container, and a gas introduction pipe is inserted into the storage container through the hole. The batch heating furnace according to claim 2, wherein a scraper is attached to a portion of the gas introduction pipe inserted into the storage container. The batch type according to any one of claims 1 to 3, wherein the reflector is formed of white ceramics, the heat insulating material is formed of black ceramics, and the plate is formed of aluminum. heating furnace.

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