JP2005076959A - Continuous heat treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a treated object which received a high quality heat treatment and simplify a structure of continuous heat treatment equipment by promoting heat treatment of the treated object by making unnecessary gas component for the heat treatment in atmospheric gas in a core pipe to be appropriately discharged from the core pipe. <P>SOLUTION: In the continuous heat treatment equipment equipped with the cylindrical core pipe 2 which is rotation-driven around a shaft center in a status storing the treated object, a heating means 5 for heating the core pipe 2, a supply device 8 for supplying the treated object from an end side in a shaft direction into the core pipe 2 and a discharging device for discharging the treated object traveled in the core pipe 2 from the other end side in the shaft direction and the treated object can travel from an end side in the shaft direction to the other end side along an inner peripheral face of the core pipe, a gas discharging mechanism 11 for sucking the unnecessary gas component from the core pipe 2 and discharging it to outside is provided and a gas discharging part to outside in the gas discharging mechanism 11 is provided at a treated object supply side part of the core pipe. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a continuous heat treatment apparatus used for heat treatment (for example, calcination) of an object to be treated such as powder.

  Conventionally, as a continuous heat treatment apparatus, a cylindrical furnace core tube heated by a heating means such as a heater is inclined so that the workpiece supply side is at the upper position and the processed object discharge side is at the lower position. In such a state, a structure that can rotate around its central axis has been proposed (see Patent Document 1).

  Thereby, the workpiece is heat-treated while being moved in the furnace core tube. That is, an object to be processed such as ceramic powder is heat-treated by heating by a heating means while passing through the rotationally driven furnace core tube, and the heat-treated object to be treated is discharged from one end side of the furnace core tube. The

This conventional continuous heat treatment apparatus includes a furnace core tube body in which the furnace core tube is rotationally driven and an inner member made of a porous plate provided inside the furnace core tube body. In this continuous heat treatment apparatus, the inside of the furnace core tube is alternately switched between a pressure reducing state and a pressure increasing state, and the switching is performed every half rotation. That is, the object to be processed is attached to the inner surface of the furnace core tube by decompression, and then the furnace core tube is rotated halfway so that the inner surface part of the furnace core tube to which the object to be processed is attached is positioned on the upper side. By pressurizing in this state, the adherence of the workpiece to the inner surface of the furnace core tube is released, so that the workpiece is dropped downward, and then the pressure is reduced. Thus, heat treatment with high uniformity can be performed on the object to be processed.
JP-A-8-178543 (all pages, all figures)

  In the case of a conventional continuous heat treatment apparatus in which a furnace core tube is constituted by a furnace core tube body that is rotationally driven and an inner member made of a porous plate provided inside the furnace core tube body, the furnace core tube body In addition, the object to be processed moves along the inner peripheral surface portion of the inner member rotated together, and the object to be processed may be clogged in the hole of the inner member formed of the porous plate. In this case, there is a problem that adhesion due to suction of the object to be processed and separation of the object to be processed from the inner member due to pressure become insufficient, and it becomes difficult to perform heat treatment properly. In addition, there is a problem such as a complicated structure due to the separate provision of an inner member made of a porous plate.

  Furthermore, in the conventional continuous heat treatment apparatus, only the pressure reduction for lowering the internal pressure is performed in order to adsorb the object to be treated to the inner member of the furnace core tube, and consideration is given to removing unnecessary gas components accompanying the heat treatment. It was not a thing. For this reason, in the conventional continuous heat treatment apparatus, unnecessary gas components may remain in the furnace core tube and have a concentration higher than a predetermined concentration, and such high concentration unnecessary gas components may remain in the furnace core tube. By being contained in the atmospheric gas, the reaction accompanying the heat treatment of the portion to be processed tends to be difficult to proceed. In this case, the reaction of the object to be processed may be discharged with insufficient progress.

  Thus, when the concentration of the unnecessary gas in the atmosphere gas in the furnace core tube becomes constant at a high value, there is a tendency that unreacted components tend to increase in the object to be heat treated, and the characteristics as the object to be treated are deteriorated.

  Therefore, the present invention promotes the heat treatment of the object to be processed by enabling the gas components unnecessary for the heat treatment in the furnace core tube to be discharged well from the inside of the furnace core tube, and the object to be processed that has been heat-treated at a high quality. In addition, the provision of a continuous heat treatment apparatus that can simplify the structure is an issue to be solved.

  The heat treatment apparatus according to the present invention includes a cylindrical furnace core tube that is rotationally driven around an axis in a state in which an object to be processed is accommodated, a heating unit that heats the furnace core tube, and an axial direction in the furnace core tube. A supply device for supplying the object to be processed from one end side, and a discharge device for discharging the object to be processed moved in the furnace core tube from the other end side in the axial direction. In the continuous heat treatment apparatus configured to be movable from one end side to the other end side in the axial direction along the circumferential surface, a gas discharge mechanism for sucking unnecessary gas components from the furnace core tube and discharging them to the outside is provided, and the furnace A gas discharge section to the outside of the gas discharge mechanism is provided in the workpiece supply side portion of the core tube. The furnace core tube is preferably cylindrical.

  According to the continuous heat treatment apparatus according to the present invention, the gas discharge mechanism provided in the workpiece supply side portion of the furnace core tube discharges unnecessary gas components in the atmospheric gas in the furnace core tube to the outside of the furnace core tube. Therefore, with respect to unnecessary gas components generated in the furnace core tube due to the heat treatment of the object to be heat-treated, the unnecessary gas components are eliminated from the furnace core tube from the beginning of the heat treatment. For this reason, unnecessary gas components do not stay in the furnace core tube, and it is possible to eliminate the suppression of the reaction of the object to be processed during the heat treatment.

  Further, the continuous heat treatment apparatus of the present invention does not separately provide a porous internal member in the furnace core tube as in the prior art, and has a simple structure. Furthermore, since the continuous heat treatment apparatus of the present invention does not repeatedly reduce or increase the pressure in the furnace core tube, the pressure control and the rotation control of the furnace core tube can be easily performed.

  In the heat treatment apparatus according to the present invention, preferably, the gas discharge portion of the gas discharge mechanism is provided at an end surface portion of the furnace core tube on a side to which an object to be processed is supplied, and is a main part of the furnace core tube. The gas flow is directed toward the end face portion. In this case, rather than providing the gas discharge part on the outer peripheral part of the furnace core tube that is rotationally driven, the gas discharge part is provided by utilizing the end surface part that is not rotated as a configuration capable of discharging gas even if driven to rotate. Therefore, the structure is simple. Moreover, since the end surface portion is positioned on the uppermost side when the object to be processed moves while being heated in the furnace core tube, the discharge can be performed in a state where the retention of unnecessary gas components can be further suppressed.

  In the heat treatment apparatus according to the present invention, the gas discharge mechanism in which the gas discharge portion is provided in the workpiece supply side portion of the furnace core tube has a gas discharge portion to the outside in another portion of the furnace core tube. It is preferable to have a higher gas discharge capacity than other gas discharge mechanisms provided. In this case, even if the gas discharge mechanism is provided in addition to the workpiece supply side portion of the furnace core tube, the gas discharge mechanism provided in the workpiece supply side portion has the highest gas discharge capability. The flow of exhausting unnecessary gas in the furnace core tube tends to be directed toward the initial location where the heat-treated object is heated, and the retention of unnecessary gas components in the furnace core tube is sufficiently suppressed.

  In the heat treatment apparatus according to the present invention, preferably, the pressure in the furnace core tube is set to an atmospheric pressure or less by gas discharge by the gas discharge mechanism. In this case, it is easy to take outside air into the furnace core tube from which unnecessary gas components are discharged, and it is possible to purify the atmospheric gas and to react with the object to be processed accompanying the heat treatment. Gas generation is also easily promoted.

  According to the continuous heat treatment apparatus according to the present invention, the gas discharge mechanism provided in the workpiece supply side portion of the furnace core tube discharges unnecessary gas components in the atmospheric gas in the furnace core tube to the outside of the furnace core tube. Therefore, with respect to unnecessary gas components generated in the furnace core tube due to the heat treatment of the object to be heat-treated, the unnecessary gas components are eliminated from the furnace core tube from the beginning of the heat treatment. For this reason, unnecessary gas components do not stay in the furnace core tube, and it is possible to eliminate the suppression of the reaction of the object to be processed during the heat treatment.

  In addition, it is a configuration in which only the furnace core tube is provided as a member that moves while the workpiece is heat-treated, and the furnace core tube can be heat-treated by continuing constant rotation. It is possible to simplify the control of the rotation of the furnace core tube.

  An embodiment of a continuous heat treatment apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal side view showing an example of a continuous heat treatment apparatus, and FIG. 2 is a graph showing a distribution state of internal carbon dioxide concentration in the continuous heat treatment apparatus of FIG.

  In this embodiment, a continuous heat treatment apparatus 1 for producing barium titanate by solid phase reaction of barium carbonate and titanium dioxide as an object to be processed will be described. Referring to FIG. 1, a continuous heat treatment apparatus 1 is a rotary kiln (rotary retort furnace), and includes a cylindrical furnace core tube 2 in a state where the furnace length direction is inclined with respect to the horizontal. The continuous heat treatment apparatus 1 includes a plurality of rollers 3 that support a furnace core tube 2 so as to be rotatable around the axis of the cylinder, and an electric motor 4 that drives the furnace core tube 2 through the rollers 3. And a furnace body 6 provided with a heater 5 as a heating means arranged so as to surround the furnace core tube 2 along the furnace length direction. The heater 5 for heating is controlled in accordance with a heating temperature and a heating profile corresponding to the type of the ceramic object to be processed. The furnace core tube 2 itself is composed of a dense solid material (for example, mullite) having no holes or micropores communicating with the inside or outside so that the powder object to be processed does not leak outside during the heat treatment. Yes. A partition 7 that covers the furnace core tube 2 is provided on a side surface on one end side that is the upper side of the furnace core tube 2. A central portion of the partition 7 is opened, and a workpiece supply apparatus 8 for introducing a ceramic workpiece to be processed into the furnace core tube 2 passes therethrough. On the other hand, the other end, which is the lower side of the furnace core tube 2, is open because the raw material is discharged. The 2nd partition body 9 which controls discharge | emission depending on a to-be-processed object is provided. The second partition 9 is provided in a spiral shape with respect to the axial direction of the furnace core tube 2.

  An object supply device 8 for supplying an object to be processed through a partition 7 constituting one end portion of the furnace core tube 2 has a predetermined amount per unit time from a supply-side hopper 10 that stores the powder object to be processed. A ceramic workpiece can be supplied into the furnace core tube 2. The workpiece supply device 8 is, for example, a screw-type transfer device provided in a transfer cylinder so as to be rotatably driven, and a raw material supply port at an end of the workpiece supply device 8 is provided in the furnace core tube 2. I ’m here. Since the partition 7 is provided integrally with the furnace core tube 2, the partition 7 rotates together with the furnace core tube 2. Further, a gas discharge mechanism 11 for discharging atmospheric gas in the furnace core tube 2 to the outside on the same side as the workpiece supply apparatus 8 penetrates the partition body 7. The gas discharge mechanism 11 is an exhaust pump having an intake port facing the furnace core tube 2 and an exhaust port facing the outside, and is driven by an electric motor (not shown).

  The second partition 9 receives the object to be processed discharged from the furnace core tube 2 and performs storage or guidance to the next process, and is fixed to the furnace core tube 2. The second partition 9 is formed with a discharge port that guides the workpiece that has moved to the lower end of the furnace core tube 2 to the workpiece discharge device 12. Moreover, the fixing method of the furnace core pipe 2 and the 2nd partition body 9 is not specifically limited, The material of the 2nd partition body 9 is also not limited to ceramics and a metal.

With the above configuration, this continuous heat treatment apparatus 1 supplies a mixture (same molar amount) of powdered barium carbonate (BaCO ₃ ) and powdered titanium dioxide (TiO ₂ ), which are raw materials to be heat treated, to the supply-side hopper 10. Is supplied into the furnace core tube 2 by a predetermined amount of the object supply device 8 per unit time. The furnace core tube 2 is continuously driven to rotate in a fixed direction at a predetermined rotational speed. The inside of the furnace core tube 2 is heated to a temperature suitable for heat treatment by the heater 5. In this state, the barium carbonate powder and the titanium dioxide powder supplied into the furnace core tube 2 by the workpiece supply device 8 move downward along the inner peripheral surface of the furnace core tube 2, and the inside of the furnace In the reaction, carbon dioxide is separated, and barium titanate powder is solid-phase synthesized. The carbon dioxide gas generated by the reaction is sucked by the gas discharge mechanism 11 together with the atmospheric gas in the furnace core tube 2 and discharged to the outside. The operation of the gas discharge mechanism 11 places the inside of the furnace core tube 2 in a negative pressure lower than the external pressure.

  The inventor measured the carbon dioxide concentration in the furnace core tube 2 of the continuous heat treatment apparatus 1 for obtaining the barium titanate. In FIG. 2, the carbon dioxide concentration at each position obtained by dividing the movement path of the object to be processed in the furnace core tube 2 by 8 is indicated by a triangle mark corresponding to the measurement position and a thick line connecting them. Note that the carbon dioxide concentration in the furnace core tube of a rotary kiln having no gas discharge mechanism was also measured for comparison, and the results are shown by white triangles and thin lines in FIG. In the case of the present invention, the gas discharge mechanism 11 is operated and the atmosphere gas in the furnace core tube 2 containing carbon dioxide gas is discharged from the workpiece input side. Although the concentration is high on the first half side of the material movement path, the carbon dioxide concentration is remarkably reduced on the second half side, and the reaction in the entire furnace core tube 2 is easily performed well. On the other hand, in the case of the comparative example, since the carbon dioxide concentration as a whole in the furnace core tube 2 is a high concentration of about 15%, a state in which a high concentration of carbon dioxide is retained in the furnace core tube 2 as a whole. It has become. In the case of this comparative example, since the carbon dioxide concentration in the atmospheric gas is high, the reaction for separating carbon dioxide does not proceed easily, and barium carbonate that has been short-passed without reaction in the workpiece discharged from the furnace core tube 2 Variations in quality became large, such as the presence of titanium dioxide.

  Next, another embodiment will be described with reference to FIG. Note that the description of the same structure as that of the above embodiment is omitted, and the same reference numerals are used in the drawings.

  Referring to FIG. 3, this continuous heat treatment apparatus 1 is also a rotary kiln. The lid body 13 at the end surface portion of the furnace core tube 2 on the side to which the workpiece is supplied is fixed integrally with the furnace core tube 2. The cylindrical portion of the joint member 14 integrated with the workpiece supply device for supplying the workpiece to the furnace core tube 2 and the cylindrical portion of the lid 13 are fitted in a relatively rotatable manner. A rotary joint 15 is configured by a structure in which the lid 13 and the joint member 14 are fitted. A non-rotating joint member 14 and a workpiece supply device 16 are provided at the center of the rotary joint 15 along the rotation center axis of the furnace core tube 2. The raw material is supplied from the end of the workpiece supply apparatus 16 facing the furnace core tube 2. There is a gap 18 between the inner walls of the workpiece supply device 16 and the rotary joint 15, and the atmospheric gas sucked in the furnace core tube 2 is exhausted through the gap 18. The gas exhausted through the gap 18 is exhausted to the outside through the exhaust chamber 17 that is integral with the workpiece supply device 16. A vacuum pump (not shown) for exhausting the atmospheric gas to the outside is provided in the exhaust part of the exhaust chamber 17. Further, a supply path is formed so that the object to be processed can be supplied into the furnace core tube 2 by the object supply device 16. Therefore, the object to be processed (a mixture of powdered barium carbonate and powdered titanium dioxide) can be supplied to the furnace core tube 2 that is driven to rotate through the rotary joint 15.

  The workpiece is heated by the heater 5 to accelerate the reaction, so that carbon dioxide is separated and converted into barium titanate and discharged from the discharge end of the furnace core tube 2. This discharge portion is also formed in the rotary joint 18. That is, the cylindrical portion of the second lid 19 integrated with the furnace core tube 2 and the cylindrical portion of the joint member 21 integrated with the hopper-shaped workpiece discharge portion 20 that receives the discharged workpiece are relatively disposed. A rotary joint 18 is configured by being fitted in a rotatable manner. A discharge path through which the workpiece can be discharged from the furnace core tube 2 to the workpiece discharge portion 20 is formed in the cylindrical portion of the second lid 19 and the cylindrical portion of the joint member 21.

  In each of the above-described embodiments, the continuous heat treatment apparatus provided with only one gas discharge mechanism for discharging unnecessary gas from the furnace core tube to the outside is shown, but a plurality of gas discharge mechanisms may be provided. However, even in that case, a gas discharge mechanism must be provided on the side where the workpiece is supplied into the furnace core tube. Further, the gas discharge mechanism for supplying the object to be processed into the furnace core tube needs to have a higher discharge capacity than the other gas discharge mechanisms. For example, if the gas discharge mechanism is provided only on the discharge side of the workpiece, or if the gas discharge mechanism provided on the discharge side is set to have the highest discharge capacity, the discharge from the furnace core tube is performed. The concentration of unnecessary gas on the exhaust side increases, and the reaction due to the heat treatment on the exhaust side decreases, and unreacted workpieces are likely to be generated. Is promoted, and the reaction of the object to be processed can be completed.

Schematic longitudinal sectional view of a continuous heat treatment apparatus according to an embodiment of the present invention 1 is a graph showing the carbon dioxide concentration in the furnace core tube during heat treatment in the continuous heat treatment apparatus of FIG. 1 and the continuous heat treatment apparatus of the comparative example. Schematic longitudinal sectional view of a continuous heat treatment apparatus according to another embodiment of the present invention

Explanation of symbols

1 Continuous heat treatment device 2 Furnace core tube 5 Heater (heating means)
8 Supply device 11 Gas discharge mechanism

Claims (4)

A cylindrical furnace core tube that is rotationally driven around the axis in a state in which the object to be processed is stored, a heating means for heating the furnace core tube, and the object to be processed is supplied into the furnace core tube from one end in the axial direction. And a discharge device that discharges the workpiece moved in the furnace core tube from the other axial end side, and the workpiece is axially extended along the inner peripheral surface of the furnace core tube. In the continuous heat treatment apparatus configured to be movable from the side to the other end side,
A gas discharge mechanism for sucking unnecessary gas from the furnace core pipe and discharging it to the outside is provided, and a gas discharge section to the outside of the gas discharge mechanism is provided on the workpiece supply side portion of the furnace core pipe. A continuous heat treatment apparatus. The continuous heat treatment apparatus according to claim 1,
The gas discharge portion of the gas discharge mechanism is provided in an end surface portion of the furnace core tube on a side to which an object to be processed is supplied, and a main gas flow in the furnace core tube is directed to the end surface portion. Continuous heat treatment equipment. The continuous heat treatment apparatus according to claim 1 or 2,
The gas discharge mechanism in which the gas discharge unit is provided in the workpiece supply side portion of the furnace core tube is another gas discharge mechanism in which a gas discharge unit to the outside is provided in another part of the furnace core tube. A continuous heat treatment apparatus having a higher gas discharge capacity. The continuous heat treatment apparatus according to any one of claims 1 to 3,
A continuous heat treatment apparatus, wherein the pressure in the furnace core tube is reduced to an atmospheric pressure or less by gas discharge by the gas discharge mechanism.

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