JPH11351767A - Heat exchanger and production of high purity powder and grain - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform heat exchange of high purity material to be processed efficiently by passing fluid through the air gap between an outer tube and a tubular pipe and exchanging with the material to be processed. SOLUTION: A material being subjected to heat exchange is fed from one end of a tubular pipe 1. The material rolls through rotation of the tubular pipe 1 to move easily in the direction of the other end from the supply end. The tubular pipe 1 is secured at two or a plurality of supporting parts 2. An outer tube 3 is arranged to surround the tubular pipe 1 and cooling gas flows through a gap defined by the outer circumference of the tubular pipe 1 and the outer tube 3 made of a heat resistant heat insulating material. The outer tube 3 is constructed independently from the tubular pipe 1. Since a driving force for turning the tubular pipe 1 is not transmitted externally through the outer tube 3 surrounding the tubular pipe 1 through a gap passing a fluid for heat exchange, interlocked rotation of the outer tube 3 and the tubular pipe 1 is not required.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high-purity powders and granules, and a heat exchanger suitable for such a production method. The present invention can provide a method of efficiently collecting heat energy by cooling efficiently, and particularly relates to a method suitable for producing an inorganic material such as ceramic or glass.

[0002]

2. Description of the Related Art Conventionally, a rotary kiln type heating device has been generally used for continuously firing and drying powdery or granular objects to be processed. This heating device includes a cylindrical furnace tube rotating at a constant speed, and the material to be fired or dried from one end inlet is transferred to the opposite end outlet by rotation. In the externally heated rotary kiln, the workpiece is heated to a predetermined temperature by heat transfer from a heating body disposed on the outer surface of the furnace tube during this transfer. In particular, in the firing and drying of ceramic raw material powder, which requires high purity, contamination of abrasion powder of furnace tube material generated by contact with ceramic raw material powder due to reaction with heavy metal vapor generated from ceramic raw material powder. Therefore, a high-purity and high-density ceramic material is also required as a material of the furnace tube directly in contact with the ceramic powder.

[0003] Since the heat-treated object is continuously discharged from the rotary kiln at a high temperature, substantially continuous cooling of the object is required as a post-treatment step. FIG. 1 shows an apparatus for continuously cooling the object discharged from the rotary kiln.
As shown in 0 to 12, a shaft type, a rotary type, a great type, and the like are known. In these systems, a cooling gas is blown into the cooling device to cool the workpiece,
This is a type in which heat exchange is performed by direct contact between a gas as a cooling medium and a solid as an object to be processed, thereby cooling the object to be processed.
In the figure, 41 is a rotary kiln, 42 is a cooling device main body,
43 is an oscillating grid, 44 is cooling air, 45 is a flow of the object to be processed, and 46 is a flow of cooling air.

[0004]

In the cooling of ceramic raw material powder requiring high purity, the contamination of the abrasion powder of the cooling part material generated by coming into contact with the powder to be cooled, as in the case of firing and drying. From problems such as
A high-purity and high-density material is required for the material of the portion directly in contact with the ceramic powder. However, in the case of the great type and the shaft type shown in FIGS. 10 and 11, it is extremely difficult to manufacture a portion directly in contact with the ceramic powder using a material suitable for maintaining the quality of the product. For this purpose, a rotary type using a high purity and high density ceramic material for the furnace tube is desirable.

In the rotary type shown in FIG. 12, the object to be processed is cooled by direct contact with a cooling gas supplied into a rotating cylindrical tube. However, when heat transfer of the object to be treated is taken into consideration, heat radiation from the outer surface of the rotary cylindrical tube is dominant in cooling the object to be treated, in addition to direct contact with the cooling gas. Therefore, it is considered that the object to be processed can be effectively cooled by actively cooling the rotating cylindrical tube. In order to minimize contamination of impurities to be processed, a cooling device having a double structure in which a high-purity and high-density material is inserted as an inner cylinder may be considered. Further, it is desirable that the object to be processed and the cooling medium do not directly contact each other.

Here, when a cylindrical tube made of a high-purity and high-density ceramic material is used, and the condition is large or the operating temperature is high, the load or the weight of the object to be processed in the cylindrical tube is insufficient. High mechanical strength may not be obtained. In JP-A-6-191825, a quartz glass tubular body having an outer diameter smaller than its inner diameter is placed inside a tubular body composed of an outer cylinder of a metal plate and a heat insulating material. Is a device that applies a rotational driving force to the entire body and rotates about the central axis as a whole, and annular air is formed between a quartz glass tubular body that is an inner cylinder and a tubular body that constitutes an outer cylinder. There has been proposed an apparatus capable of performing heat exchange by providing a passage and moving air substantially countercurrent to the movement of quartz powder particles as an object to be processed. In this apparatus, cooling is performed by the flow of air from the outer surface of the inner cylinder.However, when processing a high-temperature workpiece, it is unavoidable that the inner cylinder becomes hot due to heat conduction. Therefore, the strength of the inner cylinder is not sufficient, and it is difficult to secure the strength. For this reason, there is a possibility that the inner cylinder may be deformed or damaged depending on the method of supporting the inner cylinder, the supporting interval, and the like.

To solve these problems, for example, as shown in FIG. 4, the inner cylinder made of a high-purity and high-density ceramic is inserted into an outer cylinder made of a heat-resistant metal, which is a protective tube, to support the inner cylinder. It is conceivable to adopt a structure that allows the inner cylinder to be supported at a support interval that ensures the strength of the inner cylinder. However, in such a cooling device having a double structure, FIG.
As shown in (1), a gap 33 is generated between the cylindrical tube 1 as the inner tube and the protective tube 31 as the outer tube. This gap is provided by the installation of a structure / mechanism for absorbing a displacement between the cylindrical tube 1 and the protective tube 31 due to a difference in thermal expansion caused by a difference in the material of the cylindrical tube 1 and the protective tube 31, The installation and adjustment of the non-slip 32 and the like for efficiently transmitting the rotational force transmitted to the cylindrical tube 1 to the cylindrical tube 1 have to be largely taken. In particular, when considering a large-sized and very long device in the axial direction for industrial use, the installation of the anti-slip 32
The adjustment is performed at the inlet 13 of the workpiece 18 which is the both end surfaces of the cylindrical tube.
Or, it is not enough just from the outlet 14. Further, due to the gap 33, the efficiency of heat transfer from the cooling medium to the processing object 18 is reduced.

[0008] The present invention has been made in view of the problems of the prior art, and has as its object to provide a heat exchange apparatus for efficiently exchanging heat of a high-purity object.

[0009]

The heat exchange device of the present invention comprises:
This was done to achieve these goals,
(1) A cylindrical tube that can be moved from one end to the other while rotating the object to be processed by rotating about a central axis, and an outer tube surrounding the cylindrical tube and independent of the cylindrical tube. A heat exchange device having a heat exchanger capable of exchanging heat with an object to be processed through a fluid in a space between the outer tube and the cylindrical tube, and (2) an inside of the cylindrical tube from one end of the cylindrical tube surrounded by the outer tube via the space. A method of heating the granular material by applying a driving force from the outside of the cylindrical tube while introducing the granular material into the cylindrical tube, rotating the cylindrical tube, exchanging heat with the granular material through the fluid through the gap, and heating the granular material. A method of heating the granular material, wherein the outer tube is independent of the cylindrical tube; (3) powder is introduced into the cylindrical tube from one end of the cylindrical tube surrounded by the outer tube via a gap; A driving force is applied from the outside of the cylindrical tube while introducing the granular material to rotate the cylindrical tube, and heat exchange with the granular material is performed through the fluid through the gap. A method of cooling a granular material for cooling a squeezed granular material, wherein the outer cylinder is independent of the cylindrical tube, and (4) a method of cooling the granular material through a gap. A high-purity powder that heat-treats the powder fluid through a fluid through the void while applying a driving force from the outside of the cylindrical pipe while introducing the powder into the cylindrical pipe from one end of the cylindrical pipe surrounded by the outer cylinder and rotating the cylindrical pipe. A method for producing a body, wherein the outer cylinder is independent of the cylindrical tube.

According to the heat exchange apparatus of the present invention, the cylindrical tube is rotated, the object to be processed is supplied from one end of the cylindrical tube into the cylindrical tube, and the inside of the cylindrical tube is rolled and moved in the other end direction.
By passing the fluid through the gap between the outer tube surrounding the cylindrical tube and the cylindrical tube, the indirect cooling of the object to be processed and the subsequent discharge from the device can be performed substantially continuously. it can. In particular, by dividing the supporting portion for fixing the cylindrical tube into a plurality of portions in the axial direction of the cylindrical tube, the supporting portion can be freely moved at the time of thermal expansion of the cylindrical tube, and the strength of the cylindrical tube can be easily maintained. By using such a heat exchanger, even a high-purity object to be processed can be cooled with high efficiency while minimizing contamination of impurities.

Further, in the above apparatus, a high-temperature fluid is passed through a gap between the cylindrical tube and the outer tube surrounding the cylindrical tube, so that a low-temperature workpiece is supplied from one end of the cylindrical tube, and the inside of the cylindrical tube is supplied. Can be heated while rolling, and can be discharged substantially continuously from the other end.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an object to be subjected to heat exchange is supplied from one end of a cylindrical tube. The object is rolled by the rotation of the cylindrical tube, and easily moves from the supply end to the other end. The cylindrical tube is covered with a cylindrical outer cylinder. Further, since the heat transfer coefficient between the rolling object and the inner surface of the cylindrical tube is extremely large, the heat transfer area required for exchanging heat energy is small, and the construction cost of the apparatus is small.

Hereinafter, the present invention will be described in detail with reference to FIGS. <First Embodiment> FIG. 1 is a side view showing an overall view of an example of a heat exchange device of the present invention. FIG. 2 is a sectional view taken along line XX ′ in FIG. FIG. 3 is a sectional view taken along the line YY 'in FIG.

As shown in FIG. 1, a cylindrical tube 1 is fixed by two or more support portions 2 at two or more positions. An outer cylinder 3 is disposed so as to surround the outer periphery of the cylindrical tube 1,
The cooling gas flows through a gap surrounded by the outer circumference of the cylindrical tube 1 and the outer cylinder 3 made of a heat-resistant and heat-insulating material.
Unlike the device shown in FIG. 4, in the present invention, the outer cylinder has a configuration independent of the cylindrical tube. In other words, the driving force for rotating the cylindrical tube is not transmitted from the outside via the outer tube surrounding the cylindrical tube via the gap through which the fluid for heat exchange passes, so that the outer tube is This means that there is no need to rotate in conjunction with the cylindrical tube. Therefore, the outer tube does not need to be connected to the cylindrical tube, does not require a displacement absorbing / adjusting mechanism, a driving force transmission device, a non-slip, etc. as shown in FIG. 4, and the gap between the cylindrical tube and the outer tube is heat. Since the setting can be made in consideration of the exchange efficiency, the whole apparatus becomes very compact, and there is no limit to the choice of materials for these members in order to prevent contamination. Retaining the outer cylinder can be easily achieved, for example, by fixing it on the base of the device.

The support 2 supports the cylindrical tube and is installed on the rotary transmission 4. Cylindrical tube 1 and support 2
The rotation transmission mechanism from the rotation transmission device 4 to the support 2
In order to transmit the rotation to, it is engaged with a general transmission mechanism such as a gear. The rotation transmission device 4 is connected by a coaxial shaft 5 so that the respective support portions 2 can be driven synchronously, and the coaxial shaft 5 and the rotation transmission device 4 are connected via a chain 6 to an electric motor 7 as rotation driving means. I have. In addition,
The end of the cylindrical tube may have a squeezed shape as shown at 8 in FIG. 1 and a part 22 made of a plate as shown in FIG.
May be used, and the shape is arbitrary.

Reference numeral 12 denotes a central axis, which may be horizontal or inclined with respect to the horizontal, and rotates about the central axis 12 integrally with the cylindrical tube 1 by applying a rotational driving force to the support 2.
The high-temperature granular material to be processed is substantially continuously fed from the inlet 13 formed by one end of the cylindrical tube 1, moves in the direction of the other end while rolling in the cylindrical tube 1, and cools. Then, the paper is discharged from the discharge port 14 to the outside of the apparatus.

The gas supplied to the space in the outer tube 3 exchanges heat with the cylindrical tube 1 to cool the cylindrical tube 1, and the object supplied into the cylindrical tube 1 exchanges heat with the cylindrical tube 1. Cooled. Therefore, the processing object supplied into the cylindrical tube 1 is indirectly cooled by the gas supplied into the outer tube 3, so that contamination can be prevented. The workpiece is conveyed from the supply side to the discharge side by the rotation of the cylindrical tube 1, and is cooled to a predetermined temperature during that time. On the other hand, the low temperature gas is in duct 1
5 and enters the inner surface of the outer tube 3 and cools the cylindrical tube 1 through an annular passage 17 which is a gap formed between the outer surface of the cylindrical tube 1 and the inner surface of the outer tube 3. That is, the heat is cooled in a state in which the flow is substantially countercurrent to the flow of the processing object, and the heat energy is recovered. The gas becomes high temperature and is introduced into another duct 16.

The axial movement of the supporting portion 2 caused by the thermal expansion of the cylindrical tube 1 caused by the supply of a high-temperature treated material or the like is caused by slipping on the gear contact surface of the rotary transmission 4. You can escape. By the way, the details of the support portion 2 for supporting and fixing the cylindrical tube 1 are divided into four parts in the circumferential direction as shown in FIG. 2, and the radial direction is adjusted so that the fixing strength of the cylindrical tube 1 and the centering of the rotary tube can be adjusted. It has an adjustment mechanism 9 that can adjust the distance. In addition, a filler 11 such as a ceramic fiber is attached to a gap between the support rod 10 and the cylindrical tube 1.

These divided support portions can be intermittently arranged at appropriate intervals according to the cooling conditions, the mechanical strength of the cylindrical tube, and the like. This facilitates free movement of the support portion during thermal expansion of the cylindrical tube, and facilitates adjustment of the support interval. The presence or absence of the intermittent and the degree of the intermittent may be appropriately selected depending on the purpose. The material of the cylindrical tube 1 is 1000 to 1400 ° C. in terms of heat resistance to the temperature of the object to be processed.
Under high temperature conditions, ceramic material
Under a low temperature condition of 0 ° C. or less, a heat-resistant metal may be used. In particular, high-purity ceramics and the like can be selected under conditions where there is a problem of contamination of the product due to abrasion due to an object to be processed or a chemical reaction.

Particularly preferred materials include high-purity and high-density ceramic materials. The use of such a material is preferable because contamination can be prevented even with respect to an object to be processed which requires particularly high purity. As high-purity and high-density ceramics, high-purity ceramics may be used as long as contamination to the object does not substantially cause a problem. It suffices if the density is high enough not to cause a problem in quality due to the generation of an object. The use of a desired high-purity material and a common material is also a more desirable embodiment. Specific examples include, but are not limited to, alumina crystals having a purity of 99.5% or more, zirconia crystals, silicon carbide, silicon nitride, high-purity quartz glass, and the like. In any case, it may be appropriately selected according to the purpose and use conditions.

The object to be treated can be used without any particular limitation as long as it is a powder or a granular material such as a powder or a granular material that can be processed in a cylindrical furnace tube, and these can be used with the heat exchanger of the present invention. By carrying out the treatment, a high-purity granular material, which is a granular high-purity material without contamination, can be produced very efficiently. The powdery high-purity material is not particularly limited, but specifically, for example, a ceramic material such as a barium titanate-based dielectric material, a zirconate titanate-based piezoelectric material, or a high-purity glass material such as quartz glass powder. And the like, such as powder and granules.

The fluid used for heat exchange is usually preferably a gas typified by air because of its easy handling, but may be appropriately selected depending on the type of the object to be treated and the processing temperature. <Second Embodiment> FIGS. 1 to 3 show a cooling medium flow path having a simple annular cross section. However, the cooling medium flow path in the present invention is not limited to this. As shown in FIG. 6, a plurality of heat- and heat-insulating baffle plates 19 substantially perpendicular to the central axis are provided to improve heat transfer between the cooling medium and the outer surface of the cylindrical tube. Can be. 6A and 6B respectively show XX ′ and Y in FIG.
It shows a cross section perpendicular to the central axis at the position of -Y '. At this time, the shape and number of baffles are arbitrary, and are not necessarily limited to those shown in FIGS. <Third Embodiment> Further, as a method of exchanging heat between the cooling medium and the rotary cylindrical tube 1, a baffle 19 can be spirally arranged as shown in FIGS. As shown in FIG. 8, the helix is coaxial with the cylindrical tube. FIG. 7 is a sectional view perpendicular to the center axis 12 of rotation, and FIG. 8 is a sectional view of the outer cylinder 3. The cooling medium introduced from the duct 15 is spirally wound around the rotary cylindrical tube 1 by the baffle 19 disposed on the inner surface of the outer cylinder 3 to cool the rotary cylindrical tube 1, and then discharged from the duct 16. Although any direction can be adopted as the rotation direction of the cooling medium, it is preferable that the rotation direction is opposite to the rotation direction of the rotary cylindrical tube 1 from the viewpoint of heat conduction. The number of spiral turns and the size of the flow path can be arbitrarily selected.

[0023]

As described above, the object to be processed, which requires high purity, can be continuously and efficiently cooled by the heat exchanger of the present invention. In particular, in the heat exchange device of the present invention in which the support portion is divided, even if the operating temperature is large or the temperature is high, the interval between the support portions intermittently arranged in the axial direction to support and fix the cylindrical tube is arbitrary. Therefore, it is possible to realize a cooling device having a structure capable of sufficiently securing the mechanical strength of the cylindrical tube with respect to the load and the own weight of the object to be processed in the cylindrical tube. It is useful for upsizing. In addition, since the heat transfer coefficient between the rolling workpiece and the inner surface of the cylindrical tube is extremely large, it is possible to cool the high-temperature workpiece in an order of magnitude shorter than in the related art. Not only that, the energy possessed can be effectively recovered. Furthermore, since there is no inclusion such as a protective tube that reduces the efficiency of heat conduction in the gap between the cylindrical rotating tube and the cooling medium, the device is excellent in heat conductivity and temperature controllability and extremely industrially useful.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the overall structure of a heat exchange device according to a first embodiment.

FIG. 2 is a sectional view taken along the line X-X 'in FIG.

FIG. 3 is a sectional view taken along the line Y-Y 'in FIG.

FIG. 4 is a cross-sectional view showing the entire structure of an example of a double-tube cooling device.

FIG. 5 is a vertical sectional view including a central axis of a heat exchange device according to a second embodiment.

6 is a sectional view perpendicular to the central axis of FIG.

FIG. 7 is a vertical sectional view including a central axis of a heat exchange device according to a third embodiment.

8 is a sectional view taken along the central axis in FIG.

FIG. 9 is a cross-sectional view of the shape near the outlet of the workpiece in the heat exchange device shown in FIG.

FIG. 10 is a cross-sectional view showing the structure of a great cooling device according to the related art.

FIG. 11 is a cross-sectional view showing the structure of a conventional shaft-type cooling device.

FIG. 12 is a sectional view showing the structure of a rotary cooling device according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical pipe 2 Support part 3 Outer cylinder 4 Rotary transmission device 5 Coaxial shaft 6 Chain 7 Electric motor 8 Cylindrical tube end part 9 Adjusting mechanism 10 Support rod 11 Filling 12 Center shaft 13 Inlet 14 Outlet 15 Duct 16 Duct 17 Cooling fluid flow Passage 18 Workpiece 19 Baffle 20 Cooling fluid flow direction 21 Cylindrical pipe outlet end 22 End part 31 Protective tube 32 Non-slip 33 Gap 41 Rotary kiln 42 Cooling device main body 43 Oscillating grid 44 Cooling air 45 Flow of work 46 Cooling air flow

Claims (8)

[Claims] 1. A cylindrical tube capable of moving an object to be processed inside from one end to the other end while rotating about a central axis, and an outer tube surrounding the cylindrical tube and independent of the cylindrical tube. And a heat exchange device capable of performing heat exchange with the object to be processed through a fluid in a gap between the outer cylinder and the cylindrical tube. 2. The heat exchange device according to claim 1, wherein the gap between the outer tube and the cylindrical tube forms a spiral coaxial with the cylindrical tube. 3. The heat exchange device according to claim 1, wherein a baffle plate is provided in a gap between the outer cylinder and the cylindrical tube. 4. The cylindrical tube is made of an inorganic material.
4. The heat exchange device according to any one of 3. 5. The heat exchanger according to claim 4, wherein the material of the cylindrical tube is quartz. 6. A cylindrical tube is rotated by applying a driving force from the outside of the cylindrical tube while introducing powdery material into the cylindrical tube from one end of the cylindrical tube surrounded by the outer tube via the gap, and passing fluid through the gap. What is claimed is: 1. A method for heating a granular material, comprising exchanging heat with the granular material and heating the granular material, wherein the outer cylinder is independent of the cylindrical tube. 7. A cylindrical tube is rotated by applying a driving force from the outside of the cylindrical tube while introducing powder and granules into the cylindrical tube from one end of the cylindrical tube surrounded by the outer cylinder via the gap, and passing the fluid through the gap. A method for cooling a granular material, wherein heat is exchanged with the granular material to cool the granular material, wherein the outer cylinder is independent of the cylindrical tube. 8. A cylindrical pipe is rotated by applying a driving force from outside the cylindrical pipe while introducing powder and granules into the cylindrical pipe from one end of the cylindrical pipe surrounded by the outer cylinder via the gap, and passing fluid through the gap. A method for producing a high-purity granular material for cooling a granular material, wherein the outer cylinder is independent of the cylindrical tube.