JP7712822B2 - Honeycomb structure, its manufacturing method, and honeycomb structure arrangement - Google Patents

Description

The present invention relates to a honeycomb structure that is placed inside a radiant tube as a heat transfer promoter or heat storage body, a manufacturing method thereof, and an arrangement structure for the honeycomb structure.

A radiant tube heater is a device that heats a metal or ceramic tube (radiant tube) by circulating gas heated by a burner or other device inside the tube, and indirectly heats the object to be heated by the radiant heat from the heated tube.

However, when heated gas (hereafter referred to as "heated gas") flows through the tube, frictional resistance occurs near the inner wall surface of the tube, making it difficult for the gas to flow, so the heated gas tends to flow near the center of the tube and heat is not easily transferred to the tube. In addition, the temperature of the heated gas flowing near the inner wall surface of the tube decreases due to heat exchange with the inner wall surface. For this reason, there is a problem in that the tube cannot be heated sufficiently as the distance from a heating source such as a burner increases.

For this reason, a heat transfer promoter has traditionally been placed inside the radiant tube at a position away from the heat source. The heat from the heated gas flowing inside the tube is collected by the heat transfer promoter, and the heat is transferred from the heat transfer promoter to the tube, facilitating the transfer of heat from the heated gas to the radiant tube.

The applicant has proposed to use, as such a heat transfer promoter, a honeycomb structure having a plurality of cells separated by partition walls arranged in a row extending in a single direction (see Patent Documents 1 and 2). A honeycomb structure has a large surface area and a large area in contact with the heated gas, so it can efficiently recover the heat of the heated gas and has the advantage of having a large area for radiating heat toward the inner wall surface of the tube.

In addition, the honeycomb structures of Patent Documents 1 and 2 have a structure that makes it easier to radiate heat toward the inner wall surface of the tube. Specifically, the honeycomb structure of Patent Document 1 has at least one of its end faces inclined with respect to a plane perpendicular to the axial direction of the tube, so that heat radiated from the end face can be efficiently transferred to the tube. The honeycomb structure of Patent Document 2 is a honeycomb structure in which multiple segments having a honeycomb structure are joined together, and the segments are joined so that the cell axes of two or more segments extend in different directions. With this configuration, gas that has passed through the honeycomb structure flows in different directions within the tube, which can cause turbulence in the gas flow and allow gas to flow near the inner wall surface of the tube where gas has difficulty flowing due to frictional resistance, and the heat of the heated gas can be efficiently transferred to the radiant tube.

However, while the honeycomb structures in Patent Documents 1 and 2 can efficiently transfer heat from the heated gas to the tubes, they have a complex structure and are difficult to manufacture, leaving room for improvement.

On the other hand, there is also a regenerative type of radiant tube heater. This heater switches the gas flow direction at a specified time interval so that gas flows through the same heat exchange section alternately when hot gas is discharged due to burner combustion and when new gas is supplied for burner combustion. A heat storage body is placed inside the heat exchange section, and the heat of the heated gas that is discharged is recovered by the heat storage body, and this heat is used to preheat the new gas that is supplied for burner combustion. Such regenerative radiant tube heaters come in two types: one that uses a pair of burners each combined with a heat exchange section, and one that switches the gas flow direction with a single burner.

While solid balls are used as the heat storage body of a regenerative radiant tube heater, honeycomb structures are sometimes used (see Patent Document 3). However, as mentioned above, frictional resistance occurs near the inner wall surface of the tube, making it difficult for gas to flow, so the gas tends to flow near the center of the tube, and the heated gas that has flowed near the center tends to continue straight and pass only near the center of the honeycomb structure. As a result, only the center of the honeycomb structure is partially used as a heat storage body, and there is a problem that the advantage of the honeycomb structure, that is, its very large specific surface area, cannot be fully utilized. Therefore, there has been a demand for a honeycomb structure that is highly effective as a heat storage body without making the structure complicated.

Patent No. 6652313 Patent No. 6470571 JP 2021-071242 A

In view of the above, the present invention aims to provide a honeycomb structure that is placed inside a radiant tube and has a simple structure yet is highly effective as a heat transfer promoter or heat storage material, a method for manufacturing the honeycomb structure, and an arrangement structure for the honeycomb structure.

In order to solve the above problems, the honeycomb structure according to the present invention comprises:
"A ceramic honeycomb structure having a plurality of cells separated by partition walls arranged in a row extending in a single direction , the honeycomb structure being intended to be disposed as a heat transfer promoter or heat storage body within the tube of a radiant tube heater ,
The honeycomb structure has a through hole passing through the honeycomb structure in parallel to a cell axis, which is a direction in which the cells extend,
The through hole is
A circular hole having an opening area in a cross section perpendicular to the cell axis that is larger than the opening area of the plurality of cells,
The center of the opening is located at an outer edge portion whose distance from the center point of the cross section is equal to or greater than half the distance between the center point and the outer periphery,
The cross section of the partition wall is exposed in the internal space of the through hole, and the cell is open in the internal space.

The honeycomb structure of this configuration has through holes that run parallel to the cell axis. The opening area of the through holes in cross section is larger than the opening area of the cells, so when the honeycomb structure is placed inside a tube through which heated gas flows, the gas flows through the cells and preferentially flows through the through holes. The opening center of the through holes is located at the outer edge in cross section. Therefore, the heated gas flows preferentially through the outer edge of the honeycomb structure.

Therefore, when a honeycomb structure is placed inside a radiant tube as a heat transfer promoter, the heated gas easily flows through the through holes in the outer edge, and the heat of the heated gas is effectively recovered at the outer edge of the honeycomb structure. In the honeycomb structure, the outer edge close to the inner wall surface of the tube is effectively heated, so that the heat recovered from the heated gas can be effectively transferred to the tube. On the other hand, when a honeycomb structure is placed inside a heat storage radiant tube as a heat storage body, the heated gas easily flows through the through holes in the outer edge, and the heat of the heated gas is effectively recovered at the outer edge of the honeycomb structure. As a result, a large amount of heat can be stored even at the outer edge, where gas could not fully function as a heat storage body in conventional honeycomb structures due to the difficulty in passing through the outer edge, and the honeycomb structure can function as a heat storage body overall.

In addition, in the honeycomb structure of this configuration, the cross section of the partition wall is exposed in the internal space of the through hole, and the cells are open. In this configuration, the inner surface of the cell and the cross section of the partition wall form the inner peripheral surface of the through hole, and the surface area is extremely large. Therefore, the contact area between the heated gas flowing through the through hole and the honeycomb structure is extremely large, and the heat of the heated gas can be sufficiently recovered.

The honeycomb structure having the above-mentioned configuration can be manufactured by the following manufacturing method.
"By subjecting a ceramic raw material to a process of extrusion molding, a honeycomb-structured molded body is formed having a plurality of cells separated by partition walls arranged in a row extending in a single direction,
Before or after firing the molded body, through-holes are formed by hollowing out the molded body so as to penetrate the molded body in a direction parallel to a cell axis, which is the extension direction of the cells;
The through hole ,
The opening area in a cross section perpendicular to the cell axis is a circular hole larger than the opening area of the plurality of cells,
The center of the opening is formed to be located at an outer edge portion whose distance from the center point of the cross section is equal to or greater than half the distance between the center point and the outer periphery ,
This is a manufacturing method for manufacturing a honeycomb structure to be placed inside the tube of a radiant tube heater as a heat transfer promoter or heat storage body .

When extrusion molding a ceramic honeycomb structure, a mold corresponding to the cross-sectional shape is manufactured, and the ceramic raw material mixture is extruded from this mold. Therefore, when manufacturing a honeycomb structure having through holes that penetrate in a direction parallel to the cell axis, it is conceivable to provide a hole-shaped portion for forming the through holes in the extrusion mold. In that case, however, the inner surface of the through holes formed by extrusion molding is the same as the inner surface of a cylinder, and the surface area is not large. In contrast, in this manufacturing method, after forming a molded body having a honeycomb structure by extrusion molding, the through holes are formed by hollowing out before or after firing the molded body. Therefore, the partition walls that divide the cells are partially cut off, and the cross sections of the partition walls are exposed in the internal space of the through holes, and the cells are opened in the internal space, and a honeycomb structure having an extremely large contact area with the heated gas flowing through the through holes can be manufactured.

In addition, because the through holes are formed by hollowing out a honeycomb-structured molded body or fired body, it is possible to easily manufacture a honeycomb structure that has a simple structure but is highly effective as a heat transfer promoter or heat storage body.

The honeycomb structure according to the present invention has the following structure instead of the above structure:
"A ceramic honeycomb structure having a plurality of cells separated by partition walls arranged in a row extending in a single direction , the honeycomb structure being intended to be disposed as a heat transfer promoter or heat storage body within the tube of a radiant tube heater ,
A through groove is provided that passes through the honeycomb structure in a direction parallel to a cell axis, which is a direction in which the cells extend.
The through groove is
The groove is an arc-shaped groove having an opening area in a cross section perpendicular to the cell axis that is larger than the opening area of the plurality of cells,
The cross-section is open at its periphery,
A cross section of the partition wall is exposed in the inner space of the through groove, and the cell is open in the inner space.

The honeycomb structure of this configuration has through grooves that run parallel to the cell axis. The opening area of the through grooves in cross section is larger than the opening area of the cells, so when the honeycomb structure is placed inside a tube through which heated gas flows, the gas flows through the cells and preferentially flows through the through grooves. And because the through grooves open on the outer periphery in cross section, the heated gas preferentially flows through the outer periphery of the honeycomb structure.

Therefore, when a honeycomb structure is placed inside a radiant tube as a heat transfer promoter, the heated gas easily flows through the through grooves on the outer periphery, and the heat of the heated gas is effectively recovered near the outer periphery of the honeycomb structure. By effectively heating the outer periphery near the inner wall surface of the tube in the honeycomb structure, the heat recovered from the heated gas can be effectively transferred to the tube.

On the other hand, even when a honeycomb structure is placed inside a heat storage radiant tube as a heat storage body, the heated gas easily flows through the through grooves on the outer periphery, and the heat of the heated gas is well recovered near the outer periphery of the honeycomb structure. This makes it possible to store a large amount of heat even near the outer periphery, where conventional honeycomb structures were unable to fully function as a heat storage body due to the difficulty in passing gas, and allows the honeycomb structure to function as a heat storage body overall.

In addition, in the honeycomb structure of this configuration, the cross section of the partition wall is exposed in the inner space of the through groove, and the cells are open. In this configuration, the inner surface of the cell and the cross section of the partition wall form the inner surface of the through groove, and the surface area is extremely large. Therefore, the contact area between the heated gas flowing through the through groove and the honeycomb structure is extremely large, and the heat of the heated gas can be sufficiently recovered.

Furthermore, when a honeycomb structure is used as a heat transfer promoter, the outer peripheral surface is the surface that radiates heat toward the inner wall surface of the tube, but because the surface area of the inner surface of the through groove that opens on the outer periphery is extremely large, the area that radiates heat toward the inner wall surface of the tube is also extremely large, which has the advantage of transmitting a large amount of heat to the tube.

The honeycomb structure having the above-mentioned through grooves can be manufactured by the following manufacturing method.
"By subjecting a ceramic raw material to a process of extrusion molding, a honeycomb-structured molded body is formed having a plurality of cells separated by partition walls arranged in a row extending in a single direction,
Before or after firing the molded body, a through groove is formed by hollowing out the molded body so as to penetrate the molded body in a direction parallel to a cell axis, which is the extension direction of the cells;
The through groove ,
The groove is an arc-shaped groove having an opening area in a cross section perpendicular to the cell axis that is larger than the opening area of the plurality of cells,
By forming the cross section so as to open at the outer periphery,
This is a manufacturing method for manufacturing a honeycomb structure to be placed inside the tube of a radiant tube heater as a heat transfer promoter or heat storage body .

In this manufacturing method, rather than providing a cutout portion in the extrusion mold for forming the through grooves, a molded body having a honeycomb structure is formed by extrusion molding, and then the through grooves are formed by hollowing out the molded body before or after it is fired. As a result, the partition walls that separate the cells are partially cut away, exposing the cross section of the partition walls in the inner space of the through grooves, and the cells are open in the inner space, making it possible to manufacture a honeycomb structure with an extremely large contact area with the heated gas flowing through the through grooves.

In addition, since the through grooves are formed by hollowing out a honeycomb-structured molded body or fired body, it is possible to easily manufacture a honeycomb structure that has a simple structure but has a high function as a heat transfer promoter or heat storage body.

In addition to the above configuration, the honeycomb structure having the through holes or through grooves has the following features:
The honeycomb structure may be configured as follows: "The honeycomb structure is formed by joining a plurality of segments having a honeycomb structure including a plurality of cells separated by partition walls arranged in a row extending in a single direction."

In this configuration, the honeycomb structure is formed by joining multiple segments, which allows for a high degree of freedom in the size of the honeycomb structure.

The honeycomb structure having such a configuration is manufactured by the following manufacturing method.
"The molded body is a molded body of a segment having a honeycomb structure including a plurality of cells divided by partition walls arranged in a row extending in a single direction,
The manufacturing method is such that a plurality of the segments are joined together before or after the compact is sintered.

It does not matter which order the "formation of through holes or through grooves" is before or after firing the molded body, and the "joining of segments" is before or after firing the molded body. In other words, the molded body of the segment may be fired and then the through holes or through grooves may be formed before joining, or the segments may be joined and then the through holes or through grooves may be formed. Alternatively, the molded body of the segment may be formed with through holes or through grooves, fired and then joined, or joined and then fired. Alternatively, the molded body of the segment may be joined and then fired, and then the through holes or through grooves may be formed, or the through holes or through grooves may be formed and then fired.

Next, the arrangement structure of the honeycomb structure according to the present invention is as follows:
"The honeycomb structure described above is disposed within the tube of a radiant tube heater as a heat transfer promoter or heat storage body."

Since the honeycomb structure has through holes on the outer edge, or through grooves on the outer periphery, or both, when it is placed inside a radiant tube as a heat transfer promoter, it is easy to transfer heat from the heated gas to the tube, as described above. Also, when it is placed inside a radiant tube as a heat storage body, the honeycomb structure as a whole can function as a heat storage body, as described above.

As described above, according to the present invention, it is possible to provide a honeycomb structure that is placed inside a radiant tube and has a simple structure yet is highly effective as a heat transfer promoter or heat storage material, a method for manufacturing the honeycomb structure, and an arrangement structure for the honeycomb structure.

FIG. 1(a) is a plan view of a honeycomb structure 1 according to one embodiment of the present invention, FIG. 1(b) is an explanatory diagram of the outer edge portion, and FIG. 1(c) is a perspective view of the honeycomb structure 1 cut along line AA. FIG. 2(a) is a plan view of a honeycomb structure 1b according to another embodiment, and FIG. 2(b) is a perspective view of the honeycomb structure 1b cut along line BB. FIG. 10 is a plan view of a honeycomb structure 1c according to another embodiment. FIG. 4(a) is a plan view of a honeycomb structure 1d according to another embodiment, and FIG. 4(b) is a perspective view of the honeycomb structure 1d. FIG. 5(a) is a plan view of a honeycomb structure 1e according to another embodiment, and FIG. 5(b) is a plan view of a honeycomb structure 1f according to another embodiment.

The following describes a honeycomb structure, which is a specific embodiment of the present invention, and a method for manufacturing the same, with reference to the drawings. The honeycomb structure of this embodiment is intended to form an arrangement in which a honeycomb structure is arranged as a heat transfer promoter or heat storage body within the tube of a radiant tube heater.

The honeycomb structure of this embodiment is manufactured by a manufacturing method including a "molding" process, at least one of a "through hole forming" process and a "through groove forming" process, and a "firing" process. In addition, the manufacturing method may include a "bonding" process as an optional process.

In the "molding" process, the mixture of ceramic raw materials with water and binder is extruded from a mold to form a molded body with a honeycomb structure. The outer shape of the molded body can be cylindrical, elliptical cylindrical, or rectangular. The cross-sectional shape of the cells can be polygonal, such as a square, triangle, or hexagon.

The ceramic material is not particularly limited, and examples include silicon carbide, alumina, cordierite, and mullite. Silicon carbide has high thermal conductivity, making it suitable for use as a heat transfer promoter. In addition to its high thermal conductivity, silicon carbide also has a small thermal expansion coefficient, making it excellent in thermal shock resistance, making it suitable for use as a heat storage material that is repeatedly heated and cooled.

In the "firing" process, the ceramic particles are sintered by heating for a specified period of time at a temperature lower than the melting point. Oxide ceramics such as alumina, cordierite, and mullite are fired in an oxidizing atmosphere, while non-oxide ceramics such as silicon carbide are fired in a non-oxidizing atmosphere such as a nitrogen gas atmosphere, an inert gas atmosphere, or a mixture of these.

The "bonding" step is a step of bonding a plurality of segments with a bonding material, and is carried out after the molding step and before or after the firing step, similar to the "through hole forming" step and the "through groove forming" step described later in detail. Regardless of the order of the "bonding" step, the "through hole forming" step, and the "through groove forming" step, each step can be carried out in the following order:
(1) "Molding" → "Firing" → "Forming through holes and through grooves" → "Joining"
(2) "Molding" → "Firing" → "Joining" → "Forming through holes and through grooves"
(3) "Molding" → "Forming through holes and through grooves" → "Firing" → "Joining"
(4) "Molding" → "Forming through holes and through grooves" → "Joining" → "Firing"
(5) "Molding" → "Joining" → "Firing" → "Forming through holes and through grooves"
(6) "Molding" → "Joining" → "Forming through holes and through grooves" → "Firing"

The process sequence (1) to (3) is suitable for cases where the bonding process is performed after the firing process, and therefore the bonding material layer is required to relieve thermal stress. In such cases, a bonding material that is a mixture of ceramic powder, inorganic fibers, and a binder (an inorganic binder such as colloidal silica and/or an organic binder such as carboxymethyl cellulose) can be used.

On the other hand, in the process sequence of (4) to (6), since the firing process is carried out after the bonding process, a bonding material that can be fired under the same conditions as the honeycomb structure formed body is used. For example, as in the technology proposed by the present applicant in Patent No. 5180942, a bonding material that becomes a ceramic sintered body by firing and is integrated with the honeycomb structure segment by sintering can be used.

The "through hole forming" process and the "through groove forming" process are carried out after the molding process and before or after the firing process, and are processes in which a honeycomb-structured molded body or sintered body is hollowed out so as to penetrate parallel to the cell axis. Hollowing out partially cuts out the partition walls that separate the cells. If the partition walls are hollowed out so that they do not reach the outer peripheral wall, through holes are formed. On the other hand, if the partition walls are hollowed out so that they reach the outer peripheral wall, through grooves that open on the outer periphery are formed.

For example, as shown in FIG. 1(a), when a honeycomb structure formed body or fired body having a honeycomb structure with a plurality of cells 15 divided by partition walls 11 arranged in a row extending in a single direction is hollowed out so that the partition walls 11 are not cut out to reach the outer wall 13, a through hole 21 is formed. At this time, as shown in FIGS. 1(a) and 1(b), the through hole 21 is formed so that the opening center P of the through hole 21 is located at the outer edge portion 10p in the cross section (cross section perpendicular to the cell axis). The outer edge portion 10p is the range in the cross section where the distance from the center point C is half or more of the distance R between the center point C and the outer periphery (hatched portion in FIG. 1(b)). Here, the line that is R/2 away from the center point C in the cross section is indicated by L.

The size of the through holes 21 is set so that the opening area of each through hole 21 in the cross section is larger than the opening area of each cell 15. Here, an example is shown in which four through holes 21 are formed at equal angular intervals relative to the central axis in a cylindrical molded body or fired body.

In the internal space of the through hole 21 formed by hollowing out, as shown in FIG. 1(c), the cross section of the partition wall 11 is exposed and the cell 15 is open.

When a honeycomb structure 1 having the above configuration is placed inside a radiant tube as a heat transfer promoter, the heated gas easily flows through the through holes 21 in the outer edge portion 10p, and the heat of the heated gas is effectively recovered at the outer edge portion 10p of the honeycomb structure 1. By effectively heating the outer edge portion 10p close to the inner wall surface of the tube in the honeycomb structure 1, the heat recovered from the heated gas can be effectively transferred to the tube.

On the other hand, even when the honeycomb structure 1 is placed inside a radiant tube as a heat storage body, the heated gas easily flows through the through holes 21 in the outer edge portion 10p, and the heat of the heated gas is well recovered at the outer edge portion 10p of the honeycomb structure 1. As a result, in conventional honeycomb structures, the outer edge portion 10p, which was not able to fully function as a heat storage body because gas did not easily flow there, can store a large amount of heat, and the honeycomb structure 1 can function as a heat storage body as a whole.

In addition, in the honeycomb structure 1, the cross section of the partition wall 11 is exposed in the internal space of the through hole 21, and the cells 15 are open, so that the surface area is extremely large. Therefore, the contact area between the heated gas flowing through the through hole 21 and the honeycomb structure 1 is extremely large, and the heat of the heated gas can be sufficiently recovered.

In the honeycomb structure 1, the opening center P of the through hole 21 is located at the outer edge 10p, but the inside of the through hole 21 slightly overlaps the line L. In other words, in this example, a part of the through hole 21 is located inside the outer edge 10p. In contrast, as shown in Figures 2(a) and (b), a honeycomb structure 1b can be made in which the entire through hole 21 is located at the outer edge 10p. Here, an example is shown in which eight through holes 21 are formed at equal angular intervals relative to the central axis in a cylindrical molded body or fired body. Even with this configuration, the same effects as those of the honeycomb structure 1 are achieved.

The number of through holes 21 per honeycomb structure is not limited to the number exemplified for honeycomb structures 1 and 1b. In addition, although honeycomb structures 1 and 1b are integral, a honeycomb structure manufactured through the above-mentioned bonding process as an optional process can have through holes 21. As an example, FIG. 3 shows honeycomb structure 1c, which has a cylindrical outer shape like honeycomb structure 1b and has eight through holes 21 formed at equal angular intervals relative to the central axis.

Honeycomb structure 1c is made by joining multiple rectangular pillar-shaped segments 30 having a honeycomb structure with a joining material 33, and then processing the outer shape into a cylindrical shape. Even with this configuration, it exhibits the same effects as honeycomb structures 1 and 1b. In addition, because it is a body of multiple segments 30 joined together, it has the advantage of having a high degree of freedom in size.

Above, honeycomb structures 1, 1b, and 1c with through holes 21 were shown, and next, a honeycomb structure with through grooves will be shown. A honeycomb structure with through grooves may be a one-piece structure or a jointed body formed by joining segments. As an example, Figs. 4(a) and (b) show a honeycomb structure 1d, which is a jointed body of multiple segments 30 and has through grooves 22. When a honeycomb structure molded body or fired body having multiple cells 15 divided by partition walls 11 arranged in a row extending in a single direction is hollowed out so that the cutting of the partition walls reaches the outer wall 13, through grooves 22 that open on the outer periphery are formed. The size of the through grooves 22 is set so that the opening area of one through groove 22 in the cross section is larger than the opening area of one cell 15.

In the inner space of the through groove 22 formed by hollowing out, as shown in FIG. 4(b), the cross section of the partition wall 11 is exposed and the cells 15 are open. Here, a case is shown in which multiple rectangular columnar segments 30 having a honeycomb structure are joined with a joining material 33 and processed into a cylindrical shape, and eight through grooves 22 are formed at equal angular intervals relative to the central axis, but the number is not particularly limited.

The honeycomb structure 1d configured in this way has through grooves 22 that run parallel to the cell axis, and the opening area of the through grooves 22 in cross section is larger than the opening area of the cells 15, so when the honeycomb structure is placed in a tube through which heated gas flows, the gas flows through the cells and preferentially flows through the through grooves 22. And, because the through grooves 22 open on the outer periphery in cross section, the heated gas preferentially flows through the outer periphery of the honeycomb structure 1d.

Therefore, when a honeycomb structure 1d is placed inside a radiant tube as a heat transfer promoter, the heated gas easily flows through the through grooves 22 on the outer periphery, and the heat of the heated gas is effectively recovered near the outer periphery of the honeycomb structure 1d. By effectively heating the outer periphery near the inner wall surface of the tube in the honeycomb structure 1d, the heat recovered from the heated gas can be effectively transferred to the tube.

On the other hand, when the honeycomb structure 1d is placed in a heat storage radiant tube as a heat storage body, the heated gas easily flows through the through grooves 22 on the outer periphery, and the heat of the heated gas is well recovered near the outer periphery of the honeycomb structure 1d. This makes it possible to store a large amount of heat even near the outer periphery, where the conventional honeycomb structure was not able to fully function as a heat storage body because gas did not easily flow, and allows the honeycomb structure 1d to function as a heat storage body overall.

In addition, in the honeycomb structure 1d, the cross section of the partition wall 11 is exposed in the inner space of the through groove 22, and the cells 15 are open, so that the surface area is extremely large. Therefore, the contact area between the heated gas flowing through the through groove 22 and the honeycomb structure 1d is extremely large, and the heat of the heated gas can be sufficiently recovered.

Furthermore, when the honeycomb structure 1d is used as a heat transfer promoter, the outer peripheral surface is the surface that radiates heat toward the inner wall surface of the tube, but because the surface area of the inner surface of the through groove 22 that opens on the outer periphery is extremely large, the area that radiates heat toward the inner wall surface of the tube is also extremely large, which has the advantage of transmitting a large amount of heat to the tube.

The present invention has been described above with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various improvements and design changes are possible without departing from the spirit of the present invention, as described below.

For example, it is possible to make a honeycomb structure having both through holes and through grooves. This results in a honeycomb structure that combines the function of a honeycomb structure having through holes 21, as exemplified using honeycomb structures 1, 1b, and 1c, and the function of a honeycomb structure having through grooves 22, as exemplified using honeycomb structure 1d.

Also, as in the honeycomb structures 1e and 1f shown in Figures 5(a) and 5(b), a structure can be constructed having through holes 25 that are not located at the outer edge. Here, the case is shown in which the opening center of the through hole 25 coincides with the center point of the cross section. A honeycomb structure having such a through hole 25 is suitable for use as a heat storage body of a heat storage type radiant tube heater. In a heat storage type radiant tube heater, the heat storage body is placed at the position where the burner is inserted, so that the inner tube with the burner inserted can be inserted into the central through hole 25.

Note that honeycomb structure 1e is an example that has through-grooves 22 that open on the outer periphery in addition to through-holes 25, and honeycomb structure 1f is an example that has through-holes 21 whose opening centers are located on the outer edge in addition to through-holes 25, and through-holes 21 of different sizes. Both are illustrated as a bonded body in which multiple segments 30 are bonded with bonding material 33, but they may be one piece.

A coating may also be applied to the outer surface of a honeycomb structure having at least one of through holes 21 and through grooves 22. Examples of coating agents include those intended to increase emissivity, those intended to increase strength, and those intended to suppress oxidation when the honeycomb structure is made of non-oxide ceramics. Such coating can be performed by applying or spraying the coating agent to the outer surface of the honeycomb structure. Alternatively, it can be performed by impregnating the honeycomb structure with the coating agent.

1, 1b, 1c, 1d, 1e, 1f Honeycomb structure 10p Outer edge portion 11 Partition wall 15 Cell 21 Through hole 22 Through groove 30 Segment 33 Bonding material C Center point (center point in cross section)
P: Center of opening (center of through hole opening)

Claims (7)

A ceramic honeycomb structure having a plurality of cells separated by partition walls arranged in a row extending in a single direction, the honeycomb structure being intended to be disposed as a heat transfer promoter or a heat storage body within a tube of a radiant tube heater ,
The honeycomb structure has a through hole passing through the honeycomb structure in parallel to a cell axis, which is a direction in which the cells extend,
The through hole is
A circular hole having an opening area in a cross section perpendicular to the cell axis that is larger than the opening area of the plurality of cells,
The center of the opening is located at an outer edge portion whose distance from the center point of the cross section is equal to or greater than half the distance between the center point and the outer periphery,
A honeycomb structure, characterized in that a cross section of each of the partition walls is exposed in an internal space of each of the through holes, and each of the cells is open in the internal space. A ceramic honeycomb structure having a plurality of cells separated by partition walls arranged in a row extending in a single direction, the honeycomb structure being intended to be disposed as a heat transfer promoter or a heat storage body within a tube of a radiant tube heater ,
A through groove is provided that passes through the honeycomb structure in a direction parallel to a cell axis, which is a direction in which the cells extend.
The through groove is
The groove is an arc-shaped groove having an opening area in a cross section perpendicular to the cell axis that is larger than the opening area of the plurality of cells,
The cross-section is open at its periphery,
A honeycomb structure, characterized in that a cross section of each of the partition walls is exposed in an inner space of each of the through grooves, and each of the cells is open in the inner space. The honeycomb structure according to claim 1 or claim 2, characterized in that the honeycomb structure is formed by joining a plurality of segments having a honeycomb structure including a plurality of cells separated by partition walls arranged in a row extending in a single direction. A molded body having a honeycomb structure including a plurality of cells separated by partition walls arranged in a row and extending in a single direction is formed through a process of extruding a ceramic raw material,
Before or after firing the molded body, through-holes are formed by hollowing out the molded body so as to penetrate the molded body in a direction parallel to a cell axis, which is the extension direction of the cells;
The through hole ,
The opening area in a cross section perpendicular to the cell axis is a circular hole larger than the opening area of the plurality of cells,
The center of the opening is formed to be located at an outer edge portion whose distance from the center point of the cross section is equal to or greater than half the distance between the center point and the outer periphery ,
Manufacture a honeycomb structure to be placed inside the tube of a radiant tube heater as a heat transfer promoter or heat storage body.
A method for manufacturing a honeycomb structure comprising the steps of: A molded body having a honeycomb structure including a plurality of cells separated by partition walls arranged in a row and extending in a single direction is formed through a process of extruding a ceramic raw material,
Before or after firing the molded body, a through groove is formed by hollowing out the molded body so as to penetrate the molded body in a direction parallel to a cell axis, which is the extension direction of the cells;
The through groove ,
The groove is an arc-shaped groove having an opening area in a cross section perpendicular to the cell axis that is larger than the opening area of the plurality of cells,
By forming the cross section so as to open at the outer periphery,
Manufacture a honeycomb structure to be placed inside the tube of a radiant tube heater as a heat transfer promoter or heat storage body.
A method for manufacturing a honeycomb structure comprising the steps of: the molded body is a molded body of a segment having a honeycomb structure including a plurality of cells partitioned by partition walls arranged in a row extending in a single direction,
6. The method for manufacturing a honeycomb structure according to claim 4, wherein a plurality of the segments are bonded together before or after the formed body is fired. 4. A honeycomb structure arrangement, comprising: a honeycomb structure according to claim 1, which is disposed in a tube of a radiant tube heater as a heat transfer promoter or a heat storage body.