JP2016125797A - Honeycomb structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a honeycomb structure capable of efficiently transmitting heat from heating fluid to a tube, by being arranged in the tube of a radiant tube heater.SOLUTION: A honeycomb structure 1 including a plurality of cells 21 sectioned by partition walls 20 extending in a single direction and arranged in a row is configured such that in a cross section orthogonal to an axial direction, cell density of a central part 10 is made larger than cell density of an outer peripheral part 11. Also, the honeycomb structure can be configured such that a plurality of segments having a honeycomb structure are connected to each other. In this case, the central part and the outer peripheral part are formed by a segment with single cell density.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a honeycomb structure disposed in a tube of a radiant tube heater.

  A radiant tube heater heats a tube by circulating a fluid such as air heated by a burner or the like in a metal or ceramic tube, and indirectly heats the object to be heated by radiant heat from the heated tube. Device. In general, the radiant tube heater is used in a heating furnace that controls the atmosphere in the furnace, such as a carburizing furnace that performs a carburizing process of an iron material or an annealing furnace that performs an annealing process.

  However, when heated fluid (hereinafter referred to as “heated fluid”) flows through the tube, the frictional resistance acts and hardly flows near the inner wall surface of the tube, so that the heated fluid easily flows near the center of the tube. , Heat is not easily transmitted to the tube. In addition, the temperature of the heating fluid that flows in the vicinity of the inner wall surface of the tube decreases due to heat exchange with the inner wall surface. For this reason, there existed a problem that the temperature of a tube fell as the distance from heating sources, such as a burner, became large.

  In order to solve this problem, proposals have been made to arrange a heat transfer promoting body for promoting heat transfer from a heated fluid to the tube (see Patent Documents 1 and 2). The heat transfer promoting body of Patent Document 1 has a cross-shaped cross section having four plate-like partitions made of lightweight refractory, and the axial direction of the heat transfer promoting body is parallel to the axial direction of the tube. Is to be arranged. The heat transfer promoting body of Patent Document 2 has a spiral guide vane formed of ceramics or the like, and is arranged with the axial direction of the spiral parallel to the axial direction of the tube.

  However, the heat transfer promoting bodies of Patent Document 1 and Patent Document 2 are not large in surface area. For this reason, the area which contacts the heating fluid is not large, and heat is not easily transmitted from the heating fluid to the heat transfer promoting body. Further, since the amount of heat radiated from the heat transfer promoting body to the tube depends on the surface area, it is difficult for heat to be transferred from the heat transfer promoting body to the tube.

  Thus, it has been proposed to use a honeycomb structure as a heat transfer promoting body (see Patent Document 3). Since the honeycomb structure has a large surface area, the area in contact with the heating fluid in the heat transfer promoting body of Patent Document 3 is larger than that of the heat transfer promoting body of Patent Document 1 and Patent Document 2. However, since the heating fluid tends to flow near the center of the tube as described above, the heating fluid easily flows through the central portion of the honeycomb structure even in the honeycomb structure disposed in the tube. For this reason, in the invention of Patent Document 3, the size of the surface area of the honeycomb structure cannot be fully utilized, and it cannot be said that the efficiency of heat transfer is high.

Japanese Utility Model Publication No. 63-173613 Japanese Patent Laid-Open No. 57-112694 JP 2013-19644 A

  Therefore, in view of the above situation, the present invention has an object to provide a honeycomb structure that can be efficiently transferred from a heating fluid to a tube by being arranged in the tube of a radiant tube heater. It is.

  In order to solve the above-described problems, a honeycomb structure according to the present invention has a structure in which a plurality of cells defined by partition walls arranged in a single axial direction and arranged in a tube of a radiant tube heater are arranged. The honeycomb structure is provided with a cell density in the central portion larger than that in the outer peripheral portion in the cross section orthogonal to the axial direction.

  The “tube” of the “radiant tube heater” has a configuration in which a heating fluid using a gas burner, an electric heater or the like as a heating source is circulated inside, and has various shapes such as a U shape, an L shape, a T shape, and a straight shape. It can be a shape. Furthermore, it is good also as a structure which provides a heat exchanger in the edge part by which the fluid is discharged | emitted, and preheats the fluid which flows in into a tube.

  The material of the “honeycomb structure” is preferably ceramics such as silicon carbide, alumina, mullite, cordierite and the like because it is exposed to a high temperature environment for a long time, and silicon carbide is particularly preferable because of its high thermal conductivity. In addition, the shape of the honeycomb structure is not particularly limited, and the outer shape can be a cylindrical shape or a polygonal column shape, and the cell cross-sectional shape can be a polygon such as a quadrangle, a triangle, a hexagon, or the like. .

  “The cell density in the central part is larger than the cell density in the outer periphery”, the honeycomb structure is extruded using a mold in which the cell density is distributed as such, and each cell density is a single size. A plurality of honeycomb structure segments having different cell densities can be joined together.

  Moreover, it can be set as the structure provided with an "intermediate part" whose cell density is smaller than a center part and larger than an outer periphery part between "center part" and "outer periphery part". In this case, the intermediate portion can be further formed of a plurality of portions having a cell density smaller on the outer peripheral portion side than on the central portion side.

  In the honeycomb structure of this configuration, since the cell density is larger in the center than in the outer periphery, the heating fluid is less likely to flow in the center than in the outer periphery. For this reason, the amount of the heating fluid flowing into the outer peripheral portion is increased, and the heating fluid that has been distributed in the center of the conventional honeycomb structure is distributed close to a uniform flow throughout the honeycomb structure. Can do. Thereby, the large surface area of the honeycomb structure is fully utilized, and the heat of the heating fluid can be efficiently transmitted to the tube.

  In addition to the above-described structure, the honeycomb structure according to the present invention is formed by joining a plurality of segments having a honeycomb structure including a plurality of cells partitioned by partition walls extending in a single direction. The central portion and the outer peripheral portion are each formed by the segments having a single cell density.

  The shape of the “segment” is not particularly limited, and may be an outer shape of a polygonal column such as a quadrangular prism or a triangular prism depending on the shape of the honeycomb structure. In addition, the number of segments is not limited as long as the central portion and the outer peripheral portion are each formed of a single cell density. When the intermediate portion is provided in addition to the center portion and the outer peripheral portion as described above, the honeycomb structure is formed by three or more types of segments having different cell densities.

  According to the honeycomb structure of the present configuration, the honeycomb structure of the present configuration can be easily formed using the conventional honeycomb structure having a single cell density as a segment. For this reason, it is not necessary to introduce new equipment, and the honeycomb structure of the present configuration can be manufactured at a reduced cost. Further, a honeycomb structure having a large cross-sectional area can be easily formed according to the inner diameter of the tube of the radiant tube heater. Thereby, even if it is a large radiant tube heater, the heat of a heating fluid can be efficiently transmitted to a tube by making the cross-sectional area of a honeycomb structure into the magnitude | size according to the internal diameter of a tube.

  As described above, as an effect of the present invention, it is possible to provide a honeycomb structure that can efficiently transfer heat from a heated fluid to a tube by being disposed in the tube of a radiant tube heater.

(A) A plan view of the honeycomb structure according to the first embodiment of the present invention, (b) a plan view of the honeycomb structure obtained by extrusion molding using a mold having a cell density at the center portion higher than that of the outer peripheral portion. is there. (A) The top view of the honeycomb structure which is 2nd embodiment of this invention, (b) The top view of the joined body which joined the segment from which cell density differs. (A), (b) It is a top view of the honeycomb structure of other embodiment.

  Hereinafter, the honeycomb structures according to the first embodiment and the second embodiment of the present invention will be described with reference to FIGS. 1 and 2, respectively.

  The honeycomb structure 1 according to the first embodiment includes a plurality of cells 21 that are disposed in a tube of a radiant tube heater and that are partitioned by partition walls 20 that extend in a single axial direction. In the cross section orthogonal to the axial direction, the cell density of the central portion 10 is larger than the cell density of the outer peripheral portion 11. Here, in 1st embodiment, the center part 10 and the outer peripheral part 11 are integrally molded.

  More specifically, the honeycomb structure 1 of the first embodiment is made of ceramics, and a plan view viewed from the end face side where the cells are open is shown in FIG. The outer peripheral part 11 is formed along the outer periphery of the part 10, and the outer shape of the cross section is a circular column. Further, the cell density of the central portion 10 is twice the cell density of the outer peripheral portion 11.

  Such a honeycomb structure 1 is formed by drying or firing a molded product obtained by extruding a kneaded material obtained by mixing ceramic powder with water or a binder. Using a mold having a square central portion and an outer peripheral portion formed along the outer periphery of the central portion and having a cell density that is ½ of the central portion, and having a square outermost section. it can. As a result, as shown in FIG. 1B, the central portion 10 having a square cross-sectional shape and the outer peripheral portion 11 formed along the outer periphery of the central portion and having a cell density of ½ of the central portion. And a quadrangular prism-shaped molded body 25 having a square outermost cross section. The dried body obtained by drying the molded body 25 or the fired fired body is cut as shown by a one-dot chain line in the drawing to adjust the outer shape into a cylindrical shape, whereby the honeycomb structure 1 is formed. In FIG. 1A, the alternate long and two short dashes line is shown in order to clarify the shape of the honeycomb structure 1, and the outermost peripheral cell 21 is open on the side surface side. Moreover, the case where the cross-sectional shape of the cell 21 is a square is illustrated.

  According to the honeycomb structure 1 of the first embodiment, since the cell density of the central portion 10 is as large as twice the cell density of the outer peripheral portion 11, the heating fluid flowing through the central portion 10 is sufficient to reduce the flow rate. Resistance. And the flow of the heating fluid which distribute | circulates the outer peripheral part 11 increases because the heating fluid which was hard to flow into the center part 10 and was extruded to the outer peripheral part 11 distribute | circulates the outer peripheral part 11. FIG. Therefore, the heating fluid that has been distributed to the central portion 10 in the conventional honeycomb structure can be distributed close to the entire honeycomb structure 1 uniformly. Thereby, the large surface area of the honeycomb structure 1 is fully utilized, and the heat of the heating fluid can be efficiently transmitted to the tube. Further, since the outermost peripheral cell 21 is opened on the side surface side, the surface area is large on the side surface side of the honeycomb structure 1 and the amount of radiated heat is large, so that the heat of the heating fluid is more efficiently transferred to the tube. I can tell you.

  Next, the honeycomb structure of the second embodiment will be described with reference to FIG. The honeycomb structure 2 is formed by joining a plurality of segments 30, 31 each having a honeycomb structure including a plurality of cells 21 partitioned by partition walls 20 extending in a single direction. The central portion 12 is formed by one of the segments 31 having a single cell density, and the outer peripheral portion 13 is formed by eight of the segments 30 having a single cell density.

  More specifically, the honeycomb structure 2 of the second embodiment is made of ceramics, and a plan view viewed from the end face side where the cells 21 are opened is shown in FIG. The outer peripheral portion 13 is formed along the outer periphery of the central portion 12, and the outer shape of the cross section is a circular column shape. Further, the cell density of the central portion 12 is twice the cell density of the outer peripheral portion 13.

  As shown in FIG. 2B, the honeycomb structure 2 having such a shape has eight segments 30 arranged around a single segment 31 having a cell density twice that of the segments 30. The adjacent segments 30 and 31 are formed from the joined body 40 joined through the heat-resistant adhesive layer 22. The segments 30 and 31 are each formed by extrusion molding into a quadrangular prism using a mold having a single cell density. The cell density of the segment 31 mold is 2 of the cell density of the segment 30 mold. Is double. Then, the joined body 40 is cut as indicated by the alternate long and short dash line in the drawing, and the outer shape is adjusted to a cylindrical shape, whereby the honeycomb structure 2 is formed. Here, in the honeycomb structure 2, a portion constituted by the segments 31 corresponds to the central portion 12, and a portion formed by the eight segments 30 corresponds to the outer peripheral portion 13. In FIG. 2A, a two-dot chain line is shown for clarifying the shape of the honeycomb structure 2, and the outermost peripheral cell 21 is open on the side surface side.

  According to the honeycomb structure 2 of the second embodiment, a honeycomb structure having a cell density in the central portion 12 larger than that in the outer peripheral portion 13 can be easily manufactured by joining a plurality of conventional honeycomb structures (segments). Can do. As a result, it is possible to manufacture the honeycomb structure 2 having the same operational effects as the honeycomb structure 1 of the first embodiment while suppressing the manufacturing cost without the need to introduce new equipment.

  As described above, according to the honeycomb structures 1 and 2 of the first embodiment and the second embodiment, by increasing the cell density in the center portion, the flow rate of the heating fluid flowing through the outer peripheral portion is increased, and the honeycomb structure body The heating fluid can be made to circulate uniformly throughout. Thereby, the large surface area of the honeycomb structure can be effectively utilized, and the heat of the heating fluid can be efficiently transmitted to the tube. In addition, since the outermost peripheral cell 21 is opened on the side surface side, the surface area is large on the side surface side of the honeycomb structures 1 and 2 and the amount of radiated heat is large, so the heat of the heating fluid is more efficient Can be communicated to the tube.

  Moreover, according to the honeycomb structure 2 of the second embodiment, a honeycomb structure having a distribution in cell density can be easily manufactured by joining a plurality of conventional honeycomb structures (segments), and the manufacturing cost is reduced. Can be suppressed. In addition, it is generally difficult to produce a honeycomb structure with a large cross-sectional area by extrusion molding. However, since the cross-sectional area can be easily increased by joining the segments, it is suitable for radiant tube heaters of various sizes. A honeycomb structure having a size can be easily manufactured.

  The present invention has been described with reference to the preferred embodiments. However, the present invention is not limited to the above-described embodiments, and various improvements can be made without departing from the scope of the present invention as described below. And design changes are possible.

  For example, as with the honeycomb structure 1 of the first embodiment, when a honeycomb structure in which the central portion and the outer peripheral portion are integrated is manufactured by extrusion, the outer shape of the cross section of the central portion can be circular. Similarly to the honeycomb structure 2 of the second embodiment, when a honeycomb structure is manufactured by joining a plurality of segments, the number of segments constituting the central portion may be plural.

  Moreover, the honeycomb structure can be configured to include an intermediate portion between the center portion and the outer peripheral portion, in which the cell density is smaller than that of the central portion and larger than that of the outer peripheral portion. As illustrated in FIG. 3A, such a honeycomb structure has two segments 32, 33, and 34 having different cell densities, and the two segments around the segment 34 having the highest cell density. It can be formed from a joined body 42 in which the segment 33 having the second largest cell density is joined, and the segment 32 having the smallest cell density is joined around the segment 33. That is, the honeycomb structure includes a central portion constituted by the segments 34, an intermediate portion constituted by the segments 33, and an outer peripheral portion constituted by the segments 32.

  Further, when the honeycomb structure includes an intermediate portion between the center portion and the outer peripheral portion, the cell density is smaller than the central portion and larger than the outer peripheral portion, the intermediate portion is further closer to the outer peripheral portion side than the central portion side. It can be set as the structure formed in several parts with small cell density. As shown in FIG. 3 (b), such a honeycomb structure has a segment 38 having the highest cell density as a center, and is surrounded by four segments 35, 36, 37, and 38 having different cell densities. A segment 37 having the second largest cell density is joined, and a segment 36 having the third largest cell density is joined to the periphery of the segment 37, and a segment 43 having the smallest cell density is joined to the outermost periphery. can do. That is, the honeycomb structure includes a central portion constituted by the segment 38, a first intermediate portion constituted by the segment 37, a second intermediate portion constituted by the segment 36, and an outer peripheral portion constituted by the segment 35. Yes. As described above, in the configuration including the intermediate portion, it is possible to more precisely control the ease of circulation of the heating fluid in the cross section orthogonal to the axial direction of the honeycomb structure.

1, 2 Honeycomb structure 20 Partition 21 Cell 30-38 segment

Claims (2)

A honeycomb structure including a plurality of cells defined by partition walls arranged in a single axial direction and arranged in a tube of a radiant tube heater,
A honeycomb structure characterized in that, in a cross section orthogonal to the axial direction, a cell density in a central portion is larger than a cell density in an outer peripheral portion. A plurality of segments having a honeycomb structure including a plurality of cells partitioned by partition walls extending in a single direction are joined and formed.
The honeycomb structure according to claim 1, wherein the central portion and the outer peripheral portion are each formed by the segments having a single cell density.

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