JP2010002056A - Heating furnace and method for manufacturing honeycomb structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating furnace allowing proper grasping of characteristics of gas in a furnace in a process needing heating such as a degreasing process. <P>SOLUTION: This heating furnace 10 for calcining a heating object, includes a furnace space for placing the heated object, a heating means for rising the temperature of the furnace space, an oxygen supplying passage 28 formed with a part of an outer wall around the furnace space opened to introduce gas including oxygen into the furnace space, an exhaust passage 46 connected with the furnace space and discharging the gas in the furnace space to the outside of the furnace space, and a measuring means disposed in the exhaust passage for measuring the characteristics of the gas passing through the exhaust passage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a heating furnace and a method for manufacturing a honeycomb structure.

In recent years, it has become a problem that particulates such as soot in exhaust gas discharged from internal combustion engines such as vehicles such as buses and trucks and construction machinery cause harm to the environment and the human body. In view of this, various particulate filters have been proposed that collect particulates in exhaust gas and purify the exhaust gas by using a honeycomb structure made of porous ceramic. There is also known a honeycomb structure that modifies nitrogen oxides and the like in exhaust gas by bringing the supported catalyst into contact with exhaust gas.

As such a honeycomb structure, a prism-shaped honeycomb fired body manufactured by subjecting a mixture containing a ceramic material such as silicon carbide to extrusion, degreasing, firing, and the like is used as a sealing material layer (adhesive layer). ) Are used.

Of the steps for producing the honeycomb fired body, the degreasing step is a step for decomposing and removing organic substances such as a binder in the honeycomb formed body produced by the extrusion molding step in an oxygen atmosphere. In this degreasing step, A degreasing furnace is used.

Patent Document 1 discloses a continuous degreasing furnace used in a degreasing process. When this continuous degreasing furnace is used, a degreasing process can be performed by heating a degreasing object moving in a muffle.
Here, in the degreasing step, it is necessary to control the characteristics of the gas in the degreasing furnace, that is, pressure, temperature, gas concentration, and the like within an appropriate range.
If the oxygen concentration is too high among the above gas concentrations, a large amount of organic matter decomposes in a short time and a large amount of heat is generated, so that the temperature of the honeycomb formed body rises rapidly and cracks may occur in the honeycomb formed body. It was. In addition, if the oxygen concentration is too low, decomposition of organic substances does not proceed and degreasing may not proceed sufficiently. If firing is performed without sufficient degreasing, the strength of the honeycomb fired body may be reduced. It was.

Patent Document 2 discloses a method of degreasing a silicon carbide molded body in which degreasing is performed by heating in an atmosphere having an oxygen concentration of 1 to 20% of the gas concentration in the degreasing furnace.
In the invention disclosed in Patent Document 2, the oxygen concentration is adjusted by introducing a gas having a low oxygen concentration. In order to control the oxygen concentration within a range of 1 to 20%, a degreasing furnace is used. It is thought that it is necessary to appropriately grasp the oxygen concentration in the inside.

JP 2002-20174 A JP 2002-20173 A

Until now, as a method for grasping the oxygen concentration in the space in the degreasing furnace where the honeycomb formed body is disposed, a certain amount of gas in the furnace space is periodically extracted, A method of measuring the oxygen concentration after cooling was used.
However, since gases such as nitrogen, oxygen, and air may be introduced into the furnace space, several types of gases may be mixed in the firing furnace. In addition, gas may be generated due to combustion of organic matter or the like in the object to be heated.
Due to these factors, the flow of gas flowing in the furnace space, that is, the type, direction, speed, etc. of the gas may change greatly.

Therefore, in an environment where the flow of gas flowing in the interior space of the degreasing furnace is greatly changed, the oxygen concentration in the vicinity of a portion where a certain amount of gas is extracted may change greatly in a short time.
In addition, when a method of periodically extracting a certain amount of gas in the furnace space and measuring the oxygen concentration in the furnace space, time was required between the extraction of the gas and the concentration measurement. .
Therefore, it cannot be said that the measured oxygen concentration of the gas properly reflects the oxygen concentration in the furnace space at the time of measurement, and the methods used so far appropriately set the oxygen concentration in the furnace space. There was a problem that it was not possible to grasp.

The present invention has been made to solve such problems, and a heating furnace capable of appropriately grasping the characteristics of the gas in the furnace space in a process that requires heating, such as a degreasing process, and a degreasing process Provided is a method for manufacturing a honeycomb structure capable of manufacturing a honeycomb structure by appropriately grasping characteristics of gas in a furnace space in a process and removing organic substances in the honeycomb molded body under appropriate conditions. For the purpose.

The heating furnace according to claim 1 for achieving the above object is a heating furnace for calcining an object to be heated, and heating for raising the temperature in the furnace space in which the object to be heated is disposed and the furnace space. Means, and a part of the outer wall around the furnace space is opened, an oxygen supply passage for introducing a gas containing oxygen into the furnace space, and a gas in the furnace space connected to the furnace space. An exhaust passage that discharges outside the furnace space and a measuring means that is disposed in the exhaust passage and measures the characteristics of the gas passing through the exhaust passage are provided.

According to the heating furnace according to claim 1, the component included in the heating object is obtained by introducing the gas containing oxygen into the furnace space from the oxygen supply passage and heating the heating object using the heating means. Can be oxidized and burned.
In addition, since the measuring means for measuring the gas characteristics is provided in the exhaust passage, the characteristics of the gas passing through the exhaust passage can be measured.
Here, combustion of organic substances or the like does not occur in the exhaust passage, and the gas flowing in the exhaust passage flows from the interior of the furnace to the outside of the interior of the furnace. Compared with the gas flow, the flow is small and stable.
And, since the characteristics of the gas passing through the exhaust passage reflect the characteristics of the gas existing in the furnace space on average, by measuring the characteristics of the gas passing through the exhaust passage, The characteristics of the gas existing in the space can be grasped stably.
Therefore, by using the heating furnace of the present invention, the characteristics of the gas passing through the exhaust passage are measured, and the components contained in the heating object are determined while grasping the characteristics of the gas in the furnace space stably and appropriately. It can be oxidized and burned.
In the present specification, “calcination” means that a substance is ignited in air to remove volatile components in the substance, and is a concept including degreasing.

In the heating furnace according to claim 2, the gas in the furnace space is constantly discharged out of the furnace space.
According to the heating furnace according to claim 2, since the gas passing through the exhaust passage always flows from the inside of the furnace toward the outside of the inside of the furnace, the flow direction of the gas in contact with the measuring means is constant, and the furnace The characteristics of the gas in the internal space can be grasped more stably.

In the heating furnace according to claim 3, the flow rate of the gas passing through the exhaust passage is 10 to 100 m ³ / h (Normal).
Here, when the gas flow rate exceeds 100 m ³ / h (Normal), it becomes difficult to control the temperature of the object to be heated, and when the flow rate is less than 10 m ³ / h (Normal), the vaporized organic matter is exhausted from the exhaust passage. In the heating furnace according to claim 3, since the gas flow rate is controlled in such a range, the characteristics of the gas in the furnace space can be further stabilized. I can grasp it.

In the heating furnace according to claim 4, the measuring means is a gas concentration sensor, and in the heating furnace according to claim 5, the measuring means is an oxygen concentration sensor.
According to the heating furnace of the fourth aspect, since the gas concentration of the gas passing through the exhaust passage can be measured, it is possible to stably grasp the degree of progress of the chemical reaction during heating.
According to the heating furnace described in claim 5, since the oxygen concentration can be measured in particular, it is possible to stably grasp the degree of progress of the oxidation reaction caused by heating the object to be heated.

In the heating furnace according to claim 6, a control unit having an input unit to which a measurement value measured by the measurement unit is input and an output unit for outputting a control signal, and a control to be output from the output unit based on the measurement value A furnace atmosphere adjusting means that operates in response to the signal, and adjusts the characteristics of the gas in the furnace space by operating the furnace atmosphere adjusting means based on the control signal.
According to the heating furnace described in claim 6, since the measuring means, the control means, and the furnace atmosphere adjusting means are provided, the control means and the furnace atmosphere adjusting means are provided on the basis of the measured value measured by the measuring means. It can be operated to adjust the characteristics of the gas in the furnace space, and the characteristics of the heating object to be manufactured can be more suitably controlled.

In the heating furnace according to claim 7, the object to be heated is a kneaded material in which inorganic particles and an organic substance are kneaded. In the heating furnace according to claim 8, the organic substance is removed from the object to be heated by heating. Is done.
According to the heating furnace of the seventh and eighth aspects, the organic matter can be removed by heating the object to be heated while grasping the characteristics of the gas in the furnace space stably and appropriately.
In addition, when the heating furnace of the present invention includes the control means and the furnace atmosphere adjustment means according to claim 6, the characteristics of the gas in the furnace space are controlled to an appropriate range to control the inorganic particles and the organic matter. Therefore, the organic matter contained in the heating object can be removed at an appropriate processing speed without causing cracks in the heating object.
Moreover, in the heating furnace of Claim 9, a heating furnace can be used for degreasing of a heating target object.

In the heating furnace according to claim 10, the object to be heated is formed by forming a raw material composition containing a ceramic raw material and an organic substance, and a columnar honeycomb in which a large number of cells are arranged in parallel in the longitudinal direction with a cell wall therebetween. It is a molded body. According to the heating furnace of the tenth aspect, the honeycomb formed body can be heated while grasping the characteristics of the gas in the furnace space stably and appropriately.
Further, when the heating furnace of the present invention is provided with the control means and furnace atmosphere adjustment means according to claim 6, it is possible to control the characteristics of the gas in the furnace space to an appropriate range, The organic matter contained in the honeycomb molded body can be sufficiently decomposed at an appropriate processing speed without causing cracks in the honeycomb molded body.

The method for manufacturing a honeycomb structure according to claim 11, wherein a raw material composition including a ceramic raw material and an organic material is formed, and a columnar honeycomb formed body in which a large number of cells are arranged in parallel in a longitudinal direction with a cell wall therebetween. A honeycomb molded body preparation step for manufacturing a honeycomb degreased body by heating the honeycomb molded body in a heating furnace to remove organic matter in the honeycomb molded body to produce a honeycomb degreased body, and honeycomb firing by firing the honeycomb degreased body A manufacturing method of a honeycomb structure comprising a honeycomb fired body, including a firing step of producing a body,
The heating furnace used in the degreasing step is configured such that the furnace space in which the honeycomb formed body is disposed, the heating means for raising the temperature of the furnace space, and a part of the outer wall around the furnace space are opened. An oxygen supply passage for introducing a gas containing oxygen therein, an exhaust passage connected to the furnace space and exhausting the gas in the furnace space to the outside of the furnace space, an exhaust passage, and passing through the exhaust passage Measuring means for measuring the characteristics of the gas.

According to the method for manufacturing a honeycomb structured body according to claim 11, in the degreasing step, by measuring the characteristics of the gas passing through the exhaust passage, the characteristics of the gas in the furnace space during the degreasing step can be stabilized. I can grasp it.
That is, the honeycomb structure can be manufactured by stably and appropriately grasping the characteristics of the gas in the furnace space during the degreasing process.

In the honeycomb structure manufacturing method according to the twelfth aspect, in the degreasing step, the gas in the furnace space is always discharged out of the furnace space.
According to the method for manufacturing a honeycomb structured body according to claim 12, since the gas passing through the exhaust passage always flows from the inside of the furnace toward the outside of the inside of the furnace, the flowing direction of the gas in contact with the measuring means is determined. The honeycomb structure can be manufactured by grasping the characteristics of the gas in the furnace space during the degreasing process more stably.

In the method for manufacturing a honeycomb structured body according to claim 13, in the degreasing step, the flow rate of the gas passing through the exhaust passage is 10 to 100 m ³ / h (Normal).
Here, when the gas flow rate exceeds 100 m ³ / h (Normal), it becomes difficult to control the temperature of the object to be heated, and when the flow rate is less than 10 m ³ / h (Normal), the vaporized organic matter is exhausted from the exhaust passage. In the method for manufacturing a honeycomb structured body according to claim 13, since the gas flow rate is controlled within such a range, the inside of the furnace space during the degreasing process may be condensed. A honeycomb structure can be manufactured by more stably grasping the gas characteristics.

In the method for manufacturing a honeycomb structure according to claim 14, the measurement means is a gas concentration sensor, and in the method for manufacturing the honeycomb structure according to claim 15, the measurement means is an oxygen concentration sensor.
According to the method for manufacturing a honeycomb structured body according to claim 14, since the gas concentration can be measured among the characteristics of the gas passing through the exhaust passage, the degree of progress of the chemical reaction during the degreasing process can be stabilized. A honeycomb structure can be manufactured by grasping.
According to the method for manufacturing a honeycomb structure according to claim 15, since the oxygen concentration can be measured in particular, the progress of the oxidation reaction caused by heating the honeycomb formed body can be stably grasped and the honeycomb structure The body can be manufactured.

In the method for manufacturing a honeycomb structured body according to claim 16, the heating furnace is based on the measurement value, the control means having the input part to which the measurement value measured by the measurement means is input and the output part to output the control signal. A furnace atmosphere adjusting means that operates in response to a control signal output from the control means, and adjusts the gas characteristics in the furnace space by operating the furnace atmosphere adjusting means based on the control signal. .
According to the method for manufacturing a honeycomb structured body according to claim 16, since the heating furnace used in the degreasing step includes the measurement means, the control means, and the furnace atmosphere adjustment means, based on the measurement value measured by the measurement means. Thus, the control means and the furnace atmosphere adjustment means can be operated to adjust the characteristics of the gas in the furnace space.
Therefore, the honeycomb structure can be manufactured by removing the organic matter contained in the honeycomb formed body without causing cracks in the honeycomb formed body in the degreasing step and at an appropriate processing speed.

(First embodiment)
Hereinafter, a first embodiment which is an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a front view showing a heating furnace according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of the heating furnace shown in FIG.
In addition, although the four exhaust passages 46 are provided in the heating furnace 10 shown in FIG.1 and FIG.2, the measurement means and exhaust blower 40 which are installed with respect to each exhaust passage 46 in FIG. For the above devices, only the device provided for the rightmost exhaust passage is shown, and the mechanisms provided in the other exhaust passages are omitted.

The heating furnace 10 shown in FIG. 1 is a continuous furnace, and a horizontally long main body frame 22 constituting the heating furnace 10 is mostly a tubular muffle made of a heat-resistant material except for the carry-in portion 25 and the carry-out portion 27. 23 is supported sideways, and an inlet purge chamber 24 is provided in the vicinity of the inlet 23 a of the muffle 23.
The carry-in section 25 is provided on the upstream side of the inlet purge chamber 24, that is, on the left side in FIG.
On the other hand, an outlet purge chamber 26 is provided in the vicinity of the outlet portion 23 b of the muffle 23.
The carry-out unit 27 is provided on the rear side of the outlet purge chamber 26, that is, on the right side in FIG.

The furnace space 21 is a space surrounded by an outer wall made of a muffle 23, and a degreasing jig G1 on which the honeycomb formed body 100 (object to be heated) is placed is placed in the furnace space 21. can do.
In addition, a part of the conveyor belt 31 is laid in the muffle 23 so as to extend along the longitudinal direction of the muffle 23, and includes a motor 32 and a plurality of pulleys 33 on the lower side of the rear stage of the muffle 23. A conveyor drive is provided. The conveyor belt 31 is wound around each pulley 33.

By driving the motor 32, the conveyor belt 31 moves from the inlet 23a toward the outlet 23b, that is, from the left side to the right side in FIG.
The honeycomb molded body 100 (the heating target object) is transported from the inlet part 23a toward the outlet part 23b by placing the heating target object on the conveyor belt 31 in front of the inlet part 23a and driving the motor 32. Can do.

Of the outer wall formed of the muffle 23 surrounding the furnace space 21, the inlet 23 a and the outlet 23 b are opened, and the main body frame 22 is opened from the carry-in part 25 to the carry-out part 27. Therefore, the air containing oxygen can pass to the carry-out part 27 through the inlet part 23a and the outlet part 23b. As described above, the heating furnace 10 according to the present embodiment includes the oxygen supply passage 28 that is an open passage that is connected from the carry-in portion 25 to the carry-out portion 27 through the furnace space 21.

The muffle 23 is surrounded by a heat insulating material 34, and a cooling jacket 36 serving as a cooling means is provided at the rear end portion 23c of the muffle 23.
An exhaust passage 46 is connected to the ceiling portion 23 d of the muffle 23.

The heat insulating material 34 is a quadrangular cylindrical member, and is disposed so as to surround the muffle 23 as shown in FIG. 2. Inside the heat insulating material 34, a heater 35 as a heating unit is provided.
The heater 35 is for heating the honeycomb formed body 100 moving in the furnace space 21 to a predetermined temperature.
The cooling jacket 36 is for cooling the high-temperature honeycomb degreased body from which the honeycomb formed body 100 has been degreased to room temperature.
Accordingly, the honeycomb formed body 100 can be heated to a degreasable temperature and cooled to room temperature after the degreasing treatment.

One end of the exhaust passage 46 extends from the ceiling 23 d of the muffle 23, and the gas in the furnace space 21 is discharged from the exhaust port 41 to the outside 29 of the furnace space through the exhaust passage 46.
Further, in the exhaust passage 46, a measuring element 49a of an oxygen concentration sensor 49 which is a measuring means is provided.
In the middle of the exhaust passage 46, an exhaust blower 40, which is a furnace atmosphere adjusting means, is provided at a position on the exhaust port 41 side rather than the muffle 23 side with respect to the probe 49a.

The oxygen concentration sensor 49 is arranged so that the probe 49a and the gas flowing through the exhaust passage 46 are in contact with each other, and is electrically connected to an input unit 51 of an electronic control unit (hereinafter referred to as ECU) 50 that is a control means. Has been. Therefore, the oxygen concentration of the gas flowing through the exhaust passage 46 can be measured, and the obtained measurement value can be sent to the ECU 50 as an electrical signal.
The oxygen concentration sensor 49 is provided with a display unit (not shown) that displays the measured oxygen concentration numerically.

The ECU 50 is electrically connected to the oxygen concentration sensor 49 at its input 51 and to the exhaust blower 40 at its output 52. In addition, an input mechanism (not shown) is provided for the operator to directly input a set value of the oxygen concentration. Further, in the ECU 50, there is an arithmetic processing unit 53 for calculating the rotational speed of the exhaust blower necessary for controlling the oxygen concentration from the set value of the oxygen concentration and the measured value of the oxygen concentration inputted in the form of an electric signal. Is provided.

Next, the honeycomb formed body 100 to be heated, the honeycomb fired body 110 obtained by degreasing and firing the honeycomb formed body, and the honeycomb structure to be manufactured by the honeycomb structure manufacturing method of the present embodiment. The body 120 will be described with reference to FIGS. 3 (a), 3 (b), and 4. FIG. Fig.3 (a) is a perspective view which shows typically an example of a honeycomb molded object, FIG.3 (b) is the BB sectional drawing.
FIG. 4 is a perspective view schematically showing an example of a honeycomb structure.

As shown in FIG. 3A, the honeycomb formed body 100 has a large number of cells 101 arranged in parallel in the longitudinal direction (the direction of arrow C in FIG. 3A). Separated by One end of the cell 101 is sealed with the sealing material 103.

The honeycomb fired body 110 is obtained by degreasing and firing such a honeycomb formed body 100. Since the honeycomb fired body 110 is made of a porous ceramic whose shape is substantially the same as that of the honeycomb molded body 100, when exhaust gas is allowed to flow into one cell of the honeycomb fired body 110, the exhaust gas always passes through the cell walls separating the cells. After that, it flows out from other cells. Therefore, when exhaust gas passes through the cell wall, particulates in the exhaust gas are captured by the cell wall portion, and the exhaust gas is purified.
That is, the cell wall of the honeycomb fired body 110 functions as an exhaust gas purification filter.

The honeycomb structure 120 is cut so that the cross-sectional shape is circular on the outer periphery of the aggregated body 122 of honeycomb fired bodies in which a plurality of honeycomb fired bodies 110 are bound through a sealing material layer (adhesive layer) 121. And a sealing material layer (coat layer) 123 is formed on the outer periphery thereof.

Hereinafter, the manufacturing method of the honeycomb structure of the first embodiment will be described in the order of steps.
Here, the manufacturing method of the honeycomb structure of the first embodiment when silicon carbide powder, which is a ceramic raw material, is used as the main component of the constituent material will be described.

First, as a ceramic raw material, silicon carbide powder having a different average particle size and an organic binder are dry-mixed to prepare a mixed powder, and a liquid plasticizer, a lubricant and water are mixed to prepare a mixed liquid. The mixed powder and the mixed liquid are mixed using a wet mixer to prepare a wet mixture for manufacturing a molded body.

The wet mixture is transported after preparation and put into a molding machine.
When the wet mixture is charged into an extruder, the wet mixture becomes a honeycomb formed body having a predetermined shape by extrusion. This honeycomb formed body is dried using a microwave dryer, a hot air dryer, a dielectric dryer, a vacuum dryer, a vacuum dryer, a freeze dryer or the like to obtain a honeycomb formed body in a dried state.

Next, a cutting step of cutting both ends of the honeycomb formed body manufactured using the cutting device is performed, and the honeycomb formed body is cut into a predetermined length. Then, if necessary, the end side of the inlet side cell group and the end side of the outlet side cell group at the inlet side are filled with a predetermined amount of sealing material paste as a sealing material, and the cells are To seal. When sealing the cells, a sealing mask is applied to the end face of the honeycomb formed body (that is, the cut surface after the cutting step), and only the cells that need to be sealed are filled with the sealing material paste.
Through such a process, the honeycomb formed body 100 that is a heating object to be degreased in the degreasing process is manufactured.

Next, in order to remove the organic matter in the honeycomb formed body filled with the sealing material paste, the honeycomb formed body is transported to the heating furnace 10 of the present invention, and a degreasing process is performed. The removed honeycomb degreased body is produced.
The details of this degreasing process will be described in detail later.

Next, the produced honeycomb degreased body is conveyed to a firing furnace, and a firing process is performed to produce a honeycomb fired body.
Although the said baking process can be performed by a conventionally well-known method and it does not specifically limit, It is preferable to carry out in the temperature range of 1400-2300 degreeC by making it normal pressure in presence of gas with low reactivity, such as argon.
After the firing step, a sealing material paste to be a sealing material layer (adhesive layer) is applied to the side surface of the obtained honeycomb fired body to form a sealing material paste layer, and sequentially on the sealing material paste layer, The process of laminating other honeycomb fired bodies is repeated to produce an aggregate of honeycomb fired bodies in which a predetermined number of honeycomb fired bodies are bundled. In addition, as a sealing material paste, what consists of an inorganic binder, an organic binder, an inorganic fiber, and / or an inorganic particle can be used, for example.

Next, the aggregate of the honeycomb fired bodies is heated to dry and solidify the adhesive paste layer to form a sealing material layer (adhesive layer). Then, the aggregate of the honeycomb fired bodies is cut using a diamond cutter to form a ceramic block, the sealing material paste is applied to the outer peripheral surface of the ceramic block, the sealing material paste is dried and solidified, and the sealing material layer (coating layer) ) To complete the honeycomb structure.

Next, the operation of the heating furnace in the degreasing process for degreasing the honeycomb formed body 100 will be described.
When performing the degreasing process, before the honeycomb formed body 100 is charged into the degreasing furnace 10, electric power is supplied to the heater 35, which is a heating means, and the temperature of the heater 35 is increased. And the temperature of the muffle 23 is raised by the heat from the heater 35, and the temperature of the in-furnace space 21 is made into the temperature (200-600 degreeC) suitable for the degreasing process.

FIG. 5 is an enlarged view of the vicinity of the muffle in FIG.
When the honeycomb molded body is put into the degreasing furnace 10, a plurality of honeycomb molded bodies 100 are disposed on a degreasing jig G 1 as shown in FIG. 5 and the longitudinal direction thereof is perpendicular to the traveling direction of the conveyor belt 31. Arrange them in the direction. In this embodiment, two degreasing jigs G <b> 1 are arranged with respect to the width of the conveyor belt 31.
Further, a rib (not shown) is provided on the mounting surface of the degreasing jig G1, and a certain interval is provided between the mounting surface of the degreasing jig G1 and the bottom surface of the honeycomb formed body 100. .

Next, the degreasing jig G1 in which the honeycomb formed bodies 100 are arranged in this way is placed on the conveyor belt 31 in the carry-in portion 25.
Subsequently, when the motor 32 is driven, the conveyor belt 31 moves from the carry-in portion 25 toward the carry-out portion 27, so that the degreasing jig G <b> 1 placed on the conveyor belt 31 also moves toward the carry-out portion 27. .

The degreasing jig G <b> 1 is introduced into the in-furnace space 21 from the inlet portion 23 a of the muffle 23 through the inlet purge chamber 24. As the degreasing jig G1 moves through the furnace space 21, the temperature of the degreasing jig and the honeycomb molded body 100 rises, and the organic matter contained in the honeycomb molded body 100 volatilizes and degreasing proceeds. .

At this time, since the oxygen supply passage 28 is provided in the heating furnace 10 of the present invention, oxygen is always supplied to the furnace space 21. Therefore, some of the volatilized organic substances react with oxygen and burn. Organic substances and oxygen are consumed by this combustion reaction, and reactive gases such as carbon monoxide, carbon dioxide, and water vapor are generated.

Volatile organic substances and reaction gas are introduced into the exhaust passage 46 from the ceiling 23 d of the muffle 23, pass through the exhaust passage 46, and are exhausted from the exhaust port 41.
At this time, since the exhaust blower 40 is provided in the exhaust passage 46, by operating the exhaust blower 40, the gas passing through the exhaust passage 46 is always directed from the inside of the furnace space 21 toward the outside of the furnace space. The direction of gas flow can be controlled to flow.

The exhausted gas passes through the exhaust passage 46. At this time, the exhaust gas contacts the probe 49a of the oxygen concentration sensor 49 provided in the exhaust passage 46, so that the oxygen concentration of the gas flowing in the exhaust passage 46 is measured. Is done.
As described above, since the direction of the gas flowing in the exhaust passage 46 is constant, the direction of the gas flowing in contact with the measuring element 49a is constant, and the oxygen concentration can be measured stably.

The oxygen concentration sensor 49 converts a measurement value (electric resistance or the like) measured by the probe 49a into an appropriate electric signal, and displays the oxygen concentration as a numerical value on the display unit. Thereby, the operator can confirm whether the suitable oxygen concentration is maintained in the degreasing process.
Further, the oxygen concentration is sent from the oxygen concentration sensor 49 to the input unit 51 of the ECU 50 as a measured value in the form of an electric signal.

The ECU 50 includes a well-known microcomputer composed of a CPU, ROM, RAM, etc. (not shown) and its peripheral circuits. The ECU 50 has an arithmetic processing unit 53. The arithmetic processing unit 53 performs an arithmetic process based on a preset program based on the set value of the oxygen concentration and the measured value of the oxygen concentration, and an exhaust blower necessary for controlling the oxygen concentration to an appropriate range. The number of rotations of 40 is obtained, and the calculation processing result is output from the output unit 52 as a control signal from the output unit 52 to the exhaust blower 40 which is the furnace atmosphere adjusting means.

The exhaust blower 40 controls the exhaust speed from the exhaust blower 40 by changing the rotation speed based on the control signal output from the output unit 52 of the ECU 50.
By doing so, the flow rate of the gas passing through the exhaust passage 46 can be controlled.
The oxygen concentration in the furnace space 21 can be controlled by controlling the flow rate of the gas passing through the exhaust passage 46.
In addition, since the arithmetic processing unit 53 is set with a program for determining the rotational speed of the exhaust blower 40 so that the gas flow rate is in an appropriate range (10 to 100 m ³ / h (Normal)), the exhaust passage 46 is set. The oxygen concentration in the furnace space 21 can be controlled by controlling the flow rate of the gas flowing through the reactor to an appropriate range.

Here, a method for controlling the oxygen concentration in the furnace space 21 will be further described.
In the degreasing process, the organic substances volatilized from the honeycomb formed body 100 are burned, so that oxygen in the furnace space 21 is consumed, and the oxygen concentration in the furnace space 21 decreases. When the oxygen concentration becomes too low, the exhaust speed is increased by increasing the rotational speed of the exhaust blower 40. As a result, the internal pressure in the furnace space 21 decreases and the amount of air flowing into the furnace space 21 from the oxygen supply passage 28 increases, so that the oxygen concentration in the furnace space 21 can be increased.
On the other hand, if the amount of air flowing from the oxygen supply passage 28 into the furnace space 21 is too large, the oxygen concentration in the furnace space 21 increases. When the oxygen concentration becomes too high, the exhaust speed is reduced by lowering the rotational speed of the exhaust blower 40. As a result, the internal pressure in the furnace space 21 increases and the amount of air flowing into the furnace space 21 from the oxygen supply passage 28 decreases, so that the oxygen concentration in the furnace space 21 can be lowered.

Since the degreasing jig G1 moves in the furnace space 21 in a state where the oxygen concentration in the furnace space 21 is controlled to an appropriate range in this way, the honeycomb formed body 100 is subjected to an appropriate oxygen concentration condition. Degreased. The degreasing jig G1 reaches the rear end 23c of the muffle 23, and the degreasing jig G1 and the honeycomb formed body 100 are cooled to room temperature by the cooling jacket 36.

Then, the degreasing jig reaches the outside of the muffle 23 from the outlet portion 23b of the muffle 23, is carried out of the heating furnace 10 from the carry-out portion 27 through the outlet purge chamber 26, and the degreasing step is completed.

Hereinafter, the effects of the heating furnace of the present embodiment and the honeycomb structure manufacturing method using the heating furnace will be listed.
(1) Since the measuring element 49a of the oxygen concentration sensor 49 as a measuring means is disposed in the exhaust passage 46, the oxygen concentration of the gas passing through the exhaust passage 46 can be measured. Since the oxygen concentration of the gas passing through the exhaust passage 46 is an average reflection of the oxygen concentration of the gas existing in the furnace space 21 of the heating furnace 10, the oxygen concentration of the gas passing through the exhaust passage 46 is By measuring, the oxygen concentration of the gas existing in the furnace space 21 of the heating furnace 10 can be grasped stably and appropriately.
Therefore, the oxygen concentration of the gas passing through the exhaust passage 46 is measured, and the organic matter contained in the honeycomb formed body 100 is oxidized while stably and properly grasping the oxygen concentration of the gas in the furnace space 21 of the heating furnace 10. Can be burned.
(2) Since the exhaust passage 46 is provided with the exhaust blower 40, the gas in the furnace space 21 can always be discharged out of the furnace space. Thus, if the gas flowing through the exhaust passage 46 always flows from the inside of the furnace space 21 toward the outside 29 of the furnace space, the flow direction of the gas in contact with the probe 49a becomes constant. The oxygen concentration inside can be grasped more stably.
(3) By adjusting the rotation speed of the exhaust blower 40, the flow rate of the gas passing through the exhaust passage 46 can be controlled within an appropriate range. By controlling the flow rate of the gas passing through the exhaust passage 46, it is possible to prevent organic substances in the gas from condensing in the exhaust passage 46 and insufficient temperature control of the object to be heated.
(4) Since the measured value of the oxygen concentration is input from the oxygen concentration sensor 49 to the ECU 50 and the rotational speed of the exhaust blower 40 is controlled by the control signal from the ECU 50, the measured value of the oxygen concentration measured in the exhaust passage 46 is used. The oxygen concentration in the furnace space 21 is adjusted by adjusting the exhaust speed of the gas discharged from the furnace space 21 and adjusting the amount of oxygen supplied from the oxygen supply passage 28 into the furnace space 21. be able to.
Thereby, in the degreasing step, the organic matter contained in the honeycomb formed body 100 can be sufficiently decomposed at an appropriate processing speed, and cracks can be prevented from occurring in the honeycomb formed body 100.

Examples that more specifically disclose the first embodiment of the present invention will be described below.
Example 1
250 kg of α-type silicon carbide powder having an average particle size of 10 μm, 100 kg of α-type silicon carbide powder having an average particle size of 0.5 μm, and 20 kg of an organic binder (methylcellulose) were mixed to prepare a mixed powder.
Next, separately, 12 kg of lubricant (Unilube manufactured by NOF Corporation), 5 kg of plasticizer (glycerin), and 65 kg of water are mixed to prepare a liquid mixture, and this liquid mixture and the mixed powder are mixed in a wet mixer. And mixed to prepare a wet mixture.
The moisture content of the wet mixture prepared here was 14% by weight.

Next, this wet mixture was conveyed to an extrusion molding machine using a conveyance device, and charged into a raw material inlet of the extrusion molding machine.
In addition, the moisture content of the wet mixture immediately before feeding the extruder was 13.5% by weight.
And the production | generation form of substantially the same shape as the honeycomb molded object 100 shown to Fig.3 (a) was produced by extrusion molding.

Next, after drying the generated shape using a microwave dryer or the like, a predetermined cell is filled with a sealing material paste having the same composition as the wet mixture, and further dried using a dryer. A honeycomb molded body 100 made of a silicon carbide molded body having a size of 34.3 mm × 34.3 mm × 250 mm, a number of cells (cell density) of 46.5 cells / cm ² , and a cell wall thickness of 0.30 mm. Produced.

Next, the honeycomb formed body 100 was degreased at 400 ° C. using the heating furnace 10 shown in the first embodiment. Specific specifications of the heating furnace 10 are as follows.
The heating furnace 10 was a continuous furnace, the muffle 23 had a length of 2.4 m, a width of 0.85 m, a maximum height of 0.15 m, and the total volume of the furnace space 21 was 2.7 m ³ . .
Four exhaust passages 46 are erected from the muffle 23 and have a diameter of 0.1 m. And the measuring element 49a of the oxygen concentration sensor 49 was installed in each exhaust passage 46 at the position of 1 m from the ceiling part 23d of the muffle 23 toward the exhaust port side.

Using this heating furnace 10, a degreasing process was performed according to the following procedure.
First, electric power was supplied to the heater 35, and the temperature of the heater 35 was raised so that the temperature of the furnace inner space 21 would be 400 ° C. Further, the motor 32 is driven so that the conveyor belt 31 moves in the direction from the carry-in unit 25 to the carry-out unit 27.
At this time, the moving speed of the conveyor belt 31 was 140 mm / min.
And many degreasing jig | tool G1 which accommodated ten honeycomb forming bodies 100 side by side was prepared.
Then, the degreasing jig G1 is arranged along the traveling direction of the conveyor belt 31 and placed on the conveyor belt 31 in the carry-in portion 25 of the heating furnace 10, whereby the degreasing jig G1 is sequentially placed in the furnace space of the muffle 23. 21 and the honeycomb formed body 100 was continuously degreased.

The oxygen concentration set value input to the ECU 50 is set to 10 vol%, the oxygen concentration in the exhaust passage 46 is measured by the oxygen concentration sensor 49, and the rotational speed of the exhaust blower 40 is controlled based on the measured oxygen concentration. The oxygen concentration in the space 21 was adjusted.
The exhaust blower 40 is always operated according to a program set in the arithmetic processing unit 53 so that the flow rate of the gas passing through the exhaust passage 46 is 10 to 100 m ³ / h (Normal). Gas was constantly discharged out of the furnace space 29.
Then, the degreasing jig G1 storing the honeycomb degreased body was taken out from the carry-out portion 27, and the degreasing process was completed.

Subsequently, the honeycomb degreased body was fired at 2200 ° C. for 3 hours in an argon atmosphere at normal pressure to complete the production of the honeycomb fired body made of the silicon carbide sintered body.

(Reference Example 1)
The program set in the arithmetic processing unit 53 is changed so that the flow rate of the gas passing through the exhaust passage 46 is 5 to 100 m ³ / h (Normal), and the exhaust blower 40 is always operated according to this program. The degreasing process was performed in the same manner as in Example 1 to produce a honeycomb fired body.

(Reference Example 2)
Except that the program set in the arithmetic processing unit 53 is changed so that the flow rate of the gas passing through the exhaust passage 46 becomes 10 to 120 m ³ / h (Normal), and the exhaust blower 40 is always operated according to this program. The degreasing process was performed in the same manner as in Example 1 to produce a honeycomb fired body.

(Reference Example 3)
When controlling the oxygen concentration, the program set in the arithmetic processing unit 53 is changed so as to control the ON / OFF of the rotation of the exhaust blower 40 instead of controlling the rotation speed of the exhaust blower. According to the above, a degreasing process was performed in the same manner as in Example 1 except that the exhaust blower 40 was not always operated, and a honeycomb fired body was manufactured.

(Comparative Example 1)
A heating furnace in which an oxygen concentration sensor probe was additionally installed in the furnace space 21 of the heating furnace 10 used in Example 1 was manufactured.
The installation position of the added oxygen concentration sensor probe is a position that protrudes 1 cm into the furnace space 21 from the ceiling 23d of the muffle 23, and the direction from the highest point of the ceiling 23d of the muffle 23 to the side surface of the muffle 23 ( The position was moved 0.2 m to the right in FIG.
The ECU 50 is not connected to the added oxygen concentration sensor, and the added oxygen concentration sensor has only a function of measuring the oxygen concentration in the furnace space 21 exclusively.
That is, this heating furnace can simultaneously measure the oxygen concentration in the exhaust passage 46 and in the furnace space 21, and controls the oxygen concentration based on the result of measuring the oxygen concentration of the gas flowing through the exhaust passage 46. there were.
Using this heating furnace, a degreasing process was performed in the same manner as in Example 1 to produce a honeycomb fired body.

(Evaluation of recording results of oxygen concentration in the degreasing process)
In the degreasing process of Example 1, Reference Examples 1 to 3, and Comparative Example 1, the oxygen concentration was measured and recorded by the oxygen concentration sensor installed in each heating furnace, and the variation in the measured value of the oxygen concentration was determined from the recorded result. evaluated.
Specifically, the degreasing jig G1 in which the honeycomb formed body 100 is housed is sequentially introduced into the heating furnace, and after 60 minutes have passed since the heating furnace was continuously operated, the oxygen concentration is changed every 150 minutes for 150 minutes. Recorded.

Table 1 shows the conditions for recording the oxygen concentration in each example, reference example, and comparative example, and the average value and variation of the recorded results.
FIG. 6 shows the relationship between the time (minutes) from the start of recording and the recorded oxygen concentration (vol%) in Example 1 and Comparative Example 1.
Furthermore, the relationship between the time (minutes) from the start of recording in Example 1 and Reference Example 3 and the recorded oxygen concentration (vol%) is shown in FIG. FIG. 7 also shows a section moving average curve of oxygen concentration every 20 minutes.

In Comparative Example 1, the oxygen concentration was measured simultaneously with an oxygen concentration sensor in which a probe was installed in each of the furnace space 21 and the exhaust passage 46. Table 1 and FIG. The result of measuring and recording the concentration is shown.
The oxygen concentration was measured and recorded in the four exhaust passages 46. Table 1, FIG. 6 and FIG. 7 show the right exhaust passage 46 in FIG. The measured value of the sensor provided in is shown.

As apparent from Table 1 and FIG. 6, in Example 1 and Reference Examples 1 to 3, the oxygen concentration was measured in the exhaust passage, so the variation in the recorded value of the oxygen concentration was small (effects ( 1)). In contrast, in Comparative Example 1, since the oxygen concentration was measured in the furnace space, the variation in the recorded value of the oxygen concentration was large.
In particular, when Example 1 and Comparative Example 1 were compared, although the actual state in the furnace space was considered to be the same, the variation in the recorded values was greatly different. From this, it has been clarified that a stable measurement value can be obtained by measuring the oxygen concentration in the exhaust passage, and the oxygen concentration can be properly grasped (operation effect (1)).

Further, as apparent from FIG. 7, in the first embodiment, the gas in the furnace space is constantly discharged outside the furnace space, so that the gas in the furnace space is always discharged outside the furnace space. It was found that the waviness of the section moving average curve can be made smaller than that of the reference example 3 which is not performed. From this, it became clear that the oxygen concentration in the furnace space 21 could be grasped more stably (operation effect (2)).

Further, in Example 1, since the flow rate of the gas passing through the exhaust passage is controlled to an appropriate range, the organic matter is not condensed in the exhaust passage, and degreasing of the honeycomb formed body is sufficiently advanced. (Action and effect (3)).
On the other hand, in Reference Examples 1 and 3, the flow rate of the gas passing through the exhaust passage may be as low as less than 10 m ³ / h ((Normal), and part of the organic matter is condensed in the exhaust passage. Was observed.
Further, in Reference Example 2, the flow rate of the gas passing through the exhaust passage may increase beyond 100 m ³ / h (Normal), and the temperature control of the honeycomb formed body that is the heating target is not sufficiently performed. In some cases, the honeycomb formed body was not sufficiently degreased.

(Second embodiment)
FIG. 8 is a cross-sectional view schematically showing a part of another embodiment of the heating furnace of the present invention.
In the heating furnace 140 of the present embodiment, a measurement exhaust passage 146 is provided separately from the exhaust passage 46. One end of the measurement exhaust passage 146 is connected to the ceiling portion 23 d of the muffle 23, and the other end is connected to the exhaust passage 46. An oxygen sensor 49a is installed in the measurement exhaust passage 146.

In the heating furnace 140 of this embodiment, the oxygen concentration of the gas passing through the measurement exhaust passage 146 can be measured. Since the gas flow passing through the measurement exhaust passage 146 is more stable than in the furnace space 21, the oxygen concentration can be measured stably.
Further, since the oxygen concentration can be controlled based on the measured oxygen concentration, the oxygen concentration can be adjusted to an appropriate range.
Accordingly, even in the heating furnace having such a configuration, the oxygen concentration can be measured and controlled in the same manner as in the heating furnace of the first embodiment, and the effects (1) to (4) are also provided in this embodiment. Can be demonstrated.

(Third embodiment)
FIG. 9 is a cross-sectional view schematically showing a part of another embodiment of the heating furnace of the present invention.
In the heating furnace 160 of the present embodiment, instead of using the exhaust blower 40, gas introduction means that adjusts the oxygen concentration by introducing a low oxygen concentration gas into the muffle is used as the furnace atmosphere adjustment means. This gas introduction means includes a pipe 161, a nozzle 162, an electromagnetic valve 163, and a gas supply source 164.
Moreover, in the heating furnace 160, unlike the heating furnace 10 shown in the first embodiment, the output unit 52 of the ECU 50 is connected to the electromagnetic valve 163 and is not electrically connected to the exhaust blower 40.

In this gas introducing means, a nozzle 162 is provided at one end of a pipe 161, and the nozzle 162 is connected to the side wall portion 23 e of the muffle 23. The other end of the pipe 161 is connected to a gas supply source 164 through an electromagnetic valve 163.
The gas supply source 164 stores a low oxygen concentration gas composed of a mixed gas of nitrogen and oxygen, and this low oxygen concentration gas passes through the pipe 161 from the nozzle 162 into the muffle 23, that is, into the furnace space 21. be introduced.

The solenoid valve 163 is electrically connected to the output unit 52 of the ECU 50, and the opening degree thereof can be adjusted based on a control signal output from the ECU 50.
By adjusting the opening degree of the electromagnetic valve 163, the flow rate of the low oxygen concentration gas introduced from the nozzle 162 into the furnace space 21 through the piping 161 through the electromagnetic valve 163 from the gas supply source 164 is adjusted. The Thus, by operating the electromagnetic valve 163, the oxygen concentration in the furnace space 21 can be adjusted.
Specifically, when the oxygen concentration in the furnace space 21 is high, the opening degree of the electromagnetic valve 163 is increased to introduce a low oxygen concentration gas from the gas supply source 164 into the furnace space 21, and the furnace The oxygen concentration in the inner space 21 can be reduced.
On the contrary, when the oxygen concentration in the furnace space 21 is low, the amount of the low oxygen concentration gas introduced into the furnace space 21 from the gas supply source 164 is reduced by lowering the opening degree of the electromagnetic valve 163. Thus, the oxygen concentration in the furnace space 21 can be increased.
Accordingly, the effects (1) to (3) can be exhibited also in the present embodiment. Further, the amount of the low oxygen concentration gas supplied from the gas supply source 164 into the furnace space 21 is adjusted based on the measured value of the oxygen concentration measured in the exhaust passage 46, so that the oxygen concentration in the furnace space 21 is adjusted. Can be adjusted.
Thereby, in the degreasing step, the organic matter contained in the honeycomb formed body 100 can be sufficiently decomposed and removed at an appropriate processing speed, and cracks can be prevented from occurring in the honeycomb formed body 100.

(Fourth embodiment)
In the heating furnace of the present embodiment, although not particularly illustrated, both the exhaust blower 40 shown in the first embodiment and the gas introduction means shown in the third embodiment are used as furnace atmosphere adjustment means.
In the heating furnace of the present embodiment, both the exhaust blower 40 and the electromagnetic valve 163 are connected to the output unit 52 of the ECU 50, and both the exhaust blower 40 and the electromagnetic valve 163 are controlled by a control signal output from the output unit 52 of the ECU 50. In operation, the oxygen concentration in the furnace space 21 can be adjusted.
Therefore, in this embodiment, the operational effects (1) to (4) can be exhibited, and the organic matter contained in the honeycomb formed body 100 can be sufficiently decomposed and removed at an appropriate processing speed in the degreasing step. Moreover, it is possible to prevent the honeycomb formed body 100 from being cracked.

(Other embodiments)
The heating furnace and the manufacturing method of the honeycomb structure in the first to fourth embodiments may be as follows.
The heating furnace may be a batch-type heating furnace instead of the continuous furnace shown in FIG.
Even in the case of a batch-type heating furnace, the same muffle, exhaust passage, measuring means, control means, and furnace atmosphere adjusting means as in the heating furnace 10 of the first embodiment can be provided.
It is desirable that the shape and size of the heating furnace and each part be a shape and size that allows an operator to manually input and remove the degreasing jig G1.
And when performing a degreasing process using a batch-type heating furnace, instead of carrying in and taking out the degreasing jig | tool G1 continuously in a furnace interior space using a conveyor belt etc., for degreasing | defatting. Repeat the procedure of manually loading the jig G1 into the furnace space, manually removing the degreasing jig G1 after the degreasing process, and manually loading another degreasing jig G1 into the furnace space again. Thus, a degreasing process can be performed.
Even in such a batch-type heating furnace, by providing the measuring means in the exhaust passage, it is possible to appropriately grasp the characteristics of the gas in the heating furnace.

In addition, the characteristics of the gas measured in the exhaust passage are not particularly limited to the oxygen concentration, but are generated by the concentration of other gases, for example, the concentration of alcohol that is volatile from the honeycomb molded body, or the combustion of organic matter. It may be the concentration of carbon monoxide, carbon dioxide, water vapor, etc., or the temperature of the gas.
Further, a plurality of characteristics may be measured simultaneously by installing a plurality of measuring means.

In the heating furnace 10 shown in FIGS. 1 and 2, four exhaust passages 46 are provided, and a probe 49 a is installed in each exhaust passage 46, but the probe 49 a is part of the exhaust passage 46. It may be installed only in.
Even in this case, the characteristics of the gas passing through the exhaust passage 46 can be measured, and the characteristics of the gas existing in the furnace space 21 can be stably grasped.
Further, the furnace atmosphere adjusting means for discharging the gas from the furnace space 21 to the outside of the furnace space is not particularly limited to the exhaust blower 40, and an apparatus such as a suction pump may be used.

The honeycomb structure manufactured in the first to fourth embodiments is not limited to the honeycomb structure in which the cells are sealed. A honeycomb structure in which cells are sealed can be suitably used as a honeycomb filter, and a honeycomb structure in which cells are not sealed can be suitably used as a catalyst carrier.
Therefore, in the method for manufacturing a honeycomb structure according to the first to fourth embodiments, it is not always necessary to fill the plug material paste, and filling may be performed as necessary.

The main component of the constituent material of the honeycomb structure is not limited to silicon carbide. Other ceramic raw materials include, for example, nitride ceramics such as aluminum nitride, silicon nitride, boron nitride, and titanium nitride, zirconium carbide, and carbonized Examples thereof include inorganic powders such as carbide ceramics such as titanium, tantalum carbide, and tungsten carbide, and oxide ceramics such as alumina, zirconia, cordierite, mullite, and aluminum titanate.
Of these, non-oxide ceramics are preferred, and silicon carbide is particularly preferred. This is because ceramics made of these constituent materials are excellent in heat resistance, mechanical strength, thermal conductivity, and the like. In addition, ceramic raw materials such as silicon-containing ceramics in which metallic silicon is blended with the above-described ceramics, ceramics bonded with silicon or a silicate compound can be cited as constituent materials, and among these, silicon carbide is blended with silicon carbide. (Silicon-containing silicon carbide) is desirable.

The particle size of the inorganic powder such as silicon carbide powder is not particularly limited. For example, 100 parts by weight of a powder having an average particle size of 0.3 to 50 μm and a powder having an average particle size of 0.1 to 1.0 μm A combination of 5 to 65 parts by weight is preferred. When the particle size of the inorganic powder is adjusted in this way, the honeycomb fired body that has undergone the subsequent firing step is preferable in that the size change (shrinkage) is smaller than that of the honeycomb degreased body.
In order to adjust the pore diameter and the like of the honeycomb fired body, it is necessary to adjust the firing temperature. By adjusting the particle size of the inorganic powder in this way, the pore diameter of the honeycomb fired body can be adjusted. .

The organic binder in the wet mixture is not particularly limited, and examples thereof include methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, and polyethylene glycol. Of these, methylcellulose is desirable. Usually, the blending amount of the organic binder is desirably 1 to 10 parts by weight with respect to 100 parts by weight of the inorganic powder.
The plasticizer in the wet mixture is not particularly limited, and examples thereof include glycerin. The lubricant is not particularly limited, and examples thereof include polyoxyalkylene compounds such as polyoxyethylene alkyl ether and polyoxypropylene alkyl ether.
Specific examples of the lubricant include polyoxyethylene monobutyl ether and polyoxypropylene monobutyl ether.
In some cases, the plasticizer and the lubricant may not be contained in the mixed raw material powder.

In preparing the wet mixture, a dispersion medium liquid may be used. Examples of the dispersion medium liquid include water, alcohols such as methanol, and organic solvents such as benzene.
Furthermore, a molding aid may be added to the wet mixture.
The molding aid is not particularly limited, and examples thereof include ethylene glycol, dextrin, fatty acid, fatty acid soap, polyalcohol and the like.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide ceramics, spherical acrylic particles, and graphite may be added to the wet mixture as necessary.
The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Of these, alumina balloons are desirable.

Moreover, it is desirable that the temperature of the wet mixture using the silicon carbide powder prepared here is 28 ° C. or less. It is because an organic binder may gelatinize when temperature is too high.
Further, the organic content in the wet mixture is desirably 10% by weight or less, and the water content is desirably 8.0 to 20.0% by weight.

Although it does not specifically limit as a sealing material paste which seals a cell, The thing from which the porosity of the sealing material manufactured through a post process becomes 30 to 75% is desirable, For example, the thing similar to a wet mixture is used. be able to.

Further, when an aggregate of honeycomb fired bodies is manufactured as a honeycomb structure, the honeycomb fired bodies are assembled in advance through a spacer, and then a sealing material paste is injected into the gap between the honeycomb fired bodies. Thus, an aggregate of honeycomb fired bodies may be produced.

Examples of the inorganic binder in the sealing material paste include silica sol and alumina sol. These may be used alone or in combination of two or more. Among inorganic binders, silica sol is desirable.

Examples of the organic binder in the sealing material paste include polyvinyl alcohol, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and the like. These may be used alone or in combination of two or more. Among organic binders, carboxymethylcellulose is desirable.

Examples of inorganic fibers in the sealing material paste include ceramic fibers such as silica-alumina, mullite, alumina, and silica. These may be used alone or in combination of two or more. Among inorganic fibers, alumina fibers are desirable.

Examples of the inorganic particles in the sealing material paste include carbides and nitrides. Specific examples include inorganic powders made of silicon carbide, silicon nitride, and boron nitride. These may be used alone or in combination of two or more. Among the inorganic particles, silicon carbide having excellent thermal conductivity is desirable.

Furthermore, a pore-forming agent such as balloons that are fine hollow spheres containing oxide ceramics, spherical acrylic particles, and graphite may be added to the sealing material paste as necessary. The balloon is not particularly limited, and examples thereof include an alumina balloon, a glass micro balloon, a shirasu balloon, a fly ash balloon (FA balloon), and a mullite balloon. Of these, alumina balloons are desirable.

It is a front view which shows the heating furnace of 1st embodiment of this invention. It is the sectional view on the AA line of the heating furnace shown in FIG. (A) is a perspective view which shows typically an example of a honeycomb molded object, (b) is the BB sectional drawing. It is a perspective view which shows typically an example of a honeycomb structure. FIG. 3 is an enlarged view of the vicinity of a muffle in FIG. 2. It is a graph which shows the relationship between the time (minute) from the recording start in Example 1 and Comparative Example 1, and the recorded oxygen concentration (vol%). It is a graph which shows the relationship between the time (minute) from the recording start in Example 1 and Reference Example 3, and the recorded oxygen concentration (vol%). It is sectional drawing which shows the heating furnace of 2nd embodiment of this invention. It is sectional drawing which shows the heating furnace of 3rd embodiment of this invention.

Explanation of symbols

10 Heating furnace (first embodiment)
21 Furnace space 23 Muffle (outer wall)
28 Oxygen supply passage 29 Outside the furnace space 35 Heater (heating means)
40 Exhaust blower (furnace atmosphere adjustment means)
46 Exhaust passage 49 Oxygen concentration sensor (measuring means)
49a Measuring element 50 ECU (control means)
51 Input Unit 52 Output Unit 100 Honeycomb Molded Body 101 Cell 102 Cell Wall 110 Honeycomb Fired Body 120 Honeycomb Structure 140 Heating Furnace (Second Embodiment)
146 Measurement exhaust passage (exhaust passage)
160 Heating furnace (third embodiment)
G1 Degreasing jig

Claims (16)

A heating furnace for calcining an object to be heated,
A furnace space in which the heating object is disposed;
Heating means for raising the temperature of the furnace space;
A part of the outer wall around the inner space of the furnace is opened, and an oxygen supply passage for introducing a gas containing oxygen into the inner space of the furnace;
An exhaust passage connected to the furnace space and exhausting the gas in the furnace space to the outside of the furnace space;
A heating furnace, comprising: a measuring unit that is disposed in the exhaust passage and measures characteristics of the gas passing through the exhaust passage. The heating furnace according to claim 1, wherein the gas in the furnace space is constantly discharged out of the furnace space. ^3. The heating furnace according to claim 1, wherein a flow rate of the gas passing through the exhaust passage is 10 to 100 m ³ / h (Normal). The heating furnace according to any one of claims 1 to 3, wherein the measuring means is a gas concentration sensor. The heating furnace according to claim 4, wherein the measuring means is an oxygen concentration sensor. A control unit having an input unit for inputting a measurement value measured by the measurement unit and an output unit for outputting a control signal;
Furnace atmosphere adjustment means that operates in response to a control signal output from the output unit based on the measured value,
The heating furnace according to any one of claims 1 to 5, wherein a characteristic of a gas in the furnace space is adjusted by operating the furnace atmosphere adjusting means based on the control signal. The heating furnace according to any one of claims 1 to 6, wherein the heating object is a kneaded material in which inorganic particles and an organic material are kneaded. The heating furnace according to claim 7, wherein the organic substance is removed from the heating object by heating. The heating furnace in any one of Claims 1-8 used for the degreasing | defatting of the said heating target object. The heating object is a columnar honeycomb formed body in which a raw material composition containing a ceramic raw material and an organic material is formed, and a large number of cells are arranged in parallel in the longitudinal direction with a cell wall therebetween. A heating furnace according to any one of the above. Forming a raw material composition containing a ceramic raw material and an organic material, and forming a columnar honeycomb formed body in which a number of cells are arranged in parallel in the longitudinal direction across the cell wall; and
A degreasing step of heating the honeycomb formed body in a heating furnace to remove the organic matter in the honeycomb formed body to produce a honeycomb degreased body;
A method for producing a honeycomb structure comprising the honeycomb fired body, comprising a firing step of firing the honeycomb degreased body to produce a honeycomb fired body,
The heating furnace used in the degreasing step is
A furnace space in which the honeycomb formed body is disposed;
Heating means for raising the temperature of the furnace space;
A part of the outer wall around the inner space of the furnace is opened, and an oxygen supply passage for introducing a gas containing oxygen into the inner space of the furnace;
An exhaust passage connected to the furnace space and exhausting the gas in the furnace space to the outside of the furnace space;
A method for manufacturing a honeycomb structure, comprising: a measuring unit that is disposed in the exhaust passage and measures characteristics of the gas passing through the exhaust passage. The method for manufacturing a honeycomb structured body according to claim 11, wherein in the degreasing step, the gas in the furnace space is always discharged out of the furnace space. In the degreasing step, the flow rate of the gas passing through the exhaust ^{passage, 10~100m} 3 / h (Normal) a method for manufacturing a honeycomb structure according to claim 11 or 12. The method for manufacturing a honeycomb structured body according to any one of claims 11 to 13, wherein the measuring means is a gas concentration sensor. The method for manufacturing a honeycomb structured body according to claim 14, wherein the measuring means is an oxygen concentration sensor. The heating furnace includes a control unit having an input unit to which a measurement value measured by the measurement unit is input and an output unit for outputting a control signal;
Furnace atmosphere adjustment means that operates in response to a control signal output from the output unit based on the measured value,
The method for manufacturing a honeycomb structured body according to any one of claims 11 to 15, wherein the characteristics of the gas in the furnace space is adjusted by operating the furnace atmosphere adjusting means based on the control signal.

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