JP2009236412A - Continuous firing furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a continuous firing furnace for preventing adhesion of binder components to an inner face of an ejector forcibly exhausting atmosphere gas of a furnace interior containing the binder components. <P>SOLUTION: In the continuous firing furnace with the ejector 9 attached to an atmosphere gas exhaust passage 8a exhausting the atmosphere gas in the furnace containing the binder components generated by a treated product to a furnace exterior, it is composed by providing an air heating means 11 for heating air to a temperature higher than a condensation temperature of the binder components to an air supply passage 10 supplying air to the ejector 9. By supplying the air heated to the temperature higher than the condensation temperature of the binder components by the air heating means 11 to the ejector 9, the binder components in the atmosphere gas forcibly exhausted to the furnace exterior is cooled, and condensation to the inner face of the ejector 9 is prevented. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a continuous firing furnace, and in particular, has been improved so that the binder component does not condense on the inner surface of the ejector for forcibly exhausting the atmospheric gas in the furnace containing the binder component generated from the article to be processed. The present invention relates to a continuous firing furnace.

  When the article to be treated containing the binder is baked in a continuous firing furnace, a binder component is generated from the article to be treated, so the atmosphere gas containing the binder component is exhausted out of the furnace and treated with a catalyst, or Then, after treating with a catalyst in the furnace, it is exhausted to the outside of the furnace. In that case, the atmospheric gas containing the binder component or the atmospheric gas treated with the catalyst in the furnace is generally exhausted by the venturi effect by supplying air to the ejector provided in the exhaust pipe. is there.

The present applicant also provides a catalyst unit for treating the binder component in the catalyst activation temperature region in the furnace, efficiently treats the binder component in the furnace to save energy, and uses the ejector provided in the exhaust pipe to go outside the furnace. A continuous firing furnace configured to forcibly exhaust has already been proposed (Patent Document 1).
JP 2007-139289 A

  However, in the case of forced evacuation with an ejector, there is no problem if the binder component has already been treated with a catalyst in the furnace as in the continuous firing furnace of Patent Document 1, but the untreated binder component was included. When the atmospheric gas is forcibly exhausted with an ejector, the following problems occur.

  That is, in the conventional continuous firing furnace, ambient air is used as it is as air supplied to the ejector, so that the forcedly exhausted atmosphere gas containing the binder component is cooled by the air supplied to the ejector. As a result, the binder component is condensed, and the binder component B adheres to the inner surface in front of the air discharge nozzle 9a of the ejector 9 as shown in FIG. When the binder component B adheres in this manner, exhaust failure or exhaust clogging occurs, and the concentration of the binder component in the atmospheric gas in the furnace increases, so that the obtained fired product becomes a defective product.

  The present invention has been made to cope with the above problem, and the problem to be solved is that the binder component is condensed and adhered to the inner surface of the ejector forcibly exhausting the atmospheric gas in the furnace containing the binder component. An object of the present invention is to provide a continuous firing furnace capable of preventing the above.

  In order to solve the above problems, a continuous firing furnace according to the present invention is a continuous firing furnace in which an ejector is attached to an atmosphere gas exhaust path for exhausting the atmosphere gas in the furnace containing the binder component generated from the product to be processed out of the furnace. In the above, an air heating means for heating the air to a temperature higher than the condensation temperature of the binder component is provided in an air supply path for supplying air to the ejector.

  In the continuous firing furnace of the present invention, it is preferable that the air heating means is a heater provided in the air supply passage, has an internal passage through which air flows, and an electric heat source is built in the internal passage. .

  As in the continuous firing furnace of the present invention, the air supply passage for supplying air to the ejector is provided with air heating means for heating the air to a temperature higher than the condensation temperature of the binder component. Since air heated to a temperature higher than the condensation temperature can be supplied, the binder component in the atmospheric gas forcibly exhausted outside the furnace is prevented from being cooled inside the ejector and adhering to the inner surface. Therefore, exhaust defects and clogging due to the adhesion of the binder component on the inner surface of the ejector are eliminated, and the concentration of the binder component in the atmosphere gas in the furnace is kept extremely low, preventing the occurrence of defective quality fired products. can do.

  And if the air heating means is a heater provided in the air supply passage and has an internal passage through which air flows, and an electric heat source is built in this internal passage, it can be easily obtained as a commercial product, Since air can be heated above the condensation temperature of the binder component in a short time, adhesion of the binder component on the inner surface of the ejector can be reliably prevented.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a partial side view of a continuous firing furnace according to an embodiment of the present invention, FIG. 2 is a partial plan view of the continuous firing furnace, FIG. 3 is a front view of the continuous firing furnace, and FIG. 5 is a schematic explanatory view of a heater (spot heater) used as an air heating means, and FIG. 6 is a partially cutaway view of an ejector of the same continuous firing furnace in which air heated by the air heating means is supplied.

  In this continuous firing furnace, as shown in FIG. 1, a heating chamber 2 is provided inside an exterior wall 1, and a heating muffle 3 is installed through the heating chamber 2. The upper, lower, left, and right walls of the heating chamber 2 are made of a thick plate-like hard heat insulating material obtained by vacuum-forming ceramic fibers, and an electric heater is incorporated therein.

  The muffle 3 that penetrates the heating chamber 2 is a cylinder made of heat-resistant steel, and the front end portion 3a of the muffle 3 protruding forward (leftward in FIG. 1) from the heating chamber 2 is a purge chamber on the inlet side. The purge gas is supplied so that the atmospheric gas and the outside air inside the muffle 3 are blocked. Although not shown, a cooling muffle made of heat-resistant steel having a height lower than that of the muffle 3 is connected to the rear end of the muffle 3, and the rear end of the cooling muffle 3 is connected to the outlet side. It is a purge chamber.

  An endless mesh conveyor belt 4 passes through the heating muffle 3 and the cooling muffle, and the workpiece W (see FIG. 3) is placed on the conveyor belt 4 and the heating muffle 3 and the cooling muffle 3 are cooled. While moving through the inside of the muffle, the firing process and the cooling process are performed with a predetermined temperature profile.

  A combustion device 5 having a built-in catalyst unit is installed beside the continuous firing furnace, and atmospheric gas containing the binder component exhausted from the heating muffle 3 is burned by the combustion device 5. Released to the outdoors.

  As shown in FIGS. 1 to 3, the top wall portion 1 a of the exterior wall 1 of the continuous firing furnace is connected to the heating muffle 3 to capture the atmospheric gas containing the binder component in the muffle 3. A collection box 6 that collects and an exhaust box 7 that faces the collection box are provided. As shown in FIGS. 2 and 4, four atmospheric gas exhaust passages 8a are provided in parallel between both boxes 6 and 7, and each of the atmospheric gas exhaust passages 8a includes an ejector. 9 is provided. The exhaust box 7 is connected to a tee pipe 5a (see FIG. 4) below the combustion device 5 through an atmospheric gas exhaust path 8b.

  As shown in FIG. 4, an air supply passage 10 for supplying air to the ejector 9 is provided by branching from an air introduction passage 16 for introducing air to the combustion device 5, and the tip portion thereof is divided into four. It branches and is connected to the air discharge nozzles 9a (see FIG. 6) inside the four ejectors 9. The air introduction path 16 is provided with a flow meter 12, a solenoid valve 13, a regulator 14, a ball valve 15, and the like, and the air supply path 10 is also provided with a flow meter 17, so that air is controlled in flow rate. The fuel is supplied to the combustion device 5 and the ejector 9.

  The air supply passage 10 is provided with a heater 11 that heats the air to a temperature higher than the condensation temperature of the binder component in the atmospheric gas forcedly exhausted as an air heating means. It is attached to a support formed on the side of the box 6.

  As shown in FIG. 5, the heater 11 has an internal passage 11a through which air flows, an electric heat source 11b is built in the internal passage 11a, and a temperature sensor 11d provided in the vicinity of the air discharge port 11c. In addition, the temperature of the air flowing through the discharge port 11c is detected, and the temperature of the electric heat source 11b is detected by the temperature sensor 11e provided in the vicinity of the electric heat source 11b, and the temperature of the air flowing through the internal passage 11a is controlled while controlling the temperature of the electric heat source 11b. And is discharged from the discharge port 11c.

  Such a heater 11 is easily available in the market under the trade name of a spot heater, and a heater having an output of about 3 kW can heat air to 500 to 600 ° C. in a short time. Therefore, for example, when a product to be processed formed of graphite powder is fired, since a binder component is generated at 280 to 500 ° C., the air supplied to the ejector 9 is heated to a temperature higher than the condensation temperature of the binder component. Can do.

  In the continuous firing furnace configured as described above, the workpiece W is placed on the transport belt 4 and transported through the heating muffle 3 and the cooling muffle, and the firing process and the cooling process are performed at a predetermined temperature profile. Is done. At that time, the atmospheric gas containing the binder component generated from the workpiece W inside the heating muffle 3 is collected in the collection box 6 and forcedly exhausted by each ejector 9 through the atmospheric gas exhaust path 8a. Then, the gas is sent from the exhaust box 7 to the combustion device 5 through the atmospheric gas exhaust passage 8b, and is burned and released to the outdoors.

  On the other hand, a part of the air sent to the combustion device 5 passes through the air supply passage 10 and is instantaneously heated to a temperature higher than the condensation temperature of the binder component by the air heating means (spot heater) 11 in the middle. It is supplied to each ejector 9, is discharged from the discharge nozzle 9a inside each ejector 9, and the atmospheric gas containing the binder component in the atmospheric gas exhaust path 8a is forcibly exhausted as described above due to its venturi effect. At this time, since the air discharged from the discharge nozzle 9a of each ejector 9 is heated to a temperature higher than the condensation temperature of the binder component by the spot heater 11, the binder component is condensed inside the ejector as shown in FIG. Thus, it does not adhere to the inner surface of the ejector 9. Therefore, exhaust failure and exhaust clogging due to adhesion of the binder component to the inner surface of the ejector 9 are eliminated, and the atmospheric gas containing the binder component inside the heating muffle 3 is efficiently exhausted, and the binder component inside the muffle 3 Since the concentration is kept extremely low, it is possible to prevent occurrence of defective quality fired products.

  As described above, the continuous firing furnace of the present invention has been described with reference to typical embodiments. However, the present invention is not limited only to this embodiment. For example, the combustion heat of the combustion device 5 is used as air heating means. The air supplied to the ejector 9 may be heated to a temperature higher than the condensation temperature of the binder component, or the air may be heated by using the spot heater 11 and the combustion heat of the combustion device 5 together. Good.

  In addition, as a means for preventing the adhesion of the binder component to the inner surface of the ejector, for example, a method of heating the outer surface of the ejector 9 with a sheathed heater or the like is conceivable, but in that case, the adhesion to the inner surface of the ejector 9 is prevented. Even if it can be done, it cannot prevent the adhesion to the discharge nozzle 9a. On the other hand, when the air itself is heated by the air heating means 11 as in the continuous firing furnace of the present invention, adhesion to the inner surface of the ejector 9 and adhesion to the discharge nozzle 9a can be sufficiently prevented. This is far more effective than heating the outer surface of the ejector.

It is a partial side view of the continuous baking furnace which concerns on one Embodiment of this invention. It is a partial top view of the continuous baking furnace. It is a front view of the continuous firing furnace. It is an airflow figure of the continuous baking furnace. It is a schematic explanatory drawing of the heater (spot heater) used as an air heating means. It is a partially broken figure of the ejector of the same continuous baking furnace in which the air heated with the air heating means is supplied. It is a partially broken figure of the ejector of the conventional continuous baking furnace in which normal temperature air is supplied.

Explanation of symbols

2 Heating chamber 3 Heating muffle 4 Conveyor belt 6 Collection box 7 Exhaust box 8a, 8b Atmospheric gas exhaust path 9 Ejector 9a Air discharge nozzle 10 Air supply path 11 Air heating means (spot heater)
16 Airway

Claims (2)

In a continuous firing furnace in which an ejector is attached to an atmosphere gas exhaust path for exhausting the atmosphere gas in the furnace containing the binder component generated from the product to be processed outside the furnace,
A continuous firing furnace characterized in that air heating means for heating air to a temperature higher than the condensation temperature of the binder component is provided in an air supply path for supplying air to the ejector.   The continuous heating according to claim 2, wherein the air heating means is a heater provided in the air supply passage, and has an internal passage through which air flows, and an electric heat source is built in the internal passage. Firing furnace.

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