JPH0391691A - Crucible furnace device - Google Patents

Abstract

PURPOSE:To lower the noise, reduce NOx and prolong the life of a crucible by a method wherein at the downstream side of a primary mixture chamber a panel-shaped catalyst layer is installed and at its center part a secondary mixture tube with an ejecting hole at its pointed end is projected to form a combustion part and one or a plurality of such combustion parts are installed at the side walls of the crucible furnace. CONSTITUTION:At the center of a panel-shaped catalyst layer 2 a secondary mixture tube with an ejecting hole 3 at its pointed end is projected to constituted a combustion part 5 and it is so constituted that one or a plurality of the parts 5 are installed at the side walls 7 of a crucible furnace 6. Here, when the primary mixture of fuel gas and air is introduced into a primary mixture chamber 1 from an introducing part 13 for the mixture and reaches a panel- shaped catalyst layer 2, the primary mixture is ignited by an ignitor 11 to form fire flames on the overall surface of the layer 2 and the temp. of the layer 2 is kept at the range of 600-1000 deg.C. Thereby, the noise is controlled so as to be low and the generation of NOx is minimized and the life of the crucible can be greatly prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a crucible furnace device used for melting and holding aluminum ξ.

(Prior art and problems) In Fig. 4, the inner surface of the crucible furnace main body a is lined with a refractory material, and the crucible C is lined with a refractory material inside the refractory material and maintained at a constant distance. It is installed in The crucible C contains an object to be heated d such as an aluminum block. A burner e is installed tangentially on the side wall of the crucible furnace main body a, and a high-speed injection burner is mainly used as the burner e.

The high-temperature combustion gas f burned in the burner e is injected into the furnace at high speed, swirls at high speed in the annular path g between the crucible C and the refractory material, and forces the material to be heated inside the crucible C to undergo controlled convection. It is designed to heat the outer surface of the crucible C as uniformly as possible.

Combustion gas f, which has ascended through the annular passage g between the crucible C and the refractory material, is exhausted from the exhaust port in the upper part of the furnace body.

Furthermore, some are equipped with an air preheater at the exhaust port to preheat the combustion air and recover heat.

Such conventional technology uses a normal burner and requires high-load combustion to melt aluminum lumps and the like. For this reason, the noise caused by combustion noise is large, and it is difficult to reduce NOx in the exhaust gas below a certain value, which is usually 60 to 100 p.
The limit is about pa+.

Further, the combustion gas combusted in the burner is ejected into the furnace at high speed in order to uniformly and rapidly heat the crucible.

For this reason, the high-temperature, high-velocity combustion gas directly contacts the crucible, causing the life span of the crucible (6 months to 1 year) to be shortened compared to normal.

The purpose of the present invention is to solve the above-mentioned problems, such as (1) high noise, (2) difficulty in reducing NOx, and (2) short life of the crucible.

(Means for solving the problem) In FIG. 1, reference numeral 1 indicates a primary air-fuel mixture chamber, and 2 indicates a panel-shaped catalyst layer provided on the downstream side thereof. A combustion section 5 is constructed by protruding from the center of the panel-shaped catalyst layer 2 a secondary air mixture pipe 4 having an ejection hole 3 at its tip. One or more combustion units 5 having such a configuration are provided on the side wall 7 of the crucible furnace 6.

The device according to claim 2 corresponds to FIG. 2, and the entire combustion section 5 is configured to be small, and the combustion section 5 is installed in a combustion completion chamber 9 provided with a jet nozzle 8 having a tapered configuration. Put it in,
It has a configuration in which the spout 8 is opened into the crucible furnace 6,
In the third aspect of the present invention, the temperature of the panel-shaped catalyst layer 2 is set at 60°C.
The configuration is such that the temperature is maintained at 0 to 1000°C, and the configuration according to claim 4 has a primary mixture passage 10 on the outer periphery of the primary mixture chamber 1.
The configuration described in item 5 is a configuration in which the ejection holes 3 provided in the primary air mixture pipe 4 are provided in the lateral direction. The panel-shaped catalyst layer 2 described above may be made of, for example, platinum, palladium, or a mixture thereof.

(Function) In FIG. 1, when the primary mixture of fuel gas and air is introduced into the primary mixture chamber 1 from the primary mixture introduction part 13 and reaches the panel-shaped catalyst layer 2, the primary mixture is It is ignited by the igniter 11 to form a flame over the entire surface of the panel-shaped catalyst layer 2, and maintains the temperature of the catalyst layer 2 in the range of 600 to 1000°C. This temperature is maintained by detecting the temperature of the catalyst layer 2 with the temperature detector 14 and controlling the combustion amount. In this state, the secondary mixer is introduced into the secondary mixer tube 4,
When it is ejected laterally from the ejection hole 3 at the tip, the temperature of the panel-shaped catalyst layer 2 has reached 600 to 1000°C, so the heat immediately causes a reaction and starts combustion.

According to the present invention, since lean fuel combustion is performed in the panel-shaped catalyst layer 2, there is no local overheating, and
Since low-temperature combustion of 1000°C is performed, nitrogen oxides (N
Ox) generation can be suppressed to a minimum, and at the same time, low-noise combustion can be realized by the lean fuel combustion. Also,
Combustion using the secondary air-fuel mixture is combustion surrounded by the catalyst layer 2, that is, combustion that takes place in an atmosphere within the above temperature range. It is a short flame. Second, the secondary air is sent to the nozzle 3
Since the combustion is carried out by injecting the fuel into the surrounding area, it is possible to achieve low NOx combustion and low noise combustion without local overheating due to the diffusion of the air-fuel mixture.

Furthermore, since the crucible 12 is heated mainly by radiant heat from the panel-shaped catalyst layer 2, uniform heating can be performed by radiant heating from a wide area, and there is no direct contact with the flame, so the life of the crucible 12 can be extended. can be significantly improved. In addition, the amount of heat required for the crucible 12 differs depending on whether it is melting aluminum or holding it, but in the case of holding the molten metal, for example, it is necessary to stop injecting the secondary mixture from the secondary mixer pipe 4. It is only necessary to control the injection amount, and the device of the present invention can be used for both melting and holding. As a result, the temperature of the catalyst layer 2 becomes lower than that of the catalyst layer 2.
．． The temperature required to maintain combustion at (600 to 1000
℃), there is no need to increase the temperature of the catalyst layer 2 unnecessarily, and there is an advantage that the catalyst life can be extended.

FIG. 2 shows another embodiment in which the combustion section 5 is constructed to be small overall, and is inserted into a combustion completion chamber 9 equipped with a jet nozzle 8. 8 is opened into the crucible furnace 6.

In this embodiment, the combustion gas generated as described above in the combustion section 5 is completely combusted in the combustion completion chamber 9 and ejected from the jet port 8, and circulates around the outer circumference of the crucible 12 to heat the crucible 12. Since the circulating gas is a heat flow that has completed combustion, the flame will not directly hit the crucible 12.
The life of the crucible 12 can be extended. Embodiments of such a configuration can also provide the various advantages described above by simply replacing the burner installed in a conventional crucible furnace apparatus.

FIG. 3 is an enlarged explanatory view of the combustion section, and shows an embodiment in which a primary mixture flow path 13 is provided on the outer periphery of the primary mixture chamber 1 of the combustion section 5. With this configuration, the primary mixture can be preheated. I can do it.

(Effects of the Invention) As described above, the present invention makes it possible to suppress the generation of nitrogen oxides to a minimum with low noise, and also prevents the flame from directly hitting the crucible due to its unique configuration. This has various effects such as greatly improving the life of the crucible.

[Brief explanation of drawings]

FIG. 1 is a detailed explanatory diagram of the present invention, FIG. 2 is a cross-sectional explanatory diagram of another embodiment of the present invention, FIG. ) is an explanatory front view. Fig. 4 is a cross-sectional explanatory view of a conventional crucible furnace. Reference numeral 1...-skin aeration chamber, 2... panel-shaped catalyst layer,
3... Ejection hole, 4... Secondary mixture pipe, 5... Combustion section, 6... Crucible furnace, 7... Side wall, 8... Ejection port, 9... Combustion completion chamber , 10...-Skin Aikido, 1
DESCRIPTION OF SYMBOLS 1... Igniter, 12... Crucible, 13... - skin aiki introduction part, 14... Temperature detector. 15...gL flow 1 anti-Fig. 3 (A) Fig.

Claims (5)

[Claims] (1) A panel-shaped catalyst layer is provided on the downstream side of the primary mixture chamber,
A crucible furnace device comprising one or more combustion sections on the side wall of the crucible furnace, each of which has a combustion section formed by protruding a secondary air mixture pipe having an ejection hole at its tip from the center of the panel-shaped catalyst layer. (2) A crucible furnace device in which the combustion section is inserted into a combustion completion chamber provided with a jet nozzle having a tapered configuration, and the jet nozzle is opened into the crucible furnace. (3) The temperature of the panel-shaped catalyst layer is 600 to 1000°C.
3. The crucible furnace apparatus according to claim 1, wherein the crucible furnace apparatus is maintained within a range of . (4) The crucible furnace apparatus according to claim 1, 2 or 3, wherein a primary mixture passage is provided on the outer periphery of the primary mixture chamber. (5) Claim 1, 2, 3, or 4, wherein the ejection section provided in the primary air mixture pipe is provided so as to eject the secondary air mixture in a lateral direction.
The crucible furnace apparatus described.