JP2996589B2 - Thermal storage combustion method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat storage combustion method and apparatus using a heat storage body.

[0002]

2. Description of the Related Art A regenerative combustion method in which a pair of regenerators is attached to a furnace body, heat is stored in one of the regenerators through combustion exhaust gas, and preheating is performed in the other regenerator through combustion air is known as a heat storage combustion method. Has been known for some time. Recently, a technology has been developed in which the air switching device is switched in a short cycle of 20 to 30 seconds to reduce the heat loss of exhaust gas and increase the temperature of combustion air.

However, when this heat storage combustion method is applied to a reduction firing furnace used for firing ceramic products, reducing combustion exhaust gas discharged from the furnace maintained in a reducing atmosphere is flammable. If the air is leaking even slightly in the air switching device, the combustion exhaust gas comes into contact with the leaked air, burns, and may damage the air switching device. Further, there is a possibility that the combustion exhaust gas comes into contact with air in the exhaust duct and burns, causing the exhaust duct to glow red. Furthermore, even when the exhaust gas is discharged without burning in the exhaust duct, there is a possibility that carbon monoxide in the combustion exhaust gas may deteriorate the surrounding working environment.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems. Even when the heat storage combustion method is applied to a reduction firing furnace, there is a possibility that an air switching device or the like may be damaged due to combustion of combustion exhaust gas. The present invention has been made to provide a heat storage combustion method and apparatus that do not cause deterioration of the working environment.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a heat storage combustion method according to the present invention is a step of preheating heat by storing combustion heat in one heat storage and passing combustion air through the other heat storage. The method is characterized in that air is injected into a reducing combustion exhaust gas discharged from a furnace maintained in a reducing atmosphere, burned, and then passed through a heat storage body. Further, the heat storage combustion device of the present invention is provided with a pair of heat storage bodies through which combustion exhaust gas and combustion air alternately pass, and a furnace body whose interior is maintained in a reducing atmosphere and which is closer to the furnace body than these heat storage bodies. Is provided with an air injection nozzle.

[0006]

According to the regenerative combustion method and apparatus of the present invention, the combustion exhaust gas and the combustion air are alternately passed through a pair of regenerators attached to the furnace body, and the heat is applied to the regenerator from the exhaust gas. As in the past, it is possible to preheat combustion air and recover waste heat to achieve excellent thermal efficiency. However, in the present invention, an air injection nozzle is provided on the furnace body side with respect to these heat accumulators, and air is injected into the reducing combustion exhaust gas discharged from the furnace maintained in the reducing atmosphere and burned. Because of the passage, the combustible combustion exhaust gas burns before reaching the air switching device. For this reason, the air switching device is not damaged and does not burn in the exhaust duct. Further, since the discharged gas does not contain carbon monoxide or the like, there is no possibility that the working environment is deteriorated. In addition, the combustion heat generated when the combustion exhaust gas is burned heats the heat storage body, so that the thermal efficiency can be further improved as compared with the related art.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 shows a first embodiment of the present invention, wherein 1 is a furnace body in which the inside of the furnace is maintained in a reducing atmosphere, 2 and 2 are air passages provided on both sides thereof, and 3 and 3 are each air. These are heat storage bodies arranged inside the flow paths 2 and 2, respectively. In the embodiment, a ceramic honeycomb structure made of a ceramic material such as cordierite is used as the heat accumulator 3, but other heat accumulators such as ceramic beads may be used.

Each of the air passages 2 is connected to an air switching device 4. In the state shown in FIG. 1, the air switching device 4 supplies combustion air supplied from the fan 5 to the right air passage 2 and exhausts combustion exhaust gas from the left air passage 2, and conversely. The switching operation is performed so that the combustion air supplied from the fan 5 is supplied to the left air flow path 2 and the combustion exhaust gas from the right air flow path 2 is exhausted. This switching operation is performed as described above.
It is repeated in a short cycle of about 30 seconds.

Fuel injection nozzles 6 are provided at the connection between the air passages 2 and the furnace body 1, respectively. The fuel injection nozzles 6 are connected to the air switching device 4 respectively. It is connected to an interlocking fuel switching device 7. For this reason, combustion occurs inside the furnace body 1 by injecting fuel from the fuel injection nozzle 6 of the air flow path 2 on the side to which combustion air is supplied as shown in FIG. 1, but in the present invention, in a continuous furnace, In a batch furnace, reduction firing is performed according to the firing process in a batch furnace, and the inside of the furnace body 1 is maintained in a reducing atmosphere.

The high-temperature reducing flue gas generated by such combustion passes through the air passage 2 on the opposite side, passes through the air switching device 4 and is exhausted to the outside. Since the heat storage element 3 is disposed in the
Is heated and then exhausted. Next, when the combustion air is supplied to the furnace body 1 from the air flow path 2, the combustion air is preheated by the heated regenerator 3.

The above construction is the same as that of the conventional heat storage combustion apparatus, but in this embodiment, the air injection nozzle 8 is provided on the furnace body 1 side of each of the heat storage bodies 3 and 3. Therefore, the air flow path 2
Flammable exhaust gas exhausted from the air injection nozzle 8
The fuel is burned by air injected from the air and passes through the heat storage body 3. Therefore, even if air leaks in the air switching device 4, there is no risk of burning in the air switching device 4 and no combustion occurs in the exhaust duct. In addition, since the heat generated by the combustion is also given to the regenerator 3, the heat efficiency is higher than when the combustible combustion exhaust gas is exhausted as it is, and the carbon monoxide in the combustion exhaust gas is exhausted to the outside while being consumed. Therefore, there is no risk of deteriorating the environment.

FIG. 2 shows a second embodiment of the present invention, and shows an example in which the heat storage body 3 is also arranged on the furnace body 1 side from the air injection nozzle 8. In this case, the same operation and effect as those of the first embodiment are exerted, but the air injection nozzle 8 is controlled by the second air switching device 9 and provided in the air passage 2 on the side where the combustion exhaust gas flows. If air is injected only from the air injection nozzle 8 that has been used, the amount of air that is wastefully supplied from the air injection nozzle 8 into the combustion air can be reduced. In addition, if these heat storage bodies 3 support an oxidation catalyst, the flammable combustion exhaust gas completely burns when passing through the heat storage bodies 3, so that more preferable results can be obtained.

Next, in order to confirm the effect of the present invention, a firing experiment was conducted using tableware and a shuttle kiln for firing tiles, which are typical products to be reduced and fired in the ceramic industry. The shuttle kiln used had an inner volume of 2.9 m ³ using LNG as fuel, and when only a normal burner was installed, when a conventional heat storage combustion device was installed, the heat storage combustion with an air injection nozzle of the present invention was used. 3 when the device is installed
The fuel consumption and the concentration of carbon monoxide in the exhaust gas were compared for the elderly. Table 1 shows the results.

As is clear from the data shown in Table 1, according to the present invention, the fuel consumption is the lowest and the concentration of carbon monoxide in the exhaust gas is low both when the tableware is baked and when the tile is baked. Is zero, indicating that the combustion is complete.

[0015]

[Table 1]

[0016]

As described above, according to the present invention, even when the regenerative combustion method is applied to the reduction firing furnace, the combustion exhaust gas is burned inside the air switching device of the exhaust system or the like, and the air switching device is used. And the like, and the exhaust can be performed with the carbon monoxide concentration set to zero, so that the working environment does not deteriorate. In addition, since heat generated by combustion of combustible combustion exhaust gas can also be recovered by the heat storage body, there is an advantage that fuel consumption can be reduced and thermal efficiency can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Furnace body, 2 air flow paths, 3 heat storage bodies, 4 air switching devices, 5 fans, 6 fuel injection nozzles, 7 fuel switching devices, 8 air injection nozzles, 9 second air switching devices

Claims (5)

(57) [Claims] In a regenerative combustion method in which a step of preheating heat by passing combustion exhaust gas through one regenerator and preheating by passing combustion air through the other regenerator is repeated, the regenerative discharge discharged from the furnace maintained in a reducing atmosphere is performed. A heat storage combustion method characterized by injecting air into a combustion exhaust gas and burning it, and then passing the heat storage body. 2. A furnace body whose inside is maintained in a reducing atmosphere,
A heat storage and combustion device comprising a pair of regenerators through which combustion exhaust gas and combustion air alternately pass, and an air injection nozzle provided on a furnace body side of the regenerators. 3. The heat storage combustion device according to claim 2, wherein the heat storage body is a ceramic honeycomb structure. 4. The heat storage combustion device according to claim 2, wherein the heat storage body supports an oxidation catalyst. 5. The heat storage combustion device according to claim 2, wherein a heat storage body is also arranged on the furnace body side from the air injection nozzle.