JP3438354B2 - Thermal storage combustion device - 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 and combustion apparatus applicable to various industrial furnaces, and more specifically to reducing the emission of nitrogen oxides (NOx).

[0002]

2. Description of the Related Art At least one pair of a combination of a burner and a heat accumulator is provided on a furnace wall, and the burners are burned alternately.
By passing the combustion gas of one burner to the other heat storage unit and discharging it to the outside of the furnace, the exhaust heat of the combustion gas is recovered in this heat storage unit, and the combustion air is passed through the heat storage unit by alternate combustion. The heat storage combustion device in which the combustion air is preheated by the recovered heat and supplied to the furnace is effective in utilizing the exhaust heat of the combustion gas and the energy saving effect is remarkable. It is used as a heat source for various industrial furnaces such as furnaces.

[0003]

By the way, the biggest problem with this heat storage and combustion device is that nitrogen oxides (NOx) are easily generated in the furnace because the preheating temperature of the combustion air is high, and the NOx level of the exhaust gas is high. It was high and there was a risk of air pollution.

One conventional method for improving the problem is to consider the structure and arrangement of the burner so that the fuel gas blown into the furnace and the combustion air are slowly mixed in the furnace. One of them is to blow the fuel gas directly into the furnace, and one of them is to limit the amount of combustion air supplied into the furnace.

In this heat storage and combustion apparatus, a small amount of air is constantly supplied to the burner through the burner nozzle in order to prevent the burner from being overheated and damaged by the combustion gas during its rest. As a result, the oxygen concentration in the furnace increased, which caused nitrogen oxides to be generated in the furnace.

[0006]

In view of the above, the present invention is designed to prevent a burner nozzle from being overheated by supplying a part of the combustion gas that has passed through the regenerator to a dormant burner nozzle in the above heat storage and combustion device. It is characterized by.

The present invention also provides the above heat storage and combustion device,
It is characterized in that the burner nozzle in the idle state is supplied with the combustion gas and the fuel gas in an oxygen equivalent amount.

[0008]

[Operation] By supplying the combustion gas whose temperature has decreased by passing through the heat accumulator to the dormant burner nozzle, the burner nozzle can be cooled, and since the oxygen concentration of the combustion gas is low, nitrogen oxides are generated in the furnace. Make it difficult. Further, by supplying the fuel gas together with the above-mentioned combustion gas to the burner nozzle at rest, oxygen contained in the combustion gas can be eliminated by the combustion reaction and the generation of nitrogen oxides can be suppressed more reliably.

[0009]

EXAMPLE An example of the heat storage and combustion apparatus according to the present invention will be described below with reference to the piping system diagram shown in FIG. In the figure, 1 is a furnace body having openings 2a and 2b on opposite side walls, 3a,
Reference numeral 3b is a burner installed outside the openings 2a and 2b. Reference numerals 4a and 4b are burner nozzles provided in the burners 3a and 3b. Reference numerals 8a and 8b are pilot burners provided immediately before the burner nozzles 4a and 4b in the burners 3a and 3b.

Reference numerals 9a and 9b denote heat accumulators provided on one side of the combustion chambers 3a and 3b and made of a gas permeable solid.
9b includes a blower 10, a flow control valve 11, and an on-off valve 12.
Air supply passages 13a and 13b are provided so that combustion air can be supplied via a and 12b. Also 14a, 14
b is an exhaust passage, and the opening / closing valve 15 is provided in the exhaust passages 14a and 14b.
a, 15b are provided, the exhaust passages 14a, 14b are integrated with the exhaust passage 18, and a flow rate control valve 16 and a blower 17 are provided in the exhaust passage 18, respectively. Therefore, the combustion gas in the passage is transferred to the heat accumulators 9a and 9b, the exhaust passages 14a and 14b, and the on-off valve 1.
The blower 17 can be sucked through 5a, 15b, the exhaust passage 18, and the flow rate control valve 16. Also, blower 17
The combustion gas sucked by the exhaust gas passes through the exhaust passage 19 and the damper 22, and is exhausted into the atmosphere from the chimney 23.

Reference numeral 20 is a fuel control valve that controls the amount of fuel gas supplied to the burner nozzles 4a and 4b to control the temperature inside the furnace. The secondary side of the fuel control valve 20 is a feed gas pipe 21.
On-off valves 25a and 25b are provided on the supply gas pipes 21a and 21b, respectively. Further, the exhaust gas circulation path 26 is provided from one side of the damper 22 in the exhaust path 19.
a, 26b, and the burner nozzles 4a, 27b with the opening / closing valves 27a, 27b interposed in the exhaust gas circulation paths 26a, 26b.
Connect to 4b.

In this heat storage and combustion apparatus, however, one opening / closing valve 25a is opened so that the fuel gas is blown out into the combustion chamber 3a from the burner nozzle 4a, and the opening / closing valve 12a is opened into the combustion chamber 3a via the heat accumulator 9a. Combustion air is supplied and ignited by the pilot burner 8a to blow out combustion gas into the furnace through the opening 2a. Then, the on-off valve 15b is opened and sucked by the blower 17 through the exhaust passage 14b, so that the combustion gas in the furnace is sucked into the regenerator 9b through the other opening 2b and discharged to the outside through the exhaust passage 19 and the chimney 23. As a result, the combustion gas flows through the heat accumulator 9b and is heated by its exhaust heat. When the heat accumulator 9b is sufficiently heated, the on-off valves 25a, 12a, 15b are closed, and at the same time, the on-off valves 25b, 12b, 15a are opened to blow out the fuel gas from the burner nozzle 4b and blower 10
The combustion air sent under pressure is passed through the heat storage unit 9b to preheat the combustion air and supply the combustion air to the combustion chamber 3b, and the fuel gas is ignited by the pilot burner 8b to burn. The combustion gas is passed through the heat storage unit 9a and sucked and discharged from the blower 17, whereby the heat storage unit 9a is heated by the exhaust heat. When the heat accumulator 9a is sufficiently heated, the open / close state of each of the on-off valves is switched again and the fuel gas is blown out from the burner nozzle 4a. In this way, the burners 3a and 3b are alternately placed in a combustion state at regular intervals, and the exhaust heat of the combustion gas is recovered in the heat accumulators 9a and 9b, and the recovered heat is effectively used to preheat the combustion air.

The opening / closing valve 27a and the opening / closing valve 27b are simultaneously opened / closed at the time of opening / closing, and a part of the combustion gas sucked by the blower 17 is supplied to the dormant burner nozzle 4a or the burner nozzle 4b through the exhaust gas circulation paths 26a, 26b. Since this combustion gas has a low temperature due to heat recovery by passing through the regenerator 9a or the regenerator 9b, its overheating can be sufficiently prevented by supplying it to the burner nozzle at rest. Moreover, since it is a combustion gas, it has an advantage that it has a low oxygen concentration and is unlikely to become a factor for generating nitrogen oxides without increasing the oxygen concentration in the furnace even if it is blown into the furnace.
A cooler (not shown) may be provided in the exhaust gas circulation paths 26a and 26b to further forcibly lower the temperature of the combustion gas.

On the other hand, the embodiment shown in FIG.
Flow rate control valves 28a and 28b are provided in parallel with a and 25b,
The flow rate control valves 28a and 28b are connected to the exhaust gas circulation path 26, respectively.
It is set so as to open in proportion to the pressure of the combustion gas passing through a and 26b, and other configurations are similar to those of the embodiment of FIG. In this way, in this embodiment, the combustion gas is supplied to the dormant burner, and at the same time, the fuel gas is constantly replenished by the oxygen equivalent in the combustion gas through the flow rate control valves 28a and 28b, so that the oxygen content in the combustion gas is reduced. This prevents the oxygen concentration in the furnace from rising and reduces the risk of nitrogen oxides generation more thoroughly.

Although a pair of burners is provided on the left and right in these embodiments, a plurality of burners are further provided or the burner arrangement is taken into consideration so that combustion of the fuel gas in the furnace is slowed down. It is also possible to use a measure to suppress the generation of nitrogen oxides at the time of high temperature combustion such as.

[0016]

As described above, according to the present invention, at least a pair of burners provided on the furnace wall are alternately burned, and the combustion gas of one burner is passed to the heat storage device of the other burner so that the combustion gas In the heat storage combustion device that recovers the exhaust heat and preheats the combustion air, the combustion gas after passing through the regenerator is supplied to prevent overheating of the burner while the burner is stopped. N in the exhaust gas is suppressed by suppressing the production of nitrogen oxides without increasing the oxygen concentration in the furnace.
There is a beneficial effect of reducing the Ox level.

[Brief description of drawings]

FIG. 1 is a piping system diagram showing an embodiment of a heat storage and combustion device of the present invention.

FIG. 2 is a piping system diagram showing another embodiment of the heat storage and combustion device of the present invention.

[Explanation of symbols]

1 furnace body 2a, 2b opening 3a, 3b combustion chamber 4a, 4b burner 9a, 9b heat accumulator 10 Blower 11 Flow control valve 12a, 12b open / close valve 13a, 13b Air supply passage 14a, 14b exhaust path 15a, 15b open / close valve 16 Flow control valve 17 Blower 18 exhaust path 19 Exhaust path 20 Fuel control valve 21a, 21b Gas supply pipe 22 Damper 23 chimney 25a, 25b open / close valve 26a, 26b Exhaust gas circulation path 27a, 27b open / close valve 28a, 28b Flow rate control valve

Claims (2)

(57) [Claims] 1. A furnace wall is provided with at least one pair of a combination of a burner and a heat accumulator, and the burners are burned alternately.
By passing the combustion gas of one burner to the other heat storage unit and discharging it to the outside of the furnace, the exhaust heat of the combustion gas is recovered in this heat storage unit, and the combustion air is passed through the heat storage unit by alternate combustion. In the regenerative combustion device in which the combustion air is preheated by the recovered heat and supplied to the furnace, a part of the combustion gas that has passed through the regenerator is supplied to the dormant burner nozzle to prevent overheating of the burner nozzle. The heat storage and combustion device characterized in that 2. The heat storage combustion apparatus according to claim 1, wherein the burner which is at rest is supplied with the combustion gas and the fuel gas in an amount equivalent to the oxygen equivalent of the combustion gas.