JP3212002B2 - Low-nitrogen oxide alternating combustion method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alternating combustion method for producing low nitrogen oxides.

[0002]

2. Description of the Related Art An alternating combustion burner in which two burners having a heat storage layer are alternately burned as a set is used. When the combustion air passing through the bed is sufficiently preheated by the recovered heat, higher preheated air is obtained as compared with the indirect heat exchanger, and very high energy efficiency is obtained.

[0003]

The combustion method in the alternating combustion burner described above has a problem that the preheated air temperature is high and the concentration of nitrogen oxide (NOx) is high. To solve this, there is an exhaust gas recirculation method. Such exhaust gas recirculation method is to burn the exhaust gas forcibly lower the nitrogen partial pressure was introduced <br/> the air introducing portion or combustion part, these various facilities inevitably for exhaust gas introducing In addition, since the thermal efficiency decreases as the recirculation rate increases, there are various problems such as the necessity of controlling the recirculation rate in order to prevent the thermal efficiency from decreasing.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of storing heat in each of the burners of an alternating combustion burner in which two burners having a heat storage layer are alternately switched and burned as a set. The layer contains one of the fuel gases
A fuel gas mixing device for introducing the fuel gas into the combustion gas guide section from the heat storage layer to the inside of the furnace.
Providing a residual fuel gas ejection part for introducing fuel gas ,
By mixing a 10% to 25% of the fuel gas of the total combustion amount in the heat storage layer under heating conditions from the fuel gas introducing device, cause heat accumulation lean combustion reaction and combustion air come to flow into the heat storage layer After that, the remaining fuel gas in the combustion gas guide section
The fuel gas is introduced into the combustion gas guide via the residual fuel gas ejection part, and the combustion gas and the residual fuel gas from the heat storage lean combustion are used.
It is characterized in that combustion is completed by mixing .

[0005] Further, the present invention provides a fuel gas mixing device,
The fuel gas is installed at a low temperature in the heat storage layer under heat.
Is introduced .

[0006]

When the combustion air is introduced into the heated heat storage layer from the lower portion and at the same time , for example, 10% of the total fuel gas used for combustion is introduced, the fuel gas and the air are good. The heat storage lean combustion reaction starts at a high temperature portion around 700 ° C. Combustion gases generated from the heat storage layer
The fuel is introduced into the furnace while being mixed and burnt well with the remaining fuel gas ejected from the remaining fuel gas ejecting portion provided in the combustion gas guide portion leading to the inside of the furnace to complete the combustion.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference numeral 1 denotes an alternating combustion burner for alternately switching and burning two burners having a heat storage layer 2 as a set. A fuel gas mixing device 3 is installed in the heat storage layer 2 of each of the burner portions A and B of the alternating combustion burner. Reference numeral 4 denotes a residual fuel installed in the combustion gas guide 5 on the downstream side of the heat storage layer 2.
This is the gas outlet. The fuel gas mixing device 3 includes the heat storage layer 2
If the fuel gas and the air are installed in a position where the temperature is low, the fuel gas and the air are preheated while being mixed well before reaching the high temperature part 6 which is the combustion area. In addition, when the residual fuel gas ejection part 4 is installed in the combustion gas guide part 5, the residual fuel gas is introduced into the furnace 7 while being satisfactorily mixed with the combustion gas and burning. In the combustion at this time, since the oxygen partial pressure is lowered by the first stage combustion, the same low NOx effect as the combustion in the exhaust gas recirculation can be exhibited. Thus, from the fuel gas mixing device 3, to introduce the entire amount of combustion 10% to 25% of the fuel gas.

When the exhaust gas burned in one burner section A is discharged from another burner section B, the sensible heat is recovered by the heat storage layer 2 of the burner section B. When the combustion is switched from the burner section A to the burner section B, air is introduced into the heat storage layer 2 of the burner section B from the lower portion thereof, and at the same time, the fuel gas of 10% of the total combustion amount is supplied to the heat storage layer 2. Is introduced into the heat storage layer 2 from the fuel gas mixing device 3. Thermal storage layer 2
Is in a heated state, the fuel gas and the air are mixed and preheated satisfactorily while rising, and the combustion reaction starts around 700 ° C. in the high temperature section 6. The combustion gases, fuel reaching the furnace 7 from the heat storage layer 2
The remaining fuel gas is supplied from the remaining fuel gas ejection section 4 in the combustion gas guide section 5 and is introduced into the furnace 7 while burning while mixing, and the combustion is completed in the furnace 7 to complete the other burner sections. The heat is discharged while the sensible heat is recovered in the heat storage layer 2 of A. Such combustion is repeated, for example, every 60 seconds. At this time, when the fuel gas mixing device 3 is installed at a position where the temperature of the heat storage layer 2 is low, the fuel gas and the air are premixed and satisfactorily heated before reaching the high temperature portion 6 which is the combustion region. In addition, when the residual fuel gas jetting section 4 is installed in the combustion gas guide section 5, the residual fuel gas is introduced into the furnace 7 while burning while being well mixed with the combustion gas, and as described above, the exhaust gas recirculation effect is obtained. The same effect as described above promotes the NOx reduction effect. Thus, from the fuel gas mixing device 3, to introduce the entire amount of combustion 10% to 25% of the fuel gas. When the fuel gas amount introduced from the fuel gas mixing device 3 is 10% of the total combustion amount, a NOx reduction rate at the time of emission of about 50% can be achieved, and a reduction rate of about 70% by introducing 20%. Was achieved.
However, if the introduction rate is set to 25% or more or is offset, soot is generated, which is not preferable. As described above, the present invention realizes the lean combustion in the heat storage layer 2 and burns the remaining fuel gas together with the combustion gas, so that the combustion under the low oxygen partial pressure similar to the so-called exhaust gas recirculation combustion is effective. And without reducing the combustion efficiency,
The generation of NOx can be greatly suppressed.

[0009]

As described above, the present invention has the following effects. Exhaust gas recirculation combustion does not require an exhaust gas recirculation facility and can suppress NOx to the same level. Exhaust gas recirculation combustion has a decrease in efficiency. However, since the present invention is combustion in a heat storage layer, there is no decrease in thermal efficiency. Since the invention is a complete preheating mixed regenerative combustion, the exhaust gas is uniform and the exhaust gas recirculation effect is completely obtained.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Alternating combustion burner 2 Heat storage layer 3 Fuel gas mixing device 4 Residual fuel gas ejection part 5 Combustion gas guide part 6 High temperature part 7 Furnace

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F23C 11/00 F23D 14/66 F23L 15/02 F23D 23/00 F23C 7/06

Claims (2)

(57) [Claims] 1. A part of fuel gas to be provided for combustion in a heat storage layer of each burner part of an alternating combustion burner in which two burners having a heat storage layer are alternately switched and burned as a set.
A fuel gas mixing device for introducing the fuel gas is provided, and the remaining combustion gas guide portion from the heat storage layer to the inside of the furnace is provided.
Providing a residual fuel gas ejection part for introducing fuel gas ,
By mixing a 10% to 25% of the fuel gas of the total combustion amount in the heat storage layer under heating conditions from the fuel gas introducing device, cause heat accumulation lean combustion reaction and combustion air come to flow into the heat storage layer After that, the remaining fuel gas in the combustion gas guide section
The fuel gas is introduced into the combustion gas guide via the residual fuel gas ejection part, and the combustion gas and the residual fuel gas from the heat storage lean combustion are used.
An alternating combustion method for producing low nitrogen oxides, wherein the combustion is completed by mixing . Wherein said fuel gas introducing device,蓄under heat
Fuel gas is introduced at a low temperature in the thermal layer.
2. The method according to claim 1, wherein the alternating combustion is performed with low nitrogen oxides.