JPS5995309A - Denitration burner - Google Patents

Abstract

PURPOSE:To reduce NOX without increasing soot and dust in exhaust gas, by a method wherein a main burner and a denitration burner are arranged alternately along a pair of confronting side walls of a fire furnace in a horizontal direction by viewing-through and both end burners are made to function as the main burners. CONSTITUTION:Each of flames of main burners in each of steps such as the main burners 3A, 4A and 5A touches individually flames of denitration burners in each of steps of the corresponding denitration burners 3B, 4B and 5B, and NOX contained within the flames of the main burners are reduced to N2 effectively owing to the fact that a length of contact becomes long due to opposing contact of the flames. Disadvantages that reaction speed of the flames of the denitration burner is lowered and CO and soot and dust are generated resulting from radiation cooling to a side walls 12C and 12D of a fire furnace are eliminated by making both ends of a pair of the burners at each step into the main burners, through which a burning condition such as excessive fuel, which is advantageous to a reduction of NOX, can be strengthened and a drastic reduction of the NOX becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a denitrification combustion device, and particularly to a boiler device suitable for reducing nitrogen oxides (hereinafter referred to as NO treatment) in exhaust gas.

Since NO is considered to be one of the causative agents of photochemical oxidants and acid rain, there has been a demand in recent years for the development of a combustion method that effectively suppresses its generation.

Combustion methods that meet these objectives include (1) exhaust gas recirculation method, (2) two-stage combustion method, and (3) in-furnace denitrification combustion method. Recently, the in-furnace denitrification combustion method, which has excellent operability, has been attracting particular attention.

As shown in Fig. 1 and Fig. g2, the device applied to the conventional in-furnace denitrification combustion method consists of lower stages installed sequentially from the bottom to the top on the front side wall (in some cases including the rear side wall) of the furnace 1. The main burner 3, the middle main burner 4, the upper denitrification burner 5, the front after-air 6A provided above the upper denitrification burner 5, the rear after-air 6B provided on the rear wall of the furnace 1, and the lower part of the furnace 1. It mainly consists of a hopper 1 and 2 provided for exhaust gas adjustment. Note that the burners of each stage burner 3.4 and 5 are sequentially arranged in the longitudinal direction to form a row.

In an apparatus with such a configuration, a combustion region with a large excess of fuel (with an extremely small air ratio) is formed in the upper stage denitrification burner 5, and the reduction radicals generated in this region are used to burn the lower main burner 3 and the middle stage burner on the upstream side. The No. □ generated in the combustion area of No. 4 is reduced, while the unburned matter is returned to the after-aero 6A.
J? The high-temperature exhaust gas 7 after the combustion passes through the flue in the upper part of the furnace 1, and the heat is recovered by a heat exchanger (not shown) provided as necessary. and emitted into the atmosphere.

Although the above method achieves a certain degree of reduction of unburned content in the exhaust gas and reduction of NO emissions, the conventional in-furnace denitrification/burning method still has various drawbacks as described below.

One of the problems is that the furnace becomes excessively high because the main burner layer and the denitrification burner layer are sequentially stacked from the bottom to the top of the furnace. The disadvantage of this song is that, as mentioned above, the main burner 1 layer and the denitrification burner layer are separated vertically, so the flame of the main burner layer and the flame of the denitrification burner layer are not mixed well, and therefore the denitrification efficiency is low. It is a word that becomes low. A further disadvantage of the song is that the burners at both ends of the denitrification burner are arranged on the side wall of the furnace on the same row as the main burner, so radiation cooling to the side wall of the furnace reduces the reaction speed of the denitrification burner flame. ,c.

This means that it becomes easier to generate soot and dust. Therefore) NO
It becomes difficult to strengthen the combustion conditions of excess fuel, which is advantageous for reducing the amount of fuel left behind, and as a result, sufficient denitrification efficiency cannot be obtained.

It is an object of the present invention to provide a denitrification combustion device that eliminates the drawbacks of the prior art described above and can significantly reduce the number of NOs without increasing soot and dust in exhaust gas.

In order to achieve the above object, the present invention provides a combustion apparatus in which a pair of opposing furnace side walls are each equipped with multi-stage, multi-row burners and an after-air above the burners, in which at least one of a pair of burner stages having a relative amount is provided. is a pair of mixing burner stages including a main burner and a denitrification burner, and in the pair of mixing burner stages, the main burner and the denitrification burner are arranged alternately in the horizontal direction as seen in perspective, and the burners at both ends are used as the main burner. Features.

The arrangement of the main burner and the denitrification burner in the above-mentioned mixing burner stage pair can be implemented in any form as long as the main burner and the denitrification burner are arranged alternately in the horizontal direction of the burner stage pair. One of the pair of stages may be provided with only a main burner, and the other pair may be provided with only a denitrification burner, or each of the pair of burner stages may be provided with a main burner and a denitrification burner.

By setting such a burner + R, 1rIA
Since the denitrification burner flame can be brought into contact with each main burner flame and the contact distance can be made large, it becomes possible to efficiently reduce NOx contained in the main burner flame. The above-mentioned mixing burner stage pair is designed to reduce the NOx to be reduced.
When the level of NO is relatively low or during part-load combustion, a single stage pair may be used, but at a high level NO! If reduction is desired, it is preferable to use two or more stages. Note that when the number of mixing burner stage pairs is small, the remaining burner stage pairs may generally be composed of only main burners. Incidentally, the burner stage pairs including the mixing burner stage pair are usually arranged in the same horizontal plane, but they may be provided in a stepped manner from each other along the stage direction.

Furthermore, since the after-air aero membrane is provided above the multi-stage burner, there is no particular restriction as long as the unburned matter generated in the burner section can be completely combusted. In general, it is sufficient to provide the same number of aero as there are burner rows, but if you want to lower the air ratio of the entire burner, increase the number, and conversely, if you want to increase the air ratio, reduce the number. It is preferable to let

Although it is preferable to provide each after-air and each stage burner with an independently partitioned wind box, it is of course possible to apply a common wind box to them.

In the present invention, the burners at both ends of the pair of mixing burner stages are used as the main burners (when the number of main burners is 1, the number of denitrification burners is 1), because the reaction rate of the denitrification burner flame is This is to prevent it from becoming too low.

Hereinafter, the present invention will be explained in more detail with reference to embodiments shown in the drawings.

The apparatus shown in FIGS. 3 and 4 consists of a front lower stage main burner 3A, a front middle stage main burner 4A and A front upper main burner 5A, a front after aero 6A provided above the front upper main burner 5A and having nine role aeros, and a rear In! Rear lower stage denitration burner 3B, '71 side middle stage denitrification burner 4B, each consisting of four rows of crotch burners arranged sequentially from the bottom to the top of the wall.
and a rear upper stage denitrification burner 5B, a rear after aero 6B having nine functional aeros provided above the rear upper stage denitrification burner 5B, and a hopper port for exhaust gas adjustment provided at the bottom of the furnace 1. It mainly consists of 2.

The front lower main burner 3A and the rear lower main burner 3B
, front middle stage main burner 4A and rear middle stage denitration cup 4B,
The front upper stage main burner 5A and the rear upper stage denitrification burner 5B
) (-In the thigh pair, the main burner and the denitrification burner are arranged alternately in the horizontal direction when looking through from the front of the front side wall toward the rear side wall, and one end of them is formed by the main burner. In addition, in FIG. 3, 8A and 9A are provided.

10A, IIA, 8B, 9B, IOB and 11B are
Front lower main burner 3A1 @ middle main burner 4A
, front upper main burner 5A, front after aero 6A, rear lower denitrification burner 3B, rear middle denitrification burner 4B, rear upper denitrification burner 5B, and rear after aero 6B. Front lower wind box, front full middle wind box, front upper wind box, front after-air wind box, rear lower wind box, rear middle wind box, rear upper wind box, and rear after-air wind box It is. In a device with such a configuration, each stage main node on the front side (3A, 4A and 5
A generally has an air ratio of 0.8 to 1.0 and a fuel usage rate of 80%.
On the other hand, in the rear denitrification burners 3B, 4B and 5B, denitrification and combustion power are carried out at an air ratio of 0.4 to 0.6 and a fuel efficiency of 20 cm. be exposed. The flames of the main burners in each membrane of the main burners 3A, 4A and 5A are in individual contact with the corresponding flames of the respective membranes of the main burners 3B, 4B and 5B, and the contact distance is This is mainly due to the fact that the contact is longer than the opposite contact, and the NO contained in the flame is efficiently reduced to N2.

In addition, by using both ends of each stage burner pair as the main burner, the reaction speed of the denitrification burner flame decreases due to radiation cooling to the furnace side walls 12C and 12D, causing CO and soot to be generated. The disadvantage is eliminated, and therefore, the combustion conditions of excess fuel, which are advantageous for reducing No. 1, can be strengthened. In this embodiment, the above-mentioned effects contribute synergistically, and NOx can be reduced without increasing the height of the furnace, without increasing the soot and dust in the exhaust gas, and without requiring a downstream denitrification device. can be significantly reduced.

Although the above has described typical implementations of the present invention, the present invention is of course not limited to this, and there may be various embodiments and modifications of the song within the scope of the idea of the present invention. Needless to say.

For example, the same effect can be achieved by simultaneously providing a main burner and a denitrification burner in each pair of burner stages.

As described above, according to the present invention, at least one of the opposing burner stage pairs is a mixing burner stage pair including a main burner and a denitrification burner, and in the mixing burner stage pair, the main burner is By arranging the and denitrification burners alternately and using the burners at both ends as the main burners, the intramembrane main burner flame of each mixing burner stage pair is brought into contact with the intramembrane denitrification burner flame individually and over a long contact distance. This makes it possible to efficiently reduce NOx contained in the main burner flame to <N2. In addition, by using both ends of each stage burner pair as the main burners, the disadvantage that the reaction rate of the plow denitrification burner flame decreases due to radiation cooling to the side wall of the first furnace and generates CO and soot is eliminated. It is possible to strengthen combustion conditions with excess fuel, which are advantageous for reducing NO. Due to these synergistic effects, it becomes possible to significantly reduce the number of no-works without increasing the soot and dust in the exhaust gas.

[Brief explanation of the drawing]

Figure 1 is a side sectional view showing a conventional combustion device, and Figure 2 is a
FIG. 1 is a side sectional view of the denitrification combustion apparatus according to the embodiment of the present invention, and FIG. 4 is a sectional view taken along line BB in FIG. be. 1... Furnace, 3A... Front lower main burner, 4A...
・Front middle main burner, 5A...Front upper main burner, 6
A...Front after aero, 3B...Rear lower denitrification burner, 4B...Rear middle denitrification burner, 5B...Rear upper denitrification burner, 6B...Rear after aero, 8A.
...Front lower wind and rain, 9A...Front middle wind and rain, 10A.
...Front side, upper stage j', tm, 11 A...Front side after air wind and rain, 8B...Rear F stage wind and rain, 9B...Rear f
ill middle row 1 box, 10B...rear upper row wind and rain, 11B
...Rear after-air wind box, 12C112D...Furnace side wall. Agent Patent Attorney Takenaga Kawakita

Claims (1)

[Claims] (1) In a combustion device in which a pair of opposing furnace side beams are each equipped with multi-stage, multi-row burners and an after-air above the burners, at least one of the pair of opposing burner stages includes a main burner and a denitrification burner. 1. A denitrification combustion apparatus comprising a pair of mixing burner stages, in which main burners and denitrification burners are alternately arranged in a horizontal direction as seen in perspective, and burners at both ends are used as the main burners.