JPH09126416A - Combustion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the production of an unburnt content in ash on a furnace bottom and to perform low NOx combustion having high combustion efficiency by a method wherein a plurality of auxiliary air injection nozzles to charge a part of combustion air in a direction crossing the jet of a burner are arranged in a level lower than that of a lowermost stage burner. SOLUTION: A plurality of main burners 7-9 are arranged in a horizontal direction and vertically in a plurality of stages and arranged facing a front wall 2 and a rear wall 3 to form a main combustion area. A plurality of injection nozzles 10 for two-stage combustion air arranged horizontally facing each other in parallel to the main burners 7-9 above a main burner 9 at a final stage, i.e., on the wake flow, to form a two-stage combustion air charge part. An injection nozzle 11 for auxiliary air is arranged in a level lower than that of the main burner 7 situated at a lowermost stage facing left and right walls 4 and 5 and a part of combustion air is injected in a direction crossing a main burner injection flow at right angles. As noted above, charge of auxiliary air optimum to the operation condition of a combustion furnace 1, such as, boiler, is regulated, an amount of generating unburnt content is reduced, and the generation of NOx is effectively reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for performing two-stage combustion suitable for suppressing the generation of nitrogen oxides in exhaust gas in a combustion furnace such as a boiler.

[0002]

2. Description of the Related Art In a combustion furnace such as a boiler, low pollution (low NOx) and high efficiency (low unburned content) combustion are strongly demanded, and there is a two-stage combustion method as a method for making this possible. .

FIG. 2 shows the structure of a two-stage combustion method in a conventional combustion furnace. In the figure, 07, 08, 09 are main burners that burn fuel, and a part of the combustion air that is injected together with the fuel from the plurality of multi-stage main burners 06, 07, 08 is used as main burners 07, 08, No. 0 two-stage combustion air jet port installed on the downstream side of the gas flow direction 0
It is charged into the furnace 01 from 10.

As a result, in the main burner region, the amount of combustion air is reduced relative to the amount of fuel to form a reducing atmosphere to suppress the generation of NOx, and the remaining combustion air is injected again on the downstream side. This is a combustion method in which generation of unburned components, CO, and the like is suppressed by charging from the outlet 010.

[0005]

The prior art enables low NOx and low unburned combustion, but especially for solid fuels such as coal, two-stage combustion is aimed at. When the combustion is strengthened (the amount of air for two-stage combustion is increased), there is a problem that the unburned content contained in the ash falling to the bottom of the furnace increases and the combustion efficiency of the boiler decreases.

That is, in FIG. 2, the main burners 07,
The fuel injected from 08 and 09 is burned in a state of air shortage (less than the theoretical combustion air amount) for the purpose of reducing NOx, so that the combustion gas contains a large amount of unburned components.

If this rises along with the flow of the combustion gas, the shortage of air will be injected from the two-stage combustion air jet in the wake, and the state will be close to almost complete combustion. The unburned portion of the portion is separated from this ascending flow, falls to the bottom hopper 06 below, and is discharged outside the system as bottom ash.

In particular, the flow of flame from the burner 07 installed in the lowermost stage of the main burners has a flow pattern such that it once descends to the bottom of the furnace, as in the case of the lowest stage burner jet 012 shown in the figure. In addition, there is a problem that the relationship with the increase in unburned content in the bottom ash becomes large.

The present invention solves the above-mentioned problems in the prior art and reduces the generation of unburned components in the bottom ash that increases with the two-stage combustion, thus achieving low NOx combustion with high combustion efficiency. It is an object of the present invention to provide a two-stage combustion which is made possible.

[0010]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and a plurality of air jets are provided in the wake of the main combustion region which is formed by arranging a plurality of burners in a plurality of stages. By providing a two-stage combustion air injection section configured to have, the unburned components in the gas discharged from the main combustion area are almost completely burned by the air supplied from the two-stage combustion air injection section. In the above, there is provided a combustion device provided with a plurality of auxiliary air jets for injecting a part of combustion air in a direction orthogonal to the jet flow of the burner at a position lower than that of the bottom burner, By injecting a part of the combustion air in a direction orthogonal to the main burner jet from a plurality of auxiliary air jets installed at a low level, the lowermost burner jet (flame) stops falling to the furnace bottom and Compensating for shortage of bottom with combustion air , In which was set to be able to reduce the unburned carbon in Rosokohai.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIG. Reference numeral 1 denotes a combustion furnace, which is divided into a front wall 2 and a rear wall 3, and left and right side walls 4 and 5.

Main burners 7, 8 and 9 are arranged in the horizontal direction and are arranged in a plurality of stages in the vertical direction to form a front wall 2.
And the rear wall 3 are provided so as to face each other, and a main combustion zone is formed here.

Reference numeral 10 denotes an injection port for the two-stage combustion air, which is above the main burner 9 at the final stage, that is, on the downstream side.
A plurality of horizontal stages are arranged so as to face each other in parallel with the stages 8 and 9 to form a two-stage combustion air injection part.

Reference numeral 11 is a jet of auxiliary air, which is provided at a level lower than that of the main burner 7 in the lowermost stage of the main burners 7, 8 and 9 so as to face the left and right side walls 4 and 5, and burns. A part of the working air is ejected in a direction orthogonal to the main burner jet.

Reference numeral 6 denotes a furnace bottom hopper, and 12 denotes a jet flow (flame) of the lowermost main burner 7.

Since the present embodiment is configured as described above, the jets (flames) from the main burners 7, 8 and 9 of the respective stages, which are arranged so as to face the left and right side walls 4 and 5, are once generated in the furnace. After the collision at the center, it becomes an upward flow, and it is an opposite combustion that goes to the wake side.

A two-stage combustion air jet port 10 is arranged above the main burners 7, 8 and 9 (in the downstream flow) to reduce the NO level.
In order to achieve x, in the main combustion area by the main burner parts 7, 8 and 9, reduction combustion is performed in an air-deficient state, and the unburned components generated there are almost eliminated by the two-stage combustion air injected from the same jet port 10. Burn it completely.

At this time, a part of the unburned component generated in the main burners 7, 8 and 9 flows into the lower part, so that it is arranged on the left and right side walls 4 and 5 at a level lower than that of the lowermost main burner 7. A part of the combustion air is discharged from the auxiliary air jet 11 as shown in FIG.
By injecting in the direction orthogonal to the main burner jet as shown by the broken line in Fig. 5, the unburned components in this region are almost completely burned, and the unburned components in the ash falling into the bottom hopper 6 are reduced. Is.

That is, according to the present embodiment, in the upper part of the main combustion region, the unburned component generated as a result of the reduction combustion in the main combustion region is almost completely burned by the two-stage combustion air. Auxiliary air flow 1 in the lower part of the main combustion zone
3 reduces the degree to which the jet 12 of the lowermost burner descends to the bottom of the furnace, and at the same time, the main burners 7, 8 and 9 with insufficient air flow.
On the other hand, by injecting a part of the combustion air to a level lower than that of the lowermost burner 7, it is possible to effectively combust the unburned matter in the ash that passes through this zone and drops into the furnace bottom hopper 6. It can be done.

The main burners 7, 8 and 9 are arranged on the front wall 2 and the rear wall 3 so as to face each other, and similarly auxiliary air is introduced from the left and right side walls 4 and 5, whereby the above-mentioned effect is obtained. Will become more prominent.

As described above, according to the present embodiment, the amount of unburned components generated in the bottom ash is reduced by adjusting the injection of the optimum auxiliary air for the operating conditions of the combustion furnace such as the boiler. This makes it possible to reduce NOx by the effective two-stage combustion.

In the present embodiment, the auxiliary air ejection ports 11 are provided on the left and right side walls 4 and 5, respectively, but three auxiliary air ejection ports 11 are provided, but the selection or number of side walls is not limited to this. However, the point is that the auxiliary air jet 11 is at a lower level than the lowermost burner 7, and the main burner jet flows in the combustion furnace 1
It should be inserted so as to be orthogonal to the part that collided at the center of.

Although the present invention has been described with reference to the illustrated embodiments, the present invention is not limited to such embodiments.
It goes without saying that various modifications may be made to the specific structure within the scope of the present invention.

[0024]

As described above in detail, according to the present invention, it is possible to reduce the unburned content in the bottom ash discharged from the bottom of the furnace, so that the combustion efficiency is kept high. With this, it is possible to achieve low NOx combustion, which in turn can reduce the running cost.

Further, this effect becomes more significant as the two-stage combustion is strengthened (the combustion air in the main burner is reduced) in order to reduce NOx.

[Brief description of the drawings]

FIG. 1 shows an arrangement of auxiliary air ejection ports according to an embodiment of the present invention, (a) is a side view thereof, and (b) is an explanatory view from the front.

FIG. 2 is a configuration diagram showing conventional two-stage combustion.

[Explanation of symbols]

 1 Combustion furnace 2 Front wall 3 Rear wall 4,5 Side wall 7, 8, 9 Main burner 10, 11 Jet outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshimitsu Ichinose 5-171-1 Fukahori-cho, Nagasaki City Mitsubishi Heavy Industries Ltd. Nagasaki Research Institute

Claims (1)

[Claims] 1. A main combustion system comprising a plurality of burners arranged in a plurality of stages and a two-stage combustion air injection unit having a plurality of air jets in a wake of a main combustion region. In the one in which the unburned components in the gas discharged from the region are almost completely burned by the air supplied in the two-stage combustion air input part, the burner is orthogonal to the burner jet at a position lower than the burner in the bottom stage. A plurality of auxiliary air jets for injecting a part of combustion air in a direction are provided.