JPS6280412A - Combustion control method and combustion control device - Google Patents

Abstract

PURPOSE:To facilitate an ignition of a fuel having a poor characteristic of ignition and to enable a stable combustion to be attained by enlarging a contact area of fuel with oxygen at an outlet of a burner. CONSTITUTION:In order to stop a supplying of a secondary air to be fed and to keep a required ratio of air at a burner, a reduced amount of air is added to a tertiary air to control an amount of air to be supplied. Applying of this controlling method accelerates a diffusion of fuel at an outlet of a burner B and enlarges a contact area of the fuel with air, and then it is possible to prevent a flame from being lifted up. An excessive reduction in supplying of a secondary air to adjust an amount of third air enables a similar effect to be obtained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a boiler combustion control method and an apparatus thereof.
In particular, the present invention relates to a method and apparatus suitable for controlling the amount of combustion air so as to increase the contact area of fuel with oxygen (or air) at the burner outlet.

[Background of the invention]

Previously, JP-A-57-26310, JP-A-57-1
As disclosed in Publication No. 6703, when burning fuels that are said to have poor combustibility, such as pulverized coal fuel (particularly high fuel ratio coal), CWM fuel, etc., the flame lifts from the burner,
There was a phenomenon in which it was difficult to obtain ignition stability. This is because pulverized coal fuel, especially high-fuel ratio coal, has a lower combustion rate and flame lift because it has less volatile carbon than solid carbon. Since it contains , it takes more time for its evaporation, making it more difficult to burn.

In addition to this, conventional burner structures e.g.
As shown in the figure, the fuel is supplied from the center and all combustion air (secondary and tertiary air) is supplied from the surrounding area for combustion3. Therefore, the combustibility of the fuel is If the condition is poor, the air (oxygen) contact surface fjt' of the fuel cannot be sufficiently maintained at the burner outlet. Therefore, there has been a problem that the flame during combustion lifts (Fig. 4).

As described above, with pulverized coal fuel, CWM fuel, etc., the flame tends to lift easily, and furthermore, there are the following problems.

■Combustion vibration: When the flame lifts, the ignition position changes, which makes combustion vibration more likely to occur.

■Explosion: There is a possibility that unburned fuel will fill the furnace and ignite and cause an explosion.

In order to avoid such a situation, combustion has traditionally been constantly monitored using a frame detector, an ITV camera, etc.

However, a burner combustion control method for fuel with poor combustibility has not been established, and there is also the problem that the control depends on the experience of the operator.

[Purpose of the invention]

An object of the present invention is to provide a combustion control method and device that improves the ignition of fuel with poor combustibility and achieves stable combustion.

[Summary of the invention]

The present invention focuses on the fact that general burners are designed for twisting charges with good combustibility, and furthermore, the fuel oxygen (
This is a combustion control method and device that improves the ignitability of even fuel with poor combustibility by increasing the area of contact with the fuel (or air).

[Embodiments of the invention]

Figure 4 shows the point at which the secondary and tertiary air flows and the mixing of fuel and air begin when the flame lifts. Flame lift occurs because secondary air, which is originally supplied as air for combustion, impedes the diffusion of fuel in the case of fuel with poor combustibility, increasing the contact area with air (or oxygen). This is because it cannot be removed. For this reason, the flames were concentrated at the locations indicated by hatching.

An embodiment of the present invention is shown in FIG. In FIG. 1, the secondary air to be supplied is stopped, and in order to maintain the burner air ratio, the reduced amount is added to the tertiary air and supplied, and the supply amount is controlled. As a result, it is as if the secondary air supply was simply shut off, which is the simplest solution based on this phenomenon. By adopting this control method, the diffusion of fuel at the outlet of burner B is accelerated, and the contact area with air is increased.
Flame lift can be prevented. In this embodiment, the supply of secondary air is stopped, but the same effect can be obtained by reducing the supply as much as possible and adjusting the amount of tertiary air.

Another embodiment of the invention is shown in FIG. In Fig. 2, the burner B' is modified to control the supply amount of secondary and tertiary air.

The idea is the same as in the case of Figure 1. By separating the secondary air supply from the fuel outlet, a negative pressure area is created between the air supply port and the fuel outlet, which speeds up the diffusion of fuel and improves the ignition position. It is placed close to burner B to achieve stable combustion.

However, in order to increase the contact area between fuel and air, it is better not to increase the amount of conveying air supplied. This is because the flow rate must be increased to supply the same amount of fuel, resulting in flame lift.

In this way, in the present invention, since the contact area of fuel with air (or oxygen) at the burner outlet is increased, it is possible to control the amount of air or modify the burner, and it is also easy to combine the two.

〔Effect of the invention〕

According to the present invention, flame lift is prevented, the ignition position is stabilized, boiler vibration is prevented, boiler safety is improved,
The burden on the operator can be reduced.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of one embodiment of the present invention, Fig. 2 is an explanatory diagram of another embodiment of the present invention, Fig. 3 is a conventional burner structure diagram, and Fig. 4 is the generation of flame lift by a conventional burner. FIG. B...Burna.

Claims (1)

[Claims] 1. A burner device for a power generation boiler, characterized in that the combustion air is controlled to diffuse the fuel so as to increase the contact area of the fuel with oxygen at the outlet of the burner device. Combustion control method. 2. In claim 1, in order to increase the contact area of the fuel with oxygen at the outlet of the burner device, the amount of secondary air is minimized and the reduced amount of air is supplied as tertiary air. A combustion control method characterized by: 3. A combustion control method according to claim 1, characterized in that the tertiary air is introduced in a direction in which it is diffused outward, and the primary air and fuel are supplied in the form of a spray. 4. In a burner device for a power generation boiler, in order to increase the contact area of the fuel with oxygen at the outlet of the burner device, it is recommended that the fuel outlet and the secondary air outlet be separated by a predetermined distance. Characteristic combustion control device. 5. The combustion control device according to claim 4, further comprising means for supplying the secondary air and the tertiary air.