JPS63315811A - Burner for combustion of pulverized fuel - Google Patents

Abstract

PURPOSE:To maintain an air/fuel ratio suitable for an ignition point and form a stabilized flame by setting a funnel-like baffle plates at intervals at the tip of a fuel pipe to feed the pulverized fuel and the primary air into the furnace. CONSTITUTION:When the mixed air of the primary air and the pulverized fuel getting out of a fuel pipe 1 flows within an air nozzle 2, a part thereof is brought to the outside of a plate 4 for retaining a flame by the plate 4 for retaining a flame possessing a smaller opening than the inside diameter of the fuel pipe 1 to be jetted out of the air nozzle 2 so that it spreads over between the plate 4 for retaining a flame broaden toward the end and a point portion 2'' (a) broaden toward the end on the inside wall of the air nozzle. Therefore, a flowing speed of the mixed air of the primary air and the pulverized fuel flowing the outside of the plate 4 for retaining a flame becomes slow, making such a form as wrapping the circumference of the residual air going straight through the opening of the plate 4 for retaining a flame, and enabling a flame to which an ignition point is attracted. Thus, the pulverized fuel going straight is ignited, so that the combustion entirely stabilized can be performed.

Description

[Detailed description of the invention] [Industrial application field] The present invention is a boiler that burns fuel in fine powder.

This article relates to burners used in incinerators, etc.

[Conventional technology]

For example, in a conventional boiler that burns pulverized coal, as shown in Fig. 4, a mixture of primary air and coal powder that has passed through a pulverizer (mill) and is used as coal conveying air flows through a fuel pipe 1. The secondary air passes through the center of the air nozzle and is ejected from the center of the burner, and the secondary air flows through the fuel pipe 1.
The burner is configured to eject from the outer periphery of the mixture of primary air and coal fines ejected through the passage between the air box 3 and the annular outer passage of the air nozzle 2 to aid in combustion.

[Problem that the invention seeks to solve]

In the conventional No. 2 system mentioned above, the mixture of secondary air and fine powder is ejected from the center of the layer, and the secondary air is ejected from the outer periphery of the burner and burned, but the amount of secondary air is finely pulverized. Since the amount of air is determined by the problem of conveyance of the machine, it is not possible to maintain the air/fuel suitable for the ignition point, and the ignition point 1 is usually located far from the tip of the L5-2 inertia burner, as shown in Figure 4. However, this causes problems such as unstable combustion and an increase in unburned matter.

Coal with a low fuel ratio (fixed carbon/volatile matter) has good ignitability, and at an air/fuel ratio of about 2.0, an ignition point of about 300 to 1000 cm from the burner tip is secured. However, even in this case, when the load decreases, the air ratio cannot be made small and the ignition point jumps, resulting in unstable combustion.

Furthermore, direct combustion of materials with a high fuel ratio, such as wood powder or oil coke, has the disadvantage that the ignition point jumps, causing combustion instability and unburned carbon is generated.

The present invention seeks to solve these problems.

[Means for solving problems]

In the fuel powder combustion burner of the present invention, a funnel-shaped flame-holding plate that widens toward the downstream side and has an opening smaller than the inner diameter of the fuel pipe is provided at the tip of the fuel pipe that sends the fuel powder and primary air into the furnace. Arranged with a gap.

[For production]

Using the fuel pipe, a portion of the mixture of fine fuel powder and primary air gradually spreads outside the funnel-shaped flame-holding plate that spreads toward the downstream side, lowers the flow velocity, and passes straight through the opening of the flame-holding plate. The shape wraps around the remaining air-fuel mixture, resulting in the formation of a stable flame, and its ignition point is drawn to Nomina 4.

〔Example〕

An embodiment of the present invention will be described with reference to FIG.

A fuel pipe 1 is installed inside the wind box 3, and the inside of the fuel pipe 1 becomes a passage for a mixture of secondary air and fuel fine powder, and the space between the fuel pipe 1 and the wind box 3 is a passage for secondary air. It is a passageway. A funnel-shaped part 1' is provided at the tip of the fuel pipe 1. Wind box 3
An air nozzle 2 is attached to the tip (end inside the furnace) of the air nozzle 2 facing into the furnace. The air nozzle 2 consists of a conical outer wall 2' and an inner wall 2'' whose diameter decreases toward the inside of the furnace, and the tips 2' of the outer wall 2' and the inner wall 2''
On the contrary, cLt 2'a expands downstream into the furnace in a funnel-like manner. The tip of the fuel pipe 1 is open at the rear end of the inner wall 2 (the end opposite to the furnace),
The inside of the inner wall 2 serves as a passage for the primary air and fuel powder that exited the pipe 1, and the space between the outer wall 2 and the inner wall 2'' serves as a passage for secondary air. A flame-holding plate 4 is disposed inside the end-widening portion 2G with a gap between it and the end-widening portion 2a, and the flame-holding plate 4 is attached to the inner wall 2'' by a holding plate 5.

The flame holding plate 4 has a widening part 2c at the tip of the inner wall.
It has a shape similar to L, and opens toward the downstream side K, that is, into the furnace. Yo 5 to 7
．． - It has an opening smaller than the inner diameter of the tip of the L pipe 1.

This embodiment is configured as described above.

When the mixture of primary air and fuel powder that has exited the fuel pipe 1 flows through the air nozzle 2, it passes through the 7-L pipe 1.
As shown in Fig. 3, a part of the flame stabilizing plate 4 having an opening smaller than the inner diameter of the flame stabilizing plate 4 is guided to the outside of the flame stabilizing plate 4, and the inner wall of the flame stabilizing plate 4 and the inner wall of the air nozzle widens toward the end. The air is ejected from the air nozzle 2 in such a way that it spreads between the air nozzle 2 and the end portion 28 of the air.

For this reason, 1 the air mixture of primary air and fine fuel particles flowing outside the flame stabilizing plate 4 has a slow flow velocity and wraps around the remaining air mixture that passes straight through the opening of the flame stabilizing plate 4. As shown in Figure 3, a stable flame is formed in the surrounding area, with the ignition point being attracted, and this causes the fuel powder traveling straight to ignite, resulting in combustion in a stable overall state. .

Therefore, even when using fine fuel powder with a high fuel ratio and poor ignitability, stable combustion is achieved.

Furthermore, even when the load is reduced, the ignition point will not jump and combustion will not become unstable.

FIG. 2 shows another embodiment of the invention. In this embodiment, the pipe 1 is not provided with a widening part 1', and the tips 2a, 2a of the outer wall 2J and inner wall 2 of the air nozzle 2 are funnel-shaped and enlarge toward the inside of the furnace, and have a diameter of 1'. The structure is similar to that of the embodiment shown in FIG. 1, except that it does not have a conical portion that reduces.

Therefore, this embodiment can also achieve the above-mentioned operations and effects similar to those of the embodiment shown in FIG. 1 above.

〔Effect of the invention〕

The present invention features a flame-holding plate that spreads out at the tip of the 7-Elnoip (which slows down the speed of the fine fuel powder and spreads around the outer periphery, keeping the flame stable, and also draws the ignition point of the fuel toward the burner side. Therefore, even when the load on the furnace is reduced, and even when using pulverized fuel with a high fuel ratio that has poor ignitability, combustion can occur in a stable state and there will be no unburned material. minutes 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 invention, Fig. 3 is an explanatory diagram showing the combustion state in the above embodiment, and Fig. 4 is an explanatory diagram of the conventional It is an explanatory view of Z-su (for fine powder combustion). 1...Fu-L pipe, 2...Air nozzle, 3.
...Wind box.

Claims (1)

[Claims] A funnel-shaped flame-holding plate with an opening smaller than the inner diameter of the fuel pipe and widening toward the downstream side is disposed at the tip of the fuel pipe that sends fuel powder and primary air into the furnace with a gap. Burner for combustion of pulverized fuel.