JPH0652122B2 - Coal burning equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coal combustion apparatus used in the fields of boilers, chemical industrial furnaces and the like.

2. Description of the Related Art As a conventional coal combustion apparatus, there is one as shown in FIGS. 3 to 4, and FIG. 4 shows a cross section taken along line IV-IV in FIG.

In these drawings, reference numeral 1 denotes a furnace main body having a polygonal cylindrical shape, generally a square cylindrical shape as shown in the drawing, and each burner main body 2 has a furnace horizontal wall on which the ultimate heat flux from the furnace 3 is maximized on the same horizontal plane. It is installed in the center of. In each of these burner main bodies 2, a dense pulverized coal mixture gas nozzle 4 directed in the same direction as each of the side walls constituting the furnace main body 1 is provided.
And the pulverized coal mixture nozzle 5 are provided in plural sets with the former as the upper stage and the latter as the lower stage and facing downward (θ = 5 to 30 °). A large capacity air nozzle 6 and a small capacity air nozzle 7 are provided on both sides of each of these nozzles 4 and 5.

Then, the coal 9 sent to each of the plurality of coal pulverizers 8 is pulverized and mixed with the carrier air [temporary air (warm air)] 10 simultaneously sent to mix the pulverized coal mixture 11 [generally in a weight ratio. Air (A) / pulverized coal (C) = mixing ratio of 2 to 4] is formed and fed into the pulverized coal separator 13 through the pulverized coal transport pipe 12.

Pulverized coal mixture 11 sent to this pulverized coal separator 13
Is divided into a dense pulverized coal mixture 14 (A / C≈1.0 ± 0.5) and a light pulverized coal mixture 15 (A / C≈5 to 20). Both dense and light pulverized coal mixture nozzles 4 and 5 built in the burner body 2 through the transport pipe 17.
And is jetted downward from the nozzle tips into the furnace 3.

On the other hand, the combustion air (secondary air) 18 is blown into the burner body 2 through the combustion air line 20 by the blower 19. The large-capacity air nozzles 6 and the small-capacity air nozzles 7 provided on both sides of the dense and light pulverized coal mixture nozzles 4 and 5 in the burner body 2 are large-capacity air nozzles when viewed in a horizontal cross section of the furnace. Nozzle 6 is both dense and light pulverized coal mixture nozzles 4, 5
It is mounted on the side where the angle formed by the injection direction of 1 and the wall surface of the burner main body 2 is small, so that the pulverized coal flame 21 does not collide with the side wall of the furnace main body 1 and combustion deteriorates.

Then, the combustion air sent into the burner body 2
18 is jetted into the furnace 3 from an air jetting unit provided around the large-capacity air nozzle 6, the small-capacity air nozzle 7, and the dense and light pulverized coal mixture nozzles 4 and 5.

Problems to be Solved by the Invention In the coal combustion apparatus described above, stable ignition of the pulverized coal flame 21 is generally said to be better as it qualifies for the following four conditions.

(1) The volatile content in the pulverized coal is large.

(2) The heat flux reaching the burner port is large.

(3) A / C of pulverized coal mixture 11 is close to 1.

(4) The ejection speed of the pulverized coal mixture 11 is low.

However, in a device that burns coal that is difficult to ignite, the amount of volatile matter contained in the coal is small (20% or less), and the condition (1) above is disqualified, so other conditions (2), ( 3), (4)
Will need more careful consideration.

However, in the conventional example, since the large-capacity air nozzle 6 and the small-capacity air nozzle 7 are provided on both sides of both the dense and light pulverized coal mixture nozzles 4 and 5, fuel and air are generated due to the swirling flow in the furnace. And are mixed and cooled rapidly, and there is a problem in ignitability. Further, in the high temperature region of the burner, molten ash adheres to the side wall of the furnace (slugging), which causes problems such as heat transfer inhibition.

Means for Solving the Problems In order to solve such conventional problems, the coal combustion apparatus according to the present invention has a polygonal tubular furnace body and a side wall constituting the furnace body, which are provided with the same rotation. A nozzle for ejecting two types of air-fuel mixture of dense pulverized coal and light pulverized coal, which are oriented in the direction, and a mixture between the above-mentioned air-fuel mixture ejected from the nozzle and the side wall. It has a secondary air nozzle for ejecting secondary air and a tertiary air port opening to the side wall.

Action According to such means, the secondary air is
Since it is injected between the air-fuel mixture ejected from the pulverized coal mixture of pulverized coal and the side wall of the furnace body, it is possible to prevent the fuel from being cooled by the rapid air mixing in the burner section and to stably ignite the fuel. it can. Further, by introducing the tertiary air, an oxygen-excessive region is formed, so that adhesion of molten ash to the furnace side wall can be prevented.

Examples Hereinafter, preferred examples of the present invention will be described in detail with reference to FIGS. In these figures, the same parts as those shown in FIGS. 3 to 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

Therefore, according to this embodiment, the secondary air nozzle 22 in which the conventional large-capacity air nozzle 6 and the small-capacity air nozzle 7 are integrated is provided from the dense and light pulverized coal mixture nozzles 4 and 5. The secondary air 18 is arranged in the vicinity of the downstream side of the swirling flow of the jetted air-fuel mixture, and the secondary air 18 is jetted between the air-fuel mixture jetted from the nozzles 4 and 5 and the side wall forming the furnace body 1. Therefore, the introduction of such secondary air prevents rapid cooling of the fuel due to air mixing and stabilizes ignition.

Further, according to the present embodiment, the tertiary air port 23 is located further downstream than each of the secondary air nozzles 22 described above with respect to the swirling flow of the air-fuel mixture jetted from both the dense and light pulverized coal air-fuel mixture nozzles 4 and 5. It opens at the side wall of the furnace body 1 at the side position. Therefore, by injecting the tertiary air 24 into the furnace 3 through these tertiary air ports 23, an air layer is formed in the vicinity of the inner surface of the furnace side wall, and the molten ash scattered on the furnace side wall is cooled and solidified to cool the furnace side wall. To be prevented.

Further, according to this preferred embodiment, as shown in FIG. 2, the refractory material 25 is lined on the side wall portion of the furnace body 1 below the burner body 2. Therefore, even if
Even if both of the both pulverized coal mixture nozzles 4 and 5 (Fig. 2) or only the nozzle 4 is installed downward (θ °) and the fire 21 goes down to the low temperature part below the bottommost nozzle,
The fire temperature in this portion can be raised by the lining of the refractory material 25 described above, and stable combustion can be performed.

EFFECTS OF THE INVENTION As described above in detail, according to the present invention, the secondary air is collectively collected from the vicinity of the nozzle for ejecting the two kinds of air-fuel mixture of dense pulverized coal and light pulverized coal on each side wall of the furnace body. By charging the fuel, the ignition stability of the fuel can be improved, and by forming an air layer by charging the tertiary air, it is possible to prevent the molten ash from adhering to the side wall of the furnace and improve the heat transfer property. Even coal can be burned well.

[Brief description of drawings]

FIG. 1 is a schematic transverse sectional view showing an example of a boiler equipped with a coal combustion apparatus according to the present invention, FIG. 2 is a schematic longitudinal sectional view thereof, and FIG. 3 is a schematic longitudinal section showing a system of a boiler equipped with a conventional coal combustion apparatus. FIG. 4 is a schematic cross sectional view taken along the line IV-IV in FIG. 1 ... Furnace body, 2 ... Burner body, 4 ... Dense coal mixture nozzle, 5 ... Light coal mixture nozzle, 22 ... Secondary air nozzle, 23 ... Tertiary air port, 25 ... Fireproof Material.

Claims (1)

[Claims] 1. A furnace body having a polygonal cylindrical shape, and a nozzle for ejecting two kinds of air-fuel mixture of dense pulverized coal and light pulverized coal, which are oriented in the same rotation direction on respective side walls constituting the furnace body. A secondary air nozzle disposed near these nozzles for ejecting secondary air between the air-fuel mixture ejected from the nozzles and the side wall, and a tertiary air port opening to the side wall. Characteristic coal combustion equipment.