JPH10185164A - Furnace slagging preventing apparatus for coal fired boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a facility cost and to save steam consumption amount by connecting an air duct for diffusing cooing air along an inner surface of a nose to an upper part of a furnace of a boiler, thereby eliminating a soot blower. SOLUTION: At the time of operating the coal fired boiler 1, cooling air A is sprayed from an air duct 6 along an inner surface of a nose 2 by driving a fan 7. Then, an air curtain is formed at the inner surface of the nose 2. Ash is cooled, and conveyed so that ash is scarcely adhered to the inner surface of the nose 2, and slagging is scarcely generated. Here, flowing speed of the air A into a furnace 1a is preferably set to 10[m/sec] or more to prevent invasion of the ash into the duct 6. And, since an oblique surface 8 as a downward gradient toward the furnace 1a is formed at an inclination angle of a repose angle of ash or more at the connector of the duct 6 to an upper part of the furnace 1a, there is no anxiety of depositing the ash at the connector of the duct 6 to the upper part of the furnace 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a furnace slagging prevention device for a coal-fired boiler.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a conventional coal-fired boiler. In the figure, reference numeral 1 denotes a boiler main body including a furnace 1a, a sub-side wall 1b, and a rear heat transfer section 1c.
A nose portion 3 formed at the upper part of the furnace 1a is a burner for supplying fuel such as pulverized coal to the lower part of the furnace 1a of the boiler body 1, and is supplied from the burner 3 to the lower part of the furnace 1a of the boiler body 1. Burning the fuel to produce a combustion gas G1,
The generated combustion gas G1 heats water and steam flowing in the heat transfer tube of the boiler main body 1, and also main steam flowing in a superheater (not shown) disposed in the sub-side wall 1b of the boiler main body 1. And heats steam or the like flowing in a reheater or a economizer (not shown) disposed in the rear heat transfer portion 1c of the boiler main body 1 to remove the heat-deprived combustion gas G1 from the rear. Exhaust gas duct 4 as boiler exhaust gas G2 from the lower end of heat transfer section 1c
To be discharged to

[0003] In the case of a coal-fired boiler as described above, especially on the inner surface of the nose portion 2, the attached ash receives strong flame radiation from the burner 3, becomes hot and melts, and slag is generated and deposited. Conventionally, a soot blower 5 is provided below the nose portion 2 as shown in FIG.
Is operated at predetermined time intervals (approximately four to eight hours) or in accordance with the state of adhesion of ash, such that steam or the like is blown onto the inner surface of the nose portion 2 and the attached ash is blown away to remove.

[0004]

However, as described above, if the soot blower 5 provided below the nose portion 2 is appropriately operated to blow off and remove the ash attached to the inner surface of the nose portion 2, the soot blower 5 will not work. This has the drawback that the necessity leads to an increase in equipment costs, an increase in steam consumption in the plant, and a decrease in plant efficiency.

In view of such circumstances, the present invention can eliminate the need for a soot blower, reduce equipment costs, reduce steam consumption in a plant, and improve plant efficiency. An object of the present invention is to provide a furnace slagging prevention device for a coal-fired boiler.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for preventing furnace slagging in a coal-fired boiler, wherein an air duct for blowing cold air is connected along the inner surface of the nose to the upper part of the furnace of the boiler body. Things.

In the apparatus for preventing slagging of a furnace of a coal-fired boiler, it is effective to form an inclined surface which is inclined downward into the furnace at an angle of inclination equal to or larger than the angle of repose of ash at a connection portion of the air duct with respect to the upper part of the furnace. is there.

According to the above means, the following effects can be obtained.

During operation of the coal-fired boiler, when cool air is blown from the air duct along the inner surface of the nose, an air curtain is formed on the inner surface of the nose, and the ash is cooled and conveyed, and the ash is formed on the inner surface of the nose. Is less likely to adhere and slagging does not occur.

At the connection of the air duct to the upper part of the furnace,
By forming an inclined surface that is inclined downward into the furnace at an inclination angle equal to or larger than the angle of repose of the ash, there is no fear that the ash accumulates at the connection of the air duct to the upper part of the furnace.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 3 show an embodiment of the present invention. In the drawings, the portions denoted by the same reference numerals as those in FIG. 4 represent the same components, and the basic structure is shown in FIG. The present embodiment is the same as the conventional one shown in FIGS. 1 to 3, except that, as shown in FIGS. This is at the point where the air duct 6 to be blown is connected.

In the illustrated example, a fan 7 for supplying cold air A is installed on the upstream side of the air duct 6, but a dedicated fan is used as the fan 7 as shown in the figure. Instead, a forced draft fan (not shown) or the like provided for feeding the combustion air into the furnace 1a is used, and a part of the air fed from the forced draft fan or the like is used as the cold air A. Needless to say, it is good.

As shown in FIG. 2, the connection point of the air duct 6 to the upper part of the furnace 1a has an angle of repose of ash (about 45 degrees).
゜) The inclined surface 8 having a downward slope toward the furnace 1a is formed at the above-mentioned inclination angle θ.

As shown in FIG. 3, a portion of the upper part of the furnace 1a to which the air duct 6 is connected is formed by bending the furnace wall tube 9 constituting the furnace 1a and by connecting the fins 10 connecting the adjacent furnace wall tubes 9 to each other. Cut off part of the opening 1
1, and a plurality of openings 11 are arranged at a required pitch in the width direction of the furnace 1a.

Next, the operation of the illustrated example will be described.

During operation of the coal-fired boiler, when cool air A is blown from the air duct 6 along the inner surface of the nose portion 2 by driving the fan 7, an air curtain is formed on the inner surface of the nose portion 2 to cool and transport the ash. And ash hardly adheres to the inner surface of the nose portion 2 and slagging does not occur.

Here, the flow rate of the cold air A into the furnace 1a is desirably set to about 10 [m / sec] or more in order to prevent the ash from entering the air duct 6.

At the connection between the air duct 6 and the upper part of the furnace 1a, an inclined surface 8 is formed, which is inclined downward into the furnace 1a at an inclination angle θ larger than the angle of repose of the ash. There is no risk of deposition at the connection to the upper part of the furnace 1a.

In this way, the cold air A is blown along the inner surface of the nose portion 2, so that the soot blower 5
Can be eliminated, equipment costs can be reduced, steam consumption in the plant can be reduced, plant efficiency can be improved, and the air duct 6 can be connected to the upper part of the furnace 1a. By forming the inclined surface 8 having a downward slope toward the inside of the furnace 1a at an inclination angle θ equal to or larger than the angle of repose of the ash, it is possible to prevent ash from accumulating on the connection portion of the air duct 6 to the upper part of the furnace 1a.

Incidentally, the furnace slagging prevention device for a coal-fired boiler of the present invention is not limited to the above-described example, and various modifications can be made without departing from the scope of the present invention. is there.

[0022]

As described above, the first aspect of the present invention is as described above.
According to the furnace slagging prevention device for a coal-fired boiler described above, a soot blower can be eliminated, equipment costs can be reduced, steam consumption in the plant can be reduced, and plant efficiency can be improved. According to the apparatus for preventing slagging of a furnace of a coal-fired boiler according to claim 2 of the present invention, in addition to the above-mentioned effects, in addition to the above-described effects, ash accumulation on a connection portion of the air duct with respect to the furnace upper part can be achieved. This can provide an excellent effect that it can also prevent the occurrence.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion II in FIG.

FIG. 3 is a view taken in the direction of arrows III-III in FIG. 2;

FIG. 4 is a schematic configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Boiler main body 1a Furnace 2 Nose part 6 Air duct 8 Inclined surface A Cold air θ Incline angle

Claims (2)

[Claims] 1. An apparatus for preventing slagging in a furnace of a coal-fired boiler, wherein an air duct for blowing cold air is connected along an inner surface of a nose part to an upper part of a furnace of the boiler body. 2. The furnace slagging prevention device for a coal-fired boiler according to claim 1, wherein a slope is formed at a connecting portion of the air duct to the upper part of the furnace, the slope being inclined downward into the furnace at an inclination angle greater than the angle of repose of the ash.