JPH0861656A - Combustion apparatus for boiler - Google Patents

Abstract

PURPOSE: To provide a boiler apparatus which can prevent the adherence of combustion ash to a furnace wall or particularly to a furnace sidewall even if fuel for generating the ash having a strong adhesion is burned. CONSTITUTION: A boiler apparatus comprises a plurality of burners 2 for burning fuel containing adhesive incombustible components at either a front wall 25 or a rear wall 26 for forming a boiler furnace wall or the both, a slewing blade 3 for applying a slewing force to a combustion air supply unit to the burners, its driver 4 and a connecting rod. Further, the apparatus comprises a controller 6 which regulates the force by the blade in response to the property change of the fuel, reduces the force as compared with other burner for the burner near the sidewall, or inhibits to apply the force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiler combustion apparatus, and more particularly to a boiler combustion apparatus suitable for preventing or suppressing adhesion to a furnace wall even when using a fuel that produces adherent combustion ash. Regarding

[0002]

2. Description of the Related Art FIG. 8 shows a system diagram of a conventional boiler combustion apparatus. Further, FIG. 9 is a IX-IX of the boiler shown in FIG.
It is a systematic diagram about the interruption burner part of a horizontal cross section in a line arrow direction. 8 and 9, the furnace 1 is formed by the front wall 25 and the rear wall 26 on which the burner 2 is arranged, and the both side walls 14 connecting the front and rear walls. In the boiler shown in FIG. 8, four burners 2 are arranged on the front and rear walls of each of the upper, middle and lower stages. Further, the burner 2 is supplied with fuel from the fuel supply device 7 through the fuel supply pipe 27. When the fuel is solid such as coal, the fuel supply device 7 is a solid fuel (coal) crushing device or bottle, when it is liquid such as oil, it is a tank and pump, and when it is gas fuel, it is a tank. is there. on the other hand,
The combustion air supply system uses the heat exchanger (air preheater) 9 to heat the combustion air from the forced air blower 10 to the predetermined temperature with the boiler exhaust gas, and then the air supply pipe 28,
It is supplied to the wind box 5 of the combustion apparatus through the damper 8 and is swirled by passing the swirl vanes 3 in the wind box to give a swirl to the combustion air, which is mixed with the above fuel at the burner outlet and sent into the furnace.

In the conventional swirl vane 3, as shown in FIG. 10, the swivel vane angle can be changed by rotating the connecting rod 22 by the manual rotating machine 15, and the swirl force of the combustion air can be adjusted. . In FIG. 10, 12 is a link,
13 is a fuel pipe. In the conventional boiler in which the burner 2 is arranged on the opposite wall surfaces 25 and 26, when using a fuel containing a component (hereinafter referred to as an impurity) other than combustible components such as pulverized coal and heavy oil, the burner 2 For the purpose of reducing NOx, a swirl is given to a mixture of fuel and combustion air (hereinafter referred to as mixture).

In the above-mentioned boiler, after the flames of the burners provided on the opposite wall surfaces collide with each other, a part thereof flows to the side wall and collides with the water wall of the side wall 14. If the flame impinging on the water wall contains impurities, and due to the nature of the fuel, the impurities have a low melting point and have an adhesive force, they are deposited here and form slagging, which impedes heat transfer to the water wall tube.

[0005]

The above-mentioned conventional techniques are
No consideration was given to the adherence of impurities to the side wall, and the adherence of impurities to the side wall deteriorates the heat transfer characteristics of the side wall, lowers the heat recovery capability of the boiler, and further the combustion gas remains at a high temperature to the furnace outlet. Since it flows, there is a problem that the heat load on the water wall near the outlet becomes too large.

The object of the present invention is to control the swirling force applied to the jet flow sent from the burner into the furnace in accordance with the boiler load, the fuel properties, etc., and to control the amount of collision of the air-fuel mixture (flame) on the side wall water wall. It is an object of the present invention to provide a boiler combustion apparatus capable of suppressing the amount of impurities adhering to the water wall by reducing the amount or delaying the collision.

[0007]

In order to achieve the above object, the invention claimed in the present application is as follows. (1) Either the front wall or the rear wall that constitutes the boiler furnace wall,
Alternatively, in both of them, a plurality of burners for burning a fuel containing adherent incombustibles are provided, and a combustion device of a boiler is provided with a swirling mechanism of air in a combustion air supply device for the burners. A combustion apparatus for a boiler, characterized in that a swirl mechanism control means for adjusting the swirl force of the supply air from the combustion air supply apparatus is provided.

(2) In (1), the turning mechanism control means is configured to decrease the turning force when the boiler load is large and increase the turning force when the boiler load is small. Boiler combustion device. (3) Either the front wall or the rear wall that constitutes the boiler furnace wall,
In both or both, a plurality of burners for burning fuel containing adherent incombustibles are provided, and in a combustion apparatus of a boiler in which an air swirling mechanism is provided in a combustion air supply apparatus for the burners, combustion is performed by the burners. A combustion apparatus for a boiler, comprising a swirl mechanism control means for adjusting a swirl force of supply air from a combustion air supply apparatus according to a change in property of fuel.

(4) A plurality of burners for burning a fuel containing adherent incombustibles are provided on either or both of a front wall and a rear wall constituting a boiler furnace wall, and for burning to the burner. In a boiler combustion device in which an air supply device is provided with an air swirl mechanism, the swirl force of the supply air from the combustion air supply device is applied to other burners for the burner closest to the side wall, or for that burner and the next burner. Combustion apparatus for a boiler, characterized by being provided with a turning mechanism control means for adjusting the turning force to be smaller than the turning force or not applying the turning force.

[0010]

[Operation] When a mixture is swirled from the burner of the boiler, the direction of the jet flow from the burner outlet is
It changes depending on the strength of the centrifugal force applied to the mixture due to the turning. If the turning force is strong, it will spread rapidly, and negative pressure will occur at the center, causing reverse flow. Usually, the air-fuel mixture (flame) ejected from the burner closest to the side wall collides with the side wall in a short time due to the centrifugal force. However, there is no problem when using a fuel that does not easily adhere, such as a high melting point of impurities. Under the same operating conditions, when using a fuel to which impurities such as low melting point of impurities easily adhere, the impurities reach and adhere to the water wall before the impurities in the fuel react sufficiently.

However, when the swirling force control device according to the present invention is used, in the case of a fuel to which impurities are likely to adhere, the swirling force is made small and the penetrating force of the jet of the air-fuel mixture is made strong to cause collision near the center of the furnace. Since it takes a long time to collide with the water wall, impurities are already oxidized at the time of collision with the water wall, and the impurities collide with each other in a state where the adhesive force is lost and do not adhere. Further, as described above, the air-fuel mixture is promptly sent to the central part of the furnace.
Since the combustion gas rises faster in the central part of the furnace than in the wall part, the probability of collision with the water wall is significantly reduced.

When the boiler load is high, as a matter of course, the amount of the air-fuel mixture sent into the furnace is large, and therefore there is a high possibility of collision with the water wall. At this time, in the control method according to the present invention, the swirling force is appropriately adjusted, the mixture is quickly sent to the central portion of the furnace, and the mixture is raised together with the upward flow of the central portion of the furnace. Can be taken for a long time. When the boiler load is low, the amount of air-fuel mixture sent into the furnace volume is small, so the time it takes for the air-fuel mixture to reach the water wall is long compared to when it is under high load.
There is little need to weaken the turning force and suppress the amount of impurities adhering to the water wall. Operate to increase the turning force and reduce NOx.

By the above operations, it becomes possible to suppress the adhesion of impurities to the water wall even when the boiler load changes and the fuel property changes, and the heat load on the furnace water wall is stabilized. The stable operation of the boiler can be achieved.

[0014]

1 shows a system diagram of a boiler according to a first embodiment of the present invention. FIG. 2 shows a system diagram of the middle stage of the burner in a horizontal cross section taken along line II-II of the boiler shown in FIG. The structure of the boiler of the present invention is basically the furnace 1, the burner 2, the side wall 14
Consists of Fuel is supplied to the burner 2 from a fuel supply device 7. When the fuel is a solid such as coal, the fuel supply device 7 is a crushing device (for example, a coal mill) or a bottle,
In the case of liquid such as oil, it is a tank or pump, and in the case of gaseous fuel, it is a tank or the like. On the other hand, in the combustion air system, the combustion air from the forced draft blower 10 is heated to a predetermined temperature by the boiler exhaust gas using the heat exchanger 9 and then supplied into the wind box 5 to pass the swirl vanes 3. The combustion air is swirled to mix with the above-mentioned fuel at the burner outlet and send it into the furnace. In the present invention, in the boiler arranged on the front and rear wall surfaces 25, 26 that oppose the burner 2, the burner 2 that uses a fuel containing impurities such as pulverized coal and heavy oil as a fuel
Then, the air-fuel mixture is swirled for the purpose of reducing NOx. In the present invention, the swirl vane 3 is driven by the electric motor 4 as shown in FIG. 3, and the angle of the swirl vane 3 can be changed by instructing from the control device 6, and the swivel force can be adjusted.
In the above-mentioned boiler, the turning force is adjusted to be small when the melting point of impurities has a low adhesive property due to the property of fuel or when the load increases or the slugging characteristics are poor. By this operation, after colliding with the air-fuel mixture of the opposing burner, the flow to the side wall side is reduced as compared with before the operation described above, and the time to reach the side wall becomes longer,
Sufficiently burned and oxidized. By this action, impurities attached to the side wall can be suppressed. FIG. 4 is an explanatory view schematically showing the flow of the air-fuel mixture in this embodiment.

FIG. 5 shows a schematic diagram of a second embodiment of the present invention, in which the combustion air swirl direction 17 of each burner in the boiler is shown.
Shows the pattern. FIG. 1 shows an example of a swirling pattern of combustion air of each burner in the same horizontal stage of a conventional burner.
1 and 12 of the burners closest to the side wall shown in FIG.
There is a side wall swirling pattern as shown by reference numeral 30 in this case. In this case, the rising flow velocity rises because the combustion gas upward flow 18 on the side wall side is combined with the swirling flow in the burner, and the pressure rises. , The burner jet moved to the side wall side and became more likely to collide with the water wall. On the other hand, in the present invention, FIG.
As described in the above embodiment, the turning direction is reversed in a situation where impurities in the fuel are likely to adhere depending on the properties of the fuel and the boiler load. When the swirling direction is reversed, a region 19 where the pressure is high is created on the side wall side as in the swirling pattern of the side wall portion shown in FIG. 6, and the jet 16 of the air-fuel mixture from the burner is directed toward the center direction 20 (low pressure range) of the furnace. By this operation, it becomes possible to suppress the adhesion of impurities.

FIG. 7 shows the turning force of the burner according to the third embodiment of the present invention. Adhesion of impurities in the fuel to the water wall is particularly problematic near the side wall. For operations in which the adherence of impurities in the fuel is concerned, the swirling flow of the burner near the side wall is made smaller than that of other burners to increase the penetrating force and reduce the adherence of impurities. As an operation method of the present invention, the control mechanism can be configured based on the properties of the fuel, for example, in the case of coal, the relationship between the softening temperature and melting temperature of ash and the temperature of the water wall surface of the boiler. That is, when the surface temperature of the water wall is between the softening temperature and the melting temperature of the ash, the adhesive force of the ash increases, so the swirling force is reduced and the penetration of the air-fuel mixture is increased to collide with the water wall. The flow rate of the air-fuel mixture to be used is reduced and the time until collision is lengthened.

The same can be said when the boiler load is high. Since the time until the collision is short, a control method such as reducing the turning force and lengthening the time until the collision can be considered. In order to verify the relationship between the swirling force and the ash adhesion, FIG. 14 shows the result of testing the relationship between the swirling force and the ash adhesion amount using a large test furnace. In the test results, a horizontal axis is a swirl number (hereinafter, referred to as Sw number) which is an infinite number representing a turning strength, and a vertical axis is an ash adhesion amount and an ash adhesion amount per water wall area. . The definition of the Sw number is shown below.

[0018]

## EQU1 ## Sw number = angular momentum / (translational momentum × radius) In the test apparatus used in this test, the Sw number is 0.2 to 0.2.
When set between 5, the coal does not completely burn and collides with the water wall, and a state in which ash easily attaches starts, and S
As a result, the amount of attached ash increased with the number of w. Further, the amount of ash attached is greatly influenced by the turning direction. 6 and 13 show the relationship between the swirling direction and the upward flow when the swirling direction of the burner closest to the side wall is reversed. In the swirling direction of FIG. 13, the upward flow of the water wall portion is promoted, A region where the flow velocity increases and the pressure decreases is formed in the side wall portion. Further, the upflow between the adjacent burners is suppressed, the flow velocity decreases, and the pressure increases. Therefore, the jet flow bends toward the water wall portion, and the jet flow easily collides with the water wall. On the contrary, in the turning direction of FIG. 6 according to the present invention, the pressure on the water wall side rises and the pressure between the adjacent burners decreases, so that the burner jet flows away from the water wall, and the adhesion of ash is reduced. Using the above-mentioned test device, a test was conducted in which the swirling direction of the combustion air injected from the burner near the side wall was reversed. The amount of ash deposited at this time was as shown in FIG.

Although the content of the combustion air has not been described in the above description, it naturally includes air mixed with combustion exhaust gas. Further, the present invention is most effective in the case where the front and rear walls are provided with burners facing each other, but it is also effective for the case where the burners are provided only on either the front wall or the rear wall. Nor.

[0020]

According to the present invention, the adhesion of impurities to the water wall can be suppressed, and the boiler can be operated without impairing the heat recovery function of the water wall. Further, it is possible to prevent inconveniences such as an excessive heat load near the boiler furnace outlet.

[Brief description of drawings]

FIG. 1 is an overall system diagram of a boiler according to a first embodiment of the present invention.

FIG. 2 is a system diagram of a horizontal cross section of the middle burner stage of the boiler shown in FIG.

FIG. 3 is an enlarged sectional view of a swirl vane according to an embodiment of the present invention.

FIG. 4 is an explanatory view schematically showing a mixture flow according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of the second embodiment of the present invention, and is a schematic explanatory diagram of the swirling direction of the combustion air of the burner.

FIG. 6 is a schematic explanatory view of a mixture gas flow according to a second embodiment of the present invention.

FIG. 7 is an explanatory view schematically showing a swirling force of combustion air according to a third embodiment of the present invention.

FIG. 8 is an explanatory diagram of a boiler system showing a conventional example.

9 is a system explanatory view of a horizontal section of the middle burner stage of the boiler in FIG.

FIG. 10 is an enlarged sectional view of a swirl vane showing a conventional example.

FIG. 11 is a schematic explanatory view of a mixture flow showing a conventional example.

FIG. 12 is a schematic explanatory diagram of a swirling direction of combustion air showing an example.

FIG. 13 is a schematic explanatory view of a mixture flow showing a conventional example.

FIG. 14 is an explanatory view showing test results of turning force and ash adhesion amount.

FIG. 15 is an explanatory diagram showing the test results of the turning direction and the ash adhesion amount.

[Explanation of symbols]

1 ... Furnace, 2 ... Burner, 3 ... Swivel blade, 4 ... Electric motor, 5
... wind box, 6 ... control device, 7 ... fuel supply device, 8 ... damper, 9 ... heat exchanger (air preheater), 10 ... forced air blower, 11 ... after air port, 12 ... link, 13 ... fuel pipe, 14 ... Side wall, 15 ... Manual rotating machine, 16 ... Jet flow, 1
7 ... Swirl direction, 18 ... Upflow, 19 ... High pressure range, 20
… Low pressure range, 21… Measuring point, 22… Connecting rod, 25
... front wall, 26 ... rear wall, 27 ... fuel supply pipe, 28 ... air supply pipe.

Claims (4)

[Claims] 1. A plurality of burners for burning a fuel containing an adherent incombustible component are provided on either or both of a front wall and a rear wall constituting a boiler furnace wall, and combustion air for the burners is provided. In a boiler combustion apparatus in which a supply device is provided with an air swirl mechanism, a swirl mechanism control means for adjusting the swirl force of the supply air from the combustion air supply device according to the boiler load is provided. Combustion device. 2. The boiler according to claim 1, wherein the turning mechanism control means is configured to decrease the turning force when the boiler load is large and increase the turning force when the boiler load is small. Combustion device. 3. A plurality of burners for burning a fuel containing an adherent incombustible component are provided on either or both of a front wall and a rear wall constituting a boiler furnace wall, and combustion air for the burners is provided. In a boiler combustion device in which a supply device is provided with an air swirl mechanism, swirl mechanism control means is provided for adjusting the swirl force of the supply air from the combustion air supply device in accordance with changes in the properties of fuel burned in the burner. Boiler combustion device characterized by. 4. A plurality of burners for burning a fuel containing an adherent incombustible substance are provided on one or both of a front wall and a rear wall of a boiler furnace wall, and combustion air for the burners is provided. In a boiler combustor in which a supply device is provided with an air swirl mechanism, the swirl force of the supply air from the combustion air supply device is changed to the burner closest to the side wall, or the burner and the next burner, for other burners. A combustion apparatus for a boiler, characterized in that a turning mechanism control means for adjusting the turning force to be smaller than the turning force or not applying the turning force is provided.