KR20000045131A - Pulverized coal burner for reducing nox - Google Patents

Abstract

PURPOSE: A pulverized coal burner is provided to partially increase fuel and air content at the outlet of a burner and to reduce NOx(nitrogen oxyde) by concentrating or dispersing pulverized coal. CONSTITUTION: Primary air flows toward a furnace through a pulverized coal nozzle(44) by rotating a rotary block unit(54). The density of pulverized coal is increased from the inside to the outside of the furnace and rarefied in the center by changing the channel of the pulverized coal and primary air with a block(52). Therefore, the nitrogen elements of the pulverized coal are changed into nitrogen molecules and NOx is reduced through reduction.

Description

Nitrogen oxide reduction type pulverized coal burner

The present invention relates to a pulverized coal burner of the present invention, and more particularly, to a nitrogen oxide-reduced pulverized coal burner capable of reducing pollution during combustion.

The pulverized coal burner grinds coal, which is a kind of fossil fuel, into a pulverized coal of about 50 mesh and sends it to the brazier by the preheater with the primary air preheated and then with the secondary air. It is a device that burns in a floating state by spraying it from.

The turn-down ratio of the pulverized coal burner is determined by the production and transportation characteristics of the pulverized coal pulverized by the mill. At this time, the minimum amount of pulverized coal to primary air (Air / coal ratio) is increased, causing a serious problem in stabilizing the flame in the furnace. In general, the minimum load for the operation of the mill is maintained at about 35-40% due to the operation characteristics of the mill, but there is a method of changing the characteristics of the mill in order to expand the stable operating range of the mill. However, this is difficult to install a separate mill with different operating characteristics. Therefore, in recent years, burner manufacturers have solved this problem by appropriately adjusting the ratio of pulverized coal to primary air due to a change in the burner structure.

In addition, the method of reducing pollutants such as nitrogen oxide (No _x ) and fine dust (dust) generated during pulverized coal combustion, mainly in the primary combustion zone (initial combustion zone of the burner), the fuel over-air shortage state, that is, Maintain the air ratio below 1.0 to suppress the reaction of nitrogen and to guide the incomplete combustion products caused by the lack of air to the downstream side of the furnace where the temperature is lower than the inlet temperature in the furnace. The method of making is mainly used.

The low pollution combustion method currently in use is a combustion gas recirculation method in which a part of the first combustion combustion gas is mixed with combustion air and introduced into a burner for combustion, and a part of the combustion air is directly sent to a hole installed on the burner to be incomplete in the burner area. Nitrogen oxides are controlled by controlling the mixing characteristics of combustion air and fuel by the method of reducing pollutants by adding facilities such as two-stage combustion method in the furnace that completely burns the combusted combustion gas and the aerodynamic method of separately supplying combustion air from the burner. And low-pollution burners that reduce the production of unburned dust.The combustion gas recycling method and the pollutant reduction method have a high effect of reducing nitrogen oxides, but they need to add an anti-pollution aftertreatment facility to existing facilities. There is a constant burden on maintenance and maintenance. Therefore, in recent years, low-pollution type burners that can reduce pollutants without additional equipment by changing the structure due to aerodynamic considerations inside the burner are preferred.

7 schematically shows a conventionally known nitrogen oxide reduced pulverized coal burner.

An oil burner gun (2) for supplying liquid fuel into the furnace is installed in communication with a through hole (8) formed in a part of the burner tile (6) contained in the oil burner outer cylinder (4), and the oil burner gun At the outside of (2), a cylindrical pulverized coal nozzle 10 capable of mixing and supplying pulverized coal, which is a kind of fossil fuel, and primary air is arranged.

In addition, a secondary air supply cylinder 16 and a tertiary air supply cylinder 18, each of which is equipped with a secondary air swirler 12 and a tertiary air swirler 14, are installed outside the pulverized coal nozzle 10. . A flow divider 20 is installed between these secondary air supply cylinders 16 and the tertiary air supply cylinders 18, so that the external air introduced by the swirlers 12 and 14 is secondary. Separate with air and tertiary air.

The pulverized coal burner is pulverized by pulverized coal and primary air supplied through the pulverized coal nozzle 10 by the burner nozzle 22 installed at the tip of the oil burner gun 2 to form a flame zone. The secondary and tertiary air swirlers 12 and 14 mounted on the cylinder 16 and the tertiary air supply cylinder 18 flow in external air and are converted into secondary and tertiary air. Together with the effect of releasing volatiles of pulverized coal, the air keeps unburned volatiles and burned char left in a sufficient oxygen state to achieve complete combustion.

However, when pulverized coal is introduced into the furnace and burned, it not only has a straightness in the direction of the tube axis of the pulverized coal nozzle but also swirls in a forward and reverse direction to form a flame, in which the mixture of pulverized coal and air is not smooth. As a result, a lot of nitrogen oxides are emitted, which causes a problem of incomplete combustion in the furnace.

The present invention is to propose a pulverized coal burner having an improved structure in order to seek more improved complete combustion in such a conventionally known nitrogen oxide reduced pulverized coal burner, the uniform distribution of pulverized coal in the pulverized coal nozzle and into the furnace By adjusting the concentration of pulverized coal to be concentrated or dispersed, it enhances flame protection function and provides pulverized coal burner which can reduce nitrogen oxide by partially increasing the concentration of fuel and air at the combustion furnace and burner outlet in the middle part of the furnace. The purpose is.

In order to achieve the above object, the present invention provides a rotary block unit having a plurality of blocks rotatably installed on the outer periphery of the oil nubber outer cylinder in the advancing direction of pulverized coal, and the number of pulverized coal nozzles in a number corresponding to the plurality of blocks. A fixed diffuser installed at the inner circumference and having two inclined portions which are inclined in the advancing direction of the pulverized coal proposes a structure for optimally generating a flame caused by the pulverized coal injected from the pulverized coal nozzle.

Preferably, the plurality of blocks and the plurality of fixed diffusers may be arranged at equal intervals, respectively.

And, the rotating block portion may be rotated in the range of 0 to 45 degrees.

In addition, a plurality of blocks are formed with an inclined portion which gradually rises in the advancing direction of the pulverized coal toward the brazier, so that the pulverized coal is diffused in the furnace.

In addition, the inclined portion on one side of the inclined portion of the fixed diffuser to be inclined in the same manner as the plurality of block inclined portion, the other inclined portion of the fixed diffuser is inclined opposite to the inclined portion on the side of the coal burner facing the furnace between the oil burner outer cylinder and the pulverized coal nozzle It will be inclined to collect pulverized coal in the direction of travel.

In particular, the other inclined portion is characterized in that the absolute value of the inclination is larger than the inclined portion on one side.

1 is a cross-sectional view schematically showing the configuration of a pulverized coal burner according to the present invention,

Figure 2a is a front view showing a state in which the rotary block portion of the pulverized coal burner according to the present invention,

FIG. 2B is a sectional view seen from A-A of FIG. 2A,

Figure 3a is a front view showing a state in which the rotary block portion 45 ° rotated pulverized coal burner according to the present invention,

3B is a sectional view seen from B-B of FIG. 3A,

4 is a view illustrating a pulverized coal concentration distribution of a pulverized coal nozzle outlet in a state where a rotating block part of a pulverized coal burner according to the present invention is in a fixed position;

5 is a view illustrating a distribution of pulverized coal at the pulverized coal nozzle outlet in a state in which a rotating block part of the pulverized coal burner according to the present invention is rotated 45 °;

Figure 6 is a graph showing the nitrogen oxide emission characteristics of the embodiment of the present invention and the conventionally known embodiment,

Figure 7 is a side cross-sectional view showing a conventionally known pulverized coal burner.

Explanation of symbols on the main parts of the drawings

30 burner tile 32 through hole

44: pulverized coal nozzle 46: fixed diffuser

48: oil burner gun 50: oil burner barrel

52: block 54: rotation block portion

56: pressure regulator 60: variable block

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 is a schematic cross-sectional view of a pulverized coal burner according to a feature of the present invention, Figure 2a is a front view showing a rotating block portion of the pulverized coal burner in position, Figure 2b is a sectional view seen from AA of Figure 2a, Figure 3a It is a front view in the state which the rotation block part of a pulverized coal burner rotated 45 degrees, and FIG. 3B has shown sectional drawing seen from BB of FIG. 3A.

A through hole 32 is formed in the burner tile 30 of the furnace partially omitted, and a tertiary air supply barrel 34 is installed outside the burner tile 30 in contact with the through hole 32. The tertiary air swirler 36 is mounted inside the secondary air supply cylinder 34 to suck and turn the tertiary air (external air).

In addition, a secondary air supply cylinder 38 is provided outside the tertiary air supply cylinder 34, and the secondary air supply cylinder 38 also sucks and turns secondary air (external air) inside the secondary air supply cylinder 38. The air conditioner swinger 40 is mounted.

In addition, a flow divider 42 is installed between the tertiary air supply cylinder 34 and the secondary air supply cylinder 38 to form a flow path for separating the tertiary air and the secondary air to be introduced into the furnace. .

On the other hand, to the pulverized coal nozzle 44, which is the center of the through hole 32 and disposed in the center of the secondary air supply cylinder 38, the pulverized coal and primary air obtained by pulverizing coal are mixed and supplied and sprayed into the furnace. Lose.

The furnace side end of the pulverized coal nozzle 44 is provided with a plurality of fixed diffusers 46 in accordance with the present invention, all four may be installed at 90 ° intervals in the inner circumference of the pulverized coal nozzle 44.

When the cross section of the fixed diffuser 46 is cut in the tube axis direction of the pulverized coal nozzle 44 and viewed from the side, it can be seen that it is formed in a substantially inverted trapezoid and the inclinations of the opposite oblique surfaces are formed to be opposite to each other. Here, the inclination of the other inclined surface close to the furnace side and the inclination of the other inclined surface to the absolute value is that the inclination of the other inclined surface is formed larger.

In the inner center of the pulverized coal nozzle 44 described above, an oil burner outer cylinder 50 containing the oil burner gun 48 is disposed up to the inlet of the furnace.

On the outer periphery of the end of the oil nubber outer cylinder 50, the rotation block portion 54 consisting of four blocks 52 equal to the number of the fixed diffusers 46 is installed to be rotated 45 ° in the forward and reverse directions. Reference numeral 52 has a slope that gradually rises toward the furnace side from the outer periphery of the oil burner outer cylinder 50 on the basis of the traveling direction of the pulverized coal and the primary air, the slope is the same slope as the inclined surface of one side of the fixed diffuser 46 do.

In addition, when each of the fixed diffuser 46 and each block 52 of the rotary block portion 54 is positioned at the same angle, a flow path is formed between the inclined surface of the fixed diffuser 46 and the inclined surface of the block 52. To allow pulverized coal and primary air to pass through.

It looks at the operation and the effects of the pulverized coal burner according to the present invention having such a structure.

First, in the state in which the rotating block part 54 is fixed, the pulverized coal ejected into the furnace is applied without being rotated with respect to the tube axis direction of the pulverized coal nozzle 44. At this time, the operation of the pulverized coal burner will be described. Accordingly, the liquid fuel is injected from the burner nozzle of the oil burner gun 52 and the spark is ignited, and at the same time, the pulverized coal and the primary air pass through the inside of the pulverized coal nozzle 44 to face the brazier. As the part of the air-conditioning reaches the fixed diffuser 46, the flow path is changed by the inclined surface on the other side, the flow velocity is increased, and the dispersion flows through the inclined surface of the block 52 and the inclined surface on the one side of the fixed diffuser 46, thereby dispersing. In this case, the inlet side of the furnace through the through hole 32 shows the pulverized coal concentration distribution as shown in FIG. Information diffuser 46 and the block 52 of pulverized coal and the primary is still injected into the furnace without passing through the air is a flame shape are formed with a conventional pulverized coal concentration.

Next, when the pulverized coal burner is operated while the rotary block part 54 is rotated 45 ° and air is supplied through the pulverized coal nozzle 44 and each air supply cylinder 34, 38, the pulverized coal nozzle 44 is opened. Through the pulverized coal and the primary air to the hearth, and the part of the pulverized coal and primary air that was injected is changed in the flow path by the fixed diffuser 46 and the block 52 of the rotary block 54, as shown in FIG. As shown, the flame shape according to the pulverized coal concentration injection will appear.

Here, the angle change of the rotary block portion 54 is not limited to 45 ° and can be adjusted within the range 0 ~ 45 ° can be adjusted appropriately so that the pulverized coal sprayed into the hearth can be injected without swirling in the forward and reverse direction Do.

In this way, when the supply path of the pulverized coal is changed by changing the position of the rotary block 54, as shown in FIG. 6, the concentration of the pulverized coal is increased from the inside of the furnace to the outside and is sparsely injected at the center of the nitrogen oxide reduction region. The nitrogen component contained in the volatile matter of the pulverized coal due to the expansion of is converted into nitrogen molecules rather than nitrogen oxides, and thus the amount of nitrogen oxides generated in the early stage of the flame zone can be reduced again to reduce the amount produced. In the process of suppressing nitrogen oxides, the inevitably increased unburned fuel is completely combusted by actively mixing with tertiary air in the wake of the flame zone, and in the downstream combustion region, most of the fuel components that started to burn from the middle of the flame zone are continuously burned. As it is mixed with a sufficiently heated tertiary air while moving to the flame zone afterwards, it is actively burned, so that not only nitrogen oxides but also unburned losses at the time of combustion can be significantly reduced compared to conventional coal dust burners.

As described above, the pulverized coal burner according to the present invention can obtain improved combustion more than conventional products.

That is, between the oil burner outer cylinder and the pulverized coal nozzle, a rotatable block part including a plurality of fixed diffusers and a corresponding block is installed to rotate within the range of 0 to 45 ° so that when the pulverized coal is ejected into the brazier, it is wirelessly ejected. This allows for the conversion of nitrogen oxides to nitrogen molecules early in the flame zone.

Therefore, the generation of nitrogen oxides is reduced as compared to the conventionally known pulverized coal burner, so that it is possible to reduce the emission of pollutants as complete combustion is possible.

Claims (7)

A burner gun is placed at the center of the oil burner outer cylinder for supplying cooling air, and the pulverized coal and secondary air supplied through the pulverized coal nozzle which surrounds the oil burner outer shell with liquid fuel injected through a nozzle mounted at the end thereof are brazed. In the nitrogen oxide reduced pulverized coal burner using the thermal energy generated when burning in the inside, Rotating block portion 54 which is rotatably installed with a plurality of blocks 52 having an inclined surface in the advancing direction of pulverized coal in the outer periphery of the oil burner outer cylinder 50, and the number corresponding to the plurality of blocks 52 A plurality of stationary diffusers 46 installed on the inner circumference of the pulverized coal nozzle 44 and having two inclined planes having different inclinations in the advancing direction of the pulverized coal generate optimal flames generated by the pulverized coal. Nitrogen oxide reduced pulverized coal burner, characterized in that. 2. The pulverized coal burner of claim 1, wherein the plurality of blocks (52) and the plurality of fixed diffusers (46) are arranged at equal intervals. The pulverized coal burner of claim 1, wherein the rotary block part is rotated within a range of 0 to 45 degrees. The pulverized coal burner according to claim 1, wherein the plurality of blocks (52) are formed with an inclined surface which gradually rises in the advancing direction of the pulverized coal toward the furnace to diffuse the pulverized coal into the furnace. [5] The pulverized coal burner of claim 4, wherein one of the inclined surfaces of the fixed diffuser is inclined in the same manner as the inclined surfaces of the plurality of blocks (52). The inclined surface of the other side of the fixed diffuser 46 is inclined opposite to the one inclined surface so as to be inclined so as to collect pulverized coal in the advancing direction of the pulverized coal toward the furnace between the oil burner outer cylinder 50 and the pulverized coal nozzle 44. Nitrogen oxide reduction type pulverized coal burner characterized by the above-mentioned. The pulverized coal burner according to claim 6, wherein the other inclined surface has a larger absolute value of the inclination than the inclined surface of one side.