KR19990079053A - Pulverized coal burner - Google Patents

Abstract

PURPOSE: To provide a pulverized coal burner that can reduce pulverized coal accumulation and reduce the combustion of polluted coals by suppressing the accumulation of pulverized coal in the pipe, stabilizing combustion and increasing the mixing of pulverized coal and primary air and the residence time in the furnace.

Construction: Connect and install a liquid burner gun 52 for injecting liquid fuel into a furnace, and arrange a pulverized coal nozzle 54 to mix and supply pulverized coal and primary air to the furnace, and to the outside of the liquid burner gun. Air supply cylinders 34 and 38, each of which is provided with a plurality of air swirlers 36 and 40 for sucking and turning the outside air, and installed inside the air supply cylinder to separate and guide the external air. In a pulverized coal burner composed of a flow devader 42 and using thermal energy generated when burning pulverized coal in a furnace, a part of the pulverized coal nozzle is cut to form a communication hole 56, and the pulverized coal and A variable block (60) for controlling the flow of primary air is provided, and the secondary air is provided with a secondary air swirler (46) for sucking and turning the secondary air between the pulverized coal nozzle and the air supply cylinder. A cylinder 44 is provided.

EFFECTS: It is possible to prevent environmental pollution by reducing unburned materials and abrupt generation of nitrogen oxides, and to reduce operating costs.

Description

Pulverized coal burner

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

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

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.

5 shows a conventional low pollution type burner.

A liquid burner gun (2) for supplying liquid fuel into the furnace is installed in communication with a through hole (6) formed in a part of the burner tile (4) while being included in the burner outer cylinder, and on the outside of the liquid burner gun A cylindrical pulverized coal nozzle 8 capable of supplying a mixture of pulverized coal and primary air, which is a kind of gas, is disposed.

In addition, a secondary air supply cylinder 14 and a tertiary air supply cylinder 16, each of which is equipped with a secondary air swirler 10 and a tertiary air swirler 12, are installed outside the pulverized coal nozzle 8. . A flow divider 18 is provided between the secondary air supply cylinder and the tertiary air supply cylinder to separate external air introduced by the swirlers 10 and 12 into secondary air and tertiary air. Let's do it.

The pulverized coal burner is pulverized by the burner nozzle which is supplied through the pulverized coal nozzle 8 and the primary air is installed at the tip of the liquid burner gun 2 to form a flame zone. The secondary and tertiary air swirlers 10 and 12 attached to the 14 and the tertiary air supply cylinder 16 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.

The present invention seeks to propose a pulverized coal burner having an improved structure in order to pursue more improved complete combustion in such a conventional low nitrogen oxide burner.

In other words, it suppresses the accumulation of pulverized coal in the pipe and stabilizes combustion, and increases the mixing of pulverized coal and primary air and the residence time in the furnace to pursue complete combustion and reduction of pollutants. An object of the present invention is to provide a pulverized coal burner that suppresses the formation of the coal.

In order to achieve this object, the present invention connects and installs a liquid burner gun for injecting liquid fuel into a furnace, and arranges a pulverized coal nozzle for supplying the furnace with a mixture of pulverized coal and primary air on the outside thereof. Composed of an air supply cylinder equipped with a plurality of air swirlers for sucking and turning the outside air on the outside, and a flow divider installed inside the air supply cylinder to separate and guide the outside air to burn pulverized coal in the furnace. In a pulverized coal burner using thermal energy generated in the process, a part of the pulverized coal nozzle is cut to form a communication hole, and a variable block for controlling the flow of the pulverized coal and primary air is installed at an adjacent position of the communication hole, Secondary air supply cylinder equipped with a secondary air swirler that sucks and turns secondary air between the nozzle and the air supply cylinder. And a.

Particularly, a part of the pulverized coal nozzle in which the variable block is installed is configured as a venturi-type pressure regulator tube, and the variable block selectively opens and closes the communication port to control the flow of pulverized coal and primary air to the inside and outside of the pressure regulator tube. Prevents pulverized coal accumulation in the pipe under operating load and realizes combustion stabilization.

In addition, the secondary air swivel increases the mixing of pulverized coal and primary air and the residence time in the furnace by turning pulverized coal to reduce complete combustion and pollutants, and in the primary combustion zone near the burner, On the wake side of the flame zone, the formation of excess air suppresses the rapid generation of nitrogen oxides to promote the reduction of nitrogen oxides produced in the main combustion zone and the complete combustion of incomplete combustion materials. In addition, by promoting the backward movement of the fuel by strengthening the liquid burner dry axial velocity component of the combustion air by the swirler, the nitrogen component in the fuel is induced into the nitrogen molecule, thereby obtaining partial fuel nitrogen oxide production.

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

2a and 2b is a state diagram according to the operation of the variable pulverized coal burner according to the present invention

Figure 3 is a graph showing the temperature distribution characteristics in the furnace of the pulverized coal burner according to the present invention

4 is a graph showing the oxygen and dust emission characteristics of the pulverized coal burner according to the present invention

5 is a cross-sectional view schematically showing the configuration of a conventional pulverized coal burner

Explanation of symbols on the main parts of the drawings

30: burner tile 34: 4th air supply container

36: 4th air turning machine 38: 3rd air supply container

40: tertiary air swirler 42: first flow divider

44: secondary air supply container 46: secondary air turning machine

48: second flow divider 50: burner nozzle

54: pulverized coal nozzle 56: communication port

58: 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 shows a schematic cross-sectional view of a pulverized coal burner according to a feature of the present invention.

A through hole 32 is formed in the burner tile 30 of the furnace (not shown), and the fourth air supply cylinder 34 is installed outside the burner tile in contact with the through hole. A quaternary air swirler 36 for sucking and swirling the quaternary air (external air) is mounted.

A tertiary air supply cylinder 38 is provided outside the quaternary air supply cylinder 34, and the tertiary air turning to suck and turn tertiary air (external air) inside the tertiary air supply cylinder. The machine 40 is mounted.

A first flow divider 42 is provided between the fourth air supply cylinder and the third air supply cylinder to separate the third and fourth air to form a flow path.

On the other hand, the secondary air supply cylinder 44 is installed outside the tertiary air supply cylinder 38 in accordance with the characteristics of the present invention, and the secondary air (external air) is sucked into the secondary air supply cylinder. A secondary air swirler 46 for turning is mounted, and a second flow divider 48 for forming a flow path of secondary air is also provided between the tertiary air supply cylinder and the secondary air supply cylinder.

A liquid burner gun 52 equipped with a burner nozzle 50 is disposed at the center of the through hole 32, and the outside of the liquid burner gun is capable of mixing and supplying pulverized coal and primary air obtained by pulverizing coal. Cylindrical pulverized coal nozzle 54 according to another feature of the invention is installed in contact with the secondary air supply cylinder 44. In particular, as a part of the pulverized coal nozzle 54 is cut to form the communication port 56, a part of the pulverized coal nozzle forms an open pressure regulator tube 58 in the form of a venturi.

That is, the inlet portion having a diameter smaller than the diameter of the pulverized coal nozzle from the cut end to a predetermined length is formed, and the inlet portion forms a slope portion at the end portion, and the portion having the same diameter as the diameter of the pulverized coal nozzle portion at the end portion of the slope portion again. The parallel part of the length is maintained and then formed to be inclined toward its center from the end of the parallel part to the end of the pressure adjusting tube.

On the other hand, on the outer circumferential surface of the inlet is provided a variable block 60 in the form of a ring (movable in the axial direction), when the variable block moves toward the tip of the inlet to block the communication port 56, pulverized coal and primary The mixture of air flows only to the pressure adjusting pipe 58, and when the communication port 56 is opened depending on where the variable block 60 is located at the inlet, the degree of opening thereof is changed so that pulverized coal and primary The amount of air guided to the outside of the pressure regulator tube 58 will vary.

Looking at the operation of the pulverized coal burner according to the present invention having such a structure, the liquid fuel is injected from the burner nozzle of the liquid burner gun 52 as the burner is operated, the spark is ignited, and at the same time the pulverized coal nozzle 54 Pulverized coal and primary air are ejected into the furnace through the pressure adjusting pipe 58, and at this time, depending on the load of the pressure adjusting pipe 58, that is, at the time of low load, the variable block 60 is shown. ), The pulverized coal and the primary air pass through the inside of the pressure adjusting pipe 58 to be blown into the furnace by moving from the inlet to block the communication port 56, and the high-load variable block 60 as shown in FIG. ), The pulverized coal and the primary air are guided to the outside of the pressure regulator tube 58 and mixed with the secondary air turned by the secondary air swirler 46 by moving from the inlet to open the communication port 56. These mixed pulverized coal and combustion air 2 is guided to the flow divider 48 is spread out in the furnace. In this process, the pulverized coal emitted into the furnace is concentrated in the axial direction of the burner nozzle. This is because the pulverized coal, which has a relatively higher proportion than the primary air, has its own centrifugal force inside the pulverized coal nozzle. Because it has.

Combustion air, which is external air, is separated from the 4th air swirler 36 and the 3rd air swirler 40, respectively, and is converted into 3/4 quaternary air having a turning force, and the combustion air is the first flow divider 42. It passes through the through hole through the outside and the inside of the furnace.

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

That is, at low load, as shown in FIG. 2A, the combustion of concentrated air is realized by pursuing the concentration of pulverized coal and maintaining the pulverized coal ratio with respect to the primary air. Nitrogen oxides are reduced to nitrogen molecules by enclosing the air-poor turbulent flame zone formed by pulverized coal and primary air, thereby creating a fuel mixing delay atmosphere and promoting evaporation and pyrolysis of the fuel due to high temperature in the vicinity of the through hole of burner tile Induce to be.

In addition, at high loads as shown in FIG. 2B, the mixture of primary air and pulverized coal passing through the outside of the pressure adjusting tube may be controlled by adjusting the burner nozzle axial mass distribution through the secondary air swirler. By stratification of the nitrogen component contained in the volatile matter of pulverized coal is converted to nitrogen molecules rather than nitrogen oxides. As a result, it is possible to suppress the generation of nitrogen oxides intensively generated at the beginning of the flame zone. In this process, the unburned coal, which is inevitably increased, is completely burned by being actively mixed with the fourth air in the wake of the flame zone. In the post-combustion zone, most of the fuel components that started to burn from the middle of the flame zone are continuously burned, and they are actively mixed with the sufficiently heated tertiary air while moving to the flame zone wake to reduce nitrogen oxides. .

As another effect, as shown in Figure 3, the flame temperature in the furnace according to the present invention shows a more gentle distribution than in the conventional burner, which is because there is no sudden increase in flame temperature near the burner tile through-holes It has been shown to suppress production.

In addition, as shown in Figure 4, compared to the conventional burner pulverized coal burner according to the present invention is also reduced dust amount, there is an advantage that can be operated by reducing the operating load of the burner to at least 20%. In addition, by reducing the amount of excess air for each load, the operation cost can be reduced.

Claims (3)

A liquid burner gun connected to the furnace for injecting liquid fuel, a pulverized coal nozzle disposed outside of the pulverized coal and primary air and supplied to the furnace, and a plurality of suction and turning external air outside the liquid burner gun And an air feeder equipped with an air swirler of each, and a flow divider installed inside the air feeder to separate and induce the external air, and to the pulverized coal burner using thermal energy generated when burning pulverized coal in the furnace. In A portion of the pulverized coal nozzle 54 is cut to form a communication port 56, and is provided at an adjacent position of the communication port to control the flow of the pulverized coal and primary air; Pulverized coal is characterized in that the secondary air supply cylinder 44 is provided between the pulverized coal nozzle 54 and the air supply cylinder 38 is equipped with a secondary air swirler 46 for sucking and turning the secondary air. burner. The pulverized coal burner according to claim 1, wherein a part of the pulverized coal nozzle (54) provided with the variable block (60) is composed of a venturi-type pressure regulator tube (58). According to claim 1 or 2, The variable block 60 is characterized in that for selectively opening and closing the communication port 56 to control the flow of the pulverized coal and the primary air to the inside and outside of the pressure adjusting pipe (58). Pulverized coal burner.