KR101206354B1 - A plasma ignition burner - Google Patents

Abstract

The present invention relates to a plasma ignition burner. The plasma ignition burner includes at least two stage burner barrels and a plasma generator for igniting pulverized coal in the first stage burner barrel of the at least two stage burner barrels, wherein the combustion flame of the previous stage burner barrel is the next stage burner. Ignite the pulverized coal in the barrel or burn it with air replenished in the next stage burner barrel, wherein the axial direction of the plasma generator is parallel to the direction along the pulverized coal-containing air flow entering the first stage burner barrel, and at the same time And parallel to the axes of the barrels.

Plasma, Ignition Burner, Barrel, Pulverized Coal, Flame, Plasma Generator, Bending Tube, Guide Plate, Main Pipe, Branch Pipe, Clinkers

Description

Plasma Ignition Burner {A PLASMA IGNITION BURNER}

TECHNICAL FIELD The present invention relates to the pulverized coal combustion art, and more particularly to a plasma ignition burner.

Coal-fired power is the main electricity generation scheme currently adopted by other countries. Ignition is the main aspect of the combustion process of a boiler. In order to expand the capacity of the boiler, how to quickly and economically achieve the starting process of the boiler is an important problem to be urgently solved.

Plasma ignition technology has recently been developed to replace oil ignition, which consumes a large amount of combustion oil.

In order to be able to ignite the internal coal, conventional plasma ignition devices employ a so-called "pre-combustion chamber" technique. The precombustion chamber is usually configured to maintain the temperature of the burner barrel by attaching a layer of refractory material to the interior of the firebox. The chamber wall of the precombustion chamber has a very high temperature through initial heating to assist in igniting the fuel (even independently). The precombustion chamber is long (about 2 meters) and vaporizes pulverized coal in the pulverized coal-containing air stream entering the precombustion chamber through the action of plasma, thereby generating a large amount of combustible gas mainly composed of carbon monoxide (CO) and the like. Then, thermal energy is released when a combustible gas is used to ignite the continuous pulverized coal. It is also a hierarchical ignition system, because the temperature of the precombustion chamber is so high that pulverized coal can no longer be used because it easily forms clinkers inside the precombustion chamber.

In order to solve the above problems, a new structure of hierarchical burner barrels has been proposed. As shown in FIG. 1, the plasma ignition burner is multi-stage, such as a first stage burner barrel 104, a second stage burner barrel 110, a third stage burner barrel 108, a fourth stage burner barrel 110, and the like. Burner barrels (the number of steps may be more than four or less than four, depending on power and space size). The pulverized coal-containing air stream entering the pulverized coal-containing air flow inlet 102 (as shown by the wide arrow in FIG. 1) is divided into two paths by the spacer 116 to separate the first stage burner barrel 104 and the second stage burner. Each enters barrel 106. The plasma generator is inserted into the first stage burner barrel 104 along the axial direction of the multistage burner barrels and ignites the pulverized coal airflow entering the first stage burner barrel 104, thereby causing the first stage pulverized coal flame A to be generated. do. The generated flame further ignites the pulverized coal-containing air stream in the second stage burner barrel, whereby a second stage pulverized coal flame B is formed. At the same time, the air stream coming from the air inlet 114 (as indicated by the narrow arrow in FIG. 1) enters the third stage burner barrel 108 through the third inlet 120 and provides oxygen for the second stage pulverized coal flame. , Thereby forming the third stage pulverized coal flame C. Air will enter the fourth stage burner barrel through the fourth inlet 122 to further supplement the oxygen. At the same time, the airflow flows in the space between the outer wall of the previous stage burner barrel and the burner outer barrel 118 before entering the next stage burner barrel, thereby cooling the burner barrels to prevent clinkering. Do this.

In the above technique, the plasma generator is inserted along the axial direction of the burner barrels and the pulverized coal-containing airflow inlet, and the airflow is arranged in a direction perpendicular to the axis of the burner barrels. In other words, the direction of the plasma flame is perpendicular to the direction of the airflow entering the first stage burner barrel. Therefore, there is a further need for a guide plate (not shown) for deflecting the airflow in parallel. Likewise, the direction in which the second stage pulverized coal enters into the second stage burner barrel is also perpendicular to the direction of the flame injected from the first stage burner barrel, so it is also necessary to add a guide plate to make the directions parallel. However, the guide plate is not able to deflect airflow perfectly due to space limitations. Since the two airflows are not absolutely parallel, the incoming airflow blows and deflects the plasma flame (or previous stage flame), resulting in an increase in the temperature of the barrel wall and pulverized coal.

Further, in this technique, since both the pulverized coal-containing air flow and the air flow enter the direction perpendicular to the burner barrels, the concentration of the pulverized coal and the velocity of the air flow in the section plane perpendicular to the burner barrels are not equal, whereby This will adversely affect burner quality.

Later, in order to be easily arranged locally, a plasma ignition burner configured as shown in FIG. 2 is used. In summary, only the pulverized coal-containing air flow inlet 102, the first stage burner barrel 104 and the second stage burner barrel 106 are shown in the figures, and the air inlet 114, burner outer barrel 118, A structure corresponding to a three stage burner barrel and a fourth stage burner barrel is shown in FIG. 1. The pulverized coal-containing air flow entering from the inlet 102 is divided into two parts by the barrel wall of the first stage burner barrel, the center portion enters the first stage burner barrel 104, and the peripheral portion of the first stage burner barrel and the outer barrel ( 202) (the pulverized coal containing airflow inlet 102 is provided thereon) and enters into the second stage burner barrel from the second inlet 204 of the second stage burner barrel. As shown in the figure, the plasma generator is inserted along the radial direction of the burner and the pulverized coal-containing air flow is blown along the axial direction of the burner barrels, with the two directions keeping vertical. Under the action of the pulverized coal-containing air stream, the plasma flame is deflected and provided, whereby the temperature of the side surface to which the plasma flame is deflected is greatly increased, thereby forming a mass of the material.

Therefore, a new technique is needed to prevent the pulverized coal from forming into agglomerates in the walls of the burner barrels.

Therefore, it is an object of the present invention to provide a plasma generator which can alleviate the problem of clinkering of material. As can be seen from the above description of the prior art, the angle existing between the insertion direction of the plasma generator (i.e., the direction of the plasma flame) and the direction of the pulverized coal-containing airflow is a cause of the problem of the formation of the molten mass.

Therefore, for the above object, the core of the present invention is to rearrange the pulverized coal-containing air stream and the plasma generator in order to make the direction of the pulverized coal-containing air stream entering the first stage burner barrel coincide with the direction of the plasma flame.

In addition, in order to solve the problem of the formation of agglomerates, it is necessary to make the pulverized coal-containing air stream or the next air stream as much as possible to match the pulverized coal flame of the previous stage. To this end, the invention comprises a plasma ignition burner comprising at least two stage burner barrels and a plasma generator for igniting pulverized coal in the first stage burner barrel of the at least two stage burner barrels, wherein The combustion flame of the first stage burner barrel ignites the pulverized coal in the next stage burner barrel or burns with the air replenished in the next stage burner barrel, and the axial direction of the plasma generator prevents the coal dust containing air flowing into the first stage burner barrel. Parallel to the following direction and at the same time parallel to the axis of the burner barrels.

According to the present invention, it is effectively alleviated the problem of the formation of agglomerates which occurs in the walls of the burner barrels.

3 is a partial cross-sectional view schematically illustrating a first embodiment of another plasma ignition burner according to the first embodiment of the present invention. In summary, this figure only shows a pulverized coal containing airflow inlet 102, a first stage burner barrel 104 and a second stage burner barrel 106 similar to those shown in FIG. 2. Since the structure of the multistage structure of the burner barrels has been described above, it is not repeated here. As described in the "Background Art", the number of stages of burner barrels into which pulverized coal-containing air flow enters, the number of stages of burner barrels into which air directly enters, and the number of stages of burner barrels are not limited, and may be determined according to power demand and space size. Can be. The total number of stages may be from stage 2 to stage 3, stage 4 or more, and the air stream as shown in FIG. 1 will be a pulverized coal containing air stream, depending on the application.

The essence of the invention is to make it parallel to the direction of the pulverized coal-containing air flow entering the first stage burner barrel in the direction of insertion of the plasma generator 302 and at the same time parallel to the axis of the burner barrel. Therefore, the pulverized coal-containing air stream enters into the burner barrel parallel to the axis of the burner barrel without the distribution asymmetry of the pulverized coal on the cross-sectional plane of the burner barrels due to the inertia of the pulverized coal-containing air stream. Further, since the spraying direction of the plasma flame of the plasma generator corresponds to the direction of the pulverized coal-containing air flow entering the burner barrel, the plasma flame will not be sprayed to be deflected against the wall of the burner barrel. These two points effectively alleviate the problem of lump formation that occurs at the walls of the burner barrels.

In the first embodiment shown in FIG. 3, the above technical solution provides a bending tube 308 for guiding the pulverized coal-containing air stream and the plasma generator 302 through the wall of the bending tube along the axial direction of the burner barrels. ) Is inserted into the first stage burner barrel 104. In order to equalize the distribution in the cross section plane without radiating to one side due to the centrifugal force when the pulverized coal-containing air flow enters the straight burner barrel at the position of the AA cross section plane, radians of the bending tube 308 are possible. Is set gently. However, as long as radians are present, centrifugal forces are unavoidable and therefore pulverized coal will be deflected to one side in the burner barrel. To avoid this problem, in one preferred example, the guide plate 306 is arranged along the axis of the bending tube 308 and one end of the guide plate on one side of the burner barrel is parallel to the axis of the plasma generator, the first stage burner Extends near the inlet 310 of the barrel 104. At the same time, the ends of the plasma generator 302 and the guide plate 306 are arranged on the axis of the burner barrel (of course the position of the end of the guide plate 306 will be deflected to some extent with respect to the axis of the burner barrel). Therefore, the guide plate 306 not only changes the flow direction of the pulverized coal-containing air flow to make it parallel to the plasma flame, but also increases the concentration of pulverized coal entering the central barrel (which helps ignition) by the centrifugal effect. Concentrate some of the pulverized coal near the central axis of the burner and near the plasma flame. Compared with the structure shown in FIG. 1, only one guide plate is used to simultaneously change the flow direction of the pulverized coal-containing air stream entering each stage burner barrel, so that the structure is simple and the resistance is relatively small. Since the space inside the bending head is large, the shape of the bending plate is planar and will be various bending surfaces (example shown in FIG. 4) to further increase the concentration of pulverized coal entering the center barrel.

As shown in FIG. 3, a large portion of the plasma generator 302 is exposed to a pulverized coal-containing air stream. In order to prevent the plasma generator from abrasion by the pulverized coal-containing air flow, an anti-wear protection sleeve (such as a ceramic sleeve) can be used to protect the plasma generator. Also, to reduce the resistance, the windy surface of the sleeve will be made into a V shape.

In addition to solving the problem of the formation of agglomerates in comparison with the burner inserted along the radial direction shown in FIG. 2, this burner also has a strong ignition capability. In particular, the reason is as follows. The plasma flame is located at the center line of the burner, and the center barrel is circular, so that the plasma flame in each direction has the same ignition capability, the flame is uniform and the transmission capability is strong. On the other hand, if the ignition flame is arranged on one side of the center barrel of the burner, the temperature of the flame is high on one side of the plasma flame and low on the other side. In this case, if the internal coal burns, the ignition will fail.

In the first embodiment as described above, the concentration of the undifferentiated carbon in the central barrel of the burner depends on the concentration of the guide plate 306 in the bending tube 308. However, due to space limitations, the concentration in the central barrel cannot be increased without limitation, which adversely affects the efficiency of ignition. For this purpose, a second embodiment according to the invention as shown in FIG. 5 is provided as a second embodiment of the invention.

In summary, FIG. 5 shows only the parts corresponding to those in FIGS. 2 and 3, namely the first stage burner barrel 104 and the burner inner barrel 202. As explained in the above example, within the burner inner barrel 202, many stages of burner barrels may be arranged after the first stage burner barrel 104. Outside burner inner barrel 202 there are parts corresponding to burner outer barrel 118 and multi-level burner barrels after burner inner barrel 118 and inside burner outer barrel 118.

In this embodiment, the pipe for supplying the pulverized coal-containing air stream is branched into two pipes, namely, the main pipe 508 and the branch pipe 502. The main pipe 508 may be connected to the burner inner barrel 202 in a conventional manner or by employing the bending tube 308 in the first embodiment. At the same time, the central barrel 510 is guided from the first stage burner barrel 104 to the branch pipe 502. Similarly, the connection between the branch pipe 502 and the central barrel 510 adopts a conventional manner, or adopts a second bent tube 512 similar to the bent tube 308 of the first embodiment, and the first embodiment. An example guide plate 306 (not shown in FIG. 5) may also be used. The arrangement of the plasma generator 302 will be similar to that of the first embodiment.

In this way, the concentration of pulverized coal entering into the central barrel and further into the first stage burner barrel will be relatively high by directing the pulverized coal containing air stream directly into the central barrel using branch tubes to assist in ignition. As in the preferred embodiment, it is necessary to adjust the amount of pulverized coal-containing airflow entering and / or to increase the concentration of pulverized coal in the pulverized coal-containing airflow entering the plasma ignition burner as high as possible. For this purpose, a control device will be arranged at the branch points of the main and branch pipes to flexibly adjust the amount of pulverized coal entering the branch pipe.

As a variant of the above solution, if there are burner barrels with three or more steps to guide the pulverized coal-containing air flow in the burner, each step of the burner barrels will be distributed between the center barrel and the burner inner barrel. For example, if there are three stage burner barrels, the pulverized coal in the first stage burner barrel and the second stage burner barrel of the plasma ignition burner is simultaneously guided through the central barrel and the branch pipe (in this case, the central The barrel and inner structure are similar to that shown in FIG. 2, only the burner inner barrel of FIG. 2 is changed to the central barrel of FIG. 5) The pulverized coal in the third stage burner barrel enters from the main pipe. In contrast, the pulverized coal in the first stage burner barrel of the plasma ignition burner is guided through the central barrel and the branch pipe, and the pulverized coal in the second and third stage burner barrels enters from the main pipe.

In a preferred embodiment, a valve 504 is provided in the branch pipe, which actuates the valve in the starter ignition stage and the low load stable combustion stage of the burner and stops the valve operation when the ignition is complete and the burner is in a stable state. . This valve 504 is designed to integrate with the regulator 506, so that the regulator functions simultaneously as the regulator and the branch tube valve.

As can be seen from the above description of the second embodiment, the key to this embodiment is to increase the concentration of pulverized coal in the first stage burner barrel using branch tubes. Ignition using a plasma generator or providing a plasma generator along the axial direction of the burner barrel is not limited. Therefore, various embodiments of the second embodiment may or may not be combined with aspects of the first embodiment. In particular, the ignition device may be an oil gun other than a plasma generator, and its arrangement may be inserted along a direction other than axial insertion, including radial insertion and oblique insertion.

In the above solutions, since the branch pipe is arranged and the regulator is attached, the flow rate of the pulverized coal-containing air flow and the concentration of the pulverized coal in the central barrel of the burner can be adjusted independently, and an optimum ignition condition can be achieved. .

Further, in the old type burners mounted at the point, a convenient and inexpensive reconstruction means can be provided using the second embodiment described above, and thus the present invention can be applied.

For example, the pulverized pulverized coal burner adopted by many coal-fired power plants has a central barrel, and a mixture of pulverized coal and air is sent from the outside of the central barrel into the furnace. For example, LNASB axial vortex pulverized coal burners (see FIG. 6) developed by Mitsui Babcock Energy Ltd in the 80s of the 20th century adopted this kind of structure. In this structure, the oil gun is inserted into the central barrel 602 and the pulverized coal sent from the central barrel into the furnace is ignited by the flame of the oil gun. For burners of this kind, if the reconstruction of the plasma ignition technique is carried out directly, it is necessary to remove the structure of the central barrel 602, which causes a large change in the concentration distribution of pulverized coal and the air velocity inside the burner and This will affect the initial performance. However, this problem can be solved by adopting the second embodiment of the present invention. At the time of reconstruction of the plasma technology, the central barrel 602 is connected to the first stage burner barrel 104, the central barrel 510, the ignition device (such as the plasma generator 302) and as shown in FIG. 5. It is necessary to reconfigure into branch 502. And reconstruction of the original mechanism of the burner's pulverized coal-containing air flow (ie, the structure from the main air to the third air tube shown in FIG. 6) is unnecessary, thereby making the performance as consistent with the original burner as possible.

The reconstruction scheme forms a third stage burner (ie, a first stage burner barrel, a central barrel and an outer barrel). In fact, if possible, the second stage burner will be formed by the central barrel and the outer barrel without adding the first stage burner barrel. Further, burner barrels of further stages may be added to the central barrel, or burner barrels of further stages may be added to the outer barrel.

In addition, the igniter will be an igniter of some kind, either an original burner or a reconstituted burner, including an oil gun, a plasma igniter, and the like.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Apparently, the present invention is not limited to the above detailed description, but may be variously changed or replaced within the scope of the present invention.

The invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals are used for identical or corresponding technical features.

1 is a cross-sectional view schematically illustrating a plasma ignition burner according to the prior art;

2 is a partial cross-sectional view schematically illustrating another plasma ignition burner according to the prior art;

3 is a partial cross-sectional view schematically illustrating a first embodiment of another plasma ignition burner according to the present invention;

4 is a cross-sectional view taken along line A-A of FIG. 3;

5 is a partial cross-sectional view schematically illustrating a second embodiment of a plasma ignition burner according to the present invention;

6 is a cross-sectional view illustrating a structure of an axial swirl coal dust burner according to the prior art.

<Explanation of symbols for the main parts of the drawings>

102: pulverized coal-containing air flow inlet

104: first stage burner barrel

106: second stage burner barrel

118: burner outer barrel

202: Burner Inner Barrel

302: Plasma Generator

306: Information board

308: bending tube

310: inlet

502: branch pipe

508: main pipe

510: center barrel

512: second bending tube

Claims (9)

A plasma generator for igniting pulverized coal in at least two stage burner barrels and a first stage burner barrel of the at least two stage burner barrels, wherein the combustion flame of the previous stage burner barrel ignites the pulverized coal in the next stage burner barrel; Or a plasma ignition burner burning with air replenished in the next stage burner barrel, The axial direction of the plasma generator is parallel to the direction along the pulverized coal-containing air flow entering the first stage burner barrel, and at the same time parallel to the axis of the burner barrels, to direct the pulverized coal-containing air stream into at least two stages of the burner barrel. And a bending tube having radians, wherein one end of the bending tube at the side of the burner barrel is parallel to the axis of the burner barrel, and the plasma generator is arranged along the axial direction of the burner barrel. Plasma ignition burner, characterized in that it is inserted into the first stage burner barrel through the wall of the bending tube. The plasma ignition burner of claim 1, further comprising a guide plate arranged along an axis of the bending tube, wherein one end of the guide plate is parallel to the axis of the plasma generator at one side of the burner barrel. 3. The plasma ignition burner of claim 2, wherein the guide plate extends near an inlet of the first stage burner barrel. 4. The plasma ignition burner of claim 3, wherein the ends of the plasma generator and the guide plate are arranged on the axis of the burner barrels or deflected by a predetermined distance from the axis of the burner barrels. The plasma ignition burner according to any one of claims 2 to 4, wherein the shape of the cut surface of the guide plate is flat. The plasma ignition burner according to any one of claims 2 to 4, wherein the shape of the cut surface of the guide plate is a curved surface. The plasma ignition burner according to any one of claims 2 to 4, wherein an anti-wear protection sleeve for protecting the plasma generator is provided. The plasma ignition burner according to claim 7, wherein the wind blowing surface of the wear protection sleeve has a V shape. delete

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