JP4241342B2 - Pulverized coal burner and low ash melting point sub-bituminous pulverized coal combustion method - Google Patents

Description

  The present invention relates to a method for burning pulverized coal burners and low ash melting point subbituminous pulverized coal used in coal-fired boilers. More specifically, the present invention relates to a pulverized coal burner that can control the location or amount of slag in a furnace and a combustion method of low ash melting point subbituminous pulverized coal using the same.

  An outline of the structure of a boiler that burns pulverized coal is shown in FIG. Reference numeral 1 denotes a coal-fired boiler that burns pulverized coal. The boiler has a plurality of pulverized coal burners 2 penetrating through the furnace wall. By this burner, pulverized coal fuel is fed together with air and burned in the furnace, and the furnace wall water pipe 3, superheater 4, The charcoal unit 5 is heated. Depending on how the pulverized coal fuel is burned and the quality of the coal, slag accumulates on the furnace wall, unfavorable operating conditions such as a decrease in the heat transfer amount of the furnace wall water pipe 3 and an unbalance of the heat transfer amount to the heat transfer surface in the furnace When the blockage becomes excessive, the pressure loss increases, and even a satisfactory boiler cannot be operated.

  Therefore, in a boiler that burns pulverized coal, various devices have been made to prevent slag from adhering to the furnace wall.

  In Patent Document 1, the flame from the burner is arranged so as to give a turning force, and in addition, a nozzle for curtain air or curtain exhaust gas is provided, air or exhaust gas is blown, and a separation zone is formed between the upstream and downstream burners. By making it, the pulverized coal flames of the upstream and downstream burners do not interfere with each other, and slag generation around the burner is prevented.

  In Patent Document 2, a density separation zone (deflector block) is arranged in the pulverized coal mixture nozzle of the burner, the pulverized coal mixture nozzle is eccentric with respect to the air nozzle, or supplied from the outer periphery of the pulverized coal mixture nozzle By providing a means for swirling the combustion air to be burned or a means for changing the direction of the tip of the burner, a flow path is created to prevent the flow of high pulverized coal concentration from hitting the furnace wall. A technique for burning in the center is disclosed.

  In Patent Document 3, a twist plate is provided in the pulverized coal mixture nozzle to twist the pulverized fuel to the inside of the furnace or to increase the amount of air from the furnace wall so that slag adheres to the furnace wall. Disclosed techniques are disclosed.

  A typical structure and operation of a pulverized coal burner of a current coal-fired boiler incorporating these conventional technologies will be described with reference to the drawings.

  4 is an AA cross-sectional view of the burner portion of the coal fired boiler of FIG. In this boiler, pulverized coal burners 2 are provided at the four corners of the furnace. The pulverized coal burner 2 includes a pulverized coal mixture nozzle 10 and an air nozzle 11 so as to surround it. The pulverized coal mixture nozzle 10 is attached eccentrically from the center of the air nozzle 11. With this structure, as shown in the figure, the pulverized coal mixture forms a high pulverized coal concentration region 8 in the central portion, a low pulverized coal concentration region 7 in the portion close to the furnace wall, and a secondary in the vicinity of the furnace wall. An air-rich flow region (secondary air-rich region 9) is formed. This prevents slag from adhering and accumulating on the furnace wall 6.

  Further, FIG. 5 is a perspective view of an example in which a density separation zone (deflector block 12) is arranged in a burner pulverized coal mixture nozzle 10 and a twist plate (flux rotating plate 13) is provided. That is, the pulverized coal mixture has its pulverized coal concentration distribution changed by the block 12 and is twisted by the twist plate (flux rotating plate 13), and when it is ejected into the furnace, it is biased toward the center away from the furnace wall. In this way, the high pulverized coal concentration region is ejected, and the air ejected from the air nozzle 11 becomes the secondary air rich region 9 in the vicinity of the furnace wall so that slag is not deposited on the furnace wall.

  When high slagging charcoal is burned by such a technique, it is possible to reduce the molten slag near the burner and to the furnace wall, but for example, the quality is not constant among sub-bituminous coal with high slagging properties, There are various types of coal, so in the case of coal that is not so slagging, there is too little slag adherence in the furnace, the steam temperature has not reached due to excessive heat absorption of the furnace, the slag has increased to the convection heat transfer surface, air and Problems such as an increase in unburned fuel due to poor fuel mixing occur.

Japanese Patent Application Laid-Open No. 7-119923 JP-A-10-213309 JP-A-10-274403

  Accordingly, the present invention provides a pulverized coal burner capable of controlling the location or amount of slag in the furnace and a method for burning low ash melting point sub-bituminous pulverized coal using the same, in view of the above-mentioned problems of the prior art. To the goal.

  The present invention is a pulverized coal burner that injects a pulverized coal mixture together with combustion air into a furnace and performs swirl combustion, and is disposed surrounding the pulverized coal mixture nozzle and the pulverized coal mixture nozzle. The pulverized coal mixture nozzle is provided with an adjusting means for varying the degree of protrusion at least at one location in the pulverized coal mixture nozzle. And the distribution of the pulverized coal mixture on the downstream side of the block, and by adjusting the degree of protrusion of the block according to the quality of the pulverized coal, the distribution of the pulverized coal in the nozzle cross section is changed. , It is possible to control the place or amount of slag attached.

  The adjusting means has a female screw on a shaft rod extending from the back surface of the block, and is arranged to be screwed with a male screw fixed to the air-fuel mixture nozzle. The block can be advanced and retracted by rotating the shaft rod. What is necessary is just to comprise. Further, it may be a means for driving the block forward and backward by hydraulic pressure or air pressure.

  Furthermore, in the pulverized coal burner of the present invention, the flux rotating plate of the pulverized coal mixture is provided with a rotating means, and is installed rotatably around the central axis in the mixture flow direction. By changing the flux rotation angle, the location or amount of slag can be controlled.

  The rotating means may be configured such that a shaft rod extending from the central portion of the side end of the flux rotating plate passes through the nozzle wall and can rotate the shaft rod from the outside. The rotation driving means can be manual or electric.

  Furthermore, the low ash melting point sub-bituminous pulverized coal combustion method, which is another aspect of the present invention, is a low ash melting point submerged pulverized coal mixture injected into a furnace together with combustion air to perform swirl combustion. A sub-bituminous pulverized coal combustion method, in which an air flow surrounding the pulverized coal mixed airflow is formed and injected into a furnace with a pulverized coal mixed airflow, and at least one protrusion degree variable disposed in the nozzle is variable. By the block, the pulverized coal concentration distribution is variably changed in the cross section perpendicular to the flow direction of the pulverized coal mixed airflow, and the distribution pattern is changed by a certain angle by the flux rotating plate arranged downstream of the block. By rotating it, it is possible to control the place or amount of slag attached.

  Furthermore, in the low ash melting point sub-bituminous pulverized coal combustion method of the present invention, the flux rotating plate disposed downstream of the block can be rotated, and its distribution pattern is variably rotated, so that the slag adhesion site or The amount of adhesion can be controlled.

As described above, the effects of the present invention can be summarized as follows.
(1) Since the degree of protrusion of the pulverized coal concentration distribution adjustment block placed in the pulverized coal mixture nozzle is variable, the pulverized coal concentration distribution (in the nozzle cross section) can be adjusted according to the quality of the raw coal. Therefore, it is possible to adjust the pulverized coal concentration distribution (and temperature distribution, ash concentration distribution, etc.) in the cross section of the furnace in the furnace and take it to appropriate slag adhesion.
(2) Further, since the distribution pattern can be rotated by rotating the flux rotating plate arranged downstream of the block, the pulverized coal concentration distribution (extension) in the furnace cross section in the furnace is adjusted together with the block adjustment. Temperature distribution, ash concentration distribution, etc.) and can be taken for proper slag adhesion.
(3) This makes it possible to provide a burner that can freely burn low ash melting point subbituminous coal.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a schematic diagram (A) of a pulverized coal mixture nozzle of a burner according to the present invention and a schematic diagram (B) of a conventional pulverized coal mixture nozzle of a burner.

  In FIG. 1A, the pulverized coal mixture nozzle 10 is curved approximately 90 degrees, and the left side is the outlet to the furnace. A block 12 for adjusting the pulverized coal concentration distribution of the pulverized coal mixture provided with adjusting means 14 is attached to the nozzle on the inside immediately before the curved portion of the nozzle and on the outside of the curved portion of the nozzle. The adjusting means 14 is such that a female screw of a shaft extending from the back surface of the block is screwed with a female screw fixed to the nozzle, and the rotation of the shaft allows the block to go to the outside or to the inside. A fixed flow velocity rotating plate 13 (twist plate) is attached to the horizontal portion of the nozzle downstream of the block attachment portion as shown in the figure. In the illustrated state, the inner block 12 does not protrude into the nozzle, and the outer block 12 protrudes moderately into the nozzle.

  FIG. 1B is a conventional comparative example. In the figure, the block 12 is fixed and always protrudes. The flow velocity rotating plate 13 (twist plate) is in the same mounting state as (A).

  In comparison with the conventional example (B) and the embodiment (A) of the present invention, first, in the conventional example (B), the flow of the pulverized coal mixture in the pulverized coal mixture nozzle 10 is Shows a substantially uniform concentration distribution, but it collides with the block, the pulverized coal concentration in the opposite direction to the block increases downstream, and the pulverized coal concentration changes to a concentration distribution behind the block. And downstream of that, the flux of the pulverized coal mixture is rotated by about 90 degrees by a fixed flow velocity rotating plate 13 (twist plate), and the pulverized coal mixture becomes a concentration distribution pattern as shown in the same sectional view. It is ejected into the furnace. Since the nozzle is arranged so that the left side of the cross-sectional view faces the center of the furnace and the right side faces the furnace wall, the furnace wall becomes an area rich in air and pulverized coal, and slag adheres to the furnace wall. It does not burn.

  On the other hand, in Embodiment 1 (A) of the present invention, the upstream inner block 12 in the pulverized coal mixture nozzle 10 is adjusted so as not to protrude into the nozzle in this case, so that the vicinity of the downstream outer block 12 is not reached. The pattern is almost uniform, but after being kicked by the downstream outer block 12, the lower side of the nozzle becomes high concentration, and then the pulverized coal mixture flux is rotated by approximately 90 degrees on the fixed flow velocity rotating plate 13 (twist plate). Thus, a density distribution pattern as shown in the cross-sectional view is obtained. In other words, since the pulverized coal has a high concentration on the furnace wall side and the pulverized coal has a low concentration on the center side, a predetermined degree of slag can be adhered to the furnace wall. Further, the degree of protrusion of the two blocks in the figure can be freely adjusted, and the concentration pattern can be changed according to conditions such as the quality of coal, for example, and combustion is possible.

  FIG. 2 is a schematic diagram (A) of a burner pulverized coal mixture nozzle according to the present invention and a schematic diagram (B) of a conventional burner pulverized coal mixture nozzle.

  In FIG. 2A, the pulverized coal mixture nozzle 10 is curved approximately 90 degrees, and the left side is an outlet to the furnace. A fixed pulverized coal concentration distribution adjustment block 12 is attached to the nozzle on the inner side immediately before the curved portion of the nozzle. As shown in the figure, a rotatable flow speed rotating plate 13 (twist plate) is attached to the horizontal portion of the nozzle that has passed through the bent portion downstream of the block attaching portion. From the vicinity of the center of the right side end of the rotating plate, a shaft rod is provided with a rotating means 15 configured to pass through the nozzle wall and rotate the shaft rod from the outside.

  FIG. 2B shows a conventional comparative example, which is exactly the same as that in the first embodiment, and thus the description thereof is omitted.

  In the case of Example 2 (A), the flow of the pulverized coal mixture in the pulverized coal mixture nozzle 10 exhibits a substantially uniform concentration distribution in front of the block 12, but collides with the block and in the downstream thereof. The pulverized coal concentration in the direction opposite to the block is increased, and the pulverized coal concentration is changed to a light concentration distribution behind the block. And downstream of this, in this example, the flux of the pulverized coal mixture is rotated by approximately 45 degrees by the rotatable flow velocity rotating plate 13 (twist plate), resulting in a concentration distribution pattern as shown in the same sectional view. Therefore, this method also allows a predetermined degree of slag to adhere to the furnace wall.

  Although not shown in the drawing, a pulverized coal mixture nozzle having a flow velocity rotating plate provided with rotating means and a block provided with adjusting means is also possible, and finer adjustment is possible.

  With the burner and combustion method of the present invention, low ash melting point sub-bituminous pulverized coal can be efficiently burned to generate power. Therefore, in Southeast Asia and the United States, industrial applicability is high as an indispensable elemental technology for developing boilers for low-ash melting point subbituminous coals that are in high demand.

It is the schematic (A) of the pulverized coal mixture nozzle of this invention burner, and the schematic (B) of the pulverized coal mixture nozzle of the conventional burner. It is the schematic (A) of the pulverized coal mixture nozzle of this invention burner, and the schematic (B) of the pulverized coal mixture nozzle of the conventional burner. 1 is a schematic illustration of a typical coal fired boiler with a pulverized coal burner. It is AA sectional drawing of the burner part of the coal burning boiler of FIG. It is a perspective view explaining the conventional pulverized coal burner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coal-fired boiler 2 Pulverized coal burner 3 Furnace wall water pipe 4 Superheater 5 Coal saving device 6 Furnace wall 7 Low pulverized coal concentration area 8 High pulverized coal concentration area 9 Secondary air rich area 10 Pulverized coal mixture nozzle 11 Air nozzle 12 Block 13 Flux rotating plate 14 Adjusting means 15 Rotating means

Claims (4)

  A pulverized coal burner that injects a pulverized coal mixture together with combustion air into a furnace to perform swirl combustion, and the combustion air disposed around the pulverized coal mixture nozzle and the pulverized coal mixture nozzle A pulverized coal mixture nozzle having a nozzle, and a pulverized coal concentration distribution adjustment block of the pulverized coal mixture provided with an adjusting means that makes the degree of protrusion variable at least in one place in the nozzle, The pulverized coal mixture has a flux rotating plate on the downstream side, and by adjusting the degree of protrusion of the block according to the quality of the pulverized coal, the distribution in the nozzle cross section of the pulverized coal is changed, and the slag adheres. A pulverized coal burner characterized in that the location or the amount of adhesion can be controlled.   The flux rotating plate of the pulverized coal mixture is provided with a rotating means, and is rotatably installed around the central axis in the mixture flow direction, and according to the pulverized coal quality, the flux rotation angle is changed, The pulverized coal burner according to claim 1, wherein the slag adhesion location or adhesion amount can be controlled.   A low ash melting point sub-bituminous pulverized coal combustion method in which swirl combustion is performed by injecting a low ash melting point sub-bituminous pulverized coal mixture together with combustion air into a furnace, the pulverized coal mixed air flow together with the pulverized coal mixed air flow When forming the air flow surrounding the blast furnace and injecting it into the furnace, the pulverized coal concentration distribution in the cross section perpendicular to the flow direction of the pulverized coal mixed airflow is provided by at least one block of variable protrusion disposed in the nozzle. , And the distribution pattern or amount of slag can be controlled by rotating the distribution pattern by a certain angle by a flux rotating plate arranged downstream of the block. Low ash melting point sub-bituminous pulverized coal combustion method.   The slag adhesion location or adhesion amount can be controlled by making the flux rotating plate disposed downstream of the block rotatable and variably rotating its distribution pattern. Low ash melting point sub-bituminous pulverized coal combustion method.

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