JP2007187356A - Combustion furnace and boiler apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress oxygen concentration imbalance in gas, and to suppress gas temperature imbalance, by promoting effective practical use of a combustion space inside a combustion furnace. <P>SOLUTION: In this combustion furnace 1, burners 11 of a front wall A on one side of walls facing each other and burners 12 of a rear wall B are disposed in the same horizontal plane or in nearly same horizontal planes, and respective burner central axis 2 and burner central axis 3 are disposed in positions slightly out of alignment from each other, so that flame from the burners 11 provided in the front wall A partially collides with flame from the burners 12 provided in the rear wall B, and partially not. Flame not colliding with the front or rear wall A, B facing each other of the flame from the burners 11, 12, uses a space between side walls C and the burner flame as the combustion space, and flame close to the side walls C is thrusted in a bulging direction (the arrow (R) direction as shown in a figure) to the side wall side, so that there is action reducing spaces inside the combustion furnace not effectively used for combustion generated in areas β, β'. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a combustion furnace and a boiler apparatus that uses the combustion furnace as a combustion furnace of a steam generator.

  FIG. 3 shows a burner arrangement structure (sometimes referred to as opposed combustion arrangement) in which burners 4 and 5 are arranged on opposing front and rear walls A and B, which are basic burner arrangements in a combustion furnace of a boiler apparatus. The figure seen from the side of 1 side wall is shown. The burner 4 and the burner 5 are disposed at the positions of the front and rear walls A and B facing each other in the combustion furnace 1. At this time, a plurality of burners 4 and 5 are arranged in the same horizontal direction, and the burners 4 and 5 are arranged in a plurality of stages in the vertical direction, which is the direction in which the burner flame flows.

  FIG. 6 shows a horizontal sectional view of one prior art of the combustion furnace having the opposed combustion arrangement structure of FIG. The set of at least one burner 4 or 5 on the opposite furnace wall A or B is arranged such that the extension line of the central axis of each burner 5 or 4 is on the same horizontal plane in the opposite furnace wall B or A. Combustion gas collides from each of the opposing burners 4 and 5 and forms a circulating flow that returns to the flame root of the burner 4 or 5 again by changing the flow direction by approximately 180 degrees as shown in the gas flow 6 and the gas flow 7. Is shown.

  As another known example of the opposed combustion arrangement, as shown in FIG. 7, the burner 4 and the burner 5 face each other but are arranged so as to be located at an intermediate position between the burner intervals of the opposing wall surfaces. Some of them are arranged so that the flames of the burners facing each other do not collide with each other as in the arrangement and the invention described in JP-A-2002-122304, and a large swirling flow is formed in the horizontal plane in the furnace.

Furthermore, there is a so-called tangential combustion system in which burners are arranged on four wall surfaces of a combustion furnace to cause a swirling flow in the furnace, as in the invention described in Japanese Patent Application Laid-Open No. 7-119923.
JP 2002-122304 A Japanese Patent Application Laid-Open No. 7-119923

In the above prior art, as the capacity of the burner increases, the area that cannot be effectively used in the combustion furnace increases, resulting in gas temperature imbalance, and as a result, the rear heat transfer section installed in the downstream of the combustion furnace. A heat recovery imbalance was generated.
In the prior art shown in FIG. 7, the area (b) is not effectively used. The burner 4 installed on the opposite side wall surface of the region (b) needs to maintain a sufficient distance from the side wall C of the combustion furnace 1 in order to prevent so-called interference in which the flame directly hits the side wall C of the combustion furnace 1. . However, this distance is increasing due to the increased capacity of the burner. As a result, the region (b) located on the opposite side, which is the opposite position of the burner 4, becomes larger, and the region that is not effectively used as the combustion space is expanded. Since this region (b) is not utilized as a combustion space, the oxygen concentration in the gas is high and the gas temperature is low. Therefore, the gas temperature imbalance causes heat recovery imbalance in the rear heat transfer section of the boiler device.

The arrangement in which the extension line of the burner central axis in FIG. 6 is on the same line in the horizontal direction is an effective means for minimizing the area (b), but as the capacity of the burner increases, the gas temperature is still increased. An imbalance occurs.
FIG. 8 shows the mechanism. The gas flow thrown from the burner 4 or 5 on one furnace wall A or B collides with the gas flow from the burner 5 or 4 arranged on the other furnace wall B or A, and returns to the root of the burner flame. Forming a circulating flow to come is the ideal of this opposing arrangement, but in reality, as shown in FIG. 8, the flame (gas flow) ideally collides along each burner central axis. There is not, and the delicate lateral flow in the combustion furnace 1 influences and shifts to either. Although the influence of this phenomenon was small when the burners 4 and 5 had a relatively small capacity, the distance between the burners 4 and 5 and the side wall C of the combustion furnace 1 became longer due to the increased capacity of the burners 4 and 5. The area (a) that is not effectively used as a combustion space has expanded. In particular, in the case of this example, since the extension lines of the central axes of the burners 4 and 5 are on the same line, the state shown in FIG. (B) becomes a space that is not used effectively for new combustion (chattering phenomenon). As a result, the gas temperature distribution is an unstable phenomenon that changes with time, so when this phenomenon occurs in the combustion furnace 1 of the boiler unit, this phenomenon on the hardware side such as the opening of the burner register is eliminated. There was a problem that measures to do so could not be taken.

  FIG. 10 shows the most prominent example of the influence of the gas temperature imbalance generated in the combustion furnace 1 on the rear heat transfer section. 10A is a longitudinal sectional view of the combustion furnace 1 and the rear heat transfer portions 8 and 9 of the boiler apparatus, FIG. 10B is a horizontal sectional view of the burner installation portion of the combustion furnace 1, and FIG. It is a horizontal sectional view of heat transfer parts 8 and 9.

  In the region (a) where the burner flame of the combustion furnace 1 does not hit, the gas in the region where the oxygen concentration is high and the gas temperature is low flows to the region (c) in the rear heat transfer section 8 on the wake side. As an easy-to-understand example, when the rear heat transfer section is divided into the heat transfer section 8 and the heat transfer section 9 by the dividing wall 10 as shown in FIG. 10, the heat transfer tubes arranged in the heat transfer section 8 are affected by the region (c). Therefore, the heat collection of the heat transfer tubes in the region (c) is low, while the heat collection of the heat transfer tubes arranged on the opposite side of the region (c) of the heat transfer unit 8 is high. As a result, the outlet steam of the heat transfer section 8 causes a temperature difference between the left and right of the can. Similarly, in the heat transfer section 9, there is a problem that a steam temperature distribution opposite to that of the heat transfer section 8 is generated because of the area (C ′) affected by the area (A ′) of the combustion furnace 1.

  The inventions described in JP-A-2002-122304 and JP-A-7-119923 use a burner arrangement that forms a swirl flow without causing a flame from the burner to collide. The swirling flow of the flame is an effective method in terms of promoting the mixing of fuel and combustion air, although the mixing method is different from the collision method. However, since the circular or elliptical swirling flow is placed in the rectangular combustion furnace cross section, the problem similar to the prior art of FIG. is there.

In addition to the tangential combustion in which the burner is installed near the center of each side wall surface of the furnace as in the invention described in Japanese Patent Application Laid-Open No. 2002-122304, the tangential combustion in which the burner is arranged at the corner (corner) of the side wall of the combustion furnace. In some cases, so-called corner firing. This combustion method is excellent in that it effectively uses the corner of the combustion furnace as a combustion space, but the distance between the flame from the burner and the combustion furnace wall is much closer than the opposed combustion method, so the flame Another contrivance was needed to solve problems such as corrosion caused by interference with the fuel furnace wall.
An object of the present invention is to promote effective utilization of a combustion space in a combustion furnace and realize suppression of oxygen concentration imbalance in gas and suppression of gas temperature imbalance.

The above object of the present invention is achieved by the following means.
The invention according to claim 1 is a combustion furnace in which a plurality of burner groups are respectively arranged at the same height or substantially the same height position of opposing wall surfaces, and the burner groups are arranged in at least one stage in the direction in which the burner flame flows. The pair of at least one burner at the same height or almost the same height position of the opposing wall surfaces is arranged at a position where the distance formed by the horizontal extension line of the central axis of each burner is shifted on the opposite wall surfaces. It is a combustion furnace.

According to a second aspect of the present invention, the horizontal distance formed by the extension lines of the burner central axes on the opposing wall surfaces is a value between 0.2 and 1.5 times the throat diameter D of the burner. 1. A combustion furnace according to 1.
Invention of Claim 3 is a boiler apparatus which uses the combustion furnace of Claim 1 as a combustion furnace of a steam generator.

  According to the first aspect of the present invention, the extension lines of the central axes of the burners arranged on the same horizontal plane or substantially the same horizontal plane on the front wall and the rear wall of the combustion furnace are slightly displaced from each other in the horizontal direction (this Since the deviation is sometimes referred to as an offset distance), a part of the flame (gas flow) from the burner provided on one furnace wall is part of the flame (from the burner provided on the furnace wall at the opposite position ( Gas flow) but some do not.

  As shown in FIG. 2, the gas flow that does not collide with the opposing wall surface in the flames from the respective burners 12 and 11 provided on the front and rear walls A and B adjacent to the pair of side walls C is between the side wall C and the burner flame. Is used as a combustion space, and the flame close to the side wall C is pushed in the direction of expansion toward the side wall (the direction of the arrow (R) in FIG. 2). There is an effect of reducing the space in the combustion furnace 1 that has not been used effectively.

  According to the invention described in claim 1, since the space in the combustion furnace that has not been used effectively for combustion is reduced, even in a large-capacity combustion furnace, uniform combustion is performed in the combustion furnace, and unburned in the exhaust gas. Combustion is also effective for reducing the amount of carbon and carbon monoxide.

According to the invention described in claim 2, in addition to the effect of the invention described in claim 1, if the offset distance is between 0.2D and 1.5D of the burner throat diameter, the combustion chamber is not used effectively for combustion. It has the effect of reducing the space.
According to invention of Claim 3, the effect of invention of Claim 1 can be used effectively with a boiler apparatus, and steam generation efficiency increases from before.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a horizontal sectional view of a combustion furnace according to an embodiment of the present invention. In this figure, the burner is represented by its central axis. The burner central axis 2 is arranged on the front wall A which is one wall surface of the combustion furnace 1 facing, and the burner central axis 3 is arranged on the rear wall B which is the other wall surface. The horizontal distance L between the extension lines between the burner central axis 2 and the burner central axis 3 is 0.2 to 1.5 times D, where D is the throat diameter of the burner. Is arranged.

  FIG. 2 shows a horizontal cross-sectional view of the combustion furnace at the burner installation portion of the combustion furnace showing the operation of this embodiment. The burner 11 and the burner 12 are disposed on the same horizontal surface or substantially the same horizontal surface of the front and rear walls A and B facing each other in the combustion furnace 1 facing each other. The extension lines of the central axes 2 and 3 are arranged at positions slightly shifted from each other in the horizontal direction. In this case, a part of the flame (gas flow) from the burner 11 or 12 provided on one furnace wall A or B is part of the flame (gas) from the burner 12 or 11 provided on the furnace wall B or A at the opposite position. Flow) but some do not. Such a flame collision mode is referred to as an offset collision here.

  The furnace wall A or B facing in the flame from the burner 11 or 12 provided on the front and rear walls A and B adjacent to the pair of side walls C, which are wall surfaces connecting both ends of the front and rear walls A and B of the combustion furnace 1 The gas flow that does not collide with the gas uses the space between the side wall C and the burner flame as a combustion space. In particular, due to the reaction of the force generated at the time of the offset collision, the flame close to the side wall C is pushed in the direction of the arrow (R) in the figure in the direction in which the side wall swells. There is an effect of reducing the space in the combustion furnace 1 that has not been used effectively for the combustion that has been performed.

  Offset collision by changing the distance L (offset distance L) between the central axes 2 and 3 of the two burners located on the front and rear walls A and B facing each other and located closest to each other between the facing furnace walls For example, the optimum offset distance L can be set to minimize the region (A) as shown in FIG.

  FIG. 5 shows an example of the effect of this embodiment. The horizontal axis represents the offset distance L, and the vertical axis represents the oxygen concentration deviation in the gas. Curve (A) is the oxygen concentration deviation in the gas in region (A) and region (I ') in FIG. 2, and curve (B) is the oxygen concentration in the gas in region (B) and region (B') in FIG. Indicates the deviation. A broken line (c) indicates an oxygen concentration imbalance index. A smaller oxygen concentration imbalance index indicates a smaller oxygen concentration imbalance in the gas and a smaller gas temperature imbalance. The oxygen concentration imbalance index can be obtained from the curves (b) and (b). The oxygen concentration imbalance index is affected by the burner type and capacity, the position of the burner placed in the combustion furnace, and the offset distance is It can be seen that there is an effect of reducing the space in the combustion furnace 1 that is not effectively used for combustion within the burner throat diameter of 0.2D to 1.5D. In addition, the fact that the oxygen concentration imbalance in the gas is eliminated means that uniform combustion is performed in the combustion furnace 1, and according to this embodiment, the amount of unburned carbon generated in the exhaust gas and the generation of carbon monoxide. It is also effective in reducing the amount.

  When the offset distance is small, such as L = 0.2D, the effect of suppressing the oxygen concentration and gas temperature imbalance is small, but the flow direction of the combustion gas shifts with time as shown in FIGS. This has the effect of suppressing the occurrence of unstable gas temperature distribution changes (chattering phenomenon) due to the occurrence of combustion gas, so even if gas temperature imbalance occurs, the distribution is fixed in one pattern. Therefore, hardware measures such as adjustment of the burner register opening and adjustment on the water and steam paths are effective.

  Between the burners 11 and 12 (FIG. 2) disposed on the front and rear walls A and B facing each other in the combustion furnace 1, the burners disposed at the same height position or substantially the same height position of the front and rear walls A and B facing each other. When the set of 11 and 12 has only one stage in the vertical direction, the present embodiment is applied to the one-stage burner.

  As shown in an example in FIG. 3, when a set of burners 11 and 12 arranged at the same height position of the front and rear walls A and B facing each other has a plurality of stages in the vertical direction on each furnace wall A and B, The present embodiment is preferably applied to the burners 11 and 12 in all stages. However, when this embodiment can be applied to only one specific stage due to restrictions on the boiler structure or burner arrangement, it is more effective to apply this embodiment to the upper burner stage. When this embodiment is applied to a set of upper burners, not only the effect of reducing the oxygen concentration unbalance index of only the set of upper burners 11 and 12 but also the lower burners 11 and 12 is set. This is because the region having a high oxygen concentration in the gas generated in the above set can be reduced in the set of burners 11 and 12 on the upper stage side.

FIG. 4 shows another embodiment of the present invention. In this embodiment, the offset arrangement positions of the burners arranged on the opposed front wall A and the burner arranged on the rear wall B are regularly arranged in the same direction in all the burners. There is no need. Further, the offset distance L itself between the extension lines of the burner central axes 2 and 3 arranged on the front and rear walls A and B need not be the same.
Although not shown in the drawings, it is effective to selectively carry out only the burner arranged at the position of the front and rear walls closest to the side wall.

  As a burner arrangement structure that can cope with an increase in the capacity of the burner and the combustion furnace, it can be used as a combustion furnace such as boiler equipment.

It is a top view which shows burner arrangement | positioning in the combustion furnace used as this invention. It is a horizontal sectional view of the burner installation part of the combustion furnace which shows the effect | action in the combustion furnace of FIG. It is a side view which shows the opposing combustion burner arrangement | positioning in the combustion furnace used as this invention. It is a top view which shows the opposing combustion burner arrangement | positioning in the combustion furnace used as this invention. It is a figure explaining the effect of arrangement | positioning of the opposing combustion burner in the combustion furnace used as this invention. It is a top view which shows arrangement | positioning of the opposing combustion burner in the conventional combustion furnace. It is a top view which shows staggered arrangement | positioning of the opposing combustion burner in the conventional combustion furnace. It is a top view which shows the gas flow by the burner capacity increase in the conventional combustion furnace. It is a top view of the combustion furnace which shows another pattern of FIG. A side view (FIG. 10 (a)) showing that the distribution in the conventional combustion furnace affects the rear heat transfer section, a plan view of the combustion furnace (FIG. 10 (b)), and a plan view of the rear heat transfer section ( FIG. 10 (c)).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion furnace 2,3 Burner center axis | shaft 4,5 Burner 6,7 Gas flow 8,9 Heat transfer part 10 Dividing wall 11,12 Burner A Front wall B Rear wall C Side wall

Claims (3)

In a combustion furnace in which a plurality of sets of burners are arranged at the same height or almost the same height position of opposing wall surfaces, and the set of burners is arranged in at least one stage in the direction in which the burner flame flows.
The pair of at least one burner at the same height or almost the same height position of the opposing wall surfaces is arranged at a position where the distance formed by the horizontal extension line of the central axis of each burner is shifted on the opposite wall surfaces. A combustion furnace characterized by having   The said horizontal distance which the extension line of the mutual burner center axis | shaft in an opposing wall surface makes is a value between 0.2 to 1.5 times the throat diameter D of a burner. Combustion furnace.   A boiler apparatus using the combustion furnace according to claim 1 as a combustion furnace of a steam generator.

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