Patent Description:
A gas combustion apparatus refers to an apparatus for burning a supplied fuel gas to generate heat. When the fuel gas is burned in the combustion apparatus, NOx (nitrogen oxide) is generated. NOx not only causes acid rain, but also irritates eyes and a respiratory organ and kills plants. Therefore, NOx is regulated as a main air pollutant. When a fuel gas with a relatively low fuel ratio (hereinafter, referred to as a lean gas) is used in the combustion apparatus, emission of NOx may be reduced. However, when the lean gas is used, the burning velocity is reduced so that the combustion stability is weakened, and emission of carbon monoxide (CO) is increased.

Accordingly, a lean-rich burner for reducing emission of NOx and enhancing combustion stability has been developed. The lean-rich burner refers to a burner configured such that a rich flame is located in an appropriate position around a lean flame. The rich flame refers to a flame generated when a fuel gas with a relatively high fuel ratio (hereinafter, referred to as a rich gas) is burned. In the lean-rich burner, a tertiary flame is formed while unburned fuel of the rich flame reacts with excess air of the lean flame, and therefore the combustion stability of the lean flame may be enhanced. This effect is called a flame stabilizing effect.

However, due to recent strict NOx regulation standards, it is difficult to satisfy the NOx regulation standards even through the lean-rich burner. When the fuel ratio of the rich gas in the lean-rich burner is decreased, emission of NOx may be reduced. However, in this case, the combustion stability of the rich flame is weakened.

Accordingly, to decrease the fuel ratio of the rich gas in the lean-rich burner to reduce emission of NOx and achieve a strong flame stabilizing effect, a combustion apparatus having a modified structure of a flame hole through which a lean gas and a rich gas are released has been developed in recent years.

<FIG> is a schematic plan view illustrating flame hole structures of conventional lean-rich burners. In <FIG>, slant lines represent flames. As illustrated in <FIG>, the conventional flame hole structures include, around a lean flame hole <NUM> for releasing a lean gas, rich flame holes <NUM> for releasing a rich gas. Further, a binding plate <NUM> for binding the lean flame hole <NUM> and the rich flame holes <NUM>. Alternatively, as illustrated in <FIG>, the conventional flame hole structures include a lean flame hole <NUM> for releasing a lean gas and rich flame holes <NUM> and <NUM> disposed to surround the periphery of the lean flame hole <NUM>.

However, according to the flame hole structures illustrated in <FIG>, a lifting phenomenon occurs in the flames generated in regions A and B so that the flames are unstable and therefore a flame stabilizing effect is deteriorated. Here, the lifting phenomenon refers to a phenomenon in which the release velocity of a fuel gas is higher than the burning velocity of the fuel gas so that a flame rises off from a flame hole. The flames in which the lifting occurs are unstable and are easily extinguished, or a large amount of carbon monoxide is generated.

The present invention has been made to solve the above-mentioned problems. An aspect of the present invention provides a flame hole structure for a combustion apparatus for allowing a flame to be uniformly generated in substantially all regions of a flame hole, thereby reducing emission of NOx and enhancing a flame stabilizing effect. Similar flame hole structures which have rich flame hole and lean flame hole according to the preamble of claim <NUM> can be found in <CIT>, <CIT> and <CIT>.

According to the invention, a flame hole structure for a combustion apparatus having a plurality of flame holes for forming a flame includes a lean flame hole part having at least one lean flame hole extending along a lengthwise direction that is a direction perpendicular to a release direction of a lean gas, as a flame hole to release the lean gas and a rich flame hole part having a pair of rich flame holes provided on opposite sides of the lean flame hole part with respect to a width direction that is a direction perpendicular to the release direction and the lengthwise direction, the pair of rich flame holes extending along a direction parallel to the lengthwise direction, as flame holes to release a rich gas. The lean flame hole includes at least one bent lean flame hole portion bent toward the center of the lean flame hole part along the width direction and horizontal lean flame hole portions provided on opposite sides of the bent lean flame hole portion with respect to the direction parallel to the lengthwise direction and extending along the direction parallel to the lengthwise direction. The rich flame hole includes at least one protruding rich flame hole portion protruding toward the bent lean flame hole portion to correspond to the bent lean flame hole portion and horizontal rich flame hole portions provided on opposite sides of the protruding rich flame hole portion with respect to the direction parallel to the lengthwise direction and extending along the direction parallel to the lengthwise direction to correspond to the horizontal lean flame hole portions. In a region extending from at least any one horizontal rich flame hole portion to another horizontal rich flame hole portion through the adjacent protruding rich flame hole portion, the rich flame hole part is provided to be spaced apart from the lean flame hole part by substantially the same interval.

When the combustion apparatus including the flame hole structure according to the present invention is used, a stable flame may be maintained in substantially all regions of each flame hole, and thus a uniform flame stabilizing effect may be achieved, with a reduction in NOx.

Hereinafter, some embodiments of the present invention will be described in detail with reference to the exemplary drawings. In adding the reference numerals to the components of each drawing, it should be noted that the identical or equivalent component is designated by the identical numeral even when they are displayed on other drawings. Further, in describing the embodiment of the present invention, a detailed description of well-known features or functions will be ruled out in order not to unnecessarily obscure the gist of the present invention.

Through repeated experiments and studies for solving the above-mentioned problems, the inventors of the present invention have found the cause of the lifting phenomenon in the regions A and B of <FIG>. There may be many causes, and one of them is that part of heat generated when a fuel gas is burned is transferred to the outside so that the burning velocity is reduced. More specific description will be given with reference to <FIG>.

<FIG> is a schematic view illustrating a section of a flame hole structure to describe a lifting phenomenon. As illustrated in <FIG>, for example, when a rich gas is released through a rich flame hole <NUM>, a rich flame F is generated around a flame hole wall <NUM> that forms the rich flame hole <NUM>. At this time, when the amount of heat q transferred to the flame hole wall <NUM> increases, the release velocity of the rich gas becomes higher than the burning velocity of the rich gas as the burning velocity decreases. Therefore, a problem may arise in which the rich flame F rises off the rich flame hole <NUM> and is immediately extinguished.

Accordingly, in the case of the region A in <FIG>, a lifting phenomenon is more likely to occur than in the other region because heat is able to be transferred to the binding plate <NUM> placed at the upper ends as well as the flame hole wall that forms the flame hole. Therefore, a problem may arise in which when a fuel gas is released under the same condition, no flame is generated only in the region A and a flame stabilizing effect is weakened in the region A.

Furthermore, even in the case of the region B in <FIG>, in the portion where the rich flame hole <NUM> and the rich flame hole <NUM> are disconnected from each other, the amount of heat transferred to the flame hole wall per unit heating value of the rich gas is relatively larger than in the other region, and therefore a problem may arise in which a lifting phenomenon easily occurs in the region B.

Accordingly, to solve the problems, the inventors of the present invention have derived the following flame hole structures of the combustion apparatus.

<FIG> is a plan view illustrating a flame hole structure according to embodiment <NUM> of the present invention. <FIG> is an enlarged view illustrating a region T1 in a rich flame hole of <FIG>. <FIG> is a plan view illustrating the flame hole structure according to embodiment <NUM> of the present invention in another aspect. <FIG> is an enlarged view illustrating a region T2 of <FIG>. Hereinafter, a flame hole structure of a combustion apparatus including a plurality of flame holes for forming a flame according to embodiment <NUM> of the present invention will be described with reference to <FIG>.

The flame hole structure according to embodiment <NUM> of the present invention includes a lean flame hole part <NUM> and a rich flame hole part <NUM>.

The lean flame hole part <NUM> includes at least one lean flame hole <NUM> for releasing a lean gas. The lean flame hole <NUM> extends along a lengthwise direction x that is a direction perpendicular to a release direction z of the lean gas.

The rich flame hole part <NUM> includes a pair of rich flame holes <NUM> for releasing a rich gas. The rich flame holes <NUM> extend along a direction parallel to the lengthwise direction x. At this time, the pair of rich flame holes <NUM> are provided on opposite sides of the lean flame hole part <NUM> with respect to a width direction y that is a direction perpendicular to the release direction z and the lengthwise direction x.

The lean gas released from the lean flame hole <NUM> is burned to form a lean flame, and the rich gas released from the rich flame holes <NUM> is burned to form a rich flame. Further, a flame stabilizing effect may occur while the lean flame and the rich flame exchange heat with each other.

At this time, the rich flame holes <NUM> are designed such that the flame stabilizing effect between the lean flame and the rich flame effectively occurs.

For example, each of the rich flame holes <NUM> includes, between any reference regions having the same size, a region designed such that when the rich flame by the rich gas is generated in the rich flame hole <NUM>, the sum of the amounts of heat transferred to a pair of rich flame hole walls that form each reference region is substantially the same. Alternatively, between any reference regions having the same size, the rich flame hole <NUM> may be designed such that when a flame by the rich gas is generated, the burning velocity of the rich gas in each reference region is substantially the same.

More specific description will be given with reference to <FIG>. First, a reference region S refers to a region defined at an upper end of the rich flame hole <NUM> by a first line I, a second line II, and a pair of rich flame hole walls b. The first and second lines I and II are any virtual lines across the rich flame hole <NUM>, and the rich flame hole walls b refer to walls that are spaced apart from each other along the width direction y and that form a portion of the rich flame hole <NUM> between the first and second lines I and II.

As illustrated in <FIG>, any reference regions may be defined in the rich flame hole <NUM>. For example, the reference region S defined by the first line I, the second line II, and the pair of flame hole walls b and a reference region S' defined by a first line I', a second line II', and a pair of flame hole walls b' may be defined.

When the sizes of the reference region S and the reference region S' are the same, the rich flame hole <NUM> includes, between the reference regions, a region designed such that the sum of the amounts of heat transferred to the pair of rich flame hole walls b or b', that is, the burning velocity of the rich gas in each reference region is substantially the same. In other words, when the sizes of the reference region S and the reference region S' are the same, the rich flame hole <NUM> includes a region designed such that when a flame by the rich gas is generated, the sum Q of the amounts of heat transferred to the pair of rich flame hole walls b in the reference region S and the sum Q' of the amounts of heat transferred to the pair of rich flame hole walls b' in the reference region S' are substantially the same.

In the reference regions S and S' having the same size, the same amount of rich gas will be released at substantially the same release velocity, and substantially the same amount of heat will be generated when the rich gas is burned. Further, when the amounts of heat transferred from the reference regions S and S' to the flame hole walls b and b' are substantially the same, the burning velocities of the rich gas in the reference regions S and S' will also be substantially the same, and therefore limit conditions in which lifting occurs in the reference regions S and S' will be the same. Accordingly, when the rich gas is supplied to the reference regions S and S' in an optimal condition capable of reducing emission of NOx, rich flames having substantially the same property will be generated in the reference regions S and S'.

Thus, unlike in the regions A and B of <FIG>, substantially the same flame stabilizing effect may be obtained in the entirety of the region designed as described above. Accordingly, the flame hole structure according to embodiment <NUM> of the present invention may reduce emission of NOx and may enhance the stability of burning, thereby achieving a uniform flame stabilizing effect. Further, the entire region of the rich flame hole is more preferably designed in this way.

Meanwhile, "substantially the same" does not mean "numerically exactly the same", but means the sameness to a degree that substantially the same action is caused in this technical field even though there is a slight numerical difference.

At this time, there may be various means for adjusting the amounts of heat transferred to the flame hole walls that form each reference region.

For example, when the material and thickness of a pair of rich flame hole walls are constant, the rich flame hole <NUM> may be designed, between any reference regions having the same size, such that the sum of the lengths of upper ends of the pair of rich flame hole walls that form each reference region is substantially the same. That is, in <FIG>, the rich flame hole <NUM> may be designed such that the sum of the lengths of the pair of flame hole walls b that form the reference region S and the sum of the lengths of the pair of flame hole walls b' that form the reference region S' are substantially the same. When the sums of the lengths are the same, it may be considered that the areas of the flame hole walls to which heat is transferred are the same.

When the difference between the sum of the lengths of the upper ends of the pair of flame hole walls b that form the reference region S and the sum of the lengths of the upper ends of the pair of flame hole walls b' that form the reference region S' is within an error range of about <NUM>%, the sum of the lengths of the upper ends of the pair of rich flame hole walls that form each reference region may be considered to be substantially the same. The lengths of rich flame hole walls actually manufactured may have a tolerance with design lengths, and even though there is a difference in the sum of the lengths of the upper ends of the pair of rich flame hole walls that form each reference region, the sum of the lengths of the upper ends of the pair of rich flame hole walls that form each reference region may be considered to be substantially the same within the tolerance range that occurs during manufacturing.

Accordingly, it may be considered that in each reference region, the limit condition in which lifting occurs is substantially the same and an equivalent flame stabilizing effect appears. Meanwhile, the numerical value of <NUM>% does not have a special meaning and is an example for representing a range of a tolerance level that occurs during manufacturing.

In another example, even though the distances between the pair of flame hole walls that form the reference regions differ from each other or there is a difference in other properties of the flame hole walls, the thickness and material of the flame hole walls may be adjusted such that the amounts of heat transferred to the flame hole walls are the same.

In another example, when a physical object, such as a binding plate, which is capable of receiving heat exists around a rich flame hole as illustrated in <FIG>, the rich flame hole may be designed, between any reference regions having the same size, such that the sum of the amounts of heat transferred to a physical boundary that includes a pair of flame hole walls and defines each reference region is substantially the same.

Referring again to <FIG>, the lean flame hole <NUM> may include at least one bent lean flame hole portion <NUM> and horizontal lean flame hole portions <NUM>. The bent lean flame hole portion <NUM> refers to a portion that is bent toward the center of the lean flame hole part <NUM> along the width direction y. The horizontal lean flame hole portions <NUM> refer to portions that are provided on opposite sides of the bent lean flame hole portion <NUM> with respect to the direction parallel to the lengthwise direction x and that extend along the direction parallel to the lengthwise direction x.

Furthermore, the rich flame hole <NUM> may include at least one protruding rich flame hole portion <NUM> and horizontal rich flame hole portions <NUM>. The protruding rich flame hole portion <NUM> refers to a portion that protrudes toward the bent lean flame hole portion <NUM> to correspond to the bent lean flame hole portion <NUM>. Further, the horizontal rich flame hole portions <NUM> refer to portions that are provided on opposite sides of the protruding rich flame hole portion <NUM> with respect to the direction parallel to the lengthwise direction x and that extend along the direction parallel to the lengthwise direction x to correspond to the horizontal lean flame hole portions <NUM>.

As described above, the rich flame hole <NUM> includes the protruding rich flame hole portion <NUM> corresponding to the bent lean flame hole portion <NUM>, thereby allowing the rich flame to be formed in a form surrounding the periphery of the lean flame, and an effect of increasing the area in which a flame stabilizing effect occurs may occur.

At this time, the rich flame hole <NUM> may include a communication region that is a region formed to extend from any one horizontal rich flame hole portion <NUM> to another horizontal rich flame hole portion <NUM> through the adjacent protruding rich flame hole portion <NUM>. At this time, in the entire communication region, the rich flame hole <NUM> may be designed, between the reference regions having the same size, such that the sum of the amounts of heat transferred to the pair of rich flame hole walls that form each reference region is substantially the same.

As illustrated in <FIG>, a lifting phenomenon is likely to occur in the portion where the rich flame hole parts <NUM> and <NUM> are disconnected from each other, whereas in the entire communication region of the present invention, the limit at which a lifting phenomenon occurs may be substantially the same, and therefore a flame stabilizing effect may be allowed to uniformly appear in a wide region. Furthermore, the rich flame hole <NUM> is more preferably designed to have a communication region in all the regions where the bent lean flame hole portion <NUM> and the protruding rich flame hole portion <NUM> are provided.

Meanwhile, the flame hole structure according to embodiment <NUM> of the present invention may further include a partitioning part <NUM>. The partitioning part <NUM> refers to a part that is provided between the lean flame hole part <NUM> and the rich flame hole part <NUM> and through which the lean gas and the rich gas are not released. The partitioning part <NUM> may be designed such that the lean flame and the rich flame are formed with an appropriate interval therebetween and a flame stabilizing effect most effectively appears.

At this time, referring to <FIG> and <FIG>, the lean flame hole part <NUM> may further include a plurality of lean plates <NUM> for forming the lean flame holes <NUM>, and the rich flame hole part <NUM> may further include a plurality of rich plates <NUM> for forming the rich flame holes <NUM>.

The plurality of lean/rich plates <NUM> and <NUM> may be disposed to be spaced apart from each other at a predetermined interval while facing each other along the width direction y. Further, the lean/rich flame holes <NUM> and <NUM> may be formed in spacing spaces between the lean/rich plates <NUM> and <NUM>. Furthermore, the partitioning part <NUM> may be formed between a first lean plate 13a located at the outermost position with respect to the width direction y among the plurality of lean plates <NUM> and a first rich plate 23a located at the innermost position with respect to the width direction y among the plurality of rich plates <NUM>.

At this time, the plurality of lean plates <NUM> may be bent at different angles to form the bent lean flame hole portions <NUM>. Further, the plurality of rich plates <NUM> may also form the protruding rich flame hole portions <NUM>.

At this time, the first lean plate 13a may include at least one first bent lean plate portion 133a and first horizontal lean plate portions 131a provided on opposite sides of the first bent lean plate portion 133a. The first bent lean plate portion 133a refers to a portion that is bent toward the center of the lean flame hole part <NUM> along the width direction y, and the first horizontal lean plate portions 131a refer to portions that extend along the direction parallel to the lengthwise direction x from the opposite sides of the first bent lean plate portion 133a with respect to the direction parallel to the lengthwise direction x.

Furthermore, the first rich plate 23a may include a first protruding rich plate portion 233a corresponding to the first bent lean plate portion 133a and first horizontal rich plate portions 231a corresponding to the first horizontal lean plate portions 131a. The first protruding rich plate portion 233a protrudes toward the first bent lean plate portion 133a, and the first horizontal rich plate portions 231a extend from opposite sides of the first protruding rich plate portion 233a along the direction parallel to the lengthwise direction x. Further, the second rich plate 23b may include a second protruding rich plate portion 233b and first horizontal rich plate portions 231b.

At this time, as illustrated in <FIG>, the flame hole structure according to embodiment <NUM> of the present invention may be designed such that the length of a vertical line I<NUM> drawn from any point of at least one first bent lean plate portion 133a toward the first protruding rich plate portion 233a corresponding thereto is substantially the same as the lengths of vertical lines I<NUM> and I<NUM> drawn from any points of the adjacent first horizontal lean plate portion 131a toward the first horizontal rich plate portion <NUM> corresponding thereto.

That is, the rich flame hole part <NUM> may be provided to be spaced apart from the lean flame hole part <NUM> at substantially the same interval in a region extending from at least one horizontal rich flame hole portion <NUM> to another horizontal rich flame hole portion <NUM> through the adjacent protruding rich flame hole portion <NUM> (refer to <FIG>).

At this time, the same interval does not mean numerically exact sameness. For example, even though the rich flame hole part <NUM> and the lean flame hole part <NUM> are designed to be spaced apart from each other by a distance L, when the actual interval is within an error range of about ± <NUM>% of the distance L, the rich flame hole part <NUM> and the lean flame hole part <NUM> may be considered to be spaced apart from each other by substantially the same interval.

Because the distance between the rich flame hole part and the lean flame hole part in an actual burner structure is very small at the level of <NUM> unit, considering a tolerance generated during manufacturing, it may be considered that the limit condition in which lifting occurs is substantially the same within the error range of about ± <NUM>% and an equivalent flame stabilizing effect appears.

For example, when the distance between the actual rich flame hole part and the actual lean flame hole part is within a range of about <NUM> to about <NUM>, the distance may be considered to be substantially the same. At this time, ± <NUM>% or <NUM> to <NUM> does not have a special meaning as a numerical value itself and is only disclosed as an example for representing a range of substantially the same level, when a manufacturing tolerance is considered.

Accordingly, the interval between the lean flame and the rich flame generated from the bent lean flame hole portion <NUM> and the protruding rich flame hole portion <NUM> may be designed to be substantially the same as the interval between the lean flame and the rich flame generated from the horizontal lean flame hole portions <NUM> and the horizontal rich flame hole portions <NUM>. In the entirety of the region designed in this way, an equivalent flame stabilizing effect may appear because the lean flame and the rich flame are separated from each other by the same interval in the entire region.

Accordingly, for all of the bent lean flame hole portion <NUM> and the protruding rich flame hole portion <NUM>, the length of a vertical line drawn from any point of the first bent lean plate portion 133a toward the first protruding rich plate portion 233a corresponding thereto is more preferably designed to be substantially the same as the length of a vertical line drawn from any point of the adjacent first horizontal lean plate portion 131a toward the first horizontal rich plate portion 231a corresponding thereto. Here, when the lengths of the vertical lines or the intervals between the flames are substantially the same, numerically exact sameness is not required.

<FIG> is a plan view illustrating a flame hole structure according to embodiment <NUM> of the present invention. <FIG> is an enlarged view illustrating a region T3 of <FIG>. Hereinafter, the flame hole structure according to embodiment <NUM> of the present invention will be described with reference to <FIG> and <FIG>. In the flame hole structure according to embodiment <NUM>, components identical to those in embodiment <NUM> will be described using identical reference numerals.

The flame hole structure according to embodiment <NUM> of the present invention includes a lean flame hole part <NUM> and a rich flame hole part <NUM>, like the flame hole structure according to embodiment <NUM>. The lean flame hole part <NUM> includes lean flame holes <NUM> formed by a plurality of lean plates <NUM> and rich flame holes <NUM> formed by first and second rich plates 23a and 23b.

Furthermore, the plurality of lean plates <NUM> include a bent lean plate portion <NUM> and a horizontal lean plate portion <NUM>, and the first and second rich plates 23a and 23b also include first and second protruding rich plate portions 233a and 233b corresponding to the bent lean plate portion <NUM> and first and second horizontal rich plate portions 231a and 231b corresponding to the horizontal lean plate portion <NUM>.

However, the flame hole structure according to embodiment <NUM> differs from the flame hole structure according to embodiment <NUM> in terms of the design structure of the rich flame holes <NUM>. More specifically, as illustrated in <FIG>, the flame hole structure according to embodiment <NUM> of the present invention is designed such that the lengths of vertical lines m<NUM> and m<NUM> drawn from any points of at least one first horizontal rich plate portion 231a toward the second horizontal rich plate portion 231b are substantially the same as the length of a vertical line m<NUM> drawn from any point of the adjacent first protruding rich plate portion 233a toward the second protruding rich plate portion 233b.

When the rich flame holes <NUM> are designed in this way, it may be considered that in the region where the lengths of the vertical lines m<NUM>, m<NUM>, and m<NUM> identically extend in <FIG>, as in embodiment <NUM> of the present invention, the amounts of heat transferred to flame hole walls are substantially the same between any reference regions having the same size. In other words, it may be considered that in all regions extending in a straight line shape in the rich flame holes <NUM>, that is, in all regions other than bending regions such as the portions extending from the horizontal rich plate portions 231a and 231b to the protruding rich plate portions 233a and 233b, the amounts of heat transferred to flame hole walls between any reference regions are substantially the same.

Further, between any reference region defined in the region extending in a straight line shape and any reference region defined in the bending region, the amounts of heat transferred to flame hole walls may not be substantially the same when the sizes of the reference regions are the same. However, when the rich flame holes <NUM> are designed as in embodiment <NUM> of the present invention, the difference between the amounts of heat may be insignificant, and a flame stabilizing effect may be considered to substantially identically occur in the entirety of the rich region <NUM> designed as in embodiment <NUM> of the present invention.

<FIG> is a plan view illustrating a flame hole structure according to embodiment <NUM> of the present invention. <FIG> is a plan view illustrating the flame hole structure according to embodiment <NUM> of the present invention. <FIG> is a schematic view illustrating a section taken along line C-C in <FIG>. Hereinafter, the flame hole structure according to embodiment <NUM> of the present invention will be described with reference to <FIG>. In the flame hole structure according to embodiment <NUM>, components identical to those in embodiments <NUM> and <NUM> will be described using identical reference numerals, and unnecessary description will be omitted.

The flame hole structure according to embodiment <NUM> of the present invention may further include a binding member <NUM> in the flame hole structures according to embodiments <NUM> and <NUM>. The binding member <NUM> refers to a member that passes through a rich flame hole part <NUM> and a lean flame hole part <NUM> along the width direction y and binds the lean flame hole part <NUM> and the rich flame hole part <NUM> together. As the binding member <NUM> is provided, lean flame holes <NUM> and rich flame holes <NUM> may be prevented from being changed in size (widened) when flames are generated in the lean flame holes <NUM> and the rich flame holes <NUM>.

At this time, the binding member <NUM> may be provided at a position spaced apart downward from upper ends of the lean flame hole part <NUM> and the rich flame hole part <NUM> at a predetermined interval (refer to <FIG>). As illustrated in <FIG>, in the related art, the binding plate is provided at the upper end of the flame hole, and a flame cannot be generated in the portion where the plate is provided, so that a flame stabilizing effect cannot appear. However, because the binding member <NUM> according to embodiment <NUM> of the present invention is provided at the position spaced apart downward from the upper ends of the flame hole parts at the predetermined interval with respect to a direction parallel to the release direction z, the binding member <NUM> may not hinder generation of a flame.

At this time, the interval at which the binding member <NUM> is spaced apart from the upper ends is not specially limited, and the binding member <NUM> is preferably spaced to a position where the binding member <NUM> does not hinder generation of a flame and is capable of most effectively preventing the lean flame holes <NUM> and the rich flame holes <NUM> from being changed in size.

Furthermore, the type and the binding method of the binding member <NUM> are also not specially limited, and as illustrated in <FIG>, a method of inserting the binding rod <NUM> from one side along the width direction y and thereafter binding an opposite side using welding or plastic deformation may be used. Alternatively, as illustrated in <FIG>, a method of allowing a binding wire <NUM>' to pass through and thereafter binding opposite distal ends (portions represented by a dotted circle) through welding, knot, plastic deformation, or the like may be used.

Claim 1:
A flame hole structure for a combustion apparatus having a plurality of flame holes for forming a flame, the flame hole structure comprising:
a lean flame hole part (<NUM>) having at least one lean flame hole (<NUM>) extending along a lengthwise direction that is a direction perpendicular to a release direction of a lean gas, as a flame hole to release the lean gas; and
a rich flame hole part (<NUM>) having a pair of rich flame holes (<NUM>) provided on opposite sides of the lean flame hole part (<NUM>) with respect to a width direction that is a direction perpendicular to the release direction and the lengthwise direction, the pair of rich flame holes (<NUM>) extending along a direction parallel to the lengthwise direction, as flame holes to release a rich gas,
wherein the lean flame hole (<NUM>) includes at least one bent lean flame hole portion (<NUM>) bent toward the center of the lean flame hole part (<NUM>) along the width direction and horizontal lean flame hole portions (<NUM>) provided on opposite sides of the bent lean flame hole portion (<NUM>) with respect to the direction parallel to the lengthwise direction and extending along the direction parallel to the lengthwise direction,
characterized in that the rich flame hole (<NUM>) includes at least one protruding rich flame hole portion (<NUM>) protruding toward the bent lean flame hole portion (<NUM>) to correspond to the bent lean flame hole portion (<NUM>) and horizontal rich flame hole portions (<NUM>) provided on opposite sides of the protruding rich flame hole portion with respect to the direction parallel to the lengthwise direction and extending along the direction parallel to the lengthwise direction to correspond to the horizontal lean flame hole portions (<NUM>), and
wherein in a region extending from at least any one horizontal rich flame hole portion (<NUM>) to another horizontal rich flame hole portion (<NUM>) through the adjacent protruding rich flame hole portion (<NUM>), the rich flame hole part (<NUM>) is provided to be spaced apart from the lean flame hole part (<NUM>) by substantially the same interval.