HK1120594B - Combustion apparatus - Google Patents

Description

Combustion apparatus

Technical Field

The present invention relates to a combustion device, and more particularly to a combustion device recommended for use in a water heater or a bath device (bath heater).

Background

The combustion apparatus is a main component of a water heater or a bathing apparatus, and is widely used in homes and factories.

In recent years, environmental destruction caused by acid rain has become a serious social problem, and therefore, reduction of NO has been achieved_XThe total emission of (nitrogen oxides) is an urgent necessity.

A combustion apparatus using a combustion method called a rich-lean combustion method is applied to a small-sized device such as a water heater and can reduce NO_XThe amount of discharge of (c).

The rich-lean combustion method is a method in which a main flame is generated from a lean mixture gas obtained by premixing air, which is about 1.6 times the theoretical air amount, with fuel gas, and an auxiliary flame generated from a rich mixture gas, which has a small air mixture amount and a high fuel gas concentration, is arranged near the main flame.

Combustion apparatuses based on rich-lean combustion are known, for example, as disclosed in patent documents 1 and 2.

In addition, in NO_XThere is also a combustion form called a two-stage combustion method as the combustion method with a small amount of generation of (2). The two-stage combustion method is a combustion method in which fuel gas is injected and ignited to generate a primary flame in a state where oxygen is insufficient, and secondary air is supplied to unburned gas to generate a secondary flame.

Patent document 3 discloses a combustion apparatus using such a two-stage combustion method.

[ patent document 1] JP5-118516A

[ patent document 2] JP6-126788A

[ patent document 3] JP52-143524A

Disclosure of Invention

Although the combustion apparatus NO of the thick-thin combustion method is adopted_XThe amount of produced is small and is well appreciated in the market, but there is a disadvantage that the turndown Ratio (t.d.r) is small. In particular, a combustion apparatus using the rich-lean combustion method has a disadvantage that it is difficult to burn in a region where the amount of heat generation is small.

Specifically, in the rich-lean combustion method, as described above, the main flame is generated from a lean mixture gas in which air of about 1.6 times the theoretical air amount is premixed with the fuel gas. Since the mixture is lean, the combustion speed is slow.

In order to promote the formation of a lean mixture, a combustion apparatus using the rich-lean combustion method is provided with a blower, but the blower deteriorates with age due to the use of the blower over the years, and the amount of air supplied gradually decreases. In addition, if the filter of the blower is clogged, the amount of air supplied may be reduced. The decrease in the amount of air blown due to aging tends to decrease the amount of air mixed to generate the main flame, and the amount of air mixed tends to approach the theoretical amount of air. As a result, the combustion speed of the main flame is excessively fast due to aging. Therefore, the base end portion of the flame tends to gradually approach the flame hole (burner port) due to aging. Therefore, combustion in a region where the amount of heat generation is small brings the base end portion of the flame close to the flame hole, and the flame hole is damaged. Therefore, in view of the expected deterioration, the combustion apparatus using the rich-lean combustion method has to restrict combustion in a region where the amount of heat generation is small.

In addition, the rich-lean combustion method causes complaints about a narrow range of usable gases. Specifically, although the fuel gas supplied from a gas company may be composed of only a single component, a plurality of components are mixed together in many cases. Therefore, even if the amount of heat generated (amount of heat per unit volume) is the same, the combustion speed differs among gas companies.

In the rich-lean combustion method, a main flame is generated in a state where air is excessive, and a fuel gas having a slow combustion speed causes a spark-over (blow off), resulting in unstable combustion.

In contrast, the two-stage combustion method can have a higher turn-down ratio than the rich-lean combustion method. Further, the types of fuel gas that can be used are wide. However, the two-stage combustion method is unstable because the fuel gas is combusted in a state of oxygen deficiency. Therefore, it has not been found that the two-stage combustion method is adopted in actual apparatuses such as water heaters on the market.

In order to be put into practical use as a combustion device, it is necessary to generate a flame that is uniformly distributed over a certain area. This can be achieved by generating the primary and secondary flames in a balanced manner and uniformly distributed over the entire area of the combustion site.

However, it is very difficult to generate the primary flame and the secondary flame in a balanced manner and to uniformly distribute the flame over the entire area of the combustion site. For example, a primary flame may be partially extinguished, resulting in an oversized secondary flame downstream thereof, or all of the fuel may burn out somewhere producing a primary flame, resulting in an extinguished secondary flame downstream thereof. Therefore, no two-stage combustion method has been found for equipment such as a commercial water heater.

Therefore, in view of the above-mentioned technical problems and disadvantages, it is an object of the present invention to improve a combustion apparatus employing two-stage combustion and to develop a combustion apparatus which generates primary and secondary flames in a balanced manner and uniformly distributes the flames throughout the entire region of a combustion site.

Means for solving the problems

To solve the above problems and disadvantages, an aspect of the present invention herein is to provide a combustion apparatus comprising: at least one premixer in which fuel gas and air are premixed, the premixer having an opening row portion in which openings are arranged in a row; at least one air flow path member in the shape of a wall having at least one distal air discharge opening at a distal end thereof; and at least one flame hole assembly provided between the two air flow path members or between the air flow path member and the other wall, a flame hole upstream flow path being formed between the opening row portion and the flame hole assembly, and a first combustion portion being formed by a space enclosed by the flame hole assembly and the air flow path member, air being supplied to the air flow path member, the flame hole upstream flow path and the premixer, and fuel gas being supplied to the premixer to be premixed with air inside the premixer, the air-fuel gas mixture thus obtained being supplied into the flame hole upstream flow path through the opening of the opening row portion to be further mixed with air and discharged into the first combustion portion through the flame hole assembly in an oxygen-deficient state to be combusted and further combusted based on the supply of air through the distal end air discharge opening of the air flow path member, the air flows in the flow direction in the flame hole upstream flow path, and the openings of the opening row portion are opened in a direction intersecting the flow direction.

One aspect of the present invention has a premixer in which fuel gas and air are premixed. The premixer has an opening row portion in which openings through which the fuel gas is distributed to the flame hole upstream flow path are arranged in a row. The fuel gas also mixes with the air in the flow path upstream of the flame holes. Therefore, according to the configuration of this aspect, the resulting air-fuel gas mixture flowing in the flow path upstream of the flame holes is sufficiently mixed and homogeneous. Thus, a homogenous fuel gas is discharged through all areas of the wall of the flame hole assembly. The primary flame and the secondary flame are generated in a balanced manner and the flame is distributed uniformly over the entire area of the combustion site.

Preferably there is a space adjacent the row of openings in the flow path upstream of the flame ports. This space becomes a mixing space where the fuel gas and the air are mixed. The openings of the opening row are preferably open towards the mixing space.

Further, it is preferred that the mixing space extends substantially over the entire width of the row of openings.

The mixing space extending in this way promotes a homogenization of the pressure.

The fuel gas is discharged through the openings of the opening discharge portion in a direction intersecting the air flow direction, frequently striking the air. This promotes mixing of the fuel gas and air.

Various configurations of flame orifice assemblies are contemplated. For example, a configuration may be adopted in which: the flame hole assembly includes a flame hole forming portion and two side wall portions, and has an opening between the two side wall portions at a portion opposite to the flame hole forming portion, wherein the opening row portion of the premixer is surrounded by the side wall portions, and air is supplied through the opening between the side wall portions.

Still further, it is recommended to have a configuration of: the air flow path member has an air discharge opening toward the first combustion portion for discharging air from the air flow path member toward the first combustion portion. In this case, it is preferable that the flame hole assembly has a plurality of flame hole groups, and the air discharge opening facing the first combustion portion is provided at a position corresponding to a space between the flame hole groups of the flame hole assembly.

The first combustion portion is a portion where the primary flame is generated, and the secondary flame is generated outside the first combustion portion by the air supplied from the distal air discharge opening. The air discharge opening toward the first combustion section is provided to discharge air from the side portion toward between the flame hole groups of the flame hole assembly, so that the air is blown out from the periphery of the flame hole groups, thereby ensuring primary flame stabilization. Further, air is supplied from below the primary flame, so that the secondary flame is generated at an early stage, and complete combustion of the fuel gas is performed near the primary flame. This makes the combustion space compact, thereby shortening the total length of the primary flame and the secondary flame. The base end portion of the secondary flame is also stabilized.

It is recommended that the air flow path member has an inclined surface on which an air discharge opening toward the first combustion portion is formed.

According to this configuration, the air is injected in an oblique direction without obstructing the flow of the main portion of the primary flame or the flow of the fuel gas.

Further, according to this configuration, air is introduced along the flow of the main portion of the primary flame or the flow of the fuel gas without accumulating in the vicinity of the wall of the air flow path member.

Specifically, the fuel gas flows substantially parallel to the wall within the first combustion portion. Therefore, in the case where air is introduced from the air flow path member in a direction perpendicular to the first combustion portion, the air hits the primary flame or the fuel gas, possibly causing accumulation. If air accumulates near the wall of the air flow path member, the accumulated air may cause combustion of surrounding unburned gases and produce a flame near the wall of the air flow path member. The wall may be heated excessively and glowing.

For this reason, the air injected in the oblique direction is introduced along the flow of the primary flame or the flow of the fuel gas, so that the secondary flame is generated at a position distant from the air flow path member. This avoids incandescence of the wall of the air flow path member.

Further, it is also recommended that the air flow path member has an upstream air discharge opening for injecting air, the upstream air discharge opening being located upstream of a portion of the air flow path member defining the first combustion portion, the air injected from the upstream air discharge opening flowing to a side of the flame hole assembly.

According to the above configuration, the air discharged from the upstream air discharge opening flows to the side of the flame hole assembly, thereby supplying oxygen to the side of the flame hole assembly. This causes a stable flame to be generated on the side surface of the flame hole assembly, and the base end portion of the primary flame is held. As a result, the primary flame is stabilized.

Still further, it is also recommended that the flame hole assembly have a central opening and side openings such that fuel gas is discharged from the side openings slower than fuel gas is discharged from the central opening, and that air flow near the side openings of the flame hole assembly.

This arrangement makes the distinction between the flame holes for producing the main part of the primary flame and the flame holes for producing the secondary flame obvious.

Specifically, according to the above configuration, the flow rate of the fuel gas discharged from the side openings is slower than the flow rate of the fuel gas discharged from the central opening, whereby the flames generated at the side openings are hardly extinguished. Further, air is supplied to the vicinity of the side opening, so that the fuel gas discharged from the side opening is relatively stably combusted, and the base end portion of the primary flame is held. As a result, the primary flame is stabilized.

The side openings can be formed in such a way that: the flame hole assembly is constituted by a main body and a pressure reducing wall provided on a side of the main body, a gap having a side opening is defined between the main body and the pressure reducing wall, and the main body has an opening through which a part of the fuel gas flowing in the main body flows into the gap.

According to the above configuration, the fuel gas is introduced from the opening formed on the main body into the gap formed between the side wall and the pressure-reducing wall, but the amount of the fuel gas (more precisely, the fuel gas premixed with air) is restricted by the opening, and therefore the flow rate of the fuel gas discharged from the side opening becomes slower than the flow rate of the fuel gas discharged from other portions.

The openings of the opening row portion may be all slit-shaped.

Further, the opening row portion may have an inclined surface on which the opening is formed. In this case, the opening row portion preferably has an inner angle of 180 or less.

By forming the opening on the inclined surface, the fuel gas is discharged in an oblique direction. This causes the fuel gas to come into contact with the air flow more frequently, promoting mixing of the fuel gas with the air.

Further, it is recommended that the distal end of the air flow path member is a ridge at an acute angle.

An air discharge opening is formed at a distal end of the air flow path member to supply secondary air. According to the above configuration, the distal end of the air flow path member is a sharp-angled ridge, thereby ensuring that less air flows around within the member. This stabilizes the discharge direction of the air.

The invention has the advantages of

The combustion apparatus of the present invention generates primary flame and secondary flame in a balanced manner, and makes the flame uniformly distributed over the entire area of the combustion portion, which is very practical.

Furthermore, the combustion device NO of the invention_XLess emissions and higher turndown ratio. Moreover, the combustion apparatus of the present invention is widely applicable to fuel gas having any combustion speed, and thus to all types of gas.

Drawings

Fig. 1 is a cut-away perspective view conceptually illustrating the configuration of a combustion apparatus of the present invention;

FIG. 2 is a perspective view of a combustion apparatus of a practical embodiment of the present invention;

FIG. 3 is a top view of the combustion apparatus of FIG. 2 housed within a housing;

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

FIG. 5 is a cross-sectional view of the combustion apparatus of FIG. 2;

fig. 6 is a perspective view showing an internal structure of the combustion apparatus which is broken step by step;

FIG. 7 is an exploded perspective view of the combustion apparatus of FIG. 2;

FIG. 8 is an exploded cross-sectional view of the combustion apparatus of FIG. 2;

fig. 9 is a perspective view of a premixer of the combustion apparatus of fig. 2;

FIG. 10 is a cross-sectional view taken along line A-A of FIG. 9;

FIG. 11 is a cross-sectional view taken along line B-B of FIG. 9;

FIG. 12 is a perspective view of an air flow path member of the combustion apparatus of FIG. 2;

fig. 13 is an enlarged view of a concave portion of the air flow path member of fig. 12;

FIG. 14 is a perspective view of a flame hole assembly of the combustion apparatus of FIG. 2;

FIG. 15 is an enlarged front view of a groove (rough) for engagement with the flame hole assembly of FIG. 14;

FIG. 16 is a side view showing a flame port assembly coupled to a premixer;

FIG. 17 is an enlarged view showing the vicinity of the base end portion of the flame hole assembly of FIG. 16;

fig. 18 is a schematic diagram showing a positional relationship between the opening of the premixer and the rib of the air flow path member;

fig. 19 is a schematic view showing a positional relationship between an opening of a premixer and a rib of an air flow path member in another embodiment;

fig. 20 is a schematic view showing the flow of air in the air flow path member of the present embodiment;

fig. 21 is a schematic view showing air flows in an air flow path member of another embodiment;

FIG. 22 is an exploded perspective view of another embodiment of a combustion apparatus;

FIG. 23 is an exploded perspective view of a combustion apparatus of yet another embodiment;

fig. 24 is a partially enlarged plan view showing a positional relationship between the flame hole group of the flame hole assembly and the air discharge opening of the air flow path member toward the combustion section.

Detailed Description

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. First, a schematic configuration and basic functions of the present invention will be described with reference to a schematic diagram of fig. 1. The embodiment in fig. 1 conceptually illustrates the invention.

In the following description, the vertical positional relationship is based on the posture in which the combustion apparatus 1 is vertically placed and flame is generated on the upper side. In addition, the terms "upstream" and "downstream" are based on the flow of air or fuel gas. The "width direction" refers to a lateral direction (a direction of an arrow W in the drawing) when a portion having the largest area of the combustion apparatus is defined as a front surface.

The combustion apparatus 1 of the present embodiment may be used by housing one or more apparatuses in the casing, or may be used alone. The combustion apparatus 1 includes a premixer 2, a flame hole assembly 3, and two air flow path members 5. In the combustion apparatus 1, the premixer 2 and the flame hole assembly 3 are joined to each other to constitute an intermediate member 6, and the intermediate member 6 is sandwiched between the two air flow path members 5. However, in actual use, the plurality of air flow passage members 5 and the plurality of intermediate members 6 are arranged alternately in a planar manner in the order of the air flow passage member 5, the intermediate member 6, and the air flow passage member 5.

The premixer 2, which is a constituent member of the combustion apparatus 1, serves to premix the fuel gas and the air inside thereof. The premixer 2 includes: a mixing section 7 having a curved path and an opening row section 10 provided with openings 8 in a row. The opening row 10 has a longitudinally linearly extending cavity of generally square cross section.

The air flow passage member 5 is a member having a substantially thin wall shape. The air flow path member 5 is constituted by a first surface 11 and a second surface 12 both made of a thin plate, and the first surface 11 and the second surface 12 are connected with a minute gap formed therebetween, and 3 side surfaces other than the bottom surface are bonded to define a cavity serving as an air flow path 13 inside.

Specifically, the first face 11 and the second face 12 are formed by folding a single sheet. The distal end of which has an acute angle bend 14, which bend 14 constitutes the top 9, which extends like a ridge.

The base end of the air flow path member 5 is open between the plates of the first surface 11 and the second surface 12, forming an air inlet 15.

In the air flow path member 5, openings for discharging air are formed in 3 regions. As described above, since the air flow passage members 5 and the intermediate member 6 are alternately arranged in a planar shape, the same number of openings are formed in the same portion of the first surface 11 and the second surface 12 of each air flow passage member 5.

Roughly speaking, openings for air exhaust are formed at the distal end, at a position facing the first combustion portion 46, and at a position facing the intermediate member 6.

Specifically, the first and second surfaces 11 and 12 of the air flow path member 5 are mostly arranged in parallel, and only the distal ends thereof are bent in an angular shape, and inclined surfaces 16 and 17 are formed on the first and second surfaces, respectively. The inclined surfaces 16, 17 each have a distal opening 20. Further, a distal end opening 21 is formed on the tip (ridge line). The distal openings 20, 21 are formed for supplying secondary air to the secondary flame.

As shown in fig. 1, the first surface 11 and the second surface 12 of the air passage member 5 are formed so that the air passage 13 at the distal end is narrower than the air passage 13 at the proximal end, and have a step at a position corresponding to the proximal end of the first combustion portion 46, and the step also constitutes the inclined surface 22. An air discharge opening 23 is formed at each step toward the combustion portion. The air discharge opening 23 is designed to supply secondary air into the primary flame in the first combustion portion 46, to combust a portion of the primary flame, and to generate a secondary flame within a portion of the first combustion portion 46.

Further, an air discharge opening (upstream air discharge opening) 48 is formed at a position toward the intermediate member 6. The air discharge opening (upstream air discharge opening) 48 is used to stabilize the auxiliary flame by supplying air to each side of the flame hole assembly 3.

The flame hole assembly 3 is mainly composed of a main body 25 and a pressure reduction wall 26. The main body 25 of the flame hole assembly 3 is made by bending a sheet of metal plate, and has a top surface 30 that functions as a flame hole, and two side wall portions 31, 32 bent at an angle of about 90 ° at both edges of the top surface 30. The flame hole assembly 3 is closed on both the left and right sides and is open only at the bottom in the drawing. The top surface 30 of the flame hole assembly 3 has an elongated shape with an a-line shaped cross-section. Slits are regularly arranged on the top surface 30, and the slits form flame holes 33. The flame holes 33 formed in the main body 25 function as "central openings".

A bulging portion 34 bulging outward (in the thickness direction) is provided in each of the intermediate portions of the side wall portions 31, 32. The bulge 34 is formed along the entire width of the flame hole assembly 3.

As shown, the open ends of the side wall portions 31, 32 are bent twice at about 90 ° to form engaging recesses (or grooves) 38 on the outer sides. The bottom wall 36 of the recess 38 is perpendicular to the side wall portions 31, 32, and the outer wall 37 of the recess 38 is parallel to the side wall portions 31, 32.

As described above, the main body 25 is coupled with the decompression wall 26. The decompression wall 26 is fixed to the side wall portions 31, 32 of the main body 25 with a gap 29 therebetween. The gaps 29 each have an opening at the top in the figure. This opening functions as a side opening 27.

The side wall portions 31 and 32 have an opening 35 formed therein at a position facing the pressure reducing wall 26. The gap 29 communicates with the inner space of the main body 25 through the opening 35.

The relationship between the respective constituent members will be described below.

In the present embodiment, as described above, the premixer 2 and the flame hole assembly 3 are engaged with each other to constitute the intermediate member 6. More specifically, the opening row portion 10 of the premixer 2 is placed between the side wall portions 31, 32 of the flame hole assembly 3. In the actual manufacturing process, the premixer 2 is inserted from the opening (bottom in the drawing) between the side wall portions 31, 32 of the flame hole assembly 3 to combine the two.

The side wall portions 31, 32 and the opening row portion 10 are partially in contact by their unillustrated concave-convex shapes, thereby being integrated. As described above, the side wall portions 31, 32 and the opening row portion 10 are brought into partial contact by the concave-convex shape thereof, in other words, they are kept partially separated. The cross section of fig. 1 shows a cross section at a portion where the side wall portions 31, 32 are separated from the opening row portion 10.

The portions of the side walls 31 and 32 corresponding to the bulge portions 34 are away from the accommodated opening row portion 10. The bulging portions 34 each correspond to one row of the openings 8 of the opening row portion 10. Therefore, the outside of the opening 8 of the opening row portion 10 is kept apart from the side wall portions 31, 32, and a space (mixing space) 39 wider than the other portions is formed. This space 39 extends over the entire width of all openings 8.

Between the side wall portions 31, 32, and between the top of the opening row 10 and the top surface 30 of the flame hole assembly 3, a relatively large space 47 is formed. In the present embodiment, the flame hole upstream flow path 49 is formed by the mixing space 39 and the space 47 downstream of the open discharge portion 10.

The air flow path members 5 are coupled to both sides of the intermediate member 6. Each of the air flow path members 5 is joined to the intermediate member 6 by engaging the groove 38 of the flame hole assembly 3 with the air introduction port 15 of the base end of the member 5. Specifically, the outer wall 37 of the groove 38 is inserted into the air introduction port 15, and the tip end of the air flow path member 5 is inserted into the groove 38, whereby the air flow path member 5 is brought into contact with the bottom wall 36 of the groove 38.

The air flow passage member 5 and the intermediate member 6 (flame hole assembly 3) are partially in contact with each other by the concave-convex shape, and thus the two members are integrated. The two members are in partial contact with each other as just described, in other words, are kept partially separated from each other. In order to easily understand the function thereof, the cross section of fig. 1 shows a portion where the air flow path member 5 and the intermediate member 6 (flame hole assembly 3) are separated from each other. However, at the upstream end portion (bottom side in the drawing) of the combustion apparatus 1, the space 40 between the air flow path member 5 and the intermediate member 6 is closed by the bottom wall 36 of the groove 38. Therefore, the space 40 between the air flow path member 5 and the intermediate piece 6 does not directly communicate with the outside at the base end.

As described above, the flame hole assembly 3 is sandwiched between the two air flow path members 5, and the top surface 30 of the flame hole assembly 3 is located below (in the drawing) the top level (level) of the air flow path members 5, i.e., buried between the air flow path members 5. Therefore, the space in front of the top surface 30 of the flame hole assembly 3 is partitioned by the walls of the two air flow path members 5. In the present embodiment, a space surrounded by the top surface 30 of the flame hole assembly 3 and the two air flow path members 5 is used as the first combustion portion 46.

Next, the function of the combustion apparatus 1 will be explained in detail.

A plurality of combustion apparatuses 1 are arranged in a casing, not shown, and are blown by a blower 41 from the bottom in the drawing. The fuel gas is introduced into the apparatus 1 from a gas inlet 43 of the premixer 2 by a nozzle 42.

First, the air flow will be explained. The air flow is indicated by thin lines in fig. 1.

The air generated by the air blower 41 is rectified by the opening 45 of the rectifying vane 44 to be introduced into the combustion apparatus 1 from the base end (bottom in the drawing) of the combustion apparatus 1.

There are 3 paths for introducing air into the combustion apparatus 1. The first path is a path passing through the inside of the air flow path member 5, and the air flows into the air flow path member 5 through an air introduction port 15 formed at the base end portion of the air flow path member 5, and flows upward to the distal end through the air flow path 13 in the air flow member 5. The majority of the air is discharged from the distal openings 20, 21 to the outside.

Also, a part of the air flowing in the air flow path member 5 is discharged from the air discharge opening 23 and the air discharge opening (upstream air discharge opening) 48 toward the combustion portion.

The air discharged through the air discharge opening 23 is discharged from the inclined surface 22 of the step portion in a forward inclined direction with respect to the axis of the combustion apparatus 1.

Further, the air discharged through the air discharge opening 48 flows in the space 40 between the air flow path member 5 and the intermediate member 6, reaching the side of the flame hole assembly 3.

The second path is a path passing through the intermediate member 6. The intermediate member 6 is constituted by the opening row portion 10 of the premixer 2 sandwiched between the side wall portions 31 and 32 of the flame hole assembly 3. A gap (opening) is provided between the opening row portion 10 and the flame hole assembly 3, and a part of the gap (opening) is opened at the bottom of the intermediate member 6.

Therefore, air enters between the premixer 2 and the side wall portions 31, 32 of the flame hole assembly 3 through the opening portion 28.

This air flows through the gaps between the side wall portions 31, 32 and the open row 10, into the mixing space 39, and then to the space 47 between the open row 10 and the top surface 30 of the flame hole assembly 3. That is, the air flows through the flame hole upstream flow path 49. Finally, the air is discharged from the slits, i.e., the flame holes 33, to the first combustion portion 46. A part of the air that has entered the space 47 enters the gap 29 between the main body 25 and the side wall portions 31, 32 from the openings 35 formed in the side wall portions 31 and 32 of the main body 25, and is discharged from the side opening 27 to the first combustion portion 46.

The third path of the air is explained in detail below. The third path is a path for primary air, which is introduced together with the fuel gas from the gas inlet 43 of the premixer 2. Since the third path is the same as the path along which the fuel gas flows, the flow of the fuel gas will be described below. In fig. 1, the flow of the fuel gas is indicated by solid arrows.

The fuel gas and the primary air are introduced from the gas inlet 43 of the premixer 2 into the third path, mixed with the air in the mixer 7 and the like, and the mixed gas flows into the opening discharge portion 10. Since the plurality of openings 8 are linearly arranged in the opening discharge portion 10, the fuel gas that has entered the opening discharge portion 10 is uniformly discharged from each opening 8. The fuel gas discharged from the opening 8 of the opening discharge portion 10 enters the mixing space 39 formed between the side wall portions 31, 32 of the flame hole assembly 3 and the opening 8 of the opening discharge portion 10, and is mixed with the air flowing in the flame hole upstream flow path 49 (including the mixing space 39).

The air flowing in the flame hole upstream flow path 49 (including the mixing space 39) flows vertically (from below to above), whereas the fuel gas discharged from the opening 8 of the opening discharge portion 10 flows in a direction perpendicular to the air flow. Therefore, the fuel gas collides vigorously with the air in the mixing space 39, thereby promoting the mixing of the fuel gas and the air. Further, since the mixing spaces 39 each extend in the entire length direction of the open discharge portion 10, the pressure is also smoothed.

The fuel gas flows into the space 47 after passing through the mixing space 39, during which mixing of the fuel gas with the air is promoted. Thereafter, the fuel gas flows into the space 47 between the open discharge portion 10 and the top surface 30 of the flame hole assembly 3 in the same path as the gas flow in the flame hole upstream flow path 49, and is mostly discharged from the slits (flame holes) 33 to the first combustion portion 46. A part of the air having entered the space 47 enters the gap 29 between the decompression wall 26 and the side wall portions 31, 32 from the openings 35 formed in the side wall portions 31, 32 of the main body 25, and is discharged from the side surface openings 27 to the first combustion portion 46.

The fuel gas discharged from the flame holes 33 is mixed with the air in the premixer 2 and further mixed with the air in the mixing space 39, thus becoming uniform and discharged from the flame holes 33 at a uniform speed.

However, although the fuel gas discharged from the flame holes 33 is mixed with air, the amount of air is lower than the theoretical amount of air. This is why the fuel gas discharged from the flame holes 33 cannot be completely combusted with only the fuel gas in an oxygen-deficient state.

The fuel gas is ignited, and the fuel gas generates a primary flame in the first combustion portion 46 to perform primary combustion. However, as described above, the fuel gas is not completely combusted due to insufficient oxygen, resulting in generation of a lot of unburned combustible components.

Unburned combustible components are discharged to the outside from the opening of the first combustion portion 46. Here, air is supplied from the distal end of the air flow path member 5 to the outside of the first combustion portion 46. Therefore, the unburned combustible components are subjected to secondary combustion based on the supply of oxygen. In other words, the region outside the first combustion portion 46 functions as a second combustion portion, and generates secondary flame.

In the present embodiment, air is supplied to the base end portion of the primary flame, and the auxiliary flame is generated at the base end portion of the primary flame.

In the present embodiment, the fuel gas is discharged not only from the flame holes 33, i.e., the "central opening", but also from the side openings 27. However, the flow rate of the fuel gas discharged from the side surface opening 27 is slower than the flow rate of the fuel gas discharged from the flame holes 33. Specifically, the fuel gas enters the gap 29 between the decompression wall 26 and the side wall portions 31, 32 from the openings 35 formed on the side wall portions 31, 32 of the main body 25, and is discharged from the side surface openings 27 to the first combustion portion 46. This limits the amount of fuel gas that enters the gap 29, resulting in a small amount of fuel gas that is discharged from the side opening 27. Conversely, the side openings 27 all have a large opening space. Therefore, the fuel gas discharged from the side opening 27 has a low flow rate.

Further, as described above, a part of the air passing through the air flow path member 5 is discharged from the air discharge opening (upstream air discharge opening) 48 into the space 40 between the air flow path member 5 and the intermediate member 6, passes through the space 40, and reaches the side of the flame hole assembly 3. Therefore, the side surface of the flame hole assembly 3 is rich in oxygen compared to other portions, and the fuel gas discharged from the side surface opening 27 is ensured to be burned relatively stably based on the supplied air.

As described above, in addition to the low flow rate of the fuel gas, a stable pilot flame is generated in the vicinity of the side opening 27. The base end portion of the primary flame is held by a small flame generated in the vicinity of the side opening 27.

Further, in the present embodiment, the secondary flame is stabilized by the air discharged from the air discharge opening 23 toward the combustion portion. Specifically, in the present embodiment, the first surface 11 and the second surface 12 of the air flow path member 5 have the inclined surface 22 at a portion corresponding to the base end portion of the first combustion portion 46. An air discharge opening 23 is formed in the inclined surface 22, and air is supplied from the base end portion of the first combustion portion 46 in a direction inclined with respect to the air flow direction. Therefore, the supplied air is supplied to the first combustion portion 46 without interfering with the flow of the primary flame or the unburned gas. As a result, a part of the unburned gas in the first combustion portion 46 starts to be combusted, a part of the unburned gas generates a secondary flame, and the secondary flame is coupled with the external secondary flame, so that the external secondary flame is also stabilized.

In the present embodiment, as described above, the air discharge opening 23 facing the combustion portion is opened in an oblique direction, and does not interfere with the flow of the primary flame or the unburned gas. As a result, the secondary flame is generated at a position distant from the air flow passage member 5, and the air flow passage member 5 is not excessively heated.

Therefore, the combustion apparatus of the present embodiment can stabilize both the primary flame and the secondary flame, and is therefore very practical.

Now, a more practical configuration example of the present invention will be described with reference to the drawings after fig. 2. The embodiments described below are actually designed to implement the present invention, and have the most preferred configurations.

Although the basic structure and basic function of the combustion device shown in the figures following fig. 2 are the same as in the above-described embodiment, a practical design is implemented in terms of details. The same reference numerals are given to members that perform the same functions as those of the previous embodiment, and the repeated functions will be described only briefly.

As shown in fig. 3 and 4, a plurality of the combustion apparatuses 1 shown in fig. 2 are arranged side by side in the casing 54. The combustion apparatus 1 of the present embodiment also includes a premixer 2, a flame hole assembly 3, and an air flow path member 5. The premixer 2 and the flame hole assembly 3 are joined to constitute an intermediate member 6, and the intermediate member 6 is sandwiched between the two air flow path members 5.

The shape of the premixer 2 is shown in fig. 9, 10 and 11. The premixer 2 is formed by press-molding a steel plate into a developed shape having a concave-convex shape on the surface, bending and joining by spot welding at the periphery. Spot welding is performed at the peripheral flange 51.

The combined premixer 2 has a shape of a front plate 52 and a rear plate 53 symmetrical to the front plate 52 as shown in fig. 8 and 9. The premixer 2 has a stubby shape with a flat top 50 and is sealed at its outer periphery to prevent gas leakage.

The premixer 2 forms an integral (unity) gas flow path between the front plate 52 and the rear plate 53. Specifically, the steel plate forms a space at a position where the convexo-concave shapes of the front panel 52 and the rear panel 53 correspond to each other, and thus, a gas flow path is formed by the space.

As shown in fig. 9, in the premixer 2 employed in the present embodiment, the gas flow path is roughly divided into an upper portion and a lower portion. More specifically, the gas flow path is mainly composed of the mixing flow path 19 and the opening discharge portion 10.

Referring to fig. 9, a mixing flow path 19 is formed from the inlet of the gas flow path to the open discharge portion 10 in the lower portion of the premixer 2. The gas introduction port 43 is opened at a corner (corner) of the lower portion of the combustion apparatus 1 from the flow path inlet. The gas introduction port 43 has a squeeze portion 55 partially squeezed in cross-sectional area and a diameter expansion portion 56 downstream thereof gradually expanding in cross-sectional area. A uniform cross-sectional portion 57 having a uniform cross-sectional area extends further downstream. The flow path from the gas introduction port 43 through the squeeze portion 55 and the diametrically expanded portion 56 to the uniform cross-section portion 57 is straight.

The end of each cross-sectional portion 57 is connected to the open row portion 10 having a flow path bent at a right angle.

Here, in the present embodiment, the just-front portion of the opening row portion 10 is not pressed.

Referring to fig. 9, the opening row portion 10 is located at an upper portion of the premixer 2 and extends in the entire length direction. As shown in fig. 10 and 11, the sectional area of the opening row 10, in other words, the space between the front panel 52 and the rear panel 53 of the opening row 10 is large.

Referring to fig. 10 and 11, the open row 10 has a cross-section of two-piece construction with a small area 58 of slightly smaller cross-section near the top 50.

Specifically, the opening row portion 10 has a cross section in which the top portion 50 is flat and the upper vertical walls 81 extend vertically from both sides of the top portion 50. The bottom edges of the upper vertical walls 81 are each connected to an inclined wall, extending slightly outwardly. In addition, the bottom edge of the inclined surface meets the lower vertical wall 82.

The small-area portion 58 as the outer surface of the opening row portion 10 has many openings 8 on both the front panel 52 and the rear panel 53. The openings 8 are formed in a linear arrangement at predetermined intervals.

In the present embodiment, the openings 8 are formed only on the front and rear sides of the opening row portion 10, not on the top portion 50.

Next, the air flow path member 5 will be described in detail with reference to fig. 8, 12, and 20. The air flow path member 5 is similarly formed by press-molding a single steel plate into a developed shape having irregularities on the surface, bending the steel plate, and connecting the bent steel plate by spot welding on the outer periphery. As shown in fig. 8, the air flow path member 5 is constituted by a first panel 11 and a second panel 12, and the first panel 11 and the second panel 12 are joined at the outer periphery with a small gap, thereby forming a cavity as an air flow path 13.

The distal end of the air flow path member 5 has an acute angle bend constituting a crest 9 extending in a ridgeline.

As shown in fig. 12, the air flow path member 5 has flanges 83 at both side portions adjacent to the bent portion, and the flanges 83 are fixed to both side portions by spot welding.

The base end of the air flow path member 5 is open between the first panel 11 and the second panel 12, forming an air inlet 15.

Referring to fig. 12, the air flow path member 5 is thin-walled and is roughly divided into three regions in the height direction in its vertical state.

Specifically, the three regions are composed of an introduction portion 60 from the base end to about one-third of the total height, an intermediate portion 61 from the introduction portion 60 to about two-thirds of the total height, and a first combustion portion forming portion 62 of the other one-third of the total height in the vicinity of the distal end.

The air flow path member 5 constitutes a flow path from the air introduction port 15 toward the distal end, and the cross-sectional area of the flow path narrows toward the distal end.

Specifically, as shown in fig. 8, a portion (the introduction portion 60) from the air introduction port 15 to about a third of the total height has a substantially uniform cross-sectional area. In other words, in the introduction portion 60, as shown in the cross section of fig. 8, the first panel 11 and the second panel 12 are parallel to each other without changing the interval therebetween.

The intermediate portion 61 has a substantially conical shape.

Specifically, as shown, the intermediate portion 61 extends in a tapered shape, with a lower portion thereof being wider and narrower as going upward. However, a bulge portion 84 is formed between the distal end of the tapered portion and the first combustion portion forming portion 62. The two sides of the outer wall defining the bulge 84 are parallel to each other.

The first combustion section forming portion 62 has a substantially uniform cross-sectional area (except for the apex portion 9), but its cross-sectional area per unit length is about one-third of that of the introduction portion 60. A step formed by the inclined surface 22 is formed between the first combustion portion forming portion 62 and the intermediate portion 61.

The air flow path member 5 has air discharge openings in three regions. Generally, these three regions include a distal end portion, a position facing the first combustion portion 46, and a position facing the intermediate member 6.

Specifically, the first panel 11 and the second panel 12 of the air flow path member 5 are bent angularly at distal ends thereof, forming an inclined surface 16 and an inclined surface 17 at the first panel and the second panel, respectively. As shown in fig. 12, the inclined surfaces 16 and 17 each have a rounded distal opening 20. The top (ridge line portion) is also formed with a rounded distal opening 21.

Further, in the present embodiment, the top 9 and the inclined surface 16, the inclined surface 17 have a short slit-like distal end opening 63 and a long slit-like distal end opening 64. Each shorter distal opening 63 extends over the entire height of the inclined surface 16, the inclined surface 17 and the top 9. And each longer distal opening 64 extends from the first panel 11 and the second panel 12 parallel to the top 9.

The longer slits (distal openings) 64 are greater in number than the shorter slits (distal openings) 63; two or three longer slits 64 are arranged in a row, then one shorter slit 63, then two or three longer slits 64 are arranged in a row, and so on. This sequence is provided over the entire region in the longitudinal direction of the air flow path member 5.

The above-mentioned circular distal openings 20 and 21 are formed between two slits (distal openings) 63 or 64.

As with the previous embodiment, the distal openings 20 and 21 are used to provide secondary air for the secondary flame.

Further, an air discharge opening 23 facing the combustion portion is formed on the inclined surface 22 between the first combustion portion forming portion 62 and the intermediate portion 61. The air discharge opening 23 supplies secondary air into the primary flame generated in the first combustion portion 46, burns a part of the primary flame and generates a secondary flame.

In addition, an air discharge opening (upstream air discharge opening) 48 is formed between the introduction portion 60 and the intermediate portion 61 near the boundary. The air discharge opening (upstream air discharge opening) 48 is used to supply air to the side of the flame hole assembly in order to stabilize the auxiliary flame.

Each of the first panel 11 and the second panel 12 of the air flow path member 5 has a concave-convex shape at each portion, so that a gap is formed between the two panels or between each panel and another member.

Next, in the vicinity of the distal end portion, a plurality of grooves 70 and grooves 71 extending in the height direction are formed on the wall defining the first combustion portion forming portion 62. Both the grooves 70 and 71 are concave or hollow in surface view and extend in parallel in the height direction. The groove 70 is shorter than the groove 71. The grooves 70 and 71 are formed mainly for reinforcing the panel.

In the present embodiment, the grooves 70 and 71 are provided over the entire width of the air flow path member 5, and are arranged in the order of: a plurality of short grooves 70, then a plurality of long grooves 71, then a plurality of short grooves 70, and so on.

Also, the distance between the long grooves 71 is wider than the distance between the other grooves.

As shown in fig. 12 and 13, a recess 72 is formed between each two long grooves 71 and near the base end portions of the long grooves 71. Each recess 72 is streamlined and concave in surface view. More specifically, each of the concave portions 72 is formed by a large circle and a small circle whose centers are offset from each other and whose circumferences are connected by a common tangent line, the large circle being located upstream of the air flow path, and the small circle being located downstream of the air flow path. The straight line connecting the centers of the two circles is parallel to the direction of the airflow. The common tangent line connecting the two circles forms an inclination angle of less than or equal to 30 degrees with respect to the straight line connecting the centers of the two circles.

As shown in fig. 12, six ribs 73 are formed in the intermediate portion 61 of the air flow passage member 5. Each rib 73 is arranged parallel to the airflow direction. Each rib 73 is in contact with the outer surface of the intermediate member 6 to form a gap therebetween, and as described below, the rib 73 has a top (ridge) and the position of the top (distance from the center line of the air flow path member 5) is completely at the same level at any point. Specifically, as described above, the intermediate portion 61 has a tapered flow path cross section, but the height (rise dimension) of the rib 73 increases upward in an opposite tapered manner, and the position of the top is at the same level.

A plurality of grooves 75 are also formed in parallel on the introduction portion 60. The grooves 75 each extend from the base end to the distal end of the air flow path member 5, and have a concave shape as viewed superficially.

The groove 77 extends in the lateral direction (in the direction perpendicular to the airflow) near the introduction portion 60.

The groove 77 is formed mainly for positioning.

A substantially triangular ridge 80 is formed in the center of each side surface of the air flow path member 5.

The flame hole assembly 3 will now be explained. Referring to fig. 8 and 14, the flame hole assembly 3 is composed of a main body 25 welded at each side with a decompression wall 26.

The main body 25 of the flame hole assembly 3 is also formed by press-molding a steel plate into a developed shape having a concave-convex shape on the surface, bending and joining by spot welding at the outer periphery. As shown in fig. 14, the main body 25 has flanges 85 at both sides adjacent to the top surface 30, joined by the flanges 85, and the surface opposite to the top surface 30 is open.

As shown in fig. 8 and 14, the main body 25 of the flame hole assembly 3 has a top surface 30 functioning as a flame hole and two side wall portions 31 and 32 bent at an angle of about 90 degrees at both sides of the top surface 30. The top surface 30 of the flame hole assembly 3 has an elongated shape with an a-line shaped cross-section. The top surface 30 is roof-shaped with a central ridge 86 highest and gradually sloping walls 87 on either side.

As described above, the flame hole assembly 3 is made by bending a piece of metal plate that is folded down at the ridge 86 of the top surface 30. Thus, as shown, the fold-up portion projects downwardly, becoming a vertical wall 88 within the cavity of the flame vent assembly 3.

The top surface 30 of the main body 25 has a slit-like opening constituting a flame hole (central opening) 33. Each slit (flame hole 33) extends in the width direction of the top surface 30. A plurality of slit-like openings are formed in parallel over the entire area in the longitudinal direction of the top surface 30. As shown in fig. 14, the plurality of slit-shaped openings constitute a flame hole group 89, and the plurality of flame hole groups 89 are provided at regular intervals on the top surface 30.

As shown in fig. 8, with respect to the cross section of the main body 25, the main body 25 has two pressing portions 78 and 79. Conversely, two bulging portions, i.e., a distal bulging portion 90 and an intermediate bulging portion 91 excluding the proximal end portion are provided.

Specifically, the main body 25 has a distal bulging portion 90 including the above-described top surface 30 and an intermediate bulging portion 91 formed in the middle portion. The distal end pressing portion 78 is formed between the intermediate bulge portion 91 and the distal end bulge portion 90. The base end pressing portion 79 is formed near the base end of the intermediate bulging portion 91.

Among the above-described bulging portions 90, 91 and pressing portions 78, 79, the distal end bulging portion 90 and the intermediate bulging portion 91 are formed over the entire width of the flame hole assembly 3.

As shown in fig. 14, a row of small openings 35 is formed on the side of the distal bulge 90.

As shown in fig. 14, the base end pressing portion 79 has a plurality of ribs 92. Each rib 92 is outwardly bulged in a surface view; in other words, the groove 93 is formed in the cavity as shown in fig. 6. Each rib 92 extends in the height direction of the flame hole assembly 3, and is arranged in parallel in the width direction of the flame hole assembly 3.

As shown in fig. 6, 8, 16, and 17, the open end sides of the side walls 31 and 32 are bent twice by about 90 °, and a concave groove (or groove) 38 for bonding is formed on each outer side. The bottom wall 36 of the recessed groove 38 is perpendicular to the side walls 31, 32, and the outer wall 37 of the joining recessed groove 38 is parallel to the side walls 31, 32.

The outer wall 37 constituting the groove 38 has a substantially trapezoidal frontal shape. Specifically, as shown in the enlarged view of fig. 15, both sides of the outer wall 37 are tapered. In addition, as shown in fig. 16 and 17, the side wall portions 31, 32 in the recess 38 each have a ridge 95. The ridges 95 are located at both ends of the groove 38, respectively; one ridge 95 is located at one end.

The pressure reducing wall 26 is fixed to the upper end portions of the respective side wall portions 31, 32 of the main body 25. As shown in fig. 14, each of the decompression walls 26 is a long plate covering the entire area of the distal end bulge 90 of the main body 25. A gap 29 is formed between the decompression wall 26 and each of the side wall portions 31, 32 of the main body 25. Each gap 29 is open at the upper side in the figure. This opening functions as a side opening 27. Here, as shown in fig. 8, the pressure-reducing wall 26 has a small ridge 97 on its inner surface, and the ridge 97 is in contact with the main body 25 to maintain the distance of the side opening 27.

As described above, the row of openings 35 is formed on the distal end bulge portion 90 (fig. 14). The gap 29 communicates with the inner space of the main body 25 through the opening 35.

At both end portions of the main body 25, the side wall portions 31, 32 are joined by spot welding to constitute a flange 85, and have a gap 98 from the base end to the vicinity of the intermediate bulge portion 91.

Next, the relationship between the respective constituent members will be explained with reference to fig. 5 and 6.

In the present embodiment, the premixer 2 and the flame hole assembly 3 are also joined to constitute the intermediate member 6.

As described above, the flame hole assembly 3 (intermediate member 6) is sandwiched between the two air flow path members 5, and the top surface 30 of the flame hole assembly 3 is below (in the drawing) the top horizontal surface of the air flow path members 5 in the drawing, i.e., buried between the air flow path members 5. Therefore, the space in front of the top surface 30 of the flame hole assembly 3 is partitioned by the walls of the two air flow path members 5. In the present embodiment, the space surrounded by the top surface 30 of the flame hole assembly 3 and the two air flow path members 5 functions as the first combustion portion 46.

The intermediate member 6 is constituted by inserting the premixer 2 into the cavity of the flame port assembly 3 with the top portion 50 as the front portion to join the premixer 2 and the flame port assembly 3. At this time, the flanges 51 formed on both sides of the premixer 2 are engaged with the gaps 98 formed on both sides of the flame hole assembly 3. Then, the top portions of the premixer 2 are respectively brought into contact with the innermost sides of the gaps 98, thereby completing the positioning in the insertion direction.

Vertical walls 82 formed in the lower portion of the opening row portion 10 of the premixer 2 are respectively in contact with the inner walls of the base end pressing portions 79 of the flame hole assemblies 3, thereby completing the positioning in the thickness direction.

The small area part 58 of the opening row part 10 of the premixer 2 reaches the position of the middle bulging part 91 of the flame hole assembly 3.

As for the gap between the opening row portion 10 of the premixer 2 and the flame hole assembly 3, as described above, the small-area portion 58 is located in the intermediate bulging portion 91 of the side wall portions 31, 32 of the flame hole assembly 3. Specifically, the intermediate bulge 91 corresponds to the position of the row of openings 8 of the opening row 10. Therefore, the outside of the opening 8 of the opening row portion 10 is distant from the side wall portions 31, 32, thereby forming a space (mixing space) 39 wider than other portions. The mixing space 39 extends over the entire width corresponding to the opening 8.

As described above, the lower portion of the opening row portion 10 of the premixer 2 is in contact with the inner wall of the base end pressing portion 79 of the flame hole assembly 3. Therefore, the outer wall of the opening row portion 10 is in contact with the inner wall of the flame hole assembly 3, and there is no space at most positions in the width direction. However, as described above, the base end pressing portion 79 has the plurality of ribs 92 whose inner surfaces are the grooves 93 (fig. 6). Thus, the outer wall of the port row 10 remains separated from the inner wall of the flame hole assembly 3 at the location of the rib 92. Further, each rib 92 extends in the height direction of the flame hole assembly 3, thereby ensuring that the mixing space 39 communicates with the base end of the flame hole assembly 3.

Here, as for the positional relationship between the rib 92 and the opening 8 formed on the opening row portion 10 of the premixer 2, as shown in fig. 18, the opening 8 is located above the rib 92. In other words, the opening 8 is located on an extension of the rib 92. In the present embodiment, the ribs 92 correspond to the openings 8 one by one as shown in fig. 18, but instead of one, the openings 8 may be more than the ribs 92 or the ribs 92 may be more than the openings 8 as shown in fig. 19.

There is a gap between the base end of the flame hole assembly 3 and the premixer 2. Therefore, the mixing space 39 communicates with the outside through the rib 92 (the groove 93) and the above-mentioned gap.

Above the mixing space 39, on the other hand, there is a relatively large space 47 between the side wall portions 31, 32 and between the top 50 of the opening row 10 and the top surface 30 of the flame hole assembly 3. In the present embodiment, the mixing space 39 and the space 47 downstream of the open discharge portion 10 constitute a flame hole upstream flow path 49.

Referring to fig. 5 and 6, the air flow path member 5 is combined with both sides of the intermediate member 6. Each air flow path member 5 is fixed to the intermediate member 6 by engaging the air introduction port 15 at the base end of the air flow path member 5 with the groove 38 of the flame hole assembly 3. Specifically, the outer wall 37 of the groove 38 is inserted into the air introduction port 15, and the tip of the air flow path member 5 is inserted into the groove 38, so that the air flow path member 5 is brought into contact with the bottom wall 36 of the groove 38.

Here, as described above, the outer wall 37 of the groove 38 is in a truncated-cone shape in a surface view, and both sides are tapered, so that when the air flow path member 5 is joined, the inner wall of the air introduction port 15 conforms to (follow) the taper of the outer wall 37 of the groove 38, thereby completing the positioning in the width direction.

As shown in fig. 17, when the air flow path member 5 is fitted in a normal position in the flame hole assembly 3, the ridge 95 formed in the groove 38 engages with the outer edge of the groove 77 formed near the opening of the air flow path member 5 in a click stop manner.

Further, as shown in fig. 24, when the air flow path member 5 is fitted in the regular position, the air discharge opening 23 facing the combustion portion is located between the flame hole groups 89 of the flame hole assembly 3 in the width direction.

At the upstream end (bottom in the drawing) of the combustion apparatus 1, a space 40 between the air flow path member 5 and the intermediate member 6 is closed by the bottom wall 36 of the groove 38. Therefore, the space 40 between the air flow path member 5 and the intermediate member 6 does not directly communicate with the outside at the base end.

As shown in fig. 5 and 6, the distal end pressing portion 78 reaches the upstream air discharge opening 48 side of the air flow path member 5. The distal end extrusion 78 is a recess of the surface of the flame hole assembly 3, so there is a gap between the air flow path member 5 and the flame hole assembly 3 near the upstream air discharge opening 48.

Further, the gap communicates with the first combustion portion 46. Specifically, the air flow path of the air flow path member 5 is tapered toward the distal end beyond the opening 48, and therefore the outer wall of the air flow path member 5 is located on the inner side of the air flow path toward the downstream, thereby forming a wide space between the air flow path member 5 and the flame hole assembly 3. Here, the outer wall of the air flow path member 5 and the flame hole assembly 3 are partially in contact with each other by a rib 73 formed on the air flow path member 5.

The function of the combustion apparatus 1 will be explained below.

As shown in fig. 3, a plurality of combustion apparatuses 1 are housed in a casing 54, and as shown in fig. 4, air is blown from the bottom in the figure by a blower 41. Further, the fuel gas is introduced from the gas inlet 43 of the premixer 2 through a nozzle.

The air flows substantially in the same manner as in the above-described embodiment, that is, the air flow generated by the blower 41 is introduced into the combustion apparatus 1 from the base end (bottom in the drawing) of the combustion apparatus 1 after being rectified by the opening of the rectifying vane 44 (fig. 4).

As in the previous embodiment, there are 3 paths for introducing air into the combustion apparatus 1. Specifically, the first path passes through the air flow path member 5, and as shown in fig. 6, the air flow is introduced into the air flow path member 5 from an air introduction port 15 formed at the base end portion of the air flow path member 5, and flows upward to the distal end through the air flow path 13 inside the air flow path member 5. The majority of the air is discharged from the distal openings 20, 21 to the outside.

Here, in the present embodiment, as shown in fig. 20, the distal end of the air flow path member 5 is acute-angled, and among all the distal end openings, the distal end openings 63, 64 are slits extending over the entire height of the slopes 16, 17 and the top 9, thereby preventing air from being trapped in the distal end portion or generating turbulence.

As shown in fig. 21, for example, when the distal end portion of the air flow path member is circular, the air introduced from the air introduction port 15 hits an arc surface of the ceiling and flows around the distal end portion along the arc surface. As indicated by the arrows, the air flowing around hits the newly supplied air flow, causing the discharge of the newly supplied air to be disturbed, and the discharge direction to be twisted. Thus, the circular distal end portion of the air flow path member 5 generates turbulence or air vortex, resulting in an unstable air flow direction. This causes the secondary flame to flicker. Furthermore, according to the test of the present inventors, this also causes noise.

On the other hand, the present embodiment has an acute-angled distal end portion as shown in fig. 20, thereby ensuring that less parts are struck by the supply air and less air flows around the distal end portion. Further, a slit-shaped opening is formed on the inclined surface, so most of the air striking the inclined surface is discharged to the outside through the slit-shaped opening. This stabilizes the discharge direction of air, makes flickering of secondary flames less, and reduces noise. However, in the present invention, the distal end shape of the air flow path member is not limited thereto, and may be a circular shape as shown in fig. 21.

In the combustion apparatus 1 of the present embodiment, a part of the air flowing in the air flow path member 5 is also discharged through the air discharge opening 23 and the air discharge opening (upstream air discharge opening) 48 toward the combustion portion.

The air discharged toward the air discharge opening 23 of the combustion part is discharged from the inclined surface 22 toward the space between the flame hole groups 89, 89 of the flame hole group assembly 3 in a direction inclined to the axial front of the combustion apparatus 1.

The air discharged through the opening (upstream air discharge opening) 48 flows into the space 40 between the air flow path member 5 and the intermediate member 6, and then reaches the side of the flame hole 3. More specifically, the air discharged through the opening 48 is discharged into the gap formed by the base-end pressing portion 78 of the flame hole assembly 3, and then flows into the space formed by the tapered wall of the air flow path member 5 to be discharged to the side surface of the flame hole assembly 3.

The second path passes through the inside of the intermediate member 6, and in the second path, air is introduced between the premixer 2 and the side wall portions 31, 32 of the flame hole assembly 3 through the opening portion 28.

The air flows into the mixing space 39 through the groove 93 (the back side of the rib 92) formed on the inner surface of the flame hole assembly 3, and then flows into the space 47 between the open row portion 10 and the top surface 30 of the flame hole assembly 3. That is, the air flows in the flame hole upstream flow path 49. Finally, the air is discharged from the slits, i.e., the flame holes (central openings) 33, into the first combustion portion 46. A part of the air entering the space 47 enters the gap 29 between the main body 25 and the side wall portions 31, 32 from the openings 35 formed in the side wall portions 31, 32 of the main body 25, and is discharged from the side opening 27 into the first combustion portion 46.

The third path of the air will now be described in detail. The third path is a path for primary air, which is introduced together with the fuel gas from the gas inlet 43 of the premixer 2. Since the third path is the same as the path through which the fuel gas flows, the flow of the fuel gas will be described as an example. The flow of fuel gas is indicated by solid arrows.

The fuel gas and the primary air are introduced from the gas inlet 43 of the premixer 2 into the third path, mixed with the air in a portion such as the mixer portion 7, and the mixed gas flows into the opening discharge portion 10. Here, in the present embodiment, there is no pressing portion between the cross-sectional portion 57 and the opening row portion 10. Therefore, the fuel gas enters the open discharge portion 10 without a particular change in flow rate.

The fuel gas that enters the opening discharge portion 10 is uniformly discharged from each opening 8. Specifically, since the inside of the opening discharge portion 10 is not so small, a dispersed minute vortex is generated in a portion such as a meandering flow path of the premixer 2. Further, as described above, there is no squeezing portion immediately before the open discharge portion 10, so the change in the flow velocity of the fuel gas introduced into the open discharge portion 10 is small over the entire flow path cross section. Therefore, the change in the internal pressure of the orifice discharge portion 10 is small, and the fuel gas is uniformly discharged through each orifice 8. The opening diameter of the opening 8 can be reduced to equalize the amount of the ejected gas.

The fuel gas discharged from the opening 8 of the opening discharge portion 10 enters the mixing space 39 constituted by the intermediate bulging portion 91 of the flame hole assembly 3, and is mixed with the air flowing in the flame hole upstream flow path 49 (including the mixing space 39).

The air flowing in the mixing space 39 flows from the bottom to the top in the drawing and is rectified.

Specifically, the air flowing in the mixing space 39, which is introduced into the mixing space 39 from the opening 28 between the premixer 2 and the side wall portions 31, 32 of the flame hole assembly 3, passes through the groove 93 (the back side of the rib 92) formed on the inner surface of the flame hole assembly 3, and thus becomes a laminar air flow.

More specifically, in the present embodiment, most of the base end pressing portion 79 of the flame hole assembly 3 is in contact with the outer wall of the premixer 2, but the base end pressing portion 79 is formed with many grooves 93 on the inner surface thereof, and therefore has a gap at the position of the groove 93. Each recess 93 communicates with the mixing space 39. Therefore, the air introduced from the opening 28 between the premixer 2 and the side wall portions 31, 32 passes through the plurality of recesses 93 and then reaches the mixing space 39. Since the grooves 93 are elongated flow paths arranged in parallel at regular intervals, the introduced air is rectified by flowing in the plurality of grooves 93.

The air flowing in the flame hole upstream flow path 49 (including the mixing space 39) flows in the height direction of the combustion apparatus 1, and the fuel gas that has been discharged from the opening 8 of the opening discharge portion 10 flows into the mixing space 39 in the direction perpendicular to the air flow. Therefore, the fuel gas discharged from the opening 8 of the opening discharge portion 10 also hits the air at the mixing space 39, promoting mixing thereof with the air.

Further, in the present embodiment, the openings 8 of the opening discharge portion 10 are respectively located on the extended portions of the grooves 93 (the back sides of the ribs 92), so the air passing through the grooves 93 more surely hits the fuel gas discharged from the openings 8.

Further, since the mixing space 39 extends over the entire width of the open discharge portion 10, the pressure is smoothed.

The fuel gas passing through the mixing space 39 flows upward into the space formed by the distal end bulge 90, where the mixing with the air is promoted during the flow. Then, most of the fuel gas is discharged from the slits, i.e., the flame holes 33, into the first combustion portion 46.

Since the gas is mixed with the air in the premixer 2 and further in the mixing space 39, the fuel gas discharged from the slits is homogeneous and the flow rate at the time of discharge from the slits is uniform.

A part of the air having entered the space 47 enters the gap 29 between the main body 25 and the side wall portions 31, 32 from the opening 35 formed on the side wall portion of the main body 25, and is then discharged into the first combustion portion 46 from the side opening 27.

The fuel gas is ignited, and the fuel gas generates a primary flame in the first combustion portion 46 to perform primary combustion. Unburned combustible components are discharged from the opening of the first combustion portion 46 to the outside to be subjected to secondary combustion with the air supplied from the distal end portion of the air flow passage member 5.

Further, in the present embodiment, air is supplied into the base end portion of the primary flame to generate the auxiliary flame at the base end portion of the primary flame.

In short, in the present embodiment, a part of the fuel gas is discharged from the side opening 27 into the first combustion portion 46. However, the flow rate of the fuel gas discharged from the side opening 27 is slower than the flow rate of the fuel gas discharged from the slit. Specifically, the fuel gas enters the gap 29 between the main body 25 and the side wall portions 31, 32 from the opening 35 formed on the side wall portion of the main body 25, and then is discharged into the first combustion portion 46 from the side opening 27. Therefore, the amount of fuel gas entering the gap 29 is limited, and thus the amount of gas discharged from the side opening 27 is small. However, each of the side openings 27 has a large opening space, so the fuel gas discharged from the side opening 27 flows slowly.

Further, as described above, a part of the air passing through the air flow path member 5 is supplied to the fuel gas discharged from the side surface opening 27, thereby ensuring complete combustion.

Specifically, the air discharged from the air discharge opening (upstream air discharge opening) 48 passes through the gap formed by the side wall of the air flow path member 5 and the distal end pressing portion 78 of the flame hole assembly 3, flows along the gap formed by the tapered wall of the air flow path member 5, and then reaches the side surface of the flame hole assembly 3.

Coupled with the low flow rate of the fuel gas as described above, a stable pilot flame is produced near the side opening 27. Therefore, the base end of the primary flame is held by the small flame generated near the side opening 27.

Also in the present embodiment, air is supplied obliquely through the air discharge opening 23 formed on the inclined surface 22 toward the combustion portion, so that part of the unburned gas in the first combustion portion 46 starts to burn, generating a partial secondary flame. The secondary flame is connected to an external secondary flame.

Further, in the present embodiment, air is discharged between the flame hole groups 89 of the flame hole assembly 3, and therefore, sufficient air is supplied to the vicinity of the flame hole groups 89, thereby surely stabilizing the primary flame.

Also in the present embodiment, the air supplied from the air discharge opening 23 toward the combustion portion does not obstruct the flow of the primary flame or unburned gas, so that the secondary flame is generated at a position away from the air flow path member 5 without excessively heating the air flow member 5.

Therefore, the combustion apparatus of the present embodiment stabilizes the primary flame and the secondary flame, and is practical.

The above embodiment describes the premixer whose side surface has the opening for discharging the fuel gas by way of example. This configuration discharges the fuel gas in a direction perpendicular to the air flow, so that the fuel gas and the air frequently collide to promote mixing of the two.

In order to exert similar effects, a structure in which the fuel gas is obliquely discharged may be considered. For example, as shown in fig. 22, roof-shaped inclined surfaces 66 and 67 having a slit-shaped opening 68 are formed at the top of the premixer 2. In the present embodiment, the fuel gas is discharged obliquely forward from the slit-shaped opening 68. As a result, the fuel gas impinges on the air, promoting mixing with the air. Further, the present embodiment rarely causes swirl of the fuel gas or air, thereby stabilizing the concentration of the fuel gas.

The combustion apparatus shown in fig. 23 has a slit-like opening 69 formed at the top of the premixer.

It is recommended to discharge the fuel gas in the direction intersecting the air flow, but the present invention does not exclude the configuration shown in fig. 23 in which the fuel gas is discharged in the air flow.

In the embodiment shown in the figures subsequent to fig. 2, each member has many concave-convex shapes on its surface. The uneven shape not only functions to form a flow path, but also serves to increase the rigidity of each plate. The uneven shape not forming the flow path merely serves to increase the rigidity of each plate.

In each of the above embodiments, the gap between the metal plates constitutes an integrated flow path. Specifically, a recess is formed in one or both of the plates, thereby forming a gap between the plate and the other plate. Here, forming a concave portion or the like on an arbitrary plate when forming a flow path is only one modification of the design, and the present invention is not limited to the above-described embodiment. In the above-described embodiment, for example, the second path includes a flow path passing between the inner surface of the flame hole assembly 3 and the outer peripheral surface of the premixer 2 to secure the flow path by forming the groove 93 on the inner surface of the flame hole assembly 3. However, conversely, the flow path may be formed by forming a recess or the like in the premixer 2.

Claims (14)

1. A combustion apparatus, comprising:

at least one premixer in which fuel gas and air are premixed, the premixer having an opening row portion in which openings are arranged in a row;

at least one air flow path member in the shape of a wall having at least one distal air discharge opening at a distal end thereof; and

at least one flame hole assembly provided between two of the air flow path members or between the air flow path member and another wall,

a flame hole upstream flow path is formed between the opening row portion and the flame hole assembly, and a space enclosed by the flame hole assembly and the air flow path member forms a first combustion portion,

air is supplied to the air flow path member, the flame hole upstream flow path, and the premixer, and

the fuel gas is supplied to the premixer to be premixed with the air in the premixer, the thus obtained air-fuel gas mixture is supplied into the flame hole upstream flow path through the opening of the opening discharge portion to be further mixed with the air and discharged into the first combustion portion through the flame hole assembly in an oxygen-deficient state to be combusted, and is further combusted by supplying the air from the distal air discharge opening of the air flow path member,

the air flows in a flow direction in the flame hole upstream flow path, and the openings of the opening row portion open in a direction intersecting the flow direction.

2. The combustion apparatus as claimed in claim 1,

a mixing space adjacent to the open row portion is provided in the flow path upstream of the flame holes,

the openings of the opening row open into the mixing space.

3. The combustion apparatus as claimed in claim 2,

the mixing space extends substantially over the entire width of the row of openings.

4. The combustion apparatus as claimed in claim 1,

the flame hole assembly includes a flame hole forming portion and two side wall portions, and has an opening between the two side wall portions at a portion opposite to the flame hole forming portion,

the opening row portion of the premixer is surrounded by the side wall portion, and

the air is supplied through the openings between the side wall portions.

5. The combustion apparatus as claimed in claim 1,

the air flow path member has an air discharge opening toward the first combustion portion for discharging air from the air flow path member to the first combustion portion.

6. The combustion apparatus as claimed in claim 5,

the air flow path member has an inclined surface on which the air discharge opening toward the first combustion portion is formed.

7. The combustion apparatus as claimed in claim 5 or 6,

the flame hole assembly has a plurality of flame hole groups,

the air discharge opening facing the first combustion portion is provided at a position corresponding to between the flame hole groups of the flame hole assembly.

8. The combustion apparatus as claimed in claim 1,

the air flow path member having an upstream air discharge opening for discharging air, the upstream air discharge opening being located upstream of a portion of the air flow path member defining the first combustion portion,

the air discharged from the upstream air discharge opening flows to the side of the flame hole assembly.

9. The combustion apparatus as claimed in claim 1,

the flame hole assembly has a central opening and side openings,

the flow rate of the fuel gas discharged from the side openings is slower than the flow rate of the fuel gas discharged from the central opening, and the air flows near the side openings of the flame hole assembly.

10. The combustion apparatus as claimed in claim 1,

the flame hole component consists of a main body and a pressure reducing wall arranged on the side surface of the main body,

a gap having a side opening is defined between the main body and the pressure-reducing wall, an

The main body has an opening through which a portion of the fuel gas flowing in the main body flows into the gap.

11. The combustion apparatus as claimed in claim 1,

the openings of the opening row part are all in a slit shape.

12. The combustion apparatus as claimed in claim 1,

the opening row portion has an inclined surface on which the opening is formed.

13. The combustion apparatus as claimed in claim 1,

the opening row portion has an interior angle of 180 degrees or less.

14. The combustion apparatus as claimed in claim 1,

the distal end of the air flow path member is an acute angled ridge.