JP2005249240A - Premixed gas combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a premixed gas combustion device with excellent safety for well performing excellent low load combustion and rated load combustion for a long period by completely preventing backfire and heat loss due to the overheat of a supplementary firing body. <P>SOLUTION: This premixed gas combustion device, the premixed gas formed of a combustion air and a gas-like fuel passed through the supplementary firing body is burned in a combustion chamber formed above the ceramic ball type gas permeable supplementary firing body. The supplementary firing body is formed of a fixed layer formed by filling, in a laminated state, a plurality of ceramic ball second heat resistant spherical bodies in a rectangular box formed of a heat resistant porous plate and a movable layer formed by horizontally arranging, parallel with each other, and vertically arranging a plurality of ceramic ball first heat resistant spherical bodies above the heat resistant porous plate forming the rectangular box in such a fitted state that can be vertically moved relative to each other. The side part of the movable layer in contact with a cooling wall is cooled by disposing the cooling wall above all the side parts of the rectangular box and, in the rated load combustion, the premixed gas supplied from the underside of the fixed layer is passed through the supplementary firing body in the state of flowing all or a part of the first heat resistant spherical bodies forming the movable layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to an improvement of a premixed gas combustion apparatus used in a multi-tube once-through boiler or the like, and uses a gas-permeable auxiliary combustor for premixed gas in which gaseous fuel and combustion air are mixed. In a premixed gas combustion apparatus of the type to be combusted, it can be said that the combustion chamber is maintained at a high temperature by reducing the flow rate of the premixed gas or continuing the combustion under a low O ₂ concentration. Pre-mixed gas combustion device that can greatly improve safety by completely preventing the flame in the combustion chamber from returning to the auxiliary combustion body even when combustion that is significantly different from the normal combustion state is performed It is about.

  The applicant has previously developed a premixed gas combustion apparatus using an auxiliary combustor made of ceramic balls having the structure shown in FIGS. 3 to 8 and discloses this as JP-A-2003-302012.

That is, FIG. 3 is a longitudinal side view showing the overall configuration of the premixed combustion apparatus according to Japanese Patent Laid-Open No. 2003-302012, FIG. 4 is a cross-sectional view taken along the line II in FIG. 3, and FIG. FIG. 6 is a partially enlarged view of the main part of FIG. 5, FIG. 7 is an enlarged view of the main part of FIG. 3, and FIG. 8 is an explanatory view showing a supply state of the premixed gas.
3 to 8, 1 is a premixed gas combustion apparatus, 2 is an apparatus main body, 3 is a combustion chamber, 4 is a heat exchange chamber, 5 is an upper header, 6 is a lower header, 7 is a water pipe wall, 7a is a water tube, 7b is a strip-shaped fin, 8 is a water tube group, 8a is a water tube, 8b is a finned water tube, 8c is a finned water tube, 9 is an auxiliary body, 10 is a premixed gas, 10a is combustion air, and 10b is fuel. Gas, 10c is combustion gas, 11 is a premixed gas supply means, 12 is a flue, 13 is an upper wall, 14 is a lower wall, 15 is a side wall, 16 is a front wall, 17 is a pilot burner, 18 is a steam discharge pipe, 19 is a boiler feed water, 20 is a boiler feed pipe, 21 is a movable layer, 21a is a first heat-resistant sphere, 22 is a fixed layer, 22 'is an upstream portion of the fixed layer, 22 "is a downstream portion of the fixed layer, 22a 22b is a second heat-resistant sphere, 23 is a rectangular box, 23a and 23b are heat-resistant perforated plates, 24 Is a projecting wall, 25 is a castable refractory, 26 is a premixed gas supply chamber, 27 is a supply duct, and 28 is a mixer.

  The premixed gas combustion apparatus 1 includes an apparatus main body 2, a combustion chamber 3 and a heat exchange chamber 4 formed in the apparatus main body 2, upper and lower headers 5 and 6 provided at the upper and lower portions of the apparatus main body 2, A water pipe wall 7 and a water pipe group 8 connected to the headers 5 and 6, a gas permeable auxiliary combustor 9 disposed in the lower part of the combustion chamber 3, and combustion air 10 c and natural gas directly below the auxiliary combustor 9. A three-position control multi-pipe once-through boiler comprising a premixed gas supply means 11 for supplying a premixed gas 10 mixed with the gaseous fuel 10b.

  The apparatus main body 2 has a rectangular box shape in which the outer peripheral portion is closed by the upper and lower walls 13, 14, the left and right side walls 15, 15 and the front wall 16 except for the rear end opening to which the flue 12 is connected. is there. The upper and lower walls 13 and 14 and the front wall 16 are comprised of fireproof walls (castable). Each side wall 15 is formed by a water pipe wall 7 connecting a plurality of finned water pipes.

  The combustion chamber 3 is constituted by a substantially first half portion of the internal space of the apparatus main body 2. Further, a pilot burner 17 and a viewing window (not shown) are provided on the front wall 16 of the combustion chamber 3, and the pilot flame is directed to the upper surface of the auxiliary combustor 9 described later.

  The heat exchange chamber 4 is constituted by a substantially second half portion of the internal space of the apparatus main body 2, and the front and rear end portions are opened. A front end opening of the heat exchange chamber 4 communicates with the combustion chamber 3, and a flue 12 is connected to the rear end opening. In the heat exchange chamber 4, a water tube group 8 including a plurality of water tubes 8a is disposed.

  The combustion gas 10 c passes through the heat exchange chamber 4 from the combustion chamber 3 and is discharged to the flue 12. In addition, 8a is a water pipe without fins, 8b is a water pipe with fins, 8c is a water pipe with a strip-like fin, and each water pipe 8a, 8b, 8c is arrange | positioned at zigzag form. The band-shaped finned water pipe 8 c is used to prevent the combustion gas 10 c from short-passing from the combustion chamber 3 to the rear of the heat exchange chamber 4.

  The auxiliary combustor 9 is formed in a rectangular shape that substantially matches the cross-sectional shape of the combustion chamber 3, and has a gas permeable structure in which a number of first heat-resistant spheres 21 a and second heat-resistant spheres 22 a and 22 b are stacked in two upper and lower stages. It is a structure.

That is, the auxiliary combustor 9 is formed of a movable layer 21 and a fixed layer 22 disposed therebelow as shown in FIG. The fixed layer 22 includes a plurality of second heat-resistant spheres 22a and 22b arranged in parallel in a horizontal direction in a rectangular box 23 having upper and lower walls 23a and 23b formed of a heat-resistant perforated plate (punched metal or the like) and vertically. And packed in close contact. The second heat-resistant spheres 22a and 22b are in point contact with each other in the horizontal direction and the vertical direction, and are held in a state where relative movement is impossible.
In addition, in the fixed layer 22, a large number of gas passages communicating in the vertical direction are formed by gaps between the second heat-resistant spheres 22a and 22b that make point contact in the vertical direction and the horizontal direction.

  As shown in FIG. 8, the movable layer 21 has first heat-resistant spheres 21a having a diameter larger than those of the second heat-resistant spheres 22a and 22b arranged in parallel in the horizontal direction on the upper wall 23a of the rectangular box 23 and vertically aligned in the vertical direction. And placed in close contact.

The first heat-resistant sphere 21a that forms the movable layer 21 is configured so as to be capable of relative movement in the vertical direction.
Similarly to the fixed layer 22, the movable layer 21 is formed with a large number of gas passages communicating in the vertical direction by gaps between the first heat-resistant spheres 21a that make point contact in the vertical and horizontal directions. .
Further, the movement of the movable layer 21 in the horizontal direction of the first heat-resistant sphere 21a is restricted by the front wall 16 of the apparatus body 2 and the projection wall 24 made of a refractory material provided at the boundary position between the chambers 3 and 4. Has been. The protruding wall 24 is set to a height that prevents the first heat-resistant sphere 21a from entering the heat exchange chamber 4 when the first heat-resistant sphere 21a floats during rated combustion.

  The first heat-resistant sphere 21a and the second heat-resistant sphere 22a, 22b are made of heat-resistant metal, ceramics or the like, but are generally made of ceramics such as alumina or silicon carbide having high heat conductivity. Has been. That is, the diameters of the first and second heat-resistant spheres 21a, 22a, and 22b are appropriately set in the range of 5 mm to 20 mm (more preferably 8 mm to 12 mm) according to the combustion conditions. Moreover, the height of the movable layer 21 is appropriately set in the range of 20 mm to 100 mm (more preferably 30 mm to 70 mm) according to the combustion conditions. Furthermore, the height of the fixed layer 22 and the diameters of the second heat-resistant spheres 22a and 22b are generally set smaller than the height of the movable layer 21 and the diameter of the first heat-resistant sphere 21a.

  As shown in FIG. 3, the premixed gas supply means 11 is disposed in a premixed gas supply chamber 26 formed immediately below the auxiliary combustor 9, a supply duct 27 connected thereto, and a supply duct 27. And a mixer 28. In FIG. 3, 10a is combustion air, 10b is fuel gas, and 10c is combustion gas.

  The premixed gas 10 supplied to the premixed gas supply chamber 26 by the premixed gas supply means 11 passes upward through the auxiliary combustor 9 and is ignited by the pilot burner 17, so that the upper surface region of the auxiliary combustor 9 ( In the combustion chamber 3), the rated output combustion or the low output combustion is performed.

In order to perform good combustion, it is necessary that the amount of premixed gas flowing out from the auxiliary combustor 9 to the combustion chamber 3 is uniform over the entire surface of the auxiliary combustor 9.
Therefore, the movable layer 21 is composed of the first heat-resistant spheres 21a made of ceramics (made of alumina) having the same diameter, and the fixed layer 22 is made of the second heat-resistant spheres 22a made of ceramics (made of alumina) having different diameters. , 22b, the outflow of the premixed gas is made uniform.

  That is, as shown in FIG. 8, since the movable layer 21 is formed by stacking the first heat-resistant spheres 21a having the same diameter (for example, 10 mm diameter), the gas passage formed between the first heat-resistant spheres 21a. Have the same cross-sectional area. On the other hand, the fixed layer 22 is composed of a downstream fixed layer portion 22 ″ and an upstream fixed layer portion 22 ′ having different gas passage resistances, and the upstream fixed layer portion 22 ′ is a first heat-resistant sphere. The second heat-resistant sphere 22b having a diameter smaller than that of the second heat-resistant sphere 22b is formed by laminating the second heat-resistant sphere 22b having a diameter smaller than that of the second heat-resistant sphere 22b. The spheres 22a are laminated so that the cross-sectional area of the gas passage in the downstream fixed layer portion 22 ″ is smaller than the cross-sectional area of the gas passage in the upstream fixed layer portion 22 ′.

  As a result, the gas passage resistance of the downstream fixed layer portion 22 "is higher than that of the upstream fixed layer portion 22 ', and the amount of premixed gas flowing into the downstream fixed layer portion 22" is reduced to the upstream fixed layer portion 22'. Even when the amount is larger than the premixed gas inflow amount, the premixed gas amount supplied to the movable layer 21 through the fixed layer 22 becomes uniform, and stable and good combustion is performed in the combustion chamber 3.

  Specifically, all or part of the first heat-resistant spheres 21a of the movable layer 21 float (flow) with an increase in the supply amount of the premixed gas 10 (an increase in the pressure of the premixed gas 10). After entering the non-contact state and the supply amount (pressure) of the premixed gas 10 reaches the set value, the floating state (non-contact state) is stabilized. Further, during the rated output operation, the height of the movable layer 21 is slightly higher than the layer height during low-power combustion, but does not vary greatly and stabilizes at a predetermined layer height. Further, due to the floating (flow) of the first heat-resistant sphere 21a, the premixed gas passage increases according to the supply amount of the premixed gas 10, and the pressure loss in the movable layer 21 is stabilized.

Unlike the case where the cross-sectional area of the gas passage in the movable layer 21 is simply increased, the premixed gas 10 flows out smoothly over the entire surface of the movable layer 21, so that there is no inconvenience such as a lift phenomenon.
Further, when the combustion shifts to the low power combustion, the floating state of the first heat-resistant sphere 21a is canceled and the original point contact state is restored.

The auxiliary burner 9 is a laminate of heat-resistant spheres 21a, 22a, 22b made of spherical ceramic balls.
Combustion at the time of low output is surface combustion on the heat-resistant sphere 21a without the auxiliary combustor 9 floating. The thermal conductivity of the ceramic balls is high, the mutual contact of the heat-resistant spheres 21a, 22a, and 22b is point contact, and the second heat-resistant gas is surrounded by a heat-resistant porous plate (such as punching metal). Each heat-resistant sphere is supplied to the first heat-resistant sphere through the spheres 22a and 22b at a sufficient flow velocity (faster than the combustion speed), thereby effectively cooling each heat-resistant sphere. Is not overheated or subject to heat loss.

  At the time of high power combustion, all or part of the first heat-resistant spheres float (flow) and are not in contact with each other. At this time, the supply amount of the premixed gas is also about three times (turndown ratio 1: 3) (the flow rate is also about 3 times), and the flame is formed downstream of the movable layer. Therefore, the heat-resistant sphere 21a below the movable layer is not heated excessively or suffers from heat loss. Further, there is no possibility that cracks or clogging will occur in the auxiliary combustor 9.

For the reasons described above, in the combustion apparatus, regardless of the supply amount of the premixed gas 10, the flashback phenomenon accompanying the increase in the temperature of the auxiliary combustor 9 is relatively effectively prevented. In addition, the durability of the auxiliary combustor 9 including the rectangular box 23 and the durability of the premixed gas combustion device 1 are greatly improved, and good combustion (low power combustion and rated output) is achieved over a long period of time. Combustion).
In particular, the movable layer 21 of the auxiliary combustor 9 is composed of a number of first heat-resistant spheres 21a made of ceramic balls, and the premixed gas 10 is ejected and burned from the gaps between the first heat-resistant spheres 21a. Therefore, a large number of divided flames are formed on the upper surface of the movable layer 21. In addition, a large number of high-temperature flame recirculation regions are formed on the downstream side of the first heat-resistant sphere 21a from which each premixed gas is ejected, so that the premixed gas ejection section is heated to achieve stable combustion. it can.

As a result, stable low output combustion (surface combustion) and rated output combustion can be continued over a wide range of air-fuel ratios and combustion amounts.
In addition, by appropriately setting the diameter, layer height, etc. of each heat-resistant sphere 21a, 22a, 22b, it is possible to ensure a wide range of use including rated output combustion, and a high-power density premixed gas Not only can the combustion apparatus 1 be manufactured, but also the apparatus itself can be significantly reduced in size.

  Thus, in the conventional premixed gas combustion apparatus 1, the premixed gas 10 supplied to the premixed gas supply chamber 26 passes through the gas passage of the fixed layer 22 and the gas passage of the movable layer 21. Combustion is started in the combustion chamber 3 by being ignited by the pilot burner 17, and after that, the combustion is continued by continuously supplying the premixed gas 10. The combustion gas 10c generated in the combustion chamber 3 is discharged from the combustion chamber 3 through the heat exchange chamber 4 to the flue 12, and during this time, heat exchange is performed with the boiler feed water in the water tube wall 7 and the water tube group 8. The generated steam is taken out from the header 5 through steam pipes 18 and 18.

With reference to FIG. 6 to FIG. 8, at the time of low output combustion with a small supply amount of the mixed gas 10 (at the time of low output of about 1/2 to 1/3 of the rated output), the first constituting the movable layer 21. The heat-resistant sphere 21a does not move relatively and is held in a point contact state.
Thereby, on the upper surface of the movable layer 21, surface combustion accompanied by a micro flame is performed.
At the rated output with a large supply amount of the premixed gas 10, the push-up force of the first heat-resistant sphere 21 a by the premixed gas 10 passing through the movable layer 21 exceeds its weight, and the premixed gas 10 is moved to the movable layer 21. The first heat-resistant sphere 21a constituting a part or the whole of the first heat-resistant sphere 21a passes while floating (flowing), and on the movable layer 21, rated output combustion with a long flame is performed.
When the first heat-resistant sphere 21a is in a floating (flowing) state, the pressure loss in this portion becomes almost constant even if the premixed gas amount (also the combustion amount) is increased. This means that many premixed gases can be combusted with the same blowing function force, which is one of the features of this combustion system.

By the way, in the conventional premixed gas combustion apparatus 1 using this kind of ceramic ball auxiliary combustor 9, in order to prevent so-called backfire during premixed gas combustion, the flow rate of the premixed gas 10 during low output combustion ( The supply speed is set to be faster than the turbulent combustion speed of the premixed gas.
Moreover, each heat-resistant sphere forming the auxiliary combustor 9 has a considerable heat capacity. The heat-resistant sphere itself has excellent thermal conductivity and is cooled by the premixed gas 10 in a state of point contact with each other.
Therefore, in a normal combustion state, the flame on the upper surface side of the movable layer 21 does not return to the inside of the auxiliary combustor 9 (so-called reverse fire), and stable combustion can be continued.

However, when a combustion state greatly deviating from the normal combustion state occurs, for example, the flow rate of the premixed gas 10 flowing through the auxiliary combustor 9 is greatly reduced, or combustion with a low O ₂ concentration is continued. When the temperature of the chamber 3 is kept at a high temperature for a long time, there is a risk that the flame may return to the inside of the auxiliary combustor 9 from the vicinity of the side surface of the movable layer 21, which is a problem in terms of ensuring safety. Was left.
This is because the heat-resistant sphere 21a is held in point contact with the castable refractory 25 at a relatively high temperature on the side surface of the movable layer 21, and the gap is relatively large. Because.

JP 2003-302012 A

  The present invention continues the above-described problem in the premixed gas combustion apparatus of the type using the conventional ceramic ball auxiliary combustor 9, that is, a state in which the normal combustion state is largely deviated, and the combustion chamber temperature is high. In this case, the problem is that the flame returns to the inside of the auxiliary combustor from the side surface of the movable layer 21 and may cause a so-called backfire, and the combustion chamber temperature is continuously increased. To provide a premixed gas combustion apparatus that completely prevents the flame from returning from the side surface of the auxiliary combustor to the auxiliary combustor even when abnormal combustion that is maintained at a high temperature occurs, and further improves safety. Is the main purpose of the invention.

  A first aspect of the present invention is a premixed gas of a type in which a premixed gas of combustion air and gaseous fuel passing through the auxiliary combustor is burned in a combustion chamber formed above a gas permeable auxiliary combustor made of ceramic balls. In the combustion apparatus, a fixed layer formed by laminating a plurality of second heat-resistant spheres made of ceramic balls into a rectangular box formed of a heat-resistant perforated plate, and the rectangular box. Above the heat-resistant perforated plate to be formed, there is a movable layer in which a number of first heat-resistant spheres made of ceramic balls are juxtaposed in a horizontal direction and vertically aligned in a close contact state capable of relative movement in the vertical direction. In addition, a cooling wall is provided above all sides of the rectangular box to cool the side of the movable layer in contact with the cooling wall. Mixed gas forms the movable layer It is an basic configuration of the invention that has been configured circulating in co 燃体 and in a state of flowing all or part of the first refractory spheres.

  According to a second aspect of the present invention, in the first aspect of the invention, the cooling wall is formed of a support plate and a presser plate, the lower portion is a narrow rectangle, and the upper portion is a right triangle having an inclined surface on the auxiliary combustor side. A structure having an air introduction path having a cross-sectional shape and a part of the combustion air supplied into the air introduction path from a plurality of cooling air holes formed in the inclined surface of the air introduction path into the movable layer It is designed to be ejected.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the diameter of the first heat-resistant sphere made of ceramic forming the movable layer is 5 to 20 mm.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the amount of combustion air supplied into the air introduction path is set to 3 to 8% of the total amount of combustion air and obliquely from the cooling air hole. Combustion air is jetted upward into the movable layer.

In the present invention, a cooling wall is provided on all sides of the movable layer forming the auxiliary combustor, the side of the movable layer is cooled by the cooling wall, and the combustion air enters the air introduction passage of the cooling wall. A part of the combustion air is supplied, and a part of the combustion air is ejected into the movable layer obliquely upward through the cooling air hole.
As a result, even if abnormal combustion occurs such that the flow rate (supply rate) of the premixed gas passing through the auxiliary combustor decreases or the temperature of the combustion chamber rises over a long period of time, A so-called flashback phenomenon in which the flame returns from the side into the fixed bed is completely prevented, and the safety of the premixed gas combustion apparatus is greatly improved.

Embodiments of the present invention will be described below with reference to the drawings. In the present invention, the configuration of the other parts except the main part of the present invention shown in FIGS. 1 and 2 is substantially the same as the configuration shown in FIGS. 3 to 8 described above. Therefore, these drawings are used to describe the embodiment of the present invention.
[Embodiment]
FIG. 1 is a longitudinal sectional view of a premixed gas combustion apparatus according to the present invention, which corresponds to FIG. 5 of the prior art.
2 is a partially enlarged view of the portion indicated by arrow A in FIG. 1. Except for the structure of the portion of the partially enlarged view, the structure of the other portions is the premixed gas combustion previously shown in FIGS. The configuration of the apparatus is substantially the same.
Therefore, in the description of the embodiment of the present invention, the same reference numerals are used for the same parts and members as those shown in FIGS.

  1 and 2, 3 is a combustion chamber, 5 is an upper header, 6 is a lower header, 7 is a water pipe wall, 7a is a water pipe, 7b is a strip fin, 8 is a group of water pipes, 9 is an auxiliary body, 10 is a premixed gas, 13 is an upper wall, 14 is a lower wall, 15 is a side wall, 20 is a boiler feed pipe, 21 is a movable layer, 21a is a first heat-resistant sphere (ceramic ball), 22 is a fixed layer, and 22b is Second heat-resistant sphere (ceramic ball), 23 is a rectangular box, 23a and 23b are heat-resistant perforated plates, 25 is a castable refractory, 26 is a premixed gas supply chamber, 27 is a supply duct, 29 is a cooling wall, 29a is The presser plate, 29b is a support plate, and 29c is a cooling air hole.

  The cooling wall 29 is provided on all side portions of the movable layer 21 forming the auxiliary burner 9 and cools the side portions of the movable layer 21. That is, as shown in FIG. 2, the cooling wall 29 includes a support plate 29b that is fixed upward at an upper end portion of the supply duct 27, and an air introduction passage 30 that is fixed to an inner upper portion of the support plate 29b. The support plate 29b and the presser plate 29a make the cross-sectional shape narrower at the lower part of the rectangle, and the upper part becomes narrower toward the upper part. An air introduction passage 30 having a substantially right triangle shape is formed.

  Further, cooling air holes 29c having an inner diameter of 1.5 to 2.0 mmφ are provided at a constant pitch over the entire circumference in the upper part (inclined part) of the holding plate 29a, and the combustion air enters the air introduction passage 30. Part of the combustion air 10a introduced through an introduction pipe (not shown) is ejected into the movable layer 21 through the cooling air hole 29c.

That is, a part of the combustion air 10a introduced into the air introduction passage 30 cools the cooling wall 29 itself, thereby cooling the first heat-resistant sphere (ceramic ball) 21a that is in direct contact therewith.
Further, the air flow jetted obliquely upward into the movable layer 21 from the cooling air hole 29c directly cools the first heat-resistant sphere 21a, and the flame or the like returns in the direction in which abnormal combustion occurs (backfire) Direction).

In addition, the average temperature in the auxiliary combustor 9 during normal rated output combustion is about 60 ° C., and the temperature of the combustion air 10a is set to about 40 ° C. to 50 ° C.
Furthermore, the supply amount of the combustion air 10a ejected into the movable layer 21 through the cooling air hole 29c is set to about 3 to 10% (preferably 5 to 8%) of the total combustion air supply amount.

  The parts other than the configuration and operation of the premixed gas combustion apparatus according to the present invention shown in FIGS. 1 and 2 are substantially the same as those in FIGS. 3 to 8 described above. The description is omitted.

  INDUSTRIAL APPLICABILITY The present invention is used as a combustion apparatus for various boiler apparatuses such as a multi-tube type once-through boiler and a hot water generator using a premixed gas as fuel.

It is a longitudinal cross-sectional schematic diagram of the premixed gas combustion apparatus which concerns on this invention. It is an enlarged view of the A section of FIG. 1 which shows the principal part of this invention. It is a vertical side view of the premixed gas combustion apparatus which concerns on a prior art. FIG. 4 is a cross-sectional view taken along the line II in FIG. 3. FIG. 4 is a cross-sectional view of FIG. FIG. 6 is an enlarged detailed view showing a main part of FIG. 5. FIG. 4 is an enlarged detailed view showing a main part of FIG. 3. It is the longitudinal cross-sectional view which abbreviate | omitted a part corresponding to FIG. 7 which shows the supply state of premixed gas.

Explanation of symbols

  1 is a premixed gas combustion apparatus, 2 is an apparatus main body, 3 is a combustion chamber, 4 is a heat exchange chamber, 5 is an upper header, 6 is a lower header, 7 is a water pipe wall, 7a is a water pipe, 7b is a fin, 8 is Water tube group, 8a is a water tube, 8b is a finned water tube, 8c is a finned water tube, 9 is an auxiliary combustor, 10 is premixed gas, 10a is combustion air, 10b is fuel gas, 10c is combustion gas, and 11 is premixed gas Supply means, 12 is a flue, 13 is an upper wall, 14 is a lower wall, 15 is a side wall, 16 is a front wall, 17 is a pilot burner, 18 is a steam discharge pipe, 19 is a boiler feed water, 20 is a boiler feed pipe, 21 Is a movable layer, 21a is a first heat-resistant sphere (ceramic ball), 22 is a fixed layer, 22 'is an upstream portion of the fixed layer, 22 "is a downstream portion of the fixed layer, and 22a and 22b are second heat-resistant spheres. (Ceramic balls), 23 is a rectangular box, 23a and 23b are heat resistant Plate, 24 projecting wall, 25 castable refractory, 26 premixed gas supply chamber, 27 supply duct, 28 mixer, 29 cooling wall, 29a holding plate, 29b support plate, 29c cooling air Hole 30 is an air introduction path.

Claims (4)

  In a premixed gas combustion apparatus of a type that burns a premixed gas of combustion air and gaseous fuel that has passed through the auxiliary combustion body in a combustion chamber formed above a gas-permeable auxiliary combustion body made of ceramic balls. A fixed layer formed by laminating a plurality of second heat-resistant spheres made of ceramic balls into a rectangular box formed of a heat-resistant perforated plate, and a heat-resistant perforated plate forming the rectangular box. A plurality of ceramic ball-shaped first heat-resistant spheres formed on a movable layer formed in parallel with each other in a horizontal direction and vertically aligned in a close contact state capable of relative movement in the vertical direction; A cooling wall is provided above all sides of the movable layer to cool the side of the movable layer in contact with the cooling wall, and at the time of rated output combustion, the premixed gas supplied from below the fixed layer is allowed to pass through the movable layer. First heat-resistant sphere to be formed Configuration and premixed gas combustion apparatus flowing through the auxiliary 燃体 whole or in a state for flowing a part.   The cooling wall is composed of a support plate and a presser plate, and the lower portion is a narrow rectangle and the upper portion is provided with an air introduction path having a right-angled triangular cross-section with the inclined surface on the auxiliary combustor side, 2. The premixed gas combustion according to claim 1, wherein a part of the combustion air supplied into the air introduction path is ejected into the movable layer from a plurality of cooling air holes formed in the inclined surface of the air introduction path. apparatus.   The premixed gas combustion apparatus according to claim 1 or 2, wherein the first heat-resistant sphere made of ceramic forming the movable layer has a diameter of 5 to 20 mm.   The combustion air amount supplied into the air introduction path is 3 to 8% of the total combustion air amount, and the combustion air is jetted into the fixed layer obliquely upward from the cooling air hole. The premixed gas combustion apparatus according to claim 2.

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