JP3302888B2 - Gas combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a gas combustion apparatus used in a multi-tube boiler and the like, and a premixed gas is introduced into a relatively thin packed bed of heat-resistant ceramic particles or metal particles from below. By supplying the gas and performing surface combustion on the outer surface layer of the packed bed, stable combustion with low NOx and high power density can be performed, and a large-sized combustion device with high performance can be achieved. The present invention relates to a combustion device.

[0002]

2. Description of the Related Art As a gas combustion device used in a multi-tube boiler or the like, a blast combustion device of the type in which gas and air are forcibly mixed and burned in a combustion chamber and a surface of a ceramic plate having many small holes are conventionally used. The surface combustion device of the type in which the premixed gas is burned (see Japanese Utility Model Laid-Open No. 2-135135).
No. 7) and a catalytic combustion device of the type in which a premixed gas is burned by utilizing the oxidizing action of a catalyst in a catalyst layer in which a metal catalyst is supported on ceramic particles (Japanese Patent Application Laid-Open No. 5-223201). Developed and used.

[0003] However, since the blast combustion apparatus forcibly mixes the air by blowing air around the ejected gas (or partially premixed gas), and diffuses and burns the mixed gas in the combustion chamber, the blast combustion apparatus is more difficult. This would require a large combustion space. As a result, there is a disadvantage that the gas combustion device is inevitably increased in size and the boiler equipment and the like are also increased in size.

[0004] In the above-mentioned surface combustion apparatus, distortion and cracks often occur in the plate due to a temperature difference generated between a place where a flame port exists and a place where no flame port exists on the ceramic plate. As a result, it is actually difficult to manufacture a large-capacity combustion device, and the capacity is practically 300,000K.
cal / h or less, there is a problem that flashback or flame lift is likely to occur, and it is difficult to perform stable combustion.

Further, in the above-mentioned catalytic combustion apparatus, it is necessary to preheat the catalyst or the premixed gas to the catalyst activation temperature, and it is unavoidable that the catalyst is thermally degraded. Many problems remain.

On the other hand, as one solution to the above-mentioned problems in the conventional combustion apparatus, as shown in FIG.
A water-cooled distribution grid 31 is provided on the bottom surface of the combustion device main body 30,
The ceramic granules 32a are filled above the combustion layer 32a.
And a cooling water pipe 33 is horizontally arranged in the combustion layer 32, and the combustion layer 3 is passed through the water-cooled distribution grid 31.
The premixed gas 34 supplied to the inside 2 is diffused and burned in the outer surfaces of the granules 32a and in the gaps between the granules, and the gas combustion apparatus which takes out the generated heat to the outside through the cooling water pipe 33 first. (Japanese Patent Laid-Open No. 145927/1995).

The gas combustion apparatus shown in FIG. 17 can perform relatively stable combustion over a wide range of air ratio. Also,
It has an excellent effect that it generates less unburned harmful substances and NOx, has excellent heat transfer characteristics, and can achieve a significant downsizing of a gas combustion device (or a boiler facility using the same). However, the gas combustion apparatus still has many problems to be solved. First, the first problem is that it takes time to stop the gas combustion device, and the energy consumption required for cooling water circulation increases. That is, the combustion layer 32 is formed by filling ceramic particles having a diameter of about 2 to 20 mm into substantially the entire internal space of the main body 30. Therefore, the heat capacity of the combustor body 30 itself inevitably increases, and when the gas combustion device is stopped, it is necessary to circulate the cooling water for a considerably long time after the stop, and the power cost of the circulation pump is reduced. The problem is that it increases.

The second problem is that it is necessary to circulate cooling water forcibly, and a so-called natural circulation type cooling system cannot be employed. That is, in the gas combustion apparatus of FIG. 17, the cooling water pipe 33 is buried in the combustion layer 32 in a horizontal state, and the combustion layer 32 is formed from a packed layer of ceramic granules 32a. ,
Due to its structure, the forced circulation system must be used. As a result, even a very small gas combustion device requires a forced circulation type cooling system, and there is a problem in that it is difficult to reduce equipment costs and running costs of the cooling system.

[0009] The third problem is the prevention of flashback and the stability of combustion. As described above, the gas combustion apparatus of FIG. 17 can perform relatively stable diffusion combustion in the combustion layer even when the combustion amount and the air ratio of the premixed gas change, and the water-cooled distribution grid 3
By providing 1, the flashback is almost completely prevented. However, in reality, flashback has not yet been completely prevented by 100%, and some problems remain in terms of safety. That is, the premixed gas 34 supplied through the water-cooled distribution grid 31 is ignited by an ignition source 35 provided on the downstream side outside the combustion layer 32, and the combustion flame immediately after ignition is formed in the upper space 30 a of the combustion layer 32. You. Also,
As the combustion layer 32 is heated by the flame, the combustion line moves upstream (downward) between the particles 32a by a kind of flashback phenomenon, and the downstream side separated from the cooling distribution grid 31 by the quenching portion. In the combustion layer, the combustion is continued. However, in the combustion device of FIG. 17, the water-cooled distribution grid 31 has an extremely simple configuration in which the cooling water pipes 31b are simply arranged between the perforated plates 31a, 31a.
Since no consideration is given to the premixed gas supply method (for example, the mixed supply of the rich premixed gas and the lean premixed gas or the adjustment of the ejection speed of the premixed gas), the flashback is completely stopped. There is a drawback that it has not been reached before it can be prevented.

[0010]

SUMMARY OF THE INVENTION The present invention comprises a combustion layer 32 comprising a packed layer of relatively large-diameter porous ceramic particles 32a, in which a premixed gas is diffused and burned inside the combustion layer 32. The above-mentioned problems in the gas combustion apparatus having the configuration as shown in FIG. 17, that is, the increase in energy consumption after the combustion apparatus is stopped, that the natural circulation cooling system cannot be adopted due to the structure, and that a flashback may occur. This is to solve the problems such as lack of safety, etc.It is a natural circulation cooling system, and it is possible to reduce the size and capacity of the gas combustion device and completely prevent flashback. It is an object of the present invention to provide a gas combustion device which is excellent in safety and can easily start and stop the combustion device.

[0011]

In order to solve the above-mentioned problems, in the present invention, a combustion apparatus is provided with a premixed gas flow hole formed in a bottom surface of a combustion chamber surrounded by a water cooling wall, and the premixed gas flow hole is provided. A thin packed layer of small-sized ceramic particles is formed on the holes, and the premixed gas supplied from the premixed gas flow holes into the packed layer is surface-burned at the outer surface layer of the packed layer. I have.

As shown in FIG. 18, the combustion form of the premixed gas in the packed bed composed of the ceramic granules is determined by the sectional combustion load (kcal / m ² h) of the ceramic packed bed. It has been found that there are three forms, surface combustion and fluid combustion. Note that FIG.
Means that a ceramic granule having an outer diameter of 5 mm
Laminated at a height of about 70 mm on a perforated plate having an area of 0 mm, a premixed gas of natural gas (13A) is supplied from below the perforated plate, and the air ratio is 1.27 to 1.30. It shows the relationship between the sectional combustion load (kcal / m ² h) of the packed bed and the combustion mode when the amount of combustion of the premixed gas is changed.

As is apparent from FIG. 18, when the sectional combustion load is 75 × 10 ⁴ kcal / m ² h or less, the premixed gas is initially burned at the upper part of the ceramic packed bed. Due to the flashback phenomenon, the combustion sequentially moves into the packed bed, and finally, the combustion continues in a state where the flame exists in the packed bed. In addition, the combustion device of FIG.
This cross section uses a combustion mode in which the combustion load is in a range of 75 × 10 ⁴ kcal / m ² h or less, in which diffusion combustion in the combustion layer is performed.

On the other hand, the sectional combustion load is about 450 × 10 ⁴ k
When cal / m ² h or more, the ceramic particles forming the packed bed begin to flow, and when the sectional combustion load is further increased, a so-called fluidized bed combustion state is obtained. The starting point of the flow of the packed bed varies depending on the outer diameter and properties of the ceramic particles forming the packed bed.
Assuming mφ, the flow start point is about 600 × 10 ⁴ kcal
/ M ² h. Further, the value of the sectional combustion load representing the flow starting point of the ceramic particles becomes lower as the ceramic particle diameter becomes smaller.

Further, the sectional combustion load is about 75 × 10 ⁴ to 4
In the range of 50 × 10 ⁴ kcal / m ² h, the combustion mode is a so-called surface combustion state in the outer surface layer of the ceramic particle packed bed.

By the way, in the range of the sectional combustion load, that is, under the condition of surface combustion, the flow rate of the premixed gas in the packed bed and at the outlet of the packed bed is considerably higher than the burning velocity. There is no flashback. Further, the ceramic particles forming the filling layer have good thermal conductivity, and each particle is in a state of point contact, so that a large number of minute spaces are formed between the particles. As a result, the ceramic particles themselves are cooled by the room temperature premixed gas flowing at high speed in the minute space, and the ceramic particles are not excessively heated. That is, the thermal stress due to heating hardly occurs in the ceramic particles forming the filling layer. In addition, there is no need to consider the heat capacity of the packed bed after stopping the combustion as in the conventional example.

Further, since the surface combustion itself is carried out on the outer surface of a large number of ceramic particles in the outer surface layer of the packed layer having a large unevenness, stable combustion is continued in a wide range of air-fuel ratio and combustion amount. It becomes possible. Further, in the case of surface combustion, since the flame becomes a large number of small flames due to the combustion of the premixed gas, the combustion temperature becomes a temperature value at which the generation of NOx is relatively small unlike the case of the conventional blast combustion. NOx is greatly reduced. FIG. 19 shows FIG.
8 shows the combustion characteristics when the premixed gas is subjected to surface combustion in the ceramic packed bed of No. 8, and shows that the NOx value is relatively low.

The present invention is mainly based on utilizing the surface combustion of the premixed gas in the outer surface layer portion of the packed bed made of the ceramic granules. A premixed gas flow hole is formed on the bottom surface of the narrow combustion chamber formed by the wall, and a premixed gas supply device is arranged below the premixed gas flow hole.
A filler layer was formed by laminating 10 mm ceramic particles at a height of 20 mm to 100 mm with a heat insulating material interposed between the ceramic particles and the water pipe wall, and the filler layer was supplied into the filler layer through the premixed gas flow holes. The basic constitution of the present invention is to cause the mixed gas to burn on the surface of the outer surface layer of the packed bed.

The invention described in claim 2 is the first invention.
In the invention, a premixed gas supply device is provided with a wind box having a rectangular shape in cross section and a sectional area gradually decreasing toward a tip end, and a fuel gas injected into combustion air at an inlet of the wind box. And a pre-mixed gas forming mechanism for mixing air and fuel gas by ejecting air.

Further, according to a third aspect of the present invention, in the first aspect of the invention, one or a plurality of perforated plates are provided at the bottom of the narrow combustion chamber formed by the water pipe wall. The perforated plate is set to have a porosity of 15 to 30%, the pore size is made smaller than the diameter of the ceramic particles filling the upper portion, and the holes of the perforated plate are used as premixed gas flow holes. It is characterized by having made it.

According to a fourth aspect of the present invention, a premixed gas supply device is provided with a wind box surrounding a lower part of a perforated plate on a bottom surface of a combustion chamber, a gas supply main pipe arranged along the wind box, and a gas supply main pipe. A branch pipe which is further branched and rises with its front end directed toward the perforated plate, a cover body surrounding a part of the back side of the perforated plate and the front end of the branch pipe, and a gas jet provided on the side of the front end of the branch pipe. An outlet and a gas outlet for supplying gas from the gas supply main pipe into the wind box, and a concentrated premixed gas is passed through a hole of a perforated plate located inside the cover body, and a gas discharged from the outside of the cover body. The diluted premixed gas is supplied into the packed bed through the holes of the perforated plate located at the position (1).

According to a fifth aspect of the present invention, the combustion chamber is formed in a narrow rectangular column shape by a water pipe wall including a finned outer water pipe and an inner water pipe, and the fin of the inner water pipe near the front on the long side. To form a combustion gas passage, and discharge combustion gas in the combustion chamber to the outside through a combustion gas passage formed between the combustion gas passage and the inner / outer water pipes. .

According to a sixth aspect of the present invention, the combustion chamber is formed in a narrow rectangular shape and a combustion gas passage is provided at a corner of a water pipe wall forming a long side of the combustion chamber. Along with forming a combustion gas passage by providing a water pipe wall in parallel with the water pipe wall provided with the passage at an interval outside the water pipe wall,
A water pipe array is arranged in a combustion gas passage formed by both water pipe walls, and combustion gas from a combustion chamber is introduced into a combustion gas passage formed by both water pipe walls through a combustion gas passage provided in the corner portion. Further, a basic structure of the present invention is that the exhaust pipe is configured to be discharged from a space between the two water pipe walls to a flue through a space between an outer water pipe wall and a casing provided outside the water pipe wall.

According to a seventh aspect of the present invention, in the sixth aspect, the water pipe row provided between the water pipe walls is a water pipe row including finned water pipes or bare water pipes or both. It is assumed that.

The invention according to claim 8 is characterized in that both side walls of a narrow rectangular can body are formed by two parallel rows of water pipe walls connecting the upper header and the lower header, and a heat-resistant block is provided on the front side thereof. A wall is provided, and the front space of the can body is used as a combustion chamber,
Further, a water pipe row is disposed inside the can body as a combustion gas passage in the rear space, and a perforated plate forming a bottom surface of the combustion chamber is disposed above the lower header at intervals. A ceramic granule having an outer diameter of 2 to 10 mm is placed on a plate with a heat insulating material interposed between the ceramic tube and a water pipe wall for 20 mm to 100 mm.
The filling layer is formed by stacking the premixed gas at a height of 2 mm, and the premixed gas supplied from the premixing gas supply portion formed between the lower header and the perforated plate into the filling layer through the premixed gas flow hole of the perforated plate is filled. The basic constitution of the present invention is to perform surface combustion on the outer surface layer of the layer.

According to a ninth aspect of the present invention, in the eighth aspect of the present invention, a premixed gas inlet, a pilot burner, a flame detector, and a ceramic particle filling port are provided in the heat-resistant block wall on the front side. An exhaust port for combustion gas is provided on the rear side of the body, and an air cooling mechanism is provided on the heat-resistant block wall.

The premixed gas 19 (or the rich premixed gas 19a and the lean premixed gas 19b) in which the air ratio λ is adjusted to the flammable range from the premixed gas supply device 16 through the premixed gas flow hole on the bottom of the combustion chamber. Is supplied into a packed bed 15 formed by filling ceramic granules to a predetermined height, and a pilot burner 17 is operated. Thereby, the premixed gas 19 is ignited, and combustion starts on the surface of the packed bed 15 of the combustion chamber 14. The heat of the combustion gas generated by the combustion of the premixed gas 19 is transferred to the water pipe wall or the water pipe row, and then the combustion gas is discharged to the outside through the flue 13.

In the present invention, the filling layer is formed by ceramic granules, and the surface of the premixed gas is burned in the outer surface portion of the filling layer. Therefore, the shape of the filling layer can be freely selected. can do. For this reason, for example, it is possible to form an elongated combustion chamber that was impossible in the conventional blast combustion, and it is possible to significantly reduce the lateral width of the can body of the combustion device.

Further, as in a conventional combustion apparatus using a ceramic plate made of a sintered body, special measures are taken for mounting the ceramic plate to prevent a short path of the premixed gas due to damage to the plate. Such a need is completely eliminated, and the structure of the combustion chamber can be extremely simplified.

Further, since there is no danger of causing a flashback unlike a conventional combustion apparatus using a combustion layer made of ceramic granules, all special measures for the premixed gas supply section are unnecessary, and the structure is reduced. It can be greatly simplified.

[0031]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional side view of a gas combustion device according to the present invention, FIG. 2 is a sectional view taken along line AA of FIG. 1 (after ceramic particles are filled), FIG. 3 is a sectional view taken along line BB of FIG.
FIG. 4 is an enlarged view of a part of FIG. 3, and FIG. 5 is a cross-sectional view taken along the line CC of FIG. 1 to 5, reference numeral 1 denotes a casing, 2
Is a cover, 3 is a heat-resistant block, 4 is combustion air, 5 is an outer water pipe, 6 is an inner water pipe, 7 is a fin of a water pipe, 8 is an upper header, 9 is a lower header, 10 is a fuel gas, and 11 and 12 are combustion. Gas passage, 13 a flue, 14 a combustion chamber, 15 a ceramic packed bed, 15 a ceramic granules, 15 b a heat insulating material, 16 a premixed gas supply device, 17 a pilot burner, 18 a flame detector, 19 Denotes a premixed gas, 20 denotes a combustion gas, and 21 denotes a premixed gas forming mechanism.

As shown in FIG. 1 and FIG.
The longitudinal cross-sectional shape is formed in the shape of a narrow rectangular quadrangular prism, and both sides in the longitudinal direction are formed in a so-called water pipe wall structure by the casing 1, the heat-resistant material 3a, the inner and outer water pipes 5, 6, the water pipe fins 7, and the like. Have been. Further, a flue 13 is provided on the back side of one short side of the combustion device main body, and a heat-resistant block 3 is provided on the other short side (front side), respectively. A pilot burner 17 and a flame detector 18 to be described later are inserted. Further, the outer water pipe 5
The inside water pipes 6 with fins are arranged in a line at a predetermined interval inside the space, and the gap between the inner and outer water pipes 5, 6 forms a combustion gas passage 11.

A plurality of fins 7 on the front side of the inner water pipe row 6 are cut off at a middle portion thereof to form a combustion gas passage 12 as shown in FIGS. Through the gap passage 12 of the inner water pipe 6 from which
The combustion gas 20 flows as shown by the arrow in FIG. The upper end and the lower end of each of the outer water pipes 5 and the inner water pipes 6 are connected to an upper header 8 and a lower header 9, respectively.
A so-called cooling water natural circulation type multi-tube boiler is configured.

A narrow combustion chamber 14 is formed between the inner water pipe rows 6 on both sides of the combustion apparatus main body, and has a bottom surface 14a.
Is provided with a premixed gas flow hole 14b through which a premixed gas 19 from a premixed gas supply device 16 described later flows. On the bottom surface 14a of the combustion chamber 14, a heat-resistant ceramic particle 15 having a particle size of about 2 to 10 mmφ is provided.
a is filled to a predetermined height, for example, about 20 to 100 mm, and the ceramic filler layer 15 of the present invention is formed by the granules 15a. The smaller the particle size of the ceramic particles 15a, the better the flammability,
If the particle size is 2 mmφ or less, the premixed gas flow holes must be reduced, which may cause troubles such as clogging, and the pressure loss in the packed bed increases as described later. Therefore, it is not appropriate to reduce the particle size to about 2 mmφ or less. When the particle size is about 10 mmφ or more, the pressure loss is reduced, but the surface combustion tends to become unstable. Therefore, it is desirable that the particle size be about 10 mmφ or less.

Further, a refractory material or a heat insulating sheet 15b is provided on a side surface of the filling layer 15 composed of the ceramic particles 15a. By providing the heat insulating material or the heat insulating sheet 15b, the phenomenon that the combustion range on the outer surface of the packed bed is slightly narrowed when the distance between the water cooling walls on both sides is shortened is prevented, and the surface combustion range becomes more stable.

The flammability of the premixed gas in the packed bed 15 improves as the particle size of the ceramic particles 15a decreases, but the pressure loss in the packed bed 15 increases. Therefore, when the particle size of the ceramic particles is small, for example, when the outer diameter is about 2 to 3 mmφ, the height of the packed layer is about 1 mm.
The thickness is most preferably about 00 mm, preferably about 50 to 70 mm. If the height exceeds 100 mm, a problem occurs in terms of pressure loss. Also, the height of the packed bed is about 20m
m or less, the surface combustion becomes slightly unstable,
It is more likely to cause a flashback. Therefore, it is desirable that the height of the ceramic filling layer be about 20 mm or more.

Further, in the present embodiment shown in FIGS. 1 to 5, the slit-shaped premixed gas flow holes 14b are formed in the bottom surface 14a of the combustion chamber 14.
It is a matter of course that the bottom surface 14a of the combustion chamber 14 may be formed of a single perforated plate, or a plurality of perforated plates may be arranged at predetermined intervals on the bottom surface 14a instead of b.
It is needless to say that the inner diameter of the premixed gas flow hole 14b must be smaller than the outer diameter of the ceramic particles to be used, and from the viewpoint of combustion stabilization, the area of the combustion chamber bottom surface 14a is small. It has been determined that an aperture ratio of about 15-30% is required.

As shown in FIGS. 1 and 4, the premixed gas supply device 16 is disposed along the longitudinal direction below the lower header 9 below the combustion chamber 14 and extends downward. A wind box 16a and a premixed gas nozzle 16b forming a premixed gas supply device 16 are provided on the lower surface side of the narrow rectangular combustion chamber bottom surface 14a surrounded by the header 9. That is, as shown in FIG. 5 and FIG. 6, the premixed gas supply device has a rectangular cross section provided below the bottom surface 14a of the combustion chamber 14 and has a horizontally long window box 16a having a width reduced toward the tip. And a premixed gas nozzle 16b disposed in the wind box 16a in the longitudinal direction. The gas passage 16e of the premixed gas nozzle 16b has a plurality of partition plates 16d between both side wall plates 16c, 16c having a height of about 10 mm or more.
Are provided in parallel while maintaining the respective intervals at 1 to 5 mm. Further, the narrow gas passages 16e are defined by partition wall plates 16f at an appropriate pitch in the longitudinal direction as shown in FIG.
Are finished so that the cross-sectional shape becomes semicircular.

It is to be noted that the shape of the wind box 16a is reduced in width toward the tip, and the width, height and cross-sectional shape of the gas passage 16e are set to the above-mentioned values and shapes, respectively. The premixed gas from the premixed gas nozzle 16b has a jet velocity of about 3 m / sec or more, and flows smoothly and uniformly at a constant speed, and is supplied to the packed bed 15 without generating a stagnation portion. Go.

A predetermined amount of combustion air 4 is supplied into the wind box 16a by a blower (not shown). A premixed gas forming mechanism 21 is provided upstream of the premixed gas nozzle 16b (or perforated plate) of the wind box 16a. That is, the premixed gas supply mechanism 21 is formed of a plurality of (two in this embodiment) gas supply pipes 21a arranged orthogonally to the flow of the fuel air 4 (see FIG. 1). As shown in FIG. 7, the gas supply pipe 21a has a gas outlet 21b having a relatively large diameter in a direction perpendicular to the fuel air 4, and a plurality of gas outlets whose diameters are sequentially reduced in the flow direction of the air 4. Spouts 21c, 21
d is formed respectively. The gas outlet 21b,
It is desirable to provide a plurality of rows 21c and 21d at an appropriate pitch in the longitudinal direction of the gas supply pipe 21a.

FIGS. 8, 9 and 11 show another example of the premixed gas supply device 16 used in the present invention.
The premixed gas supply device 16 is intended to achieve low NOx combustion by performing lean and rich combustion. That is, as shown in FIG.
16g, which forms the bottom surface 14a of the fourth, and a horizontally long window box 16 provided below the perforated plate,
a, and a premixed gas nozzle 16b disposed in the wind box 16a in the longitudinal direction. The premixed gas nozzle 16b is further disposed in the wind box 16a in the longitudinal direction and has a plurality of gas jets on the side surface. A gas supply main pipe 22 provided with an outlet 22a, and a branch pipe 2 branched upward from the main pipe 22 and provided with a gas ejection port 23a at a distal end portion
3 and a cover 16h surrounding a part of the hole of the perforated plate 16g and the upper part of the branch pipe 23.

A predetermined amount of combustion air 4 is supplied from a blower (not shown) into the wind box 16a, and the gas ejected from the gas outlet 22 is mixed into the wind box 16a. A lean premixed gas 19a is formed. In the cover 16h, the gas discharged from the gas outlet 23a and the lean premixed gas 19a flowing from the lower opening of the cover 16h are mixed to form a rich premixed gas 19b. Further, in the example of FIG. 8, the gas supply main pipe 22 is disposed in the wind box 16a, and the gas outlet 22a is provided directly on the main pipe 22, but the main pipe 22 is located outside the wind box 16a, Gas may be supplied into the wind box 16a via a pipe. In addition, the pore size of the perforated plate 16g is such that the flow rate of the premixed gas 19 flowing through the perforated plate is about 3
m / sec or more.

Next, the operation of the gas combustion apparatus according to this embodiment will be described. Referring to FIG. 1, the premixed gas formed in premixed gas supply device 16 is uniformly supplied into packed bed 15 through each premixed gas nozzle 16b, and ignited by a fire source from pilot burner 17. Then, surface combustion starts at the outer surface layer of the packed layer 15.

The premixed gas supply device 1 shown in FIG.
In the case of using No. 6, first, the wind box 16a
By supplying a predetermined amount of combustion air 4 into the inside and simultaneously ejecting the fuel gas 10 from the gas ejection port 22a of the gas supply main pipe 22 in a right angle direction, the lean premixed gas 19a having an air ratio of about twice or more is produced. It is formed. On the other hand, inside the cover body 16h, the lean premixed gas 19a
The fuel gas from the outlet 23a of the branch pipe 23 is mixed therein, and a concentrated premixed gas 19b having an air ratio of 0.7 to 1 is formed.

The concentrated premixed gas 19b is supplied to the cover 16
h into the filling layer 15 through the perforated plate 16a in the portion covered with the porous layer 16a, and the diluted premixed gas 19a passes through the portion of the perforated plate 16g not covered with the cover body 16h.
5 respectively. While flowing between the particles in the packed bed 15, the concentrated premixed gas 19b from the center and the lean premixed gas 19a from the outer periphery mix with each other to become a flammable concentrated premixed gas and become a packed premixed gas. The combustion zone is formed in the outer surface layer of the packed bed 15 by being ignited by the pilot burner 17.

The combustion gas generated by the surface combustion on the outer surface layer of the packed bed 15 contains unburned components therein, but the unburned components (that is, the unburned premixed gas) are contained in the combustion gas. ,
Lean premixed gas 19a from the outer periphery in the combustion chamber 14
(That is, excess air in the lean premixed gas) to perform diffusion combustion, and the combustion at the outlet of the combustion chamber 14 is completely completed. By adopting the surface combustion mode as described above, rapid combustion of the premixed gas is prevented, and the flame temperature is also reduced, so that even lower NOx combustion can be achieved.

As shown in FIG. 2, the combustion gas 20 of the combustion layer 14 passes through the combustion gas passage 12 formed by cutting off the water pipe fin 7 of the inner water pipe 6 and the passage formed in the gap between the inner and outer water pipe rows 6 and 7. After flowing into the inside of the pipe 11 and exchanging heat in the water in the water pipes 6 and 7, the water is discharged from the flue 13 outside the combustion apparatus.

In this embodiment, the casing 1
Is about 1350mm in height and 500m in width on the short side
m, long side width 1500mm, water pipe outer diameter 60.3φm
m, the outer diameter of the ceramic granules 15a is 5 mm, the height of the packed layer of the ceramic granules 15a is 70 mm, and the output is 810,000 kcl /
h, and NOx generated during steady operation is also 4
0 ppm (O ₂ = 0 conversion) or less.

FIGS. 11, 12 and 13 show a second embodiment of the present invention.
11 to 13 show an embodiment, in which 1 is a casing, 2 is a cover, 3 is a heat-resistant block,
4 is combustion air, 5 is an outer water pipe, 6 is an inner water pipe, 7 is a water pipe fin, 8 is an upper header, 9 is a lower header, 10 is fuel gas, 11, 11a and 12 are combustion gas passages, and 13 is a flue. , 14 a combustion chamber, 15 a ceramic packed bed, 16 a premixed gas supply device, 17 a pilot burner, 18 a flame detector, 19 a premixed gas, 20 a combustion gas, 24a
Is a finned water pipe, and 24b is a bare water pipe.

In this embodiment, the inner water pipe 6 and the fin 7 form a narrow rectangular combustion chamber 14 having a water pipe wall structure. Further, a water pipe wall composed of an outer water pipe 5 and a fin 7 is provided outside a water pipe wall forming one long side of the combustion chamber 14, and the combustion gas passage 11 is formed by the water pipe wall. Have been.

That is, the inner water pipe 6 forming the corner of the combustion chamber 14 is not provided with the fin 7 and the combustion gas passage 12 is formed in this portion. Further, a finned water pipe 24a provided with flange-shaped fins and a bare water pipe 24b are provided between the inner water pipe wall and the outer water pipe wall, whereby heat in the combustion gas 20 is recovered. .

The combustion gas 20 in the combustion chamber 14 passes from the combustion gas passage 12 at the corner through the combustion gas passage 11 and the combustion gas passage 11a formed between the outer water pipe wall and the casing 1 and passes through the flue 13 (shown in FIG. (Omitted).
In the present embodiment, the bare water pipe 24b and the finned water pipe 24a are arranged on the upstream side and the downstream side of the combustion gas passage 11, however, all of them are provided as the bare water pipe 24b or the finned water pipe 24a. Of course, it is good. Further, as a finned water pipe, it is a matter of course that a vertical fin may be provided on the entire circumference of the pipe in parallel with a so-called pipe axis. Further, the structure of each part of the present embodiment is exactly the same as that of the first embodiment except for the arrangement structure of the water pipes, and the description thereof is omitted here.

FIGS. 14 to 16 show a third embodiment of the present invention. In FIGS. 14 to 16, 1 is a casing, 2 is a cover, 3 is a heat-resistant block, 6 is an inner water pipe, 7 Is a water tube fin, 8 is an upper header, 9 is a lower header,
11 is a combustion gas passage, 13 is a flue, 14 is a combustion chamber, 14
a is the bottom of the combustion chamber, 14b is a premixed gas flow hole, 15 is a ceramic packed bed, 15a is a ceramic granule, 15b is a heat insulating material (or heat insulating sheet), 16 is a premixed gas supply device,
16g is a perforated plate, 19 is a premixed gas, 20 is a combustion gas,
24a is a finned water pipe, 24b is a bare water pipe, 25 is an air cooling mechanism, 26 is a premixed gas inlet, and 27 is a ceramic particle filling port.

In this embodiment, the can body of the combustion device is formed by the water pipe walls on both sides composed of the water pipe 6 and the fin 7, the air-cooled heat-resistant block wall 3 on the front side, and the casing plate 1 on the rear side. The combustion chamber 14 is formed in a front part of the can body. The space behind the can body is a so-called combustion gas passage 11, in which a bare water pipe 24b and a finned water pipe 24a are provided.

Further, a premixed gas inlet 26 and a ceramic particle filling port 27 are formed in the heat-resistant block wall 3 on the front side, and a pilot burner 17 and a flame detector 18 are attached thereto. Air cooling mechanism 2 on the outer surface side
5 is air-cooled. That is, the block wall 3 is cooled by flowing the combustion air A along the outer surface of the heat-resistant block wall 3. The upper and lower ends of the water tubes 6, 24a, 24b constituting the can body are connected to an upper header 8 and a lower header 9, respectively.

In the present embodiment, a premixed gas supply section is provided above the lower header 9 as shown in FIG. That is, a perforated plate 16g that forms the combustion chamber bottom surface 14a is provided horizontally below the combustion chamber 14 and above the lower header 9, and has an outer diameter of 2 mmφ to 10 m above it.
The ceramic filler layer 15 is formed by laminating ceramic particles 15a of mφ to a height of about 20 to 100 m.

Further, a heat-resistant material or a heat-resistant sheet 15b is interposed at a portion where the ceramic filling layer 15 is in contact with the water tube row, and the heat-insulating material 15b allows the filling layer 15 to be formed in the same manner as in the first embodiment. To prevent the combustion area on the outer surface from being reduced.

The gas combustion apparatus according to the third embodiment is mainly applied to a small-capacity combustion apparatus having a steam generation amount of about 300 kg / h or less, and a premix gas supply apparatus 16 is located above the lower header 9. By doing so, it is possible to make the combustion device can compact and compact.

[0059]

According to the present invention, the combustion chamber 14 formed by the water pipe wall is provided.
Premixed gas flow holes 14b (or perforated plate 1)
6g) on which the ceramic granules 15a have a thickness of 20 to
A relatively thin packed layer of 100 mm is formed, and the surface of the premixed gas 19 is burned on the packed layer. As a result, the ceramic granules 15a are formed all over the conventional combustion chamber.
Packed bed 1 compared to a gas combustion device configured to fill
The heat capacity of the five parts is remarkably reduced, energy loss required for cooling or the like at the time of operation stop can be reduced, and the device can be started and stopped quickly. In addition, compared to a conventional combustion device using a ceramic plate made of a ceramic sintered body, the packed bed 15
Since it is formed from a, there is little danger of cracks or the like in the packed bed, there is no danger of clogging, the shape can be freely selected, the range where flashback does not occur is wide, and the ceramic particle diameter is selected, so that high load can be achieved. It has characteristics such as a wide range of use including combustion. Therefore, it is possible to manufacture a combustion device having a high output density, and it is possible to significantly reduce the size of the combustion device. Furthermore, since the combustion chamber 14 has a water-cooled wall structure with vertical water pipes and is configured to absorb the heat of the combustion gas 20, a natural circulation system for cooling water in the water pipes can be employed. As a result, the energy required for forced circulation of the cooling water is not required, and a high output density can be obtained in the form of a multi-tube once-through boiler, and a device having a large output (about 1,000,000 kcal / h) can be easily manufactured. be able to.

For example, when the gas combustion apparatus of the present invention has a capacity of 1.
When applied to a 5 t / h multi-tube once-through boiler, in the conventional blast combustion method, the shape of the combustion chamber is regulated by the flame shape, so that even the boiler body (can) alone is about 11 times.
Requires a diameter of 50 mmφ. On the other hand, when the present invention is applied, the width of the boiler body is about 500 mm is sufficient, and the can body width can be reduced to about 43%. Also, regarding the height of the can body, the rectification of combustion air required for blast combustion and the flame stabilization mechanism can be simplified, and a part of the mechanism can be configured in the boiler main body. In this case, the can body height of 1900 mm can be reduced to a height of about 1350 mm, which facilitates installation and carrying in and reduces the required floor area.

In the premixed gas supply device 16 of the second embodiment used in the present invention, the premixed gas supply device 16 is provided below the lower header 9 forming the bottom plate of the combustion chamber 14, and the lean premixed gas 19a is provided. The concentrated premixed gas 19b is supplied into the packed bed 15 at an appropriate flow rate ratio. As a result, the combustible concentrated premixed gas having an appropriate air ratio formed by mixing the two in the packed bed 15 is smoothly surface-burned at an appropriate burning speed in the outer surface layer of the packed bed 15, The unburned premixed gas is also air-combusted in the combustion chamber 14 by mixing with the air flow in the lean premixed gas 19a, which is different from that of the conventional combustion apparatus in which diffusion combustion is performed in the combustion layer. Thus, even lower NOx combustion can be achieved. The present invention has excellent practical utility as described above.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional side view of a gas combustion apparatus according to a first embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a partially enlarged view of a lower part of FIG. 3;

FIG. 5 is a sectional view taken along the line CC of FIG. 1;

6 is an enlarged cross-sectional view of a front end portion (a portion in FIG. 5) of the premixed gas supply device.

FIG. 7 is an operation explanatory view of an a part of FIG. 1;

FIG. 8 shows a second embodiment of the premixed gas supply device.

FIG. 9 is a sectional view taken along line AA of FIG. 8;

FIG. 10 is a sectional view taken along line BB of FIG. 8;

FIG. 11 is a longitudinal sectional side view of a gas combustion device according to a second embodiment.

FIG. 12 is a sectional view taken along line AA of FIG. 11;

FIG. 13 is a sectional view taken along line BB of FIG. 11;

FIG. 14 is a longitudinal sectional view of a gas combustion device according to a third embodiment.

FIG. 15 is a sectional view taken along line AA of FIG.

FIG. 16 is a partially enlarged view of a sectional view taken along line BB of FIG. 14;

FIG. 17 is a schematic longitudinal sectional view of a conventional gas combustion apparatus provided with a combustion layer formed of a packed layer of porous particles.

FIG. 18 is a diagram showing a relationship between a sectional combustion load, a combustion mode, and a pressure loss in a ceramic packed bed.

FIG. 19 is a diagram showing the relationship between the concentration of O _{2, the} concentration of NOx, and the concentration of CO using the combustion mode as a parameter in the ceramic packed bed.

[Explanation of symbols]

1 is a casing, 2 is a cover, 3 is a heat-resistant block, 3a
Is a heat-resistant material, 4 is combustion air, 5 is an outer water pipe, 6 is an inner water pipe, 7 is a water pipe fin, 8 is an upper header, 9 is a lower header,
10 is a fuel gas, 11 ・ 11a ・ 12 are combustion gas passages,
13 is a flue, 14 is a combustion chamber, 14a is a bottom of the combustion chamber, 14
b is a premixed gas flow hole, 14c is a narrow rectangular hole, 14
d is a combustion chamber space, 15 is a ceramic packed layer, 15a is ceramic granules, 15b is a heat insulating material (heat insulating sheet), 16
Is a premixed gas supply device, 16a is a wind box, 1
6b is a premixed gas nozzle, 16c is a side wall plate, 16d is a partition plate, 16e is a gas flow passage, 16f is a partition wall plate, 16g
Is a perforated plate, 16h is a cover body, 17 is a pilot burner, 18 is a flame detector, 19 is a premixed gas, 19a is a lean premixed gas, 19b is a rich premixed gas, 20 is a combustion gas, and 21 is a premixed gas. Forming mechanism, 21a is a gas supply pipe,
21b, 21c and 21d are gas outlets, 22 is a main gas supply pipe, 22a is a gas outlet, 23 is a branch pipe, 23a is a gas outlet, 24a is a finned water pipe, 24a is a bare water pipe, 2a
5 is an air cooling mechanism, 26 is a premix gas introduction port, and 27 is a ceramic particle filling port.

Continuation of the front page (56) References JP-A-7-145901 (JP, A) JP-A-7-145927 (JP, A) JP-A-1-121609 (JP, A) Japanese Utility Model Application Sho 61-175722 (JP) , U) Japanese Utility Model Showa 62-131224 (JP, U) Japanese Utility Model Showa 49-27238 (JP, U) Japanese Utility Model Utility Model 1-94725 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB Name) F23D 14/12-14/18 F23C 11/00 F22B 21/04-21/06

Claims (9)

(57) [Claims] 1. A premixed gas flow hole is formed in a bottom surface of a narrow combustion chamber formed by a water pipe wall, and a premixed gas supply device is disposed below the premixed gas flow hole. A filler layer is formed by laminating ceramic particles having an outer diameter of 2 to 10 mm at a height of 20 to 100 mm with a heat insulating material interposed between the water tube wall and the filler layer. A gas combustion apparatus characterized in that a premixed gas supplied into the inside is subjected to surface combustion at an outer surface portion of a packed bed. 2. A premixed gas supply device, comprising: a wind box having a rectangular cross-sectional shape having a rectangular shape and having a cross-sectional area gradually decreasing toward a tip end; and supplying fuel gas into combustion air at an inlet of the wind box. 2. The gas combustion apparatus according to claim 1, further comprising a premixed gas forming mechanism for ejecting and mixing air and fuel gas. 3. A single perforated plate or a plurality of perforated plates are arranged on the bottom surface of a narrow combustion chamber formed by a water pipe wall at intervals, and the porosity of the perforated plate is set to 15 to 15. 2. The gas combustion apparatus according to claim 1, wherein the hole diameter of the perforated plate is reduced to 30%, and the diameter of the hole is made smaller than the diameter of the ceramic particles filled in the upper part, and the holes of the perforated plate are used as premixed gas flow holes. 4. A premix gas supply device comprising: a wind box surrounding a lower part of a perforated plate on a bottom surface of a combustion chamber; a gas supply main pipe arranged along the wind box; A branch pipe standing up to the perforated plate, a cover body surrounding a part of the back side of the perforated plate and the tip of the branch pipe, a gas outlet provided on a side face of the tip of the branch pipe, and a gas supply main pipe. A concentrated premixed gas formed through a hole in a perforated plate located inside the cover body, and a hole in a perforated plate located outside the cover body. The gas combustion apparatus according to claim 1, wherein the lean premixed gas is supplied into the packed bed through the respective through holes. 5. A combustion gas passage formed by forming a combustion chamber in a narrow rectangular column shape with a water pipe wall including an outer water pipe and an inner water pipe with fins, and cutting off fins of an inner water pipe near a front side on a long side. The gas combustion apparatus according to claim 1, wherein the combustion gas in the combustion chamber is discharged to the outside through a combustion gas passage formed between the combustion gas passage and the inner / outer water pipe. 6. A combustion gas passage is formed in a corner portion of a water pipe wall forming a long side of the combustion chamber while forming the combustion chamber in a narrow rectangular shape, and the water provided with the combustion gas passage is further provided. A water pipe wall is provided parallel to and spaced from the outside of the pipe wall to form a combustion gas passage, and a row of water pipes is arranged in the combustion gas passage formed by the two water pipe walls, so that combustion from the combustion chamber is performed. Gas is introduced into the combustion gas passage formed by the two water pipe walls through the combustion gas passage provided in the corner portion, and further, the combustion gas is provided between the two water pipe walls to the outer water pipe wall and to the outside thereof. The gas combustion apparatus according to claim 1 or 3, wherein the gas is discharged to a flue through a space between the casings. 7. The gas combustion apparatus according to claim 6, wherein the water pipe row provided between the water pipe walls is a water pipe row including finned water pipes, bare water pipes, or both. 8. A long side wall of a narrow rectangular can body is formed by two parallel rows of water pipe walls connecting the upper header and the lower header, and a heat-resistant block wall is provided on the front side thereof. A water pipe row is arranged inside the can body as a combustion chamber, and a space behind the can body as a combustion gas passage,
Further, a perforated plate forming the bottom surface of the combustion chamber is disposed above the lower header at intervals, and ceramic granules having an outer diameter of 2 to 10 mm are placed on the perforated plate between the water pipe wall. A filler layer is formed by laminating a height of 20 mm to 100 mm with a heat insulating material interposed therebetween, and filling is performed from a premix gas supply section formed between the lower header and the perforated plate through a premix gas flow hole of the perforated plate. A gas combustion apparatus characterized in that a premixed gas supplied into a layer is subjected to surface combustion at an outer surface layer portion of a packed bed. 9. A premixed gas inlet, a pilot burner, a flame detector, and a ceramic particle filling port are provided on the heat-resistant block wall on the front side, and a combustion gas discharge port is provided on the rear side of the can body. The gas combustion device according to claim 8, wherein an air cooling mechanism is provided on the heat-resistant block wall.