JP2001248801A - Fluid heating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid heating equipment which can obtain a higher NOx reducing effect while the burden of maintenance is reduced. SOLUTION: In this fluid heating equipment, a combustion chamber 3 to which the flame forming section 19 of a gas burner main body 4A is faced, and a heat-exchanging section HE which heats a fluid to be heated by using the exhaust combustion gas generated in the chamber, the chamber 3 is adjacently arranged in a heating chamber 2 so that the exhaust combustion gas may flow from the combustion chamber 3 to the section HE, and an exhaust path 5 which leads the exhaust combustion gas discharged from the section HE is provided outside the heating chamber 2. An induced draft I induces part of the exhaust combustion gas flowing to the section HE by utilizing the inducing action of gas fuel supplied to the flame forming section 19 and mixes the induced exhaust combustion gas with the gas fuel is provided in the heating chamber 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a combustion chamber which faces a flame forming portion of a gas burner body and a heat exchange portion which heats a fluid to be heated by combustion exhaust gas generated in the combustion chamber. So that the combustion exhaust gas flows from the heat exchange section to the heat chamber, disposed adjacent to the heating chamber, outside the heating chamber,
The present invention relates to a fluid heating device provided with an exhaust passage for guiding combustion exhaust gas discharged from the heat exchange unit.

[0002]

2. Description of the Related Art In such a fluid heating apparatus, a gas fuel is burned in a combustion chamber in a flame forming section of a gas burner main body, and combustion exhaust gas generated in the combustion chamber is caused to flow through a heat exchange section so that a fluid to be heated is heated. The combustion exhaust gas that has been heated and discharged from the heat exchange section is exhausted through an exhaust path provided outside the heating chamber. In such a fluid heating device, the gas fuel is burned while recirculating a part of the combustion exhaust gas generated in the combustion chamber to the flame forming portion,
It is desired that the gas fuel be slowly burned to reduce the NOx concentration of the combustion exhaust gas discharged from the exhaust passage.

Conventionally, as shown in FIG. 11, an external suction passage 41 branched from the middle of an exhaust passage 5 is connected to a suction port of a blower 9 for supplying combustion air provided outside a heating chamber 2. By this blower 9, the exhaust passage 5 is connected to the external suction passage 4.
1 and a part of the generated combustion exhaust gas E is mixed with the supply combustion air A by mixing the intake combustion exhaust gas E with the combustion air A supplied to the gas burner main body 4A. Flame forming part 1 of gas burner main body 4A
9 to be recirculated. Note that 1 in FIG.
Is a can body forming a heating chamber 2 therein, and the can body 1
The combustion chamber 3 and the heat exchange section HE are arranged adjacent to each other so that the combustion exhaust gas E flows from the combustion chamber 3 to the heat exchange section HE. 42 is
A control valve is provided in the external suction passage 41 to control the recirculation amount of the combustion exhaust gas. Reference numeral 7 denotes a fuel supply passage for supplying the gas fuel G to the flame forming portion 19 of the gas burner main body 4A.
Uses the blower 9 to convert the combustion air A into the gas burner body 4A.
And F is a flame formed in the flame forming section 19.

[0004]

However, in the conventional fluid heating apparatus, heat is radiated to the surroundings (in other words, the cooling action of the surrounding air) in the external suction passage 41 and the blower 9 located outside the heating chamber 2. As a result, acid drain easily occurs due to the condensation of moisture in the combustion exhaust gas, and oxidative corrosion is likely to occur, which causes a problem that the burden of maintenance is large.

Therefore, the applicant of the present invention first described FIG.
As shown in the figure, inside the gas burner main body 4A, the exhaust gas introduction passage 43 in which the introduction port 43a is open to the combustion chamber 3, and the combustion chamber through the exhaust gas introduction passage 43 by the attraction effect of the gas fuel G supplied to the flame forming portion 19. No. 3 proposed a fluid heating device provided with an ejector 44 for sucking a part of the combustion exhaust gas E and mixing the intake exhaust gas E with the supply gas fuel G (see Japanese Patent Application No. 2000-4401). Note that 1 in FIG.
Is a can body forming a heating chamber 2 therein, and the can body 1
The combustion chamber 3 and a heat exchange section (not shown) are arranged adjacent to each other such that the combustion exhaust gas E flows from the combustion chamber 3 to the heat exchange section inside the heating chamber 2 formed by the heating chamber 2. Also, FIG.
Numeral 7 in 0 is a fuel supply path for supplying gaseous fuel G to the flame forming section 19 of the gas burner main body 4A, and 8 is an air supply path for supplying combustion air A to the flame forming section 19 of the gas burner main body 4A. Here, F is a flame formed in the flame forming portion 19.

[0006] This is a form in which, with the supply of gas fuel to the gas burner main body, a part of the generated combustion exhaust gas is sucked directly from a combustion chamber through an exhaust gas introduction path in an ejector.
The intake flue gas is mixed with the supply gas fuel to be sent to the flame forming section, whereby a part of the generated flue gas is supplied to the flame forming section while being recirculated to the flame forming section in a mixed state with the supply gas fuel. The gas fuel is burned to reduce the NOx concentration of the generated combustion exhaust gas.

[0007] The temperature of the flue gas in the combustion chamber is considerably higher than the temperature of the flue gas in the exhaust passage (for example,
Although the temperature of the flue gas in the combustion chamber is 1000 ° C., the temperature of the flue gas in the exhaust path where the heat possessed by the flue gas is spent for heating the fluid to be heated is generally about 300 ° C.) Since the gas burner body installed in the combustion chamber becomes hot due to the heat transfer of combustion heat, as described above, the inlet of the exhaust gas introduction path is opened to the combustion chamber, and the combustion exhaust gas to be sucked into the ejector is directly discharged from the combustion chamber. By adopting a configuration in which the exhaust gas introduction path and the ejector are provided inside the gas burner main body while taking the form of suction, the combustion exhaust gas in the exhaust path as in the conventional burner shown in FIG. Condensation of moisture in the intake flue gas due to a temperature drop can be effectively prevented compared to that inhaled by a blower, and this enables Generation of acid drainage to effectively prevent at, since the oxidation corrosion which caused its acidic drain can be effectively prevented, it is possible to reduce the burden of maintenance.

However, the combustion exhaust gas in the combustion chamber sucked by the ejector has a higher specific volume due to its higher temperature than the combustion exhaust gas flowing through the exhaust passage, and the combustion exhaust gas suction amount (mass) by the ejector is larger. In other words, it is difficult to increase the exhaust gas recirculation rate, and in addition, the combustion exhaust gas in the combustion chamber sucked by the ejector has a higher residual oxygen concentration than the combustion exhaust gas flowing through the exhaust passage, so that the gas fuel The effect of slow combustion is small. From these facts, in the one proposed by the applicant of the present invention, although the desired NOx reduction effect can be obtained, there is room for improvement in obtaining a higher NOx reduction effect. there were.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fluid heating device which can obtain a higher NOx reduction effect while reducing the maintenance burden.

[0010]

Means for Solving the Problems [Invention according to claim 1]
The characteristic configuration according to claim 1, wherein a part of the combustion exhaust gas flowing through the heat exchange unit is attracted by the attraction effect of the gas fuel supplied to the flame forming unit, and the induced combustion exhaust gas is converted into the gas fuel. The attraction part which mixes with the heating chamber is provided in the heating chamber. According to the characteristic configuration of the first aspect, with the supply of the gaseous fuel to the flame forming portion, the attraction portion induces a part of the combustion exhaust gas flowing through the heat exchange portion, so that the induced combustion exhaust gas. Is mixed with the supply gas fuel to be sent to the flame forming section, whereby the supplied gas fuel is burned in the flame forming section while a part of the generated flue gas is recirculated to the flame forming section in a mixed state with the supply gas fuel. In this way, the NOx concentration of the generated combustion exhaust gas is reduced.

[0011] The combustion exhaust gas flowing through the heat exchange section uses the retained heat for heating the fluid to be heated. Therefore, the specific volume is small since the temperature is lower than the combustion exhaust gas in the combustion chamber. It is easy to increase the amount (mass) of inducing flue gas by the attraction unit, in other words, it is easy to increase the exhaust gas recirculation rate, and the flue gas flowing through the heat exchange unit is
Compared to the flue gas in the combustion chamber, the residual oxygen concentration is low, so the effect of slowly burning the gas fuel is large, and from these, the flue gas generated directly from the combustion chamber as proposed by the applicant of the present application has been described. The NOx concentration of the generated combustion exhaust gas can be further reduced as compared with the one that attracts a part.

Further, the temperature of the combustion exhaust gas flowing through the heat exchange section is higher than the temperature of the combustion exhaust gas in the exhaust passage outside the heating chamber, although the retained heat is used for heating the fluid to be heated. In addition, since the heat exchange section is provided in the heating chamber together with the combustion chamber, and the heating chamber in which the induction section is provided has a high temperature, the combustion exhaust gas is heated in the exhaust passage as in a conventional fluid heating device. It is possible to effectively prevent the condensation of moisture in the induced flue gas due to the temperature drop, thereby effectively preventing the oxidative corrosion caused by the acid drain, as compared with the case where the air is sucked into the blower outside the heating room through the outdoor outside suction passage. be able to. Therefore, it is possible to provide a fluid heating device that can achieve a higher NOx reduction effect while reducing the maintenance burden.

[0013] According to a second aspect of the present invention, an exhaust gas inducing path for inducing combustion exhaust gas from the heat exchanging portion by the attraction of the attraction portion is partitioned from the combustion chamber. It is formed in a state.
According to the characteristic configuration of the second aspect, the combustion exhaust gas is attracted from the heat exchange section through the exhaust gas induction path partitioned from the combustion chamber by the induction action of the induction section, so that the pressure of the exhaust gas induction path is changed by heat exchange. Since the pressure can be maintained lower than the internal pressure, the effect of attracting the combustion exhaust gas flowing through the heat exchanging portion can be further promoted. Can be prevented from being attracted together with the combustion exhaust gas flowing through the heat exchange section. Therefore, it is possible to prevent the attraction of the flue gas in the combustion chamber at a high temperature and in a state where the residual oxygen concentration is relatively high, while effectively increasing the intended amount of the flue gas attraction from the heat exchange section, which is the intended purpose. Therefore, the NOx concentration of the generated combustion exhaust gas can be more effectively reduced, and the NOx reduction effect can be more effectively improved.

According to a third aspect of the present invention, there is provided a guide structure for deflecting and guiding the combustion exhaust gas flowing through the heat exchange section in a direction toward the attraction section. It is in. According to the characteristic configuration of claim 3,
The guide body guides the flue gas flowing through the heat exchanging section in the direction toward the attracting section, so that the flue gas flowing through the heat exchanging section is easily attracted by the attracting section,
It is possible to further increase the amount of attracted flue gas, in other words, to further increase the recirculation rate of flue gas. Therefore, the NOx concentration of the generated combustion exhaust gas can be more effectively reduced, and the NOx reduction effect can be more effectively improved.

According to a fourth aspect of the present invention, there is provided a fuel cell system according to the fourth aspect, wherein the combustion exhaust gas induced by the attraction portion is provided inside the gas burner main body with the combustion air supplied to the flame forming portion. A cooling unit is provided for cooling by heat exchange through the heat transfer wall. According to the characteristic configuration of the fourth aspect, in the cooling unit, the combustion exhaust gas induced by the induction unit exchanges heat with the combustion air supplied to the flame forming unit through the heat transfer wall, thereby causing the combustion exhaust gas to be in the combustion exhaust gas. Since the water is appropriately cooled within a range that does not cause water condensation, the specific volume of the induced flue gas is reduced, and the amount (mass) of the flue gas attracted by the attracting portion is further increased, in other words, the exhaust gas recirculation rate is further increased. Can be higher. Therefore, the NOx concentration of the generated combustion exhaust gas can be more effectively reduced, and the NOx reduction effect can be more effectively improved.

According to a fifth aspect of the present invention, there is provided a fuel cell system according to the fifth aspect, wherein an exhaust gas outlet for extracting combustion exhaust gas from the heat exchange unit by the attraction of the attraction unit is provided in the heat exchange unit. It is provided at a location close to the communication section with the exhaust path. According to the characteristic configuration of the fifth aspect, the combustion exhaust gas that has flowed to a location near the communication section with the exhaust path in the heat exchange section is attracted by the induction section and is recirculated to the flame forming section. In other words, the further the gas flows in the heat exchange section to the downstream side of the flue gas flow path, the more the gaseous fuel that could not be burned in the combustion chamber progresses, and the lower the concentration of residual oxygen in the flue gas. By recirculating the combustion exhaust gas having a low residual oxygen concentration in a portion close to the communication portion with the exhaust passage in the above to the flame forming portion, the slow combustion of the gas fuel can be effectively promoted. By the way, in the vicinity of the communication part with the exhaust passage in the heat exchange part, the residual oxygen concentration in the combustion exhaust gas is, for example, 4-6.
%. Therefore, the slow combustion of the gaseous fuel can be effectively promoted, so that the NOx concentration of the generated combustion exhaust gas can be more effectively reduced, and the NOx reduction effect can be more effectively improved.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment in which the present invention is applied to a multi-tube water pipe boiler will be described below with reference to FIGS. As shown in FIG. 1, a water tube boiler includes a combustion chamber 3 and a combustion exhaust gas E generated in the combustion chamber 3 in a heating chamber 2 formed inside a can body 1. The heat exchange section HE for heating water is arranged adjacent to the heat exchange section HE for heating water so that the combustion exhaust gas E flows from the combustion chamber 3 to the heat exchange section HE, and the gas burner 4 is provided at the upper end of the can body 1. The flame forming part 19 is attached in a state facing the combustion chamber 3, and the heat exchange part H is provided outside the heating chamber 2.
An exhaust path 5 for guiding the combustion exhaust gas E discharged from E is provided. Then, the supply gas fuel G is burned in the flame forming portion 19 of the gas burner 4, the heat exchange portion HE is heated by the formation flame F, and the generated combustion exhaust gas E is passed through the heat exchange portion HE to generate heat. By heating the exchange unit HE, the water W supplied to the heat exchange unit HE is heated, and the generated steam S is supplied to the steam demand destination through the steam delivery path 6.

The gas burner 4 is provided with a fuel supply path 7 for supplying gas fuel G such as city gas to the gas burner main body 4A, and a blower 9 for supplying combustion air A to the gas burner main body 4A through an air supply path 8. is there. Fuel supply path 7
Is provided with a gas amount adjusting valve Vg for adjusting the gas fuel supply amount to the gas burner main body 4A, and the air supply path 8 is provided with an air adjustment valve Va for adjusting the combustion air supply amount to the gas burner main body 4A. This air regulating valve Va is linked with the gas regulating valve Vg so as to maintain the optimum air-fuel ratio in the regulation of the gas fuel supply amount (that is, regulation of the burner combustion amount) by the gas regulating valve Vg. And make it work.

A water supply passage 10 for supplying water W for heating is connected to the heat exchange part HE, and a water W flowing through the water supply passage 10 and a combustion exhaust gas flowing through the exhaust passage 5 are connected to the exhaust passage 5. E is exchanged with E to recover the sensible heat of the flue gas E and the latent heat associated with the condensation of moisture in the flue gas, and a heat exchanger 11 for preheating the feed water for preheating the feed water W is provided.

As shown in FIGS. 1 and 2, the heat exchange section HE
The inner water pipe collecting tube 12 and the outer water pipe collecting tube 13 formed by connecting a large number of water pipes p in a vertical posture with fin-like members f in a cylindrical shape are arranged coaxially at an interval from each other, The lower ends of all the water pipes p of the inner water pipe collecting pipe 12 and the outer water pipe collecting pipe 13 are connected to the ring-shaped water supply header 14, and the upper ends of all the water pipes p of the inner water pipe collecting pipe 12 and the outer water pipe collecting pipe 13 are ringed. An annular space which is connected to the steam header 15 in the shape of a circle, and the space between the inner water pipe collecting tube 12 and the outer water pipe collecting tube 13 is vertically closed by the water supply header 14 and the steam header 15 to function as a combustion exhaust gas passage 16. The space is formed. And the flue gas passage 1
The water W supplied from the water supply header 14 to the water pipes p of the inner and outer water pipe collecting tubes 12 and 13 is heated by the combustion exhaust gas E flowing through the pipe 6, and the generated steam S is collected in the steam header 15. , And is taken out through a steam delivery path 6 connected to the steam header 15.

The heat exchange part HE constructed as described above is arranged inside the can body 1, and the cavity inside the inner water pipe collecting tube 12 in the heat exchange part HE is made to be the combustion chamber 3. A lower end portion of the inner water pipe collecting tube 13 is opened over the entire circumference to form a combustion exhaust gas supply port 17, and an upper end portion of the outer water pipe collecting tube 13 is opened over the entire circumference to form a flue gas discharge port 18. The exhaust path 5 is connected to the upper end position of the can body 1 so as to communicate with the inside of the can body. Then, the flue gas E generated in the combustion chamber 3 is introduced into the flue gas passage 16 from the flue gas supply port 17 at the lower end of the heat exchange section, and is caused to flow upward through the flue gas passage 16. From the flue gas discharge port 18 at the upper end of the heat exchange section,
The gas is discharged to the exhaust path 5.

The main body 4A of the gas burner 4 is shown in FIGS.
As shown in the figure, in a configuration in which the flame forming portion 19 at the tip is attached to the upper wall 1a of the can body 1 so as to face the combustion chamber 3, the combustion air A is supplied from the air supply passage 8 described above. The air chamber 20 is formed at the base end of the gas burner main body 4A outside the combustion chamber, and receives the supply of the gas fuel G from the fuel supply path 7 and forms the flame from the fuel nozzle 21 at the tip. An internal fuel passage 23 for ejecting and supplying the fuel into the fuel ejection pipe 22 in the portion 19 is provided at the center of the gas burner main body 4A.
An annular internal air passage 24 for guiding the combustion air A supplied from 0 to the flame forming portion 19 is formed around the internal fuel passage 23 in the gas burner main body 4A.

In the flame forming section 19, the gas fuel G injected and supplied to the inside of the fuel injection pipe 22 whose end is closed.
From the plurality of fuel outlets 25 formed in the pipe wall of the fuel outlet pipe 22 to the periphery of the pipe, and the combustion air A guided by the annular internal air path 24 is applied to the tip of the internal air path 24. The plurality of air outlets 26 having the annular arrangement are ejected from the gas ejection G into the ejection area of the gas fuel G.
The gas fuel G jetting area (in other words, the jet gas fuel G
And a jet combustion air A).

Further, the inner air passage 24 penetrates in the radial direction,
The negative pressure area 21i around the fuel nozzle 21 in the fuel ejection pipe 22 is connected to the gas burner main body 4A at the outer opening 27o.
The four flue gas introduction pipes 27 that communicate with the outside are provided substantially uniformly distributed in the circumferential direction.

As shown in FIGS. 2 and 3, the upper end of the inner water pipe collecting tube 12 has four combustion exhaust gas outlets 2.
8, each of which is an outer opening 27o of the flue gas introduction pipe 27.
The guide body 29 is formed at the upper opening edge of each flue gas discharge port 28 so as to protrude toward the flue gas passage 16 and be inclined downward. The guide 29 extends the exhaust gas E flowing through the exhaust gas passage 16 from the exhaust gas outlet 28 to the outside of the heat exchanger HE. I will guide you.

Further, the annular wall 30 is attached to the inner water pipe collecting cylinder 1.
2, a position near the lower portion of the flue gas outlet 28,
An outer peripheral portion of the gas burner main body 4A is provided over an outer opening 27o of the flue gas introduction pipe 27 and a position between the air outlet 26, and a combustion exhaust gas introduction chamber (corresponding to an exhaust gas guide path) is provided above the combustion chamber 3. ) 31 are formed so as to be partitioned from the combustion chamber 3.

Then, as shown in FIGS. 2 and 3, a part of the combustion exhaust gas E flowing through the combustion exhaust gas passage 16 of the heat exchange section HE is guided by the attraction effect of the gas G ejected from the fuel nozzle 21. The flue gas introduction chamber 31 by the body 29
(Ie, the direction toward the negative pressure region 21i of the fuel nozzle 21), the exhaust gas outlet 28, the exhaust gas introduction chamber 31, and the exhaust gas introduction pipe 27.
Through the fuel nozzle 21 and the intake combustion exhaust gas E
To be mixed with the fuel G ejected from the fuel. At that time, the combustion exhaust gas flowing through the combustion exhaust gas introduction pipe 27 and the combustion air flowing through the internal air passage 24 are subjected to heat exchange using the pipe wall 27w of the combustion exhaust gas introduction pipe 27 as a heat transfer wall. The exhaust gas is appropriately cooled within a range that does not cause condensation of moisture in the combustion exhaust gas.

That is, the fuel nozzle 21 and the surrounding negative pressure area 21i allow the gaseous fuel G
(A so-called ejector) I that attracts (inhales) a part of the flue gas E flowing through the heat exchange section HE by the attraction (suction) action of the gas, and mixes the induced flue gas E into the gas fuel G. And the attraction part I is provided in the gas burner main body 4 </ b> A located in the heating chamber 2.
Further, inside the gas burner body 4A, the flue gas E induced by the attracting portion I and the combustion air A supplied to the flame forming portion 19 and the flue gas introducing pipe 2 for functioning as a heat transfer wall.
Cooling unit 3 for cooling by heat exchange through tube wall 27w
2 is provided. Further, an exhaust gas outlet 2 for extracting the combustion exhaust gas E from the heat exchange unit HE by the attraction of the attraction unit I.
8 is provided at a location near the flue gas discharge port 18, that is, at a location near the communication section with the exhaust path 5 in the heat exchange section HE.

That is, by providing the attraction unit I, a part of the combustion exhaust gas E having a reduced temperature flowing through the heat exchange unit HE is mixed with the supply gas fuel G in the flame forming unit 19.
The supply gas fuel G is burned in the flame forming section 19 while recirculating the combustion gas, whereby the combustion becomes slower than in the case where the recirculation of the combustion exhaust gas E is not performed. NO of generated combustion exhaust gas E in the chamber 3
x concentration is effectively reduced. Further, the recirculation of the flue gas E flowing through the heat exchange section HE, in which the temperature is lower than the flue gas E in the combustion chamber 3 to reduce the specific volume and the residual oxygen concentration is low. By
Compared with the case where the combustion exhaust gas E in the combustion chamber 3 is recirculated, slow combustion can be further promoted, and the NOx concentration can be effectively reduced.

[Second Embodiment] Hereinafter, based on FIG.
A second embodiment in which the present invention is applied to a multi-tube water pipe boiler will be described. Note that the same components as those of the first embodiment and components having the same operations are denoted by the same reference numerals to avoid redundant description, and description thereof is omitted.
Mainly, a configuration different from the first embodiment will be described. Second
In the embodiment, the body structure of the gas burner 4 is partially changed, and the other configuration is the same as that of the first embodiment.

The gas burner body 4A is different from the gas burner body 4A in that an outer annular gap f1 is formed between the air chamber 20 and the internal air path 24 inside the gas burner body 4A. A gas burner main body 4A is attached to the upper wall 1a of the can body 1 by forming an inner annular gap f2 between them and connecting the base ends of the annular gaps f1 and f2 to each other inside the gas burner main body 4A. Forming an annular combustion exhaust gas introduction passage 33 having an end annular opening 33a of the outer annular gap f1 opened to the combustion exhaust gas introduction chamber 31 as an introduction port, and an introduction passage end at the tip of the inner annular gap f2, Furthermore, the tip of the inner annular gap f2 is annularly opened in a negative pressure region 21i around the fuel nozzle 21 and a plurality of the plurality of holes allow the air chamber 20 to communicate with the internal air passage 24. The passing pipe 34, is provided in a state penetrating the outer annular gap f1 in the radial direction.

Then, a part of the combustion exhaust gas E flowing through the combustion exhaust gas passage 16 of the heat exchange section HE is introduced into the combustion exhaust gas introduction chamber 31 by the guide 29 by the attraction effect of the gas G ejected from the fuel nozzle 21. The flue gas discharge port 28 and the flue gas introduction chamber 3 are guided in a direction in which the flue gas is deflected in the direction (ie, the direction toward the negative pressure region 21i of the fuel nozzle 21).
1. Inhalation is performed through the end annular port 33a and the combustion exhaust gas introduction passage 33, and the intake combustion exhaust gas E is mixed with the gas fuel G ejected from the fuel nozzle 21. At that time,
Combustion exhaust gas flowing through the combustion exhaust gas introduction passage 33 and the communication pipe 3
4 and the combustion air flowing through the internal air passage 24, the pipe wall 34w of the communication pipe 34, the outer annular gap f1, and the internal air passage 2
4 and the cylindrical cylindrical wall 36 that partitions the internal air passage 24 and the inner annular gap f2 are each subjected to heat exchange as heat transfer walls. The mixture is cooled appropriately within a range that does not cause condensation.

That is, the fuel nozzle 21 and the surrounding negative pressure region 21i allow the gas fuel G
Of the combustion exhaust gas E flowing through the heat exchange section HE to form an induction section (so-called ejector) I for mixing the induced combustion exhaust gas E with the gas fuel G by the attracting action of the heat exchange section HE. The attraction part I is provided in the gas burner main body 4 </ b> A located in the heating chamber 2. Further, the flue gas E attracted by the attracting portion I is provided inside the gas burner main body 4A.
The pipe wall 34w of the communication pipe 34 that functions as a heat transfer wall with the combustion air supplied to the flame forming section 19, the cylindrical pipe wall 3
A cooling unit 32 for cooling by heat exchange through the cylindrical wall 5 and the cylindrical wall 36 is provided.

Accordingly, in the water tube boiler of the second embodiment, the area of the heat transfer wall for exchanging heat between the combustion exhaust gas and the combustion air in the cooling section 32 is increased as compared with the water tube boiler of the first embodiment. Therefore, the cooling capacity of the cooling unit 32 can be increased, whereby the specific volume of the induced flue gas is further reduced, and the amount (mass) of the flue gas attracted by the attracting unit I is further increased. Thus, the exhaust gas recirculation rate can be further increased.
Thereby, in the water tube boiler of the second embodiment, the NOx concentration of the generated combustion exhaust gas E in the combustion chamber 3 can be effectively reduced as compared with the water tube boiler of the first embodiment.

[Another Embodiment] Next, another embodiment will be described. (A) In the above embodiment, the heat exchange part HE is
The combustion exhaust gas E contains the inner water pipe collecting pipe 12 and the outer water pipe collecting pipe 1
3 has been exemplified so as to flow from the lower side to the upper side. However, as shown in FIGS. 6 and 7, and FIGS. E may be configured to flow in the combustion exhaust gas passage 16 between the inner water pipe collecting tube 12 and the outer water pipe collecting tube 13 in the circumferential direction.

The heat exchange part HE shown in FIGS. 6 and 7 is configured such that a part of the inner water pipe collecting cylinder 12 in the circumferential direction is
A flue gas supply port 17 is formed by opening in a slit shape over substantially the entire length of the lower part of the lower part, and the outer water pipe collecting tube 13 is positioned vertically opposite to the flue gas supply port 17 in a circumferential direction. The combustion exhaust gas discharge port 18 is formed by opening a slit. This heat exchange section HE
Then, the flue gas E is introduced into the flue gas passage 16 from the flue gas supply port 17 and the flue gas passage
6 is allowed to flow over substantially half the circumference on each side in the circumferential direction, and is discharged from the flue gas discharge port 18 to the exhaust path 5.

In this case, the wall 3 is positioned in the inner water pipe collecting tube 12 at a position facing the flue gas discharge port 18.
0 and two flue gas outlets 2
8 are arranged side by side in the circumferential direction. A guide body 29 is provided at the side edge of each flue gas outlet 28 on the lower side in the flue gas flow direction so as to be inclined so as to extend toward the flue gas flow passage 16 and to the upper side in the flue gas flow direction. do it,
By the guide body 29, a part of the flue gas E flowing through the flue gas passage 16 in the circumferential direction is led out of the flue gas outlet 28 to the outside of the heat exchanger HE (to the flue gas introduction chamber 31). I will be turning.

The heat exchange section HE shown in FIGS. 8 and 9 divides the flue gas passage 16 in the circumferential direction by a partition wall 37 over substantially the entire length in the vertical direction. The adjacent portion is opened in a slit shape over substantially the entire length of the portion below the wall 30,
A flue gas supply port 17 is formed, and a portion adjacent to the partition wall 37 on the side opposite to the flue gas supply port 17 side in the circumferential direction with respect to the partition wall 37 in the outer water pipe collecting cylinder 13 is vertically opened in a slit shape. , A combustion exhaust gas outlet 18 is formed. In this heat exchange section HE, the flue gas E is introduced from the flue gas supply port 17 into the flue gas passage 16,
The flue gas flow passage 16 is caused to flow through the circumferential direction substantially over the entire circumference, and is discharged from the flue gas discharge port 18 to the exhaust passage 5.

In this case, the inner water pipe collecting tube 12 is positioned above the wall 30 at a position adjacent to the partition wall 37 on the side opposite to the combustion exhaust gas supply port 17 in the circumferential direction, and A flue gas outlet 28 is formed.
A guide body 29 is provided at a side edge of the flue gas discharge port 28 on the lower side in the flue gas flow direction so as to extend in an inclined state extending toward the flue gas flow passage 16 and the flue gas flow direction upper side. Then, a part of the flue gas E flowing through the flue gas passage 16 in the circumferential direction is led out from the flue gas outlet 28 to the outside of the heat exchange section HE (with respect to the flue gas introduction chamber 31) by the guide body 29. I will guide you to turn.

(B) In the above embodiment, the gas fuel G supplied to the gas burner main body 4A is supplied to the flame forming section 19
In the above, the case where one attracting portion I is provided in the internal fuel passage 23 before being distributed to the plurality of fuel outlets 25 is illustrated. Instead of this, the attraction unit I may be individually provided for each of the plurality of fuel ejection ports 25 that eject the gas fuel G supplied to the gas burner main body 4 </ b> A in the flame forming unit 19. In this case, since the flue gas is attracted by the plurality of attracting portions I, the amount of flue gas attracted can be further increased, and the NOx reduction effect can be further improved.

(C) In the above embodiment, the case where the attraction portion I is provided in the gas burner main body 4A located in the heating chamber 2 has been described as an example, but it may be provided in the heating chamber 2 outside the gas burner main body 4A. good.

(D) In the above embodiment, the annular wall 30 may be omitted. Alternatively, the annular wall 30
The tip of which is the inner water pipe collecting tube 12 and the gas burner body 4
It may be extended from the inner water pipe collecting tube 12 to the combustion chamber 3 side in a state located at an intermediate position with respect to the outer peripheral portion of A. However, at high temperatures,
Moreover, in order to prevent the combustion exhaust gas in the combustion chamber 3 in a state where the residual oxygen concentration is relatively high from being attracted by the attracting portion I, the annular wall 30 forms the combustion exhaust gas introduction chamber 3.
It is preferred that 1 is formed in a compartment with the combustion chamber 3.

(E) In the above embodiment, the number of the exhaust gas outlets 28 and the number of the exhaust
The installation number of 7 can be changed suitably. For example, the flue gas outlet 28 and the flue gas introduction pipe 27 may be provided one by one, or five or more may be provided.

(F) The fluid heating device to which the present invention can be applied is not limited to the multi-tube water tube boiler exemplified in the above embodiment, but may be applied to various types of steam boilers and hot water boilers. Can be applied.
Further, the present invention can also be applied to a regenerator for heating and regenerating a rare absorbent in an absorption type cold / hot water generator. The fluid to be heated may be a liquid or a gas other than water, and the structure of the heat exchange unit HE for heating the fluid to be heated with the combustion exhaust gas is also shown in the above-described embodiment and FIGS. It is not limited to the structure of another embodiment.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a water tube boiler according to an embodiment.

FIG. 2 is a partially cutaway perspective view of a heat exchange unit of the water tube boiler according to the embodiment.

FIG. 3 is a longitudinal sectional view showing a gas burner main body of the water tube boiler according to the first embodiment.

FIG. 4 is a cross-sectional view of the water tube boiler according to the first embodiment.

FIG. 5 is a longitudinal sectional view showing a gas burner main body of a water tube boiler according to a second embodiment.

FIG. 6 is a perspective view of a heat exchange unit of a water tube boiler according to another embodiment.

FIG. 7 is a cross-sectional view of a heat exchange unit of a water tube boiler according to another embodiment.

FIG. 8 is a perspective view of a heat exchange unit of a water tube boiler according to another embodiment.

FIG. 9 is a cross-sectional view of a heat exchange unit of a water tube boiler according to another embodiment.

FIG. 10 is a longitudinal sectional view of a fluid heating device showing a comparative example.

FIG. 11 is a longitudinal sectional view of a fluid heating device showing a conventional example.

[Explanation of symbols]

 2 Heating chamber 3 Combustion chamber 4A Gas burner main body 5 Exhaust path 19 Flame forming part 28 Exhaust gas outlet 27w, 34w, 35, 36 Heat transfer wall 29 Guide 31 Exhaust gas induction path 32 Cooling part HE Heat exchange part I Induction part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor: Tetsu Minami 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture F-term in Osaka Gas Co., Ltd. (reference) 3K017 CA06 CB09 CE03 3K019 AA06 BA02 BB03 BB04 BD04 BD09 CC04 3K065 TA01 TC01 TD05 TE01 TG02 TH05 TH11 TL03 TL04 TM02 TM03 TN07

Claims (5)

[Claims] 1. A combustion chamber facing a flame forming part of a gas burner main body, and a heat exchange part for heating a fluid to be heated by combustion exhaust gas generated in the combustion chamber, from the combustion chamber to the heat exchange part. A fluid heating device provided adjacent to a heating chamber so that the combustion exhaust gas flows, and an exhaust path for guiding the combustion exhaust gas discharged from the heat exchange unit is provided outside the heating chamber, Due to the attraction effect of the gas fuel supplied to the flame forming unit, an attraction unit that attracts a part of the combustion exhaust gas flowing through the heat exchange unit and mixes the induced combustion exhaust gas with the gas fuel is provided in the heating chamber. Fluid heating device provided. 2. The fluid heating device according to claim 1, wherein an exhaust gas induction passage for inducing combustion exhaust gas from the heat exchange unit by an attraction action of the induction unit is formed so as to be separated from the combustion chamber. 3. The fluid heating device according to claim 1, further comprising a guide body for deflecting and guiding the combustion exhaust gas flowing through the heat exchange unit in a direction toward the attraction unit. 4. A cooling unit is provided inside the gas burner main body for exchanging heat with the combustion air supplied to the flame forming unit through a heat transfer wall to cool the combustion exhaust gas induced by the induction unit. The fluid heating device according to claim 1. 5. An exhaust gas outlet for drawing out combustion exhaust gas from the heat exchange unit by an attraction action of the attraction unit is provided at a position near a communication portion with the exhaust path in the heat exchange unit. The fluid heating device according to any one of claims 1 to 4.