JPH07243605A - Boiler - Google Patents

Abstract

PURPOSE:To achieve miniaturization of the whole of a boiler as a system together with ensurance of high efficiency and low cost by increasing the degrees of freedom of a heat transfer surface in the boiler and miniaturizing a can structure, and further decreasing the capacity of auxiliary instruments such as a fan. CONSTITUTION:There are provided a boiler can structure K including at least a radiation heat transfer surface therein, a combustion apparatus 6 disposed facing the radiation heat transfer surface of the can structure, a flue 12 provided in the vicinity of the combustion apparatus 6 for exhausting waste gas from the inside of the can structure K, a wind box 5 provided on the can structure K for rectifying combustion air from fan means and supplying it to the combustion apparatus 6, and a heat exchanger H provided on the wind box 5 for heat exchanging the waste gas from the flue 12 and combustion air in the wind box 5. Further the heat exchanger H is constructed by defining the interior of the wind box 5 to a combustion air introduction passage 16 and a waste gas exhaust passage 17 by making use of a partition member serving as a heat exchange surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water tube boiler such as a once-through boiler, a natural circulation type water tube boiler and a forced circulation type water tube boiler, and various boilers such as a furnace tube boiler, a smoke tube boiler, and a round boiler such as a furnace tube smoke tube boiler. The present invention relates to a boiler having a novel heat recovery mechanism, which is suitable for application to.

[0002]

Boilers are generally used to heat water or other heat transfer liquid by using hot gas generated by a combustion device as a heating source to obtain steam or hot water. The so-called water tube boiler, which uses a large number of water tubes (heat transfer tubes) instead of round boilers such as furnace tube boilers, smoke tube boilers, furnace tube smoke tube boilers, etc. Has been done. Water pipe boilers of this type include a once-through boiler, a natural circulation type water pipe boiler, a forced circulation type water pipe boiler, and the like, and these have a heat transfer section configured by one or a plurality of water pipes. The hot gas referred to here is
Including a relatively high temperature gas body containing combustion flame and combustion gas,
Further, the combustion gas includes the gas until the combustion is completed.

[0003]

The above-mentioned water tube boiler has a structure in which the boiler gas can be recovered as much as possible from the hot gas generated by the combustion equipment in the boiler can body to improve the boiler efficiency in the can body. ing.

Therefore, in such a boiler,
To ensure as large a heat transfer area as possible in the boiler can, and to use the heat effectively by using a combustion device that generates a larger amount of heat, the gas between the combustion chamber and the exhaust gas outlet of the boiler can It has a can structure in which the passage is divided into a plurality of water pipes. Then, in the combustion chamber, heat recovery is mainly performed by radiant heat transfer from the hot gas generated by the combustion device, and in the gas passage between the combustion chamber and the exhaust gas outlet, heat recovery is mainly performed by contact heat transfer. The boiler is configured to recover as much heat as possible from the hot gas.

By the way, generally, the heat transfer portion that receives the radiant heat transfer from the above-mentioned hot gas (hereinafter, referred to as the radiant heat transfer part) has a large amount of heat transfer and also comes into contact with the hot gas led out from the combustion chamber. The heat transfer portion that receives heat transfer (hereinafter referred to as the contact heat transfer portion) has a smaller amount of heat transfer than the radiant heat transfer portion. However, in the water tube boiler as described above, since the water tube of the radiant heat transfer section and the water tube of the contact heat transfer section both have the same pressure resistance and heat resistance strength, there is a difference in the amount of heat transfer between the water tubes. Remarkably, in terms of the amount of heat recovered in the boiler canister and the heat exchange efficiency, the heat transfer surface was inadvertently increased, resulting in an expensive and less flexible heat transfer surface. Also,
In order to increase the amount of heat recovered in the contact heat transfer section, it is necessary to enlarge the heat transfer surface of this section or to narrow the flow gap of the hot gas in the contact heat transfer section to increase the flow rate. However, in the case of such a method, since the pressure loss of the boiler can is increased, an increase in the capacity of the blower is unavoidable, and the use of such a blower also causes a significant increase in cost.

Therefore, the problem to be solved by the present invention is to increase the degree of freedom of the heat transfer surface and downsize the can body in a conventional boiler, and further to reduce the capacity and cost of auxiliary equipment such as a blower. To reduce the overall size of the boiler as a system and achieve higher efficiency.

[0007]

The present invention has been made to solve the above-mentioned problems, and its concrete means are as follows.
A boiler can body having at least a radiant heat transfer surface inside, a combustion device arranged so as to face the radiant heat transfer surface of the boiler can body, and exhaust gas from the boiler can body provided near the combustion device. A flue gas for discharging, a wind box provided in the boiler can for rectifying the combustion air from the blowing means and supplying it to a combustion device, and an exhaust gas from the flue gas provided in the wind box. A first feature of the boiler is a heat exchanger for exchanging heat with the combustion air in the wind box, wherein the heat exchanger has a partition wall member inside the wind box for introducing the combustion air and the heat exchanger. A second feature is that the partition wall is divided into an exhaust gas exhaust passage communicating with a flue and the partition wall member serves as a heat exchange surface. The third feature is that the heat exchange surface is projected toward the exhaust gas discharge passage, and the fourth feature is that the combustion device incorporates heat recovery means from the waste gas. is there.

[0008]

In the boiler according to the present invention, first, heat is recovered from the hot gas generated by the combustion device on the radiant heat transfer surface defining the combustion chamber, and the exhaust gas discharged from the combustion chamber is passed through the flue. The heat is recovered from the exhaust gas to the combustion air in the wind box through the above, and heat is recovered from the combustion air to generate hot gas by the combustion device.

[0009]

1 is a longitudinal sectional view schematically showing a first embodiment in which the present invention is applied to a multi-tube once-through boiler which is a kind of water tube boiler. Incidentally, in this first embodiment,
Although it is a steam boiler, this can structure can be similarly applied to a hot water boiler and a heat medium boiler using a heat medium liquid as a fluid to be heated instead of water.

First, the boiler can body (K) will be described. In this boiler can body (K), a large number of water pipes (1) are arranged in an annular shape and arranged as an annular water pipe array (2).
(2) is arranged between a pair of upper headers (3) and lower headers (4) forming an annular shape, and the upper and lower ends of the water pipe (1) are respectively connected to the upper header (3) and the lower header (4). ) Is connected to communicate with. In the above-mentioned ring-shaped water pipe array (2), a space between the adjacent water pipes (1) is closed so as to substantially prevent the flow of hot gas, or a closing member (not shown) that closes the space. ) Is provided.
A boiler outer wall (8) surrounding the water pipe array (2) is provided outside the annular water pipe array (2). At the upper center of the upper header (3), a wind box (5) that rectifies the combustion air from a blower (not shown) and supplies it to the combustion device (6).
And a combustion device (6) is provided on the inner side (central part), whereby the inside of the annular water pipe array (2) is defined as the combustion chamber (7). In this can structure, the water pipe (1) is
Only the combustion chamber (7) is constituted, and the water pipe (1) facing the combustion chamber (7) most efficiently transfers heat from the hot gas generated by the combustion device (6).

Further, on the lower surface of the upper header (3) and the upper surface of the lower header (4), a refractory layer (9) for protecting a fixed portion (generally by welding) of the water pipe (1) is provided. ),(Ten)
The refractory layer (10) on the lower header (4) side has a shape that closes the central part of the annular lower header (4) to prevent hot gas from flowing out. . Also,
Between the central space of the annular upper header (3) and the combustion device (6) is a flue (12) for discharging hot gas as exhaust gas to the outside of the system.

The wind box (5) is provided with a heat exchanger (H) for exchanging heat between the combustion air flowing inside and the exhaust gas from the flue (12).

With such a configuration, the combustion device
The hot gas generated in the combustion chamber (7) by (6) is
The radiant heat is transferred to the water pipe (1) defining the combustion chamber (7) to heat the water (or the heat transfer liquid) in the water pipe. Then, the hot gas is mixed with the upper header (3) and
After flowing into the heat exchanger (H) in the wind box (5) through the flue (12) between (6), directly from a discharge means (not shown) such as a chimney or preheating the water supply. It is indirectly discharged as exhaust gas via a economizer (not shown). When this exhaust gas passes through the heat exchanger (H) in the wind box (5), heat is exchanged with the combustion air. Therefore, since the combustion air is heated, the heat of the exhaust gas can be recovered into the combustion chamber (7) again, and this recovery position is at the inlet of the combustion air to the combustion chamber (7). The flue that is the closest and is the exit from the combustion chamber (7) for the exhaust gas.
Since it is performed in the wind box (5) closest to (12), it does not waste heat from exhaust gas to the outside of the system,
The amount of heat transferred to the combustion air can be efficiently performed.

Further, since the combustion air is heated by the exhaust gas, the heat wasted as exhaust heat can be effectively used and the combustion state can be stabilized. In this case, in the case of the combustion device using the liquid fuel, there is an advantage that the flowability and the ignitability of the liquid are further improved.
In particular, in the case of a combustion device that vaporizes and burns liquid fuel, vaporization can be performed completely and efficiently, so that there is an advantage that the fuel can be efficiently burned without waste.

That is, in the above embodiment, only the radiant heat transfer section having the highest heat transfer efficiency has a heat resistant and pressure resistant structure, and the contact heat transfer section having a low heat transfer efficiency like the conventional boiler is constructed in the can body. Instead, it is configured to recover by combustion air, so it is not necessary to have a heat-resistant and pressure-resistant structure up to the contact heat transfer part with a low heat recovery rate as in conventional boilers, and the amount of heat transfer for each water pipe Since there is no difference in the amount of heat transfer between the water tubes, the heat transfer surface of the boiler can be reduced. In other words, the amount of recovered heat can be improved with a narrower heat transfer surface area, and therefore the size can be reduced relative to the capacity. Further miniaturization can be achieved by eliminating the contact heat transfer section. Furthermore, by eliminating the contact heat transfer section, the capacity of the air blower can be reduced, so that the size can be reduced, and the boiler system can be greatly downsized and highly efficient.

FIG. 2 is a longitudinal sectional view schematically showing a second embodiment in which the present invention is applied to a can body of another type of a multi-tube type once-through boiler which is a kind of water tube boiler, like the above-mentioned embodiment. The constituent elements corresponding to those of the first embodiment are designated by the same reference numerals and symbols, and detailed description thereof will be omitted. Although the steam boiler is also used in the second embodiment, this can structure can be similarly applied to a hot water boiler and a heat medium boiler that uses a heat medium liquid as a fluid to be heated instead of water.

Boiler can body (K) in this second embodiment
This boiler can body (K) is provided with a second upper header (13) above the upper header (3), and between the upper header (3) and the second upper header (13). Multiple connecting pipes
Connected by (14). The number of the connecting pipes (14) is equal to or less than the number of water pipes connecting the upper header (3) and the lower header (4). This second upper header (13) is a second upper header located above the steam generated in the upper header (3) via the connecting pipe (14).
By introducing the liquid into (13), it is possible to prevent the mixing of the liquid droplets and prevent the decrease in the dryness of the steam.

Further, the wind box (5) is mounted above the second upper header (13), and a combustion device (6) is provided in the center of the inside of the wind box (5) to prevent fire. Regarding the material layers (9) and (10), the refractory layer (9) on the upper header (3) side is the second upper header (13) and the connecting pipe (1).
The refractory layer (10) on the lower header (4) side is formed so as to be buried therein, and the central portion of the lower header (4) is formed in order to prevent outflow of hot gas as in the first embodiment. Has a shape to close.

The upper header (3) and the second upper header
A flue (12) for discharging hot gas as exhaust gas to the outside of the system is provided between the central space of (13) and the combustion device (6), but in the second embodiment, The flue (12) is formed by molding the refractory layer (9) as follows. That is, in the refractory layer (9) between the upper header (3) and the second upper header (13), the opening for the combustion chamber (7) is formed in a tapered shape, and the opening and the wind box (5) are formed. ) Is a narrowed portion.

By thus tapering the opening of the refractory layer (9), the hot gas from the combustion device (6) effectively spreads in the combustion chamber (7), and the refractory material is Layer (9)
Reflects the radiant heat of the hot gas into the combustion chamber (7), increasing the efficiency of radiant heat transfer. Furthermore, by providing a narrowed portion in the refractory layer (9), the hot gas ejected from the combustion device (6) also has the effect of sucking the hot gas in the combustion chamber (7) toward the flue (12). Demonstrate. Also in the can body structure of this embodiment, the water pipe (1) constitutes only the combustion chamber (7), and the water pipe (1) facing this combustion chamber (7) is formed by the combustion device (6). The heat transfer from the generated hot gas is most efficiently performed.

In the second embodiment, the combustion air and the flue which are provided in the wind box (5) and circulate inside the wind box (5) are provided.
Heat exchanger (H) that exchanges heat with the exhaust gas from (12)
Has the following configuration. That is, the inside of the wind box (5) is divided into two or more spaces by an appropriate partition member, and at least one space is used as a combustion air introduction passage (16), and the remaining space is a flue (12). It has a structure in which the partition wall member (15) is formed as a heat exchange surface by partitioning with the exhaust gas exhaust passage (17) connected to the.

More specifically, in the illustrated second embodiment, the wind box (5) has a cylindrical main body portion (5a) provided so as to be substantially coaxial with the can body (K). A connecting pipe portion (5b) provided on the side of the main body portion (5a), and the main body portion (5a) is formed by a first partition member (15a) disposed inside the main pipe portion (5a) at an appropriate interval. , Connection pipe part
The (5b) is divided into two spaces by the second partition member (15b) arranged inside the (5b) at an appropriate interval. The space between the main body portion (5a) and the first partition member (15a) communicates with the space between the connection pipe portion (5b) and the second partition member (15b), and this space is It serves as an introduction passage (16) for the combustion air. Therefore, a combustion air supply means (F) is connected to the connection pipe portion (5b) side of the introduction passage (16),
The combustion device (6) is connected to the body part (5a) side. On the other hand, the space inside the first partition member (15a) is the second partition member (15b).
Communicates with the inner space of the exhaust gas, and this space serves as an exhaust gas discharge passage (17) connected to the flue (12). Therefore, an exhaust means such as a chimney is directly connected to the connection pipe part (5b) side of the discharge passageway (17) or indirectly through a heat recovery means such as an economizer.

Here, the procedure for attaching the combustion device (6) to the wind box (5) is as follows:
a) so as to open in the introduction passage (16) for the combustion air,
The combustion device (6) is attached to the first partition member (15a).
The fuel pipe (6b) is the main part (5a) of the windbox (5).
From the outside by connecting to the combustion device (6) through the combustion air introduction passage (16).

With the above structure, the first partition member (15
a) and the second partition member (15b) separates the introduction passage (16) for the combustion air and the exhaust passage (17) for exhaust gas that is connected to the flue (12), and each passage (16) (17) The structure is such that it functions as a heat exchange surface between the combustion air flowing through the exhaust gas and the exhaust gas, and the heat exchange procedure is the same as in the first embodiment, so the explanation is omitted.

As described above, the exhaust gas exhaust passage (1
It is preferable to position the introduction passage (16) for the combustion air on the outside of 7) in order to increase the heat recovery rate, and by arranging in this way, the introduction passage (16) for the combustion air is provided.
Since it can be used as an insulation layer, the wind box (5)
It is also preferable from the viewpoint of safety, since it is possible to prevent the outer surface of the material from becoming highly heated.

Further, in the second embodiment, the first
Third partition member (15) in which the partition member (15a) is projected from the air introduction passage (16) toward at least the exhaust gas discharge passage (17).
c) is provided. The third partition member (15c) projects from the introduction passage (16) toward the exhaust gas discharge passage (17), thereby expanding the heat exchange surface between the combustion air and the exhaust gas. Since the 3 partition member (15c) protrudes toward the flue (12) and reaches the exhaust gas region where the temperature is relatively high, the amount of heat recovered from the exhaust gas can be increased,
Increase boiler efficiency. As shown in the drawing, the third partition wall member (15c) has a substantially bottomed cylindrical shape, and the combustion device (6)
A plurality of them are arranged at appropriate intervals around the. Each third
The partition member (15c) is partitioned by a partition member (20) along the axial direction so as to form a substantially U-shaped reciprocating flow passage therein. Further, the partition member (20) extends over the position where the third partition member (15c) is arranged in the introduction passage (16) and extends inside the wind box (5) and the first partition member (15a).
Therefore, all the combustion air from the blower means is passed through the substantially U-shaped reciprocating flow passage formed inside each third partition member (15c) to form the combustion device (6). Flow into.
Regarding the formation of the substantially U-shaped reciprocating flow path, the partition member (20) for partitioning the inside of the third partition member (15c) in the axial direction.
It is not necessary to use, and the third partition member (15c) can be easily constructed by forming it into a U-shape.

Further, in the second embodiment, a cylindrical rectifying member (21) surrounding the third partition member (15c) at an appropriate interval is provided at the upper end opening of the refractory layer (9). The rectifying member (21) is provided so that the exhaust gas from the flue (12) is surely brought into contact with the third partition member (15c) to allow heat exchange.

FIGS. 3 and 4 are longitudinal sectional views schematically showing the third and fourth embodiments, respectively, in which the present invention is applied to a single-tube type boiler, which is a kind of water tube boiler, so-called mono-tube type boiler. In the figure, the components corresponding to those of the first and second embodiments are designated by the same reference numerals and symbols, and detailed description thereof will be omitted. The configurations shown in the third and fourth embodiments are often used in so-called heat medium boilers that heat a heat medium liquid, but this can structure has an ordinary boiler (steam boiler, hot water) using water as a heating fluid. The same can be applied to the boiler).

In the third embodiment shown in FIG. 3, the basic structure of the can body corresponds to the heat transfer tube (corresponding to the water tube of the first and second embodiments. In the following embodiments, (1) is spirally wound to form a tube-shaped heat transfer tube wall (30), and the combustion device (6) is arranged facing the innermost peripheral space of this wall. By making the portion into the combustion chamber (7), the heat transfer tube portion facing this combustion chamber (7) is used as the radiant heat transfer portion. Also in this third embodiment, as in the above-mentioned respective embodiments, in the wind box (5),
By recovering heat from exhaust gas to combustion air,
It is possible to improve the thermal efficiency without constructing a contact heat transfer section with low heat transfer efficiency in the can as in a conventional boiler.
Moreover, since the heat transfer surface load of each heat transfer tube is uniform, there is no significant difference in the heat transfer amount of each heat transfer tube, the heat transfer surface of the boiler is reduced, and the boiler system is significantly downsized. High efficiency can be achieved.

Generally, in a conventional heat medium boiler, it is necessary to prevent the heat medium liquid from deteriorating at a high temperature, so that the heat transfer surface load on the heat transfer tube (the amount of heat received per unit area on the heat receiving surface of the heat transfer tube). However, since the heat transfer surface load is set lower than that of an ordinary boiler that heats water, the temperature of the hot gas flowing out from the radiant heat transfer section is low and the contact heat transfer section is installed. Even when the heat recovery is performed by using the conventional boiler, the amount thereof is smaller than that of the normal boiler, and the conditions are stricter than those of the normal boiler. However, by adopting the configuration as in the third embodiment, the heat can be recovered more effectively than the can body of the type having the contact heat transfer section, so that the can body structure can be simplified, and in particular, It is suitable for such a heat medium boiler.

In the fourth embodiment shown in FIG. 4, the basic structure of the can body is obtained by spirally winding the heat transfer tube (1) into a double tube-shaped heat transfer tube wall having different winding diameters. By forming (31) and (32) and arranging them so that the combustion device (6) faces the innermost peripheral space and making this space part the combustion chamber (7), the combustion chamber (7) is formed. The heat transfer tube portion facing each other is used as a radiant heat transfer section, and the space between the double cylindrical heat transfer tube portions serves as a flow gap of the hot gas from the combustion chamber (7), so that the heat transfer tube facing this gap (33) is transferred. The heat pipe part is the contact heat transfer part.

In the boiler can body shown in the fourth embodiment, the flow of the hot gas from the combustion chamber (7) to the gap (33) is provided in the gap (34) provided below the inner heat transfer tube wall (31). Done by a gap (33)
The exhaust gas is distributed from the flue to the flue (12) by a large number of flue inlets (12 ') radially provided in the refractory layer (9). Also in the fourth embodiment, as in the third embodiment, in the wind box (5),
By recovering heat from exhaust gas to combustion air,
The thermal efficiency can be improved. The boiler can body shown in the fourth embodiment is of a so-called conventional type in which a contact heat transfer part is provided in order to increase the amount of heat recovery, but by applying the present invention, The heat recovery amount can be increased, and the fuel can be saved, so that the thermal efficiency is increased.

In each of the above embodiments, in order to further recover heat from the exhaust gas discharged from the boiler and improve the thermal efficiency, for example, a shell-and-tube type or a plate type is provided downstream of the exhaust gas discharge passageway (17). Of the fixed type heat exchanger, the air preheater using the heat storage type heat exchanger equipped with ceramic honeycomb or corrugated type heat storage body, for example, the fixed type heat exchanger of tube type, shell & tube type, etc. The water supply preheater described above may be connected, whereby the efficiency of the boiler can be further improved.

In the above description, the case where the present invention is applied to a multi-tube once-through boiler as an example of a water tube boiler has been described. However, in the present invention, another type of water tube boiler, that is, a natural circulation type boiler is used. It can be easily applied to a water tube boiler and a forced circulation type water tube boiler.
This is because the difference between these boilers lies in the circulation ratio of water (or heat transfer liquid) in the can and whether or not this circulation is forcibly performed using a liquid feeding means such as a circulation pump. This is because the cans themselves have substantially the same structure.

Furthermore, the present invention can be similarly applied to round boilers such as a furnace tube boiler, a smoke tube boiler, and a furnace tube smoke tube boiler, in addition to the above water tube boiler. That is, according to the present invention, the flue (1) that draws the exhaust gas from the combustion chamber (7) out of the combustion chamber (7) close to the wind box (5)
A boiler can that can form 2) can be easily implemented by disposing the heat exchanger (H) in the wind box (5).

[0036]

As described above, according to the present invention, heat is recovered from the hot gas generated by the combustion device on the radiant heat transfer surface that defines the combustion chamber, and the exhaust gas discharged from the combustion chamber is discharged. By flowing into the wind box through the flue, to perform heat recovery from the exhaust gas to the combustion air in this wind box, because it is a configuration to generate hot gas by the combustion device by the heat recovered combustion air, The thermal efficiency can be improved without constructing a contact heat transfer section with low heat transfer efficiency as in a conventional boiler, and moreover, the heat transfer surface load of each heat transfer tube becomes uniform,
There is no significant difference in the amount of heat transfer between the heat transfer tubes, the heat transfer surface of the boiler can be reduced, and the boiler system can be significantly downsized and highly efficient. Furthermore, by eliminating the contact heat transfer section, the capacity of the blowing means can be reduced,
From this point as well, the size can be reduced, and the boiler system can be greatly downsized and highly efficient.

[Brief description of drawings]

FIG. 1 is a vertical sectional view schematically showing a first embodiment in which the present invention is applied to a multi-tube once-through boiler which is a type of water tube boiler.

FIG. 2 is a longitudinal sectional view schematically showing a second embodiment in which the present invention is applied to a multi-tube once-through boiler which is a type of water tube boiler.

FIG. 3 is an enlarged cross-sectional view schematically showing the structure of the wind box portion of the second embodiment, taken along the line III-III of FIG.

FIG. 4 is a vertical cross-sectional view schematically showing a third embodiment in which the present invention is applied to a monotube once-through boiler which is a type of water tube boiler.

FIG. 5 is a vertical sectional view schematically showing a fourth embodiment in which the present invention is applied to a monotube once-through boiler which is a type of water tube boiler.

[Explanation of symbols]

 (K) Boiler can (H) Heat exchanger (1) Water pipe (heat transfer pipe) (5) Windbox (5a) Windbox body (5b) Windbox connecting piping (6) Combustor (7) Combustion chamber (12) Flue (15) Partition member (15a) First partition member (15b) Second partition member (15c) Third partition member (16) Introduction passage (combustion air introduction passage) (17) Discharge passage (Exhaust gas discharge passage)

Claims (4)

[Claims] 1. A boiler can body (K) having at least a radiant heat transfer surface therein, a combustion device (6) arranged so as to face the radiant heat transfer surface of the boiler can body (K), and the combustion. A flue (12) provided near the device (6) for discharging exhaust gas from the inside of the boiler can body (K), and a combustion air from a blower provided at the boiler can body (K). A wind box (5) that rectifies the gas and supplies it to the combustion device (6), and exhaust gas from the flue (12) provided in the wind box (5) and combustion air in the wind box (5). And a heat exchanger (H) for exchanging heat of the boiler. 2. The heat exchanger (H) is provided with an exhaust gas discharge passage, which is connected to a combustion air introduction passage (16) and the flue (12) by a partition member (15) inside the wind box (5). (17)
The boiler according to claim 1, characterized in that the partition member (15) has a structure in which the partition member (15) serves as a heat exchange surface. 3. The partition member (1) of the wind box (5)
5) from the air introduction passage (16) to at least the exhaust gas discharge passage
The boiler according to claim 2, wherein the heat exchange surface is projected toward the (17). 4. The boiler according to claim 1, wherein the combustion device (6) has a means for recovering heat from exhaust gas therein.