JP2005274028A - Combustion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop a combustion device having improved heat efficiency without excessively increasing its whole shape. <P>SOLUTION: The combustion device 1 comprises a canned body 2, a primary heat exchanger 3 (a sensible heat recovery heat exchanger), and a combustion burner 5 (a combustion means) and a blowing means 6. A secondary heat exchanger 7 (a latent heat recovery heat exchanger) has a plurality of heat receiving tubes 18 arranged in parallel between a pair of headers 16, 17. In this embodiment, the heat receiving tubes 18 are mounted on a tube plate 20 on which the heat receiving tubes 18 are mounted. The heat receiving tubes 18 are bare tubes which are arranged in the direction of crossing the flow of combustion gas. The stack number of the receiving tubes 18 in the vertical direction is less than the stack number thereof in the lateral direction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a combustion apparatus, and more particularly to a combustion apparatus provided with a heat exchanger for recovering latent heat.

Combustion devices that burn gas or liquid fuel are often used as heat sources for water heaters, bath devices, and the like. In recent years, from the viewpoint of energy saving and environmental protection, a combustion apparatus having higher thermal efficiency than the conventional combustion apparatus is desired. In order to solve such a demand, a combustion apparatus provided with a plurality of heat exchangers and a combustion apparatus called a latent heat recovery type combustion apparatus capable of recovering latent heat in addition to sensible heat of combustion gas have been proposed.
A conventional latent heat recovery combustion apparatus has a configuration as disclosed in, for example, Patent Document 1 below, and mainly includes a sensible heat recovery heat exchanger that recovers sensible heat of combustion gas, and mainly combustion gas. It is provided with a latent heat recovery heat exchanger that recovers the latent heat (recovers the remaining sensible heat).
JP-A-11-148642

FIG. 11 is a model diagram of the combustion apparatus described in Patent Document 1. In the latent heat recovery combustion apparatus described in Patent Document 1, a finned tube 100 is used as a latent heat recovery heat exchanger as shown in FIG. Here, the finned tube 100 is a tube in which fins are welded around the heat receiving tube, and is also referred to as a fin tube.
In the prior art, the finned tube 100 is directly inserted into the combustion gas passage 101. That is, in the prior art, the combustion gas flow path 101 is configured by the wall body 102 as shown in FIG. 11, and the finned tube 100 is inserted into the combustion gas flow path 101 formed by the wall body 102. In the prior art, the finned tubes 100 in the combustion gas passage 101 are arranged in series as shown in the figure.

The conventional latent heat recovery type combustion apparatus has higher thermal efficiency than a normal combustion apparatus. However, further improvement in thermal efficiency is desired in the market.
Here, as a measure for improving the thermal efficiency, it is conceivable to increase the heat exchange efficiency of the latent heat recovery heat exchanger by lengthening the entire length of the finned tube 100 inserted into the combustion gas flow path 101. However, when the overall length of the finned tube 100 is increased, the volume occupied by the latent heat recovery heat exchanger increases, which has the disadvantage of increasing the overall shape of the combustion apparatus.

  Accordingly, an object of the present invention is to develop a combustion apparatus that can further improve thermal efficiency without excessively increasing the overall shape.

  As a result of diligent research to solve the above-mentioned problems, it has been found that the influence of the drain is large as a factor for reducing the heat exchange efficiency of the heat exchanger for recovering latent heat. That is, since the latent heat recovery type combustion apparatus recovers even the latent heat of the combustion gas, the water vapor contained in the combustion gas is liquefied and a large amount of drain is generated. Since this drain is generated on the surface of the heat exchanger for recovering latent heat, the combustion gas comes into contact with the drain, and the thermal energy of the combustion gas is taken away by the drain. Therefore, the heat of the combustion gas is consumed for re-evaporating the drain, and the thermal energy contributing to the temperature rise of the hot water in the heat exchanger is reduced.

In addition, if a large amount of drain adheres to the surface of the latent heat recovery heat exchanger, the drain hinders the transfer of heat into the latent heat recovery heat exchanger, thereby greatly reducing the heat exchange efficiency.
It was also found that it is desirable to use a heat exchanger with a structure in which a large number of heat receiving tubes are arranged in parallel in order to ensure a large contact area with the combustion gas without excessively increasing the overall shape. . A heat exchanger having a structure in which a large number of heat receiving tubes are arranged in parallel is generally difficult to downsize, and there is no example of adopting it as a heat exchanger for recovering latent heat of a combustion apparatus. In general, a stack type heat exchanger is often used for a device that requires a compact and highly efficient heat exchanger, but according to the study of the present inventors, the stack type heat exchanger is a drain. Therefore, a heat exchanger having a structure in which a large number of heat receiving tubes are arranged in parallel is more suitable for use as a heat exchanger for recovering latent heat of a combustion apparatus.

  Further, a heat exchanger having a structure in which a large number of heat receiving tubes are arranged in parallel has a higher degree of design freedom than a stacked heat exchanger. In other words, heat exchangers with a structure in which a large number of heat receiving tubes are arranged in parallel can be changed in external shape design by appropriately selecting the length and vertical and horizontal arrangement of the tubes, and are designed to match the combustion equipment. Easy to do. For this reason, it is difficult for an extra air gap to be generated in the combustion apparatus, and as a result, it contributes to downsizing of the combustion apparatus.

  The invention according to claim 1 based on the above-described knowledge includes a combustion means, a sensible heat recovery heat exchanger that recovers sensible heat of combustion gas generated mainly in the combustion means and heats hot water, and the sensible heat recovery. A heat exchanger for latent heat recovery, which is disposed downstream of the combustion gas flow path with respect to the heat exchanger for heat and mainly recovers the latent heat of the combustion gas and heats the hot water, and passes through the heat exchanger for latent heat recovery In the combustion apparatus piped so that the hot and cold water flows to the sensible heat recovery heat exchanger, the latent heat recovery heat exchanger is composed of a large number of heat receiving tubes arranged in parallel. Device.

  In the combustion apparatus of the present invention, a heat exchanger for latent heat recovery in which a large number of heat receiving tubes are arranged in parallel is employed. Therefore, in the combustion apparatus of the present invention, there are many opportunities for contact between the combustion gas and the heat receiving pipe, and the thermal efficiency is high.

  The invention according to claim 2 is the combustion apparatus according to claim 1, wherein the heat receiving pipe of the heat exchanger for recovering latent heat is a bare pipe.

In heat exchangers that exchange heat between gas and liquid, finned heat receiving tubes are generally used for the purpose of increasing the chance of contact with combustion gas and the like. In contrast, in a heat exchanger that performs heat exchange between gas and liquid, bare tubes are rarely used as heat receiving tubes.
However, according to the study by the present inventors, it has been found that a sufficiently high thermal efficiency can be obtained even when a bare tube without fins is used as the heat receiving tube of the latent heat recovery heat exchanger.
That is, since the latent heat recovery type combustion apparatus recovers even the latent heat of the combustion gas, the water vapor contained in the combustion gas is liquefied and a large amount of drain is generated. In the heat exchanger for recovering latent heat employed in the prior art, the fins are provided on the heat receiving pipe, so that the drain adheres to the fins and a drain film is formed on the heat receiving pipe.
Therefore, most of the heat energy of the combustion gas is consumed for re-evaporating the drain, and the heat energy contributing to the temperature rise of the hot water in the heat exchanger is reduced. In particular, when the drain is accumulated between the fins, the drain is greatly surrounded around the heat receiving tube, and the heat exchange efficiency is significantly reduced.
Further, in the heat exchanger for latent heat recovery employed in the prior art, it is difficult to remove the drain due to the fins in the heat receiving pipe, and the heat exchange efficiency is lowered.
On the other hand, in the present invention, since the heat receiving pipe is a bare pipe, the drain is smoothly detached, the drain film formed on the heat receiving pipe is thin, and the heat exchange efficiency is hardly lowered.

  In the invention according to claim 3, the heat receiving pipe of the heat exchanger for recovering latent heat has a three-dimensional structure laminated in the vertical direction and the horizontal direction, and the number of laminations in the vertical direction is equal to the number of laminations in the horizontal direction. The combustion apparatus according to claim 1, wherein the combustion apparatus is less in number.

In the combustion apparatus of the present invention, the heat receiving tube of the heat exchanger for recovering latent heat constitutes a three-dimensional structure laminated in the vertical direction and the horizontal direction, but the number of vertical layers is larger than the number of horizontal layers. Few. Therefore, draining is smooth.
That is, when the heat receiving pipes are three-dimensionally stacked, the drain generated on the upper stage falls to the heat receiving pipe located on the lower stage, and the amount of drain adhering to the heat receiving pipe located on the lower end increases, and the heat receiving pipe located on the lower stage side. The heat exchange efficiency will be reduced.
On the other hand, in the present invention, the number of stacked heat receiving tubes is smaller than the number of stacked layers in the vertical direction. Therefore, in the combustion apparatus of the present invention, the number of stacks in the height direction of the heat receiving tubes is small, and the influence of the drain generated on the upper stage side on the lower heat receiving tubes is small.

  According to a fourth aspect of the present invention, in the combustion according to any one of the first to third aspects, the heat receiving tubes of the heat exchanger for recovering latent heat are arranged in a direction crossing the flow of the combustion gas. Device.

  In the combustion apparatus of the present invention, since the heat receiving tubes of the latent heat recovery heat exchanger are arranged in a direction crossing the flow of the combustion gas, the drain adhering to the heat receiving tube is easily blown off by the combustion gas. Therefore, the drain film formed on the heat receiving tube is thin, and the heat exchange efficiency is hardly lowered.

  In the invention according to claim 5, the heat exchanger for recovering latent heat has a plurality of heat receiving tubes arranged in parallel between a pair of headers, and the header includes a tube plate to which the heat receiving tubes are attached. 2. An end chamber member provided on the back side of the tube sheet, wherein the header constitutes a part of a wall surface of a series of combustion gas passages extending from the combustion means to the exhaust part. It is a combustion apparatus in any one of thru | or 4.

  In the combustion apparatus of the present invention, since the header of the latent heat recovery heat exchanger constitutes a part of the wall surface of the combustion gas flow path, the overall shape of the combustion apparatus can be reduced in size.

  The combustion apparatus of the present invention has an effect that heat exchange efficiency is excellent while being small.

  Subsequently, a combustion apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of the combustion apparatus of the present embodiment. FIG. 2 is an exploded perspective view showing the vicinity of the secondary heat exchanger of the combustion apparatus shown in FIG. FIG. 3 is a perspective view showing the secondary heat exchanger and the exhaust member. FIG. 4 is an exploded perspective view of the secondary heat exchanger shown in FIG. FIG. 5 is a cross-sectional view of the secondary heat exchanger shown in FIG. Fig.6 (a) is a schematic diagram which shows arrangement | positioning of the heat receiving tube in the secondary heat exchanger shown in FIG. 3, (b), (c) is a modification of arrangement | positioning of the heat receiving tube shown to (a). It is a schematic diagram which shows. FIGS. 7A and 8A are perspective views showing the cup member of the secondary heat exchanger shown in FIG. 3, and FIGS. 7B and 8B are FIGS. ), An AA cross-sectional view of FIG. FIG. 9 is a cross-sectional view showing the relationship between the cup member and the tube sheet in the heat exchanger shown in FIG. FIG. 10 is an external view of the combustion apparatus of the present embodiment.

  In FIG. 1, 1 is a combustion apparatus of this embodiment. The combustion apparatus 1 has a configuration in which a can body 2, a primary heat exchanger 3 (sensible heat recovery type heat exchanger), a combustion burner 5 (combustion means), and a blower means 6 are provided. Further, on the downstream side (upper side in FIG. 1) of the combustion gas flow path 8 with respect to the primary heat exchanger 3, a secondary heat exchanger 7 (latent heat recovery) for recovering latent heat mainly recovering latent heat from the combustion gas. Heat exchanger).

  The primary heat exchanger 3 is a so-called fin-and-tube heat exchanger whose main part is made of copper. The primary heat exchanger 3 is disposed in a combustion gas flow path 8 through which high-temperature combustion gas generated in the combustion burner 5 flows. The primary heat exchanger 3 mainly functions as sensible heat recovery means for recovering sensible heat of the combustion gas, and heats hot water flowing inside.

  The primary heat exchanger 3 includes a water inlet 10 and a water outlet 11. The water inlet 10 is connected to the water outlet 13 side of the secondary heat exchanger 7. Hot water after heat exchange in the secondary heat exchanger 7 flows into the primary heat exchanger 3.

  The primary heat exchanger 3 exchanges heat with the combustion gas flowing in the combustion gas flow path 8 of the can body 2 in which the combustion burner 5 is arranged, and the outlet 11 is a load terminal such as a heating device (not shown). Or a hot water tap is connected.

  As shown in FIGS. 1 and 2, the secondary heat exchanger 7 is connected to the can body 2 via a connection member 14. As shown in FIG. 2, the connecting member 14 has a collecting portion 14a connected to the opening portion of the can body 2 and a connecting portion 14b arranged in a substantially “L” shape, and has a flow path communicating with the inside. Forming. The connection portion 14 b is a portion that comes into surface contact with the back surface of the case member 15 (body portion) of the secondary heat exchanger 7 and is in an airtight state. The connection portion 14 b is an opening for introducing combustion gas into the case member 15. 14c is provided.

As shown in FIGS. 3 and 4, the secondary heat exchanger 7 is configured by brazing a large number of heat receiving tubes 18 to headers 16 and 17 arranged in parallel to both ends of a hollow box-shaped case member 15. Connected.
The case member 15 is a member in which a metal plate is bent to form a “U” shape as shown in FIG. 4, and a top plate 70 is attached to form a box shape as shown in FIG. 3. That is, the case member 15 includes a top plate 70, a front plate 71, a back plate 72, and a bottom plate 73, and the side portions 74 and 75 are open. The side surface portions 74 and 75 of the case member 15 are closed by the headers 16 and 17 as described later. The case member 15 has a discharge port 15a (exhaust part) on the front surface and an introduction port 15b on the back surface.

  The discharge port 15 a is an opening for discharging combustion gas from the secondary heat exchanger 7. As shown in FIG. 3, an exhaust member 19 having four openings is mounted on the front side of the discharge port 15a. The inlet 15b is for introducing the combustion gas that has passed through the primary heat exchanger 3 into the secondary heat exchanger 7, and the secondary heat exchanger 7 is connected to the can body 2 via the connecting member 14. Is provided at a position corresponding to the opening 14c of the connection member. The combustion gas introduced from the inlet 15 b passes through the gaps between the many heat receiving pipes 18 that traverse the inside of the case member 15, and exchanges heat with the hot water in the heat receiving pipe 18. The combustion gas that has exchanged heat with the hot water in the heat receiving pipe 18 is discharged to the outside of the secondary heat exchanger 7 through the discharge port 15a.

  The heat receiving pipes 18 are metal pipes, and are arranged in parallel with gaps that allow the combustion gas to pass therethrough. The secondary heat exchanger 7 is discharged after the hot water flowing through each heat receiving pipe 18 turns back in the flow direction in the headers 16 and 17 and reciprocates with respect to the case member 15. The heat receiving pipe 18 employed in the present embodiment is made of a corrosion resistant material such as stainless steel. Further, the heat receiving pipe 18 employed in the present embodiment is a bare pipe and does not have fins.

When the heat receiving pipes 18 constituting the secondary heat exchanger 7 are arranged in the state shown in FIG. 4, four heat receiving pipes 18 are arranged in the vertical direction of the main body case 15 and eight in the width direction of the main body case 15. The heat receiving pipes 18 are arranged side by side. That is, in the present embodiment, the heat receiving pipe 18 of the secondary heat exchanger 7 (latent heat recovery heat exchanger) has a three-dimensional structure laminated in the vertical direction and the horizontal direction, and the number of stacked layers in the vertical direction is horizontal. Less than the number of layers in the direction. It is desirable that the number of stacks in the vertical direction is not more than ½ of the number of stacks in the horizontal direction.
When the secondary heat exchanger 7 is observed from the direction of the arrow P in FIG. 4, the heat receiving tubes 18 are arranged in an array (staggered) as shown in FIG. 6A. The arrangement of the heat receiving tubes 18 is preferably a complex array as shown in FIG. 6A, but may be a matrix as shown in FIG. 6B.

  Among the heat receiving pipes 18 arranged in the case member 15, those arranged in the first and second rows from the inlet 15 b side constitute the upstream heat receiving pipe group 23, and 3 to 6 adjacent thereto. The columns in the row are classified as the midstream heat receiving tube groups 24 and 25. Further, the heat receiving pipes 18 arranged in the seventh and eighth rows from the inlet 15b side, that is, the first and second rows from the outlet 15a side constitute a downstream heat receiving pipe group 26.

  As shown in FIGS. 3, 4, and 5, the header 16 is configured such that three cup-shaped cup members 30, 31, and 32 (end chamber members) are aligned and brazed to the tube plate 20. . The header 17 is formed by brazing two cup-shaped cup members 33 and 35 (end chamber members) to the tube plate 20.

  The tube plate 20 is made of metal, and a plurality of tube insertion holes 38 are provided on the connection surface 37a of the flat plate portion 37 in accordance with the arrangement of the heat receiving tubes 18, and the step portions 40 are formed by bending four sides. Is. The step portion 40 protrudes to the joining side of the cup members 30, 31, 32, that is, the joining surface 37 b side of the flat plate portion 37. The tube plate 20 on the header 16 side is divided into a region A where the flat plate portion 37 is roughly divided and the upstream heat receiving tube group 23 is connected, a region B where the midstream heat receiving tube groups 24 and 25 are connected, and a downstream heat receiving tube group 26. The region C is classified into three regions. Further, the flat plate portion 37 of the tube plate 20 on the header 17 side is roughly divided into a region D to which the upstream heat receiving tube group 23 and the midstream heat receiving tube group 24 are connected, and the midstream heat receiving tube group 25 and the downstream heat receiving tube group 26. The region E is classified. As shown in FIG. 4, the tube plate 20 is brazed so as to close both end portions of the case member 15 and joined so as to be in an airtight state. Therefore, the side portions 74 and 75 of the case member 15 are closed by the tube plates 20 of the headers 16 and 17.

The cup members 30 and 31 are members brazed so as to cover the regions A and C of the joint surface 37b. As shown in FIG. 5, the cup members 30 and 31 form an inflow chamber 36 and an outflow chamber 39 with the joint surface 37 b of the tube plate 20. As shown in FIG. 7, the cup members 30 and 31 have a flange 41 and a water chamber portion 43 surrounded by the periphery of the opening. The flange 41 has a parallel part 45 joined substantially parallel to the flat plate part 37 of the tube sheet 20 via a brazing material, and a substantially vertical direction with the outer peripheral end of the parallel part 45 facing the bulging direction of the water chamber part 43. The separation portion 46 is folded back.
The water chamber portion 43 is provided with a connection port 47 for connecting the inside and outside of the inflow chamber 36 and the outflow chamber 39 constituted by the cup members 30 and 31 and the tube plate 20 to connect the pipe. The connection port 47 on the cup member 30 side functions as an inlet 47 a for supplying hot water to the secondary heat exchanger 7 from the outside, and the connection port 47 on the cup member 31 side is subjected to heat exchange in the secondary heat exchanger 7. It functions as an outlet 47b for discharging hot water to the outside.

  The cup members 32, 33, and 35 have structures similar to the cup members 30 and 31, respectively, as shown in FIG. 8, and the sizes and shapes thereof are the same. The cup members 32, 33, and 35 each have a flange 50 having the same shape as the flange 41 of the cup members 30 and 31, and the water chamber portion 43 of the cup members 30 and 31 is located at a position surrounded by the flange 50. A large water chamber 51 is also provided.

  As shown in FIG. 5, the cup member 32 covers the substantially entire region B in the center portion of the tube plate 20 on the header 16 side to form a midstream bypass chamber 55. Further, the cup members 33 and 35 mounted on the header 17 side cover the substantially entire areas of the regions D and E of the tube plate 20 to form an upstream bypass chamber 56 and a downstream bypass chamber 57, respectively.

  A water supply pipe 60 for supplying hot water from the outside is connected to the inflow port 47 a provided in the cup member 30. A connection pipe 61 that connects the secondary heat exchanger 7 and the primary heat exchanger 3 is connected to the outlet 47 b provided in the cup member 31. The secondary heat exchanger 7 includes an upstream heat receiving tube group 23, a midstream heat receiving tube group 24, 25 and a downstream heat receiving tube group by cup members 32, 33, 35 brazed to the tube plates 20, 20 of the headers 16, 17. 26 are connected to each other. As a result, a series of flow paths are formed which connect the inflow port 47a to the outflow port 47b and allow the hot water to reciprocate inside the case member 15.

The external shape of the combustion apparatus 1 of the present embodiment is as shown in FIG. 10, the combustion burner 5 is provided at the lower part of the can body 2, and the primary heat exchanger 3 (sensible heat recovery type heat exchanger) is provided at the upper part of the can body 2. ) And the connection member 14 is provided in the upper end part of the can body 2, and the secondary heat exchanger 7 is mounted in the connection member 14. FIG.
In the present embodiment, the case member 15 and the headers 16 and 17 of the secondary heat exchanger 7 constitute a part of the outer wall of the combustion device 1. Therefore, the combustion apparatus 1 of this embodiment has few parts and is easy to assemble. In the present embodiment, the cup members 30, 31, 32, 33, and 35 (end chamber members) of the headers 16 and 17 of the secondary heat exchanger 7 are provided on the outer side surface of the combustion gas flow path 8. ing.
Inside the combustion apparatus 1, a series of combustion gas flow paths 8 extending from the combustion burner 5 to the exhaust member 19 are formed.

More specifically, the combustion gas flow path 8 is formed by the inside of the can body 2 from the combustion burner 5 to the connecting member 14. Inside the connecting member 14, the combustion gas flow path 8 is formed by the connecting member 14 itself. Further, the secondary heat exchanger 7 itself serves as the combustion gas flow path 8 from the connection member 14 to the exhaust member 19.
That is, the secondary heat exchanger 7 includes a case member 15, and the top surface, the front surface, the back surface, and the bottom surface are surrounded by the case member 15. Further, the side surface portions 74 and 75 of the case member 15 are closed by the tube plates 20 of the headers 16 and 17. Therefore, the secondary heat exchanger 7 is surrounded by six surfaces except the inlet 15 b and the outlet 15 a, and the inside functions as the combustion gas flow path 8.
Thus, in the combustion apparatus 1 of the present embodiment, the tube plates 20 of the headers 16 and 17 constitute a part of the wall surface of the combustion gas flow path 8.

  In this embodiment, since the tube plates 20 of the headers 16 and 17 constitute a part of the wall surface of the combustion gas flow path 8, the heat receiving pipes 18 are densely arranged in the combustion gas flow path 8. That is, the secondary heat exchanger 7 includes a plurality of heat receiving tubes 18 arranged in parallel between a pair of headers 16 and 17. In the present embodiment, the secondary heat exchanger 7 receives the heat receiving tubes 18 on the tube plate 20 to which the heat receiving tubes 18 are attached. A heat pipe 18 is attached. In this embodiment, since the tube plate 20 to which the heat receiving pipe 18 is attached constitutes the side wall surface of the combustion gas flow path 8, the heat receiving pipe 18 penetrates both side walls of the combustion gas flow path 8. . Therefore, the heat receiving pipe 18 crosses the combustion gas flow path 8 and has a large surface area in the flow path.

Then, the flow of the hot water in the combustion apparatus 1 of this embodiment is demonstrated.
Hot water supplied from outside through the water supply pipe 60 flows into the inflow chamber 36 of the header 16 from the inlet 47a of the secondary heat exchanger 7 as indicated by an arrow in FIG. This hot water communicates with the inflow chamber 36, flows into each heat receiving pipe 18 constituting the upstream heat receiving pipe group 23, and flows toward the header 17. Hot water flowing through the upstream heat receiving pipe group 23 flows into the upstream detour chamber 56, reverses the flow direction, and flows into the heat receiving pipe 18 of the middle flow heat receiving pipe group 24 opened in the upstream detour chamber 56. Thereafter, the hot water flows in the heat receiving pipes 18 constituting the midstream heat receiving pipe group 25 and the downstream heat receiving pipe group 26 while being diverted in the middle flow bypass chamber 55 and the downstream bypass chamber 57 in the same manner, and flows into the outflow chamber 39. The hot and cold water flowing in each heat receiving pipe 18 is heat exchange heated with the combustion gas introduced into the case member 15. Hot water reaching the outflow chamber 39 is discharged from the outlet 47 b to the outside of the secondary heat exchanger 7 and supplied to the primary heat exchanger 3 through the connection pipe 61. The hot water introduced into the primary heat exchanger 3 is heated by heat exchange with the high-temperature combustion gas flowing in the combustion gas flow path 8 and supplied from a water outlet 11 to a hot water tap and a load terminal (not shown).

Next, the flow of the combustion gas in the combustion apparatus 1 of the present embodiment will be described.
The combustion gas generated by the combustion operation of the combustion burner 5 flows in the combustion gas flow path 8 of the can 2 toward the downstream side, that is, upward. The high-temperature combustion gas generated in the combustion burner 5 passes through the primary heat exchanger 3 provided in the middle of the combustion gas flow path 8 and heats hot water flowing in the primary heat exchanger 3. The combustion gas from which sensible heat has been mainly recovered in the primary heat exchanger 3 reaches the connection member 14 disposed on the most downstream side of the combustion gas flow path 8.

The combustion gas that has passed through the primary heat exchanger 5 gathers at the gathering portion 14a of the connecting member 14, and flows into the secondary heat exchanger 7 through the inlet 15b that is airtightly connected to the opening 14c of the connecting portion 14b. To do. In the secondary heat exchanger 7, the combustion gas flows in a horizontal direction (lateral direction) from an introduction port 15 b provided on the back surface of the case member 15 toward an exhaust port 15 a (exhaust part) provided on the front surface of the case member 15. ). On the other hand, since the secondary heat exchanger 7 has a large number of heat receiving pipes 18 arranged in parallel on headers 16 and 17 provided on both side surfaces of the case member 15, the combustion gas flows into the heat receiving pipe 18. Across the heat receiving pipes 18 arranged in parallel. Thereby, in the secondary heat exchanger 7, the latent heat of the combustion gas is mainly recovered in the hot water flowing in the heat receiving pipe 18, and the drain generated on the surface of the heat receiving pipe 18 is separated from the heat receiving pipe 18 by the blowing of the combustion gas. .
Thereafter, the combustion gas reaches the discharge port 15 a in front of the secondary heat exchanger 7 and is discharged to the outside of the case member 15.

  In the combustion apparatus 1 of the present embodiment, the tube plates 20 of the headers 16 and 17 constitute the side wall surface of the combustion gas flow path 8, and a plurality of heat receiving tubes 18 are arranged in parallel with the tube plate 20. Therefore, the heat receiving pipe 18 is densely stored in the combustion gas flow path 8. Therefore, there are many contact opportunities between the surface of the heat receiving pipe 18 and the combustion gas, and the heat exchange efficiency is high.

  Further, as described above, since the latent heat of the combustion gas is recovered by the secondary heat exchanger 7, water vapor in the combustion gas is condensed and drainage is generated. Drain is generated on the surface of the heat receiving tube 18, but the heat receiving tube 18 employed in the present embodiment is a bare tube and does not have protrusions such as fins. Also, since there are no fins, there is no gap for the drain to enter. Therefore, the heat receiving pipe 18 employed in the present embodiment is unlikely to accumulate drainage.

  Moreover, in the combustion apparatus 1 of this embodiment, the heat receiving pipes 18 are arranged in a direction crossing the flow of the combustion gas. Therefore, the drain adhering to the heat receiving pipe 18 is blown off by the combustion gas, and the drain is not easily collected.

  In addition, although the drain generated on the upper stage falls to the heat receiving pipe located on the lower stage, in the combustion apparatus 1 of the present embodiment, the number of stacks in the vertical direction is smaller than the number of stacks in the horizontal direction. The amount of drain falling on the heat pipe is small.

  Thus, in the combustion apparatus 1 of this embodiment, since the amount of drains adhering to the heat receiving pipe 18 is small, the heat exchange efficiency of the secondary heat exchanger 7 is high. Since the heat exchange efficiency of the secondary heat exchanger 7 is high, the combustion apparatus 1 of this embodiment has high heat efficiency and energy saving.

In the embodiment described above, the present invention is applied to a structure in which the combustion burner 5 is in the lower part and the heat exchanger (the primary heat exchanger 3 and the secondary heat exchanger 7) is provided in the upper part. It is also possible to apply the present invention to a combustion apparatus called “reverse combustion system” by those skilled in the art. Here, the “reverse combustion method” refers to a configuration in which a heat exchanger is provided in the lower part of the combustion burner 5.
However, the effect of the present invention is more conspicuous in the case of adopting the structure in which the heat exchanger is provided on the upper part of the combustion burner 5 as shown in the embodiment than in the case of employing the “reverse combustion method”. . That is, when the reverse combustion method is adopted, the combustion gas flows in the direction of gravity, and the combustion gas flows in the forward direction with respect to the drain falling direction. Therefore, the separation of the drain is relatively smooth and the adverse effect of the drain is small. On the other hand, when adopting a structure in which a heat exchanger is provided in the upper part of the combustion burner 5, according to the structure of the prior art, the combustion gas flows in the direction opposite to the direction in which the drain falls, and the drain accumulates. What was easy was that drainage was smoothly discharged by adopting the present invention.

  In the above-described embodiment, the brazing structure is exemplified as the structure of the headers 16 and 17, but the present invention is not limited to this structure, and may be, for example, a screw fastening structure or a rivet structure. When a screw tightening structure or a rivet structure is adopted, packing is used together.

It is a block diagram of the combustion apparatus which is one Embodiment of this invention. It is a disassembled perspective view which shows the secondary heat exchanger vicinity of the combustion apparatus shown in FIG. It is a perspective view which shows a secondary heat exchanger and an exhaust member. It is a disassembled perspective view of the secondary heat exchanger shown in FIG. It is AA sectional drawing of the secondary heat exchanger shown in FIG. (A) is a schematic diagram which shows arrangement | positioning of the heat receiving tube in the secondary heat exchanger shown in FIG. 3, (b), (c) shows the modification of arrangement | positioning of the heat receiving tube shown to (a). It is a schematic diagram. (A) is a perspective view which shows the cup member of the secondary heat exchanger shown in FIG. 3, (b) is AA sectional drawing of (a). (A) is a perspective view which shows the cup member of the secondary heat exchanger shown in FIG. 3, (b) is AA sectional drawing of (a). It is sectional drawing which shows the relationship between the cup member and tube sheet in the heat exchanger shown in FIG. It is an external view of the combustion apparatus of this embodiment. It is a model figure of the combustion apparatus described in Unexamined-Japanese-Patent No. 11-148642.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion apparatus 2 Can body 3 Primary heat exchanger (sensible heat recovery type heat exchanger)
5 Combustion burner (combustion means)
7 Secondary heat exchanger (heat exchanger for latent heat recovery)
15 Case member 16, 17 Header 18 Heat receiving pipe 30, 31, 32, 33, 35 Cup member (end chamber member)

Claims (5)

Combustion means, a sensible heat recovery heat exchanger that recovers sensible heat of combustion gas generated mainly in the combustion means and heats hot water, and a downstream side of the combustion gas flow path with respect to the sensible heat recovery heat exchanger And a latent heat recovery heat exchanger that mainly recovers the latent heat of the combustion gas and heats the hot water, and the hot water that has passed through the latent heat recovery heat exchanger flows to the sensible heat recovery heat exchanger. In the combustion apparatus piped, the heat exchanger for latent heat recovery includes a large number of heat receiving tubes arranged in parallel. The combustion apparatus according to claim 1, wherein the heat receiving pipe of the heat exchanger for recovering latent heat is a bare pipe. The heat receiving pipe of the heat exchanger for latent heat recovery has a three-dimensional structure laminated in a vertical direction and a horizontal direction, and the number of vertical layers is smaller than the number of horizontal layers. The combustion apparatus according to 1 or 2. The combustion apparatus according to any one of claims 1 to 3, wherein the heat receiving pipes of the latent heat recovery heat exchanger are arranged in a direction crossing the flow of the combustion gas. The heat exchanger for latent heat recovery has a plurality of heat receiving tubes arranged in parallel between a pair of headers, and the header is provided on a tube plate to which the heat receiving tubes are attached and on the back side of the tube plate. The combustion apparatus according to any one of claims 1 to 4, further comprising an end chamber member, wherein the header constitutes a part of a wall surface of a series of combustion gas passages extending from the combustion means to the exhaust portion. .

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