US20130061821A1

US20130061821A1 - Combustion apparatus

Info

Publication number: US20130061821A1
Application number: US13/606,633
Authority: US
Inventors: Yuki Maeshima; Hidefumi Koda
Original assignee: Noritz Corp
Current assignee: Noritz Corp
Priority date: 2011-09-09
Filing date: 2012-09-07
Publication date: 2013-03-14
Also published as: JP2013057464A; JP5782938B2

Abstract

An exhaust channel of a combustion apparatus is defined by an upper sloping plate and a lower sloping plate. The lower sloping plate contains a rising part and a lower sloping wall. A water droplet baffle plate is positioned across an interspace from the rising part. The interspace is brought into fluid communication with the exhaust channel through an upper surface opening while being brought into fluid communication with a bottom of a heat exchange chamber through a communication opening. A collision wall part of the water droplet baffle plate is disposed in close proximity to a lowest fine tube so as to oppose against a combustion exhaust flow. Water droplets adhere onto the collision wall part. Water droplets failing to adhere to the collision wall part fall through the upper surface opening positioned over an upper end of the collision wall part.

Description

TECHNICAL FIELD

The present invention relates to a combustion apparatus equipped with a latent heat exchanger (a heat exchanger for the recovery of latent heat). In particular, the present invention is concerned with technology for the prevention of scattering of the condensed water when combustion exhaust having passed through the latent heat exchanger is let off from the exhaust outlet port.

BACKGROUND ART

In recent years, there has been known a so-called condensing-type combustion apparatus made up of a primary heat exchanger (a sensible heat exchanger) configured for heat-exchange heating by the heat of combustion of a combustion burner and a secondary heat exchanger (a latent heat exchanger) configured for the recovery of latent heat from the combustion exhaust having undergone heat exchange in the primary heat exchanger. And, in such a condensing-type combustion apparatus, when combustion exhaust comes into contact with the latent heat exchanger, water vapor present in the combustion exhaust condenses into condensed water (drain water) of strong acidity. Incidentally, the condensing-type combustion apparatus requires space necessary for the arrangement of the latent heat exchanger. This may cause inconveniences, such as a lack of space for placing a sound absorption material for the purpose of noise control, a complexity of the route through which the combustion exhaust passes and other troublesome conditions. Therefore, it is quite likely that the generation of noise associated with combustion and the generation of noise associated with the passage of combustion exhaust will take place.
Therefore, the following proposals have been made mainly for the purpose of the control of noise. According to Patent Literature Publications 1 and 2, the exhaust channel extending from the outlet port of a heat exchange chamber which accommodates a latent heat exchanger up to the exhaust port is formed as a sloping channel at an upward slant in the direction of the exhaust port. In addition, according to Patent Literature Publication 3, the exhaust channel is formed as a curved channel in the shape of an upward crank.

CITATION LIST

Patent Literature Cited

Patent Literature Pub. 1: JP-A-2007-232289;
Patent Literature Pub. 2: JP-A-2009-243725; and
Patent Literature Pub. 3: JP-A-2007-33001

SUMMARY OF INVENTION

Technical Problem

However, the following problems tend to occur if it is configured that the combustion exhaust exiting the heat exchange chamber flows upward along the sloping exhaust channel. In other words, it is likely that a part of the drain water to be flowed off downward from the bottom of the heat exchange chamber in the vicinity of the outlet port thereof for neutralizing treatment, is involved, in the form of water droplets, in the flow of combustion exhaust into the exhaust channel. As a result, it is likely that such drain water droplets join the combustion exhaust flow, thereafter being scattered to the outside from the exhaust port.
Therefore, the technical problem to be solved is to prevent scattering of the drain water to the outside while accomplishing noise control in a combustion apparatus equipped with a latent heat exchanger.

Solution to Problem

The present invention is intended for a combustion apparatus which includes a latent heat exchanger and which is connected by an exhaust channel extending obliquely upward from an exhaust outlet port of a heat exchange chamber in which is housed the latent heat exchanger to an exhaust port situated higher relative to the exhaust outlet port. And, the combustion apparatus of the present invention has the following characteristic particulars. More specifically, the exhaust channel is made up of an upper sloping plate and a lower sloping plate. And, the lower sloping plate is made up of a rising part extending generally vertically from the bottom of the heat exchange chamber and a sloping part extending obliquely upward from the upper end of the rising part towards the exhaust port. And, a water droplet baffle plate is disposed across an interspace from the rising part and generally in parallel with the rising part, whereby the water droplet baffle plate is situated nearer to the heat exchange chamber than the rising part. The exhaust outlet port of the heat exchange chamber is defined by the upper end of the water droplet baffle plate and the lower end of the upper sloping plate.
According to the aforesaid combustion apparatus of the present invention, even if, after the drain water is condensed on the surface of the latent heat exchanger as a result of the recovery of latent heat from the combustion exhaust in the heat exchange chamber, droplets of the drain water are involved in the flow of combustion exhaust and flow, together with the combustion exhaust, in the direction of the exhaust outlet port, the combustion exhaust in a state of involving drain water droplets is collided against the water droplet baffle plate, whereby the combustion exhaust changes in its flow direction after collision to now move upward to enter the exhaust channel from the exhaust outlet port. At that time, the combustion exhaust flow collides against the water droplet baffle plate, whereby the water droplets that have been involved in the combustion exhaust adhere onto and move downward along the water droplet baffle plate. This enables the combustion exhaust from which water droplets have been removed to flow into the exhaust channel, whereby it is ensured that the occurrence of a problem that the drain water will scatter out of the combustion exhaust discharged from the exhaust outlet port is prevented.
The following advantageous effects are obtained by the arrangement that, in the aforesaid combustion apparatus of the present invention, the interspace is brought into fluid communication with the exhaust channel through an upper surface opening which opens upward to the exhaust channel and a communication opening in fluid communication with the interspace is provided between the water droplet baffle plate and the bottom of the heat exchange chamber. Stated in another way, it is further ensured that the scattering of drain water from the exhaust port is prevented. In addition, even when the water droplet baffle plate is provided, it is eliminated as much as possible that such provision becomes resistant to the combustion exhaust, thereby inhibiting an increase in noise rise and achieving quietness of operation. Describing in detail this, even when the combustion exhaust is collided against the water droplet baffle plate, all of the water droplets are not adhered onto the water droplet baffle plate, and it is therefore conceivable that water droplets may remain in some amount in the combustion exhaust flowing into the exhaust channel form the exhaust outlet port. However, even in the case where water droplets linger in some amount, the flow direction is forcibly changed upward towards the exhaust outlet port on the upper end side when collided against the water droplet baffle plate, whereby the momentum of the combustion exhaust flow becomes damp and, in addition, the residual water droplets are made to fall down into the interspace from the upper surface opening for discharge through the communication opening on the bottom side because the upper surface opening is opened at a position over the upper end of the water droplet baffle plate. Furthermore, even when the water droplet baffle plate is disposed in close proximity to the latent heat exchanger, the interspace and the heat exchange chamber are brought into fluid communication with each other via the communication opening as well as via the upper surface opening, thereby preventing an increase in resistance to the combustion exhaust to thereby contribute to the quietness of operation.
In addition, the following advantageous effects will be achieved if, in the aforesaid combustion apparatus of the present invention, the lower end of the water droplet baffle plate is horizontally displaced out of a virtual vertical line extending vertically downward from the upper end of the water droplet baffle plate, whereby the water droplet baffle plate is at an oblique slant to be placed in an overhang state towards the heat exchange chamber. In other words, the drain water droplets collided against and then adhered onto the water droplet baffle plate are made to easily fall out from the surface of the water droplet baffle plate. This enables water droplets from the subsequently colliding combustion exhaust to easily adhere to and separate from the water droplet baffle plate, whereby it is further ensured that the adhesion of water droplets to the water droplet baffle plate by collision and the separation of water droplets from the water droplet baffle plate will be accomplished.
Finally, the following advantageous effects will be accomplished by the arrangement that, in the aforesaid combustion apparatus of the present invention, the upper end of the water droplet baffle plate is situated higher relative to the lowest front-end portion of the latent heat exchanger housed in the heat exchange chamber whereas the lower end of the water droplet baffle plate is situated lower relative to the aforesaid lowest portion of the latent heat exchanger towards the bottom of the heat exchange chamber. In other words, the water droplet baffle plate is oriented so as to positively face or oppose against the flow of combustion exhaust flowing under the lowest front-end portion of the latent heat exchanger, i.e., the flow of combustion exhaust flowing between the lowest portion of the latent heat exchanger and the bottom of the heat exchange chamber. This positively ensures that the combustion exhaust flow is collided against the water droplet baffle plate, whereby it is further ensured that the adhesion of water droplets to the water droplet baffle plate by collision and the separation of water droplets from the water droplet baffle plate will be accomplished.

BRIEF DESCRIPTION OF DRAWINGS

In the drawing:

FIG. 1 is an illustrative diagram showing in cross section a combustion apparatus according to an embodiment of the present invention;

FIG. 2 is a partially enlarged diagram relating to an exhaust channel portion of FIG. 1;

FIG. 3 is a partially enlarged diagram showing, in a more enlarged manner, the exhaust channel portion of FIG. 2; and

FIG. 4 is an enlarged perspective view showing a specific example of the shape of a water droplet baffle plate.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawing figures.
Referring first to FIG. 1, there is shown a part of a hot water supply heater serving as a combustion apparatus in accordance with an embodiment of the present invention. The hot water supply heater of FIG. 1 is configured as a so-called condensing-type (a latent heat recovery-type) hot water supply heater. More specifically, the combustion apparatus includes, in its housing 1, a combustion burner 2, a primary heat exchanger 3 for effecting heat-exchange heating by the heat of combustion (the sensible heat) of the combustion burner 2, a secondary heat exchanger (a latent heat exchanger) 4 for guiding the combustion exhaust past the primary heat exchanger 3 configured for the recovery of latent heat from the combustion exhaust and an exhaust channel 5 into and from which the combustion exhaust having passed through the secondary heat exchanger 4 is flowed and then discharged to the outside space.
The combustion burner 2, which is housed in a burner casing 21, is provided with the supply of combustion air from a fan 22 and the supply of fuel (for example, fuel gas) from a fuel supply pipe 23. The combustion burner 2 burns into flames towards an upper combustion space. The primary heat exchanger 3 is housed in a primary heat exchanger casing 31 connected to the upper side of the burner casing 21. Water preheated when it was previously passed through the secondary heat exchanger 4 is flowed out from one end of the primary heat exchanger 3 to the other end. During the flow through the primary heat exchanger 3, the water is heated by heat exchange by the heat of combustion of the combustion burner 2.
A channel casing 6 is interposed between the primary heat exchanger casing 31 and a secondary heat exchanger casing 41 in which the secondary heat exchanger 4 is enclosed. In the channel casing 6, an inner channel 61 is formed such that the combustion exhaust from the upper surface opening of the primary heat exchanger casing 31 is collected and then guided up to an exhaust inlet port 42 of the secondary heat exchanger casing 41. The channel casing 6 is configured such that the inner channel 61 is, at its lower side, expanded throughout the entire upper surface opening of the primary heat exchanger casing 31 so that the combustion exhaust from the primary heat exchanger 3 is collected, and is gradually narrowed upward towards the rear side whereby to guide the combustion exhausts (see dotted arrows in FIG. 1) to the exhaust inlet port 42 on the rear side of the secondary heat exchanger casing 41.
An exhaust top 7 is connected by a flange piece 71, situated around the exhaust top 7, to the front side of the secondary heat exchanger casing 41. And in the secondary heat exchanger casing 41, a heat exchange chamber 40 is defined by partition formation. The heat exchange chamber 40 is, on the rear side (the right-hand side in the figure), in fluid communication with the inner channel 61 by way of the exhaust inlet port 42 and is, on the front side (the left-hand side in the figure), in fluid communication with the exhaust channel 5 by way of an exhaust outlet port 44 serving also as an inflow port of the exhaust channel 5. The upstream end of a drain collecting pipe 81 is opened at the bottom on the front end side of the heat exchange chamber 40, i.e., at a position under and near the exhaust outlet port 44 of the heat exchange chamber 40. Such arrangement enables the drain water falling down onto the upper surface of a bottom wall 45 from the secondary heat exchanger 4 and so on to fall down into the drain collecting pipe 81 to gather there.
As the secondary heat exchanger 4 to be accommodated in the heat exchange chamber 40, there is exemplarily shown in the figure a so-called capillary or multitubular type heat exchanger although various types of heat exchangers may be employed. A large number of fine tubes 43, 43, . . . grouped into outward fine tubes and return fine tubes are arrayed so as to pass transversely across the inside of the secondary heat exchanger casing 41. In such an arrangement, the water admitted into a water entrance side header (not shown in the figure) is passed through a large number of outward fine tubes 43, 43, . . . and then through a large number of return fine tubes 43, 43, . . . from a return header. Thereafter, the water is fed to one of the end sides of the primary heat exchanger 3 from the return header. And, during the time from when the combustion exhaust is introduced into the secondary heat exchanger casing 41 from the exhaust inlet port 42 to when it passes through the exhaust outlet port 44, the combustion exhaust is brought into contact with the fine tubes 43, 43, . . . wherein latent heat in the combustion exhaust is absorbed in the water present in each fine tube 43 by heat exchange, thereby effecting the recovery of latent heat. Of course, as pointed out above, any type other than the capillary type may be employed as serving as the secondary heat exchanger 4.
The exhaust channel 5 is a channel that is extended from the exhaust outlet port 44 positioned in the vertical middle of the heat exchange chamber 40 up to an exhaust port 72 opening at the front surface upper end side position of the exhaust top 7. The exhaust channel 5 is defined by partition formation so as to form a sloping channel extending obliquely upward to the exhaust port 72 as a whole so that the combustion exhaust admitted in from the exhaust outlet port 44 flows obliquely upward towards the exhaust port 72 positioned higher relative to the exhaust outlet port 44. More specifically, as shown in detail in FIGS. 2 and 3, the exhaust channel 5 as a characteristic portion of the present invention is made up of an upper sloping plate 51 and a lower sloping plate 52, wherein there is defined by partition formation between the upper sloping plate 51 and the lower sloping plate 52 a channel space serving as a sloping channel curving such that its upward inclination becomes gradually lower in the direction of the exhaust port 72. In addition, a water droplet baffle plate 53 is disposed on the side of the exhaust outlet port 44 of the exhaust channel 5 (the inflow port side of the exhaust channel 5). Hereinafter, a description will be made in which the horizontal direction in the drawing is meant to be the front-rear direction of the heat exchange chamber 40, the secondary heat exchanger casing 41, the secondary heat exchanger 4 and so on.
The upper sloping plate 51 is made up of an upper wall part 512 and an upper sloping wall 514. The upper wall part 512 is disposed such that it hangs downward vertically from an upper end edge 511 which is connected, at the front end side, to the lower surface of a top wall 46 of the secondary heat exchanger casing 41, thereby partitioning off the front end side of the heat exchange chamber 40. On the other hand, the upper sloping wall 514 curves at a sharp angle into a V-shape towards the exhaust port 72 at the lower end edge (lower end) 513 of the upper wall part 512 and extends therefrom obliquely upward. The upper sloping wall 514 is curved halfway in its extension and a leading edge 515 thereof is connected to the exhaust top 7 so as to provide covering over the upper side of the exhaust port 72. In addition, the lower sloping plate 52 is made up of a rising part 522 and a lower sloping wall 524. The rising part 522 has a lower end edge 521 which is raised upward from the bottom wall 45 of the secondary heat exchanger casing 41. On the other hand, the lower sloping wall 524 curves at an upper end 523 of the rising part 522 and then extends obliquely upward. And, the lower sloping wall 524 curves halfway in its extension and then changes gradually or moderately in its sloping pitch and a leading edge 525 thereof is connected to the exhaust top 7 so as to provide covering over the lower side of the exhaust port 72.
The water droplet baffle plate 53 is disposed across an interspace 54 from the rising part 522 and generally in parallel with the rising part 522 so as to be situated nearer to the secondary heat exchanger 4 than the rising part 522 of the lower sloping plate 52, i.e., the water droplet baffle plate 53 is positioned on the rear side of the rising part 522. Owing to such arrangement, the water droplet baffle plate 53 is made to positively face or oppose against the flow of combustion exhaust F (see FIG. 3) moving forward especially under the lowest front-side one of the fine tubes 43, 43, . . . which together form the secondary heat exchanger 4, i.e., a fine tube 43 a. And, the interspace 54 has in its upper surface an upper surface opening 541 so as to face the exhaust channel 5, and is brought into fluid communication with the exhaust channel 5 via the upper surface opening 541. In addition, the interspace 54 is, in its lower end position, brought into fluid communication with the bottom of the heat exchange chamber 40 via a communication opening 542. In other words, the water droplet baffle plate 53 has a lower end 531 which is positioned in such a manner that it is floatingly situated a predetermined distance above the bottom wall 45 of the secondary heat exchanger casing 41. In addition, the lower end 531 of the water droplet baffle plate 53 is displaced forward (leftward in FIG. 3) by a predetermined angle a relative to a virtual vertical line V extending downward from the upper end 532, whereby the water droplet baffle plate 53 is disposed such that its upper end side opposes against the exhaust gas flow F in an overhang state.
The exhaust outlet port 44 in communication with the exhaust channel 5 from the heat exchange chamber 40 is formed, by an opening defined between the upper end 532 of the water droplet baffle plate 53 and the lower end edge 513 of the upper sloping plate 51, in a vertical intermediate region of the heat exchange chamber 40. In addition, since the purpose of provision of the water droplet baffle plate 53 as described above is that its collision wall part 533 is collided against the combustion exhaust flow F for adhesion of water droplets thereon, it is preferred that the water droplet baffle plate 53 is disposed in close proximity to the front end fine tube 43 a, with a relatively narrow space left therebetween (for example, at a distance of about 10 millimeters). In addition to the above, in order that droplets of the drain water dripping off from the lower end edge 513 fall down onto the bottom wall 45, it is preferable that the collision wall part 533 is positioned nearer to the exhaust top 7 than the lower end edge 513 of the upper wall part 512 of the upper sloping plate 51, in other words, the collision wall part 533 is positioned horizontally ahead of the lower end edge 513.
FIG. 4 shows a concrete shape example of the water droplet baffle plate 53. More specifically, the water droplet baffle plate 53 is formed using a plate material of stainless steel in view of the prevention of corrosion by drain water. And, the water droplet baffle plate 53 includes, as its main element, the collision wall part 533 which is raised from the lower end 531 up to the upper end 532 and against which the combustion exhaust flow F comes into collision. The water droplet baffle plate 53 curves generally at right angles in the direction of the front side (the left-hand side in FIG. 4), i.e., in the direction of the exhaust top 7, from the upper end 532 of the collision wall part 533 and then extends generally in the horizontal direction and in addition, its sloping wall part 534 extends obliquely upward along the upper surface of the lower sloping plate 52 (see also FIG. 3) for a predetermined distance. In addition, an opening corresponding to the upper surface opening 541 is formed in a portion extending generally in the horizontal direction from the upper end 532 of the collision wall part 533, and both end edge portions of the collision wall part 533 are curved forward at adequate positions to thereby form supporting parts 535, 535 extending up to the rising part 522 of the lower sloping plate 52. In addition, the lower end 531 is provided with a flange part having a curved lower end edge for reinforcement so that the collision wall part 533 is maintained in a flat shape. And, the supporting parts 535, 535 are joined to the rising part 522 of the lower sloping plate 52 while the sloping wall part 534 is joined to the lower sloping wall 524 of the lower sloping plate 52, whereby the water droplet baffle plate 53 is assembled.
In addition, as the water droplet baffle plate 53, it suffices if the collision wall part 533 is disposed in place and therefore the other portions are not essential. Stated in another way, it suffices if (i) the collision wall part 533 is positioned such that the interspace 54 is defined between itself and the rising part 522 of the lower sloping plate 52, (ii) the communication opening 542 is formed on the underside of the interspace 54 and (iii) the upper surface opening 541 is formed on the upper side of the interspace 54.
The exhaust channel 5 described above provides the following advantageous operation/working-effects. More specifically, during the time from when the combustion exhaust flows into the heat exchange chamber 40 via the exhaust inlet port 42 to when it advances to the exhaust outlet port 44, the drain water is condensed on the surface of the secondary heat exchanger 4 as a result of the recovery of latent heat from the combustion exhaust. Especially, much more drain water falls down onto the bottom wall 45 from the lowest front-side fine tube 43 a. Droplets of the drain water are involved in the combustion exhaust flow F (see FIG. 3). And, after the combustion exhaust involving drain water droplets collides against the collision wall part 533 of the water droplet baffle plate 53, the flow direction is changed upward to flow into the exhaust channel 5 by way of the exhaust outlet port 44. At that time, as a result of collision of the combustion exhaust flow F against the collision wall part 533, the drain water droplets caught up in the combustion exhaust adhere onto the collision wall part 533. And, these adhered drain water droplets move downward along the collision wall part 533 to the bottom wall 45 and are collected together in the drain collecting pipe 81. On the other hand, the combustion exhaust from which drain water droplets have been removed will flow into the exhaust channel 5 by way of the exhaust outlet port 44. This certainly ensures that the condition that the drain water to be discharged from the exhaust port 72 through the exhaust channel 5 is scattered around, is prevented.
In addition, even when drain water droplets remain in some amount in the combustion exhaust flowing into the exhaust channel 5 by way of the exhaust outlet port 44, the momentum of the flow of combustion exhaust becomes damp because the flow direction is forcibly changed upward by collision against the collision wall part 533 and, in addition, the residual drain water droplets also fall down into the interspace 54 via the upper surface opening 541 because the upper surface opening 541 is opened from the position of the upper end 532 of the collision wall part 533. As the result of this, it is further ensured that the scattering of drain water from the exhaust port 72 is prevented. Furthermore, although it is disposed in relatively close proximity, in face-to-face manner, to the lower end position of the secondary heat exchanger 4, the collision wall part 533 is in fluid communication with the exhaust channel 5 via the upper surface opening 541 at the rear (on the front side) and, in addition, the interspace 54 in fluid communication with the heat exchange chamber 40 via the communication opening 542 is defined by partition formation, whereby it is eliminated as much as possible that the collision wall part 533 becomes resistant to the combustion exhaust, thereby inhibiting an increase in noise rise and achieving quietness of operation.

OTHER EMBODIMENTS

It should be noted that the present invention is not limited to the foregoing embodiment and therefore includes other various embodiments. More specifically, in the foregoing embodiment, the collision wall part 533 is inclined in an overhang state so that drain water droplets adhered by collision easily fall down, which however should not be considered limitative for the present invention. It is preferred that the collision wall part 533 be positioned, at least, vertically. In addition, even in the case where the collision wall part 533 is disposed on a slant reverse to that in the foregoing embodiment, it is still possible to cause drain water droplets adhered to the collision wall part 533 by collision to flow downward.

Claims

1. A combustion apparatus which comprises a latent heat exchanger and which is connected by an exhaust channel extending obliquely upward from an exhaust outlet port of a heat exchange chamber in which is housed said latent heat exchanger to an exhaust port situated higher relative to said exhaust outlet port,

wherein said exhaust channel comprises an upper sloping plate and a lower sloping plate;

wherein said lower sloping plate comprises a rising part extending generally vertically from the bottom of said heat exchange chamber and a sloping part extending obliquely upward from the upper end of said rising part towards said exhaust port;

wherein a water droplet baffle plate is disposed across an interspace from said rising part and generally in parallel with said rising part, said water droplet baffle plate being situated nearer to said heat exchange chamber than said rising part; and

wherein said exhaust outlet port of said heat exchange chamber is defined by the upper end of said water droplet baffle plate and the lower end of said upper sloping plate.

2. The combustion apparatus as set forth in claim 1,

wherein said interspace is brought into fluid communication with said exhaust channel through an upper surface opening which opens upward to said exhaust channel and wherein a communication opening in fluid communication with said interspace is provided between said water droplet baffle plate and the bottom of said heat exchange chamber.

3. The combustion apparatus as set forth in claim 1,

wherein the lower end of said water droplet baffle plate is horizontally displaced out of a virtual vertical line extending vertically downward from the upper end of said water droplet baffle plate, whereby said water droplet baffle plate is at an oblique slant to be placed in an overhang state towards said heat exchange chamber.

4. The combustion apparatus as set forth in claim 1,

wherein the upper end of said water droplet baffle plate is situated higher relative to the lowest front-end portion of said latent heat exchanger housed in said heat exchange chamber whereas the lower end of said water droplet baffle plate is situated lower relative to the aforesaid lowest portion of said latent heat exchanger.