Latent heat recovery heat exchanger

Abstract

To effectively prevent scattering of drain water to the outside of an exhaust cylinder 3, in a latent heat recovery-type heat exchanger which includes: a housing 1 having a heat exchange chamber 11 in which a combustion exhaust gas flows from a rear part to a front part; and a plurality of heat absorption pipes 2 disposed in the heat exchange chamber 11, and in which the exhaust cylinder 3 into which the combustion exhaust gas flows through an exhaust port 13 formed on a front plate portion 1b, is mounted on the front plate portion 1b of the housing 1, a drain receiving portion 112 recessed to a lower portion and a drain port 113 are disposed on a front end portion of a bottom surface 111 of the heat exchange chamber 11, and further a cover plate 6 for covering the drain receiving portion 112 from an upper part is disposed.SOLUTION: A latent heat recovery-type heat exchanger is constituted to allow drain water on a cover plate 6 to fall down to a drain receiving portion 112 from one end in a lateral direction of a cover plate 6 by providing the cover plate 6 with down grade to one side in the lateral direction orthogonal to a longitudinal direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a latent heat recovery heat exchanger that includes a housing having an internal heat exchange chamber through which combustion exhaust gas flows from rear to front, and a plurality of heat absorption pipes arranged in the heat exchange chamber, and that recovers the latent heat contained in the combustion exhaust gas to heat water flowing through the heat absorption pipes. [Background technology]

[0002] In this type of latent heat recovery heat exchanger, an exhaust pipe is typically attached to the front plate of the housing, into which combustion exhaust gas flows through an exhaust port opened in the front plate. The front end of the bottom of the heat exchange chamber is provided with a downwardly recessed drain receiver and a drain port for draining drain water from the drain receiver. Drain water is highly acidic water that is generated when moisture in the combustion exhaust gas condenses on the outer surface of the heat absorption pipe. While most of the drain water is drained from the drain receiver through the drain port, some of the drain water in the drain receiver can be blown up by the combustion exhaust gas flowing toward the exhaust port and splashed out of the exhaust pipe, potentially contaminating the area around the exhaust pipe.

[0003] Therefore, a conventional latent heat recovery heat exchanger is known, as disclosed in Patent Document 1, which is provided with a cover plate that covers the drain receiving portion from above. In this case, the cover plate prevents the combustion exhaust gas from striking the drain water in the drain receiving portion with force, thereby suppressing the drain water from being stirred up. In addition, in this case, holes are formed in the cover plate to allow the drain water on the cover plate to fall into the drain receiving portion, preventing the drain water from accumulating on the cover plate.

[0004] However, it was discovered that this system had the following drawback: When holes were formed in the cover plate, the combustion exhaust gas that had gotten under the cover plate flowed upward through the holes, creating an upward flow of combustion exhaust gas within the holes. Some of the drain water that fell through the holes was then swirled up by the upward flow of combustion exhaust gas and scattered outside the exhaust stack. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-223645 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above, an object of the present invention is to provide a latent heat recovery heat exchanger that can more effectively prevent drain water from scattering outside the exhaust stack. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention provides a latent heat recovery heat exchanger comprising a housing having an internal heat exchange chamber through which combustion exhaust gas flows from rear to front, and a plurality of heat absorption pipes arranged in the heat exchange chamber, wherein the latent heat contained in the combustion exhaust gas is recovered to heat water flowing through the heat absorption pipes, wherein an exhaust pipe is attached to the front plate of the housing, into which the combustion exhaust gas flows through an exhaust port opened in the front plate, and a drain receiving section recessed downward and a drain port for draining drain water in the drain receiving section are provided at the front end of the bottom surface of the heat exchange chamber, and further wherein a cover plate is provided to cover the drain receiving section from above, wherein the cover plate has a downward slope in one lateral direction perpendicular to the front-to-rear direction, so that the drain water on the cover plate falls into the drain receiving section from one lateral end of the cover plate.

[0008] According to the present invention, by providing the cover plate with a downward slope in one lateral direction, the drain water on the cover plate falls from one lateral end of the cover plate into the drain receiving section, eliminating the need to form a hole in the cover plate for the drain water to fall through. Therefore, the drain water is not blown up by the upward flow of combustion exhaust gas generated at the hole. As a result, the drain water can be effectively prevented from scattering outside the exhaust stack.

[0009] In the present invention, it is also desirable that the lower surface of the exhaust flow path in the exhaust stack be located above the front end of the cover plate that reaches the front plate of the housing, and that a wall be provided that extends above the front end of the cover plate to the same height as the lower surface of the exhaust flow path. In this way, the wall functions as a barrier that prevents drain water on the cover plate from entering the exhaust flow path, making it possible to more effectively prevent drain water from splashing outside the exhaust stack.

[0010] Furthermore, in the present invention, when the cover plate is formed in a stepped shape with the front portion positioned lower than the rear portion, it is desirable to provide an upright baffle plate at the other lateral end of the front portion of the cover plate to prevent combustion exhaust gas from flowing from the lateral outer side of that end onto the front portion of the cover plate. Here, when combustion exhaust gas flows from the lateral outer side onto the front portion of the cover plate, some of the drain water flowing down the step between the rear and front portions of the cover plate may be blown up by the flow of combustion exhaust gas. If the flow of combustion exhaust gas from the lateral outer side onto the front portion of the cover plate is blocked by the baffle plate as described above, the blowing up of the drain water flowing down the step can be suppressed, and the splashing of the drain water outside the exhaust stack can be more effectively prevented. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a latent heat recovery heat exchanger according to an embodiment of the present invention; [Figure 2] FIG. 2 is a cross-sectional side view taken along line II-II in FIG. [Figure 3] Cross-sectional view taken along line III-III in Figure 2. [Figure 4] FIG. 2 is an exploded perspective view showing the attachment structure of the exhaust pipe in the latent heat recovery type heat exchanger according to the embodiment. [Figure 5] FIG. 2 is a perspective view of a cover plate provided in the latent heat recovery type heat exchanger according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] 1 and 2, a latent heat recovery heat exchanger A according to an embodiment of the present invention includes a housing 1 having an internal heat exchange chamber 11 through which combustion exhaust gas flows from rear to front (from right to left in FIG. 2), and a plurality of heat absorption pipes 2 arranged in the heat exchange chamber 11. The latent heat contained in the combustion exhaust gas is recovered to heat water flowing through the heat absorption pipes 2.

[0013] The rear plate 1a of the housing 1 is provided with an inlet 12 through which combustion exhaust gas flows in after passing through a sensible heat recovery heat exchanger (not shown), and the front plate 1b of the housing 1 is provided with an exhaust port 13 through which combustion exhaust gas flows out after passing through the heat exchange chamber 11. An exhaust stack 3 is attached to the front plate 1b, into which the combustion exhaust gas flows in via the exhaust port 13. Three upper and lower flow straightening members 31, 32, and 33 are attached inside the exhaust stack 3, and two upper and lower exhaust flow paths 3a and 3b are defined between the upper flow straightening member 31 and the middle flow straightening member 32, and between the middle flow straightening member 32 and the lower flow straightening member 33. The cross-sectional area of ​​each exhaust flow path 3a and 3b is narrowed to increase the flow velocity of the combustion exhaust gas and prevent the combustion exhaust gas from accumulating near the outlet of the exhaust stack 3.

[0014] The mounting structure of the exhaust stack 3 will be described in detail with reference to Figure 4 as well. In this embodiment, a mounting plate 4 having an opening 41 that matches the exhaust port 13 is provided for mounting the exhaust stack 3. The mounting plate 4 is then placed on the front surface of the front plate 1b with a packing 42 sandwiched therebetween, and the flange portion 34 at the rear end of the exhaust stack 3 is placed on the front surface of the mounting plate 4 with a packing 43 sandwiched therebetween. In this state, the flange portion 34, along with the packing 43, mounting plate 4, and packing 42, are fastened together to the front plate 1b with screws 44. The portion of the mounting plate 4 near the upper edge of the opening 41 is fastened together with the packing 42 to the front plate 1b with screws 45, and the upper portion of the flange portion 34 is fastened together with the packing 43 to the mounting plate 4 with screws 46.

[0015] In this embodiment, six heat absorption pipes 2 are arranged vertically in the heat exchange chamber 11, extending in the front-rear direction while meandering in a horizontal direction perpendicular to the front-rear direction. Vertically adjacent heat absorption pipes 2, 2 are shifted in the front-rear direction by half the meandering pitch. On the outer surface of one horizontal side panel 1c of the casing 1, an inlet header 21 and an outlet header 22 are attached to which the upstream ends and downstream ends of the six heat absorption pipes 2 are connected, respectively. Water flowing through each heat absorption pipe 2 from the inlet header 21 to the outlet header 22 is heated by the recovery of latent heat due to condensation of moisture in the combustion exhaust gas on the outer surface of each heat absorption pipe 2.

[0016] The bottom surface 111 of the heat exchange chamber 11, which is formed by the bottom plate of the housing 1, is inclined downward toward the front. A downwardly recessed drain receiver 112 is provided at the front end of the bottom surface 111, into which drain water dripping from the outer surface of the heat absorption pipe 2 flows due to the inclination of the bottom surface 111. Referring to Figure 3, the drain receiver 112 has its lowest point in the horizontal direction at a portion that roughly coincides with the exhaust port 13, and this portion is provided with a drain outlet 113 for discharging the drain water in the drain receiver 112. The drain water drained from the drain outlet 113 is led to a neutralizer (not shown).

[0017] Furthermore, a guide plate 5 is provided at the upper front end of the heat exchange chamber 11 to guide the flow of the combustion exhaust gas downward, preventing the combustion exhaust gas from proceeding straight into the exhaust stack 3 while still containing droplets of drain water. Furthermore, a cover plate 6 is provided at the lower front end of the heat exchange chamber 11 to cover from above the drain receptacle 112 that is close to the exhaust port 13. This prevents the combustion exhaust gas from hitting the drain water in the drain receptacle 112 with too much force, preventing the drain water from being stirred up by the combustion exhaust gas.

[0018] Here, as shown in FIG. 3 , the cover plate 6 has a downward slope in one lateral direction (to the right in FIG. 3 ). Therefore, drain water on the cover plate 6 falls from one lateral end of the cover plate 6 into the drain receiving portion 112. Therefore, there is no need to form a hole in the cover plate 6 through which drain water falls, as in the conventional example. If a hole were formed, the combustion exhaust gas that has slipped under the cover plate 6 would flow upward through the hole, generating an upward flow of combustion exhaust gas within the hole. Then, some of the drain water falling through the hole may be lifted up by the upward flow of combustion exhaust gas and splash outside the exhaust stack 3. On the other hand, in this embodiment, since there is no need to form a hole as described above, such a problem does not occur and splashing of drain water outside the exhaust stack 3 can be effectively prevented.

[0019] Furthermore, the lower surface of the exhaust flow path inside the exhaust stack 3, i.e., the lower surface of the lower exhaust flow path 3b, is located above the front end of the cover plate 6 that reaches the front plate 1b of the housing 1. A wall portion 7 is provided that extends above the front end of the cover plate 6 and reaches the same height as the lower surface of the lower exhaust flow path 3b. This allows the wall portion 7 to function as a barrier that prevents drain water on the cover plate 6 from entering the lower exhaust flow path 3b. This makes it possible to more effectively prevent drain water from splashing outside the exhaust stack 3.

[0020] In this embodiment, the wall 7 is configured as a hanging plate 33a curved at the rear end of the lower flow straightening member 33 inside the exhaust stack 3, but is not limited to this. For example, it is also possible to form the exhaust port 13 with a chord-shaped lower edge whose height matches the lower surface of the lower exhaust flow path 3b, and to configure the wall 7 with the lower part of the exhaust port 13 on the front plate 1b.

[0021] 5, the cover plate 6 has a stepped shape in which the front portion 61 is located lower than the rear portion 62 and a step portion 63 is formed between the front portion 61 and the rear portion 62. The front portion 61 is sloped downward in one lateral direction. A fixing portion 64 is provided that protrudes rearward like a tongue from the rear portion 62 and is spot welded to the bottom surface 111 of the heat exchange chamber 11. The front portion 61 is formed with a relief hole 61a to prevent interference with the mounting screws 44 for the exhaust pipe 3.

[0022] In such a cover plate 6, when combustion exhaust gas flows laterally outward onto the front portion 61, some of the drain water flowing down the step portion 63 may be stirred up by the flow of combustion exhaust gas. Therefore, in this embodiment, an upright baffle plate portion 65 is provided at the other lateral end (the opposite direction to the downward slope) of the front portion 61 of the cover plate 6, to obstruct the flow of combustion exhaust gas from the lateral outside of that end onto the front portion 61 of the cover plate 6. This makes it possible to suppress the stirring up of the drain water flowing down the step portion 63 and more effectively prevent the drain water from scattering outside the exhaust stack 3.

[0023] Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited thereto. For example, in the above embodiment, the cover plate 6 is provided to cover the portion of the drain receiving portion 112 that is close to the exhaust port 12, but it is also possible to provide a cover plate to cover a wider area of ​​the drain receiving portion 112. [Explanation of symbols]

[0024] A...latent heat recovery heat exchanger, 1...housing, 1b...front plate portion, 11...heat exchange chamber, 111...bottom surface, 112...drain receiving portion, 113...drain outlet, 13...exhaust port, 2...heat absorption pipe, 3...exhaust stack, 3b...lower exhaust flow path (exhaust flow path), 6...cover plate, 61...front portion, 62...rear portion, 65...baffle portion, 7...wall portion.

Claims

1. A latent heat recovery heat exchanger comprising a housing having an internal heat exchange chamber through which combustion exhaust gas flows from rear to front, and a plurality of heat absorption pipes arranged in the heat exchange chamber, and configured to recover latent heat contained in the combustion exhaust gas to heat water flowing through the heat absorption pipes, An exhaust pipe is attached to the front plate of the housing, into which combustion exhaust gas flows through an exhaust port opened in the front plate, A heat exchanger in which a drain receiving portion recessed downward and a drain outlet for draining drain water from the drain receiving portion are provided at the front end of the bottom surface of the heat exchanger, and a cover plate is further provided to cover the drain receiving portion from above, This latent heat recovery type heat exchanger is characterized in that the cover plate has a downward slope in one lateral direction perpendicular to the front-to-rear direction, so that drain water on the cover plate falls from one lateral end of the cover plate into a drain receiving part.

2. 2. The latent heat recovery heat exchanger according to claim 1, characterized in that the lower surface of the exhaust flow path in the exhaust stack is located above the front end of the cover plate that reaches the front plate portion of the housing, and a wall portion is provided that extends above the front end of the cover plate and reaches the same height as the lower surface of the exhaust flow path.

3. 3. A latent heat recovery type heat exchanger according to claim 1, wherein the cover plate is formed in a stepped shape with a front portion positioned lower than a rear portion, and a standing baffle portion is provided at the other lateral end of the front portion of the cover plate to prevent combustion exhaust gas from flowing from the lateral outside of that end onto the front portion of the cover plate.

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