CHIMNEY SYSTEMS WITH INTEGRATED WASTE HEAT RECOVERY AND RELATED METHODS

Abstract

A representative system includes: an inner stack defining a flow path to direct exhaust gasses from the exhaust air outlet of a heating appliance to an exhaust; an outer stack disposed about an exterior of the inner stack and being spaced therefrom to form a combustion air passage in a heat transfer relationship with the exterior of the inner stack; a combustion air opening disposed at the intake end of the outer stack configured to receive combustion air and provide the combustion air to the combustion air passage; an air dam positioned to terminate the combustion air passage; a combustion air conduit configured to direct the combustion air from the combustion air passage to the combustion air inlet of the heating appliance; wherein, in operation, heat is transferred from the exhaust gasses to the combustion air directed through the combustion air passage.

Claims

1. A chimney system with integrated waste heat recovery for use with a heating appliance, the heating appliance being located within a structure, the heating appliance having a combustion air inlet and an exhaust air outlet, the system comprising: an inner stack pneumatically communicating with the exhaust air outlet and extending in length to an exhaust, disposed exterior to the structure, the inner stack defining a flow path to direct exhaust gasses from the exhaust air outlet to the exhaust; an outer stack extending along a portion of the length of the inner stack between an intake end and an appliance end, the outer stack being disposed about an exterior of the inner stack and being spaced therefrom to form a combustion air passage therebetween, the combustion air passage being annular in cross-section and in a heat transfer relationship with the exterior of the inner stack; a combustion air opening disposed at the intake end of the outer stack, the combustion air opening being configured to receive combustion air and provide the combustion air to the combustion air passage; an air dam disposed at the appliance end of the outer stack to terminate the combustion air passage; and a combustion air conduit pneumatically communicating with the combustion air passage at the appliance end of the outer stack and upstream of the air dam, the combustion air conduit being configured to direct the combustion air from the combustion air passage to the combustion air inlet of the heating appliance; wherein, in operation, heat is transferred from the exhaust gasses being directed from the heating appliance to the combustion air directed through the combustion air passage.

2. The system of claim 1, wherein: the outer stack has a first aperture defining a first opening; and an inlet of the combustion air conduit communicates with the combustion air passage via the first opening.

3. The system of claim 1, further comprising a flow disruption assembly disposed along the flow path of the exhaust gasses, the flow disruption assembly having a first fin extending radially across the flow path, the first fin being inclined with respect to the flow path to disrupt the flow of the exhaust gasses.

4. The system of claim 3, wherein: the flow disruption assembly is a first flow disruption assembly; and the system further comprises a second flow disruption assembly disposed along the flow path of the exhaust gasses, the second flow disruption assembly being spaced from the first flow disruption assembly.

5. The system of claim 3, wherein the flow disruption assembly has a second fin, the second fin being positioned downstream of the first fin with respect to the flow path of the exhaust gasses.

6. The system of claim 3, wherein the flow disruption assembly has an axial shaft, and the first fin is attached to the axial shaft.

7. The system of claim 3, wherein: the outer stack has a second aperture defining a second opening; the inner stack has a first inner aperture defining a first inner opening, the first inner opening being aligned with the second opening; the flow disruption assembly is mounted to an inner stack panel configured to selectively cover the first inner opening, the first fin being fixed in position relative to the inner stack panel.

8. The system of claim 7, wherein: the flow disruption assembly is removably mounted to the inner stack via the inner stack panel; and the outer stack has an outer door configured to provide selective access to the second opening to permit installation and removal of the flow disruption assembly.

9. The system of claim 1, wherein the combustion air opening is annular.

10. The system of claim 1, wherein the air dam is annular.

11. The system of claim 1, wherein the air dam is positioned between an inner surface of the outer stack and an outer surface of the inner stack.

12. A method for integrated waste heat recovery of a heating appliance, the heating appliance being located within a structure, the heating appliance having a combustion air inlet and an exhaust air outlet, the method comprising: providing an inner flow path to direct exhaust gasses from the exhaust air outlet of the heating appliance to an exhaust, which is disposed exterior to the structure; providing a combustion air passage annular in cross section and disposed about an exterior of the inner flow path, the combustion air passage being in a heat transfer relationship with the inner flow path; providing a combustion air flow path to direct the combustion air from the combustion air passage to the combustion air inlet of the heating appliance; and transferring heat from the exhaust gasses of the heating appliance being directed along the inner flow path to the combustion air being directed in a counter-flow direction through the combustion air passage.

13. The method of claim 12, wherein the combustion air opening is disposed within the structure.

14. The method of claim 12, further comprising disrupting the flow of the exhaust gasses along the inner flow path to enhance heat exchange.

15. The method of claim 14, wherein the disrupting is provided by a flow disruption assembly having a first fin, the flow disruption assembly being removably positioned along the inner flow path.

16. The method of claim 15, further comprising: removing the flow disruption assembly; cleaning the flow disruption assembly; and reinstalling the flow disruption assembly.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Non-limiting and non-exhaustive embodiments are described with reference to the following drawings. In the drawings, like reference numerals refer to like parts throughout the various figures unless otherwise specified. These drawings are not necessarily drawn to scale. Likewise, the relative sizes of elements illustrated by the drawings may differ from the relative sizes depicted.

[0008] The disclosure can be more fully understood by the subsequent detailed description and examples with reference made to the accompanying drawings.

[0009] FIG. 1 is a schematic diagram of an example embodiment of a chimney system with integrated waste heat recovery.

[0010] FIG. 2 is a schematic diagram, in plan view, of the embodiment of FIG. 1.

[0011] FIG. 3 is a cross-sectional schematic diagram of the embodiment of FIGS. 1 and 2 as viewed along section line 3-3 of FIG. 2.

[0012] FIG. 4 is a cross-sectional schematic diagram of the embodiment of FIGS. 1-3 as viewed along section line 4-4 of FIG. 2.

[0013] FIG. 5 is a schematic diagram showing detail of the exhaust fan and combustion air inlet.

[0014] FIG. 6 is a cross-sectional schematic diagram showing detail of the combustion air inlet and combustion air passage.

[0015] FIG. 7 is a cross-sectional schematic diagram showing detail of the combustion air passage and the combustion air conduit.

[0016] FIG. 8 is a partially cut-away, cross-sectional schematic diagram showing detail of the combustion air passage and the combustion air conduit.

[0017] FIG. 9 is a partially exploded, schematic diagram showing detail of an example embodiment of a turbulator assembly.

[0018] FIG. 10 is a schematic diagram showing the embodiment of the turbulator assembly of FIG. 9 in an installed configuration.

[0019] FIG. 11 is a schematic diagram of the turbulator assembly of FIGS. 9 and 10.

[0020] FIG. 12 is a flow chart depicting an example embodiment of a method for integrated waste heat recovery.

DETAILED DESCRIPTION

[0021] The following describes several embodiments of chimney systems with integrated waste heat recovery and related methods. It is to be understood that the invention is not limited in its application to the details of the arrangements shown since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation.

[0022] Reference throughout this specification to one embodiment, an embodiment, one example, and/or an example (or language similar thereto) means that a particular feature, structure, and/or characteristic described in connection with the embodiment or example is included in at least one embodiment or version. Thus, appearances of the phrases in one embodiment, in an embodiment, one example, and/or an example in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the feature(s), structure(s), and/or characteristic(s) may be combined in any suitable combination(s) and/or sub-combination(s) in one or more embodiments or examples.

[0023] In this regard, FIGS. 1-8 depict an example embodiment of a chimney system with integrated waste heat recovery (hereinafter chimney system) 100. Chimney system 100 is configured for use with a heating appliance 102 (such as a boiler, for example), that is typically located within a structure 104 (for example, a building). Heating appliance 102 incorporates a combustion air inlet 106 and an exhaust air outlet 108. Chimney system 100 interconnects with heating appliance 102 and is configured to direct a flow of combustion air to combustion air inlet 106 and direct exhaust gasses from exhaust air outlet 108.

[0024] Chimney system 100 includes an inner stack 110 and an outer stack 120. Each stack may be formed of multiple sections (see, for example, sections 103 and 105 of FIG. 8) that are joined in a generally end-to-end configuration to form a flow path. The sections can be assembled with a male/female joint system with or without flanges that can be secured with an optional locking band (e.g., 107 of FIG. 8). The joint between adjacent sections can be sealed with gasket material (e.g., a graphite gasket) configured to withstand high temperature and pressure.

[0025] Inner stack 110 (see, FIGS. 4 and 7) pneumatically communicates with exhaust air outlet 108. Inner stack 110 defines a flow path 112 that extends from exhaust air outlet 108 to exhaust 114. Inner stack 110 is operative to direct exhaust gasses from exhaust air outlet 108 outward and through exhaust 114. Typically, exhaust 114 is disposed outside of the structure in which heating appliance 102 is located.

[0026] An outer stack 120 extends from an intake end 122 to an appliance end 124 along a portion of the length of inner stack 110. Outer stack 120 also is disposed about an exterior of inner stack 110 and is spaced from inner stack 110 to form a combustion air passage 130 therebetween. Combustion air passage 130 is annular in cross-section and is disposed in a heat transfer relationship with the exterior 116 of inner stack 110.

[0027] As best shown in FIGS. 5 and 6, an intake cone 125 defining a combustion air opening 132 is disposed at intake end 122. Intake cone 125 is configured to allow for smooth transition of ambient air into the annulus of combustion air passage 130. Combustion air opening 132 is annular in cross section and is positioned about inner stack 110. Oftentimes, combustion air opening 132 is located within the structure in which heating appliance 102 is located. Combustion air opening 132 is configured to receive combustion air 134 and provide the combustion air to combustion air passage 130 for routing the combustion air toward heating appliance 102, i.e., in a counter-flow direction relative to the flow direction of the exhaust gasses. As shown in FIG. 4, combustion air passage 130 exhibits an annular cross section.

[0028] At appliance end 124 of outer stack 120, an air dam 136 is disposed for terminating combustion air passage 130. As shown in FIGS. 7 and 8, air dam 136 is annular and is positioned between an inner surface 128 of outer stack 120 and an outer surface 116 of inner stack 110. Notably, air dam 136 pneumatically seals this end of combustion air passage 130 upstream of combustion air inlet 106 of heating appliance 102.

[0029] Upstream of air dam 136, a combustion air conduit 140 is disposed to direct combustion air 134 from combustion air passage 130 to combustion air inlet 106 of heating appliance 102. Specifically, an inlet 142 of combustion air conduit 140 pneumatically communicates with combustion air passage 130. In the depicted embodiment, outer stack 120 incorporates a first aperture 126 defining a first opening 127. Inlet 142 of combustion air conduit 140 communicates with combustion air passage 130 via first opening 127 and reconfigures the flow of combustion air into a non-annual flow.

[0030] A mechanical exhaust fan 150 (see, FIGS. 1 and 5, for example) may be included to provide mechanically induced draft for drawing out exhaust gasses, such as when a heat source of the heating appliance does not produce sufficient draft for proper operation. Although depicted in FIG. 5 as being disposed at the exhaust 114 (i.e., the vent termination point), in other embodiments, mechanical exhaust fan 150 may be disposed inline between heating appliance 102 and the vent termination point.

[0031] In some embodiments, a mechanical intake fan 152 (see, FIG. 1, for example) may be included to provide mechanically induced draft for enhancing air flow into combustion air opening 132 and through combustion air passage 130. The combustion air flow could also be created by another means such as a heating appliance with a power burner (not shown). As would be understood by one of skill in the art, a fan system for the exhaust and/or intake air may incorporate other components (e.g., draft controllers) to maintain the proper air flow as the application dictates. These controllers should maintain draft via pressure transducers measuring the pressure in the exhaust and intake air streams.

[0032] In operation, as relatively hot exhaust gasses are directed along flow path 112 defined by inner stack 110, heat is transferred from the exhaust gasses to combustion air 134 that is being directed through combustion air passage 130 toward heating appliance 102. Specifically, by creating flows in opposite directions separated by the inner stack, the heat of the hotter exhaust gasses is transferred by convection onto the inner surface of the inner stack and then conducted to the outer surface where it heats the cooler unconditioned air flowing through the annulus of the combustion air passage.

[0033] The heat transfer between the two flows can be enhanced in several ways. For instance, the outer stack can be insulated with insulation material to limit the convective heat loss from the outer stack to the surrounding environment. As another example, a turbulator assembly may be used to create turbulence in the exhaust air flow, which may lead to more heat being transferred between the two flows. Additionally, or alternatively, the inner stack may be fitted with fins that protrude inwardly from the inner surface to create turbulence and increase the heat transfer surface area.

[0034] The described concepts can be used in conjunction with heating appliances and high-temperature exhaust applications. Of note, by preheating the combustion air through the heat exchange, combustion efficiency of the associated heating appliance may be substantially increased. Additionally, removal of heat from the exhaust gasses may reduce the appearance of exhaust plumes.

[0035] As mentioned, one or more turbulator assemblies may optionally be disposed along flow path 112 to disrupt the flow of exhaust gasses and enhance heat transfer. In the example embodiment of FIGS. 1-8, two turbulator assemblies (160, 162) are provided that are spaced from each other; however, for ease of description, only one will be described in detail. It should be noted that placement of one or more turbulators along a flow path may deviate from the positions shown.

[0036] With reference to FIG. 9, turbulator assembly 160 is modular in configuration and includes an inner stack section 170, an outer stack section 180, and a turbulator section 190. Inner stack section 170, in addition to defining a portion of flow path 112, incorporates an inner stack aperture 172 that defines an inner stack opening 174. Inner stack section 170 also exhibits a centerline 176. Outer stack section 180 incorporates an outer stack aperture 182 that defines an outer stack opening 184.

[0037] As shown in FIGS. 10 and 11, turbulator section 190 includes an inner stack panel 192 that is configured to seal inner stack opening 174, such as with an interposed gasket 193. Inner stack panel 192 also mounts a flow disruption assembly 194 that is configured to alter the flow of exhaust gasses along flow path 112 to disrupt the temperature gradient, thereby increasing heat transfer to air within the combustion air passage.

[0038] Flow disruption assembly 194 includes one or more fins (e.g., fins 196 and 198) mounted to an axial shaft 200 via one or more arms (e.g., arm 201). The fins extend outwardly from axial shaft 200 and radially across flow path 112, although various other arrangements may be used. In this embodiment, each fin is generally planar and is fixed in an inclined position with respect to flow path 112 to divert gasses outwardly from centerline 176. In embodiments in which multiple fins are used, sets (e.g., pairs) of fins may be mounted at various positions along and/or about the flow path. For instance, one or more fins may be positioned downstream of one or more other fins.

[0039] Attachment of flow disruption assembly 194 to inner stack panel 192 facilitates removal of turbulator section 190 from turbulator assembly 160. In this regard, an optionally hinged outer door 202, which may be secured to outer stack 180 via adjustable latches (e.g., latch 204), provides selective access to outer stack opening 184 of outer stack section 180 to permit installation and removal of turbulator section 190, such as may be performed for cleaning of flow disruption assembly 194. A gasket 203 may be interposed between outer door 202 and outer stack section 180.

[0040] A perceived benefit of the removable turbulator section is to provide easy access for cleaning in applications where the exhaust air can contaminate and clog other designs. Note also that removal of turbulator section 190 may be a toolless operation, such as in embodiments that use wing nuts (e.g., nut 205) for securement of inner stack panel 192.

[0041] An example embodiment of a method for integrated waste heat recovery of a heating appliance is shown in FIG. 12. As shown in FIG. 12, method 250 may be construed as beginning at block 252, in which an inner flow path is provided to direct exhaust gasses from an exhaust air outlet of the heating appliance to an exhaust. In some embodiments, the exhaust is disposed exterior to the structure in which the heating appliance is located. In block 254, a combustion air passage, annular in cross section, is disposed about an exterior of the inner flow path, with the combustion air passage being in a heat transfer relationship with the inner flow path. In block 256, a combustion air flow path is provided to direct the combustion air from the combustion air passage to the combustion air inlet of the heating appliance. Then, as shown in block 258, heat from the exhaust gasses is transferred to the combustion air that is being directed in a counter-flow direction through the combustion air passage.

[0042] In some embodiments, such a method may additionally include disrupting the flow of the exhaust gasses along the inner flow path to enhance heat exchange. As described previously, for example, disrupting the flow of the exhaust gasses may be provided by a flow disruption assembly that is removably positioned along the inner flow path. If so equipped, a related method may further include removing the flow disruption assembly from the inner flow path, cleaning the flow disruption assembly (to remove any accumulation/debris that may degrade performance), and reinstalling the flow disruption assembly.

[0043] The embodiments described above are illustrative of the invention and it will be appreciated that various permutations of these embodiments may be implemented consistent with the scope and spirit of the invention as defined by the claims. By way of example, although described as being used primarily for combustion air heating, various other uses, such as heating of the ambient air and/or sending the heated air to a secondary heat exchanger, may be provided. Any examples provided are non-limiting examples.