Patent Application
20240247808
A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
Not Applicable
The present disclosure generally relates to biomass (e.g., wood or coal) furnaces. More particularly, the present disclosure relates to secondary combustion systems of biomass furnaces.
Biomass furnaces with secondary combustion air are described in, for example, U.S. Pat. No. 9,651,262 and U.S. Patent Pub. No. 2018/0080656 A1, the contents of which are incorporated herein by reference.
Aspects of the present invention provide a biomass furnace with improved burn efficiency and heat transfer to the area heated by the furnace. Biomass (e.g., cut wood) is placed in a burn chamber through a door at the front of the furnace and lit. Primary and secondary combustion air is forcibly blown into the burn chamber by a combustion fan, generating a forced draft for both primary and secondary combustion.
In one aspect, a biomass furnace comprises a housing including a front wall, a rear wall, a thickness extending from the front wall to the rear wall, a bottom, a top, a height extending from the bottom to the top and perpendicular to the thickness, and a width perpendicular to the thickness and the height. The front wall, the rear wall, the bottom and the top define an interior comprising a burn chamber configured to hold a biomass fuel undergoing combustion. The front wall comprises a fuel loading opening configured to load the biomass fuel into the burn chamber and a fuel loading door to open and close the fuel loading opening. The housing comprises an air inlet in gaseous communication with the burn chamber configured to feed air from the exterior environment into the housing interior 86. The biomass furnace is configured to warm air entering through the air inlet. The housing comprises an air outlet in gaseous communication with the burn chamber configured to feed air warmed by the biomass furnace from the housing interior 86 to the exterior environment. The interior further comprises a secondary air system comprising a longitudinal main tube located above the burn chamber, the main tube comprising a front opening and a main tube interior in gaseous communication with the front opening, and a plurality of branch tubes attached to and oriented transverse to the main tube and each branch tube comprising a branch tube interior in gaseous communication with the front opening. The main tube further comprises at least one aperture in gaseous communication with the front opening and configured to direct secondary air downwardly. Some or all of the branch tubes comprise at least one aperture in gaseous communication with the front opening and configured to direct secondary air downwardly.
In one aspect, a biomass furnace is provided which includes a housing and a burn chamber configured to burn a biomass fuel therein. The biomass furnace further includes a primary air passageway feeding into the burn chamber, a secondary air passageway feeding into the burn chamber, and at least one barometric damper connected to the housing and configured to selectively allow air into the primary and secondary air passageways. The biomass furnace further includes a combustion fan connected to the housing. The combustion fan is configured to intake and forcibly blow warm air into the primary air passageway and the secondary air passageway, generating a forced draft for primary and secondary combustion and selectively closing the at least one barometric damper.
Reference will now be made in detail to optional embodiments of the invention, examples of which are illustrated in accompanying drawings. Whenever possible, the same reference numbers are used in the drawing and in the description referring to the same or like parts.
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention.
To facilitate the understanding of the embodiments described herein, a number of terms are defined below. The terms defined herein have meanings as commonly understood by a person of ordinary skill in the areas relevant to the present invention. Terms such as “a,” “an,” and “the” are not intended to refer to only a singular entity, but rather include the general class of which a specific example may be used for illustration. The terminology herein is used to describe specific embodiments of the invention, but their usage does not delimit the invention, except as set forth in the claims.
As described herein, an upright position is considered to be the position of apparatus components while in proper operation or in a natural resting position as described herein. Vertical, horizontal, above, below, side, top, bottom and other orientation terms are described with respect to this upright position during operation unless otherwise specified. The term “when” is used to specify orientation for relative positions of components, not as a temporal limitation of the claims or apparatus described and claimed herein unless otherwise specified. The terms “above”, “below”, “over”, and “under” mean “having an elevation or vertical height greater or lesser than” and are not intended to imply that one object or component is directly over or under another object or component.
The phrase “in one embodiment,” as used herein does not necessarily refer to the same embodiment, although it may Conditional language used herein, such as, among others, “can,” “might,” “may” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without operator input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment.
With reference to the provided drawings, the present disclosure provides a biomass furnace. The provided drawings are CAD drawings drawn to scale. However, it will be appreciated that other dimensions are possible. In the drawings, the arrows represent airflow. The features described herein may be combined in any desired combination.
Referring generally to
The primary air system 16 is in the form of a forced draft system 16 that intakes primary air entering through a primary air inlet 34 at the front of the housing 12, next to and above a fuel loading door 36 selectively sealing a fuel loading opening 37 (
The secondary air system 18 is also in the form of a forced draft system 18 that intakes secondary air from the preheating chamber 38 at the front of the housing 12, as supplied by the combustion blower 30 when running and/or the open barometric dampers 32 (when the blower 30 is not running, unless manually opened as desired). The secondary air system 18 comprises a trunk assembly 54 which defines the secondary air passageway that feeds into the burn chamber 14. The trunk assembly 54 generally includes a main tube 56 fluidly connected to the preheating chamber 38 at its front opening 58, branch tubes 60 extending outwardly from the main tube 56, and an anterior trunk chamber 62. As discussed in more detail below, respective apertures 64, 66, 68 in the main tube 56, the branch tubes 60, and the trunk chamber 62 direct the preheated air into the top of the burn chamber 14. Hence, the biomass furnace 10 is configured to provide forced draft primary and secondary combustion by way of the combustion fan 30 forcing preheated air into the burn chamber 14 via the pilot hole 50 (the primary air passageway) and the trunk assembly 54 (the secondary air passageway).
The distribution fan(s) 28, located at the bottom rear of the housing 12, intake and blow relatively cool air into distribution ductwork 70, e.g., one or more ducts 70, within one or more walls of the housing 12 surrounding the burn chamber 14 (
In some embodiments, there is provided a biomass furnace 10 comprising one or more of the following features: a housing 12 that may include a front wall 72, a rear wall 74, a thickness 76 extending from the front wall 72 to the rear wall 74, a bottom 78, a top 80, a height 82 extending from the bottom 78 to the top 80 and perpendicular to the thickness 76, and a width 84 perpendicular to the thickness 76 and the height 82 (FIG.
2). In one embodiment, the front wall 72, the rear wall 74, the bottom 78, and the top 80 define a housing interior 86 comprising the burn chamber 14 configured to hold a biomass undergoing combustion. In one embodiment, the front wall 72 comprises the fuel loading opening 37 configured to load the biomass fuel into the burn chamber 14 and the fuel loading door 36, with a handle 88 thereon, to open and close the fuel loading opening 32.
The biomass fuel rests on the bottom of the burn chamber 14. Ashes from the biomass fuel can pass through a grate 90 and into an ashpan 92, which can be emptied as desired via an ashpan door 94. In one embodiment, the housing 12 comprises the air inlet 34 in gaseous communication with the burn chamber 14, which is configured to feed air from the exterior environment into the housing interior 86. In one embodiment, the housing 12 comprises the air outlet 42 in gaseous communication with the burn chamber 14, which is configured to feed air, warmed by the biomass furnace 10, into the chimney connector 40 (and from the housing interior 86 to the exterior environment therearound).
In one embodiment, the longitudinal main tube 56 i) may be located above the burn chamber 14, ii) may include the front opening 58 iii) may include a main tube interior 96 in gaseous communication with the front opening 58, and/or iv) that may extend toward the rear wall 74 of the housing 12. The secondary air system 18 may also include the plurality of branch tubes 60 that may be attached to and/or oriented transverse to the longitudinal main tube 56 and/or that may include branch tube interiors 98 (as shown in
In one embodiment, the main tube 56 is located approximately in the center of the housing width 84. In one embodiment, the main tube 56 comprises a main tube length 100 extending generally parallel to the housing thickness 76. In one embodiment, some or all of the branch tubes 60 comprise a branch tube length 102 extending parallel to the housing width 84. The main tube 56 extends from a front 104 to a rear end 106. The main tube 56 may extend across the top of the burn chamber 14.
In one embodiment, the secondary air system 18 further comprises the trunk chamber 62 located underneath and at the rear 106 of the main tube 56. The interior of the trunk chamber 62 may be in gaseous communication with the front opening 58 of the main tube 56. The trunk chamber 62 a top wall 108, a bottom wall 110, side walls 112, a rear wall 114, and the front wall 116 with the plurality of apertures 68 therein. The rear wall 114 can define the rear wall of the rear end 106 of the main tube 56. The trunk chamber 62 can be wider than the width of the main tube 56, and in some embodiments, wider than the collective width of the main tube 56 and the branch tubes 60. The front wall 116 extends downwardly and transverse to the main tube 56. As shown in
In one embodiment, the chimney connector 40 is located adjacent to the top 80 of the housing 12. In embodiment, one or more combustion fans 30 are located adjacent to the chimney connector 40.
In one embodiment, as shown in
In more detail, the thermostat 24 and the limiter device 26 can work in tandem to automatically control the operation of the combustion fan(s) 30, based upon preset temperature limits of the thermostat 24. The limiter device 26 can be mounted on ductwork, just above the air discharge atop the biomass furnace 10 (unnumbered). The limiter device 26 includes a probe (not shown) for reading the furnace plenum temperature. The limiter device 26 is operably connected to the thermostat, via a wired and/or wireless connection, and accordingly the limiter device 26 sends its temperature readings to the thermostat 24. The limiter device 26 is operably connected to the distribution blowers 28 and the combustion blower 30 via a junction box 122 (
In operation, when the thermostat 24 is calling for heat, the combustion fan 30 may run (max duty cycle) and when the thermostat 24 is not calling for heat the combustion fan 30 may cycle off (min duty cycle). When the combustion fan 30 is cycled off, the dampers 32 are configured to open, via the natural draft, to feed the primary and secondary air systems 16, 18 with enough air to have clean combustion during the minimum duty cycle.
In one embodiment, in addition to directing secondary air directly toward the burn chamber 14, one or more components of the secondary air system 18 (e.g., the branch tubes 60) can be configured to direct secondary air along an inclined interior wall 124, which can be comprised of firebrick, which is located above the branch tubes 60 (e.g., sloping downwardly towards the rear wall 74). The inclined interior wall 124 can assist in further heating air as the air winds back and forth through a series of baffles 126 toward the air outlet 42.
In one embodiment, the biomass furnace 10 further includes an inclined interior wall located above the branch tubes, a portal located in the rear wall, a duct in the top, and a duct in the front wall. In addition to directing secondary air directly toward the air chamber, one or more components of the secondary air system can be configured to direct secondary air along the inclined interior wall located above the branch tubes, through the portal located in the rear wall, along the duct located in the top, along the duct located in the front wall, and into the burn chamber.
In one embodiment, there is provided a biomass furnace 10 comprising one or more features shown in the provided drawings. In one embodiment, there is provided a biomass furnace 10 circulating and warming air as exemplified by one or more of the arrows shown in the provided drawings.
This written description uses examples to disclose the invention and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
It will be understood that the particular embodiments described herein are shown by way of illustration and not as limitations of the invention. The principal features of this invention may be employed in various embodiments without departing from the scope of the invention. Those of ordinary skill in the art will recognize numerous equivalents to the specific procedures described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.
All of the compositions and/or methods disclosed and claimed herein may be made and/or executed without undue experimentation in light of the present disclosure. While the compositions and methods of this invention have been described in terms of the embodiments included herein, it will be apparent to those of ordinary skill in the art that variations may be applied to the compositions and/or methods and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit, and scope of the invention. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope, and concept of the invention as defined by the appended claims.
Thus, although there have been described particular embodiments of the present invention of a new and useful BIOMASS FURNACE WITH FORCE DRAFT PRIMARY AND SECONDARY COMBUSTION it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.
This application is a non-provisional application of and hereby claims priority to U.S. Provisional Patent Application No. 63/440,661 entitled “BIOMASS FURNACE WITH WARMED SECONDARY COMBUSTION AIR”, filed on Jan. 23, 2023.
| Number | Date | Country | |
|---|---|---|---|
| 63440661 | Jan 2023 | US |
