Patent Application
20250137645
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.
This application claims priority to and hereby incorporates by reference in its entirety U.S. Provisional Patent Application Ser. No. 63/593,575 filed Oct. 27, 2023 entitled “BIOMASS SECONDARY COMBUSTION STOVE WITH EXHAUST MIXER.”
Not Applicable
The present invention relates generally to biomass stoves. More particularly, this invention pertains to small wood burning stoves.
Biomass stoves can burn different biomass such as peat, wood logs, and wood pellets. Large biomass stoves with secondary combustion systems have higher burn rates and thus airflow rates than smaller stoves. This promotes mixing of exhaust gases. Large biomass stoves also have large exhaust tubing (i.e., flue tubing). When miniaturizing these stoves, burn rates and airflow rates reduce such that fluctuations in exhaust gas temperatures are common. This can make determining safe size, length, and spacing for combustible materials from the exhaust gas tubing difficult. While upsizing the exhaust gas tubing and increasing recommended setoffs for combustible materials is one potential solution, this reduces the places where such a miniaturized biomass stove can be installed. That is, making safe small biomass stoves for small rooms becomes difficult because of hot spotting within the exhaust gas tubing (e.g., exhaust gas outlet and flue).
Aspects of the present invention provide biomass combustion stove with an exhaust gas mixer. The exhaust gas mixer is positioned at the exhaust gas outlet flue of the stove. That is the exhaust gas mixer is positioned within the path of exhaust gases exiting the stove burn chamber at the point where the exhaust gases exit the burn chamber, above a baffle of the stove. The exhaust gas mixer may be a cone, a pair of opposing cones, a sphere, turbine, propeller, partial helical, or fan configured to promote mixing or turbulence of the exhaust gases as they exit the stove. In one embodiment, the stove provides some room air to the exhaust gas outlet to cool the exhaust gas tubing (e.g., outlet flange and flue) as the exhaust gases exit the stove.
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. The upright position of the stove disclosed herein is when properly installed on a generally horizontal surface such as show at, for example,
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.
Referring now to
In one embodiment, an exhaust gas mixer 131 is mounted to or within the exhaust gas outlet 115 when then stove 100 is assembled. In one embodiment, the exhaust gas mixer 131 is mounted within the outlet flange 117 where the flange 117 passes through the housing 105. In one embodiment, the exhaust gas mixer 131 is formed of metal. In another embodiment, the exhaust gas mixer 131 is ceramic. The exhaust gas mixer 131 is generally centered within the exhuast gas outlet 115, cylindrical outlet flange 117, and/or flue. The exhaust gas mixer 131 may be shaped as a pair of opposing cones, a sphere, a helix, or a number of other shapes. The purpose of the exhaust gas mixer 131 is to mix exhaust gases as they leave the housing 105 and burn chamber 103 to prevent hot spots in the flue. The exhaust gas mixer 131 may accomplish this mixing by speeding airflow and then slowing it (e.g., such as with a sphere or pair of opposing cones), or by providing turbidity within the air (e.g., such as with a helix or screw shape). Preventing hot spots in the flue reduces the risk of fire from articles or materials located in close proximity to the flue.
In one embodiment, the biomass stove 100 includes the burn chamber 103, exhaust gas outlet 115, and exhaust gas mixer 131. In one embodiment, the stove 100 has a maximum designed heat output of no more than 25000 BTU of heat. The burn chamber 103 is configured to receive combustion air and biomass such that combustion of the biomass occurs within the burn chamber 103.
The exhaust gas outlet 115 is configured to receive exhaust gases from the burn chamber 103 and convey the received exhaust gases to a flue (which conveys the exhaust gases outside of the room in which the stove 100 is installed). In one embodiment, the exhaust gas outlet 115 includes the outlet flange 117 extending from the burn chamber 103. The outlet flange 117 is configured to connect to the flue. In one embodiment, the outlet flange 117 and flue are cylindrical (e.g., tubular). In one embodiment, the stove 100 further includes one or more standoffs 305 configured to connect the exhaust gas mixer 131 to the burn chamber 103 at the outlet flange 117. The standoffs 305 may alternatively be connected to the outlet flange 117 to support the exhaust gas mixer 131 within the scope of the claims. In one embodiment, standoffs 305 center the exhaust gas mixer 131 within the outlet flange 117. In one embodiment, the outlet flange 117 extends upward from the burn chamber 103 (i.e., a top of the burn chamber) when the stove 100 is in the upright position.
The exhaust gas mixer 131 is positioned within the exhaust gas outlet 115 when the biomass stove 100 is assembled. The exhaust gas mixer 131 is configured to disrupt flow of exhaust gases from the burn chamber 103 to the flue such that the exhaust gases have reduced temperature variance within the flue. In one embodiment, the exhaust gas mixer 131 is a pair of opposing cones, a helix, or a spiral. In the embodiment where the exhaust gas mixer 131 is a pair of opposing cones, each cone of the pair of opposing cones has a based joined to a base of the other cone such that a top and a bottom of the exhaust gas mixer are points of the pair of opposing cones. In one embodiment, the exhaust gas mixer 131 extends above the outlet flange 117. In one embodiment, the exhaust gas mixer 131 does not extend into the burn chamber 103. That is, the exhaust gas mixer 131 does not extend down below a top wall 331 of the burn chamber 103. In one embodiment, the exhaust gas mixer 131 is above the top wall 331 of the burn chamber 103 when the stove 100 is assembled and in the upright position, and in another embodiment, the exhaust gas mixer 131 is even above the top of the housing 105 when the stove 100 is assembled and in the upright position.
In one embodiment, the stove 100 further includes a combustion air intake flange 303 and a combustion air regulator 301. The intake flange 303 is configured to receive combustion air and provide the received combustion air to the burn chamber 103 via the regulator 301. In one embodiment, the intake flange 303 is generally tubular and configure to receive combustion air from outside the room in which the stove 100 is located in order to prevent depletion of oxygen within the room due to the oxygen being used for combustion. The regulator 301 is configured to modulate flow volume of combustion air provided to the burn chamber 103 as a function of input form a user such that a burn rate and heat output of the stove 100 is determined as a function of the input form the user to the combustion air regulator 301. In one embodiment, the regulator 301 has a knob configured to slide a plate in order to open or close passage(s) in the regulator that provide combustion air to a primary combustion air path and a secondary combustion air path within the stove 100. The primary combustion air path feeds primary combustion air under the burn chamber into the burn chamber at the bottom front of the burn chamber 103. The secondary combustion air path feeds secondary combustion air up the lateral sides of the burn chamber 103 (preheating the air as it travels) and into secondary air tubes 151 which are configured to provide the preheated secondary combustion air to the burn chamber 103 when the stove 100 is burning biomass in the burn chamber 103. In one embodiment, the stove 100 further includes a first baffle 111, a second baffle 113, and the top wall 331 defining a top of the burn chamber 103. The first baffle 111 is over the plurality of secondary air tubes 151, and the second baffle 113 is over the first baffle 111. In one embodiment, exhaust gases rise up around a front of the first baffle 111 and up to the top wall 331 over the second baffle 113 at a rear or back of the second baffle 113. In one embodiment, the first and second baffles 111, 113 are higher toward the front of the stove than toward the rear of the stove 103. The front of the stove 100 is at a door of the stove 100 (i.e., the door by which biomass is provided to the combustion chamber 103 by the user).
In one embodiment, the stove 100 further includes a stand 300 configured to support the burn chamber 103 and space the burn chamber 103 from a surface supporting the stove 100 (e.g., the floor of the room in which the stove 100 is installed). In one embodiment, the stand 300 supports and houses the combustion air intake (e.g., intake flange 303) and combustion air regulator 301 beneath the burn chamber 103.
In one embodiment, the stove 100 further includes room air blower 107 configured to force air from the room through the space 109 between the housing 105 and the burn chamber 103. In one embodiment, the housing 105 does not contact outlet flange 117 such that there is a gap 335 between the housing 105 and the outlet flange 117. Thus, air from the room air blower 107 passes through the space 109 between the housing 105 and the burn chamber 103 and through the gap 335 back into the room in which the stove 100 is installed when the room air blower 107 is operating. Room air being forced through the gap 335 acts to cool the outlet flange 117 and flue, which also increases the heat transfer efficiency of the stove 100.
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 SECONDARY COMBUSTION STOVE WITH EXHAUST MIXER 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.
| Number | Date | Country | |
|---|---|---|---|
| 63593575 | Oct 2023 | US |
