Patent Application
20060003276
The present invention generally relates to fireplaces, and more specifically relates to fireplaces that use hydrogen as a source of fuel.
The use of hydrogen as a source of fuel has gained increased popularity in recent years as technology related to the production of hydrogen has improved and the public perception of safety related to hydrogen has gradually changed. Hydrogen fuel has many benefits and advantages over other commonly used sources of fuel. For example, combusting petroleum products (e.g., natural gas and liquid propane) and fibrous products (e.g., wood) in a heating appliance generates harmful gases such as carbon monoxide (CO) that must be exhausted. Providing exhaust vent systems for a heating appliance adds significant cost, time and space requirements when installing the heating appliance. In contrast, the byproducts of generating and combusting hydrogen are oxygen (O2) and water (H2O). These byproducts are not only safe for the environment, but are also desirable products that can be used for alternative purposes in a beneficial way. Thus, an exhaust system is not required when combusting hydrogen.
An associated advantage of combusting hydrogen relates to proper venting of an open front fireplace structure. Open front fireplaces typically have a certain amount of the combustion gases that spill out of the fireplace front, especially under conditions of back draft in the fireplace exhaust vent or negative pressure in the living space. Thus, the use of open front fireplaces for combusting typical fuels (e.g., petroleum based and fibrous products) has become very limited in the recent past due in part to higher air quality standards and an increases awareness of safety issues related to combustion gases. As noted above, byproducts of combusting hydrogen do not have to be exhausted, thus removing limitations to the use of an open front fireplace.
Another advantage with using hydrogen as a source of fuel relates to the relative simplicity of generating hydrogen fuel itself. Water is commonly used as a basis for hydrogen fuel production. In one example, sodium hydroxide is mixed with aluminum and water; the chemical reaction of which produces hydrogen gas. Another example hydrogen production system is an electrolyzer that generates hydrogen by charging water particles to create a polarity and then splitting the water particles with a charged proton exchange membrane. Many other types of hydrogen production are known or are being developed for use.
The use of hydrogen as a fuel also has some disadvantages. One disadvantage relates to storage of hydrogen and delivery of hydrogen to an end user. Unlike natural gas and other petroleum based and fibrous materials that are used for energy, there is presently no infrastructure or system established for mass production and/or delivery of hydrogen fuel to an end user. As a result, the hydrogen fuel must be generated on site or delivered in relatively small quantities. Two example storage methods for hydrogen fuel are a pressurized tank in which the hydrogen fuel displaces water also contained in the tank, and a metal hydride foam which when charged with one polarity is able to retain hydrogen and when charged in the opposite polarity releases the hydrogen.
The use of hydrogen as a fuel to create a decorative flame or to produce heat in a heat generating appliance also has some disadvantages. One disadvantage relates to the appearance of combusting hydrogen as a decorative flame. Combusting hydrogen is relatively colorless and the flame is relatively hot compared to flames of other known combustible materials. Also, the flame appearance is linear and involves very little movement of the flame itself (flame movement being known generally as “flicker”). Decorative flames typically have a yellow or orange tint and flicker significantly at any flame size.
Structures and methods relating to combusting hydrogen in a heating appliance that address these and other disadvantages of combusting hydrogen would be an advance in the art.
The present invention generally relates to fireplaces, and more specifically relates to fireplaces that use hydrogen as a source of fuel. One aspect of the invention relates to a gas fireplace that includes a combustion chamber enclosure, a burner, and a flame enhancement member. The combustion chamber enclosure defines a combustion chamber. The burner is disposed in the combustion chamber and defines apertures positioned to provide hydrogen gas to a surface of the burner for combustion. The flame enhancement member is positioned relative to the surface of the burner to engage the combusting hydrogen thereby improving visibility of the combusting hydrogen.
Another aspect of the invention relates to a burner for use in a hydrogen burning appliance that includes a gas enclosure defining a gas distribution chamber and a gas aperture, a burner having a combustion surface, a hydrogen gas source coupled to the gas enclosure, and a flame enhancement member positioned in a path of the combusting hydrogen. The hydrogen gas source supplies hydrogen gas to the gas chamber for distribution to the gas aperture for combustion of the hydrogen gas at the combustion surface.
A further aspect of the invention relates to a method for generating a visible hydrogen flame. The hydrogen flame is provided in a gas enclosure that defines a gas distribution chamber and a combustion surface having a gas aperture formed therein. The method includes supplying hydrogen gas to the gas distribution chamber, passing the hydrogen gas out of the gas aperture, combusting the hydrogen gas at the combustion surface, and passing the combusting hydrogen gas through a flame enhancement member to alter a color of the combusting hydrogen gas.
Another aspect of the invention relates to a fire display assembly that includes a burner, a flame enhancement member, and a support platform. The burner defines apertures positioned to provide hydrogen gas to a surface of the burner for combustion. The flame enhancement member is positioned relative to the surface of the burner to engage the combusting hydrogen thereby improving visibility of the combusting hydrogen. The platform is configured to support the burner and flame enhancement member from vertically beneath the burner and flame enhancement member. The burner is open to ambient air on all sides such that the fire display assembly is configured as an open fire pit.
The above summary of the present invention is not intended to describe each disclosed embodiment or every implementation of the present invention. Figures in the detailed description that follow more particularly exemplified embodiments of the invention. While certain embodiments will be illustrated and described, the invention is not limited to use in such embodiments.
The invention may be more completely understood in consideration of the following detailed description of various embodiments in the invention and in connection with accompanying drawings, in which:
While the invention is amenable to various modifications and alternate forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the invention is not limited to the particular embodiments described. On the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
The present invention generally relates to fireplaces, and more particularly relates to fireplaces that use hydrogen as a source of fuel. The present invention also relates to methods of generating a visible hydrogen flame, methods of generating, storing, and delivering hydrogen to a hydrogen burner in a fireplace, and other methods and structures related to the use of hydrogen as a fuel in heating appliances such as fireplaces.
While the example embodiments of the present invention provided below are described in connection with example fireplaces, the present invention may be applicable to other systems or apparatuses such as furnaces and stoves. Principles of the present invention may be embodied in retrofit configurations that can be applied to existing fireplaces. Further, common venting systems and fireplace configurations such as a direct vent, a universal vent, a B-vent, a horizontal/vertical-vent, a dual direct vent, and a multisided unit having two or three glass panels as combustion chamber side panels may be used to exhaust unwanted byproducts (heat, water (H2O) or oxygen (O2)) of combusting hydrogen fuel. Such common venting systems and fireplace configurations may include an adjustable baffle member (not shown) that controls the flow of combustion byproducts into a venting system as desired (e.g., exhausting heat and water byproducts during the warmer summer months and not exhausting heat and moisture byproducts during colder, dryer winter months). While the present invention is not so limited, an appreciation of various aspects of the invention will be gained through a discussion of the examples provided below. Principles of the present invention may be best recognized in applications in which the combusting hydrogen is viewable as a decorative flame.
As used herein, a “combustion chamber” may include any structure that at least partially encloses a space in which a flame, simulated flame, or flame-related effect is generated by, for example, combusting material or generating a flame-related effect such as sound or light. A “combustion chamber” may be defined by one or more panels that permit viewing through the panel. A “combustion air enclosure” is defined as any enclosure that defines a chamber for holding combustion air for use in the combustion chamber. A “combustion fuel enclosure” is defined as any enclosure that defines a chamber for holding combustible fuel. A “flame enhancement member” is any solid material such as, for example, metal, metal alloy, or other material that alters a property of the combusting hydrogen. In one example, the flame enhancement member is a metal member that alters the visible color of the combusting hydrogen by, for example, ionizing the combusting hydrogen.
One example fireplace assembly 10 that includes features related to combustion of hydrogen is described and illustrated with reference to
The outer enclosure 12 may include an exhaust aperture 20, an intake vent 22, and an exhaust vent 24, although some or all of these features may not be required because of the limited combustion air requirements and the clean combustion byproducts of combusting hydrogen. The combustion chamber enclosure 14 includes rear, bottom, side, and front panels 30, 32, 34, 36, which together define a combustion chamber 38, wherein combustion of hydrogen occurs for the generation of heat. The panels of the combustion chamber enclosure 14 may include materials such as, for example, sheet metal, molded fiber material, or a combination of these materials. In one embodiment, the combustion chamber enclosure is constructed of a moldable material like that described in U.S. patent application Ser. No. 09/781,148, incorporated herein by reference.
Typically, the combustion chamber enclosure 14 is positioned within the outer enclosure 12 such that a plenum is defined there between in which air drawn in through the intake vent 22 can be heated by heat emanating from the combustion chamber 38 through the panels 30, 32, 34, 36. The heated air may be exhausted out of the exhaust vent 24 back into a living space, or vented to a remote location. Preferably, the combustion chamber enclosure is open at a front surface thereof to provide a more realistic fireplace setting. Because the byproducts of hydrogen combustion pose no health risks, the venting issues common to known open front fireplaces are not relevant; with the possible exception of venting heat.
A front panel (not shown) made of a clear material that provides viewing of the combustion chamber 38 while sealing the combustion chamber 38 may be included in some embodiments. The addition of a front panel (either a fixed or removable panel) may improve safety and help control venting of the combustion byproducts. Still further embodiments may include modified panels of the combustion chamber enclosure 14 to alter the flow of air and combustion products into and out of the combustion chamber 38. For example, one embodiment may include a bottom panel 32 having a plurality of apertures formed therein and the fireplace includes a blower or a plurality of blowers positioned in fluid communications with the apertures so as to provide either a stream of fresh air into the combustion chamber or to provide a suction force that draws combustion products and heat out of the combustion chamber.
The burner assembly 16 includes a valve 40, a first fuel line 42, a base 44, an ignition/pilot system 46 having a thermopile 48 and a pilot burner 49, a tube burner 50, a flame enhancement member 52, and a second fuel line 54. The first fuel line 42 is coupled to the fuel source 19, and the second fuel line 54 couples the valve 40 to the tube burner 50. Typically, the fuel source 19 provides hydrogen gas for combustion. Alternatively, mixtures of hydrogen gas and other combustible gases, such as natural gas and propane, can be burned within the combustion chamber enclosure. The amounts of hydrogen and other gases can be metered, regulated, or prepared to modify the heat of combustion and visual appearance of the flame.
The fuel source 19 can be placed within the plenum created between the combustion chamber enclosure 14 and the outer enclosure 12. Alternatively, the fuel source 19 can be located in remote location and the hydrogen gas can be supplied for combustion by a supply line. One hydrogen generating fuel source is an electrolyzer. An exemplary electrolyzer can be obtained from HYDROGENICS located in Mississauga, Ontario, Canada.
As shown in
The ignition system 46 may be any system or device that ignites the hydrogen fuel to begin combustion of hydrogen at the burner 50. The thermopile 48 is designed to recognize the presence of combusting hydrogen fuel. When the thermopile 48 recognized the presence of combusting hydrogen via the pilot burner 49, then the ignition system signals the valve 40 to deliver hydrogen fuel to the burner 50 for combustion. When the thermopile does not recognize the presence of combusting hydrogen, it will stop the flow of gas through the valve. Additionally, a signal can be sent to the electrolyzer to stop the production of hydrogen and protect the closed valve from damage due to pressure.
A hydrogen flame does not conduct electricity sufficient for known flame conduction and rectification systems to operate properly. Known thermocouples respond relatively slowly, which would make a hydrogen flame sensing method that uses a known thermocouple dangerous because a potentially dangerous amount of hydrogen could accumulate before the thermocouple responds. The use of example circuitry 900 shown in
The example circuit 900 may function as follows: Resistors R2, R1 and amplifier IC1A produce a steady state gain of 2. Capacitor C1 and R2 with the amplifier IC1A form a differentiator, the maximum gain being limited by C2. Capacitors C3, C2 and C4 act as filters, decreasing the sensitivity to noise ratio, which is advantageous because differentiation is an inherently noisy process. Transistor Q1 pulls the diode D1 to ground and R4 provides a light load so that flame sensing circuitry (not shown) of ignition/pilot system 46 senses a flame. The other half of the amplifier IC1A is not used, but is merely coupled so as to minimize the current drain. A standard thermocouple could also be used if the gain of the circuit were increased. Such a thermocouple could also be adapted to drive the valve 40 in other configurations with different components of the ignition/pilot system 46 removed or modified.
Referring again to
The flame enhancement member 52 may include a porous structure that permits passage of combusting hydrogen through the material. Some example porous structures include foam, mesh, and screen structures. Other material structures besides foam structures may also be used so long as the combusting hydrogen can pass through, around or otherwise in contact with the flame enhancement member such that the color of the combusting hydrogen is at least partially changed as a result of contact between the combusting hydrogen and the flame enhancement member. Member 52 may include metals, metal alloys, and other substances that alter an appearance of the flame by, for example, ionizing the combusting hydrogen due to the intense heat generated by the combusting hydrogen to provide coloring of the resulting flame. In one example, the use of a flame enhancement member 52 that includes nickel provides yellow coloring of the flame. Some further example materials that generate specific colors when contacted by a flame are listed in the following Table I.
In order to produce a realistic appearing flame or at least a flame that more closely resembles a combusting fibrous material (e.g., wood), the combusting hydrogen is preferably changed to yellow, orange, or red color, or a combination of these colors.
To further enhance the “realistic” appearance of the combusting hydrogen, a blower may be positioned in proximity to the burner to provide a flow of air that alters a position of the combusting hydrogen flame. Such a blower may be modulated thereby providing a modulated air flow that contacts the combusting hydrogen to give the appearance of a modulating flame, which is also common to a flame emanating from a burning fibrous product such as wood.
An example fireplace 800 that includes a blower 804 is shown and described with reference to
The blower 504 may be controlled by a controller (not shown) that modulates or otherwise controls the flow of air from the blower 804, thereby further altering the flame 851. Control of the blower 504 may be synchronized with other controlled features of the fireplace 800 such as the flow of fuel from the fuel source 819 to the burner 850, lighting (not shown) and sound (not shown).
A blower may also be used as part of a heat recovery system such as the heat recovery system shown and described in U.S. Pat. No. 6,550,687, which is incorporated herein by reference in its entirety. A heat recovery system associated with the fireplace 10 may also include a moisture recovery and oxygen recovery system (water and oxygen being the by products of hydrogen combustion) (system not shown), which products can be recycled and reused by the fireplace 10 or for other desired purposes.
The fuel source 19 may be any hydrogen generating system that is capable of generating hydrogen fuel and is sized to be disposed within the outer enclosure 12, for example, below the combustion chamber enclosure 14. In other embodiments, the fuel source 19 may be positioned at a remote location from the fireplace 10 and fuel source 19 is coupled to the burner assembly via the first fuel line 42. In still further embodiments, the fuel source 19 and burner assembly 16 may be portable devices that can be moved from one heating appliance to another or function separate from a heating appliance such as, for example, as a fire pit or a fire display device in an outdoor area or within a building structure.
Certain features of the burner assembly 16 may be interchangeable with alternative features that have different designs and functions. For example, the tube burner 50 and flame enhancement member 52 may be replaced with the example pan burner 116 shown in
An example of a shaped flame enhancement member is shown in
Another example burner assembly 316 is shown with reference to
Another example pan burner 550 that includes a molded flame enhancement member 552 is shown with reference to
Referring now to
The stand alone burner assembly 216 may be used without an exhaust ventilation system as is commonly required for typical decorative fire display devices burning known combustion products such as natural gas and fibrous products. As a result, the assembly 216 could be used in an open room of an enclosed living space without any danger of pollution or the release of harmful substances into the room air. Combusting hydrogen may actually provide an added benefit of increasing the moisture content of the room air and oxygenizing the room air for improved living comfort and health of those residing with the living structure. Alternatively, the oxygen byproduct can be delivered to the combusting hydrogen to aid in combustion. A system or device can be utilized that meters or regulates the amount of oxygen being directed to the combusting hydrogen gas.
Referring now to
The light source 608 is positioned vertically below the smoke simulator 660 in
Referring now to
The display 700 may be a portable device that can be positioned at any location inside or outside of a living structure. The display 700 may include a self-generating source of fuel such as an electrolyzer that is powered by power cord 707. Alternatively, the electrolyzer can be powered from the wind, solar energy, a generator, battery power, or any combination of these power sources. For example, solar energy can be stored onto batteries for use as needed. Cord 707 may provide power for the ignition system 746, light source 708, and smoke simulator 760.
The display 700 may include a protective viewing panel (not shown) that extends at least partially around the burner 750, for example, around a periphery of the platform 714, to prevent users from accidentally touching the heated burner 750 or other objects heated by the flame 751. Other embodiments may include one or more wall structures that surround the burner to provide, for example, a background such as a brick wall, while the display 700 is open vertically above the burner. Other embodiments may also include a covering oriented vertically above the burner with no surrounding wall structures for the purpose of, or example, protecting the burner from rain when using the display 700 in an outdoor setting while maximizing viewing of the combusting hydrogen from all sides.
The burners and ignition/pilot systems described above may be configured to combust a mixture of hydrogen and alternative fuels. For example, hydrogen fuel may be mixed with liquid propane or natural gas in a fuel mixing chamber at the fuel source or at any other location prior to combustion at the fuel aperture on the surface of the burner. In other embodiments, the pilot light of the system may burn hydrogen while the main burner burns an alternative fuel, or visa versa. In still further embodiments, the burner may be configured with separate apertures at the combustion surface for different fuels. Burning a mixture of hydrogen and an alternative fuel may provide advantages of improved emissions and higher efficiency as compared to burning the alternative fuel alone.
The burners described herein may include any desired materials that would be appropriate for use in this high temperature application. For example, the burner may be a metal member having certain features that are formed using stamping or other forming techniques, while other embodiments may include molded or caste burners. Likewise, the flame enhancement members may be formed using similar methods and may be formed separately or integrally with the burner.
The burners, fireplaces, and systems disclosed herein may be operable using some basic steps of operation illustrated in the exemplary process diagram of
The present invention should not be considered limited to the particular examples or materials described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention may be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the instant specification.
