The present invention related to biomass-burning stoves, particularly camping and hunting stoves
In outdoor and hunting activities, wood-burning stoves are commonly used to warm a tent or cabin. The stove may be of the open fire, dosed box or gasifier type. The latter is more efficient, employing secondary burning to burn wood gas that is emitted from the primary burn stage. The smaller of these are portable but do not produce much heat for warming a space. Large wood burning stoves may be powerful but very heavy. In certain applications it is desirable to have a portable and yet powerful stove for easily transporting to and heating large recreational living spaces.
Present inventions of the preferred embodiment may be described with reference to the following figures in which like references correspond to like parts, in which:
In general, the present invention provides a gasifier stove, particularly those used to warm up a cabin or tent.
According to one aspect there is a biomass-burning stove comprising: an outer housing; a biomass-burning chamber located within the outer housing and spaced-apart from a wall of the outer housing, the chamber having a biomass-receiving base at its bottom and baffle plate at its top; a chimney connectable to the outer housing at a location above the baffle plate; first air vents in the housing for directing air to the base of the burning chamber, which first vents are variable in area; and second air vents in the outer housing for supplying air to third air vents at the top of the burning chamber.
The invention will now be described in detail with reference to the accompanying drawings. Provided are apparatus and methods for using a gasifier stove.
One preferred form of the stove is that of a double-walled housing, created by an inner housing 30 with burning chamber an outer housing 35 surrounding and spaced apart from the inner chamber, with venting therebetween to control primary 5 and secondary air 15 inlet flow for primary and secondary burning. As shown in
A baffle 34 at the top of the burning chamber, controls the exit of wood gas and air to optimize the mixing and burning in the secondary stage. Preferably the area of vents 32 and 36 are similar to each other. Preferably each of these vent areas are between 50% and 120% of the area of variable vent 22 in the fully open setting.
Removable ashtray 31 is located below the burning chamber and receives ash from the burned biomass, which drops through holes in the base of that chamber. As shown in
First vents 22 in the outer housing control air flow to the primary burning. The area of these vents is variable to optimize the present combustion stage, i.e. different air flow rates are required for starting combustion versus medium and high burn rates. In preferred embodiments the venting area is controlled by knob 25 which provides finer control of the vent opening then is possible with a sliding vent. The knob controls the vent area via gear 23 that slides a first plate with holes 22B over vents 22A in the housing. Thus the knob is coupled to the vent to translate user rotation into linear vent control. In a preferred embodiment there are a plurality of vent holes 22B, whereby additional discrete vents 22A are opened with every indexing of the control knob 25.
Advantageously, as shown in
The vents 32 and 36 for the secondary burning may also be of variable type to control the rate of secondary burning relative to primary burning. The skilled person will appreciate that the size shape in orientation of the events may be varied and remain within the scope of the invention.
As shown in
As shown in
Collapsible legs 40 are mounted to the outer housing to lift the stove off the ground in an extended position, while still being small enough to be portable in the stowing position. Springs 58 and locking mechanism 59 bias and hold the legs to lock into the extended position for use, while relieving the force on the spring enables the leg to be released from the lock to collapse against the base of the housing for stowing. Typically there will be three or four legs for a stove
The hot burned gases are removed from the stove via the chimney 60 which is mounted at the top and back of the housing. For improved portability, the chimney may be comprised of plural segments that are connectable or nestable to each other. As shown in
The exit to the chimney is directed to an exit of the living space or through a pipe jack in a tent. The chimney may include a damper to adjust exit flow during burning or block flow when not in use.
The top of the outer housing may be used as a cooking service, either by simply placing cookware on top of it or by removing plates on the top of the outer housing to expose the flame.
Without being limited to any modality or particular theory of operation, the stove is intended to work as follows. Biomasses is loaded into the base of the burning chamber with the largest biomass on bottom and lighter kindling on top. The kindling is then ignited. At this point the vent is already set to its lowest level, so as to start the fire without putting it out. After several minutes, the heat from the lit kindling will ignite the lower and heavier biomass, such as logs. Eventually wood gas will be released from the larger biomass through pyrolysis (degeneration of the wood components in the absence of oxygen). This wood gas will collect at the top of the burning chamber, but is restricted by the above baffle plate 34. As the fresh air 15 enters through the air vents 32 at the top of the burning chamber, it mixes with and burns the wood gas. The design of the top of the burning chamber, in particular the baffle and air vents, ensures that there is proper mixing, while reducing dispersion of the wood gas. This optimizes this secondary burning at the top of the burning chamber.
The twice burned fuel then leaves thru a hole in the baffle plate, to intensely heat the top of the cooking surface 38 and then escapes through the chimney 60, located at the top and rear of the outer housing.
As shown in
An ashtray compartment is located at the bottom of the inner housing, below the base that holds the burning biomass, It is inserted through a suitably shaped cut-out in the outer housing. A door 20 is mounted on hinges to the front of the outer housing with a latch opposite the hinged side. To the outer housing are connected collapsible legs, cooking plates, drying trays, and a chimney.
Terms, such as “top, bottom, above below, front, rear, and side” are intended to provide clarity of relative locations and parts of the stove when in normal use.
This application claims priority to U.S. Application No. 63/116778, filed on Nov. 20, 2020, the disclosure of which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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63116778 | Nov 2020 | US |