A pellet burner includes: a burner body having a combustion chamber and an open top; a feed opening at a sidewall of the burner body; a through port under the burner body; and a grate structure above the through port and including two tiers of supports both secured to the burner body. Supports in the first tier are lower than the adjacent supports in the second tier. The second tier of supports are staggered with the first tier. A passage is between the two tiers of supports. The passage is narrower than a diameter D of the pellet fuel. A spacing between two adjacent supports in the second tier is greater than D but smaller than 2D. The feed opening is above the grate structure by no less than 3D. The pellet fuel drops from the feed opening. Air entering via the through port disperses the burnt pellet fuel ash.

Nozzles for delivering air into a combustion system of a boiler including an interchangeable nozzle barrel. Nozzle barrels can be easily replaced for maintenance or to change the size and flow velocity of the nozzles to optimize combustion performance. Nozzles may include converging sections with an arc, double arc's, bell shaped, or hyperbolic curves around the entire perimeter of the nozzle and optimized for delivery of air into the combustion system from ducting or from within a plenum.

Disclosed is a stove that includes a dome-shaped fire grate comprising a center, a perimeter surrounding and spaced from the center, the center being higher than the perimeter; a plurality of radial stiffening ribs extending away from the perimeter and toward the center; at least one circumferential stiffening ring extending at least partially about the center; and a plurality of ventilation holes between the center and the perimeter.

A combustion/pyrolization system comprising a combustion/pyrolization chamber supported by the base frame, and a perforated grate forms a bottom surface of the combustion/pyrolization chamber and facilitates passage of char and boichar therethrough. The combustion/pyrolization chamber is open along at a top and an air manifold supplies a first source of combustion air across the top of the combustion/pyrolization chamber to form an air curtain. A char collection/transfer chamber is located below the perforated grate for collecting at least the char and boichar that passes therethrough, and a conveying mechanism transfers the char and boichar out of the combustion/pyrolization system for collection and use. An air plenum chamber cools the char collection/transfer chamber such that the supplied secondary air becomes heated, and the heated secondary air flows into the char collection/transfer chamber and through the perforated grate into the combustion/pyrolization chamber to provide secondary combustion air.

A fuel management system for a biomass furnace features a common drive motor operatively coupled to both a fuel delivery conveyor, which is arranged to support and displace fuel during combustion in a combustion chamber of the furnace, and an ash removal conveyor which is arranged to transfer ash generated by the combustion out of the combustion chamber. The system also features ducting which extends around the fuel delivery conveyor to convey airflow generated by a blower for subsequent discharge both below and above the fuel during combustion. Furthermore, the system features a housing which operably supports at least the fuel delivery conveyor and which is arranged to be removably insertible into the combustion chamber of the furnace.

The present invention relates to an over fire air arrangement for a furnace (1), the furnace (1) having opposing first wall (4) and second wall (6) and opposing first side wall (5) and second side wall (7) between the first and second walls (4, 6) for forming a furnace enclosure (2). The over fire air arrangement comprising at least one first over fire air port (20) provided to the first wall (4) for supplying a first over fire air flow (40) into the furnace (1) and at least one first additional over fire air port (50) provided to at least one of the first and second side walls (5, 7) in the vicinity of the first wall (4), the at least one first additional over fire air port (50) being arranged to supplying a first additional over fire air flow (60) into the furnace (1) transversely to the first over fire air flow (40).

A combustion device includes a body defining a firebox, a viewing window in front of the firebox, an upper plate adjacent to a top side of the firebox, a first air passage extending from an end adjacent to a rear end of the body to a second end adjacent to a front end of the body, and a second air passage adjacent to a back side of the firebox. The second air passage has a communication opening at an end communicated with the firebox. The communication opening is at a height higher than a height of a bottom side of the firebox and lower than a height of the top side of the firebox. A burner is disposed within and adjacent to the bottom side of the firebox.

A fire pit includes an engine having at least one wall defining an inner chamber. At least one primary air aperture is defined through the inner chamber wall at a first, lower level, and at least one secondary air aperture is defined through the inner chamber wall at a second, upper level. A fuel grate is supported within the inner chamber at a level between the lower level and the upper level.

A fire pit includes an engine having at least one wall defining an inner chamber. At least one primary air aperture is defined through the inner chamber wall at a first, lower level, and at least one secondary air aperture is defined through the inner chamber wall at a second, upper level. A fuel grate is supported within the inner chamber at a level between the lower level and the upper level.

The invention is a novel Top-Lit-Updraft cook stove with internal forced primary and secondary air, designed to burn biomass. The cook stove is specifically designed to cleanly burn biomass. The stoves design innovations include a cylinder-within-cylinder design to provide heated, forced secondary to the burner area right below the burner. The burner design addresses limitations in previous cookstove burner design by implementing a bluff body design to direct syngas to the secondary air jets, improving mixing and combustion of volatile gases.