In accordance with the flow distribution of combustion gas including an unburned portion, an after-air port (AAP) arranged downstream of the two-stage combustion burner can effectively reduce the unburned portion by dividing as appropriate so as to avoid interaction, and by mixing together, two types of after-air having functions of linearity and spreading. As the configuration of this AAP, a primary nozzle for supplying primary after-air and having a vertical height greater than the horizontal width is provided in the center in the opening of the AAP, a secondary nozzle for supplying secondary after-air is provided in the opening outside of the primary nozzle, and one or more secondary after-air guide vanes having a fixed or variable tilt angle relative to the after-air port center axis are provided at the outlet of the said secondary nozzle to deflect and supply the secondary after-air horizontally to the left or right.

A furnace including a combustion chamber for burning fuel can have increased fuel burning efficiency, increased heating efficiency, and decreased harmful emissions of combustion byproducts. A combustion air delivery system delivers primary and secondary combustion air to the combustion chamber. Primary and secondary combustion air may be delivered at amounts that increase burning efficiency. An amount of secondary combustion air can be controlled by a valve system. A heat transfer device efficiently transfers heat from products of combustion for heating an enclosed space.

A furnace including a combustion chamber for burning fuel can have increased fuel burning efficiency, increased heating efficiency, and decreased harmful emissions of combustion byproducts. A combustion air delivery system delivers primary and secondary combustion air to the combustion chamber. Primary and secondary combustion air may be delivered at amounts that increase burning efficiency. An amount of secondary combustion air can be controlled by a valve system. A heat transfer device efficiently transfers heat from products of combustion for heating an enclosed space.

Slag (28) is formed during the combustion of solid fuels with a lower ash fusion temperature and covers parts of the solid fuel, prevents complete combustion and blocks the air supply, thereby leading to an interruption of the combustion process. According to the invention, the embers and the fusing ashes are mixed by means of a cleaning comb (22) and are discharged from the burner. The burner consists of rotating grate bars (25) which are arranged parallel to one another within the inner walls (1). The cleaning comb (22) moves between the grate bars (25); upwards between the grate bars (25); in direction of the burner opening; downwards under the grate bars; and finally in the direction of the burner flange (7). When the slag (28) adheres to the rotating grate bars (25), it is scraped off by the cleaning comb (22). The fuel supplied to a funnel (8) slides downwards by the force of gravity, the funnel lid (9) opens, and the fuel is pushed onto the grate bars (25) by the plunger (11). The plunger (11) has at least one opening (15) for secondary air (5) which also provides cooling. A blower (13) blows the ashes fallen through the grate bars (25) through a cut-out section in the burner floor (30) opened by the floor trap (20).

Slag (28) is formed during the combustion of solid fuels with a lower ash fusion temperature and covers parts of the solid fuel, prevents complete combustion and blocks the air supply, thereby leading to an interruption of the combustion process. According to the invention, the embers and the fusing ashes are mixed by means of a cleaning comb (22) and are discharged from the burner. The burner consists of rotating grate bars (25) which are arranged parallel to one another within the inner walls (1). The cleaning comb (22) moves between the grate bars (25); upwards between the grate bars (25); in direction of the burner opening; downwards under the grate bars; and finally in the direction of the burner flange (7). When the slag (28) adheres to the rotating grate bars (25), it is scraped off by the cleaning comb (22). The fuel supplied to a funnel (8) slides downwards by the force of gravity, the funnel lid (9) opens, and the fuel is pushed onto the grate bars (25) by the plunger (11). The plunger (11) has at least one opening (15) for secondary air (5) which also provides cooling. A blower (13) blows the ashes fallen through the grate bars (25) through a cut-out section in the burner floor (30) opened by the floor trap (20).

A biomass furnace including a housing, a burn chamber configured to hold a biomass fuel, a fuel loading door to open and close a fuel loading opening, and a secondary air system that includes a main tube and a plurality of branch tubes oriented transverse to the main tube. The main tube includes a front opening, a main tube interior in gaseous communication with the front opening, and 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 include at least one aperture in gaseous communication with the front opening of the main tube and which is configured to direct secondary air downwardly.

A biomass furnace including a housing, a burn chamber configured to hold a biomass fuel, a fuel loading door to open and close a fuel loading opening, and a secondary air system that includes a main tube and a plurality of branch tubes oriented transverse to the main tube. The main tube includes a front opening, a main tube interior in gaseous communication with the front opening, and 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 include at least one aperture in gaseous communication with the front opening of the main tube and which is configured to direct secondary air downwardly.

A solid fuel combustion device includes: a fuel supply device including a firewood feed pipe or another fuel supplier; a primary combustion chamber coupled to the fuel supply device; a secondary combustion chamber including a wall formed of a fireproof material and having a structure in which a space is formed at a side of the combustion gas outlet of the primary combustion chamber to induce primary combustion gas to be secondarily expanded and combusted; and an air supply system including at least one air supply device in an entire combustion path formed in the primary combustion chamber and the secondary combustion chamber.

A special distribution of nozzles in the flue gas outlet and their alignment make it possible to guide the flue gas along a wavy line. The addition of combustion air for primary air and secondary air can be variably distributed during operation of the combustion plant, for example so as to also keep the burnout per unit of time constant while maintaining a constant combustion air ratio.

A special distribution of nozzles in the flue gas outlet and their alignment make it possible to guide the flue gas along a wavy line. The addition of combustion air for primary air and secondary air can be variably distributed during operation of the combustion plant, for example so as to also keep the burnout per unit of time constant while maintaining a constant combustion air ratio.