A method is provided for controlling airflow into a furnace that employs a velocity type damper. In one embodiment, the method for controlling airflow may include engaging a velocity type damper to an air port opening of a furnace. The velocity type damper includes at least one air controlling surface that is positioned proximate to a wall of the furnace at the air port opening so that air velocity exiting the at least one air controlling surface is substantially equal to the air velocity entering the air port opening to the furnace. The method may further include adjusting a cross sectional area through the velocity type damper to control air velocity into the furnace through the air port opening.

A method is provided for controlling airflow into a furnace that employs a velocity type damper. In one embodiment, the method for controlling airflow may include engaging a velocity type damper to an air port opening of a furnace. The velocity type damper includes at least one air controlling surface that is positioned proximate to a wall of the furnace at the air port opening so that air velocity exiting the at least one air controlling surface is substantially equal to the air velocity entering the air port opening to the furnace. The method may further include adjusting a cross sectional area through the velocity type damper to control air velocity into the furnace through the air port opening.

A burner tip apparatus which is resistant to plugging, and a staged air method of operation which reduces the peak temperature of the flame of the burner tip to provide low levels of NO.sub.x and other emissions. The burner tip can be used as an auxiliary burner tip for stabilizing a main burner flame, or for other purposes.

A burner tip apparatus which is resistant to plugging, and a staged air method of operation which reduces the peak temperature of the flame of the burner tip to provide low levels of NO.sub.x and other emissions. The burner tip can be used as an auxiliary burner tip for stabilizing a main burner flame, or for other purposes.

A reverse-jet swirl pulverized coal burner with multi-stage recirculations includes a pre-combustion housing, a primary coal-air structure, a rich-lean output structure, an inner secondary air structure, and an outer secondary air structure. The pre-combustion housing has a pre-combustion chamber and a housing outlet. The primary coal-air structure is configured to separate a primary coal-air flow into a fuel-rich coal-air flow and a fuel-lean coal-air flow. The rich-lean output structure is configured to output the fuel-lean coal-air flow and block the fuel-rich coal-air flow to make the fuel-rich coal-air flow reversely flow to the pre-combustion chamber. The inner secondary air structure is configured to introduce an inner secondary air into the pre-combustion chamber, thereby forming a first-stage recirculation zone in the pre-combustion chamber and forming a second-stage recirculation zone. The outer secondary air structure is configured to form a third-stage recirculation zone at the housing outlet.

A biomass heating system for burning fuel in the form of pellets and/or wood chips is disclosed, the system comprising the following: a boiler with a combustion device, a heat exchanger with a plurality of boiler tubes, wherein the combustion device comprises: a combustion chamber with a rotating grate, with a primary combustion zone and with a secondary combustion zone; wherein the primary combustion zone is enclosed by a plurality of combustion chamber bricks laterally and by the rotating grate from below; wherein a plurality of secondary air nozzles is provided in the combustion chamber bricks; wherein the primary combustion zone and the secondary combustion zone are separated at the level of the secondary air nozzles; wherein the secondary combustion zone of the combustion chamber is fluidically connected to an inlet of the heat exchanger.

A rotating grate for a biomass heating system is disclosed, the grate comprising: at least one rotating grate element; at least one bearing axle, by means of which the rotating grate element is rotatably mounted; at least one cleaning device attached to one of the rotating grate elements, wherein the cleaning device comprises a mass element movable relative to the rotating grate element; wherein the cleaning device is arranged in such a way that, upon rotation of the rotating grate element, an acceleration movement of the mass element is initiated so that the cleaning device exerts a knocking effect on the rotating grate element in order to clean the rotating grate element.

A biomass heating system for firing fuel in the form of pellets and/or wood chips is disclosed, comprising: a boiler with a combustion device; a heat exchanger with an inlet and an outlet; wherein the combustion device comprises a combustion chamber with a primary combustion zone and with a secondary combustion zone provided downstream thereof; the combustion device having a rotating grate on which the fuel can be burned; the secondary combustion zone of the combustion chamber being fluidically connected to the inlet of the heat exchanger the primary combustion zone being laterally enclosed by a plurality of combustion chamber bricks.

A biomass heating system for firing fuel in the form of pellets and/or wood chips is disclosed, comprising: a boiler with a combustion device; a heat exchanger with an inlet and an outlet; wherein the combustion device comprises a combustion chamber with a primary combustion zone and with a secondary combustion zone provided downstream thereof; the combustion device having a rotating grate on which the fuel can be burned; the secondary combustion zone of the combustion chamber being fluidically connected to the inlet of the heat exchanger the primary combustion zone being laterally enclosed by a plurality of combustion chamber bricks.

A grill apparatus includes a bottom portion, a lid portion, a firebox and an ash bucket. The lid portion is coupled to the bottom portion forming a cooking chamber. The bottom portion receives the firebox. A support structure of the firebox rests on an inner surface of the bottom portion. An inner surface of the bottom port, the support structure of the firebox and a firebox lower opening define a first air path from a lower portion of the cooking chamber to a heat chamber. The ash bucket includes an air vent extending from a base of the ash bucket base into an internal ash receptacle and has an upper vent aperture with a vent cover connected to the air vent. The cover is disposed over an upper vent aperture to further define the first air path.