A fire tube boiler includes a perforated flame holder configured to hold a combustion reaction that produces very low oxides of nitrogen (NOx).

A scalable pulse combustor that can be deployed as the heat exchanger in high efficiency, low NOx condensing boilers, water heaters and steam generators is provided. The combustor generally comprises an annular burner coil with a burner flange for accommodating the nozzle of a conventional burner/blower fitted into the central aperture thereof; a spaced-apart opposite annular spreader coil with a heat exchange hub fitted into the central aperture thereof; and a plurality of annular intermediate coils. Each of the burner, spreader and intermediate coils are preferably formed of spiral wound stainless steel tubing, with each winding directly abutting the preceding winding so as to create an annular wall. The heat exchange hub functions as a secondary heat exchanger with its own independently controllable coolant flow.

An array includes a plurality of refractory bricks, each having a substantially tubular body including a first end, an opposed second end, a central bore extending from the first end to the second end along the longitudinal length thereof and defining an inner surface of the refractory brick, and an outer surface extending from the first end to the second end along the longitudinal length thereof. The outer surface of each refractory brick has a shape that transitions axially between a plurality of hexagonal portions and non-hexagonal portions along the longitudinal lengths thereof, and the plurality of refractory bricks are arranged and interlocked with one another in a vertical and horizontal manner via mating members provided on the hexagonal portions of the outer surfaces thereof. A continuous plenum space is defined by the non-hexagonal portions of the refractory bricks arranged in the array.

A combustion system includes a fuel and oxidant source that outputs fuel and oxidant, a first perforated flame holder, and a second perforated flame holder separated from the first perforated flame holder by a gap. The first and second perforated flame holders sustain a combustion reaction of the fuel and oxidant within the first and second perforated flame holders.

A combustion system includes a fuel and oxidant source that outputs fuel and oxidant, a first perforated flame holder, and a second perforated flame holder separated from the first perforated flame holder by a gap. The first and second perforated flame holders sustain a combustion reaction of the fuel and oxidant within the first and second perforated flame holders.

Example apparatus and methods providing for the improved chemical conversion of the combustible components of a gaseous medium are disclosed. In some examples, the apparatus includes a guiding body that guides the flow of the gaseous medium within a reaction chamber of the apparatus. In some examples, the guiding body of the disclosed apparatus is configured to stabilize a residence period of the gaseous medium in the reaction chamber. In some examples, the guiding body results in a flow path of the gaseous medium within the reaction chamber being optimized and/or maximized, and/or results in a short circuit flow of the gaseous medium in the reaction chamber being suppressed. In some disclosed examples, the guiding body causes at least a portion of the flow path of the gaseous medium within the reaction chamber to take the form of a cyclone flow.

Example apparatus and methods providing for the improved chemical conversion of the combustible components of a gaseous medium are disclosed. In some examples, the apparatus includes a guiding body that guides the flow of the gaseous medium within a reaction chamber of the apparatus. In some examples, the guiding body of the disclosed apparatus is configured to stabilize a residence period of the gaseous medium in the reaction chamber. In some examples, the guiding body results in a flow path of the gaseous medium within the reaction chamber being optimized and/or maximized, and/or results in a short circuit flow of the gaseous medium in the reaction chamber being suppressed. In some disclosed examples, the guiding body causes at least a portion of the flow path of the gaseous medium within the reaction chamber to take the form of a cyclone flow.

A gas-burning appliance includes a combustor and a flow guide device engaged with the combustor. The combustor has a gas outlet. The flow guide device includes a separator and two stop plates. The separator has an opening. Each of the stop plates is located at the opening, and a top edge thereof is higher than a top surface of the separator. The combustor is located below the separator with the gas outlet corresponding to a space between the stop plates. The flow guide device has at least one first air inlet, which is located below the separator, and communicates with the space between the stop plates. A gas fireplace includes a firebox, a translucent shield, and the gas-burning appliance. A separator divides the firebox into an air chamber, which receives the combustor, and a combustion chamber. Whereby, the visibility of flame and the combustion efficiency could be improved.

A gas-burning appliance includes a combustor and a flow guide device engaged with the combustor. The combustor has a gas outlet. The flow guide device includes a separator and two stop plates. The separator has an opening. Each of the stop plates is located at the opening, and a top edge thereof is higher than a top surface of the separator. The combustor is located below the separator with the gas outlet corresponding to a space between the stop plates. The flow guide device has at least one first air inlet, which is located below the separator, and communicates with the space between the stop plates. A gas fireplace includes a firebox, a translucent shield, and the gas-burning appliance. A separator divides the firebox into an air chamber, which receives the combustor, and a combustion chamber. Whereby, the visibility of flame and the combustion efficiency could be improved.

A combustion system includes a fuel and oxidant source, a perforated flame holder, and a support structure that supports the perforated flame holder at a selected distance from the fuel and oxidant source. The fuel and oxidant source outputs fuel and oxidant onto the perforated flame holder. The perforated flame holder receives the fuel and oxidant and sustains a combustion reaction of the fuel and oxidant within the perforated flame holder.