Abstract: A watertube boiler system is disclosed which provides a plurality of radiant burners mounted within a housing in parallel, spaced-apart relationship. Individual burners are encircled by heat cells comprised of watertube coils which are in tangential juxtaposed relationship achieving a high view factor to the burner surfaces. Premixed fuel and air combusts on the outer surfaces of the burners which radiate energy to the tubes forming the heat cells. The ratio of combustion surface area to heat cell volume is within an optimum range for minimizing NOX and CO emissions.

Abstract: A commercial storage water heater process including a storage tank which is heated by a fiber matrix radiant burner positioned within an upright combustion tube at the lower end of the tank. A mixture of natural gas and air is forced by a blower at the upper end of the tank down through an inlet conduit and into the burner with combustion taking place flamelessly along the outer surface of the burner to radiate thermal energy to the combustion tube which is turn heats the water. Exhaust gases from the burner are directed along a path leading upwardly through a plurality of flue tubes which transfer a part of the residual energy of the gases into the water. Exhaust gases exiting the flue tubes are directed through an outlet port and vented to a stack. The combustion tube and outlet port are positioned radially offset and on opposite sides of the longitudinal axis of the tank to facilitate access to the combustion tube and burner.

Abstract: An efficient gas-fired bayonet-type heater has been developed to challenge the dominant position long enjoyed by the electric bayonet-type heater. The new heater replaces the electric resistance element in the bayonet-type heat exchange shell with a tubular porous fiber burner having a high length-to-diameter ratio attached to a long feed tube for the gas-air mixture. An annular space around the burner and feed tube within the shell provides the path for the combustion gases to flow to a discharge opening near the entry point of the gas-air mixture.

Abstract: Zone-controlled radiant burners are provided for retrofit installation in existing heaters. The burners comprise hollow cylindrical fiber matrix layers with baffles forming separate plena. A main stream of pre-mixed fuel and air is directed into the middle plenum, with the mixture flowing through the fiber matrix layer and incandescently combusting on the active surface zones to radiantly heat the tube coils. A reduced flow of fuel/air mixture, or only air, is directed into the remaining plenum so that the surrounding surface zones are combustibly less active or inactive to avoid destructive overheating of the burner surfaces.