Abstract: A multiple fuel burning system that may be employed in conjunction with a furnace includes a first annular tubular conduit connected to a source of pressurized fluid and a second annular conduit concentric with the first annular tubular conduit and coupled to a source of pressurized fuel. A third annular tubular conduit is also included that is concentric with the first and second tubular conduits but of a lesser diameter so as to be within the first and second annular tubular conduits. The third annular tubular conduit is connected to a source of heat retaining liquid such as water or the like. The first, second and third tubular conduits define an elongated combustion chamber with three nozzles mounted at one end. Two of the three nozzles are connected to a source of combustible fuel such as fuel oil. The third nozzle may be connected to a source of pulverized combustible fuel.

Abstract: A furnace and method of making the same are provided. The furnace has an integral poured refractory concrete combustion chamber wall having embedded therein a tertiary air supply system for supplying air around the burning fuels and air mixtures emitted from the burner. The tertiary air is introduced at positions spaced along the length of the combustion chamber.The combustion chamber wall is produced by positioning manifolds and multiple air supply tubes spaced along the wall length with the tubes directed inwardly toward the flame and around it, but stoppng short of the inner surface of the poured concrete wall. Removable plugs or screws are inserted into the open tube ends and extend the tube ends to the position of the proposed inner surface of the wall.Forms are provided for pouring the refractory concrete to form the wall. The outer form can be a steel plate or sheet or the like of relatively rigid structure.