Oil-heated once-through heater with apparatus for pre-heating the mixing chamber

Claim 1

In a water heater of the once-through type having a heating shaft, a plate block heat exchanger adjacent one end of the shaft, a first annular chamber surrounding the shaft and having upper and lower ends, said lower end communicating with the other end of the shaft, an oil gasification burner including a burner plate intermediate the ends of the shaft, a second annular chamber surrounding the first annular chamber and having upper and lower ends, said upper ends of the two chambers being in communication, a tubular conduit having one end in communication with the lower end of the second chamber and having a second end, a blower communicating with the second end of the conduit for supplying combustion air having oxygen therein to the shaft, an oil supply nozzle means adjacent the other end of the shaft for supplying oil to the shaft to be vaporized therein and burned at the side of the plate adjacent said one end, and heating means for preliminarily heating said shaft upon the start-up of the burner, the improvement wherein said heating means comprises: an auxiliary oil injection nozzle in said conduit downstream from said blower to spray oil into said conduit, and an ignition electrode associated with said conduit nozzle for igniting said sprayed oil to produce a flame for heating the air flowing through said conduit to the shaft, said nozzle being of a capacity such that when the oil therefrom is burned the amount of combustion is quite insufficient to use up all of the oxygen supplied by said blower.