Fluid heater with spiral hot gas flow

Claim 1

In a fluid heater, the combination comprising (a) a first upright shell having a lower interior in which fuel is combusted to produce hot gases that rise in the shell interior, and having an upper exhaust vent, (b) a series of like hollow, generally flat discs arranged generally vertically in the shell interior, with spaces between the entireties of all the discs and the shell inner wall to pass the hot gases upwardly, (c) the discs tilted from horizontal and in multiple azimuthal directions, the discs having fluid inlets and outlets, and (d) means to pass fluid through the discs via said inlets and outlets, for heat transfer to the fluid in the discs, said means comprising fluid passing tubes that also support the discs, the tubes supported by the shell, the tubes located radially outwardly of the discs, (e) there being three of said tubes for each disc and spaced thereabout, two of the three tubes being inlet tubes located at the same lower elevation and the third tube being an outlet tube located at a relatively higher elevation, the third tubes for the multiple discs being circularly staggered about an upright axis passing through the heater, whereby the hot gases are caused to flow upwardly between and around the edges of the tilted discs in a swirling zig-zag manner, the three tubes for each disc being equally spaced about said axis, all the flat discs tilted at about 5° from horizontal, (f) all three tubes for each tilted disc being everywhere in the same tilted plane as defined by the flat disc, there being an outer shell surrounding the first shell and spaced therefrom to form an annular fluid chamber therebetween, all the tubes communicating with said chamber which has a lower fluid inlet and an upper fluid outlet whereby said hot gas spiral flow passes adjacent the inner side of the first shell outwardly of the periphery of each tilted disc.