Apparatus and method for burning a combustible gas, and a heat exchanger for use in this apparatus

Apparatus for burning a combustible gas comprising:

• a housing having walls defining a liquid chamber capable of holding liquid;
• a cylindrical combustion chamber sealed except for a gas inlet and a frustoconical outlet for combustion products, said combustion chamber being disposed within said liquid chamber and having liquid-impervious walls;
• an exhaust conduit having an inlet connected to the small end of the frustoconical outlet of said combustion chamber and an exhaust outlet through which combustion products can leave said conduit, said conduit being of substantially uniform cross-section from its inlet to its exhaust outlet;
• a gas burner disposed within said combustion chamber and in fluid communication with said gas inlet, said gas burner having walls defining an internal chamber and apertures passing through said walls, thereby establishing fluid communication between said internal chamber of said gas burner and said combustion chamber outside said gas burner;
• and
• an impeller means for urging a combustible mixture of a combustible gas and air through said gas inlet into said internal chamber of said gas burner, means for controlling the ratio of gas and air in the range 1-1.2 times the amount of air to completely burn the gas,
• said apertures in said gas burner being sized such that combustion of said combustible mixture within said combustion chamber outside said gas burner will not cause ignition of said combustible mixture within said internal chamber of said gas burner,
• the housing being surrounded by an insulating jacket which in turn is surrounded by an outer housing,
• said exhaust conduit comprises a first heat exchanger for being immersed in liquid in said liquid chamber for effecting heat exchange between the combustion products produced by combustion of said combustible mixture and the liquid in said liquid chamber, said first heat exchanger being disposed within said liquid chamber and comprising a riser section extending upwardly from said small end of the frustoconical outlet and a helical section extending downwardly from said riser section to said exhaust outlet.