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US 5,666,944 AGranted
Water heating apparatus with passive flue gas recirculation
AssigneePVI Industries, Inc.
InventorMark A. Ferguson
Life of this patent
Estimating the term…
Abstract
The invention relates to a water heating apparatus and method to passively recirculate flue gas in order to reduce NO.sub.x emissions formed during combustion. The apparatus uses a high efficiency burner, a submergible, pressurized, combustion chamber having multiple external heating surfaces, and a flue collector that collects and passively recirculates a portion of the flue gases back into the burner air intake while exhausting the rest. The multiple external heating surfaces are installed within a closed tank and are submerged in water under pressure during use.
Claims4
A water heating apparatus comprising:
- a closed tank having an exterior, an interior and external walls having at least one opening therein;
- a submerged, pressurized combustion chamber mounted within the tank opening by means of a mounting flange, the combustion chamber having multiple external heating surfaces which are submerged in water under pressure when the combustion chamber is mounted within the tank opening;
- a flue collector mounted to the combustion chamber mounting flange on the tank exterior, the flue collector having a flue opening communicating with the combustion chamber and having an annular chamber surrounding the flue opening and separated therefrom which receives the products of combustion produced within the combustion chamber, the annular chamber having a flue exhaust outlet and a flue gas recirculation outlet;
- an air-fed, forced draft burner having an air intake region for the intake of fresh air, a fuel/air mixing passage leading to a combustion region, a motor-driven impeller for forcing air from the intake region in the direction of the combustion region and a burner nozzle, the burner nozzle being mounted within the flue opening of the flue collector for producing controlled combustion within the combustion chamber;
- an air intake box having a fresh air inlet, the air intake box being connected by means of an air intake passage with the air intake region of the forced draft burner;
- a primary flue gas recirculation conduit passively connecting the flue gas recirculation outlet with the air intake region of the burner upstream of the combustion region and burner nozzle, whereby fresh air and recirculated flue gas are mixed in the air intake region of the burner prior to entering the combustion region and burner nozzle;
- and
- a secondary flue gas recirculation conduit connecting the flue gas recirculation outlet with the air intake box for providing recirculated flue gas to the forced draft burner during periods of low burner fire or pilot operations.
5 more elements
Dependencies are inferred from the claim text.