Side-Feed Forced-Air Biomass Burning Cookstove

Abstract

Disclosed herein are systems and devices that aid in reducing particulate emissions from biomass stoves, for example by the use of gases injected in or near the oxidation zone of a combustion chamber. Also disclosed are systems and devices providing electricity to a pump or blower that aids in injecting the gas and/or collecting exhaust gases. In some embodiments the device providing electricity is a thermoelectric generator that may also be used to power other devices. In many embodiments, the systems and devices inject a gas at or near the oxidation zone in the combustion chamber of a biomass stove. The gas injected into the zone may be fresh air, exhaust from combustion or combinations thereof. The gas can be forced into the to combustion chamber with the aid of a pump or blower that may also aid in drawing in exhaust gas.

We claim: 
     
         1 . A device for reducing emissions from a biomass stove, the device comprising:
 a fluid inlet orifice;   an inlet conduit having an outside surface and an interior surface, the interior surface defining an inlet chamber, the inlet chamber in fluid communication with the exterior surface via the inlet orifice, the interior chamber for channeling a fluid;   a fan positioned within the inlet chamber and distal the inlet orifice, the fan for drawing a fluid through the inlet orifice and into the chamber, and into;   an outlet conduit the outlet conduit having an interior surface defining an outlet chamber, the outlet chamber in fluid communication with the inlet chamber;   one or more nozzles having an interior in fluid communication with the outlet chamber, the nozzle for directing the fluid into a combustion chamber of a biomass stove; and   a plurality of outlet orifices defined on the surface of the nozzle, the outlet orifices designed to allow the fluid to exit the interior of the nozzle.   
     
     
         2 . The device of  claim 1 , wherein the nozzle is positioned at or near the top of a lower combustion chamber. 
     
     
         3 . The device of  claim 1 , wherein the outlet orifices have an average diameter of between 0.5 and 3.5 mm. 
     
     
         4 . The device of  claim 3 , wherein the outlet orifices define a circle, a square, a triangle, or an oval, the average diameter being measured through the center of the circle, square, triangle, or oval. 
     
     
         5 . The device of  claim 3 , wherein the volume of gas escaping the one or more nozzles is greater than about 10 standard liters per minute and less than about 100 standard liters per minute. 
     
     
         6 . The device of  claim 5 , wherein the velocity of gas escaping from the one or more nozzles is greater than about 5 meters per second and less than about 20 meters per second. 
     
     
         7 . The device of  claim 1 , wherein the nozzle is selected from linear or circular. 
     
     
         8 . The device of  claim 7 , wherein the nozzle is a ring positioned above the lower combustion chamber and within the lower half of the upper combustion chamber, and designed to allow combustion gasses to pass directly through an injection region. 
     
     
         9 . The device of  claim 1 , wherein the fluid is a gas comprising greater than about 15% O 2 , oxygen. 
     
     
         10 . A method of reducing emissions from a biomass stove, the method comprising:
 placing a gas into an interior chamber of nozzle, the nozzle positioned at or near a flame;   increasing the pressure of the gas within the nozzle;   expelling a volume of the gas from the nozzle through a plurality of outlet orifices defined by the outer surface of the nozzle; and   directing the injected gas into a flame within a combustion chamber of the biomass stove, wherein the gas decreases the amount of at least one pollutant exiting the biomass stove.   
     
     
         11 . The method of  claim 10 , wherein the volume of gas is between about 10 standard liters per minute and 100 standard liters per minute. 
     
     
         12 . The method of  claim 10 , wherein the nozzle defines a ring, and the outlet orifices are positioned in the interior surface of the ring to aid in injecting a gas into the center of the ring. 
     
     
         13 . The method of  claim 10 , wherein the outlet orifices define a diameter of between 0.5 and 6.0 mm. 
     
     
         14 . The method of  claim 10 , wherein the outlet orifices are positioned equidistant from a floor of the combustion chamber. 
     
     
         15 . The method of  claim 10 , wherein the gas is forced into the nozzle by an electrically powered fan or blower. 
     
     
         16 . The method of  claim 10 , wherein the gas is expelled through one or more orifices at a velocity of between 5 and 25 meters per second. 
     
     
         17 . The method of  claim 10 , wherein the emission reduced is particulate matter less than about 2.5 micrometer. 
     
     
         18 . The method of  claim 17 , wherein the amount of particulate matter, less than about 2.5 micrometer, emitted from the stove during combustion is between about 25% and 90% less than the amount emitted when the pressure of the gas in the nozzle is not increased. 
     
     
         19 . The method of  claim 1 , wherein the gas is injected into the flame at an angle of between about −10 degrees to about +30 degrees. 
     
     
         20 . A method of reducing particulate emissions from a biomass stove, the method comprising:
 drawing a gas into a chamber, the gas comprising greater than about 15% O 2 ;   channeling the gas from the chamber into a nozzle having an interior surface and an exterior surface, the nozzle defining a circular tube having a plurality of outlet orifices on the inner surface of the circle, wherein the outlet orifices allow a gas to travel from the interior of the tube and toward the center of the circle;   increasing the pressure of the gas within the interior of the nozzle;   expelling a volume of the pressurized gas from the nozzle at a velocity of between about 5 meters per second and 20 meters per second; and   directing the injected gas into a flame within a combustion chamber of the biomass stove, wherein the gas decreases the amount of at least one pollutant exiting the biomass stove by greater than about 25% relative the stove lacking a nozzle or lacking a pressurized gas within the nozzle.