Biomass secondary combustion stove with exhaust mixer

Abstract

Aspects of the present invention provide biomass combustion stove with an exhaust gas mixer. The exhaust gas mixer is positioned in the exhaust gas outlet of the stove. That is the exhaust gas mixer is positioned within the path of exhaust gases exiting the stove housing at the point where the exhaust gases exit the housing, above a baffle of the stove. The exhaust gas mixer may be a cone, a pair of opposing cones, a sphere, turbine, propeller, partial helical, or fan configured to promote mixing and/or turbulence of the exhaust gases as they exit the housing. In one embodiment, the stove provides some room air to the exhaust gas outlet and flue above the baffle to cool the exhaust gases as they exit the housing via the exhaust gas outlet of the stove.

What is claimed is: 
     
         1 . A biomass stove comprising:
 a burn chamber configured to receive air and biomass, wherein combustion of the biomass occurs within the burn chamber;   an exhaust gas outlet configured to receive exhaust gases from the burn chamber and convey the received exhaust gases to a flue;   an exhaust gas mixer positioned in the exhaust gas outlet when the biomass stove is assembled.   
     
     
         2 . The biomass stove of  claim 1 , wherein:
 the exhaust gas mixer is configured to disrupt flow of exhaust gases from the burn chamber to the flue such that the exhaust gases have reduced temperature variance in the flue.   
     
     
         3 . The biomass stove of  claim 1 , wherein:
 the biomass stove further comprises a stand configured to support the burn chamber and space the burn chamber from a surface supporting the stove.   
     
     
         4 . The biomass stove of  claim 1 , wherein:
 the stove has a maximum designed output of no more than 25000 BTU of heat.   
     
     
         5 . The biomass stove of  claim 1 , wherein:
 the exhaust gas mixer is a pair of opposing cones;   each cone of the pair of opposing cones has a base joined to a base of the other cone of the pair of opposing cones such that a top and a bottom of the exhaust gas mixer are points of the pair of opposing cones; and   the exhaust gas mixer is centered within the exhaust gas outlet.   
     
     
         6 . The biomass stove of  claim 1 , wherein:
 the exhaust gas mixer is one of a pair of opposing cones, a helix, or a spiral.   
     
     
         7 . The biomass stove of  claim 1 , wherein:
 the exhaust gas mixer is formed of metal.   
     
     
         8 . The biomass stove of  claim 1 , wherein:
 the exhaust gas outlet comprises an outlet flange extending from the burn chamber; and   the outlet flange is configured to connect to the flue.   
     
     
         9 . The biomass stove of  claim 1 , wherein:
 the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue; and   the stove further comprises a standoff configured to connect the exhaust gas mixer to the burn chamber at the outlet flange.   
     
     
         10 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue; and   the outlet flange extends upward from the burn chamber through the housing when the stove is in an upright position.   
     
     
         11 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue;   the outlet flange extends upward from the burn chamber through the housing when the stove is in an upright position;   the stove further comprises a standoff configured to connect the exhaust gas mixer to the burn chamber at the outlet flange; and   the standoff centers the exhaust gas mixer within the outlet flange.   
     
     
         12 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue;   the outlet flange extends upward from the burn chamber through the housing when the stove is in an upright position;   the stove further comprises a standoff configured to connect the exhaust gas mixer to the burn chamber at the outlet flange;   the standoff centers the exhaust gas mixer within the outlet flange; and   the exhaust gas mixer extends above the outlet flange when the stove is in an upright position.   
     
     
         13 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue;   the outlet flange extends upward from the burn chamber through the housing when the stove is in an upright position;   the stove further comprises a standoff configured to connect the exhaust gas mixer to the burn chamber at the outlet flange;   the standoff centers the exhaust gas mixer within the outlet flange;   the exhaust gas mixer extends above the outlet flange when the stove is in an upright position; and   the exhaust gas mixer does not extend into the burn chamber.   
     
     
         14 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue;   the outlet flange extends upward from the burn chamber through the housing when the stove is in an upright position;   the stove further comprises a standoff configured to connect the exhaust gas mixer to the burn chamber at the outlet flange;   the standoff centers the exhaust gas mixer within the outlet flange;   the exhaust gas mixer extends above the outlet flange when the stove is in an upright position; and   a bottom of the exhaust gas mixer is above the housing when the stove is in the upright position.   
     
     
         15 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a combustion air intake flange configured to receive combustion air and provide the received combustion air to the burn chamber.   
     
     
         16 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a combustion air regulator configured to modulate a flow volume of combustion air provided to the burn chamber as a function of input from a user such that a burn rate and heat output of the stove is determined as a function the input from the user to the combustion air regulator; and   the stove further comprises a combustion air intake flange configured to receive combustion air and provide the received combustion air to the combustion air regulator.   
     
     
         17 . The biomass stove of  claim 1 , wherein:
 the stove is located in a room;   the stove further comprises a combustion air regulator configured to modulate a flow volume of combustion air provided to the burn chamber as a function of input from a user such that a burn rate and heat output of the stove is determined as a function the input from the user to the combustion air regulator;   the stove further comprises a combustion air intake flange configured to receive combustion air and provide the received combustion air to the combustion air regulator;   the combustion air intake is configured to connect to an inlet air tube to receive air from outside of the room;   the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue, said flue configured to conduct exhaust gases out of the room; and   the outlet flange extends upward from the burn chamber through the housing when the stove is in an upright position.   
     
     
         18 . The biomass stove of  claim 1 , wherein:
 the stove is located in a room;   the stove further comprises a combustion air regulator configured to modulate a flow volume of combustion air provided to the burn chamber as a function of input from a user such that a burn rate and heat output of the stove is determined as a function the input from the user to the combustion air regulator;   the stove further comprises a combustion air intake flange configured to receive combustion air and provide the received combustion air to the combustion air regulator;   the combustion air intake is configured to connect to an inlet air tube to receive air from outside of the room;   the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue, said flue configured to conduct exhaust gases out of the room;   the outlet flange extends upward from the burn chamber through the housing when the stove is in an upright position; and   the stove further comprises a room air blower configured to force air from the room through a space between the housing and the burn chamber.   
     
     
         19 . The biomass stove of  claim 1 , wherein:
 the stove is located in a room;   the stove further comprises a housing at least partially surrounding the burn chamber;   the exhaust gas outlet comprises an outlet flange extending from the burn chamber;   the outlet flange is configured to connect to the flue, said flue configured to conduct exhaust gases out of the room;   the stove further comprises a room air blower configured to force air from the room through a space between the housing and the burn chamber; and   the stove comprises a gap between the housing and the outlet flange such that air from the room air blower passes through the space between the housing and the burn chamber and through the gap back to the room when the room air blower is operating.   
     
     
         20 . The biomass stove of  claim 1 , wherein:
 the stove further comprises a plurality of secondary air tubes configured to provide secondary combustion air to the burn chamber when the stove is burning biomass in the burn chamber;   a first baffle over the plurality of secondary air tubes when the stove is assembled and in an upright position;   a second baffle over the first baffle when the stove is assembled and in the upright position; and   a top wall defining a top of the burn chamber above the second baffle when the stove is assembled and in the upright position.