Biomass pellet fuel heating device, system and method

Abstract

There is provided a pelletized-biomass combustion device comprising: (a) an elongate upright combustion capsule; (b) a grate element disposed within and bisecting the combustion capsule, (i) the grate element having a first side and a second side and (ii) the grate element open to fluid communication between the first side and the second side; (c) a first combustion air inlet facing the first side of the grate; (d) a second combustion air inlet facing the second side of the grate; (e) a fuel-feed inlet; and (f) a flue-gas exhaust outlet. The combustion capsule can be formed of two mated components such as a chamber housing mated with a burn pot member, or instead it can be formed as a single unit such as the chamber housing bisected by the grate. In any event, the grate element has two sides, and there are two combustion air inlets, each facing opposite sides of the grate. The combustion device is preferably an induced-draft system wherein the exhaust fan is positioned at the distal end of the stove pipe.

1 . A pelletized-biomass combustion device comprising:
 an elongate upright combustion capsule;   a grate element disposed within and bisecting said combustion capsule,   said grate element having a first side and a second side;   said grate element open to fluid communication between said first side and said second side;   a first combustion air inlet facing said first side of said grate;   a second combustion air inlet facing said second side of said grate;   a fuel-feed inlet; and   a flue-gas exhaust outlet.   
   
   
       2 . A pelletized-biomass combustion device according to  claim 1  wherein said grate element has a fuel-support surface open to said fuel-feed inlet, and
 wherein said fuel-support surface is substantially horizontal and substantially flat.   
   
   
       3 . A pelletized-biomass combustion device according to  claim 1  wherein said grate element has a fuel-support surface open to said fuel-feed inlet,
 wherein said fuel-support surface is substantially horizontal and substantially level,   wherein said fuel-support surface substantially extends across said combustion capsule providing a close-mode cross-section profile to said combustion capsule.   
   
   
       4 . A pelletized-biomass combustion device according to  claim 1  further including
 a stovepipe downstream of said flue-gas exhaust outlet, said stovepipe having a proximal end and a distal end; and   an exhaust fan in fluid communication with said stovepipe and disposed proximate said distal end of said stovepipe.   
   
   
       5 . A pelletized-biomass combustion device according to  claim 1  wherein said grate element bisects said combustion capsule into an upper chamber and a lower chamber,
 wherein said first side of said grate element is open to said upper chamber,   wherein said second side of said grate element is open to said lower chamber,   wherein said first side of said grate element is substantially horizontal and level, and is open to said fuel-feed inlet,   wherein said first combustion air inlet is disposed within said upper chamber and is spaced apart from, and substantially centered on, said first side of said grate element,   wherein said second combustion air inlet is disposed within said lower chamber and is spaced apart from, and substantially centered on, said second side of said grate element, and   wherein said flue-gas exhaust outlet is open to said upper chamber.   
   
   
       6 . A pelletized-biomass combustion device according to  claim 5  wherein said first side of said grate element includes a fuel-support surface open to said fuel-feed inlet,
 wherein said fuel-support surface is substantially horizontal and level, and   wherein said fuel-support surface substantially extends across said combustion capsule providing a close-mode cross-section profile to said combustion capsule.   
   
   
       7 . A pelletized-biomass combustion device according to  claim 6  wherein said lower chamber has a substantially hemispherical configuration. 
   
   
       8 . A pelletized-biomass combustion device according to  claim 6  wherein said upper chamber is substantially bounded by a thin-wall-construction chamber housing. 
   
   
       9 . A pelletized-biomass combustion device according to  claim 6  further including a coextensive combustion air/fuel feed tube disposed within said upper chamber, said coextensive combustion air/fuel feed tube having an open end,
 wherein said first combustion air inlet, said fuel-feed inlet and said open end of said coextensive combustion air/fuel feed tube are coincident.   
   
   
       10 . A pelletized-biomass combustion device comprising:
 an elongate upright combustion capsule comprised of a combustion chamber housing and a burn pot mated with said combustion chamber housing;   a grate element disposed within said combustion chamber,   said grate element and said combustion chamber housing substantially defining a primary combustion chamber,   said grate element and said burn pot substantially defining a secondary combustion chamber;   said grate element having a first side facing said primary combustion chamber;   said grate element having a second side facing said secondary combustion chamber;   said primary combustion chamber being in fluid communication with said secondary combustion chamber through said grate element;   a first combustion air inlet facing said first side of said grate;   a second combustion air inlet facing said second side of said grate;   a fuel-feed inlet; and   a flue-gas exhaust outlet from said primary combustion chamber.   
   
   
       11 . A pelletized-biomass combustion device according to  claim 10  wherein said secondary combustion chamber has a substantially hemispherical configuration. 
   
   
       12 . A pelletized-biomass combustion device according to  claim 10  wherein said secondary combustion chamber has a bottom, and
 wherein said second air inlet is disposed at said bottom of said secondary combustion chamber.   
   
   
       13 . A pelletized-biomass combustion device according to  claim 10  wherein said first side of said grate element has a fuel-support surface open to said fuel-feed inlet, and
 wherein said fuel-support surface is substantially horizontal and substantially flat.   
   
   
       14 . A pelletized-biomass combustion device according to  claim 10  wherein said grate element has a fuel-support surface open to said fuel-feed inlet,
 wherein said fuel-support surface is substantially horizontal and substantially level,   wherein said primary combustion chamber has a horizontal cross-section profile, and wherein said fuel-support surface is substantially coincident with said horizontal cross-section profile of said primary combustion chamber.   
   
   
       15 . A pelletized-biomass combustion device according to  claim 10  further including a stovepipe downstream of said flue-gas exhaust outlet, said stovepipe having a proximal end and a distal end; and
 an exhaust fan in fluid communication with said stovepipe and disposed proximate said distal end of said stovepipe.   
   
   
       16 . A pelletized-biomass combustion device according to  claim 10  further including a first air feed tube,
 said first air feed tube being substantially disposed within said primary combustion chamber and having a terminal end, and   said first air inlet being coincident with said terminal end of said first air feed tube.   
   
   
       17 . A pelletized-biomass combustion device according to  claim 10  wherein said combustion chamber housing is a substantially thin-wall-construction combustion chamber housing. 
   
   
       18 . A pelletized-biomass combustion device according to  claim 10  wherein said first combustion air inlet is substantially centered on said first side of said grate, and
 wherein said second combustion air inlet is substantially centered on said second side of said grate.   
   
   
       19 . A method of combusting biomass fuel pellets in a pelletized-biomass combustion device under flux conditions within a confined combustion capsule, said pelletized-biomass combustion device having an elongate upright combustion capsule and a grate element disposed within and bisecting said combustion capsule, said grate element having a first side and a second side, and said grate element open to fluid communication between said first side and said second side, said grate element having a substantially horizontal and substantially level fuel-support surface open to said fuel-feed inlet and substantially extending across said combustion capsule providing a close-mode cross-section profile to said combustion capsule, said combustion device further having a first combustion air inlet facing said first side of said grate, a second combustion air inlet facing said second side of said grate, a fuel-feed inlet and a flue-gas exhaust outlet, comprising the steps of:
 combusting pelletized-biomass fuel on said fuel-support surface while   feeding combustion air to said fuel-support surface simultaneously through said first combustion air inlet and said second combustion air inlet.   
   
   
       20 . A method of combusting biomass fuel pellets in a pelletized-biomass combustion device under flux conditions within a confined combustion capsule according to  claim 19 , wherein said combustion device further includes a stovepipe downstream of said flue-gas exhaust outlet, said stovepipe having a proximal end and a distal end, and an exhaust fan in fluid communication with said stovepipe and disposed proximate said distal end of said stovepipe, further including the step of:
 maintaining a water-column negative draft pressure within said combustion capsule of between about 0.01 to about 0.08 while combusting said pelletized-biomass fuel on said fuel-support surface.   
   
   
       21 . A method of combusting biomass fuel pellets in a pelletized-biomass combustion device under flux conditions within a confined combustion capsule according to  claim 19 , wherein said grate bisects said combustion capsule into a primary combustion chamber and a secondary combustion chamber, said first said of said grate element facing said primary combustion chamber, and said second side of said grate element facing said secondary combustion chamber, and said primary combustion chamber being bounded by a thin-wall-construction chamber housing having an external surface, further including the step of:
 maintaining a temperature of about 400° F. to about 2,000° F. at said external surface of said chamber housing while combusting said pelletized-biomass fuel on said fuel-support surface.   
   
   
       22 . A method of combusting biomass fuel pellets in a pelletized-biomass combustion device under flux conditions within a confined combustion capsule according to  claim 19 , wherein said fuel-feed inlet is above and spaced-apart from said fuel-support surface, further including the step of:
 feeding fresh pelletized-biomass fuel to said pelletized-biomass fuel on said fuel-support surface by dropping said fresh pelletized-biomass fuel from said fuel-feed inlet onto said fuel-support surface while combusting said pelletized-biomass fuel on said fuel-support surface.