Method and apparatus for cascaded biomass oxidation with thermal feedback

Abstract

The invention relates to a method for cascaded biomass oxidation in a dish burner with ejection firing. The fuel ( 18 ), together with oxygen-containing primary air, is fed to a gasifier dish ( 8 ) having high thermal conductivity, in which the fuel is gasified by pyrolysis in a first combustion step, the resulting gas is conducted through guiding devices ( 6, 9 ) over the dish edge ( 11 ) of the gasifier dish, or over recesses on the upper dish edge, to the outside wall of the dish ( 8 ), and is enriched with oxygen-containing secondary air in the intermediate chamber ( 10 ) and converted into a cyclone flow around the outer shell dish during a second combustion step, through the convection of which strong thermal feedback is created, together with the high reflection of the thermal radiation on the guiding devices.

1 - 20 . (canceled) 
     
     
         21 . A method for cascaded biomass oxidation in a dish burner with ejection firing, the method comprising:
 supplying fuel together with primary air containing oxygen to a gasifier box with high thermal conductivity;   gasifying the fuel through pyrolysis in a first combustion step;   directing the resultant gas towards the outside wall of the box via guide devices arranged above a box edge of the gasifier box or through recesses arranged at the top edge of the gasifier box towards the outside wall of the box; and   enriching the resultant gas in an intermediate space with secondary air containing oxygen and, during a second combustion step, transforming the resultant gas into a cyclonic flow about the outside box wall, a high convection of which, in conjunction with a high reflection of heat radiation at the guide devices, resulting in strong thermal feedback,   wherein the flow can be forced into additional cascades with the aid of additional alternating dish-like and funnel-like guide devices, and   wherein a downward flow is followed again by an upward flow, and conversely an upward flow is followed again by a downward flow, and the cascades thus produced represent flow layers with respect to the subsequent diffuser chamber.   
     
     
         22 . The method according to  claim 21 , wherein a predominant flow direction of the cyclonic flow points downward and the gas flow is conveyed directly into a diffuser chamber at the lowest point directly beneath the box. 
     
     
         23 . The method according to  claim 21 , wherein the flow speed of the primary air in the gasifier box and that of the secondary air in the zones outside the gasifier box are different or can be regulated separately from one another. 
     
     
         24 . An apparatus for cascaded biomass oxidation in a dish burner with ejection firing, the apparatus comprising:
 guide devices arranged above and below a gasifier box to guide the gas flow after pyrolysis into close contact with an outside of the gasifier box; and   at least one secondary air nozzle provided between the gasifier box and the guide devices whose axial flow outlet direction has a horizontal component and runs at least approximately tangentially to the gasifier box wall.   
     
     
         25 . The apparatus according to  claim 24 , wherein the top guide device is designed as a cover constructed in two layers with a hollow space and has at least one air intake opening, has at least one nozzle with air inlet opening that is connectable to the a bottom boundary of the cover and to a hollow space, and has a fill opening with feed pipe for the fuel. 
     
     
         26 . The apparatus according to  claim 24 , wherein the bottom guide device, with the exception of a bottom recess, is designed as a second box around the outer wall of the gasifier box, with parallel spacing or with spacing that narrows towards the bottom, and wherein the bottom guide device is attached to the top guide device. 
     
     
         27 . The apparatus according to  claim 26 , wherein the bottom guide device and the gasifier box have pyramidal, spherical, conical, paraboloidal or hyperboloidal surface segments. 
     
     
         28 . The apparatus according to  claim 24 , wherein the gasifier box and its surrounding guide device are arranged coaxially and concentrically about a burner axis and are configured to be rotationally symmetrical. 
     
     
         29 . The apparatus according to  claim 24 , wherein at least one air outlet opening has at least one primary air nozzle just above the lowest point of the box inside the box, near the burn-off position of the biomass, and/or has at least one air outlet opening of at least one secondary air nozzle on the outside of the box. 
     
     
         30 . The apparatus according to  claim 24 , wherein at least one of the air supply nozzles is configured as an annular gap nozzle about the feed pipe. 
     
     
         31 . The apparatus according to  claim 24 , wherein multiple primary air nozzles and/or multiple secondary air nozzles are arranged about the burner axis at a uniform angular spacing. 
     
     
         32 . The apparatus according to  claim 24 , wherein the flow speed through the air supply nozzles is regulatable by at least one suction blower as exhaust gas fan and/or a rotary valve around at least one air intake opening. 
     
     
         33 . The apparatus according to  claim 24 , wherein the regulating devices are provided in the air supply nozzles. 
     
     
         34 . The apparatus according to  claim 24 , wherein the air supply nozzles are made by deep drawing, or from welded-on metal or ceramic tube sections. 
     
     
         35 . The apparatus according to  claims 24 , wherein the top guide device is spherical in shape, or has individual, separate convexities. 
     
     
         36 . The apparatus according to  claim 24 , wherein the gasifier box and the bottom guide device are arranged with a small, constant radial spacing, or a radial spacing that tapers in the flow direction, and wherein the spacing is adjustable via lifting spindles. 
     
     
         37 . The apparatus according to  claim 24 , wherein a thermal insulating layer made of mineral wool or ceramic fiber is arranged above the top guide device. 
     
     
         38 . The apparatus according to  claim 24 , wherein the gasifier box has a grate or a spring-mounted impact cone for removal of residual ash. 
     
     
         39 . The apparatus according to  claim 24 , wherein the mass flow rate of the fuel is regulatable by the level of the fuel at its input-side surface in the gasifier box via a sensor.