Biochar kiln

Abstract

A biochar kiln is disclosed. An example of the biochar kiln includes a body having a one-piece rolled wall, a curved floor attached to the sidewall by a single weld line, and a removable lid. The example biochar kiln includes a plurality of semi-independent combustion cells. The example biochar kiln also includes a ventilation subsystem, an ember suppression subsystem, and a stack subsystem. A control subsystem may configured to monitor a plurality of zones of the biochar kiln for a plurality of process control variables, to produce a quality biochar product with well-managed emissions.

The invention claimed is: 
     
       1. A biochar kiln, comprising:
 a body having a one-piece rolled wall, a curved floor attached to the sidewall by a single weld line, and a removable lid; 
 a plurality of semi-independent combustion cells, wherein a center combustion cell is provided in the center of the body and six perimeter combustion cells are provided between the center combustion cell and the wall; 
 an outside vent pipe loading to a center of each of the perimeter combustion cells to provide combustion air; 
 a plurality of thermowell tubes built into the curved floor for each of the combustion cells, wherein the thermowell tubes are positioned adjacent the vent pipes; 
 a ventilation subsystem; 
 an ember suppression subsystem; 
 a stack subsystem; and 
 a control subsystem. 
 
     
     
       2. The biochar kiln of  claim 1 , wherein the ventilation subsystem includes ports around the perimeter of the body of the biochar kiln, each of the ports connected to internal air inlets. 
     
     
       3. The biochar kiln of  claim 1 , further comprising an automatic control including computer-controlled dampers to regulate airflow into the body of the biochar kiln. 
     
     
       4. The biochar kiln of  claim 3 , wherein damper airflow is by negative pressure in the kiln or blown in by an external blower or both. 
     
     
       5. The biochar kiln of  claim 1 , wherein the stack subsystem includes a stack blower to move combustion air through a duct where smoke then enters a venturi mix tube. 
     
     
       6. The biochar kiln of  claim 5 , wherein air from the blower entrains nearby flue gas to pull up into the venturi mix tube, and the air and flue gas combine en route a secondary burner. 
     
     
       7. The biochar kiln of  claim 1 , wherein the ember suppression subsystem includes a gas injected into the body of the biochar kiln to purge and/or dilute residual oxygen in the body. 
     
     
       8. The biochar kiln of  claim 7 , wherein carbon dioxide gas is utilized to enable produced biochar to flood the body of the biochar kiln from bottom-up. 
     
     
       9. The biochar kiln of  claim 1 , wherein the control subsystem manages a plurality of zones within the body. 
     
     
       10. The biochar kiln of  claim 9 , wherein the zones include independent horizontal and vertical zones. 
     
     
       11. The biochar kiln of  claim 9 , wherein the zones include at least one of a plurality of floor combustion cells. 
     
     
       12. The biochar kiln of  claim 9 , wherein the zones are managed for variable kiln wood, kiln biochar, stack smoke, stack mix, stack burner temperature, and flue gas. 
     
     
       13. The biochar kiln of  claim 9 , wherein the zones are monitored by one or more sensor and/or dampers.