Apparatus, system, and method for operating and controlling combustor for ground or particulate biomass

Abstract

An apparatus, method, and system for combusting bridging fuel which includes biomass material. The apparatus includes an enclosure having a relatively thin wall defining a firebox. A combustion air manifold, and exhaust manifold, and heat exchanger are positioned along the center horizontal axis of the firebox. A fuel feed conveyor enters through the wall of the firebox and extends along the top of the firebox through a feed opening. A temperature sensor is positioned on the exterior of the wall of the firebox. A controller is operatively connected to the temperature sensor and the fuel feed conveyor. If the temperature sensor exceeds a set point, the controller automatically operates the fuel feed conveyor to refill the firebox with fuel. This can reinsulated the wall of the firebox so that fuel surrounds the combustion. Heat is extracted from the combustion by the heat exchanger while the exterior wall of the firebox is kept relatively cool by the insulating layer of fuel. The automatic fuel refill process allows combustion to be continuous instead of requiring shut-down of combustion and re-ignition after filling the firebox with fuel. In one aspect of the invention, the fuel feed conveyor can be automatically reversed after the firebox is filled to plug fuel in the feed opening to seal it and preserve a sole exhaust path through the exhaust manifold. A method according to the invention causes a refilling of fuel into a firebox upon sensing a condition indicative of a collapse of the bridging fuel in the firebox during combustion, losing its insulating effect at that location. The refilling is adapted to reinsulated the firebox with the fuel.

1 . A method of combusting biomass that has bridging characteristics comprising:
 a. igniting the biomass internally so that it burns inside out;   b. automatically detecting if the biomass caves in or is consumed to its exterior;   c. if so, filling any gap in the biomass with additional biomass.   
     
     
         2 . The method of  claim 1  wherein the bridging biomass comprises ground or particulate biomass. 
     
     
         3 . The method of  claim 1  wherein the bridging biomass comprises biomass comprises ground or particulate or relatively small biomass in combination with other combustible substance. 
     
     
         4 . The method of  claim 3  wherein the other combustible substance comprises manure. 
     
     
         5 . The method of  claim 1  wherein the step of detecting comprises monitoring temperature on the exterior of the biomass. 
     
     
         6 . The method of  claim 5  wherein monitoring temperature comprises enclosing the biomass in a container and measuring temperature on the exterior of the container. 
     
     
         7 . The method of  claim 6  wherein the container comprises a firebox with a metal wall. 
     
     
         8 . The method of  claim 7  wherein the temperature is measured on the exterior of the metal wall. 
     
     
         9 . The method of  claim 5  wherein the temperature is measured independently at a plurality of locations on the exterior of the biomass. 
     
     
         10 . The method of  claim 1  wherein the step of filing comprises automatically moving biomass to the gap upon the step of detecting. 
     
     
         11 . The method of  claim 6  further comprising automatically moving biomass through an opening into the container to the gap upon the step of detecting. 
     
     
         12 . The method of  claim 11  further comprising sealing the opening into the container. 
     
     
         13 . The method of  claim 12  wherein the step of sealing comprises sealing the opening with biomass. 
     
     
         14 . The method of  claim 1  further comprising injecting combustion air into the biomass. 
     
     
         15 . The method of  claim 14  further comprising controlling the amount of combustion air. 
     
     
         16 . The method of  claim 1  further comprising extracting heat from combustion of the biomass. 
     
     
         17 . The method of  claim 16  wherein the step of extracting heat comprises heating air. 
     
     
         18 . The method of  claim 16  wherein the step of extracting heat comprises heating fluid. 
     
     
         19 . The method of  claim 1  further comprising using heat from combustion of the biomass. 
     
     
         20 . The method of  claim 19  wherein the step of using heat comprises boiling water to produce steam. 
     
     
         21 . A method of filling a combustion chamber with fuel comprising:
 a. moving fuel into the combustion chamber through an inlet opening;   b. allowing the fuel to drop by gravity to at least substantially fill the chamber;   c. moving a portion of the fuel back towards the inlet opening to at least substantially pack and plug the inlet opening.   
     
     
         22 . The method of  claim 21  wherein the fuel is a bridging fuel. 
     
     
         23 . The method of  claim 21  wherein the inlet opening is at the end of a tube or conduit. 
     
     
         24 . The method of  claim 21  wherein the fuel is moved by an auger. 
     
     
         25 . The method of  claim 24  wherein the fuel is moved into the chamber by the auger and the portion of fuel is moved back by reversing the auger. 
     
     
         26 . The method of  claim 21  wherein the fuel is moved upon detection of an event that indicates need for additional fuel. 
     
     
         27 . The method of  claim 26  wherein the event is a rise in temperature on the exterior of the combustion chamber. 
     
     
         28 . A method of controlling combustion in a firebox adapted to combust a bridging biomass fuel comprising:
 a. igniting the fuel substantially internally of the fuel so that non-combusting fuel surrounds combusting fuel and insulates the exterior of the non-combusting fuel from substantial heat of combustion;   b. detecting if there is any loss of insulation around the combustion;   c. if so, move fuel in a manner which re-establishes insulation around the combustion.   
     
     
         29 . The method of  claim 28  wherein the step of detecting comprises monitoring if temperature at a point outside the insulation exceeds a certain level. 
     
     
         30 . A control system for a combustor of naturally bridging organic fuel or mixture of naturally bridging organic fuel with other materials, where the combustor includes a firebox with a wall having a top, bottom, opposite sides, and opposite ends and defining an interior and exterior, a clean out transporter motor operatively connected to a clean out transporter at or near the bottom interior, a fuel feed transporter motor operatively connected to a fuel feed transporter at or near the top interior in communication with a feed inlet into the firebox, a combustion air fan or pump motor operatively connected to a combustion air manifold extending into the firebox, a heat exchanger fan, pump, or turbine operatively connected to a heat exchanger extending into the firebox, and an exhaust chamber in fluid communication with an exhaust air manifold extending into the firebox, comprising:
 a. a controller;   b. a temperature sensor on the exterior of the firebox having a threshold temperature setting;   c. a power supply;   d. a program operatively executable by the controller which reads the temperature sensor and if the threshold temperature is exceeded:
 i. reduces or shuts off the combustion air fan or pump motor; 
 ii. operates the fuel feed transporter motor in a first direction; 
 iii. operates the fuel feed transporter motor in a second direction. 
   
     
     
         31 . The system of  claim 30  wherein the controller is programmable. 
     
     
         32 . The system of  claim 30  wherein the controller is digital. 
     
     
         33 . The system of  claim 30  further comprising a thermostat in operative communication with the controller. 
     
     
         34 . The system of  claim 30  further comprising a smoke detector in operative communication with the controller. 
     
     
         35 . The system of  claim 30  further comprising an igniter in the firebox operatively connected to the controller. 
     
     
         36 . The system of  claim 30  further comprising a vibrator motor operatively connected to a vibrator device which is operatively connected to the firebox. 
     
     
         37 . The system of  claim 30  further comprising a plurality of temperature sensors operatively connected to the controller. 
     
     
         38 . A method of combusting bridgeable fuels comprising:
 a. monitoring temperature of an exterior point on a firebox enclosing the fuel and having a fuel feed inlet;   b. monitoring if the fuel feed inlet is substantially sealed;   c. if the temperature of the exterior point exceeds a set point or the fuel feed inlet is not substantially sealed, commencing an automatic sequence comprising:
 i. moving fuel through the fuel feed inlet into the firebox; 
 ii. moving fuel to seal the fuel feed inlet. 
   
     
     
         39 . The method of  claim 38  further comprising monitoring temperature of a plurality of exterior points on the firebox. 
     
     
         40 . The method of  claim 38  wherein the fuel is moved through the fuel feed inlet by a conveying mechanism that can operate in opposite directions. 
     
     
         41 . The method of  claim 40  wherein the fuel is moved into the firebox by operating the conveying mechanism in a first direction and moved to seal the fuel feed inlet by operating the conveying mechanism in the opposite direction. 
     
     
         42 . The method of  claim 38  wherein the fuel feed inlet is monitored by sensing temperature at or around the fuel feed inlet and, if sensed temperature exceeds a threshold assuming the fuel feed inlet is not substantially sealed. 
     
     
         43 . The method of  claim 38  wherein the fuel is moved by am electrical motor or actuator of a conveying mechanism and amperage draw of the electrical motor or actuator is monitored to determine when the firebox is full of fuel and when the fuel feed inlet is substantially sealed. 
     
     
         44 . The method of  claim 38  further comprising monitoring an exhaust pathway for a condition indicative of a fire, and reducing combustion if such a condition is indicated. 
     
     
         45 . The method of  claim 38  further comprising exchanging heat from combustion in the firebox with a heat exchange medium, and monitoring the temperature of the heat exchange medium for a temperature indicative of a condition, and if such temperature is met, reducing combustion. 
     
     
         46 . The method of  claim 38  wherein the step of moving fuel into the firebox is a timed event. 
     
     
         47 . The method of  claim 38  further comprising moving ash from the firebox. 
     
     
         48 . A method of combusting bridgeable organic fuel in a combustion zone comprising:
 a. surrounding the combustion zone with the fuel;   b. monitoring whether a thermostat calls for heat and, if so,
 i. injecting combustion air into the combustion zone, and 
 ii. exchanging a heat exchange medium to and from the combustion zone; 
 iii. monitoring temperature at a point outside the fuel and, if temperature exceeds a set point,
 1. turning combustion air off; 
 2. moving more fuel around the combustion zone. 
 
   
     
     
         49 . The method of  claim 48  wherein the fuel is vibrated when combustion air is injected. 
     
     
         50 . The method of  claim 48  wherein combustion byproducts are removed before combustion air is injected. 
     
     
         51 . The method of  claim 48  wherein combustion air and heat exchange medium exchanging are dynamically balanced during combustion air injection. 
     
     
         52 . The method of  claim 48  wherein the step of moving more fuel around the combustion zone comprises moving fuel from a fresh fuel supply through a path to the fuel surrounding the combustion zone. 
     
     
         53 . The method of  claim 52  further comprising substantially sealing the path after moving more fuel around the combustion zone. 
     
     
         54 . The method of  claim 52  further comprising monitoring temperature at or around the path.