Apparatus and Methods For Providing Uniformly Volume Distributed Combustion of Fuel

Abstract

A combustor apparatus and method for the combustion of viscous fuels are provided. The combustor apparatus can include a precombustion chamber particularly adapted to heat and at least partially combust a heavy primary fuel, and a main combustion chamber adapted to combust the primary fuel uniformly through the main combustion chamber (in flameless mode). The precombustion chamber can include at least one air injection inlet port positioned to induce a first stage vortex in the main body portion of the housing of the precombustion chamber. Further, the precombustion chamber can be interfaced with a main combustion chamber to induce a second stage vortex within the main combustion chamber. The main combustion chamber can have an extended axial length in order to accommodate heavier fuels that require additional time to sufficiently combust (oxidize) within the combustion chamber.

1 . An apparatus for providing flameless combustion of a viscous fuel, the apparatus comprising:
 a precombustion chamber adapted to heat and at least partially combust a primary fuel, the precombustion chamber including:
 an outer housing having an enclosed proximal end portion, an open distal end portion, and a substantially hollow main body portion extending therebetween and substantially enclosing a precombustion chamber cavity, 
 at least one air injection inlet port extending through the main body portion of the outer housing and positioned to inject combustion air into the precombustion chamber, the at least one air injection inlet port further positioned to induce a first stage vortex in the main body portion of the housing of the precombustion chamber, 
 at least one primary fuel nozzle positioned to inject the primary fuel into the precombustion chamber, 
 an igniter fuel nozzle positioned to inject ignition fuel into the precombustion chamber, and 
 a hollow cylindrical combustion stabilizer positioned within the precombustion chamber cavity to receive igniter fuel and primary fuel and to isolate the primary fuel from a portion of the combustion air when being heated with the igniter fuel, and having a proximal end portion, a distal end portion, and a main body portion extending between the proximal end portion and the distal end portion, the combustion stabilizer main body portion comprising a large diameter sidewall spaced radially inward from the precombustion chamber housing to define an annulus therebetween and having at least one air inlet aperture extending therethrough to receive a portion of the combustion air to thereby supply oxygen to the igniter fuel and to thereby initiate oxidation of the fuel within the combustion stabilizer, the distal end portion in fluid communication with the combustion stabilizer main body portion and having a small diameter sidewall having a diameter substantially smaller than the large diameter sidewall of the main body, the distal end portion of the combustion stabilizer further having an unobstructed distal end aperture for expelling heated primary fuel into the precombustion chamber cavity adjacent to the distal end portion of the precombustion chamber housing; and 
   a main combustion chamber adapted to combust the primary fuel, the main combustion chamber including:
 a housing having an at least partially enclosed proximal end portion including an exhaust aperture, an enclosed distal end portion, and an elongate main body extending therebetween and substantially enclosing a main combustion chamber cavity, the main body having an inner main body diameter and having a main body axial length extending at least approximately twice the main body diameter, the main body axial length having a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance within the main combustion chamber based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof, 
 an exhaust-inlet located adjacent the proximal end portion of the main combustion chamber housing and extending through the main body of the main combustion chamber housing, and positioned to receive the at least partially combusted primary fuel from the precombustion chamber and to induce a second stage vortex within the main body of the main combustion chamber housing, and 
 a combustion exhaust tube extending from and interfaced with the proximal end portion of the main combustion chamber housing and extending coaxially along a same longitudinal axis as the main combustion chamber housing, and having an open distal end portion and an elongate main body extending between the open distal end portion of the combustion exhaust tube and the proximal end portion of the main combustion chamber housing, the distal end portion of the combustion exhaust tube extending axially within the main combustion chamber cavity to a location between a position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and a position located axially a distance of at least one exhaust tube main body diameter from the distal end portion of the main combustion chamber housing. 
   
     
     
         2 . An apparatus as defined in  claim 1 , wherein the primary fuel is viscous at ambient supply temperature, the apparatus further comprising a primary fuel supply system to provide the primary viscous fuel for combustion, the primary fuel supply system including:
 a compressed gas injector connected to a portion of the primary fuel supply system to form at least a suspension to thereby minimize a size of fuel droplets exiting the at least one primary fuel nozzle;   a temperature sensor positioned to detect an exhaust gas temperature of the exhaust gas exiting the combustion exhaust tube; and   a logic circuit positioned to control a flow of the igniter fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust tube.   
     
     
         3 . An apparatus as defined in  claim 1 , wherein a diameter of the second stage vortex is substantially larger than the diameter of the first stage vortex. 
     
     
         4 . An apparatus as defined in  claim 1 ,
 wherein the pre-combustion chamber housing has an axial length to main body cross-sectional diameter ratio of between 2.5:1 to 4:1; and   wherein the combustion air to mass flow of the primary fuel has a ratio of between 35:1 to 45:1.   
     
     
         5 . An apparatus as defined in  claim 1 , wherein the combined airflow rate of the combustion air entering the precombustion chamber is set based upon predetermined ratios of momentum and mass flow of primary fuel for a given fuel flow rate defining an air-fuel flow to thereby enhance instability of the air-fuel flow. 
     
     
         6 . An apparatus as defined in  claim 1 ,
 wherein the primary fuel is glycerin;   wherein the housing of the pre-combustion chamber is of a substantially cylindrical shape;   wherein the housing of the main combustion chamber is of a substantially cylindrical shape;   wherein the combustion exhaust tube has a configuration comprising one or more of the following: a cylindrical shape and a venturi shape; and   wherein the combined airflow rate of the air exiting the at least one air inlet port and mass flow of primary fuel entering the precombustion chamber has a ratio between 20:1 to 40:1 to thereby enhance instability of the air-fuel flow.   
     
     
         7 . An apparatus as defined in  claim 1 ,
 wherein the primary fuel is glycerin; and   wherein a shape of the main body of the main combustion chamber housing is configured to provide a uniform temperature and pressure distribution inside of the main combustion chamber cavity and to optimize a pressure drop adjacent the open distal end portion of the combustion exhaust tube.   
     
     
         8 . An apparatus as defined in  claim 1 ,
 wherein the primary fuel is glycerin;   wherein the main combustion chamber cavity has an axial length to main body cross-sectional diameter ratio of between 4:1 to 6:1; and   wherein the combustion exhaust tube has an axial offset distance from the distal end portion of the housing of the main combustion chamber-to-combustion exhaust tube cross-sectional diameter ratio of between approximately 1.5:1 to 2.5:1.   
     
     
         9 . An apparatus as defined in  claim 1 ,
 wherein the main combustion chamber housing further includes an annulus extending between the proximal end and distal end portions of the housing; and   wherein the distal end portion of the main combustion chamber housing includes a passageway extending from and in communication with the annulus and a plurality of swirl nozzles positioned to supply a cooling fluid to a portion of the cavity of the housing adjacent the distal end of the combustion exhaust tube, the cooling fluid including oxygen and trapped fuel film extracted from within the cavity adjacent the proximal end portion of the housing, the nozzles oriented to enhance instability of the fuel flow adjacent the distal end of the combustion exhaust tube.   
     
     
         10 . An apparatus as defined in  claim 1 ,
 wherein the main combustion chamber further comprises a perforated liner secured to interior surfaces of the outer housing, inner bottom wall and inner top wall, the portion of the liner adjacent the inner bottom wall and inner top wall having an arc configured to provide constant vortex radial velocity conditions to thereby provide minimal hydrodynamic losses and to thereby confine unvaporized fuel droplets in equilibrium in an orbit of rotation of the second stage vortex stream;   wherein the apparatus further comprises:
 a cooling air supply system to provide a fluid to cool inner surfaces of the main combustion chamber housing and to provide the fluid to the plurality of swirl nozzles to thereby enhance instability of the fuel flow adjacent the distal end of the combustion exhaust tube, and
 a recirculation passageway extending between the proximal end and distal end portions of the housing positioned to return trapped fuel film received from a portion of the cavity of the housing adjacent the proximal end of the combustion exhaust tube; and 
 
   wherein the at least partially enclosed proximal end portion of the main combustion chamber housing includes an annular raised lip ring extending into the recirculation passageway and configured to cause a venturi effect within the recirculation passageway.   
     
     
         11 . An apparatus for providing flameless combustion of a fuel, the apparatus comprising a main combustion chamber adapted to combust a primary fuel, the main combustion chamber including:
 a housing having a proximal end portion including an exhaust aperture, a distal end portion, and an elongate main body extending therebetween and substantially enclosing a main combustion chamber cavity, the main body having an inner main body diameter and having a main body axial length; and   an exhaust-inlet extending through the main body of the main combustion chamber housing at an inlet location, and positioned to receive at least partially combusted primary fuel from a precombustion chamber and to induce a vortex within the main body of the main combustion chamber housing, the main body axial length extending distally from the inlet location a distance approximately equal to or greater than a value of the inner main body diameter.   
     
     
         12 . An apparatus as defined in  claim 11 , wherein the main body axial length has a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the exhaust-inlet within the main combustion chamber cavity based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof. 
     
     
         13 . An apparatus as defined in  claim 11 , wherein the main combustion chamber further comprises:
 a combustion exhaust conduit extending from and interfaced with the proximal end portion of the main combustion chamber housing and extending coaxially along a same longitudinal axis as the main combustion chamber housing, and having an open distal end portion and an elongate main body extending between the open distal end portion of the combustion exhaust conduit and the proximal end portion of the main combustion chamber housing, the distal end portion of the combustion exhaust conduit extending within the main combustion chamber cavity to a location between a position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and a position axially adjacent to the distal end portion of the main combustion chamber housing, an axial spacing of the distal end portion of the combustion exhaust conduit from an inner surface of the distal end portion of the main combustion chamber housing having a value approximately equal to or greater than that of the inner diameter of the distal end portion of the exhaust conduit main body.   
     
     
         14 . An apparatus as defined in  claim 13 ,
 wherein the exhaust-inlet is positioned normal to an inner surface portion of the main body of the main combustion chamber housing adjacent thereto; and   wherein an outer surface of the combustion exhaust conduit includes a swirl enhancer comprising at least one of the following: a spiral recess extending along a substantial portion of the longitudinal length thereof, or a spiral protuberance extending along the substantial portion of the longitudinal length thereof, to thereby enhance the inducement of the vortex within the main body of the main combustion chamber housing.   
     
     
         15 . An apparatus as defined in  claim 13 ,
 wherein the main body of the main combustion chamber housing has an axial length to main body cross-sectional inner diameter ratio of between approximately 4:1 to 6:1; and   wherein the distal end portion of the combustion exhaust conduit has an axial offset distance from the distal end portion of the housing of the main combustion chamber to combustion exhaust conduit distal end portion cross-sectional diameter ratio of between approximately 5:1 to 2.5:1.   
     
     
         16 . An apparatus as defined in  claim 11 , wherein the vortex is a second stage vortex, the apparatus further comprising a precombustion chamber adapted to heat and at least partially combust the primary fuel, the precombustion chamber including:
 a housing having a proximal end portion, an open distal end portion, and a substantially hollow main body portion extending therebetween and having a substantially cylindrical inner surface substantially enclosing a precombustion chamber cavity; and   at least one air injection inlet port extending through the main body portion of the precombustion chamber housing and positioned to inject combustion air into the precombustion chamber, the at least one air injection inlet port further positioned to induce a first stage vortex in the main body portion of the housing of the precombustion chamber.   
     
     
         17 . An apparatus as defined in  claim 11 , further comprising a precombustion chamber adapted to heat and at least partially combust the primary fuel, the precombustion chamber including:
 a housing having a proximal end portion, an open distal end portion, and a substantially hollow main body portion extending therebetween and ,substantially enclosing a precombustion chamber cavity;   at least one primary fuel nozzle positioned to inject primary fuel into the precombustion chamber;   an igniter fuel nozzle positioned to inject ignition fuel into the precombustion chamber; and   a hollow combustion stabilizer positioned within the precombustion chamber cavity to receive the igniter fuel and the primary fuel and to isolate the primary fuel from a portion of the combustion air when being initially heated with the igniter fuel, and having a proximal end portion, a distal end portion, and a main body portion extending between the proximal end portion and the distal end portion, the combustion stabilizer main body portion comprising a large diameter sidewall spaced radially inward from the precombustion chamber housing to define an annulus therebetween and having at least one air inlet aperture extending therethrough to receive a portion of the combustion air to thereby supply oxygen to the igniter fuel and to thereby initiate oxidation of the fuel within the combustion stabilizer, the distal end portion of the combustion stabilizer in fluid communication with the combustion stabilizer main body and having a small diameter sidewall having a diameter substantially smaller than the large diameter sidewall of the main body, the distal end portion further having an unobstructed distal end aperture for expelling heated primary fuel into the precombustion chamber cavity adjacent to the distal end portion of the precombustion chamber housing.   
     
     
         18 . An apparatus as defined in  claim 17 , wherein a diameter of the second stage vortex is substantially larger than the diameter of the first stage vortex. 
     
     
         19 . An apparatus as defined in  claim 17 , wherein the primary fuel is viscous at ambient supply temperature, the apparatus further comprising a primary fuel supply system to provide the primary viscous fuel for combustion, the primary fuel supply system including:
 a compressed gas injector connected to a portion of the primary fuel supply system to form at least a suspension to thereby minimize a size of fuel droplets exiting the at least one primary fuel nozzle;   a temperature sensor positioned to detect an exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit; and   a logic circuit configured to control a flow of the igniter fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit.   
     
     
         20 . An apparatus as defined in  claim 17 ,
 wherein the pre-combustion chamber housing has an axial length to main body cross-sectional diameter ratio of between 2.5:1 to 4:1;   wherein the combustion air to mass flow of the primary fuel has a ratio of between 30:1 to 50:1; and   wherein the combined airflow rate of the combustion air entering the precombustion chamber is set based upon predetermined ratios of momentum and mass flow of primary fuel for a given fuel flow rate defining an air-fuel flow to thereby enhance instability of the air-fuel flow.   
     
     
         21 . A method of providing flameless combustion of a viscous fuel, the method comprising the steps of:
 inducing a first stage vortex in a primary fuel-air mixture within a main body portion of a precombustion chamber of a flameless combustor;   receiving the primary fuel-air mixture having the first stage vortex induced state within a main body of a main combustion chamber of the flameless combustor; and   inducing a second stage vortex in the received primary fuel-air mixture to form a complex vortex pattern to thereby enhance flameless oxidation of the primary fuel within the main body of the main combustion chamber, a diameter of the first stage vortex being substantially smaller than a diameter of the second stage vortex.   
     
     
         22 . A method as defined in  claim 21 ,
 wherein the step of inducing a second stage vortex includes expelling the primary fuel-air mixture tangentially into the main combustion chamber cavity through a precombustion chamber exhaust outlet; and   wherein the precombustion chamber exhaust outlet is axially spaced apart from the combustion exhaust conduit inlet a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the precombustion chamber exhaust outlet within the main combustion chamber cavity based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof.   
     
     
         23 . A method as defined in  claim 22 , wherein the primary fuel is a glycerol fuel, the method further comprising the step of:
 preselecting the value of the axial separation between the precombustion chamber exhaust outlet and the combustion exhaust conduit inlet to provide the sufficient pyrolyzed fuel travel distance from the exhaust-inlet port within the main combustion chamber cavity responsive to one or more fuel performance characteristics of the glycerol fuel.   
     
     
         24 . A method as defined in  claim 21 , further comprising the steps of:
 interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel;   igniting a secondary fuel within the precombustion chamber adjacent a flowpath of the primary fuel to at least partially combust the primary fuel within the precombustion chamber of the flameless combustor;   sensing a temperature of the exhaust gas exiting the combustion exhaust conduit of the main combustion chamber; and   controlling a flow of the secondary fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit.   
     
     
         25 . A method as defined in  claim 21 , further comprising the steps of:
 interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel; and   aerating the primary fuel prior to entry into the precombustion chamber to minimize a size of fuel droplets entering the precombustion chamber.   
     
     
         26 . A method as defined in  claim 21 , further comprising the steps of:
 providing a main vortex combustion chamber of a flameless combustor having a main body substantially enclosing a main combustion chamber cavity, the main combustion chamber cavity having an axial length approximately equal to or greater than an inner diameter of the main combustion chamber cavity; and   providing a combustion exhaust conduit within and axially coincident with the main combustion chamber cavity, the combustion exhaust conduit having an inlet positioned at a location between an axial position distally forward of an axial midpoint position of the elongate main body of the main combustion chamber housing and an axial position within the main combustion chamber cavity adjacent the distal end portion of the main combustion chamber housing, an axial spacing of the distal end portion of the combustion exhaust conduit from an inner surface of the distal end portion of the main combustion chamber housing having a value approximately equal to or greater than that of the inner diameter of the distal end portion of the exhaust conduit.   
     
     
         27 . A method of providing flameless combustion of a viscous fuel, the method comprising the steps of:
 providing a main vortex combustion chamber of a flameless combustor having a main body substantially enclosing a main combustion chamber cavity, the main combustion chamber cavity having an axial length approximately equal to or greater than an inner diameter of the main combustion chamber cavity; and   inducing flameless oxidation of a primary fuel within the main combustion chamber cavity, the step of inducing flameless oxidation comprising the step of inducing a vortex within the main combustion chamber cavity to enhance formation of a fuel air mixture.   
     
     
         28 . A method as defined in  claim 27 , wherein the main body ( 101 ) is an elongate main body ( 101 ), the method further comprising the step of providing a combustion exhaust conduit within and axially coincident with the main combustion chamber cavity, the combustion exhaust conduit having an inlet positioned at a location between an axial position distally forward of an axial midpoint position of the main body of the main combustion chamber housing and an axial position within the main combustion chamber cavity adjacent the distal end portion of the main combustion chamber housing, an axial spacing of the distal end portion of the combustion exhaust conduit from an inner surface of the distal end portion of the main combustion chamber housing having a value approximately equal to or greater than that of the inner diameter of distal end portion of the exhaust conduit. 
     
     
         29 . A method as defined in  claim 27 , further comprising the step of:
 injecting the primary fuel into the main combustion chamber cavity through a precombustion chamber exhaust outlet, the precombustion chamber exhaust outlet axially spaced apart from the combustion exhaust conduit inlet a preselected value preselected to provide a sufficient pyrolyzed fuel travel distance from the precombustion chamber exhaust outlet within the main combustion chamber cavity based upon one or more fuel performance characteristics of the primary fuel to provide substantially complete pyrolization thereof.   
     
     
         30 . A method as defined in  claim 29 , wherein the primary fuel is a glycerol fuel, the method further comprising the step of:
 preselecting the value of the axial separation between the precombustion chamber exhaust outlet and the combustion exhaust conduit inlet to provide the sufficient pyrolyzed fuel travel distance from the precombustion chamber exhaust outlet within the main combustion chamber cavity responsive to one or more fuel performance characteristics of the glycerol fuel.   
     
     
         31 . A method as defined in  claim 27 , further comprising the steps of:
 interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel;   igniting a secondary fuel within the precombustion chamber adjacent a flowpath of the primary fuel to at least partially combust the primary fuel within the precombustion chamber of the flameless combustor;   sensing a temperature of the exhaust gas exiting the combustion exhaust conduit of the main combustion chamber; and   controlling a flow of the igniter fuel into the precombustion chamber responsive to the exhaust gas temperature of the exhaust gas exiting the combustion exhaust conduit.   
     
     
         32 . A method as defined in  claim 31 , wherein the induced vortex in the main combustion chamber is the second stage vortex, the method further comprising the step of:
 inducing a first stage vortex in a precombustion chamber of a flameless combustor to form a complex vortex pattern, a diameter of the first stage vortex being substantially smaller than a diameter of the second stage vortex.   
     
     
         33 . A method as defined in  claim 27 , further comprising the steps of:
 interfacing a precombustion chamber with the main combustion chamber, the precombustion chamber adapted to heat and at least partially combust the primary fuel; and   aerating the primary fuel prior to entry into the precombustion chamber to minimize a size of fuel droplets entering the precombustion chamber.   
     
     
         34 . A method as defined in  claim 28 , further comprising the step of:
 selecting a shape of the main body of the main combustion chamber that provides a substantially uniform temperature and pressure distribution inside at least a substantial portion of the main chamber and that substantially optimizes a pressure drop adjacent the inlet of the combustion exhaust conduit.