Corn Burners – Solid Fuel Burners

Patent application

HYBRID CONVECTION COMBUSTION SYSTEM

BACKGROUND OF THE INVENTION

Field of the Invention

The present disclosure is directed to a combustion system utilizing both free convention airflow and forced convections airflow to maximize the combustion efficiency of a fuel source burned therein, as well as optimizing the operating efficiency of the overall system, by optimizing the forced convection airflow requirements of the system.

DESCRIPTION OF THE RELATED ART

Solid fuel is one of the oldest combustible fuel sources known to mankind. As such, numerous devices and systems have been developed throughout the ages having widely varying degrees of efficiency for the combustion of solid fuel for a variety of purposes such as, cooking, heating, steam generation, etc. More recently, there has been considerable interest in the area of renewable energy sources, including, solid fuels. These renewable solid fuel sources include processed plant matter, plant byproducts, such as olive cake pellets and algae cake pellets, biomass, waste treatment byproducts, and vegetable based products, for example, dried corn kernels.

A primary consideration in a design of any solid fuel combustion unit is a provision of sufficient air for efficient combustion of the fuel source as well as to carry unwanted contaminants in the exhaust gas away from the combustion chamber. In the earliest and simplest form of solid fuel combustion, ambient air is drawn through a solid fuel supply during combustion by way of naturally occurring free convection currents in which air enters the solid fuel supply with oxygen for combustion and exits the same with combustion products and byproducts. While free convection offers a generally cost free supply of combustion airflow, these savings may not be realized as a result of overall inefficiency due to low burn rates as well as incomplete combustion of the solid fuel supply in such systems.

In order to improve the combustion efficiency of a solid fuel source, external air supplies have been utilized in conjunction with solid fuel combustion devices. More in particular, a forced convection airflow supply can be introduced into a solid fuel supply in a combustion chamber by way of fans, blowers, compressed air, or other such sources as are utilized to supply an amount of airflow on demand. While the use of such external air supply sources can improve combustion efficiency of a solid fuel source, there is necessarily a tradeoff in the cost associated with installation, operation, and maintenance of such an external air supply and the benefits of increased combustion efficiency.

One attempt to achieve a balance between free and forced convection airflow in order to improve the efficiency of a solid fuel combustion system includes an external air supply, in the form of a blower, structured to introduce a forced convection airflow into the bottom of a combustion chamber. The system further utilizes an assembly for the induction of ambient air via free convection around and through a portion of a secondary combustion chamber for the dual purposes of providing a means of temperature control to prevent excessive temperature rise in the inner walls of a combustion assembly, as well as to provide additional air for further combustion of initial exhaust gases in the secondary chamber.

Another system which employees an external air supply, once again, in the form of a blower, splits the external air supply from the blower into at least two portions for introduction into a combustion device. Specifically, one portion of the external air supply is directed into the combustion chamber so as to provide oxygen to the solid fuel supply for combustion, while another portion is directed into the exhaust stack from the combustion chamber, to facilitate the discharge of the exhaust gases from the system. Yet another system employs a blower directly in the exhaust stack for purposes of retrofitting a conventional central heating oil furnace to facilitate combustion of fragmented wood type fuels.

While the foregoing systems, when properly operated, should provide improve combustion efficiency versus a simple free convection air supply system, each requires a considerable external air supply for operation. As such, it would be beneficial to provide a combustion system physically structured to optimizes the utilization of free convection airflow and force convection airflow to effect very high efficiency combustion of a solid fuel supply. It would also be desirable to provide a combustion system having a control mechanism in place to both monitor the degree of combustion in the terminal exhaust gasses and regulate a forced airflow supply to the system to maintain a high efficiency combustion process. Yet another advantage of such a system would be to maximize the inductive forces generated from the introduction of a forced convection airflow into the system, such as by way of one or more convection assembly structured to direct exhaust gasses from the combustion chamber to a terminal exhaust stack. As will be demonstrated hereinafter, the foregoing factors may be combined in such a manner so as to provide a very high efficiency hybrid convection combustion system which optimizes the usage of free and forced convection airflow supplies.

SUMMARY OF THE INVENTION

The present disclosure is directed to a hybrid convection combustion system, as illustrated throughout the figures, wherein the system is structured to utilize both free convention and forced convection airflow sources to maximize the combustion and operating efficiencies of the system. The present hybrid convection combustion system comprises a combustion chamber assembly structured to burn a fuel source, and in at least one embodiment, a solid fuel source, wherein the solid fuel source comprises a plurality of discrete solid fuel units. The combustion system also includes a fuel supply assembly disposed in a fuel transferring relation to the combustion chamber assembly, so as to allow for continuous operation of the hybrid convection combustion system.

The hybrid convection combustion system further comprises an airflow supply assembly disposed in an airflow transferring relation to at least the combustion chamber assembly, the airflow supply assembly being structured and disposed to direct at least a free convention airflow supply thereto. The airflow supply assembly further comprises a free convection airflow supply plenum for directing the free convection airflow supply. The airflow supply assembly further comprising a forced convection airflow supply structured to provide a forced convection airflow into at least a portion of the hybrid convection combustion system during operation.

In at least one embodiment, the hybrid convection combustion system comprises an afterburner assembly disposed in an operative orientation relative to the combustion chamber assembly, the afterburner assembly comprising a forced convection airflow preheat unit, wherein the forced convection airflow supply is structured to provide a forced convection airflow to the forced convection airflow preheat unit.

In accordance with the present disclosure, the hybrid convection combustion system further comprises a draught induction assembly disposed in an operative orientation relative to the combustion chamber. More in particular, the draught induction assembly comprises at least one, and in at least one embodiment, a plurality of convection chambers disposed in a series configuration structured to induce a free convection airflow through at least a portion of the combustion chamber assembly during operation. Moreover, each convection chamber comprises a convection zone at least partially defining a free convection airflow path for an exhaust gas airflow from said combustion chamber assembly and a discharge section having a discharge port, wherein the exhaust gas airflow from the convection zone through the discharge port of a convection chamber induces the free convection airflow through at least a portion of the combustion chamber assembly, thereby optimizing both the combustion and operating efficiencies of a hybrid convection combustion system in accordance with the present disclosure.

These and other objects, features and advantages of the present invention will become clearer when the drawings as well as the detailed description are taken into consideration.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature of the present invention, reference should be had to the following detailed description taken in connection with the accompanying drawings in which:

Figure 1 is an perspective view of one embodiment of a hybrid convection combustion system in accordance with the present disclosure.

Figure 2 is cross-sectional elevation of an embodiment of a hybrid convection combustion system in accordance with the present disclosure.

Figure 3 is a cross-sectional elevation of a portion of one embodiment of a hybrid convection combustion assembly in accordance with the present disclosure.

Figure 4 is a perspective view of a portion of yet another embodiment of a hybrid convection combustion assembly in accordance with the present disclosure.

Figure 5 is a perspective view of one embodiment of a forced convection airflow preheat assembly in accordance with the present disclosure.

Figure 6 is a cross-sectional perspective elevation of an embodiment of a hybrid convection combustion assembly illustrating one embodiment of a heat exchange assembly in accordance with the present disclosure.

Figure 7 is cross-sectional elevation illustrative of one embodiment of a draught induction assembly in accordance with the present disclosure.

Figure 8 is a schematic representation of a hybrid convection combustion assembly disposed in an operative relationship with an external system in accordance with the present disclosure.

Like reference numerals refer to like parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As stated above, the present disclosure is directed to a hybrid convection combustion system, generally as shown at 10 throughout the figure. Figure 1 is illustrative of one embodiment of a hybrid convection combustion system 10. As illustrated in the embodiment of Figure 1, the hybrid convection combustion system 10 comprises a combustion chamber assembly 20, an airflow supply assembly 30, an afterburner assembly 40, a draught induction assembly 50, and a fuel supply assembly 60, each of which are described below in detail.

Figure 6 illustrates one embodiment of a heat exchange assembly 70 associated with a hybrid convection combustion system 10 in accordance with the present disclosure, which is also described in greater detail below. As illustrated schematically in Figure 8, the heat exchange assembly 70 is structured and disposed in an operative orientation relative to an external system such as, but in no manner limited to, a steam engine, gas turbine, water heater, facility heating system, etc. As discussed in detail below, the heat exchange assembly 70 in accordance with the present disclosure is structured to provide an amount of heat energy to such an external system sufficient to operate the same.

Turning now to the specific components of a hybrid convection combustion system 10 in accordance with the present disclosure, we begin with the combustion chamber assembly 20. Figure 3 is illustrative of a partial cross section of a portion of one embodiment of a hybrid convection combustion system 10. More in particular, Figure 3 shows a combustion chamber assembly 20 including a fuel support 22 which is mounted in a combustion chamber base 21. As further shown in Figure 3, the fuel support 22 comprises a plurality of air supply ports 23 which are structured to permit the flow of air into the combustion chamber assembly 20 to provide oxygen for combustion of fuel, such as solid fuel, supplied to the combustion chamber assembly 20.

In at least one embodiment, the combustion chamber assembly 20 includes a combustion chamber cover 24 structured to overlie an open upper end of fuel support 22. As shown in Figure 3, the combustion chamber cover 24 comprises upwardly curving sidewalls which terminate at a combustion chamber discharge port 28, the upwardly curving sidewalls structured to direct the exhaust gas airflow generated from the combustion of fuel in the combustion chamber assembly 20 into, in at least one embodiment, an afterburner assembly 40.

A combustion chamber discharge screen 29 may be disposed in overlying relation to the combustion chamber discharge port 28, at illustrated in the embodiment of Figure 3. Combustion discharge chamber screen 29 serves dual purposes, namely, retaining a solid fuel supply within the combustion chamber assembly 20 as well as providing a source of ignition for non-combusted fuel vapors present in the exhaust gas airflow passing therethrough. More in particular, the solid fuel supplied to the fuel support 22 of the combustion chamber assembly 20 may comprise a plurality of discreet solid fuel units, such as pellets or kernels, which are subject to uplift via the free convection airflow entering through free convection airflow supply plenum 31, discussed in greater detailed below, as well as induction forces created via a forced convection airflow supply to the hybrid convection combustion system 10. Thus, the combustion chamber discharge screen 29 serves to prevent solid fuel units from exiting the combustion chamber assembly 20 through the combustion chamber discharge port 28 as a result of these free and/or forced convection airflows. Further, as a result of its proximity to the fuel support 22, on which solid fuel units are burned while the system 10 is in operation, at least portions of the combustion chamber discharge screen 29 will achieve temperatures approaching 3,000 degrees Fahrenheit, which is more than sufficient to ignite non-combusted fuel vapors present in the exhaust gas airflow exiting the combustion chamber assembly 20 through the combustion chamber discharge port 28.

In the embodiment illustrated in Figures 2 and 3, the combustion chamber assembly 20 further comprises a fuel agitator mechanism 25, which is structured to stir the solid fuel units disposed on the fuel support 22 to minimize the agglomeration of the discreet solid fuel units and to facilitate more thorough combustion of the same. More in particular, the fuel agitator mechanism 25 includes an agitator drive assembly 27, which may comprise an electric motor specifically structured for use in high temperature applications, and an agitator 26 which at least partially extends through a portion of fuel support 22 so as to provide direct contact with the plurality of solid fuel units disposed thereon. In operation, the fuel agitator mechanism 25 can be manually activated and deactivated as deemed necessary by a system operator or, in at least one embodiment, a timer or other control mechanism may be employed to dictate conditions under which the fuel agitator mechanism 25 is activated and deactivated. In at least one embodiment, the agitator drive assembly 27 is structured to operate at speed in the range of approximately 500 to 1,000 revolutions per minute (“rpm”). Additionally, in at least one further embodiment, the fuel agitator mechanism 25 is structured to operate in a series of short burst having a duration of between about 1 to 5 seconds each, for example, in one embodiment, the series of short bursts have a duration of about 3 seconds each.

Given the extreme operating conditions of a combustion system, the components of a combustion chamber assembly 20 of the present hybrid convection combustion system 10 may be manufactured from any of a variety of materials such as steel, hardened steel, stainless steel, other metals and/or metal alloys, super alloys, such as, nickel-copper alloys, e.g., MONEL®, nickel-chromium alloys, e.g., INCONEL®, and molybdenum alloys, or engineered materials, in order to maintain structural integrity of the combustion chamber assembly 20 through repeated cycles of heating to temperatures approaching 3,000 degrees Fahrenheit while in operation, and subsequent cooling to ambient temperatures while not in use.

The hybrid convection combustion system 10, as noted above, further comprises an airflow supply assembly 30. The air supply assembly 30 is structured to provide both a free convection airflow supply and a forced convection airflow supply to the hybrid convection combustion system 10 which, as presented below, cooperatively serve to improve the combustion efficiency of the plurality of solid fuel units within the combustion chamber assembly 20. To facilitate the introduction of ambient air into the combustion chamber assembly 20, a free convection airflow supply plenum 31 is provided. As illustrated in the embodiment of Figure 4, the free convection airflow supply plenum 31 is structured and disposed to be mounted below the combustion chamber base 21, as well as below the fuel support 22, as illustrated in Figures 2 and 3. In the illustrative embodiment of Figure 4, the convection airflow supply plenum 31 includes an enlarged opening at its base to allow the unrestricted entry of ambient air, and an upwardly curving back wall structured to direct a free convection airflow to the underside of fuel support 22. As noted above, fuel support 22 comprises a plurality of air supply ports 23 through which the free convection airflow is permitted to pass thereby providing the oxygen necessary for combustion of the solid fuel units disposed on fuel support 22.

Turning to the embodiment of Figure 2, the airflow supply assembly 30 comprises a forced convection airflow supply 32 which, in this illustrative embodiment, comprises a centrifugal blower 33. Of course, it is well within the scope and intent of the present invention for the forced convection airflow supply 32 to comprise any one of a number of airflow supply sources such as, but not limited to, a compressed air canister, an on demand air compressor system, a compressed air storage tank, other types of air blowers, or other such means of providing a forced airflow supply. As also illustrated in Figures 2 and 3, the airflow supply assembly 30 includes a forced convection airflow supply duct 34 structured to transfer the forced convection airflow from the forced convection airflow supply 32 to a portion of the afterburner assembly 40. The forced convection airflow supply 32 is further structured to supply a sources air to sight glass 67 to minimize the accumulation of ash or other contaminants from the portion of the sight glass 67 which may serve to impair the operation of the same.

In at least one embodiment, the airflow supply assembly 30 comprises an air/fuel sensor 35 which is structured to measure the concentration of at least one component in the exhaust gas airflow, such as, by way of example only, a vaporized fuel component which is indicative of incomplete combustion. As shown in Figure 2, the air/fuel sensor 35 is disposed at the top of exhaust stack 57 thereby monitoring the exhaust gas airflow just prior to exiting the hybrid convection combustion system 10. The air/fuel sensor 35 is structured and disposed in operative communication with air/fuel controller 36. More specifically, based on the concentration of one or more target component(s) as measured by the air/fuel sensor 35, the air/fuel controller 36 will act to increase, decrease, or maintain the output of the forced convection airflow supply 32. More in particular, if the air/fuel sensor 35 indicates an excess of non-combusted fuel in the exhaust gas airflow, the air/fuel controller 36 will increase the output of the forced convection airflow supply 32 to provide a greater amount of oxygen to facilitate a more complete combustion of the fuel vapors remaining in the exhaust gas airflow as it pass through the hybrid convection combustion system 10. Conversely, if the air/fuel sensor 35 fails to register the presence of one or more target components above a predetermined minimum concentration, thereby indicating an excess of combustion airflow, the airflow controller 36 will act to reduce the output of the forced convection airflow supply 32, thereby making more efficient use of the same. In at least one embodiment, the air/fuel sensor 35 comprises an oxygen sensor structured to measure the concentration of oxygen in the exhaust gas airflow just prior to exiting the hybrid convection combustion system 10.

As noted above with reference to Figure 2, in at least one embodiment the hybrid convection combustion system 10 in accordance with the present disclosure comprises an afterburner assembly 40. As perhaps illustrated best in Figure 3, the afterburner assembly 40 is disposed above combustion chamber assembly 20 and, in the illustrated embodiment, the afterburner assembly 40 is disposed immediately proximate the combustion chamber discharge port 28. This arrangement of the afterburner assembly 40 in relation to the combustion discharge port 28 serves to maximize the operation of the afterburner assembly 40 on the exhaust gas airflow generated by the combustion of fuel within the combustion chamber assembly 20.

As shown in Figure 3, the afterburner assembly 40 comprises a forced convection airflow preheat unit 42, an air/air heat exchanger 44, and a radiant black body 48. The forced convection airflow preheat unit 42 is structured to receive forced convection airflow from the forced convection airflow supply 32 via forced convection airflow supply duct 34, and to elevate the temperature of the forced convection airflow prior to discharge into the hybrid convection combustion system 10. More in particular, the forced convection airflow preheat unit 42 comprises an air/air heat exchanger 44 through which the forced convection airflow passes prior to discharge into the hybrid convection combustion system 10. As noted above, and as illustrated in best in Figure 3, the air/air heat exchanger is disposed directly proximate the combustion chamber assembly 20 discharge port 28 in the path of the exhaust gas airflow which being generated by combustion of fuel within the combustion chamber assembly 20, the exhaust gases having elevated temperatures in the range of about 1,000 to 1,500 degrees Fahrenheit while the system 10 is operating at steady state. As such, the exhaust gas airflow passing over the air/air heat exchanger 44 in the afterburner assembly 40 serves to significantly increase the temperature of the air/air heat exchanger 44. Further, as the air/air heat exchanger 44 is constructed of a material having favorable thermal conduction properties, such as MONEL® or INCONEL®,the heat energy absorbed by the outer surfaces of the air/air heat exchanger 44 from the exhaust gas airflow will be transferred to the forced convection airflow as it passes over the inner surfaces of the air/air heat exchanger 44.

As best illustrated in Figure 5, the air/air heat exchanger 44 includes a forced convection airflow inlet 45 which is connected to forced convection airflow supply duct 34. Further, in the illustrative embodiments of Figures 3 and 5, the air/air heat exchanger 44 comprises an annular tubing arrangement through which the forced convection airflow passes and a lower annular tube arrangement having at least one forced convection airflow discharge nozzle 46 extending therefrom. In at least one embodiment, such as illustrated in Figure 5, the air/air heat exchanger 44 comprises a plurality of forced convection airflow discharge nozzles 46 which are disposed in a generally upwardly directed manner to facilitate passage of the forced convection airflow through the hybrid convection combustion system 10. In yet one further embodiment, the forced convection airflow discharge nozzle 46 comprises a laminar jet nozzle.

Further, in at least one embodiment, the afterburner assembly 40 comprises a radiant black body 48, such as is illustrated in Figure 3. The radiant black body 48 is constructed of a material exhibiting radiant heat transfer properties, for example, steel or nickel alloys like MONEL® or INCONEL®, and is structured to absorb significant amounts of heat energy present in the exhaust gas airflow discharged from the combustion chamber assembly 20 through combustion chamber discharge port 28. Additionally, the radiant black body 48 is structured to release an amount of the heat energy absorbed from the exhaust gas airflow in a controlled manner to the force convection airflow as it passes through the air/air heat exchanger 44 as well as it is discharged from the air/air heat exchanger 44 via one or more forced convection airflow discharge nozzle 46. As will be appreciated, this arrangement of an air/air heat exchanger 44 and radiant black body 48 allows both conductive heat transfer through the air/air heat exchanger to the incoming forced convection airflow as well as radiant heat transfer from the radiant black body 48 to both the free and forced convection airflows. As such, the exhaust gas airflow exiting the afterburner assembly 40, will be in the range of about 1,500 to 2,700 degrees Fahrenheit while the system 10 is operating at steady state.

As illustrated throughout the Figures, a hybrid convection combustion system 10 in accordance with the present disclosure comprises a draught induction assembly as generally shown at 50. The draught induction assembly 50 comprises at least one convection chamber 51 which, in at least one embodiment, is structured and disposed in an operative orientation adjacent and above an afterburner assembly 40. Of course, it is understood that in at least one embodiment, the hybrid convection combustion system 10 includes one or more convection chamber 51 disposed adjacent the combustion chamber assembly 20 itself, thereby eliminating an afterburner assembly 40 from the system 10. As illustrated best in Figure 2, in at least one embodiment, the draught induction assembly 50 comprises a plurality of convection chambers 51 disposed in a series configuration one on top of the other following an afterburner assembly 40. As with the components of the combustion chamber assembly, given the extreme operating temperatures of the hybrid convection combustion system 10, the convection chambers are constructed of steel, coated steel, stainless steel, nickel-steel alloy, or any of a variety of metal alloys and/or other engineered materials suited for operation at the extreme temperatures including, by way of example only, those materials noted above with regard to the combustion chamber assembly 20.

As shown in Figure 2, each convection chamber 51 is structured to define a convection zone 51′ therein. Further, Figure 2 illustrates that convection chamber 51 includes a sidewall 52 wherein the sidewall serves to define the boundaries of convection zone 51′. As illustrated in Figure 6, the convection chamber 51 comprises a discharge section 55, wherein the discharge section 55 is further structured to define a discharge port 56. As described above with regard to the combustion chamber cover 24, in the illustrated embodiments of the hybrid convection combustion system 10, the discharge section 55 of each convection chamber 51 comprises a substantially curved configuration which provides additional surface area for contact with the exhaust gas airflow passing therethough, as well as serving to direct the exhaust gas airflow through convection chamber 51 towards discharge port 56.

Figure 7 is illustrative of the free convection airflow and forced convection airflow through the hybrid convection combustion system 10 in accordance with the present disclosure. To begin, free convection airflow supply plenum 31 is structured to capture and direct an amount of airflow into the combustion chamber assembly 20 by means of free convection forces. Concurrently, afterburner assembly 40 is structured to receive an amount of forced convection airflow from forced convection airflow supply 32, the forced convection airflow supply passes through the air/air heat exchanger 44 prior to discharge into the hybrid convection combustion system 10 through one or more forced convection airflow discharge nozzle 46. Upon discharge from the afterburner assembly 40 into convection chamber 51, the driving force of the present hybrid convection combustion system 10 is realized. Specifically, within each convection chamber 51, the exhaust gas airflow generated by the combustion of fuel within the combustion chamber assembly 20 substantially follows the free convection airflow path as illustrated by arrows 53 in Figure 7. As illustrated in the Figure, the free convection airflow path swirls and turns along the sides of convection chamber 51 and in contact with free convection surface area 52′ as it makes its way upward and out through discharge port 56 of convection chamber 51. Also shown in Figure 7, is the forced convection airflow path 54 which, as represented in the Figure, comprises a more straightforward and higher velocity path through the draught induction assembly 50 of the hybrid convection combustion system 10. Importantly, the flow of forced convection airflow along forced convection airflow path 54 serves to induced free convection airflow into and through the hybrid convection combustion system 10. More in particular, the forced convection airflow along the forced convection airflow path 54 creates a back pressure which serves to draw ambient air in through free convection airflow supply plenum 31 at an increased rate that would not otherwise be achievable in the absence of the forced convection airflow supply 32. Therefore, by inducing an additional amount of free convection airflow into the hybrid convection combustion system 10, more efficient combustion of fuel within the combustion chamber assembly 20 is achievable. Furthermore, the introduction of the forced convection airflow into the hybrid convection combustion system 10 provides an additional source of oxygen, having an elevated temperature by way of afterburner assembly 40, to facilitate the combustion of any non-combusted fuel vapors in the exhaust gas airflow discharged from the combustion chamber assembly 20. More in particular, the combination of preheated forced convection airflow with the non-combusted fuel vapors in the exhaust gas airflow facilitates further combustion of the same thereby increasing the overall combustion efficiency realized via the hybrid convection combustion system 10 of the present disclosure.

In at least one embodiment, the hybrid convection combustion system 10 includes a fuel supply assembly 60, such as is illustrated in Figures 1 and 2. As shown, the fuel supply assembly 60 is structured to facilitate transfer of fuel to the combustion chamber assembly 20 and more specifically, onto fuel support 22, for subsequent combustion thereon. While the hybrid convection combustion system 10 of the present invention may be utilized to operate utilizing alternative fuel sources, for example, liquid fuel, natural gas, large solid fuel units, such as wood or coal. In at least one embodiment, the hybrid convection combustion system 10 in accordance with the present disclosure is structured for the combustion of discrete solid fuel units, such as, pelletized solid fuel units in the form of densified biomass fuel, corn kernels and/or similar organic feed stocks.

To facilitate handling of discrete solid fuel pellets or units, the fuel supply assembly 60 in accordance with at least one embodiment of the present disclosure includes a fuel hopper 62 which is structured to store an operative amount of the discreet solid fuel unit for immediate transfer to combustion chamber assembly 20 during operation of the hybrid convection combustion system 10. To facilitate the transfer of the solid fuel, a fuel supply port 63 is formed in the combustion chamber assembly 20 to allow for the transfer and disposition of the discreet solid fuel units onto the fuel support 22 of the combustion chamber assembly 20. Further, the fuel supply assembly 60 includes a fuel transfer assembly 64, such as is shown best in Figure 2. The fuel transfer assembly 64 is structured to operatively communicate between fuel hopper 62 and combustion chamber assembly 20 by way of fuel supply port 63. In at least one embodiment, fuel transfer assembly 64 comprises a fuel transfer member 66 which captures solid fuel from a portion of fuel hopper 62, such as at the base as shown in Figure 2, and transport an amount of the discreet solid fuel units from the fuel hopper 62 to the combustion chamber assembly 20. As shown in the illustrated embodiment of Figure 2, the fuel transfer member 66 comprises an auger 66′ which is rotated within an auger sleeve thereby causing the transfer of discreet solid fuel units from the fuel hopper 62 into combustion chamber assembly 20 through fuel supply port 63. Figure 2 further illustrates fuel supply drive assembly 68 which provides the driving force for the rotation of auger 66′, or for operation of such other fuel transfer member 66 as may be employed such as, a conveyor system.

In at least one embodiment, the fuel supply assembly 60 in accordance with the present disclosure comprises a fuel supply controller 69 which is structured to regulate the operation of the fuel supply drive assembly 68 thereby controlling the amount and rate of transfer of fuel from fuel hopper 62 to combustion chamber assembly 20 during operation of the present hybrid convection combustion system 10. In one embodiment, a sight glass 67 is employed to allow visual monitoring of the degree combustion of fuel disposed on fuel support 22 within combustion chamber assembly 20. As illustrated in the illustrative embodiment of Figure 3, the sight glass 67 is structured and disposed to allow visual monitoring of the bottom portion of the fuel support 22. More in particular, sight glass 67 is structured to monitor for the red/white hot glow of solid fuel disposed on fuel support 22 through one or more air supply port 23 disposed therethrough. Specifically, red/white hot solid fuel units visible through one or more air supply port 23 is indicative that the solid fuel present in combustion chamber assembly 20 is substantially spent and replenishment of fuel to the assembly 20 is required. As such, upon observation of red/white hot embers, via sight glass 67, fuel supply controller 69 is actuated to activate fuel supply drive assembly 68 thereby effecting a transfer of an amount of fuel from fuel hopper 62 onto fuel support 22 of combustion chamber assembly 20 so as to allow uninterrupted operation of the hybrid convection combustion system 10 in accordance with the present disclosure.

As previously indicated, in at least one embodiment, the hybrid convection combustion system 10 is structured to provide a source of heat energy sufficient to power an external system (ES) including, but not limited to, a steam engine, gas turbine, water heater, facility heating system, etc., such as is demonstrated schematically in Figure 8. Figure 6 is illustrative of one embodiment of a heat exchange assembly 70 in accordance with the present disclosure which is structured and at least partially disposed in a heat transferring relation to one or more external system (ES), for purposes of powering the same. More in particular, Figure 6 illustrates a variety of heat exchange devices which may be disposed in one or more convection chamber 51 and/or exhaust stack 57, any one or more of which may be employed to provide power an external System (ES), in the form of heat energy.

One such heat exchange device is an air/steam heat exchanger 72 which, as shown in Figure 6, is disposed immediately proximate the afterburner assembly 40 so as to be in position to receive the free and forced convection airflows having the greatest latent heat energy available for transfer to a heat exchange device. Thus, the air/steam heat exchanger 72 is structured to convert a flow of water into steam which may be utilized either directly or indirectly for powering an external system (ES).

In addition, the heat exchange assembly 70 may comprise one or more air/oil heat exchanger 73, such as is shown in Figure 6, wherein latent heat energy present in the exhaust gas airflow is transferred to a thermally conductive oil circulating therethrough. As in the case of the steam generated in the air/steam heat exchanger 72, the oil heated in the air/oil heat exchanger 73 may be utilized directly or indirectly for purposes of powering an external system (ES), as well as to a supply an amount of heat energy to the air and/or water circulating through another heat exchange device of the heat exchanger assembly.

As shown in Figure 6, the heat exchange assembly 70 may also comprise one or more air/water heat exchangers 76. The air/water heat exchanger 76 is structured to preheat an amount of water flowing therethrough via the exhaust gas airflow passing through the convection chamber 51 in which the heat exchanger is disposed. Once again, the heated fluid, i.e., water, may be utilized, at least in part, as a source of heat energy for an external system (ES), however, in at least one embodiment, the heated water produced in the air/water heat exchanger 76 will serve as a feed to an air/steam heat exchanger, such as is illustrated at 72. Figure 6 also illustrates an air/water economizer 76 disposed in the exhaust stack 57 of the hybrid convection combustion assembly 10. The air/water economizer 76 is utilized to extract remaining amounts of available latent heat energy from the exhaust gas airflow for purpose of providing an initial preheat to an amount of water which, in at least one embodiment, will serve as an input to the one or more air/water heat exchanger 76.

As will be appreciated from the foregoing, the heat exchange assembly 70 in accordance with the present disclosure provides a significant degree of flexibility to allow for the capture and transfer of a significant amount of the latent heat energy available from the exhaust gas airflow generated by the hybrid convection combustion system 10. It is noteworthy that although as shown, the heat exchanger assemblies 72, 73, 74, and 76 as well as air/air heat exchanger 44, comprise a quasi-shell and tube configuration wherein heat is transferred from the hot exhaust gasses flowing through the “shell” side to an amount of air, water, oil, of other heat transfer fluid, flowing through the “tube” side of a corresponding one of the heat exchange devices. Of course, it is well within the scope and intent of the present disclosure to employ other energy transfer technologies.

Since many modifications, variations and changes in detail can be made to the described preferred embodiment of the invention, it is intended that all matters in the foregoing description and shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense. Thus, the scope of the invention should be determined by the appended claims and their legal equivalents.

Now that the invention has been described,

What is claimed is:

  1. A hybrid convection combustion system comprising:

a combustion chamber assembly structured to facilitate combustion of solid fuel,

a fuel supply assembly disposed in a transferring relation with said combustion chamber assembly, said fuel supply assembly structured to transfer solid fuel into said combustion chamber assembly,

an airflow supply assembly structured disposed in a communicating relation with at least said combustion chamber assembly and structured to direct a free convection airflow supply thereto, and

a draught induction assembly disposed in an inductive orientation relative to said combustion chamber assembly, said draught induction assembly structured to induce a free convection airflow through at least a portion of said combustion chamber assembly.

  1. The system as recited in claim 1 wherein said combustion chamber assembly comprises a combustion chamber base having a fuel support interconnected thereto.

  2. The system as recited in claim 2 wherein said fuel support comprises a plurality of air supply ports.

  3. The system as recited in claim 3 wherein said combustion chamber assembly further comprises a fuel agitator mechanism structured and disposed to stir solid fuel disposed on said fuel support.

  4. The system as recited in claim 1 wherein said airflow supply assembly comprises a free convection airflow supply plenum disposed in a communicative relation with said combustion chamber assembly.

  5. The system as recited in claim 5 wherein said free convection airflow supply plenum is structured to direct the free convection airflow into said combustion chamber assembly.

  6. The system as recited in claim 1 wherein said draught induction assembly comprises at least one convection chamber having a convection zone, said convection zone at least partially defining a free convection airflow path for an exhaust gas airflow generated by combustion of the solid fuel units in said combustion chamber assembly.

  7. The system as recited in claim 7 wherein said at least one convection chamber comprises a free convection surface area.

  8. The system as recited in claim 8 wherein said at least one convection chamber comprises a discharge section, said discharge section having a discharge port defining a discharge flow area.

  9. The system as recited in claim 9 wherein said discharge flow area is less than said free convection surface area.

  10. The system as recited in claim 10 wherein passage of the exhaust gas airflow from said convection zone through said discharge port induces the free convection airflow through at least a portion of said combustion chamber assembly.

  11. The system as recited in claim 1 wherein said draught induction assembly comprises a plurality of convection chambers disposed in a series configuration, each of said plurality of convection chambers having a convection zone at least partially defining a free convection airflow path for an exhaust gas airflow generated by combustion of the solid fuel units in said combustion chamber assembly.

  12. The system as recited in claim 12 wherein each of said plurality of convection chambers comprises a free convection surface area.

  13. The system as recited in claim 13 wherein each of said plurality of convection chambers further comprising a discharge section having a discharge port which defines a discharge flow area, wherein each said discharge flow area is less than said free convection surface area of a corresponding one of said plurality of convection chambers.

  14. The system as recited in claim 14 wherein passage of the exhaust gas airflow from said convection zone through said discharge port of each corresponding one of said plurality of convection chambers at least partially induces the free convection airflow through at least a portion of said combustion chamber assembly.

  15. A hybrid convection combustion system comprising:

a combustion chamber assembly structured to burn a solid fuel source, wherein the solid fuel source comprises a plurality of discrete solid fuel units,

a fuel supply assembly disposed in a fuel transferring relation to said combustion chamber assembly,

an airflow supply assembly comprising a free convection airflow supply plenum disposed in an airflow transferring relation to at least said combustion chamber assembly,

said airflow supply assembly comprising a forced convection airflow supply,

an afterburner assembly disposed in an operative orientation relative to said combustion chamber assembly, said afterburner assembly comprising a forced convection airflow preheat unit,

said forced convection airflow supply structured to provide a forced convection airflow to said forced convection airflow preheat unit,

a draught induction assembly disposed in an operative orientation relative to said combustion chamber, wherein said draught induction assembly comprises a plurality of convection chambers disposed in a series configuration structured to induce a free convection airflow through at least a portion of said combustion chamber assembly, and

each of said plurality of convection chambers comprises a convection zone at least partially defining a free convection airflow path for an exhaust gas airflow from said combustion chamber assembly and a discharge section having a discharge port, wherein the exhaust gas airflow from said convection zone through said discharge port of a corresponding one of said plurality of convection chambers induces the free convection airflow through at least a portion of said combustion chamber assembly.

  1. The system as recited in claim 16 wherein said forced convection airflow preheat unit comprises an air/air heat exchanger.

  2. The system as recited in claim 17 wherein said air/air heat exchanger is structured to transfer an amount of exhaust heat energy from the exhaust gas airflow to the forced convection airflow supplied thereto, thereby preheating the forced convection airflow.

  3. The system as recited in claim 18 wherein said air/air heat exchanger further comprises at least one forced convection airflow discharge nozzle structured to discharge at least a portion of the preheated forced convection airflow therefrom.

  4. The system as recited in claim 19 wherein said at least one forced convection airflow discharge nozzle is structured and disposed to discharge at least said portion of the preheated forced convection airflow into said convection zone of at least one of said plurality of convection chambers.

  5. The system as recited in claim 19 wherein said air/air heat exchanger further comprises a plurality of forced convection airflow discharge nozzles, each of said plurality of forced convection airflow discharge nozzles structured and disposed to discharge at least a portion of the preheated forced convection airflow into said convection zone of at least one of said plurality of convection chambers.

  6. The system as recited in claim 17 wherein said forced convection airflow preheat unit further comprises a radiant black body structured to absorb an amount of exhaust heat energy from the exhaust gas airflow.

  7. The system as recited in claim 22 wherein said radiant black body is further structured to transfer an amount of radiant heat energy to said air/air heat exchanger.

  8. The system as recited in claim 16 wherein said forced convection airflow supply comprises a centrifugal blower.

  9. The system as recited in claim 24 wherein said forced convection airflow supply comprises an air/fuel sensor structured and disposed to monitor a concentration of at least one component in the exhaust gas airflow.

  10. The system as recited in claim 25 wherein said airflow supply assembly further comprises an air/fuel controller disposed in an operative relationship relative to said air/fuel sensor and said centrifugal blower.

  11. The system as recited in claim 26 wherein said air/fuel controller is structured to regulate an amount of the forced convection airflow from said centrifugal blower to said afterburner assembly based at least partially on the concentration of the at least one component in the exhaust gas airflow.

  12. A hybrid convection combustion system comprising:

a combustion chamber assembly structured to burn a solid fuel source, wherein the solid fuel source comprises a plurality of discrete solid fuel units,

a fuel supply assembly structured to transfer the plurality of discrete solid fuel units to said combustion chamber assembly,

said combustion chamber assembly comprises a fuel agitator mechanism structured and disposed to stir the discrete solid fuel units to minimize agglomeration of the discrete solid fuel units disposed in said combustion chamber assembly,

said combustion chamber comprising a combustion chamber discharge port structured to discharge an exhaust gas airflow generated by combustion of the solid fuel units in said combustion chamber assembly,

an airflow supply assembly comprising a free convection airflow supply plenum disposed in an airflow transferring relation to at least said combustion chamber assembly,

disposed in a communicating relation to at least said combustion chamber assembly,

an afterburner assembly disposed in an operative orientation relative to said combustion chamber assembly, said afterburner assembly comprising an air/air heat exchanger and a radiant black body,

said airflow supply assembly further comprising a forced convection airflow supply, said forced convection airflow supply being disposed in a communicative configuration with at least said air/air heat exchanger,

a draught induction assembly disposed in an operative orientation relative to said combustion chamber, wherein said draught induction assembly comprises a plurality of convection chambers disposed in a series configuration, each of said plurality of convection chambers comprising a convection zone structured to receive at least the exhaust gas airflow,

said plurality of convection chambers further structured to induce the free convection airflow through at least a portion of said combustion chamber assembly, and

said air/air heat exchanger and said radiant black body disposed in one of said plurality of convection chambers in a contacting relation with the exhaust gas airflow therethrough, wherein said air/air heat exchanger is structured to transfer an amount of exhaust heat energy from the exhaust gas airflow to the forced convection airflow supplied thereto, thereby preheating the forced convection airflow, and

a heat exchange assembly disposed in an operative orientation relative to an external system and structured to provide an operative amount of heat energy to the external system.

  1. The system as recited in claim 28 wherein said combustion chamber further comprises a combustion chamber discharge screen structured to ignite an amount of non-combusted fuel present in the exhaust gas airflow.

  2. The system as recited in claim 28 wherein said combustion chamber further comprises a combustion chamber discharge screen structured to retain the plurality of discrete solid fuel units in said combustion chamber.

  3. The system as recited in claim 28 wherein said combustion chamber further comprises a sight glass structured to measure a degree of combustion of the plurality of discrete solid fuel units disposed in said combustion chamber.

  4. The system as recited in claim 31 wherein said fuel supply assembly further comprises a fuel supply controller disposed in an operative relation with said sight glass, said fuel supply controller structured to transfer a predetermined amount of discrete solid fuel units to said combustion chamber assembly based on said degree of combustion of the plurality of discrete solid fuel units disposed in said combustion chamber.

ABSTRACT OF THE DISCLOSURE

A hybrid convection combustion system comprises a combustion chamber assembly having an airflow supply assembly structured and disposed to provide at least a free convection airflow supply to the combustion chamber assembly to provide oxygen needed for the combustion of a fuel supply therein. The system also includes a draught induction assembly to facilitate the supply of free convection airflow into the combustion chamber, and a forced convection airflow supply to provide a forced convection airflow to the system, in at least one instance, via an afterburner assembly disposed downstream of the combustion chamber assembly. A fuel supply assembly is provided to allow for continuation operation of the hybrid convection combustion system, and a heat exchange assembly may be included to facilitate the transfer of an amount of heat energy for powering an external system, such as, but not limited to, a steam engine, gas turbine, water heater, facility heating system, etc.

This external combustion chamber burns “feed corn”. And is the main heat source for the flash steam heat exchanger which operates the four cycle steam engine.

This cornburner unit has remarkable performance. And uses only corn to generate these flames.

In this example the corn burner is “manual feed”. However we have also experimented with fully automated units. The “truth table of fuzzy logic control” will vary between “top feed and bottom fuel” feed burners. fortunately the fiber optic sensor is unaffected by the access door. All automated features are omitted on this model including the “agitator”. Due to space constraints of the complete system design. But in the automated units that we have worked with, the fuzzy logic schedule of fueling is always superior to the “on delay, off delay” of conventional timer circuits. Since fuzzy logic type of methodology will not to pack the combustion chamber full of corn due to flame out. The “if and then” scenario is determined by the fiber optic sensor. It will continually adjust timing sequences to match current environmental conditions (humidity, water content in the corn, etc.). This is generally superior to simple timing sequences. Even with these improvements the burner will operate with a “ebb and flood over time” type of affect with respect to the fire output. As is the case with most solid fuel burners. But it should be noted that a larger combustion chamber and unit, will lesson this “ebb and flood effect”. The design methods that we follow allow “never seen before performance” in corn burners. And the units that we build, carry this performance into larger sizes.

bpic3

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SAFE COMPONENT SELECTION—-When selecting a component, the total system design must be considered to ensure safe, trouble free performance. Component function, materials compatibility, adequate ratings, proper installation, operation, and maintenance are the responsibility of the system designer and user.

General feedback info@flashsteam.com.

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