Patent Application
20100285413
1. Field of the Invention
The present invention relates to fuel combustion processes and apparatus, and specifically to apparatus for providing uniformly volume distributed combustion and related methods.
2. Description of Related Art
It was arguably not until the late 1970s and early 1980s, as a result of the first and the second energy crisis, that research and development activities began to seriously focus on improving energy efficiency. Similarly, it has only been since until after such time period that industry has truly recognized the need for eliminating noxious pollutants such as nitrogen oxides, mostly due to concerns over human health and concern for the environment. As a result, although uniformly distributed (flameless) combustion was discovered circa 1911, it was not until recently that uniformly distributed combustion (flameless oxidation) has become a focus of industrial research.
In flameless combustion, ignition occurs and progresses with generally no visible or audible signs of a flame usually associated with burning. As early as 1989, it was found that combustion in a furnace could be sustained even in an extremely low concentration of oxygen, if the combustion air was sufficiently preheated. Particularly, during experiments with a self-recuperative burner, it was observed that at furnace combustion temperatures of about 1000° C. and an air preheat temperature of about 650° C., no flame was visible and no ultraviolet signal was detected. Nevertheless, the fuel was substantially combusted “burnt,” and the carbon monoxide content and nitric oxide of the exhaust was found to be extremely low.
Conventionally, to initiate flameless combustion, preheated oxidizing air and fuel gas is fed into a combustion chamber at relatively high injection speeds. The geometry of the combustion chamber, as well as the injection speed of the fuel-air mixture, create large internal recirculations of the combustion mixture. Once the recirculations are sufficient, the combustion becomes distributed throughout the volume of the combustion chamber and the flame will no longer be visible. Further, as an application of such principle, nitric oxide emission can be reduced by dilution of the combustion air with recirculated burned gas in the furnace. Dilution of the combustion air can reduce the oxygen content of the oxidizer, which decreases temperature fluctuations in the combustion chamber as well as the mean temperature, hence, a resultantly low amount of nitric oxide emission.
Recognizing the potential benefits of flameless combustion, the industry has attempted to develop various types of combustion chambers that support flameless combustion. For example, U.S. Pat. No. 6,796,789 by Gibson et al. titled Method to Facilitate Flameless Combustion Absent Catalyst or High-Temperature Oxidant” describes and oval-shaped combustion chamber configured to recirculate fuel gas with flue gas and combustible air. U.S. Pat. No. 5,340,020 by Manus et al. Titled “Method and Apparatus for Generating Heat by Flameless Combustion of a Fuel in a Gas Flow” describes a combustion apparatus, which utilizes a catalyst for producing the flameless combustion.
U.S. Pat. No. 5,839,270 by Jirnov et al., titled “Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression of Air” describes a particularly effective combustion chamber originally configured for use with the sliding-blade rotary air-heat engine. The Jirnov “vortex” combustion combined with a straight-flow precombustion chamber successfully solved problems associated with operating on multi-fuels with a high completeness of combustion over the wide range of the coefficient of air redundance, while producing a substantial drop in toxicity of the exhaust gases. The combustor was also characterized by providing a simplified combustor design and ease of fabricating, high thermal and volumetric efficiency, while being able to employ a variety of types of combustible hydrocarbon gas or liquid fuels. The vortex combustor provided a vortex chamber positioned at the tube inlet and ejectors with feedback loops positioned along the length of the heat transfer section. This enabled the results to he increased by inducing a swirl flow and intensive recirculation of fluid all along the length of the heat transfer section. A precombustion chamber was provided to form a super-rich fuel and air mixture, ignition, partial combustion and pyrolyzation of heavy and low grade fuels. In operation with the Jirnov engine, prior to entering the precombustion chamber the combustion air was first preheated by exhaust gases. Upon entry, heating coils in the precombustion chamber then further heated the air and heated fuel also injected into the precombustion chamber prior to entry into the main vortex combustion chamber. The entry of the fuel-air mixture into the main vortex combustion chamber was such that a very large swirl was created which helped ensure proper mixture and a substantially uniform combustion within the combustion chamber.
In recent years, due to the cost of fuel and due to concern for the environment, there has been a high interest in the use of biofuels. Biofuels can include solid, liquid, or gas fuel derived from recently expired biological material. Biofuel can be produced from theoretically any biological carbon source, the most common of which include plants and plant-derived materials. The biofuel industry is expanding in Europe, Asia and the Americas. The most common use for biofuels is as liquid fuels for automotive transport. There is also, however, a desire in industry to use biofuel to generate steam at and/or electricity. Biodiesel is the most common biofuel in Europe, and is becoming more popular in Asia and America. Biodiesel can be produced from oils or fats, for example, using transesterification of vegetable oil, and forms into a liquid similar in composition to petroleum diesel.
Biodiesel production can result in glycerol (glycerin) as a by-product; for example, at one part glycerol for every 10 parts biodiesel. This has resulted in a glut in the market for glycerol. Accordingly, rather than being able to sell the glycerol, many companies have to pay for its disposal. Sources indicate that the 2006 levels of glycerol production were at about 350,000 tons per annum in the USA, and 600,000 tons per annum in Europe. Sources further indicate that such levels will only increase as biodiesel becomes more popular as a homegrown energy source and as Europe implements EU directive 2003/30/EC, which requires replacement of 5.75% of petroleum fuels with biofuel, across all member states by 2010. Recognized, therefore, by the inventor is the need for and apparatus and methods of economically disposing of glycerin or other in an environmentally friendly and energy efficient manner.
Also recognized by the inventor is that, although considered a waste product of biodiesel fuel production, waste fuels, such as glycerin, have significant energy delivery potential. Glycerin, however, along with some other forms of waste/biofuels, have characteristics which must be overcome in order to employ them as a fuel source. For example, various forms of glycerol remain a solid below approximately 18° C. (64.4° F.), have a flashpoint of 199° C. (390.2° F.), and have an autoignition point of 412° C. (773.6° F.). In contrast, petroleum diesel is a liquid at room temperature and has a typical flashpoint of between approximately 52° C. (126° F.) and 96° C. (204° F.) and an autoignition point of approximately 210° C. (410° F.)—nearly half that of glycerin. Recognized, therefore, by the inventor is the need for an apparatus and methods for economically and efficiently burning such heavily viscous waste/biofuels in a combustion chamber to produce an exhaust which can be utilized as an energy source. Further recognized by the inventor is the need for such apparatus and methods which can provide flameless combustion to thereby decrease nitric oxide emissions and increase energy efficiency.
In view of the foregoing, various embodiments of the present invention advantageously provide an apparatus and methods for economically and efficiently burning viscous biofuels in a combustion chamber to produce an exhaust which can be utilized as an energy source. Various embodiments of the present invention also advantageously provide an apparatus and methods which include a vortex combustion chamber configured to provide flameless combustion to thereby decrease nitric oxide emissions and increase energy efficiency. Various embodiments of the present invention provide an apparatus and methods which improve upon the Jirnov vortex combustion chamber and precombustion chamber described in U.S. Pat. No. 5,839,270 by Jirnov et al., titled “Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression of Air,” to more efficiently accommodate use of the more viscous fuels, such as glycerol.
Particularly, various embodiments of the present invention advantageously provide an apparatus for providing flameless combustion of a viscous fuel. According to an embodiment of the present invention, the apparatus includes a precombustion chamber adapted to heat and at least partially combust a primary fuel and a main combustion chamber adapted to combust the primary fuel. The precombustion chamber can include a cylindrical housing having an enclosed proximal end portion, an open distal end portion, and a substantially hollow main body extending therebetween and substantially enclosing a precombustion chamber cavity. The precombustion chamber can include at least one air injection inlet port extending through the body of the cylindrical outer housing and positioned to inject or otherwise deliver combustion air into the precombustion chamber and positioned to help induce a first stage vortex in the main body portion of the housing of the precombustion chamber. The precombustion chamber can also include 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, an igniter positioned to ignite the igniter fuel, 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.
The combustion stabilizer includes 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 includes a large diameter sidewall spaced radially inward from the precombustion chamber housing to define an annulus therebetween and includes 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 is in fluid communication with the combustion stabilizer main body and has a small diameter sidewall having a diameter substantially smaller than the large diameter sidewall of the main body. The distal end portion further includes 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.
The main combustion chamber includes an, e.g., cylindrical or elliptical 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 can include an inner main body diameter and can have a main body axial length extending at least approximately twice the main body diameter. The main body axial length can have 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. The main combustion chamber can also include a combination precombustion chamber exhaust outlet and main combustion chamber fuel-air mixture inlet (hereinafter “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. The exhaust-inlet is positioned to receive the at least partially combusted primary fuel from the precombustion chamber and positioned (e.g., tangentially) to induce a second stage vortex within the main body of the main combustion chamber housing.
The main combustion chamber also includes a combustion exhaust tube or other form of conduit (e.g., Venture form) 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. The combustion exhaust tube or conduit includes 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 extends 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.
According to another embodiment of the present invention, an apparatus for providing flameless combustion of a fuel includes a main combustion chamber adapted to combust a primary fuel. The main combustion chamber includes 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 has an inner main body diameter and a main body axial length. An exhaust-inlet extends through the main body of the main combustion chamber housing at an inlet location. The exhaust-inlet is positioned to receive at least partially combusted primary fuel from a precombustion chamber and is positioned to help induce a vortex within the main body of the main combustion chamber housing. According to a preferred configuration, the main body axial length extends distally from the inlet location a distance value approximately equal to or greater than that of the inner main body diameter. Particularly, 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 to exit based upon one or more fuel performance characteristics of the particular type/configuration of the primary fuel.
The main combustion chamber can further include 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. The combustion exhaust conduit can include 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. Specifically, the distal end portion of the combustion exhaust tube can extend 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. According to this configuration, the axial spacing of the distal end portion of the combustion exhaust conduit from the distal end portion of the main combustion chamber housing has a value approximately equal to or greater than that of at least one exhaust conduit main body diameter inner diameter.
Various embodiments of the present invention also provide methods of providing flameless combustion of a viscous fuel. According to an embodiment of the present invention, such a method can include the steps of inducing a first stage vortex in a primary fuel-air mixture within a main body of a precombustion chamber of a flameless combustor, receiving within a main body of a main combustion chamber of the flameless combustor the primary fuel-air mixture having a first stage vortex induced state, 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. According to a preferred configuration, the step of inducing can include expelling the primary fuel-air mixture tangentially into the main combustion chamber cavity through a precombustion chamber exhaust outlet. According to this configuration, the diameter of the first stage vortex is substantially smaller than a diameter of the second stage vortex formed within the main combustion chamber.
The method can also include the steps of interfacing with the main combustion chamber, a 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, 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.
According to another embodiment of the present invention, a method of providing flameless combustion of a viscous fuel can include the steps of providing a main vortex combustion chamber of a flameless combustor having a main body substantially enclosing a 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 a vortex within the main combustion chamber cavity to enhance flameless oxidation of a primary fuel. The method can also include the step of providing a combustion exhaust conduit within and axially coincident with the main combustion chamber cavity. The combustion exhaust conduit can have 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. The 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 can further have a value approximately equal to or greater than that of at least one exhaust conduit main body inner diameter.
The method can further include the step of injecting the primary fuel into the main combustion chamber cavity through a combination precombustion chamber exhaust outlet-main combustion chamber inlet (“exhaust-inlet”). The exhaust-inlet is axially spaced apart from the combustion exhaust conduit inlet 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. The method can further include the step of preselecting the value of the axial separation between the exhaust-inlet and the combustion exhaust conduit inlet to provide the sufficient pyrolyzed fuel travel distance from the exhaust-inlet within the main combustion chamber cavity responsive to one or more fuel performance characteristics of the glycerol fuel.
Various embodiments of the present invention also provide a precombustion chamber, and a vortex combustion chamber which is an improvement over the Jirnov vortex combustion chamber and precombustion chamber. Various embodiments of the present invention provide, for example, a vortex combustor including a main combustion chamber connected or otherwise interfaced with a precombustion chamber, which successfully solves problems associated with operating on highly viscous fuels with a high completeness of combustion over the wide range of the coefficient of air redundance and produces a substantial reduction in toxicity of exhaust gases. Various embodiments of the present invention provide high thermal and volumetric efficiency, may employ a variety of types of viscous and non-viscous combustible hydrocarbon fuels, have reduced quantities of environmentally damaging emissions, and have a simplified combustor design and ease of fabricating, which is economical to manufacture in mass production and is inexpensive to operate, service, and repair.
Various embodiments of the present invention provide a vortex chamber positioned at the tube inlet and provide feedback loops positioned along the length of the heat transfer section, which enable the resulting fuel combustion efficiency to be increased by inducing a swirl flow and intensive recirculation of fluid along the length of the heat transfer section. Such improved fuel efficiency can advantageously reduce environmentally damaging emissions. Further, such apparatus may be used in converting thermal energy into electric power, can be used in generating steam, and/or can be utilized as part of a transportation engine with high thermal efficiency.
So that the manner in which the features and advantages of the invention, as well as others which will become apparent, may be understood in more detail, a more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings, which form a part of this specification. It is to be noted, however, that the drawings illustrate only various embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it may include other effective embodiments as well.
The present invention will now be described more fully hereinafter with reference to the accompanying drawings, which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.
More specifically, as perhaps best illustrated in
As shown in
According to an embodiment of the precombustion chamber 33, a funnel-shaped flame tube 61 is secured to the open end of the outer housing 41 by a radial flange 63 and has a hollow cylindrical side wall portion 65 received within the open end of the outer housing 41, a conical side wall portion 67, and a reduced diameter neck portion 69 at one end. The radial flange 63 is secured between the open end of the outer housing 41 and a conical flanged fitting 71 on the outer housing of the vortex combustion chamber 35. The conical side wall portion 67 of the flame tube 61 is received within the conical flanged fitting 71, and the reduced diameter neck portion 69 is connected with a tubular channel 73 disposed tangential to the periphery of the main vortex combustion chamber 35. The exterior of the cylindrical side wall portion 65 is spaced radially inward from the interior of the outer housing 41 and the conical side wall portion 67; and the reduced neck portion 69 is spaced radially inward from the interior of the conical flanged fitting 71 to define an annulus 75 therebetween. Further, a plurality of passageways 77 extend through the radial flange 63 to allow communication through the annulus 75.
According to an embodiment of the present invention, the combustion stabilizer 49 is provided with one or more primary fuel injectors/nozzles 81 for injecting a primary fuel, a secondary fuel injector(s)/nozzle(s) 83 for injecting a secondary or ignition fuel positioned to ignite the primary fuel, and a fuel igniter or spark plug 85. The secondary fuel injector 83 can provide fuel, e.g., propane, etc., to pre-heat the primary fuel, particularly if a heavy or viscous primary fuel is used or if the ambient temperature is below that required. According to a preferred configuration, the nozzles 81, 83, and the igniter 85 are located in the top cover portion 87 of the precombustion chamber 33. A portion of air from the general airflow drawn or injected through opening 45, is further drawn or injected into the combustion stabilizer 49 through air inlets 57 to create an air-fuel mixture near the secondary fuel injector 83 and the spark plug 85.
According to another embodiment of the present invention, as perhaps best illustrated in
According to an embodiment of the present invention, in operation, fuel is delivered to the precombustion chamber 33 through single or multiple primary fuel injector(s)/nozzle(s) 81 via a fuel supply system 37. When multiple nozzles 81 are utilized, the fuel supply system 37 can beneficially allow the apparatus 31 to oxidize different types of liquid or gaseous fuels emanating from independent sources, separately or simultaneously. The fuel nozzle or nozzles 81 can be interfaced with a compressed air/gas supply, either directly or indirectly via taps (not shown) in the fuel supply lines 39, to help breakup the liquid fuel jet expelled from the fuel nozzle(s) 81 and provide a minimal size of fuel droplets, i.e., form an aerosol or colloid, or at least a suspension. The resulting minimal size droplets can have a reduced (short) time of vaporization, and thus, reduced combustion time. This can be especially beneficial when combustion for waste fuels, such as Glycerin, is desired.
As noted above, combustion airflow, for example, provided by a cooling air (gas/fluid) supply system 36, is provided through the one or more air inlets 45 extending through sidewall 47. The required airflow rate and/or oxygen content of the combustion air can be determined and set based on the ratios of momentum and mass for a given liquid fuel flow rate to provide maximum instability of the air-fuel flow and efficient precombustion. Particularly, the combined airflow rate of the air entering/exiting the inlet(s) 45 and mass flow of primary fuel entering the precombustion chamber 33 can have a ratio between 20:1 to 40:1, with a preferred ratio of approximately 30:1; and the combustion gas (e.g., air) to mass flow of fuel can have a ratio of preferably between 30:1 to 50:1, with a more preferred ratio of approximately 40:1. Such fuel injection configuration can provide for the shortest breakup length and breakup time inside of the precombustion chamber 33. Further, the precombustion chamber 33 can have an axial length to sidewall/main body cross-sectional diameter ratio of preferably between 2:1 to 4:1, with a more preferred ratio of approximately 3:1 to ensure sufficient precombustion prior to entering the main vortex combustion chamber 35. Consequently, according to embodiments of the apparatus 31, the combustion process is complete and occurs downstream inside of the main chamber 35 without flame on the exit. The absence of a flame on exit can beneficially extend the use of apparatus 31/vortex combustion chamber 35 for many applications known to those skilled in the art, including for turbines, engines, and heaters.
As perhaps best shown in
The combustion management/fuel-gas supply system 200 can also include various sensors, known to those skilled in the art, including, for example, a mass flow/density/momentum meter or meters 211 interfaced with the fuel system 37 to monitor fuel characteristics of the primary fuel; a combustion air pressure sensor 213 positioned to monitor air pressure of the air entering air inlet or inlets 45; a combustion air oxygen content sensor 215 positioned to monitor the oxygen content of the combustion air; and an exhaust gas temperature (EGT) probe 217 positioned to sense the temperature of the exhaust gases emanating from combustion exhaust tube or conduit 115 (see
The combustion management/fuel-gas supply system 200 can further include various control devices including, for example, a combustion air/gas pump, injector, or valve 221 for adjusting combustion air pressure; a primary fuel pump or valve 223 for managing fuel pressure of the primary fuel; a secondary fuel control pump or valve 225 for managing the amount of secondary fuel used to help pre-combust the primary fuel in the combustion stabilizer 49 of the precombustion chamber 33; an ignition circuit 227 for igniting the secondary fuel; and an fuel-air pump 229 for aerating the primary fuel. Note, it should be understood by one skilled in the art that the above described control devices can further include internal controllers within each device.
The combustion management/fuel-gas supply system 200 can also include a user interface 207 as known to those skilled in the art, to provide a user access to manipulate or access software and database records, and combustion management program product 231 stored in memory 205 of the controller 201 to provide combustion management. The program product 231, according to an embodiment of the combustion management/fuel-gas supply systems 200 includes instructions that when executed by the controller 201 cause the controller to perform various operations to include gathering or otherwise collecting real-time data from sensors 211, 213, 215, and 217, to perform real-time combustion management to include, for example: adjusting fuel pressure of the primary fuel responsive to output requirements of a supported system (e.g., turbine, engine, etc.); adjusting combustion air pressure/rate to maximize instability of the air-fuel flow and/or adjusting aeration of the fuel responsive to the density or mass flow of the primary fuel to enhance combustibility of the fuel; and applying or discontinuing application of the secondary fuel responsive to the exhaust gas temperature to help ensure substantially complete oxidation of the primary fuel prior to exit from the main combustion chamber exhaust conduit 115, just to name a few.
Note, the combustion management program product 231 can be in the form of microcode, programs, routines, and symbolic languages that provide a specific set for sets of ordered operations that control the functioning of the hardware and direct its operation, as known and understood by those skilled in the art. Note also, the combustion management program product 231, according to an embodiment of the present invention, need not reside in its entirety in volatile memory, but can be selectively loaded, as necessary, according to various methodologies as known and understood by those skilled in the art.
As shown in
According to various embodiments of the present invention, the main body 101 of the main combustion chamber 35 preferably has a cylindrical form (
According to embodiments of the present invention, the main combustion chamber 35 further includes a combustion exhaust tube or conduit 115, which serves as the outlet or exhaust pipe for the near-axis zone of the main vortex combustion chamber 35. The exhaust conduit 115 can be configured either as a separate unit, or as a tubular extension of collector member 107, which extends distally therefrom through a central opening 117 in the inner top wall 105. The combustion exhaust conduit 115 and central opening 117 together form an annulus 119 therebetween. The combustion exhaust conduit 115 can have various shapes to include cylindrical (see, e.g.,
According to an embodiment of the present invention, the combustion exhaust tube or conduit 115 is positioned and extends within the main combustion chamber cavity 109 to a location, for example, at least beyond the midpoint of the main body 101 of the combustion chamber 35, but preferably adjacent the bottom end wall 103 spaced apart therefrom at an axial distance equivalent to at least the value of the inner diameter of a distal/inlet portion 11.6 of the combustion exhaust conduit 115. When heavily viscous fuel such as glycerol is used, which requires additional time to oxidize, the combustion exhaust tube or conduit 115 can have a axial offset distance from the inner surface of the bottom end wall 103 to combustion exhaust tube cross-sectional inner diameter ratio of between 1:1 to 3:1, with a preferred ratio of approximately 2:1. As perhaps best shown in
Accordingly, for the main combustion chamber 35 configuration having a main combustion chamber cavity 109, combustion exhaust conduit 115, and precombustion chamber 33 positioned, for example, as shown in
According to an embodiment of the present invention, an inner bottom wall 121 and an inner top wall 123 are secured within the outer bottom wall 103 and outer top wall 105, respectively, in a spaced apart relation to define a flow passageway 125 therebetween. One or more swirl nozzles 127 are connected to or otherwise interfaced with the passageway 125 between the outer bottom wall 103 and inner bottom wall 121. A plurality of passageways 129 extend longitudinally through the side wall of the cylindrical main body 101 of the combustion chamber housing to allow communication with the flow passageways 131. The passageways 125, 129, and 131, form an isolated fuel-air recirculation channel which passes around the interior of the main combustion chamber 35.
According to an embodiment of the present invention, a bypass conduit 133 connects the radial passageways 131 to a compressed airflow entering the recirculation system of combustion chamber 35 via an external supply conduit 135. According to a preferred configuration, the recirculation system via bypass conduit 133 and external supply conduit 135 receives both cooling air and another cooling fluid (e.g., water) to enhance cooling the main combustion chamber 35.
As perhaps best shown in
The liner 141 includes a cylindrical side wall 145 joined tangentially to the tubular channel 73 (see, e.g.,
The cool and moist air (identified above) can be directed through the bypass conduit 133 and the radial passageways 131, and onto the annular raised lip ring 151, which serves as a fuel-air ejector ring, and which causes a Ventura effect to return trapped fuel film through the recirculation channel 125, 129, 131 and swirl nozzle(s) 127 back into the chamber combustion zone. The swirl nozzle(s) 127 are configured to swirl the recirculated fuel-air-water mixture flowing through the recirculation channels 125, 129, 131, as it enters the interior of the main combustion chamber 35. Because the swirl nozzle or nozzles 127 are located in the near-axis zone of the vortex combustion chamber 35 where the lowest pressure tends to occur, the fuel-air ejector ring 151 is subjected to a substantial pressure drop and its operation is thus intensified.
To initiate combustion of a primary fuel (e.g., glycerin), in the embodiment shown in
Similarly, in the embodiment shown in
As perhaps best shown in
The air received through air/gas inlet(s) 45 can also flow through the annulus 53, 75, and passageways 77 between the flame tube 61 and the housing 41 of the precombustion chamber 33 and conical flanged fitting 71 of the vortex combustion chamber 35 and the annulus 147 surrounding the perforated liner 141, to thereby cool the flame tube 61, perforated liner 141 and cylindrical side wall 145. According to an embodiment of the present invention illustrated in
It is perhaps best shown in
In the combustion process, a portion of the fuel, not participating in mixing and combustion, moistens the inner walls of the liner 141 in the vortex combustion chamber 35, and in the form of a migrating film of unmixed and uncombusted fuel, migrates to the lower portion of the chamber 35, at least in part, due to gravity, and is captured at the inward side of the annular raised lip ejector ring 151. A portion of the preferably cool and moist air is directed through the conduit 135, the bypass conduit 133, and the radial passageways 131, onto the outward side of the annular raised lip ejector ring 151, which causes a venturi effect, which further functions to return the trapped unmixed and uncombusted fuel as a fuel-air mixture through the recirculation channels 125, 129, and swirl nozzle 127 back into the chamber combustion zone. The swirl nozzle 127 swirls the recirculated fuel-air mixture flowing through the recirculation channels 125, 129, as it enters the cavity 109 of the vortex combustion chamber 35.
Efficient and reliable cooling of the combustion chamber 35 can be provided by air flows through the annulus 75 and 147 and by the flowing of part of the cooling air (preferably with a certain amount of water) through recirculation channels 125, 129. As noted previously, because the swirl nozzle or nozzles 127 are located in the near-axis zone of the vortex combustion chamber where re-refraction occurs, in such configuration, the fuel-air ejector ring 151 is subjected to a substantial pressure drop, and its operation is intensified. The combined total amount of air arriving at the main vortex chamber combustion zone through air inlet ports 57, tubular channel 73, annulus 75, and bypass conduit 133, form a lean fuel-air mixture for after-burning.
Beneficially, the various combinations of the structural and operational features of embodiments of the main vortex combustion chamber 35 provide a small combustion chamber capable of burning a variety of fuels with high energy efficiency and low toxicity of the products, including low amounts of NOx. According to various embodiments of the present invention, the process of combustion, managed by controlling the supply of a super-rich air-fuel mixture in the precombustion chamber 31, supply of a lean mixture in the vortex chamber cavity 109, and the introduction of a certain amount of water into the combustion zone, can help ensure a sufficiently low temperature of combustion, which is typically the significant, if not dominant, factor in decreasing the NOx content in exhaust gases, but that is also sufficiently high enough to prevent escape of other unwanted or toxic exhaust gases.
Embodiments of the present invention also include methods for providing flameless combustion of a fuel, in general, and for a heavy viscous waste fuel, such as glycerol, in particular. According to an embodiment of the present invention, such a method can include forming a combustor apparatus 31 including a precombustion chamber 33 and a main combustion chamber 35 (see, e.g.,
As perhaps best shown in
As perhaps best shown in
As perhaps best shown in
This patent application is related to U.S. Provisional Application No. 61/052,076 by Anatoli Borissov, filed May 9, 2008, titled “Apparatus And Methods For Providing Uniformly Volume Distributed Combustion of Fuel and U.S. Pat. No. 5,839,270 by Jirnov et al., titled “Sliding-Blade Rotary Air-Heat Engine with Isothermal Compression of Air,” incorporated by reference in its entirety.
In the drawings and specification, there have been disclosed a typical preferred embodiment of the invention, and although specific terms are employed, the terms are used in a descriptive sense only and not for purposes of limitation. The invention has been described in considerable detail with specific reference to these illustrated embodiments. It will be apparent, however, that various modifications and changes can be made within the spirit and scope of the invention as described in the foregoing specification.
This non-provisional application claims priority to and the benefit of U.S. Patent Application No. 61/176,006, filed May 6, 2009, titled “Apparatus and Methods for Providing Uniformly Volume Distributed Combustion of Fuel,” incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61176006 | May 2009 | US |
